Open with O_CREAT flag set fails to open existing files on non writable directories
commit18c76472ce00748c2d53ff46f3a70537b632f304
authorSachin Prabhu <sprabhu@redhat.com>
Wed, 20 Apr 2011 12:09:35 +0000 (20 13:09 +0100)
committerAndi Kleen <ak@linux.intel.com>
Mon, 1 Aug 2011 20:54:43 +0000 (1 13:54 -0700)
treee4292fb054c277b0f0efcce5652ebd706684adf0
parent00b450cca3cfa0495203f171e787d5c629cbaeac
Open with O_CREAT flag set fails to open existing files on non writable directories

commit 1574dff8996ab1ed92c09012f8038b5566fce313 upstream.

An open on a NFS4 share using the O_CREAT flag on an existing file for
which we have permissions to open but contained in a directory with no
write permissions will fail with EACCES.

A tcpdump shows that the client had set the open mode to UNCHECKED which
indicates that the file should be created if it doesn't exist and
encountering an existing flag is not an error. Since in this case the
file exists and can be opened by the user, the NFS server is wrong in
attempting to check create permissions on the parent directory.

The patch adds a conditional statement to check for create permissions
only if the file doesn't exist.

Signed-off-by: Sachin S. Prabhu <sprabhu@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
fs/nfsd/vfs.c