diff options
| -rw-r--r-- | fs/namespace.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index de402eb6eaf..a72eaabfe8f 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1484,13 +1484,30 @@ out_unlock: } /* + * Sanity check the flags to change_mnt_propagation. + */ + +static int flags_to_propagation_type(int flags) +{ + int type = flags & ~MS_REC; + + /* Fail if any non-propagation flags are set */ + if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) + return 0; + /* Only one propagation flag should be set */ + if (!is_power_of_2(type)) + return 0; + return type; +} + +/* * recursively change the type of the mountpoint. */ static int do_change_type(struct path *path, int flag) { struct vfsmount *m, *mnt = path->mnt; int recurse = flag & MS_REC; - int type = flag & ~MS_REC; + int type; int err = 0; if (!capable(CAP_SYS_ADMIN)) @@ -1499,6 +1516,10 @@ static int do_change_type(struct path *path, int flag) if (path->dentry != path->mnt->mnt_root) return -EINVAL; + type = flags_to_propagation_type(flag); + if (!type) + return -EINVAL; + down_write(&namespace_sem); if (type == MS_SHARED) { err = invent_group_ids(mnt, recurse); |