ipv6: add ip6_sock_set_addr_preferences

Add a helper to directly set the IPV6_ADD_PREFERENCES sockopt from kernel
space without going through a fake uaccess.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/net/ipv6.h

@@ -1195,4 +1195,71 @@ static inline void ip6_sock_set_recverr(struct sock *sk)
 	release_sock(sk);
 }
 
+static inline int __ip6_sock_set_addr_preferences(struct sock *sk, int val)
+{
+	unsigned int pref = 0;
+	unsigned int prefmask = ~0;
+
+	/* check PUBLIC/TMP/PUBTMP_DEFAULT conflicts */
+	switch (val & (IPV6_PREFER_SRC_PUBLIC |
+		       IPV6_PREFER_SRC_TMP |
+		       IPV6_PREFER_SRC_PUBTMP_DEFAULT)) {
+	case IPV6_PREFER_SRC_PUBLIC:
+		pref |= IPV6_PREFER_SRC_PUBLIC;
+		prefmask &= ~(IPV6_PREFER_SRC_PUBLIC |
+			      IPV6_PREFER_SRC_TMP);
+		break;
+	case IPV6_PREFER_SRC_TMP:
+		pref |= IPV6_PREFER_SRC_TMP;
+		prefmask &= ~(IPV6_PREFER_SRC_PUBLIC |
+			      IPV6_PREFER_SRC_TMP);
+		break;
+	case IPV6_PREFER_SRC_PUBTMP_DEFAULT:
+		prefmask &= ~(IPV6_PREFER_SRC_PUBLIC |
+			      IPV6_PREFER_SRC_TMP);
+		break;
+	case 0:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* check HOME/COA conflicts */
+	switch (val & (IPV6_PREFER_SRC_HOME | IPV6_PREFER_SRC_COA)) {
+	case IPV6_PREFER_SRC_HOME:
+		prefmask &= ~IPV6_PREFER_SRC_COA;
+		break;
+	case IPV6_PREFER_SRC_COA:
+		pref |= IPV6_PREFER_SRC_COA;
+		break;
+	case 0:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* check CGA/NONCGA conflicts */
+	switch (val & (IPV6_PREFER_SRC_CGA|IPV6_PREFER_SRC_NONCGA)) {
+	case IPV6_PREFER_SRC_CGA:
+	case IPV6_PREFER_SRC_NONCGA:
+	case 0:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	inet6_sk(sk)->srcprefs = (inet6_sk(sk)->srcprefs & prefmask) | pref;
+	return 0;
+}
+
+static inline int ip6_sock_set_addr_preferences(struct sock *sk, bool val)
+{
+	int ret;
+
+	lock_sock(sk);
+	ret = __ip6_sock_set_addr_preferences(sk, val);
+	release_sock(sk);
+	return ret;
+}
+
 #endif /* _NET_IPV6_H */

net/ipv6/ipv6_sockglue.c

@@ -845,67 +845,10 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		break;
 
 	case IPV6_ADDR_PREFERENCES:
-	    {
-		unsigned int pref = 0;
-		unsigned int prefmask = ~0;
-
 		if (optlen < sizeof(int))
 			goto e_inval;
-
-		retv = -EINVAL;
-
-		/* check PUBLIC/TMP/PUBTMP_DEFAULT conflicts */
-		switch (val & (IPV6_PREFER_SRC_PUBLIC|
-			       IPV6_PREFER_SRC_TMP|
-			       IPV6_PREFER_SRC_PUBTMP_DEFAULT)) {
-		case IPV6_PREFER_SRC_PUBLIC:
-			pref |= IPV6_PREFER_SRC_PUBLIC;
-			break;
-		case IPV6_PREFER_SRC_TMP:
-			pref |= IPV6_PREFER_SRC_TMP;
-			break;
-		case IPV6_PREFER_SRC_PUBTMP_DEFAULT:
-			break;
-		case 0:
-			goto pref_skip_pubtmp;
-		default:
-			goto e_inval;
-		}
-
-		prefmask &= ~(IPV6_PREFER_SRC_PUBLIC|
-			      IPV6_PREFER_SRC_TMP);
-pref_skip_pubtmp:
-
-		/* check HOME/COA conflicts */
-		switch (val & (IPV6_PREFER_SRC_HOME|IPV6_PREFER_SRC_COA)) {
-		case IPV6_PREFER_SRC_HOME:
-			break;
-		case IPV6_PREFER_SRC_COA:
-			pref |= IPV6_PREFER_SRC_COA;
-		case 0:
-			goto pref_skip_coa;
-		default:
-			goto e_inval;
-		}
-
-		prefmask &= ~IPV6_PREFER_SRC_COA;
-pref_skip_coa:
-
-		/* check CGA/NONCGA conflicts */
-		switch (val & (IPV6_PREFER_SRC_CGA|IPV6_PREFER_SRC_NONCGA)) {
-		case IPV6_PREFER_SRC_CGA:
-		case IPV6_PREFER_SRC_NONCGA:
-		case 0:
-			break;
-		default:
-			goto e_inval;
-		}
-
-		np->srcprefs = (np->srcprefs & prefmask) | pref;
-		retv = 0;
-
+		retv = __ip6_sock_set_addr_preferences(sk, val);
 		break;
-	    }
 	case IPV6_MINHOPCOUNT:
 		if (optlen < sizeof(int))
 			goto e_inval;

net/sunrpc/xprtsock.c

@@ -2150,7 +2150,6 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 
 	if (!transport->inet) {
 		struct sock *sk = sock->sk;
-		unsigned int addr_pref = IPV6_PREFER_SRC_PUBLIC;
 
 		/* Avoid temporary address, they are bad for long-lived
 		 * connections such as NFS mounts.
@@ -2159,8 +2158,10 @@ static int xs_tcp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
 		 *    knowledge about the normal duration of connections,
 		 *    MAY override this as appropriate.
 		 */
-		kernel_setsockopt(sock, SOL_IPV6, IPV6_ADDR_PREFERENCES,
-				(char *)&addr_pref, sizeof(addr_pref));
+		if (xs_addr(xprt)->sa_family == PF_INET6) {
+			ip6_sock_set_addr_preferences(sk,
+				IPV6_PREFER_SRC_PUBLIC);
+		}
 
 		xs_tcp_set_socket_timeouts(xprt, sock);