diff mbox series

[v2,net-next,4/8] net: ipv4: use kfree_skb_reason() in ip_rcv_core()

Message ID 20220127091308.91401-5-imagedong@tencent.com
State Handled Elsewhere
Delegated to: Pablo Neira
Headers show
Series net: use kfree_skb_reason() for ip/udp packet receive | expand

Commit Message

Menglong Dong Jan. 27, 2022, 9:13 a.m. UTC 
From: Menglong Dong <imagedong@tencent.com>

Replace kfree_skb() with kfree_skb_reason() in ip_rcv_core(). Three new
drop reasons are introduced:

SKB_DROP_REASON_OTHERHOST
SKB_DROP_REASON_IP_CSUM
SKB_DROP_REASON_IP_INHDR

Signed-off-by: Menglong Dong <imagedong@tencent.com>
---
v2:
- remove unrelated cleanup
- add document for introduced drop reasons
---
 include/linux/skbuff.h     |  9 +++++++++
 include/trace/events/skb.h |  3 +++
 net/ipv4/ip_input.c        | 11 +++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

Comments

David Ahern Jan. 27, 2022, 4:33 p.m. UTC | #1 
On 1/27/22 2:13 AM, menglong8.dong@gmail.com wrote:
> diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
> index 3a025c011971..7f64c5432cba 100644
> --- a/net/ipv4/ip_input.c
> +++ b/net/ipv4/ip_input.c
> @@ -436,13 +436,18 @@ static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
>  static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
>  {
>  	const struct iphdr *iph;
> +	int drop_reason;
>  	u32 len;
>  
> +	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
> +
>  	/* When the interface is in promisc. mode, drop all the crap
>  	 * that it receives, do not try to analyse it.
>  	 */
> -	if (skb->pkt_type == PACKET_OTHERHOST)
> +	if (skb->pkt_type == PACKET_OTHERHOST) {
> +		drop_reason = SKB_DROP_REASON_OTHERHOST;
>  		goto drop;
> +	}
>  
>  	__IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
>  
> @@ -516,11 +521,13 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)

There's another path:
        len = ntohs(iph->tot_len);
        if (skb->len < len) {
                __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
                goto drop;
        } else if (len < (iph->ihl*4))
...

where reason = SKB_DROP_REASON_PKT_TOO_SMALL

rest looks ok to me.


>  	return skb;
>  
>  csum_error:
> +	drop_reason = SKB_DROP_REASON_IP_CSUM;
>  	__IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
>  inhdr_error:
> +	drop_reason = drop_reason ?: SKB_DROP_REASON_IP_INHDR;
>  	__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
>  drop:
> -	kfree_skb(skb);
> +	kfree_skb_reason(skb, drop_reason);
>  out:
>  	return NULL;
>  }
diff mbox series

Patch

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 786ea2c2334e..2e87da91424f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -321,6 +321,15 @@  enum skb_drop_reason {
 	SKB_DROP_REASON_SOCKET_FILTER,	/* dropped by socket filter */
 	SKB_DROP_REASON_UDP_CSUM,	/* UDP checksum error */
 	SKB_DROP_REASON_NETFILTER_DROP,	/* dropped by netfilter */
+	SKB_DROP_REASON_OTHERHOST,	/* packet don't belong to current
+					 * host (interface is in promisc
+					 * mode)
+					 */
+	SKB_DROP_REASON_IP_CSUM,	/* IP checksum error */
+	SKB_DROP_REASON_IP_INHDR,	/* there is something wrong with
+					 * IP header (see
+					 * IPSTATS_MIB_INHDRERRORS)
+					 */
 	SKB_DROP_REASON_MAX,
 };
 
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 3d89f7b09a43..f2b1778485f0 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -17,6 +17,9 @@ 
 	EM(SKB_DROP_REASON_SOCKET_FILTER, SOCKET_FILTER)	\
 	EM(SKB_DROP_REASON_UDP_CSUM, UDP_CSUM)			\
 	EM(SKB_DROP_REASON_NETFILTER_DROP, NETFILTER_DROP)	\
+	EM(SKB_DROP_REASON_OTHERHOST, OTHERHOST)		\
+	EM(SKB_DROP_REASON_IP_CSUM, IP_CSUM)			\
+	EM(SKB_DROP_REASON_IP_INHDR, IP_INHDR)			\
 	EMe(SKB_DROP_REASON_MAX, MAX)
 
 #undef EM
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 3a025c011971..7f64c5432cba 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -436,13 +436,18 @@  static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 {
 	const struct iphdr *iph;
+	int drop_reason;
 	u32 len;
 
+	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+
 	/* When the interface is in promisc. mode, drop all the crap
 	 * that it receives, do not try to analyse it.
 	 */
-	if (skb->pkt_type == PACKET_OTHERHOST)
+	if (skb->pkt_type == PACKET_OTHERHOST) {
+		drop_reason = SKB_DROP_REASON_OTHERHOST;
 		goto drop;
+	}
 
 	__IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
 
@@ -516,11 +521,13 @@  static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
 	return skb;
 
 csum_error:
+	drop_reason = SKB_DROP_REASON_IP_CSUM;
 	__IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
 inhdr_error:
+	drop_reason = drop_reason ?: SKB_DROP_REASON_IP_INHDR;
 	__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
 drop:
-	kfree_skb(skb);
+	kfree_skb_reason(skb, drop_reason);
 out:
 	return NULL;
 }