New LOOKUP flag, telling path_lookupat() to act as path_mountpointat().
IOW, traverse mounts at the final point and skip revalidation of the
location where it ends up.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1) no instances of ->d_automount() have ever made use of the "return
ERR_PTR(-EISDIR) if you don't feel like mounting anything" - that's
a rudiment of plans that got superseded before the thing went into
the tree. Despite the comment in follow_automount(), autofs has
never done that.
2) if there's no ->d_automount() in dentry_operations, filesystems
should not set DCACHE_NEED_AUTOMOUNT in the first place. None have
ever done so...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Protection against automount/automount races (two threads hitting the same
referral point at the same time) is based upon do_add_mount() prevention of
identical overmounts - trying to overmount the root of mounted tree with
the same tree fails with -EBUSY. It's unreliable (the other thread might've
mounted something on top of the automount it has triggered) *and* causes
no end of headache for follow_automount() and its caller, since
finish_automount() behaves like do_new_mount() - if the mountpoint to be is
overmounted, it mounts on top what's overmounting it. It's not only wrong
(we want to go into what's overmounting the automount point and quietly
discard what we planned to mount there), it introduces the possibility of
original parent mount getting dropped. That's what 8aef188452 (VFS: Fix
vfsmount overput on simultaneous automount) deals with, but it can't do
anything about the reliability of conflict detection - if something had
been overmounted the other thread's automount (e.g. that other thread
having stepped into automount in mount(2)), we don't get that -EBUSY and
the result is
referral point under automounted NFS under explicit overmount
under another copy of automounted NFS
What we need is finish_automount() *NOT* digging into overmounts - if it
finds one, it should just quietly discard the thing it was asked to mount.
And don't bother with actually crossing into the results of finish_automount() -
the same loop that calls follow_automount() will do that just fine on the
next iteration.
IOW, instead of calling lock_mount() have finish_automount() do it manually,
_without_ the "move into overmount and retry" part. And leave crossing into
the results to the caller of follow_automount(), which simplifies it a lot.
Moral: if you end up with a lot of glue working around the calling conventions
of something, perhaps these calling conventions are simply wrong...
Fixes: 8aef188452 (VFS: Fix vfsmount overput on simultaneous automount)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make to_mnt_ns() static to address the following 'sparse' warning:
fs/namespace.c:1731:22: warning: symbol 'to_mnt_ns' was not declared. Should it be static?
Link: http://lkml.kernel.org/r/20191209234830.156260-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In prepare_namespace(), do_mount() can be used instead of ksys_mount()
as the first and third argument are const strings in the kernel, the
second and fourth argument are passed through anyway, and the fifth
argument is NULL.
In do_mount_root(), ksys_mount() is called with the first and third
argument being already kernelspace strings, which do not need to be
copied over from userspace to kernelspace (again). The second and
fourth arguments are passed through to do_mount() anyway. The fifth
argument, while already residing in kernelspace, needs to be put into
a page of its own. Then, do_mount() can be used instead of
ksys_mount().
Once this is done, there are no in-kernel users to ksys_mount() left,
which can therefore be removed.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Pull misc vfs cleanups from Al Viro:
"No common topic, just three cleanups".
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
make __d_alloc() static
fs/namespace: add __user to open_tree and move_mount syscalls
fs/fnctl: fix missing __user in fcntl_rw_hint()
Thw open_tree and move_mount syscalls take names from the
user, so add the __user to these to ensure the following
warnings from sparse are fixed:
fs/namespace.c:2392:35: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:2392:35: expected char const [noderef] <asn:1> *name
fs/namespace.c:2392:35: got char const *filename
fs/namespace.c:3541:38: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:3541:38: expected char const [noderef] <asn:1> *name
fs/namespace.c:3541:38: got char const *from_pathname
fs/namespace.c:3550:36: warning: incorrect type in argument 2 (different address spaces)
fs/namespace.c:3550:36: expected char const [noderef] <asn:1> *name
fs/namespace.c:3550:36: got char const *to_pathname
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
After do_add_mount() returns success, the caller doesn't hold a
reference to the 'struct mount' anymore. So it's invalid to access it
in mnt_warn_timestamp_expiry().
Fix it by calling mnt_warn_timestamp_expiry() before do_add_mount()
rather than after, and adjusting the warning message accordingly.
Reported-by: syzbot+da4f525235510683d855@syzkaller.appspotmail.com
Fixes: f8b92ba67c ("mount: Add mount warning for impending timestamp expiry")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Merge more updates from Andrew Morton:
- almost all of the rest of -mm
- various other subsystems
Subsystems affected by this patch series:
memcg, misc, core-kernel, lib, checkpatch, reiserfs, fat, fork,
cpumask, kexec, uaccess, kconfig, kgdb, bug, ipc, lzo, kasan, madvise,
cleanups, pagemap
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (77 commits)
arch/sparc/include/asm/pgtable_64.h: fix build
mm: treewide: clarify pgtable_page_{ctor,dtor}() naming
ntfs: remove (un)?likely() from IS_ERR() conditions
IB/hfi1: remove unlikely() from IS_ERR*() condition
xfs: remove unlikely() from WARN_ON() condition
wimax/i2400m: remove unlikely() from WARN*() condition
fs: remove unlikely() from WARN_ON() condition
xen/events: remove unlikely() from WARN() condition
checkpatch: check for nested (un)?likely() calls
hexagon: drop empty and unused free_initrd_mem
mm: factor out common parts between MADV_COLD and MADV_PAGEOUT
mm: introduce MADV_PAGEOUT
mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM
mm: introduce MADV_COLD
mm: untag user pointers in mmap/munmap/mremap/brk
vfio/type1: untag user pointers in vaddr_get_pfn
tee/shm: untag user pointers in tee_shm_register
media/v4l2-core: untag user pointers in videobuf_dma_contig_user_get
drm/radeon: untag user pointers in radeon_gem_userptr_ioctl
drm/amdgpu: untag user pointers
...
This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.
In copy_mount_options a user address is being subtracted from TASK_SIZE.
If the address is lower than TASK_SIZE, the size is calculated to not
allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
However if the address is tagged, then the size will be calculated
incorrectly.
Untag the address before subtracting.
Link: http://lkml.kernel.org/r/1de225e4a54204bfd7f25dac2635e31aa4aa1d90.1563904656.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQSQHSd0lITzzeNWNm3h3BK/laaZPAUCXYod6wAKCRDh3BK/laaZ
PG3fAP9WXuvUeYh3X7ThQPa2D33VCIMJRd6t+1TVSSc/H8P3dAD/ehN5HIWjnmzz
iZFc3zDtO9UCJUe23IZomblxOQbu6Qk=
=I0S2
-----END PGP SIGNATURE-----
Merge tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse updates from Miklos Szeredi:
- Continue separating the transport (user/kernel communication) and the
filesystem layers of fuse. Getting rid of most layering violations
will allow for easier cleanup and optimization later on.
- Prepare for the addition of the virtio-fs filesystem. The actual
filesystem will be introduced by a separate pull request.
- Convert to new mount API.
- Various fixes, optimizations and cleanups.
* tag 'fuse-update-5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (55 commits)
fuse: Make fuse_args_to_req static
fuse: fix memleak in cuse_channel_open
fuse: fix beyond-end-of-page access in fuse_parse_cache()
fuse: unexport fuse_put_request
fuse: kmemcg account fs data
fuse: on 64-bit store time in d_fsdata directly
fuse: fix missing unlock_page in fuse_writepage()
fuse: reserve byteswapped init opcodes
fuse: allow skipping control interface and forced unmount
fuse: dissociate DESTROY from fuseblk
fuse: delete dentry if timeout is zero
fuse: separate fuse device allocation and installation in fuse_conn
fuse: add fuse_iqueue_ops callbacks
fuse: extract fuse_fill_super_common()
fuse: export fuse_dequeue_forget() function
fuse: export fuse_get_unique()
fuse: export fuse_send_init_request()
fuse: export fuse_len_args()
fuse: export fuse_end_request()
fuse: fix request limit
...
This series from Deepa Dinamani adds a per-superblock minimum/maximum
timestamp limit for a file system, and clamps timestamps as they are
written, to avoid random behavior from integer overflow as well as having
different time stamps on disk vs in memory.
At mount time, a warning is now printed for any file system that can
represent current timestamps but not future timestamps more than 30
years into the future, similar to the arbitrary 30 year limit that was
added to settimeofday().
This was picked as a compromise to warn users to migrate to other file
systems (e.g. ext4 instead of ext3) when they need the file system to
survive beyond 2038 (or similar limits in other file systems), but not
get in the way of normal usage.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2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=em9y
-----END PGP SIGNATURE-----
Merge tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground
Pull y2038 vfs updates from Arnd Bergmann:
"Add inode timestamp clamping.
This series from Deepa Dinamani adds a per-superblock minimum/maximum
timestamp limit for a file system, and clamps timestamps as they are
written, to avoid random behavior from integer overflow as well as
having different time stamps on disk vs in memory.
At mount time, a warning is now printed for any file system that can
represent current timestamps but not future timestamps more than 30
years into the future, similar to the arbitrary 30 year limit that was
added to settimeofday().
This was picked as a compromise to warn users to migrate to other file
systems (e.g. ext4 instead of ext3) when they need the file system to
survive beyond 2038 (or similar limits in other file systems), but not
get in the way of normal usage"
* tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground:
ext4: Reduce ext4 timestamp warnings
isofs: Initialize filesystem timestamp ranges
pstore: fs superblock limits
fs: omfs: Initialize filesystem timestamp ranges
fs: hpfs: Initialize filesystem timestamp ranges
fs: ceph: Initialize filesystem timestamp ranges
fs: sysv: Initialize filesystem timestamp ranges
fs: affs: Initialize filesystem timestamp ranges
fs: fat: Initialize filesystem timestamp ranges
fs: cifs: Initialize filesystem timestamp ranges
fs: nfs: Initialize filesystem timestamp ranges
ext4: Initialize timestamps limits
9p: Fill min and max timestamps in sb
fs: Fill in max and min timestamps in superblock
utimes: Clamp the timestamps before update
mount: Add mount warning for impending timestamp expiry
timestamp_truncate: Replace users of timespec64_trunc
vfs: Add timestamp_truncate() api
vfs: Add file timestamp range support
-----BEGIN PGP SIGNATURE-----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=63t2
-----END PGP SIGNATURE-----
Merge tag 'filelock-v5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull file locking updates from Jeff Layton:
"Just a couple of minor bugfixes, a revision to a tracepoint to account
for some earlier changes to the internals, and a patch to add a
pr_warn message when someone tries to mount a filesystem with '-o
mand' on a kernel that has that support disabled"
* tag 'filelock-v5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
locks: fix a memory leak bug in __break_lease()
locks: print a warning when mount fails due to lack of "mand" support
locks: Fix procfs output for file leases
locks: revise generic_add_lease tracepoint
Pull vfs namei updates from Al Viro:
"Pathwalk-related stuff"
[ Audit-related cleanups, misc simplifications, and easier to follow
nd->root refcounts - Linus ]
* 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
devpts_pty_kill(): don't bother with d_delete()
infiniband: don't bother with d_delete()
hypfs: don't bother with d_delete()
fs/namei.c: keep track of nd->root refcount status
fs/namei.c: new helper - legitimize_root()
kill the last users of user_{path,lpath,path_dir}()
namei.h: get the comments on LOOKUP_... in sync with reality
kill LOOKUP_NO_EVAL, don't bother including namei.h from audit.h
audit_inode(): switch to passing AUDIT_INODE_...
filename_mountpoint(): make LOOKUP_NO_EVAL unconditional there
filename_lookup(): audit_inode() argument is always 0
The unused vfs code can be removed. Don't pass empty subtype (same as if
->parse callback isn't called).
The bits that are left involve determining whether it's permitted to split the
filesystem type string passed in to mount(2). Consequently, this means that we
cannot get rid of the FS_HAS_SUBTYPE flag unless we define that a type string
with a dot in it always indicates a subtype specification.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The warning reuses the uptime max of 30 years used by
settimeofday().
Note that the warning is only emitted for writable filesystem mounts
through the mount syscall. Automounts do not have the same warning.
Print out the warning in human readable format using the struct tm.
After discussion with Arnd Bergmann, we chose to print only the year number.
The raw s_time_max is also displayed, and the user can easily decode
it e.g. "date -u -d @$((0x7fffffff))". We did not want to consolidate
struct rtc_tm and struct tm just to print the date using a format specifier
as part of this series.
Given that the rtc_tm is not compiled on all architectures, this is not a
trivial patch. This can be added in the future.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Since 9e8925b67a ("locks: Allow disabling mandatory locking at compile
time"), attempts to mount filesystems with "-o mand" will fail.
Unfortunately, there is no other indiciation of the reason for the
failure.
Change how the function is defined for better readability. When
CONFIG_MANDATORY_FILE_LOCKING is disabled, printk a warning when
someone attempts to mount with -o mand.
Also, add a blurb to the mandatory-locking.txt file to explain about
the "mand" option, and the behavior one should expect when it is
disabled.
Reported-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
We need to drop everything we remove from the tree, whether
mnt_has_parent() is true or not. Usually the bug manifests as a slow
memory leak (leaked struct mount for initramfs); it becomes much more
visible in mount_subtree() users, such as btrfs. There we leak
a struct mount for btrfs superblock being mounted, which prevents
fs shutdown on subsequent umount.
Fixes: 56cbb429d9 ("switch the remnants of releasing the mountpoint away from fs_pin")
Reported-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
user_path_mountpoint_at() always gets it and the reasons to have it
there (i.e. in umount(2)) apply to kern_path_mountpoint() callers
as well.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull dcache and mountpoint updates from Al Viro:
"Saner handling of refcounts to mountpoints.
Transfer the counting reference from struct mount ->mnt_mountpoint
over to struct mountpoint ->m_dentry. That allows us to get rid of the
convoluted games with ordering of mount shutdowns.
The cost is in teaching shrink_dcache_{parent,for_umount} to cope with
mixed-filesystem shrink lists, which we'll also need for the Slab
Movable Objects patchset"
* 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
switch the remnants of releasing the mountpoint away from fs_pin
get rid of detach_mnt()
make struct mountpoint bear the dentry reference to mountpoint, not struct mount
Teach shrink_dcache_parent() to cope with mixed-filesystem shrink lists
fs/namespace.c: shift put_mountpoint() to callers of unhash_mnt()
__detach_mounts(): lookup_mountpoint() can't return ERR_PTR() anymore
nfs: dget_parent() never returns NULL
ceph: don't open-code the check for dead lockref
Pull vfs mount updates from Al Viro:
"The first part of mount updates.
Convert filesystems to use the new mount API"
* 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
mnt_init(): call shmem_init() unconditionally
constify ksys_mount() string arguments
don't bother with registering rootfs
init_rootfs(): don't bother with init_ramfs_fs()
vfs: Convert smackfs to use the new mount API
vfs: Convert selinuxfs to use the new mount API
vfs: Convert securityfs to use the new mount API
vfs: Convert apparmorfs to use the new mount API
vfs: Convert openpromfs to use the new mount API
vfs: Convert xenfs to use the new mount API
vfs: Convert gadgetfs to use the new mount API
vfs: Convert oprofilefs to use the new mount API
vfs: Convert ibmasmfs to use the new mount API
vfs: Convert qib_fs/ipathfs to use the new mount API
vfs: Convert efivarfs to use the new mount API
vfs: Convert configfs to use the new mount API
vfs: Convert binfmt_misc to use the new mount API
convenience helper: get_tree_single()
convenience helper get_tree_nodev()
vfs: Kill sget_userns()
...
We used to need rather convoluted ordering trickery to guarantee
that dput() of ex-mountpoints happens before the final mntput()
of the same. Since we don't need that anymore, there's no point
playing with fs_pin for that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Lift getting the original mount (dentry is actually not needed at all)
of the mountpoint into the callers - to do_move_mount() and pivot_root()
level. That simplifies the cleanup in those and allows to get saner
arguments for attach_mnt_recursive().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Using dput_to_list() to shift the contributing reference from ->mnt_mountpoint
to ->mnt_mp->m_dentry. Dentries are dropped (with dput_to_list()) as soon
as struct mountpoint is destroyed; in cases where we are under namespace_sem
we use the global list, shrinking it in namespace_unlock(). In case of
detaching stuck MNT_LOCKed children at final mntput_no_expire() we use a local
list and shrink it ourselves. ->mnt_ex_mountpoint crap is gone.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
No point having two call sites (earlier in init_rootfs() from
mnt_init() in case we are going to use shmem-style rootfs,
later from do_basic_setup() unconditionally), along with the
logics in shmem_init() itself to make the second call a no-op...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
init_mount_tree() can get to rootfs_fs_type directly and that simplifies
a lot of things. We don't need to register it, we don't need to look
it up *and* we don't need to bother with preventing subsequent userland
mounts. That's the way we should've done that from the very beginning.
There is a user-visible change, namely the disappearance of "rootfs"
from /proc/filesystems. Note that it's been unmountable all along
and it didn't show up in /proc/mounts; however, it *is* a user-visible
change and theoretically some script might've been using its presence
in /proc/filesystems to tell 2.4.11+ from earlier kernels.
*IF* any complaints about behaviour change do show up, we could fake
it in /proc/filesystems. I very much doubt we'll have to, though.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
sys_move_mount() crashes by dereferencing the pointer MNT_NS_INTERNAL,
a.k.a. ERR_PTR(-EINVAL), if the old mount is specified by fd for a
kernel object with an internal mount, such as a pipe or memfd.
Fix it by checking for this case and returning -EINVAL.
[AV: what we want is is_mounted(); use that instead of making the
condition even more convoluted]
Reproducer:
#include <unistd.h>
#define __NR_move_mount 429
#define MOVE_MOUNT_F_EMPTY_PATH 0x00000004
int main()
{
int fds[2];
pipe(fds);
syscall(__NR_move_mount, fds[0], "", -1, "/", MOVE_MOUNT_F_EMPTY_PATH);
}
Reported-by: syzbot+6004acbaa1893ad013f0@syzkaller.appspotmail.com
Fixes: 2db154b3ea ("vfs: syscall: Add move_mount(2) to move mounts around")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When propagating mounts across mount namespaces owned by different user
namespaces it is not possible anymore to move or umount the mount in the
less privileged mount namespace.
Here is a reproducer:
sudo mount -t tmpfs tmpfs /mnt
sudo --make-rshared /mnt
# create unprivileged user + mount namespace and preserve propagation
unshare -U -m --map-root --propagation=unchanged
# now change back to the original mount namespace in another terminal:
sudo mkdir /mnt/aaa
sudo mount -t tmpfs tmpfs /mnt/aaa
# now in the unprivileged user + mount namespace
mount --move /mnt/aaa /opt
Unfortunately, this is a pretty big deal for userspace since this is
e.g. used to inject mounts into running unprivileged containers.
So this regression really needs to go away rather quickly.
The problem is that a recent change falsely locked the root of the newly
added mounts by setting MNT_LOCKED. Fix this by only locking the mounts
on copy_mnt_ns() and not when adding a new mount.
Fixes: 3bd045cc9c ("separate copying and locking mount tree on cross-userns copies")
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Tested-by: Christian Brauner <christian@brauner.io>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
sys_fsmount() needs to take a reference to the new mount when adding it
to the anonymous mount namespace. Otherwise the filesystem can be
unmounted while it's still in use, as found by syzkaller.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: syzbot+99de05d099a170867f22@syzkaller.appspotmail.com
Reported-by: syzbot+7008b8b8ba7df475fdc8@syzkaller.appspotmail.com
Fixes: 93766fbd26 ("vfs: syscall: Add fsmount() to create a mount for a superblock")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Based on 1 normalized pattern(s):
released under gpl v2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 15 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528171438.895196075@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Call graph of vfs_get_tree():
vfs_fsconfig_locked() # neither kernmount, nor submount
do_new_mount() # neither kernmount, nor submount
fc_mount()
afs_mntpt_do_automount() # submount
mount_one_hugetlbfs() # kernmount
pid_ns_prepare_proc() # kernmount
mq_create_mount() # kernmount
vfs_kern_mount()
simple_pin_fs() # kernmount
vfs_submount() # submount
kern_mount() # kernmount
init_mount_tree()
btrfs_mount()
nfs_do_root_mount()
The first two need the check (unconditionally).
init_mount_tree() is setting rootfs up; any capability
checks make zero sense for that one. And btrfs_mount()/
nfs_do_root_mount() have the checks already done in their
callers.
IOW, we can shift mount_capable() handling into
the two callers - one in the normal case of mount(2),
another - in fsconfig(2) handling of FSCONFIG_CMD_CREATE.
I.e. the syscalls that set a new filesystem up.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
What triggers it is a race between mount --move and umount -l
of the source; we should reject it (the source is parentless *and*
not the root of anon namespace at that), but the check for namespace
being an anon one is broken in that case - is_anon_ns() needs
ns to be non-NULL. Better fixed here than in is_anon_ns(), since
the rest of the callers is guaranteed to get a non-NULL argument...
Reported-by: syzbot+494c7ddf66acac0ad747@syzkaller.appspotmail.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Provide a system call by which a filesystem opened with fsopen() and
configured by a series of fsconfig() calls can have a detached mount object
created for it. This mount object can then be attached to the VFS mount
hierarchy using move_mount() by passing the returned file descriptor as the
from directory fd.
The system call looks like:
int mfd = fsmount(int fsfd, unsigned int flags,
unsigned int attr_flags);
where fsfd is the file descriptor returned by fsopen(). flags can be 0 or
FSMOUNT_CLOEXEC. attr_flags is a bitwise-OR of the following flags:
MOUNT_ATTR_RDONLY Mount read-only
MOUNT_ATTR_NOSUID Ignore suid and sgid bits
MOUNT_ATTR_NODEV Disallow access to device special files
MOUNT_ATTR_NOEXEC Disallow program execution
MOUNT_ATTR__ATIME Setting on how atime should be updated
MOUNT_ATTR_RELATIME - Update atime relative to mtime/ctime
MOUNT_ATTR_NOATIME - Do not update access times
MOUNT_ATTR_STRICTATIME - Always perform atime updates
MOUNT_ATTR_NODIRATIME Do not update directory access times
In the event that fsmount() fails, it may be possible to get an error
message by calling read() on fsfd. If no message is available, ENODATA
will be reported.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Allow a detached tree created by open_tree(..., OPEN_TREE_CLONE) to be
attached by move_mount(2).
If by the time of final fput() of OPEN_TREE_CLONE-opened file its tree is
not detached anymore, it won't be dissolved. move_mount(2) is adjusted
to handle detached source.
That gives us equivalents of mount --bind and mount --rbind.
Thanks also to Alan Jenkins <alan.christopher.jenkins@gmail.com> for
providing a whole bunch of ways to break things using this interface.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a move_mount() system call that will move a mount from one place to
another and, in the next commit, allow to attach an unattached mount tree.
The new system call looks like the following:
int move_mount(int from_dfd, const char *from_path,
int to_dfd, const char *to_path,
unsigned int flags);
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
open_tree(dfd, pathname, flags)
Returns an O_PATH-opened file descriptor or an error.
dfd and pathname specify the location to open, in usual
fashion (see e.g. fstatat(2)). flags should be an OR of
some of the following:
* AT_PATH_EMPTY, AT_NO_AUTOMOUNT, AT_SYMLINK_NOFOLLOW -
same meanings as usual
* OPEN_TREE_CLOEXEC - make the resulting descriptor
close-on-exec
* OPEN_TREE_CLONE or OPEN_TREE_CLONE | AT_RECURSIVE -
instead of opening the location in question, create a detached
mount tree matching the subtree rooted at location specified by
dfd/pathname. With AT_RECURSIVE the entire subtree is cloned,
without it - only the part within in the mount containing the
location in question. In other words, the same as mount --rbind
or mount --bind would've taken. The detached tree will be
dissolved on the final close of obtained file. Creation of such
detached trees requires the same capabilities as doing mount --bind.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs mount infrastructure updates from Al Viro:
"The rest of core infrastructure; no new syscalls in that pile, but the
old parts are switched to new infrastructure. At that point
conversions of individual filesystems can happen independently; some
are done here (afs, cgroup, procfs, etc.), there's also a large series
outside of that pile dealing with NFS (quite a bit of option-parsing
stuff is getting used there - it's one of the most convoluted
filesystems in terms of mount-related logics), but NFS bits are the
next cycle fodder.
It got seriously simplified since the last cycle; documentation is
probably the weakest bit at the moment - I considered dropping the
commit introducing Documentation/filesystems/mount_api.txt (cutting
the size increase by quarter ;-), but decided that it would be better
to fix it up after -rc1 instead.
That pile allows to do followup work in independent branches, which
should make life much easier for the next cycle. fs/super.c size
increase is unpleasant; there's a followup series that allows to
shrink it considerably, but I decided to leave that until the next
cycle"
* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
afs: Use fs_context to pass parameters over automount
afs: Add fs_context support
vfs: Add some logging to the core users of the fs_context log
vfs: Implement logging through fs_context
vfs: Provide documentation for new mount API
vfs: Remove kern_mount_data()
hugetlbfs: Convert to fs_context
cpuset: Use fs_context
kernfs, sysfs, cgroup, intel_rdt: Support fs_context
cgroup: store a reference to cgroup_ns into cgroup_fs_context
cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper
cgroup_do_mount(): massage calling conventions
cgroup: stash cgroup_root reference into cgroup_fs_context
cgroup2: switch to option-by-option parsing
cgroup1: switch to option-by-option parsing
cgroup: take options parsing into ->parse_monolithic()
cgroup: fold cgroup1_mount() into cgroup1_get_tree()
cgroup: start switching to fs_context
ipc: Convert mqueue fs to fs_context
proc: Add fs_context support to procfs
...
-----BEGIN PGP SIGNATURE-----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=57/1
-----END PGP SIGNATURE-----
Merge tag 'audit-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
Pull audit updates from Paul Moore:
"A lucky 13 audit patches for v5.1.
Despite the rather large diffstat, most of the changes are from two
bug fix patches that move code from one Kconfig option to another.
Beyond that bit of churn, the remaining changes are largely cleanups
and bug-fixes as we slowly march towards container auditing. It isn't
all boring though, we do have a couple of new things: file
capabilities v3 support, and expanded support for filtering on
filesystems to solve problems with remote filesystems.
All changes pass the audit-testsuite. Please merge for v5.1"
* tag 'audit-pr-20190305' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit:
audit: mark expected switch fall-through
audit: hide auditsc_get_stamp and audit_serial prototypes
audit: join tty records to their syscall
audit: remove audit_context when CONFIG_ AUDIT and not AUDITSYSCALL
audit: remove unused actx param from audit_rule_match
audit: ignore fcaps on umount
audit: clean up AUDITSYSCALL prototypes and stubs
audit: more filter PATH records keyed on filesystem magic
audit: add support for fcaps v3
audit: move loginuid and sessionid from CONFIG_AUDITSYSCALL to CONFIG_AUDIT
audit: add syscall information to CONFIG_CHANGE records
audit: hand taken context to audit_kill_trees for syscall logging
audit: give a clue what CONFIG_CHANGE op was involved
Pull vfs fixes from Al Viro:
"Assorted fixes that sat in -next for a while, all over the place"
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
aio: Fix locking in aio_poll()
exec: Fix mem leak in kernel_read_file
copy_mount_string: Limit string length to PATH_MAX
cgroup: saner refcounting for cgroup_root
fix cgroup_do_mount() handling of failure exits
The kern_mount_data() isn't used any more so remove it.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[AV - unfuck kern_mount_data(); we want non-NULL ->mnt_ns on long-living
mounts]
[AV - reordering fs/namespace.c is badly overdue, but let's keep it
separate from that series]
[AV - drop simple_pin_fs() change]
[AV - clean vfs_kern_mount() failure exits up]
Implement a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount.
The mounting procedure then becomes:
(1) Allocate new fs_context context.
(2) Configure the context.
(3) Create superblock.
(4) Query the superblock.
(5) Create a mount for the superblock.
(6) Destroy the context.
Rather than calling fs_type->mount(), an fs_context struct is created and
fs_type->init_fs_context() is called to set it up. Pointers exist for the
filesystem and LSM to hang their private data off.
A set of operations has to be set by ->init_fs_context() to provide
freeing, duplication, option parsing, binary data parsing, validation,
mounting and superblock filling.
Legacy filesystems are supported by the provision of a set of legacy
fs_context operations that build up a list of mount options and then invoke
fs_type->mount() from within the fs_context ->get_tree() operation. This
allows all filesystems to be accessed using fs_context.
It should be noted that, whilst this patch adds a lot of lines of code,
there is quite a bit of duplication with existing code that can be
eliminated should all filesystems be converted over.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This reverts commit 9da3f2b740.
It was well-intentioned, but wrong. Overriding the exception tables for
instructions for random reasons is just wrong, and that is what the new
code did.
It caused problems for tracing, and it caused problems for strncpy_from_user(),
because the new checks made perfectly valid use cases break, rather than
catch things that did bad things.
Unchecked user space accesses are a problem, but that's not a reason to
add invalid checks that then people have to work around with silly flags
(in this case, that 'kernel_uaccess_faults_ok' flag, which is just an
odd way to say "this commit was wrong" and was sprinked into random
places to hide the wrongness).
The real fix to unchecked user space accesses is to get rid of the
special "let's not check __get_user() and __put_user() at all" logic.
Make __{get|put}_user() be just aliases to the regular {get|put}_user()
functions, and make it impossible to access user space without having
the proper checks in places.
The raison d'être of the special double-underscore versions used to be
that the range check was expensive, and if you did multiple user
accesses, you'd do the range check up front (like the signal frame
handling code, for example). But SMAP (on x86) and PAN (on ARM) have
made that optimization pointless, because the _real_ expense is the "set
CPU flag to allow user space access".
Do let's not break the valid cases to catch invalid cases that shouldn't
even exist.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tobin C. Harding <tobin@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On ppc64le, When a string with PAGE_SIZE - 1 (i.e. 64k-1) length is
passed as a "filesystem type" argument to the mount(2) syscall,
copy_mount_string() ends up allocating 64k (the PAGE_SIZE on ppc64le)
worth of space for holding the string in kernel's address space.
Later, in set_precision() (invoked by get_fs_type() ->
__request_module() -> vsnprintf()), we end up assigning
strlen(fs-type-string) i.e. 65535 as the
value to 'struct printf_spec'->precision member. This field has a width
of 16 bits and it is a signed data type. Hence an invalid value ends
up getting assigned. This causes the "WARN_ONCE(spec->precision != prec,
"precision %d too large", prec)" statement inside set_precision() to be
executed.
This commit fixes the bug by limiting the length of the string passed by
copy_mount_string() to strndup_user() to PATH_MAX.
Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
Reported-by: Abdul Haleem <abdhalee@linux.ibm.com>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't fetch fcaps when umount2 is called to avoid a process hang while
it waits for the missing resource to (possibly never) re-appear.
Note the comment above user_path_mountpoint_at():
* A umount is a special case for path walking. We're not actually interested
* in the inode in this situation, and ESTALE errors can be a problem. We
* simply want track down the dentry and vfsmount attached at the mountpoint
* and avoid revalidating the last component.
This can happen on ceph, cifs, 9p, lustre, fuse (gluster) or NFS.
Please see the github issue tracker
https://github.com/linux-audit/audit-kernel/issues/100
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: merge fuzz in audit_log_fcaps()]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Replace do_remount_sb() with a function, reconfigure_super(), that's
fs_context aware. The fs_context is expected to be parameterised already
and have ->root pointing to the superblock to be reconfigured.
A legacy wrapper is provided that is intended to be called from the
fs_context ops when those appear, but for now is called directly from
reconfigure_super(). This wrapper invokes the ->remount_fs() superblock op
for the moment. It is intended that the remount_fs() op will be phased
out.
The fs_context->purpose is set to FS_CONTEXT_FOR_RECONFIGURE to indicate
that the context is being used for reconfiguration.
do_umount_root() is provided to consolidate remount-to-R/O for umount and
emergency remount by creating a context and invoking reconfiguration.
do_remount(), do_umount() and do_emergency_remount_callback() are switched
to use the new process.
[AV -- fold UMOUNT and EMERGENCY_REMOUNT in; fixes the
umount / bug, gets rid of pointless complexity]
[AV -- set ->net_ns in all cases; nfs remount will need that]
[AV -- shift security_sb_remount() call into reconfigure_super(); the callers
that didn't do security_sb_remount() have NULL fc->security anyway, so it's
a no-op for them]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Right now vfs_get_tree() calls security_sb_kern_mount() (i.e.
mount MAC) unless it gets MS_KERNMOUNT or MS_SUBMOUNT in flags.
Doing it that way is both clumsy and imprecise.
Consider the callers' tree of vfs_get_tree():
vfs_get_tree()
<- do_new_mount()
<- vfs_kern_mount()
<- simple_pin_fs()
<- vfs_submount()
<- kern_mount_data()
<- init_mount_tree()
<- btrfs_mount()
<- vfs_get_tree()
<- nfs_do_root_mount()
<- nfs4_try_mount()
<- nfs_fs_mount()
<- vfs_get_tree()
<- nfs4_referral_mount()
do_new_mount() always does need MAC (we are guaranteed that neither
MS_KERNMOUNT nor MS_SUBMOUNT will be passed there).
simple_pin_fs(), vfs_submount() and kern_mount_data() pass explicit
flags inhibiting that check. So does nfs4_referral_mount() (the
flags there are ulimately coming from vfs_submount()).
init_mount_tree() is called too early for anything LSM-related; it
doesn't matter whether we attempt those checks, they'll do nothing.
Finally, in case of btrfs_mount() and nfs_fs_mount(), doing MAC
is pointless - either the caller will do it, or the flags are
such that we wouldn't have done it either.
In other words, the one and only case when we want that check
done is when we are called from do_new_mount(), and there we
want it unconditionally.
So let's simply move it there. The superblock is still locked,
so nobody is going to get access to it (via ustat(2), etc.)
until we get a chance to apply the checks - we are free to
move them to any point up to where we drop ->s_umount (in
do_new_mount_fc()).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Create an fs_context-aware version of do_new_mount(). This takes an
fs_context with a superblock already attached to it.
Make do_new_mount() use do_new_mount_fc() rather than do_new_mount(); this
allows the consolidation of the mount creation, check and add steps.
To make this work, mount_too_revealing() is changed to take a superblock
rather than a mount (which the fs_context doesn't have available), allowing
this check to be done before the mount object is created.
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Roll the handling of subtypes into do_new_mount() and vfs_get_tree(). The
former determines any subtype string and hangs it off the fs_context; the
latter applies it.
Make do_new_mount() create, parameterise and commit an fs_context and
create a mount for itself rather than calling vfs_kern_mount().
[AV -- missing kstrdup()]
[AV -- ... and no kstrdup() if we get to setting ->s_submount - we
simply transfer it from fc, leaving NULL behind]
[AV -- constify ->s_submount, while we are at it]
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Create a new helper, vfs_create_mount(), that creates a detached vfsmount
object from an fs_context that has a superblock attached to it.
Almost all uses will be paired with immediately preceding vfs_get_tree();
add a helper for such combination.
Switch vfs_kern_mount() to use this.
NOTE: mild behaviour change; passing NULL as 'device name' to
something like procfs will change /proc/*/mountstats - "device none"
instead on "no device". That is consistent with /proc/mounts et.al.
[do'h - EXPORT_SYMBOL_GPL slipped in by mistake; removed]
[AV -- remove confused comment from vfs_create_mount()]
[AV -- removed the second argument]
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Introduce a filesystem context concept to be used during superblock
creation for mount and superblock reconfiguration for remount. This is
allocated at the beginning of the mount procedure and into it is placed:
(1) Filesystem type.
(2) Namespaces.
(3) Source/Device names (there may be multiple).
(4) Superblock flags (SB_*).
(5) Security details.
(6) Filesystem-specific data, as set by the mount options.
Accessor functions are then provided to set up a context, parameterise it
from monolithic mount data (the data page passed to mount(2)) and tear it
down again.
A legacy wrapper is provided that implements what will be the basic
operations, wrapping access to filesystems that aren't yet aware of the
fs_context.
Finally, vfs_kern_mount() is changed to make use of the fs_context and
mount_fs() is replaced by vfs_get_tree(), called from vfs_kern_mount().
[AV -- add missing kstrdup()]
[AV -- put_cred() can be unconditional - fc->cred can't be NULL]
[AV -- take legacy_validate() contents into legacy_parse_monolithic()]
[AV -- merge KERNEL_MOUNT and USER_MOUNT]
[AV -- don't unlock superblock on success return from vfs_get_tree()]
[AV -- kill 'reference' argument of init_fs_context()]
Signed-off-by: David Howells <dhowells@redhat.com>
Co-developed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
mount_subtree() creates (and soon destroys) a temporary namespace,
so that automounts could function normally. These beasts should
never become anyone's current namespaces; they don't, but it would
be better to make prevention of that more straightforward. And
since they don't become anyone's current namespace, we don't need
to bother with reserving procfs inums for those.
Teach alloc_mnt_ns() to skip inum allocation if told so, adjust
put_mnt_ns() accordingly, make mount_subtree() use temporary
(anon) namespace. is_anon_ns() checks if a namespace is such.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs mount API prep from Al Viro:
"Mount API prereqs.
Mostly that's LSM mount options cleanups. There are several minor
fixes in there, but nothing earth-shattering (leaks on failure exits,
mostly)"
* 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (27 commits)
mount_fs: suppress MAC on MS_SUBMOUNT as well as MS_KERNMOUNT
smack: rewrite smack_sb_eat_lsm_opts()
smack: get rid of match_token()
smack: take the guts of smack_parse_opts_str() into a new helper
LSM: new method: ->sb_add_mnt_opt()
selinux: rewrite selinux_sb_eat_lsm_opts()
selinux: regularize Opt_... names a bit
selinux: switch away from match_token()
selinux: new helper - selinux_add_opt()
LSM: bury struct security_mnt_opts
smack: switch to private smack_mnt_opts
selinux: switch to private struct selinux_mnt_opts
LSM: hide struct security_mnt_opts from any generic code
selinux: kill selinux_sb_get_mnt_opts()
LSM: turn sb_eat_lsm_opts() into a method
nfs_remount(): don't leak, don't ignore LSM options quietly
btrfs: sanitize security_mnt_opts use
selinux; don't open-code a loop in sb_finish_set_opts()
LSM: split ->sb_set_mnt_opts() out of ->sb_kern_mount()
new helper: security_sb_eat_lsm_opts()
...
Pull trivial vfs updates from Al Viro:
"A few cleanups + Neil's namespace_unlock() optimization"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
exec: make prepare_bprm_creds static
genheaders: %-<width>s had been there since v6; %-*s - since v7
VFS: use synchronize_rcu_expedited() in namespace_unlock()
iov_iter: reduce code duplication
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.
It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access. But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.
A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model. And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.
This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.
There were a couple of notable cases:
- csky still had the old "verify_area()" name as an alias.
- the iter_iov code had magical hardcoded knowledge of the actual
values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
really used it)
- microblaze used the type argument for a debug printout
but other than those oddities this should be a total no-op patch.
I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something. Any missed conversion should be trivially fixable, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Keep void * instead, allocate on demand (in parse_str_opts, at the
moment). Eventually both selinux and smack will be better off
with private structures with several strings in those, rather than
this "counter and two pointers to dynamically allocated arrays"
ugliness. This commit allows to do that at leisure, without
disrupting anything outside of given module.
Changes:
* instead of struct security_mnt_opt use an opaque pointer
initialized to NULL.
* security_sb_eat_lsm_opts(), security_sb_parse_opts_str() and
security_free_mnt_opts() take it as var argument (i.e. as void **);
call sites are unchanged.
* security_sb_set_mnt_opts() and security_sb_remount() take
it by value (i.e. as void *).
* new method: ->sb_free_mnt_opts(). Takes void *, does
whatever freeing that needs to be done.
* ->sb_set_mnt_opts() and ->sb_remount() might get NULL as
mnt_opts argument, meaning "empty".
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
combination of alloc_secdata(), security_sb_copy_data(),
security_sb_parse_opt_str() and free_secdata().
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This paves the way for retaining the LSM options from a common filesystem
mount context during a mount parameter parsing phase to be instituted prior
to actual mount/reconfiguration actions.
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Separate just the changing of mount flags (MS_REMOUNT|MS_BIND) from full
remount because the mount data will get parsed with the new fs_context
stuff prior to doing a remount - and this causes the syscall to fail under
some circumstances.
To quote Eric's explanation:
[...] mount(..., MS_REMOUNT|MS_BIND, ...) now validates the mount options
string, which breaks systemd unit files with ProtectControlGroups=yes
(e.g. systemd-networkd.service) when systemd does the following to
change a cgroup (v1) mount to read-only:
mount(NULL, "/run/systemd/unit-root/sys/fs/cgroup/systemd", NULL,
MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_REMOUNT|MS_BIND, NULL)
... when the kernel has CONFIG_CGROUPS=y but no cgroup subsystems
enabled, since in that case the error "cgroup1: Need name or subsystem
set" is hit when the mount options string is empty.
Probably it doesn't make sense to validate the mount options string at
all in the MS_REMOUNT|MS_BIND case, though maybe you had something else
in mind.
This is also worthwhile doing because we will need to add a mount_setattr()
syscall to take over the remount-bind function.
Reported-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>
Only the mount namespace code that implements mount(2) should be using the
MS_* flags. Suppress them inside the kernel unless uapi/linux/mount.h is
included.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>
The synchronize_rcu() in namespace_unlock() is called every time
a filesystem is unmounted. If a great many filesystems are mounted,
this can cause a noticable slow-down in, for example, system shutdown.
The sequence:
mkdir -p /tmp/Mtest/{0..5000}
time for i in /tmp/Mtest/*; do mount -t tmpfs tmpfs $i ; done
time umount /tmp/Mtest/*
on a 4-cpu VM can report 8 seconds to mount the tmpfs filesystems, and
100 seconds to unmount them.
Boot the same VM with 1 CPU and it takes 18 seconds to mount the
tmpfs filesystems, but only 36 to unmount.
If we change the synchronize_rcu() to synchronize_rcu_expedited()
the umount time on a 4-cpu VM drop to 0.6 seconds
I think this 200-fold speed up is worth the slightly high system
impact of using synchronize_rcu_expedited().
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> (from general rcu perspective)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since commit ff17fa561a ("d_invalidate(): unhash immediately")
immediately unhashes the dentry, we'll never return the mountpoint in
lookup_mountpoint(), which can lead to an unbreakable loop in
d_invalidate().
I have reports of NFS clients getting into this condition after the server
removes an export of an existing mount created through follow_automount(),
but I suspect there are various other ways to produce this problem if we
hunt down users of d_invalidate(). For example, it is possible to get into
this state by using XFS' d_invalidate() call in xfs_vn_unlink():
truncate -s 100m img{1,2}
mkfs.xfs -q -n version=ci img1
mkfs.xfs -q -n version=ci img2
mkdir -p /mnt/xfs
mount img1 /mnt/xfs
mkdir /mnt/xfs/sub1
mount img2 /mnt/xfs/sub1
cat > /mnt/xfs/sub1/foo &
umount -l /mnt/xfs/sub1
mount img2 /mnt/xfs/sub1
mount --make-private /mnt/xfs
mkdir /mnt/xfs/sub2
mount --move /mnt/xfs/sub1 /mnt/xfs/sub2
rmdir /mnt/xfs/sub1
Fix this by moving the check for an unlinked dentry out of the
detach_mounts() path.
Fixes: ff17fa561a ("d_invalidate(): unhash immediately")
Cc: stable@vger.kernel.org
Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Timothy Baldwin <timbaldwin@fastmail.co.uk> wrote:
> As per mount_namespaces(7) unprivileged users should not be able to look under mount points:
>
> Mounts that come as a single unit from more privileged mount are locked
> together and may not be separated in a less privileged mount namespace.
>
> However they can:
>
> 1. Create a mount namespace.
> 2. In the mount namespace open a file descriptor to the parent of a mount point.
> 3. Destroy the mount namespace.
> 4. Use the file descriptor to look under the mount point.
>
> I have reproduced this with Linux 4.16.18 and Linux 4.18-rc8.
>
> The setup:
>
> $ sudo sysctl kernel.unprivileged_userns_clone=1
> kernel.unprivileged_userns_clone = 1
> $ mkdir -p A/B/Secret
> $ sudo mount -t tmpfs hide A/B
>
>
> "Secret" is indeed hidden as expected:
>
> $ ls -lR A
> A:
> total 0
> drwxrwxrwt 2 root root 40 Feb 12 21:08 B
>
> A/B:
> total 0
>
>
> The attack revealing "Secret":
>
> $ unshare -Umr sh -c "exec unshare -m ls -lR /proc/self/fd/4/ 4<A"
> /proc/self/fd/4/:
> total 0
> drwxr-xr-x 3 root root 60 Feb 12 21:08 B
>
> /proc/self/fd/4/B:
> total 0
> drwxr-xr-x 2 root root 40 Feb 12 21:08 Secret
>
> /proc/self/fd/4/B/Secret:
> total 0
I tracked this down to put_mnt_ns running passing UMOUNT_SYNC and
disconnecting all of the mounts in a mount namespace. Fix this by
factoring drop_mounts out of drop_collected_mounts and passing
0 instead of UMOUNT_SYNC.
There are two possible behavior differences that result from this.
- No longer setting UMOUNT_SYNC will no longer set MNT_SYNC_UMOUNT on
the vfsmounts being unmounted. This effects the lazy rcu walk by
kicking the walk out of rcu mode and forcing it to be a non-lazy
walk.
- No longer disconnecting locked mounts will keep some mounts around
longer as they stay because the are locked to other mounts.
There are only two users of drop_collected mounts: audit_tree.c and
put_mnt_ns.
In audit_tree.c the mounts are private and there are no rcu lazy walks
only calls to iterate_mounts. So the changes should have no effect
except for a small timing effect as the connected mounts are disconnected.
In put_mnt_ns there may be references from process outside the mount
namespace to the mounts. So the mounts remaining connected will
be the bug fix that is needed. That rcu walks are allowed to continue
appears not to be a problem especially as the rcu walk change was about
an implementation detail not about semantics.
Cc: stable@vger.kernel.org
Fixes: 5ff9d8a65c ("vfs: Lock in place mounts from more privileged users")
Reported-by: Timothy Baldwin <timbaldwin@fastmail.co.uk>
Tested-by: Timothy Baldwin <timbaldwin@fastmail.co.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Jonathan Calmels from NVIDIA reported that he's able to bypass the
mount visibility security check in place in the Linux kernel by using
a combination of the unbindable property along with the private mount
propagation option to allow a unprivileged user to see a path which
was purposefully hidden by the root user.
Reproducer:
# Hide a path to all users using a tmpfs
root@castiana:~# mount -t tmpfs tmpfs /sys/devices/
root@castiana:~#
# As an unprivileged user, unshare user namespace and mount namespace
stgraber@castiana:~$ unshare -U -m -r
# Confirm the path is still not accessible
root@castiana:~# ls /sys/devices/
# Make /sys recursively unbindable and private
root@castiana:~# mount --make-runbindable /sys
root@castiana:~# mount --make-private /sys
# Recursively bind-mount the rest of /sys over to /mnnt
root@castiana:~# mount --rbind /sys/ /mnt
# Access our hidden /sys/device as an unprivileged user
root@castiana:~# ls /mnt/devices/
breakpoint cpu cstate_core cstate_pkg i915 intel_pt isa kprobe
LNXSYSTM:00 msr pci0000:00 platform pnp0 power software system
tracepoint uncore_arb uncore_cbox_0 uncore_cbox_1 uprobe virtual
Solve this by teaching copy_tree to fail if a mount turns out to be
both unbindable and locked.
Cc: stable@vger.kernel.org
Fixes: 5ff9d8a65c ("vfs: Lock in place mounts from more privileged users")
Reported-by: Jonathan Calmels <jcalmels@nvidia.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
It was recently pointed out that the one instance of testing MNT_LOCKED
outside of the namespace_sem is in ksys_umount.
Fix that by adding a test inside of do_umount with namespace_sem and
the mount_lock held. As it helps to fail fails the existing test is
maintained with an additional comment pointing out that it may be racy
because the locks are not held.
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Fixes: 5ff9d8a65c ("vfs: Lock in place mounts from more privileged users")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Move remaining definitions and declarations from include/linux/bootmem.h
into include/linux/memblock.h and remove the redundant header.
The includes were replaced with the semantic patch below and then
semi-automated removal of duplicated '#include <linux/memblock.h>
@@
@@
- #include <linux/bootmem.h>
+ #include <linux/memblock.h>
[sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au
[sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h]
Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au
[sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal]
Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au
Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Serge Semin <fancer.lancer@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There have been multiple kernel vulnerabilities that permitted userspace to
pass completely unchecked pointers through to userspace accessors:
- the waitid() bug - commit 96ca579a1e ("waitid(): Add missing
access_ok() checks")
- the sg/bsg read/write APIs
- the infiniband read/write APIs
These don't happen all that often, but when they do happen, it is hard to
test for them properly; and it is probably also hard to discover them with
fuzzing. Even when an unmapped kernel address is supplied to such buggy
code, it just returns -EFAULT instead of doing a proper BUG() or at least
WARN().
Try to make such misbehaving code a bit more visible by refusing to do a
fixup in the pagefault handler code when a userspace accessor causes a #PF
on a kernel address and the current context isn't whitelisted.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: dvyukov@google.com
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20180828201421.157735-7-jannh@google.com
Pull IDA updates from Matthew Wilcox:
"A better IDA API:
id = ida_alloc(ida, GFP_xxx);
ida_free(ida, id);
rather than the cumbersome ida_simple_get(), ida_simple_remove().
The new IDA API is similar to ida_simple_get() but better named. The
internal restructuring of the IDA code removes the bitmap
preallocation nonsense.
I hope the net -200 lines of code is convincing"
* 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax: (29 commits)
ida: Change ida_get_new_above to return the id
ida: Remove old API
test_ida: check_ida_destroy and check_ida_alloc
test_ida: Convert check_ida_conv to new API
test_ida: Move ida_check_max
test_ida: Move ida_check_leaf
idr-test: Convert ida_check_nomem to new API
ida: Start new test_ida module
target/iscsi: Allocate session IDs from an IDA
iscsi target: fix session creation failure handling
drm/vmwgfx: Convert to new IDA API
dmaengine: Convert to new IDA API
ppc: Convert vas ID allocation to new IDA API
media: Convert entity ID allocation to new IDA API
ppc: Convert mmu context allocation to new IDA API
Convert net_namespace to new IDA API
cb710: Convert to new IDA API
rsxx: Convert to new IDA API
osd: Convert to new IDA API
sd: Convert to new IDA API
...
This contains two new features:
1) Stack file operations: this allows removal of several hacks from the
VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
2) Metadata only copy-up: when file is on lower layer and only metadata is
modified (except size) then only copy up the metadata and continue to
use the data from the lower file.
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQSQHSd0lITzzeNWNm3h3BK/laaZPAUCW3srhAAKCRDh3BK/laaZ
PC6tAQCP+KklcN+TvNp502f+O/kATahSpgnun4NY1/p4I8JV+AEAzdlkTN3+MiAO
fn9brN6mBK7h59DO3hqedPLJy2vrgwg=
=QDXH
-----END PGP SIGNATURE-----
Merge tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
"This contains two new features:
- Stack file operations: this allows removal of several hacks from
the VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
- Metadata only copy-up: when file is on lower layer and only
metadata is modified (except size) then only copy up the metadata
and continue to use the data from the lower file"
* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
ovl: Enable metadata only feature
ovl: Do not do metacopy only for ioctl modifying file attr
ovl: Do not do metadata only copy-up for truncate operation
ovl: add helper to force data copy-up
ovl: Check redirect on index as well
ovl: Set redirect on upper inode when it is linked
ovl: Set redirect on metacopy files upon rename
ovl: Do not set dentry type ORIGIN for broken hardlinks
ovl: Add an inode flag OVL_CONST_INO
ovl: Treat metacopy dentries as type OVL_PATH_MERGE
ovl: Check redirects for metacopy files
ovl: Move some dir related ovl_lookup_single() code in else block
ovl: Do not expose metacopy only dentry from d_real()
ovl: Open file with data except for the case of fsync
ovl: Add helper ovl_inode_realdata()
ovl: Store lower data inode in ovl_inode
ovl: Fix ovl_getattr() to get number of blocks from lower
ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
ovl: Copy up meta inode data from lowest data inode
ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
...
__legitimize_mnt() has two problems - one is that in case of success
the check of mount_lock is not ordered wrt preceding increment of
refcount, making it possible to have successful __legitimize_mnt()
on one CPU just before the otherwise final mntpu() on another,
with __legitimize_mnt() not seeing mntput() taking the lock and
mntput() not seeing the increment done by __legitimize_mnt().
Solved by a pair of barriers.
Another is that failure of __legitimize_mnt() on the second
read_seqretry() leaves us with reference that'll need to be
dropped by caller; however, if that races with final mntput()
we can end up with caller dropping rcu_read_lock() and doing
mntput() to release that reference - with the first mntput()
having freed the damn thing just as rcu_read_lock() had been
dropped. Solution: in "do mntput() yourself" failure case
grab mount_lock, check if MNT_DOOMED has been set by racing
final mntput() that has missed our increment and if it has -
undo the increment and treat that as "failure, caller doesn't
need to drop anything" case.
It's not easy to hit - the final mntput() has to come right
after the first read_seqretry() in __legitimize_mnt() *and*
manage to miss the increment done by __legitimize_mnt() before
the second read_seqretry() in there. The things that are almost
impossible to hit on bare hardware are not impossible on SMP
KVM, though...
Reported-by: Oleg Nesterov <oleg@redhat.com>
Fixes: 48a066e72d ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
mntput_no_expire() does the calculation of total refcount under mount_lock;
unfortunately, the decrement (as well as all increments) are done outside
of it, leading to false positives in the "are we dropping the last reference"
test. Consider the following situation:
* mnt is a lazy-umounted mount, kept alive by two opened files. One
of those files gets closed. Total refcount of mnt is 2. On CPU 42
mntput(mnt) (called from __fput()) drops one reference, decrementing component
* After it has looked at component #0, the process on CPU 0 does
mntget(), incrementing component #0, gets preempted and gets to run again -
on CPU 69. There it does mntput(), which drops the reference (component #69)
and proceeds to spin on mount_lock.
* On CPU 42 our first mntput() finishes counting. It observes the
decrement of component #69, but not the increment of component #0. As the
result, the total it gets is not 1 as it should've been - it's 0. At which
point we decide that vfsmount needs to be killed and proceed to free it and
shut the filesystem down. However, there's still another opened file
on that filesystem, with reference to (now freed) vfsmount, etc. and we are
screwed.
It's not a wide race, but it can be reproduced with artificial slowdown of
the mnt_get_count() loop, and it should be easier to hit on SMP KVM setups.
Fix consists of moving the refcount decrement under mount_lock; the tricky
part is that we want (and can) keep the fast case (i.e. mount that still
has non-NULL ->mnt_ns) entirely out of mount_lock. All places that zero
mnt->mnt_ns are dropping some reference to mnt and they call synchronize_rcu()
before that mntput(). IOW, if mntput() observes (under rcu_read_lock())
a non-NULL ->mnt_ns, it is guaranteed that there is another reference yet to
be dropped.
Reported-by: Jann Horn <jannh@google.com>
Tested-by: Jann Horn <jannh@google.com>
Fixes: 48a066e72d ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The underlying real file used by overlayfs still contains the overlay path.
This results in mnt_want_write_file() calls by the filesystem getting
freeze protection on the wrong inode (the overlayfs one instead of the real
one).
Fix by using file_inode(file)->i_sb instead of file->f_path.mnt->mnt_sb.
Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This reverts commit 7c6893e3c9.
Overlayfs no longer relies on the vfs for checking writability of files.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This reverts commit 954c736f86.
Overlayfs no longer relies on the vfs for checking writability of files.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Superblock level remounts are currently restricted to global
CAP_SYS_ADMIN, as is the path for changing the root mount to
read only on umount. Loosen both of these permission checks to
also allow CAP_SYS_ADMIN in any namespace which is privileged
towards the userns which originally mounted the filesystem.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
In do_mount() when the MS_* flags are being converted to MNT_* flags,
MS_RDONLY got accidentally convered to SB_RDONLY.
Undo this change.
Fixes: e462ec50cb ("VFS: Differentiate mount flags (MS_*) from internal superblock flags")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We want it only for the stuff created by SB_KERNMOUNT mounts, *not* for
their copies. As it is, creating a deep stack of bindings of /proc/*/ns/*
somewhere in a new namespace and exiting yields a stack overflow.
Cc: stable@kernel.org
Reported-by: Alexander Aring <aring@mojatatu.com>
Bisected-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Using this helper allows us to avoid the in-kernel call to the sys_umount()
syscall. The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as ksys_umount().
In the near future, the only fs-external caller of ksys_umount() should be
converted to call do_umount() directly. Then, ksys_umount() can be moved
within sys_umount() again.
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>
Using this helper allows us to avoid the in-kernel calls to the sys_mount()
syscall. The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_mount().
In the near future, all callers of ksys_mount() should be converted to call
do_mount() directly.
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>
Since commit e462ec50cb ("VFS: Differentiate mount flags (MS_*) from
internal superblock flags") the lazytime mount option doesn't get passed
on anymore.
Fix the issue by handling the option in do_mount().
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The mount i_version flag is not enabled in the new sb_flags. This patch
adds the missing SB_I_VERSION flag.
Fixes: e462ec5 "VFS: Differentiate mount flags (MS_*) from internal
superblock flags"
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Overlayfs directory file_inode() is the overlay inode whether the real
inode is upper or lower.
This fixes a regression in xfstest generic/158.
Fixes: 7c6893e3c9 ("ovl: don't allow writing ioctl on lower layer")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull misc leftovers from Al Viro.
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fix the __user misannotations in asm-generic get_user/put_user
fput: Don't reinvent the wheel but use existing llist API
namespace.c: Don't reinvent the wheel but use existing llist API
Pull mount flag updates from Al Viro:
"Another chunk of fmount preparations from dhowells; only trivial
conflicts for that part. It separates MS_... bits (very grotty
mount(2) ABI) from the struct super_block ->s_flags (kernel-internal,
only a small subset of MS_... stuff).
This does *not* convert the filesystems to new constants; only the
infrastructure is done here. The next step in that series is where the
conflicts would be; that's the conversion of filesystems. It's purely
mechanical and it's better done after the merge, so if you could run
something like
list=$(for i in MS_RDONLY MS_NOSUID MS_NODEV MS_NOEXEC MS_SYNCHRONOUS MS_MANDLOCK MS_DIRSYNC MS_NOATIME MS_NODIRATIME MS_SILENT MS_POSIXACL MS_KERNMOUNT MS_I_VERSION MS_LAZYTIME; do git grep -l $i fs drivers/staging/lustre drivers/mtd ipc mm include/linux; done|sort|uniq|grep -v '^fs/namespace.c$')
sed -i -e 's/\<MS_RDONLY\>/SB_RDONLY/g' \
-e 's/\<MS_NOSUID\>/SB_NOSUID/g' \
-e 's/\<MS_NODEV\>/SB_NODEV/g' \
-e 's/\<MS_NOEXEC\>/SB_NOEXEC/g' \
-e 's/\<MS_SYNCHRONOUS\>/SB_SYNCHRONOUS/g' \
-e 's/\<MS_MANDLOCK\>/SB_MANDLOCK/g' \
-e 's/\<MS_DIRSYNC\>/SB_DIRSYNC/g' \
-e 's/\<MS_NOATIME\>/SB_NOATIME/g' \
-e 's/\<MS_NODIRATIME\>/SB_NODIRATIME/g' \
-e 's/\<MS_SILENT\>/SB_SILENT/g' \
-e 's/\<MS_POSIXACL\>/SB_POSIXACL/g' \
-e 's/\<MS_KERNMOUNT\>/SB_KERNMOUNT/g' \
-e 's/\<MS_I_VERSION\>/SB_I_VERSION/g' \
-e 's/\<MS_LAZYTIME\>/SB_LAZYTIME/g' \
$list
and commit it with something along the lines of 'convert filesystems
away from use of MS_... constants' as commit message, it would save a
quite a bit of headache next cycle"
* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
VFS: Differentiate mount flags (MS_*) from internal superblock flags
VFS: Convert sb->s_flags & MS_RDONLY to sb_rdonly(sb)
vfs: Add sb_rdonly(sb) to query the MS_RDONLY flag on s_flags
Problem with ioctl() is that it's a file operation, yet often used as an
inode operation (i.e. modify the inode despite the file being opened for
read-only).
mnt_want_write_file() is used by filesystems in such cases to get write
access on an arbitrary open file.
Since overlayfs lets filesystems do all file operations, including ioctl,
this can lead to mnt_want_write_file() returning OK for a lower file and
modification of that lower file.
This patch prevents modification by checking if the file is from an
overlayfs lower layer and returning EPERM in that case.
Need to introduce a mnt_want_write_file_path() variant that still does the
old thing for inode operations that can do the copy up + modification
correctly in such cases (fchown, fsetxattr, fremovexattr).
This does not address the correctness of such ioctls on overlayfs (the
correct way would be to copy up and attempt to perform ioctl on upper
file).
In theory this could be a regression. We very much hope that nobody is
relying on such a hack in any sane setup.
While this patch meddles in VFS code, it has no effect on non-overlayfs
filesystems.
Reported-by: "zhangyi (F)" <yi.zhang@huawei.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Although llist provides proper APIs, they are not used. Make them used.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Differentiate the MS_* flags passed to mount(2) from the internal flags set
in the super_block's s_flags. s_flags are now called SB_*, with the names
and the values for the moment mirroring the MS_* flags that they're
equivalent to.
In this patch, just the headers are altered and some kernel code where
blind automated conversion isn't necessarily correct.
Note that this shows up some interesting issues:
(1) Some MS_* flags get translated to MNT_* flags (such as MS_NODEV ->
MNT_NODEV) without passing this on to the filesystem, but some
filesystems set such flags anyway.
(2) The ->remount_fs() methods of some filesystems adjust the *flags
argument by setting MS_* flags in it, such as MS_NOATIME - but these
flags are then scrubbed by do_remount_sb() (only the occupants of
MS_RMT_MASK are permitted: MS_RDONLY, MS_SYNCHRONOUS, MS_MANDLOCK,
MS_I_VERSION and MS_LAZYTIME)
I'm not sure what's the best way to solve all these cases.
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Firstly by applying the following with coccinelle's spatch:
@@ expression SB; @@
-SB->s_flags & MS_RDONLY
+sb_rdonly(SB)
to effect the conversion to sb_rdonly(sb), then by applying:
@@ expression A, SB; @@
(
-(!sb_rdonly(SB)) && A
+!sb_rdonly(SB) && A
|
-A != (sb_rdonly(SB))
+A != sb_rdonly(SB)
|
-A == (sb_rdonly(SB))
+A == sb_rdonly(SB)
|
-!(sb_rdonly(SB))
+!sb_rdonly(SB)
|
-A && (sb_rdonly(SB))
+A && sb_rdonly(SB)
|
-A || (sb_rdonly(SB))
+A || sb_rdonly(SB)
|
-(sb_rdonly(SB)) != A
+sb_rdonly(SB) != A
|
-(sb_rdonly(SB)) == A
+sb_rdonly(SB) == A
|
-(sb_rdonly(SB)) && A
+sb_rdonly(SB) && A
|
-(sb_rdonly(SB)) || A
+sb_rdonly(SB) || A
)
@@ expression A, B, SB; @@
(
-(sb_rdonly(SB)) ? 1 : 0
+sb_rdonly(SB)
|
-(sb_rdonly(SB)) ? A : B
+sb_rdonly(SB) ? A : B
)
to remove left over excess bracketage and finally by applying:
@@ expression A, SB; @@
(
-(A & MS_RDONLY) != sb_rdonly(SB)
+(bool)(A & MS_RDONLY) != sb_rdonly(SB)
|
-(A & MS_RDONLY) == sb_rdonly(SB)
+(bool)(A & MS_RDONLY) == sb_rdonly(SB)
)
to make comparisons against the result of sb_rdonly() (which is a bool)
work correctly.
Signed-off-by: David Howells <dhowells@redhat.com>
Pull ->s_options removal from Al Viro:
"Preparations for fsmount/fsopen stuff (coming next cycle). Everything
gets moved to explicit ->show_options(), killing ->s_options off +
some cosmetic bits around fs/namespace.c and friends. Basically, the
stuff needed to work with fsmount series with minimum of conflicts
with other work.
It's not strictly required for this merge window, but it would reduce
the PITA during the coming cycle, so it would be nice to have those
bits and pieces out of the way"
* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
isofs: Fix isofs_show_options()
VFS: Kill off s_options and helpers
orangefs: Implement show_options
9p: Implement show_options
isofs: Implement show_options
afs: Implement show_options
affs: Implement show_options
befs: Implement show_options
spufs: Implement show_options
bpf: Implement show_options
ramfs: Implement show_options
pstore: Implement show_options
omfs: Implement show_options
hugetlbfs: Implement show_options
VFS: Don't use save/replace_mount_options if not using generic_show_options
VFS: Provide empty name qstr
VFS: Make get_filesystem() return the affected filesystem
VFS: Clean up whitespace in fs/namespace.c and fs/super.c
Provide a function to create a NUL-terminated string from unterminated data
Kill off s_options, save/replace_mount_options() and generic_show_options()
as all filesystems now implement ->show_options() for themselves. This
should make it easier to implement a context-based mount where the mount
options can be passed individually over a file descriptor.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Mauro Carvalho Chehab