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Pull smb server fixes from Steve French:
"ksmbd server fixes, mostly addressing malformed SMB request
handling and connection/session lifetime issues, including
two information-disclosure or memory-safety bugs in the SMB2
request/response paths.
- validate FILE_ALLOCATION_INFORMATION before block rounding to
prevent a client-controlled overflow from truncating a file.
- pin connections while asynchronous oplock and lease-break
notifications are pending.
- initialize compound SMB2 READ alignment padding, preventing
disclosure of uninitialized heap bytes.
- release the allocated alternate-stream xattr name after rename.
- size multichannel binding session-key buffers for the largest
permitted key, avoiding a stack buffer overflow.
- remove a disconnecting connection's channels from every session,
including channels whose binding state has since changed.
- serialize binding preauthentication-session lookup and update
against its teardown.
- check that every compound request element contains StructureSize2
before reading it"
* tag 'v7.2-rc3-smb3-server-fixes' of git://git.samba.org/ksmbd:
ksmbd: validate compound request size before reading StructureSize2
ksmbd: lock the binding preauth session in smb3_preauth_hash_rsp
ksmbd: remove stale channels from all sessions on teardown
ksmbd: fix stack buffer overflow in multichannel session-key copy
ksmbd: fix memory leak of xattr_stream_name in smb2_rename()
ksmbd: zero the smb2_read alignment tail to avoid an infoleak
ksmbd: pin conn during async oplock break notification
ksmbd: fix integer overflow in set_file_allocation_info()
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When ksmbd validates a compound (chained) SMB2 request,
ksmbd_smb2_check_message() reads pdu->StructureSize2 without first
checking that the compound element is large enough to contain it.
StructureSize2 is a 2-byte field at offset 64
(__SMB2_HEADER_STRUCTURE_SIZE) from the start of each element.
The compound-walking logic only guarantees that a full 64-byte SMB2
header is present for the trailing element: when NextCommand is 0, len is
reduced to the number of bytes remaining after next_smb2_rcv_hdr_off. A
remote client can craft a compound request whose last element has exactly
64 bytes, so the 2-byte StructureSize2 read at offset 64 extends one byte
past the receive buffer, producing a slab-out-of-bounds read.
BUG: KASAN: slab-out-of-bounds in ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402)
Read of size 2 at addr ffff888012ae31ac by task kworker/0:1/14
The buggy address is located 172 bytes inside of allocated 173-byte region
Workqueue: ksmbd-io handle_ksmbd_work
Call Trace:
...
kasan_report (mm/kasan/report.c:595)
ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402)
handle_ksmbd_work (fs/smb/server/server.c:119)
process_one_work (kernel/workqueue.c:3314)
worker_thread (kernel/workqueue.c:3397)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:158)
ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
Reject any compound element that is too small to hold StructureSize2
before dereferencing it.
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Reported-by: AutonomousCodeSecurity@microsoft.com
Signed-off-by: Xiang Mei (Microsoft) <xmei5@asu.edu>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb3_preauth_hash_rsp() computes the SMB3.1.1 preauth integrity hash on
the response path. For a binding SESSION_SETUP it looks up the
per-connection preauth_session and reads its Preauth_HashValue.
smb2_sess_setup() frees that preauth_session under ksmbd_conn_lock().
Two SMB2 requests on one connection can run concurrently, so an unlocked
lookup and hash can use a preauth_session after another worker frees it.
Take ksmbd_conn_lock() before selecting conn->binding and hold it across
the selected preauth hash lookup and update. This preserves the existing
hash selection while preventing the lookup-to-use lifetime race.
Fixes: 1c5daa2ea924 ("ksmbd: handle channel binding with a different user")
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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ksmbd_sessions_deregister() removes a connection's channels from other
sessions' channel lists only while conn->binding is still set:
if (conn->binding) {
hash_for_each_safe(sessions_table, ...)
ksmbd_chann_del(conn, sess);
}
conn->binding is a transient flag: it is cleared once a binding
SESSION_SETUP completes, and also by a subsequent non-binding
SESSION_SETUP on the same connection (a reauthentication on a bound
channel, or a new SessionId==0 setup). A connection that has bound a
channel into another session's ksmbd_chann_list and then clears
conn->binding leaves that channel behind when it disconnects: the
channel, whose chann->conn points at the now freed struct ksmbd_conn,
stays on the owner session's list.
When the owning connection later tears down, the second loop
dereferences the stale channel:
xa_for_each(&sess->ksmbd_chann_list, chann_id, chann)
if (chann->conn != conn)
ksmbd_conn_set_exiting(chann->conn); /* freed */
which is a use-after-free write into the freed ksmbd_conn (the same
stale channel is also walked by show_proc_session() through /proc). The
session is leaked as well, because its channel list never empties.
Remove the conn->binding gate so a connection always removes its
channels from every session on teardown.
Fixes: faf8578c77f3 ("ksmbd: find bound sessions during reauthentication")
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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Commit 4b706360ffb7 ("ksmbd: fix multichannel binding and enforce channel
limit") moved the binding-path session key out of the session-wide
sess->sess_key (CIFS_KEY_SIZE = 40) into a new per-channel buffer, and
sized both that buffer and the on-stack copy used during binding with
SMB2_NTLMV2_SESSKEY_SIZE (16):
struct channel {
char sess_key[SMB2_NTLMV2_SESSKEY_SIZE]; /* 16 */
...
};
ntlm_authenticate() / krb5_authenticate():
char channel_key[SMB2_NTLMV2_SESSKEY_SIZE] = {}; /* 16 */
char *auth_key = conn->binding ? channel_key : sess->sess_key;
The two writers that fill this destination still bound the copy length
against CIFS_KEY_SIZE (40), not against the 16-byte buffer:
ksmbd_decode_ntlmssp_auth_blob() (NTLM key exchange):
if (sess_key_len > CIFS_KEY_SIZE) /* 40 */
return -EINVAL;
arc4_crypt(ctx_arc4, sess_key,
(char *)authblob + sess_key_off, sess_key_len);
ksmbd_krb5_authenticate():
if (resp->session_key_len > sizeof(sess->sess_key)) /* 40 */
...
memcpy(sess_key, resp->payload, resp->session_key_len);
On a binding SESSION_SETUP, auth_key points at the 16-byte channel_key,
so a client that supplies an NTLM EncryptedRandomSessionKey of up to 40
bytes (with NTLMSSP_NEGOTIATE_KEY_EXCH), or a Kerberos ticket whose
session key is longer than 16 bytes (a normal AES256 key is 32), writes
past the 16-byte stack buffer -- up to a 24-byte kernel stack overflow.
KASAN reports it as a stack-out-of-bounds write in arc4_crypt() called
from ksmbd_decode_ntlmssp_auth_blob().
The destinations must be able to hold the full session key the length
checks already permit. Size the per-channel key buffer and the two
on-stack channel_key buffers with CIFS_KEY_SIZE, matching sess->sess_key.
Fixes: 4b706360ffb7 ("ksmbd: fix multichannel binding and enforce channel limit")
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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On an SMB2 SET_INFO(FileRenameInformation) whose target names an alternate
data stream, smb2_rename() obtains a formatted stream-name string from
ksmbd_vfs_xattr_stream_name(), which allocates it with kasprintf() and
returns it through an out-param:
rc = ksmbd_vfs_xattr_stream_name(stream_name, &xattr_stream_name, ...);
if (rc)
goto out;
rc = ksmbd_vfs_setxattr(..., xattr_stream_name, ...);
if (rc < 0) {
...
goto out;
}
goto out;
xattr_stream_name is declared inside the alternate-data-stream block, but
the out: label is outside that block and frees only new_name, so it cannot
release xattr_stream_name. ksmbd_vfs_setxattr() takes a const char * and
only reads the name, so it does not take ownership either. Both the
setxattr-failure and the success path therefore leak the kasprintf()'d
string. An authenticated client with a writable share can leak kernel
memory on every stream rename, exhausting kernel memory over time.
Free xattr_stream_name after its use, before the block's goto out. The
two earlier goto out paths never assign the variable, so there is no
double-free.
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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Commit 6b9a2e09d4cc ("ksmbd: avoid zeroing the read buffer in smb2_read()")
switched the SMB2 READ payload buffer from kvzalloc() to kvmalloc(), on the
premise that only the nbytes actually read are ever transmitted, so the
ALIGN(length, 8) tail need not be initialized.
That premise does not hold for a compound response. ksmbd_vfs_read() fills
only nbytes, leaving [nbytes, ALIGN(length, 8)) uninitialized. The aux
payload is pinned as the last response iov with iov_len == nbytes, but when
the READ is a member of a compound, init_chained_smb2_rsp() 8-byte-aligns
the previous member by extending that same iov:
new_len = ALIGN(len, 8);
work->iov[work->iov_idx].iov_len += (new_len - len);
inc_rfc1001_len(work->response_buf, new_len - len);
so up to 7 uninitialized bytes of the kvmalloc()'d slab tail are sent
to the client. When the read length is small the buffer is served from
a general kmalloc slab, so those bytes can be stale kernel-heap
contents, including pointer values -- an information leak usable to
defeat KASLR.
An authenticated client triggers it with a compound request containing a
READ whose returned nbytes is not 8-aligned (for example [READ, CLOSE] with
a 1-byte read).
Zero only the alignment tail after the read, preserving the bulk
no-zeroing optimization of 6b9a2e09d4cc.
Fixes: 6b9a2e09d4cc ("ksmbd: avoid zeroing the read buffer in smb2_read()")
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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smb2_oplock_break_noti() and smb2_lease_break_noti() store a ksmbd_conn
pointer in an async ksmbd_work and then queue that work on ksmbd-io. The
work only increments conn->r_count, which prevents teardown from passing
the pending-request wait after the increment, but it does not pin the
struct ksmbd_conn object.
If connection teardown races with an oplock break notification, the last
conn reference can be dropped before the queued worker finishes. The
worker then uses the freed conn in ksmbd_conn_write() and
ksmbd_conn_r_count_dec().
Take a real conn reference when publishing the conn pointer to the async
work item, and drop it after the notification work has decremented
r_count. Apply the same lifetime rule to lease break notification, which
uses the same work->conn pattern.
Fixes: 3aa660c05924 ("ksmbd: prevent connection release during oplock break notification")
Signed-off-by: Qihang <q.h.hack.winter@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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set_file_allocation_info() converts the client-supplied
FILE_ALLOCATION_INFORMATION::AllocationSize into a 512-byte block
count with:
alloc_blks = (le64_to_cpu(file_alloc_info->AllocationSize) + 511) >> 9;
AllocationSize is a fully client-controlled __le64 field; the only
validation performed by the caller (smb2_set_info_file(), case
FILE_ALLOCATION_INFORMATION) is that the fixed buffer is at least
sizeof(struct smb2_file_alloc_info) == 8 bytes. The value itself is
never range-checked before this arithmetic.
When AllocationSize is close to U64_MAX (e.g. 0xffffffffffffffff),
"AllocationSize + 511" wraps around mod 2^64 to a small number
(0xffffffffffffffff + 511 = 510), so alloc_blks becomes 0. Since any
existing regular file has stat.blocks > 0, the function then takes
the "shrink" branch and calls:
ksmbd_vfs_truncate(work, fp, alloc_blks * 512); /* == 0 */
silently truncating the file to size 0, even though the client asked
to grow the allocation to (what looks like) the maximum possible
size. The trailing "if (size < alloc_blks * 512) i_size_write(inode,
size);" restore is guarded by a comparison that is never true once
alloc_blks == 0, so the truncation is not undone. This lets an
authenticated SMB client that already holds an open handle with
FILE_WRITE_DATA on a file silently truncate that same file to size 0
via a single crafted SET_INFO(FILE_ALLOCATION_INFORMATION) request
advertising a near-U64_MAX AllocationSize, even though the request
asks to grow the file's allocation rather than shrink it. This is a
functional/data-loss bug, not a privilege-boundary
violation: the same client could already truncate the file via
FILE_END_OF_FILE_INFORMATION or a plain write.
Fix it by validating AllocationSize against MAX_LFS_FILESIZE, the
same upper bound the VFS itself uses to reject unrepresentable file
sizes, before doing the "+511" rounding, and rejecting oversized
values with -EINVAL. Bounding AllocationSize to
MAX_LFS_FILESIZE - 511 guarantees the "+511" addition cannot wrap,
and that the subsequent "alloc_blks * 512" values passed to
vfs_fallocate() and ksmbd_vfs_truncate() stay within a representable
loff_t as well.
No legitimate SMB client asks for an allocation size anywhere near
2^64 bytes, so this only rejects a value that was previously
silently misinterpreted as zero.
Runtime-verified on a v6.19 KASAN test stand: sending SET_INFO
(FILE_ALLOCATION_INFORMATION) with AllocationSize = 0xffffffffffffffff
against ksmbd now returns -EINVAL and leaves the target file's size
unchanged, where the unpatched kernel truncated it from 4096 to 0
bytes.
Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org
Signed-off-by: Ibrahim Hashimov <security@auditcode.ai>
Assisted-by: AuditCode-AI:2026.07
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Punching a hole after a large buffered write may leave the range
reported as data. Reproduce it with:
xfs_io -f \
-c "pwrite -b 3m -S 0x61 0 3m" \
-c "fpunch 1m 1m" \
-c "seek -h 0" \
-c "seek -d 1m" \
/mnt/test/repro
Punching 1 MiB at offset 1 MiB should produce:
0 1 MiB 2 MiB 3 MiB
| DATA | HOLE | DATA | EOF
Instead, the entire file is reported as data. SEEK_HOLE(0) returns EOF,
and SEEK_DATA(1M) returns 1M.
This happens because a dirty folio spanning the punched range can be
written back after the punch and refill the hole.
Fix this by flushing and waiting for dirty data in the punched range
before invalidating the page cache and issuing FSCTL_SET_ZERO_DATA.
The xfstests generic/539 pass against Samba/ksmbd with this change.
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Replace EXPORT_SYMBOL_FOR_MODULES() with EXPORT_SYMBOL_IF_KUNIT()
to mark the symbols as visible only if CONFIG_KUNIT is enabled.
Kunit test should import the namespace EXPORTED_FOR_KUNIT_TESTING to
use these marked symbols. This is the standard way for all KUnit
tests.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Replace EXPORT_SYMBOL_FOR_MODULES() with EXPORT_SYMBOL_IF_KUNIT()
to mark the symbols as visible only if CONFIG_KUNIT is enabled.
Kunit test should import the namespace EXPORTED_FOR_KUNIT_TESTING to
use these marked symbols. This is the standard way for all KUnit
tests.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to
responses without data area") restricted the implied bcc[0] length
exception to responses without a data area. However, the overlap
handling in __smb2_calc_size() clears data_length, which can make an
invalid response appear to have no data area and so qualify for the
exception.
Track data area overlap separately and reject such responses before
applying the length compatibility exceptions.
Fixes: 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area")
Cc: stable@vger.kernel.org
Signed-off-by: Shoichiro Miyamoto <shoichiro.miyamoto@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Before this change, xfstests generic/496 was not supported on ksmbd:
generic/496 ... [not run] fallocated swap not supported here
ksmbd handles SetEOF as truncate, so EOF extension alone does not
allocate backing blocks. A fallocated swapfile can therefore still
look sparse to swapon.
Request allocation for EOF-extending fallocate ranges that can be
represented by FILE_ALLOCATION_INFORMATION, and refresh the allocation
state afterwards.
With this change, xfstests generic/496 and generic/701 pass on ksmbd.
However, Samba "strict allocate = no" now exposes the real generic/701
failure: the old pass came from inflated local i_blocks, not from
server allocation. generic/213 also fails in that case because an
oversized allocation request may not return ENOSPC.
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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When a mode 0 fallocate extends EOF from 1G to 2G + 1M, the client
currently sends SetEOF for 2G + 1M. This can make fallocate return
success without allocating the requested range, or allocate extra
space before that range.
For example, on a fresh file:
xfs_io -f \
-c "falloc 0 1G" \
-c "falloc 2G 1M" \
-c "truncate 3G" test
The second fallocate should allocate [2G, 2G + 1M), leaving [1G, 2G)
as a hole.
Before this change, the result depended on the server allocation policy.
With Samba "strict allocate = no", SetEOF could return success without
allocating [2G, 2G + 1M). With "strict allocate = yes":
# filefrag -v test
[0, 1G) allocated
[1G, 2G) allocated unexpectedly
[2G, 2G + 1M) allocated
SMB cannot allocate that arbitrary range, so write zeroes to small
EOF-extending ranges instead. Limit this to 1 MiB to bound the
client-side I/O cost.
With "strict allocate = no", the requested range [2G, 2G + 1M) is
allocated by the writes. With "strict allocate = yes":
# filefrag -v test
[0, 1G) allocated
[1G, 2G) hole
[2G, 2G + 1M) allocated
This fixes the small EOF-extending range case exercised by generic/213.
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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The fallocate emulation allocates a 1 MiB zero-filled buffer even
though each SMB2_write request is limited to SMB2_MAX_BUFFER_SIZE,
which is 64 KiB. A high-order 1 MiB allocation is more likely to
fail on a fragmented system.
Allocate only the smaller of the requested range and SMB2_MAX_BUFFER_SIZE,
and reuse that zero-filled buffer for every write request. Also reject
a successful write that makes no progress to avoid looping indefinitely.
This reduces the contiguous allocation required by fallocate emulation
without changing the written data or range semantics.
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb3_simple_fallocate_range() can skip holes when an allocated range
returned by the server starts before the current fallocate offset. The
skipped hole is not zero-filled, but fallocate still returns success. A
later write to that hole may therefore fail with ENOSPC.
The function queries allocated ranges so that it can preserve existing
contents and write zeroes only into holes. However, the server may return
a range that starts before the current fallocate offset.
For example, assume the fallocate request is [100, 400) and the only
allocated range returned by the server is [0, 200):
Request: [100, 400)
Server range: [ 0, 200) allocated
Correct:
[100, 200) allocated data, skip
[200, 400) hole, zero-fill
Current:
[100, 300) skipped
[300, 400) zero-filled afterwards
The current code adds the full server range length, 200, to the current
offset 100 and moves to 300. As a result, the hole in [200, 300) is
skipped without being zero-filled.
Fix this by advancing only over the part of the allocated range that
overlaps the current fallocate offset. Ignore ranges that end before the
current offset and reject ranges whose end offset overflows.
This also prevents a malformed range length from causing an out-of-bounds
zero-buffer read.
Fixes: 966a3cb7c7db ("cifs: improve fallocate emulation")
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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FSCTL_DUPLICATE_EXTENTS_TO_FILE changes the target file extents on the
server, but the client does not refresh the target AllocationSize/i_blocks.
Callers can observe or use the wrong st_blocks value immediately after the
clone, before a later attribute revalidation corrects it.
For example, create a reflinked file with a leading hole:
xfs_io -f -c "pwrite -S 0x61 0 64k" src
touch dst
chmod 600 dst
xfs_io -c "reflink src 0 1m 64k" dst
mkswap dst
swapon dst
The file still has a hole after mkswap:
/mnt/scratch/dst:
[0..7]: allocated
[8..2047]: hole
[2048..2175]: allocated
The server also reports only the allocated ranges:
server dst size=1114112 blocks=144
but the client reported EOF-derived blocks:
client dst size=1114112 blocks=2176
and swapon succeeded:
swapon_result=success
/mnt/scratch/dst 1.1M 0B -1
So EOF-derived i_blocks can let a sparse reflinked file pass the CIFS
swapfile hole check.
Fix this by querying FILE_ALL_INFORMATION on the target handle after a
successful duplicate extents request. Update i_blocks from AllocationSize
and keep the refreshed target inode attributes valid so a following stat
does not immediately revalidate again.
If the query fails, mark the cached inode attributes stale so a later
getattr can refresh them.
This also fixes the xfstests generic/370 regression introduced by the
i_blocks accounting change, as tested on a Samba "vfs objects = btrfs"
share.
Fixes: 99cd0a6eeb6c ("smb/client: do not account EOF extension as allocation")
Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Currently in smb3_simple_fallocate_range(), a 1 MB buffer is allocated
using kzalloc(). Under heavy memory fragmentation, a contiguous 1 MB block
of physical memory (an order-8 allocation) may not be available,
causing the allocation to fail.
This failure was observed during xfstests generic/013 on a 4GB RAM
test machine running fsstress:
fsstress: page allocation failure: order:8,
mode:0x40dc0(GFP_KERNEL|__GFP_ZERO|__GFP_COMP),
nodemask=(null),cpuset=/,mems_allowed=0
Call Trace:
<TASK>
dump_stack_lvl+0x5d/0x80
warn_alloc+0x163/0x190
__alloc_pages_slowpath.constprop.0+0x71b/0x12f0
__alloc_frozen_pages_noprof+0x2f6/0x340
alloc_pages_mpol+0xb6/0x170
___kmalloc_large_node+0xb3/0xd0
__kmalloc_large_noprof+0x1e/0xc0
smb3_simple_falloc.isra.0+0x62b/0x960
cifs_fallocate+0xed/0x180
vfs_fallocate+0x165/0x3c0
__x64_sys_fallocate+0x48/0xa0
do_syscall_64+0xe1/0x640
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Node 0 Normal: 3375*4kB ... 7*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB
Since this scratch buffer does not require physically contiguous memory,
switch the allocation to kvzalloc(). This retains the performance
benefits of kmalloc() under normal conditions, while gracefully falling
back to virtually contiguous memory when physical allocation fails.
Fixes: 966a3cb7c7db ("cifs: improve fallocate emulation")
Cc: stable@vger.kernel.org
Signed-off-by: Fredric Cover <fredric.cover.lkernel@gmail.com>
Tested-by: Fredric Cover <fredric.cover.lkernel@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Pull smb client fixes from Steve French:
- DFS cache allocation fix
- DFS referral bounds check fix
- Fix absolute symlinks when mounting with POSIX extensions
- Fixes for incorrect nlink returned by fstat
- Fix atime in read completion
- Fix busy dentry on umount
- ioctl_query_info buffer overflow fix
- Two fixes for creating special files with SFU
- Fix mode mask in parse_dacl
- SMB1 is_path_accessible wildcard fix and minor SMB1 cleanup
- smb2_check_message fix
- Debug message improvement
- Minor cleanup
* tag 'v7.2-rc2-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
cifs: Remove CIFSSMBSetPathInfoFB() fallback function
cifs: Fix and improve cifs_is_path_accessible() function
smb: client: mask server-provided mode to 07777 in modefromsid
cifs: Show reason why autodisabling serverino support
smb/client: fix incorrect nlink returned by fstat()
smb/client: zero-initialize stack-allocated cifs_open_info_data
smb/client: pass cifs_open_info_data to SMB2_open()
smb/client: use stack-allocated smb2_file_all_info in smb3_query_mf_symlink()
smb: client: fix overflow in passthrough ioctl bounds check
smb: client: fix busy dentry warning on unmount after DIO
cifs: Fix support for creating SFU fifo
cifs: Fix support for creating SFU socket
smb: client: fix atime clamp check in read completion
cifs: validate DFS referral string offsets
smb: client: use GFP_KERNEL for DFS cache allocations
smb: client: restrict implied bcc[0] exemption to responses without data area
smb: client: preserve leading slash for POSIX absolute symlink targets
smb: client: refactor cifs_revalidate_mapping() to use clear_and_wake_up_bit()
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This fallback function CIFSSMBSetPathInfoFB() is called only from
CIFSSMBSetPathInfo() function. CIFSSMBSetPathInfo() is used in
smb_set_file_info() which contains all required fallback code, including
fallback via filehandle, since commit f122121796f9 ("cifs: Fix changing
times and read-only attr over SMB1 smb_set_file_info() function") and
commit 92210ccd877b ("cifs: Add fallback code path for cifs_mkdir_setinfo()").
So the CIFSSMBSetPathInfoFB() is just code duplication, which is not needed
anymore. Therefore remove it.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Do not call SMBQueryInformation() command for path with SMB wildcard
characters on non-UNICODE connection because server expands wildcards.
Function cifs_is_path_accessible() needs to check if the real path exists
and must not expand wildcard characters.
Do not dynamically allocate memory for small FILE_ALL_INFO structure and
instead allocate it on the stack. This structure is allocated on stack by
all other functions.
When CAP_NT_SMBS was not negotiated then do not issue CIFSSMBQPathInfo()
command. This command returns failure by non-NT Win9x SMB servers, so there
is no need try it. The purpose of cifs_is_path_accessible() function is
just to check if the path is accessible, so SMBQueryInformation() for old
servers is enough.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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When modefromsid is active, parse_dacl() applies the server-provided
sub_auth[2] value from the NFS mode SID to cf_mode without masking to
07777. Apply the correct masking, same as in the read path.
Fixes: e2f8fbfb8d09c ("cifs: get mode bits from special sid on stat")
Signed-off-by: Norbert Manthey <nmanthey@amazon.de>
Assisted-by: Kiro:claude-opus-4.6
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
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Extend cifs_autodisable_serverino() function to print also text message why
the function was called.
The text message is printed just once for mount then autodisabling
serverino support. Once the serverino support is disabled for mount it will
not be re-enabled. So those text messages do not cause flooding logs.
This change allows to debug issues why cifs.ko decide to turn off server
inode number support and hence disable support for detection of hardlinks.
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Reproducer:
1. mount -t cifs //${server_ip}/export /mnt
2. touch /mnt/file1; ln /mnt/file1 /mnt/file2; ln /mnt/file1 /mnt/file3
3. C program: int fd = open("/mnt/file1", O_RDONLY);
4. C program: struct stat stbuf; fstat(fd, &stbuf);
stbuf.st_nlink is always 1, should be 3
Setting `unknown_nlink` to true in `SMB2_open()` triggers the
`CIFS_FATTR_UNKNOWN_NLINK` flag in `cifs_open_info_to_fattr()`,
which safely preserves the existing i_nlink in
`cifs_nlink_fattr_to_inode()`.
See the detailed procedure below:
path_openat
open_last_lookups
lookup_open
atomic_open
cifs_atomic_open // dir->i_op->atomic_open
cifs_lookup
cifs_get_inode_info
cifs_get_fattr
smb2_query_path_info // server->ops->query_path_info
smb2_compound_op
SMB2_open_init
case SMB2_OP_QUERY_INFO
SMB2_query_info_init(FILE_ALL_INFORMATION,)
cifs_open_info_to_fattr
fattr->cf_nlink = le32_to_cpu(info->NumberOfLinks)
update_inode_info
cifs_iget
cifs_fattr_to_inode
cifs_nlink_fattr_to_inode
set_nlink(inode, fattr->cf_nlink)
do_open
vfs_open
do_dentry_open
cifs_open
cifs_nt_open
smb2_open_file // server->ops->open
SMB2_open
buf->unknown_nlink = true
cifs_get_inode_info
cifs_get_fattr
cifs_open_info_to_fattr
if (data->unknown_nlink) // true
fattr->cf_flags |= CIFS_FATTR_UNKNOWN_NLINK
update_inode_info
cifs_fattr_to_inode
cifs_nlink_fattr_to_inode
if (fattr->cf_flags & CIFS_FATTR_UNKNOWN_NLINK) // true
return // do not modify nlink
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Stack-allocated cifs_open_info_data may contain random data.
This can make some fields have wrong value if they are not set later.
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Let SMB2_open() fill the smb2_file_all_info embedded in cifs_open_info_data
directly. This removes the temporary smb2_file_all_info copy in
smb2_open_file().
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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SMB2_open() only fills the fixed fields, so a stack-allocated
smb2_file_all_info is sufficient here.
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb2_ioctl_query_info() validates the PASSTHRU_FSCTL response payload
before copying it to userspace.
The payload offset and length both come from 32-bit fields. The bounds
check currently adds OutputOffset and qi.input_buffer_length directly, so
the addition can wrap in 32-bit arithmetic before the result is compared
against the response buffer length.
A malicious server can use a large OutputOffset and a small OutputCount
to make the wrapped sum pass the bounds check. The later copy_to_user()
then reads from io_rsp + OutputOffset, outside the response buffer.
Use size_add() for the offset plus length check so overflow is treated as
out of bounds.
Fixes: 2b1116bbe898 ("CIFS: Use common error handling code in smb2_ioctl_query_info()")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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Commit c68337442f03 ("cifs: Fix busy dentry used after unmounting") fixed
the issue in cifs where deferred close of a file led to a dentry reference
count not being released in umount, by flushing deferredclose_wq in
cifs_kill_sb() to solve it.
However, the cifs DIO path suffers from the same busy-dentry problem caused
by a delayed dentry reference-count release:
[dio] [cifsd] [close + umount]
netfs_unbuffered_write_iter_locked
...
cifs_demultiplex_thread
netfs_unbuffered_write
cifs_issue_write
netfs_wait_for_in_progress_stream [1]
...
netfs_write_subrequest_terminated
netfs_subreq_clear_in_progress
netfs_wake_collector // wake [1]
netfs_put_subrequest
netfs_put_request
queue_work(system_dfl_wq, xxx) [2]
// dio write return cifs_close
_cifsFileInfo_put
// cfile->count 2->1
--cfile->count [3]
// umount
cifs_kill_sb
kill_anon_super
// warning triggered!
shrink_dcache_for_umount [4]
[system_dfl_wq] [5]
netfs_free_request
...
_cifsFileInfo_put
// cfile->count 1->0
--cfile->count
queue_work(fileinfo_put_wq, xxx)
[fileinfo_put_wq] [6]
cifsFileInfo_put_work
cifsFileInfo_put_final
dput
If the umount path is triggered before [5], it results warning:
BUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test} still in use (1)
[unmount of cifs cifs]
The existing per-inode ictx->io_count wait in cifs_evict_inode() does not
help: it lives in the inode eviction path, which runs after
shrink_dcache_for_umount() has already warned about the busy dentries.
Fix it by adding a per-superblock outstanding-rreq counter that is
incremented in cifs_init_request() and decremented in cifs_free_request().
In cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach
0 - which guarantees that all cleanup_work for this sb have run and thus
all relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq.
Then drain the workqueue so the dentry refs are dropped.
This is a targeted wait, not a flush of the system-wide system_dfl_wq.
Fixes: 340cea84f691c ("cifs: open files should not hold ref on superblock")
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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SFU fifos are natively supported (created and recognized) at least by:
- Microsoft POSIX subsystem
- OpenNT/Interix subsystem
- Microsoft SFU (Windows Services for UNIX)
- Microsoft SUA (Subsystem for UNIX-based Applications)
- Windows NFS server (up to the Windows Server 2008 R2)
Windows NFS server since Windows Server 2012 uses new reparse point format
for storing new fifos, but still can recognize this old format (also in the
latest Windows Server 2022 version).
SFU-style fifo is empty regular file which has system attribute set.
These SFU-style fifos are already recognized by Linux SMB client.
But Linux SMB client is currently creating new SFU fifos in different
format which is not compatible with all those SFU-style consumers. Fix this
by creating new fifos in correct SFU format which would be recognized by
all those applications and also by existing Linux SMB clients.
This change affects only creating new fifos when mount option -o sfu is used.
Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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SFU sockets are natively supported by Interix 3.0 subsystem and also by
later versions. It is part of Microsoft SFU (Windows Services for UNIX) and
Microsoft SUA (Subsystem for UNIX-based Applications). They can be created
and existing (stored on local disk or remote SMB share) can be recognized.
SFU sockets are recognized also by NFS server included in Windows Server.
Windows NFS server versions since Windows Server 2012 uses new reparse
point format for storing new sockets, but still can recognize this old
format (also in the latest Windows Server 2022 version).
SFU-style socket is a regular file which has system attribute set and
content of the file is one zero byte.
These SFU-style sockets are already recognized by Linux SMB client.
But Linux SMB client is currently creating new SFU socket in different
format which is not compatible with all those SFU applications. Fix this by
creating new sockets in correct SFU format which would be recognized by all
SFU, SUA, NFS and existing Linux SMB clients.
This change affects only creating new sockets when mount option -o sfu is used.
Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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cifs_rreq_done() updates the inode atime to current_time(inode) after a
netfs read. It then preserves the CIFS rule that atime should not be
older than mtime, because some applications break if atime is less than
mtime. That rule only requires clamping when atime < mtime.
The current check uses the raw non-zero result of timespec64_compare().
It therefore takes the clamp path for both atime < mtime and
atime > mtime. The latter is the normal case when reading an older file:
the newly recorded atime is newer than the file mtime. The completion
handler then immediately moves atime back to mtime, losing the access
time that was just recorded. Userspace tools that rely on atime, such as
stat, find -atime, backup tools or cold-data classifiers, can therefore
see a recently read CIFS file as not recently accessed.
This is easy to miss because the bug is silent: read I/O still succeeds,
no error is reported, and many systems either do not check atime after
reads or mount with policies such as relatime/noatime. It becomes
visible when a CIFS file has an mtime older than the current time, the
file is read, and the local inode atime is inspected before a later
revalidation replaces the cached timestamps.
Clamp only when atime is actually older than mtime. This matches the
same atime/mtime rule used when applying CIFS inode attributes.
Fixes: 69c3c023af25 ("cifs: Implement netfslib hooks")
Cc: stable@vger.kernel.org
Signed-off-by: Xu Rao <raoxu@uniontech.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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parse_dfs_referrals() validates that the response header and referral
array fit in the received buffer, but each referral also contains string
offsets supplied by the server.
Those offsets are used to compute the DfsPath and NetworkAddress string
pointers without checking whether they still point inside the response
buffer. A malformed referral can therefore make the computed pointer
exceed the end of the buffer. The resulting negative max_len is then
passed to cifs_strndup_from_utf16(), and the non-Unicode path forwards it
to kstrndup() as a size_t, allowing strnlen() to read out of bounds.
Validate each string offset before deriving the string pointer.
Fixes: 4ecce920e13a ("CIFS: move DFS response parsing out of SMB1 code")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
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In dfs_cache.c, the helper functions alloc_target(), setup_referral(),
and update_cache_entry_locked() currently utilize GFP_ATOMIC to
allocate memory.
However, all of these functions are executed in sleepable conditions.
Use GFP_KERNEL instead, to reduce the risk of allocation failure and
stop putting unnecessary pressure on emergency memory pools in
low-memory scenarios.
Signed-off-by: Fredric Cover <fredric.cover.lkernel@gmail.com>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
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smb2_check_message() has a long-standing quirk that accepts a response
whose calculated length is one byte larger than the bytes actually
received ("server can return one byte more due to implied bcc[0]").
This was introduced to accommodate servers that omit the trailing bcc[0]
overlap byte when no data area is present.
However, the exemption is applied unconditionally, regardless of whether
the command actually carries a data area (has_smb2_data_area[]). When a
response with a data area is subject to the +1 exemption, the reported
data can extend one byte beyond the bytes actually received, yet
smb2_check_message() still accepts it. The subsequent decoder then reads
past the end of the receive buffer. This is reachable during NEGOTIATE
and SESSION_SETUP, before the session is established.
The resulting out-of-bounds reads are visible under KASAN when mounting
against a non-conforming server; both the SPNEGO/negTokenInit and the
NTLMSSP challenge decoders are affected:
BUG: KASAN: slab-out-of-bounds in asn1_ber_decoder+0x16a7/0x1b00
Read of size 1 at addr ffff8880084d67c0 by task mount.cifs/81
CPU: 1 UID: 0 PID: 81 Comm: mount.cifs Not tainted 7.1.0-rc6 #1
Call Trace:
<TASK>
dump_stack_lvl+0x4e/0x70
print_report+0x157/0x4c9
kasan_report+0xce/0x100
asn1_ber_decoder+0x16a7/0x1b00
decode_negTokenInit+0x19/0x30
SMB2_negotiate+0x31d9/0x4c90
cifs_negotiate_protocol+0x1f2/0x3f0
cifs_get_smb_ses+0x93f/0x17e0
cifs_mount_get_session+0x7f/0x3a0
cifs_mount+0xb4/0xcf0
cifs_smb3_do_mount+0x23a/0x1500
smb3_get_tree+0x3b0/0x630
vfs_get_tree+0x82/0x2d0
fc_mount+0x10/0x1b0
path_mount+0x50d/0x1de0
__x64_sys_mount+0x20b/0x270
do_syscall_64+0xee/0x590
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Allocated by task 85:
kmem_cache_alloc_noprof+0x106/0x380
mempool_alloc_noprof+0x116/0x1e0
cifs_small_buf_get+0x31/0x80
allocate_buffers+0x10d/0x2b0
cifs_demultiplex_thread+0x1d5/0x1d50
kthread+0x2c6/0x390
ret_from_fork+0x36e/0x5a0
ret_from_fork_asm+0x1a/0x30
The buggy address is located 0 bytes to the right of
allocated 448-byte region [ffff8880084d6600, ffff8880084d67c0)
which belongs to the cache cifs_small_rq of size 448
BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x36/0x50
Read of size 329 at addr ffff88800726c678 by task mount.cifs/89
CPU: 0 UID: 0 PID: 89 Comm: mount.cifs Tainted: G B 7.1.0-rc6 #1
Call Trace:
<TASK>
dump_stack_lvl+0x4e/0x70
print_report+0x157/0x4c9
kasan_report+0xce/0x100
kasan_check_range+0x10f/0x1e0
__asan_memcpy+0x23/0x60
kmemdup_noprof+0x36/0x50
decode_ntlmssp_challenge+0x457/0x680
SMB2_sess_auth_rawntlmssp_negotiate+0x6f0/0xcb0
SMB2_sess_setup+0x219/0x4f0
cifs_setup_session+0x248/0xaf0
cifs_get_smb_ses+0xf79/0x17e0
cifs_mount_get_session+0x7f/0x3a0
cifs_mount+0xb4/0xcf0
cifs_smb3_do_mount+0x23a/0x1500
smb3_get_tree+0x3b0/0x630
vfs_get_tree+0x82/0x2d0
fc_mount+0x10/0x1b0
path_mount+0x50d/0x1de0
__x64_sys_mount+0x20b/0x270
do_syscall_64+0xee/0x590
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Allocated by task 93:
kmem_cache_alloc_noprof+0x106/0x380
mempool_alloc_noprof+0x116/0x1e0
cifs_small_buf_get+0x31/0x80
allocate_buffers+0x10d/0x2b0
cifs_demultiplex_thread+0x1d5/0x1d50
kthread+0x2c6/0x390
ret_from_fork+0x36e/0x5a0
ret_from_fork_asm+0x1a/0x30
The buggy address is located 120 bytes inside of
allocated 448-byte region [ffff88800726c600, ffff88800726c7c0)
whi |
