Patchwork PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #4)

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Submitter Suresh Jayaraman
Date Aug. 20, 2009, 7:33 a.m.
Message ID <4A8CFC4E.2090608@suse.de>
Download mbox | patch
Permalink /patch/31708/
State New
Headers show

Comments

Suresh Jayaraman - Aug. 20, 2009, 7:33 a.m.
One more try..

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@localhost "sleep 86400"
3. ssh -f -L 6222:127.0.0.1:445 root@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@suse.de>
---

 fs/cifs/connect.c |   45 +++++++++++++++++++++++++++++++++------------
 1 files changed, 33 insertions(+), 12 deletions(-)
Jeff Layton - Aug. 20, 2009, 10:44 a.m.
On Thu, 20 Aug 2009 13:03:34 +0530
Suresh Jayaraman <sjayaraman@suse.de> wrote:

> One more try..
> 
> 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@localhost "sleep 86400"
> 3. ssh -f -L 6222:127.0.0.1:445 root@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@suse.de>
> ---
> 


Still a little more nested that I would have preferred...

I'd have probably had it do this for each family:

if (addrs don't match)
	continue;
if (ports don't match)
	continue
break;

...but that's a rather minor point.

Acked-by: Jeff Layton <jlayton@redhat.com>
Steve French - Sept. 1, 2009, 5:22 p.m.
Merged.

Note I fixed some checkpatch warnings thrown when I checked in this patch in
a followon patch immediately after merging this.

On Thu, Aug 20, 2009 at 2:33 AM, Suresh Jayaraman <sjayaraman@suse.de>wrote:

> One more try..
>
> 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@localhost "sleep 86400"
> 3. ssh -f -L 6222:127.0.0.1:445 root@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@suse.de>
> ---
>
>  fs/cifs/connect.c |   45 +++++++++++++++++++++++++++++++++------------
>  1 files changed, 33 insertions(+), 12 deletions(-)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 1f3345d..4e47a9b 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 +1397,37 @@ 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:
> +                       if (addr4->sin_addr.s_addr ==
> +                           server->addr.sockAddr.sin_addr.s_addr) {
> +                               addr4->sin_port = htons(port);
> +                               /* user overrode default port? */
> +                               if (addr4->sin_port) {
> +                                       if (addr4->sin_port !=
> +                                           server->addr.sockAddr.sin_port)
> +                                               continue;
> +                               }
> +                               break;
> +                       } else
> +                               continue;
> +
> +               case AF_INET6:
> +                       if (ipv6_addr_equal(&addr6->sin6_addr,
> +                           &server->addr.sockAddr6.sin6_addr) &&
> +                           (addr6->sin6_scope_id ==
> +                           server->addr.sockAddr6.sin6_scope_id)) {
> +                               addr6->sin6_port = htons(port);
> +                               /* user overrode default port? */
> +                               if (addr6->sin6_port) {
> +                                      if (addr6->sin6_port !=
> +
>  server->addr.sockAddr6.sin6_port)
> +                                              continue;
> +                               }
> +                               break;
> +                       } else
> +                               continue;
> +               }
>
>                ++server->srv_count;
>                write_unlock(&cifs_tcp_ses_lock);
> @@ -1475,7 +1496,7 @@ 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;
>
>

Patch

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1f3345d..4e47a9b 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 +1397,37 @@  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:
+			if (addr4->sin_addr.s_addr ==
+			    server->addr.sockAddr.sin_addr.s_addr) {
+				addr4->sin_port = htons(port);
+				/* user overrode default port? */
+				if (addr4->sin_port) {
+					if (addr4->sin_port !=
+					    server->addr.sockAddr.sin_port)
+						continue;
+				}
+				break;
+			} else
+				continue;
+
+		case AF_INET6:
+			if (ipv6_addr_equal(&addr6->sin6_addr,
+			    &server->addr.sockAddr6.sin6_addr) &&
+			    (addr6->sin6_scope_id == 
+			    server->addr.sockAddr6.sin6_scope_id)) {
+				addr6->sin6_port = htons(port);
+				/* user overrode default port? */
+				if (addr6->sin6_port) {
+				       if (addr6->sin6_port !=
+					   server->addr.sockAddr6.sin6_port)
+					       continue;
+				}
+				break;
+			} else 
+				continue;
+		}
 
 		++server->srv_count;
 		write_unlock(&cifs_tcp_ses_lock);
@@ -1475,7 +1496,7 @@  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;