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e1bbcd277a
linux/fs
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Christian Brauner e1bbcd277a
fs: hold writers when changing mount's idmapping 
Hold writers when changing a mount's idmapping to make it more robust.

The vfs layer takes care to retrieve the idmapping of a mount once
ensuring that the idmapping used for vfs permission checking is
identical to the idmapping passed down to the filesystem.

For ioctl codepaths the filesystem itself is responsible for taking the
idmapping into account if they need to. While all filesystems with
FS_ALLOW_IDMAP raised take the same precautions as the vfs we should
enforce it explicitly by making sure there are no active writers on the
relevant mount while changing the idmapping.

This is similar to turning a mount ro with the difference that in
contrast to turning a mount ro changing the idmapping can only ever be
done once while a mount can transition between ro and rw as much as it
wants.

This is a minor user-visible change. But it is extremely unlikely to
matter. The caller must've created a detached mount via OPEN_TREE_CLONE
and then handed that O_PATH fd to another process or thread which then
must've gotten a writable fd for that mount and started creating files
in there while the caller is still changing mount properties. While not
impossible it will be an extremely rare corner-case and should in
general be considered a bug in the application. Consider making a mount
MOUNT_ATTR_NOEXEC or MOUNT_ATTR_NODEV while allowing someone else to
perform lookups or exec'ing in parallel by handing them a copy of the
OPEN_TREE_CLONE fd or another fd beneath that mount.

Link: https://lore.kernel.org/r/20220510095840.152264-1-brauner@kernel.org
Cc: Seth Forshee <seth.forshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-05-12 10:12:00 +02:00
..
9p Netfs prep for write helpers 2022-03-31 15:49:36 -07:00
adfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
affs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
afs fscache: Remove the cookie parameter from fscache_clear_page_bits() 2022-04-08 23:54:37 +01:00
autofs
befs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
bfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
btrfs for-5.18-rc2-tag 2022-04-14 10:58:27 -07:00
cachefiles cachefiles: Fix KASAN slab-out-of-bounds in cachefiles_set_volume_xattr 2022-04-08 23:32:40 +01:00
ceph Filesystem/VFS changes for 5.18, part two 2022-04-01 13:50:50 -07:00
cifs cifs: destage any unwritten data to the server before calling copychunk_write 2022-04-20 22:54:54 -05:00
coda Folio changes for 5.18 2022-03-22 17:03:12 -07:00
configfs configfs: fix a race in configfs_{,un}register_subsystem() 2022-02-22 18:30:28 +01:00
cramfs
crypto fs: Remove ->readpages address space operation 2022-04-01 13:45:33 -04:00
debugfs debugfs: Document that debugfs_create functions need not be error checked 2022-02-25 11:56:13 +01:00
devpts
dlm
ecryptfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
efivarfs
efs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
erofs erofs: fix use-after-free of on-stack io[] 2022-04-15 23:51:43 +08:00
exfat Description for this pull request: 2022-04-01 14:20:24 -07:00
exportfs
ext2 \n 2022-03-25 17:38:15 -07:00
ext4 Fix some syzbot-detected bugs, as well as other bugs found by I/O 2022-04-22 18:18:27 -07:00
f2fs f2fs: Get the superblock from the mapping instead of the page 2022-04-01 14:40:44 -04:00
fat Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
freevxfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
fscache fscache: remove FSCACHE_OLD_API Kconfig option 2022-04-08 23:54:37 +01:00
fuse fs: Remove ->readpages address space operation 2022-04-01 13:45:33 -04:00
gfs2 gfs2 fixes 2022-03-31 15:57:50 -07:00
hfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
hfsplus Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
hostfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
hpfs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
hugetlbfs mm, hugetlb: allow for "high" userspace addresses 2022-04-21 20:01:09 -07:00
iomap iomap: Simplify is_partially_uptodate a little 2022-04-01 14:40:43 -04:00
isofs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
jbd2 Fix some syzbot-detected bugs, as well as other bugs found by I/O 2022-04-22 18:18:27 -07:00
jffs2 This pull request contains fixes for JFFS2, UBI and UBIFS 2022-03-31 16:09:41 -07:00
jfs A couple bug fixes 2022-03-29 18:17:30 -07:00
kernfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2022-04-01 19:57:03 -07:00
ksmbd ksmbd: set fixed sector size to FS_SECTOR_SIZE_INFORMATION 2022-04-14 20:56:13 -05:00
lockd NFSD: Move svc_serv_ops::svo_function into struct svc_serv 2022-02-28 10:26:40 -05:00
minix Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
netfs netfs: Split some core bits out into their own file 2022-03-18 09:29:05 +00:00
nfs NFS client bugfixes for Linux 5.18 2022-04-08 07:39:17 -10:00
nfs_common
nfsd NFSD bug fixes for 5.18-rc: 2022-04-12 14:23:19 -10:00
nilfs2 nilfs2: get rid of nilfs_mapping_init() 2022-04-01 11:46:09 -07:00
nls
notify fsnotify: remove redundant parameter judgment 2022-03-14 09:05:25 +01:00
ntfs ntfs: Correct mark_ntfs_record_dirty() folio conversion 2022-04-01 14:40:44 -04:00
ntfs3 Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
ocfs2 ocfs2: fix crash when mount with quota enabled 2022-04-01 11:46:09 -07:00
omfs fs: Convert __set_page_dirty_buffers to block_dirty_folio 2022-03-16 13:37:04 -04:00
openpromfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
orangefs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
overlayfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
proc Updates to Tracing: 2022-04-03 12:26:01 -07:00
pstore pstore: Don't use semaphores in always-atomic-context code 2022-03-15 11:08:23 -07:00
qnx4 fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
qnx6 fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
quota quota: make dquot_quota_sync return errors from ->sync_fs 2022-01-30 08:59:47 -08:00
ramfs
reiserfs \n 2022-03-25 17:38:15 -07:00
romfs fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
smbfs_common smb3: fix ksmbd bigendian bug in oplock break, and move its struct to smbfs_common 2022-03-31 09:38:53 -05:00
squashfs Merge branch 'akpm' (patches from Andrew) 2022-03-22 16:11:53 -07:00
sysfs kobject: kobj_type: remove default_attrs 2022-04-05 15:39:19 +02:00
sysv Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
tracefs tracefs: Set the group ownership in apply_options() not parse_options() 2022-02-25 21:05:04 -05:00
ubifs This pull request contains fixes for JFFS2, UBI and UBIFS 2022-03-31 16:09:41 -07:00
udf \n 2022-03-25 17:38:15 -07:00
ufs Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
unicode kbuild: unify cmd_copy and cmd_shipped 2022-02-14 10:37:32 +09:00
vboxsf Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
verity fs: Remove ->readpages address space operation 2022-04-01 13:45:33 -04:00
xfs Bug fixes for 5.18: 2022-04-01 19:30:44 -07:00
zonefs for-5.18/write-streams-2022-03-18 2022-03-26 11:51:46 -07:00
aio.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2022-04-01 19:57:03 -07:00
anon_inodes.c
attr.c
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c coredump: Snapshot the vmas in do_coredump 2022-03-08 12:55:29 -06:00
binfmt_elf_test.c binfmt_elf: Introduce KUnit test 2022-03-03 20:38:56 -08:00
binfmt_elf.c revert "fs/binfmt_elf: use PT_LOAD p_align values for static PIE" 2022-04-15 14:49:56 -07:00
binfmt_flat.c coredump: Don't compile flat_core_dump when coredumps are disabled 2022-03-09 10:37:07 -06:00
binfmt_misc.c Fix regression due to "fs: move binfmt_misc sysctl to its own file" 2022-02-09 09:50:02 -08:00
binfmt_script.c
buffer.c filemap: Remove AOP_FLAG_CONT_EXPAND 2022-04-01 14:40:44 -04:00
char_dev.c
compat_binfmt_elf.c binfmt_elf: Introduce KUnit test 2022-03-03 20:38:56 -08:00
coredump.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
d_path.c
dax.c dax for 5.18 2022-03-24 18:12:09 -07:00
dcache.c mm: dcache: use kmem_cache_alloc_lru() to allocate dentry 2022-03-22 15:57:03 -07:00
direct-io.c block: remove the per-bio/request write hint 2022-03-07 12:45:57 -07:00
drop_caches.c
eventfd.c
eventpoll.c
exec.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
fcntl.c fs: remove fs.f_write_hint 2022-03-08 17:55:03 -07:00
fhandle.c
file_table.c SUNRPC: Ensure we flush any closed sockets before xs_xprt_free() 2022-04-07 16:19:47 -04:00
file.c fs: fix fd table size alignment properly 2022-03-29 23:29:18 -07:00
filesystems.c
fs_context.c
fs_parser.c
fs_pin.c
fs_struct.c
fs_types.c
fs-writeback.c Merge branch 'akpm' (patches from Andrew) 2022-03-22 16:11:53 -07:00
fsopen.c
init.c
inode.c fs: introduce alloc_inode_sb() to allocate filesystems specific inode 2022-03-22 15:57:03 -07:00
internal.h Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2022-04-01 19:57:03 -07:00
io_uring.c io_uring: fix leaks on IOPOLL and CQE_SKIP 2022-04-17 06:54:11 -06:00
io-wq.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
io-wq.h io_uring: stop using io_wq_work as an fd placeholder 2022-04-11 17:06:20 -06:00
ioctl.c Fixes for 5.18-rc1: 2022-04-01 19:35:56 -07:00
Kconfig Folio changes for 5.18 2022-03-22 17:03:12 -07:00
Kconfig.binfmt execve updates for v5.18-rc1 2022-03-21 19:16:02 -07:00
kernel_read_file.c
libfs.c fs: Convert __set_page_dirty_no_writeback to noop_dirty_folio 2022-03-16 13:37:05 -04:00
locks.c
Makefile Fix from Christoph Hellwig merging the CONFIG_UNICODE_UTF8_DATA into the 2022-02-01 11:13:24 -08:00
mbcache.c
mount.h
mpage.c for-5.18/alloc-cleanups-2022-03-25 2022-03-26 11:59:30 -07:00
namei.c VFS: filename_create(): fix incorrect intent. 2022-04-14 15:53:43 -07:00
namespace.c fs: hold writers when changing mount's idmapping 2022-05-12 10:12:00 +02:00
no-block.c
nsfs.c
open.c fs: remove fs.f_write_hint 2022-03-08 17:55:03 -07:00
pipe.c Revert "fs/pipe: use kvcalloc to allocate a pipe_buffer array" 2022-04-20 12:07:53 -07:00
pnode.c
pnode.h
posix_acl.c fs: fix acl translation 2022-04-19 10:19:02 -07:00
proc_namespace.c
read_write.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2022-04-01 19:57:03 -07:00
readdir.c
remap_range.c Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
select.c
seq_file.c seq_file: fix NULL pointer arithmetic warning 2022-02-01 11:31:55 -05:00
signalfd.c
splice.c mm: Convert remove_mapping() to take a folio 2022-03-21 12:59:01 -04:00
stack.c
stat.c stat: fix inconsistency between struct stat and struct compat_stat 2022-04-12 13:35:08 -10:00
statfs.c
super.c vfs: make freeze_super abort when sync_filesystem returns error 2022-01-30 08:59:47 -08:00
sync.c vfs: make sync_filesystem return errors from ->sync_fs 2022-01-30 08:59:47 -08:00
sysctls.c
timerfd.c
userfaultfd.c userfaultfd: provide unmasked address on page-fault 2022-03-22 15:57:08 -07:00
utimes.c
xattr.c fs: fix acl translation 2022-04-19 10:19:02 -07:00