File 0012-mountd-reject-unknown-client-IP-when-use_ipaddr.patch of Package nfs-utils.23507

From 1f6fe06e53c60f05095cbec8ca4211a1c47f1ca7 Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Mon, 15 Mar 2021 09:36:33 -0400
Subject: [PATCH] mountd: reject unknown client IP when !use_ipaddr.

When use_ipaddr is not in effect, an auth_unix_ip lookup
request from the kernel for an unknown client will be
rejected.  When it IS in effect, these requests are
always granted with the IP address being mapped to a
string form of the address, preceded by a '$'.

This is inconsistent behaviour and could present a small
information leak. It means that, for example, a SETCLIENT
NFSv4 request may or may not succeed depending on an
internal setting in rpc.mountd.

This is easily rectified by always checking if the
client is known.

Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Steve Dickson <steved@redhat.com>
---
 utils/mountd/cache.c |   17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -80,6 +80,7 @@ static void auth_unix_ip(int f)
 	char class[20];
 	char ipaddr[INET6_ADDRSTRLEN + 1];
 	char *client = NULL;
+	struct addrinfo *ai = NULL;
 	struct addrinfo *tmp = NULL;
 	char buf[RPC_CHAN_BUF_SIZE], *bp;
 	int blen;
@@ -105,21 +106,17 @@ static void auth_unix_ip(int f)
 
 	auth_reload();
 
-	/* addr is a valid, interesting address, find the domain name... */
-	if (!use_ipaddr) {
-		struct addrinfo *ai = NULL;
-
-		ai = client_resolve(tmp->ai_addr);
-		if (ai) {
-			client = client_compose(ai);
-			freeaddrinfo(ai);
-		}
+	/* addr is a valid address, find the domain name... */
+	ai = client_resolve(tmp->ai_addr);
+	if (ai) {
+		client = client_compose(ai);
+		freeaddrinfo(ai);
 	}
 	bp = buf; blen = sizeof(buf);
 	qword_add(&bp, &blen, "nfsd");
 	qword_add(&bp, &blen, ipaddr);
 	qword_adduint(&bp, &blen, time(0) + DEFAULT_TTL);
-	if (use_ipaddr) {
+	if (use_ipaddr && client) {
 		memmove(ipaddr + 1, ipaddr, strlen(ipaddr) + 1);
 		ipaddr[0] = '$';
 		qword_add(&bp, &blen, ipaddr);