Comment 0 for bug 1697339

forceps (ubuntubugs-web) wrote :

Description: Ubuntu 16.04.2 LTS
Release: 16.04

Package: nfs-common 1:1.2.8-9ubuntu12.1.0

This bug affects all active and proposed versions of nfs-common used by ubuntu (as every version is based on nfs-utils_1.2.8) from trusty to artful.

There is a small error in the code for rpc.gssd that causes it to always perform reverse DNS when looking up the server name to pass to GSSAPI. This causes a problem for NFS4 in environments where reverse DNS is correctly configured. This has been confirmed in Debian and a more recent version of nfs-utils that appears to have fixed this has been pushed to sid:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=803710

However, I do not know if that version of nfs-utils will make it to ubuntu soon. Will it?

If not, the patch to this appears to be rather straightforward.
The error is an '== 1' instead of an '== 0' in two lines of gssd_proc.c that are evaluated when the -D flag to rpc.gssd is not passed (and thus avoid_dns is true)

--- utils/gssd/gssd_proc.c 2017-06-11 15:47:35.000000000 -0700
+++ utils/gssd/gssd_proc_patch.c 2017-06-11 15:48:36.152115792 -0700
@@ -181,17 +181,17 @@
  if (avoid_dns) {
   /*
    * Determine if this is a server name, or an IP address.
    * If it is an IP address, do the DNS lookup otherwise
    * skip the DNS lookup.
    */
   servername = 0;
- if (strchr(name, '.') && inet_pton(AF_INET, name, buf) == 1)
+ if (strchr(name, '.') && inet_pton(AF_INET, name, buf) == 0)
    servername = 1; /* IPv4 */
- else if (strchr(name, ':') && inet_pton(AF_INET6, name, buf) == 1)
+ else if (strchr(name, ':') && inet_pton(AF_INET6, name, buf) == 0)
    servername = 1; /* or IPv6 */

   if (servername) {
    return strdup(name);
   }
  }

Is there any way to get either 1) the updated version of nfs-utils or 2) this patch applied to xenial (and, hopefully, other versions of ubuntu)? Thank you for looking at this!