linux.git/fs/cifs, branch v4.11

cifs: Do not send echoes before Negotiate is complete

2017-04-17T20:44:23+00:00

commit 4fcd1813e640 ("Fix reconnect to not defer smb3 session reconnect
long after socket reconnect") added support for Negotiate requests to
be initiated by echo calls.

To avoid delays in calling echo after a reconnect, I added the patch
introduced by the commit b8c600120fc8 ("Call echo service immediately
after socket reconnect").

This has however caused a regression with cifs shares which do not have
support for echo calls to trigger Negotiate requests. On connections
which need to call Negotiation, the echo calls trigger an error which
triggers a reconnect which in turn triggers another echo call. This
results in a loop which is only broken when an operation is performed on
the cifs share. For an idle share, it can DOS a server.

The patch uses the smb_operation can_echo() for cifs so that it is
called only if connection has been already been setup.

kernel bz: 194531

Signed-off-by: Sachin Prabhu 
Tested-by: Jonathan Liu 
Acked-by: Pavel Shilovsky 
CC: Stable 
Signed-off-by: Steve French

CIFS: Fix SMB3 mount without specifying a security mechanism

2017-04-13T15:03:26+00:00

Commit ef65aaede23f ("smb2: Enforce sec= mount option") changed the
behavior of a mount command to enforce a specified security mechanism
during mounting. On another hand according to the spec if SMB3 server
doesn't respond with a security context it implies that it supports
NTLMSSP. The current code doesn't keep it in mind and fails a mount
for such servers if no security mechanism is specified. Fix this by
indicating that a server supports NTLMSSP if a security context isn't
returned during negotiate phase. This allows the code to use NTLMSSP
by default for SMB3 mounts.

Signed-off-by: Pavel Shilovsky 
Signed-off-by: Steve French

CIFS: store results of cifs_reopen_file to avoid infinite wait

2017-04-11T04:36:39+00:00

This fixes Continuous Availability when errors during
file reopen are encountered.

cifs_user_readv and cifs_user_writev would wait for ever if
results of cifs_reopen_file are not stored and for later inspection.

In fact, results are checked and, in case of errors, a chain
of function calls leading to reads and writes to be scheduled in
a separate thread is skipped.
These threads will wake up the corresponding waiters once reads
and writes are done.

However, given the return value is not stored, when rc is checked
for errors a previous one (always zero) is inspected instead.
This leads to pending reads/writes added to the list, making
cifs_user_readv and cifs_user_writev wait for ever.

Signed-off-by: Germano Percossi 
Reviewed-by: Pavel Shilovsky 
CC: Stable 
Signed-off-by: Steve French

CIFS: remove bad_network_name flag

2017-04-11T04:36:39+00:00

STATUS_BAD_NETWORK_NAME can be received during node failover,
causing the flag to be set and making the reconnect thread
always unsuccessful, thereafter.

Once the only place where it is set is removed, the remaining
bits are rendered moot.

Removing it does not prevent "mount" from failing when a non
existent share is passed.

What happens when the share really ceases to exist while the
share is mounted is undefined now as much as it was before.

Signed-off-by: Germano Percossi 
Reviewed-by: Pavel Shilovsky 
CC: Stable 
Signed-off-by: Steve French

CIFS: reconnect thread reschedule itself

2017-04-11T04:36:39+00:00

In case of error, smb2_reconnect_server reschedule itself
with a delay, to avoid being too aggressive.

Signed-off-by: Germano Percossi 
Reviewed-by: Pavel Shilovsky 
CC: Stable 
Signed-off-by: Steve French

CIFS: handle guest access errors to Windows shares

2017-04-11T04:36:38+00:00

Commit 1a967d6c9b39c226be1b45f13acd4d8a5ab3dc44 ("correctly to
anonymous authentication for the NTLM(v2) authentication") introduces
a regression in handling errors related to attempting a guest
connection to a Windows share which requires authentication. This
should result in a permission denied error but actually causes the
kernel module to enter a never-ending loop trying to follow a DFS
referal which doesn't exist.

The base cause of this is the failure now occurs later in the process
during tree connect and not at the session setup setup and all errors
in tree connect are interpreted as needing to follow the DFS paths
which isn't in this case correct. So, check the returned error against
EACCES and fail if this is returned error.

Feedback from Aurelien:

PS> net user guest /activate:no
PS> mkdir C:\guestshare
PS> icacls C:\guestshare /grant 'Everyone:(OI)(CI)F'
PS> new-smbshare -name guestshare -path C:\guestshare -fullaccess Everyone

I've tested v3.10, v4.4, master, master+your patch using default options
(empty or no user "NU") and user=abc (U).

NT_LOGON_FAILURE in session setup: LF
This is what you seem to have in 3.10.

NT_ACCESS_DENIED in tree connect to the share: AD
This is what you get before your infinite loop.

No infinite DFS loop :(
All these issues result in mount failing very fast with permission denied.

I guess it could be from either the Windows version or the share/folder
ACL. A deeper analysis of the packets might reveal more.

In any case I did not notice any issues for on a basic DFS setup with
the patch so I don't think it introduced any regressions, which is
probably all that matters. It still bothers me a little I couldn't hit
the bug.

I've included kernel output w/ debugging output and network capture of
my tests if anyone want to have a look at it. (master+patch = ml-guestfix).

Signed-off-by: Mark Syms
Reviewed-by: Aurelien Aptel
Tested-by: Aurelien Aptel
Acked-by: Pavel Shilovsky
Signed-off-by: Steve French

CIFS: Fix null pointer deref during read resp processing

2017-04-11T04:36:38+00:00

Currently during receiving a read response mid->resp_buf can be
NULL when it is being passed to cifs_discard_remaining_data() from
cifs_readv_discard(). Fix it by always passing server->smallbuf
instead and initializing mid->resp_buf at the end of read response
processing.

Signed-off-by: Pavel Shilovsky 
CC: Stable 
Acked-by: Sachin Prabhu 
Signed-off-by: Steve French

Reset TreeId to zero on SMB2 TREE_CONNECT

2017-04-07T13:04:41+00:00

Currently the cifs module breaks the CIFS specs on reconnect as
described in http://msdn.microsoft.com/en-us/library/cc246529.aspx:

"TreeId (4 bytes): Uniquely identifies the tree connect for the
command. This MUST be 0 for the SMB2 TREE_CONNECT Request."

Signed-off-by: Jan-Marek Glogowski 
Reviewed-by: Aurelien Aptel 
Tested-by: Aurelien Aptel 
Signed-off-by: Steve French 
CC: Stable

CIFS: Fix build failure with smb2

2017-04-07T13:04:41+00:00

I saw the following build error during a randconfig build:

fs/cifs/smb2ops.c: In function 'smb2_new_lease_key':
fs/cifs/smb2ops.c:1104:2: error: implicit declaration of function 'generate_random_uuid' [-Werror=implicit-function-declaration]

Explicit include the right header to fix this issue.

Signed-off-by: Tobias Regnery 
Reviewed-by: Aurelien Aptel 
Signed-off-by: Steve French

Introduce cifs_copy_file_range()

2017-04-07T13:04:41+00:00

The earlier changes to copy range for cifs unintentionally disabled the more
common form of server side copy.

The patch introduces the file_operations helper cifs_copy_file_range()
which is used by the syscall copy_file_range. The new file operations
helper allows us to perform server side copies for SMB2.0 and 2.1
servers as well as SMB 3.0+ servers which do not support the ioctl
FSCTL_DUPLICATE_EXTENTS_TO_FILE.

The new helper uses the ioctl FSCTL_SRV_COPYCHUNK_WRITE to perform
server side copies. The helper is called by vfs_copy_file_range() only
once an attempt to clone the file using the ioctl
FSCTL_DUPLICATE_EXTENTS_TO_FILE has failed.

Signed-off-by: Sachin Prabhu 
Reviewed-by: Pavel Shilovsky 
CC: Stable  
Signed-off-by: Steve French