[linux-cifs-client] [PATCH] cifs: Fix broken mounts when SSH tunnel is used

[Suresh Jayaraman]

It seems there is a regression that got introduced while Jeff fixed
all the mount/umount races. While attempting to find whether a tcp
session is already existing, we were not checking whether the "port"
used are the same. When a second mount is attempted with a different
"port=" option, it is being ignored. Because of this the cifs mounts
that uses a SSH tunnel appears to be broken.

Steps to reproduce:

1. create 2 shares
# SSH Tunnel a SMB session
2. ssh -f -L 6111:127.0.0.1:445 root at localhost "sleep 86400"
3. ssh -f -L 6222:127.0.0.1:445 root at localhost "sleep 86400"
4. tcpdump -i lo 6111 &
5. mkdir -p /mnt/mnt1
6. mkdir -p /mnt/mnt2
7. mount.cifs //localhost/a /mnt/mnt1 -o username=guest,ip=127.0.0.1,port=6111
#(shows tcpdump activity on port 6111)
8. mount.cifs //localhost/b /mnt/mnt2 -o username=guest,ip=127.0.0.1,port=6222
#(shows tcpdump activity only on port 6111 and not on 6222

Fix this by adding a check to verify whether the port, before deciding that a
existing tcp session is found and can be used. 

Signed-off-by: Suresh Jayaraman <sjayaraman at suse.de>
---
 fs/cifs/connect.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1f3345d..c00159c 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1399,13 +1399,15 @@ cifs_find_tcp_session(struct sockaddr_storage *addr)
 
 		if (addr->ss_family == AF_INET &&
 		    (addr4->sin_addr.s_addr !=
-		     server->addr.sockAddr.sin_addr.s_addr))
+		     server->addr.sockAddr.sin_addr.s_addr ||
+		     addr4->sin_port != server->addr.sockAddr.sin_port))
 			continue;
 		else if (addr->ss_family == AF_INET6 &&
 			 (!ipv6_addr_equal(&server->addr.sockAddr6.sin6_addr,
 					   &addr6->sin6_addr) ||
 			  server->addr.sockAddr6.sin6_scope_id !=
-					   addr6->sin6_scope_id))
+					   addr6->sin6_scope_id ||
+			  server->addr.sockAddr6.sin6_port != addr6->sin6_port))
 			continue;
 
 		++server->srv_count;