make sure that mntns_install() doesn't end up with referral for root (4f757f3c) · Commits · 戴 / test

fs/namei.c

+38 −0

Original line number	Diff line number	Diff line
		@@ -2252,6 +2252,35 @@ static inline int lookup_last(struct nameidata *nd)
		return walk_component(nd, 0);
		}

		static int handle_lookup_down(struct nameidata *nd)
		{
		struct path path = nd->path;
		struct inode *inode = nd->inode;
		unsigned seq = nd->seq;
		int err;

		if (nd->flags & LOOKUP_RCU) {
		/*
		* don't bother with unlazy_walk on failure - we are
		* at the very beginning of walk, so we lose nothing
		* if we simply redo everything in non-RCU mode
		*/
		if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
		return -ECHILD;
		} else {
		dget(path.dentry);
		err = follow_managed(&path, nd);
		if (unlikely(err < 0))
		return err;
		inode = d_backing_inode(path.dentry);
		seq = 0;
		}
		path_to_nameidata(&path, nd);
		nd->inode = inode;
		nd->seq = seq;
		return 0;
		}

		/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
		static int path_lookupat(struct nameidata nd, unsigned flags, struct path path)
		{
		@@ -2260,6 +2289,15 @@ static int path_lookupat(struct nameidata nd, unsigned flags, struct path path

		if (IS_ERR(s))
		return PTR_ERR(s);

		if (unlikely(flags & LOOKUP_DOWN)) {
		err = handle_lookup_down(nd);
		if (unlikely(err < 0)) {
		terminate_walk(nd);
		return err;
		}
		}

		while (!(err = link_path_walk(s, nd))
		&& ((err = lookup_last(nd)) > 0)) {
		s = trailing_symlink(nd);

+11 −7

Original line number	Diff line number	Diff line
		@@ -3465,8 +3465,9 @@ static void mntns_put(struct ns_common *ns)
		static int mntns_install(struct nsproxy nsproxy, struct ns_common ns)
		{
		struct fs_struct *fs = current->fs;
		struct mnt_namespace *mnt_ns = to_mnt_ns(ns);
		struct mnt_namespace mnt_ns = to_mnt_ns(ns), old_mnt_ns;
		struct path root;
		int err;

		if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) \|\|
		!ns_capable(current_user_ns(), CAP_SYS_CHROOT) \|\|
		@@ -3477,15 +3478,18 @@ static int mntns_install(struct nsproxy nsproxy, struct ns_common ns)
		return -EINVAL;

		get_mnt_ns(mnt_ns);
		put_mnt_ns(nsproxy->mnt_ns);
		old_mnt_ns = nsproxy->mnt_ns;
		nsproxy->mnt_ns = mnt_ns;

		/* Find the root */
		root.mnt = &mnt_ns->root->mnt;
		root.dentry = mnt_ns->root->mnt.mnt_root;
		path_get(&root);
		while(d_mountpoint(root.dentry) && follow_down_one(&root))
		;
		err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt,
		"/", LOOKUP_DOWN, &root);
		if (err) {
		/* revert to old namespace */
		nsproxy->mnt_ns = old_mnt_ns;
		put_mnt_ns(mnt_ns);
		return err;
		}

		/* Update the pwd and root */
		set_fs_pwd(fs, &root);

+1 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,7 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
		#define LOOKUP_JUMPED 0x1000
		#define LOOKUP_ROOT 0x2000
		#define LOOKUP_EMPTY 0x4000
		#define LOOKUP_DOWN 0x8000

		extern int path_pts(struct path *path);