linux-toradex.git/fs/ceph, branch master

ceph: use the mount idmap for the owner checks in the SET_LAYOUT ioctls

2026-08-12T19:21:41+00:00

ceph_ioctl_set_layout() and ceph_ioctl_set_layout_policy() call
inode_owner_or_capable() with &nop_mnt_idmap instead of the idmap of the
mount the ioctl was issued on.

CephFS supports idmapped mounts (FS_ALLOW_IDMAP), so on such a mount this
compares the caller's fsuid against the unmapped on-disk owner rather than
the mapped owner: the actual owner can be wrongly denied with -EACCES and
an unrelated caller wrongly allowed.  Both functions already have the
struct file, so use file_mnt_idmap(file) instead.

Cc: stable@vger.kernel.org
Fixes: cee38bbf5556 ("ceph: add owner/capability checks for CEPH_IOC_SET_LAYOUT*")
Signed-off-by: Zhan Xusheng 
Reviewed-by: Xiubo Li 
Reviewed-by: Alex Markuze 
Signed-off-by: Ilya Dryomov

ceph: fix MDS random selection readiness predicate

2026-08-12T19:21:41+00:00

CEPH_MDS_IS_READY() is parsed so that the ternary expression can
return true for an MDS entry with state 0 when it is not laggy. This
allows the random selector to choose a down/DNE rank.

Group the ternary expression under the state check so zero-state ranks
are not treated as ready.

Cc: stable@vger.kernel.org
Fixes: b38c9eb4757d ("ceph: add possible_max_rank and make the code more readable")
Link: https://tracker.ceph.com/issues/78648
Signed-off-by: Yiming Zhu 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov

ceph: avoid fs reclaim while using current->journal_info

2026-07-23T18:29:42+00:00

handle_reply() stores a `ceph_mds_request` pointer in
`current->journal_info` while filling the inode and dentry cache from
an MDS reply.

An allocation in this section can enter direct reclaim and prune
dentries from another filesystem.  If this dirties an ext4 inode, ext4
starts a JBD2 transaction.  JBD2 interprets the Ceph request in
`current->journal_info` as a journal handle and dereferences the
request's `r_tid` as `h_transaction`, causing a kernel crash, e.g.:

 Unable to handle kernel paging request at virtual address 00000000077b4818
 [...]
 Internal error: Oops: 0000000096000004 [#1]  SMP
 Modules linked in:
 CPU: 6 UID: 0 PID: 2699135 Comm: kworker/6:3 Tainted: G        W           6.18.38-i3 #1113 NONE
 [...]
 Workqueue: ceph-msgr ceph_con_workfn
 pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
 pc : jbd2__journal_start+0x2c/0x208
 lr : __ext4_journal_start_sb+0x100/0x178
 [...]
 Call trace:
  jbd2__journal_start+0x2c/0x208 (P)
  __ext4_journal_start_sb+0x100/0x178
  ext4_dirty_inode+0x3c/0x90
  __mark_inode_dirty+0x58/0x400
  iput.part.0+0x2b0/0x370
  iput+0x18/0x30
  dentry_unlink_inode+0xc0/0x158
  __dentry_kill+0x80/0x250
  shrink_dentry_list+0x90/0x130
  prune_dcache_sb+0x60/0x98
  super_cache_scan+0xe8/0x190
  do_shrink_slab+0x174/0x388
  shrink_slab+0xd8/0x4c0
  shrink_node+0x31c/0x908
  do_try_to_free_pages+0xd0/0x508
  try_to_free_pages+0x11c/0x238
  __alloc_frozen_pages_noprof+0x4d0/0xdd0
  __folio_alloc_noprof+0x18/0x70
  __filemap_get_folio+0x248/0x440
  ceph_readdir_prepopulate+0x570/0x9e8
  mds_dispatch+0x1424/0x1ba0
  ceph_con_process_message+0x74/0xa0
  ceph_con_v1_try_read+0x3a0/0x1510
  ceph_con_workfn+0x260/0x460

Enter a scoped NOFS allocation context and leave it after clearing
`journal_info`.  This prevents filesystem reclaim from recursing into
another filesystem while the field contains Ceph-private data.

Cc: stable@vger.kernel.org
Fixes: 315f24088048 ("ceph: fix security xattr deadlock")
Signed-off-by: Max Kellermann 
Reviewed-by: Viacheslav Dubeyko 
Reviewed-by: Xiubo Li 
Signed-off-by: Ilya Dryomov

ceph: add owner/capability checks for CEPH_IOC_SET_LAYOUT*

2026-07-23T18:29:42+00:00

These permission checks were already missing in the initial
impementation of these ioctls.  This Ceph allows any user who owns a
file descriptor to manipulate the layout of any file, even if they
don't have write permissions.

It might be a good idea to guard other ioctls with permission checks
as well or even disallow regular users (even if they own the file) to
manipulate layout settings completely, as this may be abused to DoS
the Ceph servers, but right now, I find it most urgent to have setter
checks at all.

Cc: stable@vger.kernel.org
Fixes: 8f4e91dee2a2 ("ceph: ioctls")
Signed-off-by: Max Kellermann 
Reviewed-by: Xiubo Li 
Signed-off-by: Ilya Dryomov

ceph: fix hanging __ceph_get_caps() with stale mds_wanted

2026-07-23T18:29:42+00:00

A reader can hang forever in __ceph_get_caps() when the client no
longer holds `FILE_RD`, but local cap state still says that the
capability is already wanted (via `mds_wanted`).

One way to trigger this is through MDS cap revocation.  If another
client performs a conflicting operation, the MDS can revoke `FILE_RD`
from the reader; the next read then has to reacquire `FILE_RD`.  If
the cap update that should request `FILE_RD` never reaches the MDS
after `cap->mds_wanted` was raised, the reader is left holding only
non-file caps while local `mds_wanted` still includes the file read
caps.

In that state, try_get_cap_refs() sees `need <= mds_wanted` and
returns 0, so __ceph_get_caps() just waits on `i_cap_wq`.  If the cap
update that was supposed to request `FILE_RD never reaches the MDS
after `cap->mds_wanted was` raised, no further request is sent and the
waiter can sleep indefinitely until unrelated cap traffic happens to
wake it up.

The ordering issue is that `cap->mds_wanted` is updated in
__prep_cap() before the `CEPH_MSG_CLIENT_CAPS message` is actually
queued for send.  That makes one field serve two different meanings at
once: what this client wants, and what the client believes the MDS
already knows it wants.

A proper fix would be to split those states and track whether a cap
update is actually in flight or has been observed by the MDS.
However, simply moving the `cap->mds_wanted assignment` later would
not be sufficient: queueing the message in the messenger does not
guarantee that the MDS processed that specific wanted set, and
reconnect or message loss can still invalidate that assumption.
Fixing that properly would require a larger rework of the cap state
machine.

To allow simpler backports to stable kernels, this patch implements a
simpler workaround:

- stop waiting forever in __ceph_get_caps(); after a bounded wait,
  fall back to the renew path

- make ceph_renew_caps() issue a synchronous `OPEN` request whenever
  the inode still does not actually hold the wanted caps, instead of
  only calling ceph_check_caps()

The extra issued-vs-wanted check in ceph_renew_caps() is necessary
because the previous test only checked whether the inode still had any
real caps at all.  That is not enough after revocation: the client can
still hold something like `pLs` and yet be missing `FILE_RD`
completely.  In that case, falling back to ceph_check_caps() is not
sufficient, because it still trusts `cap->mds_wanted` and may resend
nothing.  By requiring `(issued & wanted) == wanted` before taking the
asynchronous path, the code only uses ceph_check_caps() when the
`wanted caps` are already actually issued.  Otherwise, it sends the
synchronous `OPEN` renew.

This preserves the existing asynchronous fast path when the wanted
caps are already issued, avoids changing cap-state semantics, and
fixes the hang by guaranteeing that a stalled waiter eventually
retries through a path that does not rely on the stale `mds_wanted`
state.

[ idryomov: move CEPH_GET_CAPS_WAIT_TIMEOUT from libceph.h to
  mds_client.h, formatting ]

Cc: stable@vger.kernel.org
Fixes: 0a454bdd501a ("ceph: reorganize __send_cap for less spinlock abuse")
Signed-off-by: Max Kellermann 
Reviewed-by: Alex Markuze 
Signed-off-by: Ilya Dryomov

ceph: fix refcount leak in ceph_readdir()

2026-07-23T18:29:41+00:00

The ceph_readdir() function allocates a ceph_mds_request via
ceph_mdsc_create_request() and stores it in dfi->last_readdir. In
the directory entry processing loop, if the entry's offset is less
than ctx->pos or if the inode pointer is unexpectedly NULL, the
function returns -EIO without releasing the reference held by
dfi->last_readdir, causing a refcount leak.

Fix this by adding ceph_mdsc_put_request(dfi->last_readdir) before
returning on these error paths. Also set dfi->last_readdir to NULL
for safety, matching the cleanup done at the normal exit.

Cc: stable@vger.kernel.org
Fixes: af9ffa6df7e3 ("ceph: add support to readdir for encrypted names")
Signed-off-by: WenTao Liang 
Reviewed-by: Viacheslav Dubeyko 
Reviewed-by: Alex Markuze 
Signed-off-by: Ilya Dryomov

ceph: fix writeback_count leak in write_folio_nounlock()

2026-07-23T18:29:41+00:00

write_folio_nounlock() increments fsc->writeback_count to track
in-flight writeback operations. On several error paths where the
function returns early (folio lookup failure, snapshot context
allocation failure, and writepages submission failure), the function
returns without calling atomic_long_dec_return() to decrement the
counter.

Each leaked increment keeps the counter above zero, which can prevent
the filesystem from cleanly unmounting or suspending writes.

Add atomic_long_dec_return() calls on all error paths that currently
return without decrementing the counter.

Cc: stable@vger.kernel.org
Fixes: d55207717ded ("ceph: add encryption support to writepage and writepages")
Signed-off-by: Wentao Liang 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov

ceph: fix pre-auth out-of-bounds read on snaptrace in ceph_handle_caps()

2026-07-23T18:29:41+00:00

ceph_handle_caps() reads snap_trace_len from the wire-format
ceph_mds_caps header and uses it unconditionally to build a fake
end pointer (snaptrace + snaptrace_len) that is later handed to
ceph_update_snap_trace() in the CEPH_CAP_OP_IMPORT case:

    snaptrace     = h + 1;
    snaptrace_len = le32_to_cpu(h->snap_trace_len);
    p             = snaptrace + snaptrace_len;
    ...
    case CEPH_CAP_OP_IMPORT:
        if (snaptrace_len) {
            ...
            if (ceph_update_snap_trace(mdsc, snaptrace,
                                       snaptrace + snaptrace_len,
                                       false, &realm)) { ... }

ceph_update_snap_trace() then decodes a struct ceph_mds_snap_realm
from snaptrace using ceph_decode_need(&p, e, sizeof(*ri), bad)
with the attacker-supplied fake end e == snaptrace + snaptrace_len.
With snaptrace_len == 0xFFFFFFFF the bound check is trivially
satisfied, ri = p reads sizeof(struct ceph_mds_snap_realm) past
the legitimate msg->front buffer, and ri->num_snaps /
ri->num_prior_parent_snaps then drive further out-of-bounds
reads of the encoded snap arrays.

The eleven msg_version >= 2 .. msg_version >= 12 decoder blocks
above the op switch each catch this OOB through their
ceph_decode_*_safe() / ceph_decode_need() helpers, but they sit
behind a hdr.version-gated if, so a malicious or compromised
MDS that sets msg->hdr.version = 1 reaches the IMPORT path with
no version-gated decoder having validated snap_trace_len. The
shape has been present since ceph_handle_caps() was introduced.

Validate snap_trace_len against the message front buffer before
consuming it, using the canonical ceph_decode_need() / ceph_has_room()
helper.  The helper bounds the length with subtraction (n <= end - p,
guarded by end >= p) rather than pointer addition, so it is wrap-safe
for the attacker-controlled u32 length on 32-bit builds where
p + snap_trace_len could overflow the address space.  This matches the
rest of the ceph decode path (e.g. the pool_ns_len check a few lines
below), and the existing goto bad cleanup already covers this exit
path.

Cc: stable@vger.kernel.org
Fixes: a8599bd821d0 ("ceph: capability management")
Signed-off-by: Bryam Vargas 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov

Merge tag 'ceph-for-7.2-rc1' of https://github.com/ceph/ceph-client

2026-06-26T23:15:53+00:00

Pull ceph updates from Ilya Dryomov:
 "This adds support for manual client session reset in CephFS, allowing
  operators to get out of tricky livelock situations involving caps and
  file locks without evicting the problematic client instance on the MDS
  side or rebooting the client node both of which can be disruptive"

* tag 'ceph-for-7.2-rc1' of https://github.com/ceph/ceph-client:
  ceph: add manual reset debugfs control and tracepoints
  ceph: add client reset state machine and session teardown
  ceph: add diagnostic timeout loop to wait_caps_flush()
  ceph: harden send_mds_reconnect and handle active-MDS peer reset
  ceph: use proper endian conversion for flock_len in reconnect
  ceph: convert inode flags to named bit positions and atomic bitops
  rbd: switch to dynamic root device

ceph: add manual reset debugfs control and tracepoints

2026-06-22T20:45:05+00:00

Add the debugfs and trace plumbing used to trigger and observe
manual client reset.

The reset interface exposes a trigger file for operator-initiated
reset and a status file for tracking the most recent run.  The
tracepoints record scheduling, completion, and blocked caller
behavior so reset progress can be diagnosed from the client side.

debugfs layout under /sys/kernel/debug/ceph//reset/:
  trigger - write to initiate a manual reset
  status  - read to see the most recent reset result

The reset directory is cleaned up via debugfs_remove_recursive()
on the parent, so individual file dentries are not stored.

Tracepoints:
  ceph_client_reset_schedule  - reset queued
  ceph_client_reset_complete  - reset finished (success or failure)
  ceph_client_reset_blocked   - caller blocked waiting for reset
  ceph_client_reset_unblocked - caller unblocked after reset

All tracepoints use a null-safe access for monc.auth->global_id
to guard against early-init or late-teardown edge cases.

Signed-off-by: Alex Markuze 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Viacheslav Dubeyko 
Signed-off-by: Ilya Dryomov