[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / netfilter / ip6t_frag.c

/* Kernel module to match FRAG parameters. */

/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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/ip6_tables.h>
#include <linux/netfilter_ipv6/ip6t_frag.h>

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

/* Returns 1 if the id is matched by the range, 0 otherwise */
static inline bool
id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
{
	bool r;
	pr_debug("id_match:%c 0x%x <= 0x%x <= 0x%x\n", invert ? '!' : ' ',
		 min, id, max);
	r = (id >= min && id <= max) ^ invert;
	pr_debug(" result %s\n", r ? "PASS" : "FAILED");
	return r;
}

static bool
frag_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
	struct frag_hdr _frag;
	const struct frag_hdr *fh;
	const struct ip6t_frag *fraginfo = par->matchinfo;
	unsigned int ptr = 0;
	int err;

	err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL, NULL);
	if (err < 0) {
		if (err != -ENOENT)
			par->hotdrop = true;
		return false;
	}

	fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
	if (fh == NULL) {
		par->hotdrop = true;
		return false;
	}

	pr_debug("INFO %04X ", fh->frag_off);
	pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
	pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
	pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF));
	pr_debug("ID %u %08X\n", ntohl(fh->identification),
		 ntohl(fh->identification));

	pr_debug("IPv6 FRAG id %02X ",
		 id_match(fraginfo->ids[0], fraginfo->ids[1],
			  ntohl(fh->identification),
			  !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
	pr_debug("res %02X %02X%04X %02X ",
		 fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
		 ntohs(fh->frag_off) & 0x6,
		 !((fraginfo->flags & IP6T_FRAG_RES) &&
		   (fh->reserved || (ntohs(fh->frag_off) & 0x06))));
	pr_debug("first %02X %02X %02X ",
		 fraginfo->flags & IP6T_FRAG_FST,
		 ntohs(fh->frag_off) & ~0x7,
		 !((fraginfo->flags & IP6T_FRAG_FST) &&
		   (ntohs(fh->frag_off) & ~0x7)));
	pr_debug("mf %02X %02X %02X ",
		 fraginfo->flags & IP6T_FRAG_MF,
		 ntohs(fh->frag_off) & IP6_MF,
		 !((fraginfo->flags & IP6T_FRAG_MF) &&
		   !((ntohs(fh->frag_off) & IP6_MF))));
	pr_debug("last %02X %02X %02X\n",
		 fraginfo->flags & IP6T_FRAG_NMF,
		 ntohs(fh->frag_off) & IP6_MF,
		 !((fraginfo->flags & IP6T_FRAG_NMF) &&
		   (ntohs(fh->frag_off) & IP6_MF)));

	return (fh != NULL) &&
		id_match(fraginfo->ids[0], fraginfo->ids[1],
			 ntohl(fh->identification),
			 !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)) &&
		!((fraginfo->flags & IP6T_FRAG_RES) &&
		  (fh->reserved || (ntohs(fh->frag_off) & 0x6))) &&
		!((fraginfo->flags & IP6T_FRAG_FST) &&
		  (ntohs(fh->frag_off) & ~0x7)) &&
		!((fraginfo->flags & IP6T_FRAG_MF) &&
		  !(ntohs(fh->frag_off) & IP6_MF)) &&
		!((fraginfo->flags & IP6T_FRAG_NMF) &&
		  (ntohs(fh->frag_off) & IP6_MF));
}

static int frag_mt6_check(const struct xt_mtchk_param *par)
{
	const struct ip6t_frag *fraginfo = par->matchinfo;

	if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
		pr_debug("unknown flags %X\n", fraginfo->invflags);
		return -EINVAL;
	}
	return 0;
}

static struct xt_match frag_mt6_reg __read_mostly = {
	.name		= "frag",
	.family		= NFPROTO_IPV6,
	.match		= frag_mt6,
	.matchsize	= sizeof(struct ip6t_frag),
	.checkentry	= frag_mt6_check,
	.me		= THIS_MODULE,
};

static int __init frag_mt6_init(void)
{
	return xt_register_match(&frag_mt6_reg);
}

static void __exit frag_mt6_exit(void)
{
	xt_unregister_match(&frag_mt6_reg);
}

module_init(frag_mt6_init);
module_exit(frag_mt6_exit);
Commit	Line	Data
1da177e4 LT	1	/* Kernel module to match FRAG parameters. */
	2
	3	/* (C) 2001-2002 Andras Kis-Szabo <kisza@sch.bme.hu>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License version 2 as
	7	* published by the Free Software Foundation.
	8	*/
ff67e4e4	9	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
1da177e4 LT	10	#include <linux/module.h>
	11	#include <linux/skbuff.h>
	12	#include <linux/ipv6.h>
	13	#include <linux/types.h>
	14	#include <net/checksum.h>
	15	#include <net/ipv6.h>
	16
6709dbbb	17	#include <linux/netfilter/x_tables.h>
1da177e4 LT	18	#include <linux/netfilter_ipv6/ip6_tables.h>
	19	#include <linux/netfilter_ipv6/ip6t_frag.h>
	20
	21	MODULE_LICENSE("GPL");
2ae15b64	22	MODULE_DESCRIPTION("Xtables: IPv6 fragment match");
1da177e4 LT	23	MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
1da177e4 LT	24
1da177e4	25	/* Returns 1 if the id is matched by the range, 0 otherwise */
1d93a9cb JE	26	static inline bool
1d93a9cb JE	27	id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
1da177e4	28	{
1d93a9cb	29	bool r;
ff67e4e4	30	pr_debug("id_match:%c 0x%x <= 0x%x <= 0x%x\n", invert ? '!' : ' ',
0d53778e	31	min, id, max);
f0daaa65	32	r = (id >= min && id <= max) ^ invert;
0d53778e	33	pr_debug(" result %s\n", r ? "PASS" : "FAILED");
f0daaa65	34	return r;
1da177e4 LT	35	}
1da177e4 LT	36
1d93a9cb	37	static bool
62fc8051	38	frag_mt6(const struct sk_buff skb, struct xt_action_param par)
1da177e4	39	{
a47362a2 JE	40	struct frag_hdr _frag;
a47362a2 JE	41	const struct frag_hdr *fh;
f7108a20	42	const struct ip6t_frag *fraginfo = par->matchinfo;
84018f55	43	unsigned int ptr = 0;
6d381634	44	int err;
1da177e4	45
84018f55	46	err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL, NULL);
6d381634 PM	47	if (err < 0) {
6d381634 PM	48	if (err != -ENOENT)
b4ba2611	49	par->hotdrop = true;
1d93a9cb	50	return false;
6d381634	51	}
1da177e4	52
e674d0f3	53	fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
f0daaa65	54	if (fh == NULL) {
b4ba2611	55	par->hotdrop = true;
1d93a9cb	56	return false;
e674d0f3	57	}
1da177e4	58
0d53778e PM	59	pr_debug("INFO %04X ", fh->frag_off);
	60	pr_debug("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
	61	pr_debug("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
	62	pr_debug("MF %04X ", fh->frag_off & htons(IP6_MF));
	63	pr_debug("ID %u %08X\n", ntohl(fh->identification),
	64	ntohl(fh->identification));
	65
	66	pr_debug("IPv6 FRAG id %02X ",
	67	id_match(fraginfo->ids[0], fraginfo->ids[1],
	68	ntohl(fh->identification),
	69	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
	70	pr_debug("res %02X %02X%04X %02X ",
	71	fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
	72	ntohs(fh->frag_off) & 0x6,
3666ed1c JP	73	!((fraginfo->flags & IP6T_FRAG_RES) &&
3666ed1c JP	74	(fh->reserved \|\| (ntohs(fh->frag_off) & 0x06))));
0d53778e PM	75	pr_debug("first %02X %02X %02X ",
	76	fraginfo->flags & IP6T_FRAG_FST,
	77	ntohs(fh->frag_off) & ~0x7,
3666ed1c JP	78	!((fraginfo->flags & IP6T_FRAG_FST) &&
3666ed1c JP	79	(ntohs(fh->frag_off) & ~0x7)));
0d53778e PM	80	pr_debug("mf %02X %02X %02X ",
	81	fraginfo->flags & IP6T_FRAG_MF,
	82	ntohs(fh->frag_off) & IP6_MF,
3666ed1c JP	83	!((fraginfo->flags & IP6T_FRAG_MF) &&
3666ed1c JP	84	!((ntohs(fh->frag_off) & IP6_MF))));
0d53778e PM	85	pr_debug("last %02X %02X %02X\n",
	86	fraginfo->flags & IP6T_FRAG_NMF,
	87	ntohs(fh->frag_off) & IP6_MF,
3666ed1c JP	88	!((fraginfo->flags & IP6T_FRAG_NMF) &&
	89	(ntohs(fh->frag_off) & IP6_MF)));
	90
	91	return (fh != NULL) &&
	92	id_match(fraginfo->ids[0], fraginfo->ids[1],
	93	ntohl(fh->identification),
	94	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)) &&
	95	!((fraginfo->flags & IP6T_FRAG_RES) &&
	96	(fh->reserved \|\| (ntohs(fh->frag_off) & 0x6))) &&
	97	!((fraginfo->flags & IP6T_FRAG_FST) &&
	98	(ntohs(fh->frag_off) & ~0x7)) &&
	99	!((fraginfo->flags & IP6T_FRAG_MF) &&
	100	!(ntohs(fh->frag_off) & IP6_MF)) &&
	101	!((fraginfo->flags & IP6T_FRAG_NMF) &&
	102	(ntohs(fh->frag_off) & IP6_MF));
1da177e4 LT	103	}
1da177e4 LT	104
b0f38452	105	static int frag_mt6_check(const struct xt_mtchk_param *par)
1da177e4	106	{
9b4fce7a	107	const struct ip6t_frag *fraginfo = par->matchinfo;
f0daaa65	108
f0daaa65	109	if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
ff67e4e4	110	pr_debug("unknown flags %X\n", fraginfo->invflags);
bd414ee6	111	return -EINVAL;
f0daaa65	112	}
bd414ee6	113	return 0;
1da177e4 LT	114	}
1da177e4 LT	115
d3c5ee6d	116	static struct xt_match frag_mt6_reg __read_mostly = {
1da177e4	117	.name = "frag",
ee999d8b	118	.family = NFPROTO_IPV6,
d3c5ee6d	119	.match = frag_mt6,
7f939713	120	.matchsize = sizeof(struct ip6t_frag),
d3c5ee6d	121	.checkentry = frag_mt6_check,
1da177e4 LT	122	.me = THIS_MODULE,
	123	};
	124
d3c5ee6d	125	static int __init frag_mt6_init(void)
1da177e4	126	{
d3c5ee6d	127	return xt_register_match(&frag_mt6_reg);
1da177e4 LT	128	}
1da177e4 LT	129
d3c5ee6d	130	static void __exit frag_mt6_exit(void)
1da177e4	131	{
d3c5ee6d	132	xt_unregister_match(&frag_mt6_reg);
1da177e4 LT	133	}
1da177e4 LT	134
d3c5ee6d JE	135	module_init(frag_mt6_init);
d3c5ee6d JE	136	module_exit(frag_mt6_exit);