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nfs: Fix NFS v4 client handling of MAY_EXEC in nfs_permission.

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The problem is that permission checking is skipped if atomic open is
possible, but when exec opens a file, it just opens it O_READONLY which
means EXEC permission will not be checked at that time.

This problem is observed by the following sequence (executed as root):

  mount -t nfs4 server:/ /mnt4
  echo "ls" >/mnt4/foo
  chmod 744 /mnt4/foo
  su guest -c "mnt4/foo"

Signed-off-by: Frank Filz <ffilzlnx@us.ibm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
Tested-by: Eugene Teo <eugeneteo@kernel.sg>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Frank Filz 2009-05-18 17:41:40 -04:00 committed by Linus Torvalds
parent 3633832770
commit 7ee2cb7f32
1 changed files with 2 additions and 1 deletions
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3
fs/nfs/dir.c
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@ -1943,7 +1943,8 @@ int nfs_permission(struct inode *inode, int mask)
case S_IFREG:
/* NFSv4 has atomic_open... */
if (nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN)
&& (mask & MAY_OPEN))
&& (mask & MAY_OPEN)
&& !(mask & MAY_EXEC))
goto out;
break;
case S_IFDIR: