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android_kernel_google_msm/fs
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Eric W. Biederman 3e34c77b60 fs: Limit sys_mount to only request filesystem modules. 
Modify the request_module to prefix the file system type with "fs-"
and add aliases to all of the filesystems that can be built as modules
to match.

A common practice is to build all of the kernel code and leave code
that is not commonly needed as modules, with the result that many
users are exposed to any bug anywhere in the kernel.

Looking for filesystems with a fs- prefix limits the pool of possible
modules that can be loaded by mount to just filesystems trivially
making things safer with no real cost.

Using aliases means user space can control the policy of which
filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf
with blacklist and alias directives.  Allowing simple, safe,
well understood work-arounds to known problematic software.

This also addresses a rare but unfortunate problem where the filesystem
name is not the same as it's module name and module auto-loading
would not work.  While writing this patch I saw a handful of such
cases.  The most significant being autofs that lives in the module
autofs4.

This is relevant to user namespaces because we can reach the request
module in get_fs_type() without having any special permissions, and
people get uncomfortable when a user specified string (in this case
the filesystem type) goes all of the way to request_module.

After having looked at this issue I don't think there is any
particular reason to perform any filtering or permission checks beyond
making it clear in the module request that we want a filesystem
module.  The common pattern in the kernel is to call request_module()
without regards to the users permissions.  In general all a filesystem
module does once loaded is call register_filesystem() and go to sleep.
Which means there is not much attack surface exposed by loading a
filesytem module unless the filesystem is mounted.  In a user
namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT,
which most filesystems do not set today.

Change-Id: I623b13dbdb44bb9ba7481f29575e1ca4ad8102f4
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reported-by: Kees Cook <keescook@google.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>
2020-12-14 20:34:05 +01:00
..
9p fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
adfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
affs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
afs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
autofs4 stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
befs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
bfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
btrfs fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
cachefiles don't pass nameidata * to vfs_create() 2018-12-07 22:28:48 +04:00
ceph mm: kill vma flag VM_CAN_NONLINEAR 2020-11-29 16:11:40 +03:00
cifs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
coda fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
configfs stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
cramfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
crypto ext4/fscrypto: avoid RCU lookup in d_revalidate 2016-10-29 23:12:37 +08:00
debugfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
devpts fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
dlm
ecryptfs don't pass nameidata * to vfs_create() 2018-12-07 22:28:48 +04:00
efs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
exofs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
exportfs move d_rcu from overlapping d_child to overlapping d_alias 2017-09-22 19:11:55 +03:00
ext2 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
ext3 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
ext4 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
f2fs fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
fat fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
freevxfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
fscache lib/radix-tree.c: make radix_tree_node_alloc() work correctly within interrupt 2020-12-07 21:02:05 +03:00
fuse fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
gfs2 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
hfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
hfsplus fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
hostfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
hpfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
hppfs stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
hugetlbfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
isofs stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
jbd
jbd2 jbd2: Fix unreclaimed pages after truncate in data=journal mode 2016-10-26 23:15:34 +08:00
jffs2 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
jfs fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
lockd
logfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
minix fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
ncpfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
nfs fs: Limit sys_mount to only request filesystem modules. 2020-12-14 20:34:05 +01:00
nfs_common
nfsd userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr 2020-12-07 21:02:21 +03:00
nilfs2 fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
nls
notify fanotify: check file flags passed in fanotify_init 2018-12-07 22:28:48 +04:00
ntfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
ocfs2 fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
omfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
openpromfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
proc fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
pstore fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
qnx4 fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
qnx6 fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
quota vfs: define struct filename and have getname() return it 2018-12-07 22:28:48 +04:00
ramfs don't pass nameidata to ->create() 2018-12-07 22:28:00 +04:00
reiserfs fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
romfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
sdcardfs mm: kill vma flag VM_CAN_NONLINEAR 2020-11-29 16:11:40 +03:00
squashfs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
sysfs stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
sysv fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
ubifs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
udf fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
ufs fs: push sync_filesystem() down to the file system's remount_fs() 2020-11-29 16:11:45 +03:00
xfs fs: make posix_acl_create more useful 2020-12-07 21:02:49 +03:00
yaffs2
aio.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
anon_inodes.c
attr.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
bad_inode.c mm/fs: remove truncate_range 2020-12-07 20:57:30 +03:00
binfmt_aout.c
binfmt_elf.c binfmt_elf: Don't clobber passed executable's file header 2016-10-26 23:15:28 +08:00
binfmt_elf_fdpic.c
binfmt_em86.c
binfmt_flat.c
binfmt_misc.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
binfmt_script.c
binfmt_som.c
bio-integrity.c
bio.c
block_dev.c
buffer.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
char_dev.c
compat.c vfs: define struct filename and have getname() return it 2018-12-07 22:28:48 +04:00
compat_binfmt_elf.c
compat_ioctl.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
dcache.c [O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now... 2018-12-07 22:28:48 +04:00
dcookies.c
direct-io.c
drop_caches.c
eventfd.c
eventpoll.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
exec.c vfs: make path_openat take a struct filename pointer 2018-12-07 22:28:48 +04:00
fcntl.c shm: add sealing API 2020-12-07 22:15:12 +03:00
fhandle.c vfs: read file_handle only once in handle_to_path 2016-10-29 23:12:11 +08:00
fifo.c
file.c
file_table.c get rid of s_files and files_lock 2016-03-21 09:17:55 +08:00
filesystems.c vfs: define struct filename and have getname() return it 2018-12-07 22:28:48 +04:00
fs-writeback.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
fs_struct.c sdcardfs: override umask on mkdir and create 2017-09-22 19:12:02 +03:00
inode.c mm: allow drivers to prevent new writable mappings 2020-12-07 21:08:09 +03:00
internal.h vfs: make path_openat take a struct filename pointer 2018-12-07 22:28:48 +04:00
ioctl.c
ioprio.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
Kconfig fs: remove generic_acl 2020-12-07 21:02:53 +03:00
Kconfig.binfmt
libfs.c stop passing nameidata to ->lookup() 2018-12-07 22:26:28 +04:00
locks.c
Makefile fs: remove generic_acl 2020-12-07 21:02:53 +03:00
mbcache.c
mount.h
mpage.c
namei.c fs: add get_acl helper 2020-12-07 21:02:40 +03:00
namespace.c vfs: define struct filename and have getname() return it 2018-12-07 22:28:48 +04:00
no-block.c
open.c fs: Fix file mode for O_TMPFILE 2018-12-07 22:28:48 +04:00
pipe.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
pnode.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
pnode.h ANDROID: mnt: remount should propagate to slaves of slaves 2017-09-22 19:12:11 +03:00
posix_acl.c fs: NULL dereference in posix_acl_to_xattr() 2020-12-07 21:05:11 +03:00
proc_namespace.c vfs: Allow filesystems to access their private mount data 2017-09-22 19:12:06 +03:00
read_write.c
read_write.h
readdir.c kernel: Only expose su when daemon is running 2017-05-19 18:41:25 -06:00
select.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
seq_file.c
signalfd.c
splice.c Merge remote-tracking branch 'stable/linux-3.4.y' into lineage-15.1 2017-12-27 17:13:15 +03:00
stack.c
stat.c vfs: make O_PATH file descriptors usable for 'fstat()' 2020-11-22 01:21:34 +03:00
statfs.c
super.c vmscan: remove obsolete shrink_control comment 2020-11-29 16:11:26 +03:00
sync.c fs/sync.c: make sync_file_range(2) use WB_SYNC_NONE writeback 2017-12-31 13:02:49 +03:00
timerfd.c timerfd: support CLOCK_BOOTTIME clock 2017-08-27 19:07:23 +03:00
utimes.c vfs: Add setattr2 for filesystems with per mount permissions 2017-09-22 19:12:07 +03:00
xattr.c fs, xattr: fix bug when removing a name not in xattr list 2020-12-07 21:02:30 +03:00