cls_rsvp.h

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/*
 * net/sched/cls_rsvp.h	Template file for RSVPv[46] classifiers.
 *
 *		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, <[e-mail]>
 */

/*
   Comparing to general packet classification problem,
   RSVP needs only sevaral relatively simple rules:

   * (dst, protocol) are always specified,
     so that we are able to hash them.
   * src may be exact, or may be wildcard, so that
     we can keep a hash table plus one wildcard entry.
   * source port (or flow label) is important only if src is given.

   IMPLEMENTATION.

   We use a two level hash table: The top level is keyed by
   destination address and protocol ID, every bucket contains a list
   of "rsvp sessions", identified by destination address, protocol and
   DPI(="Destination Port ID"): triple (key, mask, offset).

   Every bucket has a smaller hash table keyed by source address
   (cf. RSVP flowspec) and one wildcard entry for wildcard reservations.
   Every bucket is again a list of "RSVP flows", selected by
   source address and SPI(="Source Port ID" here rather than
   "security parameter index"): triple (key, mask, offset).


   NOTE 1. All the packets with IPv6 extension headers (but AH and ESP)
   and all fragmented packets go to the best-effort traffic class.


   NOTE 2. Two "port id"'s seems to be redundant, rfc2207 requires
   only one "Generalized Port Identifier". So that for classic
   ah, esp (and udp,tcp) both *pi should coincide or one of them
   should be wildcard.

   At first sight, this redundancy is just a waste of CPU
   resources. But DPI and SPI add the possibility to assign different
   priorities to GPIs. Look also at note 4 about tunnels below.


   NOTE 3. One complication is the case of tunneled packets.
   We implement it as following: if the first lookup
   matches a special session with "tunnelhdr" value not zero,
   flowid doesn't contain the true flow ID, but the tunnel ID (1...255).
   In this case, we pull tunnelhdr bytes and restart lookup
   with tunnel ID added to the list of keys. Simple and stupid 8)8)
   It's enough for PIMREG and IPIP.


   NOTE 4. Two GPIs make it possible to parse even GRE packets.
   F.e. DPI can select ETH_P_IP (and necessary flags to make
   tunnelhdr correct) in GRE protocol field and SPI matches
   GRE key. Is it not nice? 8)8)


   Well, as result, despite its simplicity, we get a pretty
   powerful classification engine.  */

#include <linux/config.h>

struct rsvp_head
{
	u32			tmap[256/32];
	u32			hgenerator;
	u8			tgenerator;
	struct rsvp_session	*ht[256];
};

struct rsvp_session
{
	struct rsvp_session	*next;
	u32			dst[RSVP_DST_LEN];
	struct tc_rsvp_gpi 	dpi;
	u8			protocol;
	u8			tunnelid;
	/* 16 (src,sport) hash slots, and one wildcard source slot */
	struct rsvp_filter	*ht[16+1];
};


struct rsvp_filter
{
	struct rsvp_filter	*next;
	u32			src[RSVP_DST_LEN];
	struct tc_rsvp_gpi	spi;
	u8			tunnelhdr;

	struct tcf_result	res;
#ifdef CONFIG_NET_CLS_POLICE
	struct tcf_police	*police;
#endif

	u32			handle;
	struct rsvp_session	*sess;
};

static __inline__ unsigned hash_dst(u32 *dst, u8 protocol, u8 tunnelid)
{
	unsigned h = dst[RSVP_DST_LEN-1];
	h ^= h>>16;
	h ^= h>>8;
	return (h ^ protocol ^ tunnelid) & 0xFF;
}

static __inline__ unsigned hash_src(u32 *src)
{
	unsigned h = src[RSVP_DST_LEN-1];
	h ^= h>>16;
	h ^= h>>8;
	h ^= h>>4;
	return h & 0xF;
}

#ifdef CONFIG_NET_CLS_POLICE
#define RSVP_POLICE() \
if (f->police) { \
	int pol_res = tcf_police(skb, f->police); \
	if (pol_res < 0) continue; \
	if (pol_res) return pol_res; \
}
#else
#define RSVP_POLICE()
#endif


static int rsvp_classify(struct sk_buff *skb, struct tcf_proto *tp,
			 struct tcf_result *res)
{
	struct rsvp_session **sht = ((struct rsvp_head*)tp->root)->ht;
	struct rsvp_session *s;
	struct rsvp_filter *f;
	unsigned h1, h2;
	u32 *dst, *src;
	u8 protocol;
	u8 tunnelid = 0;
	u8 *xprt;
#if RSVP_DST_LEN == 4
	struct ipv6hdr *nhptr = skb->nh.ipv6h;
#else
	struct iphdr *nhptr = skb->nh.iph;
#endif

#if !defined( __i386__) && !defined(__mc68000__)
	if ((unsigned long)nhptr & 3)
		return -1;
#endif

restart:

#if RSVP_DST_LEN == 4
	src = &nhptr->saddr.s6_addr32[0];
	dst = &nhptr->daddr.s6_addr32[0];
	protocol = nhptr->nexthdr;
	xprt = ((u8*)nhptr) + sizeof(struct ipv6hdr);
#else
	src = &nhptr->saddr;
	dst = &nhptr->daddr;
	protocol = nhptr->protocol;
	xprt = ((u8*)nhptr) + (nhptr->ihl<<2);
	if (nhptr->frag_off&__constant_htons(IP_MF|IP_OFFSET))
		return -1;
#endif

	h1 = hash_dst(dst, protocol, tunnelid);
	h2 = hash_src(src);

	for (s = sht[h1]; s; s = s->next) {
		if (dst[RSVP_DST_LEN-1] == s->dst[RSVP_DST_LEN-1] &&
		    protocol == s->protocol &&
		    !(s->dpi.mask & (*(u32*)(xprt+s->dpi.offset)^s->dpi.key))
#if RSVP_DST_LEN == 4
		    && dst[0] == s->dst[0]
		    && dst[1] == s->dst[1]
		    && dst[2] == s->dst[2]
#endif
		    && tunnelid == s->tunnelid) {

			for (f = s->ht[h2]; f; f = f->next) {
				if (src[RSVP_DST_LEN-1] == f->src[RSVP_DST_LEN-1] &&
				    !(f->spi.mask & (*(u32*)(xprt+f->spi.offset)^f->spi.key))
#if RSVP_DST_LEN == 4
				    && src[0] == f->src[0]
				    && src[1] == f->src[1]
				    && src[2] == f->src[2]
#endif
				    ) {
					*res = f->res;

					RSVP_POLICE();

matched:
					if (f->tunnelhdr == 0)
						return 0;

					tunnelid = f->res.classid;
					nhptr = (void*)(xprt + f->tunnelhdr - sizeof(*nhptr));
					goto restart;
				}
			}

			/* And wildcard bucket... */
			for (f = s->ht[16]; f; f = f->next) {
				*res = f->res;
				RSVP_POLICE();
				goto matched;
			}
			return -1;
		}
	}
	return -1;
}

static unsigned long rsvp_get(struct tcf_proto *tp, u32 handle)
{
	struct rsvp_session **sht = ((struct rsvp_head*)tp->root)->ht;
	struct rsvp_session *s;
	struct rsvp_filter *f;
	unsigned h1 = handle&0xFF;
	unsigned h2 = (handle>>8)&0xFF;

	if (h2 > 16)
		return 0;

	for (s = sht[h1]; s; s = s->next) {
		for (f = s->ht[h2]; f; f = f->next) {
			if (f->handle == handle)
				return (unsigned long)f;
		}
	}
	return 0;
}

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

static int rsvp_init(struct tcf_proto *tp)
{
	struct rsvp_head *data;

	MOD_INC_USE_COUNT;
	data = kmalloc(sizeof(struct rsvp_head), GFP_KERNEL);
	if (data) {
		memset(data, 0, sizeof(struct rsvp_head));
		tp->root = data;
		return 0;
	}
	MOD_DEC_USE_COUNT;
	return -ENOBUFS;
}

static void rsvp_destroy(struct tcf_proto *tp)
{
	struct rsvp_head *data = xchg(&tp->root, NULL);
	struct rsvp_session **sht;
	int h1, h2;

	if (data == NULL)
		return;

	sht = data->ht;

	for (h1=0; h1<256; h1++) {
		struct rsvp_session *s;

		while ((s = sht[h1]) != NULL) {
			sht[h1] = s->next;

			for (h2=0; h2<=16; h2++) {
				struct rsvp_filter *f;

				while ((f = s->ht[h2]) != NULL) {
					unsigned long cl;

					s->ht[h2] = f->next;
					if ((cl = __cls_set_class(&f->res.class, 0)) != 0)
						tp->q->ops->cl_ops->unbind_tcf(tp->q, cl);
#ifdef CONFIG_NET_CLS_POLICE
					tcf_police_release(f->police);
#endif
					kfree(f);
				}
			}
			kfree(s);
		}
	}
	kfree(data);
	MOD_DEC_USE_COUNT;
}

static int rsvp_delete(struct tcf_proto *tp, unsigned long arg)
{
	struct rsvp_filter **fp, *f = (struct rsvp_filter*)arg;
	unsigned h = f->handle;
	struct rsvp_session **sp;
	struct rsvp_session *s = f->sess;
	int i;

	for (fp = &s->ht[(h>>8)&0xFF]; *fp; fp = &(*fp)->next) {
		if (*fp == f) {
			unsigned long cl;


			tcf_tree_lock(tp);
			*fp = f->next;
			tcf_tree_unlock(tp);

			if ((cl = cls_set_class(tp, &f->res.class, 0)) != 0)
				tp->q->ops->cl_ops->unbind_tcf(tp->q, cl);

#ifdef CONFIG_NET_CLS_POLICE
			tcf_police_release(f->police);
#endif

			kfree(f);

			/* Strip tree */

			for (i=0; i<=16; i++)
				if (s->ht[i])
					return 0;

			/* OK, session has no flows */
			for (sp = &((struct rsvp_head*)tp->root)->ht[h&0xFF];
			     *sp; sp = &(*sp)->next) {
				if (*sp == s) {
					tcf_tree_lock(tp);
					*sp = s->next;
					tcf_tree_unlock(tp);

					kfree(s);
					return 0;
				}
			}

			return 0;
		}
	}
	return 0;
}

static unsigned gen_handle(struct tcf_proto *tp, unsigned salt)
{
	struct rsvp_head *data = tp->root;
	int i = 0xFFFF;