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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2010 Patrick McHardy <[email protected]>
4 */
5#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
6#include <linux/module.h>
7#include <linux/gfp.h>
8#include <linux/skbuff.h>
9#include <linux/netfilter_ipv4/ip_tables.h>
10#include <linux/netfilter_ipv6/ip6_tables.h>
11#include <linux/netfilter/x_tables.h>
12#include <linux/netfilter/xt_CT.h>
13#include <net/netfilter/nf_conntrack.h>
14#include <net/netfilter/nf_conntrack_l4proto.h>
15#include <net/netfilter/nf_conntrack_helper.h>
16#include <net/netfilter/nf_conntrack_ecache.h>
17#include <net/netfilter/nf_conntrack_timeout.h>
18#include <net/netfilter/nf_conntrack_zones.h>
19#include "nf_internals.h"
20
21static inline int xt_ct_target(struct sk_buff *skb, struct nf_conn *ct)
22{
23 /* Previously seen (loopback)? Ignore. */
24 if (skb->_nfct != 0)
25 return XT_CONTINUE;
26
27 if (ct) {
28 refcount_inc(&ct->ct_general.use);
29 nf_ct_set(skb, ct, IP_CT_NEW);
30 } else {
31 nf_ct_set(skb, ct, IP_CT_UNTRACKED);
32 }
33
34 return XT_CONTINUE;
35}
36
37static unsigned int xt_ct_target_v0(struct sk_buff *skb,
38 const struct xt_action_param *par)
39{
40 const struct xt_ct_target_info *info = par->targinfo;
41 struct nf_conn *ct = info->ct;
42
43 return xt_ct_target(skb, ct);
44}
45
46static unsigned int xt_ct_target_v1(struct sk_buff *skb,
47 const struct xt_action_param *par)
48{
49 const struct xt_ct_target_info_v1 *info = par->targinfo;
50 struct nf_conn *ct = info->ct;
51
52 return xt_ct_target(skb, ct);
53}
54
55static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
56{
57 if (par->family == NFPROTO_IPV4) {
58 const struct ipt_entry *e = par->entryinfo;
59
60 if (e->ip.invflags & IPT_INV_PROTO)
61 return 0;
62 return e->ip.proto;
63 } else if (par->family == NFPROTO_IPV6) {
64 const struct ip6t_entry *e = par->entryinfo;
65
66 if (e->ipv6.invflags & IP6T_INV_PROTO)
67 return 0;
68 return e->ipv6.proto;
69 } else
70 return 0;
71}
72
73static int
74xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
75 const struct xt_tgchk_param *par)
76{
77 struct nf_conntrack_helper *helper;
78 struct nf_conn_help *help;
79 u8 proto;
80
81 proto = xt_ct_find_proto(par);
82 if (!proto) {
83 pr_info_ratelimited("You must specify a L4 protocol and not use inversions on it\n");
84 return -ENOENT;
85 }
86
87 helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
88 proto);
89 if (helper == NULL) {
90 pr_info_ratelimited("No such helper \"%s\"\n", helper_name);
91 return -ENOENT;
92 }
93
94 help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
95 if (help == NULL) {
96 nf_conntrack_helper_put(helper);
97 return -ENOMEM;
98 }
99
100 rcu_assign_pointer(help->helper, helper);
101 return 0;
102}
103
104static int
105xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
106 const char *timeout_name)
107{
108#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
109 const struct nf_conntrack_l4proto *l4proto;
110 u8 proto;
111
112 proto = xt_ct_find_proto(par);
113 if (!proto) {
114 pr_info_ratelimited("You must specify a L4 protocol and not "
115 "use inversions on it");
116 return -EINVAL;
117 }
118 l4proto = nf_ct_l4proto_find(proto);
119 return nf_ct_set_timeout(par->net, ct, par->family, l4proto->l4proto,
120 timeout_name);
121
122#else
123 return -EOPNOTSUPP;
124#endif
125}
126
127static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
128{
129 switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
130 XT_CT_ZONE_DIR_REPL)) {
131 case XT_CT_ZONE_DIR_ORIG:
132 return NF_CT_ZONE_DIR_ORIG;
133 case XT_CT_ZONE_DIR_REPL:
134 return NF_CT_ZONE_DIR_REPL;
135 default:
136 return NF_CT_DEFAULT_ZONE_DIR;
137 }
138}
139
140static void xt_ct_put_helper(struct nf_conn_help *help)
141{
142 struct nf_conntrack_helper *helper;
143
144 if (!help)
145 return;
146
147 /* not yet exposed to other cpus, or ruleset
148 * already detached (post-replacement).
149 */
150 helper = rcu_dereference_raw(help->helper);
151 if (helper)
152 nf_conntrack_helper_put(helper);
153}
154
155static int xt_ct_tg_check(const struct xt_tgchk_param *par,
156 struct xt_ct_target_info_v1 *info)
157{
158 struct nf_conntrack_zone zone;
159 struct nf_conn_help *help;
160 struct nf_conn *ct;
161 int ret = -EOPNOTSUPP;
162
163 if (info->flags & XT_CT_NOTRACK) {
164 ct = NULL;
165 goto out;
166 }
167
168#ifndef CONFIG_NF_CONNTRACK_ZONES
169 if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
170 XT_CT_ZONE_DIR_REPL |
171 XT_CT_ZONE_MARK))
172 goto err1;
173#endif
174
175 ret = nf_ct_netns_get(par->net, par->family);
176 if (ret < 0)
177 goto err1;
178
179 memset(&zone, 0, sizeof(zone));
180 zone.id = info->zone;
181 zone.dir = xt_ct_flags_to_dir(info);
182 if (info->flags & XT_CT_ZONE_MARK)
183 zone.flags |= NF_CT_FLAG_MARK;
184
185 ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
186 if (!ct) {
187 ret = -ENOMEM;
188 goto err2;
189 }
190
191 if ((info->ct_events || info->exp_events) &&
192 !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
193 GFP_KERNEL)) {
194 ret = -EINVAL;
195 goto err3;
196 }
197
198 if (info->helper[0]) {
199 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
200 ret = -ENAMETOOLONG;
201 goto err3;
202 }
203
204 ret = xt_ct_set_helper(ct, info->helper, par);
205 if (ret < 0)
206 goto err3;
207 }
208
209 if (info->timeout[0]) {
210 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
211 ret = -ENAMETOOLONG;
212 goto err4;
213 }
214
215 ret = xt_ct_set_timeout(ct, par, info->timeout);
216 if (ret < 0)
217 goto err4;
218 }
219 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
220out:
221 info->ct = ct;
222 return 0;
223
224err4:
225 help = nfct_help(ct);
226 xt_ct_put_helper(help);
227err3:
228 nf_ct_tmpl_free(ct);
229err2:
230 nf_ct_netns_put(par->net, par->family);
231err1:
232 return ret;
233}
234
235static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
236{
237 struct xt_ct_target_info *info = par->targinfo;
238 struct xt_ct_target_info_v1 info_v1 = {
239 .flags = info->flags,
240 .zone = info->zone,
241 .ct_events = info->ct_events,
242 .exp_events = info->exp_events,
243 };
244 int ret;
245
246 if (info->flags & ~XT_CT_NOTRACK)
247 return -EINVAL;
248
249 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
250
251 ret = xt_ct_tg_check(par, &info_v1);
252 if (ret < 0)
253 return ret;
254
255 info->ct = info_v1.ct;
256
257 return ret;
258}
259
260static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
261{
262 struct xt_ct_target_info_v1 *info = par->targinfo;
263
264 if (info->flags & ~XT_CT_NOTRACK)
265 return -EINVAL;
266
267 return xt_ct_tg_check(par, par->targinfo);
268}
269
270static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
271{
272 struct xt_ct_target_info_v1 *info = par->targinfo;
273
274 if (info->flags & ~XT_CT_MASK)
275 return -EINVAL;
276
277 return xt_ct_tg_check(par, par->targinfo);
278}
279
280static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
281 struct xt_ct_target_info_v1 *info)
282{
283 struct nf_conn *ct = info->ct;
284 struct nf_conn_help *help;
285
286 if (ct) {
287 help = nfct_help(ct);
288 xt_ct_put_helper(help);
289
290 nf_ct_netns_put(par->net, par->family);
291
292 nf_ct_destroy_timeout(ct);
293 nf_ct_put(info->ct);
294 }
295}
296
297static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
298{
299 struct xt_ct_target_info *info = par->targinfo;
300 struct xt_ct_target_info_v1 info_v1 = {
301 .flags = info->flags,
302 .zone = info->zone,
303 .ct_events = info->ct_events,
304 .exp_events = info->exp_events,
305 .ct = info->ct,
306 };
307 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
308
309 xt_ct_tg_destroy(par, &info_v1);
310}
311
312static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
313{
314 xt_ct_tg_destroy(par, par->targinfo);
315}
316
317static unsigned int
318notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
319{
320 /* Previously seen (loopback)? Ignore. */
321 if (skb->_nfct != 0)
322 return XT_CONTINUE;
323
324 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
325
326 return XT_CONTINUE;
327}
328
329static struct xt_target xt_ct_tg_reg[] __read_mostly = {
330 {
331 .name = "NOTRACK",
332 .revision = 0,
333 .family = NFPROTO_IPV4,
334 .target = notrack_tg,
335 .table = "raw",
336 .me = THIS_MODULE,
337 },
338 {
339 .name = "CT",
340 .family = NFPROTO_IPV4,
341 .targetsize = sizeof(struct xt_ct_target_info),
342 .usersize = offsetof(struct xt_ct_target_info, ct),
343 .checkentry = xt_ct_tg_check_v0,
344 .destroy = xt_ct_tg_destroy_v0,
345 .target = xt_ct_target_v0,
346 .table = "raw",
347 .me = THIS_MODULE,
348 },
349 {
350 .name = "CT",
351 .family = NFPROTO_IPV4,
352 .revision = 1,
353 .targetsize = sizeof(struct xt_ct_target_info_v1),
354 .usersize = offsetof(struct xt_ct_target_info_v1, ct),
355 .checkentry = xt_ct_tg_check_v1,
356 .destroy = xt_ct_tg_destroy_v1,
357 .target = xt_ct_target_v1,
358 .table = "raw",
359 .me = THIS_MODULE,
360 },
361 {
362 .name = "CT",
363 .family = NFPROTO_IPV4,
364 .revision = 2,
365 .targetsize = sizeof(struct xt_ct_target_info_v1),
366 .usersize = offsetof(struct xt_ct_target_info_v1, ct),
367 .checkentry = xt_ct_tg_check_v2,
368 .destroy = xt_ct_tg_destroy_v1,
369 .target = xt_ct_target_v1,
370 .table = "raw",
371 .me = THIS_MODULE,
372 },
373#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
374 {
375 .name = "NOTRACK",
376 .revision = 0,
377 .family = NFPROTO_IPV6,
378 .target = notrack_tg,
379 .table = "raw",
380 .me = THIS_MODULE,
381 },
382 {
383 .name = "CT",
384 .family = NFPROTO_IPV6,
385 .targetsize = sizeof(struct xt_ct_target_info),
386 .usersize = offsetof(struct xt_ct_target_info, ct),
387 .checkentry = xt_ct_tg_check_v0,
388 .destroy = xt_ct_tg_destroy_v0,
389 .target = xt_ct_target_v0,
390 .table = "raw",
391 .me = THIS_MODULE,
392 },
393 {
394 .name = "CT",
395 .family = NFPROTO_IPV6,
396 .revision = 1,
397 .targetsize = sizeof(struct xt_ct_target_info_v1),
398 .usersize = offsetof(struct xt_ct_target_info_v1, ct),
399 .checkentry = xt_ct_tg_check_v1,
400 .destroy = xt_ct_tg_destroy_v1,
401 .target = xt_ct_target_v1,
402 .table = "raw",
403 .me = THIS_MODULE,
404 },
405 {
406 .name = "CT",
407 .family = NFPROTO_IPV6,
408 .revision = 2,
409 .targetsize = sizeof(struct xt_ct_target_info_v1),
410 .usersize = offsetof(struct xt_ct_target_info_v1, ct),
411 .checkentry = xt_ct_tg_check_v2,
412 .destroy = xt_ct_tg_destroy_v1,
413 .target = xt_ct_target_v1,
414 .table = "raw",
415 .me = THIS_MODULE,
416 },
417#endif
418};
419
420static int __init xt_ct_tg_init(void)
421{
422 return xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
423}
424
425static void __exit xt_ct_tg_exit(void)
426{
427 xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
428}
429
430module_init(xt_ct_tg_init);
431module_exit(xt_ct_tg_exit);
432
433MODULE_LICENSE("GPL");
434MODULE_DESCRIPTION("Xtables: connection tracking target");
435MODULE_ALIAS("ipt_CT");
436MODULE_ALIAS("ip6t_CT");
437MODULE_ALIAS("ipt_NOTRACK");
438MODULE_ALIAS("ip6t_NOTRACK");