[linux-2.6-block.git] / net / netfilter / nft_exthdr.c

/*
 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
 *
 * 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.
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <net/netfilter/nf_tables.h>
#include <net/tcp.h>

struct nft_exthdr {
	u8			type;
	u8			offset;
	u8			len;
	u8			op;
	enum nft_registers	dreg:8;
	u8			flags;
};

static unsigned int optlen(const u8 *opt, unsigned int offset)
{
	/* Beware zero-length options: make finite progress */
	if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0)
		return 1;
	else
		return opt[offset + 1];
}

static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 *dest = &regs->data[priv->dreg];
	unsigned int offset = 0;
	int err;

	err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
	if (priv->flags & NFT_EXTHDR_F_PRESENT) {
		*dest = (err >= 0);
		return;
	} else if (err < 0) {
		goto err;
	}
	offset += priv->offset;

	dest[priv->len / NFT_REG32_SIZE] = 0;
	if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
		goto err;
	return;
err:
	regs->verdict.code = NFT_BREAK;
}

static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
				struct nft_regs *regs,
				const struct nft_pktinfo *pkt)
{
	u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
	struct nft_exthdr *priv = nft_expr_priv(expr);
	unsigned int i, optl, tcphdr_len, offset;
	u32 *dest = &regs->data[priv->dreg];
	struct tcphdr *tcph;
	u8 *opt;

	if (!pkt->tprot_set || pkt->tprot != IPPROTO_TCP)
		goto err;

	tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buff);
	if (!tcph)
		goto err;

	tcphdr_len = __tcp_hdrlen(tcph);
	if (tcphdr_len < sizeof(*tcph))
		goto err;

	tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, tcphdr_len, buff);
	if (!tcph)
		goto err;

	opt = (u8 *)tcph;
	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
		optl = optlen(opt, i);

		if (priv->type != opt[i])
			continue;

		if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
			goto err;

		offset = i + priv->offset;
		dest[priv->len / NFT_REG32_SIZE] = 0;
		memcpy(dest, opt + offset, priv->len);

		return;
	}

err:
	regs->verdict.code = NFT_BREAK;
}

static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
	[NFTA_EXTHDR_DREG]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_TYPE]		= { .type = NLA_U8 },
	[NFTA_EXTHDR_OFFSET]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_LEN]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_FLAGS]		= { .type = NLA_U32 },
};

static int nft_exthdr_init(const struct nft_ctx *ctx,
			   const struct nft_expr *expr,
			   const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
	int err;

	if (!tb[NFTA_EXTHDR_DREG] ||
	    !tb[NFTA_EXTHDR_TYPE] ||
	    !tb[NFTA_EXTHDR_OFFSET] ||
	    !tb[NFTA_EXTHDR_LEN])
		return -EINVAL;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
	if (err < 0)
		return err;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
	if (err < 0)
		return err;

	if (tb[NFTA_EXTHDR_FLAGS]) {
		err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
		if (err < 0)
			return err;

		if (flags & ~NFT_EXTHDR_F_PRESENT)
			return -EINVAL;
	}

	if (tb[NFTA_EXTHDR_OP]) {
		err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
		if (err < 0)
			return err;
	}

	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
	priv->offset = offset;
	priv->len    = len;
	priv->dreg   = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
	priv->flags  = flags;
	priv->op     = op;

	return nft_validate_register_store(ctx, priv->dreg, NULL,
					   NFT_DATA_VALUE, priv->len);
}

static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
	const struct nft_exthdr *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
		goto nla_put_failure;
	if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static struct nft_expr_type nft_exthdr_type;
static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_ipv6_eval,
	.init		= nft_exthdr_init,
	.dump		= nft_exthdr_dump,
};

static const struct nft_expr_ops nft_exthdr_tcp_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_tcp_eval,
	.init		= nft_exthdr_init,
	.dump		= nft_exthdr_dump,
};

static const struct nft_expr_ops *
nft_exthdr_select_ops(const struct nft_ctx *ctx,
		      const struct nlattr * const tb[])
{
	u32 op;

	if (!tb[NFTA_EXTHDR_OP])
		return &nft_exthdr_ipv6_ops;

	op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP]));
	switch (op) {
	case NFT_EXTHDR_OP_TCPOPT:
		return &nft_exthdr_tcp_ops;
	case NFT_EXTHDR_OP_IPV6:
		return &nft_exthdr_ipv6_ops;
	}

	return ERR_PTR(-EOPNOTSUPP);
}

static struct nft_expr_type nft_exthdr_type __read_mostly = {
	.name		= "exthdr",
	.select_ops	= &nft_exthdr_select_ops,
	.policy		= nft_exthdr_policy,
	.maxattr	= NFTA_EXTHDR_MAX,
	.owner		= THIS_MODULE,
};

static int __init nft_exthdr_module_init(void)
{
	return nft_register_expr(&nft_exthdr_type);
}

static void __exit nft_exthdr_module_exit(void)
{
	nft_unregister_expr(&nft_exthdr_type);
}

module_init(nft_exthdr_module_init);
module_exit(nft_exthdr_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
MODULE_ALIAS_NFT_EXPR("exthdr");
Commit	Line	Data
96518518 PM	1	/*
	2	* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*
	8	* Development of this code funded by Astaro AG (http://www.astaro.com/)
	9	*/
	10
	11	#include <linux/kernel.h>
	12	#include <linux/init.h>
	13	#include <linux/module.h>
	14	#include <linux/netlink.h>
	15	#include <linux/netfilter.h>
	16	#include <linux/netfilter/nf_tables.h>
	17	#include <net/netfilter/nf_tables.h>
935b7f64	18	#include <net/tcp.h>
96518518 PM	19
	20	struct nft_exthdr {
	21	u8 type;
	22	u8 offset;
	23	u8 len;
935b7f64	24	u8 op;
96518518	25	enum nft_registers dreg:8;
c078ca3b	26	u8 flags;
96518518 PM	27	};
96518518 PM	28
935b7f64 MM	29	static unsigned int optlen(const u8 *opt, unsigned int offset)
	30	{
	31	/* Beware zero-length options: make finite progress */
	32	if (opt[offset] <= TCPOPT_NOP \|\| opt[offset + 1] == 0)
	33	return 1;
	34	else
	35	return opt[offset + 1];
	36	}
	37
	38	static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
	39	struct nft_regs *regs,
	40	const struct nft_pktinfo *pkt)
96518518 PM	41	{
96518518 PM	42	struct nft_exthdr *priv = nft_expr_priv(expr);
49499c3e	43	u32 *dest = &regs->data[priv->dreg];
540436c8	44	unsigned int offset = 0;
96518518 PM	45	int err;
	46
	47	err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
c078ca3b PS	48	if (priv->flags & NFT_EXTHDR_F_PRESENT) {
	49	*dest = (err >= 0);
	50	return;
	51	} else if (err < 0) {
96518518	52	goto err;
c078ca3b	53	}
96518518 PM	54	offset += priv->offset;
96518518 PM	55
49499c3e	56	dest[priv->len / NFT_REG32_SIZE] = 0;
fad136ea	57	if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
96518518 PM	58	goto err;
	59	return;
	60	err:
a55e22e9	61	regs->verdict.code = NFT_BREAK;
96518518 PM	62	}
96518518 PM	63
935b7f64 MM	64	static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
	65	struct nft_regs *regs,
	66	const struct nft_pktinfo *pkt)
	67	{
	68	u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
	69	struct nft_exthdr *priv = nft_expr_priv(expr);
	70	unsigned int i, optl, tcphdr_len, offset;
	71	u32 *dest = &regs->data[priv->dreg];
	72	struct tcphdr *tcph;
	73	u8 *opt;
	74
	75	if (!pkt->tprot_set \|\| pkt->tprot != IPPROTO_TCP)
	76	goto err;
	77
	78	tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, sizeof(*tcph), buff);
	79	if (!tcph)
	80	goto err;
	81
	82	tcphdr_len = __tcp_hdrlen(tcph);
	83	if (tcphdr_len < sizeof(*tcph))
	84	goto err;
	85
	86	tcph = skb_header_pointer(pkt->skb, pkt->xt.thoff, tcphdr_len, buff);
	87	if (!tcph)
	88	goto err;
	89
	90	opt = (u8 *)tcph;
	91	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
	92	optl = optlen(opt, i);
	93
	94	if (priv->type != opt[i])
	95	continue;
	96
	97	if (i + optl > tcphdr_len \|\| priv->len + priv->offset > optl)
	98	goto err;
	99
	100	offset = i + priv->offset;
	101	dest[priv->len / NFT_REG32_SIZE] = 0;
	102	memcpy(dest, opt + offset, priv->len);
	103
	104	return;
	105	}
	106
	107	err:
	108	regs->verdict.code = NFT_BREAK;
	109	}
	110
96518518 PM	111	static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
	112	[NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
	113	[NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
	114	[NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
	115	[NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
c078ca3b	116	[NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 },
96518518 PM	117	};
	118
	119	static int nft_exthdr_init(const struct nft_ctx *ctx,
	120	const struct nft_expr *expr,
	121	const struct nlattr * const tb[])
	122	{
	123	struct nft_exthdr *priv = nft_expr_priv(expr);
935b7f64	124	u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
21a9e0f1	125	int err;
96518518	126
935b7f64 MM	127	if (!tb[NFTA_EXTHDR_DREG] \|\|
	128	!tb[NFTA_EXTHDR_TYPE] \|\|
	129	!tb[NFTA_EXTHDR_OFFSET] \|\|
	130	!tb[NFTA_EXTHDR_LEN])
96518518 PM	131	return -EINVAL;
96518518 PM	132
36b701fa LGL	133	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
	134	if (err < 0)
	135	return err;
4da449ae	136
36b701fa LGL	137	err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
	138	if (err < 0)
	139	return err;
4da449ae	140
c078ca3b PS	141	if (tb[NFTA_EXTHDR_FLAGS]) {
	142	err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
	143	if (err < 0)
	144	return err;
	145
	146	if (flags & ~NFT_EXTHDR_F_PRESENT)
	147	return -EINVAL;
	148	}
	149
935b7f64 MM	150	if (tb[NFTA_EXTHDR_OP]) {
	151	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
	152	if (err < 0)
	153	return err;
	154	}
	155
96518518	156	priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
4da449ae LGL	157	priv->offset = offset;
4da449ae LGL	158	priv->len = len;
b1c96ed3	159	priv->dreg = nft_parse_register(tb[NFTA_EXTHDR_DREG]);
c078ca3b	160	priv->flags = flags;
935b7f64	161	priv->op = op;
96518518	162
1ec10212 PM	163	return nft_validate_register_store(ctx, priv->dreg, NULL,
1ec10212 PM	164	NFT_DATA_VALUE, priv->len);
96518518 PM	165	}
	166
	167	static int nft_exthdr_dump(struct sk_buff skb, const struct nft_expr expr)
	168	{
	169	const struct nft_exthdr *priv = nft_expr_priv(expr);
	170
b1c96ed3	171	if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
96518518 PM	172	goto nla_put_failure;
	173	if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
	174	goto nla_put_failure;
	175	if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
	176	goto nla_put_failure;
	177	if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
	178	goto nla_put_failure;
c078ca3b PS	179	if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
c078ca3b PS	180	goto nla_put_failure;
935b7f64 MM	181	if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
935b7f64 MM	182	goto nla_put_failure;
96518518 PM	183	return 0;
	184
	185	nla_put_failure:
	186	return -1;
	187	}
	188
ef1f7df9	189	static struct nft_expr_type nft_exthdr_type;
935b7f64 MM	190	static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
	191	.type = &nft_exthdr_type,
	192	.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	193	.eval = nft_exthdr_ipv6_eval,
	194	.init = nft_exthdr_init,
	195	.dump = nft_exthdr_dump,
	196	};
	197
	198	static const struct nft_expr_ops nft_exthdr_tcp_ops = {
ef1f7df9	199	.type = &nft_exthdr_type,
96518518	200	.size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
935b7f64	201	.eval = nft_exthdr_tcp_eval,
96518518 PM	202	.init = nft_exthdr_init,
96518518 PM	203	.dump = nft_exthdr_dump,
ef1f7df9 PM	204	};
ef1f7df9 PM	205
935b7f64 MM	206	static const struct nft_expr_ops *
	207	nft_exthdr_select_ops(const struct nft_ctx *ctx,
	208	const struct nlattr * const tb[])
	209	{
	210	u32 op;
	211
	212	if (!tb[NFTA_EXTHDR_OP])
	213	return &nft_exthdr_ipv6_ops;
	214
	215	op = ntohl(nla_get_u32(tb[NFTA_EXTHDR_OP]));
	216	switch (op) {
	217	case NFT_EXTHDR_OP_TCPOPT:
	218	return &nft_exthdr_tcp_ops;
	219	case NFT_EXTHDR_OP_IPV6:
	220	return &nft_exthdr_ipv6_ops;
	221	}
	222
	223	return ERR_PTR(-EOPNOTSUPP);
	224	}
	225
ef1f7df9 PM	226	static struct nft_expr_type nft_exthdr_type __read_mostly = {
ef1f7df9 PM	227	.name = "exthdr",
935b7f64	228	.select_ops = &nft_exthdr_select_ops,
96518518 PM	229	.policy = nft_exthdr_policy,
96518518 PM	230	.maxattr = NFTA_EXTHDR_MAX,
ef1f7df9	231	.owner = THIS_MODULE,
96518518 PM	232	};
	233
	234	static int __init nft_exthdr_module_init(void)
	235	{
ef1f7df9	236	return nft_register_expr(&nft_exthdr_type);
96518518 PM	237	}
	238
	239	static void __exit nft_exthdr_module_exit(void)
	240	{
ef1f7df9	241	nft_unregister_expr(&nft_exthdr_type);
96518518 PM	242	}
	243
	244	module_init(nft_exthdr_module_init);
	245	module_exit(nft_exthdr_module_exit);
	246
	247	MODULE_LICENSE("GPL");
	248	MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
	249	MODULE_ALIAS_NFT_EXPR("exthdr");