Commit c9a0f75d authored by Al Viro's avatar Al Viro
Browse files

follow_dotdot{,_rcu}(): lift LOOKUP_BENEATH checks out of loop 



Behaviour change: LOOKUP_BENEATH lookup of .. in absolute root
yields an error even if it's not the process' root.  That's
possible only if you'd managed to escape chroot jail by way of
procfs symlinks, but IMO the resulting behaviour is not worse -
more consistent and easier to describe:
	".." in root is "stay where you are", uness LOOKUP_BENEATH
	has been given, in which case it's "fail with EXDEV".

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent abc2c632

fs/namei.c

+10 −10
Original line number Diff line number Diff line
@@ -1370,11 +1370,8 @@ static int follow_dotdot_rcu(struct nameidata *nd) 
	unsigned seq;



	while (1) {

		if (path_equal(&nd->path, &nd->root)) {

			if (unlikely(nd->flags & LOOKUP_BENEATH))

				return -ECHILD;

		if (path_equal(&nd->path, &nd->root))

			break;

		}

		if (nd->path.dentry != nd->path.mnt->mnt_root) {

			struct dentry *old = nd->path.dentry;
@@ -1405,7 +1402,10 @@ static int follow_dotdot_rcu(struct nameidata *nd) 
			nd->seq = seq;

		}

	}

	if (likely(parent)) {

	if (unlikely(!parent)) {

		if (unlikely(nd->flags & LOOKUP_BENEATH))

			return -ECHILD;

	} else {

		nd->path.dentry = parent;

		nd->seq = seq;

	}
@@ -1447,11 +1447,8 @@ static int follow_dotdot(struct nameidata *nd) 
{

	struct dentry *parent = NULL;

	while (1) {

		if (path_equal(&nd->path, &nd->root)) {

			if (unlikely(nd->flags & LOOKUP_BENEATH))

				return -EXDEV;

		if (path_equal(&nd->path, &nd->root))

			break;

		}

		if (nd->path.dentry != nd->path.mnt->mnt_root) {

			/* rare case of legitimate dget_parent()... */

			parent = dget_parent(nd->path.dentry);
@@ -1466,7 +1463,10 @@ static int follow_dotdot(struct nameidata *nd) 
		if (unlikely(nd->flags & LOOKUP_NO_XDEV))

			return -EXDEV;

	}

	if (likely(parent)) {

	if (unlikely(!parent)) {

		if (unlikely(nd->flags & LOOKUP_BENEATH))

			return -EXDEV;

	} else {

		dput(nd->path.dentry);

		nd->path.dentry = parent;

	}