linux/fs
Mattias Nissler dab741e0e0 Add a "nosymfollow" mount option.
For mounts that have the new "nosymfollow" option, don't follow symlinks
when resolving paths. The new option is similar in spirit to the
existing "nodev", "noexec", and "nosuid" options, as well as to the
LOOKUP_NO_SYMLINKS resolve flag in the openat2(2) syscall. Various BSD
variants have been supporting the "nosymfollow" mount option for a long
time with equivalent implementations.

Note that symlinks may still be created on file systems mounted with
the "nosymfollow" option present. readlink() remains functional, so
user space code that is aware of symlinks can still choose to follow
them explicitly.

Setting the "nosymfollow" mount option helps prevent privileged
writers from modifying files unintentionally in case there is an
unexpected link along the accessed path. The "nosymfollow" option is
thus useful as a defensive measure for systems that need to deal with
untrusted file systems in privileged contexts.

More information on the history and motivation for this patch can be
found here:

https://sites.google.com/a/chromium.org/dev/chromium-os/chromiumos-design-docs/hardening-against-malicious-stateful-data#TOC-Restricting-symlink-traversal

Signed-off-by: Mattias Nissler <mnissler@chromium.org>
Signed-off-by: Ross Zwisler <zwisler@google.com>
Reviewed-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-08-27 16:06:47 -04:00
..
9p 9p: Remove unneeded cast from memory allocation 2020-07-31 07:28:25 +02:00
adfs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
affs block: move block-related definitions out of fs.h 2020-06-24 09:16:02 -06:00
afs Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
autofs fs: autofs: delete repeated words in comments 2020-08-14 19:56:56 -07:00
befs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
bfs docs: filesystems: fix renamed references 2020-04-20 15:45:22 -06:00
btrfs for-5.9-tag 2020-08-13 12:26:18 -07:00
cachefiles cachefiles: switch to kernel_write 2020-07-08 08:27:56 +02:00
ceph ceph: handle zero-length feature mask in session messages 2020-08-05 17:47:07 +02:00
cifs 3 small cifs/smb3 fixes, one for stable fixing mkdir path with idsfromsid mount option 2020-08-15 08:31:39 -07:00
coda docs: filesystems: convert coda.txt to ReST 2020-05-05 09:22:21 -06:00
configfs A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
cramfs docs: filesystems: fix renamed references 2020-04-20 15:45:22 -06:00
crypto mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
debugfs Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-08-05 20:13:21 -07:00
devpts
dlm dlm for 5.9 2020-08-06 19:44:25 -07:00
ecryptfs mm, treewide: rename kzfree() to kfree_sensitive() 2020-08-07 11:33:22 -07:00
efivarfs efi/efivars: Expose RT service availability via efivars abstraction 2020-07-09 10:14:29 +03:00
efs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
erofs Changes since last update: 2020-08-06 19:22:51 -07:00
exfat exfat: retain 'VolumeFlags' properly 2020-08-12 08:31:13 +09:00
exportfs
ext2 ext2: ext2.h: fix duplicated word + typos 2020-07-27 10:58:06 +02:00
ext4 New code for 5.9: 2020-08-06 19:35:12 -07:00
f2fs f2fs-for-5.9-rc1 2020-08-10 18:33:22 -07:00
fat fat: fix fat_ra_init() for data clusters == 0 2020-08-12 10:58:01 -07:00
freevxfs
fscache Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 2020-06-03 16:27:18 -07:00
fuse virtio: fixes, features 2020-08-11 14:34:17 -07:00
gfs2 Changes in gfs2: 2020-08-10 18:22:43 -07:00
hfs block: move block-related definitions out of fs.h 2020-06-24 09:16:02 -06:00
hfsplus treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
hostfs hostfs: Use kasprintf() instead of fixed buffer formatting 2020-03-29 23:23:00 +02:00
hpfs hpfs: fix warning due to superfluous semicolon 2020-06-06 10:08:17 -07:00
hugetlbfs hugetlbfs: prevent filesystem stacking of hugetlbfs 2020-08-12 10:57:56 -07:00
iomap iomap: fall back to buffered writes for invalidation failures 2020-08-05 09:24:16 -07:00
isofs Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
jbd2 This is the second round of ext4 commits for 5.8 merge window. It 2020-06-15 09:32:10 -07:00
jffs2 This pull request contains changes for JFFS2, UBI and UBIFS 2020-08-10 18:20:04 -07:00
jfs block: move struct block_device to blk_types.h 2020-06-24 09:16:02 -06:00
kernfs fsnotify: pass dir and inode arguments to fsnotify() 2020-07-27 23:15:48 +02:00
lockd proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
minix fs/minix: remove expected error message in block_to_path() 2020-08-12 10:58:00 -07:00
nfs NFS client updates for Linux 5.9 2020-08-15 08:26:55 -07:00
nfs_common
nfsd Highlights: 2020-08-09 13:58:04 -07:00
nilfs2 nilfs2: use a more common logging style 2020-08-12 10:58:01 -07:00
nls treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
notify fanotify: compare fsid when merging name event 2020-07-28 10:58:07 +02:00
ntfs ntfs: fix ntfs_test_inode and ntfs_init_locked_inode function type 2020-08-07 11:33:21 -07:00
ocfs2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 21:14:30 -07:00
omfs treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
openpromfs
orangefs orangefs: remove unnecessary assignment to variable ret 2020-08-04 15:01:58 -04:00
overlayfs Remove uninitialized_var() macro for v5.9-rc1 2020-08-04 13:49:43 -07:00
proc mm, oom: make the calculation of oom badness more accurate 2020-08-12 10:57:56 -07:00
pstore pstore: Fix linking when crypto API disabled 2020-07-06 19:42:31 -07:00
qnx4
qnx6 fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
quota \n 2020-08-06 19:28:26 -07:00
ramfs fs_parse: fold fs_parameter_desc/fs_parameter_spec 2020-02-07 14:48:37 -05:00
reiserfs \n 2020-08-06 19:28:26 -07:00
romfs treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
squashfs squashfs: fix length field overlap check in metadata reading 2020-07-24 12:42:41 -07:00
sysfs RDMA 5.8 merge window pull request 2020-06-05 14:05:57 -07:00
sysv docs: filesystems: fix renamed references 2020-04-20 15:45:22 -06:00
tracefs
ubifs This pull request contains changes for JFFS2, UBI and UBIFS 2020-08-10 18:20:04 -07:00
udf \n 2020-08-06 19:28:26 -07:00
ufs fs/ufs: avoid potential u32 multiplication overflow 2020-08-12 10:58:01 -07:00
unicode .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
vboxsf vboxsf: don't use the source name in the bdi name 2020-05-07 08:45:47 -06:00
verity fs-verity: use smp_load_acquire() for ->i_verity_info 2020-07-21 16:02:41 -07:00
xfs Fixes for 5.9-rc1: 2020-08-13 12:22:19 -07:00
zonefs zonefs: add zone-capacity support 2020-08-11 17:42:24 +09:00
aio.c mm: remove unnecessary wrapper function do_mmap_pgoff() 2020-08-07 11:33:27 -07:00
anon_inodes.c
attr.c
bad_inode.c fs: move the fiemap definitions out of fs.h 2020-06-03 23:16:55 -04:00
binfmt_aout.c exec: Rename flush_old_exec begin_new_exec 2020-05-07 16:55:47 -05:00
binfmt_elf_fdpic.c Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
binfmt_elf.c kill elf_fpxregs_t 2020-07-27 14:29:23 -04:00
binfmt_em86.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_flat.c Merge branch 'uaccess.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-06-10 16:02:54 -07:00
binfmt_misc.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
binfmt_script.c Merge branch 'akpm' (patches from Andrew) 2020-06-04 19:18:29 -07:00
block_dev.c for-5.9/io_uring-20200802 2020-08-03 13:01:22 -07:00
buffer.c for-5.9/block-20200802 2020-08-03 11:57:03 -07:00
char_dev.c vfs: allow unprivileged whiteout creation 2020-05-14 16:44:23 +02:00
compat_binfmt_elf.c Split the old READ_IMPLIES_EXEC workaround from executable PT_GNU_STACK 2020-06-05 13:45:21 -07:00
compat.c
coredump.c coredump: add %f for executable filename 2020-08-12 10:58:01 -07:00
d_path.c
dax.c dax: Fix incorrect argument passed to xas_set_err() 2020-07-30 18:14:33 -06:00
dcache.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
dcookies.c
direct-io.c block: remove the bd_queue field from struct block_device 2020-07-01 08:08:20 -06:00
drop_caches.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
eventfd.c eventfd: convert to f_op->read_iter() 2020-05-06 22:33:43 -04:00
eventpoll.c epoll: call final ep_events_available() check under the lock 2020-05-14 10:00:35 -07:00
exec.c mm/gup: remove task_struct pointer for all gup code 2020-08-12 10:58:04 -07:00
fcntl.c fcntl: Distribute switch variables for initialization 2020-03-03 10:55:06 -05:00
fhandle.c
file_table.c Revert "fs: Do not check if there is a fsnotify watcher on pseudo inodes" 2020-06-29 09:40:55 -07:00
file.c Merge branch 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 09:40:34 -07:00
filesystems.c fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() 2020-04-10 15:36:22 -07:00
fs_context.c vfs: don't parse "silent" option 2020-05-14 16:44:25 +02:00
fs_parser.c fs_parse: remove pr_notice() about each validation 2020-04-02 09:35:26 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fs-writeback.c A lot of bug fixes and cleanups for ext4, including: 2020-06-05 16:19:28 -07:00
fsopen.c add prefix to fs_context->log 2020-02-07 14:48:35 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c AFS Changes 2020-06-05 16:26:36 -07:00
internal.h Merge branch 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 09:40:34 -07:00
io_uring.c io_uring: short circuit -EAGAIN for blocking read attempt 2020-08-15 15:58:42 -07:00
io-wq.c io-wq: update hash bits 2020-07-25 09:47:44 -06:00
io-wq.h io_uring/io-wq: move RLIMIT_FSIZE to io-wq 2020-07-24 13:00:44 -06:00
ioctl.c fs: remove ksys_ioctl 2020-07-31 08:16:01 +02:00
Kconfig tmpfs: support 64-bit inums per-sb 2020-08-07 11:33:24 -07:00
Kconfig.binfmt treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
libfs.c block: remove the error_sector argument to blkdev_issue_flush 2020-05-22 08:45:46 -06:00
locks.c Highlights: 2020-08-09 13:58:04 -07:00
Makefile init: add an init_mount helper 2020-07-31 08:17:51 +02:00
mbcache.c
mount.h proc/mounts: add cursor 2020-05-14 16:44:24 +02:00
mpage.c fs: convert mpage_readpages to mpage_readahead 2020-06-02 10:59:07 -07:00
namei.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
namespace.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
no-block.c
nsfs.c nsproxy: attach to namespaces via pidfds 2020-05-13 11:41:22 +02:00
open.c exec: move S_ISREG() check earlier 2020-08-12 10:58:01 -07:00
pipe.c Notifications over pipes + Keyring notifications 2020-06-13 09:56:21 -07:00
pnode.c propagate_one(): mnt_set_mountpoint() needs mount_lock 2020-04-27 10:37:14 -04:00
pnode.h
posix_acl.c vfs: clean up posix_acl_permission() logic aroudn MAY_NOT_BLOCK 2020-06-08 11:04:19 -07:00
proc_namespace.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
read_write.c initrd: switch initrd loading to struct file based APIs 2020-07-30 08:22:47 +02:00
readdir.c fs: remove ksys_getdents64 2020-07-31 08:16:00 +02:00
select.c pselect6() and friends: take handling the combined 6th/7th args into helper 2020-05-29 19:10:42 -04:00
seq_file.c fs/seq_file.c: seq_read: Update pr_info_ratelimited 2020-06-04 19:06:25 -07:00
signalfd.c fs/signalfd.c: fix inconsistent return codes for signalfd4 2020-08-12 10:58:01 -07:00
splice.c Notifications over pipes + Keyring notifications 2020-06-13 09:56:21 -07:00
stack.c
stat.c New code for 5.8: 2020-06-02 19:45:12 -07:00
statfs.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
super.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-06-10 16:09:11 -07:00
sync.c overlayfs update for 5.8 2020-06-09 15:40:50 -07:00
timerfd.c
userfaultfd.c A set of locking fixes and updates: 2020-08-10 19:07:44 -07:00
utimes.c fs: expose utimes_common 2020-07-31 08:16:01 +02:00
xattr.c xattr: add a function to check if a namespace is supported 2020-07-13 17:27:03 -04:00