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A deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on
conn->async_requests via setup_async_work(), with cancel_fn =
smb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock.
When the request is cancelled, the worker frees the file_lock with
locks_free_lock() and takes the cancelled early-exit, which "goto out"s and never
reaches release_async_work() -- the only site that unlinks the work from
conn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays
matchable on async_requests with a live cancel_fn pointing at the freed file_lock,
until connection teardown finally runs release_async_work().
smb2_cancel() fires cancel_fn unconditionally with no state guard, so a second
SMB2_CANCEL for the same AsyncId, arriving in that window, re-runs
smb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free:
BUG: KASAN: slab-use-after-free in __locks_delete_block
__locks_delete_block
locks_delete_block
ksmbd_vfs_posix_lock_unblock
smb2_remove_blocked_lock
smb2_cancel <- 2nd SMB2_CANCEL fires cancel_fn
handle_ksmbd_work
Allocated by ...: locks_alloc_lock <- smb2_lock
Freed by ...: locks_free_lock <- smb2_lock (cancelled branch)
... cache file_lock_cache of size 192
Reproduced on mainline with KASAN by an authenticated SMB client.
Skip a work whose state is already KSMBD_WORK_CANCELLED so its cancel callback
cannot be fired a second time.
Cc: stable@vger.kernel.org
Signed-off-by: Gil Portnoy <dddhkts1@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Two concurrent same-user DHnC reconnects can both observe fp->conn == NULL
before either sets it. ksmbd_reopen_durable_fd() checks fp->conn to guard
against a handle already being reconnected, but the check and the binding
assignment are not atomic: both threads pass the guard, both call
ksmbd_conn_get() on the same fp, and both eventually reach
kfree(fp->owner.name) -- a double-free of the owner.name slab object.
The double-bound ksmbd_file also causes a write-UAF on the 344-byte
ksmbd_file_cache object when a concurrent smb2_close() spins on fp->f_lock
after the object has been freed by the losing reconnect path.
KASAN on 7.1-rc5 (48-thread concurrent reconnect, 3000 cycles):
BUG: KASAN: double-free in ksmbd_reopen_durable_fd+0x268/0x308
BUG: KASAN: slab-use-after-free in _raw_spin_lock+0xac/0x150
Write of size 4 at offset 24 into freed ksmbd_file_cache object
Five double-bind windows observed; 63 total KASAN reports triggered.
Fix: validate and claim fp->conn under write_lock(&global_ft.lock) so the
check-and-claim is atomic. ksmbd_lookup_durable_fd() already treats
fp->conn != NULL as "in use" and skips such an fp; setting fp->conn before
dropping the lock closes the race. ksmbd_conn_get() is a non-sleeping
refcount increment, safe under the rwlock. The rollback path on __open_id()
failure also clears fp->conn/tcon under the lock so concurrent readers see
a consistent state.
Fixes: b1f1e80620de ("ksmbd: centralize ksmbd_conn final release to plug transport leak")
Assisted-by: Henry (Claude):claude-opus-4
Signed-off-by: Gil Portnoy <dddhkts1@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn
into a local with neither READ_ONCE() nor a NULL check. Both run from
oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a
concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL
under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then
writes through NULL at offset 0xc4 -- a remotely triggerable oops.
Guard both reads the way compare_guid_key() already does: read
opinfo->conn with READ_ONCE() and return early if it is NULL, before
allocating the work struct so nothing leaks. A NULL conn means the
client is gone and the break is moot, so return 0; oplock_break() treats
that as success and runs the normal teardown.
Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2")
Assisted-by: Henry (Claude):claude-opus-4
Signed-off-by: Gil Portnoy <dddhkts1@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Pull smb client fixes from Steve French:
- fix uninitialized variable in smb2_writev_callback()
- detect short folioq copy in cifs_copy_folioq_to_iter()
* tag 'v7.1-rc6-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
smb: client: fix uninitialized variable in smb2_writev_callback
smb: client: detect short folioq copy in cifs_copy_folioq_to_iter()
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compiling with W=2 pointed out that "written may be used uninitialized"
Fixes: 20d72b00ca81 ("netfs: Fix the request's work item to not require a ref")
Cc: stable@vger.kernel.org
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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cifs_copy_folioq_to_iter() copies a requested number of bytes from
a folio queue into the destination iterator. Since the encrypted
SMB2 READ path was changed to pass the server-declared payload
length (data_len) instead of the larger folioq buffer length, the
caller can ask for fewer bytes than the folio queue holds.
In that case the helper continues walking the remaining folios after
data_size has reached zero and calls copy_folio_to_iter() with
len = 0, which is unnecessary work.
The helper also returns 0 (success) when the folio queue is
exhausted before data_size bytes have been copied. The caller has
no way to distinguish that from a full copy and the reported
transfer count ends up larger than the amount of data placed in the
iterator.
Add an early exit when data_size reaches zero, and return an error
when the folio queue is exhausted before all requested bytes have
been copied.
Signed-off-by: Jeremy Erazo <mendozayt13@gmail.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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FSCTL_SET_SPARSE
FSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file's sparse
attribute and saves it through xattr without any permission checks.
This exposes two issues:
1) A client on a read-only share can change the sparse attribute
on files it opened, even though the share is read-only.
Other FSCTL write operations already check
test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE),
but FSCTL_SET_SPARSE does not.
2) Even on writable shares, clients without FILE_WRITE_DATA or
FILE_WRITE_ATTRIBUTES access should not modify the sparse
attribute. Similar handle-level checks exist in other functions
but are missing here.
Add both share-level writable check and per-handle access check.
Use goto out on error to avoid leaking file references.
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steve French <smfrench@gmail.com>
Signed-off-by: Sean Shen <grayhat@foxmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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ksmbd_query_inode_status() and ksmbd_lookup_fd_inode() both take a
reference on a ksmbd_inode via __ksmbd_inode_lookup() (which performs
atomic_inc_not_zero()) and later release it using a bare
atomic_dec(&ci->m_count). Unlike ksmbd_inode_put(), a bare
atomic_dec() does not check whether the reference count has reached
zero, so if the caller happens to drop the last reference, the
ksmbd_inode is leaked: it stays in the global inode hash table with
m_count == 0, future __ksmbd_inode_lookup() calls reject it via
atomic_inc_not_zero(), and ksmbd_inode_free() is never invoked.
The race is:
T1: __ksmbd_inode_lookup() -> atomic_inc_not_zero(): m_count = 2
T2: ksmbd_inode_put() -> atomic_dec_and_test(): m_count = 1
(not freed)
T1: atomic_dec(&ci->m_count) -> m_count = 0
return (LEAK)
In ksmbd_lookup_fd_inode() the matched-fp path (which now also uses
ksmbd_inode_put()) cannot currently reach m_count == 0 because the
matched ksmbd_file holds its own reference on ci, but converting it to
the proper API keeps the three call sites consistent and avoids
future regressions if the locking changes.
Because ksmbd_inode_put() may free the ksmbd_inode if this drops the
last reference, the call must happen after up_read(&ci->m_lock) on the
two affected paths in ksmbd_lookup_fd_inode(). On the no-match path
this is a pure reordering; on the matched path ksmbd_fp_get() is
moved above the unlock so that the returned ksmbd_file is pinned
before the inode reference is released.
Signed-off-by: Aleksandr Golovnya <cofedish@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Commit d07b26f39246 ("ksmbd: require minimum ACE size in
smb_check_perm_dacl()") introduced a transposed bounds check:
if (offsetof(struct smb_ace, sid) + aces_size < CIFS_SID_BASE_SIZE)
Since offsetof(..sid) is 8 and CIFS_SID_BASE_SIZE is 8, this evaluates
to `aces_size < 0`. Because `aces_size` is always non-negative, this
check becomes dead code and never breaks the loop.
Worse, that commit removed the old 4-byte guard, meaning the loop now
reads `ace->size` (offset 2) even when `aces_size` is 0-3 bytes. This
re-opens a 2-byte heap out-of-bounds (OOB) read past the pntsd allocation
during subsequent SMB2_CREATE operations.
Fix this by properly transposing the comparison to require at least
16 bytes (8-byte offset + 8-byte SID base), matching the correct form
used in smb_inherit_dacl().
Fixes: d07b26f39246 ("ksmbd: require minimum ACE size in smb_check_perm_dacl()")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ganiyev <ali.qaniyev@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Pull smb server fixes from Steve French:
- fix for creating tmpfiles
- fix durable reconnect error path
- validate SID in security descriptor when inheriting DACL
* tag 'v7.1-rc5-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
smb/server: promote S_DEL_ON_CLS to S_DEL_PENDING when close
ksmbd: validate SID in parent security descriptor during ACL inheritance
ksmbd: fix durable reconnect error path file lifetime
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Pull smb client fixes from Steve French:
- Fix missing lock
- Fix dentry in use after unmounting
- cifs.upcall security fix
- require CAP_NET_ADMIN for swn netlink
- change allocation in DUP_CTX_STR to GFP_KERNEL
- minor smbdirect debug fix
- handle_read_data() folio fix
* tag 'v7.1-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
smb: client: change allocation requirements in DUP_CTX_STR macro
smb: client: require net admin for CIFS SWN netlink
smb: smbdirect: divide, not multiply, milliseconds by 1000
cifs: Fix busy dentry used after unmounting
smb: client: use data_len for SMB2 READ encrypted folioq copy
smb: client: reject userspace cifs.spnego descriptions
smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()
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Reproducer:
1. server: systemctl start ksmbd
2. client: mount -t cifs //${server_ip}/export /mnt
3. client: C program: openat(AT_FDCWD, "/mnt", O_RDWR | O_TMPFILE, 0600)
Do not treat `FILE_DELETE_ON_CLOSE_LE` as delete pending while files
remain open.
This patch fixes xfstests generic/004.
Cc: stable@vger.kernel.org
Link: https://chenxiaosong.com/en/smb-xfstests-generic-004.html
Co-developed-by: Huiwen He <hehuiwen@kylinos.cn>
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Tested-by: Steve French <stfrench@microsoft.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID
and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved
from the parent directory.
Cc: stable@vger.kernel.org
Signed-off-by: Junyi Liu <moss80199@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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After a durable reconnect succeeds, ksmbd_reopen_durable_fd() republishes
the same ksmbd_file into the session volatile-id table. If smb2_open()
then takes a later error path, cleanup first calls ksmbd_fd_put(work, fp)
and then unconditionally calls ksmbd_put_durable_fd(dh_info.fp).
In this case fp and dh_info.fp are the same object. The first put drops the
reconnect lookup reference, but the final durable put can run
__ksmbd_close_fd(NULL, fp). Because the final close is not session-aware,
it can free the file object without removing the volatile-id entry that was
just published into the session table.
Use the session-aware put for the final reconnect drop when the reconnect
had already succeeded and the error path is cleaning up the republished
file. Earlier reconnect failures, before fp is assigned to dh_info.fp, keep
using the durable-only put path.
Fixes: 1baff47b81f9 ("ksmbd: fix use-after-free in smb2_open during durable reconnect")
Signed-off-by: Junyi Liu <moss80199@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Currently, the macro DUP_CTX_STR allocates new_ctx->field using
GFP_ATOMIC. DUP_CTX_STR is only used in smb3_fs_context_dup(), which
is never called in an atomic context. Using GFP_ATOMIC puts unnecessary
pressure on emergency memory pools.
Change GFP_ATOMIC to GFP_KERNEL.
Signed-off-by: Fredric Cover <fredric.cover.lkernel@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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CIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command. The
intended sender is the cifs.witness helper, but the generic-netlink
operation currently has no capability flag, so any local process can send
RESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness
handler.
The same family exposes CIFS_GENL_MCGRP_SWN without multicast-group
capability flags. Register messages sent to that group include the witness
registration id and, for NTLM-authenticated mounts, the username, domain,
and password attributes copied from the CIFS session. An unprivileged
local process should not be able to join that group and receive those
messages.
Require CAP_NET_ADMIN for incoming SWN_NOTIFY commands with
GENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for
joining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN. The
cifs.witness service runs with the privileges needed for both operations.
Fixes: fed979a7e082 ("cifs: Set witness notification handler for messages from userspace daemon")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Steve French <stfrench@microsoft.com>
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Unless smbdirect_connection_legacy_debug_proc_show()
wants to debug-log keep_alive_interval as microseconds,
a magnitude higher precision than available by the way,
keepalive_interval_msec should not be multiplied by 1000.
Fixes: cc55f65dd352 ("smb: client: make use of common smbdirect_socket_parameters")
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Since commit 340cea84f691c ("cifs: open files should not hold ref on
superblock"), cifs file only holds the dentry ref_cnt, the cifs file
close work(cfile->deferred) could be executed after unmounting, which
will trigger a warning in generic_shutdown_super:
BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of
cifs cifs]
The detailed processs is:
process A process B kworker
fd = open(PATH)
vfs_open
file->__f_path = *path // dentry->d_lockref.count = 1
cifs_open
cifs_new_fileinfo
cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2
close(fd)
__fput
cifs_close
queue_delayed_work(deferredclose_wq, cfile->deferred)
dput(dentry) // dentry->d_lockref.count = 1
smb2_deferred_work_close
_cifsFileInfo_put
list_del(&cifs_file->flist)
umount
cleanup_mnt
deactivate_super
cifs_kill_sb
cifs_close_all_deferred_files_sb
cifs_close_all_deferred_files
// cannot find cfile, skip _cifsFileInfo_put
kill_anon_super
generic_shutdown_super
shrink_dcache_for_umount
umount_check
WARN ! // dentry->d_lockref.count = 1
cifsFileInfo_put_final
dput(cifs_file->dentry)
// dentry->d_lockref.count = 0
Fix it by flushing 'deferredclose_wq' before calling kill_anon_super.
Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.
Fixes: 340cea84f691c ("cifs: open files should not hold ref on superblock")
Cc: stable@vger.kernel.org
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Pull smb server fixes from Steve French:
- Fix two null pointer dereferences and a memory leak
* tag 'v7.1-rc4-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
ksmbd: fix null pointer dereference in compare_guid_key()
ksmbd: fix null pointer dereference in proc_show_files()
ksmbd: fix SID memory leak in set_posix_acl_entries_dacl() on overflow
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In handle_read_data() the encrypted/folioq branch
(buf_len <= data_offset, reached via receive_encrypted_read for
transform PDUs > CIFSMaxBufSize + MAX_HEADER_SIZE) copies the READ
payload using buffer_len rather than data_len:
rdata->result = cifs_copy_folioq_to_iter(buffer, buffer_len,
cur_off,
&rdata->subreq.io_iter);
...
rdata->got_bytes = buffer_len;
buffer_len comes from the SMB3 transform header OriginalMessageSize
field (OriginalMessageSize - read_rsp_size); it represents the size
of the decrypted message after the SMB2 header. data_len comes from
the SMB2 READ response DataLength field; it represents the actual
READ payload size and may be smaller than buffer_len when the
decrypted message contains padding or other trailing bytes after the
READ payload. The existing check `data_len > buffer_len - pad_len`
only enforces an upper bound, so a server that emits
OriginalMessageSize larger than read_rsp_size + pad_len + data_len
passes the check and the kernel copies buffer_len bytes per response,
ignoring the server-asserted DataLength.
Two observable failures with a crafted server (DataLength=4,
buffer_len=20000):
- the kernel returns 20000 bytes per sub-request to userspace and
sets got_bytes = buffer_len, even though the response claimed
only 4 bytes of payload;
- on a partial netfs sub-request whose iterator is sized to
data_len, the over-large copy_folio_to_iter() short-reads,
cifs_copy_folioq_to_iter() returns -EIO via the n != len path,
and the entire netfs read collapses to -EIO even though the
leading sub-requests succeeded.
Use data_len for the copy length and for got_bytes so the kernel
honours the server-asserted READ payload size. For well-formed
servers (where buffer_len == pad_len + data_len) the change is
behaviour-equivalent.
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Erazo <mendozayt13@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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cifs.spnego key descriptions contain authority-bearing fields such as
pid, uid, creduid, and upcall_target that cifs.upcall treats as
kernel-originating inputs. However, userspace can also create keys of
this type through request_key(2) or add_key(2), allowing those fields to
be supplied without CIFS origin.
Only accept cifs.spnego descriptions while CIFS is using its private
spnego_cred to request the key.
Fixes: f1d662a7d5e5 ("[CIFS] Add upcall files for cifs to use spnego/kerberos")
Assisted-by: avom-custom-harness:gpt-5.5-qwen3.6-mod-mix
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Asim Viladi Oglu Manizada <manizada@pm.me>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields")
refactored cifs code to change cifs_tcp_ses_lock for tc_lock around
tc_count changes.
There was missing lock around tc_count increment inside
smb2_find_smb_sess_tcon_unlocked().
Cc: stable@vger.kernel.org
Fixes: 96c4af418586 ("cifs: Fix locking usage for tcon fields")
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Fix a couple of undefined variables introduced by the patch to fix tearing
on ->remote_i_size and ->zero_point. For some reason, make W=1 with gcc
doesn't give undefined variable warnings (but clang does).
Fixes: 2c8f4742bb76 ("netfs: Fix potential for tearing in ->remote_i_size and ->zero_point")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202605031459.eX5UbO3K-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202605021450.ca5QGqLH-lkp@intel.com/
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: Christian Brauner <brauner@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
"This contains a fixes for the current development cycle. Note that AI
related review sometimes delays fixes a bit because we find more fixes
for the fixes. I might try and send smaller but more fixes PRs if this
trend keeps up.
- Fix various netfslib bugs
- Fix an out-of-bounds write when listing idmappings
- Fix the return values in jfs_mkdir() and orangefs_mkdir()
- Fix a writeback writeback array overflow in fuse
- Fix a forced iversion increment on lazytime timestamp updates
- Reject a negative timeval component in kern_select()
- Fix error return when vfs_mkdir() fails in the cachefiles code
- Fix wrong error code returned for pidns ioctls"
* tag 'vfs-7.1-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (31 commits)
cachefiles: Fix error return when vfs_mkdir() fails
afs: Fix the locking used by afs_get_link()
netfs, afs: Fix write skipping in dir/link writepages
netfs: Fix netfs_read_folio() to wait on writeback
netfs: Fix folio->private handling in netfs_perform_write()
netfs: Fix partial invalidation of streaming-write folio
netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages()
netfs: Fix leak of request in netfs_write_begin() error handling
netfs: Fix early put of sink folio in netfs_read_gaps()
netfs: Fix write streaming disablement if fd open O_RDWR
netfs: Fix read-gaps to remove netfs_folio from filled folio
netfs: Fix potential deadlock in write-through mode
netfs: Fix streaming write being overwritten
netfs: Defer the emission of trace_netfs_folio()
netfs: Fix netfs_invalidate_folio() to clear dirty bit if all changes gone
netfs: Fix overrun check in netfs_extract_user_iter()
netfs: fix error handling in netfs_extract_user_iter()
netfs: Fix potential uninitialised var in netfs_extract_user_iter()
netfs: fix VM_BUG_ON_FOLIO() issue in netfs_write_begin() call
netfs: Fix zeropoint update where i_size > remote_i_size
...
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Fix smbdirect_map_sges_from_iter() to use pre-decrement, not post-decrement
so that it cleans up the correct slots.
Fixes: e5fbdde43017 ("cifs: Add a function to build an RDMA SGE list from an iterator")
Closes: https://sashiko.dev/#/patchset/20260326104544.509518-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Tom Talpey <tom@talpey.com>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
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SMB2 READ response validation in cifs_readv_receive() and
handle_read_data() checks data_offset + data_len against the received
buffer length. Both values are attacker-controlled fields from the
server response and are stored as unsigned int, so the addition can
wrap before the bounds check:
fs/smb/client/transport.c:1259
if (!use_rdma_mr && (data_offset + data_len > buflen))
fs/smb/client/smb2ops.c:4839
else if (buf_len >= data_offset + data_len)
A malicious SMB server can use this to bypass validation. In the
non-encrypted receive path the client attempts an oversized socket
read and stalls for the SMB response timeout (180 seconds) before
reconnecting. In the SMB3 encrypted path, runtime testing shows the
malformed length can reach copy_to_iter() in handle_read_data() with
attacker-controlled size, where usercopy hardening stops the oversized
copy before bytes reach userspace.
Guard both call sites with check_add_overflow(), which is already
used elsewhere in this subsystem (smb2pdu.c). On overflow, treat the
response as malformed and reject with -EIO.
Signed-off-by: Jeremy Erazo <mendozayt13@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb3_reconfigure() moves strings out of cifs_sb->ctx before the
multichannel update, so a later failure can leave the live context
with NULL strings or options that do not match the session.
Stage the new ctx separately, commit it only on success, and restore
the snapshot on failure. Also make smb3_sync_session_ctx_passwords()
all-or-nothing.
Commit session passwords before channel updates so newly added channels
authenticate with the staged credentials.
Fixes: ef529f655a2c ("cifs: client: allow changing multichannel mount options on remount")
Reported-by: RAJASI MANDAL <rajasimandalos@gmail.com>
Closes: https://lore.kernel.org/lkml/CAEY6_V1+dzW3OD5zqXhsWyXwrDTrg5tAMGZ1AJ7_GAuRE+aevA@mail.gmail.com/
Link: https://lore.kernel.org/lkml/xkr2dlvgibq5j6gkcxd3yhhnj4atgxw2uy4eug2pxm7wy7nbms@iq6cf5taa65v/
Reviewed-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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On 32-bit architectures, the infinite loop is as follows:
len = p->ErrorDataLength == 0xfffffff8
u8 *next = p->ErrorContextData + len
next == p
On 32-bit architectures, the out-of-bounds read is as follows:
len = p->ErrorDataLength == 0xfffffff0
u8 *next = p->ErrorContextData + len
next == (u8 *)p - 8
Reported-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+")
Cc: stable@vger.kernel.org
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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session_fd_check() walks the per-inode m_op_list during durable-handle
session teardown and sets op->conn = NULL for every opinfo whose conn
matched the closing session's connection. The matching opinfo, however,
stays linked in its per-ClientGuid lease_table_list entry's lb->lease_list
because destroy_lease_table() only runs on full TCP-connection teardown,
not on SESSION_LOGOFF.
If the same TCP connection then negotiates a fresh session with the
same ClientGuid (ClientGuid is bound to NEGOTIATE, not the session, and
is unchanged across LOGOFF + SETUP) and issues a SMB2 CREATE with a
lease context on a different inode, find_same_lease_key() walks
lb->lease_list, reaches the stale opinfo, and calls compare_guid_key(),
which unconditionally dereferences opinfo->conn->ClientGUID. The conn
pointer is NULL and the kernel panics.
Reproducer requires only a successful SMB2 SESSION_SETUP and a share
configured with 'durable handles = yes'. KASAN report on mainline
70390501d194:
general protection fault, probably for non-canonical address
0xdffffc0000000069: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000348-0x000000000000034f]
Workqueue: ksmbd-io handle_ksmbd_work
RIP: 0010:bcmp+0x5b/0x230
Call Trace:
compare_guid_key+0x4b/0xd0
find_same_lease_key+0x324/0x690
smb2_open+0x6aea/0x8e60
handle_ksmbd_work+0x796/0xee0
...
Faulting address 0x348 is the offset of ClientGUID within struct
ksmbd_conn, confirming opinfo->conn was NULL.
Read opinfo->conn once and bail out if it has been cleared by a
concurrent session_fd_check(). A half-detached opinfo cannot be the
owner of an active lease, so returning 0 is the correct match result.
Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2")
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Laratro <research@aradex.io>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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When a SMB2 client opens a file with a durable v2 handle and then issues
SMB2 SESSION_LOGOFF, session_fd_check() clears fp->tcon = NULL on the
reconnectable file pointer but leaves the fp registered in global_ft.idr
until the durable scavenger fires (up to fp->durable_timeout seconds
later).
During that window any read of /proc/fs/ksmbd/files (mode 0400) panics
the kernel because proc_show_files() walks global_ft.idr and
unconditionally dereferences fp->tcon->id with no NULL guard.
Reproducer requires only a successful SMB2 SESSION_SETUP and a share
configured with 'durable handles = yes'. KASAN report on mainline
70390501d194:
general protection fault, probably for non-canonical address
0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:proc_show_files+0x118/0x740
Call Trace:
proc_show_files+0x118/0x740
seq_read_iter+0x4ef/0xe10
proc_reg_read_iter+0x1b7/0x280
...
Guard the dereference. A durable-disconnected fp legitimately has no
tcon; report its tree id as 0 rather than oopsing.
Fixes: b38f99c1217a ("ksmbd: add procfs interface for runtime monitoring and statistics")
Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Laratro <research@aradex.io>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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Commit 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16
DACL size overflow") added check_add_overflow() guards that break out
of the ACE-building loops in set_posix_acl_entries_dacl() when the
accumulated DACL size would wrap past 65535.
However, each iteration allocates a struct smb_sid via kmalloc_obj()
at the top of the loop and relies on the kfree(sid) call at the end
of the loop body (the 'pass_same_sid' label in the first loop, and
the explicit kfree at the tail of the second loop) to release it.
The newly introduced 'break' statements bypass those kfree() calls,
leaking the sid buffer every time an overflow is detected.
A malicious or malformed file with enough POSIX ACL entries to trip
the overflow check will leak one or more struct smb_sid allocations
on every request that touches the file's DACL, providing a trivial
kernel memory exhaustion vector.
Free sid before breaking out of the loops to plug the leak.
Fixes: 299f962c0b02 ("ksmbd: use check_add_overflow() to prevent u16 DACL size overflow")
Cc: stable@vger.kernel.org
Signed-off-by: Ferry Meng <mengferry@linux.alibaba.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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New Infolevels for QUERY_DIR (and QUERY_INFO) levels 78 through 81 are
now being used by Windows clients and were added to the documentation.
Add defines for them (and correct some typos in documentation). See
MS-SMB2 2.2.33 and MS-FSCC 2.4
Signed-off-by: Steve French <stfrench@microsoft.com>
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Fix potential tearing in using ->remote_i_size and ->zero_point by copying
i_size_read() and i_size_write() and using the same seqcount as for i_size.
We need to make sure that netfslib and the filesystems that use it always
hold i_lock whilst updating any of the sizes to prevent i_size_seqcount
from getting corrupted.
Fixes: 4058f742105e ("netfs: Keep track of the actual remote file size")
Fixes: 100ccd18bb41 ("netfs: Optimise away reads above the point at which there can be no data")
Closes: https://sashiko.dev/#/patchset/20260414082004.3756080-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-6-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Pull smb client fixes from Steve French:
- Fix for two ACL issues (security fix to validate dacloffset better
and chmod fix)
- Fix out of bounds reads (in check_wsl_eas and smb2_check_msg for
symlinks)
- Two Kerberos fixes including an important one when AES-256 encryption
chosen
- Fix open_cached_dir problem when directory leases disabled
* tag 'v7.1-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
smb: client: validate dacloffset before building DACL pointers
smb/client: fix out-of-bounds read in smb2_compound_op()
smb/client: fix out-of-bounds read in symlink_data()
smb: client: Zero-pad short GSS session keys per MS-SMB2
smb: client: Use FullSessionKey for AES-256 encryption key derivation
smb: client: use kzalloc to zero-initialize security descriptor buffer
cifs: abort open_cached_dir if we don't request leases
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parse_sec_desc(), build_sec_desc(), and the chown path in
id_mode_to_cifs_acl() all add the server-supplied dacloffset to pntsd
before proving a DACL header fits inside the returned security
descriptor.
On 32-bit builds a malicious server can return dacloffset near
U32_MAX, wrap the derived DACL pointer below end_of_acl, and then slip
past the later pointer-based bounds checks. build_sec_desc() and
id_mode_to_cifs_acl() can then dereference DACL fields from the wrapped
pointer in the chmod/chown rewrite paths.
Validate dacloffset numerically before building any DACL pointer and
reuse the same helper at the three DACL entry points.
Fixes: bc3e9dd9d104 ("cifs: Change SIDs in ACEs while transferring file ownership.")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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If a server sends a truncated response but a large OutputBufferLength, and
terminates the EA list early, check_wsl_eas() returns success without
validating that the entire OutputBufferLength fits within iov_len.
Then smb2_compound_op() does:
memcpy(idata->wsl.eas, data[0], size[0]);
Where size[0] is OutputBufferLength. If iov_len is smaller than size[0],
memcpy can read beyond the end of the rsp_iov allocation and leak adjacent
kernel heap memory.
Link: https://lore.kernel.org/linux-cifs/d998240c-aca9-420d-9dbd-f5ba24af19e0@chenxiaosong.com/
Fixes: ea41367b2a60 ("smb: client: introduce SMB2_OP_QUERY_WSL_EA")
Cc: stable@vger.kernel.org
Signed-off-by: Zisen Ye <zisenye@stu.xidian.edu.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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Since smb2_check_message() returns success without length validation for
the symlink error response, in symlink_data() it is possible for
iov->iov_len to be smaller than sizeof(struct smb2_err_rsp). If the buffer
only contains the base SMB2 header (64 bytes), accessing
err->ErrorContextCount (at offset 66) or err->ByteCount later in
symlink_data() will cause an out-of-bounds read.
Link: https://lore.kernel.org/linux-cifs/297d8d9b-adf7-42fd-a1c2-5b1f230032bc@chenxiaosong.com/
Fixes: 76894f3e2f71 ("cifs: improve symlink handling for smb2+")
Cc: Stable@vger.kernel.org
Signed-off-by: Zisen Ye <zisenye@stu.xidian.edu.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Per MS-SMB2 section 3.2.5.3, Session.SessionKey is the first 16 bytes
of the GSS cryptographic key, right-padded with zero bytes if the key
is shorter than 16 bytes.
SMB2_auth_kerberos() copies the GSS session key from the cifs.upcall
response using kmemdup(msg->data, msg->sesskey_len, ...) and stores
the GSS-reported length verbatim in ses->auth_key.len. generate_key()
reads SMB2_NTLMV2_SESSKEY_SIZE bytes from this buffer when feeding the
HMAC-SHA256 KDF for signing key derivation. If a GSS mechanism returns
a session key shorter than 16 bytes (e.g. a deprecated single-DES
Kerberos enctype with an 8-byte session key), the KDF call performs an
out-of-bounds slab read and derives keys that do not match the server,
which pads per the spec.
Modern KDCs disable short-key enctypes by default, so this is latent
rather than reachable in production, but it is still a kernel heap
over-read.
Allocate auth_key.response with kzalloc() at a length of
max(msg->sesskey_len, SMB2_NTLMV2_SESSKEY_SIZE), copy the GSS key in,
and rely on kzalloc()'s zero initialization for the spec-mandated
padding. Set ses->auth_key.len to the padded length. Larger GSS keys
(e.g. the 32-byte aes256-cts-hmac-sha1-96 session key) continue to be
stored at their natural length, preserving the FullSessionKey path.
Emit a cifs_dbg(VFS, ...) message when a short key is encountered to
surface deprecated-enctype usage.
NTLMv2 and NTLMSSP code paths produce a 16-byte session key by
construction and are unaffected.
Signed-off-by: Piyush Sachdeva <psachdeva@microsoft.com>
Signed-off-by: Piyush Sachdeva <s.piyush1024@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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When Kerberos authentication is used with AES-256 encryption (AES-256-CCM
or AES-256-GCM), the SMB3 encryption and decryption keys must be derived
using the full session key (Session.FullSessionKey) rather than just the
first 16 bytes (Session.SessionKey).
Per MS-SMB2 section 3.2.5.3.1, when Connection.Dialect is "3.1.1" and
Connection.CipherId is AES-256-CCM or AES-256-GCM, Session.FullSessionKey
must be set to the full cryptographic key from the GSS authentication
context. The encryption and decryption key derivation (SMBC2SCipherKey,
SMBS2CCipherKey) must use this FullSessionKey as the KDF input. The
signing key derivation continues to use Session.SessionKey (first 16
bytes) in all cases.
Previously, generate_key() hardcoded SMB2_NTLMV2_SESSKEY_SIZE (16) as the
HMAC-SHA256 key input length for all derivations. When Kerberos with
AES-256 provides a 32-byte session key, the KDF for encryption/decryption
was using only the first 16 bytes, producing keys that did not match the
server's, causing mount failures with sec=krb5 and require_gcm_256=1.
Add a full_key_size parameter to generate_key() and pass the appropriate
size from generate_smb3signingkey():
- Signing: always SMB2_NTLMV2_SESSKEY_SIZE (16 bytes)
- Encryption/Decryption: ses->auth_key.len when AES-256, otherwise 16
Also fix cifs_dump_full_key() to report the actual session key length for
AES-256 instead of hardcoded CIFS_SESS_KEY_SIZE, so that userspace tools
like Wireshark receive the correct key for decryption.
Cc: <stable@vger.kernel.org>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Piyush Sachdeva <psachdeva@microsoft.com>
Signed-off-by: Piyush Sachdeva <s.piyush1024@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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Commit 62e7dd0a39c2d ("smb: common: change the data type of num_aces
to le16") split struct smb_acl's __le32 num_aces field into __le16
num_aces and __le16 reserved. The reserved field corresponds to Sbz2
in the MS-DTYP ACL wire format, which must be zero [1].
When building an ACL descriptor in build_sec_desc(), we are using a
kmalloc()'ed descriptor buffer and writing the fields explicitly using
le16() writes now. This never writes to the 2 byte reserved field,
leaving it as uninitialized heap data.
When the reserved field happens to contain non-zero slab garbage,
Samba rejects the security descriptor with "ndr_pull_security_descriptor
failed: Range Error", causing chmod to fail with EINVAL.
Change kmalloc() to kzalloc() to ensure the entire buffer is
zero-initialized.
Fixes: 62e7dd0a39c2d ("smb: common: change the data type of num_aces to le16")
Cc: stable@vger.kernel.org
Signed-off-by: Bjoern Doebel <doebel@amazon.de>
Assisted-by: Kiro:claude-opus-4.6
[1] https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/20233ed8-a6c6-4097-aafa-dd545ed24428
Signed-off-by: Steve French <stfrench@microsoft.com>
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It is possible that SMB2_open_init may not set lease context based
on the requested oplock level. This can happen when leases have been
temporarily or permanently disabled. When this happens, we will have
open_cached_dir making an open without lease context and the response
will anyway be rejected by open_cached_dir (thereby forcing a close to
discard this open). That's unnecessary two round-trips to the server.
This change adds a check before making the open request to the server
to make sure that SMB2_open_init did add the expected lease context
to the open in open_cached_dir.
Cc: <stable@vger.kernel.org>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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smb_inherit_dacl() walks the parent directory DACL loaded from the
security descriptor xattr. It verifies that each ACE contains the fixed
SID header before using it, but does not verify that the variable-length
SID described by sid.num_subauth is fully contained in the ACE.
A malformed inheritable ACE can advertise more subauthorities than are
present in the ACE. compare_sids() may then read past the ACE.
smb_set_ace() also clamps the copied destination SID, but used the
unchecked source SID count to compute the inherited ACE size. That could
advance the temporary inherited ACE buffer pointer and nt_size accounting
past the allocated buffer.
Fix this by validating the parent ACE SID count and SID length before
using the SID during inheritance. Compute the inherited ACE size from the
copied SID so the size matches the bounded destination SID. Reject the
inherited DACL if size accumulation would overflow smb_acl.size or the
security descriptor allocation size.
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Shota Zaizen <s@zaizen.me>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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The kernel test robot reported W=1 build warnings for ksmbd_conn_get()
and ksmbd_conn_put() due to missing parameter descriptions.
Add the @conn description to fix these warnings.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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Non-pipe shares must have a duplicated backing path before they can be
published. share_config_request() currently calls kstrndup() for that
path, but if the allocation fails it leaves ret unchanged. If veto list
parsing succeeds and share->name exists, the partially built share is
still inserted into the global share table with share->path left NULL.
A later share-root SMB2 create uses tree_conn->share_conf->path as the
lookup root. If the share was published with path == NULL, that request
passes a NULL pathname into do_getname_kernel()/strlen() and can crash
the ksmbd worker.
Set ret = -ENOMEM when path duplication fails so the incomplete share is
destroyed before publication.
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
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ksmbd_durable_scavenger() has two related races against any walker
that iterates f_ci->m_fp_list, including ksmbd_lookup_fd_inode()
(used by ksmbd_vfs_rename) and the share-mode checks in
fs/smb/server/smb_common.c.
(1) fp->node list-head reuse. Durable-preserved handles can remain
linked on f_ci->m_fp_list after session teardown so share-mode checks
still see them while the handle is reconnectable. The scavenger
collected expired handles by adding fp->node to a local
scavenger_list after removing them from the global durable idr.
Because fp->node is the same list_head used by m_fp_list,
list_add(&fp->node, &scavenger_list) overwrites the m_fp_list links
and corrupts both lists. CONFIG_DEBUG_LIST can report this on the
share-mode walk path.
(2) Refcount race against m_fp_list walkers. The scavenger qualifies
an expired durable handle with atomic_read(&fp->refcount) > 1 and
fp->conn under global_ft.lock, removes fp from global_ft, then drops
global_ft.lock before unlinking fp from m_fp_list and freeing it.
During that gap fp is still linked on m_fp_list with f_state ==
FP_INITED. ksmbd_lookup_fd_inode() under m_lock read calls
ksmbd_fp_get() (atomic_inc_not_zero on refcount that is still 1) and
takes a live reference; the scavenger then unlinks and frees fp
while the holder owns a reference, leading to UAF on the holder's
subsequent ksmbd_fd_put() and on any field reads performed by a
concurrent share-mode walker that iterates m_fp_list without taking
ksmbd_fp_get() (smb_check_perm_dleases-like paths).
Fix both:
* Stop reusing fp->node as a scavenger-private list node. Remove
one expired handle from global_ft under global_ft.lock, take an
explicit transient reference, drop the lock, unlink fp->node
from m_fp_list under f_ci->m_lock, then drop both the durable
lifetime and transient references with atomic_sub_and_test(2,
&fp->refcount). If the scavenger is the last putter the close
runs there; otherwise an in-flight holder that already raced
through the m_fp_list lookup owns the final close via its
ksmbd_fd_put() path. The one-at-a-time disposal can rescan the
durable idr when multiple handles expire in the same pass, but
durable scavenging is a background expiration path and the final
full scan recomputes min_timeout before the next wait.
* Clear fp->persistent_id inside __ksmbd_remove_durable_fd() right
after idr_remove(), so a delayed final close from a holder that
snatched fp does not re-issue idr_remove() on a persistent id
that idr_alloc_cyclic() in ksmbd_open_durable_fd() may have
already handed out to a brand-new durable handle.
* Bypass the per-conn open_files_count decrement in
__put_fd_final() when fp is detached from any session table
(fp->conn cleared by session_fd_check() at durable preserve --
paired with the volatile_id clear at unpublish, so checking
fp->conn alone is sufficient). The walker that owns the final
close runs from an unrelated work->conn whose
stats.open_files_count never tracked this durable fp; without
this guard the holder would underflow that unrelated counter.
The two races are folded into one patch because patch (1) alone
cleans up the corrupted list but leaves a deterministic UAF window
for m_fp_list walkers that the transient-reference and
persistent_id discipline in (2) close; bisecting onto an
intermediate state would land on a UAF that pre-patch chaos merely
made less reproducible.
Validation:
* CONFIG_DEBUG_LIST coverage for the list_head reuse path.
* KASAN-enabled direct SMB2 durable-handle coverage that exercised
ksmbd_durable_scavenger() and non-NULL ksmbd_lookup_fd_inode()
returns while durable handles expired under concurrent rename
lookups, with no KASAN, UAF, list-corruption, ODEBUG, or WARNING
reports.
* checkpatch --strict
* make -j$(nproc) M=fs/smb/server
Fixes: d484d621d40f ("ksmbd: add durable scavenger timer")
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
|
|
__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 <charsyam@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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ksmbd_conn_free() is one of four sites that can observe the last
refcount drop of a struct ksmbd_conn. The other three
fs/smb/server/connection.c ksmbd_conn_r_count_dec()
fs/smb/server/oplock.c __free_opinfo()
fs/smb/server/vfs_cache.c session_fd_check()
end the conn with a bare kfree(), skipping
ida_destroy(&conn->async_ida) and
conn->transport->ops->free_transport(conn->transport). Whenever one
of them is the last putter, the embedded async_ida and the entire
transport struct leak -- for TCP, that is also the struct socket and
the kvec iov.
__free_opinfo() being a final putter is not theoretical. opinfo_put()
queues the callback via call_rcu(&opinfo->rcu, free_opinfo_rcu), so
ksmbd_server_terminate_conn() can deposit N opinfo releases in RCU and
have ksmbd_conn_free() run in the handler thread before any of them
fire. ksmbd_conn_free() then observes refcnt > 0 and short-circuits;
the last RCU-delivered __free_opinfo() falls onto its bare kfree(conn)
branch and the transport is lost.
A/B validation in a QEMU/virtme guest, mounting //127.0.0.1/testshare:
each iteration holds 8 files open via sleep processes, force-closes
TCP with "ss -K sport = :445", kills the holders, lazy-umounts;
repeated 10 times, then ksmbd shutdown and kmemleak scan.
state conn_alloc conn_free tcp_free opi_rcu kmemleak
---------- ---------- --------- -------- ------- --------
pre-patch 20 20 10 160 7
with patch 20 20 20 160 0
Pre-patch conn_free=20 with tcp_free=10 directly demonstrates the
bare-kfree paths skipping transport cleanup; kmemleak backtraces point
into struct tcp_transport / iov. With this patch tcp_free matches
conn_free at 20/20 and kmemleak is clean.
Move the per-struct final release into __ksmbd_conn_release_work() and
route the three bare-kfree final-put sites through a new
ksmbd_conn_put(). Those sites now pair ida_destroy() and
free_transport() with kfree(conn) regardless of which holder happens
to release the last reference. stop_sessions() only triggers the
transport shutdown and does not itself drop the last conn reference,
so it is unaffected.
The centralized release reaches sock_release() -> tcp_close() ->
lock_sock_nested() (might_sleep) from every final putter, including
__free_opinfo() invoked from an RCU softirq callback, which trips
CONFIG_DEBUG_ATOMIC_SLEEP. Defer the release to a dedicated
ksmbd_conn_wq workqueue so ksmbd_conn_put() is safe from any
non-sleeping context.
Make ksmbd_file own a strong connection reference while fp->conn is
non-NULL so durable-preserve and final-close paths cannot dereference
a stale connection. ksmbd_open_fd() and ksmbd_reopen_durable_fd()
take the reference via ksmbd_conn_get() (the latter also reorders the
fp->conn / fp->tcon assignments before __open_id() so the published fp
is never observed with fp->conn == NULL); session_fd_check() and
__ksmbd_close_fd() drop it via ksmbd_conn_put(). With that invariant,
session_fd_check() can take a local conn pointer once and use it
across the m_op_list and lock_list iterations even though op->conn
puts may otherwise drop the last reference.
At module exit the workqueue is flushed and destroyed after
rcu_barrier(), so any release queued by a trailing RCU callback is
drained before the inode hash and module text go away.
Fixes: ee426bfb9d09 ("ksmbd: add refcnt to ksmbd_conn struct")
Signed-off-by: DaeMyung Kang <charsyam@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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ib_dma_map_sg() modifies the provided scatterlist and returns the
number of mapped entries, which can be fewer than the requested
mr->sgt.nents if the DMA controller coalesces contiguous memory
segments. Passing the original, uncoalesced count to ib_map_mr_sg()
causes memory registration failures if coalescing actually occurs.
Capture the actual mapped count returned by ib_dma_map_sg() and pass it
to ib_map_mr_sg() to ensure correct MR registration.
Also update the ib_dma_map_sg() error logging to drop the error
pointer formatting, since the return value is an integer count
rather than an error code.
Ensure a proper error code (-EIO) is assigned when DMA mapping or
MR registration fails.
Fixes: de5ef8ec3c46 ("smb: smbdirect: introduce smbdirect_mr.c with client mr code")
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221408
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Yi Kuo <yi@yikuo.dev>
Signed-off-by: Steve French <stfrench@microsoft.com>
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This makes it easier to rebuild cifs.ko and ksmbd.ko against
a running kernel.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/linux-cifs/aehrPuY60VMcYGU8@infradead.org/
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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This is a better solution than
EXPORT_SYMBOL_FOR_MODULES(__sym, "cifs,ksmbd") as it makes
it possible to rebuild smbdirect.ko against a
running kernel and then load the existing cifs.ko and ksmbd.ko
from the running kernel.
Suggested-by: Christoph Hellwig <hch@infradead.org>
Link: https://lore.kernel.org/linux-cifs/aehrPuY60VMcYGU8@infradead.org/
Cc: Steve French <smfrench@gmail.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Long Li <longli@microsoft.com>
Cc: Namjae Jeon <linkinjeon@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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