Commit fd249821 authored Jul 06, 2017 by Marc Dionne Committed by Linus Torvalds Jul 09, 2017

afs: Ignore AFS_ACE_READ and AFS_ACE_WRITE for directories



The AFS_ACE_READ and AFS_ACE_WRITE permission bits should not
be used to make access decisions for the directory itself.  They
are meant to control access for the objects contained in that
directory.

Reading a directory is allowed if the AFS_ACE_LOOKUP bit is set.
This would cause an incorrect access denied error for a directory
with AFS_ACE_LOOKUP but not AFS_ACE_READ.

The AFS_ACE_WRITE bit does not allow operations that modify the
directory.  For a directory with AFS_ACE_WRITE but neither
AFS_ACE_INSERT nor AFS_ACE_DELETE, this would result in trying
operations that would ultimately be denied by the server.

Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f991af3d

fs/afs/security.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -327,12 +327,11 @@ int afs_permission(struct inode *inode, int mask)
		if (!(access & AFS_ACE_LOOKUP))
		goto permission_denied;
		} else if (mask & MAY_READ) {
		if (!(access & AFS_ACE_READ))
		if (!(access & AFS_ACE_LOOKUP))
		goto permission_denied;
		} else if (mask & MAY_WRITE) {
		if (!(access & (AFS_ACE_DELETE \| /* rmdir, unlink, rename from */
		AFS_ACE_INSERT \| /* create, mkdir, symlink, rename to */
		AFS_ACE_WRITE))) /* chmod */
		AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
		goto permission_denied;
		} else {
		BUG();