[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.
 */

#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("IPv6 FRAG match");
MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

/* 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;
	DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
	       min, id, max);
	r = (id >= min && id <= max) ^ invert;
	DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
	return r;
}

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)
{
	struct frag_hdr _frag;
	const struct frag_hdr *fh;
	const struct ip6t_frag *fraginfo = matchinfo;
	unsigned int ptr;
	int err;

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

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

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

	DEBUGP("IPv6 FRAG id %02X ",
	       id_match(fraginfo->ids[0], fraginfo->ids[1],
			 ntohl(fh->identification),
			 !!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
	DEBUGP("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))));
	DEBUGP("first %02X %02X %02X ",
	       fraginfo->flags & IP6T_FRAG_FST,
	       ntohs(fh->frag_off) & ~0x7,
	       !((fraginfo->flags & IP6T_FRAG_FST)
		 && (ntohs(fh->frag_off) & ~0x7)));
	DEBUGP("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))));
	DEBUGP("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));
}

/* Called when user tries to insert an entry of this type. */
static bool
checkentry(const char *tablename,
	   const void *ip,
	   const struct xt_match *match,
	   void *matchinfo,
	   unsigned int hook_mask)
{
	const struct ip6t_frag *fraginfo = matchinfo;

	if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
		DEBUGP("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
		return false;
	}
	return true;
}

static struct xt_match frag_match = {
	.name		= "frag",
	.family		= AF_INET6,
	.match		= match,
	.matchsize	= sizeof(struct ip6t_frag),
	.checkentry	= checkentry,
	.me		= THIS_MODULE,
};

static int __init ip6t_frag_init(void)
{
	return xt_register_match(&frag_match);
}

static void __exit ip6t_frag_fini(void)
{
	xt_unregister_match(&frag_match);
}

module_init(ip6t_frag_init);
module_exit(ip6t_frag_fini);
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	*/
	9
	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");
	22	MODULE_DESCRIPTION("IPv6 FRAG match");
	23	MODULE_AUTHOR("Andras Kis-Szabo <kisza@sch.bme.hu>");
	24
	25	#if 0
	26	#define DEBUGP printk
	27	#else
	28	#define DEBUGP(format, args...)
	29	#endif
	30
	31	/* Returns 1 if the id is matched by the range, 0 otherwise */
1d93a9cb JE	32	static inline bool
1d93a9cb JE	33	id_match(u_int32_t min, u_int32_t max, u_int32_t id, bool invert)
1da177e4	34	{
1d93a9cb	35	bool r;
f0daaa65 YK	36	DEBUGP("frag id_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',
	37	min, id, max);
	38	r = (id >= min && id <= max) ^ invert;
	39	DEBUGP(" result %s\n", r ? "PASS" : "FAILED");
	40	return r;
1da177e4 LT	41	}
1da177e4 LT	42
1d93a9cb	43	static bool
1da177e4 LT	44	match(const struct sk_buff *skb,
	45	const struct net_device *in,
	46	const struct net_device *out,
c4986734	47	const struct xt_match *match,
1da177e4 LT	48	const void *matchinfo,
	49	int offset,
	50	unsigned int protoff,
cff533ac	51	bool *hotdrop)
1da177e4	52	{
a47362a2 JE	53	struct frag_hdr _frag;
a47362a2 JE	54	const struct frag_hdr *fh;
f0daaa65 YK	55	const struct ip6t_frag *fraginfo = matchinfo;
f0daaa65 YK	56	unsigned int ptr;
6d381634	57	int err;
1da177e4	58
6d381634 PM	59	err = ipv6_find_hdr(skb, &ptr, NEXTHDR_FRAGMENT, NULL);
	60	if (err < 0) {
	61	if (err != -ENOENT)
cff533ac	62	*hotdrop = true;
1d93a9cb	63	return false;
6d381634	64	}
1da177e4	65
e674d0f3	66	fh = skb_header_pointer(skb, ptr, sizeof(_frag), &_frag);
f0daaa65	67	if (fh == NULL) {
cff533ac	68	*hotdrop = true;
1d93a9cb	69	return false;
e674d0f3	70	}
1da177e4	71
f0daaa65 YK	72	DEBUGP("INFO %04X ", fh->frag_off);
	73	DEBUGP("OFFSET %04X ", ntohs(fh->frag_off) & ~0x7);
	74	DEBUGP("RES %02X %04X", fh->reserved, ntohs(fh->frag_off) & 0x6);
	75	DEBUGP("MF %04X ", fh->frag_off & htons(IP6_MF));
	76	DEBUGP("ID %u %08X\n", ntohl(fh->identification),
	77	ntohl(fh->identification));
	78
	79	DEBUGP("IPv6 FRAG id %02X ",
7c4e36bc	80	id_match(fraginfo->ids[0], fraginfo->ids[1],
f0daaa65	81	ntohl(fh->identification),
7c4e36bc	82	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS)));
f0daaa65	83	DEBUGP("res %02X %02X%04X %02X ",
7c4e36bc	84	fraginfo->flags & IP6T_FRAG_RES, fh->reserved,
f0daaa65 YK	85	ntohs(fh->frag_off) & 0x6,
	86	!((fraginfo->flags & IP6T_FRAG_RES)
	87	&& (fh->reserved \|\| (ntohs(fh->frag_off) & 0x06))));
	88	DEBUGP("first %02X %02X %02X ",
7c4e36bc	89	fraginfo->flags & IP6T_FRAG_FST,
f0daaa65 YK	90	ntohs(fh->frag_off) & ~0x7,
	91	!((fraginfo->flags & IP6T_FRAG_FST)
	92	&& (ntohs(fh->frag_off) & ~0x7)));
	93	DEBUGP("mf %02X %02X %02X ",
7c4e36bc	94	fraginfo->flags & IP6T_FRAG_MF,
f0daaa65 YK	95	ntohs(fh->frag_off) & IP6_MF,
	96	!((fraginfo->flags & IP6T_FRAG_MF)
	97	&& !((ntohs(fh->frag_off) & IP6_MF))));
	98	DEBUGP("last %02X %02X %02X\n",
7c4e36bc	99	fraginfo->flags & IP6T_FRAG_NMF,
f0daaa65 YK	100	ntohs(fh->frag_off) & IP6_MF,
	101	!((fraginfo->flags & IP6T_FRAG_NMF)
	102	&& (ntohs(fh->frag_off) & IP6_MF)));
	103
	104	return (fh != NULL)
	105	&&
7c4e36bc JE	106	id_match(fraginfo->ids[0], fraginfo->ids[1],
	107	ntohl(fh->identification),
	108	!!(fraginfo->invflags & IP6T_FRAG_INV_IDS))
f0daaa65 YK	109	&&
	110	!((fraginfo->flags & IP6T_FRAG_RES)
	111	&& (fh->reserved \|\| (ntohs(fh->frag_off) & 0x6)))
	112	&&
	113	!((fraginfo->flags & IP6T_FRAG_FST)
	114	&& (ntohs(fh->frag_off) & ~0x7))
	115	&&
	116	!((fraginfo->flags & IP6T_FRAG_MF)
	117	&& !(ntohs(fh->frag_off) & IP6_MF))
	118	&&
	119	!((fraginfo->flags & IP6T_FRAG_NMF)
	120	&& (ntohs(fh->frag_off) & IP6_MF));
1da177e4 LT	121	}
	122
	123	/* Called when user tries to insert an entry of this type. */
ccb79bdc	124	static bool
1da177e4	125	checkentry(const char *tablename,
f0daaa65	126	const void *ip,
c4986734	127	const struct xt_match *match,
f0daaa65	128	void *matchinfo,
f0daaa65	129	unsigned int hook_mask)
1da177e4	130	{
f0daaa65 YK	131	const struct ip6t_frag *fraginfo = matchinfo;
f0daaa65 YK	132
f0daaa65 YK	133	if (fraginfo->invflags & ~IP6T_FRAG_INV_MASK) {
f0daaa65 YK	134	DEBUGP("ip6t_frag: unknown flags %X\n", fraginfo->invflags);
ccb79bdc	135	return false;
f0daaa65	136	}
ccb79bdc	137	return true;
1da177e4 LT	138	}
1da177e4 LT	139
6709dbbb	140	static struct xt_match frag_match = {
1da177e4	141	.name = "frag",
6709dbbb	142	.family = AF_INET6,
7f939713 PM	143	.match = match,
	144	.matchsize = sizeof(struct ip6t_frag),
	145	.checkentry = checkentry,
1da177e4 LT	146	.me = THIS_MODULE,
	147	};
	148
65b4b4e8	149	static int __init ip6t_frag_init(void)
1da177e4	150	{
6709dbbb	151	return xt_register_match(&frag_match);
1da177e4 LT	152	}
1da177e4 LT	153
65b4b4e8	154	static void __exit ip6t_frag_fini(void)
1da177e4	155	{
6709dbbb	156	xt_unregister_match(&frag_match);
1da177e4 LT	157	}
1da177e4 LT	158
65b4b4e8 AM	159	module_init(ip6t_frag_init);
65b4b4e8 AM	160	module_exit(ip6t_frag_fini);