From: David Ahern <dsahern@gmail•com>
To: netdev@vger•kernel.org, borkmann@iogearbox•net, ast@kernel•org
Cc: davem@davemloft•net, David Ahern <dsahern@gmail•com>
Subject: [PATCH bpf-next 2/3] net/ipv6: Add helper to return path MTU based on fib result
Date: Thu, 17 May 2018 09:09:29 -0700 [thread overview]
Message-ID: <20180517160930.25076-3-dsahern@gmail.com> (raw)
In-Reply-To: <20180517160930.25076-1-dsahern@gmail.com>
Determine path MTU from a FIB lookup result. Logic is based on
ip6_dst_mtu_forward plus lookup of nexthop exception.
Signed-off-by: David Ahern <dsahern@gmail•com>
---
include/net/ip6_fib.h | 6 ++++++
include/net/ip6_route.h | 3 +++
net/ipv6/route.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 57 insertions(+)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index cc70f6da8462..7897efe80727 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -412,6 +412,12 @@ static inline struct net_device *fib6_info_nh_dev(const struct fib6_info *f6i)
return f6i->fib6_nh.nh_dev;
}
+static inline
+struct lwtunnel_state *fib6_info_nh_lwt(const struct fib6_info *f6i)
+{
+ return f6i->fib6_nh.nh_lwtstate;
+}
+
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int flags);
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 4cf1ef935ed9..7b9c82de11cc 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -300,6 +300,9 @@ static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)
return mtu;
}
+u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr);
+
struct neighbour *ip6_neigh_lookup(const struct in6_addr *gw,
struct net_device *dev, struct sk_buff *skb,
const void *daddr);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index cc24ed3bc334..a9b2c8e06404 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2603,6 +2603,54 @@ static unsigned int ip6_mtu(const struct dst_entry *dst)
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}
+/* MTU selection:
+ * 1. mtu on route is locked - use it
+ * 2. mtu from nexthop exception
+ * 3. mtu from egress device
+ *
+ * based on ip6_dst_mtu_forward and exception logic of
+ * rt6_find_cached_rt; called with rcu_read_lock
+ */
+u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr)
+{
+ struct rt6_exception_bucket *bucket;
+ struct rt6_exception *rt6_ex;
+ struct in6_addr *src_key;
+ struct inet6_dev *idev;
+ u32 mtu = 0;
+
+ if (unlikely(fib6_metric_locked(f6i, RTAX_MTU))) {
+ mtu = f6i->fib6_pmtu;
+ if (mtu)
+ goto out;
+ }
+
+ src_key = NULL;
+#ifdef CONFIG_IPV6_SUBTREES
+ if (f6i->fib6_src.plen)
+ src_key = saddr;
+#endif
+
+ bucket = rcu_dereference(f6i->rt6i_exception_bucket);
+ rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
+ if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
+ mtu = dst_metric_raw(&rt6_ex->rt6i->dst, RTAX_MTU);
+
+ if (likely(!mtu)) {
+ struct net_device *dev = fib6_info_nh_dev(f6i);
+
+ mtu = IPV6_MIN_MTU;
+ idev = __in6_dev_get(dev);
+ if (idev && idev->cnf.mtu6 > mtu)
+ mtu = idev->cnf.mtu6;
+ }
+
+ mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+out:
+ return mtu - lwtunnel_headroom(fib6_info_nh_lwt(f6i), mtu);
+}
+
struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
struct flowi6 *fl6)
{
--
2.11.0
next prev parent reply other threads:[~2018-05-17 16:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 16:09 [PATCH bpf-next 0/3] bpf: Add MTU check to fib lookup helper David Ahern
2018-05-17 16:09 ` [PATCH bpf-next 1/3] net/ipv4: Add helper to return path MTU based on fib result David Ahern
2018-05-17 16:09 ` David Ahern [this message]
2018-05-17 16:09 ` [PATCH bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper David Ahern
2018-05-17 22:22 ` Daniel Borkmann
2018-05-18 0:34 ` David Ahern
2018-05-18 14:01 ` Daniel Borkmann
2018-05-20 6:41 ` kbuild test robot
2018-05-20 11:14 ` kbuild test robot
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