From 35ebf65e851c6d9731abc6362b189858eb59f4d3 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 28 Jun 2012 03:59:11 -0700 Subject: 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 --- net/ipv4/ip_sockglue.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'net/ipv4/ip_sockglue.c') diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index 0d11f234d615..de29f46f68b0 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -40,6 +40,7 @@ #if IS_ENABLED(CONFIG_IPV6) #include #endif +#include #include #include @@ -1019,8 +1020,8 @@ e_inval: * @sk: socket * @skb: buffer * - * To support IP_CMSG_PKTINFO option, we store rt_iif and rt_spec_dst - * in skb->cb[] before dst drop. + * To support IP_CMSG_PKTINFO option, we store rt_iif and specific + * destination in skb->cb[] before dst drop. * This way, receiver doesnt make cache line misses to read rtable. */ void ipv4_pktinfo_prepare(struct sk_buff *skb) @@ -1030,7 +1031,7 @@ void ipv4_pktinfo_prepare(struct sk_buff *skb) if (rt) { pktinfo->ipi_ifindex = rt->rt_iif; - pktinfo->ipi_spec_dst.s_addr = rt->rt_spec_dst; + pktinfo->ipi_spec_dst.s_addr = fib_compute_spec_dst(skb); } else { pktinfo->ipi_ifindex = 0; pktinfo->ipi_spec_dst.s_addr = 0; -- cgit v1.2.3