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authorDavid S. Miller <davem@davemloft.net>2012-06-28 14:59:11 +0400
committerDavid S. Miller <davem@davemloft.net>2012-06-28 14:59:11 +0400
commit35ebf65e851c6d9731abc6362b189858eb59f4d3 (patch)
tree2e78c2c81bc72aeeb172484996cdff268f0111a2 /net/ipv4/ip_sockglue.c
parent70e7341673a47fb1525cfc7d6651cc98b5348928 (diff)
downloadlinux-35ebf65e851c6d9731abc6362b189858eb59f4d3.tar.xz
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>
Diffstat (limited to 'net/ipv4/ip_sockglue.c')
-rw-r--r--net/ipv4/ip_sockglue.c7
1 files changed, 4 insertions, 3 deletions
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 <net/transp_v6.h>
#endif
+#include <net/ip_fib.h>
#include <linux/errqueue.h>
#include <asm/uaccess.h>
@@ -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;