[mirror_ubuntu-bionic-kernel.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 int
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 1;
}

static inline int
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,
	     int *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) {
			duprintf("Dropping invalid SCTP packet.\n");
			*hotdrop = 1;
			return 0;
        	}

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

		offset += (htons(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 1;
				}
				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 0;
				}
				break;
			}
		} else {
			switch (chunk_match_type) {
			case SCTP_CHUNK_MATCH_ONLY:
				return 0;
			}
		}
	} 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 0;
	case SCTP_CHUNK_MATCH_ONLY:
		return 1;
	}

	/* This will never be reached, but required to stop compiler whine */
	return 0;
}

static int
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,
      int *hotdrop)
{
	const struct xt_sctp_info *info = matchinfo;
	sctp_sctphdr_t _sh, *sh;

	if (offset) {
		duprintf("Dropping non-first fragment.. FIXME\n");
		return 0;
	}
	
	sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
	if (sh == NULL) {
		duprintf("Dropping evil TCP offset=0 tinygram.\n");
		*hotdrop = 1;
		return 0;
       	}
	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,
					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 matchsize,
	   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 sctp_match = {
	.name		= "sctp",
	.match		= match,
	.matchsize	= sizeof(struct xt_sctp_info),
	.proto		= IPPROTO_SCTP,
	.checkentry	= checkentry,
	.family		= AF_INET,
	.me		= THIS_MODULE
};

static struct xt_match sctp6_match = {
	.name		= "sctp",
	.match		= match,
	.matchsize	= sizeof(struct xt_sctp_info),
	.proto		= IPPROTO_SCTP,
	.checkentry	= checkentry,
	.family		= AF_INET6,
	.me		= THIS_MODULE
};

static int __init xt_sctp_init(void)
{
	int ret;
	ret = xt_register_match(&sctp_match);
	if (ret)
		return ret;

	ret = xt_register_match(&sctp6_match);
	if (ret)
		xt_unregister_match(&sctp_match);

	return ret;
}

static void __exit xt_sctp_fini(void)
{
	xt_unregister_match(&sctp6_match);
	xt_unregister_match(&sctp_match);
}

module_init(xt_sctp_init);
module_exit(xt_sctp_fini);
Commit	Line	Data
1da177e4 LT	1	#include <linux/module.h>
	2	#include <linux/skbuff.h>
	3	#include <net/ip.h>
2e4e6a17	4	#include <net/ipv6.h>
1da177e4 LT	5	#include <linux/sctp.h>
1da177e4 LT	6
2e4e6a17 HW	7	#include <linux/netfilter/x_tables.h>
2e4e6a17 HW	8	#include <linux/netfilter/xt_sctp.h>
1da177e4	9	#include <linux/netfilter_ipv4/ip_tables.h>
2e4e6a17 HW	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");
1da177e4 LT	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 int
2e4e6a17	27	match_flags(const struct xt_sctp_flag_info *flag_info,
1da177e4 LT	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 1;
	41	}
	42
2e4e6a17	43	static inline int
1da177e4	44	match_packet(const struct sk_buff *skb,
2e4e6a17	45	unsigned int offset,
1da177e4 LT	46	const u_int32_t *chunkmap,
1da177e4 LT	47	int chunk_match_type,
2e4e6a17	48	const struct xt_sctp_flag_info *flag_info,
1da177e4 LT	49	const int flag_count,
	50	int *hotdrop)
	51	{
1da177e4 LT	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
1da177e4 LT	63	do {
	64	sch = skb_header_pointer(skb, offset, sizeof(_sch), &_sch);
	65	if (sch == NULL) {
	66	duprintf("Dropping invalid SCTP packet.\n");
	67	*hotdrop = 1;
	68	return 0;
	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 += (htons(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 1;
	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 0;
	98	}
	99	break;
	100	}
	101	} else {
	102	switch (chunk_match_type) {
	103	case SCTP_CHUNK_MATCH_ONLY:
	104	return 0;
	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 0;
	114	case SCTP_CHUNK_MATCH_ONLY:
	115	return 1;
	116	}
	117
	118	/* This will never be reached, but required to stop compiler whine */
	119	return 0;
	120	}
	121
	122	static int
	123	match(const struct sk_buff *skb,
	124	const struct net_device *in,
	125	const struct net_device *out,
c4986734	126	const struct xt_match *match,
1da177e4 LT	127	const void *matchinfo,
1da177e4 LT	128	int offset,
2e4e6a17	129	unsigned int protoff,
1da177e4 LT	130	int *hotdrop)
1da177e4 LT	131	{
3e72b2fe	132	const struct xt_sctp_info *info = matchinfo;
1da177e4 LT	133	sctp_sctphdr_t _sh, *sh;
1da177e4 LT	134
1da177e4 LT	135	if (offset) {
	136	duprintf("Dropping non-first fragment.. FIXME\n");
	137	return 0;
	138	}
	139
2e4e6a17	140	sh = skb_header_pointer(skb, protoff, sizeof(_sh), &_sh);
1da177e4 LT	141	if (sh == NULL) {
	142	duprintf("Dropping evil TCP offset=0 tinygram.\n");
	143	*hotdrop = 1;
	144	return 0;
	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])),
2e4e6a17	150	XT_SCTP_SRC_PORTS, info->flags, info->invflags)
1da177e4 LT	151	&& SCCHECK(((ntohs(sh->dest) >= info->dpts[0])
1da177e4 LT	152	&& (ntohs(sh->dest) <= info->dpts[1])),
2e4e6a17 HW	153	XT_SCTP_DEST_PORTS, info->flags, info->invflags)
	154	&& SCCHECK(match_packet(skb, protoff,
	155	info->chunkmap, info->chunk_match_type,
1da177e4 LT	156	info->flag_info, info->flag_count,
1da177e4 LT	157	hotdrop),
2e4e6a17	158	XT_SCTP_CHUNK_TYPES, info->flags, info->invflags);
1da177e4 LT	159	}
	160
	161	static int
	162	checkentry(const char *tablename,
2e4e6a17	163	const void *inf,
c4986734	164	const struct xt_match *match,
2e4e6a17 HW	165	void *matchinfo,
	166	unsigned int matchsize,
	167	unsigned int hook_mask)
	168	{
5d04bff0	169	const struct xt_sctp_info *info = matchinfo;
2e4e6a17	170
5d04bff0	171	return !(info->flags & ~XT_SCTP_VALID_FLAGS)
2e4e6a17 HW	172	&& !(info->invflags & ~XT_SCTP_VALID_FLAGS)
	173	&& !(info->invflags & ~info->flags)
	174	&& ((!(info->flags & XT_SCTP_CHUNK_TYPES)) \|\|
	175	(info->chunk_match_type &
	176	(SCTP_CHUNK_MATCH_ALL
	177	\| SCTP_CHUNK_MATCH_ANY
	178	\| SCTP_CHUNK_MATCH_ONLY)));
	179	}
	180
5d04bff0 PM	181	static struct xt_match sctp_match = {
	182	.name = "sctp",
	183	.match = match,
	184	.matchsize = sizeof(struct xt_sctp_info),
	185	.proto = IPPROTO_SCTP,
	186	.checkentry = checkentry,
a45049c5	187	.family = AF_INET,
5d04bff0	188	.me = THIS_MODULE
1da177e4 LT	189	};
1da177e4 LT	190
5d04bff0 PM	191	static struct xt_match sctp6_match = {
	192	.name = "sctp",
	193	.match = match,
	194	.matchsize = sizeof(struct xt_sctp_info),
	195	.proto = IPPROTO_SCTP,
	196	.checkentry = checkentry,
a45049c5	197	.family = AF_INET6,
5d04bff0 PM	198	.me = THIS_MODULE
5d04bff0 PM	199	};
2e4e6a17	200
65b4b4e8	201	static int __init xt_sctp_init(void)
1da177e4	202	{
2e4e6a17	203	int ret;
a45049c5	204	ret = xt_register_match(&sctp_match);
2e4e6a17 HW	205	if (ret)
	206	return ret;
	207
a45049c5	208	ret = xt_register_match(&sctp6_match);
2e4e6a17	209	if (ret)
a45049c5	210	xt_unregister_match(&sctp_match);
2e4e6a17 HW	211
2e4e6a17 HW	212	return ret;
1da177e4 LT	213	}
1da177e4 LT	214
65b4b4e8	215	static void __exit xt_sctp_fini(void)
1da177e4	216	{
a45049c5 PNA	217	xt_unregister_match(&sctp6_match);
a45049c5 PNA	218	xt_unregister_match(&sctp_match);
1da177e4 LT	219	}
1da177e4 LT	220
65b4b4e8 AM	221	module_init(xt_sctp_init);
65b4b4e8 AM	222	module_exit(xt_sctp_fini);