[PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #3)

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[PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #3)

by Suresh Jayaraman-2 :: Rate this Message:

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Just noticed that there was a undesired fall-through bug with the
previous version of the patch. Fixed it.

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@...>
---

 fs/cifs/connect.c |   57 +++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 1f3345d..bfc5fa9 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 +1397,49 @@ 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
+ break;
+ } else {
+ if (addr4->sin_addr.s_addr !=
+    server->addr.sockAddr.sin_addr.s_addr)
+ continue;
+ else
+ break;
+ }
+
+ 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
+ break;
+ } else {
+ if (!ipv6_addr_equal(&server->addr.sockAddr6.sin6_addr,
+    &addr6->sin6_addr) ||
+    server->addr.sockAddr6.sin6_scope_id !=
+    addr6->sin6_scope_id)
+ continue;
+ else
+ break;
+ }
+ }
 
  ++server->srv_count;
  write_unlock(&cifs_tcp_ses_lock);
@@ -1475,7 +1508,7 @@ 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;
 
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Re: [PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #3)

by Jeff Layton-2 :: Rate this Message:

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On Wed, 19 Aug 2009 15:13:07 +0530
Suresh Jayaraman <sjayaraman@...> wrote:

> Just noticed that there was a undesired fall-through bug with the
> previous version of the patch. Fixed it.
>
> 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@...>
> ---
>
>  fs/cifs/connect.c |   57 +++++++++++++++++++++++++++++++++++++++++-----------
>  1 files changed, 45 insertions(+), 12 deletions(-)
>

A couple of minor comments below. In general, I find it better to
structure the code so that you end up with less indentation, and
unneeded else clauses, etc...

> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index 1f3345d..bfc5fa9 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 +1397,49 @@ 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) {
                           ^^^^ this is rather awkward since you now have 2 copies of each address comparison per family. If you compare the address before checking for the port then this function will be slightly more efficient and will look cleaner.

> + 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
> + break;
                                ^^^ no need for the else's here, just move the break outside of the outer "if's".

> + } else {
> + if (addr4->sin_addr.s_addr !=
> +    server->addr.sockAddr.sin_addr.s_addr)
> + continue;
> + else
> + break;
> + }
> +
> + 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
> + break;
> + } else {
> + if (!ipv6_addr_equal(&server->addr.sockAddr6.sin6_addr,
> +    &addr6->sin6_addr) ||
> +    server->addr.sockAddr6.sin6_scope_id !=
> +    addr6->sin6_scope_id)
> + continue;
> + else
> + break;
> + }
> + }

The same comments apply to the IPv6 stanza here too.

>  
>   ++server->srv_count;
>   write_unlock(&cifs_tcp_ses_lock);
> @@ -1475,7 +1508,7 @@ 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;
>  

--
Jeff Layton <jlayton@...>
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