[linux-block.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 {
	u8			dreg;
	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;

	if (pkt->tprot != IPPROTO_TCP) {
		regs->verdict.code = NFT_BREAK;
		return;
	}

	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;
	}

	err = nft_parse_register_store(ctx, tb[NFTA_OSF_DREG], &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 bool nft_osf_reduce(struct nft_regs_track *track,
			   const struct nft_expr *expr)
{
	struct nft_osf *priv = nft_expr_priv(expr);
	struct nft_osf *osf;

	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
		nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
		return false;
	}

	osf = nft_expr_priv(track->regs[priv->dreg].selector);
	if (priv->flags != osf->flags ||
	    priv->ttl != osf->ttl) {
		nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
		return false;
	}

	if (!track->regs[priv->dreg].bitwise)
		return true;

	return false;
}

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,
	.reduce		= nft_osf_reduce,
};

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	8	struct nft_osf {
345023b0	9	u8 dreg;
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	30
8f518d43 PNA	31	if (pkt->tprot != IPPROTO_TCP) {
	32	regs->verdict.code = NFT_BREAK;
	33	return;
	34	}
	35
b96af92d FFM	36	tcp = skb_header_pointer(skb, ip_hdrlen(skb),
	37	sizeof(struct tcphdr), &_tcph);
	38	if (!tcp) {
	39	regs->verdict.code = NFT_BREAK;
	40	return;
	41	}
	42	if (!tcp->syn) {
	43	regs->verdict.code = NFT_BREAK;
	44	return;
	45	}
	46
22c7652c	47	if (!nf_osf_find(skb, nf_osf_fingers, priv->ttl, &data)) {
35a8a3bd	48	strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
22c7652c FFM	49	} else {
	50	if (priv->flags & NFT_OSF_F_VERSION)
	51	snprintf(os_match, NFT_OSF_MAXGENRELEN, "%s:%s",
	52	data.genre, data.version);
	53	else
	54	strlcpy(os_match, data.genre, NFT_OSF_MAXGENRELEN);
	55
	56	strncpy((char *)dest, os_match, NFT_OSF_MAXGENRELEN);
	57	}
b96af92d FFM	58	}
	59
	60	static int nft_osf_init(const struct nft_ctx *ctx,
	61	const struct nft_expr *expr,
	62	const struct nlattr * const tb[])
	63	{
	64	struct nft_osf *priv = nft_expr_priv(expr);
22c7652c	65	u32 flags;
b96af92d	66	int err;
a218dc82 FFM	67	u8 ttl;
a218dc82 FFM	68
7eaecf79 FW	69	if (!tb[NFTA_OSF_DREG])
	70	return -EINVAL;
	71
5e91c9d9	72	if (tb[NFTA_OSF_TTL]) {
a218dc82 FFM	73	ttl = nla_get_u8(tb[NFTA_OSF_TTL]);
	74	if (ttl > 2)
	75	return -EINVAL;
	76	priv->ttl = ttl;
	77	}
b96af92d	78
22c7652c FFM	79	if (tb[NFTA_OSF_FLAGS]) {
	80	flags = ntohl(nla_get_be32(tb[NFTA_OSF_FLAGS]));
	81	if (flags != NFT_OSF_F_VERSION)
	82	return -EINVAL;
	83	priv->flags = flags;
	84	}
	85
345023b0 PNA	86	err = nft_parse_register_store(ctx, tb[NFTA_OSF_DREG], &priv->dreg,
	87	NULL, NFT_DATA_VALUE,
	88	NFT_OSF_MAXGENRELEN);
b96af92d FFM	89	if (err < 0)
	90	return err;
	91
	92	return 0;
	93	}
	94
	95	static int nft_osf_dump(struct sk_buff skb, const struct nft_expr expr)
	96	{
	97	const struct nft_osf *priv = nft_expr_priv(expr);
	98
a218dc82 FFM	99	if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))
	100	goto nla_put_failure;
	101
22c7652c FFM	102	if (nla_put_be32(skb, NFTA_OSF_FLAGS, ntohl(priv->flags)))
	103	goto nla_put_failure;
	104
b96af92d FFM	105	if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
	106	goto nla_put_failure;
	107
	108	return 0;
	109
	110	nla_put_failure:
	111	return -1;
	112	}
	113
4a3e71b7 FFM	114	static int nft_osf_validate(const struct nft_ctx *ctx,
	115	const struct nft_expr *expr,
	116	const struct nft_data **data)
	117	{
	118	return nft_chain_validate_hooks(ctx->chain, (1 << NF_INET_LOCAL_IN) \|
	119	(1 << NF_INET_PRE_ROUTING) \|
	120	(1 << NF_INET_FORWARD));
	121	}
	122
ffe6488e PNA	123	static bool nft_osf_reduce(struct nft_regs_track *track,
	124	const struct nft_expr *expr)
	125	{
	126	struct nft_osf *priv = nft_expr_priv(expr);
	127	struct nft_osf *osf;
	128
	129	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
	130	nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
	131	return false;
	132	}
	133
	134	osf = nft_expr_priv(track->regs[priv->dreg].selector);
	135	if (priv->flags != osf->flags \|\|
	136	priv->ttl != osf->ttl) {
	137	nft_reg_track_update(track, expr, priv->dreg, NFT_OSF_MAXGENRELEN);
	138	return false;
	139	}
	140
	141	if (!track->regs[priv->dreg].bitwise)
	142	return true;
	143
	144	return false;
	145	}
	146
b96af92d FFM	147	static struct nft_expr_type nft_osf_type;
	148	static const struct nft_expr_ops nft_osf_op = {
	149	.eval = nft_osf_eval,
	150	.size = NFT_EXPR_SIZE(sizeof(struct nft_osf)),
	151	.init = nft_osf_init,
	152	.dump = nft_osf_dump,
	153	.type = &nft_osf_type,
4a3e71b7	154	.validate = nft_osf_validate,
ffe6488e	155	.reduce = nft_osf_reduce,
b96af92d FFM	156	};
	157
	158	static struct nft_expr_type nft_osf_type __read_mostly = {
	159	.ops = &nft_osf_op,
	160	.name = "osf",
	161	.owner = THIS_MODULE,
	162	.policy = nft_osf_policy,
	163	.maxattr = NFTA_OSF_MAX,
	164	};
	165
	166	static int __init nft_osf_module_init(void)
	167	{
	168	return nft_register_expr(&nft_osf_type);
	169	}
	170
	171	static void __exit nft_osf_module_exit(void)
	172	{
	173	return nft_unregister_expr(&nft_osf_type);
	174	}
	175
	176	module_init(nft_osf_module_init);
	177	module_exit(nft_osf_module_exit);
	178
	179	MODULE_LICENSE("GPL");
	180	MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
	181	MODULE_ALIAS_NFT_EXPR("osf");
4cacc395	182	MODULE_DESCRIPTION("nftables passive OS fingerprint support");