Each peer's endpoint contains a dst_cache entry that takes a reference to another netdev. When the containing namespace exits, we take down the socket and prevent future sockets from being created (by setting creating_net to NULL), which removes that potential reference on the netns. However, it doesn't release references to the netns that a netdev cached in dst_cache might be taking, so the netns still might fail to exit. Since the socket is gimped anyway, we can simply clear all the dst_caches (by way of clearing the endpoint src), which will release all references.

However, the current dst_cache_reset function only releases those references lazily. But it turns out that all of our usages of wg_socket_clear_peer_endpoint_src are called from contexts that are not exactly high-speed or bottle-necked. For example, when there's connection difficulty, or when userspace is reconfiguring the interface. And in particular for this patch, when the netns is exiting. So for those cases, it makes more sense to call dst_release immediately. For that, we add a small helper function to dst_cache.

This patch also adds a test to netns.sh from Hangbin Liu to ensure this doesn't regress.

Test-by: Hangbin Liu liuhangbin@gmail.com Reported-by: Xiumei Mu xmu@redhat.com Cc: Hangbin Liu liuhangbin@gmail.com Cc: Toke Høiland-Jørgensen toke@redhat.com Cc: Paolo Abeni pabeni@redhat.com Fixes: 900575aa33a3 ("wireguard: device: avoid circular netns references") Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com --- drivers/net/wireguard/device.c | 3 +++ drivers/net/wireguard/socket.c | 2 +- include/net/dst_cache.h | 11 ++++++++++ net/core/dst_cache.c | 19 +++++++++++++++++ tools/testing/selftests/wireguard/netns.sh | 24 +++++++++++++++++++++- 5 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c index 551ddaaaf540..77e64ea6be67 100644 --- a/drivers/net/wireguard/device.c +++ b/drivers/net/wireguard/device.c @@ -398,6 +398,7 @@ static struct rtnl_link_ops link_ops __read_mostly = { static void wg_netns_pre_exit(struct net *net) { struct wg_device *wg; + struct wg_peer *peer;

rtnl_lock(); list_for_each_entry(wg, &device_list, device_list) { @@ -407,6 +408,8 @@ static void wg_netns_pre_exit(struct net *net) mutex_lock(&wg->device_update_lock); rcu_assign_pointer(wg->creating_net, NULL); wg_socket_reinit(wg, NULL, NULL); + list_for_each_entry(peer, &wg->peer_list, peer_list) + wg_socket_clear_peer_endpoint_src(peer); mutex_unlock(&wg->device_update_lock); } } diff --git a/drivers/net/wireguard/socket.c b/drivers/net/wireguard/socket.c index 8c496b747108..6f07b949cb81 100644 --- a/drivers/net/wireguard/socket.c +++ b/drivers/net/wireguard/socket.c @@ -308,7 +308,7 @@ void wg_socket_clear_peer_endpoint_src(struct wg_peer *peer) { write_lock_bh(&peer->endpoint_lock); memset(&peer->endpoint.src6, 0, sizeof(peer->endpoint.src6)); - dst_cache_reset(&peer->endpoint_cache); + dst_cache_reset_now(&peer->endpoint_cache); write_unlock_bh(&peer->endpoint_lock); }

diff --git a/include/net/dst_cache.h b/include/net/dst_cache.h index 67634675e919..df6622a5fe98 100644 --- a/include/net/dst_cache.h +++ b/include/net/dst_cache.h @@ -79,6 +79,17 @@ static inline void dst_cache_reset(struct dst_cache *dst_cache) dst_cache->reset_ts = jiffies; }

+/** + * dst_cache_reset_now - invalidate the cache contents immediately + * @dst_cache: the cache + * + * The caller must be sure there are no concurrent users, as this frees + * all dst_cache users immediately, rather than waiting for the next + * per-cpu usage like dst_cache_reset does. Most callers should use the + * higher speed lazily-freed dst_cache_reset function instead. + */ +void dst_cache_reset_now(struct dst_cache *dst_cache); + /** * dst_cache_init - initialize the cache, allocating the required storage * @dst_cache: the cache diff --git a/net/core/dst_cache.c b/net/core/dst_cache.c index be74ab4551c2..0ccfd5fa5cb9 100644 --- a/net/core/dst_cache.c +++ b/net/core/dst_cache.c @@ -162,3 +162,22 @@ void dst_cache_destroy(struct dst_cache *dst_cache) free_percpu(dst_cache->cache); } EXPORT_SYMBOL_GPL(dst_cache_destroy); + +void dst_cache_reset_now(struct dst_cache *dst_cache) +{ + int i; + + if (!dst_cache->cache) + return; + + dst_cache->reset_ts = jiffies; + for_each_possible_cpu(i) { + struct dst_cache_pcpu *idst = per_cpu_ptr(dst_cache->cache, i); + struct dst_entry *dst = idst->dst; + + idst->cookie = 0; + idst->dst = NULL; + dst_release(dst); + } +} +EXPORT_SYMBOL_GPL(dst_cache_reset_now); diff --git a/tools/testing/selftests/wireguard/netns.sh b/tools/testing/selftests/wireguard/netns.sh index 2e5c1630885e..8a9461aa0878 100755 --- a/tools/testing/selftests/wireguard/netns.sh +++ b/tools/testing/selftests/wireguard/netns.sh @@ -613,6 +613,28 @@ ip0 link set wg0 up kill $ncat_pid ip0 link del wg0

+# Ensure that dst_cache references don't outlive netns lifetime +ip1 link add dev wg0 type wireguard +ip2 link add dev wg0 type wireguard +configure_peers +ip1 link add veth1 type veth peer name veth2 +ip1 link set veth2 netns $netns2 +ip1 addr add fd00:aa::1/64 dev veth1 +ip2 addr add fd00:aa::2/64 dev veth2 +ip1 link set veth1 up +ip2 link set veth2 up +waitiface $netns1 veth1 +waitiface $netns2 veth2 +ip1 -6 route add default dev veth1 via fd00:aa::2 +ip2 -6 route add default dev veth2 via fd00:aa::1 +n1 wg set wg0 peer "$pub2" endpoint [fd00:aa::2]:2 +n2 wg set wg0 peer "$pub1" endpoint [fd00:aa::1]:1 +n1 ping6 -c 1 fd00::2 +pp ip netns delete $netns1 +pp ip netns delete $netns2 +pp ip netns add $netns1 +pp ip netns add $netns2 + # Ensure there aren't circular reference loops ip1 link add wg1 type wireguard ip2 link add wg2 type wireguard @@ -631,7 +653,7 @@ while read -t 0.1 -r line 2>/dev/null || [[ $? -ne 142 ]]; do done < /dev/kmsg alldeleted=1 for object in "${!objects[@]}"; do - if [[ ${objects["$object"]} != *createddestroyed ]]; then + if [[ ${objects["$object"]} != *createddestroyed && ${objects["$object"]} != *createdcreateddestroyeddestroyed ]]; then echo "Error: $object: merely ${objects["$object"]}" >&3 alldeleted=0 fi