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ipv4: correct IGMP behavior on v3 query during v2-compatibility mode 

A recent patch to allow IGMPv2 responses to IGMPv3 queries
bypasses length checks for valid query lengths, incorrectly
resets the v2_seen timer, and does not support IGMPv1.

The following patch responds with a v2 report as required
by IGMPv2 while correcting the other problems introduced
by the patch.

Signed-Off-By: David L Stevens <dlstevens@us.ibm.com>

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Stevens 2010-09-30 14:29:40 +00:00 committed by David S. Miller
parent 10ccff62bd
commit 5b7c840667
1 changed files with 13 additions and 1 deletions
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14
net/ipv4/igmp.c
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@ -834,7 +834,7 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
int mark = 0;
if (len == 8 || IGMP_V2_SEEN(in_dev)) {
if (len == 8) {
if (ih->code == 0) {
/* Alas, old v1 router presents here. */
@ -856,6 +856,18 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
igmpv3_clear_delrec(in_dev);
} else if (len < 12) {
return; /* ignore bogus packet; freed by caller */
} else if (IGMP_V1_SEEN(in_dev)) {
/* This is a v3 query with v1 queriers present */
max_delay = IGMP_Query_Response_Interval;
group = 0;
} else if (IGMP_V2_SEEN(in_dev)) {
/* this is a v3 query with v2 queriers present;
* Interpretation of the max_delay code is problematic here.
* A real v2 host would use ih_code directly, while v3 has a
* different encoding. We use the v3 encoding as more likely
* to be intended in a v3 query.
*/
max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
} else { /* v3 */
if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)))
return;