mirror of https://github.com/torvalds/linux.git
875 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Christy Lee
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496f332404 |
Only output backtracking information in log level 2
Backtracking information is very verbose, don't print it in log level 1 to improve readability. Signed-off-by: Christy Lee <christylee@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211216213358.3374427-4-christylee@fb.com |
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Christy Lee
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2e5766483c |
bpf: Right align verifier states in verifier logs.
Make the verifier logs more readable, print the verifier states on the corresponding instruction line. If the previous line was not a bpf instruction, then print the verifier states on its own line. Before: Validating test_pkt_access_subprog3() func#3... 86: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R10=fp0 ; int test_pkt_access_subprog3(int val, struct __sk_buff *skb) 86: (bf) r6 = r2 87: R2=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) 87: (bc) w7 = w1 88: R1=invP(id=0) R7_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ; return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123)); 88: (bf) r1 = r6 89: R1_w=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) 89: (85) call pc+9 Func#4 is global and valid. Skipping. 90: R0_w=invP(id=0) 90: (bc) w8 = w0 91: R0_w=invP(id=0) R8_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ; return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123)); 91: (b7) r1 = 123 92: R1_w=invP123 92: (85) call pc+65 Func#5 is global and valid. Skipping. 93: R0=invP(id=0) After: 86: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R10=fp0 ; int test_pkt_access_subprog3(int val, struct __sk_buff *skb) 86: (bf) r6 = r2 ; R2=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) 87: (bc) w7 = w1 ; R1=invP(id=0) R7_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ; return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123)); 88: (bf) r1 = r6 ; R1_w=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) 89: (85) call pc+9 Func#4 is global and valid. Skipping. 90: R0_w=invP(id=0) 90: (bc) w8 = w0 ; R0_w=invP(id=0) R8_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ; return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123)); 91: (b7) r1 = 123 ; R1_w=invP123 92: (85) call pc+65 Func#5 is global and valid. Skipping. 93: R0=invP(id=0) Signed-off-by: Christy Lee <christylee@fb.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Christy Lee
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0f55f9ed21 |
bpf: Only print scratched registers and stack slots to verifier logs.
When printing verifier state for any log level, print full verifier state only on function calls or on errors. Otherwise, only print the registers and stack slots that were accessed. Log size differences: verif_scale_loop6 before: 234566564 verif_scale_loop6 after: 72143943 69% size reduction kfree_skb before: 166406 kfree_skb after: 55386 69% size reduction Before: 156: (61) r0 = *(u32 *)(r1 +0) 157: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=ctx(id=0,off=0,imm=0) R2_w=invP0 R10=fp0 fp-8_w=00000000 fp-16_w=00\ 000000 fp-24_w=00000000 fp-32_w=00000000 fp-40_w=00000000 fp-48_w=00000000 fp-56_w=00000000 fp-64_w=00000000 fp-72_w=00000000 fp-80_w=00000\ 000 fp-88_w=00000000 fp-96_w=00000000 fp-104_w=00000000 fp-112_w=00000000 fp-120_w=00000000 fp-128_w=00000000 fp-136_w=00000000 fp-144_w=00\ 000000 fp-152_w=00000000 fp-160_w=00000000 fp-168_w=00000000 fp-176_w=00000000 fp-184_w=00000000 fp-192_w=00000000 fp-200_w=00000000 fp-208\ _w=00000000 fp-216_w=00000000 fp-224_w=00000000 fp-232_w=00000000 fp-240_w=00000000 fp-248_w=00000000 fp-256_w=00000000 fp-264_w=00000000 f\ p-272_w=00000000 fp-280_w=00000000 fp-288_w=00000000 fp-296_w=00000000 fp-304_w=00000000 fp-312_w=00000000 fp-320_w=00000000 fp-328_w=00000\ 000 fp-336_w=00000000 fp-344_w=00000000 fp-352_w=00000000 fp-360_w=00000000 fp-368_w=00000000 fp-376_w=00000000 fp-384_w=00000000 fp-392_w=\ 00000000 fp-400_w=00000000 fp-408_w=00000000 fp-416_w=00000000 fp-424_w=00000000 fp-432_w=00000000 fp-440_w=00000000 fp-448_w=00000000 ; return skb->len; 157: (95) exit Func#4 is safe for any args that match its prototype Validating get_constant() func#5... 158: R1=invP(id=0) R10=fp0 ; int get_constant(long val) 158: (bf) r0 = r1 159: R0_w=invP(id=1) R1=invP(id=1) R10=fp0 ; return val - 122; 159: (04) w0 += -122 160: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=invP(id=1) R10=fp0 ; return val - 122; 160: (95) exit Func#5 is safe for any args that match its prototype Validating get_skb_ifindex() func#6... 161: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0 ; int get_skb_ifindex(int val, struct __sk_buff *skb, int var) 161: (bc) w0 = w3 162: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0 After: 156: (61) r0 = *(u32 *)(r1 +0) 157: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1=ctx(id=0,off=0,imm=0) ; return skb->len; 157: (95) exit Func#4 is safe for any args that match its prototype Validating get_constant() func#5... 158: R1=invP(id=0) R10=fp0 ; int get_constant(long val) 158: (bf) r0 = r1 159: R0_w=invP(id=1) R1=invP(id=1) ; return val - 122; 159: (04) w0 += -122 160: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) ; return val - 122; 160: (95) exit Func#5 is safe for any args that match its prototype Validating get_skb_ifindex() func#6... 161: R1=invP(id=0) R2=ctx(id=0,off=0,imm=0) R3=invP(id=0) R10=fp0 ; int get_skb_ifindex(int val, struct __sk_buff *skb, int var) 161: (bc) w0 = w3 162: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R3=invP(id=0) Signed-off-by: Christy Lee <christylee@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211216213358.3374427-2-christylee@fb.com |
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Jakub Kicinski
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7cd2802d74 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Jakub Kicinski
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aef2feda97 |
add missing bpf-cgroup.h includes
We're about to break the cgroup-defs.h -> bpf-cgroup.h dependency, make sure those who actually need more than the definition of struct cgroup_bpf include bpf-cgroup.h explicitly. Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/bpf/20211216025538.1649516-3-kuba@kernel.org |
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Daniel Borkmann
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e572ff80f0 |
bpf: Make 32->64 bounds propagation slightly more robust
Make the bounds propagation in __reg_assign_32_into_64() slightly more robust and readable by aligning it similarly as we did back in the __reg_combine_64_into_32() counterpart. Meaning, only propagate or pessimize them as a smin/smax pair. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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3cf2b61eb0 |
bpf: Fix signed bounds propagation after mov32
For the case where both s32_{min,max}_value bounds are positive, the
__reg_assign_32_into_64() directly propagates them to their 64 bit
counterparts, otherwise it pessimises them into [0,u32_max] universe and
tries to refine them later on by learning through the tnum as per comment
in mentioned function. However, that does not always happen, for example,
in mov32 operation we call zext_32_to_64(dst_reg) which invokes the
__reg_assign_32_into_64() as is without subsequent bounds update as
elsewhere thus no refinement based on tnum takes place.
Thus, not calling into the __update_reg_bounds() / __reg_deduce_bounds() /
__reg_bound_offset() triplet as we do, for example, in case of ALU ops via
adjust_scalar_min_max_vals(), will lead to more pessimistic bounds when
dumping the full register state:
Before fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=0,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Technically, the smin_value=0 and smax_value=4294967295 bounds are not
incorrect, but given the register is still a constant, they break assumptions
about const scalars that smin_value == smax_value and umin_value == umax_value.
After fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Without the smin_value == smax_value and umin_value == umax_value invariant
being intact for const scalars, it is possible to leak out kernel pointers
from unprivileged user space if the latter is enabled. For example, when such
registers are involved in pointer arithmtics, then adjust_ptr_min_max_vals()
will taint the destination register into an unknown scalar, and the latter
can be exported and stored e.g. into a BPF map value.
Fixes:
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Daniel Borkmann
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a82fe085f3 |
bpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg
The implementation of BPF_CMPXCHG on a high level has the following parameters:
.-[old-val] .-[new-val]
BPF_R0 = cmpxchg{32,64}(DST_REG + insn->off, BPF_R0, SRC_REG)
`-[mem-loc] `-[old-val]
Given a BPF insn can only have two registers (dst, src), the R0 is fixed and
used as an auxilliary register for input (old value) as well as output (returning
old value from memory location). While the verifier performs a number of safety
checks, it misses to reject unprivileged programs where R0 contains a pointer as
old value.
Through brute-forcing it takes about ~16sec on my machine to leak a kernel pointer
with BPF_CMPXCHG. The PoC is basically probing for kernel addresses by storing the
guessed address into the map slot as a scalar, and using the map value pointer as
R0 while SRC_REG has a canary value to detect a matching address.
Fix it by checking R0 for pointers, and reject if that's the case for unprivileged
programs.
Fixes:
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Daniel Borkmann
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7d3baf0afa |
bpf: Fix kernel address leakage in atomic fetch
The change in commit |
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Jiri Olsa
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f92c1e1836 |
bpf: Add get_func_[arg|ret|arg_cnt] helpers
Adding following helpers for tracing programs: Get n-th argument of the traced function: long bpf_get_func_arg(void *ctx, u32 n, u64 *value) Get return value of the traced function: long bpf_get_func_ret(void *ctx, u64 *value) Get arguments count of the traced function: long bpf_get_func_arg_cnt(void *ctx) The trampoline now stores number of arguments on ctx-8 address, so it's easy to verify argument index and find return value argument's position. Moving function ip address on the trampoline stack behind the number of functions arguments, so it's now stored on ctx-16 address if it's needed. All helpers above are inlined by verifier. Also bit unrelated small change - using newly added function bpf_prog_has_trampoline in check_get_func_ip. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211208193245.172141-5-jolsa@kernel.org |
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Jakub Kicinski
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be3158290d |
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Andrii Nakryiko says:
====================
bpf-next 2021-12-10 v2
We've added 115 non-merge commits during the last 26 day(s) which contain
a total of 182 files changed, 5747 insertions(+), 2564 deletions(-).
The main changes are:
1) Various samples fixes, from Alexander Lobakin.
2) BPF CO-RE support in kernel and light skeleton, from Alexei Starovoitov.
3) A batch of new unified APIs for libbpf, logging improvements, version
querying, etc. Also a batch of old deprecations for old APIs and various
bug fixes, in preparation for libbpf 1.0, from Andrii Nakryiko.
4) BPF documentation reorganization and improvements, from Christoph Hellwig
and Dave Tucker.
5) Support for declarative initialization of BPF_MAP_TYPE_PROG_ARRAY in
libbpf, from Hengqi Chen.
6) Verifier log fixes, from Hou Tao.
7) Runtime-bounded loops support with bpf_loop() helper, from Joanne Koong.
8) Extend branch record capturing to all platforms that support it,
from Kajol Jain.
9) Light skeleton codegen improvements, from Kumar Kartikeya Dwivedi.
10) bpftool doc-generating script improvements, from Quentin Monnet.
11) Two libbpf v0.6 bug fixes, from Shuyi Cheng and Vincent Minet.
12) Deprecation warning fix for perf/bpf_counter, from Song Liu.
13) MAX_TAIL_CALL_CNT unification and MIPS build fix for libbpf,
from Tiezhu Yang.
14) BTF_KING_TYPE_TAG follow-up fixes, from Yonghong Song.
15) Selftests fixes and improvements, from Ilya Leoshkevich, Jean-Philippe
Brucker, Jiri Olsa, Maxim Mikityanskiy, Tirthendu Sarkar, Yucong Sun,
and others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (115 commits)
libbpf: Add "bool skipped" to struct bpf_map
libbpf: Fix typo in btf__dedup@LIBBPF_0.0.2 definition
bpftool: Switch bpf_object__load_xattr() to bpf_object__load()
selftests/bpf: Remove the only use of deprecated bpf_object__load_xattr()
selftests/bpf: Add test for libbpf's custom log_buf behavior
selftests/bpf: Replace all uses of bpf_load_btf() with bpf_btf_load()
libbpf: Deprecate bpf_object__load_xattr()
libbpf: Add per-program log buffer setter and getter
libbpf: Preserve kernel error code and remove kprobe prog type guessing
libbpf: Improve logging around BPF program loading
libbpf: Allow passing user log setting through bpf_object_open_opts
libbpf: Allow passing preallocated log_buf when loading BTF into kernel
libbpf: Add OPTS-based bpf_btf_load() API
libbpf: Fix bpf_prog_load() log_buf logic for log_level 0
samples/bpf: Remove unneeded variable
bpf: Remove redundant assignment to pointer t
selftests/bpf: Fix a compilation warning
perf/bpf_counter: Use bpf_map_create instead of bpf_create_map
samples: bpf: Fix 'unknown warning group' build warning on Clang
samples: bpf: Fix xdp_sample_user.o linking with Clang
...
====================
Link: https://lore.kernel.org/r/20211210234746.2100561-1-andrii@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Paul Chaignon
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345e004d02 |
bpf: Fix incorrect state pruning for <8B spill/fill
Commit |
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Jakub Kicinski
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3150a73366 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Hou Tao
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866de40744 |
bpf: Disallow BPF_LOG_KERNEL log level for bpf(BPF_BTF_LOAD)
BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.
Fixes:
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Maxim Mikityanskiy
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2fa7d94afc |
bpf: Fix the off-by-two error in range markings
The first commit cited below attempts to fix the off-by-one error that
appeared in some comparisons with an open range. Due to this error,
arithmetically equivalent pieces of code could get different verdicts
from the verifier, for example (pseudocode):
// 1. Passes the verifier:
if (data + 8 > data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
// 2. Rejected by the verifier (should still pass):
if (data + 7 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The attempted fix, however, shifts the range by one in a wrong
direction, so the bug not only remains, but also such piece of code
starts failing in the verifier:
// 3. Rejected by the verifier, but the check is stricter than in #1.
if (data + 8 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The change performed by that fix converted an off-by-one bug into
off-by-two. The second commit cited below added the BPF selftests
written to ensure than code chunks like #3 are rejected, however,
they should be accepted.
This commit fixes the off-by-two error by adjusting new_range in the
right direction and fixes the tests by changing the range into the
one that should actually fail.
Fixes:
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Alexei Starovoitov
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fbd94c7afc |
bpf: Pass a set of bpf_core_relo-s to prog_load command.
struct bpf_core_relo is generated by llvm and processed by libbpf. It's a de-facto uapi. With CO-RE in the kernel the struct bpf_core_relo becomes uapi de-jure. Add an ability to pass a set of 'struct bpf_core_relo' to prog_load command and let the kernel perform CO-RE relocations. Note the struct bpf_line_info and struct bpf_func_info have the same layout when passed from LLVM to libbpf and from libbpf to the kernel except "insn_off" fields means "byte offset" when LLVM generates it. Then libbpf converts it to "insn index" to pass to the kernel. The struct bpf_core_relo's "insn_off" field is always "byte offset". Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211201181040.23337-6-alexei.starovoitov@gmail.com |
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Hou Tao
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436d404cc8 |
bpf: Clean-up bpf_verifier_vlog() for BPF_LOG_KERNEL log level
An extra newline will output for bpf_log() with BPF_LOG_KERNEL level as shown below: [ 52.095704] BPF:The function test_3 has 12 arguments. Too many. [ 52.095704] [ 52.096896] Error in parsing func ptr test_3 in struct bpf_dummy_ops Now all bpf_log() are ended by newline, but not all btf_verifier_log() are ended by newline, so checking whether or not the log message has the trailing newline and adding a newline if not. Also there is no need to calculate the left userspace buffer size for kernel log output and to truncate the output by '\0' which has already been done by vscnprintf(), so only do these for userspace log output. Signed-off-by: Hou Tao <houtao1@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20211201073458.2731595-2-houtao1@huawei.com |
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Joanne Koong
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e6f2dd0f80 |
bpf: Add bpf_loop helper
This patch adds the kernel-side and API changes for a new helper function, bpf_loop: long bpf_loop(u32 nr_loops, void *callback_fn, void *callback_ctx, u64 flags); where long (*callback_fn)(u32 index, void *ctx); bpf_loop invokes the "callback_fn" **nr_loops** times or until the callback_fn returns 1. The callback_fn can only return 0 or 1, and this is enforced by the verifier. The callback_fn index is zero-indexed. A few things to please note: ~ The "u64 flags" parameter is currently unused but is included in case a future use case for it arises. ~ In the kernel-side implementation of bpf_loop (kernel/bpf/bpf_iter.c), bpf_callback_t is used as the callback function cast. ~ A program can have nested bpf_loop calls but the program must still adhere to the verifier constraint of its stack depth (the stack depth cannot exceed MAX_BPF_STACK)) ~ Recursive callback_fns do not pass the verifier, due to the call stack for these being too deep. ~ The next patch will include the tests and benchmark Signed-off-by: Joanne Koong <joannekoong@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211130030622.4131246-2-joannekoong@fb.com |
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Jakub Kicinski
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50fc24944a |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Daniel Borkmann
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353050be4c |
bpf: Fix toctou on read-only map's constant scalar tracking
Commit |
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Dmitrii Banshchikov
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5e0bc3082e |
bpf: Forbid bpf_ktime_get_coarse_ns and bpf_timer_* in tracing progs
Use of bpf_ktime_get_coarse_ns() and bpf_timer_* helpers in tracing progs may result in locking issues. bpf_ktime_get_coarse_ns() uses ktime_get_coarse_ns() time accessor that isn't safe for any context: ====================================================== WARNING: possible circular locking dependency detected 5.15.0-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/14877 is trying to acquire lock: ffffffff8cb30008 (tk_core.seq.seqcount){----}-{0:0}, at: ktime_get_coarse_ts64+0x25/0x110 kernel/time/timekeeping.c:2255 but task is already holding lock: ffffffff90dbf200 (&obj_hash[i].lock){-.-.}-{2:2}, at: debug_object_deactivate+0x61/0x400 lib/debugobjects.c:735 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&obj_hash[i].lock){-.-.}-{2:2}: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0xd1/0x120 kernel/locking/spinlock.c:162 __debug_object_init+0xd9/0x1860 lib/debugobjects.c:569 debug_hrtimer_init kernel/time/hrtimer.c:414 [inline] debug_init kernel/time/hrtimer.c:468 [inline] hrtimer_init+0x20/0x40 kernel/time/hrtimer.c:1592 ntp_init_cmos_sync kernel/time/ntp.c:676 [inline] ntp_init+0xa1/0xad kernel/time/ntp.c:1095 timekeeping_init+0x512/0x6bf kernel/time/timekeeping.c:1639 start_kernel+0x267/0x56e init/main.c:1030 secondary_startup_64_no_verify+0xb1/0xbb -> #0 (tk_core.seq.seqcount){----}-{0:0}: check_prev_add kernel/locking/lockdep.c:3051 [inline] check_prevs_add kernel/locking/lockdep.c:3174 [inline] validate_chain+0x1dfb/0x8240 kernel/locking/lockdep.c:3789 __lock_acquire+0x1382/0x2b00 kernel/locking/lockdep.c:5015 lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 seqcount_lockdep_reader_access+0xfe/0x230 include/linux/seqlock.h:103 ktime_get_coarse_ts64+0x25/0x110 kernel/time/timekeeping.c:2255 ktime_get_coarse include/linux/timekeeping.h:120 [inline] ktime_get_coarse_ns include/linux/timekeeping.h:126 [inline] ____bpf_ktime_get_coarse_ns kernel/bpf/helpers.c:173 [inline] bpf_ktime_get_coarse_ns+0x7e/0x130 kernel/bpf/helpers.c:171 bpf_prog_a99735ebafdda2f1+0x10/0xb50 bpf_dispatcher_nop_func include/linux/bpf.h:721 [inline] __bpf_prog_run include/linux/filter.h:626 [inline] bpf_prog_run include/linux/filter.h:633 [inline] BPF_PROG_RUN_ARRAY include/linux/bpf.h:1294 [inline] trace_call_bpf+0x2cf/0x5d0 kernel/trace/bpf_trace.c:127 perf_trace_run_bpf_submit+0x7b/0x1d0 kernel/events/core.c:9708 perf_trace_lock+0x37c/0x440 include/trace/events/lock.h:39 trace_lock_release+0x128/0x150 include/trace/events/lock.h:58 lock_release+0x82/0x810 kernel/locking/lockdep.c:5636 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:149 [inline] _raw_spin_unlock_irqrestore+0x75/0x130 kernel/locking/spinlock.c:194 debug_hrtimer_deactivate kernel/time/hrtimer.c:425 [inline] debug_deactivate kernel/time/hrtimer.c:481 [inline] __run_hrtimer kernel/time/hrtimer.c:1653 [inline] __hrtimer_run_queues+0x2f9/0xa60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xd4/0x130 kernel/locking/spinlock.c:194 try_to_wake_up+0x702/0xd20 kernel/sched/core.c:4118 wake_up_process kernel/sched/core.c:4200 [inline] wake_up_q+0x9a/0xf0 kernel/sched/core.c:953 futex_wake+0x50f/0x5b0 kernel/futex/waitwake.c:184 do_futex+0x367/0x560 kernel/futex/syscalls.c:127 __do_sys_futex kernel/futex/syscalls.c:199 [inline] __se_sys_futex+0x401/0x4b0 kernel/futex/syscalls.c:180 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae There is a possible deadlock with bpf_timer_* set of helpers: hrtimer_start() lock_base(); trace_hrtimer...() perf_event() bpf_run() bpf_timer_start() hrtimer_start() lock_base() <- DEADLOCK Forbid use of bpf_ktime_get_coarse_ns() and bpf_timer_* helpers in BPF_PROG_TYPE_KPROBE, BPF_PROG_TYPE_TRACEPOINT, BPF_PROG_TYPE_PERF_EVENT and BPF_PROG_TYPE_RAW_TRACEPOINT prog types. Fixes: |
|
|
Jakub Kicinski
|
a5bdc36354 |
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says: ==================== pull-request: bpf-next 2021-11-15 We've added 72 non-merge commits during the last 13 day(s) which contain a total of 171 files changed, 2728 insertions(+), 1143 deletions(-). The main changes are: 1) Add btf_type_tag attributes to bring kernel annotations like __user/__rcu to BTF such that BPF verifier will be able to detect misuse, from Yonghong Song. 2) Big batch of libbpf improvements including various fixes, future proofing APIs, and adding a unified, OPTS-based bpf_prog_load() low-level API, from Andrii Nakryiko. 3) Add ingress_ifindex to BPF_SK_LOOKUP program type for selectively applying the programmable socket lookup logic to packets from a given netdev, from Mark Pashmfouroush. 4) Remove the 128M upper JIT limit for BPF programs on arm64 and add selftest to ensure exception handling still works, from Russell King and Alan Maguire. 5) Add a new bpf_find_vma() helper for tracing to map an address to the backing file such as shared library, from Song Liu. 6) Batch of various misc fixes to bpftool, fixing a memory leak in BPF program dump, updating documentation and bash-completion among others, from Quentin Monnet. 7) Deprecate libbpf bpf_program__get_prog_info_linear() API and migrate its users as the API is heavily tailored around perf and is non-generic, from Dave Marchevsky. 8) Enable libbpf's strict mode by default in bpftool and add a --legacy option as an opt-out for more relaxed BPF program requirements, from Stanislav Fomichev. 9) Fix bpftool to use libbpf_get_error() to check for errors, from Hengqi Chen. * https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (72 commits) bpftool: Use libbpf_get_error() to check error bpftool: Fix mixed indentation in documentation bpftool: Update the lists of names for maps and prog-attach types bpftool: Fix indent in option lists in the documentation bpftool: Remove inclusion of utilities.mak from Makefiles bpftool: Fix memory leak in prog_dump() selftests/bpf: Fix a tautological-constant-out-of-range-compare compiler warning selftests/bpf: Fix an unused-but-set-variable compiler warning bpf: Introduce btf_tracing_ids bpf: Extend BTF_ID_LIST_GLOBAL with parameter for number of IDs bpftool: Enable libbpf's strict mode by default docs/bpf: Update documentation for BTF_KIND_TYPE_TAG support selftests/bpf: Clarify llvm dependency with btf_tag selftest selftests/bpf: Add a C test for btf_type_tag selftests/bpf: Rename progs/tag.c to progs/btf_decl_tag.c selftests/bpf: Test BTF_KIND_DECL_TAG for deduplication selftests/bpf: Add BTF_KIND_TYPE_TAG unit tests selftests/bpf: Test libbpf API function btf__add_type_tag() bpftool: Support BTF_KIND_TYPE_TAG libbpf: Support BTF_KIND_TYPE_TAG ... ==================== Link: https://lore.kernel.org/r/20211115162008.25916-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
|
Song Liu
|
d19ddb476a |
bpf: Introduce btf_tracing_ids
Similar to btf_sock_ids, btf_tracing_ids provides btf ID for task_struct, file, and vm_area_struct via easy to understand format like btf_tracing_ids[BTF_TRACING_TYPE_[TASK|file|VMA]]. Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20211112150243.1270987-3-songliubraving@fb.com |
|
|
Alexei Starovoitov
|
34d11a440c |
bpf: Fix inner map state pruning regression.
Introduction of map_uid made two lookups from outer map to be distinct.
That distinction is only necessary when inner map has an embedded timer.
Otherwise it will make the verifier state pruning to be conservative
which will cause complex programs to hit 1M insn_processed limit.
Tighten map_uid logic to apply to inner maps with timers only.
Fixes:
|
|
|
Song Liu
|
7c7e3d31e7 |
bpf: Introduce helper bpf_find_vma
In some profiler use cases, it is necessary to map an address to the backing file, e.g., a shared library. bpf_find_vma helper provides a flexible way to achieve this. bpf_find_vma maps an address of a task to the vma (vm_area_struct) for this address, and feed the vma to an callback BPF function. The callback function is necessary here, as we need to ensure mmap_sem is unlocked. It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem safely when irqs are disable, we use the same mechanism as stackmap with build_id. Specifically, when irqs are disabled, the unlocked is postponed in an irq_work. Refactor stackmap.c so that the irq_work is shared among bpf_find_vma and stackmap helpers. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Hengqi Chen <hengqi.chen@gmail.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20211105232330.1936330-2-songliubraving@fb.com |
|
Martin KaFai Lau
|
3990ed4c42 |
bpf: Stop caching subprog index in the bpf_pseudo_func insn
This patch is to fix an out-of-bound access issue when jit-ing the
bpf_pseudo_func insn (i.e. ld_imm64 with src_reg == BPF_PSEUDO_FUNC)
In jit_subprog(), it currently reuses the subprog index cached in
insn[1].imm. This subprog index is an index into a few array related
to subprogs. For example, in jit_subprog(), it is an index to the newly
allocated 'struct bpf_prog **func' array.
The subprog index was cached in insn[1].imm after add_subprog(). However,
this could become outdated (and too big in this case) if some subprogs
are completely removed during dead code elimination (in
adjust_subprog_starts_after_remove). The cached index in insn[1].imm
is not updated accordingly and causing out-of-bound issue in the later
jit_subprog().
Unlike bpf_pseudo_'func' insn, the current bpf_pseudo_'call' insn
is handling the DCE properly by calling find_subprog(insn->imm) to
figure out the index instead of caching the subprog index.
The existing bpf_adj_branches() will adjust the insn->imm
whenever insn is added or removed.
Instead of having two ways handling subprog index,
this patch is to make bpf_pseudo_func works more like
bpf_pseudo_call.
First change is to stop caching the subprog index result
in insn[1].imm after add_subprog(). The verification
process will use find_subprog(insn->imm) to figure
out the subprog index.
Second change is in bpf_adj_branches() and have it to
adjust the insn->imm for the bpf_pseudo_func insn also
whenever insn is added or removed.
Third change is in jit_subprog(). Like the bpf_pseudo_call handling,
bpf_pseudo_func temporarily stores the find_subprog() result
in insn->off. It is fine because the prog's insn has been finalized
at this point. insn->off will be reset back to 0 later to avoid
confusing the userspace prog dump tool.
Fixes:
|
|
|
Martin KaFai Lau
|
f30d4968e9 |
bpf: Do not reject when the stack read size is different from the tracked scalar size
Below is a simplified case from a report in bcc [0]: r4 = 20 *(u32 *)(r10 -4) = r4 *(u32 *)(r10 -8) = r4 /* r4 state is tracked */ r4 = *(u64 *)(r10 -8) /* Read more than the tracked 32bit scalar. * verifier rejects as 'corrupted spill memory'. */ After commit |
|
Linus Torvalds
|
fc02cb2b37 |
Core:
- Remove socket skb caches
- Add a SO_RESERVE_MEM socket op to forward allocate buffer space
and avoid memory accounting overhead on each message sent
- Introduce managed neighbor entries - added by control plane and
resolved by the kernel for use in acceleration paths (BPF / XDP
right now, HW offload users will benefit as well)
- Make neighbor eviction on link down controllable by userspace
to work around WiFi networks with bad roaming implementations
- vrf: Rework interaction with netfilter/conntrack
- fq_codel: implement L4S style ce_threshold_ect1 marking
- sch: Eliminate unnecessary RCU waits in mini_qdisc_pair_swap()
BPF:
- Add support for new btf kind BTF_KIND_TAG, arbitrary type tagging
as implemented in LLVM14
- Introduce bpf_get_branch_snapshot() to capture Last Branch Records
- Implement variadic trace_printk helper
- Add a new Bloomfilter map type
- Track <8-byte scalar spill and refill
- Access hw timestamp through BPF's __sk_buff
- Disallow unprivileged BPF by default
- Document BPF licensing
Netfilter:
- Introduce egress hook for looking at raw outgoing packets
- Allow matching on and modifying inner headers / payload data
- Add NFT_META_IFTYPE to match on the interface type either from
ingress or egress
Protocols:
- Multi-Path TCP:
- increase default max additional subflows to 2
- rework forward memory allocation
- add getsockopts: MPTCP_INFO, MPTCP_TCPINFO, MPTCP_SUBFLOW_ADDRS
- MCTP flow support allowing lower layer drivers to configure msg
muxing as needed
- Automatic Multicast Tunneling (AMT) driver based on RFC7450
- HSR support the redbox supervision frames (IEC-62439-3:2018)
- Support for the ip6ip6 encapsulation of IOAM
- Netlink interface for CAN-FD's Transmitter Delay Compensation
- Support SMC-Rv2 eliminating the current same-subnet restriction,
by exploiting the UDP encapsulation feature of RoCE adapters
- TLS: add SM4 GCM/CCM crypto support
- Bluetooth: initial support for link quality and audio/codec
offload
Driver APIs:
- Add a batched interface for RX buffer allocation in AF_XDP
buffer pool
- ethtool: Add ability to control transceiver modules' power mode
- phy: Introduce supported interfaces bitmap to express MAC
capabilities and simplify PHY code
- Drop rtnl_lock from DSA .port_fdb_{add,del} callbacks
New drivers:
- WiFi driver for Realtek 8852AE 802.11ax devices (rtw89)
- Ethernet driver for ASIX AX88796C SPI device (x88796c)
Drivers:
- Broadcom PHYs
- support 72165, 7712 16nm PHYs
- support IDDQ-SR for additional power savings
- PHY support for QCA8081, QCA9561 PHYs
- NXP DPAA2: support for IRQ coalescing
- NXP Ethernet (enetc): support for software TCP segmentation
- Renesas Ethernet (ravb) - support DMAC and EMAC blocks of
Gigabit-capable IP found on RZ/G2L SoC
- Intel 100G Ethernet
- support for eswitch offload of TC/OvS flow API, including
offload of GRE, VxLAN, Geneve tunneling
- support application device queues - ability to assign Rx and Tx
queues to application threads
- PTP and PPS (pulse-per-second) extensions
- Broadcom Ethernet (bnxt)
- devlink health reporting and device reload extensions
- Mellanox Ethernet (mlx5)
- offload macvlan interfaces
- support HW offload of TC rules involving OVS internal ports
- support HW-GRO and header/data split
- support application device queues
- Marvell OcteonTx2:
- add XDP support for PF
- add PTP support for VF
- Qualcomm Ethernet switch (qca8k): support for QCA8328
- Realtek Ethernet DSA switch (rtl8366rb)
- support bridge offload
- support STP, fast aging, disabling address learning
- support for Realtek RTL8365MB-VC, a 4+1 port 10M/100M/1GE switch
- Mellanox Ethernet/IB switch (mlxsw)
- multi-level qdisc hierarchy offload (e.g. RED, prio and shaping)
- offload root TBF qdisc as port shaper
- support multiple routing interface MAC address prefixes
- support for IP-in-IP with IPv6 underlay
- MediaTek WiFi (mt76)
- mt7921 - ASPM, 6GHz, SDIO and testmode support
- mt7915 - LED and TWT support
- Qualcomm WiFi (ath11k)
- include channel rx and tx time in survey dump statistics
- support for 80P80 and 160 MHz bandwidths
- support channel 2 in 6 GHz band
- spectral scan support for QCN9074
- support for rx decapsulation offload (data frames in 802.3
format)
- Qualcomm phone SoC WiFi (wcn36xx)
- enable Idle Mode Power Save (IMPS) to reduce power consumption
during idle
- Bluetooth driver support for MediaTek MT7922 and MT7921
- Enable support for AOSP Bluetooth extension in Qualcomm WCN399x
and Realtek 8822C/8852A
- Microsoft vNIC driver (mana)
- support hibernation and kexec
- Google vNIC driver (gve)
- support for jumbo frames
- implement Rx page reuse
Refactor:
- Make all writes to netdev->dev_addr go thru helpers, so that we
can add this address to the address rbtree and handle the updates
- Various TCP cleanups and optimizations including improvements
to CPU cache use
- Simplify the gnet_stats, Qdisc stats' handling and remove
qdisc->running sequence counter
- Driver changes and API updates to address devlink locking
deficiencies
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- Remove socket skb caches
- Add a SO_RESERVE_MEM socket op to forward allocate buffer space and
avoid memory accounting overhead on each message sent
- Introduce managed neighbor entries - added by control plane and
resolved by the kernel for use in acceleration paths (BPF / XDP
right now, HW offload users will benefit as well)
- Make neighbor eviction on link down controllable by userspace to
work around WiFi networks with bad roaming implementations
- vrf: Rework interaction with netfilter/conntrack
- fq_codel: implement L4S style ce_threshold_ect1 marking
- sch: Eliminate unnecessary RCU waits in mini_qdisc_pair_swap()
BPF:
- Add support for new btf kind BTF_KIND_TAG, arbitrary type tagging
as implemented in LLVM14
- Introduce bpf_get_branch_snapshot() to capture Last Branch Records
- Implement variadic trace_printk helper
- Add a new Bloomfilter map type
- Track <8-byte scalar spill and refill
- Access hw timestamp through BPF's __sk_buff
- Disallow unprivileged BPF by default
- Document BPF licensing
Netfilter:
- Introduce egress hook for looking at raw outgoing packets
- Allow matching on and modifying inner headers / payload data
- Add NFT_META_IFTYPE to match on the interface type either from
ingress or egress
Protocols:
- Multi-Path TCP:
- increase default max additional subflows to 2
- rework forward memory allocation
- add getsockopts: MPTCP_INFO, MPTCP_TCPINFO, MPTCP_SUBFLOW_ADDRS
- MCTP flow support allowing lower layer drivers to configure msg
muxing as needed
- Automatic Multicast Tunneling (AMT) driver based on RFC7450
- HSR support the redbox supervision frames (IEC-62439-3:2018)
- Support for the ip6ip6 encapsulation of IOAM
- Netlink interface for CAN-FD's Transmitter Delay Compensation
- Support SMC-Rv2 eliminating the current same-subnet restriction, by
exploiting the UDP encapsulation feature of RoCE adapters
- TLS: add SM4 GCM/CCM crypto support
- Bluetooth: initial support for link quality and audio/codec offload
Driver APIs:
- Add a batched interface for RX buffer allocation in AF_XDP buffer
pool
- ethtool: Add ability to control transceiver modules' power mode
- phy: Introduce supported interfaces bitmap to express MAC
capabilities and simplify PHY code
- Drop rtnl_lock from DSA .port_fdb_{add,del} callbacks
New drivers:
- WiFi driver for Realtek 8852AE 802.11ax devices (rtw89)
- Ethernet driver for ASIX AX88796C SPI device (x88796c)
Drivers:
- Broadcom PHYs
- support 72165, 7712 16nm PHYs
- support IDDQ-SR for additional power savings
- PHY support for QCA8081, QCA9561 PHYs
- NXP DPAA2: support for IRQ coalescing
- NXP Ethernet (enetc): support for software TCP segmentation
- Renesas Ethernet (ravb) - support DMAC and EMAC blocks of
Gigabit-capable IP found on RZ/G2L SoC
- Intel 100G Ethernet
- support for eswitch offload of TC/OvS flow API, including
offload of GRE, VxLAN, Geneve tunneling
- support application device queues - ability to assign Rx and Tx
queues to application threads
- PTP and PPS (pulse-per-second) extensions
- Broadcom Ethernet (bnxt)
- devlink health reporting and device reload extensions
- Mellanox Ethernet (mlx5)
- offload macvlan interfaces
- support HW offload of TC rules involving OVS internal ports
- support HW-GRO and header/data split
- support application device queues
- Marvell OcteonTx2:
- add XDP support for PF
- add PTP support for VF
- Qualcomm Ethernet switch (qca8k): support for QCA8328
- Realtek Ethernet DSA switch (rtl8366rb)
- support bridge offload
- support STP, fast aging, disabling address learning
- support for Realtek RTL8365MB-VC, a 4+1 port 10M/100M/1GE switch
- Mellanox Ethernet/IB switch (mlxsw)
- multi-level qdisc hierarchy offload (e.g. RED, prio and shaping)
- offload root TBF qdisc as port shaper
- support multiple routing interface MAC address prefixes
- support for IP-in-IP with IPv6 underlay
- MediaTek WiFi (mt76)
- mt7921 - ASPM, 6GHz, SDIO and testmode support
- mt7915 - LED and TWT support
- Qualcomm WiFi (ath11k)
- include channel rx and tx time in survey dump statistics
- support for 80P80 and 160 MHz bandwidths
- support channel 2 in 6 GHz band
- spectral scan support for QCN9074
- support for rx decapsulation offload (data frames in 802.3
format)
- Qualcomm phone SoC WiFi (wcn36xx)
- enable Idle Mode Power Save (IMPS) to reduce power consumption
during idle
- Bluetooth driver support for MediaTek MT7922 and MT7921
- Enable support for AOSP Bluetooth extension in Qualcomm WCN399x and
Realtek 8822C/8852A
- Microsoft vNIC driver (mana)
- support hibernation and kexec
- Google vNIC driver (gve)
- support for jumbo frames
- implement Rx page reuse
Refactor:
- Make all writes to netdev->dev_addr go thru helpers, so that we can
add this address to the address rbtree and handle the updates
- Various TCP cleanups and optimizations including improvements to
CPU cache use
- Simplify the gnet_stats, Qdisc stats' handling and remove
qdisc->running sequence counter
- Driver changes and API updates to address devlink locking
deficiencies"
* tag 'net-next-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2122 commits)
Revert "net: avoid double accounting for pure zerocopy skbs"
selftests: net: add arp_ndisc_evict_nocarrier
net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter
net: arp: introduce arp_evict_nocarrier sysctl parameter
libbpf: Deprecate AF_XDP support
kbuild: Unify options for BTF generation for vmlinux and modules
selftests/bpf: Add a testcase for 64-bit bounds propagation issue.
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
net: vmxnet3: remove multiple false checks in vmxnet3_ethtool.c
net: avoid double accounting for pure zerocopy skbs
tcp: rename sk_wmem_free_skb
netdevsim: fix uninit value in nsim_drv_configure_vfs()
selftests/bpf: Fix also no-alu32 strobemeta selftest
bpf: Add missing map_delete_elem method to bloom filter map
selftests/bpf: Add bloom map success test for userspace calls
bpf: Add alignment padding for "map_extra" + consolidate holes
bpf: Bloom filter map naming fixups
selftests/bpf: Add test cases for struct_ops prog
bpf: Add dummy BPF STRUCT_OPS for test purpose
...
|
|
|
Alexei Starovoitov
|
388e2c0b97 |
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
Similar to unsigned bounds propagation fix signed bounds.
The 'Fixes' tag is a hint. There is no security bug here.
The verifier was too conservative.
Fixes:
|
|
|
Alexei Starovoitov
|
b9979db834 |
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
Before this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff)) After this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1)) While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1 and call __reg_combine_64_into_32(true_reg). Without the fix it would not pass the condition: if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) since umin_value == 0 at this point. Before commit |
|
|
Joanne Koong
|
9330986c03 |
bpf: Add bloom filter map implementation
This patch adds the kernel-side changes for the implementation of a bpf bloom filter map. The bloom filter map supports peek (determining whether an element is present in the map) and push (adding an element to the map) operations.These operations are exposed to userspace applications through the already existing syscalls in the following way: BPF_MAP_LOOKUP_ELEM -> peek BPF_MAP_UPDATE_ELEM -> push The bloom filter map does not have keys, only values. In light of this, the bloom filter map's API matches that of queue stack maps: user applications use BPF_MAP_LOOKUP_ELEM/BPF_MAP_UPDATE_ELEM which correspond internally to bpf_map_peek_elem/bpf_map_push_elem, and bpf programs must use the bpf_map_peek_elem and bpf_map_push_elem APIs to query or add an element to the bloom filter map. When the bloom filter map is created, it must be created with a key_size of 0. For updates, the user will pass in the element to add to the map as the value, with a NULL key. For lookups, the user will pass in the element to query in the map as the value, with a NULL key. In the verifier layer, this requires us to modify the argument type of a bloom filter's BPF_FUNC_map_peek_elem call to ARG_PTR_TO_MAP_VALUE; as well, in the syscall layer, we need to copy over the user value so that in bpf_map_peek_elem, we know which specific value to query. A few things to please take note of: * If there are any concurrent lookups + updates, the user is responsible for synchronizing this to ensure no false negative lookups occur. * The number of hashes to use for the bloom filter is configurable from userspace. If no number is specified, the default used will be 5 hash functions. The benchmarks later in this patchset can help compare the performance of using different number of hashes on different entry sizes. In general, using more hashes decreases both the false positive rate and the speed of a lookup. * Deleting an element in the bloom filter map is not supported. * The bloom filter map may be used as an inner map. * The "max_entries" size that is specified at map creation time is used to approximate a reasonable bitmap size for the bloom filter, and is not otherwise strictly enforced. If the user wishes to insert more entries into the bloom filter than "max_entries", they may do so but they should be aware that this may lead to a higher false positive rate. Signed-off-by: Joanne Koong <joannekoong@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211027234504.30744-2-joannekoong@fb.com |
|
Dave Marchevsky
|
aba64c7da9 |
bpf: Add verified_insns to bpf_prog_info and fdinfo
This stat is currently printed in the verifier log and not stored anywhere. To ease consumption of this data, add a field to bpf_prog_aux so it can be exposed via BPF_OBJ_GET_INFO_BY_FD and fdinfo. Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20211020074818.1017682-2-davemarchevsky@fb.com |
|
Kumar Kartikeya Dwivedi
|
588cd7ef53 |
bpf: Silence Coverity warning for find_kfunc_desc_btf
The helper function returns a pointer that in the failure case encodes
an error in the struct btf pointer. The current code lead to Coverity
warning about the use of the invalid pointer:
*** CID 1507963: Memory - illegal accesses (USE_AFTER_FREE)
/kernel/bpf/verifier.c: 1788 in find_kfunc_desc_btf()
1782 return ERR_PTR(-EINVAL);
1783 }
1784
1785 kfunc_btf = __find_kfunc_desc_btf(env, offset, btf_modp);
1786 if (IS_ERR_OR_NULL(kfunc_btf)) {
1787 verbose(env, "cannot find module BTF for func_id %u\n", func_id);
>>> CID 1507963: Memory - illegal accesses (USE_AFTER_FREE)
>>> Using freed pointer "kfunc_btf".
1788 return kfunc_btf ?: ERR_PTR(-ENOENT);
1789 }
1790 return kfunc_btf;
1791 }
1792 return btf_vmlinux ?: ERR_PTR(-ENOENT);
1793 }
Daniel suggested the use of ERR_CAST so that the intended use is clear
to Coverity, but on closer look it seems that we never return NULL from
the helper. Andrii noted that since __find_kfunc_desc_btf already logs
errors for all cases except btf_get_by_fd, it is much easier to add
logging for that and remove the IS_ERR check altogether, returning
directly from it.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211009040900.803436-1-memxor@gmail.com
|
|
Matthew Wilcox (Oracle)
|
9dd3d06940 |
mm/filemap: Add filemap_add_folio()
Convert __add_to_page_cache_locked() into __filemap_add_folio(). Add an assertion to it that (for !hugetlbfs), the folio is naturally aligned within the file. Move the prototype from mm.h to pagemap.h. Convert add_to_page_cache_lru() into filemap_add_folio(). Add a compatibility wrapper for unconverted callers. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Howells <dhowells@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> |
|
Andrey Ignatov
|
0640c77c46 |
bpf: Avoid retpoline for bpf_for_each_map_elem
Similarly to |
|
|
Kumar Kartikeya Dwivedi
|
a5d8272752 |
bpf: Be conservative while processing invalid kfunc calls
This patch also modifies the BPF verifier to only return error for invalid kfunc calls specially marked by userspace (with insn->imm == 0, insn->off == 0) after the verifier has eliminated dead instructions. This can be handled in the fixup stage, and skip processing during add and check stages. If such an invalid call is dropped, the fixup stage will not encounter insn->imm as 0, otherwise it bails out and returns an error. This will be exposed as weak ksym support in libbpf in later patches. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211002011757.311265-3-memxor@gmail.com |
|
|
Kumar Kartikeya Dwivedi
|
2357672c54 |
bpf: Introduce BPF support for kernel module function calls
This change adds support on the kernel side to allow for BPF programs to call kernel module functions. Userspace will prepare an array of module BTF fds that is passed in during BPF_PROG_LOAD using fd_array parameter. In the kernel, the module BTFs are placed in the auxilliary struct for bpf_prog, and loaded as needed. The verifier then uses insn->off to index into the fd_array. insn->off 0 is reserved for vmlinux BTF (for backwards compat), so userspace must use an fd_array index > 0 for module kfunc support. kfunc_btf_tab is sorted based on offset in an array, and each offset corresponds to one descriptor, with a max limit up to 256 such module BTFs. We also change existing kfunc_tab to distinguish each element based on imm, off pair as each such call will now be distinct. Another change is to check_kfunc_call callback, which now include a struct module * pointer, this is to be used in later patch such that the kfunc_id and module pointer are matched for dynamically registered BTF sets from loadable modules, so that same kfunc_id in two modules doesn't lead to check_kfunc_call succeeding. For the duration of the check_kfunc_call, the reference to struct module exists, as it returns the pointer stored in kfunc_btf_tab. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211002011757.311265-2-memxor@gmail.com |
|
Kees Cook
|
3d717fad50 |
bpf: Replace "want address" users of BPF_CAST_CALL with BPF_CALL_IMM
In order to keep ahead of cases in the kernel where Control Flow Integrity (CFI) may trip over function call casts, enabling -Wcast-function-type is helpful. To that end, BPF_CAST_CALL causes various warnings and is one of the last places in the kernel triggering this warning. Most places using BPF_CAST_CALL actually just want a void * to perform math on. It's not actually performing a call, so just use a different helper to get the void *, by way of the new BPF_CALL_IMM() helper, which can clean up a common copy/paste idiom as well. This change results in no object code difference. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://github.com/KSPP/linux/issues/20 Link: https://lore.kernel.org/lkml/CAEf4Bzb46=-J5Fxc3mMZ8JQPtK1uoE0q6+g6WPz53Cvx=CBEhw@mail.gmail.com Link: https://lore.kernel.org/bpf/20210928230946.4062144-2-keescook@chromium.org |
|
|
Martin KaFai Lau
|
354e8f1970 |
bpf: Support <8-byte scalar spill and refill
The verifier currently does not save the reg state when spilling <8byte bounded scalar to the stack. The bpf program will be incorrectly rejected when this scalar is refilled to the reg and then used to offset into a packet header. The later patch has a simplified bpf prog from a real use case to demonstrate this case. The current work around is to reparse the packet again such that this offset scalar is close to where the packet data will be accessed to avoid the spill. Thus, the header is parsed twice. The llvm patch [1] will align the <8bytes spill to the 8-byte stack address. This can simplify the verifier support by avoiding to store multiple reg states for each 8 byte stack slot. This patch changes the verifier to save the reg state when spilling <8bytes scalar to the stack. This reg state saving is limited to spill aligned to the 8-byte stack address. The current refill logic has already called coerce_reg_to_size(), so coerce_reg_to_size() is not called on state->stack[spi].spilled_ptr during spill. When refilling in check_stack_read_fixed_off(), it checks the refill size is the same as the number of bytes marked with STACK_SPILL before restoring the reg state. When restoring the reg state to state->regs[dst_regno], it needs to avoid the state->regs[dst_regno].subreg_def being over written because it has been marked by the check_reg_arg() earlier [check_mem_access() is called after check_reg_arg() in do_check()]. Reordering check_mem_access() and check_reg_arg() will need a lot of changes in test_verifier's tests because of the difference in verifier's error message. Thus, the patch here is to save the state->regs[dst_regno].subreg_def first in check_stack_read_fixed_off(). There are cases that the verifier needs to scrub the spilled slot from STACK_SPILL to STACK_MISC. After this patch the spill is not always in 8 bytes now, so it can no longer assume the other 7 bytes are always marked as STACK_SPILL. In particular, the scrub needs to avoid marking an uninitialized byte from STACK_INVALID to STACK_MISC. Otherwise, the verifier will incorrectly accept bpf program reading uninitialized bytes from the stack. A new helper scrub_spilled_slot() is created for this purpose. [1]: https://reviews.llvm.org/D109073 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210922004941.625398-1-kafai@fb.com |
|
|
Martin KaFai Lau
|
27113c59b6 |
bpf: Check the other end of slot_type for STACK_SPILL
Every 8 bytes of the stack is tracked by a bpf_stack_state. Within each bpf_stack_state, there is a 'u8 slot_type[8]' to track the type of each byte. Verifier tests slot_type[0] == STACK_SPILL to decide if the spilled reg state is saved. Verifier currently only saves the reg state if the whole 8 bytes are spilled to the stack, so checking the slot_type[7] is the same as checking slot_type[0]. The later patch will allow verifier to save the bounded scalar reg also for <8 bytes spill. There is a llvm patch [1] to ensure the <8 bytes spill will be 8-byte aligned, so checking slot_type[7] instead of slot_type[0] is required. While at it, this patch refactors the slot_type[0] == STACK_SPILL test into a new function is_spilled_reg() and change the slot_type[0] check to slot_type[7] check in there also. [1] https://reviews.llvm.org/D109073 Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210922004934.624194-1-kafai@fb.com |
|
Bixuan Cui
|
0e6491b559 |
bpf: Add oversize check before call kvcalloc()
Commit
|
|
|
Jakub Kicinski
|
19a31d7921 |
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
bpf-next 2021-08-31
We've added 116 non-merge commits during the last 17 day(s) which contain
a total of 126 files changed, 6813 insertions(+), 4027 deletions(-).
The main changes are:
1) Add opaque bpf_cookie to perf link which the program can read out again,
to be used in libbpf-based USDT library, from Andrii Nakryiko.
2) Add bpf_task_pt_regs() helper to access userspace pt_regs, from Daniel Xu.
3) Add support for UNIX stream type sockets for BPF sockmap, from Jiang Wang.
4) Allow BPF TCP congestion control progs to call bpf_setsockopt() e.g. to switch
to another congestion control algorithm during init, from Martin KaFai Lau.
5) Extend BPF iterator support for UNIX domain sockets, from Kuniyuki Iwashima.
6) Allow bpf_{set,get}sockopt() calls from setsockopt progs, from Prankur Gupta.
7) Add bpf_get_netns_cookie() helper for BPF_PROG_TYPE_{SOCK_OPS,CGROUP_SOCKOPT}
progs, from Xu Liu and Stanislav Fomichev.
8) Support for __weak typed ksyms in libbpf, from Hao Luo.
9) Shrink struct cgroup_bpf by 504 bytes through refactoring, from Dave Marchevsky.
10) Fix a smatch complaint in verifier's narrow load handling, from Andrey Ignatov.
11) Fix BPF interpreter's tail call count limit, from Daniel Borkmann.
12) Big batch of improvements to BPF selftests, from Magnus Karlsson, Li Zhijian,
Yucong Sun, Yonghong Song, Ilya Leoshkevich, Jussi Maki, Ilya Leoshkevich, others.
13) Another big batch to revamp XDP samples in order to give them consistent look
and feel, from Kumar Kartikeya Dwivedi.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (116 commits)
MAINTAINERS: Remove self from powerpc BPF JIT
selftests/bpf: Fix potential unreleased lock
samples: bpf: Fix uninitialized variable in xdp_redirect_cpu
selftests/bpf: Reduce more flakyness in sockmap_listen
bpf: Fix bpf-next builds without CONFIG_BPF_EVENTS
bpf: selftests: Add dctcp fallback test
bpf: selftests: Add connect_to_fd_opts to network_helpers
bpf: selftests: Add sk_state to bpf_tcp_helpers.h
bpf: tcp: Allow bpf-tcp-cc to call bpf_(get|set)sockopt
selftests: xsk: Preface options with opt
selftests: xsk: Make enums lower case
selftests: xsk: Generate packets from specification
selftests: xsk: Generate packet directly in umem
selftests: xsk: Simplify cleanup of ifobjects
selftests: xsk: Decrease sending speed
selftests: xsk: Validate tx stats on tx thread
selftests: xsk: Simplify packet validation in xsk tests
selftests: xsk: Rename worker_* functions that are not thread entry points
selftests: xsk: Disassociate umem size with packets sent
selftests: xsk: Remove end-of-test packet
...
====================
Link: https://lore.kernel.org/r/20210830225618.11634-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
|
|
Jakub Kicinski
|
97c78d0af5 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
drivers/net/wwan/mhi_wwan_mbim.c - drop the extra arg. Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
|
|
Andrey Ignatov
|
d7af7e497f |
bpf: Fix possible out of bound write in narrow load handling
Fix a verifier bug found by smatch static checker in [0].
This problem has never been seen in prod to my best knowledge. Fixing it
still seems to be a good idea since it's hard to say for sure whether
it's possible or not to have a scenario where a combination of
convert_ctx_access() and a narrow load would lead to an out of bound
write.
When narrow load is handled, one or two new instructions are added to
insn_buf array, but before it was only checked that
cnt >= ARRAY_SIZE(insn_buf)
And it's safe to add a new instruction to insn_buf[cnt++] only once. The
second try will lead to out of bound write. And this is what can happen
if `shift` is set.
Fix it by making sure that if the BPF_RSH instruction has to be added in
addition to BPF_AND then there is enough space for two more instructions
in insn_buf.
The full report [0] is below:
kernel/bpf/verifier.c:12304 convert_ctx_accesses() warn: offset 'cnt' incremented past end of array
kernel/bpf/verifier.c:12311 convert_ctx_accesses() warn: offset 'cnt' incremented past end of array
kernel/bpf/verifier.c
12282
12283 insn->off = off & ~(size_default - 1);
12284 insn->code = BPF_LDX | BPF_MEM | size_code;
12285 }
12286
12287 target_size = 0;
12288 cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
12289 &target_size);
12290 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
^^^^^^^^^^^^^^^^^^^^^^^^^^^
Bounds check.
12291 (ctx_field_size && !target_size)) {
12292 verbose(env, "bpf verifier is misconfigured\n");
12293 return -EINVAL;
12294 }
12295
12296 if (is_narrower_load && size < target_size) {
12297 u8 shift = bpf_ctx_narrow_access_offset(
12298 off, size, size_default) * 8;
12299 if (ctx_field_size <= 4) {
12300 if (shift)
12301 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
^^^^^
increment beyond end of array
12302 insn->dst_reg,
12303 shift);
--> 12304 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
^^^^^
out of bounds write
12305 (1 << size * 8) - 1);
12306 } else {
12307 if (shift)
12308 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
12309 insn->dst_reg,
12310 shift);
12311 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
^^^^^^^^^^^^^^^
Same.
12312 (1ULL << size * 8) - 1);
12313 }
12314 }
12315
12316 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
12317 if (!new_prog)
12318 return -ENOMEM;
12319
12320 delta += cnt - 1;
12321
12322 /* keep walking new program and skip insns we just inserted */
12323 env->prog = new_prog;
12324 insn = new_prog->insnsi + i + delta;
12325 }
12326
12327 return 0;
12328 }
[0] https://lore.kernel.org/bpf/20210817050843.GA21456@kili/
v1->v2:
- clarify that problem was only seen by static checker but not in prod;
Fixes:
|
|
|
Daniel Borkmann
|
5b029a32cf |
bpf: Fix ringbuf helper function compatibility
Commit |
|
|
Jakub Kicinski
|
f444fea789 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
drivers/ptp/Kconfig: |
|
Andrii Nakryiko
|
fb7dd8bca0 |
bpf: Refactor BPF_PROG_RUN into a function
Turn BPF_PROG_RUN into a proper always inlined function. No functional and performance changes are intended, but it makes it much easier to understand what's going on with how BPF programs are actually get executed. It's more obvious what types and callbacks are expected. Also extra () around input parameters can be dropped, as well as `__` variable prefixes intended to avoid naming collisions, which makes the code simpler to read and write. This refactoring also highlighted one extra issue. BPF_PROG_RUN is both a macro and an enum value (BPF_PROG_RUN == BPF_PROG_TEST_RUN). Turning BPF_PROG_RUN into a function causes naming conflict compilation error. So rename BPF_PROG_RUN into lower-case bpf_prog_run(), similar to bpf_prog_run_xdp(), bpf_prog_run_pin_on_cpu(), etc. All existing callers of BPF_PROG_RUN, the macro, are switched to bpf_prog_run() explicitly. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20210815070609.987780-2-andrii@kernel.org |
|
Ilya Leoshkevich
|
45c709f8c7 |
bpf: Clear zext_dst of dead insns
"access skb fields ok" verifier test fails on s390 with the "verifier bug. zext_dst is set, but no reg is defined" message. The first insns of the test prog are ... 0: 61 01 00 00 00 00 00 00 ldxw %r0,[%r1+0] 8: 35 00 00 01 00 00 00 00 jge %r0,0,1 10: 61 01 00 08 00 00 00 00 ldxw %r0,[%r1+8] ... and the 3rd one is dead (this does not look intentional to me, but this is a separate topic). sanitize_dead_code() converts dead insns into "ja -1", but keeps zext_dst. When opt_subreg_zext_lo32_rnd_hi32() tries to parse such an insn, it sees this discrepancy and bails. This problem can be seen only with JITs whose bpf_jit_needs_zext() returns true. Fix by clearning dead insns' zext_dst. The commits that contributed to this problem are: 1. |
|
|
Jakub Kicinski
|
d2e11fd2b7 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Conflicting commits, all resolutions pretty trivial: drivers/bus/mhi/pci_generic.c |
|
|
Daniel Borkmann
|
2039f26f3a |
bpf: Fix leakage due to insufficient speculative store bypass mitigation
Spectre v4 gadgets make use of memory disambiguation, which is a set of techniques that execute memory access instructions, that is, loads and stores, out of program order; Intel's optimization manual, section 2.4.4.5: A load instruction micro-op may depend on a preceding store. Many microarchitectures block loads until all preceding store addresses are known. The memory disambiguator predicts which loads will not depend on any previous stores. When the disambiguator predicts that a load does not have such a dependency, the load takes its data from the L1 data cache. Eventually, the prediction is verified. If an actual conflict is detected, the load and all succeeding instructions are re-executed. |
|
David S. Miller
|
5af84df962 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Conflicts are simple overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net> |
|
|
Daniel Borkmann
|
e042aa532c |
bpf: Fix pointer arithmetic mask tightening under state pruning
In |
|
|
Daniel Borkmann
|
59089a189e |
bpf: Remove superfluous aux sanitation on subprog rejection
Follow-up to
|
|
|
David S. Miller
|
82a1ffe57e |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-07-15 The following pull-request contains BPF updates for your *net-next* tree. We've added 45 non-merge commits during the last 15 day(s) which contain a total of 52 files changed, 3122 insertions(+), 384 deletions(-). The main changes are: 1) Introduce bpf timers, from Alexei. 2) Add sockmap support for unix datagram socket, from Cong. 3) Fix potential memleak and UAF in the verifier, from He. 4) Add bpf_get_func_ip helper, from Jiri. 5) Improvements to generic XDP mode, from Kumar. 6) Support for passing xdp_md to XDP programs in bpf_prog_run, from Zvi. =================== Signed-off-by: David S. Miller <davem@davemloft.net> |
|
|
Jiri Olsa
|
9ffd9f3ff7 |
bpf: Add bpf_get_func_ip helper for kprobe programs
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs, so it's now possible to call bpf_get_func_ip from both kprobe and kretprobe programs. Taking the caller's address from 'struct kprobe::addr', which is defined for both kprobe and kretprobe. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org |
|
|
Jiri Olsa
|
9b99edcae5 |
bpf: Add bpf_get_func_ip helper for tracing programs
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs, specifically for all trampoline attach types. The trampoline's caller IP address is stored in (ctx - 8) address. so there's no reason to actually call the helper, but rather fixup the call instruction and return [ctx - 8] value directly. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org |
|
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Alexei Starovoitov
|
7ddc80a476 |
bpf: Teach stack depth check about async callbacks.
Teach max stack depth checking algorithm about async callbacks that don't increase bpf program stack size. Also add sanity check that bpf_tail_call didn't sneak into async cb. It's impossible, since PTR_TO_CTX is not available in async cb, hence the program cannot contain bpf_tail_call(ctx,...); Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210715005417.78572-10-alexei.starovoitov@gmail.com |
|
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Alexei Starovoitov
|
bfc6bb74e4 |
bpf: Implement verifier support for validation of async callbacks.
bpf_for_each_map_elem() and bpf_timer_set_callback() helpers are relying on PTR_TO_FUNC infra in the verifier to validate addresses to subprograms and pass them into the helpers as function callbacks. In case of bpf_for_each_map_elem() the callback is invoked synchronously and the verifier treats it as a normal subprogram call by adding another bpf_func_state and new frame in __check_func_call(). bpf_timer_set_callback() doesn't invoke the callback directly. The subprogram will be called asynchronously from bpf_timer_cb(). Teach the verifier to validate such async callbacks as special kind of jump by pushing verifier state into stack and let pop_stack() process it. Special care needs to be taken during state pruning. The call insn doing bpf_timer_set_callback has to be a prune_point. Otherwise short timer callbacks might not have prune points in front of bpf_timer_set_callback() which means is_state_visited() will be called after this call insn is processed in __check_func_call(). Which means that another async_cb state will be pushed to be walked later and the verifier will eventually hit BPF_COMPLEXITY_LIMIT_JMP_SEQ limit. Since push_async_cb() looks like another push_stack() branch the infinite loop detection will trigger false positive. To recognize this case mark such states as in_async_callback_fn. To distinguish infinite loop in async callback vs the same callback called with different arguments for different map and timer add async_entry_cnt to bpf_func_state. Enforce return zero from async callbacks. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210715005417.78572-9-alexei.starovoitov@gmail.com |
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Alexei Starovoitov
|
86fc6ee6e2 |
bpf: Relax verifier recursion check.
In the following bpf subprogram:
static int timer_cb(void *map, void *key, void *value)
{
bpf_timer_set_callback(.., timer_cb);
}
the 'timer_cb' is a pointer to a function.
ld_imm64 insn is used to carry this pointer.
bpf_pseudo_func() returns true for such ld_imm64 insn.
Unlike bpf_for_each_map_elem() the bpf_timer_set_callback() is asynchronous.
Relax control flow check to allow such "recursion" that is seen as an infinite
loop by check_cfg(). The distinction between bpf_for_each_map_elem() the
bpf_timer_set_callback() is done in the follow up patch.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-8-alexei.starovoitov@gmail.com
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|
|
Alexei Starovoitov
|
3e8ce29850 |
bpf: Prevent pointer mismatch in bpf_timer_init.
bpf_timer_init() arguments are:
1. pointer to a timer (which is embedded in map element).
2. pointer to a map.
Make sure that pointer to a timer actually belongs to that map.
Use map_uid (which is unique id of inner map) to reject:
inner_map1 = bpf_map_lookup_elem(outer_map, key1)
inner_map2 = bpf_map_lookup_elem(outer_map, key2)
if (inner_map1 && inner_map2) {
timer = bpf_map_lookup_elem(inner_map1);
if (timer)
// mismatch would have been allowed
bpf_timer_init(timer, inner_map2);
}
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-6-alexei.starovoitov@gmail.com
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|
|
Alexei Starovoitov
|
68134668c1 |
bpf: Add map side support for bpf timers.
Restrict bpf timers to array, hash (both preallocated and kmalloced), and lru map types. The per-cpu maps with timers don't make sense, since 'struct bpf_timer' is a part of map value. bpf timers in per-cpu maps would mean that the number of timers depends on number of possible cpus and timers would not be accessible from all cpus. lpm map support can be added in the future. The timers in inner maps are supported. The bpf_map_update/delete_elem() helpers and sys_bpf commands cancel and free bpf_timer in a given map element. Similar to 'struct bpf_spin_lock' BTF is required and it is used to validate that map element indeed contains 'struct bpf_timer'. Make check_and_init_map_value() init both bpf_spin_lock and bpf_timer when map element data is reused in preallocated htab and lru maps. Teach copy_map_value() to support both bpf_spin_lock and bpf_timer in a single map element. There could be one of each, but not more than one. Due to 'one bpf_timer in one element' restriction do not support timers in global data, since global data is a map of single element, but from bpf program side it's seen as many global variables and restriction of single global timer would be odd. The sys_bpf map_freeze and sys_mmap syscalls are not allowed on maps with timers, since user space could have corrupted mmap element and crashed the kernel. The maps with timers cannot be readonly. Due to these restrictions search for bpf_timer in datasec BTF in case it was placed in the global data to report clear error. The previous patch allowed 'struct bpf_timer' as a first field in a map element only. Relax this restriction. Refactor lru map to s/bpf_lru_push_free/htab_lru_push_free/ to cancel and free the timer when lru map deletes an element as a part of it eviction algorithm. Make sure that bpf program cannot access 'struct bpf_timer' via direct load/store. The timer operation are done through helpers only. This is similar to 'struct bpf_spin_lock'. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210715005417.78572-5-alexei.starovoitov@gmail.com |
|
|
Alexei Starovoitov
|
b00628b1c7 |
bpf: Introduce bpf timers.
Introduce 'struct bpf_timer { __u64 :64; __u64 :64; };' that can be embedded
in hash/array/lru maps as a regular field and helpers to operate on it:
// Initialize the timer.
// First 4 bits of 'flags' specify clockid.
// Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
long bpf_timer_init(struct bpf_timer *timer, struct bpf_map *map, int flags);
// Configure the timer to call 'callback_fn' static function.
long bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
// Arm the timer to expire 'nsec' nanoseconds from the current time.
long bpf_timer_start(struct bpf_timer *timer, u64 nsec, u64 flags);
// Cancel the timer and wait for callback_fn to finish if it was running.
long bpf_timer_cancel(struct bpf_timer *timer);
Here is how BPF program might look like:
struct map_elem {
int counter;
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1000);
__type(key, int);
__type(value, struct map_elem);
} hmap SEC(".maps");
static int timer_cb(void *map, int *key, struct map_elem *val);
/* val points to particular map element that contains bpf_timer. */
SEC("fentry/bpf_fentry_test1")
int BPF_PROG(test1, int a)
{
struct map_elem *val;
int key = 0;
val = bpf_map_lookup_elem(&hmap, &key);
if (val) {
bpf_timer_init(&val->timer, &hmap, CLOCK_REALTIME);
bpf_timer_set_callback(&val->timer, timer_cb);
bpf_timer_start(&val->timer, 1000 /* call timer_cb2 in 1 usec */, 0);
}
}
This patch adds helper implementations that rely on hrtimers
to call bpf functions as timers expire.
The following patches add necessary safety checks.
Only programs with CAP_BPF are allowed to use bpf_timer.
The amount of timers used by the program is constrained by
the memcg recorded at map creation time.
The bpf_timer_init() helper needs explicit 'map' argument because inner maps
are dynamic and not known at load time. While the bpf_timer_set_callback() is
receiving hidden 'aux->prog' argument supplied by the verifier.
The prog pointer is needed to do refcnting of bpf program to make sure that
program doesn't get freed while the timer is armed. This approach relies on
"user refcnt" scheme used in prog_array that stores bpf programs for
bpf_tail_call. The bpf_timer_set_callback() will increment the prog refcnt which is
paired with bpf_timer_cancel() that will drop the prog refcnt. The
ops->map_release_uref is responsible for cancelling the timers and dropping
prog refcnt when user space reference to a map reaches zero.
This uref approach is done to make sure that Ctrl-C of user space process will
not leave timers running forever unless the user space explicitly pinned a map
that contained timers in bpffs.
bpf_timer_init() and bpf_timer_set_callback() will return -EPERM if map doesn't
have user references (is not held by open file descriptor from user space and
not pinned in bpffs).
The bpf_map_delete_elem() and bpf_map_update_elem() operations cancel
and free the timer if given map element had it allocated.
"bpftool map update" command can be used to cancel timers.
The 'struct bpf_timer' is explicitly __attribute__((aligned(8))) because
'__u64 :64' has 1 byte alignment of 8 byte padding.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-4-alexei.starovoitov@gmail.com
|
|
He Fengqing
|
75f0fc7b48 |
bpf: Fix potential memleak and UAF in the verifier.
In bpf_patch_insn_data(), we first use the bpf_patch_insn_single() to
insert new instructions, then use adjust_insn_aux_data() to adjust
insn_aux_data. If the old env->prog have no enough room for new inserted
instructions, we use bpf_prog_realloc to construct new_prog and free the
old env->prog.
There have two errors here. First, if adjust_insn_aux_data() return
ENOMEM, we should free the new_prog. Second, if adjust_insn_aux_data()
return ENOMEM, bpf_patch_insn_data() will return NULL, and env->prog has
been freed in bpf_prog_realloc, but we will use it in bpf_check().
So in this patch, we make the adjust_insn_aux_data() never fails. In
bpf_patch_insn_data(), we first pre-malloc memory for the new
insn_aux_data, then call bpf_patch_insn_single() to insert new
instructions, at last call adjust_insn_aux_data() to adjust
insn_aux_data.
Fixes:
|
|
|
Daniel Borkmann
|
5dd0a6b858 |
bpf: Fix tail_call_reachable rejection for interpreter when jit failed
During testing of |
|
John Fastabend
|
f263a81451 |
bpf: Track subprog poke descriptors correctly and fix use-after-free
Subprograms are calling map_poke_track(), but on program release there is no hook to call map_poke_untrack(). However, on program release, the aux memory (and poke descriptor table) is freed even though we still have a reference to it in the element list of the map aux data. When we run map_poke_run(), we then end up accessing free'd memory, triggering KASAN in prog_array_map_poke_run(): [...] [ 402.824689] BUG: KASAN: use-after-free in prog_array_map_poke_run+0xc2/0x34e [ 402.824698] Read of size 4 at addr ffff8881905a7940 by task hubble-fgs/4337 [ 402.824705] CPU: 1 PID: 4337 Comm: hubble-fgs Tainted: G I 5.12.0+ #399 [ 402.824715] Call Trace: [ 402.824719] dump_stack+0x93/0xc2 [ 402.824727] print_address_description.constprop.0+0x1a/0x140 [ 402.824736] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824740] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824744] kasan_report.cold+0x7c/0xd8 [ 402.824752] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824757] prog_array_map_poke_run+0xc2/0x34e [ 402.824765] bpf_fd_array_map_update_elem+0x124/0x1a0 [...] The elements concerned are walked as follows: for (i = 0; i < elem->aux->size_poke_tab; i++) { poke = &elem->aux->poke_tab[i]; [...] The access to size_poke_tab is a 4 byte read, verified by checking offsets in the KASAN dump: [ 402.825004] The buggy address belongs to the object at ffff8881905a7800 which belongs to the cache kmalloc-1k of size 1024 [ 402.825008] The buggy address is located 320 bytes inside of 1024-byte region [ffff8881905a7800, ffff8881905a7c00) The pahole output of bpf_prog_aux: struct bpf_prog_aux { [...] /* --- cacheline 5 boundary (320 bytes) --- */ u32 size_poke_tab; /* 320 4 */ [...] In general, subprograms do not necessarily manage their own data structures. For example, BTF func_info and linfo are just pointers to the main program structure. This allows reference counting and cleanup to be done on the latter which simplifies their management a bit. The aux->poke_tab struct, however, did not follow this logic. The initial proposed fix for this use-after-free bug further embedded poke data tracking into the subprogram with proper reference counting. However, Daniel and Alexei questioned why we were treating these objects special; I agree, its unnecessary. The fix here removes the per subprogram poke table allocation and map tracking and instead simply points the aux->poke_tab pointer at the main programs poke table. This way, map tracking is simplified to the main program and we do not need to manage them per subprogram. This also means, bpf_prog_free_deferred(), which unwinds the program reference counting and kfrees objects, needs to ensure that we don't try to double free the poke_tab when free'ing the subprog structures. This is easily solved by NULL'ing the poke_tab pointer. The second detail is to ensure that per subprogram JIT logic only does fixups on poke_tab[] entries it owns. To do this, we add a pointer in the poke structure to point at the subprogram value so JITs can easily check while walking the poke_tab structure if the current entry belongs to the current program. The aux pointer is stable and therefore suitable for such comparison. On the jit_subprogs() error path, we omit cleaning up the poke->aux field because these are only ever referenced from the JIT side, but on error we will never make it to the JIT, so its fine to leave them dangling. Removing these pointers would complicate the error path for no reason. However, we do need to untrack all poke descriptors from the main program as otherwise they could race with the freeing of JIT memory from the subprograms. Lastly, |
|
|
Jakub Kicinski
|
b6df00789e |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Trivial conflict in net/netfilter/nf_tables_api.c. Duplicate fix in tools/testing/selftests/net/devlink_port_split.py - take the net-next version. skmsg, and L4 bpf - keep the bpf code but remove the flags and err params. Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
|
|
John Fastabend
|
7506d211b9 |
bpf: Fix null ptr deref with mixed tail calls and subprogs
The sub-programs prog->aux->poke_tab[] is populated in jit_subprogs() and
then used when emitting 'BPF_JMP|BPF_TAIL_CALL' insn->code from the
individual JITs. The poke_tab[] to use is stored in the insn->imm by
the code adding it to that array slot. The JIT then uses imm to find the
right entry for an individual instruction. In the x86 bpf_jit_comp.c
this is done by calling emit_bpf_tail_call_direct with the poke_tab[]
of the imm value.
However, we observed the below null-ptr-deref when mixing tail call
programs with subprog programs. For this to happen we just need to
mix bpf-2-bpf calls and tailcalls with some extra calls or instructions
that would be patched later by one of the fixup routines. So whats
happening?
Before the fixup_call_args() -- where the jit op is done -- various
code patching is done by do_misc_fixups(). This may increase the
insn count, for example when we patch map_lookup_up using map_gen_lookup
hook. This does two things. First, it means the instruction index,
insn_idx field, of a tail call instruction will move by a 'delta'.
In verifier code,
struct bpf_jit_poke_descriptor desc = {
.reason = BPF_POKE_REASON_TAIL_CALL,
.tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
.tail_call.key = bpf_map_key_immediate(aux),
.insn_idx = i + delta,
};
Then subprog start values subprog_info[i].start will be updated
with the delta and any poke descriptor index will also be updated
with the delta in adjust_poke_desc(). If we look at the adjust
subprog starts though we see its only adjusted when the delta
occurs before the new instructions,
/* NOTE: fake 'exit' subprog should be updated as well. */
for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start <= off)
continue;
Earlier subprograms are not changed because their start values
are not moved. But, adjust_poke_desc() does the offset + delta
indiscriminately. The result is poke descriptors are potentially
corrupted.
Then in jit_subprogs() we only populate the poke_tab[]
when the above insn_idx is less than the next subprogram start. From
above we corrupted our insn_idx so we might incorrectly assume a
poke descriptor is not used in a subprogram omitting it from the
subprogram. And finally when the jit runs it does the deref of poke_tab
when emitting the instruction and crashes with below. Because earlier
step omitted the poke descriptor.
The fix is straight forward with above context. Simply move same logic
from adjust_subprog_starts() into adjust_poke_descs() and only adjust
insn_idx when needed.
[ 82.396354] bpf_testmod: version magic '5.12.0-rc2alu+ SMP preempt mod_unload ' should be '5.12.0+ SMP preempt mod_unload '
[ 82.623001] loop10: detected capacity change from 0 to 8
[ 88.487424] ==================================================================
[ 88.487438] BUG: KASAN: null-ptr-deref in do_jit+0x184a/0x3290
[ 88.487455] Write of size 8 at addr 0000000000000008 by task test_progs/5295
[ 88.487471] CPU: 7 PID: 5295 Comm: test_progs Tainted: G I 5.12.0+ #386
[ 88.487483] Hardware name: Dell Inc. Precision 5820 Tower/002KVM, BIOS 1.9.2 01/24/2019
[ 88.487490] Call Trace:
[ 88.487498] dump_stack+0x93/0xc2
[ 88.487515] kasan_report.cold+0x5f/0xd8
[ 88.487530] ? do_jit+0x184a/0x3290
[ 88.487542] do_jit+0x184a/0x3290
...
[ 88.487709] bpf_int_jit_compile+0x248/0x810
...
[ 88.487765] bpf_check+0x3718/0x5140
...
[ 88.487920] bpf_prog_load+0xa22/0xf10
Fixes:
|
|
|
Jakub Kicinski
|
adc2e56ebe |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Trivial conflicts in net/can/isotp.c and tools/testing/selftests/net/mptcp/mptcp_connect.sh scaled_ppm_to_ppb() was moved from drivers/ptp/ptp_clock.c to include/linux/ptp_clock_kernel.h in -next so re-apply the fix there. Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
|
|
David S. Miller
|
a52171ae7b |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says: ==================== pull-request: bpf-next 2021-06-17 The following pull-request contains BPF updates for your *net-next* tree. We've added 50 non-merge commits during the last 25 day(s) which contain a total of 148 files changed, 4779 insertions(+), 1248 deletions(-). The main changes are: 1) BPF infrastructure to migrate TCP child sockets from a listener to another in the same reuseport group/map, from Kuniyuki Iwashima. 2) Add a provably sound, faster and more precise algorithm for tnum_mul() as noted in https://arxiv.org/abs/2105.05398, from Harishankar Vishwanathan. 3) Streamline error reporting changes in libbpf as planned out in the 'libbpf: the road to v1.0' effort, from Andrii Nakryiko. 4) Add broadcast support to xdp_redirect_map(), from Hangbin Liu. 5) Extends bpf_map_lookup_and_delete_elem() functionality to 4 more map types, that is, {LRU_,PERCPU_,LRU_PERCPU_,}HASH, from Denis Salopek. 6) Support new LLVM relocations in libbpf to make them more linker friendly, also add a doc to describe the BPF backend relocations, from Yonghong Song. 7) Silence long standing KUBSAN complaints on register-based shifts in interpreter, from Daniel Borkmann and Eric Biggers. 8) Add dummy PT_REGS macros in libbpf to fail BPF program compilation when target arch cannot be determined, from Lorenz Bauer. 9) Extend AF_XDP to support large umems with 1M+ pages, from Magnus Karlsson. 10) Fix two minor libbpf tc BPF API issues, from Kumar Kartikeya Dwivedi. 11) Move libbpf BPF_SEQ_PRINTF/BPF_SNPRINTF macros that can be used by BPF programs to bpf_helpers.h header, from Florent Revest. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
|
|
Daniel Borkmann
|
9183671af6 |
bpf: Fix leakage under speculation on mispredicted branches
The verifier only enumerates valid control-flow paths and skips paths that
are unreachable in the non-speculative domain. And so it can miss issues
under speculative execution on mispredicted branches.
For example, a type confusion has been demonstrated with the following
crafted program:
// r0 = pointer to a map array entry
// r6 = pointer to readable stack slot
// r9 = scalar controlled by attacker
1: r0 = *(u64 *)(r0) // cache miss
2: if r0 != 0x0 goto line 4
3: r6 = r9
4: if r0 != 0x1 goto line 6
5: r9 = *(u8 *)(r6)
6: // leak r9
Since line 3 runs iff r0 == 0 and line 5 runs iff r0 == 1, the verifier
concludes that the pointer dereference on line 5 is safe. But: if the
attacker trains both the branches to fall-through, such that the following
is speculatively executed ...
r6 = r9
r9 = *(u8 *)(r6)
// leak r9
... then the program will dereference an attacker-controlled value and could
leak its content under speculative execution via side-channel. This requires
to mistrain the branch predictor, which can be rather tricky, because the
branches are mutually exclusive. However such training can be done at
congruent addresses in user space using different branches that are not
mutually exclusive. That is, by training branches in user space ...
A: if r0 != 0x0 goto line C
B: ...
C: if r0 != 0x0 goto line D
D: ...
... such that addresses A and C collide to the same CPU branch prediction
entries in the PHT (pattern history table) as those of the BPF program's
lines 2 and 4, respectively. A non-privileged attacker could simply brute
force such collisions in the PHT until observing the attack succeeding.
Alternative methods to mistrain the branch predictor are also possible that
avoid brute forcing the collisions in the PHT. A reliable attack has been
demonstrated, for example, using the following crafted program:
// r0 = pointer to a [control] map array entry
// r7 = *(u64 *)(r0 + 0), training/attack phase
// r8 = *(u64 *)(r0 + 8), oob address
// [...]
// r0 = pointer to a [data] map array entry
1: if r7 == 0x3 goto line 3
2: r8 = r0
// crafted sequence of conditional jumps to separate the conditional
// branch in line 193 from the current execution flow
3: if r0 != 0x0 goto line 5
4: if r0 == 0x0 goto exit
5: if r0 != 0x0 goto line 7
6: if r0 == 0x0 goto exit
[...]
187: if r0 != 0x0 goto line 189
188: if r0 == 0x0 goto exit
// load any slowly-loaded value (due to cache miss in phase 3) ...
189: r3 = *(u64 *)(r0 + 0x1200)
// ... and turn it into known zero for verifier, while preserving slowly-
// loaded dependency when executing:
190: r3 &= 1
191: r3 &= 2
// speculatively bypassed phase dependency
192: r7 += r3
193: if r7 == 0x3 goto exit
194: r4 = *(u8 *)(r8 + 0)
// leak r4
As can be seen, in training phase (phase != 0x3), the condition in line 1
turns into false and therefore r8 with the oob address is overridden with
the valid map value address, which in line 194 we can read out without
issues. However, in attack phase, line 2 is skipped, and due to the cache
miss in line 189 where the map value is (zeroed and later) added to the
phase register, the condition in line 193 takes the fall-through path due
to prior branch predictor training, where under speculation, it'll load the
byte at oob address r8 (unknown scalar type at that point) which could then
be leaked via side-channel.
One way to mitigate these is to 'branch off' an unreachable path, meaning,
the current verification path keeps following the is_branch_taken() path
and we push the other branch to the verification stack. Given this is
unreachable from the non-speculative domain, this branch's vstate is
explicitly marked as speculative. This is needed for two reasons: i) if
this path is solely seen from speculative execution, then we later on still
want the dead code elimination to kick in in order to sanitize these
instructions with jmp-1s, and ii) to ensure that paths walked in the
non-speculative domain are not pruned from earlier walks of paths walked in
the speculative domain. Additionally, for robustness, we mark the registers
which have been part of the conditional as unknown in the speculative path
given there should be no assumptions made on their content.
The fix in here mitigates type confusion attacks described earlier due to
i) all code paths in the BPF program being explored and ii) existing
verifier logic already ensuring that given memory access instruction
references one specific data structure.
An alternative to this fix that has also been looked at in this scope was to
mark aux->alu_state at the jump instruction with a BPF_JMP_TAKEN state as
well as direction encoding (always-goto, always-fallthrough, unknown), such
that mixing of different always-* directions themselves as well as mixing of
always-* with unknown directions would cause a program rejection by the
verifier, e.g. programs with constructs like 'if ([...]) { x = 0; } else
{ x = 1; }' with subsequent 'if (x == 1) { [...] }'. For unprivileged, this
would result in only single direction always-* taken paths, and unknown taken
paths being allowed, such that the former could be patched from a conditional
jump to an unconditional jump (ja). Compared to this approach here, it would
have two downsides: i) valid programs that otherwise are not performing any
pointer arithmetic, etc, would potentially be rejected/broken, and ii) we are
required to turn off path pruning for unprivileged, where both can be avoided
in this work through pushing the invalid branch to the verification stack.
The issue was originally discovered by Adam and Ofek, and later independently
discovered and reported as a result of Benedict and Piotr's research work.
Fixes:
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Daniel Borkmann
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fe9a5ca7e3 |
bpf: Do not mark insn as seen under speculative path verification
... in such circumstances, we do not want to mark the instruction as seen given the goal is still to jmp-1 rewrite/sanitize dead code, if it is not reachable from the non-speculative path verification. We do however want to verify it for safety regardless. With the patch as-is all the insns that have been marked as seen before the patch will also be marked as seen after the patch (just with a potentially different non-zero count). An upcoming patch will also verify paths that are unreachable in the non-speculative domain, hence this extension is needed. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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d203b0fd86 |
bpf: Inherit expanded/patched seen count from old aux data
Instead of relying on current env->pass_cnt, use the seen count from the old aux data in adjust_insn_aux_data(), and expand it to the new range of patched instructions. This change is valid given we always expand 1:n with n>=1, so what applies to the old/original instruction needs to apply for the replacement as well. Not relying on env->pass_cnt is a prerequisite for a later change where we want to avoid marking an instruction seen when verified under speculative execution path. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Jakub Kicinski
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5ada57a9a6 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
cdc-wdm: s/kill_urbs/poison_urbs/ to fix build Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Daniel Borkmann
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a703619127 |
bpf: No need to simulate speculative domain for immediates
In
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Daniel Borkmann
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bb01a1bba5 |
bpf: Fix mask direction swap upon off reg sign change
Masking direction as indicated via mask_to_left is considered to be
calculated once and then used to derive pointer limits. Thus, this
needs to be placed into bpf_sanitize_info instead so we can pass it
to sanitize_ptr_alu() call after the pointer move. Piotr noticed a
corner case where the off reg causes masking direction change which
then results in an incorrect final aux->alu_limit.
Fixes:
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Daniel Borkmann
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3d0220f686 |
bpf: Wrap aux data inside bpf_sanitize_info container
Add a container structure struct bpf_sanitize_info which holds the current aux info, and update call-sites to sanitize_ptr_alu() to pass it in. This is needed for passing in additional state later on. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Zhen Lei
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8fb33b6055 |
bpf: Fix spelling mistakes
Fix some spelling mistakes in comments: aother ==> another Netiher ==> Neither desribe ==> describe intializing ==> initializing funciton ==> function wont ==> won't and move the word 'the' at the end to the next line accross ==> across pathes ==> paths triggerred ==> triggered excute ==> execute ether ==> either conervative ==> conservative convetion ==> convention markes ==> marks interpeter ==> interpreter Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210525025659.8898-2-thunder.leizhen@huawei.com |
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Yinjun Zhang
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ceb11679d9 |
bpf, offload: Reorder offload callback 'prepare' in verifier
Commit |
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Alexei Starovoitov
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387544bfa2 |
bpf: Introduce fd_idx
Typical program loading sequence involves creating bpf maps and applying map FDs into bpf instructions in various places in the bpf program. This job is done by libbpf that is using compiler generated ELF relocations to patch certain instruction after maps are created and BTFs are loaded. The goal of fd_idx is to allow bpf instructions to stay immutable after compilation. At load time the libbpf would still create maps as usual, but it wouldn't need to patch instructions. It would store map_fds into __u32 fd_array[] and would pass that pointer to sys_bpf(BPF_PROG_LOAD). Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210514003623.28033-9-alexei.starovoitov@gmail.com |
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Alexei Starovoitov
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af2ac3e13e |
bpf: Prepare bpf syscall to be used from kernel and user space.
With the help from bpfptr_t prepare relevant bpf syscall commands to be used from kernel and user space. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210514003623.28033-4-alexei.starovoitov@gmail.com |
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Alexei Starovoitov
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79a7f8bdb1 |
bpf: Introduce bpf_sys_bpf() helper and program type.
Add placeholders for bpf_sys_bpf() helper and new program type. Make sure to check that expected_attach_type is zero for future extensibility. Allow tracing helper functions to be used in this program type, since they will only execute from user context via bpf_prog_test_run. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210514003623.28033-2-alexei.starovoitov@gmail.com |
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Jiri Olsa
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35e3815fa8 |
bpf: Add deny list of btf ids check for tracing programs
The recursion check in __bpf_prog_enter and __bpf_prog_exit
leaves some (not inlined) functions unprotected:
In __bpf_prog_enter:
- migrate_disable is called before prog->active is checked
In __bpf_prog_exit:
- migrate_enable,rcu_read_unlock_strict are called after
prog->active is decreased
When attaching trampoline to them we get panic like:
traps: PANIC: double fault, error_code: 0x0
double fault: 0000 [#1] SMP PTI
RIP: 0010:__bpf_prog_enter+0x4/0x50
...
Call Trace:
<IRQ>
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
...
Fixing this by adding deny list of btf ids for tracing
programs and checking btf id during program verification.
Adding above functions to this list.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210429114712.43783-1-jolsa@kernel.org
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Daniel Borkmann
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049c4e1371 |
bpf: Fix alu32 const subreg bound tracking on bitwise operations
Fix a bug in the verifier's scalar32_min_max_*() functions which leads to
incorrect tracking of 32 bit bounds for the simulation of and/or/xor bitops.
When both the src & dst subreg is a known constant, then the assumption is
that scalar_min_max_*() will take care to update bounds correctly. However,
this is not the case, for example, consider a register R2 which has a tnum
of 0xffffffff00000000, meaning, lower 32 bits are known constant and in this
case of value 0x00000001. R2 is then and'ed with a register R3 which is a
64 bit known constant, here, 0x100000002.
What can be seen in line '10:' is that 32 bit bounds reach an invalid state
where {u,s}32_min_value > {u,s}32_max_value. The reason is scalar32_min_max_*()
delegates 32 bit bounds updates to scalar_min_max_*(), however, that really
only takes place when both the 64 bit src & dst register is a known constant.
Given scalar32_min_max_*() is intended to be designed as closely as possible
to scalar_min_max_*(), update the 32 bit bounds in this situation through
__mark_reg32_known() which will set all {u,s}32_{min,max}_value to the correct
constant, which is 0x00000000 after the fix (given 0x00000001 & 0x00000002 in
32 bit space). This is possible given var32_off already holds the final value
as dst_reg->var_off is updated before calling scalar32_min_max_*().
Before fix, invalid tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=1,s32_max_value=0,u32_min_value=1,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
After fix, correct tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=0,s32_max_value=0,u32_min_value=0,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
Fixes:
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Lorenz Bauer
|
c9e73e3d2b |
bpf: verifier: Allocate idmap scratch in verifier env
func_states_equal makes a very short lived allocation for idmap, probably because it's too large to fit on the stack. However the function is called quite often, leading to a lot of alloc / free churn. Replace the temporary allocation with dedicated scratch space in struct bpf_verifier_env. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Edward Cree <ecree.xilinx@gmail.com> Link: https://lore.kernel.org/bpf/20210429134656.122225-4-lmb@cloudflare.com |
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Lorenz Bauer
|
06ab6a5055 |
bpf: verifier: Use copy_array for jmp_history
Eliminate a couple needless kfree / kmalloc cycles by using copy_array for jmp_history. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210429134656.122225-3-lmb@cloudflare.com |
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Lorenz Bauer
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c69431aab6 |
bpf: verifier: Improve function state reallocation
Resizing and copying stack and reference tracking state currently does a lot of kfree / kmalloc when the size of the tracked set changes. The logic in copy_*_state and realloc_*_state is also hard to follow. Refactor this into two core functions. copy_array copies from a source into a destination. It avoids reallocation by taking the allocated size of the destination into account via ksize(). The function is essentially krealloc_array, with the difference that the contents of dst are not preserved. realloc_array changes the size of an array and zeroes newly allocated items. Contrary to krealloc both functions don't free the destination if the size is zero. Instead we rely on free_func_state to clean up. realloc_stack_state is renamed to grow_stack_state to better convey that it never shrinks the stack state. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210429134656.122225-2-lmb@cloudflare.com |
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Daniel Borkmann
|
801c6058d1 |
bpf: Fix leakage of uninitialized bpf stack under speculation
The current implemented mechanisms to mitigate data disclosure under
speculation mainly address stack and map value oob access from the
speculative domain. However, Piotr discovered that uninitialized BPF
stack is not protected yet, and thus old data from the kernel stack,
potentially including addresses of kernel structures, could still be
extracted from that 512 bytes large window. The BPF stack is special
compared to map values since it's not zero initialized for every
program invocation, whereas map values /are/ zero initialized upon
their initial allocation and thus cannot leak any prior data in either
domain. In the non-speculative domain, the verifier ensures that every
stack slot read must have a prior stack slot write by the BPF program
to avoid such data leaking issue.
However, this is not enough: for example, when the pointer arithmetic
operation moves the stack pointer from the last valid stack offset to
the first valid offset, the sanitation logic allows for any intermediate
offsets during speculative execution, which could then be used to
extract any restricted stack content via side-channel.
Given for unprivileged stack pointer arithmetic the use of unknown
but bounded scalars is generally forbidden, we can simply turn the
register-based arithmetic operation into an immediate-based arithmetic
operation without the need for masking. This also gives the benefit
of reducing the needed instructions for the operation. Given after
the work in
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Daniel Borkmann
|
b9b34ddbe2 |
bpf: Fix masking negation logic upon negative dst register
The negation logic for the case where the off_reg is sitting in the
dst register is not correct given then we cannot just invert the add
to a sub or vice versa. As a fix, perform the final bitwise and-op
unconditionally into AX from the off_reg, then move the pointer from
the src to dst and finally use AX as the source for the original
pointer arithmetic operation such that the inversion yields a correct
result. The single non-AX mov in between is possible given constant
blinding is retaining it as it's not an immediate based operation.
Fixes:
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Florent Revest
|
48cac3f4a9 |
bpf: Implement formatted output helpers with bstr_printf
BPF has three formatted output helpers: bpf_trace_printk, bpf_seq_printf and bpf_snprintf. Their signatures specify that all arguments are provided from the BPF world as u64s (in an array or as registers). All of these helpers are currently implemented by calling functions such as snprintf() whose signatures take a variable number of arguments, then placed in a va_list by the compiler to call vsnprintf(). "d9c9e4db bpf: Factorize bpf_trace_printk and bpf_seq_printf" introduced a bpf_printf_prepare function that fills an array of u64 sanitized arguments with an array of "modifiers" which indicate what the "real" size of each argument should be (given by the format specifier). The BPF_CAST_FMT_ARG macro consumes these arrays and casts each argument to its real size. However, the C promotion rules implicitely cast them all back to u64s. Therefore, the arguments given to snprintf are u64s and the va_list constructed by the compiler will use 64 bits for each argument. On 64 bit machines, this happens to work well because 32 bit arguments in va_lists need to occupy 64 bits anyway, but on 32 bit architectures this breaks the layout of the va_list expected by the called function and mangles values. In "88a5c690b6 bpf: fix bpf_trace_printk on 32 bit archs", this problem had been solved for bpf_trace_printk only with a "horrid workaround" that emitted multiple calls to trace_printk where each call had different argument types and generated different va_list layouts. One of the call would be dynamically chosen at runtime. This was ok with the 3 arguments that bpf_trace_printk takes but bpf_seq_printf and bpf_snprintf accept up to 12 arguments. Because this approach scales code exponentially, it is not a viable option anymore. Because the promotion rules are part of the language and because the construction of a va_list is an arch-specific ABI, it's best to just avoid variadic arguments and va_lists altogether. Thankfully the kernel's snprintf() has an alternative in the form of bstr_printf() that accepts arguments in a "binary buffer representation". These binary buffers are currently created by vbin_printf and used in the tracing subsystem to split the cost of printing into two parts: a fast one that only dereferences and remembers values, and a slower one, called later, that does the pretty-printing. This patch refactors bpf_printf_prepare to construct binary buffers of arguments consumable by bstr_printf() instead of arrays of arguments and modifiers. This gets rid of BPF_CAST_FMT_ARG and greatly simplifies the bpf_printf_prepare usage but there are a few gotchas that change how bpf_printf_prepare needs to do things. Currently, bpf_printf_prepare uses a per cpu temporary buffer as a generic storage for strings and IP addresses. With this refactoring, the temporary buffers now holds all the arguments in a structured binary format. To comply with the format expected by bstr_printf, certain format specifiers also need to be pre-formatted: %pB and %pi6/%pi4/%pI4/%pI6. Because vsnprintf subroutines for these specifiers are hard to expose, we pre-format these arguments with calls to snprintf(). Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210427174313.860948-3-revest@chromium.org |
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Daniel Borkmann
|
10bf4e8316 |
bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds
Similarly as |
|
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David S. Miller
|
5f6c2f536d |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-04-23 The following pull-request contains BPF updates for your *net-next* tree. We've added 69 non-merge commits during the last 22 day(s) which contain a total of 69 files changed, 3141 insertions(+), 866 deletions(-). The main changes are: 1) Add BPF static linker support for extern resolution of global, from Andrii. 2) Refine retval for bpf_get_task_stack helper, from Dave. 3) Add a bpf_snprintf helper, from Florent. 4) A bunch of miscellaneous improvements from many developers. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Florent Revest
|
a8fad73e33 |
bpf: Remove unnecessary map checks for ARG_PTR_TO_CONST_STR
reg->type is enforced by check_reg_type() and map should never be NULL (it would already have been dereferenced anyway) so these checks are unnecessary. Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210422235543.4007694-3-revest@chromium.org |
|
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Florent Revest
|
8e8ee109b0 |
bpf: Notify user if we ever hit a bpf_snprintf verifier bug
In check_bpf_snprintf_call(), a map_direct_value_addr() of the fmt map should never fail because it has already been checked by ARG_PTR_TO_CONST_STR. But if it ever fails, it's better to error out with an explicit debug message rather than silently fail. Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210422235543.4007694-2-revest@chromium.org |
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Dave Marchevsky
|
fd0b88f73f |
bpf: Refine retval for bpf_get_task_stack helper
Verifier can constrain the min/max bounds of bpf_get_task_stack's return value more tightly than the default tnum_unknown. Like bpf_get_stack, return value is num bytes written into a caller-supplied buf, or error, so do_refine_retval_range will work. Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20210416204704.2816874-2-davemarchevsky@fb.com |
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Florent Revest
|
7b15523a98 |
bpf: Add a bpf_snprintf helper
The implementation takes inspiration from the existing bpf_trace_printk helper but there are a few differences: To allow for a large number of format-specifiers, parameters are provided in an array, like in bpf_seq_printf. Because the output string takes two arguments and the array of parameters also takes two arguments, the format string needs to fit in one argument. Thankfully, ARG_PTR_TO_CONST_STR is guaranteed to point to a zero-terminated read-only map so we don't need a format string length arg. Because the format-string is known at verification time, we also do a first pass of format string validation in the verifier logic. This makes debugging easier. Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210419155243.1632274-4-revest@chromium.org |
|
|
Florent Revest
|
fff13c4bb6 |
bpf: Add a ARG_PTR_TO_CONST_STR argument type
This type provides the guarantee that an argument is going to be a const pointer to somewhere in a read-only map value. It also checks that this pointer is followed by a zero character before the end of the map value. Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210419155243.1632274-3-revest@chromium.org |
|
|
Jakub Kicinski
|
8203c7ce4e |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c - keep the ZC code, drop the code related to reinit net/bridge/netfilter/ebtables.c - fix build after move to net_generic Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Daniel Borkmann
|
7fedb63a83 |
bpf: Tighten speculative pointer arithmetic mask
This work tightens the offset mask we use for unprivileged pointer arithmetic in order to mitigate a corner case reported by Piotr and Benedict where in the speculative domain it is possible to advance, for example, the map value pointer by up to value_size-1 out-of-bounds in order to leak kernel memory via side-channel to user space. Before this change, the computed ptr_limit for retrieve_ptr_limit() helper represents largest valid distance when moving pointer to the right or left which is then fed as aux->alu_limit to generate masking instructions against the offset register. After the change, the derived aux->alu_limit represents the largest potential value of the offset register which we mask against which is just a narrower subset of the former limit. For minimal complexity, we call sanitize_ptr_alu() from 2 observation points in adjust_ptr_min_max_vals(), that is, before and after the simulated alu operation. In the first step, we retieve the alu_state and alu_limit before the operation as well as we branch-off a verifier path and push it to the verification stack as we did before which checks the dst_reg under truncation, in other words, when the speculative domain would attempt to move the pointer out-of-bounds. In the second step, we retrieve the new alu_limit and calculate the absolute distance between both. Moreover, we commit the alu_state and final alu_limit via update_alu_sanitation_state() to the env's instruction aux data, and bail out from there if there is a mismatch due to coming from different verification paths with different states. Reported-by: Piotr Krysiuk <piotras@gmail.com> Reported-by: Benedict Schlueter <benedict.schlueter@rub.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Benedict Schlueter <benedict.schlueter@rub.de> |
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Daniel Borkmann
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f528819334 |
bpf: Move sanitize_val_alu out of op switch
Add a small sanitize_needed() helper function and move sanitize_val_alu() out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu() as well out of its opcode switch so this helps to streamline both. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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073815b756 |
bpf: Refactor and streamline bounds check into helper
Move the bounds check in adjust_ptr_min_max_vals() into a small helper named sanitize_check_bounds() in order to simplify the former a bit. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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a6aaece00a |
bpf: Improve verifier error messages for users
Consolidate all error handling and provide more user-friendly error messages from sanitize_ptr_alu() and sanitize_val_alu(). Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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b658bbb844 |
bpf: Rework ptr_limit into alu_limit and add common error path
Small refactor with no semantic changes in order to consolidate the max ptr_limit boundary check. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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24c109bb15 |
bpf: Ensure off_reg has no mixed signed bounds for all types
The mixed signed bounds check really belongs into retrieve_ptr_limit()
instead of outside of it in adjust_ptr_min_max_vals(). The reason is
that this check is not tied to PTR_TO_MAP_VALUE only, but to all pointer
types that we handle in retrieve_ptr_limit() and given errors from the latter
propagate back to adjust_ptr_min_max_vals() and lead to rejection of the
program, it's a better place to reside to avoid anything slipping through
for future types. The reason why we must reject such off_reg is that we
otherwise would not be able to derive a mask, see details in
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Daniel Borkmann
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6f55b2f2a1 |
bpf: Move off_reg into sanitize_ptr_alu
Small refactor to drag off_reg into sanitize_ptr_alu(), so we later on can use off_reg for generalizing some of the checks for all pointer types. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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9601148392 |
bpf: Use correct permission flag for mixed signed bounds arithmetic
We forbid adding unknown scalars with mixed signed bounds due to the
spectre v1 masking mitigation. Hence this also needs bypass_spec_v1
flag instead of allow_ptr_leaks.
Fixes:
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Jakub Kicinski
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8859a44ea0 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Conflicts: MAINTAINERS - keep Chandrasekar drivers/net/ethernet/mellanox/mlx5/core/en_main.c - simple fix + trust the code re-added to param.c in -next is fine include/linux/bpf.h - trivial include/linux/ethtool.h - trivial, fix kdoc while at it include/linux/skmsg.h - move to relevant place in tcp.c, comment re-wrapped net/core/skmsg.c - add the sk = sk // sk = NULL around calls net/tipc/crypto.c - trivial Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
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Martin KaFai Lau
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e6ac2450d6 |
bpf: Support bpf program calling kernel function
This patch adds support to BPF verifier to allow bpf program calling kernel function directly. The use case included in this set is to allow bpf-tcp-cc to directly call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()"). Those functions have already been used by some kernel tcp-cc implementations. This set will also allow the bpf-tcp-cc program to directly call the kernel tcp-cc implementation, For example, a bpf_dctcp may only want to implement its own dctcp_cwnd_event() and reuse other dctcp_*() directly from the kernel tcp_dctcp.c instead of reimplementing (or copy-and-pasting) them. The tcp-cc kernel functions mentioned above will be white listed for the struct_ops bpf-tcp-cc programs to use in a later patch. The white listed functions are not bounded to a fixed ABI contract. Those functions have already been used by the existing kernel tcp-cc. If any of them has changed, both in-tree and out-of-tree kernel tcp-cc implementations have to be changed. The same goes for the struct_ops bpf-tcp-cc programs which have to be adjusted accordingly. This patch is to make the required changes in the bpf verifier. First change is in btf.c, it adds a case in "btf_check_func_arg_match()". When the passed in "btf->kernel_btf == true", it means matching the verifier regs' states with a kernel function. This will handle the PTR_TO_BTF_ID reg. It also maps PTR_TO_SOCK_COMMON, PTR_TO_SOCKET, and PTR_TO_TCP_SOCK to its kernel's btf_id. In the later libbpf patch, the insn calling a kernel function will look like: insn->code == (BPF_JMP | BPF_CALL) insn->src_reg == BPF_PSEUDO_KFUNC_CALL /* <- new in this patch */ insn->imm == func_btf_id /* btf_id of the running kernel */ [ For the future calling function-in-kernel-module support, an array of module btf_fds can be passed at the load time and insn->off can be used to index into this array. ] At the early stage of verifier, the verifier will collect all kernel function calls into "struct bpf_kfunc_desc". Those descriptors are stored in "prog->aux->kfunc_tab" and will be available to the JIT. Since this "add" operation is similar to the current "add_subprog()" and looking for the same insn->code, they are done together in the new "add_subprog_and_kfunc()". In the "do_check()" stage, the new "check_kfunc_call()" is added to verify the kernel function call instruction: 1. Ensure the kernel function can be used by a particular BPF_PROG_TYPE. A new bpf_verifier_ops "check_kfunc_call" is added to do that. The bpf-tcp-cc struct_ops program will implement this function in a later patch. 2. Call "btf_check_kfunc_args_match()" to ensure the regs can be used as the args of a kernel function. 3. Mark the regs' type, subreg_def, and zext_dst. At the later do_misc_fixups() stage, the new fixup_kfunc_call() will replace the insn->imm with the function address (relative to __bpf_call_base). If needed, the jit can find the btf_func_model by calling the new bpf_jit_find_kfunc_model(prog, insn). With the imm set to the function address, "bpftool prog dump xlated" will be able to display the kernel function calls the same way as it displays other bpf helper calls. gpl_compatible program is required to call kernel function. This feature currently requires JIT. The verifier selftests are adjusted because of the changes in the verbose log in add_subprog_and_kfunc(). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210325015142.1544736-1-kafai@fb.com |
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Martin KaFai Lau
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34747c4120 |
bpf: Refactor btf_check_func_arg_match
This patch moved the subprog specific logic from btf_check_func_arg_match() to the new btf_check_subprog_arg_match(). The core logic is left in btf_check_func_arg_match() which will be reused later to check the kernel function call. The "if (!btf_type_is_ptr(t))" is checked first to improve the indentation which will be useful for a later patch. Some of the "btf_kind_str[]" usages is replaced with the shortcut "btf_type_str(t)". Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210325015136.1544504-1-kafai@fb.com |
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Martin KaFai Lau
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e16301fbe1 |
bpf: Simplify freeing logic in linfo and jited_linfo
This patch simplifies the linfo freeing logic by combining "bpf_prog_free_jited_linfo()" and "bpf_prog_free_unused_jited_linfo()" into the new "bpf_prog_jit_attempt_done()". It is a prep work for the kernel function call support. In a later patch, freeing the kernel function call descriptors will also be done in the "bpf_prog_jit_attempt_done()". "bpf_prog_free_linfo()" is removed since it is only called by "__bpf_prog_put_noref()". The kvfree() are directly called instead. It also takes this chance to s/kcalloc/kvcalloc/ for the jited_linfo allocation. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210325015130.1544323-1-kafai@fb.com |
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Toke Høiland-Jørgensen
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12aa8a9467 |
bpf: Enforce that struct_ops programs be GPL-only
With the introduction of the struct_ops program type, it became possible to
implement kernel functionality in BPF, making it viable to use BPF in place
of a regular kernel module for these particular operations.
Thus far, the only user of this mechanism is for implementing TCP
congestion control algorithms. These are clearly marked as GPL-only when
implemented as modules (as seen by the use of EXPORT_SYMBOL_GPL for
tcp_register_congestion_control()), so it seems like an oversight that this
was not carried over to BPF implementations. Since this is the only user
of the struct_ops mechanism, just enforcing GPL-only for the struct_ops
program type seems like the simplest way to fix this.
Fixes:
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Daniel Borkmann
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80847a71b2 |
bpf: Undo ptr_to_map_key alu sanitation for now
Remove PTR_TO_MAP_KEY for the time being from being sanitized on pointer ALU
through sanitize_ptr_alu() mainly for 3 reasons:
1) It's currently unused and not available from unprivileged. However that by
itself is not yet a strong reason to drop the code.
2) Commit
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David S. Miller
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241949e488 |
Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-03-24 The following pull-request contains BPF updates for your *net-next* tree. We've added 37 non-merge commits during the last 15 day(s) which contain a total of 65 files changed, 3200 insertions(+), 738 deletions(-). The main changes are: 1) Static linking of multiple BPF ELF files, from Andrii. 2) Move drop error path to devmap for XDP_REDIRECT, from Lorenzo. 3) Spelling fixes from various folks. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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David S. Miller
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efd13b71a3 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Signed-off-by: David S. Miller <davem@davemloft.net> |
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Jianlin Lv
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9ef05281e5 |
bpf: Remove insn_buf[] declaration in inner block
Two insn_buf[16] variables are declared in the function which acts on function scope and block scope respectively. The statement in the inner block is redundant, so remove it. Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210318024851.49693-1-Jianlin.Lv@arm.com |
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Piotr Krysiuk
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1b1597e64e |
bpf: Add sanity check for upper ptr_limit
Given we know the max possible value of ptr_limit at the time of retrieving the latter, add basic assertions, so that the verifier can bail out if anything looks odd and reject the program. Nothing triggered this so far, but it also does not hurt to have these. Signed-off-by: Piotr Krysiuk <piotras@gmail.com> Co-developed-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Piotr Krysiuk
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b5871dca25 |
bpf: Simplify alu_limit masking for pointer arithmetic
Instead of having the mov32 with aux->alu_limit - 1 immediate, move this operation to retrieve_ptr_limit() instead to simplify the logic and to allow for subsequent sanity boundary checks inside retrieve_ptr_limit(). This avoids in future that at the time of the verifier masking rewrite we'd run into an underflow which would not sign extend due to the nature of mov32 instruction. Signed-off-by: Piotr Krysiuk <piotras@gmail.com> Co-developed-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> |
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Piotr Krysiuk
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10d2bb2e6b |
bpf: Fix off-by-one for area size in creating mask to left
retrieve_ptr_limit() computes the ptr_limit for registers with stack and
map_value type. ptr_limit is the size of the memory area that is still
valid / in-bounds from the point of the current position and direction
of the operation (add / sub). This size will later be used for masking
the operation such that attempting out-of-bounds access in the speculative
domain is redirected to remain within the bounds of the current map value.
When masking to the right the size is correct, however, when masking to
the left, the size is off-by-one which would lead to an incorrect mask
and thus incorrect arithmetic operation in the non-speculative domain.
Piotr found that if the resulting alu_limit value is zero, then the
BPF_MOV32_IMM() from the fixup_bpf_calls() rewrite will end up loading
0xffffffff into AX instead of sign-extending to the full 64 bit range,
and as a result, this allows abuse for executing speculatively out-of-
bounds loads against 4GB window of address space and thus extracting the
contents of kernel memory via side-channel.
Fixes:
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Piotr Krysiuk
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f232326f69 |
bpf: Prohibit alu ops for pointer types not defining ptr_limit
The purpose of this patch is to streamline error propagation and in particular to propagate retrieve_ptr_limit() errors for pointer types that are not defining a ptr_limit such that register-based alu ops against these types can be rejected. The main rationale is that a gap has been identified by Piotr in the existing protection against speculatively out-of-bounds loads, for example, in case of ctx pointers, unprivileged programs can still perform pointer arithmetic. This can be abused to execute speculatively out-of-bounds loads without restrictions and thus extract contents of kernel memory. Fix this by rejecting unprivileged programs that attempt any pointer arithmetic on unprotected pointer types. The two affected ones are pointer to ctx as well as pointer to map. Field access to a modified ctx' pointer is rejected at a later point in time in the verifier, and |
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David S. Miller
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c1acda9807 |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says: ==================== pull-request: bpf-next 2021-03-09 The following pull-request contains BPF updates for your *net-next* tree. We've added 90 non-merge commits during the last 17 day(s) which contain a total of 114 files changed, 5158 insertions(+), 1288 deletions(-). The main changes are: 1) Faster bpf_redirect_map(), from Björn. 2) skmsg cleanup, from Cong. 3) Support for floating point types in BTF, from Ilya. 4) Documentation for sys_bpf commands, from Joe. 5) Support for sk_lookup in bpf_prog_test_run, form Lorenz. 6) Enable task local storage for tracing programs, from Song. 7) bpf_for_each_map_elem() helper, from Yonghong. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Björn Töpel
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e6a4750ffe |
bpf, xdp: Make bpf_redirect_map() a map operation
Currently the bpf_redirect_map() implementation dispatches to the correct map-lookup function via a switch-statement. To avoid the dispatching, this change adds bpf_redirect_map() as a map operation. Each map provides its bpf_redirect_map() version, and correct function is automatically selected by the BPF verifier. A nice side-effect of the code movement is that the map lookup functions are now local to the map implementation files, which removes one additional function call. Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com |
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Alexei Starovoitov
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350a5c4dd2 |
bpf: Dont allow vmlinux BTF to be used in map_create and prog_load.
The syzbot got FD of vmlinux BTF and passed it into map_create which caused
crash in btf_type_id_size() when it tried to access resolved_ids. The vmlinux
BTF doesn't have 'resolved_ids' and 'resolved_sizes' initialized to save
memory. To avoid such issues disallow using vmlinux BTF in prog_load and
map_create commands.
Fixes:
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Brendan Jackman
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39491867ac |
bpf: Explicitly zero-extend R0 after 32-bit cmpxchg
As pointed out by Ilya and explained in the new comment, there's a
discrepancy between x86 and BPF CMPXCHG semantics: BPF always loads
the value from memory into r0, while x86 only does so when r0 and the
value in memory are different. The same issue affects s390.
At first this might sound like pure semantics, but it makes a real
difference when the comparison is 32-bit, since the load will
zero-extend r0/rax.
The fix is to explicitly zero-extend rax after doing such a
CMPXCHG. Since this problem affects multiple archs, this is done in
the verifier by patching in a BPF_ZEXT_REG instruction after every
32-bit cmpxchg. Any archs that don't need such manual zero-extension
can do a look-ahead with insn_is_zext to skip the unnecessary mov.
Note this still goes on top of Ilya's patch:
https://lore.kernel.org/bpf/20210301154019.129110-1-iii@linux.ibm.com/T/#u
Differences v5->v6[1]:
- Moved is_cmpxchg_insn and ensured it can be safely re-used. Also renamed it
and removed 'inline' to match the style of the is_*_function helpers.
- Fixed up comments in verifier test (thanks for the careful review, Martin!)
Differences v4->v5[1]:
- Moved the logic entirely into opt_subreg_zext_lo32_rnd_hi32, thanks to Martin
for suggesting this.
Differences v3->v4[1]:
- Moved the optimization against pointless zext into the correct place:
opt_subreg_zext_lo32_rnd_hi32 is called _after_ fixup_bpf_calls.
Differences v2->v3[1]:
- Moved patching into fixup_bpf_calls (patch incoming to rename this function)
- Added extra commentary on bpf_jit_needs_zext
- Added check to avoid adding a pointless zext(r0) if there's already one there.
Difference v1->v2[1]: Now solved centrally in the verifier instead of
specifically for the x86 JIT. Thanks to Ilya and Daniel for the suggestions!
[1] v5: https://lore.kernel.org/bpf/CA+i-1C3ytZz6FjcPmUg5s4L51pMQDxWcZNvM86w4RHZ_o2khwg@mail.gmail.com/T/#t
v4: https://lore.kernel.org/bpf/CA+i-1C3ytZz6FjcPmUg5s4L51pMQDxWcZNvM86w4RHZ_o2khwg@mail.gmail.com/T/#t
v3: https://lore.kernel.org/bpf/08669818-c99d-0d30-e1db-53160c063611@iogearbox.net/T/#t
v2: https://lore.kernel.org/bpf/08669818-c99d-0d30-e1db-53160c063611@iogearbox.net/T/#t
v1: https://lore.kernel.org/bpf/d7ebaefb-bfd6-a441-3ff2-2fdfe699b1d2@iogearbox.net/T/#t
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Fixes:
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Ilya Leoshkevich
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83a2881903 |
bpf: Account for BPF_FETCH in insn_has_def32()
insn_has_def32() returns false for 32-bit BPF_FETCH insns. This makes
adjust_insn_aux_data() incorrectly set zext_dst, as can be seen in [1].
This happens because insn_no_def() does not know about the BPF_FETCH
variants of BPF_STX.
Fix in two steps.
First, replace insn_no_def() with insn_def_regno(), which returns the
register an insn defines. Normally insn_no_def() calls are followed by
insn->dst_reg uses; replace those with the insn_def_regno() return
value.
Second, adjust the BPF_STX special case in is_reg64() to deal with
queries made from opt_subreg_zext_lo32_rnd_hi32(), where the state
information is no longer available. Add a comment, since the purpose
of this special case is not clear at first glance.
[1] https://lore.kernel.org/bpf/20210223150845.1857620-1-jackmanb@google.com/
Fixes:
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Yonghong Song
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314ee05e2f |
bpf: Add hashtab support for bpf_for_each_map_elem() helper
This patch added support for hashmap, percpu hashmap, lru hashmap and percpu lru hashmap. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204927.3885020-1-yhs@fb.com |
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Yonghong Song
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69c087ba62 |
bpf: Add bpf_for_each_map_elem() helper
The bpf_for_each_map_elem() helper is introduced which iterates all map elements with a callback function. The helper signature looks like long bpf_for_each_map_elem(map, callback_fn, callback_ctx, flags) and for each map element, the callback_fn will be called. For example, like hashmap, the callback signature may look like long callback_fn(map, key, val, callback_ctx) There are two known use cases for this. One is from upstream ([1]) where a for_each_map_elem helper may help implement a timeout mechanism in a more generic way. Another is from our internal discussion for a firewall use case where a map contains all the rules. The packet data can be compared to all these rules to decide allow or deny the packet. For array maps, users can already use a bounded loop to traverse elements. Using this helper can avoid using bounded loop. For other type of maps (e.g., hash maps) where bounded loop is hard or impossible to use, this helper provides a convenient way to operate on all elements. For callback_fn, besides map and map element, a callback_ctx, allocated on caller stack, is also passed to the callback function. This callback_ctx argument can provide additional input and allow to write to caller stack for output. If the callback_fn returns 0, the helper will iterate through next element if available. If the callback_fn returns 1, the helper will stop iterating and returns to the bpf program. Other return values are not used for now. Currently, this helper is only available with jit. It is possible to make it work with interpreter with so effort but I leave it as the future work. [1]: https://lore.kernel.org/bpf/20210122205415.113822-1-xiyou.wangcong@gmail.com/ Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204925.3884923-1-yhs@fb.com |
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Yonghong Song
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282a0f46d6 |
bpf: Change return value of verifier function add_subprog()
Currently, verifier function add_subprog() returns 0 for success and negative value for failure. Change the return value to be the subprog number for success. This functionality will be used in the next patch to save a call to find_subprog(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204924.3884848-1-yhs@fb.com |
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Yonghong Song
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1435137573 |
bpf: Refactor check_func_call() to allow callback function
Later proposed bpf_for_each_map_elem() helper has callback function as one of its arguments. This patch refactored check_func_call() to permit callback function which sets callee state. Different callback functions may have different callee states. There is no functionality change for this patch. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204923.3884627-1-yhs@fb.com |
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Yonghong Song
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bc2591d63f |
bpf: Factor out verbose_invalid_scalar()
Factor out the function verbose_invalid_scalar() to verbose print if a scalar is not in a tnum range. There is no functionality change and the function will be used by later patch which introduced bpf_for_each_map_elem(). Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204922.3884375-1-yhs@fb.com |
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Yonghong Song
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efdb22de7d |
bpf: Factor out visit_func_call_insn() in check_cfg()
During verifier check_cfg(), all instructions are visited to ensure verifier can handle program control flows. This patch factored out function visit_func_call_insn() so it can be reused in later patch to visit callback function calls. There is no functionality change for this patch. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210226204920.3884136-1-yhs@fb.com |
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Brendan Jackman
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e6ac593372 |
bpf: Rename fixup_bpf_calls and add some comments
This function has become overloaded, it actually does lots of diverse things in a single pass. Rename it to avoid confusion, and add some concise commentary. Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210217104509.2423183-1-jackmanb@google.com |
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Dmitrii Banshchikov
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523a4cf491 |
bpf: Use MAX_BPF_FUNC_REG_ARGS macro
Instead of using integer literal here and there use macro name for better context. Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20210225202629.585485-1-me@ubique.spb.ru |
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Dan Carpenter
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33ccec5fd7 |
bpf: Fix a warning message in mark_ptr_not_null_reg()
The WARN_ON() argument is a condition, not an error message. So this
code will print a stack trace but will not print the warning message.
Fix that and also change it to only WARN_ONCE().
Fixes:
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David S. Miller
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d489ded1a3 | Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net | |
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David S. Miller
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b8af417e4d |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says: ==================== pull-request: bpf-next 2021-02-16 The following pull-request contains BPF updates for your *net-next* tree. There's a small merge conflict between |
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Ilya Leoshkevich
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45159b2763 |
bpf: Clear subreg_def for global function return values
test_global_func4 fails on s390 as reported by Yauheni in [1].
The immediate problem is that the zext code includes the instruction,
whose result needs to be zero-extended, into the zero-extension
patchlet, and if this instruction happens to be a branch, then its
delta is not adjusted. As a result, the verifier rejects the program
later.
However, according to [2], as far as the verifier's algorithm is
concerned and as specified by the insn_no_def() function, branching
insns do not define anything. This includes call insns, even though
one might argue that they define %r0.
This means that the real problem is that zero extension kicks in at
all. This happens because clear_caller_saved_regs() sets BPF_REG_0's
subreg_def after global function calls. This can be fixed in many
ways; this patch mimics what helper function call handling already
does.
[1] https://lore.kernel.org/bpf/20200903140542.156624-1-yauheni.kaliuta@redhat.com/
[2] https://lore.kernel.org/bpf/CAADnVQ+2RPKcftZw8d+B1UwB35cpBhpF5u3OocNh90D9pETPwg@mail.gmail.com/
Fixes:
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Dmitrii Banshchikov
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e5069b9c23 |
bpf: Support pointers in global func args
Add an ability to pass a pointer to a type with known size in arguments of a global function. Such pointers may be used to overcome the limit on the maximum number of arguments, avoid expensive and tricky workarounds and to have multiple output arguments. A referenced type may contain pointers but indirect access through them isn't supported. The implementation consists of two parts. If a global function has an argument that is a pointer to a type with known size then: 1) In btf_check_func_arg_match(): check that the corresponding register points to NULL or to a valid memory region that is large enough to contain the expected argument's type. 2) In btf_prepare_func_args(): set the corresponding register type to PTR_TO_MEM_OR_NULL and its size to the size of the expected type. Only global functions are supported because allowance of pointers for static functions might break validation. Consider the following scenario. A static function has a pointer argument. A caller passes pointer to its stack memory. Because the callee can change referenced memory verifier cannot longer assume any particular slot type of the caller's stack memory hence the slot type is changed to SLOT_MISC. If there is an operation that relies on slot type other than SLOT_MISC then verifier won't be able to infer safety of the operation. When verifier sees a static function that has a pointer argument different from PTR_TO_CTX then it skips arguments check and continues with "inline" validation with more information available. The operation that relies on the particular slot type now succeeds. Because global functions were not allowed to have pointer arguments different from PTR_TO_CTX it's not possible to break existing and valid code. Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210212205642.620788-4-me@ubique.spb.ru |
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Dmitrii Banshchikov
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4ddb74165a |
bpf: Extract nullable reg type conversion into a helper function
Extract conversion from a register's nullable type to a type with a value. The helper will be used in mark_ptr_not_null_reg(). Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210212205642.620788-3-me@ubique.spb.ru |
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Daniel Borkmann
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9b00f1b788 |
bpf: Fix truncation handling for mod32 dst reg wrt zero
Recently noticed that when mod32 with a known src reg of 0 is performed, then the dst register is 32-bit truncated in verifier: 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 0: (b7) r0 = 0 1: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0 1: (b7) r1 = -1 2: R0_w=inv0 R1_w=inv-1 R10=fp0 2: (b4) w2 = -1 3: R0_w=inv0 R1_w=inv-1 R2_w=inv4294967295 R10=fp0 3: (9c) w1 %= w0 4: R0_w=inv0 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 4: (b7) r0 = 1 5: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 5: (1d) if r1 == r2 goto pc+1 R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 6: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 6: (b7) r0 = 2 7: R0_w=inv2 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0 7: (95) exit 7: R0=inv1 R1=inv(id=0,umin_value=4294967295,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2=inv4294967295 R10=fp0 7: (95) exit However, as a runtime result, we get 2 instead of 1, meaning the dst register does not contain (u32)-1 in this case. The reason is fairly straight forward given the 0 test leaves the dst register as-is: # ./bpftool p d x i 23 0: (b7) r0 = 0 1: (b7) r1 = -1 2: (b4) w2 = -1 3: (16) if w0 == 0x0 goto pc+1 4: (9c) w1 %= w0 5: (b7) r0 = 1 6: (1d) if r1 == r2 goto pc+1 7: (b7) r0 = 2 8: (95) exit This was originally not an issue given the dst register was marked as completely unknown (aka 64 bit unknown). However, after |
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Ilya Leoshkevich
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b2e37a7114 |
bpf: Fix subreg optimization for BPF_FETCH
All 32-bit variants of BPF_FETCH (add, and, or, xor, xchg, cmpxchg) define a 32-bit subreg and thus have zext_dst set. Their encoding, however, uses dst_reg field as a base register, which causes opt_subreg_zext_lo32_rnd_hi32() to zero-extend said base register instead of the one the insn really defines (r0 or src_reg). Fix by properly choosing a register being defined, similar to how check_atomic() already does that. Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210210204502.83429-1-iii@linux.ibm.com |
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Alexei Starovoitov
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638e4b825d |
bpf: Allows per-cpu maps and map-in-map in sleepable programs
Since sleepable programs are now executing under migrate_disable the per-cpu maps are safe to use. The map-in-map were ok to use in sleepable from the time sleepable progs were introduced. Note that non-preallocated maps are still not safe, since there is no rcu_read_lock yet in sleepable programs and dynamically allocated map elements are relying on rcu protection. The sleepable programs have rcu_read_lock_trace instead. That limitation will be addresses in the future. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: KP Singh <kpsingh@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-9-alexei.starovoitov@gmail.com |
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Alexei Starovoitov
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700d4796ef |
bpf: Optimize program stats
Move bpf_prog_stats from prog->aux into prog to avoid one extra load in critical path of program execution. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210210033634.62081-2-alexei.starovoitov@gmail.com |
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David S. Miller
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dc9d87581d | Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net | |
Andrei Matei
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01f810ace9 |
bpf: Allow variable-offset stack access
Before this patch, variable offset access to the stack was dissalowed for regular instructions, but was allowed for "indirect" accesses (i.e. helpers). This patch removes the restriction, allowing reading and writing to the stack through stack pointers with variable offsets. This makes stack-allocated buffers more usable in programs, and brings stack pointers closer to other types of pointers. The motivation is being able to use stack-allocated buffers for data manipulation. When the stack size limit is sufficient, allocating buffers on the stack is simpler than per-cpu arrays, or other alternatives. In unpriviledged programs, variable-offset reads and writes are disallowed (they were already disallowed for the indirect access case) because the speculative execution checking code doesn't support them. Additionally, when writing through a variable-offset stack pointer, if any pointers are in the accessible range, there's possilibities of later leaking pointers because the write cannot be tracked precisely. Writes with variable offset mark the whole range as initialized, even though we don't know which stack slots are actually written. This is in order to not reject future reads to these slots. Note that this doesn't affect writes done through helpers; like before, helpers need the whole stack range to be initialized to begin with. All the stack slots are in range are considered scalars after the write; variable-offset register spills are not tracked. For reads, all the stack slots in the variable range needs to be initialized (but see above about what writes do), otherwise the read is rejected. All register spilled in stack slots that might be read are marked as having been read, however reads through such pointers don't do register filling; the target register will always be either a scalar or a constant zero. Signed-off-by: Andrei Matei <andreimatei1@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210207011027.676572-2-andreimatei1@gmail.com |
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Daniel Borkmann
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e88b2c6e5a |
bpf: Fix 32 bit src register truncation on div/mod
While reviewing a different fix, John and I noticed an oddity in one of the
BPF program dumps that stood out, for example:
# bpftool p d x i 13
0: (b7) r0 = 808464450
1: (b4) w4 = 808464432
2: (bc) w0 = w0
3: (15) if r0 == 0x0 goto pc+1
4: (9c) w4 %= w0
[...]
In line 2 we noticed that the mov32 would 32 bit truncate the original src
register for the div/mod operation. While for the two operations the dst
register is typically marked unknown e.g. from adjust_scalar_min_max_vals()
the src register is not, and thus verifier keeps tracking original bounds,
simplified:
0: R1=ctx(id=0,off=0,imm=0) R10=fp0
0: (b7) r0 = -1
1: R0_w=invP-1 R1=ctx(id=0,off=0,imm=0) R10=fp0
1: (b7) r1 = -1
2: R0_w=invP-1 R1_w=invP-1 R10=fp0
2: (3c) w0 /= w1
3: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1_w=invP-1 R10=fp0
3: (77) r1 >>= 32
4: R0_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R1_w=invP4294967295 R10=fp0
4: (bf) r0 = r1
5: R0_w=invP4294967295 R1_w=invP4294967295 R10=fp0
5: (95) exit
processed 6 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
Runtime result of r0 at exit is 0 instead of expected -1. Remove the
verifier mov32 src rewrite in div/mod and replace it with a jmp32 test
instead. After the fix, we result in the following code generation when
having dividend r1 and divisor r6:
div, 64 bit: div, 32 bit:
0: (b7) r6 = 8 0: (b7) r6 = 8
1: (b7) r1 = 8 1: (b7) r1 = 8
2: (55) if r6 != 0x0 goto pc+2 2: (56) if w6 != 0x0 goto pc+2
3: (ac) w1 ^= w1 3: (ac) w1 ^= w1
4: (05) goto pc+1 4: (05) goto pc+1
5: (3f) r1 /= r6 5: (3c) w1 /= w6
6: (b7) r0 = 0 6: (b7) r0 = 0
7: (95) exit 7: (95) exit
mod, 64 bit: mod, 32 bit:
0: (b7) r6 = 8 0: (b7) r6 = 8
1: (b7) r1 = 8 1: (b7) r1 = 8
2: (15) if r6 == 0x0 goto pc+1 2: (16) if w6 == 0x0 goto pc+1
3: (9f) r1 %= r6 3: (9c) w1 %= w6
4: (b7) r0 = 0 4: (b7) r0 = 0
5: (95) exit 5: (95) exit
x86 in particular can throw a 'divide error' exception for div
instruction not only for divisor being zero, but also for the case
when the quotient is too large for the designated register. For the
edx:eax and rdx:rax dividend pair it is not an issue in x86 BPF JIT
since we always zero edx (rdx). Hence really the only protection
needed is against divisor being zero.
Fixes:
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Daniel Borkmann
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fd675184fc |
bpf: Fix verifier jmp32 pruning decision logic
Anatoly has been fuzzing with kBdysch harness and reported a hang in
one of the outcomes:
func#0 @0
0: R1=ctx(id=0,off=0,imm=0) R10=fp0
0: (b7) r0 = 808464450
1: R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R10=fp0
1: (b4) w4 = 808464432
2: R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R4_w=invP808464432 R10=fp0
2: (9c) w4 %= w0
3: R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
3: (66) if w4 s> 0x30303030 goto pc+0
R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff),s32_max_value=808464432) R10=fp0
4: R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff),s32_max_value=808464432) R10=fp0
4: (7f) r0 >>= r0
5: R0_w=invP(id=0) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff),s32_max_value=808464432) R10=fp0
5: (9c) w4 %= w0
6: R0_w=invP(id=0) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
6: (66) if w0 s> 0x3030 goto pc+0
R0_w=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
7: R0=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4=invP(id=0) R10=fp0
7: (d6) if w0 s<= 0x303030 goto pc+1
9: R0=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4=invP(id=0) R10=fp0
9: (95) exit
propagating r0
from 6 to 7: safe
4: R0_w=invP808464450 R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umin_value=808464433,umax_value=2147483647,var_off=(0x0; 0x7fffffff)) R10=fp0
4: (7f) r0 >>= r0
5: R0_w=invP(id=0) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0,umin_value=808464433,umax_value=2147483647,var_off=(0x0; 0x7fffffff)) R10=fp0
5: (9c) w4 %= w0
6: R0_w=invP(id=0) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
6: (66) if w0 s> 0x3030 goto pc+0
R0_w=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
propagating r0
7: safe
propagating r0
from 6 to 7: safe
processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1
The underlying program was xlated as follows:
# bpftool p d x i 10
0: (b7) r0 = 808464450
1: (b4) w4 = 808464432
2: (bc) w0 = w0
3: (15) if r0 == 0x0 goto pc+1
4: (9c) w4 %= w0
5: (66) if w4 s> 0x30303030 goto pc+0
6: (7f) r0 >>= r0
7: (bc) w0 = w0
8: (15) if r0 == 0x0 goto pc+1
9: (9c) w4 %= w0
10: (66) if w0 s> 0x3030 goto pc+0
11: (d6) if w0 s<= 0x303030 goto pc+1
12: (05) goto pc-1
13: (95) exit
The verifier rewrote original instructions it recognized as dead code with
'goto pc-1', but reality differs from verifier simulation in that we are
actually able to trigger a hang due to hitting the 'goto pc-1' instructions.
Taking a closer look at the verifier analysis, the reason is that it misjudges
its pruning decision at the first 'from 6 to 7: safe' occasion. What happens
is that while both old/cur registers are marked as precise, they get misjudged
for the jmp32 case as range_within() yields true, meaning that the prior
verification path with a wider register bound could be verified successfully
and therefore the current path with a narrower register bound is deemed safe
as well whereas in reality it's not. R0 old/cur path's bounds compare as
follows:
old: smin_value=0x8000000000000000,smax_value=0x7fffffffffffffff,umin_value=0x0,umax_value=0xffffffffffffffff,var_off=(0x0; 0xffffffffffffffff)
cur: smin_value=0x8000000000000000,smax_value=0x7fffffff7fffffff,umin_value=0x0,umax_value=0xffffffff7fffffff,var_off=(0x0; 0xffffffff7fffffff)
old: s32_min_value=0x80000000,s32_max_value=0x00003030,u32_min_value=0x00000000,u32_max_value=0xffffffff
cur: s32_min_value=0x00003031,s32_max_value=0x7fffffff,u32_min_value=0x00003031,u32_max_value=0x7fffffff
The 64 bit bounds generally look okay and while the information that got
propagated from 32 to 64 bit looks correct as well, it's not precise enough
for judging a conditional jmp32. Given the latter only operates on subregisters
we also need to take these into account as well for a range_within() probe
in order to be able to prune paths. Extending the range_within() constraint
to both bounds will be able to tell us that the old signed 32 bit bounds are
not wider than the cur signed 32 bit bounds.
With the fix in place, the program will now verify the 'goto' branch case as
it should have been:
[...]
6: R0_w=invP(id=0) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
6: (66) if w0 s> 0x3030 goto pc+0
R0_w=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
7: R0=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4=invP(id=0) R10=fp0
7: (d6) if w0 s<= 0x303030 goto pc+1
9: R0=invP(id=0,s32_max_value=12336) R1=ctx(id=0,off=0,imm=0) R4=invP(id=0) R10=fp0
9: (95) exit
7: R0_w=invP(id=0,smax_value=9223372034707292159,umax_value=18446744071562067967,var_off=(0x0; 0xffffffff7fffffff),s32_min_value=12337,u32_min_value=12337,u32_max_value=2147483647) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
7: (d6) if w0 s<= 0x303030 goto pc+1
R0_w=invP(id=0,smax_value=9223372034707292159,umax_value=18446744071562067967,var_off=(0x0; 0xffffffff7fffffff),s32_min_value=3158065,u32_min_value=3158065,u32_max_value=2147483647) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
8: R0_w=invP(id=0,smax_value=9223372034707292159,umax_value=18446744071562067967,var_off=(0x0; 0xffffffff7fffffff),s32_min_value=3158065,u32_min_value=3158065,u32_max_value=2147483647) R1=ctx(id=0,off=0,imm=0) R4_w=invP(id=0) R10=fp0
8: (30) r0 = *(u8 *)skb[808464432]
BPF_LD_[ABS|IND] uses reserved fields
processed 11 insns (limit 1000000) max_states_per_insn 1 total_states 1 peak_states 1 mark_read 1
The bug is quite subtle in the sense that when verifier would determine that
a given branch is dead code, it would (here: wrongly) remove these instructions
from the program and hard-wire the taken branch for privileged programs instead
of the 'goto pc-1' rewrites which will cause hard to debug problems.
Fixes:
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Daniel Borkmann
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ee114dd64c |
bpf: Fix verifier jsgt branch analysis on max bound
Fix incorrect is_branch{32,64}_taken() analysis for the jsgt case. The return
code for both will tell the caller whether a given conditional jump is taken
or not, e.g. 1 means branch will be taken [for the involved registers] and the
goto target will be executed, 0 means branch will not be taken and instead we
fall-through to the next insn, and last but not least a -1 denotes that it is
not known at verification time whether a branch will be taken or not. Now while
the jsgt has the branch-taken case correct with reg->s32_min_value > sval, the
branch-not-taken case is off-by-one when testing for reg->s32_max_value < sval
since the branch will also be taken for reg->s32_max_value == sval. The jgt
branch analysis, for example, gets this right.
Fixes:
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Yonghong Song
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23a2d70c7a |
bpf: Refactor BPF_PSEUDO_CALL checking as a helper function
There is no functionality change. This refactoring intends to facilitate next patch change with BPF_PSEUDO_FUNC. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210204234827.1628953-1-yhs@fb.com |
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KP Singh
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ba90c2cc02 |
bpf: Allow usage of BPF ringbuffer in sleepable programs
The BPF ringbuffer map is pre-allocated and the implementation logic does not rely on disabling preemption or per-cpu data structures. Using the BPF ringbuffer sleepable LSM and tracing programs does not trigger any warnings with DEBUG_ATOMIC_SLEEP, DEBUG_PREEMPT, PROVE_RCU and PROVE_LOCKING and LOCKDEP enabled. This allows helpers like bpf_copy_from_user and bpf_ima_inode_hash to write to the BPF ring buffer from sleepable BPF programs. Signed-off-by: KP Singh <kpsingh@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210204193622.3367275-2-kpsingh@kernel.org |
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Brendan Jackman
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37086bfdc7 |
bpf: Propagate stack bounds to registers in atomics w/ BPF_FETCH
When BPF_FETCH is set, atomic instructions load a value from memory into a register. The current verifier code first checks via check_mem_access whether we can access the memory, and then checks via check_reg_arg whether we can write into the register. For loads, check_reg_arg has the side-effect of marking the register's value as unkonwn, and check_mem_access has the side effect of propagating bounds from memory to the register. This currently only takes effect for stack memory. Therefore with the current order, bounds information is thrown away, but by simply reversing the order of check_reg_arg vs. check_mem_access, we can instead propagate bounds smartly. A simple test is added with an infinite loop that can only be proved unreachable if this propagation is present. This is implemented both with C and directly in test_verifier using assembly. Suggested-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Brendan Jackman <jackmanb@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210202135002.4024825-1-jackmanb@google.com |
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Stanislav Fomichev
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772412176f |
bpf: Allow rewriting to ports under ip_unprivileged_port_start
At the moment, BPF_CGROUP_INET{4,6}_BIND hooks can rewrite user_port
to the privileged ones (< ip_unprivileged_port_start), but it will
be rejected later on in the __inet_bind or __inet6_bind.
Let's add another return value to indicate that CAP_NET_BIND_SERVICE
check should be ignored. Use the same idea as we currently use
in cgroup/egress where bit #1 indicates CN. Instead, for
cgroup/bind{4,6}, bit #1 indicates that CAP_NET_BIND_SERVICE should
be bypassed.
v5:
- rename flags to be less confusing (Andrey Ignatov)
- rework BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY to work on flags
and accept BPF_RET_SET_CN (no behavioral changes)
v4:
- Add missing IPv6 support (Martin KaFai Lau)
v3:
- Update description (Martin KaFai Lau)
- Fix capability restore in selftest (Martin KaFai Lau)
v2:
- Switch to explicit return code (Martin KaFai Lau)
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrey Ignatov <rdna@fb.com>
Link: https://lore.kernel.org/bpf/20210127193140.3170382-1-sdf@google.com
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