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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
- More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
Raghav.
- zsmalloc performance improvements from Sergey Senozhatsky.
- Yue Zhao has found and fixed some data race issues around the
alteration of memcg userspace tunables.
- VFS rationalizations from Christoph Hellwig:
- removal of most of the callers of write_one_page()
- make __filemap_get_folio()'s return value more useful
- Luis Chamberlain has changed tmpfs so it no longer requires swap
backing. Use `mount -o noswap'.
- Qi Zheng has made the slab shrinkers operate locklessly, providing
some scalability benefits.
- Keith Busch has improved dmapool's performance, making part of its
operations O(1) rather than O(n).
- Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
permitting userspace to wr-protect anon memory unpopulated ptes.
- Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
rather than exclusive, and has fixed a bunch of errors which were
caused by its unintuitive meaning.
- Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
which causes minor faults to install a write-protected pte.
- Vlastimil Babka has done some maintenance work on vma_merge():
cleanups to the kernel code and improvements to our userspace test
harness.
- Cleanups to do_fault_around() by Lorenzo Stoakes.
- Mike Rapoport has moved a lot of initialization code out of various
mm/ files and into mm/mm_init.c.
- Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
DRM, but DRM doesn't use it any more.
- Lorenzo has also coverted read_kcore() and vread() to use iterators
and has thereby removed the use of bounce buffers in some cases.
- Lorenzo has also contributed further cleanups of vma_merge().
- Chaitanya Prakash provides some fixes to the mmap selftesting code.
- Matthew Wilcox changes xfs and afs so they no longer take sleeping
locks in ->map_page(), a step towards RCUification of pagefaults.
- Suren Baghdasaryan has improved mmap_lock scalability by switching to
per-VMA locking.
- Frederic Weisbecker has reworked the percpu cache draining so that it
no longer causes latency glitches on cpu isolated workloads.
- Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
logic.
- Liu Shixin has changed zswap's initialization so we no longer waste a
chunk of memory if zswap is not being used.
- Yosry Ahmed has improved the performance of memcg statistics
flushing.
- David Stevens has fixed several issues involving khugepaged,
userfaultfd and shmem.
- Christoph Hellwig has provided some cleanup work to zram's IO-related
code paths.
- David Hildenbrand has fixed up some issues in the selftest code's
testing of our pte state changing.
- Pankaj Raghav has made page_endio() unneeded and has removed it.
- Peter Xu contributed some rationalizations of the userfaultfd
selftests.
- Yosry Ahmed has fixed an issue around memcg's page recalim
accounting.
- Chaitanya Prakash has fixed some arm-related issues in the
selftests/mm code.
- Longlong Xia has improved the way in which KSM handles hwpoisoned
pages.
- Peter Xu fixes a few issues with uffd-wp at fork() time.
- Stefan Roesch has changed KSM so that it may now be used on a
per-process and per-cgroup basis.
* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
shmem: restrict noswap option to initial user namespace
mm/khugepaged: fix conflicting mods to collapse_file()
sparse: remove unnecessary 0 values from rc
mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
maple_tree: fix allocation in mas_sparse_area()
mm: do not increment pgfault stats when page fault handler retries
zsmalloc: allow only one active pool compaction context
selftests/mm: add new selftests for KSM
mm: add new KSM process and sysfs knobs
mm: add new api to enable ksm per process
mm: shrinkers: fix debugfs file permissions
mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
migrate_pages_batch: fix statistics for longterm pin retry
userfaultfd: use helper function range_in_vma()
lib/show_mem.c: use for_each_populated_zone() simplify code
mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
fs/buffer: convert create_page_buffers to folio_create_buffers
fs/buffer: add folio_create_empty_buffers helper
...
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During reclaim, we keep track of pages reclaimed from other means than
LRU-based reclaim through scan_control->reclaim_state->reclaimed_slab,
which we stash a pointer to in current task_struct.
However, we keep track of more than just reclaimed slab pages through
this. We also use it for clean file pages dropped through pruned inodes,
and xfs buffer pages freed. Rename reclaimed_slab to reclaimed, and add a
helper function that wraps updating it through current, so that future
changes to this logic are contained within include/linux/swap.h.
Link: https://lkml.kernel.org/r/20230413104034.1086717-4-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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relatime also updates atime if the previous atime is equal to one or
both of the ctime and mtime; a non-strict interpretation of "earlier
than" and "younger than" in the comments allows this, but for clarity,
this makes it explicit.
Pointed out by "epiii2" and "ctrl-alt-delor" in
https://unix.stackexchange.com/q/740862/86440.
Signed-off-by: Stephen Kitt <steve@sk2.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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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 256c8aed2b42 ("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
...
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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Convert to struct mnt_idmap.
Remove legacy file_mnt_user_ns() and mnt_user_ns().
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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|
Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("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>
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The file locking definitions have lived in fs.h since the dawn of time,
but they are only used by a small subset of the source files that
include it.
Move the file locking definitions to a new header file, and add the
appropriate #include directives to the source files that need them. By
doing this we trim down fs.h a bit and limit the amount of rebuilding
that has to be done when we make changes to the file locking APIs.
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: Steve French <stfrench@microsoft.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping
Pull vfsuid updates from Christian Brauner:
"Last cycle we introduced the vfs{g,u}id_t types and associated helpers
to gain type safety when dealing with idmapped mounts. That initial
work already converted a lot of places over but there were still some
left,
This converts all remaining places that still make use of non-type
safe idmapping helpers to rely on the new type safe vfs{g,u}id based
helpers.
Afterwards it removes all the old non-type safe helpers"
* tag 'fs.vfsuid.conversion.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
fs: remove unused idmapping helpers
ovl: port to vfs{g,u}id_t and associated helpers
fuse: port to vfs{g,u}id_t and associated helpers
ima: use type safe idmapping helpers
apparmor: use type safe idmapping helpers
caps: use type safe idmapping helpers
fs: use type safe idmapping helpers
mnt_idmapping: add missing helpers
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping
Pull setgid inheritance updates from Christian Brauner:
"This contains the work to make setgid inheritance consistent between
modifying a file and when changing ownership or mode as this has been
a repeated source of very subtle bugs. The gist is that we perform the
same permission checks in the write path as we do in the ownership and
mode changing paths after this series where we're currently doing
different things.
We've already made setgid inheritance a lot more consistent and
reliable in the last releases by moving setgid stripping from the
individual filesystems up into the vfs. This aims to make the logic
even more consistent and easier to understand and also to fix
long-standing overlayfs setgid inheritance bugs. Miklos was nice
enough to just let me carry the trivial overlayfs patches from Amir
too.
Below is a more detailed explanation how the current difference in
setgid handling lead to very subtle bugs exemplified via overlayfs
which is a victim of the current rules. I hope this explains why I
think taking the regression risk here is worth it.
A long while ago I found a few setgid inheritance bugs in overlayfs in
the write path in certain conditions. Amir recently picked this back
up in [1] and I jumped on board to fix this more generally.
On the surface all that overlayfs would need to fix setgid inheritance
would be to call file_remove_privs() or file_modified() but actually
that isn't enough because the setgid inheritance api is wildly
inconsistent in that area.
Before this pr setgid stripping in file_remove_privs()'s old
should_remove_suid() helper was inconsistent with other parts of the
vfs. Specifically, it only raises ATTR_KILL_SGID if the inode is
S_ISGID and S_IXGRP but not if the inode isn't in the caller's groups
and the caller isn't privileged over the inode although we require
this already in setattr_prepare() and setattr_copy() and so all
filesystem implement this requirement implicitly because they have to
use setattr_{prepare,copy}() anyway.
But the inconsistency shows up in setgid stripping bugs for overlayfs
in xfstests (e.g., generic/673, generic/683, generic/685, generic/686,
generic/687). For example, we test whether suid and setgid stripping
works correctly when performing various write-like operations as an
unprivileged user (fallocate, reflink, write, etc.):
echo "Test 1 - qa_user, non-exec file $verb"
setup_testfile
chmod a+rws $junk_file
commit_and_check "$qa_user" "$verb" 64k 64k
The test basically creates a file with 6666 permissions. While the
file has the S_ISUID and S_ISGID bits set it does not have the S_IXGRP
set.
On a regular filesystem like xfs what will happen is:
sys_fallocate()
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> setattr_copy()
In should_remove_suid() we can see that ATTR_KILL_SUID is raised
unconditionally because the file in the test has S_ISUID set.
But we also see that ATTR_KILL_SGID won't be set because while the
file is S_ISGID it is not S_IXGRP (see above) which is a condition for
ATTR_KILL_SGID being raised.
So by the time we call notify_change() we have attr->ia_valid set to
ATTR_KILL_SUID | ATTR_FORCE.
Now notify_change() sees that ATTR_KILL_SUID is set and does:
ia_valid = attr->ia_valid |= ATTR_MODE
attr->ia_mode = (inode->i_mode & ~S_ISUID);
which means that when we call setattr_copy() later we will definitely
update inode->i_mode. Note that attr->ia_mode still contains S_ISGID.
Now we call into the filesystem's ->setattr() inode operation which
will end up calling setattr_copy(). Since ATTR_MODE is set we will
hit:
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
if (!vfsgid_in_group_p(vfsgid) &&
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
mode &= ~S_ISGID;
inode->i_mode = mode;
}
and since the caller in the test is neither capable nor in the group
of the inode the S_ISGID bit is stripped.
But assume the file isn't suid then ATTR_KILL_SUID won't be raised
which has the consequence that neither the setgid nor the suid bits
are stripped even though it should be stripped because the inode isn't
in the caller's groups and the caller isn't privileged over the inode.
If overlayfs is in the mix things become a bit more complicated and
the bug shows up more clearly.
When e.g., ovl_setattr() is hit from ovl_fallocate()'s call to
file_remove_privs() then ATTR_KILL_SUID and ATTR_KILL_SGID might be
raised but because the check in notify_change() is questioning the
ATTR_KILL_SGID flag again by requiring S_IXGRP for it to be stripped
the S_ISGID bit isn't removed even though it should be stripped:
sys_fallocate()
-> vfs_fallocate()
-> ovl_fallocate()
-> file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> ovl_setattr()
/* TAKE ON MOUNTER'S CREDS */
-> ovl_do_notify_change()
-> notify_change()
/* GIVE UP MOUNTER'S CREDS */
/* TAKE ON MOUNTER'S CREDS */
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = attr_force | kill;
-> notify_change()
The fix for all of this is to make file_remove_privs()'s
should_remove_suid() helper perform the same checks as we already
require in setattr_prepare() and setattr_copy() and have
notify_change() not pointlessly requiring S_IXGRP again. It doesn't
make any sense in the first place because the caller must calculate
the flags via should_remove_suid() anyway which would raise
ATTR_KILL_SGID
Note that some xfstests will now fail as these patches will cause the
setgid bit to be lost in certain conditions for unprivileged users
modifying a setgid file when they would've been kept otherwise. I
think this risk is worth taking and I explained and mentioned this
multiple times on the list [2].
Enforcing the rules consistently across write operations and
chmod/chown will lead to losing the setgid bit in cases were it
might've been retained before.
While I've mentioned this a few times but it's worth repeating just to
make sure that this is understood. For the sake of maintainability,
consistency, and security this is a risk worth taking.
If we really see regressions for workloads the fix is to have special
setgid handling in the write path again with different semantics from
chmod/chown and possibly additional duct tape for overlayfs. I'll
update the relevant xfstests with if you should decide to merge this
second setgid cleanup.
Before that people should be aware that there might be failures for
fstests where unprivileged users modify a setgid file"
Link: https://lore.kernel.org/linux-fsdevel/20221003123040.900827-1-amir73il@gmail.com [1]
Link: https://lore.kernel.org/linux-fsdevel/20221122142010.zchf2jz2oymx55qi@wittgenstein [2]
* tag 'fs.ovl.setgid.v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
fs: use consistent setgid checks in is_sxid()
ovl: remove privs in ovl_fallocate()
ovl: remove privs in ovl_copyfile()
attr: use consistent sgid stripping checks
attr: add setattr_should_drop_sgid()
fs: move should_remove_suid()
attr: add in_group_or_capable()
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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>
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Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Currently setgid stripping in file_remove_privs()'s should_remove_suid()
helper is inconsistent with other parts of the vfs. Specifically, it only
raises ATTR_KILL_SGID if the inode is S_ISGID and S_IXGRP but not if the
inode isn't in the caller's groups and the caller isn't privileged over the
inode although we require this already in setattr_prepare() and
setattr_copy() and so all filesystem implement this requirement implicitly
because they have to use setattr_{prepare,copy}() anyway.
But the inconsistency shows up in setgid stripping bugs for overlayfs in
xfstests (e.g., generic/673, generic/683, generic/685, generic/686,
generic/687). For example, we test whether suid and setgid stripping works
correctly when performing various write-like operations as an unprivileged
user (fallocate, reflink, write, etc.):
echo "Test 1 - qa_user, non-exec file $verb"
setup_testfile
chmod a+rws $junk_file
commit_and_check "$qa_user" "$verb" 64k 64k
The test basically creates a file with 6666 permissions. While the file has
the S_ISUID and S_ISGID bits set it does not have the S_IXGRP set. On a
regular filesystem like xfs what will happen is:
sys_fallocate()
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> setattr_copy()
In should_remove_suid() we can see that ATTR_KILL_SUID is raised
unconditionally because the file in the test has S_ISUID set.
But we also see that ATTR_KILL_SGID won't be set because while the file
is S_ISGID it is not S_IXGRP (see above) which is a condition for
ATTR_KILL_SGID being raised.
So by the time we call notify_change() we have attr->ia_valid set to
ATTR_KILL_SUID | ATTR_FORCE. Now notify_change() sees that
ATTR_KILL_SUID is set and does:
ia_valid = attr->ia_valid |= ATTR_MODE
attr->ia_mode = (inode->i_mode & ~S_ISUID);
which means that when we call setattr_copy() later we will definitely
update inode->i_mode. Note that attr->ia_mode still contains S_ISGID.
Now we call into the filesystem's ->setattr() inode operation which will
end up calling setattr_copy(). Since ATTR_MODE is set we will hit:
if (ia_valid & ATTR_MODE) {
umode_t mode = attr->ia_mode;
vfsgid_t vfsgid = i_gid_into_vfsgid(mnt_userns, inode);
if (!vfsgid_in_group_p(vfsgid) &&
!capable_wrt_inode_uidgid(mnt_userns, inode, CAP_FSETID))
mode &= ~S_ISGID;
inode->i_mode = mode;
}
and since the caller in the test is neither capable nor in the group of the
inode the S_ISGID bit is stripped.
But assume the file isn't suid then ATTR_KILL_SUID won't be raised which
has the consequence that neither the setgid nor the suid bits are stripped
even though it should be stripped because the inode isn't in the caller's
groups and the caller isn't privileged over the inode.
If overlayfs is in the mix things become a bit more complicated and the bug
shows up more clearly. When e.g., ovl_setattr() is hit from
ovl_fallocate()'s call to file_remove_privs() then ATTR_KILL_SUID and
ATTR_KILL_SGID might be raised but because the check in notify_change() is
questioning the ATTR_KILL_SGID flag again by requiring S_IXGRP for it to be
stripped the S_ISGID bit isn't removed even though it should be stripped:
sys_fallocate()
-> vfs_fallocate()
-> ovl_fallocate()
-> file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = ATTR_FORCE | kill;
-> notify_change()
-> ovl_setattr()
// TAKE ON MOUNTER'S CREDS
-> ovl_do_notify_change()
-> notify_change()
// GIVE UP MOUNTER'S CREDS
// TAKE ON MOUNTER'S CREDS
-> vfs_fallocate()
-> xfs_file_fallocate()
-> file_modified()
-> __file_remove_privs()
-> dentry_needs_remove_privs()
-> should_remove_suid()
-> __remove_privs()
newattrs.ia_valid = attr_force | kill;
-> notify_change()
The fix for all of this is to make file_remove_privs()'s
should_remove_suid() helper to perform the same checks as we already
require in setattr_prepare() and setattr_copy() and have notify_change()
not pointlessly requiring S_IXGRP again. It doesn't make any sense in the
first place because the caller must calculate the flags via
should_remove_suid() anyway which would raise ATTR_KILL_SGID.
While we're at it we move should_remove_suid() from inode.c to attr.c
where it belongs with the rest of the iattr helpers. Especially since it
returns ATTR_KILL_S{G,U}ID flags. We also rename it to
setattr_should_drop_suidgid() to better reflect that it indicates both
setuid and setgid bit removal and also that it returns attr flags.
Running xfstests with this doesn't report any regressions. We should really
try and use consistent checks.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Move the helper from inode.c to attr.c. This keeps the the core of the
set{g,u}id stripping logic in one place when we add follow-up changes.
It is the better place anyway, since should_remove_suid() returns
ATTR_KILL_S{G,U}ID flags.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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In setattr_{copy,prepare}() we need to perform the same permission
checks to determine whether we need to drop the setgid bit or not.
Instead of open-coding it twice add a simple helper the encapsulates the
logic. We will reuse this helpers to make dropping the setgid bit during
write operations more consistent in a follow up patch.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Pull vfs inode update from Al Viro:
"Saner inode_init_always(), also fixing a nilfs problem"
* tag 'pull-inode' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: fix UAF/GPF bug in nilfs_mdt_destroy
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In alloc_inode, inode_init_always() could return -ENOMEM if
security_inode_alloc() fails, which causes inode->i_private
uninitialized. Then nilfs_is_metadata_file_inode() returns
true and nilfs_free_inode() wrongly calls nilfs_mdt_destroy(),
which frees the uninitialized inode->i_private
and leads to crashes(e.g., UAF/GPF).
Fix this by moving security_inode_alloc just prior to
this_cpu_inc(nr_inodes)
Link: https://lkml.kernel.org/r/CAFcO6XOcf1Jj2SeGt=jJV59wmhESeSKpfR0omdFRq+J9nD1vfQ@mail.gmail.com
Reported-by: butt3rflyh4ck <butterflyhuangxx@gmail.com>
Reported-by: Hao Sun <sunhao.th@gmail.com>
Reported-by: Jiacheng Xu <stitch@zju.edu.cn>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This restores the call to inode_has_no_xattr() in the function
__file_remove_privs(). In case the dentry_meeds_remove_privs() returned
0, the function inode_has_no_xattr() was not called.
Signed-off-by: Stefan Roesch <shr@fb.com>
Fixes: faf99b563558 ("fs: add __remove_file_privs() with flags parameter")
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20220816153158.1925040-1-shr@fb.com
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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Pull ceph updates from Ilya Dryomov:
"We have a good pile of various fixes and cleanups from Xiubo, Jeff,
Luis and others, almost exclusively in the filesystem.
Several patches touch files outside of our normal purview to set the
stage for bringing in Jeff's long awaited ceph+fscrypt series in the
near future. All of them have appropriate acks and sat in linux-next
for a while"
* tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client: (27 commits)
libceph: clean up ceph_osdc_start_request prototype
libceph: fix ceph_pagelist_reserve() comment typo
ceph: remove useless check for the folio
ceph: don't truncate file in atomic_open
ceph: make f_bsize always equal to f_frsize
ceph: flush the dirty caps immediatelly when quota is approaching
libceph: print fsid and epoch with osd id
libceph: check pointer before assigned to "c->rules[]"
ceph: don't get the inline data for new creating files
ceph: update the auth cap when the async create req is forwarded
ceph: make change_auth_cap_ses a global symbol
ceph: fix incorrect old_size length in ceph_mds_request_args
ceph: switch back to testing for NULL folio->private in ceph_dirty_folio
ceph: call netfs_subreq_terminated with was_async == false
ceph: convert to generic_file_llseek
ceph: fix the incorrect comment for the ceph_mds_caps struct
ceph: don't leak snap_rwsem in handle_cap_grant
ceph: prevent a client from exceeding the MDS maximum xattr size
ceph: choose auth MDS for getxattr with the Xs caps
ceph: add session already open notify support
...
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git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull setgid updates from Christian Brauner:
"This contains the work to move setgid stripping out of individual
filesystems and into the VFS itself.
Creating files that have both the S_IXGRP and S_ISGID bit raised in
directories that themselves have the S_ISGID bit set requires
additional privileges to avoid security issues.
When a filesystem creates a new inode it needs to take care that the
caller is either in the group of the newly created inode or they have
CAP_FSETID in their current user namespace and are privileged over the
parent directory of the new inode. If any of these two conditions is
true then the S_ISGID bit can be raised for an S_IXGRP file and if not
it needs to be stripped.
However, there are several key issues with the current implementation:
- S_ISGID stripping logic is entangled with umask stripping.
For example, if the umask removes the S_IXGRP bit from the file
about to be created then the S_ISGID bit will be kept.
The inode_init_owner() helper is responsible for S_ISGID stripping
and is called before posix_acl_create(). So we can end up with two
different orderings:
1. FS without POSIX ACL support
First strip umask then strip S_ISGID in inode_init_owner().
In other words, if a filesystem doesn't support or enable POSIX
ACLs then umask stripping is done directly in the vfs before
calling into the filesystem:
2. FS with POSIX ACL support
First strip S_ISGID in inode_init_owner() then strip umask in
posix_acl_create().
In other words, if the filesystem does support POSIX ACLs then
unmask stripping may be done in the filesystem itself when
calling posix_acl_create().
Note that technically filesystems are free to impose their own
ordering between posix_acl_create() and inode_init_owner() meaning
that there's additional ordering issues that influence S_ISGID
inheritance.
(Note that the commit message of commit 1639a49ccdce ("fs: move
S_ISGID stripping into the vfs_*() helpers") gets the ordering
between inode_init_owner() and posix_acl_create() the wrong way
around. I realized this too late.)
- Filesystems that don't rely on inode_init_owner() don't get S_ISGID
stripping logic.
While that may be intentional (e.g. network filesystems might just
defer setgid stripping to a server) it is often just a security
issue.
Note that mandating the use of inode_init_owner() was proposed as
an alternative solution but that wouldn't fix the ordering issues
and there are examples such as afs where the use of
inode_init_owner() isn't possible.
In any case, we should also try the cleaner and generalized
solution first before resorting to this approach.
- We still have S_ISGID inheritance bugs years after the initial
round of S_ISGID inheritance fixes:
e014f37db1a2 ("xfs: use setattr_copy to set vfs inode attributes")
01ea173e103e ("xfs: fix up non-directory creation in SGID directories")
fd84bfdddd16 ("ceph: fix up non-directory creation in SGID directories")
All of this led us to conclude that the current state is too messy.
While we won't be able to make it completely clean as
posix_acl_create() is still a filesystem specific call we can improve
the S_SIGD stripping situation quite a bit by hoisting it out of
inode_init_owner() and into the respective vfs creation operations.
The obvious advantage is that we don't need to rely on individual
filesystems getting S_ISGID stripping right and instead can
standardize the ordering between S_ISGID and umask stripping directly
in the VFS.
A few short implementation notes:
- The stripping logic needs to happen in vfs_*() helpers for the sake
of stacking filesystems such as overlayfs that rely on these
helpers taking care of S_ISGID stripping.
- Security hooks have never seen the mode as it is ultimately seen by
the filesystem because of the ordering issue we mentioned. Nothing
is changed for them. We simply continue to strip the umask before
passing the mode down to the security hooks.
- The following filesystems use inode_init_owner() and thus relied on
S_ISGID stripping: spufs, 9p, bfs, btrfs, ext2, ext4, f2fs,
hfsplus, hugetlbfs, jfs, minix, nilfs2, ntfs3, ocfs2, omfs,
overlayfs, ramfs, reiserfs, sysv, ubifs, udf, ufs, xfs, zonefs,
bpf, tmpfs.
We've audited all callchains as best as we could. More details can
be found in the commit message to 1639a49ccdce ("fs: move S_ISGID
stripping into the vfs_*() helpers")"
* tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
ceph: rely on vfs for setgid stripping
fs: move S_ISGID stripping into the vfs_*() helpers
fs: Add missing umask strip in vfs_tmpfile
fs: add mode_strip_sgid() helper
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Pull folio updates from Matthew Wilcox:
- Fix an accounting bug that made NR_FILE_DIRTY grow without limit
when running xfstests
- Convert more of mpage to use folios
- Remove add_to_page_cache() and add_to_page_cache_locked()
- Convert find_get_pages_range() to filemap_get_folios()
- Improvements to the read_cache_page() family of functions
- Remove a few unnecessary checks of PageError
- Some straightforward filesystem conversions to use folios
- Split PageMovable users out from address_space_operations into
their own movable_operations
- Convert aops->migratepage to aops->migrate_folio
- Remove nobh support (Christoph Hellwig)
* tag 'folio-6.0' of git://git.infradead.org/users/willy/pagecache: (78 commits)
fs: remove the NULL get_block case in mpage_writepages
fs: don't call ->writepage from __mpage_writepage
fs: remove the nobh helpers
jfs: stop using the nobh helper
ext2: remove nobh support
ntfs3: refactor ntfs_writepages
mm/folio-compat: Remove migration compatibility functions
fs: Remove aops->migratepage()
secretmem: Convert to migrate_folio
hugetlb: Convert to migrate_folio
aio: Convert to migrate_folio
f2fs: Convert to filemap_migrate_folio()
ubifs: Convert to filemap_migrate_folio()
btrfs: Convert btrfs_migratepage to migrate_folio
mm/migrate: Add filemap_migrate_folio()
mm/migrate: Convert migrate_page() to migrate_folio()
nfs: Convert to migrate_folio
btrfs: Convert btree_migratepage to migrate_folio
mm/migrate: Convert expected_page_refs() to folio_expected_refs()
mm/migrate: Convert buffer_migrate_page() to buffer_migrate_folio()
...
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inode_insert5 currently looks at I_CREATING to decide whether to insert
the inode into the sb list. This test is a bit ambiguous, as I_CREATING
state is not directly related to that list.
This test is also problematic for some upcoming ceph changes to add
fscrypt support. We need to be able to allocate an inode using new_inode
and insert it into the hash later iff we end up using it, and doing that
now means that we double add it and corrupt the list.
What we really want to know in this test is whether the inode is already
in its superblock list, and then add it if it isn't. Have it test for
list_empty instead and ensure that we always initialize the list by
doing it in inode_init_once. It's only ever removed from the list with
list_del_init, so that should be sufficient.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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This adds a file_modified_async() function to return -EAGAIN if the
request either requires to remove privileges or needs to update the file
modification time. This is required for async buffered writes, so the
request gets handled in the io worker of io-uring.
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-11-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This splits off the functions inode_needs_update_time() and
__file_update_time() from the function file_update_time().
This is required to support async buffered writes.
No intended functional changes in this patch.
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20220623175157.1715274-10-shr@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This adds the func |
