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.da...@alliedtelesis.co.nz>
---
include/uapi/linux/mroute.h | 4 ++--
net/ipv4/ipmr.c | 8 ++++++--
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/include/uapi/linux/mroute.h b/include/uapi/linux/mroute.h
index 918f1ef32ffe..1a42f5f9b31b 100644
--- 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 19b2f586319b..4809318f591b 100644
--- 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));
--
2.28.0
