linux.git/fs/cifs, branch v5.19

smb3: workaround negprot bug in some Samba servers

2022-07-14T00:59:47+00:00

Mount can now fail to older Samba servers due to a server
bug handling padding at the end of the last negotiate
context (negotiate contexts typically are rounded up to 8
bytes by adding padding if needed). This server bug can
be avoided by switching the order of negotiate contexts,
placing a negotiate context at the end that does not
require padding (prior to the recent netname context fix
this was the case on the client).

Fixes: 73130a7b1ac9 ("smb3: fix empty netname context on secondary channels")
Reported-by: Julian Sikorski 
Tested-by: Julian Sikorski 
Reviewed-by: Shyam Prasad N 
Signed-off-by: Steve French

cifs: remove unnecessary locking of chan_lock while freeing session

2022-07-12T15:35:48+00:00

In cifs_put_smb_ses, when we're freeing the last ref count to
the session, we need to free up each channel. At this point,
it is unnecessary to take chan_lock, since we have the last
reference to the ses.

Picking up this lock also introduced a deadlock because it calls
cifs_put_tcp_ses, which locks cifs_tcp_ses_lock.

Signed-off-by: Shyam Prasad N 
Acked-by: Enzo Matsumiya 
Signed-off-by: Steve French

cifs: fix race condition with delayed threads

2022-07-12T15:35:13+00:00

On failure to create a new channel, first cancel the
delayed threads, which could try to search for this
channel, and not find it.

The other option was to put the tcp session for the
channel first, before decrementing chan_count. But
that would leave a reference to the tcp session, when
it has been freed already.

So going with the former option and cancelling the
delayed works first, before rolling back the channel.

Fixes: aa45dadd34e4 ("cifs: change iface_list from array to sorted linked list")
Signed-off-by: Shyam Prasad N 
Acked-by: Enzo Matsumiya 
Signed-off-by: Steve French

cifs: update cifs_ses::ip_addr after failover

2022-06-24T18:34:28+00:00

cifs_ses::ip_addr wasn't being updated in cifs_session_setup() when
reconnecting SMB sessions thus returning wrong value in
/proc/fs/cifs/DebugData.

Signed-off-by: Paulo Alcantara (SUSE) 
Cc: stable@kernel.org
Signed-off-by: Steve French

cifs: avoid deadlocks while updating iface

2022-06-24T14:17:56+00:00

We use cifs_tcp_ses_lock to protect a lot of things.
Not only does it protect the lists of connections, sessions,
tree connects, open file lists, etc., we also use it to
protect some fields in each of it's entries.

In this case, cifs_mark_ses_for_reconnect takes the
cifs_tcp_ses_lock to traverse the lists, and then calls
cifs_update_iface. However, that can end up calling
cifs_put_tcp_session, which picks up the same lock again.

Avoid this by taking a ref for the session, drop the lock,
and then call update iface.

Also, in cifs_update_iface, avoid nested locking of iface_lock
and chan_lock, as much as possible. When unavoidable, we need
to pick iface_lock first.

Signed-off-by: Shyam Prasad N 
Signed-off-by: Steve French

cifs: periodically query network interfaces from server

2022-06-23T00:51:43+00:00

Currently, we only query the server for network interfaces
information at the time of mount, and never afterwards.
This can be a problem, especially for services like Azure,
where the IP address of the channel endpoints can change
over time.

With this change, we schedule a 600s polling of this info
from the server for each tree connect.

An alternative for periodic polling was to do this only at
the time of reconnect. But this could delay the reconnect
time slightly. Also, there are some challenges w.r.t how
we have cifs_reconnect implemented today.

Signed-off-by: Shyam Prasad N 
Signed-off-by: Steve French

cifs: during reconnect, update interface if necessary

2022-06-23T00:51:43+00:00

Going forward, the plan is to periodically query the server
for it's interfaces (when multichannel is enabled).

This change allows checking for inactive interfaces during
reconnect, and reconnect to a new interface if necessary.

Signed-off-by: Shyam Prasad N 
Signed-off-by: Steve French

cifs: change iface_list from array to sorted linked list

2022-06-23T00:51:43+00:00

A server's published interface list can change over time, and needs
to be updated. We've storing iface_list as a simple array, which
makes it difficult to manipulate an existing list.

With this change, iface_list is modified into a linked list of
interfaces, which is kept sorted by speed.

Also added a reference counter for an iface entry, so that each
channel can maintain a backpointer to the iface and drop it
easily when needed.

Signed-off-by: Shyam Prasad N 
Signed-off-by: Steve French

smb3: use netname when available on secondary channels

2022-06-23T00:46:53+00:00

Some servers do not allow null netname contexts, which would cause
multichannel to revert to single channel when mounting to some
servers (e.g. Azure xSMB). The previous patch fixed that by avoiding
incorrectly sending the netname context when there would be a null
hostname sent in the netname context, while this patch fixes the null
hostname for the secondary channel by using the hostname of the
primary channel for the secondary channel.

Fixes: 4c14d7043fede ("cifs: populate empty hostnames for extra channels")
Signed-off-by: Shyam Prasad N 
Reviewed-by: Paulo Alcantara (SUSE) 
Signed-off-by: Steve French

smb3: fix empty netname context on secondary channels

2022-06-20T21:23:50+00:00

Some servers do not allow null netname contexts, which would cause
multichannel to revert to single channel when mounting to some
servers (e.g. Azure xSMB).

Fixes: 4c14d7043fede ("cifs: populate empty hostnames for extra channels")
Reviewed-by: Shyam Prasad N 
Reviewed-by: Paulo Alcantara (SUSE) 
Signed-off-by: Steve French