This reverts commit e9f2517a3e.
Commit e9f2517a3e ("smb: client: fix TCP timers deadlock after
rmmod") is intended to fix a null-ptr-deref in LOCKDEP, which is
mentioned as CVE-2024-54680, but is actually did not fix anything;
The issue can be reproduced on top of it. [0]
Also, it reverted the change by commit ef7134c7fc ("smb: client:
Fix use-after-free of network namespace.") and introduced a real
issue by reviving the kernel TCP socket.
When a reconnect happens for a CIFS connection, the socket state
transitions to FIN_WAIT_1. Then, inet_csk_clear_xmit_timers_sync()
in tcp_close() stops all timers for the socket.
If an incoming FIN packet is lost, the socket will stay at FIN_WAIT_1
forever, and such sockets could be leaked up to net.ipv4.tcp_max_orphans.
Usually, FIN can be retransmitted by the peer, but if the peer aborts
the connection, the issue comes into reality.
I warned about this privately by pointing out the exact report [1],
but the bogus fix was finally merged.
So, we should not stop the timers to finally kill the connection on
our side in that case, meaning we must not use a kernel socket for
TCP whose sk->sk_net_refcnt is 0.
The kernel socket does not have a reference to its netns to make it
possible to tear down netns without cleaning up every resource in it.
For example, tunnel devices use a UDP socket internally, but we can
destroy netns without removing such devices and let it complete
during exit. Otherwise, netns would be leaked when the last application
died.
However, this is problematic for TCP sockets because TCP has timers to
close the connection gracefully even after the socket is close()d. The
lifetime of the socket and its netns is different from the lifetime of
the underlying connection.
If the socket user does not maintain the netns lifetime, the timer could
be fired after the socket is close()d and its netns is freed up, resulting
in use-after-free.
Actually, we have seen so many similar issues and converted such sockets
to have a reference to netns.
That's why I converted the CIFS client socket to have a reference to
netns (sk->sk_net_refcnt == 1), which is somehow mentioned as out-of-scope
of CIFS and technically wrong in e9f2517a3e, but **is in-scope and right
fix**.
Regarding the LOCKDEP issue, we can prevent the module unload by
bumping the module refcount when switching the LOCKDDEP key in
sock_lock_init_class_and_name(). [2]
For a while, let's revert the bogus fix.
Note that now we can use sk_net_refcnt_upgrade() for the socket
conversion, but I'll do so later separately to make backport easy.
Link: https://lore.kernel.org/all/20250402020807.28583-1-kuniyu@amazon.com/ #[0]
Link: https://lore.kernel.org/netdev/c08bd5378da647a2a4c16698125d180a@huawei.com/ #[1]
Link: https://lore.kernel.org/lkml/20250402005841.19846-1-kuniyu@amazon.com/ #[2]
Fixes: e9f2517a3e ("smb: client: fix TCP timers deadlock after rmmod")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
This reverts commit 4e7f1644f2.
The commit e9f2517a3e ("smb: client: fix TCP timers deadlock after
rmmod") is not only a bogus fix for LOCKDEP null-ptr-deref but also
introduces a real issue, TCP sockets leak, which will be explained in
detail in the next revert.
Also, CNA assigned CVE-2024-54680 to it but is rejecting it. [0]
Thus, we are reverting the commit and its follow-up commit 4e7f1644f2
("smb: client: Fix netns refcount imbalance causing leaks and
use-after-free").
Link: https://lore.kernel.org/all/2025040248-tummy-smilingly-4240@gregkh/ #[0]
Fixes: 4e7f1644f2 ("smb: client: Fix netns refcount imbalance causing leaks and use-after-free")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
The following Python script results in unexpected behaviour when run on
a CIFS filesystem against a Windows Server:
# Create file
fd = os.open('test', os.O_WRONLY|os.O_CREAT)
os.write(fd, b'foo')
os.close(fd)
# Open and close the file to leave a pending deferred close
fd = os.open('test', os.O_RDONLY|os.O_DIRECT)
os.close(fd)
# Try to open the file via a hard link
os.link('test', 'new')
newfd = os.open('new', os.O_RDONLY|os.O_DIRECT)
The final open returns EINVAL due to the server returning
STATUS_INVALID_PARAMETER. The root cause of this is that the client
caches lease keys per inode, but the spec requires them to be related to
the filename which causes problems when hard links are involved:
From MS-SMB2 section 3.3.5.9.11:
"The server MUST attempt to locate a Lease by performing a lookup in the
LeaseTable.LeaseList using the LeaseKey in the
SMB2_CREATE_REQUEST_LEASE_V2 as the lookup key. If a lease is found,
Lease.FileDeleteOnClose is FALSE, and Lease.Filename does not match the
file name for the incoming request, the request MUST be failed with
STATUS_INVALID_PARAMETER"
On client side, we first check the context of file open, if it hits above
conditions, we first close all opening files which are belong to the same
inode, then we do open the hard link file.
Cc: stable@vger.kernel.org
Signed-off-by: Chunjie Zhu <chunjie.zhu@cloud.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Two new file system attributes were recently added. See MS-FSCC 2.5.1:
FILE_SUPPORTS_POSIX_UNLINK_RENAME and
FILE_RETURNS_CLEANUP_RESULT_INFO
Update the missing defines for ksmbd and cifs.ko
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When reparse point in SMB1 query_path_info() callback was detected then
query also for EA $LXDEV. In this EA are stored device major and minor
numbers used by WSL CHR and BLK reparse points. Without major and minor
numbers, stat() syscall does not work for char and block devices.
Similar code is already in SMB2+ query_path_info() callback function.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Parsing reparse point buffer is generic for all SMB versions and is already
implemented by global function parse_reparse_point().
Getting reparse point buffer from the SMB response is SMB version specific,
so introduce for it a new callback get_reparse_point_buffer.
This functionality split is needed for followup change - getting reparse
point buffer without parsing it.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Like previous changes for file inode.c, handle directory name surrogate
reparse points generally also in reparse.c.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
IO_REPARSE_TAG_MOUNT_POINT is just a specific case of directory Name
Surrogate reparse point. As reparse_info_to_fattr() already handles all
directory Name Surrogate reparse point (done by the previous change),
there is no need to have explicit case for IO_REPARSE_TAG_MOUNT_POINT.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Like in UNICODE mode, SMB1 Session Setup Kerberos Request contains oslm and
domain strings.
Extract common code into ascii_oslm_strings() and ascii_domain_string()
functions (similar to unicode variants) and use these functions in
non-UNICODE code path in sess_auth_kerberos().
Decision if non-UNICODE or UNICODE mode is used is based on the
SMBFLG2_UNICODE flag in Flags2 packed field, and not based on the
capabilities of server. Fix this check too.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
MS-FSCC in section 2.1.2.7 LX SYMLINK REPARSE_DATA_BUFFER now contains
documentation about WSL symlink reparse point buffers.
https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/68337353-9153-4ee1-ac6b-419839c3b7ad
Fix the struct reparse_wsl_symlink_data_buffer to reflect buffer fields
according to the MS-FSCC documentation.
Fix the Linux SMB client to correctly fill the WSL symlink reparse point
buffer when creaing new WSL-style symlink. There was a mistake during
filling the data part of the reparse point buffer. It should starts with
bytes "\x02\x00\x00\x00" (which represents version 2) but this constant was
written as number 0x02000000 encoded in little endian, which resulted bytes
"\x00\x00\x00\x02". This change is fixing this mistake.
Fixes: 4e2043be5c ("cifs: Add support for creating WSL-style symlinks")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When mounting the same share twice, once with the "linux" mount parameter
(or equivalently "posix") and then once without (or e.g. with "nolinux"),
we were incorrectly reusing the same tree connection for both mounts.
This meant that the first mount of the share on the client, would
cause subsequent mounts of that same share on the same client to
ignore that mount parm ("linux" vs. "nolinux") and incorrectly reuse
the same tcon.
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Fix regression in mounts to e.g. onedrive shares.
Generally, reparse points are processed by the SMB server during the
SMB OPEN request, but there are few reparse points which do not have
OPEN-like meaning for the SMB server and has to be processed by the SMB
client. Those are symlinks and special files (fifo, socket, block, char).
For Linux SMB client, it is required to process also name surrogate reparse
points as they represent another entity on the SMB server system. Linux
client will mark them as separate mount points. Examples of name surrogate
reparse points are NTFS junction points (e.g. created by the "mklink" tool
on Windows servers).
So after processing the name surrogate reparse points, clear the
-EOPNOTSUPP error code returned from the parse_reparse_point() to let SMB
server to process reparse points.
And remove printing misleading error message "unhandled reparse tag:" as
reparse points are handled by SMB server and hence unhandled fact is normal
operation.
Fixes: cad3fc0a4c ("cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()")
Fixes: b587fd1286 ("cifs: Treat unhandled directory name surrogate reparse points as mount directory nodes")
Cc: stable@vger.kernel.org
Reported-by: Junwen Sun <sunjw8888@gmail.com>
Tested-by: Junwen Sun <sunjw8888@gmail.com>
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This change allows Linux SMB1 client to autoreconnect the share when it is
modified on server by admin operation which removes and re-adds it.
Implementation is reused from SMB2+ is_network_name_deleted callback. There
are just adjusted checks for error codes and access to struct smb_hdr.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
The calls to cifs_truncate_page() should be superfluous as the places that
call it also call truncate_setsize() or cifs_setsize() and therefore
truncate_pagecache() which should also clear the tail part of the folio
containing the EOF marker.
Further, smb3_simple_falloc() calls both cifs_setsize() and
truncate_setsize() in addition to cifs_truncate_page().
Remove the superfluous calls.
This gets rid of another function referring to struct page.
[Should cifs_setsize() also set inode->i_blocks?]
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <stfrench@microsoft.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
Individual bits GENERIC_READ, GENERIC_EXECUTE and GENERIC_ALL have meaning
which includes also access right for FILE_READ_ATTRIBUTES. So specifying
FILE_READ_ATTRIBUTES bit together with one of those GENERIC (except
GENERIC_WRITE) does not do anything.
This change prevents calling additional (fallback) code and sending more
requests without FILE_READ_ATTRIBUTES when the primary request fails on
-EACCES, as it is not needed at all.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
If SMB2_OP_QUERY_INFO (called when POSIX extensions are not used) failed
with STATUS_ACCESS_DENIED then it means that caller does not have
permission to open the path with FILE_READ_ATTRIBUTES access and therefore
cannot issue SMB2_OP_QUERY_INFO command.
This will result in the -EACCES error from stat() sycall.
There is an alternative way how to query limited information about path but
still suitable for stat() syscall. SMB2 OPEN/CREATE operation returns in
its successful response subset of query information.
So try to open the path without FILE_READ_ATTRIBUTES but with
MAXIMUM_ALLOWED access which will grant the maximum possible access to the
file and the response will contain required query information for stat()
syscall.
This will improve smb2_query_path_info() to query also files which do not
grant FILE_READ_ATTRIBUTES access to caller.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Some operations, like WRITE, does not require FILE_READ_ATTRIBUTES access.
So when FILE_READ_ATTRIBUTES is not explicitly requested for
smb2_open_file() then first try to do SMB2 CREATE with FILE_READ_ATTRIBUTES
access (like it was before) and then fallback to SMB2 CREATE without
FILE_READ_ATTRIBUTES access (less common case).
This change allows to complete WRITE operation to a file when it does not
grant FILE_READ_ATTRIBUTES permission and its parent directory does not
grant READ_DATA permission (parent directory READ_DATA is implicit grant of
child FILE_READ_ATTRIBUTES permission).
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Old SMB1 servers without CAP_NT_SMBS do not support CIFS_open() function
and instead SMBLegacyOpen() needs to be used. This logic is already handled
in cifs_open_file() function, which is server->ops->open callback function.
So for querying and creating MF symlinks use open callback function instead
of CIFS_open() function directly.
This change fixes querying and creating new MF symlinks on Windows 98.
Currently cifs_query_mf_symlink() is not able to detect MF symlink and
cifs_create_mf_symlink() is failing with EIO error.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When converting access_flags to SMBOPEN mode, check for all possible access
flags, not only GENERIC_READ and GENERIC_WRITE flags.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
SMB negotiate retry functionality in cifs_negotiate() is currently broken
and does not work when doing socket reconnect. Caller of this function,
which is cifs_negotiate_protocol() requires that tcpStatus after successful
execution of negotiate callback stay in CifsInNegotiate. But if the
CIFSSMBNegotiate() called from cifs_negotiate() fails due to connection
issues then tcpStatus is changed as so repeated CIFSSMBNegotiate() call
does not help.
Fix this problem by moving retrying code from negotiate callback (which is
either cifs_negotiate() or smb2_negotiate()) to cifs_negotiate_protocol()
which is caller of those callbacks. This allows to properly handle and
implement correct transistions between tcpStatus states as function
cifs_negotiate_protocol() already handles it.
With this change, cifs_negotiate_protocol() now handles also -EAGAIN error
set by the RFC1002_NEGATIVE_SESSION_RESPONSE processing after reconnecting
with NetBIOS session.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Now all NetBIOS session logic is handled in ip_rfc1001_connect() function,
so cleanup is_smb_response() function which contains generic handling of
incoming SMB packets. Note that function is_smb_response() is not used
directly or indirectly (e.g. over cifs_demultiplex_thread() by
ip_rfc1001_connect() function.
Except the Negative Session Response and the Session Keep Alive packet, the
cifs_demultiplex_thread() should not receive any NetBIOS session packets.
And Session Keep Alive packet may be received only when the NetBIOS session
was established by ip_rfc1001_connect() function. So treat any such packet
as error and schedule reconnect.
Negative Session Response packet is returned from Windows SMB server (from
Windows 98 and also from Windows Server 2022) if client sent over port 139
SMB negotiate request without previously establishing a NetBIOS session.
The common scenario is that Negative Session Response packet is returned
for the SMB negotiate packet, which is the first one which SMB client
sends (if it is not establishing a NetBIOS session).
Note that server port 139 may be forwarded and mapped between virtual
machines to different number. And Linux SMB client do not call function
ip_rfc1001_connect() when prot is not 139. So nowadays when using port
mapping or port forwarding between VMs, it is not so uncommon to see this
error.
Currently the logic on Negative Session Response packet changes server port
to 445 and force reconnection. But this logic does not work when using
non-standard port numbers and also does not help if the server on specified
port is requiring establishing a NetBIOS session.
Fix this Negative Session Response logic and instead of changing server
port (on which server does not have to listen), force reconnection with
establishing a NetBIOS session.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Currently SMB client always tries to initialize NetBIOS session when the
server port is 139. This is useful for default cases, but nowadays when
using non-standard routing or testing between VMs, it is common that
servers are listening on non-standard ports.
So add a new mount option -o nbsessinit and -o nonbsessinit which either
forces initialization or disables initialization regardless of server port
number.
This allows Linux SMB client to connect to older SMB1 server listening on
non-standard port, which requires initialization of NetBIOS session, by
using additional mount options -o port= and -o nbsessinit.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Changing owner is controlled by DACL permission WRITE_OWNER. Changing DACL
itself is controlled by DACL permisssion WRITE_DAC. Owner of the file has
implicit WRITE_DAC permission even when it is not explicitly granted for
owner by DACL.
Reading DACL or owner is controlled only by one permission READ_CONTROL.
WRITE_OWNER permission can be bypassed by the SeTakeOwnershipPrivilege,
which is by default available for local administrators.
So if the local administrator wants to access some file to which does not
have access, it is required to first change owner to ourself and then
change DACL permissions.
Currently Linux SMB client does not support this because client does not
provide a way to change owner without touching DACL permissions.
Fix this problem by introducing a new xattr "system.smb3_ntsd_owner" for
setting/changing only owner part of the security descriptor.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Access to SACL part of SMB security descriptor is granted by SACL privilege
which by default is accessible only for local administrator. But it can be
granted to any other user by local GPO or AD. SACL access is not granted by
DACL permissions and therefore is it possible that some user would not have
access to DACLs of some file, but would have access to SACLs of all files.
So it means that for accessing SACLs (either getting or setting) in some
cases requires not touching or asking for DACLs.
Currently Linux SMB client does not allow to get or set SACLs without
touching DACLs. Which means that user without DACL access is not able to
get or set SACLs even if it has access to SACLs.
Fix this problem by introducing a new xattr "system.smb3_ntsd_sacl" for
accessing only SACLs part of the security descriptor (therefore without
DACLs and OWNER/GROUP).
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
When a SMB connection is reset and reconnected, the negotiated IO
parameters (rsize/wsize) can become out of sync with the server's
current capabilities. This can lead to suboptimal performance or
even IO failures if the server's limits have changed.
This patch implements automatic IO size renegotiation:
1. Adds cifs_renegotiate_iosize() function to update all superblocks
associated with a tree connection
2. Updates each mount's rsize/wsize based on current server capabilities
3. Calls this function after successful tree connection reconnection
With this change, all mount points will automatically maintain optimal
and reliable IO parameters after network disruptions, using the
bidirectional mapping added in previous patches.
This completes the series improving connection resilience by keeping
mount parameters synchronized with server capabilities.
Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
During mount option processing and negotiation with the server, the
original user-specified rsize/wsize values were being modified directly.
This makes it impossible to recover these values after a connection
reset, leading to potential degraded performance after reconnection.
The other problem is that When negotiating read and write sizes, there are
cases where the negotiated values might calculate to zero, especially
during reconnection when server->max_read or server->max_write might be
reset. In general, these values come from the negotiation response.
According to MS-SMB2 specification, these values should be at least 65536
bytes.
This patch improves IO parameter handling:
1. Adds vol_rsize and vol_wsize fields to store the original user-specified
values separately from the negotiated values
2. Uses got_rsize/got_wsize flags to determine if values were
user-specified rather than checking for non-zero values, which is more
reliable
3. Adds a prevent_zero_iosize() helper function to ensure IO sizes are
never negotiated down to zero, which could happen in edge cases like
when server->max_read/write is zero
The changes make the CIFS client more resilient to unusual server
responses and reconnection scenarios, preventing potential failures
when IO sizes are calculated to be zero.
Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Currently, when a SMB connection is reset and renegotiated with the
server, there's no way to update all related mount points with new
negotiated sizes. This is because while superblocks (cifs_sb_info)
maintain references to tree connections (tcon) through tcon_link
structures, there is no reverse mapping from a tcon back to all the
superblocks using it.
This patch adds a bidirectional relationship between tcon and
cifs_sb_info structures by:
1. Adding a cifs_sb_list to tcon structure with appropriate locking
2. Adding tcon_sb_link to cifs_sb_info to join the list
3. Managing the list entries during mount and umount operations
The bidirectional relationship enables future functionality to locate and
update all superblocks connected to a specific tree connection, such as:
- Updating negotiated parameters after reconnection
- Efficiently notifying all affected mounts of capability changes
This is the first part of a series to improve connection resilience
by keeping all mount parameters in sync with server capabilities
after reconnection.
Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
echo_interval is checked at mount time, the code has become
unreachable.
Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
The echo_interval is not limited in any way during mounting,
which makes it possible to write a large number to it. This can
cause an overflow when multiplying ctx->echo_interval by HZ in
match_server().
Add constraints for echo_interval to smb3_fs_context_parse_param().
Found by Linux Verification Center (linuxtesting.org) with Svace.
Fixes: adfeb3e00e ("cifs: Make echo interval tunable")
Cc: stable@vger.kernel.org
Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
Pull smb client updates from Steve French:
- Fix for network namespace refcount leak
- Multichannel fix and minor multichannel debug message cleanup
- Fix potential null ptr reference in SMB3 close
- Fix for special file handling when reparse points not supported by
server
- Two ACL fixes one for stricter ACE validation, one for incorrect
perms requested
- Three RFC1001 fixes: one for SMB3 mounts on port 139, one for better
default hostname, and one for better session response processing
- Minor update to email address for MAINTAINERS file
- Allow disabling Unicode for access to old SMB1 servers
- Three minor cleanups
* tag '6.15-rc-part1-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Add new mount option -o nounicode to disable SMB1 UNICODE mode
cifs: Set default Netbios RFC1001 server name to hostname in UNC
smb: client: Fix netns refcount imbalance causing leaks and use-after-free
cifs: add validation check for the fields in smb_aces
CIFS: Propagate min offload along with other parameters from primary to secondary channels.
cifs: Improve establishing SMB connection with NetBIOS session
cifs: Fix establishing NetBIOS session for SMB2+ connection
cifs: Fix getting DACL-only xattr system.cifs_acl and system.smb3_acl
cifs: Check if server supports reparse points before using them
MAINTAINERS: reorder preferred email for Steve French
cifs: avoid NULL pointer dereference in dbg call
smb: client: Remove redundant check in smb2_is_path_accessible()
smb: client: Remove redundant check in cifs_oplock_break()
smb: mark the new channel addition log as informational log with cifs_info
smb: minor cleanup to remove unused function declaration
SMB1 protocol supports non-UNICODE (8-bit OEM character set) and
UNICODE (UTF-16) modes.
Linux SMB1 client implements both of them but currently does not allow to
choose non-UNICODE mode when SMB1 server announce UNICODE mode support.
This change adds a new mount option -o nounicode to disable UNICODE mode
and force usage of non-UNICODE (8-bit OEM character set) mode.
This allows to test non-UNICODE implementation of Linux SMB1 client against
any SMB1 server, including modern and recent Windows SMB1 server.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Windows SMB servers (including SMB2+) which are working over RFC1001
require that Netbios server name specified in RFC1001 Session Request
packet is same as the UNC host name. Netbios server name can be already
specified manually via -o servern= option.
With this change the RFC1001 server name is set automatically by extracting
the hostname from the mount source.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Commit ef7134c7fc ("smb: client: Fix use-after-free of network
namespace.") attempted to fix a netns use-after-free issue by manually
adjusting reference counts via sk->sk_net_refcnt and sock_inuse_add().
However, a later commit e9f2517a3e ("smb: client: fix TCP timers deadlock
after rmmod") pointed out that the approach of manually setting
sk->sk_net_refcnt in the first commit was technically incorrect, as
sk->sk_net_refcnt should only be set for user sockets. It led to issues
like TCP timers not being cleared properly on close. The second commit
moved to a model of just holding an extra netns reference for
server->ssocket using get_net(), and dropping it when the server is torn
down.
But there remain some gaps in the get_net()/put_net() balancing added by
these commits. The incomplete reference handling in these fixes results
in two issues:
1. Netns refcount leaks[1]
The problem process is as follows:
```
mount.cifs cifsd
cifs_do_mount
cifs_mount
cifs_mount_get_session
cifs_get_tcp_session
get_net() /* First get net. */
ip_connect
generic_ip_connect /* Try port 445 */
get_net()
->connect() /* Failed */
put_net()
generic_ip_connect /* Try port 139 */
get_net() /* Missing matching put_net() for this get_net().*/
cifs_get_smb_ses
cifs_negotiate_protocol
smb2_negotiate
SMB2_negotiate
cifs_send_recv
wait_for_response
cifs_demultiplex_thread
cifs_read_from_socket
cifs_readv_from_socket
cifs_reconnect
cifs_abort_connection
sock_release();
server->ssocket = NULL;
/* Missing put_net() here. */
generic_ip_connect
get_net()
->connect() /* Failed */
put_net()
sock_release();
server->ssocket = NULL;
free_rsp_buf
...
clean_demultiplex_info
/* It's only called once here. */
put_net()
```
When cifs_reconnect() is triggered, the server->ssocket is released
without a corresponding put_net() for the reference acquired in
generic_ip_connect() before. it ends up calling generic_ip_connect()
again to retry get_net(). After that, server->ssocket is set to NULL
in the error path of generic_ip_connect(), and the net count cannot be
released in the final clean_demultiplex_info() function.
2. Potential use-after-free
The current refcounting scheme can lead to a potential use-after-free issue
in the following scenario:
```
cifs_do_mount
cifs_mount
cifs_mount_get_session
cifs_get_tcp_session
get_net() /* First get net */
ip_connect
generic_ip_connect
get_net()
bind_socket
kernel_bind /* failed */
put_net()
/* after out_err_crypto_release label */
put_net()
/* after out_err label */
put_net()
```
In the exception handling process where binding the socket fails, the
get_net() and put_net() calls are unbalanced, which may cause the
server->net reference count to drop to zero and be prematurely released.
To address both issues, this patch ties the netns reference counting to
the server->ssocket and server lifecycles. The extra reference is now
acquired when the server or socket is created, and released when the
socket is destroyed or the server is torn down.
[1]: https://bugzilla.kernel.org/show_bug.cgi?id=219792
Fixes: ef7134c7fc ("smb: client: Fix use-after-free of network namespace.")
Fixes: e9f2517a3e ("smb: client: fix TCP timers deadlock after rmmod")
Signed-off-by: Wang Zhaolong <wangzhaolong1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
cifs.ko is missing validation check when accessing smb_aces.
This patch add validation check for the fields in smb_aces.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
In a multichannel setup, it was observed that a few fields were not being
copied over to the secondary channels, which impacted performance in cases
where these options were relevant but not properly synchronized. To address
this, this patch introduces copying the following parameters from the
primary channel to the secondary channels:
- min_offload
- compression.requested
- dfs_conn
- ignore_signature
- leaf_fullpath
- noblockcnt
- retrans
- sign
By copying these parameters, we ensure consistency across channels and
prevent performance degradation due to missing or outdated settings.
Cc: stable@vger.kernel.org
Signed-off-by: Aman <aman1@microsoft.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Function ip_rfc1001_connect() send NetBIOS session request but currently
does not read response. It even does not wait for the response. Instead it
just calls usleep_range(1000, 2000) and explain in comment that some
servers require short break before sending SMB negotiate packet. Response
is later handled in generic is_smb_response() function called from
cifs_demultiplex_thread().
That comment probably refers to the old DOS SMB server which cannot process
incoming SMB negotiate packet if it has not sent NetBIOS session response
packet. Note that current sleep timeout is too small when trying to
establish connection to DOS SMB server running in qemu virtual machine
connected over qemu user networking with guestfwd netcat options. So that
usleep_range() call is not useful at all.
NetBIOS session response packet contains useful error information, like
the server name specified NetBIOS session request packet is incorrect.
Old Windows SMB servers and even the latest SMB server on the latest
Windows Server 2022 version requires that the name is the correct server
name, otherwise they return error RFC1002_NOT_PRESENT. This applies for all
SMB dialects (old SMB1, and also modern SMB2 and SMB3).
Therefore read the reply of NetBIOS session request and implement parsing
of the reply. Log received error to dmesg to help debugging reason why
connection was refused. Also convert NetBIOS error to useful errno.
Note that ip_rfc1001_connect() function is used only when doing connection
over port 139. So the common SMB scenario over port 445 is not affected by
this change at all.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Function ip_rfc1001_connect() which establish NetBIOS session for SMB
connections, currently uses smb_send() function for sending NetBIOS Session
Request packet. This function expects that the passed buffer is SMB packet
and for SMB2+ connections it mangles packet header, which breaks prepared
NetBIOS Session Request packet. Result is that this function send garbage
packet for SMB2+ connection, which SMB2+ server cannot parse. That function
is not mangling packets for SMB1 connections, so it somehow works for SMB1.
Fix this problem and instead of smb_send(), use smb_send_kvec() function
which does not mangle prepared packet, this function send them as is. Just
API of this function takes struct msghdr (kvec) instead of packet buffer.
[MS-SMB2] specification allows SMB2 protocol to use NetBIOS as a transport
protocol. NetBIOS can be used over TCP via port 139. So this is a valid
configuration, just not so common. And even recent Windows versions (e.g.
Windows Server 2022) still supports this configuration: SMB over TCP port
139, including for modern SMB2 and SMB3 dialects.
This change fixes SMB2 and SMB3 connections over TCP port 139 which
requires establishing of NetBIOS session. Tested that this change fixes
establishing of SMB2 and SMB3 connections with Windows Server 2022.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Currently ->get_acl() callback always create request for OWNER, GROUP and
DACL, even when only DACLs was requested by user. Change API callback to
request only information for which the caller asked. Therefore when only
DACLs requested, then SMB client will prepare and send DACL-only request.
This change fixes retrieving of "system.cifs_acl" and "system.smb3_acl"
xattrs to contain only DACL structure as documented.
Note that setting/changing of "system.cifs_acl" and "system.smb3_acl"
xattrs already takes only DACL structure and ignores all other fields.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Do not attempt to query or create reparse point when server fs does not
support it. This will prevent creating unusable empty object on the server.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Pull vfs async dir updates from Christian Brauner:
"This contains cleanups that fell out of the work from async directory
handling:
- Change kern_path_locked() and user_path_locked_at() to never return
a negative dentry. This simplifies the usability of these helpers
in various places
- Drop d_exact_alias() from the remaining place in NFS where it is
still used. This also allows us to drop the d_exact_alias() helper
completely
- Drop an unnecessary call to fh_update() from nfsd_create_locked()
- Change i_op->mkdir() to return a struct dentry
Change vfs_mkdir() to return a dentry provided by the filesystems
which is hashed and positive. This allows us to reduce the number
of cases where the resulting dentry is not positive to very few
cases. The code in these places becomes simpler and easier to
understand.
- Repack DENTRY_* and LOOKUP_* flags"
* tag 'vfs-6.15-rc1.async.dir' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
doc: fix inline emphasis warning
VFS: Change vfs_mkdir() to return the dentry.
nfs: change mkdir inode_operation to return alternate dentry if needed.
fuse: return correct dentry for ->mkdir
ceph: return the correct dentry on mkdir
hostfs: store inode in dentry after mkdir if possible.
Change inode_operations.mkdir to return struct dentry *
nfsd: drop fh_update() from S_IFDIR branch of nfsd_create_locked()
nfs/vfs: discard d_exact_alias()
VFS: add common error checks to lookup_one_qstr_excl()
VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry
VFS: repack LOOKUP_ bit flags.
VFS: repack DENTRY_ flags.
Pull misc vfs updates from Christian Brauner:
"Features:
- Add CONFIG_DEBUG_VFS infrastucture:
- Catch invalid modes in open
- Use the new debug macros in inode_set_cached_link()
- Use debug-only asserts around fd allocation and install
- Place f_ref to 3rd cache line in struct file to resolve false
sharing
Cleanups:
- Start using anon_inode_getfile_fmode() helper in various places
- Don't take f_lock during SEEK_CUR if exclusion is guaranteed by
f_pos_lock
- Add unlikely() to kcmp()
- Remove legacy ->remount_fs method from ecryptfs after port to the
new mount api
- Remove invalidate_inodes() in favour of evict_inodes()
- Simplify ep_busy_loopER by removing unused argument
- Avoid mmap sem relocks when coredumping with many missing pages
- Inline getname()
- Inline new_inode_pseudo() and de-staticize alloc_inode()
- Dodge an atomic in putname if ref == 1
- Consistently deref the files table with rcu_dereference_raw()
- Dedup handling of struct filename init and refcounts bumps
- Use wq_has_sleeper() in end_dir_add()
- Drop the lock trip around I_NEW wake up in evict()
- Load the ->i_sb pointer once in inode_sb_list_{add,del}
- Predict not reaching the limit in alloc_empty_file()
- Tidy up do_sys_openat2() with likely/unlikely
- Call inode_sb_list_add() outside of inode hash lock
- Sort out fd allocation vs dup2 race commentary
- Turn page_offset() into a wrapper around folio_pos()
- Remove locking in exportfs around ->get_parent() call
- try_lookup_one_len() does not need any locks in autofs
- Fix return type of several functions from long to int in open
- Fix return type of several functions from long to int in ioctls
Fixes:
- Fix watch queue accounting mismatch"
* tag 'vfs-6.15-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
fs: sort out fd allocation vs dup2 race commentary, take 2
fs: call inode_sb_list_add() outside of inode hash lock
fs: tidy up do_sys_openat2() with likely/unlikely
fs: predict not reaching the limit in alloc_empty_file()
fs: load the ->i_sb pointer once in inode_sb_list_{add,del}
fs: drop the lock trip around I_NEW wake up in evict()
fs: use wq_has_sleeper() in end_dir_add()
VFS/autofs: try_lookup_one_len() does not need any locks
fs: dedup handling of struct filename init and refcounts bumps
fs: consistently deref the files table with rcu_dereference_raw()
exportfs: remove locking around ->get_parent() call.
fs: use debug-only asserts around fd allocation and install
fs: dodge an atomic in putname if ref == 1
vfs: Remove invalidate_inodes()
ecryptfs: remove NULL remount_fs from super_operations
watch_queue: fix pipe accounting mismatch
fs: place f_ref to 3rd cache line in struct file to resolve false sharing
epoll: simplify ep_busy_loop by removing always 0 argument
fs: Turn page_offset() into a wrapper around folio_pos()
kcmp: improve performance adding an unlikely hint to task comparisons
...
cifs_server_dbg() implies server to be non-NULL so
move call under condition to avoid NULL pointer dereference.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: e79b0332ae ("cifs: ignore cached share root handle closing errors")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
There is an unnecessary NULL check of cifs_sb in smb2_is_path_accessible(),
since cifs_sb is dereferenced multiple times prior to it.
It seems that there is no need to introduce any NULL checks of cifs_sb,
since arguments of smb2_is_path_accessible() are assumed to be non-NULL.
Therefore, this redundant check can be removed.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Ivan Abramov <i.abramov@mt-integration.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
There is an unnecessary NULL check of inode in cifs_oplock_break(), since
there are multiple dereferences of cinode prior to it.
Based on usage of cifs_oplock_break() in cifs_new_fileinfo() we can safely
assume that inode is not NULL, so there is no need to check inode in
cifs_oplock_break() at all.
Therefore, this redundant check can be removed.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
Signed-off-by: Ivan Abramov <i.abramov@mt-integration.ru>
Signed-off-by: Steve French <stfrench@microsoft.com>
For multichannel mounts, when a new channel is successfully opened
we currently log 'successfully opened new channel on iface: <>' as
cifs_dbg(VFS..) which is eventually translated into a pr_err log.
Marking these informational logs as error logs may lead to confusion
for users so they will now be logged as info logs instead.
Signed-off-by: Bharath SM <bharathsm@microsoft.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
If @server->tcpStatus is set to CifsNeedReconnect after acquiring
@ses->session_mutex in smb2_reconnect() or cifs_reconnect_tcon(), it
means that a concurrent thread failed to negotiate, in which case the
server is no longer responding to any SMB requests, so there is no
point making the caller retry the IO by returning -EAGAIN.
Fix this by returning -EHOSTDOWN to the callers on soft mounts.
Cc: David Howells <dhowells@redhat.com>
Reported-by: Jay Shin <jaeshin@redhat.com>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
