[linux-block.git] / net / ipv6 / netfilter / ip6t_ipv6header.c

// SPDX-License-Identifier: GPL-2.0-only
/* ipv6header match - matches IPv6 packets based
   on whether they contain certain headers */

/* Original idea: Brad Chapman
 * Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */

/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <net/checksum.h>
#include <net/ipv6.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_ipv6/ip6t_ipv6header.h>

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: IPv6 header types match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");

static bool
ipv6header_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct ip6t_ipv6header_info *info = par->matchinfo;
	unsigned int temp;
	int len;
	u8 nexthdr;
	unsigned int ptr;

	/* Make sure this isn't an evil packet */

	/* type of the 1st exthdr */
	nexthdr = ipv6_hdr(skb)->nexthdr;
	/* pointer to the 1st exthdr */
	ptr = sizeof(struct ipv6hdr);
	/* available length */
	len = skb->len - ptr;
	temp = 0;

	while (nf_ip6_ext_hdr(nexthdr)) {
		const struct ipv6_opt_hdr *hp;
		struct ipv6_opt_hdr _hdr;
		int hdrlen;

		/* No more exthdr -> evaluate */
		if (nexthdr == NEXTHDR_NONE) {
			temp |= MASK_NONE;
			break;
		}
		/* Is there enough space for the next ext header? */
		if (len < (int)sizeof(struct ipv6_opt_hdr))
			return false;
		/* ESP -> evaluate */
		if (nexthdr == NEXTHDR_ESP) {
			temp |= MASK_ESP;
			break;
		}

		hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
		if (!hp) {
			par->hotdrop = true;
			return false;
		}

		/* Calculate the header length */
		if (nexthdr == NEXTHDR_FRAGMENT)
			hdrlen = 8;
		else if (nexthdr == NEXTHDR_AUTH)
			hdrlen = ipv6_authlen(hp);
		else
			hdrlen = ipv6_optlen(hp);

		/* set the flag */
		switch (nexthdr) {
		case NEXTHDR_HOP:
			temp |= MASK_HOPOPTS;
			break;
		case NEXTHDR_ROUTING:
			temp |= MASK_ROUTING;
			break;
		case NEXTHDR_FRAGMENT:
			temp |= MASK_FRAGMENT;
			break;
		case NEXTHDR_AUTH:
			temp |= MASK_AH;
			break;
		case NEXTHDR_DEST:
			temp |= MASK_DSTOPTS;
			break;
		default:
			return false;
		}

		nexthdr = hp->nexthdr;
		len -= hdrlen;
		ptr += hdrlen;
		if (ptr > skb->len)
			break;
	}

	if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP)
		temp |= MASK_PROTO;

	if (info->modeflag)
		return !((temp ^ info->matchflags ^ info->invflags)
			 & info->matchflags);
	else {
		if (info->invflags)
			return temp != info->matchflags;
		else
			return temp == info->matchflags;
	}
}

static int ipv6header_mt6_check(const struct xt_mtchk_param *par)
{
	const struct ip6t_ipv6header_info *info = par->matchinfo;

	/* invflags is 0 or 0xff in hard mode */
	if ((!info->modeflag) && info->invflags != 0x00 &&
	    info->invflags != 0xFF)
		return -EINVAL;

	return 0;
}

static struct xt_match ipv6header_mt6_reg __read_mostly = {
	.name		= "ipv6header",
	.family		= NFPROTO_IPV6,
	.match		= ipv6header_mt6,
	.matchsize	= sizeof(struct ip6t_ipv6header_info),
	.checkentry	= ipv6header_mt6_check,
	.destroy	= NULL,
	.me		= THIS_MODULE,
};

static int __init ipv6header_mt6_init(void)
{
	return xt_register_match(&ipv6header_mt6_reg);
}

static void __exit ipv6header_mt6_exit(void)
{
	xt_unregister_match(&ipv6header_mt6_reg);
}

module_init(ipv6header_mt6_init);
module_exit(ipv6header_mt6_exit);
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/* ipv6header match - matches IPv6 packets based
	3	on whether they contain certain headers */
	4
1ab1457c	5	/* Original idea: Brad Chapman
1da177e4 LT	6	* Rewritten by: Andras Kis-Szabo <kisza@sch.bme.hu> */
	7
	8	/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
1da177e4 LT	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/ipv6.h>
	14	#include <linux/types.h>
	15	#include <net/checksum.h>
	16	#include <net/ipv6.h>
	17
6709dbbb	18	#include <linux/netfilter/x_tables.h>
44dde236	19	#include <linux/netfilter_ipv6.h>
1da177e4 LT	20	#include <linux/netfilter_ipv6/ip6t_ipv6header.h>
	21
	22	MODULE_LICENSE("GPL");
2ae15b64	23	MODULE_DESCRIPTION("Xtables: IPv6 header types match");
1da177e4 LT	24	MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
1da177e4 LT	25
1d93a9cb	26	static bool
62fc8051	27	ipv6header_mt6(const struct sk_buff skb, struct xt_action_param par)
1da177e4	28	{
f7108a20	29	const struct ip6t_ipv6header_info *info = par->matchinfo;
1da177e4 LT	30	unsigned int temp;
	31	int len;
	32	u8 nexthdr;
	33	unsigned int ptr;
	34
	35	/* Make sure this isn't an evil packet */
	36
	37	/* type of the 1st exthdr */
0660e03f	38	nexthdr = ipv6_hdr(skb)->nexthdr;
1da177e4 LT	39	/* pointer to the 1st exthdr */
	40	ptr = sizeof(struct ipv6hdr);
	41	/* available length */
	42	len = skb->len - ptr;
	43	temp = 0;
	44
44dde236	45	while (nf_ip6_ext_hdr(nexthdr)) {
3cf93c96 JE	46	const struct ipv6_opt_hdr *hp;
3cf93c96 JE	47	struct ipv6_opt_hdr _hdr;
f0daaa65	48	int hdrlen;
1da177e4	49
1da177e4	50	/* No more exthdr -> evaluate */
f0daaa65	51	if (nexthdr == NEXTHDR_NONE) {
1da177e4 LT	52	temp \|= MASK_NONE;
	53	break;
	54	}
b98b4947 CP	55	/* Is there enough space for the next ext header? */
	56	if (len < (int)sizeof(struct ipv6_opt_hdr))
	57	return false;
1da177e4	58	/* ESP -> evaluate */
f0daaa65	59	if (nexthdr == NEXTHDR_ESP) {
1da177e4 LT	60	temp \|= MASK_ESP;
	61	break;
	62	}
	63
	64	hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
70c0eb1c FW	65	if (!hp) {
	66	par->hotdrop = true;
	67	return false;
	68	}
1da177e4 LT	69
1da177e4 LT	70	/* Calculate the header length */
7c4e36bc	71	if (nexthdr == NEXTHDR_FRAGMENT)
f0daaa65	72	hdrlen = 8;
7c4e36bc	73	else if (nexthdr == NEXTHDR_AUTH)
416e8126	74	hdrlen = ipv6_authlen(hp);
f0daaa65 YK	75	else
f0daaa65 YK	76	hdrlen = ipv6_optlen(hp);
1da177e4 LT	77
1da177e4 LT	78	/* set the flag */
f0daaa65 YK	79	switch (nexthdr) {
	80	case NEXTHDR_HOP:
	81	temp \|= MASK_HOPOPTS;
	82	break;
	83	case NEXTHDR_ROUTING:
	84	temp \|= MASK_ROUTING;
	85	break;
	86	case NEXTHDR_FRAGMENT:
	87	temp \|= MASK_FRAGMENT;
	88	break;
	89	case NEXTHDR_AUTH:
	90	temp \|= MASK_AH;
	91	break;
	92	case NEXTHDR_DEST:
	93	temp \|= MASK_DSTOPTS;
	94	break;
	95	default:
1d93a9cb	96	return false;
1da177e4 LT	97	}
1da177e4 LT	98
f0daaa65 YK	99	nexthdr = hp->nexthdr;
	100	len -= hdrlen;
	101	ptr += hdrlen;
1da177e4 LT	102	if (ptr > skb->len)
1da177e4 LT	103	break;
f0daaa65	104	}
1da177e4	105
7c4e36bc	106	if (nexthdr != NEXTHDR_NONE && nexthdr != NEXTHDR_ESP)
1da177e4 LT	107	temp \|= MASK_PROTO;
	108
	109	if (info->modeflag)
	110	return !((temp ^ info->matchflags ^ info->invflags)
	111	& info->matchflags);
	112	else {
	113	if (info->invflags)
	114	return temp != info->matchflags;
	115	else
	116	return temp == info->matchflags;
	117	}
	118	}
	119
b0f38452	120	static int ipv6header_mt6_check(const struct xt_mtchk_param *par)
1da177e4	121	{
9b4fce7a	122	const struct ip6t_ipv6header_info *info = par->matchinfo;
1da177e4	123
1da177e4	124	/* invflags is 0 or 0xff in hard mode */
f0daaa65 YK	125	if ((!info->modeflag) && info->invflags != 0x00 &&
f0daaa65 YK	126	info->invflags != 0xFF)
bd414ee6	127	return -EINVAL;
1da177e4	128
bd414ee6	129	return 0;
1da177e4 LT	130	}
1da177e4 LT	131
d3c5ee6d	132	static struct xt_match ipv6header_mt6_reg __read_mostly = {
1da177e4	133	.name = "ipv6header",
ee999d8b	134	.family = NFPROTO_IPV6,
d3c5ee6d	135	.match = ipv6header_mt6,
7f939713	136	.matchsize = sizeof(struct ip6t_ipv6header_info),
d3c5ee6d	137	.checkentry = ipv6header_mt6_check,
1da177e4 LT	138	.destroy = NULL,
	139	.me = THIS_MODULE,
	140	};
	141
d3c5ee6d	142	static int __init ipv6header_mt6_init(void)
1da177e4	143	{
d3c5ee6d	144	return xt_register_match(&ipv6header_mt6_reg);
1da177e4 LT	145	}
1da177e4 LT	146
d3c5ee6d	147	static void __exit ipv6header_mt6_exit(void)
1da177e4	148	{
d3c5ee6d	149	xt_unregister_match(&ipv6header_mt6_reg);
1da177e4 LT	150	}
1da177e4 LT	151
d3c5ee6d JE	152	module_init(ipv6header_mt6_init);
d3c5ee6d JE	153	module_exit(ipv6header_mt6_exit);