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Date: Fri, 5 Apr 2019 16:30:34 -0700
From: David Ahern <dsahern@...nel.org>
To: davem@...emloft.net, netdev@...r.kernel.org
Cc: idosch@...lanox.com, jiri@...lanox.com,
David Ahern <dsahern@...il.com>
Subject: [PATCH v2 net-next 11/18] ipv4: Add helpers for neigh lookup for nexthop
From: David Ahern <dsahern@...il.com>
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@...il.com>
---
drivers/net/vrf.c | 10 ++++------
include/net/route.h | 32 ++++++++++++++++++++++++++++++++
net/ipv4/ip_output.c | 11 ++++-------
net/ipv4/route.c | 29 +++++++++++++++++++----------
4 files changed, 59 insertions(+), 23 deletions(-)
diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index fd1337736aa0..18d752ae554f 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -549,7 +549,7 @@ static int vrf_finish_output(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;
int ret = -EINVAL;
nf_reset(skb);
@@ -572,13 +572,11 @@ static int vrf_finish_output(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)) {
sock_confirm_neigh(skb, neigh);
- ret = neigh_output(neigh, skb, false);
+ /* if crossing protocols, can not use the cached header */
+ ret = neigh_output(neigh, skb, is_v6gw);
rcu_read_unlock_bh();
return ret;
}
diff --git a/include/net/route.h b/include/net/route.h
index 5d28a2509b58..96f6c9ae33c2 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -29,6 +29,8 @@
#include <net/flow.h>
#include <net/inet_sock.h>
#include <net/ip_fib.h>
+#include <net/arp.h>
+#include <net/ndisc.h>
#include <linux/in_route.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
@@ -350,4 +352,34 @@ static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
return hoplimit;
}
+static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
+ __be32 daddr)
+{
+ struct neighbour *neigh;
+
+ neigh = __ipv4_neigh_lookup_noref(dev, daddr);
+ if (unlikely(!neigh))
+ neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
+
+ return neigh;
+}
+
+static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
+ struct sk_buff *skb,
+ bool *is_v6gw)
+{
+ struct net_device *dev = rt->dst.dev;
+ struct neighbour *neigh;
+
+ if (likely(rt->rt_gw_family == AF_INET)) {
+ neigh = ip_neigh_gw4(dev, rt->rt_gw4);
+ } else if (rt->rt_gw_family == AF_INET6) {
+ neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
+ *is_v6gw = true;
+ } else {
+ neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
+ }
+ return neigh;
+}
+
#endif /* _ROUTE_H */
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)
--
2.11.0
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