ipv4: Prepare fib_config for IPv6 gateway

Similar to rtable, fib_config needs to allow the gateway to be either an
IPv4 or an IPv6 address. To that end, rename fc_gw to fc_gw4 to mean an
IPv4 address and add fc_gw_family. Checks on 'is a gateway set' are changed
to see if fc_gw_family is set. In the process prepare the code for a
fc_gw_family == AF_INET6.
Signed-off-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_fib.h

@@ -32,10 +32,11 @@ struct fib_config {
 	u8			fc_protocol;
 	u8			fc_scope;
 	u8			fc_type;
-	/* 3 bytes unused */
+	u8			fc_gw_family;
+	/* 2 bytes unused */
 	u32			fc_table;
 	__be32			fc_dst;
-	__be32			fc_gw;
+	__be32			fc_gw4;
 	int			fc_oif;
 	u32			fc_flags;
 	u32			fc_priority;

net/ipv4/fib_frontend.c

@@ -558,7 +558,8 @@ static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,
 	if (rt->rt_gateway.sa_family == AF_INET && addr) {
 		unsigned int addr_type;
 
-		cfg->fc_gw = addr;
+		cfg->fc_gw4 = addr;
+		cfg->fc_gw_family = AF_INET;
 		addr_type = inet_addr_type_table(net, addr, cfg->fc_table);
 		if (rt->rt_flags & RTF_GATEWAY &&
 		    addr_type == RTN_UNICAST)
@@ -568,7 +569,7 @@ static int rtentry_to_fib_config(struct net *net, int cmd, struct rtentry *rt,
 	if (cmd == SIOCDELRT)
 		return 0;
 
-	if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw)
+	if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw_family)
 		return -EINVAL;
 
 	if (cfg->fc_scope == RT_SCOPE_NOWHERE)
@@ -708,7 +709,8 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
 			cfg->fc_oif = nla_get_u32(attr);
 			break;
 		case RTA_GATEWAY:
-			cfg->fc_gw = nla_get_be32(attr);
+			cfg->fc_gw_family = AF_INET;
+			cfg->fc_gw4 = nla_get_be32(attr);
 			break;
 		case RTA_VIA:
 			NL_SET_ERR_MSG(extack, "IPv4 does not support RTA_VIA attribute");

net/ipv4/fib_semantics.c

@@ -511,8 +511,8 @@ int fib_nh_init(struct net *net, struct fib_nh *nh,
 		goto init_failure;
 
 	nh->fib_nh_oif = cfg->fc_oif;
-	if (cfg->fc_gw) {
-		nh->fib_nh_gw4 = cfg->fc_gw;
+	if (cfg->fc_gw_family == AF_INET) {
+		nh->fib_nh_gw4 = cfg->fc_gw4;
 		nh->fib_nh_gw_family = AF_INET;
 	}
 	nh->fib_nh_flags = cfg->fc_flags;
@@ -589,8 +589,10 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);
 
 			nla = nla_find(attrs, attrlen, RTA_GATEWAY);
-			if (nla)
-				fib_cfg.fc_gw = nla_get_in_addr(nla);
+			if (nla) {
+				fib_cfg.fc_gw_family = AF_INET;
+				fib_cfg.fc_gw4 = nla_get_in_addr(nla);
+			}
 
 			nla = nla_find(attrs, attrlen, RTA_FLOW);
 			if (nla)
@@ -616,11 +618,15 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh,
 			       "Nexthop device index does not match RTA_OIF");
 		goto errout;
 	}
-	if (cfg->fc_gw && fi->fib_nh->fib_nh_gw4 != cfg->fc_gw) {
+	if (cfg->fc_gw_family) {
+		if (cfg->fc_gw_family != fi->fib_nh->fib_nh_gw_family ||
+		    (cfg->fc_gw_family == AF_INET &&
+		     fi->fib_nh->fib_nh_gw4 != cfg->fc_gw4)) {
 			NL_SET_ERR_MSG(extack,
 				       "Nexthop gateway does not match RTA_GATEWAY");
 			goto errout;
 		}
+	}
 #ifdef CONFIG_IP_ROUTE_CLASSID
 	if (cfg->fc_flow && fi->fib_nh->nh_tclassid != cfg->fc_flow) {
 		NL_SET_ERR_MSG(extack,
@@ -719,7 +725,7 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 	if (cfg->fc_priority && cfg->fc_priority != fi->fib_priority)
 		return 1;
 
-	if (cfg->fc_oif || cfg->fc_gw) {
+	if (cfg->fc_oif || cfg->fc_gw_family) {
 		if (cfg->fc_encap) {
 			if (fib_encap_match(cfg->fc_encap_type, cfg->fc_encap,
 					    fi->fib_nh, cfg, extack))
@@ -730,10 +736,16 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi,
 		    cfg->fc_flow != fi->fib_nh->nh_tclassid)
 			return 1;
 #endif
-		if ((!cfg->fc_oif || cfg->fc_oif == fi->fib_nh->fib_nh_oif) &&
-		    (!cfg->fc_gw  || cfg->fc_gw == fi->fib_nh->fib_nh_gw4))
-			return 0;
+		if ((cfg->fc_oif && cfg->fc_oif != fi->fib_nh->fib_nh_oif) ||
+		    (cfg->fc_gw_family &&
+		     cfg->fc_gw_family != fi->fib_nh->fib_nh_gw_family))
 			return 1;
+
+		if (cfg->fc_gw_family == AF_INET &&
+		    cfg->fc_gw4 != fi->fib_nh->fib_nh_gw4)
+			return 1;
+
+		return 0;
 	}
 
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
@@ -1204,7 +1216,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 		goto failure;
 
 	if (fib_props[cfg->fc_type].error) {
-		if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp) {
+		if (cfg->fc_gw_family || cfg->fc_oif || cfg->fc_mp) {
 			NL_SET_ERR_MSG(extack,
 				       "Gateway, device and multipath can not be specified for this route type");
 			goto err_inval;