[deliverable/linux.git] / net / netfilter / xt_sctp.c

#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <linux/sctp.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_sctp.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kiran Kumar Immidi");
MODULE_DESCRIPTION("Match for SCTP protocol packets");
MODULE_ALIAS("ipt_sctp");

#ifdef DEBUG_SCTP
#define duprintf(format, args...) printk(format , ## args)
#else
#define duprintf(format, args...)
#endif

#define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
					      || (!!((invflag) & (option)) ^ (cond)))

static bool
match_flags(const struct xt_sctp_flag_info *flag_info,
	    const int flag_count,
	    u_int8_t chunktype,
	    u_int8_t chunkflags)
{
	int i;

	for (i = 0; i < flag_count; i++) {
		if (flag_info[i].chunktype == chunktype) {
			return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag;
		}
	}

	return true;
}

static inline bool
match_packet(const struct sk_buff *skb,
	     unsigned int offset,
	     const u_int32_t *chunkmap,
	     int chunk_match_type,
	     const struct xt_sctp_flag_info *flag_info,
	     const int flag_count,
	     bool *hotdrop)
{
	u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)];
	sctp_chunkhdr_t _sch, *sch;

#ifdef DEBUG_SCTP
	int i = 0;
#endif

	if (chunk_match_type == SCTP_CHUNK_MATCH_ALL) {
		SCTP_CHUNKMAP_COPY(chunkmapcopy, chunkmap);
	}

	do {
		sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
		if (sch == NULL || sch->length == 0) {
			duprintf("Dropping invalid SCTP packet.\n");
			*hotdrop = true;
			return false;
		}

		duprintf("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d\tflags: %x\n",
				++i, offset, sch->type, htons(sch->length), sch->flags);

		offset += (ntohs(sch->length) + 3) & ~3;

		duprintf("skb->len: %d\toffset: %d\n", skb->len, offset);

		if (SCTP_CHUNKMAP_IS_SET(chunkmap, sch->type)) {
			switch (chunk_match_type) {
			case SCTP_CHUNK_MATCH_ANY:
				if (match_flags(flag_info, flag_count,
					sch->type, sch->flags)) {
					return true;
				}
				break;

			case SCTP_CHUNK_MATCH_ALL:
				if (match_flags(flag_info, flag_count,
					sch->type, sch->flags)) {
					SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type);
				}
				break;

			case SCTP_CHUNK_MATCH_ONLY:
				if (!match_flags(flag_info, flag_count,
					sch->type, sch->flags)) {
					return false;
				}
				break;
			}
		} else {
			switch (chunk_match_type) {
			case SCTP_CHUNK_MATCH_ONLY:
				return false;
			}
		}
	} while (offset < skb->len);

	switch (chunk_match_type) {
	case SCTP_CHUNK_MATCH_ALL:
		return SCTP_CHUNKMAP_IS_CLEAR(chunkmap);
	case SCTP_CHUNK_MATCH_ANY:
		return false;
	case SCTP_CHUNK_MATCH_ONLY:
		return true;
	}

	/* This will never be reached, but required to stop compiler whine */
	return false;
}

static bool
match(const struct sk_buff *skb,
      const struct net_device *in,
      const struct net_device *out,
      const struct xt_match *match,
      const void *matchinfo,
      int offset,
      unsigned int protoff,
      bool *hotdrop)
{
	const struct xt_sctp_info *info = matchinfo;
	sctp_sctphdr_t _sh, *sh;

	if (offset) {
		duprintf("Dropping non-first fragment.. FIXME\n");
		return false;
	}

	sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
	if (sh == NULL) {
		duprintf("Dropping evil TCP offset=0 tinygram.\n");
		*hotdrop = true;
		return false;
	}
	duprintf("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest));

	return  SCCHECK(((ntohs(sh->source) >= info->spts[0])
			&& (ntohs(sh->source) <= info->spts[1])),
			XT_SCTP_SRC_PORTS, info->flags, info->invflags)
		&& SCCHECK(((ntohs(sh->dest) >= info->dpts[0])
			&& (ntohs(sh->dest) <= info->dpts[1])),
			XT_SCTP_DEST_PORTS, info->flags, info->invflags)
		&& SCCHECK(match_packet(skb, protoff + sizeof (sctp_sctphdr_t),
					info->chunkmap, info->chunk_match_type,
					info->flag_info, info->flag_count,
					hotdrop),
			   XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
}

static int
checkentry(const char *tablename,
	   const void *inf,
	   const struct xt_match *match,
	   void *matchinfo,
	   unsigned int hook_mask)
{
	const struct xt_sctp_info *info = matchinfo;

	return !(info->flags & ~XT_SCTP_VALID_FLAGS)
		&& !(info->invflags & ~XT_SCTP_VALID_FLAGS)
		&& !(info->invflags & ~info->flags)
		&& ((!(info->flags & XT_SCTP_CHUNK_TYPES)) ||
			(info->chunk_match_type &
				(SCTP_CHUNK_MATCH_ALL
				| SCTP_CHUNK_MATCH_ANY
				| SCTP_CHUNK_MATCH_ONLY)));
}

static struct xt_match xt_sctp_match[] = {
	{
		.name		= "sctp",
		.family		= AF_INET,
		.checkentry	= checkentry,
		.match		= match,
		.matchsize	= sizeof(struct xt_sctp_info),
		.proto		= IPPROTO_SCTP,
		.me		= THIS_MODULE
	},
	{
		.name		= "sctp",
		.family		= AF_INET6,
		.checkentry	= checkentry,
		.match		= match,
		.matchsize	= sizeof(struct xt_sctp_info),
		.proto		= IPPROTO_SCTP,
		.me		= THIS_MODULE
	},
};

static int __init xt_sctp_init(void)
{
	return xt_register_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
}

static void __exit xt_sctp_fini(void)
{
	xt_unregister_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
}

module_init(xt_sctp_init);
module_exit(xt_sctp_fini);
Commit	Line	Data
	1	#include <linux/module.h>
	2	#include <linux/skbuff.h>
	3	#include <net/ip.h>
	4	#include <net/ipv6.h>
	5	#include <linux/sctp.h>
	6
	7	#include <linux/netfilter/x_tables.h>
	8	#include <linux/netfilter/xt_sctp.h>
	9	#include <linux/netfilter_ipv4/ip_tables.h>
	10	#include <linux/netfilter_ipv6/ip6_tables.h>
	11
	12	MODULE_LICENSE("GPL");
	13	MODULE_AUTHOR("Kiran Kumar Immidi");
	14	MODULE_DESCRIPTION("Match for SCTP protocol packets");
	15	MODULE_ALIAS("ipt_sctp");
	16
	17	#ifdef DEBUG_SCTP
	18	#define duprintf(format, args...) printk(format , ## args)
	19	#else
	20	#define duprintf(format, args...)
	21	#endif
	22
	23	#define SCCHECK(cond, option, flag, invflag) (!((flag) & (option)) \
	24	\|\| (!!((invflag) & (option)) ^ (cond)))
	25
	26	static bool
	27	match_flags(const struct xt_sctp_flag_info *flag_info,
	28	const int flag_count,
	29	u_int8_t chunktype,
	30	u_int8_t chunkflags)
	31	{
	32	int i;
	33
	34	for (i = 0; i < flag_count; i++) {
	35	if (flag_info[i].chunktype == chunktype) {
	36	return (chunkflags & flag_info[i].flag_mask) == flag_info[i].flag;
	37	}
	38	}
	39
	40	return true;
	41	}
	42
	43	static inline bool
	44	match_packet(const struct sk_buff *skb,
	45	unsigned int offset,
	46	const u_int32_t *chunkmap,
	47	int chunk_match_type,
	48	const struct xt_sctp_flag_info *flag_info,
	49	const int flag_count,
	50	bool *hotdrop)
	51	{
	52	u_int32_t chunkmapcopy[256 / sizeof (u_int32_t)];
	53	sctp_chunkhdr_t _sch, *sch;
	54
	55	#ifdef DEBUG_SCTP
	56	int i = 0;
	57	#endif
	58
	59	if (chunk_match_type == SCTP_CHUNK_MATCH_ALL) {
	60	SCTP_CHUNKMAP_COPY(chunkmapcopy, chunkmap);
	61	}
	62
	63	do {
	64	sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
	65	if (sch == NULL \|\| sch->length == 0) {
	66	duprintf("Dropping invalid SCTP packet.\n");
	67	*hotdrop = true;
	68	return false;
	69	}
	70
	71	duprintf("Chunk num: %d\toffset: %d\ttype: %d\tlength: %d\tflags: %x\n",
	72	++i, offset, sch->type, htons(sch->length), sch->flags);
	73
	74	offset += (ntohs(sch->length) + 3) & ~3;
	75
	76	duprintf("skb->len: %d\toffset: %d\n", skb->len, offset);
	77
	78	if (SCTP_CHUNKMAP_IS_SET(chunkmap, sch->type)) {
	79	switch (chunk_match_type) {
	80	case SCTP_CHUNK_MATCH_ANY:
	81	if (match_flags(flag_info, flag_count,
	82	sch->type, sch->flags)) {
	83	return true;
	84	}
	85	break;
	86
	87	case SCTP_CHUNK_MATCH_ALL:
	88	if (match_flags(flag_info, flag_count,
	89	sch->type, sch->flags)) {
	90	SCTP_CHUNKMAP_CLEAR(chunkmapcopy, sch->type);
	91	}
	92	break;
	93
	94	case SCTP_CHUNK_MATCH_ONLY:
	95	if (!match_flags(flag_info, flag_count,
	96	sch->type, sch->flags)) {
	97	return false;
	98	}
	99	break;
	100	}
	101	} else {
	102	switch (chunk_match_type) {
	103	case SCTP_CHUNK_MATCH_ONLY:
	104	return false;
	105	}
	106	}
	107	} while (offset < skb->len);
	108
	109	switch (chunk_match_type) {
	110	case SCTP_CHUNK_MATCH_ALL:
	111	return SCTP_CHUNKMAP_IS_CLEAR(chunkmap);
	112	case SCTP_CHUNK_MATCH_ANY:
	113	return false;
	114	case SCTP_CHUNK_MATCH_ONLY:
	115	return true;
	116	}
	117
	118	/* This will never be reached, but required to stop compiler whine */
	119	return false;
	120	}
	121
	122	static bool
	123	match(const struct sk_buff *skb,
	124	const struct net_device *in,
	125	const struct net_device *out,
	126	const struct xt_match *match,
	127	const void *matchinfo,
	128	int offset,
	129	unsigned int protoff,
	130	bool *hotdrop)
	131	{
	132	const struct xt_sctp_info *info = matchinfo;
	133	sctp_sctphdr_t _sh, *sh;
	134
	135	if (offset) {
	136	duprintf("Dropping non-first fragment.. FIXME\n");
	137	return false;
	138	}
	139
	140	sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
	141	if (sh == NULL) {
	142	duprintf("Dropping evil TCP offset=0 tinygram.\n");
	143	*hotdrop = true;
	144	return false;
	145	}
	146	duprintf("spt: %d\tdpt: %d\n", ntohs(sh->source), ntohs(sh->dest));
	147
	148	return SCCHECK(((ntohs(sh->source) >= info->spts[0])
	149	&& (ntohs(sh->source) <= info->spts[1])),
	150	XT_SCTP_SRC_PORTS, info->flags, info->invflags)
	151	&& SCCHECK(((ntohs(sh->dest) >= info->dpts[0])
	152	&& (ntohs(sh->dest) <= info->dpts[1])),
	153	XT_SCTP_DEST_PORTS, info->flags, info->invflags)
	154	&& SCCHECK(match_packet(skb, protoff + sizeof (sctp_sctphdr_t),
	155	info->chunkmap, info->chunk_match_type,
	156	info->flag_info, info->flag_count,
	157	hotdrop),
	158	XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
	159	}
	160
	161	static int
	162	checkentry(const char *tablename,
	163	const void *inf,
	164	const struct xt_match *match,
	165	void *matchinfo,
	166	unsigned int hook_mask)
	167	{
	168	const struct xt_sctp_info *info = matchinfo;
	169
	170	return !(info->flags & ~XT_SCTP_VALID_FLAGS)
	171	&& !(info->invflags & ~XT_SCTP_VALID_FLAGS)
	172	&& !(info->invflags & ~info->flags)
	173	&& ((!(info->flags & XT_SCTP_CHUNK_TYPES)) \|\|
	174	(info->chunk_match_type &
	175	(SCTP_CHUNK_MATCH_ALL
	176	\| SCTP_CHUNK_MATCH_ANY
	177	\| SCTP_CHUNK_MATCH_ONLY)));
	178	}
	179
	180	static struct xt_match xt_sctp_match[] = {
	181	{
	182	.name = "sctp",
	183	.family = AF_INET,
	184	.checkentry = checkentry,
	185	.match = match,
	186	.matchsize = sizeof(struct xt_sctp_info),
	187	.proto = IPPROTO_SCTP,
	188	.me = THIS_MODULE
	189	},
	190	{
	191	.name = "sctp",
	192	.family = AF_INET6,
	193	.checkentry = checkentry,
	194	.match = match,
	195	.matchsize = sizeof(struct xt_sctp_info),
	196	.proto = IPPROTO_SCTP,
	197	.me = THIS_MODULE
	198	},
	199	};
	200
	201	static int __init xt_sctp_init(void)
	202	{
	203	return xt_register_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
	204	}
	205
	206	static void __exit xt_sctp_fini(void)
	207	{
	208	xt_unregister_matches(xt_sctp_match, ARRAY_SIZE(xt_sctp_match));
	209	}
	210
	211	module_init(xt_sctp_init);
	212	module_exit(xt_sctp_fini);