Joel Fernandes (Google)
ab3948f58f
mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd ...
Android uses ashmem for sharing memory regions. We are looking forward
to migrating all usecases of ashmem to memfd so that we can possibly
remove the ashmem driver in the future from staging while also
benefiting from using memfd and contributing to it. Note staging
drivers are also not ABI and generally can be removed at anytime.
One of the main usecases Android has is the ability to create a region
and mmap it as writeable, then add protection against making any
"future" writes while keeping the existing already mmap'ed
writeable-region active. This allows us to implement a usecase where
receivers of the shared memory buffer can get a read-only view, while
the sender continues to write to the buffer. See CursorWindow
documentation in Android for more details:
https://developer.android.com/reference/android/database/CursorWindow
This usecase cannot be implemented with the existing F_SEAL_WRITE seal.
To support the usecase, this patch adds a new F_SEAL_FUTURE_WRITE seal
which prevents any future mmap and write syscalls from succeeding while
keeping the existing mmap active.
A better way to do F_SEAL_FUTURE_WRITE seal was discussed [1] last week
where we don't need to modify core VFS structures to get the same
behavior of the seal. This solves several side-effects pointed by Andy.
self-tests are provided in later patch to verify the expected semantics.
[1] https://lore.kernel.org/lkml/20181111173650.GA256781@google.com/
Thanks a lot to Andy for suggestions to improve code.
Link: http://lkml.kernel.org/r/20190112203816.85534-2-joel@joelfernandes.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Marc-Andr Lureau <marcandre.lureau@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-05 21:07:19 -08:00
Merge branch 'work.afs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2018-11-01 19:58:52 -07:00
afs: Fix manually set volume location server list
2019-02-25 11:59:07 -08:00
autofs: fix error return in autofs_fill_super()
2019-02-01 15:46:24 -08:00
bfs: extra sanity checking and static inode bitmap
2019-01-04 13:13:47 -08:00
for-5.0-rc4-tag
2019-02-03 08:48:33 -08:00
fscache, cachefiles: remove redundant variable 'cache'
2018-11-30 16:00:58 +00:00
ceph: avoid repeatedly adding inode to mdsc->snap_flush_list
2019-02-18 18:08:29 +01:00
cifs: update internal module version number
2019-01-31 07:05:06 -06:00
Make the Cramfs code more robust against filesystem corruptions,
2018-10-30 12:46:25 -07:00
crypto: clarify name of WEAK_KEY request flag
2019-01-25 18:41:52 +08:00
debugfs: debugfs_lookup() should return NULL if not found
2019-01-30 12:39:49 +01:00
socket: Rename SO_RCVTIMEO/ SO_SNDTIMEO with _OLD suffixes
2019-02-03 11:17:31 -08:00
crypto: clarify name of WEAK_KEY request flag
2019-01-25 18:41:52 +08:00
exofs_mount(): fix leaks on failure exits
2018-12-17 18:36:33 -05:00
exportfs: do not read dentry after free
2018-11-23 09:08:17 -05:00
\n
2018-12-27 17:00:35 -08:00
Revert "ext4: use ext4_write_inode() when fsyncing w/o a journal"
2019-01-31 23:41:11 -05:00
f2fs-for-4.21-rc1
2018-12-31 09:41:37 -08:00
Merge branch 'akpm' (patches from Andrew)
2019-01-05 09:16:18 -08:00
fscache: fix race between enablement and dropping of object
2018-11-30 15:57:31 +00:00
fuse: decrement NR_WRITEBACK_TEMP on the right page
2019-01-16 10:27:59 +01:00
Revert "gfs2: read journal in large chunks to locate the head"
2019-02-14 09:52:51 -08:00
hfs: do not free node before using
2018-11-30 14:56:14 -08:00
hfsplus: return file attributes on statx
2019-01-04 13:13:47 -08:00
mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd
2019-03-05 21:07:19 -08:00
jbd2: clean up indentation issue, replace spaces with tab
2018-12-04 00:20:10 -05:00
jffs2: Fix use of uninitialized delayed_work, lockdep breakage
2018-12-02 09:20:34 +01:00
fs: kernfs: add poll file operation
2019-03-05 21:07:17 -08:00
NFS client updates for Linux 4.21
2019-01-02 16:35:23 -08:00
Merge branch 'fixes-v5.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2019-02-20 09:09:33 -08:00
Revert "nfsd4: return default lease period"
2019-02-14 12:33:19 -05:00
nilfs2: Use xa_erase_irq
2018-11-05 14:57:05 -05:00
inotify: Fix fd refcount leak in inotify_add_watch().
2019-01-02 18:28:37 +01:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
ocfs2: Use zero-sized array and struct_size() in kzalloc()
2019-03-05 21:07:13 -08:00
fs/openpromfs: Use of_node_name_eq for node name comparisons
2018-11-18 13:35:19 -08:00
orangefs: remove two un-needed BUG_ONs...
2019-02-20 15:12:52 -05:00
Revert "ovl: relax permission checking on underlying layers"
2018-12-04 11:31:30 +01:00
mm: update ptep_modify_prot_commit to take old pte value as arg
2019-03-05 21:07:18 -08:00
pstore/ram: Avoid allocation and leak of platform data
2019-01-20 14:44:52 -08:00
quota: Lock s_umount in exclusive mode for Q_XQUOTA{ON,OFF} quotactls.
2018-12-18 18:29:15 +01:00
reiserfs: remove workaround code for GCC 3.x
2018-10-31 08:54:14 -07:00
sysfs: convert BUG_ON to WARN_ON
2019-01-07 08:53:32 +01:00
sysv: return 'err' instead of 0 in __sysv_write_inode
2018-11-10 08:02:40 -05:00
mm: migrate: drop unused argument of migrate_page_move_mapping()
2018-12-28 12:11:51 -08:00
\n
2018-12-27 17:00:35 -08:00
xfs: set buffer ops when repair probes for btree type
2019-02-03 14:03:59 -08:00
Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2019-03-04 13:24:27 -08:00
a.out: remove core dumping support
2019-03-05 10:00:35 -08:00
exec: load_script: Do not exec truncated interpreter path
2019-02-18 16:49:36 -08:00
blockdev: Fix livelocks on loop device
2019-01-15 07:30:56 -07:00
fs: ratelimit __find_get_block_slow() failure message.
2019-02-06 12:58:56 -07:00
media updates for v4.20-rc1
2018-10-29 14:29:58 -07:00
dax fix 4.21
2018-12-31 09:46:39 -08:00
fs/dcache: Track & report number of negative dentries
2019-01-30 11:02:11 -08:00
direct-io: allow direct writes to empty inodes
2019-01-22 08:26:44 -07:00
fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
2019-02-01 15:46:24 -08:00
Merge branch 'akpm' (patches from Andrew)
2019-01-05 09:16:18 -08:00
exec: Fix mem leak in kernel_read_file
2019-02-18 21:26:24 -05:00
fs/file.c: initialize init_files.resize_wait
2019-03-05 21:07:14 -08:00
mm: convert totalram_pages and totalhigh_pages variables to atomic
2018-12-28 12:11:47 -08:00
writeback: synchronize sync(2) against cgroup writeback membership switches
2019-01-22 14:39:38 -07:00
fs/inode.c: inode_set_flags(): replace opencoded set_mask_bits()
2019-03-05 21:07:13 -08:00
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
iomap: fix a use after free in iomap_dio_rw
2019-01-27 08:47:42 -08:00
locks: fix error in locks_move_blocks()
2019-01-02 20:14:50 -05:00
Revert "vfs: Allow userns root to call mknod on owned filesystems."
2018-12-22 14:18:34 -08:00
Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2019-03-04 13:24:27 -08:00
memcg: localize memcg_kmem_enabled() check
2019-03-05 21:07:15 -08:00
vfs: Suppress MS_* flag defs within the kernel unless explicitly enabled
2018-12-20 16:32:56 +00:00
get rid of legacy 'get_ds()' function
2019-03-04 10:50:14 -08:00
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
Remove 'type' argument from access_ok() function
2019-01-03 18:57:57 -08:00
fs: Make splice() and tee() take into account O_NONBLOCK flag on pipes
2019-03-04 16:10:17 -08:00
mount_fs: suppress MAC on MS_SUBMOUNT as well as MS_KERNMOUNT
2018-12-21 11:51:23 -05:00
userfaultfd: clear flag if remap event not enabled
2018-12-28 12:11:51 -08:00
ab3948f58f