wireguard: allowedips: add WGALLOWEDIP_F_REMOVE_ME flag

The current netlink API for WireGuard does not directly support removal
of allowed ips from a peer. A user can remove an allowed ip from a peer
in one of two ways:

1. By using the WGPEER_F_REPLACE_ALLOWEDIPS flag and providing a new
   list of allowed ips which omits the allowed ip that is to be removed.
2. By reassigning an allowed ip to a "dummy" peer then removing that
   peer with WGPEER_F_REMOVE_ME.

With the first approach, the driver completely rebuilds the allowed ip
list for a peer. If my current configuration is such that a peer has
allowed ips 192.168.0.2 and 192.168.0.3 and I want to remove 192.168.0.2
the actual transition looks like this.

[192.168.0.2, 192.168.0.3] <-- Initial state
[]                         <-- Step 1: Allowed ips removed for peer
[192.168.0.3]              <-- Step 2: Allowed ips added back for peer

This is true even if the allowed ip list is small and the update does
not need to be batched into multiple WG_CMD_SET_DEVICE requests, as the
removal and subsequent addition of ips is non-atomic within a single
request. Consequently, wg_allowedips_lookup_dst and
wg_allowedips_lookup_src may return NULL while reconfiguring a peer even
for packets bound for ips a user did not intend to remove leading to
unintended interruptions in connectivity. This presents in userspace as
failed calls to sendto and sendmsg for UDP sockets. In my case, I ran
netperf while repeatedly reconfiguring the allowed ips for a peer with
wg.

/usr/local/bin/netperf -H 10.102.73.72 -l 10m -t UDP_STREAM -- -R 1 -m 1024
send_data: data send error: No route to host (errno 113)
netperf: send_omni: send_data failed: No route to host

While this may not be of particular concern for environments where peers
and allowed ips are mostly static, systems like Cilium manage peers and
allowed ips in a dynamic environment where peers (i.e. Kubernetes nodes)
and allowed ips (i.e. pods running on those nodes) can frequently
change making WGPEER_F_REPLACE_ALLOWEDIPS problematic.

The second approach avoids any possible connectivity interruptions
but is hacky and less direct, requiring the creation of a temporary
peer just to dispose of an allowed ip.

Introduce a new flag called WGALLOWEDIP_F_REMOVE_ME which in the same
way that WGPEER_F_REMOVE_ME allows a user to remove a single peer from
a WireGuard device's configuration allows a user to remove an ip from a
peer's set of allowed ips. This enables incremental updates to a
device's configuration without any connectivity blips or messy
workarounds.

A corresponding patch for wg extends the existing `wg set` interface to
leverage this feature.

$ wg set wg0 peer <PUBKEY> allowed-ips +192.168.88.0/24,-192.168.0.1/32

When '+' or '-' is prepended to any ip in the list, wg clears
WGPEER_F_REPLACE_ALLOWEDIPS and sets the WGALLOWEDIP_F_REMOVE_ME flag on
any ip prefixed with '-'.

Signed-off-by: Jordan Rife <jordan@jrife.io>
[Jason: minor style nits, fixes to selftest, bump of wireguard-tools version]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://patch.msgid.link/20250521212707.1767879-5-Jason@zx2c4.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jordan Rife 2025-05-21 23:27:06 +02:00 committed by Paolo Abeni
parent c852902007
commit ba3d7b93db
7 changed files with 187 additions and 44 deletions

View File

@ -249,6 +249,52 @@ static int add(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
return 0; return 0;
} }
static void remove_node(struct allowedips_node *node, struct mutex *lock)
{
struct allowedips_node *child, **parent_bit, *parent;
bool free_parent;
list_del_init(&node->peer_list);
RCU_INIT_POINTER(node->peer, NULL);
if (node->bit[0] && node->bit[1])
return;
child = rcu_dereference_protected(node->bit[!rcu_access_pointer(node->bit[0])],
lockdep_is_held(lock));
if (child)
child->parent_bit_packed = node->parent_bit_packed;
parent_bit = (struct allowedips_node **)(node->parent_bit_packed & ~3UL);
*parent_bit = child;
parent = (void *)parent_bit -
offsetof(struct allowedips_node, bit[node->parent_bit_packed & 1]);
free_parent = !rcu_access_pointer(node->bit[0]) && !rcu_access_pointer(node->bit[1]) &&
(node->parent_bit_packed & 3) <= 1 && !rcu_access_pointer(parent->peer);
if (free_parent)
child = rcu_dereference_protected(parent->bit[!(node->parent_bit_packed & 1)],
lockdep_is_held(lock));
call_rcu(&node->rcu, node_free_rcu);
if (!free_parent)
return;
if (child)
child->parent_bit_packed = parent->parent_bit_packed;
*(struct allowedips_node **)(parent->parent_bit_packed & ~3UL) = child;
call_rcu(&parent->rcu, node_free_rcu);
}
static int remove(struct allowedips_node __rcu **trie, u8 bits, const u8 *key,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
struct allowedips_node *node;
if (unlikely(cidr > bits))
return -EINVAL;
if (!rcu_access_pointer(*trie) || !node_placement(*trie, key, cidr, bits, &node, lock) ||
peer != rcu_access_pointer(node->peer))
return 0;
remove_node(node, lock);
return 0;
}
void wg_allowedips_init(struct allowedips *table) void wg_allowedips_init(struct allowedips *table)
{ {
table->root4 = table->root6 = NULL; table->root4 = table->root6 = NULL;
@ -300,44 +346,38 @@ int wg_allowedips_insert_v6(struct allowedips *table, const struct in6_addr *ip,
return add(&table->root6, 128, key, cidr, peer, lock); return add(&table->root6, 128, key, cidr, peer, lock);
} }
int wg_allowedips_remove_v4(struct allowedips *table, const struct in_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
/* Aligned so it can be passed to fls */
u8 key[4] __aligned(__alignof(u32));
++table->seq;
swap_endian(key, (const u8 *)ip, 32);
return remove(&table->root4, 32, key, cidr, peer, lock);
}
int wg_allowedips_remove_v6(struct allowedips *table, const struct in6_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock)
{
/* Aligned so it can be passed to fls64 */
u8 key[16] __aligned(__alignof(u64));
++table->seq;
swap_endian(key, (const u8 *)ip, 128);
return remove(&table->root6, 128, key, cidr, peer, lock);
}
void wg_allowedips_remove_by_peer(struct allowedips *table, void wg_allowedips_remove_by_peer(struct allowedips *table,
struct wg_peer *peer, struct mutex *lock) struct wg_peer *peer, struct mutex *lock)
{ {
struct allowedips_node *node, *child, **parent_bit, *parent, *tmp; struct allowedips_node *node, *tmp;
bool free_parent;
if (list_empty(&peer->allowedips_list)) if (list_empty(&peer->allowedips_list))
return; return;
++table->seq; ++table->seq;
list_for_each_entry_safe(node, tmp, &peer->allowedips_list, peer_list) { list_for_each_entry_safe(node, tmp, &peer->allowedips_list, peer_list)
list_del_init(&node->peer_list); remove_node(node, lock);
RCU_INIT_POINTER(node->peer, NULL);
if (node->bit[0] && node->bit[1])
continue;
child = rcu_dereference_protected(node->bit[!rcu_access_pointer(node->bit[0])],
lockdep_is_held(lock));
if (child)
child->parent_bit_packed = node->parent_bit_packed;
parent_bit = (struct allowedips_node **)(node->parent_bit_packed & ~3UL);
*parent_bit = child;
parent = (void *)parent_bit -
offsetof(struct allowedips_node, bit[node->parent_bit_packed & 1]);
free_parent = !rcu_access_pointer(node->bit[0]) &&
!rcu_access_pointer(node->bit[1]) &&
(node->parent_bit_packed & 3) <= 1 &&
!rcu_access_pointer(parent->peer);
if (free_parent)
child = rcu_dereference_protected(
parent->bit[!(node->parent_bit_packed & 1)],
lockdep_is_held(lock));
call_rcu(&node->rcu, node_free_rcu);
if (!free_parent)
continue;
if (child)
child->parent_bit_packed = parent->parent_bit_packed;
*(struct allowedips_node **)(parent->parent_bit_packed & ~3UL) = child;
call_rcu(&parent->rcu, node_free_rcu);
}
} }
int wg_allowedips_read_node(struct allowedips_node *node, u8 ip[16], u8 *cidr) int wg_allowedips_read_node(struct allowedips_node *node, u8 ip[16], u8 *cidr)

View File

@ -38,6 +38,10 @@ int wg_allowedips_insert_v4(struct allowedips *table, const struct in_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock); u8 cidr, struct wg_peer *peer, struct mutex *lock);
int wg_allowedips_insert_v6(struct allowedips *table, const struct in6_addr *ip, int wg_allowedips_insert_v6(struct allowedips *table, const struct in6_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock); u8 cidr, struct wg_peer *peer, struct mutex *lock);
int wg_allowedips_remove_v4(struct allowedips *table, const struct in_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock);
int wg_allowedips_remove_v6(struct allowedips *table, const struct in6_addr *ip,
u8 cidr, struct wg_peer *peer, struct mutex *lock);
void wg_allowedips_remove_by_peer(struct allowedips *table, void wg_allowedips_remove_by_peer(struct allowedips *table,
struct wg_peer *peer, struct mutex *lock); struct wg_peer *peer, struct mutex *lock);
/* The ip input pointer should be __aligned(__alignof(u64))) */ /* The ip input pointer should be __aligned(__alignof(u64))) */

View File

@ -46,7 +46,8 @@ static const struct nla_policy peer_policy[WGPEER_A_MAX + 1] = {
static const struct nla_policy allowedip_policy[WGALLOWEDIP_A_MAX + 1] = { static const struct nla_policy allowedip_policy[WGALLOWEDIP_A_MAX + 1] = {
[WGALLOWEDIP_A_FAMILY] = { .type = NLA_U16 }, [WGALLOWEDIP_A_FAMILY] = { .type = NLA_U16 },
[WGALLOWEDIP_A_IPADDR] = NLA_POLICY_MIN_LEN(sizeof(struct in_addr)), [WGALLOWEDIP_A_IPADDR] = NLA_POLICY_MIN_LEN(sizeof(struct in_addr)),
[WGALLOWEDIP_A_CIDR_MASK] = { .type = NLA_U8 } [WGALLOWEDIP_A_CIDR_MASK] = { .type = NLA_U8 },
[WGALLOWEDIP_A_FLAGS] = NLA_POLICY_MASK(NLA_U32, __WGALLOWEDIP_F_ALL),
}; };
static struct wg_device *lookup_interface(struct nlattr **attrs, static struct wg_device *lookup_interface(struct nlattr **attrs,
@ -329,6 +330,7 @@ static int set_port(struct wg_device *wg, u16 port)
static int set_allowedip(struct wg_peer *peer, struct nlattr **attrs) static int set_allowedip(struct wg_peer *peer, struct nlattr **attrs)
{ {
int ret = -EINVAL; int ret = -EINVAL;
u32 flags = 0;
u16 family; u16 family;
u8 cidr; u8 cidr;
@ -337,19 +339,30 @@ static int set_allowedip(struct wg_peer *peer, struct nlattr **attrs)
return ret; return ret;
family = nla_get_u16(attrs[WGALLOWEDIP_A_FAMILY]); family = nla_get_u16(attrs[WGALLOWEDIP_A_FAMILY]);
cidr = nla_get_u8(attrs[WGALLOWEDIP_A_CIDR_MASK]); cidr = nla_get_u8(attrs[WGALLOWEDIP_A_CIDR_MASK]);
if (attrs[WGALLOWEDIP_A_FLAGS])
flags = nla_get_u32(attrs[WGALLOWEDIP_A_FLAGS]);
if (family == AF_INET && cidr <= 32 && if (family == AF_INET && cidr <= 32 &&
nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in_addr)) nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in_addr)) {
ret = wg_allowedips_insert_v4( if (flags & WGALLOWEDIP_F_REMOVE_ME)
&peer->device->peer_allowedips, ret = wg_allowedips_remove_v4(&peer->device->peer_allowedips,
nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr, peer, nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
&peer->device->device_update_lock); peer, &peer->device->device_update_lock);
else if (family == AF_INET6 && cidr <= 128 && else
nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in6_addr)) ret = wg_allowedips_insert_v4(&peer->device->peer_allowedips,
ret = wg_allowedips_insert_v6( nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
&peer->device->peer_allowedips, peer, &peer->device->device_update_lock);
nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr, peer, } else if (family == AF_INET6 && cidr <= 128 &&
&peer->device->device_update_lock); nla_len(attrs[WGALLOWEDIP_A_IPADDR]) == sizeof(struct in6_addr)) {
if (flags & WGALLOWEDIP_F_REMOVE_ME)
ret = wg_allowedips_remove_v6(&peer->device->peer_allowedips,
nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
peer, &peer->device->device_update_lock);
else
ret = wg_allowedips_insert_v6(&peer->device->peer_allowedips,
nla_data(attrs[WGALLOWEDIP_A_IPADDR]), cidr,
peer, &peer->device->device_update_lock);
}
return ret; return ret;
} }

View File

@ -460,6 +460,10 @@ static __init struct wg_peer *init_peer(void)
wg_allowedips_insert_v##version(&t, ip##version(ipa, ipb, ipc, ipd), \ wg_allowedips_insert_v##version(&t, ip##version(ipa, ipb, ipc, ipd), \
cidr, mem, &mutex) cidr, mem, &mutex)
#define remove(version, mem, ipa, ipb, ipc, ipd, cidr) \
wg_allowedips_remove_v##version(&t, ip##version(ipa, ipb, ipc, ipd), \
cidr, mem, &mutex)
#define maybe_fail() do { \ #define maybe_fail() do { \
++i; \ ++i; \
if (!_s) { \ if (!_s) { \
@ -585,6 +589,50 @@ bool __init wg_allowedips_selftest(void)
test_negative(4, a, 192, 0, 0, 0); test_negative(4, a, 192, 0, 0, 0);
test_negative(4, a, 255, 0, 0, 0); test_negative(4, a, 255, 0, 0, 0);
insert(4, a, 1, 0, 0, 0, 32);
insert(4, a, 192, 0, 0, 0, 24);
insert(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 128);
insert(6, a, 0x24446800, 0xf0e40800, 0xeeaebeef, 0, 98);
test(4, a, 1, 0, 0, 0);
test(4, a, 192, 0, 0, 1);
test(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
test(6, a, 0x24446800, 0xf0e40800, 0xeeaebeef, 0x10101010);
/* Must be an exact match to remove */
remove(4, a, 192, 0, 0, 0, 32);
test(4, a, 192, 0, 0, 1);
/* NULL peer should have no effect and return 0 */
test_boolean(!remove(4, NULL, 192, 0, 0, 0, 24));
test(4, a, 192, 0, 0, 1);
/* different peer should have no effect and return 0 */
test_boolean(!remove(4, b, 192, 0, 0, 0, 24));
test(4, a, 192, 0, 0, 1);
/* invalid CIDR should have no effect and return -EINVAL */
test_boolean(remove(4, b, 192, 0, 0, 0, 33) == -EINVAL);
test(4, a, 192, 0, 0, 1);
remove(4, a, 192, 0, 0, 0, 24);
test_negative(4, a, 192, 0, 0, 1);
remove(4, a, 1, 0, 0, 0, 32);
test_negative(4, a, 1, 0, 0, 0);
/* Must be an exact match to remove */
remove(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 96);
test(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
/* NULL peer should have no effect and return 0 */
test_boolean(!remove(6, NULL, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 128));
test(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
/* different peer should have no effect and return 0 */
test_boolean(!remove(6, b, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 128));
test(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
/* invalid CIDR should have no effect and return -EINVAL */
test_boolean(remove(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 129) == -EINVAL);
test(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
remove(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef, 128);
test_negative(6, a, 0x24446801, 0x40e40800, 0xdeaebeef, 0xdefbeef);
/* Must match the peer to remove */
remove(6, b, 0x24446800, 0xf0e40800, 0xeeaebeef, 0, 98);
test(6, a, 0x24446800, 0xf0e40800, 0xeeaebeef, 0x10101010);
remove(6, a, 0x24446800, 0xf0e40800, 0xeeaebeef, 0, 98);
test_negative(6, a, 0x24446800, 0xf0e40800, 0xeeaebeef, 0x10101010);
wg_allowedips_free(&t, &mutex); wg_allowedips_free(&t, &mutex);
wg_allowedips_init(&t); wg_allowedips_init(&t);
insert(4, a, 192, 168, 0, 0, 16); insert(4, a, 192, 168, 0, 0, 16);

View File

@ -101,6 +101,10 @@
* WGALLOWEDIP_A_FAMILY: NLA_U16 * WGALLOWEDIP_A_FAMILY: NLA_U16
* WGALLOWEDIP_A_IPADDR: struct in_addr or struct in6_addr * WGALLOWEDIP_A_IPADDR: struct in_addr or struct in6_addr
* WGALLOWEDIP_A_CIDR_MASK: NLA_U8 * WGALLOWEDIP_A_CIDR_MASK: NLA_U8
* WGALLOWEDIP_A_FLAGS: NLA_U32, WGALLOWEDIP_F_REMOVE_ME if
* the specified IP should be removed;
* otherwise, this IP will be added if
* it is not already present.
* 0: NLA_NESTED * 0: NLA_NESTED
* ... * ...
* 0: NLA_NESTED * 0: NLA_NESTED
@ -184,11 +188,16 @@ enum wgpeer_attribute {
}; };
#define WGPEER_A_MAX (__WGPEER_A_LAST - 1) #define WGPEER_A_MAX (__WGPEER_A_LAST - 1)
enum wgallowedip_flag {
WGALLOWEDIP_F_REMOVE_ME = 1U << 0,
__WGALLOWEDIP_F_ALL = WGALLOWEDIP_F_REMOVE_ME
};
enum wgallowedip_attribute { enum wgallowedip_attribute {
WGALLOWEDIP_A_UNSPEC, WGALLOWEDIP_A_UNSPEC,
WGALLOWEDIP_A_FAMILY, WGALLOWEDIP_A_FAMILY,
WGALLOWEDIP_A_IPADDR, WGALLOWEDIP_A_IPADDR,
WGALLOWEDIP_A_CIDR_MASK, WGALLOWEDIP_A_CIDR_MASK,
WGALLOWEDIP_A_FLAGS,
__WGALLOWEDIP_A_LAST __WGALLOWEDIP_A_LAST
}; };
#define WGALLOWEDIP_A_MAX (__WGALLOWEDIP_A_LAST - 1) #define WGALLOWEDIP_A_MAX (__WGALLOWEDIP_A_LAST - 1)

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@ -611,6 +611,35 @@ n0 wg set wg0 peer "$pub2" allowed-ips "$allowedips"
} < <(n0 wg show wg0 allowed-ips) } < <(n0 wg show wg0 allowed-ips)
ip0 link del wg0 ip0 link del wg0
allowedips=( )
for i in {1..197}; do
allowedips+=( 192.168.0.$i )
allowedips+=( abcd::$i )
done
saved_ifs="$IFS"
IFS=,
allowedips="${allowedips[*]}"
IFS="$saved_ifs"
ip0 link add wg0 type wireguard
n0 wg set wg0 peer "$pub1" allowed-ips "$allowedips"
n0 wg set wg0 peer "$pub1" allowed-ips -192.168.0.1/32,-192.168.0.20/32,-192.168.0.100/32,-abcd::1/128,-abcd::20/128,-abcd::100/128
{
read -r pub allowedips
[[ $pub == "$pub1" ]]
i=0
for ip in $allowedips; do
[[ $ip != "192.168.0.1" ]]
[[ $ip != "192.168.0.20" ]]
[[ $ip != "192.168.0.100" ]]
[[ $ip != "abcd::1" ]]
[[ $ip != "abcd::20" ]]
[[ $ip != "abcd::100" ]]
((++i))
done
((i == 388))
} < <(n0 wg show wg0 allowed-ips)
ip0 link del wg0
! n0 wg show doesnotexist || false ! n0 wg show doesnotexist || false
ip0 link add wg0 type wireguard ip0 link add wg0 type wireguard

View File

@ -43,7 +43,7 @@ $(eval $(call tar_download,IPROUTE2,iproute2,5.17.0,.tar.gz,https://www.kernel.o
$(eval $(call tar_download,IPTABLES,iptables,1.8.7,.tar.bz2,https://www.netfilter.org/projects/iptables/files/,c109c96bb04998cd44156622d36f8e04b140701ec60531a10668cfdff5e8d8f0)) $(eval $(call tar_download,IPTABLES,iptables,1.8.7,.tar.bz2,https://www.netfilter.org/projects/iptables/files/,c109c96bb04998cd44156622d36f8e04b140701ec60531a10668cfdff5e8d8f0))
$(eval $(call tar_download,NMAP,nmap,7.92,.tgz,https://nmap.org/dist/,064183ea642dc4c12b1ab3b5358ce1cef7d2e7e11ffa2849f16d339f5b717117)) $(eval $(call tar_download,NMAP,nmap,7.92,.tgz,https://nmap.org/dist/,064183ea642dc4c12b1ab3b5358ce1cef7d2e7e11ffa2849f16d339f5b717117))
$(eval $(call tar_download,IPUTILS,iputils,s20190709,.tar.gz,https://github.com/iputils/iputils/archive/s20190709.tar.gz/#,a15720dd741d7538dd2645f9f516d193636ae4300ff7dbc8bfca757bf166490a)) $(eval $(call tar_download,IPUTILS,iputils,s20190709,.tar.gz,https://github.com/iputils/iputils/archive/s20190709.tar.gz/#,a15720dd741d7538dd2645f9f516d193636ae4300ff7dbc8bfca757bf166490a))
$(eval $(call tar_download,WIREGUARD_TOOLS,wireguard-tools,1.0.20210914,.tar.xz,https://git.zx2c4.com/wireguard-tools/snapshot/,97ff31489217bb265b7ae850d3d0f335ab07d2652ba1feec88b734bc96bd05ac)) $(eval $(call tar_download,WIREGUARD_TOOLS,wireguard-tools,1.0.20250521,.tar.xz,https://git.zx2c4.com/wireguard-tools/snapshot/,b6f2628b85b1b23cc06517ec9c74f82d52c4cdbd020f3dd2f00c972a1782950e))
export CFLAGS := -O3 -pipe export CFLAGS := -O3 -pipe
ifeq ($(HOST_ARCH),$(ARCH)) ifeq ($(HOST_ARCH),$(ARCH))