linux/net/sched/act_ife.c

/*
 * net/sched/ife.c	Inter-FE action based on ForCES WG InterFE LFB
 *
 *		Refer to:
 *		draft-ietf-forces-interfelfb-03
 *		and
 *		netdev01 paper:
 *		"Distributing Linux Traffic Control Classifier-Action
 *		Subsystem"
 *		Authors: Jamal Hadi Salim and Damascene M. Joachimpillai
 *
 *		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.
 *
 * copyright Jamal Hadi Salim (2015)
 *
*/

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/net_namespace.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <uapi/linux/tc_act/tc_ife.h>
#include <net/tc_act/tc_ife.h>
#include <linux/etherdevice.h>

#define IFE_TAB_MASK 15

static int ife_net_id;
static int max_metacnt = IFE_META_MAX + 1;
static struct tc_action_ops act_ife_ops;

static const struct nla_policy ife_policy[TCA_IFE_MAX + 1] = {
	[TCA_IFE_PARMS] = { .len = sizeof(struct tc_ife)},
	[TCA_IFE_DMAC] = { .len = ETH_ALEN},
	[TCA_IFE_SMAC] = { .len = ETH_ALEN},
	[TCA_IFE_TYPE] = { .type = NLA_U16},
};

/* Caller takes care of presenting data in network order
*/
int ife_tlv_meta_encode(void *skbdata, u16 attrtype, u16 dlen, const void *dval)
{
	u32 *tlv = (u32 *)(skbdata);
	u16 totlen = nla_total_size(dlen);	/*alignment + hdr */
	char *dptr = (char *)tlv + NLA_HDRLEN;
	u32 htlv = attrtype << 16 | dlen;

	*tlv = htonl(htlv);
	memset(dptr, 0, totlen - NLA_HDRLEN);
	memcpy(dptr, dval, dlen);

	return totlen;
}
EXPORT_SYMBOL_GPL(ife_tlv_meta_encode);

int ife_encode_meta_u16(u16 metaval, void *skbdata, struct tcf_meta_info *mi)
{
	u16 edata = 0;

	if (mi->metaval)
		edata = *(u16 *)mi->metaval;
	else if (metaval)
		edata = metaval;

	if (!edata) /* will not encode */
		return 0;

	edata = htons(edata);
	return ife_tlv_meta_encode(skbdata, mi->metaid, 2, &edata);
}
EXPORT_SYMBOL_GPL(ife_encode_meta_u16);

int ife_get_meta_u32(struct sk_buff *skb, struct tcf_meta_info *mi)
{
	if (mi->metaval)
		return nla_put_u32(skb, mi->metaid, *(u32 *)mi->metaval);
	else
		return nla_put(skb, mi->metaid, 0, NULL);
}
EXPORT_SYMBOL_GPL(ife_get_meta_u32);

int ife_check_meta_u32(u32 metaval, struct tcf_meta_info *mi)
{
	if (metaval || mi->metaval)
		return 8; /* T+L+V == 2+2+4 */

	return 0;
}
EXPORT_SYMBOL_GPL(ife_check_meta_u32);

int ife_check_meta_u16(u16 metaval, struct tcf_meta_info *mi)
{
	if (metaval || mi->metaval)
		return 8; /* T+L+(V) == 2+2+(2+2bytepad) */

	return 0;
}
EXPORT_SYMBOL_GPL(ife_check_meta_u16);

int ife_encode_meta_u32(u32 metaval, void *skbdata, struct tcf_meta_info *mi)
{
	u32 edata = metaval;

	if (mi->metaval)
		edata = *(u32 *)mi->metaval;
	else if (metaval)
		edata = metaval;

	if (!edata) /* will not encode */
		return 0;

	edata = htonl(edata);
	return ife_tlv_meta_encode(skbdata, mi->metaid, 4, &edata);
}
EXPORT_SYMBOL_GPL(ife_encode_meta_u32);

int ife_get_meta_u16(struct sk_buff *skb, struct tcf_meta_info *mi)
{
	if (mi->metaval)
		return nla_put_u16(skb, mi->metaid, *(u16 *)mi->metaval);
	else
		return nla_put(skb, mi->metaid, 0, NULL);
}
EXPORT_SYMBOL_GPL(ife_get_meta_u16);

int ife_alloc_meta_u32(struct tcf_meta_info *mi, void *metaval, gfp_t gfp)
{
	mi->metaval = kmemdup(metaval, sizeof(u32), gfp);
	if (!mi->metaval)
		return -ENOMEM;

	return 0;
}
EXPORT_SYMBOL_GPL(ife_alloc_meta_u32);

int ife_alloc_meta_u16(struct tcf_meta_info *mi, void *metaval, gfp_t gfp)
{
	mi->metaval = kmemdup(metaval, sizeof(u16), gfp);
	if (!mi->metaval)
		return -ENOMEM;

	return 0;
}
EXPORT_SYMBOL_GPL(ife_alloc_meta_u16);

void ife_release_meta_gen(struct tcf_meta_info *mi)
{
	kfree(mi->metaval);
}
EXPORT_SYMBOL_GPL(ife_release_meta_gen);

int ife_validate_meta_u32(void *val, int len)
{
	if (len == sizeof(u32))
		return 0;

	return -EINVAL;
}
EXPORT_SYMBOL_GPL(ife_validate_meta_u32);

int ife_validate_meta_u16(void *val, int len)
{
	/* length will not include padding */
	if (len == sizeof(u16))
		return 0;

	return -EINVAL;
}
EXPORT_SYMBOL_GPL(ife_validate_meta_u16);

static LIST_HEAD(ifeoplist);
static DEFINE_RWLOCK(ife_mod_lock);

static struct tcf_meta_ops *find_ife_oplist(u16 metaid)
{
	struct tcf_meta_ops *o;

	read_lock(&ife_mod_lock);
	list_for_each_entry(o, &ifeoplist, list) {
		if (o->metaid == metaid) {
			if (!try_module_get(o->owner))
				o = NULL;
			read_unlock(&ife_mod_lock);
			return o;
		}
	}
	read_unlock(&ife_mod_lock);

	return NULL;
}

int register_ife_op(struct tcf_meta_ops *mops)
{
	struct tcf_meta_ops *m;

	if (!mops->metaid || !mops->metatype || !mops->name ||
	    !mops->check_presence || !mops->encode || !mops->decode ||
	    !mops->get || !mops->alloc)
		return -EINVAL;

	write_lock(&ife_mod_lock);

	list_for_each_entry(m, &ifeoplist, list) {
		if (m->metaid == mops->metaid ||
		    (strcmp(mops->name, m->name) == 0)) {
			write_unlock(&ife_mod_lock);
			return -EEXIST;
		}
	}

	if (!mops->release)
		mops->release = ife_release_meta_gen;

	list_add_tail(&mops->list, &ifeoplist);
	write_unlock(&ife_mod_lock);
	return 0;
}
EXPORT_SYMBOL_GPL(unregister_ife_op);

int unregister_ife_op(struct tcf_meta_ops *mops)
{
	struct tcf_meta_ops *m;
	int err = -ENOENT;

	write_lock(&ife_mod_lock);
	list_for_each_entry(m, &ifeoplist, list) {
		if (m->metaid == mops->metaid) {
			list_del(&mops->list);
			err = 0;
			break;
		}
	}
	write_unlock(&ife_mod_lock);

	return err;
}
EXPORT_SYMBOL_GPL(register_ife_op);

static int ife_validate_metatype(struct tcf_meta_ops *ops, void *val, int len)
{
	int ret = 0;
	/* XXX: unfortunately cant use nla_policy at this point
	* because a length of 0 is valid in the case of
	* "allow". "use" semantics do enforce for proper
	* length and i couldve use nla_policy but it makes it hard
	* to use it just for that..
	*/
	if (ops->validate)
		return ops->validate(val, len);

	if (ops->metatype == NLA_U32)
		ret = ife_validate_meta_u32(val, len);
	else if (ops->metatype == NLA_U16)
		ret = ife_validate_meta_u16(val, len);

	return ret;
}

/* called when adding new meta information
 * under ife->tcf_lock for existing action
*/
static int load_metaops_and_vet(struct tcf_ife_info *ife, u32 metaid,
				void *val, int len, bool exists)
{
	struct tcf_meta_ops *ops = find_ife_oplist(metaid);
	int ret = 0;

	if (!ops) {
		ret = -ENOENT;
#ifdef CONFIG_MODULES
		if (exists)
			spin_unlock_bh(&ife->tcf_lock);
		rtnl_unlock();
		request_module("ifemeta%u", metaid);
		rtnl_lock();
		if (exists)
			spin_lock_bh(&ife->tcf_lock);
		ops = find_ife_oplist(metaid);
#endif
	}

	if (ops) {
		ret = 0;
		if (len)
			ret = ife_validate_metatype(ops, val, len);

		module_put(ops->owner);
	}

	return ret;
}

/* called when adding new meta information
 * under ife->tcf_lock for existing action
*/
static int add_metainfo(struct tcf_ife_info *ife, u32 metaid, void *metaval,
			int len, bool atomic)
{
	struct tcf_meta_info *mi = NULL;
	struct tcf_meta_ops *ops = find_ife_oplist(metaid);
	int ret = 0;

	if (!ops)
		return -ENOENT;

	mi = kzalloc(sizeof(*mi), atomic ? GFP_ATOMIC : GFP_KERNEL);
	if (!mi) {
		/*put back what find_ife_oplist took */
		module_put(ops->owner);
		return -ENOMEM;
	}

	mi->metaid = metaid;
	mi->ops = ops;
	if (len > 0) {
		ret = ops->alloc(mi, metaval, atomic ? GFP_ATOMIC : GFP_KERNEL);
		if (ret != 0) {
			kfree(mi);
			module_put(ops->owner);
			return ret;
		}
	}

	list_add_tail(&mi->metalist, &ife->metalist);

	return ret;
}

static int use_all_metadata(struct tcf_ife_info *ife)
{
	struct tcf_meta_ops *o;
	int rc = 0;
	int installed = 0;

	read_lock(&ife_mod_lock);
	list_for_each_entry(o, &ifeoplist, list) {
		rc = add_metainfo(ife, o->metaid, NULL, 0, true);
		if (rc == 0)
			installed += 1;
	}
	read_unlock(&ife_mod_lock);

	if (installed)
		return 0;
	else
		return -EINVAL;
}

static int dump_metalist(struct sk_buff *skb, struct tcf_ife_info *ife)
{
	struct tcf_meta_info *e;
	struct nlattr *nest;
	unsigned char *b = skb_tail_pointer(skb);
	int total_encoded = 0;

	/*can only happen on decode */
	if (list_empty(&ife->metalist))
		return 0;

	nest = nla_nest_start(skb, TCA_IFE_METALST);
	if (!nest)
		goto out_nlmsg_trim;

	list_for_each_entry(e, &ife->metalist, metalist) {
		if (!e->ops->get(skb, e))
			total_encoded += 1;
	}

	if (!total_encoded)
		goto out_nlmsg_trim;

	nla_nest_end(skb, nest);

	return 0;

out_nlmsg_trim:
	nlmsg_trim(skb, b);
	return -1;
}

/* under ife->tcf_lock */
static void _tcf_ife_cleanup(struct tc_action *a, int bind)
{
	struct tcf_ife_info *ife = to_ife(a);
	struct tcf_meta_info *e, *n;

	list_for_each_entry_safe(e, n, &ife->metalist, metalist) {
		module_put(e->ops->owner);
		list_del(&e->metalist);
		if (e->metaval) {
			if (e->ops->release)
				e->ops->release(e);
			else
				kfree(e->metaval);
		}
		kfree(e);
	}
}

static void tcf_ife_cleanup(struct tc_action *a, int bind)
{
	struct tcf_ife_info *ife = to_ife(a);

	spin_lock_bh(&ife->tcf_lock);
	_tcf_ife_cleanup(a, bind);
	spin_unlock_bh(&ife->tcf_lock);
}

/* under ife->tcf_lock for existing action */
static int populate_metalist(struct tcf_ife_info *ife, struct nlattr **tb,
			     bool exists)
{
	int len = 0;
	int rc = 0;
	int i = 0;
	void *val;

	for (i = 1; i < max_metacnt; i++) {
		if (tb[i]) {
			val = nla_data(tb[i]);
			len = nla_len(tb[i]);

			rc = load_metaops_and_vet(ife, i, val, len, exists);
			if (rc != 0)
				return rc;

			rc = add_metainfo(ife, i, val, len, exists);
			if (rc)
				return rc;
		}
	}

	return rc;
}

static int tcf_ife_init(struct net *net, struct nlattr *nla,
			struct nlattr *est, struct tc_action **a,
			int ovr, int bind)
{
	struct tc_action_net *tn = net_generic(net, ife_net_id);
	struct nlattr *tb[TCA_IFE_MAX + 1];
	struct nlattr *tb2[IFE_META_MAX + 1];
	struct tcf_ife_info *ife;
	struct tc_ife *parm;
	u16 ife_type = 0;
	u8 *daddr = NULL;
	u8 *saddr = NULL;
	bool exists = false;
	int ret = 0;
	int err;

	err = nla_parse_nested(tb, TCA_IFE_MAX, nla, ife_policy);
	if (err < 0)
		return err;

	if (!tb[TCA_IFE_PARMS])
		return -EINVAL;

	parm = nla_data(tb[TCA_IFE_PARMS]);

	exists = tcf_hash_check(tn, parm->index, a, bind);
	if (exists && bind)
		return 0;

	if (parm->flags & IFE_ENCODE) {
		/* Until we get issued the ethertype, we cant have
		 * a default..
		**/
		if (!tb[TCA_IFE_TYPE]) {
			if (exists)
				tcf_hash_release(*a, bind);
			pr_info("You MUST pass etherype for encoding\n");
			return -EINVAL;
		}
	}

	if (!exists) {
		ret = tcf_hash_create(tn, parm->index, est, a, &act_ife_ops,
				      bind, false);
		if (ret)
			return ret;
		ret = ACT_P_CREATED;
	} else {
		tcf_hash_release(*a, bind);
		if (!ovr)
			return -EEXIST;
	}

	ife = to_ife(*a);
	ife->flags = parm->flags;

	if (parm->flags & IFE_ENCODE) {
		ife_type = nla_get_u16(tb[TCA_IFE_TYPE]);
		if (tb[TCA_IFE_DMAC])
			daddr = nla_data(tb[TCA_IFE_DMAC]);
		if (tb[TCA_IFE_SMAC])
			saddr = nla_data(tb[TCA_IFE_SMAC]);
	}

	if (exists)
		spin_lock_bh(&ife->tcf_lock);
	ife->tcf_action = parm->action;

	if (parm->flags & IFE_ENCODE) {
		if (daddr)
			ether_addr_copy(ife->eth_dst, daddr);
		else
			eth_zero_addr(ife->eth_dst);

		if (saddr)
			ether_addr_copy(ife->eth_src, saddr);
		else
			eth_zero_addr(ife->eth_src);

		ife->eth_type = ife_type;
	}

	if (ret == ACT_P_CREATED)
		INIT_LIST_HEAD(&ife->metalist);

	if (tb[TCA_IFE_METALST]) {
		err = nla_parse_nested(tb2, IFE_META_MAX, tb[TCA_IFE_METALST],
				       NULL);
		if (err) {
metadata_parse_err:
			if (exists)
				tcf_hash_release(*a, bind);
			if (ret == ACT_P_CREATED)
				_tcf_ife_cleanup(*a, bind);

			if (exists)
				spin_unlock_bh(&ife->tcf_lock);
			return err;
		}

		err = populate_metalist(ife, tb2, exists);
		if (err)
			goto metadata_parse_err;

	} else {
		/* if no passed metadata allow list or passed allow-all
		 * then here we process by adding as many supported metadatum
		 * as we can. You better have at least one else we are
		 * going to bail out
		 */
		err = use_all_metadata(ife);
		if (err) {
			if (ret == ACT_P_CREATED)
				_tcf_ife_cleanup(*a, bind);

			if (exists)
				spin_unlock_bh(&ife->tcf_lock);
			return err;
		}
	}

	if (exists)
		spin_unlock_bh(&ife->tcf_lock);

	if (ret == ACT_P_CREATED)
		tcf_hash_insert(tn, *a);

	return ret;
}

static int tcf_ife_dump(struct sk_buff *skb, struct tc_action *a, int bind,
			int ref)
{
	unsigned char *b = skb_tail_pointer(skb);
	struct tcf_ife_info *ife = to_ife(a);
	struct tc_ife opt = {
		.index = ife->tcf_index,
		.refcnt = ife->tcf_refcnt - ref,
		.bindcnt = ife->tcf_bindcnt - bind,
		.action = ife->tcf_action,
		.flags = ife->flags,
	};
	struct tcf_t t;

	if (nla_put(skb, TCA_IFE_PARMS, sizeof(opt), &opt))
		goto nla_put_failure;

	tcf_tm_dump(&t, &ife->tcf_tm);
	if (nla_put_64bit(skb, TCA_IFE_TM, sizeof(t), &t, TCA_IFE_PAD))
		goto nla_put_failure;

	if (!is_zero_ether_addr(ife->eth_dst)) {
		if (nla_put(skb, TCA_IFE_DMAC, ETH_ALEN, ife->eth_dst))
			goto nla_put_failure;
	}

	if (!is_zero_ether_addr(ife->eth_src)) {
		if (nla_put(skb, TCA_IFE_SMAC, ETH_ALEN, ife->eth_src))
			goto nla_put_failure;
	}

	if (nla_put(skb, TCA_IFE_TYPE, 2, &ife->eth_type))
		goto nla_put_failure;

	if (dump_metalist(skb, ife)) {
		/*ignore failure to dump metalist */
		pr_info("Failed to dump metalist\n");
	}

	return skb->len;

nla_put_failure:
	nlmsg_trim(skb, b);
	return -1;
}

int find_decode_metaid(struct sk_buff *skb, struct tcf_ife_info *ife,
		       u16 metaid, u16 mlen, void *mdata)
{
	struct tcf_meta_info *e;

	/* XXX: use hash to speed up */
	list_for_each_entry(e, &ife->metalist, metalist) {
		if (metaid == e->metaid) {
			if (e->ops) {
				/* We check for decode presence already */
				return e->ops->decode(skb, mdata, mlen);
			}
		}
	}

	return 0;
}

struct ifeheadr {
	__be16 metalen;
	u8 tlv_data[];
};

struct meta_tlvhdr {
	__be16 type;
	__be16 len;
};

static int tcf_ife_decode(struct sk_buff *skb, const struct tc_action *a,
			  struct tcf_result *res)
{
	struct tcf_ife_info *ife = to_ife(a);
	int action = ife->tcf_action;
	struct ifeheadr *ifehdr = (struct ifeheadr *)skb->data;
	u16 ifehdrln = ifehdr->metalen;
	struct meta_tlvhdr *tlv = (struct meta_tlvhdr *)(ifehdr->tlv_data);

	spin_lock(&ife->tcf_lock);
	bstats_update(&ife->tcf_bstats, skb);
	tcf_lastuse_update(&ife->tcf_tm);
	spin_unlock(&ife->tcf_lock);

	ifehdrln = ntohs(ifehdrln);
	if (unlikely(!pskb_may_pull(skb, ifehdrln))) {
		spin_lock(&ife->tcf_lock);
		ife->tcf_qstats.drops++;
		spin_unlock(&ife->tcf_lock);
		return TC_ACT_SHOT;
	}

	skb_set_mac_header(skb, ifehdrln);
	__skb_pull(skb, ifehdrln);
	skb->protocol = eth_type_trans(skb, skb->dev);
	ifehdrln -= IFE_METAHDRLEN;

	while (ifehdrln > 0) {
		u8 *tlvdata = (u8 *)tlv;
		u16 mtype = tlv->type;
		u16 mlen = tlv->len;
		u16 alen;

		mtype = ntohs(mtype);
		mlen = ntohs(mlen);
		alen = NLA_ALIGN(mlen);

		if (find_decode_metaid(skb, ife, mtype, (mlen - NLA_HDRLEN),
				       (void *)(tlvdata + NLA_HDRLEN))) {
			/* abuse overlimits to count when we receive metadata
			 * but dont have an ops for it
			 */
			pr_info_ratelimited("Unknown metaid %d alnlen %d\n",
					    mtype, mlen);
			ife->tcf_qstats.overlimits++;
		}

		tlvdata += alen;
		ifehdrln -= alen;
		tlv = (struct meta_tlvhdr *)tlvdata;
	}

	skb_reset_network_header(skb);
	return action;
}

/*XXX: check if we can do this at install time instead of current
 * send data path
**/
static int ife_get_sz(struct sk_buff *skb, struct tcf_ife_info *ife)
{
	struct tcf_meta_info *e, *n;
	int tot_run_sz = 0, run_sz = 0;

	list_for_each_entry_safe(e, n, &ife->metalist, metalist) {
		if (e->ops->check_presence) {
			run_sz = e->ops->check_presence(skb, e);
			tot_run_sz += run_sz;
		}
	}

	return tot_run_sz;
}

static int tcf_ife_encode(struct sk_buff *skb, const struct tc_action *a,
			  struct tcf_result *res)
{
	struct tcf_ife_info *ife = to_ife(a);
	int action = ife->tcf_action;
	struct ethhdr *oethh;	/* outer ether header */
	struct ethhdr *iethh;	/* inner eth header */
	struct tcf_meta_info *e;
	/*
	   OUTERHDR:TOTMETALEN:{TLVHDR:Metadatum:TLVHDR..}:ORIGDATA
	   where ORIGDATA = original ethernet header ...
	 */
	u16 metalen = ife_get_sz(skb, ife);
	int hdrm = metalen + skb->dev->hard_header_len + IFE_METAHDRLEN;
	unsigned int skboff = skb->dev->hard_header_len;
	u32 at = G_TC_AT(skb->tc_verd);
	int new_len = skb->len + hdrm;
	bool exceed_mtu = false;
	int err;

	if (at & AT_EGRESS) {
		if (new_len > skb->dev->mtu)
			exceed_mtu = true;
	}

	spin_lock(&ife->tcf_lock);
	bstats_update(&ife->tcf_bstats, skb);
	tcf_lastuse_update(&ife->tcf_tm);

	if (!metalen) {		/* no metadata to send */
		/* abuse overlimits to count when we allow packet
		 * with no metadata
		 */
		ife->tcf_qstats.overlimits++;
		spin_unlock(&ife->tcf_lock);
		return action;
	}
	/* could be stupid policy setup or mtu config
	 * so lets be conservative.. */
	if ((action == TC_ACT_SHOT) || exceed_mtu) {
		ife->tcf_qstats.drops++;
		spin_unlock(&ife->tcf_lock);
		return TC_ACT_SHOT;
	}

	iethh = eth_hdr(skb);

	err = skb_cow_head(skb, hdrm);
	if (unlikely(err)) {
		ife->tcf_qstats.drops++;
		spin_unlock(&ife->tcf_lock);
		return TC_ACT_SHOT;
	}

	if (!(at & AT_EGRESS))
		skb_push(skb, skb->dev->hard_header_len);

	__skb_push(skb, hdrm);
	memcpy(skb->data, iethh, skb->mac_len);
	skb_reset_mac_header(skb);
	oethh = eth_hdr(skb);

	/*total metadata length */
	metalen += IFE_METAHDRLEN;
	metalen = htons(metalen);
	memcpy((skb->data + skboff), &metalen, IFE_METAHDRLEN);
	skboff += IFE_METAHDRLEN;

	/* XXX: we dont have a clever way of telling encode to
	 * not repeat some of the computations that are done by
	 * ops->presence_check...
	 */
	list_for_each_entry(e, &ife->metalist, metalist) {
		if (e->ops->encode) {
			err = e->ops->encode(skb, (void *)(skb->data + skboff),
					     e);
		}
		if (err < 0) {
			/* too corrupt to keep around if overwritten */
			ife->tcf_qstats.drops++;
			spin_unlock(&ife->tcf_lock);
			return TC_ACT_SHOT;
		}
		skboff += err;
	}

	if (!is_zero_ether_addr(ife->eth_src))
		ether_addr_copy(oethh->h_source, ife->eth_src);
	else
		ether_addr_copy(oethh->h_source, iethh->h_source);
	if (!is_zero_ether_addr(ife->eth_dst))
		ether_addr_copy(oethh->h_dest, ife->eth_dst);
	else
		ether_addr_copy(oethh->h_dest, iethh->h_dest);
	oethh->h_proto = htons(ife->eth_type);

	if (!(at & AT_EGRESS))
		skb_pull(skb, skb->dev->hard_header_len);

	spin_unlock(&ife->tcf_lock);

	return action;
}

static int tcf_ife_act(struct sk_buff *skb, const struct tc_action *a,
		       struct tcf_result *res)
{
	struct tcf_ife_info *ife = to_ife(a);

	if (ife->flags & IFE_ENCODE)
		return tcf_ife_encode(skb, a, res);

	if (!(ife->flags & IFE_ENCODE))
		return tcf_ife_decode(skb, a, res);

	pr_info_ratelimited("unknown failure(policy neither de/encode\n");
	spin_lock(&ife->tcf_lock);
	bstats_update(&ife->tcf_bstats, skb);
	tcf_lastuse_update(&ife->tcf_tm);
	ife->tcf_qstats.drops++;
	spin_unlock(&ife->tcf_lock);

	return TC_ACT_SHOT;
}

static int tcf_ife_walker(struct net *net, struct sk_buff *skb,
			  struct netlink_callback *cb, int type,
			  const struct tc_action_ops *ops)
{
	struct tc_action_net *tn = net_generic(net, ife_net_id);

	return tcf_generic_walker(tn, skb, cb, type, ops);
}

static int tcf_ife_search(struct net *net, struct tc_action **a, u32 index)
{
	struct tc_action_net *tn = net_generic(net, ife_net_id);

	return tcf_hash_search(tn, a, index);
}

static struct tc_action_ops act_ife_ops = {
	.kind = "ife",
	.type = TCA_ACT_IFE,
	.owner = THIS_MODULE,
	.act = tcf_ife_act,
	.dump = tcf_ife_dump,
	.cleanup = tcf_ife_cleanup,
	.init = tcf_ife_init,
	.walk = tcf_ife_walker,
	.lookup = tcf_ife_search,
	.size =	sizeof(struct tcf_ife_info),
};

static __net_init int ife_init_net(struct net *net)
{
	struct tc_action_net *tn = net_generic(net, ife_net_id);

	return tc_action_net_init(tn, &act_ife_ops, IFE_TAB_MASK);
}

static void __net_exit ife_exit_net(struct net *net)
{
	struct tc_action_net *tn = net_generic(net, ife_net_id);

	tc_action_net_exit(tn);
}

static struct pernet_operations ife_net_ops = {
	.init = ife_init_net,
	.exit = ife_exit_net,
	.id   = &ife_net_id,
	.size = sizeof(struct tc_action_net),
};

static int __init ife_init_module(void)
{
	return tcf_register_action(&act_ife_ops, &ife_net_ops);
}

static void __exit ife_cleanup_module(void)
{
	tcf_unregister_action(&act_ife_ops, &ife_net_ops);
}

module_init(ife_init_module);
module_exit(ife_cleanup_module);

MODULE_AUTHOR("Jamal Hadi Salim(2015)");
MODULE_DESCRIPTION("Inter-FE LFB action");
MODULE_LICENSE("GPL");