[SCTP] Support for IPV6_V6ONLY socket option. (Ardelle.fan)

include/net/sctp/sctp.h

@@ -588,6 +588,7 @@ struct sctp6_sock {
 #endif /* CONFIG_IPV6 */
 
 #define sctp_sk(__sk) (&((struct sctp_sock *)__sk)->sctp)
+#define sctp_opt2sk(__sp) &container_of(__sp, struct sctp_sock, sctp)->sk
 
 /* Is a socket of this style? */
 #define sctp_style(sk, style) __sctp_style((sk), (SCTP_SOCKET_##style))

net/sctp/ipv6.c

@@ -475,6 +475,8 @@ static int sctp_v6_available(union sctp_addr *addr, struct sctp_opt *sp)
 	if (type == IPV6_ADDR_MAPPED) {
 		if (sp && !sp->v4mapped)
 			return 0;
+		if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
+			return 0;
 		sctp_v6_map_v4(addr);
 		return sctp_get_af_specific(AF_INET)->available(addr, sp);
 	}
@@ -502,6 +504,8 @@ static int sctp_v6_addr_valid(union sctp_addr *addr, struct sctp_opt *sp)
 		 */
 		if (!sp || !sp->v4mapped)
 			return 0;
+		if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
+			return 0;
 		sctp_v6_map_v4(addr);
 		return sctp_get_af_specific(AF_INET)->addr_valid(addr, sp);
 	}
@@ -731,7 +735,7 @@ static int sctp_inet6_af_supported(sa_family_t family, struct sctp_opt *sp)
 		return 1;
 	/* v4-mapped-v6 addresses */
 	case AF_INET:
-		if (sp->v4mapped)
+		if (!__ipv6_only_sock(sctp_opt2sk(sp)) && sp->v4mapped)
 			return 1;
 	default:
 		return 0;
@@ -776,7 +780,7 @@ static int sctp_inet6_bind_verify(struct sctp_opt *opt, union sctp_addr *addr)
 	else {
 		struct sock *sk;
 		int type = ipv6_addr_type(&addr->v6.sin6_addr);
-		sk = &container_of(opt, struct sctp6_sock, sctp)->sk;
+		sk = sctp_opt2sk(opt);
 		if (type & IPV6_ADDR_LINKLOCAL) {
 			/* Note: Behavior similar to af_inet6.c:
 			 *  1) Overrides previous bound_dev_if
@@ -806,7 +810,7 @@ static int sctp_inet6_send_verify(struct sctp_opt *opt, union sctp_addr *addr)
 	else {
 		struct sock *sk;
 		int type = ipv6_addr_type(&addr->v6.sin6_addr);
-		sk = &container_of(opt, struct sctp6_sock, sctp)->sk;
+		sk = sctp_opt2sk(opt);
 		if (type & IPV6_ADDR_LINKLOCAL) {
 			/* Note: Behavior similar to af_inet6.c:
 			 *  1) Overrides previous bound_dev_if