linux.git/fs/fhandle.c, branch v6.7

exportfs: add helpers to check if filesystem can encode/decode file handles

2023-10-24T15:57:45+00:00

The logic of whether filesystem can encode/decode file handles is open
coded in many places.

In preparation to changing the logic, move the open coded logic into
inline helpers.

Reviewed-by: Jan Kara 
Reviewed-by: Jeff Layton 
Signed-off-by: Amir Goldstein 
Link: https://lore.kernel.org/r/20231023180801.2953446-2-amir73il@gmail.com
Signed-off-by: Christian Brauner

fsnotify: move fsnotify_open() hook into do_dentry_open()

2023-06-12T08:43:45+00:00

fsnotify_open() hook is called only from high level system calls
context and not called for the very many helpers to open files.

This may makes sense for many of the special file open cases, but it is
inconsistent with fsnotify_close() hook that is called for every last
fput() of on a file object with FMODE_OPENED.

As a result, it is possible to observe ACCESS, MODIFY and CLOSE events
without ever observing an OPEN event.

Fix this inconsistency by replacing all the fsnotify_open() hooks with
a single hook inside do_dentry_open().

If there are special cases that would like to opt-out of the possible
overhead of fsnotify() call in fsnotify_open(), they would probably also
want to avoid the overhead of fsnotify() call in the rest of the fsnotify
hooks, so they should be opening that file with the __FMODE_NONOTIFY flag.

However, in the majority of those cases, the s_fsnotify_connectors
optimization in fsnotify_parent() would be sufficient to avoid the
overhead of fsnotify() call anyway.

Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Message-Id: <20230611122429.1499617-1-amir73il@gmail.com>

exportfs: check for error return value from exportfs_encode_*()

2023-05-25T11:17:04+00:00

The exportfs_encode_*() helpers call the filesystem ->encode_fh()
method which returns a signed int.

All the in-tree implementations of ->encode_fh() return a positive
integer and FILEID_INVALID (255) for error.

Fortify the callers for possible future ->encode_fh() implementation
that will return a negative error value.

name_to_handle_at() would propagate the returned error to the users
if filesystem ->encode_fh() method returns an error.

Reported-by: Dan Carpenter 
Link: https://lore.kernel.org/linux-fsdevel/ca02955f-1877-4fde-b453-3c1d22794740@kili.mountain/
Signed-off-by: Amir Goldstein 
Reviewed-by: Jeff Layton 
Signed-off-by: Jan Kara 
Message-Id: <20230524154825.881414-1-amir73il@gmail.com>

exportfs: allow exporting non-decodeable file handles to userspace

2023-05-25T11:16:57+00:00

Some userspace programs use st_ino as a unique object identifier, even
though inode numbers may be recycable.

This issue has been addressed for NFS export long ago using the exportfs
file handle API and the unique file handle identifiers are also exported
to userspace via name_to_handle_at(2).

fanotify also uses file handles to identify objects in events, but only
for filesystems that support NFS export.

Relax the requirement for NFS export support and allow more filesystems
to export a unique object identifier via name_to_handle_at(2) with the
flag AT_HANDLE_FID.

A file handle requested with the AT_HANDLE_FID flag, may or may not be
usable as an argument to open_by_handle_at(2).

To allow filesystems to opt-in to supporting AT_HANDLE_FID, a struct
export_operations is required, but even an empty struct is sufficient
for encoding FIDs.

Acked-by: Jeff Layton 
Acked-by: Chuck Lever 
Signed-off-by: Amir Goldstein 
Acked-by: Christian Brauner 
Signed-off-by: Jan Kara 
Message-Id: <20230502124817.3070545-4-amir73il@gmail.com>

do_sys_name_to_handle(): constify path

2022-09-01T21:36:39+00:00

Reviewed-by: Christian Brauner (Microsoft) 
Signed-off-by: Al Viro

switch file_open_root() to struct path

2021-04-07T17:56:43+00:00

... and provide file_open_root_mnt(), using the root of given mount.

Signed-off-by: Al Viro

fs: delete repeated words in comments

2021-02-24T21:38:26+00:00

Delete duplicate words in fs/*.c.
The doubled words that are being dropped are:
  that, be, the, in, and, for

Link: https://lkml.kernel.org/r/20201224052810.25315-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap 
Reviewed-by: Matthew Wilcox (Oracle) 
Cc: Alexander Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/handle.c - fix up kerneldoc

2019-08-08T01:51:47+00:00

When building with W=1, we get some kerneldoc warnings:

  CC      fs/fhandle.o
fs/fhandle.c:259: warning: Function parameter or member 'flags' not described in 'sys_open_by_handle_at'
fs/fhandle.c:259: warning: Excess function parameter 'flag' description in 'sys_open_by_handle_at'

Fix the typo that caused it.

Signed-off-by: Valdis Kletnieks 
Signed-off-by: Al Viro

vfs: Copy struct mount.mnt_id to userspace using put_user()

2018-01-15T20:07:51+00:00

The mnt_id field can be copied with put_user(), so there is no need to
use copy_to_user(). In both cases, hardened usercopy is being bypassed
since the size is constant, and not open to runtime manipulation.

This patch is verbatim from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Signed-off-by: David Windsor 
[kees: adjust commit log]
Cc: Alexander Viro 
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Kees Cook

Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2017-11-17T20:54:01+00:00

Pull misc vfs updates from Al Viro:
 "Assorted stuff, really no common topic here"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  vfs: grab the lock instead of blocking in __fd_install during resizing
  vfs: stop clearing close on exec when closing a fd
  include/linux/fs.h: fix comment about struct address_space
  fs: make fiemap work from compat_ioctl
  coda: fix 'kernel memory exposure attempt' in fsync
  pstore: remove unneeded unlikely()
  vfs: remove unneeded unlikely()
  stubs for mount_bdev() and kill_block_super() in !CONFIG_BLOCK case
  make vfs_ustat() static
  do_handle_open() should be static
  elf_fdpic: fix unused variable warning
  fold destroy_super() into __put_super()
  new helper: destroy_unused_super()
  fix address space warnings in ipc/
  acct.h: get rid of detritus