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Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull superblock updates from Christian Brauner:
"This contains the super rework that was ready for this cycle. The
first part changes the order of how we open block devices and allocate
superblocks, contains various cleanups, simplifications, and a new
mechanism to wait on superblock state changes.
This unblocks work to ultimately limit the number of writers to a
block device. Jan has already scheduled follow-up work that will be
ready for v6.7 and allows us to restrict the number of writers to a
given block device. That series builds on this work right here.
The second part contains filesystem freezing updates.
Overview:
The generic superblock changes are rougly organized as follows
(ignoring additional minor cleanups):
(1) Removal of the bd_super member from struct block_device.
This was a very odd back pointer to struct super_block with
unclear rules. For all relevant places we have other means to get
the same information so just get rid of this.
(2) Simplify rules for superblock cleanup.
Roughly, everything that is allocated during fs_context
initialization and that's stored in fs_context->s_fs_info needs
to be cleaned up by the fs_context->free() implementation before
the superblock allocation function has been called successfully.
After sget_fc() returned fs_context->s_fs_info has been
transferred to sb->s_fs_info at which point sb->kill_sb() if
fully responsible for cleanup. Adhering to these rules means that
cleanup of sb->s_fs_info in fill_super() is to be avoided as it's
brittle and inconsistent.
Cleanup shouldn't be duplicated between sb->put_super() as
sb->put_super() is only called if sb->s_root has been set aka
when the filesystem has been successfully born (SB_BORN). That
complexity should be avoided.
This also means that block devices are to be closed in
sb->kill_sb() instead of sb->put_super(). More details in the
lower section.
(3) Make it possible to lookup or create a superblock before opening
block devices
There's a subtle dependency on (2) as some filesystems did rely
on fill_super() to be called in order to correctly clean up
sb->s_fs_info. All these filesystems have been fixed.
(4) Switch most filesystem to follow the same logic as the generic
mount code now does as outlined in (3).
(5) Use the superblock as the holder of the block device. We can now
easily go back from block device to owning superblock.
(6) Export and extend the generic fs_holder_ops and use them as
holder ops everywhere and remove the filesystem specific holder
ops.
(7) Call from the block layer up into the filesystem layer when the
block device is removed, allowing to shut down the filesystem
without risk of deadlocks.
(8) Get rid of get_super().
We can now easily go back from the block device to owning
superblock and can call up from the block layer into the
filesystem layer when the device is removed. So no need to wade
through all registered superblock to find the owning superblock
anymore"
Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/
* tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits)
super: use higher-level helper for {freeze,thaw}
super: wait until we passed kill super
super: wait for nascent superblocks
super: make locking naming consistent
super: use locking helpers
fs: simplify invalidate_inodes
fs: remove get_super
block: call into the file system for ioctl BLKFLSBUF
block: call into the file system for bdev_mark_dead
block: consolidate __invalidate_device and fsync_bdev
block: drop the "busy inodes on changed media" log message
dasd: also call __invalidate_device when setting the device offline
amiflop: don't call fsync_bdev in FDFMTBEG
floppy: call disk_force_media_change when changing the format
block: simplify the disk_force_media_change interface
nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl
xfs use fs_holder_ops for the log and RT devices
xfs: drop s_umount over opening the log and RT devices
ext4: use fs_holder_ops for the log device
ext4: drop s_umount over opening the log device
...
Summary
=======
This introduces FSCONFIG_CMD_CREATE_EXCL which will allows userspace to
implement something like mount -t ext4 --exclusive /dev/sda /B which
fails if a superblock for the requested filesystem does already exist:
Before this patch
-----------------
$ sudo ./move-mount -f xfs -o source=/dev/sda4 /A
Requesting filesystem type xfs
Mount options requested: source=/dev/sda4
Attaching mount at /A
Moving single attached mount
Setting key(source) with val(/dev/sda4)
$ sudo ./move-mount -f xfs -o source=/dev/sda4 /B
Requesting filesystem type xfs
Mount options requested: source=/dev/sda4
Attaching mount at /B
Moving single attached mount
Setting key(source) with val(/dev/sda4)
After this patch with --exclusive as a switch for FSCONFIG_CMD_CREATE_EXCL
--------------------------------------------------------------------------
$ sudo ./move-mount -f xfs --exclusive -o source=/dev/sda4 /A
Requesting filesystem type xfs
Request exclusive superblock creation
Mount options requested: source=/dev/sda4
Attaching mount at /A
Moving single attached mount
Setting key(source) with val(/dev/sda4)
$ sudo ./move-mount -f xfs --exclusive -o source=/dev/sda4 /B
Requesting filesystem type xfs
Request exclusive superblock creation
Mount options requested: source=/dev/sda4
Attaching mount at /B
Moving single attached mount
Setting key(source) with val(/dev/sda4)
Device or resource busy | move-mount.c: 300: do_fsconfig: i xfs: reusing existing filesystem not allowed
Details
=======
As mentioned on the list (cf. [1]-[3]) mount requests like
mount -t ext4 /dev/sda /A are ambigous for userspace. Either a new
superblock has been created and mounted or an existing superblock has
been reused and a bind-mount has been created.
This becomes clear in the following example where two processes create
the same mount for the same block device:
P1 P2
fd_fs = fsopen("ext4"); fd_fs = fsopen("ext4");
fsconfig(fd_fs, FSCONFIG_SET_STRING, "source", "/dev/sda"); fsconfig(fd_fs, FSCONFIG_SET_STRING, "source", "/dev/sda");
fsconfig(fd_fs, FSCONFIG_SET_STRING, "dax", "always"); fsconfig(fd_fs, FSCONFIG_SET_STRING, "resuid", "1000");
// wins and creates superblock
fsconfig(fd_fs, FSCONFIG_CMD_CREATE, ...)
// finds compatible superblock of P1
// spins until P1 sets SB_BORN and grabs a reference
fsconfig(fd_fs, FSCONFIG_CMD_CREATE, ...)
fd_mnt1 = fsmount(fd_fs); fd_mnt2 = fsmount(fd_fs);
move_mount(fd_mnt1, "/A") move_mount(fd_mnt2, "/B")
Not just does P2 get a bind-mount but the mount options that P2
requestes are silently ignored. The VFS itself doesn't, can't and
shouldn't enforce filesystem specific mount option compatibility. It
only enforces incompatibility for read-only <-> read-write transitions:
mount -t ext4 /dev/sda /A
mount -t ext4 -o ro /dev/sda /B
The read-only request will fail with EBUSY as the VFS can't just
silently transition a superblock from read-write to read-only or vica
versa without risking security issues.
To userspace this silent superblock reuse can become a security issue in
because there is currently no straightforward way for userspace to know
that they did indeed manage to create a new superblock and didn't just
reuse an existing one.
This adds a new FSCONFIG_CMD_CREATE_EXCL command to fsconfig() that
returns EBUSY if an existing superblock would be reused. Userspace that
needs to be sure that it did create a new superblock with the requested
mount options can request superblock creation using this command. If the
command succeeds they can be sure that they did create a new superblock
with the requested mount options.
This requires the new mount api. With the old mount api it would be
necessary to plumb this through every legacy filesystem's
file_system_type->mount() method. If they want this feature they are
most welcome to switch to the new mount api.
Following is an analysis of the effect of FSCONFIG_CMD_CREATE_EXCL on
each high-level superblock creation helper:
(1) get_tree_nodev()
Always allocate new superblock. Hence, FSCONFIG_CMD_CREATE and
FSCONFIG_CMD_CREATE_EXCL are equivalent.
The binderfs or overlayfs filesystems are examples.
(4) get_tree_keyed()
Finds an existing superblock based on sb->s_fs_info. Hence,
FSCONFIG_CMD_CREATE would reuse an existing superblock whereas
FSCONFIG_CMD_CREATE_EXCL would reject it with EBUSY.
The mqueue or nfsd filesystems are examples.
(2) get_tree_bdev()
This effectively works like get_tree_keyed().
The ext4 or xfs filesystems are examples.
(3) get_tree_single()
Only one superblock of this filesystem type can ever exist.
Hence, FSCONFIG_CMD_CREATE would reuse an existing superblock
whereas FSCONFIG_CMD_CREATE_EXCL would reject it with EBUSY.
The securityfs or configfs filesystems are examples.
Note that some single-instance filesystems never destroy the
superblock once it has been created during the first mount. For
example, if securityfs has been mounted at least onces then the
created superblock will never be destroyed again as long as there is
still an LSM making use it. Consequently, even if securityfs is
unmounted and the superblock seemingly destroyed it really isn't
which means that FSCONFIG_CMD_CREATE_EXCL will continue rejecting
reusing an existing superblock.
This is acceptable thugh since special purpose filesystems such as
this shouldn't have a need to use FSCONFIG_CMD_CREATE_EXCL anyway
and if they do it's probably to make sure that mount options aren't
ignored.
Following is an analysis of the effect of FSCONFIG_CMD_CREATE_EXCL on
filesystems that make use of the low-level sget_fc() helper directly.
They're all effectively variants on get_tree_keyed(), get_tree_bdev(),
or get_tree_nodev():
(5) mtd_get_sb()
Similar logic to get_tree_keyed().
(6) afs_get_tree()
Similar logic to get_tree_keyed().
(7) ceph_get_tree()
Similar logic to get_tree_keyed().
Already explicitly allows forcing the allocation of a new superblock
via CEPH_OPT_NOSHARE. This turns it into get_tree_nodev().
(8) fuse_get_tree_submount()
Similar logic to get_tree_nodev().
(9) fuse_get_tree()
Forces reuse of existing FUSE superblock.
Forces reuse of existing superblock if passed in file refers to an
existing FUSE connection.
If FSCONFIG_CMD_CREATE_EXCL is specified together with an fd
referring to an existing FUSE connections this would cause the
superblock reusal to fail. If reusing is the intent then
FSCONFIG_CMD_CREATE_EXCL shouldn't be specified.
(10) fuse_get_tree()
-> get_tree_nodev()
Same logic as in get_tree_nodev().
(11) fuse_get_tree()
-> get_tree_bdev()
Same logic as in get_tree_bdev().
(12) virtio_fs_get_tree()
Same logic as get_tree_keyed().
(13) gfs2_meta_get_tree()
Forces reuse of existing gfs2 superblock.
Mounting gfs2meta enforces that a gf2s superblock must already
exist. If not, it will error out. Consequently, mounting gfs2meta
with FSCONFIG_CMD_CREATE_EXCL would always fail. If reusing is the
intent then FSCONFIG_CMD_CREATE_EXCL shouldn't be specified.
(14) kernfs_get_tree()
Similar logic to get_tree_keyed().
(15) nfs_get_tree_common()
Similar logic to get_tree_keyed().
Already explicitly allows forcing the allocation of a new superblock
via NFS_MOUNT_UNSHARED. This effectively turns it into
get_tree_nodev().
Link: [1] https://lore.kernel.org/linux-block/20230704-fasching-wertarbeit-7c6ffb01c83d@brauner
Link: [2] https://lore.kernel.org/linux-block/20230705-pumpwerk-vielversprechend-a4b1fd947b65@brauner
Link: [3] https://lore.kernel.org/linux-fsdevel/20230725-einnahmen-warnschilder-17779aec0a97@brauner
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230802-vfs-super-exclusive-v2-4-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The get_tree_single_reconf() helper isn't used anywhere. Remove it.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230802-vfs-super-exclusive-v2-1-95dc4e41b870@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
We'll want to use setup_bdev_super instead of duplicating it in nilfs2.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Message-Id: <20230802154131.2221419-2-hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This isn't ever used by VFS now, and it couldn't even work. Any FS that
uses the SECURITY_LSM_NATIVE_LABELS flag needs to also process the
value returned back from the LSM, so it needs to do its
security_sb_set_mnt_opts() call on its own anyway.
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Merge tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm
Pull lsm updates from Paul Moore:
- Improve the error handling in the device cgroup such that memory
allocation failures when updating the access policy do not
potentially alter the policy.
- Some minor fixes to reiserfs to ensure that it properly releases
LSM-related xattr values.
- Update the security_socket_getpeersec_stream() LSM hook to take
sockptr_t values.
Previously the net/BPF folks updated the getsockopt code in the
network stack to leverage the sockptr_t type to make it easier to
pass both kernel and __user pointers, but unfortunately when they did
so they didn't convert the LSM hook.
While there was/is no immediate risk by not converting the LSM hook,
it seems like this is a mistake waiting to happen so this patch
proactively does the LSM hook conversion.
- Convert vfs_getxattr_alloc() to return an int instead of a ssize_t
and cleanup the callers. Internally the function was never going to
return anything larger than an int and the callers were doing some
very odd things casting the return value; this patch fixes all that
and helps bring a bit of sanity to vfs_getxattr_alloc() and its
callers.
- More verbose, and helpful, LSM debug output when the system is booted
with "lsm.debug" on the command line. There are examples in the
commit description, but the quick summary is that this patch provides
better information about which LSMs are enabled and the ordering in
which they are processed.
- General comment and kernel-doc fixes and cleanups.
* tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
lsm: Fix description of fs_context_parse_param
lsm: Add/fix return values in lsm_hooks.h and fix formatting
lsm: Clarify documentation of vm_enough_memory hook
reiserfs: Add missing calls to reiserfs_security_free()
lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
device_cgroup: Roll back to original exceptions after copy failure
LSM: Better reporting of actual LSMs at boot
lsm: make security_socket_getpeersec_stream() sockptr_t safe
audit: Fix some kernel-doc warnings
lsm: remove obsoleted comments for security hooks
fs: edit a comment made in bad taste
Remove the pointless keying argument and associated enum and pass the
fill_super callback and a "bool reconf" instead. Also mark the function
static given that there are no users outside of super.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
I know nobody likes a buzzkill, but I figure it's best to keep the
bad jokes appropriate for small children.
Signed-off-by: Paul Moore <paul@paul-moore.com>
Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
mount options as "remount" options, so it updates the configuration of
the single super_block on each mount.
Since that was changed, the mount options used for devtmpfs are ignored.
This is a regression which affect systemd - which mounts devtmpfs with
"-o mode=755,size=4m,nr_inodes=1m".
This patch restores the "remount" effect by calling reconfigure_single()
Fixes: d401727ea0 ("devtmpfs: don't mix {ramfs,shmem}_fill_super() with mount_single()")
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Richard reported sporadic (roughly one in 10 or so) null dereferences and
other strange behaviour for a set of automated LTP tests. Things like:
BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
RIP: 0010:kernfs_sop_show_path+0x1b/0x60
...or these others:
RIP: 0010:do_mkdirat+0x6a/0xf0
RIP: 0010:d_alloc_parallel+0x98/0x510
RIP: 0010:do_readlinkat+0x86/0x120
There were other less common instances of some kind of a general scribble
but the common theme was mount and cgroup and a dubious dentry triggering
the NULL dereference. I was only able to reproduce it under qemu by
replicating Richard's setup as closely as possible - I never did get it
to happen on bare metal, even while keeping everything else the same.
In commit 71d883c37e ("cgroup_do_mount(): massage calling conventions")
we see this as a part of the overall change:
--------------
struct cgroup_subsys *ss;
- struct dentry *dentry;
[...]
- dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root,
- CGROUP_SUPER_MAGIC, ns);
[...]
- if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
- struct super_block *sb = dentry->d_sb;
- dput(dentry);
+ ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns);
+ if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) {
+ struct super_block *sb = fc->root->d_sb;
+ dput(fc->root);
deactivate_locked_super(sb);
msleep(10);
return restart_syscall();
}
--------------
In changing from the local "*dentry" variable to using fc->root, we now
export/leave that dentry pointer in the file context after doing the dput()
in the unlikely "is_dying" case. With LTP doing a crazy amount of back to
back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely
becomes slightly likely and then bad things happen.
A fix would be to not leave the stale reference in fc->root as follows:
--------------
dput(fc->root);
+ fc->root = NULL;
deactivate_locked_super(sb);
--------------
...but then we are just open-coding a duplicate of fc_drop_locked() so we
simply use that instead.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: stable@vger.kernel.org # v5.1+
Reported-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Fixes: 71d883c37e ("cgroup_do_mount(): massage calling conventions")
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add a simple helper that filesystems can use in their parameter parser
to parse the "source" parameter. A few places open-coded this function
and that already caused a bug in the cgroup v1 parser that we fixed.
Let's make it harder to get this wrong by introducing a helper which
performs all necessary checks.
Link: https://syzkaller.appspot.com/bug?id=6312526aba5beae046fdae8f00399f87aab48b12
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previous patch changed handling of remount/reconfigure to ignore all
options, including those that are unknown to the fuse kernel fs. This was
done for backward compatibility, but this likely only affects the old
mount(2) API.
The new fsconfig(2) based reconfiguration could possibly be improved. This
would make the new API less of a drop in replacement for the old, OTOH this
is a good chance to get rid of some weirdnesses in the old API.
Several other behaviors might make sense:
1) unknown options are rejected, known options are ignored
2) unknown options are rejected, known options are rejected if the value
is changed, allowed otherwise
3) all options are rejected
Prior to the backward compatibility fix to ignore all options all known
options were accepted (1), even if they change the value of a mount
parameter; fuse_reconfigure() does not look at the config values set by
fuse_parse_param().
To fix that we'd need to verify that the value provided is the same as set
in the initial configuration (2). The major drawback is that this is much
more complex than just rejecting all attempts at changing options (3);
i.e. all options signify initial configuration values and don't make sense
on reconfigure.
This patch opts for (3) with the rationale that no mount options are
reconfigurable in fuse.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add table markups;
- Add lists markups;
- Add it to filesystems/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/32332c1659a28c22561cb5e64162c959856066b4.1588021877.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
... turning it into struct p_log embedded into fs_context. Initialize
the prefix with fs_type->name, turning fs_parse() into a trivial
inline wrapper for __fs_parse().
This makes fs_parameter_description->name completely unused.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs_parse() analogue taking p_log instead of fs_context.
fs_parse() turned into a wrapper, callers in ceph_common and rbd
switched to __fs_parse().
As the result, fs_parse() never gets NULL fs_context and neither
do fs_context-based logging primitives
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Its behaviour is identical to that of fs_value_is_filename.
It makes no sense, anyway - LOOKUP_EMPTY affects nothing
whatsoever once the pathname has been imported from userland.
And both fs_value_is_filename and fs_value_is_filename_empty
carry an already imported pathname.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse updates from Miklos Szeredi:
- Continue separating the transport (user/kernel communication) and the
filesystem layers of fuse. Getting rid of most layering violations
will allow for easier cleanup and optimization later on.
- Prepare for the addition of the virtio-fs filesystem. The actual
filesystem will be introduced by a separate pull request.
- Convert to new mount API.
- Various fixes, optimizations and cleanups.
* tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (55 commits)
fuse: Make fuse_args_to_req static
fuse: fix memleak in cuse_channel_open
fuse: fix beyond-end-of-page access in fuse_parse_cache()
fuse: unexport fuse_put_request
fuse: kmemcg account fs data
fuse: on 64-bit store time in d_fsdata directly
fuse: fix missing unlock_page in fuse_writepage()
fuse: reserve byteswapped init opcodes
fuse: allow skipping control interface and forced unmount
fuse: dissociate DESTROY from fuseblk
fuse: delete dentry if timeout is zero
fuse: separate fuse device allocation and installation in fuse_conn
fuse: add fuse_iqueue_ops callbacks
fuse: extract fuse_fill_super_common()
fuse: export fuse_dequeue_forget() function
fuse: export fuse_get_unique()
fuse: export fuse_send_init_request()
fuse: export fuse_len_args()
fuse: export fuse_end_request()
fuse: fix request limit
...
The unused vfs code can be removed. Don't pass empty subtype (same as if
->parse callback isn't called).
The bits that are left involve determining whether it's permitted to split the
filesystem type string passed in to mount(2). Consequently, this means that we
cannot get rid of the FS_HAS_SUBTYPE flag unless we define that a type string
with a dot in it always indicates a subtype specification.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add an additional keying mode to vfs_get_super() to indicate that only a
single superblock should exist in the system, and that, if it does, further
mounts should invoke reconfiguration upon it.
This allows mount_single() to be replaced.
[Fix by Eric Biggers folded in]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Create a function, get_tree_bdev(), that is fs_context-aware and a
->get_tree() counterpart of mount_bdev().
It caches the block device pointer in the fs_context struct so that this
information can be passed into sget_fc()'s test and set functions.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: linux-block@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs mount updates from Al Viro:
"The first part of mount updates.
Convert filesystems to use the new mount API"
* 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
mnt_init(): call shmem_init() unconditionally
constify ksys_mount() string arguments
don't bother with registering rootfs
init_rootfs(): don't bother with init_ramfs_fs()
vfs: Convert smackfs to use the new mount API
vfs: Convert selinuxfs to use the new mount API
vfs: Convert securityfs to use the new mount API
vfs: Convert apparmorfs to use the new mount API
vfs: Convert openpromfs to use the new mount API
vfs: Convert xenfs to use the new mount API
vfs: Convert gadgetfs to use the new mount API
vfs: Convert oprofilefs to use the new mount API
vfs: Convert ibmasmfs to use the new mount API
vfs: Convert qib_fs/ipathfs to use the new mount API
vfs: Convert efivarfs to use the new mount API
vfs: Convert configfs to use the new mount API
vfs: Convert binfmt_misc to use the new mount API
convenience helper: get_tree_single()
convenience helper get_tree_nodev()
vfs: Kill sget_userns()
...
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Merge tag 'v5.2-rc4' into mauro
We need to pick up post-rc1 changes to various document files so they don't
get lost in Mauro's massive RST conversion push.
Mostly due to x86 and acpi conversion, several documentation
links are still pointing to the old file. Fix them.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Provide a field in the fs_context struct through which bits in the
sb->s_iflags superblock field can be set.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-fsdevel@vger.kernel.org
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public licence as published by
the free software foundation either version 2 of the licence or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 114 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Implement the ability for filesystems to log error, warning and
informational messages through the fs_context. These can be extracted by
userspace by reading from an fd created by fsopen().
Error messages are prefixed with "e ", warnings with "w " and informational
messages with "i ".
Inside the kernel, formatted messages are malloc'd but unformatted messages
are not copied if they're either in the core .rodata section or in the
.rodata section of the filesystem module pinned by fs_context::fs_type.
The messages are only good till the fs_type is released.
Note that the logging object is shared between duplicated fs_context
structures. This is so that such as NFS which do a mount within a mount
can get at least some of the errors from the inner mount.
Five logging functions are provided for this:
(1) void logfc(struct fs_context *fc, const char *fmt, ...);
This logs a message into the context. If the buffer is full, the
earliest message is discarded.
(2) void errorf(fc, fmt, ...);
This wraps logfc() to log an error.
(3) void invalf(fc, fmt, ...);
This wraps errorf() and returns -EINVAL for convenience.
(4) void warnf(fc, fmt, ...);
This wraps logfc() to log a warning.
(5) void infof(fc, fmt, ...);
This wraps logfc() to log an informational message.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Provide an fsopen() system call that starts the process of preparing to
create a superblock that will then be mountable, using an fd as a context
handle. fsopen() is given the name of the filesystem that will be used:
int mfd = fsopen(const char *fsname, unsigned int flags);
where flags can be 0 or FSOPEN_CLOEXEC.
For example:
sfd = fsopen("ext4", FSOPEN_CLOEXEC);
fsconfig(sfd, FSCONFIG_SET_PATH, "source", "/dev/sda1", AT_FDCWD);
fsconfig(sfd, FSCONFIG_SET_FLAG, "noatime", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_FLAG, "acl", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_FLAG, "user_xattr", NULL, 0);
fsconfig(sfd, FSCONFIG_SET_STRING, "sb", "1", 0);
fsconfig(sfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
fsinfo(sfd, NULL, ...); // query new superblock attributes
mfd = fsmount(sfd, FSMOUNT_CLOEXEC, MS_RELATIME);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
sfd = fsopen("afs", -1);
fsconfig(fd, FSCONFIG_SET_STRING, "source",
"#grand.central.org:root.cell", 0);
fsconfig(fd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
mfd = fsmount(sfd, 0, MS_NODEV);
move_mount(mfd, "", sfd, AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH);
If an error is reported at any step, an error message may be available to be
read() back (ENODATA will be reported if there isn't an error available) in
the form:
"e <subsys>:<problem>"
"e SELinux:Mount on mountpoint not permitted"
Once fsmount() has been called, further fsconfig() calls will incur EBUSY,
even if the fsmount() fails. read() is still possible to retrieve error
information.
The fsopen() syscall creates a mount context and hangs it of the fd that it
returns.
Netlink is not used because it is optional and would make the core VFS
dependent on the networking layer and also potentially add network
namespace issues.
Note that, for the moment, the caller must have SYS_CAP_ADMIN to use
fsopen().
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Implement the ability for filesystems to log error, warning and
informational messages through the fs_context. In the future, these will
be extractable by userspace by reading from an fd created by the fsopen()
syscall.
Error messages are prefixed with "e ", warnings with "w " and informational
messages with "i ".
In the future, inside the kernel, formatted messages will be malloc'd but
unformatted messages will not copied if they're either in the core .rodata
section or in the .rodata section of the filesystem module pinned by
fs_context::fs_type. The messages will only be good till the fs_type is
released.
Note that the logging object will be shared between duplicated fs_context
structures. This is so that such as NFS which do a mount within a mount
can get at least some of the errors from the inner mount.
Five logging functions are provided for this:
(1) void logfc(struct fs_context *fc, const char *fmt, ...);
This logs a message into the context. If the buffer is full, the
earliest message is discarded.
(2) void errorf(fc, fmt, ...);
This wraps logfc() to log an error.
(3) void invalf(fc, fmt, ...);
This wraps errorf() and returns -EINVAL for convenience.
(4) void warnf(fc, fmt, ...);
This wraps logfc() to log a warning.
(5) void infof(fc, fmt, ...);
This wraps logfc() to log an informational message.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new primitive: vfs_dup_fs_context(). Comes with fs_context
method (->dup()) for copying the filesystem-specific parts
of fs_context, along with LSM one (->fs_context_dup()) for
doing the same to LSM parts.
[needs better commit message, and change of Author:, anyway]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
the former is an analogue of mount_{single,nodev} for use in
->get_tree() instances, the latter - analogue of sget() for the
same.
These are fairly similar to the originals, but the callback signature
for sget_fc() is different from sget() ones, so getting bits and
pieces shared would be too convoluted; we might get around to that
later, but for now let's just remember to keep them in sync. They
do live next to each other, and changes in either won't be hard
to spot.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[AV - unfuck kern_mount_data(); we want non-NULL ->mnt_ns on long-living
mounts]
[AV - reordering fs/namespace.c is badly overdue, but let's keep it
separate from that series]
[AV - drop simple_pin_fs() change]
[AV - clean vfs_kern_mount() failure exits up]
Implement a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount.
The mounting procedure then becomes:
(1) Allocate new fs_context context.
(2) Configure the context.
(3) Create superblock.
(4) Query the superblock.
(5) Create a mount for the superblock.
(6) Destroy the context.
Rather than calling fs_type->mount(), an fs_context struct is created and
fs_type->init_fs_context() is called to set it up. Pointers exist for the
filesystem and LSM to hang their private data off.
A set of operations has to be set by ->init_fs_context() to provide
freeing, duplication, option parsing, binary data parsing, validation,
mounting and superblock filling.
Legacy filesystems are supported by the provision of a set of legacy
fs_context operations that build up a list of mount options and then invoke
fs_type->mount() from within the fs_context ->get_tree() operation. This
allows all filesystems to be accessed using fs_context.
It should be noted that, whilst this patch adds a lot of lines of code,
there is quite a bit of duplication with existing code that can be
eliminated should all filesystems be converted over.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Put security flags, such as SECURITY_LSM_NATIVE_LABELS, into the filesystem
context so that the filesystem can communicate them to the LSM more easily.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Because the new API passes in key,value parameters, match_token() cannot be
used with it. Instead, provide three new helpers to aid with parsing:
(1) fs_parse(). This takes a parameter and a simple static description of
all the parameters and maps the key name to an ID. It returns 1 on a
match, 0 on no match if unknowns should be ignored and some other
negative error code on a parse error.
The parameter description includes a list of key names to IDs, desired
parameter types and a list of enumeration name -> ID mappings.
[!] Note that for the moment I've required that the key->ID mapping
array is expected to be sorted and unterminated. The size of the
array is noted in the fsconfig_parser struct. This allows me to use
bsearch(), but I'm not sure any performance gain is worth the hassle
of requiring people to keep the array sorted.
The parameter type array is sized according to the number of parameter
IDs and is indexed directly. The optional enum mapping array is an
unterminated, unsorted list and the size goes into the fsconfig_parser
struct.
The function can do some additional things:
(a) If it's not ambiguous and no value is given, the prefix "no" on
a key name is permitted to indicate that the parameter should
be considered negatory.
(b) If the desired type is a single simple integer, it will perform
an appropriate conversion and store the result in a union in
the parse result.
(c) If the desired type is an enumeration, {key ID, name} will be
looked up in the enumeration list and the matching value will
be stored in the parse result union.
(d) Optionally generate an error if the key is unrecognised.
This is called something like:
enum rdt_param {
Opt_cdp,
Opt_cdpl2,
Opt_mba_mpbs,
nr__rdt_params
};
const struct fs_parameter_spec rdt_param_specs[nr__rdt_params] = {
[Opt_cdp] = { fs_param_is_bool },
[Opt_cdpl2] = { fs_param_is_bool },
[Opt_mba_mpbs] = { fs_param_is_bool },
};
const const char *const rdt_param_keys[nr__rdt_params] = {
[Opt_cdp] = "cdp",
[Opt_cdpl2] = "cdpl2",
[Opt_mba_mpbs] = "mba_mbps",
};
const struct fs_parameter_description rdt_parser = {
.name = "rdt",
.nr_params = nr__rdt_params,
.keys = rdt_param_keys,
.specs = rdt_param_specs,
.no_source = true,
};
int rdt_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{
struct fs_parse_result parse;
struct rdt_fs_context *ctx = rdt_fc2context(fc);
int ret;
ret = fs_parse(fc, &rdt_parser, param, &parse);
if (ret < 0)
return ret;
switch (parse.key) {
case Opt_cdp:
ctx->enable_cdpl3 = true;
return 0;
case Opt_cdpl2:
ctx->enable_cdpl2 = true;
return 0;
case Opt_mba_mpbs:
ctx->enable_mba_mbps = true;
return 0;
}
return -EINVAL;
}
(2) fs_lookup_param(). This takes a { dirfd, path, LOOKUP_EMPTY? } or
string value and performs an appropriate path lookup to convert it
into a path object, which it will then return.
If the desired type was a blockdev, the type of the looked up inode
will be checked to make sure it is one.
This can be used like:
enum foo_param {
Opt_source,
nr__foo_params
};
const struct fs_parameter_spec foo_param_specs[nr__foo_params] = {
[Opt_source] = { fs_param_is_blockdev },
};
const char *char foo_param_keys[nr__foo_params] = {
[Opt_source] = "source",
};
const struct constant_table foo_param_alt_keys[] = {
{ "device", Opt_source },
};
const struct fs_parameter_description foo_parser = {
.name = "foo",
.nr_params = nr__foo_params,
.nr_alt_keys = ARRAY_SIZE(foo_param_alt_keys),
.keys = foo_param_keys,
.alt_keys = foo_param_alt_keys,
.specs = foo_param_specs,
};
int foo_parse_param(struct fs_context *fc,
struct fs_parameter *param)
{
struct fs_parse_result parse;
struct foo_fs_context *ctx = foo_fc2context(fc);
int ret;
ret = fs_parse(fc, &foo_parser, param, &parse);
if (ret < 0)
return ret;
switch (parse.key) {
case Opt_source:
return fs_lookup_param(fc, &foo_parser, param,
&parse, &ctx->source);
default:
return -EINVAL;
}
}
(3) lookup_constant(). This takes a table of named constants and looks up
the given name within it. The table is expected to be sorted such
that bsearch() be used upon it.
Possibly I should require the table be terminated and just use a
for-loop to scan it instead of using bsearch() to reduce hassle.
Tables look something like:
static const struct constant_table bool_names[] = {
{ "0", false },
{ "1", true },
{ "false", false },
{ "no", false },
{ "true", true },
{ "yes", true },
};
and a lookup is done with something like:
b = lookup_constant(bool_names, param->string, -1);
Additionally, optional validation routines for the parameter description
are provided that can be enabled at compile time. A later patch will
invoke these when a filesystem is registered.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduce a set of logging functions through which informational messages,
warnings and error messages incurred by the mount procedure can be logged
and, in a future patch, passed to userspace instead by way of the
filesystem configuration context file descriptor.
There are four functions:
(1) infof(const char *fmt, ...);
Logs an informational message.
(2) warnf(const char *fmt, ...);
Logs a warning message.
(3) errorf(const char *fmt, ...);
Logs an error message.
(4) invalf(const char *fmt, ...);
As errof(), but returns -EINVAL so can be used on a return statement.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This is an eventual replacement for vfs_submount() uses. Unlike the
"mount" and "remount" cases, the users of that thing are not in VFS -
they are buried in various ->d_automount() instances and rather than
converting them all at once we introduce the (thankfully small and
simple) infrastructure here and deal with the prospective users in
afs, nfs, etc. parts of the series.
Here we just introduce a new constructor (fs_context_for_submount())
along with the corresponding enum constant to be put into fc->purpose
for those.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Replace do_remount_sb() with a function, reconfigure_super(), that's
fs_context aware. The fs_context is expected to be parameterised already
and have ->root pointing to the superblock to be reconfigured.
A legacy wrapper is provided that is intended to be called from the
fs_context ops when those appear, but for now is called directly from
reconfigure_super(). This wrapper invokes the ->remount_fs() superblock op
for the moment. It is intended that the remount_fs() op will be phased
out.
The fs_context->purpose is set to FS_CONTEXT_FOR_RECONFIGURE to indicate
that the context is being used for reconfiguration.
do_umount_root() is provided to consolidate remount-to-R/O for umount and
emergency remount by creating a context and invoking reconfiguration.
do_remount(), do_umount() and do_emergency_remount_callback() are switched
to use the new process.
[AV -- fold UMOUNT and EMERGENCY_REMOUNT in; fixes the
umount / bug, gets rid of pointless complexity]
[AV -- set ->net_ns in all cases; nfs remount will need that]
[AV -- shift security_sb_remount() call into reconfigure_super(); the callers
that didn't do security_sb_remount() have NULL fc->security anyway, so it's
a no-op for them]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduce a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount. This is
allocated at the beginning of the mount procedure and into it is placed:
(1) Filesystem type.
(2) Namespaces.
(3) Source/Device names (there may be multiple).
(4) Superblock flags (SB_*).
(5) Security details.
(6) Filesystem-specific data, as set by the mount options.
Accessor functions are then provided to set up a context, parameterise it
from monolithic mount data (the data page passed to mount(2)) and tear it
down again.
A legacy wrapper is provided that implements what will be the basic
operations, wrapping access to filesystems that aren't yet aware of the
fs_context.
Finally, vfs_kern_mount() is changed to make use of the fs_context and
mount_fs() is replaced by vfs_get_tree(), called from vfs_kern_mount().
[AV -- add missing kstrdup()]
[AV -- put_cred() can be unconditional - fc->cred can't be NULL]
[AV -- take legacy_validate() contents into legacy_parse_monolithic()]
[AV -- merge KERNEL_MOUNT and USER_MOUNT]
[AV -- don't unlock superblock on success return from vfs_get_tree()]
[AV -- kill 'reference' argument of init_fs_context()]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
