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Date: Fri, 07 Sep 2012 08:37:06 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: Shawn Bohrer <sbohrer@...advisors.com>,
netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] igmp: avoid drop_monitor false positives
From: Eric Dumazet <edumazet@...gle.com>
igmp should call consume_skb() for all correctly processed packets,
to avoid false dropwatch/drop_monitor false positives.
Reported-by: Shawn Bohrer <sbohrer@...advisors.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv4/igmp.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 0b5580c..3479b98 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;
}
--
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