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>

smb: client: fix potential UAF in smb2_is_valid_oplock_break()

Skip sessions that are being teared down (status == SES_EXITING) to
avoid UAF.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix potential UAF in smb2_is_valid_lease_break()

Skip sessions that are being teared down (status == SES_EXITING) to
avoid UAF.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix potential OOB in smb2_dump_detail()

Validate SMB message with ->check_message() before calling
->calc_smb_size().

This fixes CVE-2023-6610.

Reported-by: j51569436@gmail.com
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218219
Cc; stable@vger.kernel.org
Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

smb: client: fix NULL deref in asn1_ber_decoder()

If server replied SMB2_NEGOTIATE with a zero SecurityBufferOffset,
smb2_get_data_area() sets @len to non-zero but return NULL, so
decode_negTokeninit() ends up being called with a NULL @security_blob:

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 2 PID: 871 Comm: mount.cifs Not tainted 6.7.0-rc4 #2
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
RIP: 0010:asn1_ber_decoder+0x173/0xc80
Code: 01 4c 39 2c 24 75 09 45 84 c9 0f 85 2f 03 00 00 48 8b 14 24 4c 29 ea 48 83 fa 01 0f 86 1e 07 00 00 48 8b 74 24 28 4d 8d 5d 01 <42> 0f b6 3c 2e 89 fa 40 88 7c 24 5c f7 d2 83 e2 1f 0f 84 3d 07 00
RSP: 0018:ffffc9000063f950 EFLAGS: 00010202
RAX: 0000000000000002 RBX: 0000000000000000 RCX: 000000000000004a
RDX: 000000000000004a RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 000000000000004d R15: 0000000000000000
FS: 00007fce52b0fbc0(0000) GS:ffff88806ba00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000001ae64000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
<TASK>
? __die+0x23/0x70
? page_fault_oops+0x181/0x480
? __stack_depot_save+0x1e6/0x480
? exc_page_fault+0x6f/0x1c0
? asm_exc_page_fault+0x26/0x30
? asn1_ber_decoder+0x173/0xc80
? check_object+0x40/0x340
decode_negTokenInit+0x1e/0x30 [cifs]
SMB2_negotiate+0xc99/0x17c0 [cifs]
? smb2_negotiate+0x46/0x60 [cifs]
? srso_alias_return_thunk+0x5/0xfbef5
smb2_negotiate+0x46/0x60 [cifs]
cifs_negotiate_protocol+0xae/0x130 [cifs]
cifs_get_smb_ses+0x517/0x1040 [cifs]
? srso_alias_return_thunk+0x5/0xfbef5
? srso_alias_return_thunk+0x5/0xfbef5
? queue_delayed_work_on+0x5d/0x90
cifs_mount_get_session+0x78/0x200 [cifs]
dfs_mount_share+0x13a/0x9f0 [cifs]
? srso_alias_return_thunk+0x5/0xfbef5
? lock_acquire+0xbf/0x2b0
? find_nls+0x16/0x80
? srso_alias_return_thunk+0x5/0xfbef5
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: 0033:0x7fce52c2ab1e

Fix this by setting @len to zero when @off == 0 so callers won't
attempt to dereference non-existing data areas.

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>

smb: client: fix potential deadlock when releasing mids

All release_mid() callers seem to hold a reference of @mid so there is
no need to call kref_put(&mid->refcount, __release_mid) under
@server->mid_lock spinlock. If they don't, then an use-after-free bug
would have occurred anyways.

By getting rid of such spinlock also fixes a potential deadlock as
shown below

CPU 0 CPU 1
------------------------------------------------------------------
cifs_demultiplex_thread() cifs_debug_data_proc_show()
release_mid()
spin_lock(&server->mid_lock);
spin_lock(&cifs_tcp_ses_lock)
spin_lock(&server->mid_lock)
__release_mid()
smb2_find_smb_tcon()
spin_lock(&cifs_tcp_ses_lock) *deadlock*

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.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>

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>