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: replace deprecated strncpy with strscpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

In cifssmb.c:
Using strncpy with a length argument equal to strlen(src) is generally
dangerous because it can cause string buffers to not be NUL-terminated.
In this case, however, there was extra effort made to ensure the buffer
was NUL-terminated via a manual NUL-byte assignment. In an effort to rid
the kernel of strncpy() use, let's swap over to using strscpy() which
guarantees NUL-termination on the destination buffer.

To handle the case where ea_name is NULL, let's use the ?: operator to
substitute in an empty string, thereby allowing strscpy to still
NUL-terminate the destintation string.

Interesting note: this flex array buffer may go on to also have some
value encoded after the NUL-termination:
| if (ea_value_len)
| memcpy(parm_data->list.name + name_len + 1,
| ea_value, ea_value_len);

Now for smb2ops.c and smb2transport.c:
Both of these cases are simple, strncpy() is used to copy string
literals which have a length less than the destination buffer's size. We
can simply swap in the new 2-argument version of strscpy() introduced in
Commit e6584c3964f2f ("string: Allow 2-argument strscpy()").

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: fix check of rc in function generate_smb3signingkey

Remove extra check after condition, add check after generating key
for encryption. The check is needed to return non zero rc before
rewriting it with generating key for decryption.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Fixes: d70e9fa55884 ("cifs: try opening channels after mounting")
Signed-off-by: Ekaterina Esina <eesina@astralinux.ru>
Co-developed-by: Anastasia Belova <abelova@astralinux.ru>
Signed-off-by: Anastasia Belova <abelova@astralinux.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: handle cases where a channel is closed

So far, SMB multichannel could only scale up, but not
scale down the number of channels. In this series of
patch, we now allow the client to deal with the case
of multichannel disabled on the server when the share
is mounted. With that change, we now need the ability
to scale down the channels.

This change allows the client to deal with cases of
missing channels more gracefully.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.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: client: fix missed ses refcounting

Use new cifs_smb_ses_inc_refcount() helper to get an active reference
of @ses and @ses->dfs_root_ses (if set). This will prevent
@ses->dfs_root_ses of being put in the next call to cifs_put_smb_ses()
and thus potentially causing an use-after-free bug.

Fixes: 8e3554150d6c ("cifs: fix sharing of DFS connections")
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs: new dynamic tracepoint to track ses not found errors

It is perfectly valid to not find session not found errors
when a reconnect of a session happens when requests for the
same session are happening in parallel.

We had these log messages as VFS logs. My last change dumped
these logs as FYI logs.

This change just creates a new dynamic tracepoint to capture
events of this type, just in case it is useful while
debugging issues in the future.

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

cifs: log session id when a matching ses is not found

We do not log the session id in crypt_setup when a matching
session is not found. Printing the session id helps debugging
here. This change does just that.

This change also changes this log to FYI, since it is normal to
see then during a reconnect. Doing the same for a similar log
in case of signed connections.

The plan is to have a tracepoint for this event, so that we will
be able to see this event if need be. That will be done as
another change.

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

cifs: fix session state check in smb2_find_smb_ses

Chech the session state and skip it if it's exiting.

Signed-off-by: Winston Wen <wentao@uniontech.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.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>