[PATCH 5.15 081/201] net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()

Greg Kroah-Hartman
2022-07-27T17:09:02Z

From: Menglong Dong <imagedong@tencent.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@tencent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.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