diff options
| author | David S. Miller <davem@davemloft.net> | 2012-06-28 03:59:11 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-06-28 03:59:11 -0700 |
| commit | 35ebf65e851c6d9731abc6362b189858eb59f4d3 (patch) | |
| tree | 2e78c2c81bc72aeeb172484996cdff268f0111a2 /net/ipv4/fib_frontend.c | |
| parent | 70e7341673a47fb1525cfc7d6651cc98b5348928 (diff) | |
ipv4: Create and use fib_compute_spec_dst() helper.
The specific destination is the host we direct unicast replies to.
Usually this is the original packet source address, but if we are
responding to a multicast or broadcast packet we have to use something
different.
Specifically we must use the source address we would use if we were to
send a packet to the unicast source of the original packet.
The routing cache precomputes this value, but we want to remove that
precomputation because it creates a hard dependency on the expensive
rpfilter source address validation which we'd like to make cheaper.
There are only three places where this matters:
1) ICMP replies.
2) pktinfo CMSG
3) IP options
Now there will be no real users of rt->rt_spec_dst and we can simply
remove it altogether.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_frontend.c')
| -rw-r--r-- | net/ipv4/fib_frontend.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 3854411fa37c..451939b60c54 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -180,6 +180,35 @@ unsigned int inet_dev_addr_type(struct net *net, const struct net_device *dev, } EXPORT_SYMBOL(inet_dev_addr_type); +__be32 fib_compute_spec_dst(struct sk_buff *skb) +{ + struct net_device *dev = skb->dev; + struct in_device *in_dev; + struct fib_result res; + struct flowi4 fl4; + struct net *net; + + if (skb->pkt_type != PACKET_BROADCAST && + skb->pkt_type != PACKET_MULTICAST) + return ip_hdr(skb)->daddr; + + in_dev = __in_dev_get_rcu(dev); + BUG_ON(!in_dev); + fl4.flowi4_oif = 0; + fl4.flowi4_iif = 0; + fl4.daddr = ip_hdr(skb)->saddr; + fl4.saddr = ip_hdr(skb)->daddr; + fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); + fl4.flowi4_scope = RT_SCOPE_UNIVERSE; + fl4.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0; + + net = dev_net(dev); + if (!fib_lookup(net, &fl4, &res)) + return FIB_RES_PREFSRC(net, res); + else + return inet_select_addr(dev, 0, RT_SCOPE_UNIVERSE); +} + /* Given (packet source, input interface) and optional (dst, oif, tos): * - (main) check, that source is valid i.e. not broadcast or our local * address. |