Commit bd92d7fe authored by Al Viro's avatar Al Viro
Browse files

Make trailing symlink resolution in path_lookupat() iterative 



Now the only caller of link_path_walk() that does *not* pass
LOOKUP_PARENT is do_follow_link()

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b21041d0

fs/namei.c

+53 −10
Original line number Diff line number Diff line
@@ -1588,12 +1588,23 @@ static int path_init(int dfd, const char *name, unsigned int flags, 
	return retval;

}



static inline int lookup_last(struct nameidata *nd, struct path *path)

{

	if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])

		nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;



	nd->flags &= ~LOOKUP_PARENT;

	return walk_component(nd, path, &nd->last, nd->last_type,

					nd->flags & LOOKUP_FOLLOW);

}



/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */

static int path_lookupat(int dfd, const char *name,

				unsigned int flags, struct nameidata *nd)

{

	struct file *base = NULL;

	int retval;

	struct path path;

	int err;



	/*

	 * Path walking is largely split up into 2 different synchronisation
@@ -1609,23 +1620,55 @@ static int path_lookupat(int dfd, const char *name, 
	 * be handled by restarting a traditional ref-walk (which will always

	 * be able to complete).

	 */

	retval = path_init(dfd, name, flags, nd, &base);

	err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);



	if (unlikely(retval))

		return retval;

	if (unlikely(err))

		return err;



	current->total_link_count = 0;

	retval = link_path_walk(name, nd);

	err = link_path_walk(name, nd);



	if (!err && !(flags & LOOKUP_PARENT)) {

		int count = 0;

		err = lookup_last(nd, &path);

		while (err > 0) {

			void *cookie;

			struct path link = path;

			struct inode *inode = link.dentry->d_inode;



			if (count++ > 32) {

				path_put_conditional(&path, nd);

				path_put(&nd->path);

				err = -ELOOP;

				break;

			}

			cond_resched();

			nd->flags |= LOOKUP_PARENT;

			err = __do_follow_link(&link, nd, &cookie);

			if (!err)

				err = lookup_last(nd, &path);

			if (!IS_ERR(cookie) && inode->i_op->put_link)

				inode->i_op->put_link(link.dentry, nd, cookie);

			path_put(&link);

		}

	}



	if (nd->flags & LOOKUP_RCU) {

		/* went all way through without dropping RCU */

		BUG_ON(retval);

		BUG_ON(err);

		if (nameidata_drop_rcu_last(nd))

			retval = -ECHILD;

			err = -ECHILD;

	}



	if (!retval)

		retval = handle_reval_path(nd);

	if (!err)

		err = handle_reval_path(nd);



	if (!err && nd->flags & LOOKUP_DIRECTORY) {

		if (!nd->inode->i_op->lookup) {

			path_put(&nd->path);

			return -ENOTDIR;

		}

	}



	if (base)

		fput(base);
@@ -1634,7 +1677,7 @@ static int path_lookupat(int dfd, const char *name, 
		path_put(&nd->root);

		nd->root.mnt = NULL;

	}

	return retval;

	return err;

}



static int do_path_lookup(int dfd, const char *name,