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samples/bpf: fix broken cgroup socket testing 

Currently, executing test_cgrp2_sock2 fails due to wrong section
header. This 'cgroup/sock1' style section is previously used at
'samples/bpf_load' (deprecated) BPF loader. Because this style isn't
supported in libbpf, this commit fixes this problem by correcting the
section header.

    $ sudo ./test_cgrp2_sock2.sh
    libbpf: prog 'bpf_prog1': missing BPF prog type, check ELF section name 'cgroup/sock1'
    libbpf: prog 'bpf_prog1': failed to load: -22
    libbpf: failed to load object './sock_flags_kern.o'
    ERROR: loading BPF object file failed

In addition, this BPF program filters ping packets by comparing whether
the socket type uses SOCK_RAW. However, after the ICMP socket[1] was
developed, ping sends ICMP packets using SOCK_DGRAM. Therefore, in this
commit, the packet filtering is changed to use SOCK_DGRAM instead of
SOCK_RAW.

    $ strace --trace socket ping -6 -c1 -w1 ::1
    socket(AF_INET6, SOCK_DGRAM, IPPROTO_ICMPV6) = 3

[1]: https://lwn.net/Articles/422330/

Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Link: https://lore.kernel.org/r/20230115071613.125791-5-danieltimlee@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel T. Lee 2023-01-15 16:16:07 +09:00 committed by Alexei Starovoitov
parent dac808c907
commit 31b12a4159
1 changed files with 6 additions and 6 deletions
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12
samples/bpf/sock_flags_kern.c
View File

@ -5,7 +5,7 @@
#include <uapi/linux/in6.h> #include <uapi/linux/in6.h>
#include <bpf/bpf_helpers.h> #include <bpf/bpf_helpers.h>
SEC("cgroup/sock1") SEC("cgroup/sock")
int bpf_prog1(struct bpf_sock *sk) int bpf_prog1(struct bpf_sock *sk)
{ {
char fmt[] = "socket: family %d type %d protocol %d\n"; char fmt[] = "socket: family %d type %d protocol %d\n";
@ -17,29 +17,29 @@ int bpf_prog1(struct bpf_sock *sk)
bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol); bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol);
bpf_trace_printk(fmt2, sizeof(fmt2), uid, gid); bpf_trace_printk(fmt2, sizeof(fmt2), uid, gid);
/* block PF_INET6, SOCK_RAW, IPPROTO_ICMPV6 sockets /* block PF_INET6, SOCK_DGRAM, IPPROTO_ICMPV6 sockets
* ie., make ping6 fail * ie., make ping6 fail
*/ */
if (sk->family == PF_INET6 && if (sk->family == PF_INET6 &&
sk->type == SOCK_RAW && sk->type == SOCK_DGRAM &&
sk->protocol == IPPROTO_ICMPV6) sk->protocol == IPPROTO_ICMPV6)
return 0; return 0;
return 1; return 1;
} }
SEC("cgroup/sock2") SEC("cgroup/sock")
int bpf_prog2(struct bpf_sock *sk) int bpf_prog2(struct bpf_sock *sk)
{ {
char fmt[] = "socket: family %d type %d protocol %d\n"; char fmt[] = "socket: family %d type %d protocol %d\n";
bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol); bpf_trace_printk(fmt, sizeof(fmt), sk->family, sk->type, sk->protocol);
/* block PF_INET, SOCK_RAW, IPPROTO_ICMP sockets /* block PF_INET, SOCK_DGRAM, IPPROTO_ICMP sockets
* ie., make ping fail * ie., make ping fail
*/ */
if (sk->family == PF_INET && if (sk->family == PF_INET &&
sk->type == SOCK_RAW && sk->type == SOCK_DGRAM &&
sk->protocol == IPPROTO_ICMP) sk->protocol == IPPROTO_ICMP)
return 0; return 0;