2019-10-21 20:11:29

by Matteo Croce

Subject: [PATCH net-next 2/4] flow_dissector: skip the ICMP dissector for non ICMP packets

FLOW_DISSECTOR_KEY_ICMP is checked for every packet, not only ICMP ones.
Even if the test overhead is probably negligible, move the
ICMP dissector code under the big 'switch(ip_proto)' so it gets called
only for ICMP packets.

Signed-off-by: Matteo Croce <[email protected]>
---
net/core/flow_dissector.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index affde70dad47..6443fac65ce8 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -203,6 +203,25 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
}
EXPORT_SYMBOL(__skb_flow_get_ports);

+/* If FLOW_DISSECTOR_KEY_ICMP is set, get the Type and Code from an ICMP packet
+ * using skb_flow_get_be16().
+ */
+static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
+ struct flow_dissector *flow_dissector,
+ void *target_container,
+ void *data, int thoff, int hlen)
+{
+ struct flow_dissector_key_icmp *key_icmp;
+
+ if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ICMP))
+ return;
+
+ key_icmp = skb_flow_dissector_target(flow_dissector,
+ FLOW_DISSECTOR_KEY_ICMP,
+ target_container);
+ key_icmp->icmp = skb_flow_get_be16(skb, thoff, data, hlen);
+}
+
void skb_flow_dissect_meta(const struct sk_buff *skb,
struct flow_dissector *flow_dissector,
void *target_container)
@@ -853,7 +872,6 @@ bool __skb_flow_dissect(const struct net *net,
struct flow_dissector_key_basic *key_basic;
struct flow_dissector_key_addrs *key_addrs;
struct flow_dissector_key_ports *key_ports;
- struct flow_dissector_key_icmp *key_icmp;
struct flow_dissector_key_tags *key_tags;
struct flow_dissector_key_vlan *key_vlan;
struct bpf_prog *attached = NULL;
@@ -1295,6 +1313,12 @@ bool __skb_flow_dissect(const struct net *net,
data, nhoff, hlen);
break;

+ case IPPROTO_ICMP:
+ case IPPROTO_ICMPV6:
+ __skb_flow_dissect_icmp(skb, flow_dissector, target_container,
+ data, nhoff, hlen);
+ break;
+
default:
break;
}
@@ -1308,14 +1332,6 @@ bool __skb_flow_dissect(const struct net *net,
data, hlen);
}

- if (dissector_uses_key(flow_dissector,
- FLOW_DISSECTOR_KEY_ICMP)) {
- key_icmp = skb_flow_dissector_target(flow_dissector,
- FLOW_DISSECTOR_KEY_ICMP,
- target_container);
- key_icmp->icmp = skb_flow_get_be16(skb, nhoff, data, hlen);
- }
-
/* Process result of IP proto processing */
switch (fdret) {
case FLOW_DISSECT_RET_PROTO_AGAIN:
--
2.21.0

2019-10-23 10:00:59

by Simon Horman

Subject: Re: [PATCH net-next 2/4] flow_dissector: skip the ICMP dissector for non ICMP packets

On Mon, Oct 21, 2019 at 10:09:46PM +0200, Matteo Croce wrote:
> FLOW_DISSECTOR_KEY_ICMP is checked for every packet, not only ICMP ones.
> Even if the test overhead is probably negligible, move the
> ICMP dissector code under the big 'switch(ip_proto)' so it gets called
> only for ICMP packets.
>
> Signed-off-by: Matteo Croce <[email protected]>

Reviewed-by: Simon Horman <[email protected]>

> ---
> net/core/flow_dissector.c | 34 +++++++++++++++++++++++++---------
> 1 file changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index affde70dad47..6443fac65ce8 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -203,6 +203,25 @@ __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
> }
> EXPORT_SYMBOL(__skb_flow_get_ports);
>
> +/* If FLOW_DISSECTOR_KEY_ICMP is set, get the Type and Code from an ICMP packet
> + * using skb_flow_get_be16().
> + */
> +static void __skb_flow_dissect_icmp(const struct sk_buff *skb,
> + struct flow_dissector *flow_dissector,
> + void *target_container,
> + void *data, int thoff, int hlen)
> +{
> + struct flow_dissector_key_icmp *key_icmp;
> +
> + if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ICMP))
> + return;
> +
> + key_icmp = skb_flow_dissector_target(flow_dissector,
> + FLOW_DISSECTOR_KEY_ICMP,
> + target_container);
> + key_icmp->icmp = skb_flow_get_be16(skb, thoff, data, hlen);
> +}
> +
> void skb_flow_dissect_meta(const struct sk_buff *skb,
> struct flow_dissector *flow_dissector,
> void *target_container)
> @@ -853,7 +872,6 @@ bool __skb_flow_dissect(const struct net *net,
> struct flow_dissector_key_basic *key_basic;
> struct flow_dissector_key_addrs *key_addrs;
> struct flow_dissector_key_ports *key_ports;
> - struct flow_dissector_key_icmp *key_icmp;
> struct flow_dissector_key_tags *key_tags;
> struct flow_dissector_key_vlan *key_vlan;
> struct bpf_prog *attached = NULL;
> @@ -1295,6 +1313,12 @@ bool __skb_flow_dissect(const struct net *net,
> data, nhoff, hlen);
> break;
>
> + case IPPROTO_ICMP:
> + case IPPROTO_ICMPV6:
> + __skb_flow_dissect_icmp(skb, flow_dissector, target_container,
> + data, nhoff, hlen);
> + break;
> +
> default:
> break;
> }
> @@ -1308,14 +1332,6 @@ bool __skb_flow_dissect(const struct net *net,
> data, hlen);
> }
>
> - if (dissector_uses_key(flow_dissector,
> - FLOW_DISSECTOR_KEY_ICMP)) {
> - key_icmp = skb_flow_dissector_target(flow_dissector,
> - FLOW_DISSECTOR_KEY_ICMP,
> - target_container);
> - key_icmp->icmp = skb_flow_get_be16(skb, nhoff, data, hlen);
> - }
> -
> /* Process result of IP proto processing */
> switch (fdret) {
> case FLOW_DISSECT_RET_PROTO_AGAIN:
> --
> 2.21.0
>