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Subject[ 64/78] TOMOYO: Fix mount flags checking order.
3.3-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

commit df91e49477a9be15921cb2854e1d12a3bdb5e425 upstream.

Userspace can pass in arbitrary combinations of MS_* flags to mount().

If both MS_BIND and one of MS_SHARED/MS_PRIVATE/MS_SLAVE/MS_UNBINDABLE are
passed, device name which should be checked for MS_BIND was not checked because
MS_SHARED/MS_PRIVATE/MS_SLAVE/MS_UNBINDABLE had higher priority than MS_BIND.

If both one of MS_BIND/MS_MOVE and MS_REMOUNT are passed, device name which
should not be checked for MS_REMOUNT was checked because MS_BIND/MS_MOVE had
higher priority than MS_REMOUNT.

Fix these bugs by changing priority to MS_REMOUNT -> MS_BIND ->
MS_SHARED/MS_PRIVATE/MS_SLAVE/MS_UNBINDABLE -> MS_MOVE as with do_mount() does.

Also, unconditionally return -EINVAL if more than one of
MS_SHARED/MS_PRIVATE/MS_SLAVE/MS_UNBINDABLE is passed so that TOMOYO will not
generate inaccurate audit logs, for commit 7a2e8a8f "VFS: Sanity check mount
flags passed to change_mnt_propagation()" clarified that these flags must be
exclusively passed.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
security/tomoyo/mount.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)

--- a/security/tomoyo/mount.c
+++ b/security/tomoyo/mount.c
@@ -199,30 +199,32 @@ int tomoyo_mount_permission(char *dev_na
if (flags & MS_REMOUNT) {
type = tomoyo_mounts[TOMOYO_MOUNT_REMOUNT];
flags &= ~MS_REMOUNT;
- }
- if (flags & MS_MOVE) {
- type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
- flags &= ~MS_MOVE;
- }
- if (flags & MS_BIND) {
+ } else if (flags & MS_BIND) {
type = tomoyo_mounts[TOMOYO_MOUNT_BIND];
flags &= ~MS_BIND;
- }
- if (flags & MS_UNBINDABLE) {
- type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
- flags &= ~MS_UNBINDABLE;
- }
- if (flags & MS_PRIVATE) {
+ } else if (flags & MS_SHARED) {
+ if (flags & (MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
+ return -EINVAL;
+ type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
+ flags &= ~MS_SHARED;
+ } else if (flags & MS_PRIVATE) {
+ if (flags & (MS_SHARED | MS_SLAVE | MS_UNBINDABLE))
+ return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
flags &= ~MS_PRIVATE;
- }
- if (flags & MS_SLAVE) {
+ } else if (flags & MS_SLAVE) {
+ if (flags & (MS_SHARED | MS_PRIVATE | MS_UNBINDABLE))
+ return -EINVAL;
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
flags &= ~MS_SLAVE;
- }
- if (flags & MS_SHARED) {
- type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SHARED];
- flags &= ~MS_SHARED;
+ } else if (flags & MS_UNBINDABLE) {
+ if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE))
+ return -EINVAL;
+ type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_UNBINDABLE];
+ flags &= ~MS_UNBINDABLE;
+ } else if (flags & MS_MOVE) {
+ type = tomoyo_mounts[TOMOYO_MOUNT_MOVE];
+ flags &= ~MS_MOVE;
}
if (!type)
type = "<NULL>";



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