ipmr: Add high byte of VIF ID to igmpmsg

Use the unused3 byte in struct igmpmsg to hold the high 8 bits of the
VIF ID.

If using more than 255 IPv4 multicast interfaces it is necessary to have
access to a VIF ID for cache reports that is wider than 8 bits, the VIF
ID present in the igmpmsg reports sent to mroute_sk was only 8 bits wide
in the igmpmsg header.  Adding the high 8 bits of the 16 bit VIF ID in
the unused byte allows use of more than 255 IPv4 multicast interfaces.

Signed-off-by: Paul Davey <paul.davey@alliedtelesis.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/mroute.h b/include/uapi/linux/mroute.h
index 918f1ef..1a42f5f 100644 (file)
--- a/include/uapi/linux/mroute.h
+++ b/include/uapi/linux/mroute.h
@@ -113,8 +113,8 @@ struct igmpmsg {
        __u32 unused1,unused2;
        unsigned char im_msgtype;               /* What is this */
        unsigned char im_mbz;                   /* Must be zero */
-       unsigned char im_vif;                   /* Interface (this ought to be a vifi_t!) */
-       unsigned char unused3;
+       unsigned char im_vif;                   /* Low 8 bits of Interface */
+       unsigned char im_vif_hi;                /* High 8 bits of Interface */
        struct in_addr im_src,im_dst;
 };
 

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 19b2f58..4809318 100644 (file)
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1038,10 +1038,13 @@ static int ipmr_cache_report(struct mr_table *mrt,
                memcpy(msg, skb_network_header(pkt), sizeof(struct iphdr));
                msg->im_msgtype = assert;
                msg->im_mbz = 0;
-               if (assert == IGMPMSG_WRVIFWHOLE)
+               if (assert == IGMPMSG_WRVIFWHOLE) {
                        msg->im_vif = vifi;
-               else
+                       msg->im_vif_hi = vifi >> 8;
+               } else {
                        msg->im_vif = mrt->mroute_reg_vif_num;
+                       msg->im_vif_hi = mrt->mroute_reg_vif_num >> 8;
+               }
                ip_hdr(skb)->ihl = sizeof(struct iphdr) >> 2;
                ip_hdr(skb)->tot_len = htons(ntohs(ip_hdr(pkt)->tot_len) +
                                             sizeof(struct iphdr));
@@ -1054,6 +1057,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
                ip_hdr(skb)->protocol = 0;
                msg = (struct igmpmsg *)skb_network_header(skb);
                msg->im_vif = vifi;
+               msg->im_vif_hi = vifi >> 8;
                skb_dst_set(skb, dst_clone(skb_dst(pkt)));
                /* Add our header */
                igmp = skb_put(skb, sizeof(struct igmphdr));