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Subject[ 25/73] ipv4: Save nexthop address of LSRR/SSRR option to IPCB.
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Li Wei <lw@cn.fujitsu.com>

[ Upstream commit ac8a48106be49c422575ddc7531b776f8eb49610 ]

We can not update iph->daddr in ip_options_rcv_srr(), It is too early.
When some exception ocurred later (eg. in ip_forward() when goto
sr_failed) we need the ip header be identical to the original one as
ICMP need it.

Add a field 'nexthop' in struct ip_options to save nexthop of LSRR
or SSRR option.

Signed-off-by: Li Wei <lw@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/inet_sock.h | 2 ++
net/ipv4/ip_forward.c | 2 +-
net/ipv4/ip_options.c | 5 +++--
3 files changed, 6 insertions(+), 3 deletions(-)

--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -31,6 +31,7 @@
/** struct ip_options - IP Options
*
* @faddr - Saved first hop address
+ * @nexthop - Saved nexthop address in LSRR and SSRR
* @is_data - Options in __data, rather than skb
* @is_strictroute - Strict source route
* @srr_is_hit - Packet destination addr was our one
@@ -41,6 +42,7 @@
*/
struct ip_options {
__be32 faddr;
+ __be32 nexthop;
unsigned char optlen;
unsigned char srr;
unsigned char rr;
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -84,7 +84,7 @@ int ip_forward(struct sk_buff *skb)

rt = skb_rtable(skb);

- if (opt->is_strictroute && ip_hdr(skb)->daddr != rt->rt_gateway)
+ if (opt->is_strictroute && opt->nexthop != rt->rt_gateway)
goto sr_failed;

if (unlikely(skb->len > dst_mtu(&rt->dst) && !skb_is_gso(skb) &&
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -568,12 +568,13 @@ void ip_forward_options(struct sk_buff *
) {
if (srrptr + 3 > srrspace)
break;
- if (memcmp(&ip_hdr(skb)->daddr, &optptr[srrptr-1], 4) == 0)
+ if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
break;
}
if (srrptr + 3 <= srrspace) {
opt->is_changed = 1;
ip_rt_get_source(&optptr[srrptr-1], skb, rt);
+ ip_hdr(skb)->daddr = opt->nexthop;
optptr[2] = srrptr+4;
} else if (net_ratelimit())
printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
@@ -640,7 +641,7 @@ int ip_options_rcv_srr(struct sk_buff *s
}
if (srrptr <= srrspace) {
opt->srr_is_hit = 1;
- iph->daddr = nexthop;
+ opt->nexthop = nexthop;
opt->is_changed = 1;
}
return 0;



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