ipv6: Store Router Alert option in IP6CB directly.

Router Alert option is very small and we can store the value
itself in the skb.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 8 insertions, 5 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 304a9f46b578..e971e3742172 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -84,7 +84,7 @@ static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb)
 
 struct inet6_skb_parm {
         int                     iif;
-        __u16                   ra;
+        __be16                  ra;
         __u16                   hop;
         __u16                   dst0;
         __u16                   srcrt;
@@ -100,6 +100,7 @@ struct inet6_skb_parm {
 #define IP6SKB_XFRM_TRANSFORMED 1
 #define IP6SKB_FORWARDED        2
 #define IP6SKB_REROUTED         4
+#define IP6SKB_ROUTERALERT      8
 };
 
 #define IP6CB(skb)      ((struct inet6_skb_parm*)((skb)->cb))
diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 5a2991cf0251..4bda4cf5b0f5 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -63,6 +63,8 @@ struct ipv6_opt_hdr {
 #define ipv6_destopt_hdr ipv6_opt_hdr
 #define ipv6_hopopt_hdr  ipv6_opt_hdr
 
+/* Router Alert option values (RFC2711) */
+#define IPV6_OPT_ROUTERALERT_MLD        0x0000  /* MLD(RFC2710) */
 
 /*
  *      routing header type 0 (used in cmsghdr struct)
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 473f628f9f20..07a7d65a7cb6 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -553,7 +553,8 @@ static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
         const unsigned char *nh = skb_network_header(skb);
 
         if (nh[optoff + 1] == 2) {
-                IP6CB(skb)->ra = optoff;
+                IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
+                memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
                 return true;
         }
         LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 2ccd35ec3628..4ac5bf30e16a 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -280,9 +280,8 @@ int ip6_mc_input(struct sk_buff *skb)
                 struct inet6_skb_parm *opt = IP6CB(skb);
 
                 /* Check for MLD */
-                if (unlikely(opt->ra)) {
+                if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
                         /* Check if this is a mld message */
-                        u8 *ptr = skb_network_header(skb) + opt->ra;
                         u8 nexthdr = hdr->nexthdr;
                         __be16 frag_off;
                         int offset;
@@ -290,7 +289,7 @@ int ip6_mc_input(struct sk_buff *skb)
                         /* Check if the value of Router Alert
                          * is for MLD (0x0000).
                          */
-                        if ((ptr[2] | ptr[3]) == 0) {
+                        if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
                                 deliver = false;
 
                                 if (!ipv6_ext_hdr(nexthdr)) {