[ Upstream commit 3e4bb2706817710d9461394da8b75be79981586b ]

Patch series "mm: expand mmap_prepare functionality and usage", v4.

This series expands the mmap_prepare functionality, which is intended to
replace the deprecated f_op->mmap hook which has been the source of bugs
and security issues for some time.

This series starts with some cleanup of existing mmap_prepare logic, then
adds documentation for the mmap_prepare call to make it easier for
filesystem and driver writers to understand how it works.

It then importantly adds a vm_ops->mapped hook, a key feature that was
missing from mmap_prepare previously - this is invoked when a driver which
specifies mmap_prepare has successfully been mapped but not merged with
another VMA.

mmap_prepare is invoked prior to a merge being attempted, so you cannot
manipulate state such as reference counts as if it were a new mapping.

The vm_ops->mapped hook allows a driver to perform tasks required at this
stage, and provides symmetry against subsequent vm_ops->open,close calls.

The series uses this to correct the afs implementation which wrongly
manipulated reference count at mmap_prepare time.

It then adds an mmap_prepare equivalent of vm_iomap_memory() -
mmap_action_simple_ioremap(), then uses this to update a number of drivers.

It then splits out the mmap_prepare compatibility layer (which allows for
invocation of mmap_prepare hooks in an mmap() hook) in such a way as to
allow for more incremental implementation of mmap_prepare hooks.

It then uses this to extend mmap_prepare usage in drivers.

Finally it adds an mmap_prepare equivalent of vm_map_pages(), which lays
the foundation for future work which will extend mmap_prepare to DMA
coherent mappings.

This patch (of 21):

Rather than passing arbitrary fields, pass a vm_area_desc pointer to mmap
prepare functions to mmap prepare, and an action and vma pointer to mmap
complete in order to put all the action-specific logic in the function
actually doing the work.

Additionally, allow mmap prepare functions to return an error so we can
error out as soon as possible if there is something logically incorrect in
the input.

Update remap_pfn_range_prepare() to properly check the input range for the
CoW case.

Also remove io_remap_pfn_range_complete(), as we can simply set up the
fields correctly in io_remap_pfn_range_prepare() and use
remap_pfn_range_complete() for this.

While we're here, make remap_pfn_range_prepare_vma() a little neater, and
pass mmap_action directly to call_action_complete().

Then, update compat_vma_mmap() to perform its logic directly, as
__compat_vma_map() is not used by anything so we don't need to export it.

Also update compat_vma_mmap() to use vfs_mmap_prepare() rather than
calling the mmap_prepare op directly.

Finally, update the VMA userland tests to reflect the changes.

Link: https://lkml.kernel.org/r/cover.1774045440.git.ljs@kernel.org
Link: https://lkml.kernel.org/r/99f408e4694f44ab12bdc55fe0bd9685d3bd1117.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: f96e1d5f15b7 ("mm: avoid deadlock when holding rmap on mmap_prepare error")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 6af36aeb147a06dea47c49859cd6ca5659aeb987 upstream.

Stacked filesystems such as overlayfs do not currently provide the
necessary mechanisms for LSMs to properly enforce access controls on the
mmap() and mprotect() operations.  In order to resolve this gap, a LSM
security blob is being added to the backing_file struct and the following
new LSM hooks are being created:

 security_backing_file_alloc()
 security_backing_file_free()
 security_mmap_backing_file()

The first two hooks are to manage the lifecycle of the LSM security blob
in the backing_file struct, while the third provides a new mmap() access
control point for the underlying backing file.  It is also expected that
LSMs will likely want to update their security_file_mprotect() callback
to address issues with their mprotect() controls, but that does not
require a change to the security_file_mprotect() LSM hook.

There are a three other small changes to support these new LSM hooks:
* Pass the user file associated with a backing file down to
alloc_empty_backing_file() so it can be included in the
security_backing_file_alloc() hook.
* Add getter and setter functions for the backing_file struct LSM blob
as the backing_file struct remains private to fs/file_table.c.
* Constify the file struct field in the LSM common_audit_data struct to
better support LSMs that need to pass a const file struct pointer into
the common LSM audit code.

Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL()
and supplying a fixup.

Cc: stable@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-unionfs@vger.kernel.org
Cc: linux-erofs@lists.ozlabs.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull sysctl updates from Joel Granados:

 - Remove macros from proc handler converters

   Replace the proc converter macros with "regular" functions. Though it
   is more verbose than the macro version, it helps when debugging and
   better aligns with coding-style.rst.

 - General cleanup

   Remove superfluous ctl_table forward declarations. Const qualify the
   memory_allocation_profiling_sysctl and loadpin_sysctl_table arrays.
   Add missing kernel doc to proc_dointvec_conv.

 - Testing

   This series was run through sysctl selftests/kunit test suite in
   x86_64. And went into linux-next after rc4, giving it a good 3 weeks
   of testing

* tag 'sysctl-7.00-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
  sysctl: replace SYSCTL_INT_CONV_CUSTOM macro with functions
  sysctl: Replace unidirectional INT converter macros with functions
  sysctl: Add kernel doc to proc_douintvec_conv
  sysctl: Replace UINT converter macros with functions
  sysctl: Add CONFIG_PROC_SYSCTL guards for converter macros
  sysctl: clarify proc_douintvec_minmax doc
  sysctl: Return -ENOSYS from proc_douintvec_conv when CONFIG_PROC_SYSCTL=n
  sysctl: Remove unused ctl_table forward declarations
  loadpin: Implement custom proc_handler for enforce
  alloc_tag: move memory_allocation_profiling_sysctls into .rodata
  sysctl: Add missing kernel-doc for proc_dointvec_conv

Pull more misc vfs updates from Christian Brauner:
 "Features:

   - Optimize close_range() from O(range size) to O(active FDs) by using
     find_next_bit() on the open_fds bitmap instead of linearly scanning
     the entire requested range. This is a significant improvement for
     large-range close operations on sparse file descriptor tables.

   - Add FS_XFLAG_VERITY file attribute for fs-verity files, retrievable
     via FS_IOC_FSGETXATTR and file_getattr(). The flag is read-only.
     Add tracepoints for fs-verity enable and verify operations,
     replacing the previously removed debug printk's.

   - Prevent nfsd from exporting special kernel filesystems like pidfs
     and nsfs. These filesystems have custom ->open() and ->permission()
     export methods that are designed for open_by_handle_at(2) only and
     are incompatible with nfsd. Update the exportfs documentation
     accordingly.

  Fixes:

   - Fix KMSAN uninit-value in ovl_fill_real() where strcmp() was used
     on a non-null-terminated decrypted directory entry name from
     fscrypt. This triggered on encrypted lower layers when the
     decrypted name buffer contained uninitialized tail data.

     The fix also adds VFS-level name_is_dot(), name_is_dotdot(), and
     name_is_dot_dotdot() helpers, replacing various open-coded "." and
     ".." checks across the tree.

   - Fix read-only fsflags not being reset together with xflags in
     vfs_fileattr_set(). Currently harmless since no read-only xflags
     overlap with flags, but this would cause inconsistencies for any
     future shared read-only flag

   - Return -EREMOTE instead of -ESRCH from PIDFD_GET_INFO when the
     target process is in a different pid namespace. This lets userspace
     distinguish "process exited" from "process in another namespace",
     matching glibc's pidfd_getpid() behavior

  Cleanups:

   - Use C-string literals in the Rust seq_file bindings, replacing the
     kernel::c_str!() macro (available since Rust 1.77)

   - Fix typo in d_walk_ret enum comment, add porting notes for the
     readlink_copy() calling convention change"

* tag 'vfs-7.0-rc1.misc.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs: add porting notes about readlink_copy()
  pidfs: return -EREMOTE when PIDFD_GET_INFO is called on another ns
  nfsd: do not allow exporting of special kernel filesystems
  exportfs: clarify the documentation of open()/permission() expotrfs ops
  fsverity: add tracepoints
  fs: add FS_XFLAG_VERITY for fs-verity files
  rust: seq_file: replace `kernel::c_str!` with C-Strings
  fs: dcache: fix typo in enum d_walk_ret comment
  ovl: use name_is_dot* helpers in readdir code
  fs: add helpers name_is_dot{,dot,_dotdot}
  ovl: Fix uninit-value in ovl_fill_real
  fs: reset read-only fsflags together with xflags
  fs/file: optimize close_range() complexity from O(N) to O(Sparse)

Pull vfs 'struct filename' updates from Al Viro:
 "[Mostly] sanitize struct filename handling"

* tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (68 commits)
  sysfs(2): fs_index() argument is _not_ a pathname
  alpha: switch osf_mount() to strndup_user()
  ksmbd: use CLASS(filename_kernel)
  mqueue: switch to CLASS(filename)
  user_statfs(): switch to CLASS(filename)
  statx: switch to CLASS(filename_maybe_null)
  quotactl_block(): switch to CLASS(filename)
  chroot(2): switch to CLASS(filename)
  move_mount(2): switch to CLASS(filename_maybe_null)
  namei.c: switch user pathname imports to CLASS(filename{,_flags})
  namei.c: convert getname_kernel() callers to CLASS(filename_kernel)
  do_f{chmod,chown,access}at(): use CLASS(filename_uflags)
  do_readlinkat(): switch to CLASS(filename_flags)
  do_sys_truncate(): switch to CLASS(filename)
  do_utimes_path(): switch to CLASS(filename_uflags)
  chdir(2): unspaghettify a bit...
  do_fchownat(): unspaghettify a bit...
  fspick(2): use CLASS(filename_flags)
  name_to_handle_at(): use CLASS(filename_uflags)
  vfs_open_tree(): use CLASS(filename_uflags)
  ...

Pull misc vfs updates from Christian Brauner:
 "This contains a mix of VFS cleanups, performance improvements, API
  fixes, documentation, and a deprecation notice.

  Scalability and performance:

   - Rework pid allocation to only take pidmap_lock once instead of
     twice during alloc_pid(), improving thread creation/teardown
     throughput by 10-16% depending on false-sharing luck. Pad the
     namespace refcount to reduce false-sharing

   - Track file lock presence via a flag in ->i_opflags instead of
     reading ->i_flctx, avoiding false-sharing with ->i_readcount on
     open/close hot paths. Measured 4-16% improvement on 24-core
     open-in-a-loop benchmarks

   - Use a consume fence in locks_inode_context() to match the
     store-release/load-consume idiom, eliminating a hardware fence on
     some architectures

   - Annotate cdev_lock with __cacheline_aligned_in_smp to prevent
     false-sharing

   - Remove a redundant DCACHE_MANAGED_DENTRY check in
     __follow_mount_rcu() that never fires since the caller already
     verifies it, eliminating a 100% mispredicted branch

   - Fix a 100% mispredicted likely() in devcgroup_inode_permission()
     that became wrong after a prior code reorder

  Bug fixes and correctness:

   - Make insert_inode_locked() wait for inode destruction instead of
     skipping, fixing a corner case where two matching inodes could
     exist in the hash

   - Move f_mode initialization before file_ref_init() in alloc_file()
     to respect the SLAB_TYPESAFE_BY_RCU ordering contract

   - Add a WARN_ON_ONCE guard in try_to_free_buffers() for folios with
     no buffers attached, preventing a null pointer dereference when
     AS_RELEASE_ALWAYS is set but no release_folio op exists

   - Fix select restart_block to store end_time as timespec64, avoiding
     truncation of tv_sec on 32-bit architectures

   - Make dump_inode() use get_kernel_nofault() to safely access inode
     and superblock fields, matching the dump_mapping() pattern

  API modernization:

   - Make posix_acl_to_xattr() allocate the buffer internally since
     every single caller was doing it anyway. Reduces boilerplate and
     unnecessary error checking across ~15 filesystems

   - Replace deprecated simple_strtoul() with kstrtoul() for the
     ihash_entries, dhash_entries, mhash_entries, and mphash_entries
     boot parameters, adding proper error handling

   - Convert chardev code to use guard(mutex) and __free(kfree) cleanup
     patterns

   - Replace min_t() with min() or umin() in VFS code to avoid silently
     truncating unsigned long to unsigned int

   - Gate LOOKUP_RCU assertions behind CONFIG_DEBUG_VFS since callers
     already check the flag

  Deprecation:

   - Begin deprecating legacy BSD process accounting (acct(2)). The
     interface has numerous footguns and better alternatives exist
     (eBPF)

  Documentation:

   - Fix and complete kernel-doc for struct export_operations, removing
     duplicated documentation between ReST and source

   - Fix kernel-doc warnings for __start_dirop() and ilookup5_nowait()

  Testing:

   - Add a kunit test for initramfs cpio handling of entries with
     filesize > PATH_MAX

  Misc:

   - Add missing <linux/init_task.h> include in fs_struct.c"

* tag 'vfs-7.0-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (28 commits)
  posix_acl: make posix_acl_to_xattr() alloc the buffer
  fs: make insert_inode_locked() wait for inode destruction
  initramfs_test: kunit test for cpio.filesize > PATH_MAX
  fs: improve dump_inode() to safely access inode fields
  fs: add <linux/init_task.h> for 'init_fs'
  docs: exportfs: Use source code struct documentation
  fs: move initializing f_mode before file_ref_init()
  exportfs: Complete kernel-doc for struct export_operations
  exportfs: Mark struct export_operations functions at kernel-doc
  exportfs: Fix kernel-doc output for get_name()
  acct(2): begin the deprecation of legacy BSD process accounting
  device_cgroup: remove branch hint after code refactor
  VFS: fix __start_dirop() kernel-doc warnings
  fs: Describe @isnew parameter in ilookup5_nowait()
  fs/namei: Remove redundant DCACHE_MANAGED_DENTRY check in __follow_mount_rcu
  fs: only assert on LOOKUP_RCU when built with CONFIG_DEBUG_VFS
  select: store end_time as timespec64 in restart block
  chardev: Switch to guard(mutex) and __free(kfree)
  namespace: Replace simple_strtoul with kstrtoul to parse boot params
  dcache: Replace simple_strtoul with kstrtoul in set_dhash_entries
  ...

Pull vfs mount updates from Christian Brauner:

 - statmount: accept fd as a parameter

   Extend struct mnt_id_req with a file descriptor field and a new
   STATMOUNT_BY_FD flag. When set, statmount() returns mount information
   for the mount the fd resides on — including detached mounts
   (unmounted via umount2(MNT_DETACH)).

   For detached mounts the STATMOUNT_MNT_POINT and STATMOUNT_MNT_NS_ID
   mask bits are cleared since neither is meaningful. The capability
   check is skipped for STATMOUNT_BY_FD since holding an fd already
   implies prior access to the mount and equivalent information is
   available through fstatfs() and /proc/pid/mountinfo without
   privilege. Includes comprehensive selftests covering both attached
   and detached mount cases.

 - fs: Remove internal old mount API code (1 patch)

   Now that every in-tree filesystem has been converted to the new
   mount API, remove all the legacy shim code in fs_context.c that
   handled unconverted filesystems. This deletes ~280 lines including
   legacy_init_fs_context(), the legacy_fs_context struct, and
   associated wrappers. The mount(2) syscall path for userspace remains
   untouched. Documentation references to the legacy callbacks are
   cleaned up.

 - mount: add OPEN_TREE_NAMESPACE to open_tree()

   Container runtimes currently use CLONE_NEWNS to copy the caller's
   entire mount namespace — only to then pivot_root() and recursively
   unmount everything they just copied. With large mount tables and
   thousands of parallel container launches this creates significant
   contention on the namespace semaphore.

   OPEN_TREE_NAMESPACE copies only the specified mount tree (like
   OPEN_TREE_CLONE) but returns a mount namespace fd instead of a
   detached mount fd. The new namespace contains the copied tree mounted
   on top of a clone of the real rootfs.

   This functions as a combined unshare(CLONE_NEWNS) + pivot_root() in a
   single syscall. Works with user namespaces: an unshare(CLONE_NEWUSER)
   followed by OPEN_TREE_NAMESPACE creates a mount namespace owned by
   the new user namespace. Mount namespace file mounts are excluded from
   the copy to prevent cycles. Includes ~1000 lines of selftests"

* tag 'vfs-7.0-rc1.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  selftests/open_tree: add OPEN_TREE_NAMESPACE tests
  mount: add OPEN_TREE_NAMESPACE
  fs: Remove internal old mount API code
  selftests: statmount: tests for STATMOUNT_BY_FD
  statmount: accept fd as a parameter
  statmount: permission check should return EPERM

Pull vfs atomic_open updates from Christian Brauner:
 "Allow knfsd to use atomic_open()

  While knfsd offers combined exclusive create and open results to
  clients, on some filesystems those results are not atomic. The
  separate vfs_create() + vfs_open() sequence in dentry_create() can
  produce races and unexpected errors. For example, open O_CREAT with
  mode 0 will succeed in creating the file but return -EACCES from
  vfs_open(). Additionally, network filesystems benefit from reducing
  remote round-trip operations by using a single atomic_open() call.

  Teach dentry_create() -- whose sole caller is knfsd -- to use
  atomic_open() for filesystems that support it"

* tag 'vfs-7.0-rc1.atomic_open' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs/namei: fix kernel-doc markup for dentry_create
  VFS/knfsd: Teach dentry_create() to use atomic_open()
  VFS: Prepare atomic_open() for dentry_create()
  VFS: move dentry_create() from fs/open.c to fs/namei.c

Pull vfs updates for btrfs from Christian Brauner:
 "This contains some changes for btrfs that are taken to the vfs tree to
  stop duplicating VFS code for subvolume/snapshot dentry

  Btrfs has carried private copies of the VFS may_delete() and
  may_create() functions in fs/btrfs/ioctl.c for permission checks
  during subvolume creation and snapshot destruction. These copies have
  drifted out of sync with the VFS originals — btrfs_may_delete() is
  missing the uid/gid validity check and btrfs_may_create() is missing
  the audit_inode_child() call.

  Export the VFS functions as may_{create,delete}_dentry() and switch
  btrfs to use them, removing ~70 lines of duplicated code"

* tag 'vfs-7.0-rc1.btrfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  btrfs: use may_create_dentry() in btrfs_mksubvol()
  btrfs: use may_delete_dentry() in btrfs_ioctl_snap_destroy()
  fs: export may_create() as may_create_dentry()
  fs: export may_delete() as may_delete_dentry()

Pull vfs lease updates from Christian Brauner:
 "This contains updates for lease support to require filesystems to
  explicitly opt-in to lease support

  Currently kernel_setlease() falls through to generic_setlease() when a
  a filesystem does not define ->setlease(), silently granting lease
  support to every filesystem regardless of whether it is prepared for
  it.

  This is a poor default: most filesystems never intended to support
  leases, and the silent fallthrough makes it impossible to distinguish
  "supports leases" from "never thought about it".

  This inverts the default. It adds explicit

	.setlease = generic_setlease;

  assignments to every in-tree filesystem that should retain lease
  support, then changes kernel_setlease() to return -EINVAL when
  ->setlease is NULL.

  With the new default in place, simple_nosetlease() is redundant and
  is removed along with all references to it"

* tag 'vfs-7.0-rc1.leases' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (25 commits)
  fuse: add setlease file operation
  fs: remove simple_nosetlease()
  filelock: default to returning -EINVAL when ->setlease operation is NULL
  xfs: add setlease file operation
  ufs: add setlease file operation
  udf: add setlease file operation
  tmpfs: add setlease file operation
  squashfs: add setlease file operation
  overlayfs: add setlease file operation
  orangefs: add setlease file operation
  ocfs2: add setlease file operation
  ntfs3: add setlease file operation
  nilfs2: add setlease file operation
  jfs: add setlease file operation
  jffs2: add setlease file operation
  gfs2: add a setlease file operation
  fat: add setlease file operation
  f2fs: add setlease file operation
  exfat: add setlease file operation
  ext4: add setlease file operation
  ...