[Devel] [PATCH RHEL9 COMMIT] net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-162.6.1.vz9.18.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-162.6.1.vz9.18.2
------>
commit bd9fa552badc477898e9ab5095052131c7e0edec
Author: Menglong Dong <imagedong at tencent.com>
Date:   Tue Jan 3 17:38:59 2023 +0200

    net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()
    
    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 at tencent.com>
    Reviewed-by: David Ahern <dsahern at kernel.org>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    Acked-by: Nikolay Borisov <nborisov at suse.com>
    Signed-off-by: Nikolay Borisov <nikolay.borisov at virtuozzo.com>
    
    ======
    Patchset description:
    ms/net: Annotate skb free sites with reason
    
    This series backports most of the patches that add a reason to skb free sites.
    
    https://jira.sw.ru/browse/PSBM-143302
    
    Feature: net: improve verbosity of dropped packets reporting
---
 include/linux/skbuff.h     | 10 ++++++++++
 include/trace/events/skb.h |  3 +++
 net/ipv4/ip_input.c        | 14 ++++++++++----
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 3a6bc3932a70..bc067688b1e4 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -328,6 +328,16 @@ 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 c11dfc26bf14..f4aa403da950 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;
 }