ipv6/udp: use sticky pktinfo egress ifindex on connect()

[ Upstream commit 1cdda91871470f15e79375991bd2eddc6e86ddb1 ]

Currently, the egress interface index specified via IPV6_PKTINFO
is ignored by __ip6_datagram_connect(), so that RFC 3542 section 6.7
can be subverted when the user space application calls connect()
before sendmsg().
Fix it by initializing properly flowi6_oif in connect() before
performing the route lookup.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 9e4bacc4f19e2ed2e529e1284ea65e89283deb5a..20437cb6dbddc8f21b887dcd314e2c718020b80c 100644 (file)
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -161,6 +161,9 @@ ipv4_connected:
        fl6.fl6_dport = inet->inet_dport;
        fl6.fl6_sport = inet->inet_sport;
 
+       if (!fl6.flowi6_oif)
+               fl6.flowi6_oif = np->sticky_pktinfo.ipi6_ifindex;
+
        if (!fl6.flowi6_oif && (addr_type&IPV6_ADDR_MULTICAST))
                fl6.flowi6_oif = np->mcast_oif;