On Mon, Oct 23, 2017 at 06:18:55PM -0700, Jonathan Basseri wrote: > 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. > 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. > > Note: Creating normal XFRM policies should have a similar effect on > sk_dst_cache entries that match the policy, but that is not fixed in > this patch.
I think we don't have this problem with 'normal' policies. When inserting such a policy, we bump the IPv4/IPv6 genid. This should invalidate all cached dst entries, no?
