summaryrefslogtreecommitdiffstats
path: root/net/sched/act_nat.c
blob: d541f553805face5a0d444659c17e0b720aeb843 (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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Stateless NAT actions
 *
 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/tc_act/tc_nat.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>
#include <net/icmp.h>
#include <net/ip.h>
#include <net/netlink.h>
#include <net/tc_act/tc_nat.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/tc_wrapper.h>

static struct tc_action_ops act_nat_ops;

static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
	[TCA_NAT_PARMS]	= { .len = sizeof(struct tc_nat) },
};

static int tcf_nat_init(struct net *net, struct nlattr *nla, struct nlattr *est,
			struct tc_action **a, struct tcf_proto *tp,
			u32 flags, struct netlink_ext_ack *extack)
{
	struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);
	bool bind = flags & TCA_ACT_FLAGS_BIND;
	struct tcf_nat_parms *nparm, *oparm;
	struct nlattr *tb[TCA_NAT_MAX + 1];
	struct tcf_chain *goto_ch = NULL;
	struct tc_nat *parm;
	int ret = 0, err;
	struct tcf_nat *p;
	u32 index;

	if (nla == NULL)
		return -EINVAL;

	err = nla_parse_nested_deprecated(tb, TCA_NAT_MAX, nla, nat_policy,
					  NULL);
	if (err < 0)
		return err;

	if (tb[TCA_NAT_PARMS] == NULL)
		return -EINVAL;
	parm = nla_data(tb[TCA_NAT_PARMS]);
	index = parm->index;
	err = tcf_idr_check_alloc(tn, &index, a, bind);
	if (!err) {
		ret = tcf_idr_create_from_flags(tn, index, est, a, &act_nat_ops,
						bind, flags);
		if (ret) {
			tcf_idr_cleanup(tn, index);
			return ret;
		}
		ret = ACT_P_CREATED;
	} else if (err > 0) {
		if (bind)
			return ACT_P_BOUND;
		if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
			tcf_idr_release(*a, bind);
			return -EEXIST;
		}
	} else {
		return err;
	}
	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
	if (err < 0)
		goto release_idr;

	nparm = kzalloc(sizeof(*nparm), GFP_KERNEL);
	if (!nparm) {
		err = -ENOMEM;
		goto release_idr;
	}

	nparm->old_addr = parm->old_addr;
	nparm->new_addr = parm->new_addr;
	nparm->mask = parm->mask;
	nparm->flags = parm->flags;

	p = to_tcf_nat(*a);

	spin_lock_bh(&p->tcf_lock);
	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
	oparm = rcu_replace_pointer(p->parms, nparm, lockdep_is_held(&p->tcf_lock));
	spin_unlock_bh(&p->tcf_lock);

	if (goto_ch)
		tcf_chain_put_by_act(goto_ch);

	if (oparm)
		kfree_rcu(oparm, rcu);

	return ret;
release_idr:
	tcf_idr_release(*a, bind);
	return err;
}

TC_INDIRECT_SCOPE int tcf_nat_act(struct sk_buff *skb,
				  const struct tc_action *a,
				  struct tcf_result *res)
{
	struct tcf_nat *p = to_tcf_nat(a);
	struct tcf_nat_parms *parms;
	struct iphdr *iph;
	__be32 old_addr;
	__be32 new_addr;
	__be32 mask;
	__be32 addr;
	int egress;
	int action;
	int ihl;
	int noff;

	tcf_lastuse_update(&p->tcf_tm);
	tcf_action_update_bstats(&p->common, skb);

	action = READ_ONCE(p->tcf_action);

	parms = rcu_dereference_bh(p->parms);
	old_addr = parms->old_addr;
	new_addr = parms->new_addr;
	mask = parms->mask;
	egress = parms->flags & TCA_NAT_FLAG_EGRESS;

	if (unlikely(action == TC_ACT_SHOT))
		goto drop;

	noff = skb_network_offset(skb);
	if (!pskb_may_pull(skb, sizeof(*iph) + noff))
		goto drop;

	iph = ip_hdr(skb);

	if (egress)
		addr = iph->saddr;
	else
		addr = iph->daddr;

	if (!((old_addr ^ addr) & mask)) {
		if (skb_try_make_writable(skb, sizeof(*iph) + noff))
			goto drop;

		new_addr &= mask;
		new_addr |= addr & ~mask;

		/* Rewrite IP header */
		iph = ip_hdr(skb);
		if (egress)
			iph->saddr = new_addr;
		else
			iph->daddr = new_addr;

		csum_replace4(&iph->check, addr, new_addr);
	} else if ((iph->frag_off & htons(IP_OFFSET)) ||
		   iph->protocol != IPPROTO_ICMP) {
		goto out;
	}

	ihl = iph->ihl * 4;

	/* It would be nice to share code with stateful NAT. */
	switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
	case IPPROTO_TCP:
	{
		struct tcphdr *tcph;

		if (!pskb_may_pull(skb, ihl + sizeof(*tcph) + noff) ||
		    skb_try_make_writable(skb, ihl + sizeof(*tcph) + noff))
			goto drop;

		tcph = (void *)(skb_network_header(skb) + ihl);
		inet_proto_csum_replace4(&tcph->check, skb, addr, new_addr,
					 true);
		break;
	}
	case IPPROTO_UDP:
	{
		struct udphdr *udph;

		if (!pskb_may_pull(skb, ihl + sizeof(*udph) + noff) ||
		    skb_try_make_writable(skb, ihl + sizeof(*udph) + noff))
			goto drop;

		udph = (void *)(skb_network_header(skb) + ihl);
		if (udph->check || skb->ip_summed == CHECKSUM_PARTIAL) {
			inet_proto_csum_replace4(&udph->check, skb, addr,
						 new_addr, true);
			if (!udph->check)
				udph->check = CSUM_MANGLED_0;
		}
		break;
	}
	case IPPROTO_ICMP:
	{
		struct icmphdr *icmph;

		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + noff))
			goto drop;

		icmph = (void *)(skb_network_header(skb) + ihl);

		if (!icmp_is_err(icmph->type))
			break;

		if (!pskb_may_pull(skb, ihl + sizeof(*icmph) + sizeof(*iph) +
					noff))
			goto drop;

		icmph = (void *)(skb_network_header(skb) + ihl);
		iph = (void *)(icmph + 1);
		if (egress)
			addr = iph->daddr;
		else
			addr = iph->saddr;

		if ((old_addr ^ addr) & mask)
			break;

		if (skb_try_make_writable(skb, ihl + sizeof(*icmph) +
					  sizeof(*iph) + noff))
			goto drop;

		icmph = (void *)(skb_network_header(skb) + ihl);
		iph = (void *)(icmph + 1);

		new_addr &= mask;
		new_addr |= addr & ~mask;

		/* XXX Fix up the inner checksums. */
		if (egress)
			iph->daddr = new_addr;
		else
			iph->saddr = new_addr;

		inet_proto_csum_replace4(&icmph->checksum, skb, addr, new_addr,
					 false);
		break;
	}
	default:
		break;
	}

out:
	return action;

drop:
	tcf_action_inc_drop_qstats(&p->common);
	return TC_ACT_SHOT;
}

static int tcf_nat_dump(struct sk_buff *skb, struct tc_action *a,
			int bind, int ref)
{
	unsigned char *b = skb_tail_pointer(skb);
	struct tcf_nat *p = to_tcf_nat(a);
	struct tc_nat opt = {
		.index    = p->tcf_index,
		.refcnt   = refcount_read(&p->tcf_refcnt) - ref,
		.bindcnt  = atomic_read(&p->tcf_bindcnt) - bind,
	};
	struct tcf_nat_parms *parms;
	struct tcf_t t;

	spin_lock_bh(&p->tcf_lock);

	opt.action = p->tcf_action;

	parms = rcu_dereference_protected(p->parms, lockdep_is_held(&p->tcf_lock));

	opt.old_addr = parms->old_addr;
	opt.new_addr = parms->new_addr;
	opt.mask = parms->mask;
	opt.flags = parms->flags;

	if (nla_put(skb, TCA_NAT_PARMS, sizeof(opt), &opt))
		goto nla_put_failure;

	tcf_tm_dump(&t, &p->tcf_tm);
	if (nla_put_64bit(skb, TCA_NAT_TM, sizeof(t), &t, TCA_NAT_PAD))
		goto nla_put_failure;
	spin_unlock_bh(&p->tcf_lock);

	return skb->len;

nla_put_failure:
	spin_unlock_bh(&p->tcf_lock);
	nlmsg_trim(skb, b);
	return -1;
}

static void tcf_nat_cleanup(struct tc_action *a)
{
	struct tcf_nat *p = to_tcf_nat(a);
	struct tcf_nat_parms *parms;

	parms = rcu_dereference_protected(p->parms, 1);
	if (parms)
		kfree_rcu(parms, rcu);
}

static struct tc_action_ops act_nat_ops = {
	.kind		=	"nat",
	.id		=	TCA_ID_NAT,
	.owner		=	THIS_MODULE,
	.act		=	tcf_nat_act,
	.dump		=	tcf_nat_dump,
	.init		=	tcf_nat_init,
	.cleanup	=	tcf_nat_cleanup,
	.size		=	sizeof(struct tcf_nat),
};
MODULE_ALIAS_NET_ACT("nat");

static __net_init int nat_init_net(struct net *net)
{
	struct tc_action_net *tn = net_generic(net, act_nat_ops.net_id);

	return tc_action_net_init(net, tn, &act_nat_ops);
}

static void __net_exit nat_exit_net(struct list_head *net_list)
{
	tc_action_net_exit(net_list, act_nat_ops.net_id);
}

static struct pernet_operations nat_net_ops = {
	.init = nat_init_net,
	.exit_batch = nat_exit_net,
	.id   = &act_nat_ops.net_id,
	.size = sizeof(struct tc_action_net),
};

MODULE_DESCRIPTION("Stateless NAT actions");
MODULE_LICENSE("GPL");

static int __init nat_init_module(void)
{
	return tcf_register_action(&act_nat_ops, &nat_net_ops);
}

static void __exit nat_cleanup_module(void)
{
	tcf_unregister_action(&act_nat_ops, &nat_net_ops);
}

module_init(nat_init_module);
module_exit(nat_cleanup_module);