act_api.c

linux 内核源代码

/*
 * net/sched/act_api.c	Packet action API.
 *
 *		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.
 *
 * Author:	Jamal Hadi Salim
 *
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <net/sch_generic.h>
#include <net/act_api.h>
#include <net/netlink.h>

void tcf_hash_destroy(struct tcf_common *p, struct tcf_hashinfo *hinfo)
{
	unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);
	struct tcf_common **p1p;

	for (p1p = &hinfo->htab[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
		if (*p1p == p) {
			write_lock_bh(hinfo->lock);
			*p1p = p->tcfc_next;
			write_unlock_bh(hinfo->lock);
			gen_kill_estimator(&p->tcfc_bstats,
					   &p->tcfc_rate_est);
			kfree(p);
			return;
		}
	}
	BUG_TRAP(0);
}
EXPORT_SYMBOL(tcf_hash_destroy);

int tcf_hash_release(struct tcf_common *p, int bind,
		     struct tcf_hashinfo *hinfo)
{
	int ret = 0;

	if (p) {
		if (bind)
			p->tcfc_bindcnt--;

		p->tcfc_refcnt--;
		if (p->tcfc_bindcnt <= 0 && p->tcfc_refcnt <= 0) {
			tcf_hash_destroy(p, hinfo);
			ret = 1;
		}
	}
	return ret;
}
EXPORT_SYMBOL(tcf_hash_release);

static int tcf_dump_walker(struct sk_buff *skb, struct netlink_callback *cb,
			   struct tc_action *a, struct tcf_hashinfo *hinfo)
{
	struct tcf_common *p;
	int err = 0, index = -1,i = 0, s_i = 0, n_i = 0;
	struct rtattr *r ;

	read_lock_bh(hinfo->lock);

	s_i = cb->args[0];

	for (i = 0; i < (hinfo->hmask + 1); i++) {
		p = hinfo->htab[tcf_hash(i, hinfo->hmask)];

		for (; p; p = p->tcfc_next) {
			index++;
			if (index < s_i)
				continue;
			a->priv = p;
			a->order = n_i;
			r = (struct rtattr *)skb_tail_pointer(skb);
			RTA_PUT(skb, a->order, 0, NULL);
			err = tcf_action_dump_1(skb, a, 0, 0);
			if (err < 0) {
				index--;
				nlmsg_trim(skb, r);
				goto done;
			}
			r->rta_len = skb_tail_pointer(skb) - (u8 *)r;
			n_i++;
			if (n_i >= TCA_ACT_MAX_PRIO)
				goto done;
		}
	}
done:
	read_unlock_bh(hinfo->lock);
	if (n_i)
		cb->args[0] += n_i;
	return n_i;

rtattr_failure:
	nlmsg_trim(skb, r);
	goto done;
}

static int tcf_del_walker(struct sk_buff *skb, struct tc_action *a,
			  struct tcf_hashinfo *hinfo)
{
	struct tcf_common *p, *s_p;
	struct rtattr *r ;
	int i= 0, n_i = 0;

	r = (struct rtattr *)skb_tail_pointer(skb);
	RTA_PUT(skb, a->order, 0, NULL);
	RTA_PUT(skb, TCA_KIND, IFNAMSIZ, a->ops->kind);
	for (i = 0; i < (hinfo->hmask + 1); i++) {
		p = hinfo->htab[tcf_hash(i, hinfo->hmask)];

		while (p != NULL) {
			s_p = p->tcfc_next;
			if (ACT_P_DELETED == tcf_hash_release(p, 0, hinfo))
				 module_put(a->ops->owner);
			n_i++;
			p = s_p;
		}
	}
	RTA_PUT(skb, TCA_FCNT, 4, &n_i);
	r->rta_len = skb_tail_pointer(skb) - (u8 *)r;

	return n_i;
rtattr_failure:
	nlmsg_trim(skb, r);
	return -EINVAL;
}

int tcf_generic_walker(struct sk_buff *skb, struct netlink_callback *cb,
		       int type, struct tc_action *a)
{
	struct tcf_hashinfo *hinfo = a->ops->hinfo;

	if (type == RTM_DELACTION) {
		return tcf_del_walker(skb, a, hinfo);
	} else if (type == RTM_GETACTION) {
		return tcf_dump_walker(skb, cb, a, hinfo);
	} else {
		printk("tcf_generic_walker: unknown action %d\n", type);
		return -EINVAL;
	}
}
EXPORT_SYMBOL(tcf_generic_walker);

struct tcf_common *tcf_hash_lookup(u32 index, struct tcf_hashinfo *hinfo)
{
	struct tcf_common *p;

	read_lock_bh(hinfo->lock);
	for (p = hinfo->htab[tcf_hash(index, hinfo->hmask)]; p;
	     p = p->tcfc_next) {
		if (p->tcfc_index == index)
			break;
	}
	read_unlock_bh(hinfo->lock);

	return p;
}
EXPORT_SYMBOL(tcf_hash_lookup);

u32 tcf_hash_new_index(u32 *idx_gen, struct tcf_hashinfo *hinfo)
{
	u32 val = *idx_gen;

	do {
		if (++val == 0)
			val = 1;
	} while (tcf_hash_lookup(val, hinfo));

	return (*idx_gen = val);
}
EXPORT_SYMBOL(tcf_hash_new_index);

int tcf_hash_search(struct tc_action *a, u32 index)
{
	struct tcf_hashinfo *hinfo = a->ops->hinfo;
	struct tcf_common *p = tcf_hash_lookup(index, hinfo);

	if (p) {
		a->priv = p;
		return 1;
	}
	return 0;
}
EXPORT_SYMBOL(tcf_hash_search);

struct tcf_common *tcf_hash_check(u32 index, struct tc_action *a, int bind,
				  struct tcf_hashinfo *hinfo)
{
	struct tcf_common *p = NULL;
	if (index && (p = tcf_hash_lookup(index, hinfo)) != NULL) {
		if (bind) {
			p->tcfc_bindcnt++;
			p->tcfc_refcnt++;
		}
		a->priv = p;
	}
	return p;
}
EXPORT_SYMBOL(tcf_hash_check);

struct tcf_common *tcf_hash_create(u32 index, struct rtattr *est, struct tc_action *a, int size, int bind, u32 *idx_gen, struct tcf_hashinfo *hinfo)
{
	struct tcf_common *p = kzalloc(size, GFP_KERNEL);

	if (unlikely(!p))
		return p;
	p->tcfc_refcnt = 1;
	if (bind)
		p->tcfc_bindcnt = 1;

	spin_lock_init(&p->tcfc_lock);
	p->tcfc_index = index ? index : tcf_hash_new_index(idx_gen, hinfo);
	p->tcfc_tm.install = jiffies;
	p->tcfc_tm.lastuse = jiffies;
	if (est)
		gen_new_estimator(&p->tcfc_bstats, &p->tcfc_rate_est,
				  &p->tcfc_lock, est);
	a->priv = (void *) p;
	return p;
}
EXPORT_SYMBOL(tcf_hash_create);

void tcf_hash_insert(struct tcf_common *p, struct tcf_hashinfo *hinfo)
{
	unsigned int h = tcf_hash(p->tcfc_index, hinfo->hmask);

	write_lock_bh(hinfo->lock);
	p->tcfc_next = hinfo->htab[h];
	hinfo->htab[h] = p;
	write_unlock_bh(hinfo->lock);
}
EXPORT_SYMBOL(tcf_hash_insert);

static struct tc_action_ops *act_base = NULL;
static DEFINE_RWLOCK(act_mod_lock);

int tcf_register_action(struct tc_action_ops *act)
{
	struct tc_action_ops *a, **ap;

	write_lock(&act_mod_lock);
	for (ap = &act_base; (a = *ap) != NULL; ap = &a->next) {
		if (act->type == a->type || (strcmp(act->kind, a->kind) == 0)) {
			write_unlock(&act_mod_lock);
			return -EEXIST;
		}
	}
	act->next = NULL;
	*ap = act;
	write_unlock(&act_mod_lock);
	return 0;
}

int tcf_unregister_action(struct tc_action_ops *act)
{
	struct tc_action_ops *a, **ap;
	int err = -ENOENT;

	write_lock(&act_mod_lock);
	for (ap = &act_base; (a = *ap) != NULL; ap = &a->next)
		if (a == act)
			break;
	if (a) {
		*ap = a->next;
		a->next = NULL;
		err = 0;
	}
	write_unlock(&act_mod_lock);
	return err;
}

/* lookup by name */
static struct tc_action_ops *tc_lookup_action_n(char *kind)
{
	struct tc_action_ops *a = NULL;

	if (kind) {
		read_lock(&act_mod_lock);
		for (a = act_base; a; a = a->next) {
			if (strcmp(kind, a->kind) == 0) {
				if (!try_module_get(a->owner)) {
					read_unlock(&act_mod_lock);
					return NULL;
				}
				break;
			}
		}
		read_unlock(&act_mod_lock);
	}
	return a;
}

/* lookup by rtattr */
static struct tc_action_ops *tc_lookup_action(struct rtattr *kind)
{
	struct tc_action_ops *a = NULL;

	if (kind) {
		read_lock(&act_mod_lock);
		for (a = act_base; a; a = a->next) {
			if (rtattr_strcmp(kind, a->kind) == 0) {
				if (!try_module_get(a->owner)) {
					read_unlock(&act_mod_lock);
					return NULL;
				}
				break;
			}
		}
		read_unlock(&act_mod_lock);
	}
	return a;
}

#if 0
/* lookup by id */
static struct tc_action_ops *tc_lookup_action_id(u32 type)
{
	struct tc_action_ops *a = NULL;

	if (type) {
		read_lock(&act_mod_lock);
		for (a = act_base; a; a = a->next) {
			if (a->type == type) {
				if (!try_module_get(a->owner)) {
					read_unlock(&act_mod_lock);
					return NULL;
				}
				break;
			}
		}
		read_unlock(&act_mod_lock);
	}
	return a;
}
#endif

int tcf_action_exec(struct sk_buff *skb, struct tc_action *act,
		    struct tcf_result *res)
{
	struct tc_action *a;
	int ret = -1;

	if (skb->tc_verd & TC_NCLS) {
		skb->tc_verd = CLR_TC_NCLS(skb->tc_verd);
		ret = TC_ACT_OK;
		goto exec_done;
	}
	while ((a = act) != NULL) {
repeat:
		if (a->ops && a->ops->act) {
			ret = a->ops->act(skb, a, res);
			if (TC_MUNGED & skb->tc_verd) {
				/* copied already, allow trampling */
				skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
				skb->tc_verd = CLR_TC_MUNGED(skb->tc_verd);
			}
			if (ret == TC_ACT_REPEAT)
				goto repeat;	/* we need a ttl - JHS */
			if (ret != TC_ACT_PIPE)
				goto exec_done;
		}
		act = a->next;
	}
exec_done:
	return ret;
}

void tcf_action_destroy(struct tc_action *act, int bind)
{
	struct tc_action *a;

	for (a = act; a; a = act) {
		if (a->ops && a->ops->cleanup) {
			if (a->ops->cleanup(a, bind) == ACT_P_DELETED)
				module_put(a->ops->owner);
			act = act->next;
			kfree(a);
		} else { /*FIXME: Remove later - catch insertion bugs*/
			printk("tcf_action_destroy: BUG? destroying NULL ops\n");
			act = act->next;
			kfree(a);
		}
	}
}

int
tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
	int err = -EINVAL;

	if (a->ops == NULL || a->ops->dump == NULL)
		return err;
	return a->ops->dump(skb, a, bind, ref);
}

int
tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
	int err = -EINVAL;
	unsigned char *b = skb_tail_pointer(skb);
	struct rtattr *r;

	if (a->ops == NULL || a->ops->dump == NULL)
		return err;

	RTA_PUT(skb, TCA_KIND, IFNAMSIZ, a->ops->kind);
	if (tcf_action_copy_stats(skb, a, 0))
		goto rtattr_failure;
	r = (struct rtattr *)skb_tail_pointer(skb);
	RTA_PUT(skb, TCA_OPTIONS, 0, NULL);
	if ((err = tcf_action_dump_old(skb, a, bind, ref)) > 0) {
		r->rta_len = skb_tail_pointer(skb) - (u8 *)r;
		return err;
	}

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

int
tcf_action_dump(struct sk_buff *skb, struct tc_action *act, int bind, int ref)
{
	struct tc_action *a;
	int err = -EINVAL;
	unsigned char *b = skb_tail_pointer(skb);
	struct rtattr *r ;

	while ((a = act) != NULL) {
		r = (struct rtattr *)skb_tail_pointer(skb);
		act = a->next;
		RTA_PUT(skb, a->order, 0, NULL);
		err = tcf_action_dump_1(skb, a, bind, ref);
		if (err < 0)
			goto errout;
		r->rta_len = skb_tail_pointer(skb) - (u8 *)r;
	}

	return 0;

rtattr_failure:
	err = -EINVAL;
errout:
	nlmsg_trim(skb, b);
	return err;
}

struct tc_action *tcf_action_init_1(struct rtattr *rta, struct rtattr *est,
				    char *name, int ovr, int bind, int *err)
{
	struct tc_action *a;
	struct tc_action_ops *a_o;
	char act_name[IFNAMSIZ];
	struct rtattr *tb[TCA_ACT_MAX+1];
	struct rtattr *kind;

	*err = -EINVAL;

	if (name == NULL) {
		if (rtattr_parse_nested(tb, TCA_ACT_MAX, rta) < 0)
			goto err_out;
		kind = tb[TCA_ACT_KIND-1];
		if (kind == NULL)
			goto err_out;
		if (rtattr_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ)
			goto err_out;
	} else {
		if (strlcpy(act_name, name, IFNAMSIZ) >= IFNAMSIZ)
			goto err_out;
	}

	a_o = tc_lookup_action_n(act_name);
	if (a_o == NULL) {
#ifdef CONFIG_KMOD
		rtnl_unlock();
		request_module("act_%s", act_name);
		rtnl_lock();

		a_o = tc_lookup_action_n(act_name);

		/* We dropped the RTNL semaphore in order to
		 * perform the module load.  So, even if we
		 * succeeded in loading the module we have to
		 * tell the caller to replay the request.  We
		 * indicate this using -EAGAIN.
		 */
		if (a_o != NULL) {
			*err = -EAGAIN;
			goto err_mod;
		}
#endif
		*err = -ENOENT;
		goto err_out;
	}

	*err = -ENOMEM;
	a = kzalloc(sizeof(*a), GFP_KERNEL);
	if (a == NULL)
		goto err_mod;

	/* backward compatibility for policer */
	if (name == NULL)
		*err = a_o->init(tb[TCA_ACT_OPTIONS-1], est, a, ovr, bind);
	else
		*err = a_o->init(rta, est, a, ovr, bind);
	if (*err < 0)
		goto err_free;

	/* module count goes up only when brand new policy is created
	   if it exists and is only bound to in a_o->init() then
	   ACT_P_CREATED is not returned (a zero is).
	*/
	if (*err != ACT_P_CREATED)
		module_put(a_o->owner);
	a->ops = a_o;

	*err = 0;
	return a;

err_free:
	kfree(a);
err_mod:
	module_put(a_o->owner);
err_out:
	return NULL;
}