From 5b7c84066733c5dfb0e4016d939757b38de189e4 Mon Sep 17 00:00:00 2001 From: David Stevens Date: Thu, 30 Sep 2010 14:29:40 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/ipv4/igmp.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 1fdcacd36ce7..2a4bb76f2132 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -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; -- 2.39.2