Commit d1566268 authored by David Ahern's avatar David Ahern Committed by David S. Miller
Browse files

ipv4: Allow ipv6 gateway with ipv4 routes 



Add support for RTA_VIA and allow an IPv6 nexthop for v4 routes:
   $ ip ro add 172.16.1.0/24 via inet6 2001:db8::1 dev eth0
   $ ip ro ls
   ...
   172.16.1.0/24 via inet6 2001:db8::1 dev eth0

For convenience and simplicity, userspace can use RTA_VIA to specify
AF_INET or AF_INET6 gateway.

The common fib_nexthop_info dump function compares the gateway address
family to the nh_common family to know if the gateway should be encoded
as RTA_VIA or RTA_GATEWAY.

Signed-off-by: default avatarDavid Ahern <dsahern@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 19a9d136

include/net/ip_fib.h

+2 −0
Original line number Diff line number Diff line
@@ -401,6 +401,8 @@ static inline bool fib4_rules_early_flow_dissect(struct net *net, 
/* Exported by fib_frontend.c */

extern const struct nla_policy rtm_ipv4_policy[];

void ip_fib_init(void);

int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,

		    struct netlink_ext_ack *extack);

__be32 fib_compute_spec_dst(struct sk_buff *skb);

bool fib_info_nh_uses_dev(struct fib_info *fi, const struct net_device *dev);

int fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,

net/ipv4/fib_frontend.c

+57 −3
Original line number Diff line number Diff line
@@ -665,10 +665,55 @@ const struct nla_policy rtm_ipv4_policy[RTA_MAX + 1] = { 
	[RTA_DPORT]		= { .type = NLA_U16 },

};



int fib_gw_from_via(struct fib_config *cfg, struct nlattr *nla,

		    struct netlink_ext_ack *extack)

{

	struct rtvia *via;

	int alen;



	if (nla_len(nla) < offsetof(struct rtvia, rtvia_addr)) {

		NL_SET_ERR_MSG(extack, "Invalid attribute length for RTA_VIA");

		return -EINVAL;

	}



	via = nla_data(nla);

	alen = nla_len(nla) - offsetof(struct rtvia, rtvia_addr);



	switch (via->rtvia_family) {

	case AF_INET:

		if (alen != sizeof(__be32)) {

			NL_SET_ERR_MSG(extack, "Invalid IPv4 address in RTA_VIA");

			return -EINVAL;

		}

		cfg->fc_gw_family = AF_INET;

		cfg->fc_gw4 = *((__be32 *)via->rtvia_addr);

		break;

	case AF_INET6:

#ifdef CONFIG_IPV6

		if (alen != sizeof(struct in6_addr)) {

			NL_SET_ERR_MSG(extack, "Invalid IPv6 address in RTA_VIA");

			return -EINVAL;

		}

		cfg->fc_gw_family = AF_INET6;

		cfg->fc_gw6 = *((struct in6_addr *)via->rtvia_addr);

#else

		NL_SET_ERR_MSG(extack, "IPv6 support not enabled in kernel");

		return -EINVAL;

#endif

		break;

	default:

		NL_SET_ERR_MSG(extack, "Unsupported address family in RTA_VIA");

		return -EINVAL;

	}



	return 0;

}



static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,

			     struct nlmsghdr *nlh, struct fib_config *cfg,

			     struct netlink_ext_ack *extack)

{

	bool has_gw = false, has_via = false;

	struct nlattr *attr;

	int err, remaining;

	struct rtmsg *rtm;
@@ -709,13 +754,16 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb, 
			cfg->fc_oif = nla_get_u32(attr);

			break;

		case RTA_GATEWAY:

			has_gw = true;

			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");

			err = -EINVAL;

			has_via = true;

			err = fib_gw_from_via(cfg, attr, extack);

			if (err)

				goto errout;

			break;

		case RTA_PRIORITY:

			cfg->fc_priority = nla_get_u32(attr);

			break;
@@ -754,6 +802,12 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb, 
		}

	}



	if (has_gw && has_via) {

		NL_SET_ERR_MSG(extack,

			       "Nexthop configuration can not contain both GATEWAY and VIA");

		goto errout;

	}



	return 0;

errout:

	return err;

net/ipv4/fib_semantics.c

+64 −5
Original line number Diff line number Diff line
@@ -606,12 +606,22 @@ static int fib_get_nhs(struct fib_info *fi, struct rtnexthop *rtnh, 


		attrlen = rtnh_attrlen(rtnh);

		if (attrlen > 0) {

			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);

			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);



			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

			nlav = nla_find(attrs, attrlen, RTA_VIA);

			if (nla && nlav) {

				NL_SET_ERR_MSG(extack,

					       "Nexthop configuration can not contain both GATEWAY and VIA");

				return -EINVAL;

			}

			if (nla) {

				fib_cfg.fc_gw_family = AF_INET;

				fib_cfg.fc_gw4 = nla_get_in_addr(nla);

			} else if (nlav) {

				ret = fib_gw_from_via(&fib_cfg, nlav, extack);

				if (ret)

					goto errout;

			}



			nla = nla_find(attrs, attrlen, RTA_FLOW);
@@ -792,11 +802,43 @@ int fib_nh_match(struct fib_config *cfg, struct fib_info *fi, 


		attrlen = rtnh_attrlen(rtnh);

		if (attrlen > 0) {

			struct nlattr *nla, *attrs = rtnh_attrs(rtnh);

			struct nlattr *nla, *nlav, *attrs = rtnh_attrs(rtnh);



			nla = nla_find(attrs, attrlen, RTA_GATEWAY);

			if (nla && nla_get_in_addr(nla) != nh->fib_nh_gw4)

			nlav = nla_find(attrs, attrlen, RTA_VIA);

			if (nla && nlav) {

				NL_SET_ERR_MSG(extack,

					       "Nexthop configuration can not contain both GATEWAY and VIA");

				return -EINVAL;

			}



			if (nla) {

				if (nh->fib_nh_gw_family != AF_INET ||

				    nla_get_in_addr(nla) != nh->fib_nh_gw4)

					return 1;

			} else if (nlav) {

				struct fib_config cfg2;

				int err;



				err = fib_gw_from_via(&cfg2, nlav, extack);

				if (err)

					return err;



				switch (nh->fib_nh_gw_family) {

				case AF_INET:

					if (cfg2.fc_gw_family != AF_INET ||

					    cfg2.fc_gw4 != nh->fib_nh_gw4)

						return 1;

					break;

				case AF_INET6:

					if (cfg2.fc_gw_family != AF_INET6 ||

					    ipv6_addr_cmp(&cfg2.fc_gw6,

							  &nh->fib_nh_gw6))

						return 1;

					break;

				}

			}



#ifdef CONFIG_IP_ROUTE_CLASSID

			nla = nla_find(attrs, attrlen, RTA_FLOW);

			if (nla && nla_get_u32(nla) != nh->nh_tclassid)
@@ -1429,8 +1471,25 @@ int fib_nexthop_info(struct sk_buff *skb, const struct fib_nh_common *nhc, 
			goto nla_put_failure;

		break;

	case AF_INET6:

		if (nla_put_in6_addr(skb, RTA_GATEWAY, &nhc->nhc_gw.ipv6) < 0)

		/* if gateway family does not match nexthop family

		 * gateway is encoded as RTA_VIA

		 */

		if (nhc->nhc_gw_family != nhc->nhc_family) {

			int alen = sizeof(struct in6_addr);

			struct nlattr *nla;

			struct rtvia *via;



			nla = nla_reserve(skb, RTA_VIA, alen + 2);

			if (!nla)

				goto nla_put_failure;



			via = nla_data(nla);

			via->rtvia_family = AF_INET6;

			memcpy(via->rtvia_addr, &nhc->nhc_gw.ipv6, alen);

		} else if (nla_put_in6_addr(skb, RTA_GATEWAY,

					    &nhc->nhc_gw.ipv6) < 0) {

			goto nla_put_failure;

		}

		break;

	}

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