• Jonathan Basseri's avatar
    xfrm: Clear sk_dst_cache when applying per-socket policy. · 2b06cdf3
    Jonathan Basseri authored
    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: 00bc0ef5 ("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/418659Signed-off-by: default avatarJonathan Basseri <misterikkit@google.com>
    Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
    2b06cdf3
xfrm_state.c 59.4 KB