When vfs_getattr_nosec() calls a filesystem's getattr interface function
then the 'nosec' should propagate into this function so that
vfs_getattr_nosec() can again be called from the filesystem's gettattr
rather than vfs_getattr(). The latter would add unnecessary security
checks that the initial vfs_getattr_nosec() call wanted to avoid.
Therefore, introduce the getattr flag GETATTR_NOSEC and allow to pass
with the new getattr_flags parameter to the getattr interface function.
In overlayfs and ecryptfs use this flag to determine which one of the
two functions to call.
In a recent code change introduced to IMA vfs_getattr_nosec() ended up
calling vfs_getattr() in overlayfs, which in turn called
security_inode_getattr() on an exiting process that did not have
current->fs set anymore, which then caused a kernel NULL pointer
dereference. With this change the call to security_inode_getattr() can
be avoided, thus avoiding the NULL pointer dereference.
Reported-by: <syzbot+a67fc5321ffb4b311c98@syzkaller.appspotmail.com>
Fixes: db1d1e8b98 ("IMA: use vfs_getattr_nosec to get the i_version")
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Tyler Hicks <code@tyhicks.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Suggested-by: Christian Brauner <brauner@kernel.org>
Co-developed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Link: https://lore.kernel.org/r/20231002125733.1251467-1-stefanb@linux.vnet.ibm.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This reverts commit ffb6cf19e0.
Users reported regressions due to enabling multi-grained timestamps
unconditionally. As no clear consensus on a solution has come up and the
discussion has gone back to the drawing board revert the infrastructure
changes for. If it isn't code that's here to stay, make it go away.
Message-ID: <20230920-keine-eile-c9755b5825db@brauner>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The choose_32_64() macros were added to deal with an odd inconsistency
between the 32-bit and 64-bit layout of 'struct stat' way back when in
commit a52dd971f9 ("vfs: de-crapify "cp_new_stat()" function").
Then a decade later Mikulas noticed that said inconsistency had been a
mistake in the early x86-64 port, and shouldn't have existed in the
first place. So commit 932aba1e16 ("stat: fix inconsistency between
struct stat and struct compat_stat") removed the uses of the helpers.
But the helpers remained around, unused.
Get rid of them.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mateusz reports that glibc turns 'fstat()' calls into 'fstatat()', and
that seems to have been going on for quite a long time due to glibc
having tried to simplify its stat logic into just one point.
This turns out to cause completely unnecessary overhead, where we then
go off and allocate the kernel side pathname, and actually look up the
empty path. Sure, our path lookup is quite optimized, but it still
causes a fair bit of allocation overhead and a couple of completely
unnecessary rounds of lockref accesses etc.
This is all hopefully getting fixed in user space, and there is a patch
floating around for just having glibc use the native fstat() system
call. But even with the current situation we can at least improve on
things by catching the situation and short-circuiting it.
Note that this is still measurably slower than just a plain 'fstat()',
since just checking that the filename is actually empty is somewhat
expensive due to inevitable user space access overhead from the kernel
(ie verifying pointers, and SMAP on x86). But it's still quite a bit
faster than actually looking up the path for real.
To quote numers from Mateusz:
"Sapphire Rapids, will-it-scale, ops/s
stock fstat 5088199
patched fstat 7625244 (+49%)
real fstat 8540383 (+67% / +12%)"
where that 'stock fstat' is the glibc translation of fstat into
fstatat() with an empty path, the 'patched fstat' is with this short
circuiting of the path lookup, and the 'real fstat' is the actual native
fstat() system call with none of this overhead.
Link: https://lore.kernel.org/lkml/20230903204858.lv7i3kqvw6eamhgz@f/
Reported-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The VFS always uses coarse-grained timestamps when updating the ctime
and mtime after a change. This has the benefit of allowing filesystems
to optimize away a lot metadata updates, down to around 1 per jiffy,
even when a file is under heavy writes.
Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).
If we were to always use fine-grained timestamps, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.
What we need is a way to only use fine-grained timestamps when they are
being actively queried.
POSIX generally mandates that when the the mtime changes, the ctime must
also change. The kernel always stores normalized ctime values, so only
the first 30 bits of the tv_nsec field are ever used.
Use the 31st bit of the ctime tv_nsec field to indicate that something
has queried the inode for the mtime or ctime. When this flag is set,
on the next mtime or ctime update, the kernel will fetch a fine-grained
timestamp instead of the usual coarse-grained one.
Filesytems can opt into this behavior by setting the FS_MGTIME flag in
the fstype. Filesystems that don't set this flag will continue to use
coarse-grained timestamps.
Later patches will convert individual filesystems to use the new
infrastructure.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-Id: <20230807-mgctime-v7-9-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
generic_fillattr just fills in the entire stat struct indiscriminately
today, copying data from the inode. There is at least one attribute
(STATX_CHANGE_COOKIE) that can have side effects when it is reported,
and we're looking at adding more with the addition of multigrain
timestamps.
Add a request_mask argument to generic_fillattr and have most callers
just pass in the value that is passed to getattr. Have other callers
(e.g. ksmbd) just pass in STATX_BASIC_STATS. Also move the setting of
STATX_CHANGE_COOKIE into generic_fillattr.
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: "Paulo Alcantara (SUSE)" <pc@manguebit.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230807-mgctime-v7-2-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230705190309.579783-23-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCY+5NlQAKCRCRxhvAZXjc
orOaAP9i2h3OJy95nO2Fpde0Bt2UT+oulKCCcGlvXJ8/+TQpyQD/ZQq47gFQ0EAz
Br5NxeyGeecAb0lHpFz+CpLGsxMrMwQ=
=+BG5
-----END PGP SIGNATURE-----
Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping
Pull vfs idmapping updates from Christian Brauner:
- Last cycle we introduced the dedicated struct mnt_idmap type for
mount idmapping and the required infrastucture in 256c8aed2b ("fs:
introduce dedicated idmap type for mounts"). As promised in last
cycle's pull request message this converts everything to rely on
struct mnt_idmap.
Currently we still pass around the plain namespace that was attached
to a mount. This is in general pretty convenient but it makes it easy
to conflate namespaces that are relevant on the filesystem with
namespaces that are relevant on the mount level. Especially for
non-vfs developers without detailed knowledge in this area this was a
potential source for bugs.
This finishes the conversion. Instead of passing the plain namespace
around this updates all places that currently take a pointer to a
mnt_userns with a pointer to struct mnt_idmap.
Now that the conversion is done all helpers down to the really
low-level helpers only accept a struct mnt_idmap argument instead of
two namespace arguments.
Conflating mount and other idmappings will now cause the compiler to
complain loudly thus eliminating the possibility of any bugs. This
makes it impossible for filesystem developers to mix up mount and
filesystem idmappings as they are two distinct types and require
distinct helpers that cannot be used interchangeably.
Everything associated with struct mnt_idmap is moved into a single
separate file. With that change no code can poke around in struct
mnt_idmap. It can only be interacted with through dedicated helpers.
That means all filesystems are and all of the vfs is completely
oblivious to the actual implementation of idmappings.
We are now also able to extend struct mnt_idmap as we see fit. For
example, we can decouple it completely from namespaces for users that
don't require or don't want to use them at all. We can also extend
the concept of idmappings so we can cover filesystem specific
requirements.
In combination with the vfs{g,u}id_t work we finished in v6.2 this
makes this feature substantially more robust and thus difficult to
implement wrong by a given filesystem and also protects the vfs.
- Enable idmapped mounts for tmpfs and fulfill a longstanding request.
A long-standing request from users had been to make it possible to
create idmapped mounts for tmpfs. For example, to share the host's
tmpfs mount between multiple sandboxes. This is a prerequisite for
some advanced Kubernetes cases. Systemd also has a range of use-cases
to increase service isolation. And there are more users of this.
However, with all of the other work going on this was way down on the
priority list but luckily someone other than ourselves picked this
up.
As usual the patch is tiny as all the infrastructure work had been
done multiple kernel releases ago. In addition to all the tests that
we already have I requested that Rodrigo add a dedicated tmpfs
testsuite for idmapped mounts to xfstests. It is to be included into
xfstests during the v6.3 development cycle. This should add a slew of
additional tests.
* tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits)
shmem: support idmapped mounts for tmpfs
fs: move mnt_idmap
fs: port vfs{g,u}id helpers to mnt_idmap
fs: port fs{g,u}id helpers to mnt_idmap
fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap
fs: port i_{g,u}id_{needs_}update() to mnt_idmap
quota: port to mnt_idmap
fs: port privilege checking helpers to mnt_idmap
fs: port inode_owner_or_capable() to mnt_idmap
fs: port inode_init_owner() to mnt_idmap
fs: port acl to mnt_idmap
fs: port xattr to mnt_idmap
fs: port ->permission() to pass mnt_idmap
fs: port ->fileattr_set() to pass mnt_idmap
fs: port ->set_acl() to pass mnt_idmap
fs: port ->get_acl() to pass mnt_idmap
fs: port ->tmpfile() to pass mnt_idmap
fs: port ->rename() to pass mnt_idmap
fs: port ->mknod() to pass mnt_idmap
fs: port ->mkdir() to pass mnt_idmap
...
The NFS server has a lot of special handling for different types of
change attribute access, depending on the underlying filesystem. In
most cases, it's doing a getattr anyway and then fetching that value
after the fact.
Rather that do that, add a new STATX_CHANGE_COOKIE flag that is a
kernel-only symbol (for now). If requested and getattr can implement it,
it can fill out this field. For IS_I_VERSION inodes, add a generic
implementation in vfs_getattr_nosec. Take care to mask
STATX_CHANGE_COOKIE off in requests from userland and in the result
mask.
Since not all filesystems can give the same guarantees of monotonicity,
claim a STATX_ATTR_CHANGE_MONOTONIC flag that filesystems can set to
indicate that they offer an i_version value that can never go backward.
Eventually if we decide to make the i_version available to userland, we
can just designate a field for it in struct statx, and move the
STATX_CHANGE_COOKIE definition to the uapi header.
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Convert to struct mnt_idmap.
Remove legacy file_mnt_user_ns() and mnt_user_ns().
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
We already ported most parts and filesystems over for v6.0 to the new
vfs{g,u}id_t type and associated helpers for v6.0. Convert the remaining
places so we can remove all the old helpers.
This is a non-functional change.
Reviewed-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Add support for STATX_DIOALIGN to block devices, so that direct I/O
alignment restrictions are exposed to userspace in a generic way.
Note that this breaks the tradition of stat operating only on the block
device node, not the block device itself. However, it was felt that
doing this is preferable, in order to make the interface useful and
avoid needing separate interfaces for regular files and block devices.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220827065851.135710-3-ebiggers@kernel.org
Traditionally, the conditions for when DIO (direct I/O) is supported
were fairly simple. For both block devices and regular files, DIO had
to be aligned to the logical block size of the block device.
However, due to filesystem features that have been added over time (e.g.
multi-device support, data journalling, inline data, encryption, verity,
compression, checkpoint disabling, log-structured mode), the conditions
for when DIO is allowed on a regular file have gotten increasingly
complex. Whether a particular regular file supports DIO, and with what
alignment, can depend on various file attributes and filesystem mount
options, as well as which block device(s) the file's data is located on.
Moreover, the general rule of DIO needing to be aligned to the block
device's logical block size was recently relaxed to allow user buffers
(but not file offsets) aligned to the DMA alignment instead. See
commit bf8d08532b ("iomap: add support for dma aligned direct-io").
XFS has an ioctl XFS_IOC_DIOINFO that exposes DIO alignment information.
Uplifting this to the VFS is one possibility. However, as discussed
(https://lore.kernel.org/linux-fsdevel/20220120071215.123274-1-ebiggers@kernel.org/T/#u),
this ioctl is rarely used and not known to be used outside of
XFS-specific code. It was also never intended to indicate when a file
doesn't support DIO at all, nor was it intended for block devices.
Therefore, let's expose this information via statx(). Add the
STATX_DIOALIGN flag and two new statx fields associated with it:
* stx_dio_mem_align: the alignment (in bytes) required for user memory
buffers for DIO, or 0 if DIO is not supported on the file.
* stx_dio_offset_align: the alignment (in bytes) required for file
offsets and I/O segment lengths for DIO, or 0 if DIO is not supported
on the file. This will only be nonzero if stx_dio_mem_align is
nonzero, and vice versa.
Note that as with other statx() extensions, if STATX_DIOALIGN isn't set
in the returned statx struct, then these new fields won't be filled in.
This will happen if the file is neither a regular file nor a block
device, or if the file is a regular file and the filesystem doesn't
support STATX_DIOALIGN. It might also happen if the caller didn't
include STATX_DIOALIGN in the request mask, since statx() isn't required
to return unrequested information.
This commit only adds the VFS-level plumbing for STATX_DIOALIGN. For
regular files, individual filesystems will still need to add code to
support it. For block devices, a separate commit will wire it up too.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220827065851.135710-2-ebiggers@kernel.org
* Support for the Svpbmt extension, which allows memory attributes to be
encoded in pages.
* Support for the Allwinner D1's implementation of page-based memory
attributes.
* Support for running rv32 binaries on rv64 systems, via the compat
subsystem.
* Support for kexec_file().
* Support for the new generic ticket-based spinlocks, which allows us to
also move to qrwlock. These should have already gone in through the
asm-geneic tree as well.
* A handful of cleanups and fixes, include some larger ones around
atomics and XIP.
-----BEGIN PGP SIGNATURE-----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=Loi6
-----END PGP SIGNATURE-----
Merge tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
- Support for the Svpbmt extension, which allows memory attributes to
be encoded in pages
- Support for the Allwinner D1's implementation of page-based memory
attributes
- Support for running rv32 binaries on rv64 systems, via the compat
subsystem
- Support for kexec_file()
- Support for the new generic ticket-based spinlocks, which allows us
to also move to qrwlock. These should have already gone in through
the asm-geneic tree as well
- A handful of cleanups and fixes, include some larger ones around
atomics and XIP
* tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
RISC-V: Prepare dropping week attribute from arch_kexec_apply_relocations[_add]
riscv: compat: Using seperated vdso_maps for compat_vdso_info
RISC-V: Fix the XIP build
RISC-V: Split out the XIP fixups into their own file
RISC-V: ignore xipImage
RISC-V: Avoid empty create_*_mapping definitions
riscv: Don't output a bogus mmu-type on a no MMU kernel
riscv: atomic: Add custom conditional atomic operation implementation
riscv: atomic: Optimize dec_if_positive functions
riscv: atomic: Cleanup unnecessary definition
RISC-V: Load purgatory in kexec_file
RISC-V: Add purgatory
RISC-V: Support for kexec_file on panic
RISC-V: Add kexec_file support
RISC-V: use memcpy for kexec_file mode
kexec_file: Fix kexec_file.c build error for riscv platform
riscv: compat: Add COMPAT Kbuild skeletal support
riscv: compat: ptrace: Add compat_arch_ptrace implement
riscv: compat: signal: Add rt_frame implementation
riscv: add memory-type errata for T-Head
...
struct stat (defined in arch/x86/include/uapi/asm/stat.h) has 32-bit
st_dev and st_rdev; struct compat_stat (defined in
arch/x86/include/asm/compat.h) has 16-bit st_dev and st_rdev followed by
a 16-bit padding.
This patch fixes struct compat_stat to match struct stat.
[ Historical note: the old x86 'struct stat' did have that 16-bit field
that the compat layer had kept around, but it was changes back in 2003
by "struct stat - support larger dev_t":
https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=e95b2065677fe32512a597a79db94b77b90c968d
and back in those days, the x86_64 port was still new, and separate
from the i386 code, and had already picked up the old version with a
16-bit st_dev field ]
Note that we can't change compat_dev_t because it is used by
compat_loop_info.
Also, if the st_dev and st_rdev values are 32-bit, we don't have to use
old_valid_dev to test if the value fits into them. This fixes
-EOVERFLOW on filesystems that are on NVMe because NVMe uses the major
number 259.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
One of the key architectual tenets is to keep the parameters for
io-uring stable. After the call has been submitted, its value can
be changed. Unfortunaltely this is not the case for the current statx
implementation.
IO-Uring change:
This changes replaces the const char * filename pointer in the io_statx
structure with a struct filename *. In addition it also creates the
filename object during the prepare phase.
With this change, the opcode also needs to invoke cleanup, so the
filename object gets freed after processing the request.
fs change:
This replaces the const char* __user filename parameter in the two
functions do_statx and vfs_statx with a struct filename *. In addition
to be able to correctly construct a filename object a new helper
function getname_statx_lookup_flags is introduced. The function makes
sure that do_statx and vfs_statx is invoked with the correct lookup flags.
Signed-off-by: Stefan Roesch <shr@fb.com>
Link: https://lore.kernel.org/r/20220225185326.1373304-2-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The immutable and append-only properties on an inode are published on
the inode's i_flags and enforced by the VFS.
Create a helper to fill the corresponding STATX_ATTR_ flags in the kstat
structure from the inode's i_flags.
Only orange was converted to use this helper.
Other filesystems could use it in the future.
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
statx(2) notes that any attribute that is not indicated as supported
by stx_attributes_mask has no usable value. Commits 801e523796
("fs: move generic stat response attr handling to vfs_getattr_nosec")
and 712b2698e4 ("fs/stat: Define DAX statx attribute") sets
STATX_ATTR_AUTOMOUNT and STATX_ATTR_DAX, respectively, without setting
stx_attributes_mask, which can cause xfstests generic/532 to fail.
Fix this in the same way as commit 1b9598c8fb ("xfs: fix reporting
supported extra file attributes for statx()")
Fixes: 801e523796 ("fs: move generic stat response attr handling to vfs_getattr_nosec")
Fixes: 712b2698e4 ("fs/stat: Define DAX statx attribute")
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The generic_fillattr() helper fills in the basic attributes associated
with an inode. Enable it to handle idmapped mounts. If the inode is
accessed through an idmapped mount map it into the mount's user
namespace before we store the uid and gid. If the initial user namespace
is passed nothing changes so non-idmapped mounts will see identical
behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-12-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
KSTAT_QUERY_FLAGS expands to AT_STATX_SYNC_TYPE, which itself already
is a mask. Remove the double name, especially given that the prefix
is a little confusing vs the normal AT_* flags.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The function really obsfucates checking for valid flags and setting the
lookup flags. The fact that it returns -EINVAL through and unsigned
return value, which is then used as boolean really doesn't help either.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This allows to keep vfs_statx static in fs/stat.c to prepare for the following
changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
vfs_statx_fd is only used to implement vfs_fstat. Remove vfs_statx_fd
and just implement vfs_fstat directly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
- Clean up io_is_direct.
- Add a new statx flag to indicate when file data access is being done
via DAX (as opposed to the page cache).
- Update the documentation for how system administrators and application
programmers can take advantage of the (still experimental DAX) feature.
-----BEGIN PGP SIGNATURE-----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=rS19
-----END PGP SIGNATURE-----
Merge tag 'vfs-5.8-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull DAX updates part one from Darrick Wong:
"After many years of LKML-wrangling about how to enable programs to
query and influence the file data access mode (DAX) when a filesystem
resides on storage devices such as persistent memory, Ira Weiny has
emerged with a proposed set of standard behaviors that has not been
shot down by anyone! We're more or less standardizing on the current
XFS behavior and adapting ext4 to do the same.
This is the first of a handful pull requests that will make ext4 and
XFS present a consistent interface for user programs that care about
DAX. We add a statx attribute that programs can check to see if DAX is
enabled on a particular file. Then, we update the DAX documentation to
spell out the user-visible behaviors that filesystems will guarantee
(until the next storage industry shakeup). The on-disk inode flag has
been in XFS for a few years now.
Summary:
- Clean up io_is_direct.
- Add a new statx flag to indicate when file data access is being
done via DAX (as opposed to the page cache).
- Update the documentation for how system administrators and
application programmers can take advantage of the (still
experimental DAX) feature"
Link: https://lore.kernel.org/lkml/20200505002016.1085071-1-ira.weiny@intel.com/
* tag 'vfs-5.8-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
Documentation/dax: Update Usage section
fs/stat: Define DAX statx attribute
fs: Remove unneeded IS_DAX() check in io_is_direct()
-----BEGIN PGP SIGNATURE-----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=A/qA
-----END PGP SIGNATURE-----
Merge tag 'for-5.8/io_uring-2020-06-01' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe:
"A relatively quiet round, mostly just fixes and code improvements. In
particular:
- Make statx just use the generic statx handler, instead of open
coding it. We don't need that anymore, as we always call it async
safe (Bijan)
- Enable closing of the ring itself. Also fixes O_PATH closure (me)
- Properly name completion members (me)
- Batch reap of dead file registrations (me)
- Allow IORING_OP_POLL with double waitqueues (me)
- Add tee(2) support (Pavel)
- Remove double off read (Pavel)
- Fix overflow cancellations (Pavel)
- Improve CQ timeouts (Pavel)
- Async defer drain fixes (Pavel)
- Add support for enabling/disabling notifications on a registered
eventfd (Stefano)
- Remove dead state parameter (Xiaoguang)
- Disable SQPOLL submit on dying ctx (Xiaoguang)
- Various code cleanups"
* tag 'for-5.8/io_uring-2020-06-01' of git://git.kernel.dk/linux-block: (29 commits)
io_uring: fix overflowed reqs cancellation
io_uring: off timeouts based only on completions
io_uring: move timeouts flushing to a helper
statx: hide interfaces no longer used by io_uring
io_uring: call statx directly
statx: allow system call to be invoked from io_uring
io_uring: add io_statx structure
io_uring: get rid of manual punting in io_close
io_uring: separate DRAIN flushing into a cold path
io_uring: don't re-read sqe->off in timeout_prep()
io_uring: simplify io_timeout locking
io_uring: fix flush req->refs underflow
io_uring: don't submit sqes when ctx->refs is dying
io_uring: async task poll trigger cleanup
io_uring: add tee(2) support
splice: export do_tee()
io_uring: don't repeat valid flag list
io_uring: rename io_file_put()
io_uring: remove req->needs_fixed_files
io_uring: cleanup io_poll_remove_one() logic
...
The io_uring interfaces have been replaced by do_statx() and are no
longer needed.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is a prepatory patch to allow io_uring to invoke statx directly.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Determining whether a path or file descriptor refers to a mountpoint (or
more precisely a mount root) is not trivial using current tools.
Add a flag to statx that indicates whether the path or fd refers to the
root of a mount or not.
Cc: linux-api@vger.kernel.org
Cc: linux-man@vger.kernel.org
Reported-by: Lennart Poettering <mzxreary@0pointer.de>
Reported-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Systemd is hacking around to get it and it's trivial to add to statx, so...
Cc: linux-api@vger.kernel.org
Cc: linux-man@vger.kernel.org
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
IS_NOATIME(inode) is defined as __IS_FLG(inode, SB_RDONLY|SB_NOATIME), so
generic_fillattr() will clear STATX_ATIME from the result_mask if the super
block is marked read only.
This was probably not the intention, so fix to only clear STATX_ATIME if
the fs doesn't support atime at all.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Constants of the *_ALL type can be actively harmful due to the fact that
developers will usually fail to consider the possible effects of future
changes to the definition.
Deprecate STATX_ALL in the uapi, while no damage has been done yet.
We could keep something like this around in the kernel, but there's
actually no point, since all filesystems should be explicitly checking
flags that they support and not rely on the VFS masking unknown ones out: a
flag could be known to the VFS, yet not known to the filesystem.
Cc: David Howells <dhowells@redhat.com>
Cc: linux-api@vger.kernel.org
Cc: linux-man@vger.kernel.org
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
In order for users to determine if a file is currently operating in DAX
state (effective DAX). Define a statx attribute value and set that
attribute if the effective DAX flag is set.
To go along with this we propose the following addition to the statx man
page:
STATX_ATTR_DAX
The file is in the DAX (cpu direct access) state. DAX state
attempts to minimize software cache effects for both I/O and
memory mappings of this file. It requires a file system which
has been configured to support DAX.
DAX generally assumes all accesses are via cpu load / store
instructions which can minimize overhead for small accesses, but
may adversely affect cpu utilization for large transfers.
File I/O is done directly to/from user-space buffers and memory
mapped I/O may be performed with direct memory mappings that
bypass kernel page cache.
While the DAX property tends to result in data being transferred
synchronously, it does not give the same guarantees of O_SYNC
where data and the necessary metadata are transferred together.
A DAX file may support being mapped with the MAP_SYNC flag,
which enables a program to use CPU cache flush instructions to
persist CPU store operations without an explicit fsync(2). See
mmap(2) for more information.
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
To implement an async stat, we need to provide the flags mapping and
the statx user copy. Make them available internally, through
fs/internal.h.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
generic_fillattr is an optional helper that isn't used by all file
systems, move handling purely based on inode flags to vfs_getattr_nosec,
which is common code.
This fixes setting this flag for file systems not using generic_fillattr
like xfs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We have four generations of stat() syscalls:
- the oldstat syscalls that are only used on the older architectures
- the newstat family that is used on all 64-bit architectures but
lacked support for large files on 32-bit architectures.
- the stat64 family that is used mostly on 32-bit architectures to
replace newstat
- statx() to replace all of the above, adding 64-bit timestamps among
other things.
We already compile stat64 only on those architectures that need it,
but newstat is always built, including on those that don't reference
it. This adds a new __ARCH_WANT_NEW_STAT symbol along the lines of
__ARCH_WANT_OLD_STAT and __ARCH_WANT_STAT64 to control compilation of
newstat. All architectures that need it use an explict define, the
others now get a little bit smaller, and future architecture (including
64-bit targets) won't ever see it.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Using the do_readlinkat() helper removes an in-kernel call to the
sys_readlinkat() syscall.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Provide helper __inode_get_bytes() which assumes i_lock is already
acquired. Quota code will need this to be able to use i_lock to protect
consistency of quota accounting information and inode usage.
Signed-off-by: Jan Kara <jack@suse.cz>
Pull fs/compat.c cleanups from Al Viro:
"More moving of compat syscalls from fs/compat.c to fs/*.c where the
native counterparts live.
And death to compat_sys_getdents64() - the only architecture that used
to need it was ia64, and _that_ has lost biarch support quite a few
years ago"
* 'work.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs/compat.c: trim unused includes
move compat_rw_copy_check_uvector() over to fs/read_write.c
fhandle: move compat syscalls from compat.c
open: move compat syscalls from compat.c
stat: move compat syscalls from compat.c
fcntl: move compat syscalls from compat.c
readdir: move compat syscalls from compat.c
statfs: move compat syscalls from compat.c
utimes: move compat syscalls from compat.c
move compat select-related syscalls to fs/select.c
Remove compat_sys_getdents64()
The change in commit 1e2f82d1e9 ("statx: Kill fd-with-NULL-path
support in favour of AT_EMPTY_PATH") to error on a NULL pathname to
statx() is inconsistent.
It results in the error EINVAL for a NULL pathname. Other system calls
with similar APIs (fchownat(), fstatat(), linkat()), return EFAULT.
The solution is simply to remove the EINVAL check. As I already pointed
out in [1], user_path_at*() and filename_lookup() will handle the NULL
pathname as per the other APIs, to correctly produce the error EFAULT.
[1] https://lkml.org/lkml/2017/4/26/561
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the new statx() syscall, the following both allow the attributes of
the file attached to a file descriptor to be retrieved:
statx(dfd, NULL, 0, ...);
and:
statx(dfd, "", AT_EMPTY_PATH, ...);
Change the code to reject the first option, though this means copying
the path and engaging pathwalk for the fstat() equivalent. dfd can be a
non-directory provided path is "".
[ The timing of this isn't wonderful, but applying this now before we
have statx() in any released kernel, before anybody starts using the
NULL special case. - Linus ]
Fixes: a528d35e8b ("statx: Add a system call to make enhanced file info available")
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric Sandeen <sandeen@sandeen.net>
cc: fstests@vger.kernel.org
cc: linux-api@vger.kernel.org
cc: linux-man@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Include a mask in struct stat to indicate which bits of stx_attributes the
filesystem actually supports.
This would also be useful if we add another system call that allows you to
do a 'bulk attribute set' and pass in a statx struct with the masks
appropriately set to say what you want to set.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reserve the top bit of the mask for future expansion of the statx struct
and give an error if statx() sees it set. All the other bits are ignored
if we see them set but don't support the bit; we just clear the bit in the
returned mask.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
I found that statx() was significantly slower than stat(). As a
microbenchmark, I compared 10,000,000 invocations of fstat() on a tmpfs
file to the same with statx() passed a NULL path:
$ time ./stat_benchmark
real 0m1.464s
user 0m0.275s
sys 0m1.187s
$ time ./statx_benchmark
real 0m5.530s
user 0m0.281s
sys 0m5.247s
statx is expected to be a little slower than stat because struct statx
is larger than struct stat, but not by *that* much. It turns out that
most of the overhead was in copying struct statx to userspace, mostly in
all the stac/clac instructions that got generated for each __put_user()
call. (This was on x86_64, but some other architectures, e.g. arm64,
have something similar now too.)
stat() instead initializes its struct on the stack and copies it to
userspace with a single call to copy_to_user(). This turns out to be
much faster, and changing statx to do this makes it almost as fast as
stat:
$ time ./statx_benchmark
real 0m1.624s
user 0m0.270s
sys 0m1.354s
For zeroing the reserved fields, start by zeroing the full struct with
memset. This makes it clear that every byte copied to userspace is
initialized, even implicit padding bytes (though there are none
currently). In the scenarios I tested, it also performed the same as a
designated initializer. Manually initializing each field was still
slightly faster, but would have been more error-prone and less
verifiable.
Also rename statx_set_result() to cp_statx() for consistency with
cp_old_stat() et al., and make it noinline so that struct statx doesn't
add to the stack usage during the main portion of the syscall execution.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
