[NET_SCHED]: Add flow classifier

Add new "flow" classifier, which is meant to extend the SFQ hashing
capabilities without hard-coding new hash functions and also allows
deterministic mappings of keys to classes, replacing some out of tree
iptables patches like IPCLASSIFY (maps IPs to classes), IPMARK (maps
IPs to marks, with fw filters to classes), ...

Some examples:

- Classic SFQ hash:

  tc filter add ... flow hash \
  	keys src,dst,proto,proto-src,proto-dst divisor 1024

- Classic SFQ hash, but using information from conntrack to work properly in
  combination with NAT:

  tc filter add ... flow hash \
  	keys nfct-src,nfct-dst,proto,nfct-proto-src,nfct-proto-dst divisor 1024

- Map destination IPs of 192.168.0.0/24 to classids 1-257:

  tc filter add ... flow map \
  	key dst addend -192.168.0.0 divisor 256

- alternatively:

  tc filter add ... flow map \
  	key dst and 0xff

- similar, but reverse ordered:

  tc filter add ... flow map \
  	key dst and 0xff xor 0xff

Perturbation is currently not supported because we can't reliable kill the
timer on destruction.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/pkt_cls.h

@@ -328,6 +328,56 @@ enum
 
 #define TCA_TCINDEX_MAX     (__TCA_TCINDEX_MAX - 1)
 
+/* Flow filter */
+
+enum
+{
+	FLOW_KEY_SRC,
+	FLOW_KEY_DST,
+	FLOW_KEY_PROTO,
+	FLOW_KEY_PROTO_SRC,
+	FLOW_KEY_PROTO_DST,
+	FLOW_KEY_IIF,
+	FLOW_KEY_PRIORITY,
+	FLOW_KEY_MARK,
+	FLOW_KEY_NFCT,
+	FLOW_KEY_NFCT_SRC,
+	FLOW_KEY_NFCT_DST,
+	FLOW_KEY_NFCT_PROTO_SRC,
+	FLOW_KEY_NFCT_PROTO_DST,
+	FLOW_KEY_RTCLASSID,
+	FLOW_KEY_SKUID,
+	FLOW_KEY_SKGID,
+	__FLOW_KEY_MAX,
+};
+
+#define FLOW_KEY_MAX	(__FLOW_KEY_MAX - 1)
+
+enum
+{
+	FLOW_MODE_MAP,
+	FLOW_MODE_HASH,
+};
+
+enum
+{
+	TCA_FLOW_UNSPEC,
+	TCA_FLOW_KEYS,
+	TCA_FLOW_MODE,
+	TCA_FLOW_BASECLASS,
+	TCA_FLOW_RSHIFT,
+	TCA_FLOW_ADDEND,
+	TCA_FLOW_MASK,
+	TCA_FLOW_XOR,
+	TCA_FLOW_DIVISOR,
+	TCA_FLOW_ACT,
+	TCA_FLOW_POLICE,
+	TCA_FLOW_EMATCHES,
+	__TCA_FLOW_MAX
+};
+
+#define TCA_FLOW_MAX	(__TCA_FLOW_MAX - 1)
+
 /* Basic filter */
 
 enum

net/sched/Kconfig

@@ -307,6 +307,17 @@ config NET_CLS_RSVP6
 	  To compile this code as a module, choose M here: the
 	  module will be called cls_rsvp6.
 
+config NET_CLS_FLOW
+	tristate "Flow classifier"
+	select NET_CLS
+	---help---
+	  If you say Y here, you will be able to classify packets based on
+	  a configurable combination of packet keys. This is mostly useful
+	  in combination with SFQ.
+
+	  To compile this code as a module, choose M here: the
+	  module will be called cls_flow.
+
 config NET_EMATCH
 	bool "Extended Matches"
 	select NET_CLS

net/sched/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_NET_CLS_RSVP)	+= cls_rsvp.o
 obj-$(CONFIG_NET_CLS_TCINDEX)	+= cls_tcindex.o
 obj-$(CONFIG_NET_CLS_RSVP6)	+= cls_rsvp6.o
 obj-$(CONFIG_NET_CLS_BASIC)	+= cls_basic.o
+obj-$(CONFIG_NET_CLS_FLOW)	+= cls_flow.o
 obj-$(CONFIG_NET_EMATCH)	+= ematch.o
 obj-$(CONFIG_NET_EMATCH_CMP)	+= em_cmp.o
 obj-$(CONFIG_NET_EMATCH_NBYTE)	+= em_nbyte.o

net/sched/cls_flow.c

@@ -0,0 +1,660 @@
+/*
+ * net/sched/cls_flow.c		Generic flow classifier
+ *
+ * Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
+ *
+ * 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/list.h>
+#include <linux/jhash.h>
+#include <linux/random.h>
+#include <linux/pkt_cls.h>
+#include <linux/skbuff.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+
+#include <net/pkt_cls.h>
+#include <net/ip.h>
+#include <net/route.h>
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
+struct flow_head {
+	struct list_head	filters;
+};
+
+struct flow_filter {
+	struct list_head	list;
+	struct tcf_exts		exts;
+	struct tcf_ematch_tree	ematches;
+	u32			handle;
+
+	u32			nkeys;
+	u32			keymask;
+	u32			mode;
+	u32			mask;
+	u32			xor;
+	u32			rshift;
+	u32			addend;
+	u32			divisor;
+	u32			baseclass;
+};
+
+static u32 flow_hashrnd __read_mostly;
+static int flow_hashrnd_initted __read_mostly;
+
+static const struct tcf_ext_map flow_ext_map = {
+	.action	= TCA_FLOW_ACT,
+	.police	= TCA_FLOW_POLICE,
+};
+
+static inline u32 addr_fold(void *addr)
+{
+	unsigned long a = (unsigned long)addr;
+
+	return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
+}
+
+static u32 flow_get_src(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+		return ntohl(ip_hdr(skb)->saddr);
+	case __constant_htons(ETH_P_IPV6):
+		return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
+	default:
+		return addr_fold(skb->sk);
+	}
+}
+
+static u32 flow_get_dst(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+		return ntohl(ip_hdr(skb)->daddr);
+	case __constant_htons(ETH_P_IPV6):
+		return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
+	default:
+		return addr_fold(skb->dst) ^ (__force u16)skb->protocol;
+	}
+}
+
+static u32 flow_get_proto(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+		return ip_hdr(skb)->protocol;
+	case __constant_htons(ETH_P_IPV6):
+		return ipv6_hdr(skb)->nexthdr;
+	default:
+		return 0;
+	}
+}
+
+static int has_ports(u8 protocol)
+{
+	switch (protocol) {
+	case IPPROTO_TCP:
+	case IPPROTO_UDP:
+	case IPPROTO_UDPLITE:
+	case IPPROTO_SCTP:
+	case IPPROTO_DCCP:
+	case IPPROTO_ESP:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+static u32 flow_get_proto_src(const struct sk_buff *skb)
+{
+	u32 res = 0;
+
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP): {
+		struct iphdr *iph = ip_hdr(skb);
+
+		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
+		    has_ports(iph->protocol))
+			res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
+		break;
+	}
+	case __constant_htons(ETH_P_IPV6): {
+		struct ipv6hdr *iph = ipv6_hdr(skb);
+
+		if (has_ports(iph->nexthdr))
+			res = ntohs(*(__be16 *)&iph[1]);
+		break;
+	}
+	default:
+		res = addr_fold(skb->sk);
+	}
+
+	return res;
+}
+
+static u32 flow_get_proto_dst(const struct sk_buff *skb)
+{
+	u32 res = 0;
+
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP): {
+		struct iphdr *iph = ip_hdr(skb);
+
+		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
+		    has_ports(iph->protocol))
+			res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
+		break;
+	}
+	case __constant_htons(ETH_P_IPV6): {
+		struct ipv6hdr *iph = ipv6_hdr(skb);
+
+		if (has_ports(iph->nexthdr))
+			res = ntohs(*(__be16 *)((void *)&iph[1] + 2));
+		break;
+	}
+	default:
+		res = addr_fold(skb->dst) ^ (__force u16)skb->protocol;
+	}
+
+	return res;
+}
+
+static u32 flow_get_iif(const struct sk_buff *skb)
+{
+	return skb->iif;
+}
+
+static u32 flow_get_priority(const struct sk_buff *skb)
+{
+	return skb->priority;
+}
+
+static u32 flow_get_mark(const struct sk_buff *skb)
+{
+	return skb->mark;
+}
+
+static u32 flow_get_nfct(const struct sk_buff *skb)
+{
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+	return addr_fold(skb->nfct);
+#else
+	return 0;
+#endif
+}
+
+#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
+#define CTTUPLE(skb, member)						\
+({									\
+	enum ip_conntrack_info ctinfo;					\
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);			\
+	if (ct == NULL)							\
+		goto fallback;						\
+	ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.member;			\
+})
+#else
+#define CTTUPLE(skb, member)						\
+({									\
+	goto fallback;							\
+	0;								\
+})
+#endif
+
+static u32 flow_get_nfct_src(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+		return ntohl(CTTUPLE(skb, src.u3.ip));
+	case __constant_htons(ETH_P_IPV6):
+		return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
+	}
+fallback:
+	return flow_get_src(skb);
+}
+
+static u32 flow_get_nfct_dst(const struct sk_buff *skb)
+{
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+		return ntohl(CTTUPLE(skb, dst.u3.ip));
+	case __constant_htons(ETH_P_IPV6):
+		return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
+	}
+fallback:
+	return flow_get_dst(skb);
+}
+
+static u32 flow_get_nfct_proto_src(const struct sk_buff *skb)
+{
+	return ntohs(CTTUPLE(skb, src.u.all));
+fallback:
+	return flow_get_proto_src(skb);
+}
+
+static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb)
+{
+	return ntohs(CTTUPLE(skb, dst.u.all));
+fallback:
+	return flow_get_proto_dst(skb);
+}
+
+static u32 flow_get_rtclassid(const struct sk_buff *skb)
+{
+#ifdef CONFIG_NET_CLS_ROUTE
+	if (skb->dst)
+		return skb->dst->tclassid;
+#endif
+	return 0;
+}
+
+static u32 flow_get_skuid(const struct sk_buff *skb)
+{
+	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
+		return skb->sk->sk_socket->file->f_uid;
+	return 0;
+}
+
+static u32 flow_get_skgid(const struct sk_buff *skb)
+{
+	if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
+		return skb->sk->sk_socket->file->f_gid;
+	return 0;
+}
+
+static u32 flow_key_get(const struct sk_buff *skb, int key)
+{
+	switch (key) {
+	case FLOW_KEY_SRC:
+		return flow_get_src(skb);
+	case FLOW_KEY_DST:
+		return flow_get_dst(skb);
+	case FLOW_KEY_PROTO:
+		return flow_get_proto(skb);
+	case FLOW_KEY_PROTO_SRC:
+		return flow_get_proto_src(skb);
+	case FLOW_KEY_PROTO_DST:
+		return flow_get_proto_dst(skb);
+	case FLOW_KEY_IIF:
+		return flow_get_iif(skb);
+	case FLOW_KEY_PRIORITY:
+		return flow_get_priority(skb);
+	case FLOW_KEY_MARK:
+		return flow_get_mark(skb);
+	case FLOW_KEY_NFCT:
+		return flow_get_nfct(skb);
+	case FLOW_KEY_NFCT_SRC:
+		return flow_get_nfct_src(skb);
+	case FLOW_KEY_NFCT_DST:
+		return flow_get_nfct_dst(skb);
+	case FLOW_KEY_NFCT_PROTO_SRC:
+		return flow_get_nfct_proto_src(skb);
+	case FLOW_KEY_NFCT_PROTO_DST:
+		return flow_get_nfct_proto_dst(skb);
+	case FLOW_KEY_RTCLASSID:
+		return flow_get_rtclassid(skb);
+	case FLOW_KEY_SKUID:
+		return flow_get_skuid(skb);
+	case FLOW_KEY_SKGID:
+		return flow_get_skgid(skb);
+	default:
+		WARN_ON(1);
+		return 0;
+	}
+}
+
+static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
+			 struct tcf_result *res)
+{
+	struct flow_head *head = tp->root;
+	struct flow_filter *f;
+	u32 keymask;
+	u32 classid;
+	unsigned int n, key;
+	int r;
+
+	list_for_each_entry(f, &head->filters, list) {
+		u32 keys[f->nkeys];
+
+		if (!tcf_em_tree_match(skb, &f->ematches, NULL))
+			continue;
+
+		keymask = f->keymask;
+
+		for (n = 0; n < f->nkeys; n++) {
+			key = ffs(keymask) - 1;
+			keymask &= ~(1 << key);
+			keys[n] = flow_key_get(skb, key);
+		}
+
+		if (f->mode == FLOW_MODE_HASH)
+			classid = jhash2(keys, f->nkeys, flow_hashrnd);
+		else {
+			classid = keys[0];
+			classid = (classid & f->mask) ^ f->xor;
+			classid = (classid >> f->rshift) + f->addend;
+		}
+
+		if (f->divisor)
+			classid %= f->divisor;
+
+		res->class   = 0;
+		res->classid = TC_H_MAKE(f->baseclass, f->baseclass + classid);
+
+		r = tcf_exts_exec(skb, &f->exts, res);
+		if (r < 0)
+			continue;
+		return r;
+	}
+	return -1;
+}
+
+static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
+	[TCA_FLOW_KEYS]		= { .type = NLA_U32 },
+	[TCA_FLOW_MODE]		= { .type = NLA_U32 },
+	[TCA_FLOW_BASECLASS]	= { .type = NLA_U32 },
+	[TCA_FLOW_RSHIFT]	= { .type = NLA_U32 },
+	[TCA_FLOW_ADDEND]	= { .type = NLA_U32 },
+	[TCA_FLOW_MASK]		= { .type = NLA_U32 },
+	[TCA_FLOW_XOR]		= { .type = NLA_U32 },
+	[TCA_FLOW_DIVISOR]	= { .type = NLA_U32 },
+	[TCA_FLOW_ACT]		= { .type = NLA_NESTED },
+	[TCA_FLOW_POLICE]	= { .type = NLA_NESTED },
+	[TCA_FLOW_EMATCHES]	= { .type = NLA_NESTED },
+};
+
+static int flow_change(struct tcf_proto *tp, unsigned long base,
+		       u32 handle, struct nlattr **tca,
+		       unsigned long *arg)
+{
+	struct flow_head *head = tp->root;
+	struct flow_filter *f;
+	struct nlattr *opt = tca[TCA_OPTIONS];
+	struct nlattr *tb[TCA_FLOW_MAX + 1];
+	struct tcf_exts e;
+	struct tcf_ematch_tree t;
+	unsigned int nkeys = 0;
+	u32 baseclass = 0;
+	u32 keymask = 0;
+	u32 mode;
+	int err;
+
+	if (opt == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, TCA_FLOW_MAX, opt, flow_policy);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_FLOW_BASECLASS]) {
+		baseclass = nla_get_u32(tb[TCA_FLOW_BASECLASS]);
+		if (TC_H_MIN(baseclass) == 0)
+			return -EINVAL;
+	}
+
+	if (tb[TCA_FLOW_KEYS]) {
+		keymask = nla_get_u32(tb[TCA_FLOW_KEYS]);
+		if (fls(keymask) - 1 > FLOW_KEY_MAX)
+			return -EOPNOTSUPP;
+
+		nkeys = hweight32(keymask);
+		if (nkeys == 0)
+			return -EINVAL;
+	}
+
+	err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &flow_ext_map);
+	if (err < 0)
+		return err;
+
+	err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &t);
+	if (err < 0)
+		goto err1;
+
+	f = (struct flow_filter *)*arg;
+	if (f != NULL) {
+		err = -EINVAL;
+		if (f->handle != handle && handle)
+			goto err2;
+
+		mode = f->mode;
+		if (tb[TCA_FLOW_MODE])
+			mode = nla_get_u32(tb[TCA_FLOW_MODE]);
+		if (mode != FLOW_MODE_HASH && nkeys > 1)
+			goto err2;
+	} else {
+		err = -EINVAL;
+		if (!handle)
+			goto err2;
+		if (!tb[TCA_FLOW_KEYS])
+			goto err2;
+
+		mode = FLOW_MODE_MAP;
+		if (tb[TCA_FLOW_MODE])
+			mode = nla_get_u32(tb[TCA_FLOW_MODE]);
+		if (mode != FLOW_MODE_HASH && nkeys > 1)
+			goto err2;
+
+		if (TC_H_MAJ(baseclass) == 0)
+			baseclass = TC_H_MAKE(tp->q->handle, baseclass);
+		if (TC_H_MIN(baseclass) == 0)
+			baseclass = TC_H_MAKE(baseclass, 1);
+
+		err = -ENOBUFS;
+		f = kzalloc(sizeof(*f), GFP_KERNEL);
+		if (f == NULL)
+			goto err2;
+
+		f->handle = handle;
+		f->mask	  = ~0U;
+	}
+
+	tcf_exts_change(tp, &f->exts, &e);
+	tcf_em_tree_change(tp, &f->ematches, &t);
+
+	tcf_tree_lock(tp);
+
+	if (tb[TCA_FLOW_KEYS]) {
+		f->keymask = keymask;
+		f->nkeys   = nkeys;
+	}
+
+	f->mode = mode;
+
+	if (tb[TCA_FLOW_MASK])
+		f->mask = nla_get_u32(tb[TCA_FLOW_MASK]);
+	if (tb[TCA_FLOW_XOR])
+		f->xor = nla_get_u32(tb[TCA_FLOW_XOR]);
+	if (tb[TCA_FLOW_RSHIFT])
+		f->rshift = nla_get_u32(tb[TCA_FLOW_RSHIFT]);
+	if (tb[TCA_FLOW_ADDEND])
+		f->addend = nla_get_u32(tb[TCA_FLOW_ADDEND]);
+
+	if (tb[TCA_FLOW_DIVISOR])
+		f->divisor = nla_get_u32(tb[TCA_FLOW_DIVISOR]);
+	if (baseclass)
+		f->baseclass = baseclass;
+
+	if (*arg == 0)
+		list_add_tail(&f->list, &head->filters);
+
+	tcf_tree_unlock(tp);
+
+	*arg = (unsigned long)f;
+	return 0;
+
+err2:
+	tcf_em_tree_destroy(tp, &t);
+err1:
+	tcf_exts_destroy(tp, &e);
+	return err;
+}
+
+static void flow_destroy_filter(struct tcf_proto *tp, struct flow_filter *f)
+{
+	tcf_exts_destroy(tp, &f->exts);
+	tcf_em_tree_destroy(tp, &f->ematches);
+	kfree(f);
+}
+
+static int flow_delete(struct tcf_proto *tp, unsigned long arg)
+{
+	struct flow_filter *f = (struct flow_filter *)arg;
+
+	tcf_tree_lock(tp);
+	list_del(&f->list);
+	tcf_tree_unlock(tp);
+	flow_destroy_filter(tp, f);
+	return 0;
+}
+
+static int flow_init(struct tcf_proto *tp)
+{
+	struct flow_head *head;
+
+	if (!flow_hashrnd_initted) {
+		get_random_bytes(&flow_hashrnd, 4);
+		flow_hashrnd_initted = 1;
+	}
+
+	head = kzalloc(sizeof(*head), GFP_KERNEL);
+	if (head == NULL)
+		return -ENOBUFS;
+	INIT_LIST_HEAD(&head->filters);
+	tp->root = head;
+	return 0;
+}
+
+static void flow_destroy(struct tcf_proto *tp)
+{
+	struct flow_head *head = tp->root;
+	struct flow_filter *f, *next;
+
+	list_for_each_entry_safe(f, next, &head->filters, list) {
+		list_del(&f->list);
+		flow_destroy_filter(tp, f);
+	}
+	kfree(head);
+}
+
+static unsigned long flow_get(struct tcf_proto *tp, u32 handle)
+{
+	struct flow_head *head = tp->root;
+	struct flow_filter *f;
+
+	list_for_each_entry(f, &head->filters, list)
+		if (f->handle == handle)
+			return (unsigned long)f;
+	return 0;
+}
+
+static void flow_put(struct tcf_proto *tp, unsigned long f)
+{
+	return;
+}
+
+static int flow_dump(struct tcf_proto *tp, unsigned long fh,
+		     struct sk_buff *skb, struct tcmsg *t)
+{
+	struct flow_filter *f = (struct flow_filter *)fh;
+	struct nlattr *nest;
+
+	if (f == NULL)
+		return skb->len;
+
+	t->tcm_handle = f->handle;
+
+	nest = nla_nest_start(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	NLA_PUT_U32(skb, TCA_FLOW_KEYS, f->keymask);
+	NLA_PUT_U32(skb, TCA_FLOW_MODE, f->mode);
+
+	if (f->mask != ~0 || f->xor != 0) {
+		NLA_PUT_U32(skb, TCA_FLOW_MASK, f->mask);
+		NLA_PUT_U32(skb, TCA_FLOW_XOR, f->xor);
+	}
+	if (f->rshift)
+		NLA_PUT_U32(skb, TCA_FLOW_RSHIFT, f->rshift);
+	if (f->addend)
+		NLA_PUT_U32(skb, TCA_FLOW_ADDEND, f->addend);
+
+	if (f->divisor)
+		NLA_PUT_U32(skb, TCA_FLOW_DIVISOR, f->divisor);
+	if (f->baseclass)
+		NLA_PUT_U32(skb, TCA_FLOW_BASECLASS, f->baseclass);
+
+	if (tcf_exts_dump(skb, &f->exts, &flow_ext_map) < 0)
+		goto nla_put_failure;
+
+	if (f->ematches.hdr.nmatches &&
+	    tcf_em_tree_dump(skb, &f->ematches, TCA_FLOW_EMATCHES) < 0)
+		goto nla_put_failure;
+
+	nla_nest_end(skb, nest);
+
+	if (tcf_exts_dump_stats(skb, &f->exts, &flow_ext_map) < 0)
+		goto nla_put_failure;
+
+	return skb->len;
+
+nla_put_failure:
+	nlmsg_trim(skb, nest);
+	return -1;
+}
+
+static void flow_walk(struct tcf_proto *tp, struct tcf_walker *arg)
+{
+	struct flow_head *head = tp->root;
+	struct flow_filter *f;
+
+	list_for_each_entry(f, &head->filters, list) {
+		if (arg->count < arg->skip)
+			goto skip;
+		if (arg->fn(tp, (unsigned long)f, arg) < 0) {
+			arg->stop = 1;
+			break;
+		}
+skip:
+		arg->count++;
+	}
+}
+
+static struct tcf_proto_ops cls_flow_ops __read_mostly = {
+	.kind		= "flow",
+	.classify	= flow_classify,
+	.init		= flow_init,
+	.destroy	= flow_destroy,
+	.change		= flow_change,
+	.delete		= flow_delete,
+	.get		= flow_get,
+	.put		= flow_put,
+	.dump		= flow_dump,
+	.walk		= flow_walk,
+	.owner		= THIS_MODULE,
+};
+
+static int __init cls_flow_init(void)
+{
+	return register_tcf_proto_ops(&cls_flow_ops);
+}
+
+static void __exit cls_flow_exit(void)
+{
+	unregister_tcf_proto_ops(&cls_flow_ops);
+}
+
+module_init(cls_flow_init);
+module_exit(cls_flow_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("TC flow classifier");