[PATCH] 2.6.22.6 NETWORKING [IPV4]: Always use source addr in skb to reply packet

From: lepton
Date: Mon Sep 17 2007 - 22:17:25 EST


Hi,
In some situation, icmp_reply and ip_send_reply will send
out packet with the wrong source addr, the following patch
will fix this.

I don't understand why we must use rt->rt_src in the current
code, if this is a wrong fix, please correct me.

Signed-off-by: Lepton Wu <ytht.net@xxxxxxxxx>

diff -X linux-2.6.22.6/Documentation/dontdiff -pru linux-2.6.22.6/net/ipv4/icmp.c linux-2.6.22.6-lepton/net/ipv4/icmp.c
--- linux-2.6.22.6/net/ipv4/icmp.c 2007-09-14 17:41:18.000000000 +0800
+++ linux-2.6.22.6-lepton/net/ipv4/icmp.c 2007-09-18 09:57:30.000000000 +0800
@@ -382,6 +382,7 @@ static void icmp_reply(struct icmp_bxm *
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
__be32 daddr;
+ struct iphdr *ip = ip_hdr(skb);

if (ip_options_echo(&icmp_param->replyopts, skb))
return;
@@ -393,7 +394,7 @@ static void icmp_reply(struct icmp_bxm *
icmp_out_count(icmp_param->data.icmph.type);

inet->tos = ip_hdr(skb)->tos;
- daddr = ipc.addr = rt->rt_src;
+ daddr = ipc.addr = ip->saddr;
ipc.opt = NULL;
if (icmp_param->replyopts.optlen) {
ipc.opt = &icmp_param->replyopts;
diff -X linux-2.6.22.6/Documentation/dontdiff -pru linux-2.6.22.6/net/ipv4/ip_output.c linux-2.6.22.6-lepton/net/ipv4/ip_output.c
--- linux-2.6.22.6/net/ipv4/ip_output.c 2007-09-14 17:41:18.000000000 +0800
+++ linux-2.6.22.6-lepton/net/ipv4/ip_output.c 2007-09-18 09:57:13.000000000 +0800
@@ -1337,11 +1337,12 @@ void ip_send_reply(struct sock *sk, stru
struct ipcm_cookie ipc;
__be32 daddr;
struct rtable *rt = (struct rtable*)skb->dst;
+ struct iphdr *ip = ip_hdr(skb);

if (ip_options_echo(&replyopts.opt, skb))
return;

- daddr = ipc.addr = rt->rt_src;
+ daddr = ipc.addr = ip->saddr;
ipc.opt = NULL;

if (replyopts.opt.optlen) {
-
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