From d679c5324d9a87c6295f56c2dea52d5f68834f41 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 6 Sep 2012 20:37:06 +0000 Subject: igmp: avoid drop_monitor false positives igmp should call consume_skb() for all correctly processed packets, to avoid false dropwatch/drop_monitor false positives. Reported-by: Shawn Bohrer Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/igmp.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) (limited to 'net') diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 0b5580c69f2..3479b98a00a 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -815,14 +815,15 @@ static int igmp_marksources(struct ip_mc_list *pmc, int nsrcs, __be32 *srcs) return 1; } -static void igmp_heard_report(struct in_device *in_dev, __be32 group) +/* return true if packet was dropped */ +static bool igmp_heard_report(struct in_device *in_dev, __be32 group) { struct ip_mc_list *im; /* Timers are only set for non-local groups */ if (group == IGMP_ALL_HOSTS) - return; + return false; rcu_read_lock(); for_each_pmc_rcu(in_dev, im) { @@ -832,9 +833,11 @@ static void igmp_heard_report(struct in_device *in_dev, __be32 group) } } rcu_read_unlock(); + return false; } -static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, +/* return true if packet was dropped */ +static bool igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, int len) { struct igmphdr *ih = igmp_hdr(skb); @@ -866,7 +869,7 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, /* clear deleted report items */ igmpv3_clear_delrec(in_dev); } else if (len < 12) { - return; /* ignore bogus packet; freed by caller */ + return true; /* 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; @@ -883,13 +886,13 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, max_delay = 1; /* can't mod w/ 0 */ } else { /* v3 */ if (!pskb_may_pull(skb, sizeof(struct igmpv3_query))) - return; + return true; ih3 = igmpv3_query_hdr(skb); if (ih3->nsrcs) { if (!pskb_may_pull(skb, sizeof(struct igmpv3_query) + ntohs(ih3->nsrcs)*sizeof(__be32))) - return; + return true; ih3 = igmpv3_query_hdr(skb); } @@ -901,9 +904,9 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, in_dev->mr_qrv = ih3->qrv; if (!group) { /* general query */ if (ih3->nsrcs) - return; /* no sources allowed */ + return false; /* no sources allowed */ igmp_gq_start_timer(in_dev); - return; + return false; } /* mark sources to include, if group & source-specific */ mark = ih3->nsrcs != 0; @@ -939,6 +942,7 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb, igmp_mod_timer(im, max_delay); } rcu_read_unlock(); + return false; } /* called in rcu_read_lock() section */ @@ -948,6 +952,7 @@ int igmp_rcv(struct sk_buff *skb) struct igmphdr *ih; struct in_device *in_dev = __in_dev_get_rcu(skb->dev); int len = skb->len; + bool dropped = true; if (in_dev == NULL) goto drop; @@ -969,7 +974,7 @@ int igmp_rcv(struct sk_buff *skb) ih = igmp_hdr(skb); switch (ih->type) { case IGMP_HOST_MEMBERSHIP_QUERY: - igmp_heard_query(in_dev, skb, len); + dropped = igmp_heard_query(in_dev, skb, len); break; case IGMP_HOST_MEMBERSHIP_REPORT: case IGMPV2_HOST_MEMBERSHIP_REPORT: @@ -979,7 +984,7 @@ int igmp_rcv(struct sk_buff *skb) /* don't rely on MC router hearing unicast reports */ if (skb->pkt_type == PACKET_MULTICAST || skb->pkt_type == PACKET_BROADCAST) - igmp_heard_report(in_dev, ih->group); + dropped = igmp_heard_report(in_dev, ih->group); break; case IGMP_PIM: #ifdef CONFIG_IP_PIMSM_V1 @@ -997,7 +1002,10 @@ int igmp_rcv(struct sk_buff *skb) } drop: - kfree_skb(skb); + if (dropped) + kfree_skb(skb); + else + consume_skb(skb); return 0; } -- cgit v1.2.3