kernel/linux.git/fs/smb/server/vfs_cache.h, branch linux-7.1.y

ksmbd: harden file lifetime during session teardown

2026-05-02T02:49:35+00:00

__close_file_table_ids() is the per-session teardown that closes every fp belonging to a session (or to one tree connect on that session) by walking the session's volatile-id idr. The current loop has three related problems on busy or racing workloads: * Sleeping under ft->lock. The session-teardown skip callback, session_fd_check(), already sleeps in ksmbd_vfs_copy_durable_owner() -> kstrdup(GFP_KERNEL) and down_write(&fp->f_ci->m_lock) (a rw_semaphore). Running the callback inside write_lock(&ft->lock) trips CONFIG_DEBUG_ATOMIC_SLEEP / CONFIG_PROVE_LOCKING on a durable-fd workload. * Refcount accounting blind to f_state. The unconditional atomic_dec_and_test(&fp->refcount) does not distinguish FP_INITED (idr-owned reference still intact) from FP_CLOSED (an earlier ksmbd_close_fd() already consumed the idr-owned reference while leaving fp in the idr because a holder kept refcount non-zero). When the latter races with teardown the same path over-decrements into a holder reference and ksmbd_fd_put() later UAFs that holder. * FP_NEW window. Between __open_id() publishing fp into the session idr and ksmbd_update_fstate(..., FP_INITED) committing the transition at the end of smb2_open(), an fp is in FP_NEW and an intervening teardown that takes a transient reference and unpublishes the volatile id leaves the original idr-owned reference orphaned -- the opener is unaware that fp has been unpublished, returns success to the client, and the fp leaks at refcount = 1. Refactor __close_file_table_ids() to take a transient reference on fp and unpublish fp from the session idr *under ft->lock* before calling skip() outside the lock. A transient ref protects lifetime but not concurrent field mutation, so the idr_remove() is what keeps __ksmbd_lookup_fd() through this session's idr from granting a new ksmbd_fp_get() reference to an fp whose fp->conn / fp->tcon / fp->volatile_id / op->conn / lock_list links are about to be rewritten by session_fd_check(). Durable reconnect is unaffected because it reaches fp through the global durable table (ksmbd_lookup_durable_fd -> global_ft). Decide n_to_drop together with any FP_INITED -> FP_CLOSED transition under ft->lock so teardown and ksmbd_close_fd() never both consume the idr-owned reference. See ksmbd_mark_fp_closed() for the per-state accounting. For the FP_NEW path to be safe, the opener has to learn that fp was unpublished: ksmbd_update_fstate() now returns -ENOENT when an FP_NEW -> FP_INITED transition finds f_state already advanced or the volatile id cleared (both committed by teardown under ft->lock); smb2_open() propagates that as STATUS_OBJECT_NAME_INVALID and drops the original reference via ksmbd_fd_put(). The list removal cannot be left for a deferred final putter because fp->volatile_id has already been cleared and __ksmbd_remove_fd() will intentionally skip both idr_remove() and list_del_init(). Move the m_fp_list unlink in __ksmbd_remove_fd() above the volatile-id check so that an FP_NEW fp that happened to be added to m_fp_list (smb2_open() adds fp->node before ksmbd_update_fstate() runs) is still cleaned up on the deferred putter path; list_del_init() on an empty node is a no-op and remains safe for fps that were never added. Add a defensive guard in session_fd_check() that refuses non-FP_INITED fps so that even if a teardown reaches an FP_NEW fp it falls into the close branch (where the n_to_drop = 1 accounting keeps the opener's reference alive) instead of the durable-preserve branch (which mutates fp->conn / fp->tcon). Validation on a debug kernel additionally built with CONFIG_DEBUG_LIST and CONFIG_DEBUG_OBJECTS_WORK used a same-session two-tcon workload (open/write storm on one tcon, 50 tree disconnects on the other) and reported no list-corruption, work_struct ODEBUG, sleep-in-atomic, lockdep or kmemleak reports. Reverting only the __close_file_table_ids() hunk while keeping a forced-is_reconnectable() harness produced the expected sleep-in-atomic at vfs_cache.c:1095, confirming the ft->lock-out-of-sleepable-skip discipline. KASAN-enabled direct SMB2 coverage with durable handles enabled exercised ksmbd_close_tree_conn_fds(), ksmbd_close_session_fds(), the FP_NEW failure path, tree_conn_fd_check(), and a non-zero session_fd_check() durable-preserve return. This produced no KASAN, DEBUG_LIST, ODEBUG, or WARNING reports. Fixes: f44158485826 ("cifsd: add file operations") Signed-off-by: DaeMyung Kang Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: validate owner of durable handle on reconnect

2026-04-12T23:07:54+00:00

Currently, ksmbd does not verify if the user attempting to reconnect to a durable handle is the same user who originally opened the file. This allows any authenticated user to hijack an orphaned durable handle by predicting or brute-forcing the persistent ID. According to MS-SMB2, the server MUST verify that the SecurityContext of the reconnect request matches the SecurityContext associated with the existing open. Add a durable_owner structure to ksmbd_file to store the original opener's UID, GID, and account name. and catpure the owner information when a file handle becomes orphaned. and implementing ksmbd_vfs_compare_durable_owner() to validate the identity of the requester during SMB2_CREATE (DHnC). Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Reported-by: Davide Ornaghi Reported-by: Navaneeth K Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: allow a filename to contain colons on SMB3.1.1 posix extensions

2025-08-31T22:48:38+00:00

If the client sends SMB2_CREATE_POSIX_CONTEXT to ksmbd, allow the filename to contain a colon (':'). This requires disabling the support for Alternate Data Streams (ADS), which are denoted by a colon-separated suffix to the filename on Windows. This should not be an issue, since this concept is not known to POSIX anyway and the client has to explicitly request a POSIX context to get this behavior. Link: https://lore.kernel.org/all/f9401718e2be2ab22058b45a6817db912784ef61.camel@rx2.rx-server.de/ Signed-off-by: Philipp Kerling Acked-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: handle set/get info file for streamed file

2025-06-17T21:27:16+00:00

The bug only appears when: - windows 11 copies a file that has an alternate data stream - streams_xattr is enabled on the share configuration. Microsoft Edge adds a ZoneIdentifier data stream containing the URL for files it downloads. Another way to create a test file: - open cmd.exe - echo "hello from default data stream" > hello.txt - echo "hello again from ads" > hello.txt:ads.txt If you open the file using notepad, we'll see the first message. If you run "notepad hello.txt:ads.txt" in cmd.exe, we should see the second message. dir /s /r should least all streams for the file. The truncation happens because the windows 11 client sends a SetInfo/EndOfFile message on the ADS, but it is instead applied on the main file, because we don't check fp->stream. When receiving set/get info file for a stream file, Change to process requests using stream position and size. Truncate is unnecessary for stream files, so we skip set_file_allocation_info and set_end_of_file_info operations. Reported-by: Marios Makassikis Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: fix warning: comparison of distinct pointer types lacks a cast

2024-09-21T03:16:11+00:00

smb2pdu.c: In function ‘smb2_open’: ./include/linux/minmax.h:20:28: warning: comparison of distinct pointer types lacks a cast 20 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^~ ./include/linux/minmax.h:26:4: note: in expansion of macro ‘__typecheck’ 26 | (__typecheck(x, y) && __no_side_effects(x, y)) | ^~~~~~~~~~~ ./include/linux/minmax.h:36:24: note: in expansion of macro ‘__safe_cmp’ 36 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ ./include/linux/minmax.h:45:19: note: in expansion of macro ‘__careful_cmp’ 45 | #define min(x, y) __careful_cmp(x, y, <) | ^~~~~~~~~~~~~ /home/linkinjeon/git/smbd_work/ksmbd/smb2pdu.c:3713:27: note: in expansion of macro ‘min’ 3713 | fp->durable_timeout = min(dh_info.timeout, Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: add durable scavenger timer

2024-07-15T02:45:40+00:00

Launch ksmbd-durable-scavenger kernel thread to scan durable fps that have not been reclaimed by a client within the configured time. Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: avoid reclaiming expired durable opens by the client

2024-07-14T23:00:35+00:00

The expired durable opens should not be reclaimed by client. This patch add ->durable_scavenger_timeout to fp and check it in ksmbd_lookup_durable_fd(). Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: use rwsem instead of rwlock for lease break

2024-05-05T04:53:36+00:00

lease break wait for lease break acknowledgment. rwsem is more suitable than unlock while traversing the list for parent lease break in ->m_op_list. Cc: stable@vger.kernel.org Signed-off-by: Namjae Jeon Signed-off-by: Steve French

ksmbd: add support for durable handles v1/v2

2024-03-12T05:36:39+00:00

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 Signed-off-by: Steve French

ksmbd: lazy v2 lease break on smb2_write()

2023-12-08T16:11:33+00:00

Don't immediately send directory lease break notification on smb2_write(). Instead, It postpones it until smb2_close(). Signed-off-by: Namjae Jeon Signed-off-by: Steve French