File 0002-gssd-Fix-recent-fix-to-Avoid-DNS-reverse-resolution-.patch of Package nfs-utils

From c93e8d8eeafec3e3228e24dfebef113e0a79a788 Mon Sep 17 00:00:00 2001
From: "Signed-off-by: NeilBrown" <neilb@suse.de>
Date: Tue, 28 May 2013 12:59:22 -0400
Subject: [PATCH] gssd: Fix recent fix to Avoid DNS reverse resolution in gssd.

The final version for this fix that was committed inverted the test
so makes no change in the important cases.

The documentation didn't really help a naive user know when the new -D
flag should be used.

And the code (once fixed) avoided DNS resolution on non-qualified names too,
which probably isn't a good idea.

This patch fixes all three issues.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Steve Dickson <steved@redhat.com>
---
 utils/gssd/gssd.man    | 27 ++++++++++++++++++++++-----
 utils/gssd/gssd_proc.c | 18 ++++++++++--------
 2 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/utils/gssd/gssd.man b/utils/gssd/gssd.man
index 1df75c5..ac13fd4 100644
--- a/utils/gssd/gssd.man
+++ b/utils/gssd/gssd.man
@@ -195,11 +195,28 @@ option when starting
 .BR rpc.gssd .
 .SH OPTIONS
 .TP
-.B -D
-DNS Reverse lookups are not used for determining the
-server names pass to GSSAPI. This option will reverses that and forces 
-the use of DNS Reverse resolution of the server's IP address to 
-retrieve the server name to use in GSAPI authentication.
+.B \-D
+The server name passed to GSSAPI for authentication is normally the
+name exactly as requested.  e.g. for NFS
+it is the server name in the "servername:/path" mount request.  Only if this
+servername appears to be an IP address (IPv4 or IPv6) or an
+unqualified name (no dots) will a reverse DNS lookup
+will be performed to get the canoncial server name.
+
+If
+.B \-D
+is present, a reverse DNS lookup will
+.I always
+be used, even if the server name looks like a canonical name.  So it
+is needed if partially qualified, or non canonical names are regularly
+used.
+
+Using
+.B \-D
+can introduce a security vulnerability, so it is recommended that
+.B \-D
+not be used, and that canonical names always be used when requesting
+services.
 .TP
 .B -f
 Runs
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 6cd4276..b7e2bbb 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -175,7 +175,6 @@ get_servername(const char *name, const struct sockaddr *sa, const char *addr)
 	char			*hostname;
 	char			hbuf[NI_MAXHOST];
 	unsigned char		buf[sizeof(struct in6_addr)];
-	int			servername = 0;
 
 	if (avoid_dns) {
 		/*
@@ -183,15 +182,18 @@ get_servername(const char *name, const struct sockaddr *sa, const char *addr)
 		 * 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)
-			servername = 1; /* IPv4 */
-		else if (strchr(name, ':') && inet_pton(AF_INET6, name, buf) == 1)
-			servername = 1; /* or IPv6 */
-
-		if (servername) {
+		int is_fqdn = 1;
+		if (strchr(name, '.') == NULL)
+			is_fqdn = 0; /* local name */
+		else if (inet_pton(AF_INET, name, buf) == 1)
+			is_fqdn = 0; /* IPv4 address */
+		else if (inet_pton(AF_INET6, name, buf) == 1)
+			is_fqdn = 0; /* IPv6 addrss */
+
+		if (is_fqdn) {
 			return strdup(name);
 		}
+		/* Sorry, cannot avoid dns after all */
 	}
 
 	switch (sa->sa_family) {
-- 
1.8.3.1.487.g3e7a5b4