[PATCH 1/3] ipv6: Prevent unexpected sk->sk_prot changes

[Ilya Lesokhin]

With this patch IPV6 code ensure that only sockets with the
expected sk->sk_prot are converted to IPV4.

Signed-off-by: Boris Pismenny <bor...@mellanox.com>
---
 net/ipv6/ipv6_sockglue.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 02d795f..318cd344 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -174,6 +174,7 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, 
int optname,
                if (val == PF_INET) {
                        struct ipv6_txoptions *opt;
                        struct sk_buff *pktopt;
+                       struct proto *expected_prot;
 
                        if (sk->sk_type == SOCK_RAW)
                                break;
@@ -199,6 +200,17 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, 
int optname,
                                break;
                        }
 
+                       if (sk->sk_protocol == IPPROTO_TCP &&
+                           sk->sk_prot != &tcpv6_prot)
+                               break;
+
+                       expected_prot = &udpv6_prot;
+                       if (sk->sk_protocol == IPPROTO_UDPLITE)
+                               expected_prot = &udplitev6_prot;
+
+                       if (sk->sk_prot != expected_prot)
+                               break;
+
                        fl6_free_socklist(sk);
                        __ipv6_sock_mc_close(sk);
 
-- 
1.8.3.1