net/sched/act_skbmod.c - linux - Git at Google

 /*
  * net/sched/act_skbmod.c  skb data modifier
  *
  * Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com>
  *
  * 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/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/skbuff.h>
 #include <linux/rtnetlink.h>
 #include <net/netlink.h>
 #include <net/pkt_sched.h>
 #include <net/pkt_cls.h>

 #include <linux/tc_act/tc_skbmod.h>
 #include <net/tc_act/tc_skbmod.h>

 static unsigned int skbmod_net_id;
 static struct tc_action_ops act_skbmod_ops;

 #define MAX_EDIT_LEN ETH_HLEN
 static int tcf_skbmod_act(struct sk_buff *skb, const struct tc_action *a,
 			  struct tcf_result *res)
 {
 	struct tcf_skbmod *d = to_skbmod(a);
 	int action;
 	struct tcf_skbmod_params *p;
 	u64 flags;
 	int err;

 	tcf_lastuse_update(&d->tcf_tm);
 	bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);

 	/* XXX: if you are going to edit more fields beyond ethernet header
 	 * (example when you add IP header replacement or vlan swap)
 	 * then MAX_EDIT_LEN needs to change appropriately
 	*/
 	err = skb_ensure_writable(skb, MAX_EDIT_LEN);
 	if (unlikely(err)) /* best policy is to drop on the floor */
 		goto drop;

 	action = READ_ONCE(d->tcf_action);
 	if (unlikely(action == TC_ACT_SHOT))
 		goto drop;

 	p = rcu_dereference_bh(d->skbmod_p);
 	flags = p->flags;
 	if (flags & SKBMOD_F_DMAC)
 		ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
 	if (flags & SKBMOD_F_SMAC)
 		ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
 	if (flags & SKBMOD_F_ETYPE)
 		eth_hdr(skb)->h_proto = p->eth_type;

 	if (flags & SKBMOD_F_SWAPMAC) {
 		u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
 		/*XXX: I am sure we can come up with more efficient swapping*/
 		ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
 		ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
 		ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
 	}

 	return action;

 drop:
 	qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
 	return TC_ACT_SHOT;
 }

 static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
 	[TCA_SKBMOD_PARMS]		= { .len = sizeof(struct tc_skbmod) },
 	[TCA_SKBMOD_DMAC]		= { .len = ETH_ALEN },
 	[TCA_SKBMOD_SMAC]		= { .len = ETH_ALEN },
 	[TCA_SKBMOD_ETYPE]		= { .type = NLA_U16 },
 };

 static int tcf_skbmod_init(struct net *net, struct nlattr *nla,
 			   struct nlattr *est, struct tc_action **a,
 			   int ovr, int bind, bool rtnl_held,
 			   struct tcf_proto *tp,
 			   struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
 	struct nlattr *tb[TCA_SKBMOD_MAX + 1];
 	struct tcf_skbmod_params *p, *p_old;
 	struct tcf_chain *goto_ch = NULL;
 	struct tc_skbmod *parm;
 	struct tcf_skbmod *d;
 	bool exists = false;
 	u8 *daddr = NULL;
 	u8 *saddr = NULL;
 	u16 eth_type = 0;
 	u32 lflags = 0;
 	int ret = 0, err;

 	if (!nla)
 		return -EINVAL;

 	err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL);
 	if (err < 0)
 		return err;

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

 	if (tb[TCA_SKBMOD_DMAC]) {
 		daddr = nla_data(tb[TCA_SKBMOD_DMAC]);
 		lflags |= SKBMOD_F_DMAC;
 	}

 	if (tb[TCA_SKBMOD_SMAC]) {
 		saddr = nla_data(tb[TCA_SKBMOD_SMAC]);
 		lflags |= SKBMOD_F_SMAC;
 	}

 	if (tb[TCA_SKBMOD_ETYPE]) {
 		eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]);
 		lflags |= SKBMOD_F_ETYPE;
 	}

 	parm = nla_data(tb[TCA_SKBMOD_PARMS]);
 	if (parm->flags & SKBMOD_F_SWAPMAC)
 		lflags = SKBMOD_F_SWAPMAC;

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

 	if (!lflags) {
 		if (exists)
 			tcf_idr_release(*a, bind);
 		else
 			tcf_idr_cleanup(tn, parm->index);
 		return -EINVAL;
 	}

 	if (!exists) {
 		ret = tcf_idr_create(tn, parm->index, est, a,
 				     &act_skbmod_ops, bind, true);
 		if (ret) {
 			tcf_idr_cleanup(tn, parm->index);
 			return ret;
 		}

 		ret = ACT_P_CREATED;
 	} else if (!ovr) {
 		tcf_idr_release(*a, bind);
 		return -EEXIST;
 	}
 	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
 	if (err < 0)
 		goto release_idr;

 	d = to_skbmod(*a);

 	p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
 	if (unlikely(!p)) {
 		err = -ENOMEM;
 		goto put_chain;
 	}

 	p->flags = lflags;

 	if (ovr)
 		spin_lock_bh(&d->tcf_lock);
 	/* Protected by tcf_lock if overwriting existing action. */
 	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
 	p_old = rcu_dereference_protected(d->skbmod_p, 1);

 	if (lflags & SKBMOD_F_DMAC)
 		ether_addr_copy(p->eth_dst, daddr);
 	if (lflags & SKBMOD_F_SMAC)
 		ether_addr_copy(p->eth_src, saddr);
 	if (lflags & SKBMOD_F_ETYPE)
 		p->eth_type = htons(eth_type);

 	rcu_assign_pointer(d->skbmod_p, p);
 	if (ovr)
 		spin_unlock_bh(&d->tcf_lock);

 	if (p_old)
 		kfree_rcu(p_old, rcu);
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);

 	if (ret == ACT_P_CREATED)
 		tcf_idr_insert(tn, *a);
 	return ret;
 put_chain:
 	if (goto_ch)
 		tcf_chain_put_by_act(goto_ch);
 release_idr:
 	tcf_idr_release(*a, bind);
 	return err;
 }

 static void tcf_skbmod_cleanup(struct tc_action *a)
 {
 	struct tcf_skbmod *d = to_skbmod(a);
 	struct tcf_skbmod_params  *p;

 	p = rcu_dereference_protected(d->skbmod_p, 1);
 	if (p)
 		kfree_rcu(p, rcu);
 }

 static int tcf_skbmod_dump(struct sk_buff *skb, struct tc_action *a,
 			   int bind, int ref)
 {
 	struct tcf_skbmod *d = to_skbmod(a);
 	unsigned char *b = skb_tail_pointer(skb);
 	struct tcf_skbmod_params  *p;
 	struct tc_skbmod opt = {
 		.index   = d->tcf_index,
 		.refcnt  = refcount_read(&d->tcf_refcnt) - ref,
 		.bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
 	};
 	struct tcf_t t;

 	spin_lock_bh(&d->tcf_lock);
 	opt.action = d->tcf_action;
 	p = rcu_dereference_protected(d->skbmod_p,
 				      lockdep_is_held(&d->tcf_lock));
 	opt.flags  = p->flags;
 	if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
 		goto nla_put_failure;
 	if ((p->flags & SKBMOD_F_DMAC) &&
 	    nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
 		goto nla_put_failure;
 	if ((p->flags & SKBMOD_F_SMAC) &&
 	    nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
 		goto nla_put_failure;
 	if ((p->flags & SKBMOD_F_ETYPE) &&
 	    nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
 		goto nla_put_failure;

 	tcf_tm_dump(&t, &d->tcf_tm);
 	if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
 		goto nla_put_failure;

 	spin_unlock_bh(&d->tcf_lock);
 	return skb->len;
 nla_put_failure:
 	spin_unlock_bh(&d->tcf_lock);
 	nlmsg_trim(skb, b);
 	return -1;
 }

 static int tcf_skbmod_walker(struct net *net, struct sk_buff *skb,
 			     struct netlink_callback *cb, int type,
 			     const struct tc_action_ops *ops,
 			     struct netlink_ext_ack *extack)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

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

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

 	return tcf_idr_search(tn, a, index);
 }

 static struct tc_action_ops act_skbmod_ops = {
 	.kind		=	"skbmod",
 	.id		=	TCA_ACT_SKBMOD,
 	.owner		=	THIS_MODULE,
 	.act		=	tcf_skbmod_act,
 	.dump		=	tcf_skbmod_dump,
 	.init		=	tcf_skbmod_init,
 	.cleanup	=	tcf_skbmod_cleanup,
 	.walk		=	tcf_skbmod_walker,
 	.lookup		=	tcf_skbmod_search,
 	.size		=	sizeof(struct tcf_skbmod),
 };

 static __net_init int skbmod_init_net(struct net *net)
 {
 	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

 	return tc_action_net_init(tn, &act_skbmod_ops);
 }

 static void __net_exit skbmod_exit_net(struct list_head *net_list)
 {
 	tc_action_net_exit(net_list, skbmod_net_id);
 }

 static struct pernet_operations skbmod_net_ops = {
 	.init = skbmod_init_net,
 	.exit_batch = skbmod_exit_net,
 	.id   = &skbmod_net_id,
 	.size = sizeof(struct tc_action_net),
 };

 MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
 MODULE_DESCRIPTION("SKB data mod-ing");
 MODULE_LICENSE("GPL");

 static int __init skbmod_init_module(void)
 {
 	return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
 }

 static void __exit skbmod_cleanup_module(void)
 {
 	tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
 }

 module_init(skbmod_init_module);
 module_exit(skbmod_cleanup_module);
	/*
	* net/sched/act_skbmod.c skb data modifier
	*
	* Copyright (c) 2016 Jamal Hadi Salim <jhs@mojatatu.com>
	*
	* 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/module.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/skbuff.h>
	#include <linux/rtnetlink.h>
	#include <net/netlink.h>
	#include <net/pkt_sched.h>
	#include <net/pkt_cls.h>

	#include <linux/tc_act/tc_skbmod.h>
	#include <net/tc_act/tc_skbmod.h>

	static unsigned int skbmod_net_id;
	static struct tc_action_ops act_skbmod_ops;

	#define MAX_EDIT_LEN ETH_HLEN
	static int tcf_skbmod_act(struct sk_buff skb, const struct tc_action a,
	struct tcf_result *res)
	{
	struct tcf_skbmod *d = to_skbmod(a);
	int action;
	struct tcf_skbmod_params *p;
	u64 flags;
	int err;

	tcf_lastuse_update(&d->tcf_tm);
	bstats_cpu_update(this_cpu_ptr(d->common.cpu_bstats), skb);

	/* XXX: if you are going to edit more fields beyond ethernet header
	* (example when you add IP header replacement or vlan swap)
	* then MAX_EDIT_LEN needs to change appropriately
	*/
	err = skb_ensure_writable(skb, MAX_EDIT_LEN);
	if (unlikely(err)) /* best policy is to drop on the floor */
	goto drop;

	action = READ_ONCE(d->tcf_action);
	if (unlikely(action == TC_ACT_SHOT))
	goto drop;

	p = rcu_dereference_bh(d->skbmod_p);
	flags = p->flags;
	if (flags & SKBMOD_F_DMAC)
	ether_addr_copy(eth_hdr(skb)->h_dest, p->eth_dst);
	if (flags & SKBMOD_F_SMAC)
	ether_addr_copy(eth_hdr(skb)->h_source, p->eth_src);
	if (flags & SKBMOD_F_ETYPE)
	eth_hdr(skb)->h_proto = p->eth_type;

	if (flags & SKBMOD_F_SWAPMAC) {
	u16 tmpaddr[ETH_ALEN / 2]; /* ether_addr_copy() requirement */
	/XXX: I am sure we can come up with more efficient swapping/
	ether_addr_copy((u8 *)tmpaddr, eth_hdr(skb)->h_dest);
	ether_addr_copy(eth_hdr(skb)->h_dest, eth_hdr(skb)->h_source);
	ether_addr_copy(eth_hdr(skb)->h_source, (u8 *)tmpaddr);
	}

	return action;

	drop:
	qstats_overlimit_inc(this_cpu_ptr(d->common.cpu_qstats));
	return TC_ACT_SHOT;
	}

	static const struct nla_policy skbmod_policy[TCA_SKBMOD_MAX + 1] = {
	[TCA_SKBMOD_PARMS] = { .len = sizeof(struct tc_skbmod) },
	[TCA_SKBMOD_DMAC] = { .len = ETH_ALEN },
	[TCA_SKBMOD_SMAC] = { .len = ETH_ALEN },
	[TCA_SKBMOD_ETYPE] = { .type = NLA_U16 },
	};

	static int tcf_skbmod_init(struct net net, struct nlattr nla,
	struct nlattr est, struct tc_action *a,
	int ovr, int bind, bool rtnl_held,
	struct tcf_proto *tp,
	struct netlink_ext_ack *extack)
	{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);
	struct nlattr *tb[TCA_SKBMOD_MAX + 1];
	struct tcf_skbmod_params p, p_old;
	struct tcf_chain *goto_ch = NULL;
	struct tc_skbmod *parm;
	struct tcf_skbmod *d;
	bool exists = false;
	u8 *daddr = NULL;
	u8 *saddr = NULL;
	u16 eth_type = 0;
	u32 lflags = 0;
	int ret = 0, err;

	if (!nla)
	return -EINVAL;

	err = nla_parse_nested(tb, TCA_SKBMOD_MAX, nla, skbmod_policy, NULL);
	if (err < 0)
	return err;

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

	if (tb[TCA_SKBMOD_DMAC]) {
	daddr = nla_data(tb[TCA_SKBMOD_DMAC]);
	lflags \|= SKBMOD_F_DMAC;
	}

	if (tb[TCA_SKBMOD_SMAC]) {
	saddr = nla_data(tb[TCA_SKBMOD_SMAC]);
	lflags \|= SKBMOD_F_SMAC;
	}

	if (tb[TCA_SKBMOD_ETYPE]) {
	eth_type = nla_get_u16(tb[TCA_SKBMOD_ETYPE]);
	lflags \|= SKBMOD_F_ETYPE;
	}

	parm = nla_data(tb[TCA_SKBMOD_PARMS]);
	if (parm->flags & SKBMOD_F_SWAPMAC)
	lflags = SKBMOD_F_SWAPMAC;

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

	if (!lflags) {
	if (exists)
	tcf_idr_release(*a, bind);
	else
	tcf_idr_cleanup(tn, parm->index);
	return -EINVAL;
	}

	if (!exists) {
	ret = tcf_idr_create(tn, parm->index, est, a,
	&act_skbmod_ops, bind, true);
	if (ret) {
	tcf_idr_cleanup(tn, parm->index);
	return ret;
	}

	ret = ACT_P_CREATED;
	} else if (!ovr) {
	tcf_idr_release(*a, bind);
	return -EEXIST;
	}
	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
	if (err < 0)
	goto release_idr;

	d = to_skbmod(*a);

	p = kzalloc(sizeof(struct tcf_skbmod_params), GFP_KERNEL);
	if (unlikely(!p)) {
	err = -ENOMEM;
	goto put_chain;
	}

	p->flags = lflags;

	if (ovr)
	spin_lock_bh(&d->tcf_lock);
	/* Protected by tcf_lock if overwriting existing action. */
	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
	p_old = rcu_dereference_protected(d->skbmod_p, 1);

	if (lflags & SKBMOD_F_DMAC)
	ether_addr_copy(p->eth_dst, daddr);
	if (lflags & SKBMOD_F_SMAC)
	ether_addr_copy(p->eth_src, saddr);
	if (lflags & SKBMOD_F_ETYPE)
	p->eth_type = htons(eth_type);

	rcu_assign_pointer(d->skbmod_p, p);
	if (ovr)
	spin_unlock_bh(&d->tcf_lock);

	if (p_old)
	kfree_rcu(p_old, rcu);
	if (goto_ch)
	tcf_chain_put_by_act(goto_ch);

	if (ret == ACT_P_CREATED)
	tcf_idr_insert(tn, *a);
	return ret;
	put_chain:
	if (goto_ch)
	tcf_chain_put_by_act(goto_ch);
	release_idr:
	tcf_idr_release(*a, bind);
	return err;
	}

	static void tcf_skbmod_cleanup(struct tc_action *a)
	{
	struct tcf_skbmod *d = to_skbmod(a);
	struct tcf_skbmod_params *p;

	p = rcu_dereference_protected(d->skbmod_p, 1);
	if (p)
	kfree_rcu(p, rcu);
	}

	static int tcf_skbmod_dump(struct sk_buff skb, struct tc_action a,
	int bind, int ref)
	{
	struct tcf_skbmod *d = to_skbmod(a);
	unsigned char *b = skb_tail_pointer(skb);
	struct tcf_skbmod_params *p;
	struct tc_skbmod opt = {
	.index = d->tcf_index,
	.refcnt = refcount_read(&d->tcf_refcnt) - ref,
	.bindcnt = atomic_read(&d->tcf_bindcnt) - bind,
	};
	struct tcf_t t;

	spin_lock_bh(&d->tcf_lock);
	opt.action = d->tcf_action;
	p = rcu_dereference_protected(d->skbmod_p,
	lockdep_is_held(&d->tcf_lock));
	opt.flags = p->flags;
	if (nla_put(skb, TCA_SKBMOD_PARMS, sizeof(opt), &opt))
	goto nla_put_failure;
	if ((p->flags & SKBMOD_F_DMAC) &&
	nla_put(skb, TCA_SKBMOD_DMAC, ETH_ALEN, p->eth_dst))
	goto nla_put_failure;
	if ((p->flags & SKBMOD_F_SMAC) &&
	nla_put(skb, TCA_SKBMOD_SMAC, ETH_ALEN, p->eth_src))
	goto nla_put_failure;
	if ((p->flags & SKBMOD_F_ETYPE) &&
	nla_put_u16(skb, TCA_SKBMOD_ETYPE, ntohs(p->eth_type)))
	goto nla_put_failure;

	tcf_tm_dump(&t, &d->tcf_tm);
	if (nla_put_64bit(skb, TCA_SKBMOD_TM, sizeof(t), &t, TCA_SKBMOD_PAD))
	goto nla_put_failure;

	spin_unlock_bh(&d->tcf_lock);
	return skb->len;
	nla_put_failure:
	spin_unlock_bh(&d->tcf_lock);
	nlmsg_trim(skb, b);
	return -1;
	}

	static int tcf_skbmod_walker(struct net net, struct sk_buff skb,
	struct netlink_callback *cb, int type,
	const struct tc_action_ops *ops,
	struct netlink_ext_ack *extack)
	{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

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

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

	return tcf_idr_search(tn, a, index);
	}

	static struct tc_action_ops act_skbmod_ops = {
	.kind = "skbmod",
	.id = TCA_ACT_SKBMOD,
	.owner = THIS_MODULE,
	.act = tcf_skbmod_act,
	.dump = tcf_skbmod_dump,
	.init = tcf_skbmod_init,
	.cleanup = tcf_skbmod_cleanup,
	.walk = tcf_skbmod_walker,
	.lookup = tcf_skbmod_search,
	.size = sizeof(struct tcf_skbmod),
	};

	static __net_init int skbmod_init_net(struct net *net)
	{
	struct tc_action_net *tn = net_generic(net, skbmod_net_id);

	return tc_action_net_init(tn, &act_skbmod_ops);
	}

	static void __net_exit skbmod_exit_net(struct list_head *net_list)
	{
	tc_action_net_exit(net_list, skbmod_net_id);
	}

	static struct pernet_operations skbmod_net_ops = {
	.init = skbmod_init_net,
	.exit_batch = skbmod_exit_net,
	.id = &skbmod_net_id,
	.size = sizeof(struct tc_action_net),
	};

	MODULE_AUTHOR("Jamal Hadi Salim, <jhs@mojatatu.com>");
	MODULE_DESCRIPTION("SKB data mod-ing");
	MODULE_LICENSE("GPL");

	static int __init skbmod_init_module(void)
	{
	return tcf_register_action(&act_skbmod_ops, &skbmod_net_ops);
	}

	static void __exit skbmod_cleanup_module(void)
	{
	tcf_unregister_action(&act_skbmod_ops, &skbmod_net_ops);
	}

	module_init(skbmod_init_module);
	module_exit(skbmod_cleanup_module);