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Message-ID: <20161205142734.GA5656@nanopsycho>
Date:   Mon, 5 Dec 2016 15:27:34 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Simon Horman <simon.horman@...ronome.com>
Cc:     Tom Herbert <tom@...bertland.com>,
        David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...lanox.com>
Subject: Re: [PATCH v2 net-next 1/2] flow dissector: ICMP support

Mon, Dec 05, 2016 at 03:23:16PM CET, simon.horman@...ronome.com wrote:
>On Sat, Dec 03, 2016 at 10:52:32AM -0800, Tom Herbert wrote:
>> On Sat, Dec 3, 2016 at 2:49 AM, Jiri Pirko <jiri@...nulli.us> wrote:
>> > Fri, Dec 02, 2016 at 09:31:41PM CET, simon.horman@...ronome.com wrote:
>> >>Allow dissection of ICMP(V6) type and code. This re-uses transport layer
>> >>port dissection code as although ICMP is not a transport protocol and their
>> >>type and code are not ports this allows sharing of both code and storage.
>> >>
>> >>Signed-off-by: Simon Horman <simon.horman@...ronome.com>
>
>...
>
>> > Digging into this a bit more. I think it would be much nice not to mix
>> > up l4 ports and icmp stuff.
>> >
>> > How about to have FLOW_DISSECTOR_KEY_ICMP
>> > and
>> > struct flow_dissector_key_icmp {
>> >         u8 type;
>> >         u8 code;
>> > };
>> >
>> > The you can make this structure and struct flow_dissector_key_ports into
>> > an union in struct flow_keys.
>> >
>> > Looks much cleaner to me.
>
>Hi Jiri,
>
>I wondered about that too. The main reason that I didn't do this the first
>time around is that I wasn't sure what to do to differentiate between ports
>and icmp in fl_init_dissector() given that using a union would could to
>mask bits being set in both if they are set in either.
>
>I've taken a stab at addressing that below along with implementing your
>suggestion. If the treatment in fl_init_dissector() is acceptable
>perhaps something similar should be done for FLOW_DISSECTOR_KEY_IPV[46]_ADDRS

Looks fine.

>too?
>
>> I agree, this patch adds to many conditionals into the fast path for
>> ICMP handling. Neither is there much point in using type and code as
>> input to the packet hash.
>
>Hi Tom,
>
>I'm not sure that I follow this. A packet may be ICMP or not regardless of
>if FLOW_DISSECTOR_KEY_PORT (and now FLOW_DISSECTOR_KEY_ICMP) port is set or
>not. I'd appreciate some guidance here.
>
>
>First-pass at implementing Jiri's suggestion follows:
>
>diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
>index 5540dfa18872..475cd121496f 100644
>--- a/include/net/flow_dissector.h
>+++ b/include/net/flow_dissector.h
>@@ -91,14 +91,10 @@ struct flow_dissector_key_addrs {
> 
> /**
>  * flow_dissector_key_ports:
>- *	@ports: port numbers of Transport header or
>- *		type and code of ICMP header
>+ *	@ports: port numbers of Transport header
>  *		ports: source (high) and destination (low) port numbers
>  *		src: source port number
>  *		dst: destination port number
>- *		icmp: ICMP type (high) and code (low)
>- *		type: ICMP type
>- *		type: ICMP code
>  */
> struct flow_dissector_key_ports {
> 	union {
>@@ -107,6 +103,18 @@ struct flow_dissector_key_ports {
> 			__be16 src;
> 			__be16 dst;
> 		};
>+	};
>+};
>+
>+/**
>+ * flow_dissector_key_icmp:
>+ *	@ports: type and code of ICMP header
>+ *		icmp: ICMP type (high) and code (low)
>+ *		type: ICMP type
>+ *		code: ICMP code
>+ */
>+struct flow_dissector_key_icmp {
>+	union {
> 		__be16 icmp;
> 		struct {
> 			u8 type;
>@@ -133,6 +141,7 @@ enum flow_dissector_key_id {
> 	FLOW_DISSECTOR_KEY_IPV4_ADDRS, /* struct flow_dissector_key_ipv4_addrs */
> 	FLOW_DISSECTOR_KEY_IPV6_ADDRS, /* struct flow_dissector_key_ipv6_addrs */
> 	FLOW_DISSECTOR_KEY_PORTS, /* struct flow_dissector_key_ports */
>+	FLOW_DISSECTOR_KEY_ICMP, /* struct flow_dissector_key_icmp */
> 	FLOW_DISSECTOR_KEY_ETH_ADDRS, /* struct flow_dissector_key_eth_addrs */
> 	FLOW_DISSECTOR_KEY_TIPC_ADDRS, /* struct flow_dissector_key_tipc_addrs */
> 	FLOW_DISSECTOR_KEY_VLAN, /* struct flow_dissector_key_flow_vlan */
>@@ -171,7 +180,10 @@ struct flow_keys {
> 	struct flow_dissector_key_tags tags;
> 	struct flow_dissector_key_vlan vlan;
> 	struct flow_dissector_key_keyid keyid;
>-	struct flow_dissector_key_ports ports;
>+	union {
>+		struct flow_dissector_key_ports ports;
>+		struct flow_dissector_key_icmp icmp;
>+	};
> 	struct flow_dissector_key_addrs addrs;
> };
> 
>diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
>index 0584b4bb4390..33e5fa2b3e87 100644
>--- a/net/core/flow_dissector.c
>+++ b/net/core/flow_dissector.c
>@@ -139,6 +139,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
> 	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 flow_dissector_key_keyid *key_keyid;
>@@ -559,18 +560,25 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
> 		break;
> 	}
> 
>-	if (dissector_uses_key(flow_dissector,
>-			       FLOW_DISSECTOR_KEY_PORTS)) {
>-		key_ports = skb_flow_dissector_target(flow_dissector,
>-						      FLOW_DISSECTOR_KEY_PORTS,
>-						      target_container);
>-		if (flow_protos_are_icmp_any(proto, ip_proto))
>-			key_ports->icmp = skb_flow_get_be16(skb, nhoff, data,
>-							    hlen);
>-		else
>+	if (flow_protos_are_icmp_any(proto, ip_proto)) {
>+		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);
>+		}
>+	} else {
>+		if (dissector_uses_key(flow_dissector,
>+				       FLOW_DISSECTOR_KEY_PORTS)) {
>+			key_ports = skb_flow_dissector_target(flow_dissector,
>+							      FLOW_DISSECTOR_KEY_PORTS,
>+							      target_container);
> 			key_ports->ports = __skb_flow_get_ports(skb, nhoff,
> 								ip_proto, data,
> 								hlen);
>+		}
> 	}
> 
> out_good:
>@@ -975,6 +983,10 @@ static const struct flow_dissector_key flow_keys_dissector_keys[] = {
> 		.offset = offsetof(struct flow_keys, ports),
> 	},
> 	{
>+		.key_id = FLOW_DISSECTOR_KEY_ICMP,
>+		.offset = offsetof(struct flow_keys, icmp),
>+	},
>+	{
> 		.key_id = FLOW_DISSECTOR_KEY_VLAN,
> 		.offset = offsetof(struct flow_keys, vlan),
> 	},
>diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>index c96b2a349779..f4ba69bd362f 100644
>--- a/net/sched/cls_flower.c
>+++ b/net/sched/cls_flower.c
>@@ -38,7 +38,10 @@ struct fl_flow_key {
> 		struct flow_dissector_key_ipv4_addrs ipv4;
> 		struct flow_dissector_key_ipv6_addrs ipv6;
> 	};
>-	struct flow_dissector_key_ports tp;
>+	union {
>+		struct flow_dissector_key_ports tp;
>+		struct flow_dissector_key_icmp icmp;
>+	};
> 	struct flow_dissector_key_keyid enc_key_id;
> 	union {
> 		struct flow_dissector_key_ipv4_addrs enc_ipv4;
>@@ -511,19 +514,23 @@ static int fl_set_key(struct net *net, struct nlattr **tb,
> 			       &mask->tp.dst, TCA_FLOWER_KEY_SCTP_DST_MASK,
> 			       sizeof(key->tp.dst));
> 	} else if (flow_basic_key_is_icmpv4(&key->basic)) {
>-		fl_set_key_val(tb, &key->tp.type, TCA_FLOWER_KEY_ICMPV4_TYPE,
>-			       &mask->tp.type, TCA_FLOWER_KEY_ICMPV4_TYPE_MASK,
>-			       sizeof(key->tp.type));
>-		fl_set_key_val(tb, &key->tp.code, TCA_FLOWER_KEY_ICMPV4_CODE,
>-			       &mask->tp.code, TCA_FLOWER_KEY_ICMPV4_CODE_MASK,
>-			       sizeof(key->tp.code));
>+		fl_set_key_val(tb, &key->icmp.type, TCA_FLOWER_KEY_ICMPV4_TYPE,
>+			       &mask->icmp.type,
>+			       TCA_FLOWER_KEY_ICMPV4_TYPE_MASK,
>+			       sizeof(key->icmp.type));
>+		fl_set_key_val(tb, &key->icmp.code, TCA_FLOWER_KEY_ICMPV4_CODE,
>+			       &mask->icmp.code,
>+			       TCA_FLOWER_KEY_ICMPV4_CODE_MASK,
>+			       sizeof(key->icmp.code));
> 	} else if (flow_basic_key_is_icmpv6(&key->basic)) {
>-		fl_set_key_val(tb, &key->tp.type, TCA_FLOWER_KEY_ICMPV6_TYPE,
>-			       &mask->tp.type, TCA_FLOWER_KEY_ICMPV6_TYPE_MASK,
>-			       sizeof(key->tp.type));
>-		fl_set_key_val(tb, &key->tp.code, TCA_FLOWER_KEY_ICMPV4_CODE,
>-			       &mask->tp.code, TCA_FLOWER_KEY_ICMPV4_CODE_MASK,
>-			       sizeof(key->tp.code));
>+		fl_set_key_val(tb, &key->icmp.type, TCA_FLOWER_KEY_ICMPV6_TYPE,
>+			       &mask->icmp.type,
>+			       TCA_FLOWER_KEY_ICMPV6_TYPE_MASK,
>+			       sizeof(key->icmp.type));
>+		fl_set_key_val(tb, &key->icmp.code, TCA_FLOWER_KEY_ICMPV4_CODE,
>+			       &mask->icmp.code,
>+			       TCA_FLOWER_KEY_ICMPV4_CODE_MASK,
>+			       sizeof(key->icmp.code));
> 	}
> 
> 	if (tb[TCA_FLOWER_KEY_ENC_IPV4_SRC] ||
>@@ -609,15 +616,16 @@ static int fl_init_hashtable(struct cls_fl_head *head,
> 		keys[cnt].key_id = id;						\
> 		keys[cnt].offset = FL_KEY_MEMBER_OFFSET(member);		\
> 		cnt++;								\
>-	} while(0);
>+	} while(0)
> 
> #define FL_KEY_SET_IF_MASKED(mask, keys, cnt, id, member)			\
> 	do {									\
> 		if (FL_KEY_IS_MASKED(mask, member))				\
> 			FL_KEY_SET(keys, cnt, id, member);			\
>-	} while(0);
>+	} while(0)
> 
> static void fl_init_dissector(struct cls_fl_head *head,
>+			      struct cls_fl_filter *f,
> 			      struct fl_flow_mask *mask)
> {
> 	struct flow_dissector_key keys[FLOW_DISSECTOR_KEY_MAX];
>@@ -631,8 +639,12 @@ static void fl_init_dissector(struct cls_fl_head *head,
> 			     FLOW_DISSECTOR_KEY_IPV4_ADDRS, ipv4);
> 	FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
> 			     FLOW_DISSECTOR_KEY_IPV6_ADDRS, ipv6);
>-	FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
>-			     FLOW_DISSECTOR_KEY_PORTS, tp);
>+	if (flow_basic_key_is_icmpv4(&f->key.basic))
>+		FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
>+				     FLOW_DISSECTOR_KEY_ICMP, icmp);
>+	else
>+		FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
>+				     FLOW_DISSECTOR_KEY_PORTS, tp);
> 	FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
> 			     FLOW_DISSECTOR_KEY_VLAN, vlan);
> 	FL_KEY_SET_IF_MASKED(&mask->key, keys, cnt,
>@@ -652,6 +664,7 @@ static void fl_init_dissector(struct cls_fl_head *head,
> }
> 
> static int fl_check_assign_mask(struct cls_fl_head *head,
>+				struct cls_fl_filter *f,
> 				struct fl_flow_mask *mask)
> {
> 	int err;
>@@ -672,7 +685,7 @@ static int fl_check_assign_mask(struct cls_fl_head *head,
> 	memcpy(&head->mask, mask, sizeof(head->mask));
> 	head->mask_assigned = true;
> 
>-	fl_init_dissector(head, mask);
>+	fl_init_dissector(head, f, mask);
> 
> 	return 0;
> }
>@@ -785,7 +798,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
> 	if (err)
> 		goto errout;
> 
>-	err = fl_check_assign_mask(head, &mask);
>+	err = fl_check_assign_mask(head, fnew, &mask);
> 	if (err)
> 		goto errout;
> 
>@@ -1000,24 +1013,24 @@ static int fl_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
> 				  sizeof(key->tp.dst))))
> 		goto nla_put_failure;
> 	else if (flow_basic_key_is_icmpv4(&key->basic) &&
>-		 (fl_dump_key_val(skb, &key->tp.type,
>-				  TCA_FLOWER_KEY_ICMPV4_TYPE, &mask->tp.type,
>+		 (fl_dump_key_val(skb, &key->icmp.type,
>+				  TCA_FLOWER_KEY_ICMPV4_TYPE, &mask->icmp.type,
> 				  TCA_FLOWER_KEY_ICMPV4_TYPE_MASK,
>-				  sizeof(key->tp.type)) ||
>-		  fl_dump_key_val(skb, &key->tp.code,
>-				  TCA_FLOWER_KEY_ICMPV4_CODE, &mask->tp.code,
>+				  sizeof(key->icmp.type)) ||
>+		  fl_dump_key_val(skb, &key->icmp.code,
>+				  TCA_FLOWER_KEY_ICMPV4_CODE, &mask->icmp.code,
> 				  TCA_FLOWER_KEY_ICMPV4_CODE_MASK,
>-				  sizeof(key->tp.code))))
>+				  sizeof(key->icmp.code))))
> 		goto nla_put_failure;
> 	else if (flow_basic_key_is_icmpv6(&key->basic) &&
>-		 (fl_dump_key_val(skb, &key->tp.type,
>-				  TCA_FLOWER_KEY_ICMPV6_TYPE, &mask->tp.type,
>+		 (fl_dump_key_val(skb, &key->icmp.type,
>+				  TCA_FLOWER_KEY_ICMPV6_TYPE, &mask->icmp.type,
> 				  TCA_FLOWER_KEY_ICMPV6_TYPE_MASK,
>-				  sizeof(key->tp.type)) ||
>-		  fl_dump_key_val(skb, &key->tp.code,
>-				  TCA_FLOWER_KEY_ICMPV6_CODE, &mask->tp.code,
>+				  sizeof(key->icmp.type)) ||
>+		  fl_dump_key_val(skb, &key->icmp.code,
>+				  TCA_FLOWER_KEY_ICMPV6_CODE, &mask->icmp.code,
> 				  TCA_FLOWER_KEY_ICMPV6_CODE_MASK,
>-				  sizeof(key->tp.code))))
>+				  sizeof(key->icmp.code))))
> 		goto nla_put_failure;
> 
> 	if (key->enc_control.addr_type == FLOW_DISSECTOR_KEY_IPV4_ADDRS &&

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