kernel_samsung_a53x/fs
Kees Cook 7697a4c136 exec: Fix ToCToU between perm check and set-uid/gid usage
commit f50733b45d865f91db90919f8311e2127ce5a0cb upstream.

When opening a file for exec via do_filp_open(), permission checking is
done against the file's metadata at that moment, and on success, a file
pointer is passed back. Much later in the execve() code path, the file
metadata (specifically mode, uid, and gid) is used to determine if/how
to set the uid and gid. However, those values may have changed since the
permissions check, meaning the execution may gain unintended privileges.

For example, if a file could change permissions from executable and not
set-id:

---------x 1 root root 16048 Aug  7 13:16 target

to set-id and non-executable:

---S------ 1 root root 16048 Aug  7 13:16 target

it is possible to gain root privileges when execution should have been
disallowed.

While this race condition is rare in real-world scenarios, it has been
observed (and proven exploitable) when package managers are updating
the setuid bits of installed programs. Such files start with being
world-executable but then are adjusted to be group-exec with a set-uid
bit. For example, "chmod o-x,u+s target" makes "target" executable only
by uid "root" and gid "cdrom", while also becoming setuid-root:

-rwxr-xr-x 1 root cdrom 16048 Aug  7 13:16 target

becomes:

-rwsr-xr-- 1 root cdrom 16048 Aug  7 13:16 target

But racing the chmod means users without group "cdrom" membership can
get the permission to execute "target" just before the chmod, and when
the chmod finishes, the exec reaches brpm_fill_uid(), and performs the
setuid to root, violating the expressed authorization of "only cdrom
group members can setuid to root".

Re-check that we still have execute permissions in case the metadata
has changed. It would be better to keep a copy from the perm-check time,
but until we can do that refactoring, the least-bad option is to do a
full inode_permission() call (under inode lock). It is understood that
this is safe against dead-locks, but hardly optimal.

Reported-by: Marco Vanotti <mvanotti@google.com>
Tested-by: Marco Vanotti <mvanotti@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-23 23:20:31 +01:00
..
9p fs/9p: drop inodes immediately on non-.L too 2024-11-19 11:32:45 +01:00
adfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
affs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
afs afs: Don't cross .backup mountpoint from backup volume 2024-11-19 12:27:12 +01:00
autofs Revert "file: Replace ksys_close with close_fd" 2024-11-19 12:59:08 +01:00
befs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
bfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
btrfs btrfs: fix bitmap leak when loading free space cache on duplicate entry 2024-11-23 23:20:23 +01:00
cachefiles Revert "namei: introduce struct renamedata" 2024-11-19 13:45:08 +01:00
ceph ceph: fix incorrect kmalloc size of pagevec mempool 2024-11-23 23:20:18 +01:00
cifs smb: client: fix deadlock in smb2_find_smb_tcon() 2024-11-19 14:19:30 +01:00
coda Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
configfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cramfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crypto Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
debugfs debugfs: fix automount d_fsdata usage 2024-11-18 12:12:12 +01:00
devpts Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dlm Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ecryptfs Revert "namei: introduce struct renamedata" 2024-11-19 13:45:08 +01:00
efivarfs efivarfs: force RO when remounting if SetVariable is not supported 2024-11-18 12:12:25 +01:00
efs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
erofs BACKPORT: erofs: fix lz4 inplace decompression 2024-11-17 17:41:30 +01:00
exfat exfat: support handle zero-size directory 2024-11-18 11:43:14 +01:00
exportfs exportfs: use pr_debug for unreachable debug statements 2024-11-19 12:28:26 +01:00
ext2 ext2: Verify bitmap and itable block numbers before using them 2024-11-23 23:20:12 +01:00
ext4 ext4: fix wrong unit use in ext4_mb_find_by_goal 2024-11-23 23:20:24 +01:00
f2fs f2fs: fix start segno of large section 2024-11-23 23:20:16 +01:00
fat fat: fix uninitialized field in nostale filehandles 2024-11-19 09:22:16 +01:00
freevxfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fscache Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fuse fuse: verify {g,u}id mount options correctly 2024-11-23 23:20:18 +01:00
gfs2 gfs2: Fix "ignore unlock failures after withdraw" 2024-11-19 12:26:54 +01:00
hfs hfs: fix to initialize fields of hfs_inode_info after hfs_alloc_inode() 2024-11-23 23:20:12 +01:00
hfsplus hfsplus: fix to avoid false alarm of circular locking 2024-11-23 23:19:56 +01:00
hostfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
hpfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
hugetlbfs fs,hugetlb: fix NULL pointer dereference in hugetlbs_fill_super 2024-11-18 23:18:30 +01:00
incfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
iomap Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
isofs isofs: handle CDs with bad root inode but good Joliet root directory 2024-11-19 09:23:14 +01:00
jbd2 jbd2: avoid memleak in jbd2_journal_write_metadata_buffer 2024-11-23 23:20:24 +01:00
jffs2 jffs2: Fix potential illegal address access in jffs2_free_inode 2024-11-19 14:19:41 +01:00
jfs jfs: Fix array-index-out-of-bounds in diFree 2024-11-23 23:20:16 +01:00
kernfs fs/kernfs/dir: obey S_ISGID 2024-11-18 12:13:20 +01:00
lockd lockd: drop inappropriate svc_get() from locked_get() 2024-11-19 12:28:32 +01:00
minix Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
nfs nfs: Leave pages in the pagecache if readpage failed 2024-11-19 14:19:35 +01:00
nfs_common NFSD: Add an xdr_stream-based encoder for NFSv2/3 ACLs 2024-11-19 12:27:35 +01:00
nfsd nfsd: hold a lighter-weight client reference over CB_RECALL_ANY 2024-11-19 14:19:31 +01:00
nilfs2 nilfs2: handle inconsistent state in nilfs_btnode_create_block() 2024-11-23 23:20:16 +01:00
nls Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
notify Revert "fs: add file and path permissions helpers" 2024-11-19 13:30:21 +01:00
ntfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ocfs2 ocfs2: add bounds checking to ocfs2_check_dir_entry() 2024-11-19 14:19:51 +01:00
omfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
openpromfs openpromfs: finish conversion to the new mount API 2024-11-19 12:26:52 +01:00
orangefs orangefs: fix out-of-bounds fsid access 2024-11-19 14:19:41 +01:00
overlayfs Revert "namei: introduce struct renamedata" 2024-11-19 13:45:08 +01:00
proc sysctl: always initialize i_uid/i_gid 2024-11-23 23:20:19 +01:00
pstore pstore/zone: Add a null pointer check to the psz_kmsg_read 2024-11-19 09:23:13 +01:00
qnx4 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
qnx6 Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
quota quota: Fix rcu annotations of inode dquot pointers 2024-11-19 08:44:52 +01:00
ramfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
reiserfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
romfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sdfat Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
squashfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sysfs fs: sysfs: Fix reference leak in sysfs_break_active_protection() 2024-11-19 11:32:23 +01:00
sysv sysv: don't call sb_bread() with pointers_lock held 2024-11-19 09:23:14 +01:00
tracefs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ubifs ubifs: Set page uptodate in the correct place 2024-11-19 09:22:16 +01:00
udf udf: prevent integer overflow in udf_bitmap_free_blocks() 2024-11-23 23:20:23 +01:00
ufs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
unicode Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
vboxsf vboxsf: Avoid an spurious warning if load_nls_xxx() fails 2024-11-19 09:22:46 +01:00
verity Revert "fs: add file and path permissions helpers" 2024-11-19 13:30:21 +01:00
xfs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
zonefs zonefs: Improve error handling 2024-11-18 22:25:32 +01:00
aio.c fs/aio: Check IOCB_AIO_RW before the struct aio_kiocb conversion 2024-11-19 09:22:39 +01:00
anon_inodes.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
attr.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
bad_inode.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_aout.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_elf.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_elf_fdpic.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_em86.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_flat.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_misc.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
binfmt_script.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
block_dev.c block: Don't invalidate pagecache for invalid falloc modes 2024-11-18 12:12:06 +01:00
buffer.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
char_dev.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
compat_binfmt_elf.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
coredump.c exec: Simplify unshare_files 2024-11-19 12:27:27 +01:00
d_path.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dax.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dcache.c fs: better handle deep ancestor chains in is_subdir() 2024-11-19 14:19:50 +01:00
dcookies.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
direct-io.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dlog_hook.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
drop_caches.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
eventfd.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
eventpoll.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
exec.c exec: Fix ToCToU between perm check and set-uid/gid usage 2024-11-23 23:20:31 +01:00
fcntl.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fhandle.c do_sys_name_to_handle(): use kzalloc() to fix kernel-infoleak 2024-11-19 08:44:37 +01:00
file.c protect the fetch of ->fd[fd] in do_dup2() from mispredictions 2024-11-23 23:20:21 +01:00
file_table.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
filesystems.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs-writeback.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs_context.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs_parser.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs_pin.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs_struct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fs_types.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fsopen.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
init.c Revert "fs: add file and path permissions helpers" 2024-11-19 13:30:21 +01:00
inode.c fs: add ctime accessors infrastructure 2024-11-18 12:11:13 +01:00
internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ioctl.c lsm: new security_file_ioctl_compat() hook 2024-11-18 12:12:58 +01:00
Kconfig NFSD: Remove CONFIG_NFSD_V3 2024-11-19 12:27:54 +01:00
Kconfig.binfmt Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kernel_read_file.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
libfs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
locks.c filelock: Fix fcntl/close race recovery compat path 2024-11-19 14:19:53 +01:00
Makefile Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
mbcache.c mbcache: Speed up cache entry creation 2024-11-19 17:58:19 +01:00
mount.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
mpage.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
namei.c Revert "namei: introduce struct renamedata" 2024-11-19 13:45:08 +01:00
namespace.c fs: indicate request originates from old mount API 2024-11-18 12:12:26 +01:00
no-block.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
nsfs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
open.c ftruncate: pass a signed offset 2024-11-19 14:19:34 +01:00
pipe.c pipe: wakeup wr_wait after setting max_usage 2024-11-18 12:13:04 +01:00
pnode.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
pnode.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
posix_acl.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
proc_namespace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
read_write.c security: samsung: defex_lsm: nuke 2024-06-15 16:20:49 -03:00
readdir.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
remap_range.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
select.c fs/select: rework stack allocation hack for clang 2024-11-19 08:44:37 +01:00
seq_file.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
signalfd.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
splice.c splice: don't generate zero-len segement bvecs 2024-11-19 17:42:24 +01:00
stack.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stat.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
statfs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
super.c fs: don't allow non-init s_user_ns for filesystems without FS_USERNS_MOUNT 2024-11-23 23:20:18 +01:00
sync.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
timerfd.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
userfaultfd.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
utimes.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
xattr.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00