/Documentation/

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/*
 * net/sched/cls_u32.c	Ugly (or Universal) 32bit key Packet Classifier.
 *
 *		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.
 *
 * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 *	The filters are packed to hash tables of key nodes
 *	with a set of 32bit key/mask pairs at every node.
 *	Nodes reference next level hash tables etc.
 *
 *	This scheme is the best universal classifier I managed to
 *	invent; it is not super-fast, but it is not slow (provided you
 *	program it correctly), and general enough.  And its relative
 *	speed grows as the number of rules becomes larger.
 *
 *	It seems that it represents the best middle point between
 *	speed and manageability both by human and by machine.
 *
 *	It is especially useful for link sharing combined with QoS;
 *	pure RSVP doesn't need such a general approach and can use
 *	much simpler (and faster) schemes, sort of cls_rsvp.c.
 *
 *	JHS: We should remove the CONFIG_NET_CLS_IND from here
 *	eventually when the meta match extension is made available
 *
 *	nfmark match added by Catalin(ux aka Dino) BOIE <catab at umbrella.ro>
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>

struct tc_u_knode
{
	struct tc_u_knode	*next;
	u32			handle;
	struct tc_u_hnode	*ht_up;
	struct tcf_exts		exts;
#ifdef CONFIG_NET_CLS_IND
	char                     indev[IFNAMSIZ];
#endif
	u8			fshift;
	struct tcf_result	res;
	struct tc_u_hnode	*ht_down;
#ifdef CONFIG_CLS_U32_PERF
	struct tc_u32_pcnt	*pf;
#endif
#ifdef CONFIG_CLS_U32_MARK
	struct tc_u32_mark	mark;
#endif
	struct tc_u32_sel	sel;
};

struct tc_u_hnode
{
	struct tc_u_hnode	*next;
	u32			handle;
	u32			prio;
	struct tc_u_common	*tp_c;
	int			refcnt;
	unsigned		divisor;
	struct tc_u_knode	*ht[1];
};

struct tc_u_common
{
	struct tc_u_hnode	*hlist;
	struct Qdisc		*q;
	int			refcnt;
	u32			hgenerator;
};

static const struct tcf_ext_map u32_ext_map = {
	.action = TCA_U32_ACT,
	.police = TCA_U32_POLICE
};

static __inline__ unsigned u32_hash_fold(__be32 key, struct tc_u32_sel *sel, u8 fshift)
{
	unsigned h = ntohl(key & sel->hmask)>>fshift;

	return h;
}

static int u32_classify(struct sk_buff *skb, struct tcf_proto *tp, struct tcf_result *res)
{
	struct {
		struct tc_u_knode *knode;
		u8		  *ptr;
	} stack[TC_U32_MAXDEPTH];

	struct tc_u_hnode *ht = (struct tc_u_hnode*)tp->root;
	u8 *ptr = skb_network_header(skb);
	struct tc_u_knode *n;
	int sdepth = 0;
	int off2 = 0;
	int sel = 0;
#ifdef CONFIG_CLS_U32_PERF
	int j;
#endif
	int i, r;

next_ht:
	n = ht->ht[sel];

next_knode:
	if (n) {
		struct tc_u32_key *key = n->sel.keys;

#ifdef CONFIG_CLS_U32_PERF
		n->pf->rcnt +=1;
		j = 0;
#endif

#ifdef CONFIG_CLS_U32_MARK
		if ((skb->mark & n->mark.mask) != n->mark.val) {
			n = n->next;
			goto next_knode;
		} else {
			n->mark.success++;
		}
#endif

		for (i = n->sel.nkeys; i>0; i--, key++) {

			if ((*(__be32*)(ptr+key->off+(off2&key->offmask))^key->val)&key->mask) {
				n = n->next;
				goto next_knode;
			}
#ifdef CONFIG_CLS_U32_PERF
			n->pf->kcnts[j] +=1;
			j++;
#endif
		}
		if (n->ht_down == NULL) {
check_terminal:
			if (n->sel.flags&TC_U32_TERMINAL) {

				*res = n->res;
#ifdef CONFIG_NET_CLS_IND
				if (!tcf_match_indev(skb, n->indev)) {
					n = n->next;
					goto next_knode;
				}
#endif
#ifdef CONFIG_CLS_U32_PERF
				n->pf->rhit +=1;
#endif
				r = tcf_exts_exec(skb, &n->exts, res);
				if (r < 0) {
					n = n->next;
					goto next_knode;
				}

				return r;
			}
			n = n->next;
			goto next_knode;
		}

		/* PUSH */
		if (sdepth >= TC_U32_MAXDEPTH)
			goto deadloop;
		stack[sdepth].knode = n;
		stack[sdepth].ptr = ptr;
		sdepth++;

		ht = n->ht_down;
		sel = 0;
		if (ht->divisor)
			sel = ht->divisor&u32_hash_fold(*(__be32*)(ptr+n->sel.hoff), &n->sel,n->fshift);

		if (!(n->sel.flags&(TC_U32_VAROFFSET|TC_U32_OFFSET|TC_U32_EAT)))
			goto next_ht;

		if (n->sel.flags&(TC_U32_OFFSET|TC_U32_VAROFFSET)) {
			off2 = n->sel.off + 3;
			if (n->sel.flags&TC_U32_VAROFFSET)
				off2 += ntohs(n->sel.offmask & *(__be16*)(ptr+n->sel.offoff)) >>n->sel.offshift;
			off2 &= ~3;
		}
		if (n->sel.flags&TC_U32_EAT) {
			ptr += off2;
			off2 = 0;
		}

		if (ptr < skb_tail_pointer(skb))
			goto next_ht;
	}

	/* POP */
	if (sdepth--) {
		n = stack[sdepth].knode;
		ht = n->ht_up;
		ptr = stack[sdepth].ptr;
		goto check_terminal;
	}
	return -1;

deadloop:
	if (net_ratelimit())
		printk("cls_u32: dead loop\n");
	return -1;
}

static __inline__ struct tc_u_hnode *
u32_lookup_ht(struct tc_u_common *tp_c, u32 handle)
{
	struct tc_u_hnode *ht;

	for (ht = tp_c->hlist; ht; ht = ht->next)
		if (ht->handle == handle)
			break;

	return ht;
}

static __inline__ struct tc_u_knode *
u32_lookup_key(struct tc_u_hnode *ht, u32 handle)
{
	unsigned sel;
	struct tc_u_knode *n = NULL;

	sel = TC_U32_HASH(handle);
	if (sel > ht->divisor)
		goto out;

	for (n = ht->ht[sel]; n; n = n->next)
		if (n->handle == handle)
			break;
out:
	return n;
}


static unsigned long u32_get(struct tcf_proto *tp, u32 handle)
{
	struct tc_u_hnode *ht;
	struct tc_u_common *tp_c = tp->data;

	if (TC_U32_HTID(handle) == TC_U32_ROOT)
		ht = tp->root;
	else
		ht = u32_lookup_ht(tp_c, TC_U32_HTID(handle));

	if (!ht)
		return 0;

	if (TC_U32_KEY(handle) == 0)
		return (unsigned long)ht;

	return (unsigned long)u32_lookup_key(ht, handle);
}

static void u32_put(struct tcf_proto *tp, unsigned long f)
{
}

static u32 gen_new_htid(struct tc_u_common *tp_c)
{
	int i = 0x800;

	do {
		if (++tp_c->hgenerator == 0x7FF)
			tp_c->hgenerator = 1;
	} while (--i>0 && u32_lookup_ht(tp_c, (tp_c->hgenerator|0x800)<<20));

	return i > 0 ? (tp_c->hgenerator|0x800)<<20 : 0;
}

static int u32_init(struct tcf_proto *tp)
{
	struct tc_u_hnode *root_ht;
	struct tc_u_common *tp_c;

	tp_c = tp->q->u32_node;

	root_ht = kzalloc(sizeof(*root_ht), GFP_KERNEL);
	if (root_ht == NULL)
		return -ENOBUFS;

	root_ht->divisor = 0;
	root_ht->refcnt++;
	root_ht->handle = tp_c ? gen_new_htid(tp_c) : 0x80000000;
	root_ht->prio = tp->prio;

	if (tp_c == NULL) {
		tp_c = kzalloc(sizeof(*tp_c), GFP_KERNEL);
		if (tp_c == NULL) {
			kfree(root_ht);
			return -ENOBUFS;
		}
		tp_c->q = tp->q;
		tp->q->u32_node = tp_c;
	}

	tp_c->refcnt++;
	root_ht->next = tp_c->hlist;
	tp_c->hlist = root_ht;
	root_ht->tp_c = tp_c;

	tp->root = root_ht;
	tp->data = tp_c;
	return 0;
}

static int u32_destroy_key(struct tcf_proto *tp, struct tc_u_knode *n)
{
	tcf_unbind_filter(tp, &n->res);
	tcf_exts_destroy(tp, &n->exts);
	if (n->ht_down)
		n->ht_down->refcnt--;
#ifdef CONFIG_CLS_U32_PERF
	kfree(n->pf);
#endif
	kfree(n);
	return 0;
}

static int u32_delete_key(struct tcf_proto *tp, struct tc_u_knode* key)
{
	struct tc_u_knode **kp;
	struct tc_u_hnode *ht = key->ht_up;

	if (ht) {
		for (kp = &ht->ht[TC_U32_HASH(key->handle)]; *kp; kp = &(*kp)->next) {
			if (*kp == key) {
				tcf_tree_lock(tp);
				*kp = key->next;
				tcf_tree_unlock(tp);

				u32_destroy_key(tp, key);
				return 0;
			}
		}
	}
	WARN_ON(1);
	return 0;
}

static void u32_clear_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht)
{
	struct tc_u_knode *n;
	unsigned h;

	for (h=0; h<=ht->divisor; h++) {
		while ((n = ht->ht[h]) != NULL) {
			ht->ht[h] = n->next;

			u32_destroy_key(tp, n);
		}
	}
}

static int u32_destroy_hnode(struct tcf_proto *tp, struct tc_u_hnode *ht)
{
	struct tc_u_common *tp_c = tp->data;
	struct tc_u_hnode **hn;

	WARN_ON(ht->refcnt);

	u32_clear_hnode(tp, ht);

	for (hn = &tp_c->hlist; *hn; hn = &(*hn)->next) {
		if (*hn == ht) {
			*hn = ht->next;
			kfree(ht);
			return 0;
		}
	}

	WARN_ON(1);
	return -ENOENT;
}

static void u32_destroy(struct tcf_proto *tp)
{
	struct tc_u_common *tp_c = tp->data;
	struct tc_u_hnode *root_ht = tp->root;

	WARN_ON(root_ht == NULL);

	if (root_ht && --root_ht->refcnt == 0)
		u32_destroy_hnode(tp, root_ht);

	if (--tp_c->refcnt == 0) {
		struct tc_u_hnode *ht;

		tp->q->u32_node = NULL;

		for (ht = tp_c->hlist; ht; ht = ht->next) {
			ht->refcnt--;
			u32_clear_hnode(tp, ht);
		}

		while ((ht = tp_c->hlist) != NULL) {
			tp_c->hlist = ht->next;

			WARN_ON(ht->refcnt != 0);

			kfree(ht);
		}

		kfree(tp_c);
	}

	tp->data = NULL;
}

static int u32_delete(struct tcf_proto *tp, unsigned long arg)
{
	struct tc_u_hnode *ht = (struct tc_u_hnode*)arg;

	if (ht == NULL)
		return 0;

	if (TC_U32_KEY(ht->handle))
		return u32_delete_key(tp, (struct tc_u_knode*)ht);

	if (tp->root == ht)
		return -EINVAL;

	if (ht->refcnt == 1) {
		ht->refcnt--;
		u32_destroy_hnode(tp, ht);
	} else {
		return -EBUSY;
	}

	return 0;
}

static u32 gen_new_kid(struct tc_u_hnode *ht, u32 handle)
{
	struct tc_u_knode *n;
	unsigned i = 0x7FF;

	for (n=ht->ht[TC_U32_HASH(handle)]; n; n = n->next)
		if (i < TC_U32_NODE(n->handle))
			i = TC_U32_NODE(n->handle);
	i++;

	return handle|(i>0xFFF ? 0xFFF : i);
}

static const struct nla_policy u32_policy[TCA_U32_MAX + 1] = {
	[TCA_U32_CLASSID]	= { .type = NLA_U32 },
	[TCA_U32_HASH]		= { .type = NLA_U32 },
	[TCA_U32_LINK]		= { .type = NLA_U32 },
	[TCA_U32_DIVISOR]	= { .type = NLA_U32 },
	[TCA_U32_SEL]		= { .len = sizeof(struct tc_u32_sel) },
	[TCA_U32_INDEV]		= { .type = NLA_STRING, .len = IFNAMSIZ },
	[TCA_U32_MARK]		= { .len = sizeof(struct tc_u32_mark) },
};

static int u32_set_parms(struct tcf_proto *tp, unsigned long base,
			 struct tc_u_hnode *ht,
			 struct tc_u_knode *n, struct nlattr **tb,
			 struct nlattr *est)
{
	int err;
	struct tcf_exts e;

	err = tcf_exts_validate(tp, tb, est, &e, &u32_ext_map);
	if (err < 0)
		return err;

	err = -EINVAL;
	if (tb[TCA_U32_LINK]) {
		u32 handle = nla_get_u32(tb[TCA_U32_LINK]);
		struct tc_u_hnode *ht_down = NULL, *ht_old;

		if (TC_U32_KEY(handle))
			goto errout;

		if (handle) {
			ht_down = u32_lookup_ht(ht->tp_c, handle);

			if (ht_down == NULL)
				goto errout;