commit 1f282cdc1d upstream.
may_decode_fh() is calling has_locked_children() while holding no locks.
That's an oopsable race...
The rest of the callers are safe since they are holding namespace_sem and
are guaranteed a positive refcount on the mount in question.
Rename the current has_locked_children() to __has_locked_children(), make
it static and switch the fs/namespace.c users to it.
Make has_locked_children() a wrapper for __has_locked_children(), calling
the latter under read_seqlock_excl(&mount_lock).
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Fixes: 620c266f39 ("fhandle: relax open_by_handle_at() permission checks")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[ Harshit: Resolved conflicts due to missing commit:
db04662e2f ("fs: allow detached mounts in clone_private_mount()") in
linux-6.12.y ]
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit cffd044187 ]
do_change_type() and do_set_group() are operating on different
aspects of the same thing - propagation graph. The latter
asks for mounts involved to be mounted in namespace(s) the caller
has CAP_SYS_ADMIN for. The former is a mess - originally it
didn't even check that mount *is* mounted. That got fixed,
but the resulting check turns out to be too strict for userland -
in effect, we check that mount is in our namespace, having already
checked that we have CAP_SYS_ADMIN there.
What we really need (in both cases) is
* only touch mounts that are mounted. That's a must-have
constraint - data corruption happens if it get violated.
* don't allow to mess with a namespace unless you already
have enough permissions to do so (i.e. CAP_SYS_ADMIN in its userns).
That's an equivalent of what do_set_group() does; let's extract that
into a helper (may_change_propagation()) and use it in both
do_set_group() and do_change_type().
Fixes: 12f147ddd6 "do_change_type(): refuse to operate on unmounted/not ours mounts"
Acked-by: Andrei Vagin <avagin@gmail.com>
Reviewed-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Tested-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit c28f922c9d upstream.
What we want is to verify there is that clone won't expose something
hidden by a mount we wouldn't be able to undo. "Wouldn't be able to undo"
may be a result of MNT_LOCKED on a child, but it may also come from
lacking admin rights in the userns of the namespace mount belongs to.
clone_private_mnt() checks the former, but not the latter.
There's a number of rather confusing CAP_SYS_ADMIN checks in various
userns during the mount, especially with the new mount API; they serve
different purposes and in case of clone_private_mnt() they usually,
but not always end up covering the missing check mentioned above.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Reported-by: "Orlando, Noah" <Noah.Orlando@deshaw.com>
Fixes: 427215d85e ("ovl: prevent private clone if bind mount is not allowed")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[ merge conflict resolution: clone_private_mount() was reworked in
db04662e2f ("fs: allow detached mounts in clone_private_mount()").
Tweak the relevant ns_capable check so that it works on older kernels ]
Signed-off-by: Noah Orlando <Noah.Orlando@deshaw.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit ce7df19686 ]
If we are propagating across the userns boundary, we need to lock the
mounts added there. However, in case when something has already
been mounted there and we end up sliding a new tree under that,
the stuff that had been there before should not get locked.
IOW, lock_mnt_tree() should be called before we reparent the
preexisting tree on top of what we are adding.
Fixes: 3bd045cc9c ("separate copying and locking mount tree on cross-userns copies")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 12f147ddd6 ]
Ensure that propagation settings can only be changed for mounts located
in the caller's mount namespace. This change aligns permission checking
with the rest of mount(2).
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: 07b20889e3 ("beginning of the shared-subtree proper")
Reported-by: "Orlando, Noah" <Noah.Orlando@deshaw.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d8cc0362f9 ]
9ffb14ef61 "move_mount: allow to add a mount into an existing group"
breaks assertions on ->mnt_share/->mnt_slave. For once, the data structures
in question are actually documented.
Documentation/filesystem/sharedsubtree.rst:
All vfsmounts in a peer group have the same ->mnt_master. If it is
non-NULL, they form a contiguous (ordered) segment of slave list.
do_set_group() puts a mount into the same place in propagation graph
as the old one. As the result, if old mount gets events from somewhere
and is not a pure event sink, new one needs to be placed next to the
old one in the slave list the old one's on. If it is a pure event
sink, we only need to make sure the new one doesn't end up in the
middle of some peer group.
"move_mount: allow to add a mount into an existing group" ends up putting
the new one in the beginning of list; that's definitely not going to be
in the middle of anything, so that's fine for case when old is not marked
shared. In case when old one _is_ marked shared (i.e. is not a pure event
sink), that breaks the assumptions of propagation graph iterators.
Put the new mount next to the old one on the list - that does the right thing
in "old is marked shared" case and is just as correct as the current behaviour
if old is not marked shared (kudos to Pavel for pointing that out - my original
suggested fix changed behaviour in the "nor marked" case, which complicated
things for no good reason).
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: 9ffb14ef61 ("move_mount: allow to add a mount into an existing group")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5f31c54938 ]
Holding namespace_sem is enough to make sure that result remains valid.
It is *not* enough to avoid false negatives from __lookup_mnt(). Mounts
can be unhashed outside of namespace_sem (stuck children getting detached
on final mntput() of lazy-umounted mount) and having an unrelated mount
removed from the hash chain while we traverse it may end up with false
negative from __lookup_mnt(). We need to sample and recheck the seqlock
component of mount_lock...
Bug predates the introduction of path_overmount() - it had come from
the code in finish_automount() that got abstracted into that helper.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Fixes: 26df6034fd ("fix automount/automount race properly")
Fixes: 6ac3928156 ("fs: allow to mount beneath top mount")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 250cf36930 ]
... or we risk stealing final mntput from sync umount - raising mnt_count
after umount(2) has verified that victim is not busy, but before it
has set MNT_SYNC_UMOUNT; in that case __legitimize_mnt() doesn't see
that it's safe to quietly undo mnt_count increment and leaves dropping
the reference to caller, where it'll be a full-blown mntput().
Check under mount_lock is needed; leaving the current one done before
taking that makes no sense - it's nowhere near common enough to bother
with.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 65781e19dc ]
do_umount() analogue of the race fixed in 119e1ef80e "fix
__legitimize_mnt()/mntput() race". Here we want to make sure that
if __legitimize_mnt() doesn't notice our lock_mount_hash(), we will
notice their refcount increment. Harder to hit than mntput_no_expire()
one, fortunately, and consequences are milder (sync umount acting
like umount -l on a rare race with RCU pathwalk hitting at just the
wrong time instead of use-after-free galore mntput_no_expire()
counterpart used to be hit). Still a bug...
Fixes: 48a066e72d ("RCU'd vfsmounts")
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 0d039eac6e ]
Normally do_lock_mount(path, _) is locking a mountpoint pinned by
*path and at the time when matching unlock_mount() unlocks that
location it is still pinned by the same thing.
Unfortunately, for 'beneath' case it's no longer that simple -
the object being locked is not the one *path points to. It's the
mountpoint of path->mnt. The thing is, without sufficient locking
->mnt_parent may change under us and none of the locks are held
at that point. The rules are
* mount_lock stabilizes m->mnt_parent for any mount m.
* namespace_sem stabilizes m->mnt_parent, provided that
m is mounted.
* if either of the above holds and refcount of m is positive,
we are guaranteed the same for refcount of m->mnt_parent.
namespace_sem nests inside inode_lock(), so do_lock_mount() has
to take inode_lock() before grabbing namespace_sem. It does
recheck that path->mnt is still mounted in the same place after
getting namespace_sem, and it does take care to pin the dentry.
It is needed, since otherwise we might end up with racing mount --move
(or umount) happening while we were getting locks; in that case
dentry would no longer be a mountpoint and could've been evicted
on memory pressure along with its inode - not something you want
when grabbing lock on that inode.
However, pinning a dentry is not enough - the matching mount is
also pinned only by the fact that path->mnt is mounted on top it
and at that point we are not holding any locks whatsoever, so
the same kind of races could end up with all references to
that mount gone just as we are about to enter inode_lock().
If that happens, we are left with filesystem being shut down while
we are holding a dentry reference on it; results are not pretty.
What we need to do is grab both dentry and mount at the same time;
that makes inode_lock() safe *and* avoids the problem with fs getting
shut down under us. After taking namespace_sem we verify that
path->mnt is still mounted (which stabilizes its ->mnt_parent) and
check that it's still mounted at the same place. From that point
on to the matching namespace_unlock() we are guaranteed that
mount/dentry pair we'd grabbed are also pinned by being the mountpoint
of path->mnt, so we can quietly drop both the dentry reference (as
the current code does) and mnt one - it's OK to do under namespace_sem,
since we are not dropping the final refs.
That solves the problem on do_lock_mount() side; unlock_mount()
also has one, since dentry is guaranteed to stay pinned only until
the namespace_unlock(). That's easy to fix - just have inode_unlock()
done earlier, while it's still pinned by mp->m_dentry.
Fixes: 6ac3928156 "fs: allow to mount beneath top mount" # v6.5+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 056d33137b upstream.
Currently these mount options aren't accessible via statmount().
The read handler for /proc/#/mountinfo calls security_sb_show_options()
to emit the security options after emitting superblock flag options, but
before calling sb->s_op->show_options.
Have statmount_mnt_opts() call security_sb_show_options() before
calling ->show_options.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241115-statmount-v2-2-cd29aeff9cbb@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 5eb9871053 ("fs: fix adding security options to statmount.mnt_opt")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 344bac8f0d upstream.
Move mnt->mnt_node into the union with mnt->mnt_rcu and mnt->mnt_llist
instead of keeping it with mnt->mnt_list. This allows us to use
RB_CLEAR_NODE(&mnt->mnt_node) in umount_tree() as well as
list_empty(&mnt->mnt_node). That in turn allows us to remove MNT_ONRB.
This also fixes the bug reported in [1] where seemingly MNT_ONRB wasn't
set in @mnt->mnt_flags even though the mount was present in the mount
rbtree of the mount namespace.
The root cause is the following race. When a btrfs subvolume is mounted
a temporary mount is created:
btrfs_get_tree_subvol()
{
mnt = fc_mount()
// Register the newly allocated mount with sb->mounts:
lock_mount_hash();
list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);
unlock_mount_hash();
}
and registered on sb->s_mounts. Later it is added to an anonymous mount
namespace via mount_subvol():
-> mount_subvol()
-> mount_subtree()
-> alloc_mnt_ns()
mnt_add_to_ns()
vfs_path_lookup()
put_mnt_ns()
The mnt_add_to_ns() call raises MNT_ONRB in @mnt->mnt_flags. If someone
concurrently does a ro remount:
reconfigure_super()
-> sb_prepare_remount_readonly()
{
list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
}
all mounts registered in sb->s_mounts are visited and first
MNT_WRITE_HOLD is raised, then MNT_READONLY is raised, and finally
MNT_WRITE_HOLD is removed again.
The flag modification for MNT_WRITE_HOLD/MNT_READONLY and MNT_ONRB race
so MNT_ONRB might be lost.
Fixes: 2eea9ce431 ("mounts: keep list of mounts in an rbtree")
Cc: <stable@kernel.org> # v6.8+
Link: https://lore.kernel.org/r/20241215-vfs-6-14-mount-work-v1-1-fd55922c4af8@kernel.org
Link: https://lore.kernel.org/r/ec6784ed-8722-4695-980a-4400d4e7bd1a@gmx.com [1]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull fuse updates from Miklos Szeredi:
- Add support for idmapped fuse mounts (Alexander Mikhalitsyn)
- Add optimization when checking for writeback (yangyun)
- Add tracepoints (Josef Bacik)
- Clean up writeback code (Joanne Koong)
- Clean up request queuing (me)
- Misc fixes
* tag 'fuse-update-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (32 commits)
fuse: use exclusive lock when FUSE_I_CACHE_IO_MODE is set
fuse: clear FR_PENDING if abort is detected when sending request
fs/fuse: convert to use invalid_mnt_idmap
fs/mnt_idmapping: introduce an invalid_mnt_idmap
fs/fuse: introduce and use fuse_simple_idmap_request() helper
fs/fuse: fix null-ptr-deref when checking SB_I_NOIDMAP flag
fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPEN
virtio_fs: allow idmapped mounts
fuse: allow idmapped mounts
fuse: warn if fuse_access is called when idmapped mounts are allowed
fuse: handle idmappings properly in ->write_iter()
fuse: support idmapped ->rename op
fuse: support idmapped ->set_acl
fuse: drop idmap argument from __fuse_get_acl
fuse: support idmapped ->setattr op
fuse: support idmapped ->permission inode op
fuse: support idmapped getattr inode op
fuse: support idmap for mkdir/mknod/symlink/create/tmpfile
fuse: support idmapped FUSE_EXT_GROUPS
fuse: add an idmap argument to fuse_simple_request
...
Pull 'struct fd' updates from Al Viro:
"Just the 'struct fd' layout change, with conversion to accessor
helpers"
* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add struct fd constructors, get rid of __to_fd()
struct fd: representation change
introduce fd_file(), convert all accessors to it.
Pull vfs mount updates from Christian Brauner:
"Recently, we added the ability to list mounts in other mount
namespaces and the ability to retrieve namespace file descriptors
without having to go through procfs by deriving them from pidfds.
This extends nsfs in two ways:
(1) Add the ability to retrieve information about a mount namespace
via NS_MNT_GET_INFO.
This will return the mount namespace id and the number of mounts
currently in the mount namespace. The number of mounts can be
used to size the buffer that needs to be used for listmount() and
is in general useful without having to actually iterate through
all the mounts.
The structure is extensible.
(2) Add the ability to iterate through all mount namespaces over
which the caller holds privilege returning the file descriptor
for the next or previous mount namespace.
To retrieve a mount namespace the caller must be privileged wrt
to it's owning user namespace. This means that PID 1 on the host
can list all mounts in all mount namespaces or that a container
can list all mounts of its nested containers.
Optionally pass a structure for NS_MNT_GET_INFO with
NS_MNT_GET_{PREV,NEXT} to retrieve information about the mount
namespace in one go.
(1) and (2) can be implemented for other namespace types easily.
Together with recent api additions this means one can iterate through
all mounts in all mount namespaces without ever touching procfs.
The commit message in 49224a345c ('Merge patch series "nsfs: iterate
through mount namespaces"') contains example code how to do this"
* tag 'vfs-6.12.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
nsfs: iterate through mount namespaces
file: add fput() cleanup helper
fs: add put_mnt_ns() cleanup helper
fs: allow mount namespace fd
Right now we determine if filesystem support vfs idmappings or not basing
on the FS_ALLOW_IDMAP flag presence. This "static" way works perfecly well
for local filesystems like ext4, xfs, btrfs, etc. But for network-like
filesystems like fuse, cephfs this approach is not ideal, because sometimes
proper support of vfs idmaps requires some extensions for the on-wire
protocol, which implies that changes have to be made not only in the Linux
kernel code but also in the 3rd party components like libfuse, cephfs MDS
server and so on.
We have seen that issue during our work on cephfs idmapped mounts [1] with
Christian, but right now I'm working on the idmapped mounts support for
fuse/virtiofs and I think that it is a right time for this extension.
[1] 5ccd8530dd ("ceph: handle idmapped mounts in create_request_message()")
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If no page could be allocated, an error pointer was used as format
string in pr_warn.
Rearrange the code to return early in case of OOM. Also add a check
for the return value of d_path.
Fixes: f8b92ba67c ("mount: Add mount warning for impending timestamp expiry")
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Link: https://lore.kernel.org/r/20240730085856.32385-1-olaf@aepfle.de
[brauner: rewrite commit and commit message]
Signed-off-by: Christian Brauner <brauner@kernel.org>
For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
This commit converts (almost) all of f.file to
fd_file(f). It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).
NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).
[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Christian Brauner <brauner@kernel.org> says:
Recently, we added the ability to list mounts in other mount namespaces
and the ability to retrieve namespace file descriptors without having to
go through procfs by deriving them from pidfds.
This extends nsfs in two ways:
(1) Add the ability to retrieve information about a mount namespace via
NS_MNT_GET_INFO. This will return the mount namespace id and the
number of mounts currently in the mount namespace. The number of
mounts can be used to size the buffer that needs to be used for
listmount() and is in general useful without having to actually
iterate through all the mounts.
The structure is extensible.
(2) Add the ability to iterate through all mount namespaces over which
the caller holds privilege returning the file descriptor for the
next or previous mount namespace.
To retrieve a mount namespace the caller must be privileged wrt to
it's owning user namespace. This means that PID 1 on the host can
list all mounts in all mount namespaces or that a container can list
all mounts of its nested containers.
Optionally pass a structure for NS_MNT_GET_INFO with
NS_MNT_GET_{PREV,NEXT} to retrieve information about the mount
namespace in one go.
(1) and (2) can be implemented for other namespace types easily.
Together with recent api additions this means one can iterate through
all mounts in all mount namespaces without ever touching procfs. Here's
a sample program list_all_mounts_everywhere.c:
// SPDX-License-Identifier: GPL-2.0-or-later
#define _GNU_SOURCE
#include <asm/unistd.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <linux/stat.h>
#include <sched.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/pidfd.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#define die_errno(format, ...) \
do { \
fprintf(stderr, "%m | %s: %d: %s: " format "\n", __FILE__, \
__LINE__, __func__, ##__VA_ARGS__); \
exit(EXIT_FAILURE); \
} while (0)
/* Get the id for a mount namespace */
#define NS_GET_MNTNS_ID _IO(0xb7, 0x5)
/* Get next mount namespace. */
struct mnt_ns_info {
__u32 size;
__u32 nr_mounts;
__u64 mnt_ns_id;
};
#define MNT_NS_INFO_SIZE_VER0 16 /* size of first published struct */
/* Get information about namespace. */
#define NS_MNT_GET_INFO _IOR(0xb7, 10, struct mnt_ns_info)
/* Get next namespace. */
#define NS_MNT_GET_NEXT _IOR(0xb7, 11, struct mnt_ns_info)
/* Get previous namespace. */
#define NS_MNT_GET_PREV _IOR(0xb7, 12, struct mnt_ns_info)
#define PIDFD_GET_MNT_NAMESPACE _IO(0xFF, 3)
#define STATX_MNT_ID_UNIQUE 0x00004000U /* Want/got extended stx_mount_id */
#define __NR_listmount 458
#define __NR_statmount 457
/*
* @mask bits for statmount(2)
*/
#define STATMOUNT_SB_BASIC 0x00000001U /* Want/got sb_... */
#define STATMOUNT_MNT_BASIC 0x00000002U /* Want/got mnt_... */
#define STATMOUNT_PROPAGATE_FROM 0x00000004U /* Want/got propagate_from */
#define STATMOUNT_MNT_ROOT 0x00000008U /* Want/got mnt_root */
#define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */
#define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */
#define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */
#define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */
struct statmount {
__u32 size; /* Total size, including strings */
__u32 mnt_opts;
__u64 mask; /* What results were written */
__u32 sb_dev_major; /* Device ID */
__u32 sb_dev_minor;
__u64 sb_magic; /* ..._SUPER_MAGIC */
__u32 sb_flags; /* SB_{RDONLY,SYNCHRONOUS,DIRSYNC,LAZYTIME} */
__u32 fs_type; /* [str] Filesystem type */
__u64 mnt_id; /* Unique ID of mount */
__u64 mnt_parent_id; /* Unique ID of parent (for root == mnt_id) */
__u32 mnt_id_old; /* Reused IDs used in proc/.../mountinfo */
__u32 mnt_parent_id_old;
__u64 mnt_attr; /* MOUNT_ATTR_... */
__u64 mnt_propagation; /* MS_{SHARED,SLAVE,PRIVATE,UNBINDABLE} */
__u64 mnt_peer_group; /* ID of shared peer group */
__u64 mnt_master; /* Mount receives propagation from this ID */
__u64 propagate_from; /* Propagation from in current namespace */
__u32 mnt_root; /* [str] Root of mount relative to root of fs */
__u32 mnt_point; /* [str] Mountpoint relative to current root */
__u64 mnt_ns_id;
__u64 __spare2[49];
char str[]; /* Variable size part containing strings */
};
struct mnt_id_req {
__u32 size;
__u32 spare;
__u64 mnt_id;
__u64 param;
__u64 mnt_ns_id;
};
#define MNT_ID_REQ_SIZE_VER1 32 /* sizeof second published struct */
#define LSMT_ROOT 0xffffffffffffffff /* root mount */
static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
struct statmount *stmnt, size_t bufsize, unsigned int flags)
{
struct mnt_id_req req = {
.size = MNT_ID_REQ_SIZE_VER1,
.mnt_id = mnt_id,
.param = mask,
.mnt_ns_id = mnt_ns_id,
};
return syscall(__NR_statmount, &req, stmnt, bufsize, flags);
}
static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id,
__u64 mask, unsigned int flags)
{
size_t bufsize = 1 << 15;
struct statmount *stmnt = NULL, *tmp = NULL;
int ret;
for (;;) {
tmp = realloc(stmnt, bufsize);
if (!tmp)
goto out;
stmnt = tmp;
ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags);
if (!ret)
return stmnt;
if (errno != EOVERFLOW)
goto out;
bufsize <<= 1;
if (bufsize >= UINT_MAX / 2)
goto out;
}
out:
free(stmnt);
printf("statmount failed");
return NULL;
}
static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id,
__u64 list[], size_t num, unsigned int flags)
{
struct mnt_id_req req = {
.size = MNT_ID_REQ_SIZE_VER1,
.mnt_id = mnt_id,
.param = last_mnt_id,
.mnt_ns_id = mnt_ns_id,
};
return syscall(__NR_listmount, &req, list, num, flags);
}
int main(int argc, char *argv[])
{
#define LISTMNT_BUFFER 10
__u64 list[LISTMNT_BUFFER], last_mnt_id = 0;
int ret, pidfd, fd_mntns;
struct mnt_ns_info info = {};
pidfd = pidfd_open(getpid(), 0);
if (pidfd < 0)
die_errno("pidfd_open failed");
fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0);
if (fd_mntns < 0)
die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed");
ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info);
if (ret < 0)
die_errno("ioctl(NS_GET_MNTNS_ID) failed");
printf("Listing %u mounts for mount namespace %d:%llu\n", info.nr_mounts, fd_mntns, info.mnt_ns_id);
for (;;) {
ssize_t nr_mounts;
next:
nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id, info.mnt_ns_id, list, LISTMNT_BUFFER, 0);
if (nr_mounts <= 0) {
printf("Finished listing mounts for mount namespace %d:%llu\n\n", fd_mntns, info.mnt_ns_id);
ret = ioctl(fd_mntns, NS_MNT_GET_NEXT, 0);
if (ret < 0)
die_errno("ioctl(NS_MNT_GET_NEXT) failed");
close(ret);
ret = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info);
if (ret < 0) {
if (errno == ENOENT) {
printf("Finished listing all mount namespaces\n");
exit(0);
}
die_errno("ioctl(NS_MNT_GET_NEXT) failed");
}
close(fd_mntns);
fd_mntns = ret;
last_mnt_id = 0;
printf("Listing %u mounts for mount namespace %d:%llu\n", info.nr_mounts, fd_mntns, info.mnt_ns_id);
goto next;
}
for (size_t cur = 0; cur < nr_mounts; cur++) {
struct statmount *stmnt;
last_mnt_id = list[cur];
stmnt = sys_statmount(last_mnt_id, info.mnt_ns_id,
STATMOUNT_SB_BASIC |
STATMOUNT_MNT_BASIC |
STATMOUNT_MNT_ROOT |
STATMOUNT_MNT_POINT |
STATMOUNT_MNT_NS_ID |
STATMOUNT_MNT_OPTS |
STATMOUNT_FS_TYPE,
0);
if (!stmnt) {
printf("Failed to statmount(%llu) in mount namespace(%llu)\n", last_mnt_id, info.mnt_ns_id);
continue;
}
printf("mnt_id(%u/%llu) | mnt_parent_id(%u/%llu): %s @ %s ==> %s with options: %s\n",
stmnt->mnt_id_old, stmnt->mnt_id,
stmnt->mnt_parent_id_old, stmnt->mnt_parent_id,
stmnt->str + stmnt->fs_type,
stmnt->str + stmnt->mnt_root,
stmnt->str + stmnt->mnt_point,
stmnt->str + stmnt->mnt_opts);
free(stmnt);
}
}
exit(0);
}
* patches from https://lore.kernel.org/r/20240719-work-mount-namespace-v1-0-834113cab0d2@kernel.org:
nsfs: iterate through mount namespaces
file: add fput() cleanup helper
fs: add put_mnt_ns() cleanup helper
fs: allow mount namespace fd
Signed-off-by: Christian Brauner <brauner@kernel.org>
It is already possible to list mounts in other mount namespaces and to
retrieve namespace file descriptors without having to go through procfs
by deriving them from pidfds.
Augment these abilities by adding the ability to retrieve information
about a mount namespace via NS_MNT_GET_INFO. This will return the mount
namespace id and the number of mounts currently in the mount namespace.
The number of mounts can be used to size the buffer that needs to be
used for listmount() and is in general useful without having to actually
iterate through all the mounts. The structure is extensible.
And add the ability to iterate through all mount namespaces over which
the caller holds privilege returning the file descriptor for the next or
previous mount namespace.
To retrieve a mount namespace the caller must be privileged wrt to it's
owning user namespace. This means that PID 1 on the host can list all
mounts in all mount namespaces or that a container can list all mounts
of its nested containers.
Optionally pass a structure for NS_MNT_GET_INFO with
NS_MNT_GET_{PREV,NEXT} to retrieve information about the mount namespace
in one go. Both ioctls can be implemented for other namespace types
easily.
Together with recent api additions this means one can iterate through
all mounts in all mount namespaces without ever touching procfs.
Link: https://lore.kernel.org/r/20240719-work-mount-namespace-v1-5-834113cab0d2@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull vfs mount query updates from Christian Brauner:
"This contains work to extend the abilities of listmount() and
statmount() and various fixes and cleanups.
Features:
- Allow iterating through mounts via listmount() from newest to
oldest. This makes it possible for mount(8) to keep iterating the
mount table in reverse order so it gets newest mounts first.
- Relax permissions on listmount() and statmount().
It's not necessary to have capabilities in the initial namespace:
it is sufficient to have capabilities in the owning namespace of
the mount namespace we're located in to list unreachable mounts in
that namespace.
- Extend both listmount() and statmount() to list and stat mounts in
foreign mount namespaces.
Currently the only way to iterate over mount entries in mount
namespaces that aren't in the caller's mount namespace is by
crawling through /proc in order to find /proc/<pid>/mountinfo for
the relevant mount namespace.
This is both very clumsy and hugely inefficient. So extend struct
mnt_id_req with a new member that allows to specify the mount
namespace id of the mount namespace we want to look at.
Luckily internally we already have most of the infrastructure for
this so we just need to expose it to userspace. Give userspace a
way to retrieve the id of a mount namespace via statmount() and
through a new nsfs ioctl() on mount namespace file descriptor.
This comes with appropriate selftests.
- Expose mount options through statmount().
Currently if userspace wants to get mount options for a mount and
with statmount(), they still have to open /proc/<pid>/mountinfo to
parse mount options. Simply the information through statmount()
directly.
Afterwards it's possible to only rely on statmount() and
listmount() to retrieve all and more information than
/proc/<pid>/mountinfo provides.
This comes with appropriate selftests.
Fixes:
- Avoid copying to userspace under the namespace semaphore in
listmount.
Cleanups:
- Simplify the error handling in listmount by relying on our newly
added cleanup infrastructure.
- Refuse invalid mount ids early for both listmount and statmount"
* tag 'vfs-6.11.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: reject invalid last mount id early
fs: refuse mnt id requests with invalid ids early
fs: find rootfs mount of the mount namespace
fs: only copy to userspace on success in listmount()
sefltests: extend the statmount test for mount options
fs: use guard for namespace_sem in statmount()
fs: export mount options via statmount()
fs: rename show_mnt_opts -> show_vfsmnt_opts
selftests: add a test for the foreign mnt ns extensions
fs: add an ioctl to get the mnt ns id from nsfs
fs: Allow statmount() in foreign mount namespace
fs: Allow listmount() in foreign mount namespace
fs: export the mount ns id via statmount
fs: keep an index of current mount namespaces
fs: relax permissions for statmount()
listmount: allow listing in reverse order
fs: relax permissions for listmount()
fs: simplify error handling
fs: don't copy to userspace under namespace semaphore
path: add cleanup helper
The method we used was predicated on the assumption that the mount
immediately following the root mount of the mount namespace would be the
rootfs mount of the namespace. That's not always the case though. For
example:
ID PARENT ID
408 412 0:60 /containers/overlay-containers/bc391117192b32071b22ef2083ebe7735d5c390f87a5779e02faf79ba0746ceb/userdata/hosts /etc/hosts rw,nosuid,nodev,relatime - tmpfs tmpfs rw,size=954664k,nr_inodes=238666,mode=700,uid=1000,gid=1000,inode64
409 414 0:61 / /dev/shm rw,nosuid,nodev,noexec,relatime - tmpfs shm rw,size=64000k,uid=1000,gid=1000,inode64
410 412 0:60 /containers/overlay-containers/bc391117192b32071b22ef2083ebe7735d5c390f87a5779e02faf79ba0746ceb/userdata/.containerenv /run/.containerenv rw,nosuid,nodev,relatime - tmpfs tmpfs rw,size=954664k,nr_inodes=238666,mode=700,uid=1000,gid=1000,inode64
411 412 0:60 /containers/overlay-containers/bc391117192b32071b22ef2083ebe7735d5c390f87a5779e02faf79ba0746ceb/userdata/hostname /etc/hostname rw,nosuid,nodev,relatime - tmpfs tmpfs rw,size=954664k,nr_inodes=238666,mode=700,uid=1000,gid=1000,inode64
412 363 0:65 / / rw,relatime - overlay overlay rw,lowerdir=/home/user1/.local/share/containers/storage/overlay/l/JS65SUCGTPCP2EEBHLRP4UCFI5:/home/user1/.local/share/containers/storage/overlay/l/DLW22KVDWUNI4242D6SDJ5GKCL [...]
413 412 0:68 / /proc rw,nosuid,nodev,noexec,relatime - proc proc rw
414 412 0:69 / /dev rw,nosuid - tmpfs tmpfs rw,size=65536k,mode=755,uid=1000,gid=1000,inode64
415 412 0:70 / /sys ro,nosuid,nodev,noexec,relatime - sysfs sysfs rw
416 414 0:71 / /dev/pts rw,nosuid,noexec,relatime - devpts devpts rw,gid=100004,mode=620,ptmxmode=666
417 414 0:67 / /dev/mqueue rw,nosuid,nodev,noexec,relatime - mqueue mqueue rw
418 415 0:27 / /sys/fs/cgroup ro,nosuid,nodev,noexec,relatime - cgroup2 cgroup2 rw,nsdelegate,memory_recursiveprot
419 414 0:6 /null /dev/null rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
420 414 0:6 /zero /dev/zero rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
422 414 0:6 /full /dev/full rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
423 414 0:6 /tty /dev/tty rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
430 414 0:6 /random /dev/random rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
431 414 0:6 /urandom /dev/urandom rw,nosuid,noexec - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
433 413 0:72 / /proc/acpi ro,relatime - tmpfs tmpfs rw,size=0k,uid=1000,gid=1000,inode64
440 413 0:6 /null /proc/kcore ro,nosuid - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
441 413 0:6 /null /proc/keys ro,nosuid - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
442 413 0:6 /null /proc/timer_list ro,nosuid - devtmpfs devtmpfs rw,size=4096k,nr_inodes=1179282,mode=755,inode64
443 413 0:73 / /proc/scsi ro,relatime - tmpfs tmpfs rw,size=0k,uid=1000,gid=1000,inode64
444 415 0:74 / /sys/firmware ro,relatime - tmpfs tmpfs rw,size=0k,uid=1000,gid=1000,inode64
445 415 0:75 / /sys/dev/block ro,relatime - tmpfs tmpfs rw,size=0k,uid=1000,gid=1000,inode64
446 413 0:68 /bus /proc/bus ro,nosuid,nodev,noexec,relatime - proc proc rw
447 413 0:68 /fs /proc/fs ro,nosuid,nodev,noexec,relatime - proc proc rw
448 413 0:68 /irq /proc/irq ro,nosuid,nodev,noexec,relatime - proc proc rw
449 413 0:68 /sys /proc/sys ro,nosuid,nodev,noexec,relatime - proc proc rw
450 413 0:68 /sysrq-trigger /proc/sysrq-trigger ro,nosuid,nodev,noexec,relatime - proc proc rw
364 414 0:71 /0 /dev/console rw,relatime - devpts devpts rw,gid=100004,mode=620,ptmxmode=666
In this mount table the root mount of the mount namespace is the mount
with id 363 (It isn't visible because it's literally just what the
rootfs mount is mounted upon and usually it's just a copy of the real
rootfs).
The rootfs mount that's mounted on the root mount of the mount namespace
is the mount with id 412. But the mount namespace contains mounts that
were created before the rootfs mount and thus have earlier mount ids. So
the first call to listmnt_next() would return the mount with the mount
id 408 and not the rootfs mount.
So we need to find the actual rootfs mount mounted on the root mount of
the mount namespace. This logic is also present in mntns_install() where
vfs_path_lookup() is used. We can't use this though as we're holding the
namespace semaphore. We could look at the children of the root mount of
the mount namespace directly but that also seems a bit out of place
while we have the rbtree. So let's just iterate through the rbtree
starting from the root mount of the mount namespace and find the mount
whose parent is the root mount of the mount namespace. That mount will
usually appear very early in the rbtree and afaik there can only be one.
IOW, it would be very strange if we ended up with a root mount of a
mount namespace that has shadow mounts.
Fixes: 0a3deb1185 ("fs: Allow listmount() in foreign mount namespace") # mainline only
Signed-off-by: Christian Brauner <brauner@kernel.org>
Avoid copying when we failed to, or didn't have any mounts to list.
Fixes: cb54ef4f05 ("fs: don't copy to userspace under namespace semaphore") # mainline only
Signed-off-by: Christian Brauner <brauner@kernel.org>
statmount() can export arbitrary strings, so utilize the __spare1 slot
for a mnt_opts string pointer, and then support asking for and setting
the mount options during statmount(). This calls into the helper for
showing mount options, which already uses a seq_file, so fits in nicely
with our existing mechanism for exporting strings via statmount().
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/3aa6bf8bd5d0a21df9ebd63813af8ab532c18276.1719257716.git.josef@toxicpanda.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
[brauner: only call sb->s_op->show_options()]
Signed-off-by: Christian Brauner <brauner@kernel.org>
util-linux is about to implement listmount() and statmount() support.
Karel requested the ability to scan the mount table in backwards order
because that's what libmount currently does in order to get the latest
mount first. We currently don't support this in listmount(). Add a new
LISTMOUNT_REVERSE flag to allow listing mounts in reverse order. For
example, listing all child mounts of /sys without LISTMOUNT_REVERSE
gives:
/sys/kernel/security @ mnt_id: 4294968369
/sys/fs/cgroup @ mnt_id: 4294968370
/sys/firmware/efi/efivars @ mnt_id: 4294968371
/sys/fs/bpf @ mnt_id: 4294968372
/sys/kernel/tracing @ mnt_id: 4294968373
/sys/kernel/debug @ mnt_id: 4294968374
/sys/fs/fuse/connections @ mnt_id: 4294968375
/sys/kernel/config @ mnt_id: 4294968376
whereas with LISTMOUNT_REVERSE it gives:
/sys/kernel/config @ mnt_id: 4294968376
/sys/fs/fuse/connections @ mnt_id: 4294968375
/sys/kernel/debug @ mnt_id: 4294968374
/sys/kernel/tracing @ mnt_id: 4294968373
/sys/fs/bpf @ mnt_id: 4294968372
/sys/firmware/efi/efivars @ mnt_id: 4294968371
/sys/fs/cgroup @ mnt_id: 4294968370
/sys/kernel/security @ mnt_id: 4294968369
Link: https://lore.kernel.org/r/20240607-vfs-listmount-reverse-v1-4-7877a2bfa5e5@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Don't copy mount ids to userspace while holding the namespace semaphore.
We really shouldn't do that and I've gone through lenghts avoiding that
in statmount() already.
Limit the number of mounts that can be retrieved in one go to 1 million
mount ids. That's effectively 10 times the default limt of 100000 mounts
that we put on each mount namespace by default. Since listmount() is an
iterator limiting the number of mounts retrievable in one go isn't a
problem as userspace can just pick up where they left off.
Karel menti_ned that libmount will probably be reading the mount table
in "in small steps, 512 nodes per request. Nobody likes a tool that
takes too long in the kernel, and huge servers are unusual use cases.
Libmount will very probably provide API to define size of the step (IDs
per request)."
Reported-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240610-frettchen-liberal-a9a5c53865f8@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>
The newly used helper also checks for empty ("") paths.
NULL paths with any flag value other than AT_EMPTY_PATH go the usual
route and end up with -EFAULT to retain compatibility (Rust is abusing
calls of the sort to detect availability of statx).
This avoids path lookup code, lockref management, memory allocation and
in case of NULL path userspace memory access (which can be quite
expensive with SMAP on x86_64).
Benchmarked with statx(..., AT_EMPTY_PATH, ...) running on Sapphire
Rapids, with the "" path for the first two cases and NULL for the last
one.
Results in ops/s:
stock: 4231237
pre-check: 5944063 (+40%)
NULL path: 6601619 (+11%/+56%)
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240625151807.620812-1-mjguzik@gmail.com
Tested-by: Xi Ruoyao <xry111@xry111.site>
[brauner: use path_mounted() and other tweaks]
Signed-off-by: Christian Brauner <brauner@kernel.org>
by employing `copy mount tree from src to dst` concept.
This involves renaming the opaque variables (e.g., p, q, r, s)
to be more descriptive, aiming to make the code easier to understand.
Changes:
mnt -> src_root (root of the tree to copy)
r -> src_root_child (direct child of the root being cloning)
p -> src_parent (parent of src_mnt)
s -> src_mnt (current mount being copying)
parent -> dst_parent (parent of dst_child)
q -> dst_mnt (freshly cloned mount)
Signed-off-by: Jemmy <jemmywong512@gmail.com>
Link: https://lore.kernel.org/r/20240606173912.99442-1-jemmywong512@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
A current limitation of open_by_handle_at() is that it's currently not possible
to use it from within containers at all because we require CAP_DAC_READ_SEARCH
in the initial namespace. That's unfortunate because there are scenarios where
using open_by_handle_at() from within containers.
Two examples:
(1) cgroupfs allows to encode cgroups to file handles and reopen them with
open_by_handle_at().
(2) Fanotify allows placing filesystem watches they currently aren't usable in
containers because the returned file handles cannot be used.
Here's a proposal for relaxing the permission check for open_by_handle_at().
(1) Opening file handles when the caller has privileges over the filesystem
(1.1) The caller has an unobstructed view of the filesystem.
(1.2) The caller has permissions to follow a path to the file handle.
This doesn't address the problem of opening a file handle when only a portion
of a filesystem is exposed as is common in containers by e.g., bind-mounting a
subtree. The proposal to solve this use-case is:
(2) Opening file handles when the caller has privileges over a subtree
(2.1) The caller is able to reach the file from the provided mount fd.
(2.2) The caller has permissions to construct an unobstructed path to the
file handle.
(2.3) The caller has permissions to follow a path to the file handle.
The relaxed permission checks are currently restricted to directory file
handles which are what both cgroupfs and fanotify need. Handling disconnected
non-directory file handles would lead to a potentially non-deterministic api.
If a disconnected non-directory file handle is provided we may fail to decode
a valid path that we could use for permission checking. That in itself isn't a
problem as we would just return EACCES in that case. However, confusion may
arise if a non-disconnected dentry ends up in the cache later and those opening
the file handle would suddenly succeed.
* It's potentially possible to use timing information (side-channel) to infer
whether a given inode exists. I don't think that's particularly
problematic. Thanks to Jann for bringing this to my attention.
* An unrelated note (IOW, these are thoughts that apply to
open_by_handle_at() generically and are unrelated to the changes here):
Jann pointed out that we should verify whether deleted files could
potentially be reopened through open_by_handle_at(). I don't think that's
possible though.
Another potential thing to check is whether open_by_handle_at() could be
abused to open internal stuff like memfds or gpu stuff. I don't think so
but I haven't had the time to completely verify this.
This dates back to discussions Amir and I had quite some time ago and thanks to
him for providing a lot of details around the export code and related patches!
Link: https://lore.kernel.org/r/20240524-vfs-open_by_handle_at-v1-1-3d4b7d22736b@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
When we added mount_setattr() I added additional checks compared to the
legacy do_reconfigure_mnt() and do_change_type() helpers used by regular
mount(2). If that mount had a parent then verify that the caller and the
mount namespace the mount is attached to match and if not make sure that
it's an anonymous mount.
The real rootfs falls into neither category. It is neither an anoymous
mount because it is obviously attached to the initial mount namespace
but it also obviously doesn't have a parent mount. So that means legacy
mount(2) allows changing mount properties on the real rootfs but
mount_setattr(2) blocks this. I never thought much about this but of
course someone on this planet of earth changes properties on the real
rootfs as can be seen in [1].
Since util-linux finally switched to the new mount api in 2.39 not so
long ago it also relies on mount_setattr() and that surfaced this issue
when Fedora 39 finally switched to it. Fix this.
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2256843
Link: https://lore.kernel.org/r/20240206-vfs-mount-rootfs-v1-1-19b335eee133@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: Karel Zak <kzak@redhat.com>
Cc: stable@vger.kernel.org # v5.12+
Signed-off-by: Christian Brauner <brauner@kernel.org>
Linus pointed out that there's error handling and naming issues in the
that we should rewrite:
* Perform the access checks for the buffer before actually doing any
work instead of doing it during the iteration.
* Rename the arguments to listmount() and do_listmount() to clarify what
the arguments are used for.
* Get rid of the pointless ctr variable and overflow checking.
* Get rid of the pointless speculation check.
Link: https://lore.kernel.org/r/CAHk-=wjh6Cypo8WC-McXgSzCaou3UXccxB+7PVeSuGR8AjCphg@mail.gmail.com
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Pull sysctl updates from Luis Chamberlain:
"To help make the move of sysctls out of kernel/sysctl.c not incur a
size penalty sysctl has been changed to allow us to not require the
sentinel, the final empty element on the sysctl array. Joel Granados
has been doing all this work.
In the v6.6 kernel we got the major infrastructure changes required to
support this. For v6.7 we had all arch/ and drivers/ modified to
remove the sentinel. For v6.8-rc1 we get a few more updates for fs/
directory only.
The kernel/ directory is left but we'll save that for v6.9-rc1 as
those patches are still being reviewed. After that we then can expect
also the removal of the no longer needed check for procname == NULL.
Let us recap the purpose of this work:
- this helps reduce the overall build time size of the kernel and run
time memory consumed by the kernel by about ~64 bytes per array
- the extra 64-byte penalty is no longer inncurred now when we move
sysctls out from kernel/sysctl.c to their own files
Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to
see further work by Thomas Weißschuh with the constificatin of the
struct ctl_table.
Due to Joel Granados's work, and to help bring in new blood, I have
suggested for him to become a maintainer and he's accepted. So for
v6.9-rc1 I look forward to seeing him sent you a pull request for
further sysctl changes. This also removes Iurii Zaikin as a maintainer
as he has moved on to other projects and has had no time to help at
all"
* tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
sysctl: remove struct ctl_path
sysctl: delete unused define SYSCTL_PERM_EMPTY_DIR
coda: Remove the now superfluous sentinel elements from ctl_table array
sysctl: Remove the now superfluous sentinel elements from ctl_table array
fs: Remove the now superfluous sentinel elements from ctl_table array
cachefiles: Remove the now superfluous sentinel element from ctl_table array
sysclt: Clarify the results of selftest run
sysctl: Add a selftest for handling empty dirs
sysctl: Fix out of bounds access for empty sysctl registers
MAINTAINERS: Add Joel Granados as co-maintainer for proc sysctl
MAINTAINERS: remove Iurii Zaikin from proc sysctl
