1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
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
20static inline int xt_ct_target(struct sk_buff *skb, struct nf_conn *ct)
21{
22 /* Previously seen (loopback)? Ignore. */
23 if (skb->_nfct != 0)
24 return XT_CONTINUE;
25
26 if (ct) {
27 refcount_inc(r: &ct->ct_general.use);
28 nf_ct_set(skb, ct, info: IP_CT_NEW);
29 } else {
30 nf_ct_set(skb, ct, info: IP_CT_UNTRACKED);
31 }
32
33 return XT_CONTINUE;
34}
35
36static unsigned int xt_ct_target_v0(struct sk_buff *skb,
37 const struct xt_action_param *par)
38{
39 const struct xt_ct_target_info *info = par->targinfo;
40 struct nf_conn *ct = info->ct;
41
42 return xt_ct_target(skb, ct);
43}
44
45static unsigned int xt_ct_target_v1(struct sk_buff *skb,
46 const struct xt_action_param *par)
47{
48 const struct xt_ct_target_info_v1 *info = par->targinfo;
49 struct nf_conn *ct = info->ct;
50
51 return xt_ct_target(skb, ct);
52}
53
54static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
55{
56 if (par->family == NFPROTO_IPV4) {
57 const struct ipt_entry *e = par->entryinfo;
58
59 if (e->ip.invflags & IPT_INV_PROTO)
60 return 0;
61 return e->ip.proto;
62 } else if (par->family == NFPROTO_IPV6) {
63 const struct ip6t_entry *e = par->entryinfo;
64
65 if (e->ipv6.invflags & IP6T_INV_PROTO)
66 return 0;
67 return e->ipv6.proto;
68 } else
69 return 0;
70}
71
72static int
73xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
74 const struct xt_tgchk_param *par)
75{
76 struct nf_conntrack_helper *helper;
77 struct nf_conn_help *help;
78 u8 proto;
79
80 proto = xt_ct_find_proto(par);
81 if (!proto) {
82 pr_info_ratelimited("You must specify a L4 protocol and not use inversions on it\n");
83 return -ENOENT;
84 }
85
86 helper = nf_conntrack_helper_try_module_get(name: helper_name, l3num: par->family,
87 protonum: proto);
88 if (helper == NULL) {
89 pr_info_ratelimited("No such helper \"%s\"\n", helper_name);
90 return -ENOENT;
91 }
92
93 help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
94 if (help == NULL) {
95 nf_conntrack_helper_put(helper);
96 return -ENOMEM;
97 }
98
99 rcu_assign_pointer(help->helper, helper);
100 return 0;
101}
102
103static int
104xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
105 const char *timeout_name)
106{
107#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
108 const struct nf_conntrack_l4proto *l4proto;
109 u8 proto;
110
111 proto = xt_ct_find_proto(par);
112 if (!proto) {
113 pr_info_ratelimited("You must specify a L4 protocol and not "
114 "use inversions on it");
115 return -EINVAL;
116 }
117 l4proto = nf_ct_l4proto_find(l4proto: proto);
118 return nf_ct_set_timeout(net: par->net, ct, l3num: par->family, l4num: l4proto->l4proto,
119 timeout_name);
120
121#else
122 return -EOPNOTSUPP;
123#endif
124}
125
126static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
127{
128 switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
129 XT_CT_ZONE_DIR_REPL)) {
130 case XT_CT_ZONE_DIR_ORIG:
131 return NF_CT_ZONE_DIR_ORIG;
132 case XT_CT_ZONE_DIR_REPL:
133 return NF_CT_ZONE_DIR_REPL;
134 default:
135 return NF_CT_DEFAULT_ZONE_DIR;
136 }
137}
138
139static void xt_ct_put_helper(struct nf_conn_help *help)
140{
141 struct nf_conntrack_helper *helper;
142
143 if (!help)
144 return;
145
146 /* not yet exposed to other cpus, or ruleset
147 * already detached (post-replacement).
148 */
149 helper = rcu_dereference_raw(help->helper);
150 if (helper)
151 nf_conntrack_helper_put(helper);
152}
153
154static int xt_ct_tg_check(const struct xt_tgchk_param *par,
155 struct xt_ct_target_info_v1 *info)
156{
157 struct nf_conntrack_zone zone;
158 struct nf_conn_help *help;
159 struct nf_conn *ct;
160 int ret = -EOPNOTSUPP;
161
162 if (info->flags & XT_CT_NOTRACK) {
163 ct = NULL;
164 goto out;
165 }
166
167#ifndef CONFIG_NF_CONNTRACK_ZONES
168 if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
169 XT_CT_ZONE_DIR_REPL |
170 XT_CT_ZONE_MARK))
171 goto err1;
172#endif
173
174 ret = nf_ct_netns_get(net: par->net, nfproto: par->family);
175 if (ret < 0)
176 goto err1;
177
178 memset(&zone, 0, sizeof(zone));
179 zone.id = info->zone;
180 zone.dir = xt_ct_flags_to_dir(info);
181 if (info->flags & XT_CT_ZONE_MARK)
182 zone.flags |= NF_CT_FLAG_MARK;
183
184 ct = nf_ct_tmpl_alloc(net: par->net, zone: &zone, GFP_KERNEL);
185 if (!ct) {
186 ret = -ENOMEM;
187 goto err2;
188 }
189
190 if ((info->ct_events || info->exp_events) &&
191 !nf_ct_ecache_ext_add(ct, ctmask: info->ct_events, expmask: info->exp_events,
192 GFP_KERNEL)) {
193 ret = -EINVAL;
194 goto err3;
195 }
196
197 if (info->helper[0]) {
198 if (strnlen(p: info->helper, maxlen: sizeof(info->helper)) == sizeof(info->helper)) {
199 ret = -ENAMETOOLONG;
200 goto err3;
201 }
202
203 ret = xt_ct_set_helper(ct, helper_name: info->helper, par);
204 if (ret < 0)
205 goto err3;
206 }
207
208 if (info->timeout[0]) {
209 if (strnlen(p: info->timeout, maxlen: sizeof(info->timeout)) == sizeof(info->timeout)) {
210 ret = -ENAMETOOLONG;
211 goto err4;
212 }
213
214 ret = xt_ct_set_timeout(ct, par, timeout_name: info->timeout);
215 if (ret < 0)
216 goto err4;
217 }
218 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
219out:
220 info->ct = ct;
221 return 0;
222
223err4:
224 help = nfct_help(ct);
225 xt_ct_put_helper(help);
226err3:
227 nf_ct_tmpl_free(tmpl: ct);
228err2:
229 nf_ct_netns_put(net: par->net, nfproto: par->family);
230err1:
231 return ret;
232}
233
234static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
235{
236 struct xt_ct_target_info *info = par->targinfo;
237 struct xt_ct_target_info_v1 info_v1 = {
238 .flags = info->flags,
239 .zone = info->zone,
240 .ct_events = info->ct_events,
241 .exp_events = info->exp_events,
242 };
243 int ret;
244
245 if (info->flags & ~XT_CT_NOTRACK)
246 return -EINVAL;
247
248 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
249
250 ret = xt_ct_tg_check(par, info: &info_v1);
251 if (ret < 0)
252 return ret;
253
254 info->ct = info_v1.ct;
255
256 return ret;
257}
258
259static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
260{
261 struct xt_ct_target_info_v1 *info = par->targinfo;
262
263 if (info->flags & ~XT_CT_NOTRACK)
264 return -EINVAL;
265
266 return xt_ct_tg_check(par, info: par->targinfo);
267}
268
269static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
270{
271 struct xt_ct_target_info_v1 *info = par->targinfo;
272
273 if (info->flags & ~XT_CT_MASK)
274 return -EINVAL;
275
276 return xt_ct_tg_check(par, info: par->targinfo);
277}
278
279static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
280 struct xt_ct_target_info_v1 *info)
281{
282 struct nf_conn *ct = info->ct;
283 struct nf_conn_help *help;
284
285 if (ct) {
286 help = nfct_help(ct);
287 xt_ct_put_helper(help);
288
289 nf_ct_netns_put(net: par->net, nfproto: par->family);
290
291 nf_ct_destroy_timeout(ct);
292 nf_ct_put(ct: info->ct);
293 }
294}
295
296static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
297{
298 struct xt_ct_target_info *info = par->targinfo;
299 struct xt_ct_target_info_v1 info_v1 = {
300 .flags = info->flags,
301 .zone = info->zone,
302 .ct_events = info->ct_events,
303 .exp_events = info->exp_events,
304 .ct = info->ct,
305 };
306 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
307
308 xt_ct_tg_destroy(par, info: &info_v1);
309}
310
311static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
312{
313 xt_ct_tg_destroy(par, info: par->targinfo);
314}
315
316static unsigned int
317notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
318{
319 /* Previously seen (loopback)? Ignore. */
320 if (skb->_nfct != 0)
321 return XT_CONTINUE;
322
323 nf_ct_set(skb, NULL, info: IP_CT_UNTRACKED);
324
325 return XT_CONTINUE;
326}
327
328static struct xt_target xt_ct_tg_reg[] __read_mostly = {
329 {
330 .name = "NOTRACK",
331 .revision = 0,
332 .family = NFPROTO_IPV4,
333 .target = notrack_tg,
334 .table = "raw",
335 .me = THIS_MODULE,
336 },
337 {
338 .name = "CT",
339 .family = NFPROTO_IPV4,
340 .targetsize = sizeof(struct xt_ct_target_info),
341 .usersize = offsetof(struct xt_ct_target_info, ct),
342 .checkentry = xt_ct_tg_check_v0,
343 .destroy = xt_ct_tg_destroy_v0,
344 .target = xt_ct_target_v0,
345 .table = "raw",
346 .me = THIS_MODULE,
347 },
348 {
349 .name = "CT",
350 .family = NFPROTO_IPV4,
351 .revision = 1,
352 .targetsize = sizeof(struct xt_ct_target_info_v1),
353 .usersize = offsetof(struct xt_ct_target_info, ct),
354 .checkentry = xt_ct_tg_check_v1,
355 .destroy = xt_ct_tg_destroy_v1,
356 .target = xt_ct_target_v1,
357 .table = "raw",
358 .me = THIS_MODULE,
359 },
360 {
361 .name = "CT",
362 .family = NFPROTO_IPV4,
363 .revision = 2,
364 .targetsize = sizeof(struct xt_ct_target_info_v1),
365 .usersize = offsetof(struct xt_ct_target_info, ct),
366 .checkentry = xt_ct_tg_check_v2,
367 .destroy = xt_ct_tg_destroy_v1,
368 .target = xt_ct_target_v1,
369 .table = "raw",
370 .me = THIS_MODULE,
371 },
372#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
373 {
374 .name = "NOTRACK",
375 .revision = 0,
376 .family = NFPROTO_IPV6,
377 .target = notrack_tg,
378 .table = "raw",
379 .me = THIS_MODULE,
380 },
381 {
382 .name = "CT",
383 .family = NFPROTO_IPV6,
384 .targetsize = sizeof(struct xt_ct_target_info),
385 .usersize = offsetof(struct xt_ct_target_info, ct),
386 .checkentry = xt_ct_tg_check_v0,
387 .destroy = xt_ct_tg_destroy_v0,
388 .target = xt_ct_target_v0,
389 .table = "raw",
390 .me = THIS_MODULE,
391 },
392 {
393 .name = "CT",
394 .family = NFPROTO_IPV6,
395 .revision = 1,
396 .targetsize = sizeof(struct xt_ct_target_info_v1),
397 .usersize = offsetof(struct xt_ct_target_info, ct),
398 .checkentry = xt_ct_tg_check_v1,
399 .destroy = xt_ct_tg_destroy_v1,
400 .target = xt_ct_target_v1,
401 .table = "raw",
402 .me = THIS_MODULE,
403 },
404 {
405 .name = "CT",
406 .family = NFPROTO_IPV6,
407 .revision = 2,
408 .targetsize = sizeof(struct xt_ct_target_info_v1),
409 .usersize = offsetof(struct xt_ct_target_info, ct),
410 .checkentry = xt_ct_tg_check_v2,
411 .destroy = xt_ct_tg_destroy_v1,
412 .target = xt_ct_target_v1,
413 .table = "raw",
414 .me = THIS_MODULE,
415 },
416#endif
417};
418
419static int __init xt_ct_tg_init(void)
420{
421 return xt_register_targets(target: xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
422}
423
424static void __exit xt_ct_tg_exit(void)
425{
426 xt_unregister_targets(target: xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
427}
428
429module_init(xt_ct_tg_init);
430module_exit(xt_ct_tg_exit);
431
432MODULE_LICENSE("GPL");
433MODULE_DESCRIPTION("Xtables: connection tracking target");
434MODULE_ALIAS("ipt_CT");
435MODULE_ALIAS("ip6t_CT");
436MODULE_ALIAS("ipt_NOTRACK");
437MODULE_ALIAS("ip6t_NOTRACK");
438

source code of linux/net/netfilter/xt_CT.c