linux-kernel - [PATCH 5.15 081/201] net: ipv4: use kfree_skb_reason() in ip_rcv_finish

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Date:   Wed, 27 Jul 2022 18:09:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Menglong Dong <imagedong@...cent.com>,
        David Ahern <dsahern@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 081/201] net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()

From: Menglong Dong <imagedong@...cent.com>

[ Upstream commit c1f166d1f7eef212096a98b22f5acf92f9af353d ]

Replace kfree_skb() with kfree_skb_reason() in ip_rcv_finish_core(),
following drop reasons are introduced:

SKB_DROP_REASON_IP_RPFILTER
SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST

Signed-off-by: Menglong Dong <imagedong@...cent.com>
Reviewed-by: David Ahern <dsahern@...nel.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/skbuff.h     |  9 +++++++++
 include/trace/events/skb.h |  3 +++
 net/ipv4/ip_input.c        | 14 ++++++++++----
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 514fb8074f78..cbd719e5329a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -327,6 +327,15 @@ enum skb_drop_reason {
 					 * IP header (see
 					 * IPSTATS_MIB_INHDRERRORS)
 					 */
+	SKB_DROP_REASON_IP_RPFILTER,	/* IP rpfilter validate failed.
+					 * see the document for rp_filter
+					 * in ip-sysctl.rst for more
+					 * information
+					 */
+	SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST, /* destination address of L2
+						  * is multicast, but L3 is
+						  * unicast.
+						  */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index f2b1778485f0..485a1d3034a4 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -20,6 +20,9 @@
 	EM(SKB_DROP_REASON_OTHERHOST, OTHERHOST)		\
 	EM(SKB_DROP_REASON_IP_CSUM, IP_CSUM)			\
 	EM(SKB_DROP_REASON_IP_INHDR, IP_INHDR)			\
+	EM(SKB_DROP_REASON_IP_RPFILTER, IP_RPFILTER)		\
+	EM(SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST,		\
+	   UNICAST_IN_L2_MULTICAST)				\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 7be18de32e16..d5222c0fa87c 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -318,8 +318,10 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
 {
 	const struct iphdr *iph = ip_hdr(skb);
 	int (*edemux)(struct sk_buff *skb);
+	int err, drop_reason;
 	struct rtable *rt;
-	int err;
+
+	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
 
 	if (ip_can_use_hint(skb, iph, hint)) {
 		err = ip_route_use_hint(skb, iph->daddr, iph->saddr, iph->tos,
@@ -396,19 +398,23 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
 		 * so-called "hole-196" attack) so do it for both.
 		 */
 		if (in_dev &&
-		    IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST))
+		    IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) {
+			drop_reason = SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST;
 			goto drop;
+		}
 	}
 
 	return NET_RX_SUCCESS;
 
 drop:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, drop_reason);
 	return NET_RX_DROP;
 
 drop_error:
-	if (err == -EXDEV)
+	if (err == -EXDEV) {
+		drop_reason = SKB_DROP_REASON_IP_RPFILTER;
 		__NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
+	}
 	goto drop;
 }
 
-- 
2.35.1