[linux-block.git] / net / netfilter / xt_u32.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *	xt_u32 - kernel module to match u32 packet content
 *
 *	Original author: Don Cohen <don@isis.cs3-inc.com>
 *	(C) CC Computer Consultants GmbH, 2007
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_u32.h>

static bool u32_match_it(const struct xt_u32 *data,
			 const struct sk_buff *skb)
{
	const struct xt_u32_test *ct;
	unsigned int testind;
	unsigned int nnums;
	unsigned int nvals;
	unsigned int i;
	__be32 n;
	u_int32_t pos;
	u_int32_t val;
	u_int32_t at;

	/*
	 * Small example: "0 >> 28 == 4 && 8 & 0xFF0000 >> 16 = 6, 17"
	 * (=IPv4 and (TCP or UDP)). Outer loop runs over the "&&" operands.
	 */
	for (testind = 0; testind < data->ntests; ++testind) {
		ct  = &data->tests[testind];
		at  = 0;
		pos = ct->location[0].number;

		if (skb->len < 4 || pos > skb->len - 4)
			return false;

		if (skb_copy_bits(skb, pos, &n, sizeof(n)) < 0)
			BUG();
		val   = ntohl(n);
		nnums = ct->nnums;

		/* Inner loop runs over "&", "<<", ">>" and "@" operands */
		for (i = 1; i < nnums; ++i) {
			u_int32_t number = ct->location[i].number;
			switch (ct->location[i].nextop) {
			case XT_U32_AND:
				val &= number;
				break;
			case XT_U32_LEFTSH:
				val <<= number;
				break;
			case XT_U32_RIGHTSH:
				val >>= number;
				break;
			case XT_U32_AT:
				if (at + val < at)
					return false;
				at += val;
				pos = number;
				if (at + 4 < at || skb->len < at + 4 ||
				    pos > skb->len - at - 4)
					return false;

				if (skb_copy_bits(skb, at + pos, &n,
						    sizeof(n)) < 0)
					BUG();
				val = ntohl(n);
				break;
			}
		}

		/* Run over the "," and ":" operands */
		nvals = ct->nvalues;
		for (i = 0; i < nvals; ++i)
			if (ct->value[i].min <= val && val <= ct->value[i].max)
				break;

		if (i >= ct->nvalues)
			return false;
	}

	return true;
}

static bool u32_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct xt_u32 *data = par->matchinfo;
	bool ret;

	ret = u32_match_it(data, skb);
	return ret ^ data->invert;
}

static struct xt_match xt_u32_mt_reg __read_mostly = {
	.name       = "u32",
	.revision   = 0,
	.family     = NFPROTO_UNSPEC,
	.match      = u32_mt,
	.matchsize  = sizeof(struct xt_u32),
	.me         = THIS_MODULE,
};

static int __init u32_mt_init(void)
{
	return xt_register_match(&xt_u32_mt_reg);
}

static void __exit u32_mt_exit(void)
{
	xt_unregister_match(&xt_u32_mt_reg);
}

module_init(u32_mt_init);
module_exit(u32_mt_exit);
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: arbitrary byte matching");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_u32");
MODULE_ALIAS("ip6t_u32");
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
1b50b8a3 JE	2	/*
	3	* xt_u32 - kernel module to match u32 packet content
	4	*
	5	* Original author: Don Cohen <don@isis.cs3-inc.com>
ba5dc275	6	* (C) CC Computer Consultants GmbH, 2007
1b50b8a3 JE	7	*/
	8
	9	#include <linux/module.h>
	10	#include <linux/moduleparam.h>
	11	#include <linux/spinlock.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/types.h>
	14	#include <linux/netfilter/x_tables.h>
	15	#include <linux/netfilter/xt_u32.h>
	16
	17	static bool u32_match_it(const struct xt_u32 *data,
	18	const struct sk_buff *skb)
	19	{
	20	const struct xt_u32_test *ct;
	21	unsigned int testind;
	22	unsigned int nnums;
	23	unsigned int nvals;
	24	unsigned int i;
a34c4589	25	__be32 n;
1b50b8a3 JE	26	u_int32_t pos;
	27	u_int32_t val;
	28	u_int32_t at;
1b50b8a3 JE	29
	30	/*
	31	* Small example: "0 >> 28 == 4 && 8 & 0xFF0000 >> 16 = 6, 17"
	32	* (=IPv4 and (TCP or UDP)). Outer loop runs over the "&&" operands.
	33	*/
	34	for (testind = 0; testind < data->ntests; ++testind) {
	35	ct = &data->tests[testind];
	36	at = 0;
	37	pos = ct->location[0].number;
	38
35019539	39	if (skb->len < 4 \|\| pos > skb->len - 4)
1b50b8a3 JE	40	return false;
1b50b8a3 JE	41
f449b3b5 PE	42	if (skb_copy_bits(skb, pos, &n, sizeof(n)) < 0)
f449b3b5 PE	43	BUG();
a34c4589	44	val = ntohl(n);
1b50b8a3 JE	45	nnums = ct->nnums;
	46
	47	/* Inner loop runs over "&", "<<", ">>" and "@" operands */
	48	for (i = 1; i < nnums; ++i) {
	49	u_int32_t number = ct->location[i].number;
	50	switch (ct->location[i].nextop) {
	51	case XT_U32_AND:
	52	val &= number;
	53	break;
	54	case XT_U32_LEFTSH:
	55	val <<= number;
	56	break;
	57	case XT_U32_RIGHTSH:
	58	val >>= number;
	59	break;
	60	case XT_U32_AT:
	61	if (at + val < at)
	62	return false;
	63	at += val;
	64	pos = number;
	65	if (at + 4 < at \|\| skb->len < at + 4 \|\|
	66	pos > skb->len - at - 4)
	67	return false;
	68
f449b3b5 PE	69	if (skb_copy_bits(skb, at + pos, &n,
	70	sizeof(n)) < 0)
	71	BUG();
a34c4589	72	val = ntohl(n);
1b50b8a3 JE	73	break;
	74	}
	75	}
	76
	77	/* Run over the "," and ":" operands */
	78	nvals = ct->nvalues;
	79	for (i = 0; i < nvals; ++i)
	80	if (ct->value[i].min <= val && val <= ct->value[i].max)
	81	break;
	82
	83	if (i >= ct->nvalues)
	84	return false;
	85	}
	86
	87	return true;
	88	}
	89
62fc8051	90	static bool u32_mt(const struct sk_buff skb, struct xt_action_param par)
1b50b8a3	91	{
f7108a20	92	const struct xt_u32 *data = par->matchinfo;
1b50b8a3 JE	93	bool ret;
	94
	95	ret = u32_match_it(data, skb);
	96	return ret ^ data->invert;
	97	}
	98
55b69e91 JE	99	static struct xt_match xt_u32_mt_reg __read_mostly = {
	100	.name = "u32",
	101	.revision = 0,
	102	.family = NFPROTO_UNSPEC,
	103	.match = u32_mt,
	104	.matchsize = sizeof(struct xt_u32),
	105	.me = THIS_MODULE,
1b50b8a3 JE	106	};
1b50b8a3 JE	107
d3c5ee6d	108	static int __init u32_mt_init(void)
1b50b8a3	109	{
55b69e91	110	return xt_register_match(&xt_u32_mt_reg);
1b50b8a3 JE	111	}
1b50b8a3 JE	112
d3c5ee6d	113	static void __exit u32_mt_exit(void)
1b50b8a3	114	{
55b69e91	115	xt_unregister_match(&xt_u32_mt_reg);
1b50b8a3 JE	116	}
1b50b8a3 JE	117
d3c5ee6d JE	118	module_init(u32_mt_init);
d3c5ee6d JE	119	module_exit(u32_mt_exit);
408ffaa4	120	MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
2ae15b64	121	MODULE_DESCRIPTION("Xtables: arbitrary byte matching");
1b50b8a3 JE	122	MODULE_LICENSE("GPL");
	123	MODULE_ALIAS("ipt_u32");
	124	MODULE_ALIAS("ip6t_u32");