file_hash() digests the first LOCKD_FH_HASH_SIZE bytes of
nfs_fh.data when bucketing nlm_files[], independent of fh.size.
Commit 3de744ee4e45 ("lockd: Use xdrgen XDR functions for the
NLMv4 TEST procedure") set .pc_argzero to zero for the converted
procedures and moved file-handle population into
nlm4svc_lookup_file(), which copies only xdr_lock->fh.len bytes
into lock->fh.data.

When an NLMv4 client presents a file handle shorter than
LOCKD_FH_HASH_SIZE, bytes fh.len..31 retain whatever the argument
buffer held from an earlier request.  The same wire handle then
hashes to different buckets across calls; nlm_lookup_file() misses
the existing nlm_file entry, and lock-state lookups fail.

Zero only the tail bytes that file_hash() would otherwise consume.
Handles of LOCKD_FH_HASH_SIZE or larger already populate every byte
that file_hash() reads.

Reported-by: Jeff Layton <jlayton@kernel.org>
Closes: https://lore.kernel.org/r/5229a9746d723a3f830120c0b966510f75badfc2.camel@kernel.org
Fixes: 3de744ee4e45 ("lockd: Use xdrgen XDR functions for the NLMv4 TEST procedure")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

The cached-file path in nlm_lookup_file() reaches the found: label
unconditionally, even when nlm_do_fopen() fails. At that label
*result and file->f_count are updated before the error is returned.
The wrappers nlm3svc_lookup_file() and nlm4svc_lookup_file() then
bail out of their switch without copying *result back to their
caller, so the proc handler's local nlm_file pointer remains NULL
and the cleanup path skips nlm_release_file(). The f_count
increment is never released, and nlm_traverse_files() can no
longer reap the file because its refcount never returns to zero
between requests.

Short-circuit the cached path so neither *result nor f_count is
touched when nlm_do_fopen() fails on a hashed nlm_file.

Fixes: 7f024fcd5c97 ("Keep read and write fds with each nlm_file")
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

A client can repeatedly drive nlm_do_fopen() failures by presenting
file handles that the underlying export rejects. After kzalloc_obj()
succeeds in nlm_lookup_file(), the freshly allocated nlm_file is not
yet inserted into nlm_files[]. The nlm_do_fopen() failure path jumps
to out_unlock, which releases nlm_file_mutex and returns without
freeing the allocation, so each failure leaks one nlm_file.

Route the failure through out_free so kfree() runs before the
function returns.

Fixes: 7f024fcd5c97 ("Keep read and write fds with each nlm_file")
Cc: stable@vger.kernel.org
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

A subsequent patch will convert fs/lockd/svcproc.c to use
machine-generated XDR encoding and decoding functions in a
manner similar to fs/lockd/svc4proc.c. Machine-generated
types derived from the NLM specification will conflict with
the internal types of the same name.

Rename the internal struct nlm_lock type to lockd_lock to
avoid such naming conflicts.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Pull nfsd fixes from Chuck Lever:
 "Regressions:

   - Tighten bounds checking for sunrpc cache hash tables

   - Don't report key material in the ftrace log

  Stable fix:

   - Fix lockd's implementation of the NLM TEST procedure"

* tag 'nfsd-7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  lockd: fix TEST handling when not all permissions are available.
  NFSD: Report whether fh_key was actually updated
  sunrpc: prevent out-of-bounds read in __cache_seq_start()

The F_GETLK fcntl can work with either read access or write access or
both.  It can query F_RDLCK and F_WRLCK locks in either case.

However lockd currently treats F_GETLK similar to F_SETLK in that read
access is required to query an F_RDLCK lock and write access is required
to query a F_WRLCK lock.

This is wrong and can cause problems - e.g.  when qemu accesses a
read-only (e.g. iso) filesystem image over NFS (though why it queries
if it can get a write lock - I don't know.  But it does, and this works
with local filesystems).

So we need TEST requests to be handled differently.  To do this:

- change nlm_do_fopen() to accept O_RDWR as a mode and in that case
  succeed if either a O_RDONLY or O_WRONLY file can be opened.
- change nlm_lookup_file() to accept a mode argument from caller,
  instead of deducing base on lock time, and pass that on to nlm_do_fopen()
- change nlm4svc_retrieve_args() and nlmsvc_retrieve_args() to detect
  TEST requests and pass O_RDWR as a mode to nlm_lookup_file, passing
  the same mode as before for other requests.  Also set
   lock->fl.c.flc_file to whichever file is available for TEST requests.
- change nlmsvc_testlock() to also not calculate the mode, but to use
  whatever was stored in lock->fl.c.flc_file.

This behaviour of lockd - requesting O_WRONLY access to TEST for
exclusive locks - has been present at least since git history began.
However it was hidden until recently because knfsd ignored the access
requested by lockd and required only READ access for all locking
requests (unless the underlying filesystem provided an f_op->open
function which checked access permissions).

The commit mentioned in Fixes: below changed nfsd_permission() to NOT
override the access request for LOCK requests and this exposed the bug
that we are now fixing.

Note that there is another issue that this patch does not address.
The flock(.., LOCK_EX) call is permitted on a read-only file descriptor.
Linux NFS maps this to NLM locking as whole-file byte-range locks.
nfsd will see this as though it were fcntl( F_SETLK (F_WRLCK)) and will
now require write access, which it might not be able to get.
It is not clear if this is a problem in practice, or what the best
solution might be.  So no attempt is made to address it.

Reported-by: Tj <tj.iam.tj@proton.me>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1128861
Fixes: 4cc9b9f2bf4d ("nfsd: refine and rename NFSD_MAY_LOCK")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Pull nfsd updates from Chuck Lever:

 - filehandle signing to defend against filehandle-guessing attacks
   (Benjamin Coddington)

   The server now appends a SipHash-2-4 MAC to each filehandle when
   the new "sign_fh" export option is enabled. NFSD then verifies
   filehandles received from clients against the expected MAC;
   mismatches return NFS error STALE

 - convert the entire NLMv4 server-side XDR layer from hand-written C to
   xdrgen-generated code, spanning roughly thirty patches (Chuck Lever)

   XDR functions are generally boilerplate code and are easy to get
   wrong. The goals of this conversion are improved memory safety, lower
   maintenance burden, and groundwork for eventual Rust code generation
   for these functions.

 - improve pNFS block/SCSI layout robustness with two related changes
   (Dai Ngo)

   SCSI persistent reservation fencing is now tracked per client and
   per device via an xarray, to avoid both redundant preempt operations
   on devices already fenced and a potential NFSD deadlock when all nfsd
   threads are waiting for a layout return.

 - scalability and infrastructure improvements

   Sincere thanks to all contributors, reviewers, testers, and bug
   reporters who participated in the v7.1 NFSD development cycle.

* tag 'nfsd-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux: (83 commits)
  NFSD: Docs: clean up pnfs server timeout docs
  nfsd: fix comment typo in nfsxdr
  nfsd: fix comment typo in nfs3xdr
  NFSD: convert callback RPC program to per-net namespace
  NFSD: use per-operation statidx for callback procedures
  svcrdma: Use contiguous pages for RDMA Read sink buffers
  SUNRPC: Add svc_rqst_page_release() helper
  SUNRPC: xdr.h: fix all kernel-doc warnings
  svcrdma: Factor out WR chain linking into helper
  svcrdma: Add Write chunk WRs to the RPC's Send WR chain
  svcrdma: Clean up use of rdma->sc_pd->device
  svcrdma: Clean up use of rdma->sc_pd->device in Receive paths
  svcrdma: Add fair queuing for Send Queue access
  SUNRPC: Optimize rq_respages allocation in svc_alloc_arg
  SUNRPC: Track consumed rq_pages entries
  svcrdma: preserve rq_next_page in svc_rdma_save_io_pages
  SUNRPC: Handle NULL entries in svc_rqst_release_pages
  SUNRPC: Allocate a separate Reply page array
  SUNRPC: Tighten bounds checking in svc_rqst_replace_page
  NFSD: Sign filehandles
  ...

Headers placed in include/linux/ form part of the kernel's
internal API and signal to subsystem maintainers that other
parts of the kernel may depend on them. By moving lockd.h
into fs/lockd/, lockd becomes a more self-contained module
whose internal interfaces are clearly distinguished from its
public contract with the rest of the kernel. This relocation
addresses a long-standing XXX comment in the header itself
that acknowledged the file's misplacement. Future changes to
lockd internals can now proceed with confidence that external
consumers are not inadvertently coupled to implementation
details.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

The share.h header defines struct nlm_share and declares the DOS
share management functions used by the NLM server to implement
NLM_SHARE and NLM_UNSHARE operations. These interfaces are used
exclusively within the lockd subsystem. A git grep search confirms
no external code references them.

Relocating this header from include/linux/lockd/ to fs/lockd/
narrows the public API surface of the lockd module. Out-of-tree
code cannot depend on these internal interfaces after this change.
Future refactoring of the share management implementation thus
requires no consideration of external consumers.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

The nlm_fopen() function is part of the API between nfsd and lockd.

Currently its return value is an on-the-wire NLM status code. But
that forces NFSD to include NLM wire protocol definitions despite
having no other dependency on the NLM wire protocol.

In addition, a CONFIG_LOCKD_V4 Kconfig symbol appears in the middle
of NFSD source code.

Refactor: Let's not use on-the-wire values as part of a high-level
API between two Linux kernel modules. That's what we have errno for,
right?

And, instead of simply moving the CONFIG_LOCKD_V4 check, we can get
rid of it entirely and let the decision of what actual NLM status
code goes on the wire to be left up to NLM version-specific code.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>