ipv4: Adjust semantics of rt->rt_gateway.
In order to allow prefixed routes, we have to adjust how rt_gateway
is set and interpreted.
The new interpretation is:
1) rt_gateway == 0, destination is on-link, nexthop is iph->daddr
2) rt_gateway != 0, destination requires a nexthop gateway
Abstract the fetching of the proper nexthop value using a new
inline helper, rt_nexthop(), as suggested by Joe Perches.
Signed-off-by: David S. Miller <davem@davemloft.net>
Tested-by: Vijay Subramanian <subramanian.vijay@gmail.com>
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index c38293f..a0124eb 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -475,8 +475,7 @@
return 1;
}
- paddr = skb_rtable(skb)->rt_gateway;
-
+ paddr = rt_nexthop(skb_rtable(skb), ip_hdr(skb)->daddr);
if (arp_set_predefined(inet_addr_type(dev_net(dev), paddr), haddr,
paddr, dev))
return 0;
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index c7a4de0..0a290d7 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -389,7 +389,7 @@
rt = ip_route_output_flow(net, fl4, sk);
if (IS_ERR(rt))
goto no_route;
- if (opt && opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
+ if (opt && opt->opt.is_strictroute && rt->rt_gateway)
goto route_err;
return &rt->dst;
@@ -422,7 +422,7 @@
rt = ip_route_output_flow(net, fl4, sk);
if (IS_ERR(rt))
goto no_route;
- if (opt && opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
+ if (opt && opt->opt.is_strictroute && rt->rt_gateway)
goto route_err;
return &rt->dst;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 42c44b1..b062a98 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -766,7 +766,7 @@
if (skb->protocol == htons(ETH_P_IP)) {
rt = skb_rtable(skb);
- dst = rt->rt_gateway;
+ dst = rt_nexthop(rt, old_iph->daddr);
}
#if IS_ENABLED(CONFIG_IPV6)
else if (skb->protocol == htons(ETH_P_IPV6)) {
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index c528f84..4494015 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -371,7 +371,7 @@
skb_dst_set_noref(skb, &rt->dst);
packet_routed:
- if (inet_opt && inet_opt->opt.is_strictroute && fl4->daddr != rt->rt_gateway)
+ if (inet_opt && inet_opt->opt.is_strictroute && rt->rt_gateway)
goto no_route;
/* OK, we know where to send it, allocate and build IP header. */
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 2c2c35b..99af1f0 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -487,7 +487,7 @@
dev->stats.tx_fifo_errors++;
goto tx_error;
}
- dst = rt->rt_gateway;
+ dst = rt_nexthop(rt, old_iph->daddr);
}
rt = ip_route_output_ports(dev_net(dev), &fl4, NULL,
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
index 2f210c7..cbb6a1a 100644
--- a/net/ipv4/netfilter/ipt_MASQUERADE.c
+++ b/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -52,7 +52,7 @@
struct nf_nat_ipv4_range newrange;
const struct nf_nat_ipv4_multi_range_compat *mr;
const struct rtable *rt;
- __be32 newsrc;
+ __be32 newsrc, nh;
NF_CT_ASSERT(par->hooknum == NF_INET_POST_ROUTING);
@@ -70,7 +70,8 @@
mr = par->targinfo;
rt = skb_rtable(skb);
- newsrc = inet_select_addr(par->out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
+ nh = rt_nexthop(rt, ip_hdr(skb)->daddr);
+ newsrc = inet_select_addr(par->out, nh, RT_SCOPE_UNIVERSE);
if (!newsrc) {
pr_info("%s ate my IP address\n", par->out->name);
return NF_DROP;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 85d103f..d1d5796 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1085,8 +1085,9 @@
if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
else
- src = inet_select_addr(rt->dst.dev, rt->rt_gateway,
- RT_SCOPE_UNIVERSE);
+ src = inet_select_addr(rt->dst.dev,
+ rt_nexthop(rt, iph->daddr),
+ RT_SCOPE_UNIVERSE);
rcu_read_unlock();
}
memcpy(addr, &src, 4);
@@ -1132,7 +1133,7 @@
mtu = dst->dev->mtu;
if (unlikely(dst_metric_locked(dst, RTAX_MTU))) {
- if (rt->rt_gateway != 0 && mtu > 576)
+ if (rt->rt_gateway && mtu > 576)
mtu = 576;
}
@@ -1274,7 +1275,7 @@
rth->rt_iif = dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
- rth->rt_gateway = daddr;
+ rth->rt_gateway = 0;
rth->fi = NULL;
if (our) {
rth->dst.input= ip_local_deliver;
@@ -1392,7 +1393,7 @@
rth->rt_iif = in_dev->dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
- rth->rt_gateway = daddr;
+ rth->rt_gateway = 0;
rth->fi = NULL;
rth->dst.input = ip_forward;
@@ -1557,7 +1558,7 @@
rth->rt_iif = dev->ifindex;
rth->rt_oif = 0;
rth->rt_pmtu = 0;
- rth->rt_gateway = daddr;
+ rth->rt_gateway = 0;
rth->fi = NULL;
if (res.type == RTN_UNREACHABLE) {
rth->dst.input= ip_error;
@@ -1707,7 +1708,7 @@
rth->rt_iif = orig_oif ? : dev_out->ifindex;
rth->rt_oif = orig_oif;
rth->rt_pmtu = 0;
- rth->rt_gateway = fl4->daddr;
+ rth->rt_gateway = 0;
rth->fi = NULL;
RT_CACHE_STAT_INC(out_slow_tot);
@@ -2070,7 +2071,7 @@
if (nla_put_be32(skb, RTA_PREFSRC, fl4->saddr))
goto nla_put_failure;
}
- if (fl4->daddr != rt->rt_gateway &&
+ if (rt->rt_gateway &&
nla_put_be32(skb, RTA_GATEWAY, rt->rt_gateway))
goto nla_put_failure;
