ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 737 insertions, 0 deletions

diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
new file mode 100644
index 000000000..a9ac3acf6
--- /dev/null
+++ b/net/sched/cls_flow.c
@@ -0,0 +1,737 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * net/sched/cls_flow.c		Generic flow classifier
+ *
+ * Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
+ */
+
+#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 <linux/if_vlan.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <net/inet_sock.h>
+
+#include <net/pkt_cls.h>
+#include <linux/siphash.h>
+#include <net/ip.h>
+#include <net/route.h>
+#include <net/flow_dissector.h>
+#include <net/tc_wrapper.h>
+
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#include <net/netfilter/nf_conntrack.h>
+#endif
+
+struct flow_head {
+	struct list_head	filters;
+	struct rcu_head		rcu;
+};
+
+struct flow_filter {
+	struct list_head	list;
+	struct tcf_exts		exts;
+	struct tcf_ematch_tree	ematches;
+	struct tcf_proto	*tp;
+	struct timer_list	perturb_timer;
+	u32			perturb_period;
+	u32			handle;
+
+	u32			nkeys;
+	u32			keymask;
+	u32			mode;
+	u32			mask;
+	u32			xor;
+	u32			rshift;
+	u32			addend;
+	u32			divisor;
+	u32			baseclass;
+	u32			hashrnd;
+	struct rcu_work		rwork;
+};
+
+static siphash_aligned_key_t flow_keys_secret __read_mostly;
+
+static inline u32 addr_fold(void *addr)
+{
+#ifdef CONFIG_64BIT
+	return (u32)siphash_1u64((u64)addr, &flow_keys_secret);
+#else
+	return (u32)siphash_1u32((u32)addr, &flow_keys_secret);
+#endif
+}
+
+static u32 flow_get_src(const struct sk_buff *skb, const struct flow_keys *flow)
+{
+	__be32 src = flow_get_u32_src(flow);
+
+	if (src)
+		return ntohl(src);
+
+	return addr_fold(skb->sk);
+}
+
+static u32 flow_get_dst(const struct sk_buff *skb, const struct flow_keys *flow)
+{
+	__be32 dst = flow_get_u32_dst(flow);
+
+	if (dst)
+		return ntohl(dst);
+
+	return addr_fold(skb_dst(skb)) ^ (__force u16)skb_protocol(skb, true);
+}
+
+static u32 flow_get_proto(const struct sk_buff *skb,
+			  const struct flow_keys *flow)
+{
+	return flow->basic.ip_proto;
+}
+
+static u32 flow_get_proto_src(const struct sk_buff *skb,
+			      const struct flow_keys *flow)
+{
+	if (flow->ports.ports)
+		return ntohs(flow->ports.src);
+
+	return addr_fold(skb->sk);
+}
+
+static u32 flow_get_proto_dst(const struct sk_buff *skb,
+			      const struct flow_keys *flow)
+{
+	if (flow->ports.ports)
+		return ntohs(flow->ports.dst);
+
+	return addr_fold(skb_dst(skb)) ^ (__force u16)skb_protocol(skb, true);
+}
+
+static u32 flow_get_iif(const struct sk_buff *skb)
+{
+	return skb->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 IS_ENABLED(CONFIG_NF_CONNTRACK)
+	return addr_fold(skb_nfct(skb));
+#else
+	return 0;
+#endif
+}
+
+#if IS_ENABLED(CONFIG_NF_CONNTRACK)
+#define CTTUPLE(skb, member)						\
+({									\
+	enum ip_conntrack_info ctinfo;					\
+	const 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,
+			     const struct flow_keys *flow)
+{
+	switch (skb_protocol(skb, true)) {
+	case htons(ETH_P_IP):
+		return ntohl(CTTUPLE(skb, src.u3.ip));
+	case htons(ETH_P_IPV6):
+		return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
+	}
+fallback:
+	return flow_get_src(skb, flow);
+}
+
+static u32 flow_get_nfct_dst(const struct sk_buff *skb,
+			     const struct flow_keys *flow)
+{
+	switch (skb_protocol(skb, true)) {
+	case htons(ETH_P_IP):
+		return ntohl(CTTUPLE(skb, dst.u3.ip));
+	case htons(ETH_P_IPV6):
+		return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
+	}
+fallback:
+	return flow_get_dst(skb, flow);
+}
+
+static u32 flow_get_nfct_proto_src(const struct sk_buff *skb,
+				   const struct flow_keys *flow)
+{
+	return ntohs(CTTUPLE(skb, src.u.all));
+fallback:
+	return flow_get_proto_src(skb, flow);
+}
+
+static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb,
+				   const struct flow_keys *flow)
+{
+	return ntohs(CTTUPLE(skb, dst.u.all));
+fallback:
+	return flow_get_proto_dst(skb, flow);
+}
+
+static u32 flow_get_rtclassid(const struct sk_buff *skb)
+{
+#ifdef CONFIG_IP_ROUTE_CLASSID
+	if (skb_dst(skb))
+		return skb_dst(skb)->tclassid;
+#endif
+	return 0;
+}
+
+static u32 flow_get_skuid(const struct sk_buff *skb)
+{
+	struct sock *sk = skb_to_full_sk(skb);
+
+	if (sk && sk->sk_socket && sk->sk_socket->file) {
+		kuid_t skuid = sk->sk_socket->file->f_cred->fsuid;
+
+		return from_kuid(&init_user_ns, skuid);
+	}
+	return 0;
+}
+
+static u32 flow_get_skgid(const struct sk_buff *skb)
+{
+	struct sock *sk = skb_to_full_sk(skb);
+
+	if (sk && sk->sk_socket && sk->sk_socket->file) {
+		kgid_t skgid = sk->sk_socket->file->f_cred->fsgid;
+
+		return from_kgid(&init_user_ns, skgid);
+	}
+	return 0;
+}
+
+static u32 flow_get_vlan_tag(const struct sk_buff *skb)
+{
+	u16 tag;
+
+	if (vlan_get_tag(skb, &tag) < 0)
+		return 0;
+	return tag & VLAN_VID_MASK;
+}
+
+static u32 flow_get_rxhash(struct sk_buff *skb)
+{
+	return skb_get_hash(skb);
+}
+
+static u32 flow_key_get(struct sk_buff *skb, int key, struct flow_keys *flow)
+{
+	switch (key) {
+	case FLOW_KEY_SRC:
+		return flow_get_src(skb, flow);
+	case FLOW_KEY_DST:
+		return flow_get_dst(skb, flow);
+	case FLOW_KEY_PROTO:
+		return flow_get_proto(skb, flow);
+	case FLOW_KEY_PROTO_SRC:
+		return flow_get_proto_src(skb, flow);
+	case FLOW_KEY_PROTO_DST:
+		return flow_get_proto_dst(skb, flow);
+	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, flow);
+	case FLOW_KEY_NFCT_DST:
+		return flow_get_nfct_dst(skb, flow);
+	case FLOW_KEY_NFCT_PROTO_SRC:
+		return flow_get_nfct_proto_src(skb, flow);
+	case FLOW_KEY_NFCT_PROTO_DST:
+		return flow_get_nfct_proto_dst(skb, flow);
+	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);
+	case FLOW_KEY_VLAN_TAG:
+		return flow_get_vlan_tag(skb);
+	case FLOW_KEY_RXHASH:
+		return flow_get_rxhash(skb);
+	default:
+		WARN_ON(1);
+		return 0;
+	}
+}
+
+#define FLOW_KEYS_NEEDED ((1 << FLOW_KEY_SRC) | 		\
+			  (1 << FLOW_KEY_DST) |			\
+			  (1 << FLOW_KEY_PROTO) |		\
+			  (1 << FLOW_KEY_PROTO_SRC) |		\
+			  (1 << FLOW_KEY_PROTO_DST) | 		\
+			  (1 << FLOW_KEY_NFCT_SRC) |		\
+			  (1 << FLOW_KEY_NFCT_DST) |		\
+			  (1 << FLOW_KEY_NFCT_PROTO_SRC) |	\
+			  (1 << FLOW_KEY_NFCT_PROTO_DST))
+
+TC_INDIRECT_SCOPE int flow_classify(struct sk_buff *skb,
+				    const struct tcf_proto *tp,
+				    struct tcf_result *res)
+{
+	struct flow_head *head = rcu_dereference_bh(tp->root);
+	struct flow_filter *f;
+	u32 keymask;
+	u32 classid;
+	unsigned int n, key;
+	int r;
+
+	list_for_each_entry_rcu(f, &head->filters, list) {
+		u32 keys[FLOW_KEY_MAX + 1];
+		struct flow_keys flow_keys;
+
+		if (!tcf_em_tree_match(skb, &f->ematches, NULL))
+			continue;
+
+		keymask = f->keymask;
+		if (keymask & FLOW_KEYS_NEEDED)
+			skb_flow_dissect_flow_keys(skb, &flow_keys, 0);
+
+		for (n = 0; n < f->nkeys; n++) {
+			key = ffs(keymask) - 1;
+			keymask &= ~(1 << key);
+			keys[n] = flow_key_get(skb, key, &flow_keys);
+		}
+
+		if (f->mode == FLOW_MODE_HASH)
+			classid = jhash2(keys, f->nkeys, f->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 void flow_perturbation(struct timer_list *t)
+{
+	struct flow_filter *f = timer_container_of(f, t, perturb_timer);
+
+	get_random_bytes(&f->hashrnd, 4);
+	if (f->perturb_period)
+		mod_timer(&f->perturb_timer, jiffies + f->perturb_period);
+}
+
+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]	= NLA_POLICY_MAX(NLA_U32,
+						 31 /* BITS_PER_U32 - 1 */),
+	[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 },
+	[TCA_FLOW_PERTURB]	= { .type = NLA_U32 },
+};
+
+static void __flow_destroy_filter(struct flow_filter *f)
+{
+	timer_shutdown_sync(&f->perturb_timer);
+	tcf_exts_destroy(&f->exts);
+	tcf_em_tree_destroy(&f->ematches);
+	tcf_exts_put_net(&f->exts);
+	kfree(f);
+}
+
+static void flow_destroy_filter_work(struct work_struct *work)
+{
+	struct flow_filter *f = container_of(to_rcu_work(work),
+					     struct flow_filter,
+					     rwork);
+	rtnl_lock();
+	__flow_destroy_filter(f);
+	rtnl_unlock();
+}
+
+static int flow_change(struct net *net, struct sk_buff *in_skb,
+		       struct tcf_proto *tp, unsigned long base,
+		       u32 handle, struct nlattr **tca,
+		       void **arg, u32 flags,
+		       struct netlink_ext_ack *extack)
+{
+	struct flow_head *head = rtnl_dereference(tp->root);
+	struct flow_filter *fold, *fnew;
+	struct nlattr *opt = tca[TCA_OPTIONS];
+	struct nlattr *tb[TCA_FLOW_MAX + 1];
+	unsigned int nkeys = 0;
+	unsigned int perturb_period = 0;
+	u32 baseclass = 0;
+	u32 keymask = 0;
+	u32 mode;
+	int err;
+
+	if (opt == NULL)
+		return -EINVAL;
+
+	err = nla_parse_nested_deprecated(tb, TCA_FLOW_MAX, opt, flow_policy,
+					  NULL);
+	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]);
+
+		nkeys = hweight32(keymask);
+		if (nkeys == 0)
+			return -EINVAL;
+
+		if (fls(keymask) - 1 > FLOW_KEY_MAX)
+			return -EOPNOTSUPP;
+
+		if ((keymask & (FLOW_KEY_SKUID|FLOW_KEY_SKGID)) &&
+		    sk_user_ns(NETLINK_CB(in_skb).sk) != &init_user_ns)
+			return -EOPNOTSUPP;
+	}
+
+	fnew = kzalloc_obj(*fnew, GFP_KERNEL_ACCOUNT);
+	if (!fnew)
+		return -ENOBUFS;
+
+	err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &fnew->ematches);
+	if (err < 0)
+		goto err1;
+
+	err = tcf_exts_init(&fnew->exts, net, TCA_FLOW_ACT, TCA_FLOW_POLICE);
+	if (err < 0)
+		goto err2;
+
+	err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &fnew->exts, flags,
+				extack);
+	if (err < 0)
+		goto err2;
+
+	fold = *arg;
+	if (fold) {
+		err = -EINVAL;
+		if (fold->handle != handle && handle)
+			goto err2;
+
+		/* Copy fold into fnew */
+		fnew->tp = fold->tp;
+		fnew->handle = fold->handle;
+		fnew->nkeys = fold->nkeys;
+		fnew->keymask = fold->keymask;
+		fnew->mode = fold->mode;
+		fnew->mask = fold->mask;
+		fnew->xor = fold->xor;
+		fnew->rshift = fold->rshift;
+		fnew->addend = fold->addend;
+		fnew->divisor = fold->divisor;
+		fnew->baseclass = fold->baseclass;
+		fnew->hashrnd = fold->hashrnd;
+
+		mode = fold->mode;
+		if (tb[TCA_FLOW_MODE])
+			mode = nla_get_u32(tb[TCA_FLOW_MODE]);
+		if (mode != FLOW_MODE_HASH && nkeys > 1)
+			goto err2;
+
+		if (mode == FLOW_MODE_HASH)
+			perturb_period = fold->perturb_period;
+		if (tb[TCA_FLOW_PERTURB]) {
+			if (mode != FLOW_MODE_HASH)
+				goto err2;
+			perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
+		}
+	} 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 (tb[TCA_FLOW_PERTURB]) {
+			if (mode != FLOW_MODE_HASH)
+				goto err2;
+			perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
+		}
+
+		if (TC_H_MAJ(baseclass) == 0) {
+			struct tcf_block *block = tp->chain->block;
+			struct Qdisc *q;
+
+			if (tcf_block_shared(block)) {
+				NL_SET_ERR_MSG(extack,
+					       "Must specify baseclass when attaching flow filter to block");
+				goto err2;
+			}
+
+			q = tcf_block_q(block);
+			baseclass = TC_H_MAKE(q->handle, baseclass);
+		}
+		if (TC_H_MIN(baseclass) == 0)
+			baseclass = TC_H_MAKE(baseclass, 1);
+
+		fnew->handle = handle;
+		fnew->mask  = ~0U;
+		fnew->tp = tp;
+		get_random_bytes(&fnew->hashrnd, 4);
+	}
+
+	timer_setup(&fnew->perturb_timer, flow_perturbation, TIMER_DEFERRABLE);
+
+	tcf_block_netif_keep_dst(tp->chain->block);
+
+	if (tb[TCA_FLOW_KEYS]) {
+		fnew->keymask = keymask;
+		fnew->nkeys   = nkeys;
+	}
+
+	fnew->mode = mode;
+
+	if (tb[TCA_FLOW_MASK])
+		fnew->mask = nla_get_u32(tb[TCA_FLOW_MASK]);
+	if (tb[TCA_FLOW_XOR])
+		fnew->xor = nla_get_u32(tb[TCA_FLOW_XOR]);
+	if (tb[TCA_FLOW_RSHIFT])
+		fnew->rshift = nla_get_u32(tb[TCA_FLOW_RSHIFT]);
+	if (tb[TCA_FLOW_ADDEND])
+		fnew->addend = nla_get_u32(tb[TCA_FLOW_ADDEND]);
+
+	if (tb[TCA_FLOW_DIVISOR])
+		fnew->divisor = nla_get_u32(tb[TCA_FLOW_DIVISOR]);
+	if (baseclass)
+		fnew->baseclass = baseclass;
+
+	fnew->perturb_period = perturb_period;
+	if (perturb_period)
+		mod_timer(&fnew->perturb_timer, jiffies + perturb_period);
+
+	if (!*arg)
+		list_add_tail_rcu(&fnew->list, &head->filters);
+	else
+		list_replace_rcu(&fold->list, &fnew->list);
+
+	*arg = fnew;
+
+	if (fold) {
+		tcf_exts_get_net(&fold->exts);
+		tcf_queue_work(&fold->rwork, flow_destroy_filter_work);
+	}
+	return 0;
+
+err2:
+	tcf_exts_destroy(&fnew->exts);
+	tcf_em_tree_destroy(&fnew->ematches);
+err1:
+	kfree(fnew);
+	return err;
+}
+
+static int flow_delete(struct tcf_proto *tp, void *arg, bool *last,
+		       bool rtnl_held, struct netlink_ext_ack *extack)
+{
+	struct flow_head *head = rtnl_dereference(tp->root);
+	struct flow_filter *f = arg;
+
+	list_del_rcu(&f->list);
+	tcf_exts_get_net(&f->exts);
+	tcf_queue_work(&f->rwork, flow_destroy_filter_work);
+	*last = list_empty(&head->filters);
+	return 0;
+}
+
+static int flow_init(struct tcf_proto *tp)
+{
+	struct flow_head *head;
+
+	head = kzalloc_obj(*head);
+	if (head == NULL)
+		return -ENOBUFS;
+	INIT_LIST_HEAD(&head->filters);
+	rcu_assign_pointer(tp->root, head);
+	net_get_random_once(&flow_keys_secret, sizeof(flow_keys_secret));
+	return 0;
+}
+
+static void flow_destroy(struct tcf_proto *tp, bool rtnl_held,
+			 struct netlink_ext_ack *extack)
+{
+	struct flow_head *head = rtnl_dereference(tp->root);
+	struct flow_filter *f, *next;
+
+	list_for_each_entry_safe(f, next, &head->filters, list) {
+		list_del_rcu(&f->list);
+		if (tcf_exts_get_net(&f->exts))
+			tcf_queue_work(&f->rwork, flow_destroy_filter_work);
+		else
+			__flow_destroy_filter(f);
+	}
+	kfree_rcu(head, rcu);
+}
+
+static void *flow_get(struct tcf_proto *tp, u32 handle)
+{
+	struct flow_head *head = rtnl_dereference(tp->root);
+	struct flow_filter *f;
+
+	list_for_each_entry(f, &head->filters, list)
+		if (f->handle == handle)
+			return f;
+	return NULL;
+}
+
+static int flow_dump(struct net *net, struct tcf_proto *tp, void *fh,
+		     struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
+{
+	struct flow_filter *f = fh;
+	struct nlattr *nest;
+
+	if (f == NULL)
+		return skb->len;
+
+	t->tcm_handle = f->handle;
+
+	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
+	if (nest == NULL)
+		goto nla_put_failure;
+
+	if (nla_put_u32(skb, TCA_FLOW_KEYS, f->keymask) ||
+	    nla_put_u32(skb, TCA_FLOW_MODE, f->mode))
+		goto nla_put_failure;
+
+	if (f->mask != ~0 || f->xor != 0) {
+		if (nla_put_u32(skb, TCA_FLOW_MASK, f->mask) ||
+		    nla_put_u32(skb, TCA_FLOW_XOR, f->xor))
+			goto nla_put_failure;
+	}
+	if (f->rshift &&
+	    nla_put_u32(skb, TCA_FLOW_RSHIFT, f->rshift))
+		goto nla_put_failure;
+	if (f->addend &&
+	    nla_put_u32(skb, TCA_FLOW_ADDEND, f->addend))
+		goto nla_put_failure;
+
+	if (f->divisor &&
+	    nla_put_u32(skb, TCA_FLOW_DIVISOR, f->divisor))
+		goto nla_put_failure;
+	if (f->baseclass &&
+	    nla_put_u32(skb, TCA_FLOW_BASECLASS, f->baseclass))
+		goto nla_put_failure;
+
+	if (f->perturb_period &&
+	    nla_put_u32(skb, TCA_FLOW_PERTURB, f->perturb_period / HZ))
+		goto nla_put_failure;
+
+	if (tcf_exts_dump(skb, &f->exts) < 0)
+		goto nla_put_failure;
+#ifdef CONFIG_NET_EMATCH
+	if (f->ematches.hdr.nmatches &&
+	    tcf_em_tree_dump(skb, &f->ematches, TCA_FLOW_EMATCHES) < 0)
+		goto nla_put_failure;
+#endif
+	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 void flow_walk(struct tcf_proto *tp, struct tcf_walker *arg,
+		      bool rtnl_held)
+{
+	struct flow_head *head = rtnl_dereference(tp->root);
+	struct flow_filter *f;
+
+	list_for_each_entry(f, &head->filters, list) {
+		if (!tc_cls_stats_dump(tp, arg, f))
+			break;
+	}
+}
+
+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,
+	.dump		= flow_dump,
+	.walk		= flow_walk,
+	.owner		= THIS_MODULE,
+};
+MODULE_ALIAS_NET_CLS("flow");
+
+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");