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TOMOYO: Fix mount flags checking order.

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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>
This commit is contained in:
Tetsuo Handa 2012-02-29 21:53:22 +09:00 committed by James Morris
parent a69f158902
commit df91e49477
1 changed files with 22 additions and 20 deletions
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42
security/tomoyo/mount.c
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@ -199,30 +199,32 @@ int tomoyo_mount_permission(char *dev_name, struct path *path,
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) {
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_PRIVATE];
flags &= ~MS_PRIVATE;
}
if (flags & MS_SLAVE) {
type = tomoyo_mounts[TOMOYO_MOUNT_MAKE_SLAVE];
flags &= ~MS_SLAVE;
}
if (flags & MS_SHARED) {
} 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;
} 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;
} 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>";