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

// SPDX-License-Identifier: GPL-2.0-only
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>

#include <linux/capability.h>
#include <linux/if.h>
#include <linux/inetdevice.h>
#include <linux/ip.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/tcp.h>

#include <net/ip.h>
#include <net/tcp.h>

#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_log.h>
#include <linux/netfilter/nfnetlink_osf.h>

/*
 * Indexed by dont-fragment bit.
 * It is the only constant value in the fingerprint.
 */
struct list_head nf_osf_fingers[2];
EXPORT_SYMBOL_GPL(nf_osf_fingers);

static inline int nf_osf_ttl(const struct sk_buff *skb,
			     int ttl_check, unsigned char f_ttl)
{
	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
	const struct iphdr *ip = ip_hdr(skb);
	const struct in_ifaddr *ifa;
	int ret = 0;

	if (ttl_check == NF_OSF_TTL_TRUE)
		return ip->ttl == f_ttl;
	if (ttl_check == NF_OSF_TTL_NOCHECK)
		return 1;
	else if (ip->ttl <= f_ttl)
		return 1;

	in_dev_for_each_ifa_rcu(ifa, in_dev) {
		if (inet_ifa_match(ip->saddr, ifa)) {
			ret = (ip->ttl == f_ttl);
			break;
		}
	}

	return ret;
}

struct nf_osf_hdr_ctx {
	bool			df;
	u16			window;
	u16			totlen;
	const unsigned char	*optp;
	unsigned int		optsize;
};

static bool nf_osf_match_one(const struct sk_buff *skb,
			     const struct nf_osf_user_finger *f,
			     int ttl_check,
			     struct nf_osf_hdr_ctx *ctx)
{
	const __u8 *optpinit = ctx->optp;
	unsigned int check_WSS = 0;
	int fmatch = FMATCH_WRONG;
	int foptsize, optnum;
	u16 mss = 0;

	if (ctx->totlen != f->ss || !nf_osf_ttl(skb, ttl_check, f->ttl))
		return false;

	/*
	 * Should not happen if userspace parser was written correctly.
	 */
	if (f->wss.wc >= OSF_WSS_MAX)
		return false;

	/* Check options */

	foptsize = 0;
	for (optnum = 0; optnum < f->opt_num; ++optnum)
		foptsize += f->opt[optnum].length;

	if (foptsize > MAX_IPOPTLEN ||
	    ctx->optsize > MAX_IPOPTLEN ||
	    ctx->optsize != foptsize)
		return false;

	check_WSS = f->wss.wc;

	for (optnum = 0; optnum < f->opt_num; ++optnum) {
		if (f->opt[optnum].kind == *ctx->optp) {
			__u32 len = f->opt[optnum].length;
			const __u8 *optend = ctx->optp + len;

			fmatch = FMATCH_OK;

			switch (*ctx->optp) {
			case OSFOPT_MSS:
				mss = ctx->optp[3];
				mss <<= 8;
				mss |= ctx->optp[2];

				mss = ntohs((__force __be16)mss);
				break;
			case OSFOPT_TS:
				break;
			}

			ctx->optp = optend;
		} else
			fmatch = FMATCH_OPT_WRONG;

		if (fmatch != FMATCH_OK)
			break;
	}

	if (fmatch != FMATCH_OPT_WRONG) {
		fmatch = FMATCH_WRONG;

		switch (check_WSS) {
		case OSF_WSS_PLAIN:
			if (f->wss.val == 0 || ctx->window == f->wss.val)
				fmatch = FMATCH_OK;
			break;
		case OSF_WSS_MSS:
			/*
			 * Some smart modems decrease mangle MSS to
			 * SMART_MSS_2, so we check standard, decreased
			 * and the one provided in the fingerprint MSS
			 * values.
			 */
#define SMART_MSS_1	1460
#define SMART_MSS_2	1448
			if (ctx->window == f->wss.val * mss ||
			    ctx->window == f->wss.val * SMART_MSS_1 ||
			    ctx->window == f->wss.val * SMART_MSS_2)
				fmatch = FMATCH_OK;
			break;
		case OSF_WSS_MTU:
			if (ctx->window == f->wss.val * (mss + 40) ||
			    ctx->window == f->wss.val * (SMART_MSS_1 + 40) ||
			    ctx->window == f->wss.val * (SMART_MSS_2 + 40))
				fmatch = FMATCH_OK;
			break;
		case OSF_WSS_MODULO:
			if ((ctx->window % f->wss.val) == 0)
				fmatch = FMATCH_OK;
			break;
		}
	}

	if (fmatch != FMATCH_OK)
		ctx->optp = optpinit;

	return fmatch == FMATCH_OK;
}

static const struct tcphdr *nf_osf_hdr_ctx_init(struct nf_osf_hdr_ctx *ctx,
						const struct sk_buff *skb,
						const struct iphdr *ip,
						unsigned char *opts,
						struct tcphdr *_tcph)
{
	const struct tcphdr *tcp;

	tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), _tcph);
	if (!tcp)
		return NULL;

	if (!tcp->syn)
		return NULL;

	ctx->totlen = ntohs(ip->tot_len);
	ctx->df = ntohs(ip->frag_off) & IP_DF;
	ctx->window = ntohs(tcp->window);

	if (tcp->doff * 4 > sizeof(struct tcphdr)) {
		ctx->optsize = tcp->doff * 4 - sizeof(struct tcphdr);

		ctx->optp = skb_header_pointer(skb, ip_hdrlen(skb) +
				sizeof(struct tcphdr), ctx->optsize, opts);
		if (!ctx->optp)
			return NULL;
	}

	return tcp;
}

bool
nf_osf_match(const struct sk_buff *skb, u_int8_t family,
	     int hooknum, struct net_device *in, struct net_device *out,
	     const struct nf_osf_info *info, struct net *net,
	     const struct list_head *nf_osf_fingers)
{
	const struct iphdr *ip = ip_hdr(skb);
	const struct nf_osf_user_finger *f;
	unsigned char opts[MAX_IPOPTLEN];
	const struct nf_osf_finger *kf;
	int fcount = 0, ttl_check;
	int fmatch = FMATCH_WRONG;
	struct nf_osf_hdr_ctx ctx;
	const struct tcphdr *tcp;
	struct tcphdr _tcph;

	memset(&ctx, 0, sizeof(ctx));

	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
	if (!tcp)
		return false;

	ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : 0;

	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {

		f = &kf->finger;

		if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
			continue;

		if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
			continue;

		fmatch = FMATCH_OK;

		fcount++;

		if (info->flags & NF_OSF_LOG)
			nf_log_packet(net, family, hooknum, skb,
				      in, out, NULL,
				      "%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n",
				      f->genre, f->version, f->subtype,
				      &ip->saddr, ntohs(tcp->source),
				      &ip->daddr, ntohs(tcp->dest),
				      f->ttl - ip->ttl);

		if ((info->flags & NF_OSF_LOG) &&
		    info->loglevel == NF_OSF_LOGLEVEL_FIRST)
			break;
	}

	if (!fcount && (info->flags & NF_OSF_LOG))
		nf_log_packet(net, family, hooknum, skb, in, out, NULL,
			      "Remote OS is not known: %pI4:%u -> %pI4:%u\n",
			      &ip->saddr, ntohs(tcp->source),
			      &ip->daddr, ntohs(tcp->dest));

	if (fcount)
		fmatch = FMATCH_OK;

	return fmatch == FMATCH_OK;
}
EXPORT_SYMBOL_GPL(nf_osf_match);

bool nf_osf_find(const struct sk_buff *skb,
		 const struct list_head *nf_osf_fingers,
		 const int ttl_check, struct nf_osf_data *data)
{
	const struct iphdr *ip = ip_hdr(skb);
	const struct nf_osf_user_finger *f;
	unsigned char opts[MAX_IPOPTLEN];
	const struct nf_osf_finger *kf;
	struct nf_osf_hdr_ctx ctx;
	const struct tcphdr *tcp;
	struct tcphdr _tcph;
	bool found = false;

	memset(&ctx, 0, sizeof(ctx));

	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
	if (!tcp)
		return false;

	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
		f = &kf->finger;
		if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
			continue;

		data->genre = f->genre;
		data->version = f->version;
		found = true;
		break;
	}

	return found;
}
EXPORT_SYMBOL_GPL(nf_osf_find);

static const struct nla_policy nfnl_osf_policy[OSF_ATTR_MAX + 1] = {
	[OSF_ATTR_FINGER]	= { .len = sizeof(struct nf_osf_user_finger) },
};

static int nfnl_osf_add_callback(struct sk_buff *skb,
				 const struct nfnl_info *info,
				 const struct nlattr * const osf_attrs[])
{
	struct nf_osf_user_finger *f;
	struct nf_osf_finger *kf = NULL, *sf;
	int err = 0;

	if (!capable(CAP_NET_ADMIN))
		return -EPERM;

	if (!osf_attrs[OSF_ATTR_FINGER])
		return -EINVAL;

	if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
		return -EINVAL;

	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

	kf = kmalloc(sizeof(struct nf_osf_finger), GFP_KERNEL);
	if (!kf)
		return -ENOMEM;

	memcpy(&kf->finger, f, sizeof(struct nf_osf_user_finger));

	list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
		if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
			continue;

		kfree(kf);
		kf = NULL;

		if (info->nlh->nlmsg_flags & NLM_F_EXCL)
			err = -EEXIST;
		break;
	}

	/*
	 * We are protected by nfnl mutex.
	 */
	if (kf)
		list_add_tail_rcu(&kf->finger_entry, &nf_osf_fingers[!!f->df]);

	return err;
}

static int nfnl_osf_remove_callback(struct sk_buff *skb,
				    const struct nfnl_info *info,
				    const struct nlattr * const osf_attrs[])
{
	struct nf_osf_user_finger *f;
	struct nf_osf_finger *sf;
	int err = -ENOENT;

	if (!capable(CAP_NET_ADMIN))
		return -EPERM;

	if (!osf_attrs[OSF_ATTR_FINGER])
		return -EINVAL;

	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

	list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
		if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
			continue;

		/*
		 * We are protected by nfnl mutex.
		 */
		list_del_rcu(&sf->finger_entry);
		kfree_rcu(sf, rcu_head);

		err = 0;
		break;
	}

	return err;
}

static const struct nfnl_callback nfnl_osf_callbacks[OSF_MSG_MAX] = {
	[OSF_MSG_ADD]	= {
		.call		= nfnl_osf_add_callback,
		.type		= NFNL_CB_MUTEX,
		.attr_count	= OSF_ATTR_MAX,
		.policy		= nfnl_osf_policy,
	},
	[OSF_MSG_REMOVE]	= {
		.call		= nfnl_osf_remove_callback,
		.type		= NFNL_CB_MUTEX,
		.attr_count	= OSF_ATTR_MAX,
		.policy		= nfnl_osf_policy,
	},
};

static const struct nfnetlink_subsystem nfnl_osf_subsys = {
	.name			= "osf",
	.subsys_id		= NFNL_SUBSYS_OSF,
	.cb_count		= OSF_MSG_MAX,
	.cb			= nfnl_osf_callbacks,
};

static int __init nfnl_osf_init(void)
{
	int err = -EINVAL;
	int i;

	for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i)
		INIT_LIST_HEAD(&nf_osf_fingers[i]);

	err = nfnetlink_subsys_register(&nfnl_osf_subsys);
	if (err < 0) {
		pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
		goto err_out_exit;
	}
	return 0;

err_out_exit:
	return err;
}

static void __exit nfnl_osf_fini(void)
{
	struct nf_osf_finger *f;
	int i;

	nfnetlink_subsys_unregister(&nfnl_osf_subsys);

	rcu_read_lock();
	for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i) {
		list_for_each_entry_rcu(f, &nf_osf_fingers[i], finger_entry) {
			list_del_rcu(&f->finger_entry);
			kfree_rcu(f, rcu_head);
		}
	}
	rcu_read_unlock();

	rcu_barrier();
}

module_init(nfnl_osf_init);
module_exit(nfnl_osf_fini);

MODULE_LICENSE("GPL");
Commit	Line	Data
09c434b8	1	// SPDX-License-Identifier: GPL-2.0-only
bfb15f2a FFM	2	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	3	#include <linux/module.h>
	4	#include <linux/kernel.h>
	5
	6	#include <linux/capability.h>
	7	#include <linux/if.h>
	8	#include <linux/inetdevice.h>
	9	#include <linux/ip.h>
	10	#include <linux/list.h>
	11	#include <linux/rculist.h>
	12	#include <linux/skbuff.h>
	13	#include <linux/slab.h>
	14	#include <linux/tcp.h>
	15
	16	#include <net/ip.h>
	17	#include <net/tcp.h>
	18
	19	#include <linux/netfilter/nfnetlink.h>
	20	#include <linux/netfilter/x_tables.h>
	21	#include <net/netfilter/nf_log.h>
ddba40be	22	#include <linux/netfilter/nfnetlink_osf.h>
bfb15f2a	23
f9324952 FFM	24	/*
	25	* Indexed by dont-fragment bit.
	26	* It is the only constant value in the fingerprint.
	27	*/
	28	struct list_head nf_osf_fingers[2];
	29	EXPORT_SYMBOL_GPL(nf_osf_fingers);
	30
bfb15f2a	31	static inline int nf_osf_ttl(const struct sk_buff *skb,
06ff4aa2	32	int ttl_check, unsigned char f_ttl)
bfb15f2a	33	{
a218dc82	34	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
bfb15f2a	35	const struct iphdr *ip = ip_hdr(skb);
b8d19572	36	const struct in_ifaddr *ifa;
a218dc82 FFM	37	int ret = 0;
	38
	39	if (ttl_check == NF_OSF_TTL_TRUE)
	40	return ip->ttl == f_ttl;
	41	if (ttl_check == NF_OSF_TTL_NOCHECK)
	42	return 1;
	43	else if (ip->ttl <= f_ttl)
	44	return 1;
	45
b8d19572	46	in_dev_for_each_ifa_rcu(ifa, in_dev) {
a218dc82 FFM	47	if (inet_ifa_match(ip->saddr, ifa)) {
	48	ret = (ip->ttl == f_ttl);
	49	break;
bfb15f2a FFM	50	}
	51	}
	52
a218dc82	53	return ret;
bfb15f2a FFM	54	}
bfb15f2a FFM	55
31a9c292 PNA	56	struct nf_osf_hdr_ctx {
	57	bool df;
	58	u16 window;
	59	u16 totlen;
	60	const unsigned char *optp;
	61	unsigned int optsize;
	62	};
	63
06ff4aa2 PNA	64	static bool nf_osf_match_one(const struct sk_buff *skb,
06ff4aa2 PNA	65	const struct nf_osf_user_finger *f,
31a9c292 PNA	66	int ttl_check,
31a9c292 PNA	67	struct nf_osf_hdr_ctx *ctx)
06ff4aa2	68	{
1a6a0951	69	const __u8 *optpinit = ctx->optp;
06ff4aa2 PNA	70	unsigned int check_WSS = 0;
	71	int fmatch = FMATCH_WRONG;
	72	int foptsize, optnum;
	73	u16 mss = 0;
	74
31a9c292	75	if (ctx->totlen != f->ss \|\| !nf_osf_ttl(skb, ttl_check, f->ttl))
06ff4aa2 PNA	76	return false;
	77
	78	/*
	79	* Should not happen if userspace parser was written correctly.
	80	*/
	81	if (f->wss.wc >= OSF_WSS_MAX)
	82	return false;
	83
	84	/* Check options */
	85
	86	foptsize = 0;
	87	for (optnum = 0; optnum < f->opt_num; ++optnum)
	88	foptsize += f->opt[optnum].length;
	89
	90	if (foptsize > MAX_IPOPTLEN \|\|
31a9c292 PNA	91	ctx->optsize > MAX_IPOPTLEN \|\|
31a9c292 PNA	92	ctx->optsize != foptsize)
06ff4aa2 PNA	93	return false;
	94
	95	check_WSS = f->wss.wc;
	96
	97	for (optnum = 0; optnum < f->opt_num; ++optnum) {
31a9c292	98	if (f->opt[optnum].kind == *ctx->optp) {
06ff4aa2	99	__u32 len = f->opt[optnum].length;
31a9c292	100	const __u8 *optend = ctx->optp + len;
06ff4aa2 PNA	101
	102	fmatch = FMATCH_OK;
	103
31a9c292	104	switch (*ctx->optp) {
06ff4aa2	105	case OSFOPT_MSS:
31a9c292	106	mss = ctx->optp[3];
06ff4aa2	107	mss <<= 8;
31a9c292	108	mss \|= ctx->optp[2];
06ff4aa2 PNA	109
	110	mss = ntohs((__force __be16)mss);
	111	break;
	112	case OSFOPT_TS:
	113	break;
	114	}
	115
31a9c292	116	ctx->optp = optend;
06ff4aa2 PNA	117	} else
	118	fmatch = FMATCH_OPT_WRONG;
	119
	120	if (fmatch != FMATCH_OK)
	121	break;
	122	}
	123
	124	if (fmatch != FMATCH_OPT_WRONG) {
	125	fmatch = FMATCH_WRONG;
	126
	127	switch (check_WSS) {
	128	case OSF_WSS_PLAIN:
31a9c292	129	if (f->wss.val == 0 \|\| ctx->window == f->wss.val)
06ff4aa2 PNA	130	fmatch = FMATCH_OK;
	131	break;
	132	case OSF_WSS_MSS:
	133	/*
	134	* Some smart modems decrease mangle MSS to
	135	* SMART_MSS_2, so we check standard, decreased
	136	* and the one provided in the fingerprint MSS
	137	* values.
	138	*/
	139	#define SMART_MSS_1 1460
	140	#define SMART_MSS_2 1448
31a9c292 PNA	141	if (ctx->window == f->wss.val * mss \|\|
	142	ctx->window == f->wss.val * SMART_MSS_1 \|\|
	143	ctx->window == f->wss.val * SMART_MSS_2)
06ff4aa2 PNA	144	fmatch = FMATCH_OK;
	145	break;
	146	case OSF_WSS_MTU:
31a9c292 PNA	147	if (ctx->window == f->wss.val * (mss + 40) \|\|
	148	ctx->window == f->wss.val * (SMART_MSS_1 + 40) \|\|
	149	ctx->window == f->wss.val * (SMART_MSS_2 + 40))
06ff4aa2 PNA	150	fmatch = FMATCH_OK;
	151	break;
	152	case OSF_WSS_MODULO:
31a9c292	153	if ((ctx->window % f->wss.val) == 0)
06ff4aa2 PNA	154	fmatch = FMATCH_OK;
	155	break;
	156	}
	157	}
	158
1a6a0951 FFM	159	if (fmatch != FMATCH_OK)
	160	ctx->optp = optpinit;
	161
06ff4aa2 PNA	162	return fmatch == FMATCH_OK;
	163	}
	164
31a9c292 PNA	165	static const struct tcphdr nf_osf_hdr_ctx_init(struct nf_osf_hdr_ctx ctx,
	166	const struct sk_buff *skb,
	167	const struct iphdr *ip,
c165d57b AB	168	unsigned char *opts,
c165d57b AB	169	struct tcphdr *_tcph)
31a9c292 PNA	170	{
31a9c292 PNA	171	const struct tcphdr *tcp;
31a9c292	172
c165d57b	173	tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), _tcph);
31a9c292 PNA	174	if (!tcp)
	175	return NULL;
	176
	177	if (!tcp->syn)
	178	return NULL;
	179
	180	ctx->totlen = ntohs(ip->tot_len);
	181	ctx->df = ntohs(ip->frag_off) & IP_DF;
	182	ctx->window = ntohs(tcp->window);
	183
	184	if (tcp->doff * 4 > sizeof(struct tcphdr)) {
	185	ctx->optsize = tcp->doff * 4 - sizeof(struct tcphdr);
	186
	187	ctx->optp = skb_header_pointer(skb, ip_hdrlen(skb) +
	188	sizeof(struct tcphdr), ctx->optsize, opts);
5e024c32 PNA	189	if (!ctx->optp)
5e024c32 PNA	190	return NULL;
31a9c292 PNA	191	}
	192
	193	return tcp;
	194	}
	195
bfb15f2a FFM	196	bool
	197	nf_osf_match(const struct sk_buff *skb, u_int8_t family,
	198	int hooknum, struct net_device in, struct net_device out,
	199	const struct nf_osf_info info, struct net net,
	200	const struct list_head *nf_osf_fingers)
	201	{
bfb15f2a FFM	202	const struct iphdr *ip = ip_hdr(skb);
	203	const struct nf_osf_user_finger *f;
	204	unsigned char opts[MAX_IPOPTLEN];
	205	const struct nf_osf_finger *kf;
06ff4aa2 PNA	206	int fcount = 0, ttl_check;
06ff4aa2 PNA	207	int fmatch = FMATCH_WRONG;
31a9c292	208	struct nf_osf_hdr_ctx ctx;
bfb15f2a	209	const struct tcphdr *tcp;
c165d57b	210	struct tcphdr _tcph;
bfb15f2a	211
31a9c292	212	memset(&ctx, 0, sizeof(ctx));
bfb15f2a	213
c165d57b	214	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
31a9c292	215	if (!tcp)
bfb15f2a FFM	216	return false;
bfb15f2a FFM	217
a218dc82	218	ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : 0;
06ff4aa2	219
31a9c292	220	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
bfb15f2a FFM	221
	222	f = &kf->finger;
	223
	224	if (!(info->flags & NF_OSF_LOG) && strcmp(info->genre, f->genre))
	225	continue;
	226
31a9c292	227	if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
bfb15f2a FFM	228	continue;
bfb15f2a FFM	229
06ff4aa2	230	fmatch = FMATCH_OK;
bfb15f2a FFM	231
	232	fcount++;
	233
	234	if (info->flags & NF_OSF_LOG)
	235	nf_log_packet(net, family, hooknum, skb,
	236	in, out, NULL,
	237	"%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n",
	238	f->genre, f->version, f->subtype,
	239	&ip->saddr, ntohs(tcp->source),
	240	&ip->daddr, ntohs(tcp->dest),
	241	f->ttl - ip->ttl);
	242
	243	if ((info->flags & NF_OSF_LOG) &&
	244	info->loglevel == NF_OSF_LOGLEVEL_FIRST)
	245	break;
	246	}
	247
	248	if (!fcount && (info->flags & NF_OSF_LOG))
	249	nf_log_packet(net, family, hooknum, skb, in, out, NULL,
	250	"Remote OS is not known: %pI4:%u -> %pI4:%u\n",
	251	&ip->saddr, ntohs(tcp->source),
	252	&ip->daddr, ntohs(tcp->dest));
	253
	254	if (fcount)
	255	fmatch = FMATCH_OK;
	256
	257	return fmatch == FMATCH_OK;
	258	}
	259	EXPORT_SYMBOL_GPL(nf_osf_match);
	260
22c7652c FFM	261	bool nf_osf_find(const struct sk_buff *skb,
	262	const struct list_head *nf_osf_fingers,
	263	const int ttl_check, struct nf_osf_data *data)
51c23b47 PNA	264	{
	265	const struct iphdr *ip = ip_hdr(skb);
	266	const struct nf_osf_user_finger *f;
	267	unsigned char opts[MAX_IPOPTLEN];
	268	const struct nf_osf_finger *kf;
	269	struct nf_osf_hdr_ctx ctx;
	270	const struct tcphdr *tcp;
c165d57b	271	struct tcphdr _tcph;
559c36c5	272	bool found = false;
51c23b47 PNA	273
	274	memset(&ctx, 0, sizeof(ctx));
	275
c165d57b	276	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts, &_tcph);
51c23b47	277	if (!tcp)
22c7652c	278	return false;
51c23b47 PNA	279
	280	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
	281	f = &kf->finger;
a218dc82	282	if (!nf_osf_match_one(skb, f, ttl_check, &ctx))
51c23b47 PNA	283	continue;
51c23b47 PNA	284
22c7652c FFM	285	data->genre = f->genre;
22c7652c FFM	286	data->version = f->version;
559c36c5	287	found = true;
51c23b47 PNA	288	break;
	289	}
	290
559c36c5	291	return found;
51c23b47 PNA	292	}
	293	EXPORT_SYMBOL_GPL(nf_osf_find);
	294
f9324952 FFM	295	static const struct nla_policy nfnl_osf_policy[OSF_ATTR_MAX + 1] = {
	296	[OSF_ATTR_FINGER] = { .len = sizeof(struct nf_osf_user_finger) },
	297	};
	298
a6555365 PNA	299	static int nfnl_osf_add_callback(struct sk_buff *skb,
	300	const struct nfnl_info *info,
	301	const struct nlattr * const osf_attrs[])
f9324952 FFM	302	{
	303	struct nf_osf_user_finger *f;
	304	struct nf_osf_finger kf = NULL, sf;
	305	int err = 0;
	306
	307	if (!capable(CAP_NET_ADMIN))
	308	return -EPERM;
	309
	310	if (!osf_attrs[OSF_ATTR_FINGER])
	311	return -EINVAL;
	312
a6555365	313	if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
f9324952 FFM	314	return -EINVAL;
	315
	316	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
	317
	318	kf = kmalloc(sizeof(struct nf_osf_finger), GFP_KERNEL);
	319	if (!kf)
	320	return -ENOMEM;
	321
	322	memcpy(&kf->finger, f, sizeof(struct nf_osf_user_finger));
	323
	324	list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
	325	if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
	326	continue;
	327
	328	kfree(kf);
	329	kf = NULL;
	330
a6555365	331	if (info->nlh->nlmsg_flags & NLM_F_EXCL)
f9324952 FFM	332	err = -EEXIST;
	333	break;
	334	}
	335
	336	/*
	337	* We are protected by nfnl mutex.
	338	*/
	339	if (kf)
	340	list_add_tail_rcu(&kf->finger_entry, &nf_osf_fingers[!!f->df]);
	341
	342	return err;
	343	}
	344
a6555365 PNA	345	static int nfnl_osf_remove_callback(struct sk_buff *skb,
	346	const struct nfnl_info *info,
	347	const struct nlattr * const osf_attrs[])
f9324952 FFM	348	{
	349	struct nf_osf_user_finger *f;
	350	struct nf_osf_finger *sf;
	351	int err = -ENOENT;
	352
	353	if (!capable(CAP_NET_ADMIN))
	354	return -EPERM;
	355
	356	if (!osf_attrs[OSF_ATTR_FINGER])
	357	return -EINVAL;
	358
	359	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
	360
	361	list_for_each_entry(sf, &nf_osf_fingers[!!f->df], finger_entry) {
	362	if (memcmp(&sf->finger, f, sizeof(struct nf_osf_user_finger)))
	363	continue;
	364
	365	/*
	366	* We are protected by nfnl mutex.
	367	*/
	368	list_del_rcu(&sf->finger_entry);
	369	kfree_rcu(sf, rcu_head);
	370
	371	err = 0;
	372	break;
	373	}
	374
	375	return err;
	376	}
	377
	378	static const struct nfnl_callback nfnl_osf_callbacks[OSF_MSG_MAX] = {
	379	[OSF_MSG_ADD] = {
	380	.call = nfnl_osf_add_callback,
50f2db9e	381	.type = NFNL_CB_MUTEX,
f9324952 FFM	382	.attr_count = OSF_ATTR_MAX,
	383	.policy = nfnl_osf_policy,
	384	},
	385	[OSF_MSG_REMOVE] = {
	386	.call = nfnl_osf_remove_callback,
50f2db9e	387	.type = NFNL_CB_MUTEX,
f9324952 FFM	388	.attr_count = OSF_ATTR_MAX,
	389	.policy = nfnl_osf_policy,
	390	},
	391	};
	392
	393	static const struct nfnetlink_subsystem nfnl_osf_subsys = {
	394	.name = "osf",
	395	.subsys_id = NFNL_SUBSYS_OSF,
	396	.cb_count = OSF_MSG_MAX,
	397	.cb = nfnl_osf_callbacks,
	398	};
	399
	400	static int __init nfnl_osf_init(void)
	401	{
	402	int err = -EINVAL;
	403	int i;
	404
	405	for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i)
	406	INIT_LIST_HEAD(&nf_osf_fingers[i]);
	407
	408	err = nfnetlink_subsys_register(&nfnl_osf_subsys);
	409	if (err < 0) {
	410	pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
	411	goto err_out_exit;
	412	}
	413	return 0;
	414
	415	err_out_exit:
	416	return err;
	417	}
	418
	419	static void __exit nfnl_osf_fini(void)
	420	{
	421	struct nf_osf_finger *f;
	422	int i;
	423
	424	nfnetlink_subsys_unregister(&nfnl_osf_subsys);
	425
	426	rcu_read_lock();
	427	for (i = 0; i < ARRAY_SIZE(nf_osf_fingers); ++i) {
	428	list_for_each_entry_rcu(f, &nf_osf_fingers[i], finger_entry) {
	429	list_del_rcu(&f->finger_entry);
	430	kfree_rcu(f, rcu_head);
	431	}
	432	}
	433	rcu_read_unlock();
	434
	435	rcu_barrier();
	436	}
	437
	438	module_init(nfnl_osf_init);
	439	module_exit(nfnl_osf_fini);
	440
bfb15f2a	441	MODULE_LICENSE("GPL");