summaryrefslogtreecommitdiff
path: root/net/netfilter/xt_HMARK.c
blob: dd08cc1f86c7d84909a12d0454b46d791ed288ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
/*
 * xt_HMARK - Netfilter module to set mark by means of hashing
 *
 * (C) 2012 by Hans Schillstrom <hans.schillstrom@ericsson.com>
 * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/icmp.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_HMARK.h>

#include <net/ip.h>
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
#include <net/netfilter/nf_conntrack.h>
#endif
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
#include <net/ipv6.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#endif

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Hans Schillstrom <hans.schillstrom@ericsson.com>");
MODULE_DESCRIPTION("Xtables: packet marking using hash calculation");
MODULE_ALIAS("ipt_HMARK");
MODULE_ALIAS("ip6t_HMARK");

struct hmark_tuple {
	__be32			src;
	__be32			dst;
	union hmark_ports	uports;
	u8			proto;
};

static inline __be32 hmark_addr6_mask(const __be32 *addr32, const __be32 *mask)
{
	return (addr32[0] & mask[0]) ^
	       (addr32[1] & mask[1]) ^
	       (addr32[2] & mask[2]) ^
	       (addr32[3] & mask[3]);
}

static inline __be32
hmark_addr_mask(int l3num, const __be32 *addr32, const __be32 *mask)
{
	switch (l3num) {
	case AF_INET:
		return *addr32 & *mask;
	case AF_INET6:
		return hmark_addr6_mask(addr32, mask);
	}
	return 0;
}

static inline void hmark_swap_ports(union hmark_ports *uports,
				    const struct xt_hmark_info *info)
{
	union hmark_ports hp;
	u16 src, dst;

	hp.b32 = (uports->b32 & info->port_mask.b32) | info->port_set.b32;
	src = ntohs(hp.b16.src);
	dst = ntohs(hp.b16.dst);

	if (dst > src)
		uports->v32 = (dst << 16) | src;
	else
		uports->v32 = (src << 16) | dst;
}

static int
hmark_ct_set_htuple(const struct sk_buff *skb, struct hmark_tuple *t,
		    const struct xt_hmark_info *info)
{
#if IS_ENABLED(CONFIG_NF_CONNTRACK)
	enum ip_conntrack_info ctinfo;
	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
	struct nf_conntrack_tuple *otuple;
	struct nf_conntrack_tuple *rtuple;

	if (ct == NULL)
		return -1;

	otuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	rtuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;

	t->src = hmark_addr_mask(otuple->src.l3num, otuple->src.u3.ip6,
				 info->src_mask.ip6);
	t->dst = hmark_addr_mask(otuple->src.l3num, rtuple->src.u3.ip6,
				 info->dst_mask.ip6);

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
		return 0;

	t->proto = nf_ct_protonum(ct);
	if (t->proto != IPPROTO_ICMP) {
		t->uports.b16.src = otuple->src.u.all;
		t->uports.b16.dst = rtuple->src.u.all;
		hmark_swap_ports(&t->uports, info);
	}

	return 0;
#else
	return -1;
#endif
}

/* This hash function is endian independent, to ensure consistent hashing if
 * the cluster is composed of big and little endian systems. */
static inline u32
hmark_hash(struct hmark_tuple *t, const struct xt_hmark_info *info)
{
	u32 hash;
	u32 src = ntohl(t->src);
	u32 dst = ntohl(t->dst);

	if (dst < src)
		swap(src, dst);

	hash = jhash_3words(src, dst, t->uports.v32, info->hashrnd);
	hash = hash ^ (t->proto & info->proto_mask);

	return reciprocal_scale(hash, info->hmodulus) + info->hoffset;
}

static void
hmark_set_tuple_ports(const struct sk_buff *skb, unsigned int nhoff,
		      struct hmark_tuple *t, const struct xt_hmark_info *info)
{
	int protoff;

	protoff = proto_ports_offset(t->proto);
	if (protoff < 0)
		return;

	nhoff += protoff;
	if (skb_copy_bits(skb, nhoff, &t->uports, sizeof(t->uports)) < 0)
		return;

	hmark_swap_ports(&t->uports, info);
}

#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
static int get_inner6_hdr(const struct sk_buff *skb, int *offset)
{
	struct icmp6hdr *icmp6h, _ih6;

	icmp6h = skb_header_pointer(skb, *offset, sizeof(_ih6), &_ih6);
	if (icmp6h == NULL)
		return 0;

	if (icmp6h->icmp6_type && icmp6h->icmp6_type < 128) {
		*offset += sizeof(struct icmp6hdr);
		return 1;
	}
	return 0;
}

static int
hmark_pkt_set_htuple_ipv6(const struct sk_buff *skb, struct hmark_tuple *t,
			  const struct xt_hmark_info *info)
{
	struct ipv6hdr *ip6, _ip6;
	int flag = IP6_FH_F_AUTH;
	unsigned int nhoff = 0;
	u16 fragoff = 0;
	int nexthdr;

	ip6 = (struct ipv6hdr *) (skb->data + skb_network_offset(skb));
	nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
	if (nexthdr < 0)
		return 0;
	/* No need to check for icmp errors on fragments */
	if ((flag & IP6_FH_F_FRAG) || (nexthdr != IPPROTO_ICMPV6))
		goto noicmp;
	/* Use inner header in case of ICMP errors */
	if (get_inner6_hdr(skb, &nhoff)) {
		ip6 = skb_header_pointer(skb, nhoff, sizeof(_ip6), &_ip6);
		if (ip6 == NULL)
			return -1;
		/* If AH present, use SPI like in ESP. */
		flag = IP6_FH_F_AUTH;
		nexthdr = ipv6_find_hdr(skb, &nhoff, -1, &fragoff, &flag);
		if (nexthdr < 0)
			return -1;
	}
noicmp:
	t->src = hmark_addr6_mask(ip6->saddr.s6_addr32, info->src_mask.ip6);
	t->dst = hmark_addr6_mask(ip6->daddr.s6_addr32, info->dst_mask.ip6);

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
		return 0;

	t->proto = nexthdr;
	if (t->proto == IPPROTO_ICMPV6)
		return 0;

	if (flag & IP6_FH_F_FRAG)
		return 0;

	hmark_set_tuple_ports(skb, nhoff, t, info);
	return 0;
}

static unsigned int
hmark_tg_v6(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_hmark_info *info = par->targinfo;
	struct hmark_tuple t;

	memset(&t, 0, sizeof(struct hmark_tuple));

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
		if (hmark_ct_set_htuple(skb, &t, info) < 0)
			return XT_CONTINUE;
	} else {
		if (hmark_pkt_set_htuple_ipv6(skb, &t, info) < 0)
			return XT_CONTINUE;
	}

	skb->mark = hmark_hash(&t, info);
	return XT_CONTINUE;
}
#endif

static int get_inner_hdr(const struct sk_buff *skb, int iphsz, int *nhoff)
{
	const struct icmphdr *icmph;
	struct icmphdr _ih;

	/* Not enough header? */
	icmph = skb_header_pointer(skb, *nhoff + iphsz, sizeof(_ih), &_ih);
	if (icmph == NULL || icmph->type > NR_ICMP_TYPES)
		return 0;

	/* Error message? */
	if (icmph->type != ICMP_DEST_UNREACH &&
	    icmph->type != ICMP_SOURCE_QUENCH &&
	    icmph->type != ICMP_TIME_EXCEEDED &&
	    icmph->type != ICMP_PARAMETERPROB &&
	    icmph->type != ICMP_REDIRECT)
		return 0;

	*nhoff += iphsz + sizeof(_ih);
	return 1;
}

static int
hmark_pkt_set_htuple_ipv4(const struct sk_buff *skb, struct hmark_tuple *t,
			  const struct xt_hmark_info *info)
{
	struct iphdr *ip, _ip;
	int nhoff = skb_network_offset(skb);

	ip = (struct iphdr *) (skb->data + nhoff);
	if (ip->protocol == IPPROTO_ICMP) {
		/* Use inner header in case of ICMP errors */
		if (get_inner_hdr(skb, ip->ihl * 4, &nhoff)) {
			ip = skb_header_pointer(skb, nhoff, sizeof(_ip), &_ip);
			if (ip == NULL)
				return -1;
		}
	}

	t->src = ip->saddr & info->src_mask.ip;
	t->dst = ip->daddr & info->dst_mask.ip;

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))
		return 0;

	t->proto = ip->protocol;

	/* ICMP has no ports, skip */
	if (t->proto == IPPROTO_ICMP)
		return 0;

	/* follow-up fragments don't contain ports, skip all fragments */
	if (ip->frag_off & htons(IP_MF | IP_OFFSET))
		return 0;

	hmark_set_tuple_ports(skb, (ip->ihl * 4) + nhoff, t, info);

	return 0;
}

static unsigned int
hmark_tg_v4(struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_hmark_info *info = par->targinfo;
	struct hmark_tuple t;

	memset(&t, 0, sizeof(struct hmark_tuple));

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_CT)) {
		if (hmark_ct_set_htuple(skb, &t, info) < 0)
			return XT_CONTINUE;
	} else {
		if (hmark_pkt_set_htuple_ipv4(skb, &t, info) < 0)
			return XT_CONTINUE;
	}

	skb->mark = hmark_hash(&t, info);
	return XT_CONTINUE;
}

static int hmark_tg_check(const struct xt_tgchk_param *par)
{
	const struct xt_hmark_info *info = par->targinfo;

	if (!info->hmodulus)
		return -EINVAL;

	if (info->proto_mask &&
	    (info->flags & XT_HMARK_FLAG(XT_HMARK_METHOD_L3))) {
		pr_info("xt_HMARK: proto mask must be zero with L3 mode\n");
		return -EINVAL;
	}
	if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI_MASK) &&
	    (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT_MASK) |
			     XT_HMARK_FLAG(XT_HMARK_DPORT_MASK))))
		return -EINVAL;

	if (info->flags & XT_HMARK_FLAG(XT_HMARK_SPI) &&
	    (info->flags & (XT_HMARK_FLAG(XT_HMARK_SPORT) |
			     XT_HMARK_FLAG(XT_HMARK_DPORT)))) {
		pr_info("xt_HMARK: spi-set and port-set can't be combined\n");
		return -EINVAL;
	}
	return 0;
}

static struct xt_target hmark_tg_reg[] __read_mostly = {
	{
		.name		= "HMARK",
		.family		= NFPROTO_IPV4,
		.target		= hmark_tg_v4,
		.targetsize	= sizeof(struct xt_hmark_info),
		.checkentry	= hmark_tg_check,
		.me		= THIS_MODULE,
	},
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	{
		.name		= "HMARK",
		.family		= NFPROTO_IPV6,
		.target		= hmark_tg_v6,
		.targetsize	= sizeof(struct xt_hmark_info),
		.checkentry	= hmark_tg_check,
		.me		= THIS_MODULE,
	},
#endif
};

static int __init hmark_tg_init(void)
{
	return xt_register_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
}

static void __exit hmark_tg_exit(void)
{
	xt_unregister_targets(hmark_tg_reg, ARRAY_SIZE(hmark_tg_reg));
}

module_init(hmark_tg_init);
module_exit(hmark_tg_exit);