net/sched: introduce Match-all classifier

The matchall classifier matches every packet and allows the user to apply
actions on it. This filter is very useful in usecases where every packet
should be matched, for example, packet mirroring (SPAN) can be setup very
easily using that filter.

Signed-off-by: Jiri Pirko <[e-mail]>
Signed-off-by: Yotam Gigi <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/uapi/linux/pkt_cls.h

···
 
 #define TCA_FLOWER_MAX (__TCA_FLOWER_MAX - 1)
 
+/* Match-all classifier */
+
+enum {
+	TCA_MATCHALL_UNSPEC,
+	TCA_MATCHALL_CLASSID,
+	TCA_MATCHALL_ACT,
+	__TCA_MATCHALL_MAX,
+};
+
+#define TCA_MATCHALL_MAX (__TCA_MATCHALL_MAX - 1)
+
 /* Extended Matches */
 
 struct tcf_ematch_tree_hdr {

net/sched/Kconfig

···
 	  To compile this code as a module, choose M here: the module will
 	  be called cls_flower.
 
+config NET_CLS_MATCHALL
+	tristate "Match-all classifier"
+	select NET_CLS
+	---help---
+	  If you say Y here, you will be able to classify packets based on
+	  nothing. Every packet will match.
+
+	  To compile this code as a module, choose M here: the module will
+	  be called cls_matchall.
+
 config NET_EMATCH
 	bool "Extended Matches"
 	select NET_CLS

net/sched/Makefile

···
 obj-$(CONFIG_NET_CLS_CGROUP)	+= cls_cgroup.o
 obj-$(CONFIG_NET_CLS_BPF)	+= cls_bpf.o
 obj-$(CONFIG_NET_CLS_FLOWER)	+= cls_flower.o
+obj-$(CONFIG_NET_CLS_MATCHALL)	+= cls_matchall.o
 obj-$(CONFIG_NET_EMATCH)	+= ematch.o
 obj-$(CONFIG_NET_EMATCH_CMP)	+= em_cmp.o
 obj-$(CONFIG_NET_EMATCH_NBYTE)	+= em_nbyte.o

net/sched/cls_matchall.c

···
+/*
+ * net/sched/cls_matchll.c		Match-all classifier
+ *
+ * Copyright (c) 2016 Jiri Pirko <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include <net/sch_generic.h>
+#include <net/pkt_cls.h>
+
+struct cls_mall_filter {
+	struct tcf_exts exts;
+	struct tcf_result res;
+	u32 handle;
+	struct rcu_head	rcu;
+};
+
+struct cls_mall_head {
+	struct cls_mall_filter *filter;
+	struct rcu_head	rcu;
+};
+
+static int mall_classify(struct sk_buff *skb, const struct tcf_proto *tp,
+			 struct tcf_result *res)
+{
+	struct cls_mall_head *head = rcu_dereference_bh(tp->root);
+	struct cls_mall_filter *f = head->filter;
+
+	return tcf_exts_exec(skb, &f->exts, res);
+}
+
+static int mall_init(struct tcf_proto *tp)
+{
+	struct cls_mall_head *head;
+
+	head = kzalloc(sizeof(*head), GFP_KERNEL);
+	if (!head)
+		return -ENOBUFS;
+
+	rcu_assign_pointer(tp->root, head);
+
+	return 0;
+}
+
+static void mall_destroy_filter(struct rcu_head *head)
+{
+	struct cls_mall_filter *f = container_of(head, struct cls_mall_filter, rcu);
+
+	tcf_exts_destroy(&f->exts);
+	kfree(f);
+}
+
+static bool mall_destroy(struct tcf_proto *tp, bool force)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+
+	if (!force && head->filter)
+		return false;
+
+	if (head->filter)
+		call_rcu(&head->filter->rcu, mall_destroy_filter);
+	RCU_INIT_POINTER(tp->root, NULL);
+	kfree_rcu(head, rcu);
+	return true;
+}
+
+static unsigned long mall_get(struct tcf_proto *tp, u32 handle)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+	struct cls_mall_filter *f = head->filter;
+
+	if (f && f->handle == handle)
+		return (unsigned long) f;
+	return 0;
+}
+
+static const struct nla_policy mall_policy[TCA_MATCHALL_MAX + 1] = {
+	[TCA_MATCHALL_UNSPEC]		= { .type = NLA_UNSPEC },
+	[TCA_MATCHALL_CLASSID]		= { .type = NLA_U32 },
+};
+
+static int mall_set_parms(struct net *net, struct tcf_proto *tp,
+			  struct cls_mall_filter *f,
+			  unsigned long base, struct nlattr **tb,
+			  struct nlattr *est, bool ovr)
+{
+	struct tcf_exts e;
+	int err;
+
+	tcf_exts_init(&e, TCA_MATCHALL_ACT, 0);
+	err = tcf_exts_validate(net, tp, tb, est, &e, ovr);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_MATCHALL_CLASSID]) {
+		f->res.classid = nla_get_u32(tb[TCA_MATCHALL_CLASSID]);
+		tcf_bind_filter(tp, &f->res, base);
+	}
+
+	tcf_exts_change(tp, &f->exts, &e);
+
+	return 0;
+}
+
+static int mall_change(struct net *net, struct sk_buff *in_skb,
+		       struct tcf_proto *tp, unsigned long base,
+		       u32 handle, struct nlattr **tca,
+		       unsigned long *arg, bool ovr)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+	struct cls_mall_filter *fold = (struct cls_mall_filter *) *arg;
+	struct cls_mall_filter *f;
+	struct nlattr *tb[TCA_MATCHALL_MAX + 1];
+	int err;
+
+	if (!tca[TCA_OPTIONS])
+		return -EINVAL;
+
+	if (head->filter)
+		return -EBUSY;
+
+	if (fold)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, TCA_MATCHALL_MAX,
+			       tca[TCA_OPTIONS], mall_policy);
+	if (err < 0)
+		return err;
+
+	f = kzalloc(sizeof(*f), GFP_KERNEL);
+	if (!f)
+		return -ENOBUFS;
+
+	tcf_exts_init(&f->exts, TCA_MATCHALL_ACT, 0);
+
+	if (!handle)
+		handle = 1;
+	f->handle = handle;
+
+	err = mall_set_parms(net, tp, f, base, tb, tca[TCA_RATE], ovr);
+	if (err)
+		goto errout;
+
+	*arg = (unsigned long) f;
+	rcu_assign_pointer(head->filter, f);
+
+	return 0;
+
+errout:
+	kfree(f);
+	return err;
+}
+
+static int mall_delete(struct tcf_proto *tp, unsigned long arg)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+	struct cls_mall_filter *f = (struct cls_mall_filter *) arg;
+
+	RCU_INIT_POINTER(head->filter, NULL);
+	tcf_unbind_filter(tp, &f->res);
+	call_rcu(&f->rcu, mall_destroy_filter);
+	return 0;
+}
+
+static void mall_walk(struct tcf_proto *tp, struct tcf_walker *arg)
+{
+	struct cls_mall_head *head = rtnl_dereference(tp->root);
+	struct cls_mall_filter *f = head->filter;
+
+	if (arg->count < arg->skip)
+		goto skip;
+	if (arg->fn(tp, (unsigned long) f, arg) < 0)
+		arg->stop = 1;
+skip:
+	arg->count++;
+}
+
+static int mall_dump(struct net *net, struct tcf_proto *tp, unsigned long fh,
+		     struct sk_buff *skb, struct tcmsg *t)
+{
+	struct cls_mall_filter *f = (struct cls_mall_filter *) fh;
+	struct nlattr *nest;
+
+	if (!f)
+		return skb->len;
+
+	t->tcm_handle = f->handle;
+
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (!nest)
+		goto nla_put_failure;
+
+	if (f->res.classid &&
+	    nla_put_u32(skb, TCA_MATCHALL_CLASSID, f->res.classid))
+		goto nla_put_failure;
+
+	if (tcf_exts_dump(skb, &f->exts))
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+
+	if (tcf_exts_dump_stats(skb, &f->exts) < 0)
+		goto nla_put_failure;
+
+	return skb->len;
+
+nla_put_failure:
+	nla_nest_cancel(skb, nest);
+	return -1;
+}
+
+static struct tcf_proto_ops cls_mall_ops __read_mostly = {
+	.kind		= "matchall",
+	.classify	= mall_classify,
+	.init		= mall_init,
+	.destroy	= mall_destroy,
+	.get		= mall_get,
+	.change		= mall_change,
+	.delete		= mall_delete,
+	.walk		= mall_walk,
+	.dump		= mall_dump,
+	.owner		= THIS_MODULE,
+};
+
+static int __init cls_mall_init(void)
+{
+	return register_tcf_proto_ops(&cls_mall_ops);
+}
+
+static void __exit cls_mall_exit(void)
+{
+	unregister_tcf_proto_ops(&cls_mall_ops);
+}
+
+module_init(cls_mall_init);
+module_exit(cls_mall_exit);
+
+MODULE_AUTHOR("Jiri Pirko <[e-mail]>");
+MODULE_DESCRIPTION("Match-all classifier");
+MODULE_LICENSE("GPL v2");