cifs: Add tracing for the cifs_tcon struct refcounting

Add tracing for the refcounting/lifecycle of the cifs_tcon struct, marking
different events with different labels and giving each tcon its own debug
ID so that the tracelines corresponding to individual tcons can be
distinguished. This can be enabled with:

echo 1 >/sys/kernel/debug/tracing/events/cifs/smb3_tcon_ref/enable

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: fix broken reconnect when password changing on the server by allowing password rotation

There are various use cases that are becoming more common in which password
changes are scheduled on a server(s) periodically but the clients connected
to this server need to stay connected (even in the face of brief network
reconnects) due to mounts which can not be easily unmounted and mounted at
will, and servers that do password rotation do not always have the ability
to tell the clients exactly when to the new password will be effective,
so add support for an alt password ("password2=") on mount (and also
remount) so that we can anticipate the upcoming change to the server
without risking breaking existing mounts.

An alternative would have been to use the kernel keyring for this but the
processes doing the reconnect do not have access to the keyring but do
have access to the ses structure.

Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: retrying on failed server close

In the current implementation, CIFS close sends a close to the
server and does not check for the success of the server close.
This patch adds functionality to check for server close return
status and retries in case of an EBUSY or EAGAIN error.

This can help avoid handle leaks

Cc: stable@vger.kernel.org
Signed-off-by: Ritvik Budhiraja <rbudhiraja@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: make sure server interfaces are requested only for SMB3+

Some code paths for querying server interfaces make a false
assumption that it will only get called for SMB3+. Since this
function now can get called from a generic code paths, the correct
thing to do is to have specific handler for this functionality
per SMB dialect, and call this handler.

This change adds such a handler and implements this handler only
for SMB 3.0 and 3.1.1.

Cc: stable@vger.kernel.org
Cc: Jan Čermák <sairon@sairon.cz>
Reported-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: negotiate compression algorithms

Change "compress=" mount option to a boolean flag, that, if set,
will enable negotiating compression algorithms with the server.

Do not de/compress anything for now.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: add support for WSL reparse points

Add support for creating special files via WSL reparse points when
using 'reparse=wsl' mount option. They're faster than NFS reparse
points because they don't require extra roundtrips to figure out what
->d_type a specific dirent is as such information is already stored in
query dir responses and then making getdents() calls faster.

Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: allow changing password during remount

There are cases where a session is disconnected and password has changed
on the server (or expired) for this user and this currently can not
be fixed without unmount and mounting again. This patch allows
remount to change the password (for the non Kerberos case, Kerberos
ticket refresh is handled differently) when the session is disconnected
and the user can not reconnect due to still using old password.

Future patches should also allow us to setup the keyring (cifscreds)
to have an "alternate password" so we would be able to change
the password before the session drops (without the risk of races
between when the password changes and the disconnect occurs -
ie cases where the old password is still needed because the new
password has not fully rolled out to all servers yet).

Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: update the same create_guid on replay

File open requests made to the server contain a
CreateGuid, which is used by the server to identify
the open request. If the same request needs to be
replayed, it needs to be sent with the same CreateGuid
in the durable handle v2 context.

Without doing so, we could end up leaking handles on
the server when:
1. multichannel is used AND
2. connection goes down, but not for all channels

This is because the replayed open request would have a
new CreateGuid and the server will treat this as a new
request and open a new handle.

This change fixes this by reusing the existing create_guid
stored in the cached fid struct.

REF: MS-SMB2 4.9 Replay Create Request on an Alternate Channel

Fixes: 4f1fffa23769 ("cifs: commands that are retried should have replay flag set")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: set correct d_type for reparse points under DFS mounts

Send query dir requests with an info level of
SMB_FIND_FILE_FULL_DIRECTORY_INFO rather than
SMB_FIND_FILE_DIRECTORY_INFO when the client is generating its own
inode numbers (e.g. noserverino) so that reparse tags still
can be parsed directly from the responses, but server won't
send UniqueId (server inode number)

Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: do not search for channel if server is terminating

In order to scale down the channels, the following sequence
of operations happen:
1. server struct is marked for terminate
2. the channel is deallocated in the ses->chans array
3. at a later point the cifsd thread actually terminates the server

Between 2 and 3, there can be calls to find the channel for
a server struct. When that happens, there can be an ugly warning
that's logged. But this is expected.

So this change does two things:
1. in cifs_ses_get_chan_index, if server->terminate is set, return
2. always make sure server->terminate is set with chan_lock held

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: avoid redundant calls to disable multichannel

When the server reports query network interface info call
as unsupported following a tree connect, it means that
multichannel is unsupported, even if the server capabilities
report otherwise.

When this happens, cifs_chan_skip_or_disable is called to
disable multichannel on the client. However, we only need
to call this when multichannel is currently setup.

Fixes: f591062bdbf4 ("cifs: handle servers that still advertise multichannel after disabling")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: make sure that channel scaling is done only once

Following a successful cifs_tree_connect, we have the code
to scale up/down the number of channels in the session.
However, it is not protected by a lock today.

As a result, this code can be executed by several processes
that select the same channel. The core functions handle this
well, as they pick chan_lock. However, we've seen cases where
smb2_reconnect throws some warnings.

To fix that, this change introduces a flags bitmap inside the
cifs_ses structure. A new flag type is used to ensure that
only one process enters this section at any time.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: fix stray unlock in cifs_chan_skip_or_disable

A recent change moved the code that decides to skip
a channel or disable multichannel entirely, into a
helper function.

During this, a mutex_unlock of the session_mutex
should have been removed. Doing that here.

Fixes: f591062bdbf4 ("cifs: handle servers that still advertise multichannel after disabling")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: set replay flag for retries of write command

Similar to the rest of the commands, this is a change
to add replay flags on retry. This one does not add a
back-off, considering that we may want to flush a write
ASAP to the server. Considering that this will be a
flush of cached pages, the retrans value is also not
honoured.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: commands that are retried should have replay flag set

MS-SMB2 states that the header flag SMB2_FLAGS_REPLAY_OPERATION
needs to be set when a command needs to be retried, so that
the server is aware that this is a replay for an operation that
appeared before.

This can be very important, for example, for state changing
operations and opens which get retried following a reconnect;
since the client maybe unaware of the status of the previous
open.

This is particularly important for multichannel scenario, since
disconnection of one connection does not mean that the session
is lost. The requests can be replayed on another channel.

This change also makes use of exponential back-off before replays
and also limits the number of retries to "retrans" mount option
value.

Also, this change does not modify the read/write codepath.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: handle servers that still advertise multichannel after disabling

Some servers like Azure SMB servers always advertise multichannel
capability in server capabilities list. Such servers return error
STATUS_NOT_IMPLEMENTED for ioctl calls to query server interfaces,
and expect clients to consider that as a sign that they do not support
multichannel.

We already handled this at mount time. Soon after the tree connect,
we query server interfaces. And when server returned STATUS_NOT_IMPLEMENTED,
we kept interface list as empty. When cifs_try_adding_channels gets
called, it would not find any interfaces, so will not add channels.

For the case where an active multichannel mount exists, and multichannel
is disabled by such a server, this change will now allow the client
to disable secondary channels on the mount. It will check the return
status of query server interfaces call soon after a tree reconnect.
If the return status is EOPNOTSUPP, then instead of the check to add
more channels, we'll disable the secondary channels instead.

For better code reuse, this change also moves the common code for
disabling multichannel to a helper function.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: reschedule periodic query for server interfaces

Today, we schedule periodic query for server interfaces
once every 10 minutes once a tree connection has been
established. Recent change to handle disabling of
multichannel disabled this delayed work.

This change reenables it following a reconnect, and
the server advertises multichannel.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix parsing of SMB3.1.1 POSIX create context

The data offset for the SMB3.1.1 POSIX create context will always be
8-byte aligned so having the check 'noff + nlen >= doff' in
smb2_parse_contexts() is wrong as it will lead to -EINVAL because noff
+ nlen == doff.

Fix the sanity check to correctly handle aligned create context data.

Fixes: af1689a9b770 ("smb: client: fix potential OOBs in smb2_parse_contexts()")
Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: pick channel for tcon and tdis

Today, the tree connect and disconnect requests are
sent on the primary channel only. However, the new
multichannel logic allows the session to remain active
even if one of the channels are alive. So a tree connect
can now be triggered during a reconnect on any of
its channels.

This change changes tcon and tdis calls to pick an
active channel instead of the first one.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: remove redundant variable tcon_exist

The variable tcon_exist is being assigned however it is never read, the
variable is redundant and can be removed.

Cleans up clang scan build warning:
warning: Although the value stored to 'tcon_exist' is used in
the enclosing expression, the value is never actually readfrom
'tcon_exist' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: Pass unbyteswapped eof value into SMB2_set_eof()

Change SMB2_set_eof() to take eof as CPU order rather than __le64 and pass
it directly rather than by pointer. This moves the conversion down into
SMB_set_eof() rather than all of its callers and means we don't need to
undo it for the traceline.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: fix a pending undercount of srv_count

The following commit reverted the changes to ref count
the server struct while scheduling a reconnect work:
823342524868 Revert "cifs: reconnect work should have reference on server struct"

However, a following change also introduced scheduling
of reconnect work, and assumed ref counting. This change
fixes that as well.

Fixes umount problems like:

[73496.157838] CPU: 5 PID: 1321389 Comm: umount Tainted: G W OE 6.7.0-060700rc6-generic #202312172332
[73496.157841] Hardware name: LENOVO 20MAS08500/20MAS08500, BIOS N2CET67W (1.50 ) 12/15/2022
[73496.157843] RIP: 0010:cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.157906] Code: 5d 31 c0 31 d2 31 f6 31 ff c3 cc cc cc cc e8 4a 6e 14 e6 e9 f6 fe ff ff be 03 00 00 00 48 89 d7 e8 78 26 b3 e5 e9 e4 fe ff ff <0f> 0b e9 b1 fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90
[73496.157908] RSP: 0018:ffffc90003bcbcb8 EFLAGS: 00010286
[73496.157911] RAX: 00000000ffffffff RBX: ffff8885830fa800 RCX: 0000000000000000
[73496.157913] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[73496.157915] RBP: ffffc90003bcbcc8 R08: 0000000000000000 R09: 0000000000000000
[73496.157917] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[73496.157918] R13: ffff8887d56ba800 R14: 00000000ffffffff R15: ffff8885830fa800
[73496.157920] FS: 00007f1ff0e33800(0000) GS:ffff88887ba80000(0000) knlGS:0000000000000000
[73496.157922] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[73496.157924] CR2: 0000115f002e2010 CR3: 00000003d1e24005 CR4: 00000000003706f0
[73496.157926] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[73496.157928] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[73496.157929] Call Trace:
[73496.157931] <TASK>
[73496.157933] ? show_regs+0x6d/0x80
[73496.157936] ? __warn+0x89/0x160
[73496.157939] ? cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.157976] ? report_bug+0x17e/0x1b0
[73496.157980] ? handle_bug+0x51/0xa0
[73496.157983] ? exc_invalid_op+0x18/0x80
[73496.157985] ? asm_exc_invalid_op+0x1b/0x20
[73496.157989] ? cifs_put_tcp_session+0x17d/0x190 [cifs]
[73496.158023] ? cifs_put_tcp_session+0x1e/0x190 [cifs]
[73496.158057] __cifs_put_smb_ses+0x2b5/0x540 [cifs]
[73496.158090] ? tconInfoFree+0xc2/0x120 [cifs]
[73496.158130] cifs_put_tcon.part.0+0x108/0x2b0 [cifs]
[73496.158173] cifs_put_tlink+0x49/0x90 [cifs]
[73496.158220] cifs_umount+0x56/0xb0 [cifs]
[73496.158258] cifs_kill_sb+0x52/0x60 [cifs]
[73496.158306] deactivate_locked_super+0x32/0xc0
[73496.158309] deactivate_super+0x46/0x60
[73496.158311] cleanup_mnt+0xc3/0x170
[73496.158314] __cleanup_mnt+0x12/0x20
[73496.158330] task_work_run+0x5e/0xa0
[73496.158333] exit_to_user_mode_loop+0x105/0x130
[73496.158336] exit_to_user_mode_prepare+0xa5/0xb0
[73496.158338] syscall_exit_to_user_mode+0x29/0x60
[73496.158341] do_syscall_64+0x6c/0xf0
[73496.158344] ? syscall_exit_to_user_mode+0x37/0x60
[73496.158346] ? do_syscall_64+0x6c/0xf0
[73496.158349] ? exit_to_user_mode_prepare+0x30/0xb0
[73496.158353] ? syscall_exit_to_user_mode+0x37/0x60
[73496.158355] ? do_syscall_64+0x6c/0xf0

Reported-by: Robert Morris <rtm@csail.mit.edu>
Fixes: 705fc522fe9d ("cifs: handle when server starts supporting multichannel")
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix OOB in SMB2_query_info_init()

A small CIFS buffer (448 bytes) isn't big enough to hold
SMB2_QUERY_INFO request along with user's input data from
CIFS_QUERY_INFO ioctl. That is, if the user passed an input buffer >
344 bytes, the client will memcpy() off the end of @req->Buffer in
SMB2_query_info_init() thus causing the following KASAN splat:

BUG: KASAN: slab-out-of-bounds in SMB2_query_info_init+0x242/0x250 [cifs]
Write of size 1023 at addr ffff88801308c5a8 by task a.out/1240

CPU: 1 PID: 1240 Comm: a.out Not tainted 6.7.0-rc4 #5
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x4a/0x80
print_report+0xcf/0x650
? srso_alias_return_thunk+0x5/0xfbef5
? srso_alias_return_thunk+0x5/0xfbef5
? srso_alias_return_thunk+0x5/0xfbef5
? __phys_addr+0x46/0x90
kasan_report+0xd8/0x110
? SMB2_query_info_init+0x242/0x250 [cifs]
? SMB2_query_info_init+0x242/0x250 [cifs]
kasan_check_range+0x105/0x1b0
__asan_memcpy+0x3c/0x60
SMB2_query_info_init+0x242/0x250 [cifs]
? __pfx_SMB2_query_info_init+0x10/0x10 [cifs]
? srso_alias_return_thunk+0x5/0xfbef5
? smb_rqst_len+0xa6/0xc0 [cifs]
smb2_ioctl_query_info+0x4f4/0x9a0 [cifs]
? __pfx_smb2_ioctl_query_info+0x10/0x10 [cifs]
? __pfx_cifsConvertToUTF16+0x10/0x10 [cifs]
? kasan_set_track+0x25/0x30
? srso_alias_return_thunk+0x5/0xfbef5
? __kasan_kmalloc+0x8f/0xa0
? srso_alias_return_thunk+0x5/0xfbef5
? cifs_strndup_to_utf16+0x12d/0x1a0 [cifs]
? __build_path_from_dentry_optional_prefix+0x19d/0x2d0 [cifs]
? __pfx_smb2_ioctl_query_info+0x10/0x10 [cifs]
cifs_ioctl+0x11c7/0x1de0 [cifs]
? __pfx_cifs_ioctl+0x10/0x10 [cifs]
? srso_alias_return_thunk+0x5/0xfbef5
? rcu_is_watching+0x23/0x50
? srso_alias_return_thunk+0x5/0xfbef5
? __rseq_handle_notify_resume+0x6cd/0x850
? __pfx___schedule+0x10/0x10
? blkcg_iostat_update+0x250/0x290
? srso_alias_return_thunk+0x5/0xfbef5
? ksys_write+0xe9/0x170
__x64_sys_ioctl+0xc9/0x100
do_syscall_64+0x47/0xf0
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f893dde49cf
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48
89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89>
c2 3d 00 f0 ff ff 77 18 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffc03ff4160 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffc03ff4378 RCX: 00007f893dde49cf
RDX: 00007ffc03ff41d0 RSI: 00000000c018cf07 RDI: 0000000000000003
RBP: 00007ffc03ff4260 R08: 0000000000000410 R09: 0000000000000001
R10: 00007f893dce7300 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc03ff4388 R14: 00007f893df15000 R15: 0000000000406de0
</TASK>

Fix this by increasing size of SMB2_QUERY_INFO request buffers and
validating input length to prevent other callers from overflowing @req
in SMB2_query_info_init() as well.

Fixes: f5b05d622a3e ("cifs: add IOCTL for QUERY_INFO passthrough to userspace")
Cc: stable@vger.kernel.org
Reported-by: Robert Morris <rtm@csail.mit.edu>
Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix potential OOBs in smb2_parse_contexts()

Validate offsets and lengths before dereferencing create contexts in
smb2_parse_contexts().

This fixes following oops when accessing invalid create contexts from
server:

BUG: unable to handle page fault for address: ffff8881178d8cc3
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 4a01067 P4D 4a01067 PUD 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 3 PID: 1736 Comm: mount.cifs Not tainted 6.7.0-rc4 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
RIP: 0010:smb2_parse_contexts+0xa0/0x3a0 [cifs]
Code: f8 10 75 13 48 b8 93 ad 25 50 9c b4 11 e7 49 39 06 0f 84 d2 00
00 00 8b 45 00 85 c0 74 61 41 29 c5 48 01 c5 41 83 fd 0f 76 55 <0f> b7
7d 04 0f b7 45 06 4c 8d 74 3d 00 66 83 f8 04 75 bc ba 04 00
RSP: 0018:ffffc900007939e0 EFLAGS: 00010216
RAX: ffffc90000793c78 RBX: ffff8880180cc000 RCX: ffffc90000793c90
RDX: ffffc90000793cc0 RSI: ffff8880178d8cc0 RDI: ffff8880180cc000
RBP: ffff8881178d8cbf R08: ffffc90000793c22 R09: 0000000000000000
R10: ffff8880180cc000 R11: 0000000000000024 R12: 0000000000000000
R13: 0000000000000020 R14: 0000000000000000 R15: ffffc90000793c22
FS: 00007f873753cbc0(0000) GS:ffff88806bc00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8881178d8cc3 CR3: 00000000181ca000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
? __die+0x23/0x70
? page_fault_oops+0x181/0x480
? search_module_extables+0x19/0x60
? srso_alias_return_thunk+0x5/0xfbef5
? exc_page_fault+0x1b6/0x1c0
? asm_exc_page_fault+0x26/0x30
? smb2_parse_contexts+0xa0/0x3a0 [cifs]
SMB2_open+0x38d/0x5f0 [cifs]
? smb2_is_path_accessible+0x138/0x260 [cifs]
smb2_is_path_accessible+0x138/0x260 [cifs]
cifs_is_path_remote+0x8d/0x230 [cifs]
cifs_mount+0x7e/0x350 [cifs]
cifs_smb3_do_mount+0x128/0x780 [cifs]
smb3_get_tree+0xd9/0x290 [cifs]
vfs_get_tree+0x2c/0x100
? capable+0x37/0x70
path_mount+0x2d7/0xb80
? srso_alias_return_thunk+0x5/0xfbef5
? _raw_spin_unlock_irqrestore+0x44/0x60
__x64_sys_mount+0x11a/0x150
do_syscall_64+0x47/0xf0
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f8737657b1e

Reported-by: Robert Morris <rtm@csail.mit.edu>
Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: reconnect worker should take reference on server struct unconditionally

Reconnect worker currently assumes that the server struct
is alive and only takes reference on the server if it needs
to call smb2_reconnect.

With the new ability to disable channels based on whether the
server has multichannel disabled, this becomes a problem when
we need to disable established channels. While disabling the
channels and deallocating the server, there could be reconnect
work that could not be cancelled (because it started).

This change forces the reconnect worker to unconditionally
take a reference on the server when it runs.

Also, this change now allows smb2_reconnect to know if it was
called by the reconnect worker. Based on this, the cifs_put_tcp_session
can decide whether it can cancel the reconnect work synchronously or not.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Revert "cifs: reconnect work should have reference on server struct"

This reverts commit 19a4b9d6c372cab6a3b2c9a061a236136fe95274.

This earlier commit was making an assumption that each mod_delayed_work
called for the reconnect work would result in smb2_reconnect_server
being called twice. This assumption turns out to be untrue. So reverting
this change for now.

I will submit a follow-up patch to fix the actual problem in a different
way.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client, common: fix fortify warnings

When compiling with gcc version 14.0.0 20231126 (experimental)
and CONFIG_FORTIFY_SOURCE=y, I've noticed the following:

In file included from ./include/linux/string.h:295,
from ./include/linux/bitmap.h:12,
from ./include/linux/cpumask.h:12,
from ./arch/x86/include/asm/paravirt.h:17,
from ./arch/x86/include/asm/cpuid.h:62,
from ./arch/x86/include/asm/processor.h:19,
from ./arch/x86/include/asm/cpufeature.h:5,
from ./arch/x86/include/asm/thread_info.h:53,
from ./include/linux/thread_info.h:60,
from ./arch/x86/include/asm/preempt.h:9,
from ./include/linux/preempt.h:79,
from ./include/linux/spinlock.h:56,
from ./include/linux/wait.h:9,
from ./include/linux/wait_bit.h:8,
from ./include/linux/fs.h:6,
from fs/smb/client/smb2pdu.c:18:
In function 'fortify_memcpy_chk',
inlined from '__SMB2_close' at fs/smb/client/smb2pdu.c:3480:4:
./include/linux/fortify-string.h:588:25: warning: call to '__read_overflow2_field'
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Wattribute-warning]
588 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

and:

In file included from ./include/linux/string.h:295,
from ./include/linux/bitmap.h:12,
from ./include/linux/cpumask.h:12,
from ./arch/x86/include/asm/paravirt.h:17,
from ./arch/x86/include/asm/cpuid.h:62,
from ./arch/x86/include/asm/processor.h:19,
from ./arch/x86/include/asm/cpufeature.h:5,
from ./arch/x86/include/asm/thread_info.h:53,
from ./include/linux/thread_info.h:60,
from ./arch/x86/include/asm/preempt.h:9,
from ./include/linux/preempt.h:79,
from ./include/linux/spinlock.h:56,
from ./include/linux/wait.h:9,
from ./include/linux/wait_bit.h:8,
from ./include/linux/fs.h:6,
from fs/smb/client/cifssmb.c:17:
In function 'fortify_memcpy_chk',
inlined from 'CIFS_open' at fs/smb/client/cifssmb.c:1248:3:
./include/linux/fortify-string.h:588:25: warning: call to '__read_overflow2_field'
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Wattribute-warning]
588 | __read_overflow2_field(q_size_field, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In both cases, the fortification logic inteprets calls to 'memcpy()' as an
attempts to copy an amount of data which exceeds the size of the specified
field (i.e. more than 8 bytes from __le64 value) and thus issues an overread
warning. Both of these warnings may be silenced by using the convenient
'struct_group()' quirk.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: handle when server stops supporting multichannel

When a server stops supporting multichannel, we will
keep attempting reconnects to the secondary channels today.
Avoid this by freeing extra channels when negotiate
returns no multichannel support.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: handle when server starts supporting multichannel

When the user mounts with multichannel option, but the
server does not support it, there can be a time in future
where it can be supported.

With this change, such a case is handled.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>

cifs: reconnect work should have reference on server struct

The delayed work for reconnect takes server struct
as a parameter. But it does so without holding a ref
to it. Normally, this may not show a problem as
the reconnect work is only cancelled on umount.

However, since we now plan to support scaling down of
channels, and the scale down can happen from reconnect
work itself, we need to fix it.

This change takes a reference on the server struct
before it is passed to the delayed work. And drops
the reference in the delayed work itself. Or if
the delayed work is successfully cancelled, by the
process that cancels it.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: fix confusing debug message

The message said it was an invalid mode, when it was intentionally
not set. Fix confusing message logged to dmesg.

Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: do not start laundromat thread when dir leases
disabled

When no directory lease support, or for IPC shares where directories
can not be opened, do not start an unneeded laundromat thread for
that mount (it wastes resources).

Fixes: d14de8067e3f ("cifs: Add a laundromat thread for cached directories")
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Acked-by: Tom Talpey <tom@talpey.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: fix some minor typos and repeated words

Minor cleanup pointed out by checkpatch (repeated words, missing blank
lines) in smb2pdu.c and old header location referred to in transport.c

Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: move server check earlier when setting channel sequence number

Smatch warning pointed out by Dan Carpenter:

fs/smb/client/smb2pdu.c:105 smb2_hdr_assemble()
warn: variable dereferenced before check 'server' (see line 95)

Fixes: 09ee7a3bf866 ("[SMB3] send channel sequence number in SMB3 requests after reconnects")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client: Use common code in client

Now we've got the common code, use it for the client as well.
Note there's a change here where we're using the server version of
UniStrcat now which had different types (__le16 vs wchar_t) but
it's not interpreting the value other than checking for 0, however
we do need casts to keep sparse happy.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

SMB3: rename macro CIFS_SERVER_IS_CHAN to avoid confusion

Since older dialects such as CIFS do not support multichannel
the macro CIFS_SERVER_IS_CHAN can be confusing (it requires SMB 3
or later) so shorten its name to "SERVER_IS_CHAN"

Suggested-by: Tom Talpey <tom@talpey.com>
Acked-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

[SMB3] send channel sequence number in SMB3 requests after reconnects

The ChannelSequence field in the SMB3 header is supposed to be
increased after reconnect to allow the server to distinguish
requests from before and after the reconnect. We had always
been setting it to zero. There are cases where incrementing
ChannelSequence on requests after network reconnects can reduce
the chance of data corruptions.

See MS-SMB2 3.2.4.1 and 3.2.7.1

Signed-off-by: Steve French <stfrench@microsoft.com>
Cc: stable@vger.kernel.org # 5.16+

cifs: fix charset issue in reconnection

We need to specify charset, like "iocharset=utf-8", in mount options for
Chinese path if the nls_default don't support it, such as iso8859-1, the
default value for CONFIG_NLS_DEFAULT.

But now in reconnection the nls_default is used, instead of the one we
specified and used in mount, and this can lead to mount failure.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: fix session state check in reconnect to avoid use-after-free issue

Don't collect exiting session in smb2_reconnect_server(), because it
will be released soon.

Note that the exiting session will stay in server->smb_ses_list until
it complete the cifs_free_ipc() and logoff() and then delete itself
from the list.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: fix max_credits implementation

The current implementation of max_credits on the client does
not work because the CreditRequest logic for several commands
does not take max_credits into account.

Still, we can end up asking the server for more credits, depending
on the number of credits in flight. For this, we need to
limit the credits while parsing the responses too.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb3: missing null check in SMB2_change_notify

If plen is null when passed in, we only checked for null
in one of the two places where it could be used. Although
plen is always valid (not null) for current callers of the
SMB2_change_notify function, this change makes it more consistent.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/all/202305251831.3V1gbbFs-lkp@intel.com/
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: move client and server files to common directory fs/smb

Move CIFS/SMB3 related client and server files (cifs.ko and ksmbd.ko
and helper modules) to new fs/smb subdirectory:

fs/cifs --> fs/smb/client
fs/ksmbd --> fs/smb/server
fs/smbfs_common --> fs/smb/common

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>