Currently we only support idmapped mounts for filesystems mounted
without an idmapping. This was a conscious decision mentioned in
multiple places (cf. e.g. [1]).
As explained at length in [3] it is perfectly fine to extend support for
idmapped mounts to filesystem's mounted with an idmapping should the
need arise. The need has been there for some time now. Various container
projects in userspace need this to run unprivileged and nested
unprivileged containers (cf. [2]).
Before we can port any filesystem that is mountable with an idmapping to
support idmapped mounts we need to first extend the mapping helpers to
account for the filesystem's idmapping. This again, is explained at
length in our documentation at [3] but I'll give an overview here again.
Currently, the low-level mapping helpers implement the remapping
algorithms described in [3] in a simplified manner. Because we could
rely on the fact that all filesystems supporting idmapped mounts are
mounted without an idmapping the translation step from or into the
filesystem idmapping could be skipped.
In order to support idmapped mounts of filesystem's mountable with an
idmapping the translation step we were able to skip before cannot be
skipped anymore. A filesystem mounted with an idmapping is very likely
to not use an identity mapping and will instead use a non-identity
mapping. So the translation step from or into the filesystem's idmapping
in the remapping algorithm cannot be skipped for such filesystems. More
details with examples can be found in [3].
This patch adds a few new and prepares some already existing low-level
mapping helpers to perform the full translation algorithm explained in
[3]. The low-level helpers can be written in a way that they only
perform the additional translation step when the filesystem is indeed
mounted with an idmapping.
If the low-level helpers detect that they are not dealing with an
idmapped mount they can simply return the relevant k{g,u}id unchanged;
no remapping needs to be performed at all. The no_idmapping() helper
detects whether the shortcut can be used.
If the low-level helpers detected that they are dealing with an idmapped
mount but the underlying filesystem is mounted without an idmapping we
can rely on the previous shorcut and can continue to skip the
translation step from or into the filesystem's idmapping.
These checks guarantee that only the minimal amount of work is
performed. As before, if idmapped mounts aren't used the low-level
helpers are idempotent and no work is performed at all.
This patch adds the helpers mapped_k{g,u}id_fs() and
mapped_k{g,u}id_user(). Following patches will port all places to
replace the old k{g,u}id_into_mnt() and k{g,u}id_from_mnt() with these
two new helpers. After the conversion is done k{g,u}id_into_mnt() and
k{g,u}id_from_mnt() will be removed. This also concludes the renaming of
the mapping helpers we started in [4]. Now, all mapping helpers will
started with the "mapped_" prefix making everything nice and consistent.
The mapped_k{g,u}id_fs() helpers replace the k{g,u}id_into_mnt()
helpers. They are to be used when k{g,u}ids are to be mapped from the
vfs, e.g. from from struct inode's i_{g,u}id. Conversely, the
mapped_k{g,u}id_user() helpers replace the k{g,u}id_from_mnt() helpers.
They are to be used when k{g,u}ids are to be written to disk, e.g. when
entering from a system call to change ownership of a file.
This patch only introduces the helpers. It doesn't yet convert the
relevant places to account for filesystem mounted with an idmapping.
[1]: commit 2ca4dcc490 ("fs/mount_setattr: tighten permission checks")
[2]: https://github.com/containers/podman/issues/10374
[3]: Documentations/filesystems/idmappings.rst
[4]: commit a65e58e791 ("fs: document and rename fsid helpers")
Link: https://lore.kernel.org/r/20211123114227.3124056-5-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-5-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-5-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Pull vhost,virtio,vdpa bugfixes from Michael Tsirkin:
"Misc fixes all over the place.
Revert of virtio used length validation series: the approach taken
does not seem to work, breaking too many guests in the process. We'll
need to do length validation using some other approach"
[ This merge also ends up reverting commit f7a36b03a7 ("vsock/virtio:
suppress used length validation"), which came in through the
networking tree in the meantime, and was part of that whole used
length validation series - Linus ]
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
vdpa_sim: avoid putting an uninitialized iova_domain
vhost-vdpa: clean irqs before reseting vdpa device
virtio-blk: modify the value type of num in virtio_queue_rq()
vhost/vsock: cleanup removing `len` variable
vhost/vsock: fix incorrect used length reported to the guest
Revert "virtio_ring: validate used buffer length"
Revert "virtio-net: don't let virtio core to validate used length"
Revert "virtio-blk: don't let virtio core to validate used length"
Revert "virtio-scsi: don't let virtio core to validate used buffer length"
Pull x86 build fix from Thomas Gleixner:
"A single fix for a missing __init annotation of prepare_command_line()"
* tag 'x86-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Mark prepare_command_line() __init
Pull scheduler fix from Thomas Gleixner:
"A single scheduler fix to ensure that there is no stale KASAN shadow
state left on the idle task's stack when a CPU is brought up after it
was brought down before"
* tag 'sched-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/scs: Reset task stack state in bringup_cpu()
Pull perf fix from Thomas Gleixner:
"A single fix for perf to prevent it from sending SIGTRAP to another
task from a trace point event as it's not possible to deliver a
synchronous signal to a different task from there"
* tag 'perf-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Ignore sigtrap for tracepoints destined for other tasks
Pull locking fixes from Thomas Gleixner:
"Two regression fixes for reader writer semaphores:
- Plug a race in the lock handoff which is caused by inconsistency of
the reader and writer path and can lead to corruption of the
underlying counter.
- down_read_trylock() is suboptimal when the lock is contended and
multiple readers trylock concurrently. That's due to the initial
value being read non-atomically which results in at least two
compare exchange loops. Making the initial readout atomic reduces
this significantly. Whith 40 readers by 11% in a benchmark which
enforces contention on mmap_sem"
* tag 'locking-urgent-2021-11-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Optimize down_read_trylock() under highly contended case
locking/rwsem: Make handoff bit handling more consistent
Pull another tracing fix from Steven Rostedt:
"Fix the fix of pid filtering
The setting of the pid filtering flag tested the "trace only this pid"
case twice, and ignored the "trace everything but this pid" case.
The 5.15 kernel does things a little differently due to the new sparse
pid mask introduced in 5.16, and as the bug was discovered running the
5.15 kernel, and the first fix was initially done for that kernel,
that fix handled both cases (only pid and all but pid), but the
forward port to 5.16 created this bug"
* tag 'trace-v5.16-rc2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Test the 'Do not trace this pid' case in create event
Pull ksmbd fixes from Steve French:
"Five ksmbd server fixes, four of them for stable:
- memleak fix
- fix for default data stream on filesystems that don't support xattr
- error logging fix
- session setup fix
- minor doc cleanup"
* tag '5.16-rc2-ksmbd-fixes' of git://git.samba.org/ksmbd:
ksmbd: fix memleak in get_file_stream_info()
ksmbd: contain default data stream even if xattr is empty
ksmbd: downgrade addition info error msg to debug in smb2_get_info_sec()
docs: filesystem: cifs: ksmbd: Fix small layout issues
ksmbd: Fix an error handling path in 'smb2_sess_setup()'
Use the architecture independent Kconfig option PAGE_SIZE_LESS_THAN_64KB
to indicate that VMXNET3 requires a page size smaller than 64kB.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
NTFS_RW code allocates page size dependent arrays on the stack. This
results in build failures if the page size is 64k or larger.
fs/ntfs/aops.c: In function 'ntfs_write_mst_block':
fs/ntfs/aops.c:1311:1: error:
the frame size of 2240 bytes is larger than 2048 bytes
Since commit f22969a660 ("powerpc/64s: Default to 64K pages for 64 bit
book3s") this affects ppc:allmodconfig builds, but other architectures
supporting page sizes of 64k or larger are also affected.
Increasing the maximum frame size for affected architectures just to
silence this error does not really help. The frame size would have to
be set to a really large value for 256k pages. Also, a large frame size
could potentially result in stack overruns in this code and elsewhere
and is therefore not desirable. Make NTFS_RW dependent on page sizes
smaller than 64k instead.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
NTFS_RW and VMXNET3 require a page size smaller than 64kB. Add generic
Kconfig option for use outside architecture code to avoid architecture
specific Kconfig options in that code.
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Anton Altaparmakov <anton@tuxera.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When creating a new event (via a module, kprobe, eprobe, etc), the
descriptors that are created must add flags for pid filtering if an
instance has pid filtering enabled, as the flags are used at the time the
event is executed to know if pid filtering should be done or not.
The "Only trace this pid" case was added, but a cut and paste error made
that case checked twice, instead of checking the "Trace all but this pid"
case.
Link: https://lore.kernel.org/all/202111280401.qC0z99JB-lkp@intel.com/
Fixes: 6cb206508b ("tracing: Check pid filtering when creating events")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pull xfs fixes from Darrick Wong:
"Fixes for a resource leak and a build robot complaint about totally
dead code:
- Fix buffer resource leak that could lead to livelock on corrupt fs.
- Remove unused function xfs_inew_wait to shut up the build robots"
* tag 'xfs-5.16-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: remove xfs_inew_wait
xfs: Fix the free logic of state in xfs_attr_node_hasname
Pull iomap fixes from Darrick Wong:
"A single iomap bug fix and a cleanup for 5.16-rc2.
The bug fix changes how iomap deals with reading from an inline data
region -- whereas the current code (incorrectly) lets the iomap read
iter try for more bytes after reading the inline region (which zeroes
the rest of the page!) and hopes the next iteration terminates, we
surveyed the inlinedata implementations and realized that all
inlinedata implementations also require that the inlinedata region end
at EOF, so we can simply terminate the read.
The second patch documents these assumptions in the code so that
they're not subtle implications anymore, and cleans up some of the
grosser parts of that function.
Summary:
- Fix an accounting problem where unaligned inline data reads can run
off the end of the read iomap iterator. iomap has historically
required that inline data mappings only exist at the end of a file,
though this wasn't documented anywhere.
- Document iomap_read_inline_data and change its return type to be
appropriate for the information that it's actually returning"
* tag 'iomap-5.16-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
iomap: iomap_read_inline_data cleanup
iomap: Fix inline extent handling in iomap_readpage
Pull tracing fixes from Steven Rostedt:
"Two fixes to event pid filtering:
- Make sure newly created events reflect the current state of pid
filtering
- Take pid filtering into account when recording trigger events.
(Also clean up the if statement to be cleaner)"
* tag 'trace-v5.16-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix pid filtering when triggers are attached
tracing: Check pid filtering when creating events
Pull more io_uring fixes from Jens Axboe:
"The locking fixup that was applied earlier this rc has both a deadlock
and IRQ safety issue, let's get that ironed out before -rc3. This
contains:
- Link traversal locking fix (Pavel)
- Cancelation fix (Pavel)
- Relocate cond_resched() for huge buffer chain freeing, avoiding a
softlockup warning (Ye)
- Fix timespec validation (Ye)"
* tag 'io_uring-5.16-2021-11-27' of git://git.kernel.dk/linux-block:
io_uring: Fix undefined-behaviour in io_issue_sqe
io_uring: fix soft lockup when call __io_remove_buffers
io_uring: fix link traversal locking
io_uring: fail cancellation for EXITING tasks
Christian Brauner
Linus Torvalds
Guenter Roeck
Steven Rostedt (VMware)