__ksmbd_tree_conn_disconnect() drops the share_conf reference before
checking tree_conn->refcount. When someone uses SMB3 multichannel and
binds two connections to one session, a SESSION_LOGOFF on connection A
calls ksmbd_conn_wait_idle(conn) which only drains connection A's
request counter, not connection B's. This means there's a race condition:
requests already dispatched on connection B hold tree_conn references via
work->tcon. The disconnect path frees share_conf while those requests
are still walking work->tcon->share_conf, causing a use-after-free.
This fix combines the share_conf put with the tree_conn free so it
only happens when the last reference is dropped.
Fixes: b39a1833cc ("ksmbd: fix use-after-free in ksmbd_tree_connect_put under concurrency")
Signed-off-by: Nicholas Carlini <nicholas@carlini.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
Converts tree_conns_lock to an rw_semaphore to allow sleeping while
the lock is held. Additionally, it simplifies the locking logic in
ksmbd_tree_conn_session_logoff() and introduces
__ksmbd_tree_conn_disconnect() to avoid redundant locking.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This patch introduces a /proc filesystem interface to ksmbd, providing
visibility into the internal state of the SMB server. This allows
administrators and developers to monitor active connections, user
sessions, and opened files in real-time without relying on external
tools or heavy debugging.
Key changes include:
- Connection Monitoring (/proc/fs/ksmbd/clients): Displays a list of
active network connections, including client IP addresses, SMB dialects,
credits, and last active timestamps.
- Session Management (/proc/fs/ksmbd/sessions/): Adds a global sessions
file to list all authenticated users and their session IDs.
- Creates individual session entries (e.g., /proc/fs/ksmbd/sessions/<id>)
detailing capabilities (DFS, Multi-channel, etc.), signing/encryption
algorithms, and connected tree shares.
- File Tracking (/proc/fs/ksmbd/files): Shows all currently opened files
across the server, including tree IDs, process IDs (PID), access modes
(daccess/saccess), and oplock/lease states.
- Statistics & Counters: Implements internal counters for global server
metrics, such as the number of tree connections, total sessions, and
processed read/write bytes.
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: Bahubali B Gumaji <bahubali.bg@samsung.com>
Signed-off-by: Sang-Soo Lee <constant.lee@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Under high concurrency, A tree-connection object (tcon) is freed on
a disconnect path while another path still holds a reference and later
executes *_put()/write on it.
Reported-by: Qianchang Zhao <pioooooooooip@gmail.com>
Reported-by: Zhitong Liu <liuzhitong1993@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Prefer to report ENOMEM rather than incur the oom for allocations in
ksmbd. __GFP_NORETRY could not achieve that, It would fail the allocations
just too easily. __GFP_RETRY_MAYFAIL will keep retrying the allocation
until there is no more progress and fail the allocation instead go OOM
and let the caller to deal with it.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Sangsoo reported that a DAC denial error occurred when accessing
files through the ksmbd thread. This patch override fsids for share
path check.
Reported-by: Sangsoo Lee <constant.lee@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
if thread A in smb2_write is using work-tcon, other thread B use
smb2_tree_disconnect free the tcon, then thread A will use free'd tcon.
Time
+
Thread A | Thread A
smb2_write | smb2_tree_disconnect
|
|
| kfree(tree_conn)
|
// UAF! |
work->tcon->share_conf |
+
This patch add state, reference count and lock for tree conn to fix race
condition issue.
Reported-by: luosili <rootlab@huawei.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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>
