| From: Marc Dionne <marc.dionne@auristor.com> |
| Date: Thu, 6 Jul 2017 15:50:18 +0100 |
| Subject: afs: Ignore AFS_ACE_READ and AFS_ACE_WRITE for directories |
| |
| commit fd2498211a551fd42b2d6b9050d649d43536e75c upstream. |
| |
| 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> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/afs/security.c | 5 ++--- |
| 1 file changed, 2 insertions(+), 3 deletions(-) |
| |
| --- a/fs/afs/security.c |
| +++ b/fs/afs/security.c |
| @@ -327,12 +327,11 @@ int afs_permission(struct inode *inode, |
| 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(); |
