[linux-cifs-client] [PATCH] cifs: fix broken mounts when a SSH tunnel is used (try #3)
Jeff Layton
jlayton at redhat.com
Wed Aug 19 05:19:11 MDT 2009
On Wed, 19 Aug 2009 15:13:07 +0530
Suresh Jayaraman <sjayaraman at suse.de> 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 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 | 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 at redhat.com>
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