[mirror_ubuntu-hirsute-kernel.git] / net / netfilter / nft_osf.c

// SPDX-License-Identifier: GPL-2.0-only
#include <net/ip.h>
#include <net/tcp.h>

#include <net/netfilter/nf_tables.h>
#include <linux/netfilter/nfnetlink_osf.h>

struct nft_osf {
	enum nft_registers	dreg:8;
	u8			ttl;
	u32			flags;
};

static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
	[NFTA_OSF_DREG]		= { .type = NLA_U32 },
	[NFTA_OSF_TTL]		= { .type = NLA_U8 },
	[NFTA_OSF_FLAGS]	= { .type = NLA_U32 },
};

static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
			 const struct nft_pktinfo *pkt)
{
	struct nft_osf *priv = nft_expr_priv(expr);
	u32 *dest = &regs->data[priv->dreg];
	struct sk_buff *skb = pkt->skb;
	char os_match[NFT_OSF_MAXGENRELEN + 1];
	const struct tcphdr *tcp;
	struct nf_osf_data data;
	struct tcphdr _tcph;

	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
				 sizeof(struct tcphdr), &_tcph);
	if (!tcp) {
		regs->verdict.code = NFT_BREAK;
		return;
	}
	if (!tcp->syn) {
		regs->verdict.code = NFT_BREAK;
		return;
	}

	if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) {
		strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
	} else {
		if (priv->flags & NFT_OSF_F_VERSION)
			snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s",
				 data.genre, data.version);
		else
			strlcpy(os_match, data.genre, NFT_OSF_MAXGENRELEN);

		strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
	}
}

static int nft_osf_init(const struct nft_ctx *ctx,
			const struct nft_expr *expr,
			const struct nlattr * const tb[])
{
	struct nft_osf *priv = nft_expr_priv(expr);
	u32 flags;
	int err;
	u8 ttl;

	if (!tb[NFTA_OSF_DREG])
		return -EINVAL;

	if (tb[NFTA_OSF_TTL]) {
		ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
		if (ttl > 2)
			return -EINVAL;
		priv->ttl = ttl;
	}

	if (tb[NFTA_OSF_FLAGS]) {
		flags = ntohl(nla_get_be32(tb[NFTA_OSF_FLAGS]));
		if (flags != NFT_OSF_F_VERSION)
			return -EINVAL;
		priv->flags = flags;
	}

	priv->dreg = nft_parse_register(tb[NFTA_OSF_DREG]);
	err = nft_validate_register_store(ctx, priv->dreg, NULL,
					  NFT_DATA_VALUE, NFT_OSF_MAXGENRELEN);
	if (err < 0)
		return err;

	return 0;
}

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

	if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
		goto nla_put_failure;

	if (nla_put_be32(skb, NFTA_OSF_FLAGS, ntohl(priv->flags)))
		goto nla_put_failure;

	if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
		goto nla_put_failure;

	return 0;

nla_put_failure:
	return -1;
}

static int nft_osf_validate(const struct nft_ctx *ctx,
			    const struct nft_expr *expr,
			    const struct nft_data **data)
{
	return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) |
						    (1 << NF_INET_PRE_ROUTING) |
						    (1 << NF_INET_FORWARD));
}

static struct nft_expr_type nft_osf_type;
static const struct nft_expr_ops nft_osf_op = {
	.eval		= nft_osf_eval,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_osf)),
	.init		= nft_osf_init,
	.dump		= nft_osf_dump,
	.type		= &nft_osf_type,
	.validate	= nft_osf_validate,
};

static struct nft_expr_type nft_osf_type __read_mostly = {
	.ops		= &nft_osf_op,
	.name		= "osf",
	.owner		= THIS_MODULE,
	.policy		= nft_osf_policy,
	.maxattr	= NFTA_OSF_MAX,
};

static int __init nft_osf_module_init(void)
{
	return nft_register_expr(&nft_osf_type);
}

static void __exit nft_osf_module_exit(void)
{
	return nft_unregister_expr(&nft_osf_type);
}

module_init(nft_osf_module_init);
module_exit(nft_osf_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
MODULE_ALIAS_NFT_EXPR("osf");
MODULE_DESCRIPTION("nftables passive OS fingerprint support");
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
b96af92d FFM	2	#include <net/ip.h>
	3	#include <net/tcp.h>
	4
	5	#include <net/netfilter/nf_tables.h>
ddba40be	6	#include <linux/netfilter/nfnetlink_osf.h>
b96af92d	7
b96af92d FFM	8	struct nft_osf {
b96af92d FFM	9	enum nft_registers dreg:8;
a218dc82	10	u8 ttl;
22c7652c	11	u32 flags;
b96af92d FFM	12	};
	13
	14	static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
	15	[NFTA_OSF_DREG] = { .type = NLA_U32 },
a218dc82	16	[NFTA_OSF_TTL] = { .type = NLA_U8 },
22c7652c	17	[NFTA_OSF_FLAGS] = { .type = NLA_U32 },
b96af92d FFM	18	};
	19
	20	static void nft_osf_eval(const struct nft_expr expr, struct nft_regs regs,
	21	const struct nft_pktinfo *pkt)
	22	{
	23	struct nft_osf *priv = nft_expr_priv(expr);
	24	u32 *dest = &regs->data[priv->dreg];
	25	struct sk_buff *skb = pkt->skb;
22c7652c	26	char os_match[NFT_OSF_MAXGENRELEN + 1];
b96af92d	27	const struct tcphdr *tcp;
22c7652c	28	struct nf_osf_data data;
b96af92d	29	struct tcphdr _tcph;
b96af92d FFM	30
	31	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
	32	sizeof(struct tcphdr), &_tcph);
	33	if (!tcp) {
	34	regs->verdict.code = NFT_BREAK;
	35	return;
	36	}
	37	if (!tcp->syn) {
	38	regs->verdict.code = NFT_BREAK;
	39	return;
	40	}
	41
22c7652c	42	if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) {
35a8a3bd	43	strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
22c7652c FFM	44	} else {
	45	if (priv->flags & NFT_OSF_F_VERSION)
	46	snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s",
	47	data.genre, data.version);
	48	else
	49	strlcpy(os_match, data.genre, NFT_OSF_MAXGENRELEN);
	50
	51	strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
	52	}
b96af92d FFM	53	}
	54
	55	static int nft_osf_init(const struct nft_ctx *ctx,
	56	const struct nft_expr *expr,
	57	const struct nlattr * const tb[])
	58	{
	59	struct nft_osf *priv = nft_expr_priv(expr);
22c7652c	60	u32 flags;
b96af92d	61	int err;
a218dc82 FFM	62	u8 ttl;
a218dc82 FFM	63
7eaecf79 FW	64	if (!tb[NFTA_OSF_DREG])
	65	return -EINVAL;
	66
5e91c9d9	67	if (tb[NFTA_OSF_TTL]) {
a218dc82 FFM	68	ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
	69	if (ttl > 2)
	70	return -EINVAL;
	71	priv->ttl = ttl;
	72	}
b96af92d	73
22c7652c FFM	74	if (tb[NFTA_OSF_FLAGS]) {
	75	flags = ntohl(nla_get_be32(tb[NFTA_OSF_FLAGS]));
	76	if (flags != NFT_OSF_F_VERSION)
	77	return -EINVAL;
	78	priv->flags = flags;
	79	}
	80
b96af92d FFM	81	priv->dreg = nft_parse_register(tb[NFTA_OSF_DREG]);
b96af92d FFM	82	err = nft_validate_register_store(ctx, priv->dreg, NULL,
bab43449	83	NFT_DATA_VALUE, NFT_OSF_MAXGENRELEN);
b96af92d FFM	84	if (err < 0)
	85	return err;
	86
	87	return 0;
	88	}
	89
	90	static int nft_osf_dump(struct sk_buff skb, const struct nft_expr expr)
	91	{
	92	const struct nft_osf *priv = nft_expr_priv(expr);
	93
a218dc82 FFM	94	if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
	95	goto nla_put_failure;
	96
22c7652c FFM	97	if (nla_put_be32(skb, NFTA_OSF_FLAGS, ntohl(priv->flags)))
	98	goto nla_put_failure;
	99
b96af92d FFM	100	if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
	101	goto nla_put_failure;
	102
	103	return 0;
	104
	105	nla_put_failure:
	106	return -1;
	107	}
	108
4a3e71b7 FFM	109	static int nft_osf_validate(const struct nft_ctx *ctx,
	110	const struct nft_expr *expr,
	111	const struct nft_data **data)
	112	{
	113	return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) \|
	114	(1 << NF_INET_PRE_ROUTING) \|
	115	(1 << NF_INET_FORWARD));
	116	}
	117
b96af92d FFM	118	static struct nft_expr_type nft_osf_type;
	119	static const struct nft_expr_ops nft_osf_op = {
	120	.eval = nft_osf_eval,
	121	.size = NFT_EXPR_SIZE(sizeof(struct nft_osf)),
	122	.init = nft_osf_init,
	123	.dump = nft_osf_dump,
	124	.type = &nft_osf_type,
4a3e71b7	125	.validate = nft_osf_validate,
b96af92d FFM	126	};
	127
	128	static struct nft_expr_type nft_osf_type __read_mostly = {
	129	.ops = &nft_osf_op,
	130	.name = "osf",
	131	.owner = THIS_MODULE,
	132	.policy = nft_osf_policy,
	133	.maxattr = NFTA_OSF_MAX,
	134	};
	135
	136	static int __init nft_osf_module_init(void)
	137	{
	138	return nft_register_expr(&nft_osf_type);
	139	}
	140
	141	static void __exit nft_osf_module_exit(void)
	142	{
	143	return nft_unregister_expr(&nft_osf_type);
	144	}
	145
	146	module_init(nft_osf_module_init);
	147	module_exit(nft_osf_module_exit);
	148
	149	MODULE_LICENSE("GPL");
	150	MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
	151	MODULE_ALIAS_NFT_EXPR("osf");
4cacc395	152	MODULE_DESCRIPTION("nftables passive OS fingerprint support");