From: Jonathan Basseri misterikkit@google.com
[ Upstream commit 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 ]
If a socket has a valid dst cache, then xfrm_lookup_route will get skipped. However, the cache is not invalidated when applying policy to a socket (i.e. IPV6_XFRM_POLICY). The result is that new policies are sometimes ignored on those sockets. (Note: This was broken for IPv4 and IPv6 at different times.)
This can be demonstrated like so, 1. Create UDP socket. 2. connect() the socket. 3. Apply an outbound XFRM policy to the socket. (setsockopt) 4. send() data on the socket.
Packets will continue to be sent in the clear instead of matching an xfrm or returning a no-match error (EAGAIN). This affects calls to send() and not sendto().
Invalidating the sk_dst_cache is necessary to correctly apply xfrm policies. Since we do this in xfrm_user_policy(), the sk_lock was already acquired in either do_ip_setsockopt() or do_ipv6_setsockopt(), and we may call __sk_dst_reset().
Performance impact should be negligible, since this code is only called when changing xfrm policy, and only affects the socket in question.
Fixes: 00bc0ef5880d ("ipv6: Skip XFRM lookup if dst_entry in socket cache is valid") Tested: https://android-review.googlesource.com/517555 Tested: https://android-review.googlesource.com/418659 Signed-off-by: Jonathan Basseri misterikkit@google.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/xfrm/xfrm_state.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index d6a11af0bab1..9b6e51450fc5 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1884,6 +1884,7 @@ int xfrm_user_policy(struct sock *sk, int optname, u8 __user *optval, int optlen if (err >= 0) { xfrm_sk_policy_insert(sk, err, pol); xfrm_pol_put(pol); + __sk_dst_reset(sk); err = 0; }