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authorDavid Ahern <dsahern@gmail.com>2019-04-05 16:30:34 -0700
committerDavid S. Miller <davem@davemloft.net>2019-04-08 15:22:41 -0700
commit5c9f7c1dfc2e0776551ef1ceb335187c6698d1ff (patch)
treee32182b2068ba4ec08eb046acf973a9738a84820 /net/ipv4
parent0353f28231c79416191326810e7fe656b69c63b7 (diff)
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ipv4: Add helpers for neigh lookup for nexthop
A common theme in the output path is looking up a neigh entry for a nexthop, either the gateway in an rtable or a fallback to the daddr in the skb: nexthop = (__force u32)rt_nexthop(rt, ip_hdr(skb)->daddr); neigh = __ipv4_neigh_lookup_noref(dev, nexthop); if (unlikely(!neigh)) neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); To allow the nexthop to be an IPv6 address we need to consider the family of the nexthop and then call __ipv{4,6}_neigh_lookup_noref based on it. To make this simpler, add a ip_neigh_gw4 helper similar to ip_neigh_gw6 added in an earlier patch which handles: neigh = __ipv4_neigh_lookup_noref(dev, nexthop); if (unlikely(!neigh)) neigh = __neigh_create(&arp_tbl, &nexthop, dev, false); And then add a second one, ip_neigh_for_gw, that calls either ip_neigh_gw4 or ip_neigh_gw6 based on the address family of the gateway. Update the output paths in the VRF driver and core v4 code to use ip_neigh_for_gw simplifying the family based lookup and making both ready for a v6 nexthop. ipv4_neigh_lookup has a different need - the potential to resolve a passed in address in addition to any gateway in the rtable or skb. Since this is a one-off, add ip_neigh_gw4 and ip_neigh_gw6 diectly. The difference between __neigh_create used by the helpers and neigh_create called by ipv4_neigh_lookup is taking a refcount, so add rcu_read_lock_bh and bump the refcnt on the neigh entry. Signed-off-by: David Ahern <dsahern@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_output.c11
-rw-r--r--net/ipv4/route.c29
2 files changed, 23 insertions, 17 deletions
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index cca4892b8cb2..4e42c1974ba2 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -188,7 +188,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
struct net_device *dev = dst->dev;
unsigned int hh_len = LL_RESERVED_SPACE(dev);
struct neighbour *neigh;
- u32 nexthop;
+ bool is_v6gw = false;
if (rt->rt_type == RTN_MULTICAST) {
IP_UPD_PO_STATS(net, IPSTATS_MIB_OUTMCAST, skb->len);
@@ -218,16 +218,13 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s
}
rcu_read_lock_bh();
- nexthop = (__force u32) rt_nexthop(rt, ip_hdr(skb)->daddr);
- neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
- if (unlikely(!neigh))
- neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
+ neigh = ip_neigh_for_gw(rt, skb, &is_v6gw);
if (!IS_ERR(neigh)) {
int res;
sock_confirm_neigh(skb, neigh);
- res = neigh_output(neigh, skb, false);
-
+ /* if crossing protocols, can not use the cached header */
+ res = neigh_output(neigh, skb, is_v6gw);
rcu_read_unlock_bh();
return res;
}
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 6e58acf0a87b..32ecb4c1c7e3 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -436,18 +436,27 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst,
{
const struct rtable *rt = container_of(dst, struct rtable, dst);
struct net_device *dev = dst->dev;
- const __be32 *pkey = daddr;
struct neighbour *n;
- if (rt->rt_gw_family == AF_INET)
- pkey = (const __be32 *) &rt->rt_gw4;
- else if (skb)
- pkey = &ip_hdr(skb)->daddr;
-
- n = __ipv4_neigh_lookup(dev, *(__force u32 *)pkey);
- if (n)
- return n;
- return neigh_create(&arp_tbl, pkey, dev);
+ rcu_read_lock_bh();
+
+ if (likely(rt->rt_gw_family == AF_INET)) {
+ n = ip_neigh_gw4(dev, rt->rt_gw4);
+ } else if (rt->rt_gw_family == AF_INET6) {
+ n = ip_neigh_gw6(dev, &rt->rt_gw6);
+ } else {
+ __be32 pkey;
+
+ pkey = skb ? ip_hdr(skb)->daddr : *((__be32 *) daddr);
+ n = ip_neigh_gw4(dev, pkey);
+ }
+
+ if (n && !refcount_inc_not_zero(&n->refcnt))
+ n = NULL;
+
+ rcu_read_unlock_bh();
+
+ return n;
}
static void ipv4_confirm_neigh(const struct dst_entry *dst, const void *daddr)