net: add helpers checking if socket can be bound to nonlocal address

The construction "net->ipv4.sysctl_ip_nonlocal_bind || inet->freebind
|| inet->transparent" is present three times and its IPv6 counterpart
is also present three times. We introduce two small helpers to
characterize these tests uniformly.
Signed-off-by: Vincent Bernat <vincent@bernat.im>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_sock.h

@@ -359,4 +359,12 @@ static inline bool inet_get_convert_csum(struct sock *sk)
 	return !!inet_sk(sk)->convert_csum;
 }
 
+
+static inline bool inet_can_nonlocal_bind(struct net *net,
+					  struct inet_sock *inet)
+{
+	return net->ipv4.sysctl_ip_nonlocal_bind ||
+		inet->freebind || inet->transparent;
+}
+
 #endif	/* _INET_SOCK_H */

include/net/ipv6.h

@@ -766,6 +766,13 @@ static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,
 	return hlimit;
 }
 
+static inline bool ipv6_can_nonlocal_bind(struct net *net,
+					  struct inet_sock *inet)
+{
+	return net->ipv6.sysctl.ip_nonlocal_bind ||
+		inet->freebind || inet->transparent;
+}
+
 /* copy IPv6 saddr & daddr to flow_keys, possibly using 64bit load/store
  * Equivalent to :	flow->v6addrs.src = iph->saddr;
  *			flow->v6addrs.dst = iph->daddr;

net/ipv4/af_inet.c

@@ -486,8 +486,7 @@ int __inet_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
 	 *  is temporarily down)
 	 */
 	err = -EADDRNOTAVAIL;
-	if (!net->ipv4.sysctl_ip_nonlocal_bind &&
-	    !(inet->freebind || inet->transparent) &&
+	if (!inet_can_nonlocal_bind(net, inet) &&
 	    addr->sin_addr.s_addr != htonl(INADDR_ANY) &&
 	    chk_addr_ret != RTN_LOCAL &&
 	    chk_addr_ret != RTN_MULTICAST &&

net/ipv4/ping.c

@@ -320,8 +320,7 @@ static int ping_check_bind_addr(struct sock *sk, struct inet_sock *isk,
 		if (addr->sin_addr.s_addr == htonl(INADDR_ANY))
 			chk_addr_ret = RTN_LOCAL;
 
-		if ((net->ipv4.sysctl_ip_nonlocal_bind == 0 &&
-		    isk->freebind == 0 && isk->transparent == 0 &&
+		if ((!inet_can_nonlocal_bind(net, isk) &&
 		     chk_addr_ret != RTN_LOCAL) ||
 		    chk_addr_ret == RTN_MULTICAST ||
 		    chk_addr_ret == RTN_BROADCAST)
@@ -361,8 +360,7 @@ static int ping_check_bind_addr(struct sock *sk, struct inet_sock *isk,
 						    scoped);
 		rcu_read_unlock();
 
-		if (!(net->ipv6.sysctl.ip_nonlocal_bind ||
-		      isk->freebind || isk->transparent || has_addr ||
+		if (!(ipv6_can_nonlocal_bind(net, isk) || has_addr ||
 		      addr_type == IPV6_ADDR_ANY))
 			return -EADDRNOTAVAIL;
 

net/ipv6/af_inet6.c

@@ -322,8 +322,7 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
 		/* Reproduce AF_INET checks to make the bindings consistent */
 		v4addr = addr->sin6_addr.s6_addr32[3];
 		chk_addr_ret = inet_addr_type(net, v4addr);
-		if (!net->ipv4.sysctl_ip_nonlocal_bind &&
-		    !(inet->freebind || inet->transparent) &&
+		if (!inet_can_nonlocal_bind(net, inet) &&
 		    v4addr != htonl(INADDR_ANY) &&
 		    chk_addr_ret != RTN_LOCAL &&
 		    chk_addr_ret != RTN_MULTICAST &&
@@ -362,8 +361,7 @@ static int __inet6_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len,
 			 */
 			v4addr = LOOPBACK4_IPV6;
 			if (!(addr_type & IPV6_ADDR_MULTICAST))	{
-				if (!net->ipv6.sysctl.ip_nonlocal_bind &&
-				    !(inet->freebind || inet->transparent) &&
+				if (!ipv6_can_nonlocal_bind(net, inet) &&
 				    !ipv6_chk_addr(net, &addr->sin6_addr,
 						   dev, 0)) {
 					err = -EADDRNOTAVAIL;

net/ipv6/datagram.c

@@ -803,8 +803,7 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
 
 			if (addr_type != IPV6_ADDR_ANY) {
 				int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
-				if (!(net->ipv6.sysctl.ip_nonlocal_bind ||
-				      inet_sk(sk)->freebind || inet_sk(sk)->transparent) &&
+				if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) &&
 				    !ipv6_chk_addr_and_flags(net, &src_info->ipi6_addr,
 							     dev, !strict, 0,
 							     IFA_F_TENTATIVE) &&