userns: Don't allow creation if the user is chrooted

[linux-2.6-block.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 50ca17d3cb4506de87465bb4d62f3da5f00553a5..a3035223d4218c13ac6db83f8d5444e454346c2f 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2732,6 +2732,30 @@ bool our_mnt(struct vfsmount *mnt)
        return check_mnt(real_mount(mnt));
 }
 
+bool current_chrooted(void)
+{
+       /* Does the current process have a non-standard root */
+       struct path ns_root;
+       struct path fs_root;
+       bool chrooted;
+
+       /* Find the namespace root */
+       ns_root.mnt = &current->nsproxy->mnt_ns->root->mnt;
+       ns_root.dentry = ns_root.mnt->mnt_root;
+       path_get(&ns_root);
+       while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
+               ;
+
+       get_fs_root(current->fs, &fs_root);
+
+       chrooted = !path_equal(&fs_root, &ns_root);
+
+       path_put(&fs_root);
+       path_put(&ns_root);
+
+       return chrooted;
+}
+
 static void *mntns_get(struct task_struct *task)
 {
        struct mnt_namespace *ns = NULL;