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/icmp.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/ipv4/icmp.c') diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index 49a74cc79dc..4bce5a2830a 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -95,6 +95,7 @@ #include #include #include +#include /* * Build xmit assembly blocks @@ -333,7 +334,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) struct flowi4 fl4; struct sock *sk; struct inet_sock *inet; - __be32 daddr; + __be32 daddr, saddr; if (ip_options_echo(&icmp_param->replyopts.opt.opt, skb)) return; @@ -347,6 +348,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) inet->tos = ip_hdr(skb)->tos; daddr = ipc.addr = ip_hdr(skb)->saddr; + saddr = fib_compute_spec_dst(skb); ipc.opt = NULL; ipc.tx_flags = 0; if (icmp_param->replyopts.opt.opt.optlen) { @@ -356,7 +358,7 @@ static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb) } memset(&fl4, 0, sizeof(fl4)); fl4.daddr = daddr; - fl4.saddr = rt->rt_spec_dst; + fl4.saddr = saddr; fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos); fl4.flowi4_proto = IPPROTO_ICMP; security_skb_classify_flow(skb, flowi4_to_flowi(&fl4)); -- cgit v1.2.3-70-g09d2