[linux-cifs-client] [PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #2)

[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 by adding a check to compare the port _only_ if the user tries to
override the tcp port with "port=" option, before deciding that an
existing tcp session is found. Also, clean up a bit by replacing
if-else if by a switch statment while at it as suggested by Jeff.

Signed-off-by: Suresh Jayaraman <sjayaraman at suse.de>
---

 fs/cifs/connect.c |   49 +++++++++++++++++++++++++++++++++++++------------
 1 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1f3345d..630e45d 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1377,7 +1377,7 @@ cifs_parse_mount_options(char *options, const char *devname,
 }
 
 static struct TCP_Server_Info *
-cifs_find_tcp_session(struct sockaddr_storage *addr)
+cifs_find_tcp_session(struct sockaddr_storage *addr, unsigned short int port)
 {
 	struct list_head *tmp;
 	struct TCP_Server_Info *server;
@@ -1397,16 +1397,41 @@ cifs_find_tcp_session(struct sockaddr_storage *addr)
 		if (server->tcpStatus == CifsNew)
 			continue;
 
-		if (addr->ss_family == AF_INET &&
-		    (addr4->sin_addr.s_addr !=
-		     server->addr.sockAddr.sin_addr.s_addr))
-			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))
-			continue;
+		switch (addr->ss_family) {
+		case AF_INET:
+			/* user overrode default port? */
+			if (port) {
+				addr4->sin_port = htons(port);
+				if (addr4->sin_addr.s_addr !=
+				    server->addr.sockAddr.sin_addr.s_addr ||
+				    addr4->sin_port !=
+				    server->addr.sockAddr.sin_port)
+					continue;
+			} else {
+				if (addr4->sin_addr.s_addr !=
+				    server->addr.sockAddr.sin_addr.s_addr)
+					continue;
+			}
+
+		case AF_INET6:
+			/* user overrode default port? */
+			if (port) {
+				addr6->sin6_port = htons(port);
+				if (!ipv6_addr_equal(&server->addr.sockAddr6.sin6_addr,
+				    &addr6->sin6_addr) ||
+				    server->addr.sockAddr6.sin6_scope_id !=
+				    addr6->sin6_scope_id ||
+				    server->addr.sockAddr6.sin6_port !=
+				    addr6->sin6_port)
+					continue;
+			} else {
+				if (!ipv6_addr_equal(&server->addr.sockAddr6.sin6_addr,
+				    &addr6->sin6_addr) ||
+				    server->addr.sockAddr6.sin6_scope_id !=
+				    addr6->sin6_scope_id)
+					continue;
+			}
+		}
 
 		++server->srv_count;
 		write_unlock(&cifs_tcp_ses_lock);
@@ -1475,7 +1500,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 	}
 
 	/* see if we already have a matching tcp_ses */
-	tcp_ses = cifs_find_tcp_session(&addr);
+	tcp_ses = cifs_find_tcp_session(&addr, volume_info->port);
 	if (tcp_ses)
 		return tcp_ses;