[PATCH 4.4 001/101] ipv6: fix IPV6_ADDRFORM operation logic

[Greg Kroah-Hartman]

From: Hangbin Liu <liuhang...@gmail.com>

[ Upstream commit 79a1f0ccdbb4ad700590f61b00525b390cb53905 ]

Socket option IPV6_ADDRFORM supports UDP/UDPLITE and TCP at present.
Previously the checking logic looks like:
if (sk->sk_protocol == IPPROTO_UDP || sk->sk_protocol == IPPROTO_UDPLITE)
        do_some_check;
else if (sk->sk_protocol != IPPROTO_TCP)
        break;

After commit b6f6118901d1 ("ipv6: restrict IPV6_ADDRFORM operation"), TCP
was blocked as the logic changed to:
if (sk->sk_protocol == IPPROTO_UDP || sk->sk_protocol == IPPROTO_UDPLITE)
        do_some_check;
else if (sk->sk_protocol == IPPROTO_TCP)
        do_some_check;
        break;
else
        break;

Then after commit 82c9ae440857 ("ipv6: fix restrict IPV6_ADDRFORM operation")
UDP/UDPLITE were blocked as the logic changed to:
if (sk->sk_protocol == IPPROTO_UDP || sk->sk_protocol == IPPROTO_UDPLITE)
        do_some_check;
if (sk->sk_protocol == IPPROTO_TCP)
        do_some_check;

if (sk->sk_protocol != IPPROTO_TCP)
        break;

Fix it by using Eric's code and simply remove the break in TCP check, which
looks like:
if (sk->sk_protocol == IPPROTO_UDP || sk->sk_protocol == IPPROTO_UDPLITE)
        do_some_check;
else if (sk->sk_protocol == IPPROTO_TCP)
        do_some_check;
else
        break;

Fixes: 82c9ae440857 ("ipv6: fix restrict IPV6_ADDRFORM operation")
Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/ipv6/ipv6_sockglue.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -185,14 +185,15 @@ static int do_ipv6_setsockopt(struct soc
                                        retv = -EBUSY;
                                        break;
                                }
-                       }
-                       if (sk->sk_protocol == IPPROTO_TCP &&
-                           sk->sk_prot != &tcpv6_prot) {
-                               retv = -EBUSY;
+                       } else if (sk->sk_protocol == IPPROTO_TCP) {
+                               if (sk->sk_prot != &tcpv6_prot) {
+                                       retv = -EBUSY;
+                                       break;
+                               }
+                       } else {
                                break;
                        }
-                       if (sk->sk_protocol != IPPROTO_TCP)
-                               break;
+
                        if (sk->sk_state != TCP_ESTABLISHED) {
                                retv = -ENOTCONN;
                                break;