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Subject[PATCH net-next 3/6] net: ipv4: use kfree_skb_reason() in ip_rcv_finish_core()
Date
From: Menglong Dong <imagedong@tencent.com>

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

SKB_DROP_REASON_IP_ROUTE_INPUT
SKB_DROP_REASON_IP_RPFILTER
SKB_DROP_REASON_EARLY_DEMUX
SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
include/linux/skbuff.h | 4 ++++
include/trace/events/skb.h | 5 +++++
net/ipv4/ip_input.c | 22 ++++++++++++++++------
3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index f3028028b83e..8942d32c0657 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -324,6 +324,10 @@ enum skb_drop_reason {
SKB_DROP_REASON_OTHERHOST,
SKB_DROP_REASON_IP_CSUM,
SKB_DROP_REASON_IP_INHDR,
+ SKB_DROP_REASON_IP_ROUTE_INPUT,
+ SKB_DROP_REASON_IP_RPFILTER,
+ SKB_DROP_REASON_EARLY_DEMUX,
+ SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST,
SKB_DROP_REASON_MAX,
};

diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index d1b0d9690e62..1dcdcc92cf08 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -20,6 +20,11 @@
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_ROUTE_INPUT, IP_ROUTE_INPUT) \
+ EM(SKB_DROP_REASON_IP_RPFILTER, IP_RPFILTER) \
+ EM(SKB_DROP_REASON_EARLY_DEMUX, EARLY_DEMUX) \
+ 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 ab9bee4bbf0a..77bb9ddc441b 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,
@@ -339,8 +341,10 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
if (ipprot && (edemux = READ_ONCE(ipprot->early_demux))) {
err = INDIRECT_CALL_2(edemux, tcp_v4_early_demux,
udp_v4_early_demux, skb);
- if (unlikely(err))
+ if (unlikely(err)) {
+ drop_reason = SKB_DROP_REASON_EARLY_DEMUX;
goto drop_error;
+ }
/* must reload iph, skb->head might have changed */
iph = ip_hdr(skb);
}
@@ -353,8 +357,10 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
if (!skb_valid_dst(skb)) {
err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
iph->tos, dev);
- if (unlikely(err))
+ if (unlikely(err)) {
+ drop_reason = SKB_DROP_REASON_IP_ROUTE_INPUT;
goto drop_error;
+ }
}

#ifdef CONFIG_IP_ROUTE_CLASSID
@@ -396,19 +402,23 @@ 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;
}

--
2.34.1
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