Prepending security options was made conditional on sb->s_op->show_options,
but security options are independent of sb options.

Fixes: 056d33137bf9 ("fs: prepend statmount.mnt_opts string with security_sb_mnt_opts()")
Fixes: f9af549d1fd3 ("fs: export mount options via statmount()")
Cc: stable@vger.kernel.org # v6.11
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20250129151253.33241-1-mszeredi@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Just like it's normal for unset values to be zero, unset strings should be
empty instead of containing random values.

It seems to be a typical mistake that the mask returned by statmount is not
checked, which can result in various bugs.

With this fix, these bugs are prevented, since it is highly likely that
userspace would just want to turn the missing mask case into an empty
string anyway (most of the recently found cases are of this type).

Link: https://lore.kernel.org/all/CAJfpegsVCPfCn2DpM8iiYSS5DpMsLB8QBUCHecoj6s0Vxf4jzg@mail.gmail.com/
Fixes: 68385d77c05b ("statmount: simplify string option retrieval")
Fixes: 46eae99ef733 ("add statmount(2) syscall")
Cc: stable@vger.kernel.org # v6.8
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20250130121500.113446-1-mszeredi@redhat.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.

Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.

Created this by running an spatch followed by a sed command:
Spatch:
    virtual patch

    @
    depends on !(file in "net")
    disable optional_qualifier
    @

    identifier table_name != {
      watchdog_hardlockup_sysctl,
      iwcm_ctl_table,
      ucma_ctl_table,
      memory_allocation_profiling_sysctls,
      loadpin_sysctl_table
    };
    @@

    + const
    struct ctl_table table_name [] = { ... };

sed:
    sed --in-place \
      -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
      kernel/utsname_sysctl.c

Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>

Pull vfs mount updates from Christian Brauner:

 - Add a mountinfo program to demonstrate statmount()/listmount()

   Add a new "mountinfo" sample userland program that demonstrates how
   to use statmount() and listmount() to get at the same info that
   /proc/pid/mountinfo provides

 - Remove pointless nospec.h include

 - Prepend statmount.mnt_opts string with security_sb_mnt_opts()

   Currently these mount options aren't accessible via statmount()

 - Add new mount namespaces to mount namespace rbtree outside of the
   namespace semaphore

 - Lockless mount namespace lookup

   Currently we take the read lock when looking for a mount namespace to
   list mounts in. We can make this lockless. The simple search case can
   just use a sequence counter to detect concurrent changes to the
   rbtree

   For walking the list of mount namespaces sequentially via nsfs we
   keep a separate rcu list as rb_prev() and rb_next() aren't usable
   safely with rcu. Currently there is no primitive for retrieving the
   previous list member. To do this we need a new deletion primitive
   that doesn't poison the prev pointer and a corresponding retrieval
   helper

   Since creating mount namespaces is a relatively rare event compared
   with querying mounts in a foreign mount namespace this is worth it.
   Once libmount and systemd pick up this mechanism to list mounts in
   foreign mount namespaces this will be used very frequently

     - Add extended selftests for lockless mount namespace iteration

     - Add a sample program to list all mounts on the system, i.e., in
       all mount namespaces

 - Improve mount namespace iteration performance

   Make finding the last or first mount to start iterating the mount
   namespace from an O(1) operation and add selftests for iterating the
   mount table starting from the first and last mount

 - Use an xarray for the old mount id

   While the ida does use the xarray internally we can use it explicitly
   which allows us to increment the unique mount id under the xa lock.
   This allows us to remove the atomic as we're now allocating both ids
   in one go

 - Use a shared header for vfs sample programs

 - Fix build warnings for new sample program to list all mounts

* tag 'vfs-6.14-rc1.mount.v2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  samples/vfs: fix build warnings
  samples/vfs: use shared header
  samples/vfs/mountinfo: Use __u64 instead of uint64_t
  fs: remove useless lockdep assertion
  fs: use xarray for old mount id
  selftests: add listmount() iteration tests
  fs: cache first and last mount
  samples: add test-list-all-mounts
  selftests: remove unneeded include
  selftests: add tests for mntns iteration
  seltests: move nsfs into filesystems subfolder
  fs: simplify rwlock to spinlock
  fs: lockless mntns lookup for nsfs
  rculist: add list_bidir_{del,prev}_rcu()
  fs: lockless mntns rbtree lookup
  fs: add mount namespace to rbtree late
  fs: prepend statmount.mnt_opts string with security_sb_mnt_opts()
  mount: remove inlude/nospec.h include
  samples: add a mountinfo program to demonstrate statmount()/listmount()

Pull pidfs updates from Christian Brauner:

 - Rework inode number allocation

   Recently we received a patchset that aims to enable file handle
   encoding and decoding via name_to_handle_at(2) and
   open_by_handle_at(2).

   A crucical step in the patch series is how to go from inode number to
   struct pid without leaking information into unprivileged contexts.
   The issue is that in order to find a struct pid the pid number in the
   initial pid namespace must be encoded into the file handle via
   name_to_handle_at(2).

   This can be used by containers using a separate pid namespace to
   learn what the pid number of a given process in the initial pid
   namespace is. While this is a weak information leak it could be used
   in various exploits and in general is an ugly wart in the design.

   To solve this problem a new way is needed to lookup a struct pid
   based on the inode number allocated for that struct pid. The other
   part is to remove the custom inode number allocation on 32bit systems
   that is also an ugly wart that should go away.

   Allocate unique identifiers for struct pid by simply incrementing a
   64 bit counter and insert each struct pid into the rbtree so it can
   be looked up to decode file handles avoiding to leak actual pids
   across pid namespaces in file handles.

   On both 64 bit and 32 bit the same 64 bit identifier is used to
   lookup struct pid in the rbtree. On 64 bit the unique identifier for
   struct pid simply becomes the inode number. Comparing two pidfds
   continues to be as simple as comparing inode numbers.

   On 32 bit the 64 bit number assigned to struct pid is split into two
   32 bit numbers. The lower 32 bits are used as the inode number and
   the upper 32 bits are used as the inode generation number. Whenever a
   wraparound happens on 32 bit the 64 bit number will be incremented by
   2 so inode numbering starts at 2 again.

   When a wraparound happens on 32 bit multiple pidfds with the same
   inode number are likely to exist. This isn't a problem since before
   pidfs pidfds used the anonymous inode meaning all pidfds had the same
   inode number. On 32 bit sserspace can thus reconstruct the 64 bit
   identifier by retrieving both the inode number and the inode
   generation number to compare, or use file handles. This gives the
   same guarantees on both 32 bit and 64 bit.

 - Implement file handle support

   This is based on custom export operation methods which allows pidfs
   to implement permission checking and opening of pidfs file handles
   cleanly without hacking around in the core file handle code too much.

 - Support bind-mounts

   Allow bind-mounting pidfds. Similar to nsfs let's allow bind-mounts
   for pidfds. This allows pidfds to be safely recovered and checked for
   process recycling.

   Instead of checking d_ops for both nsfs and pidfs we could in a
   follow-up patch add a flag argument to struct dentry_operations that
   functions similar to file_operations->fop_flags.

* tag 'vfs-6.14-rc1.pidfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  selftests: add pidfd bind-mount tests
  pidfs: allow bind-mounts
  pidfs: lookup pid through rbtree
  selftests/pidfd: add pidfs file handle selftests
  pidfs: check for valid ioctl commands
  pidfs: implement file handle support
  exportfs: add permission method
  fhandle: pull CAP_DAC_READ_SEARCH check into may_decode_fh()
  exportfs: add open method
  fhandle: simplify error handling
  pseudofs: add support for export_ops
  pidfs: support FS_IOC_GETVERSION
  pidfs: remove 32bit inode number handling
  pidfs: rework inode number allocation

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Support caching symlink lengths in inodes

     The size is stored in a new union utilizing the same space as
     i_devices, thus avoiding growing the struct or taking up any more
     space

     When utilized it dodges strlen() in vfs_readlink(), giving about
     1.5% speed up when issuing readlink on /initrd.img on ext4

   - Add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag

     If a file system supports uncached buffered IO, it may set
     FOP_DONTCACHE and enable support for RWF_DONTCACHE.

     If RWF_DONTCACHE is attempted without the file system supporting
     it, it'll get errored with -EOPNOTSUPP

   - Enable VBOXGUEST and VBOXSF_FS on ARM64

     Now that VirtualBox is able to run as a host on arm64 (e.g. the
     Apple M3 processors) we can enable VBOXSF_FS (and in turn
     VBOXGUEST) for this architecture.

     Tested with various runs of bonnie++ and dbench on an Apple MacBook
     Pro with the latest Virtualbox 7.1.4 r165100 installed

  Cleanups:

   - Delay sysctl_nr_open check in expand_files()

   - Use kernel-doc includes in fiemap docbook

   - Use page->private instead of page->index in watch_queue

   - Use a consume fence in mnt_idmap() as it's heavily used in
     link_path_walk()

   - Replace magic number 7 with ARRAY_SIZE() in fc_log

   - Sort out a stale comment about races between fd alloc and dup2()

   - Fix return type of do_mount() from long to int

   - Various cosmetic cleanups for the lockref code

  Fixes:

   - Annotate spinning as unlikely() in __read_seqcount_begin

     The annotation already used to be there, but got lost in commit
     52ac39e5db51 ("seqlock: seqcount_t: Implement all read APIs as
     statement expressions")

   - Fix proc_handler for sysctl_nr_open

   - Flush delayed work in delayed fput()

   - Fix grammar and spelling in propagate_umount()

   - Fix ESP not readable during coredump

     In /proc/PID/stat, there is the kstkesp field which is the stack
     pointer of a thread. While the thread is active, this field reads
     zero. But during a coredump, it should have a valid value

     However, at the moment, kstkesp is zero even during coredump

   - Don't wake up the writer if the pipe is still full

   - Fix unbalanced user_access_end() in select code"

* tag 'vfs-6.14-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
  gfs2: use lockref_init for qd_lockref
  erofs: use lockref_init for pcl->lockref
  dcache: use lockref_init for d_lockref
  lockref: add a lockref_init helper
  lockref: drop superfluous externs
  lockref: use bool for false/true returns
  lockref: improve the lockref_get_not_zero description
  lockref: remove lockref_put_not_zero
  fs: Fix return type of do_mount() from long to int
  select: Fix unbalanced user_access_end()
  vbox: Enable VBOXGUEST and VBOXSF_FS on ARM64
  pipe_read: don't wake up the writer if the pipe is still full
  selftests: coredump: Add stackdump test
  fs/proc: do_task_stat: Fix ESP not readable during coredump
  fs: add RWF_DONTCACHE iocb and FOP_DONTCACHE file_operations flag
  fs: sort out a stale comment about races between fd alloc and dup2
  fs: Fix grammar and spelling in propagate_umount()
  fs: fc_log replace magic number 7 with ARRAY_SIZE()
  fs: use a consume fence in mnt_idmap()
  file: flush delayed work in delayed fput()
  ...

Fix the return type of do_mount() function from long to int to match its ac
tual behavior. The function only returns int values, and all callers, inclu
ding those in fs/namespace.c and arch/alpha/kernel/osf_sys.c, already treat
 the return value as int. This change improves type consistency across the
filesystem code and aligns the function signature with its existing impleme
ntation and usage.

Signed-off-by: Sentaro Onizuka <sentaro@amazon.com>
Link: https://lore.kernel.org/r/20250113151400.55512-1-sentaro@amazon.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

Bring in the fix for the mount namespace rbtree. It is used as the base
for the vfs mount work for this cycle and so shouldn't be applied
directly.

Signed-off-by: Christian Brauner <brauner@kernel.org>

mnt_ns_release() can run asynchronously via call_rcu() so hitting that
lockdep assertion means someone else already grabbed the
mnt_ns_tree_lock and causes a false positive. That assertion has likely
always been wrong. call_rcu() just makes it more likely to hit.

Link: https://lore.kernel.org/r/Z2PlT5rcRTIhCpft@ly-workstation
Link: https://lore.kernel.org/r/20241219-darben-quietschen-b6e1d80327bb@brauner
Reported-by: Lai, Yi <yi1.lai@linux.intel.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

While the ida does use the xarray internally we can use it explicitly
which allows us to increment the unique mount id under the xa lock.
This allows us to remove the atomic as we're now allocating both ids in
one go.

Link: https://lore.kernel.org/r/20241217-erhielten-regung-44bb1604ca8f@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>