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>
diff --git a/net/ipv4/ip_options.c b/net/ipv4/ip_options.c
index 708b994..766dfe56 100644
--- a/net/ipv4/ip_options.c
+++ b/net/ipv4/ip_options.c
@@ -27,6 +27,7 @@
#include <net/icmp.h>
#include <net/route.h>
#include <net/cipso_ipv4.h>
+#include <net/ip_fib.h>
/*
* Write options to IP header, record destination address to
@@ -104,7 +105,7 @@
sptr = skb_network_header(skb);
dptr = dopt->__data;
- daddr = skb_rtable(skb)->rt_spec_dst;
+ daddr = fib_compute_spec_dst(skb);
if (sopt->rr) {
optlen = sptr[sopt->rr+1];
@@ -250,15 +251,14 @@
int ip_options_compile(struct net *net,
struct ip_options *opt, struct sk_buff *skb)
{
- int l;
- unsigned char *iph;
- unsigned char *optptr;
- int optlen;
+ __be32 spec_dst = (__force __be32) 0;
unsigned char *pp_ptr = NULL;
- struct rtable *rt = NULL;
+ unsigned char *optptr;
+ unsigned char *iph;
+ int optlen, l;
if (skb != NULL) {
- rt = skb_rtable(skb);
+ spec_dst = fib_compute_spec_dst(skb);
optptr = (unsigned char *)&(ip_hdr(skb)[1]);
} else
optptr = opt->__data;
@@ -330,8 +330,8 @@
pp_ptr = optptr + 2;
goto error;
}
- if (rt) {
- memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
+ if (skb) {
+ memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
opt->is_changed = 1;
}
optptr[2] += 4;
@@ -372,8 +372,8 @@
goto error;
}
opt->ts = optptr - iph;
- if (rt) {
- memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
+ if (skb) {
+ memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
timeptr = &optptr[optptr[2]+3];
}
opt->ts_needaddr = 1;