These inlines show up in the fast path (e.g., in do_dentry_open()) and
induce said full barrier regarding i_flctx access when in most cases the
pointer is NULL.
The pointer can be safely checked before issuing the barrier, dodging it
in most cases as a result.
It is plausible the consume fence would be sufficient, but I don't want
to go audit all callers regarding what they before calling here.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240806172846.886570-1-mjguzik@gmail.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Zdenek reported seeing some AVC denials due to nfsd trying to set
delegations:
type=AVC msg=audit(09.11.2023 09:03:46.411:496) : avc: denied { lease } for pid=5127 comm=rpc.nfsd capability=lease scontext=system_u:system_r:nfsd_t:s0 tcontext=system_u:system_r:nfsd_t:s0 tclass=capability permissive=0
When setting delegations on behalf of nfsd, we don't want to do all of
the normal capabilty and LSM checks. nfsd is a kernel thread and runs
with CAP_LEASE set, so the uid checks end up being a no-op in most cases
anyway.
Some nfsd functions can end up running in normal process context when
tearing down the server. At that point, the CAP_LEASE check can fail and
cause the client to not tear down delegations when expected.
Also, the way the per-fs ->setlease handlers work today is a little
convoluted. The non-trivial ones are wrappers around generic_setlease,
so when they fail due to permission problems they usually they end up
doing a little extra work only to determine that they can't set the
lease anyway. It would be more efficient to do those checks earlier.
Transplant the permission checking from generic_setlease to
vfs_setlease, which will make the permission checking happen earlier on
filesystems that have a ->setlease operation. Add a new kernel_setlease
function that bypasses these checks, and switch nfsd to use that instead
of vfs_setlease.
There is one behavioral change here: prior this patch the
setlease_notifier would fire even if the lease attempt was going to fail
the security checks later. With this change, it doesn't fire until the
caller has passed them. I think this is a desirable change overall. nfsd
is the only user of the setlease_notifier and it doesn't benefit from
being notified about failed attempts.
Cc: Ondrej Mosnáček <omosnacek@gmail.com>
Reported-by: Zdenek Pytela <zpytela@redhat.com>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2248830
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240205-bz2248830-v1-1-d0ec0daecba1@kernel.org
Acked-by: Tom Talpey <tom@talpey.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Add a new struct file_lease and move the lease-specific fields from
struct file_lock to it. Convert the appropriate API calls to take
struct file_lease instead, and convert the callers to use them.
There is zero overlap between the lock manager operations for file
locks and the ones for file leases, so split the lease-related
operations off into a new lease_manager_operations struct.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240131-flsplit-v3-47-c6129007ee8d@kernel.org
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In a future patch, we're going to split file leases into their own
structure. Since a lot of the underlying machinery uses the same fields
move those into a new file_lock_core, and embed that inside struct
file_lock.
For now, add some macros to ensure that we can continue to build while
the conversion is in progress.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240131-flsplit-v3-17-c6129007ee8d@kernel.org
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
locks_inode was turned into a wrapper around file_inode in de2a4a501e
(Partially revert "locks: fix file locking on overlayfs"). Finish
replacing locks_inode invocations everywhere with file_inode.
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
The file locking definitions have lived in fs.h since the dawn of time,
but they are only used by a small subset of the source files that
include it.
Move the file locking definitions to a new header file, and add the
appropriate #include directives to the source files that need them. By
doing this we trim down fs.h a bit and limit the amount of rebuilding
that has to be done when we make changes to the file locking APIs.
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Steve French <stfrench@microsoft.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
