net/tcp: Prevent TCP-MD5 with TCP-AO being set

Be as conservative as possible: if there is TCP-MD5 key for a given peer
regardless of L3 interface - don't allow setting TCP-AO key for the same
peer. According to RFC5925, TCP-AO is supposed to replace TCP-MD5 and
there can't be any switch between both on any connected tuple.
Later it can be relaxed, if there's a use, but in the beginning restrict
any intersection.

Note: it's still should be possible to set both TCP-MD5 and TCP-AO keys
on a listening socket for *different* peers.

Co-developed-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Co-developed-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Salam Noureddine <noureddine@arista.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 0 deletions

diff --git a/net/ipv6/tcp_ao.c b/net/ipv6/tcp_ao.c
index 049ddbabe049..0640acaee67b 100644
--- a/net/ipv6/tcp_ao.c
+++ b/net/ipv6/tcp_ao.c
@@ -12,6 +12,23 @@
 #include <net/tcp.h>
 #include <net/ipv6.h>
 
+static struct tcp_ao_key *tcp_v6_ao_do_lookup(const struct sock *sk,
+					      const struct in6_addr *addr,
+					      int sndid, int rcvid)
+{
+	return tcp_ao_do_lookup(sk, (union tcp_ao_addr *)addr, AF_INET6,
+				sndid, rcvid);
+}
+
+struct tcp_ao_key *tcp_v6_ao_lookup(const struct sock *sk,
+				    struct sock *addr_sk,
+				    int sndid, int rcvid)
+{
+	struct in6_addr *addr = &addr_sk->sk_v6_daddr;
+
+	return tcp_v6_ao_do_lookup(sk, addr, sndid, rcvid);
+}
+
 int tcp_v6_parse_ao(struct sock *sk, int cmd,
 		    sockptr_t optval, int optlen)
 {