[PATCH 24/33] ipv6: add ip6_sock_set_addr_preferences

[Christoph Hellwig]

Add a helper to directly set the IPV6_ADD_PREFERENCES sockopt from kernel
space without going through a fake uaccess.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 include/net/ipv6.h       |   1 +
 net/ipv6/ipv6_sockglue.c | 127 +++++++++++++++++++++------------------
 net/sunrpc/xprtsock.c    |   8 ++-
 3 files changed, 75 insertions(+), 61 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 69bc1651aaef8..04b2bc1935054 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1177,5 +1177,6 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex,
 
 int ip6_sock_set_v6only(struct sock *sk, bool val);
 void ip6_sock_set_recverr(struct sock *sk, bool val);
+int ip6_sock_set_addr_preferences(struct sock *sk, bool val);
 
 #endif /* _NET_IPV6_H */
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 3c67626b6f5a9..c23d42e809d7e 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -157,6 +157,74 @@ void ip6_sock_set_recverr(struct sock *sk, bool val)
 }
 EXPORT_SYMBOL(ip6_sock_set_recverr);
 
+static 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;
+}
+
+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;
+}
+EXPORT_SYMBOL(ip6_sock_set_addr_preferences);
+
 static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		    char __user *optval, unsigned int optlen)
 {
@@ -859,67 +927,10 @@ 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;
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 88aa198456858..7aaf2baf0c393 100644
--- a/net/sunrpc/xprtsock.c
+++ b/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 +2158,11 @@ 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 &&
+		    IS_REACHABLE(CONFIG_IPV6)) {
+			ip6_sock_set_addr_preferences(sk,
+				IPV6_PREFER_SRC_PUBLIC);
+		}
 
 		xs_tcp_set_socket_timeouts(xprt, sock);
 
-- 
2.26.2