ksmbd: add support for durable handles v1/v2

Durable file handles allow reopening a file preserved on a short
network outage and transparent client reconnection within a timeout.
i.e. Durable handles aren't necessarily cleaned up when the opening
process terminates.

This patch add support for durable handle version 1 and 2.

To prove durable handles work on ksmbd, I have tested this patch with
the following smbtorture tests:

smb2.durable-open.open-oplock
smb2.durable-open.open-lease
smb2.durable-open.reopen1
smb2.durable-open.reopen1a
smb2.durable-open.reopen1a-lease
smb2.durable-open.reopen2
smb2.durable-open.reopen2a
smb2.durable-open.reopen2-lease
smb2.durable-open.reopen2-lease-v2
smb2.durable-open.reopen3
smb2.durable-open.reopen4
smb2.durable-open.delete_on_close2
smb2.durable-open.file-position
smb2.durable-open.lease
smb2.durable-open.alloc-size
smb2.durable-open.read-only
smb2.durable-v2-open.create-blob
smb2.durable-v2-open.open-oplock
smb2.durable-v2-open.open-lease
smb2.durable-v2-open.reopen1
smb2.durable-v2-open.reopen1a
smb2.durable-v2-open.reopen1a-lease
smb2.durable-v2-open.reopen2
smb2.durable-v2-open.reopen2b

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: lazy v2 lease break on smb2_write()

Don't immediately send directory lease break notification on smb2_write().
Instead, It postpones it until smb2_close().

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: send v2 lease break notification for directory

If client send different parent key, different client guid, or there is
no parent lease key flags in create context v2 lease, ksmbd send lease
break to client.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: separately allocate ci per dentry

xfstests generic/002 test fail when enabling smb2 leases feature.
This test create hard link file, but removeal failed.
ci has a file open count to count file open through the smb client,
but in the case of hard link files, The allocation of ci per inode
cause incorrectly open count for file deletion. This patch allocate
ci per dentry to counts open counts for hard link.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

ksmbd: fix race condition with fp

fp can used in each command. If smb2_close command is coming at the
same time, UAF issue can happen by race condition.

Time
+
Thread A | Thread B1 B2 .... B5
smb2_open | smb2_close
|
__open_id |
insert fp to file_table |
|
| atomic_dec_and_test(&fp->refcount)
| if fp->refcount == 0, free fp by kfree.
// UAF! |
use fp |
+
This patch add f_state not to use freed fp is used and not to free fp in
use.

Reported-by: luosili <rootlab@huawei.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
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>