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
xt_ct_target(struct sk_buff * skb,struct nf_conn * ct)20 static 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(&ct->ct_general.use);
28 nf_ct_set(skb, ct, IP_CT_NEW);
29 } else {
30 nf_ct_set(skb, ct, IP_CT_UNTRACKED);
31 }
32
33 return XT_CONTINUE;
34 }
35
xt_ct_target_v0(struct sk_buff * skb,const struct xt_action_param * par)36 static 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
xt_ct_target_v1(struct sk_buff * skb,const struct xt_action_param * par)45 static 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
xt_ct_find_proto(const struct xt_tgchk_param * par)54 static 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
72 static int
xt_ct_set_helper(struct nf_conn * ct,const char * helper_name,const struct xt_tgchk_param * par)73 xt_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(helper_name, par->family,
87 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 help->helper = helper;
100 return 0;
101 }
102
103 static int
xt_ct_set_timeout(struct nf_conn * ct,const struct xt_tgchk_param * par,const char * timeout_name)104 xt_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(proto);
118 return nf_ct_set_timeout(par->net, ct, par->family, l4proto->l4proto,
119 timeout_name);
120
121 #else
122 return -EOPNOTSUPP;
123 #endif
124 }
125
xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 * info)126 static 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
xt_ct_tg_check(const struct xt_tgchk_param * par,struct xt_ct_target_info_v1 * info)139 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
140 struct xt_ct_target_info_v1 *info)
141 {
142 struct nf_conntrack_zone zone;
143 struct nf_conn_help *help;
144 struct nf_conn *ct;
145 int ret = -EOPNOTSUPP;
146
147 if (info->flags & XT_CT_NOTRACK) {
148 ct = NULL;
149 goto out;
150 }
151
152 #ifndef CONFIG_NF_CONNTRACK_ZONES
153 if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
154 XT_CT_ZONE_DIR_REPL |
155 XT_CT_ZONE_MARK))
156 goto err1;
157 #endif
158
159 ret = nf_ct_netns_get(par->net, par->family);
160 if (ret < 0)
161 goto err1;
162
163 memset(&zone, 0, sizeof(zone));
164 zone.id = info->zone;
165 zone.dir = xt_ct_flags_to_dir(info);
166 if (info->flags & XT_CT_ZONE_MARK)
167 zone.flags |= NF_CT_FLAG_MARK;
168
169 ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
170 if (!ct) {
171 ret = -ENOMEM;
172 goto err2;
173 }
174
175 if ((info->ct_events || info->exp_events) &&
176 !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
177 GFP_KERNEL)) {
178 ret = -EINVAL;
179 goto err3;
180 }
181
182 if (info->helper[0]) {
183 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
184 ret = -ENAMETOOLONG;
185 goto err3;
186 }
187
188 ret = xt_ct_set_helper(ct, info->helper, par);
189 if (ret < 0)
190 goto err3;
191 }
192
193 if (info->timeout[0]) {
194 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
195 ret = -ENAMETOOLONG;
196 goto err4;
197 }
198
199 ret = xt_ct_set_timeout(ct, par, info->timeout);
200 if (ret < 0)
201 goto err4;
202 }
203 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
204 out:
205 info->ct = ct;
206 return 0;
207
208 err4:
209 help = nfct_help(ct);
210 if (help)
211 nf_conntrack_helper_put(help->helper);
212 err3:
213 nf_ct_tmpl_free(ct);
214 err2:
215 nf_ct_netns_put(par->net, par->family);
216 err1:
217 return ret;
218 }
219
xt_ct_tg_check_v0(const struct xt_tgchk_param * par)220 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
221 {
222 struct xt_ct_target_info *info = par->targinfo;
223 struct xt_ct_target_info_v1 info_v1 = {
224 .flags = info->flags,
225 .zone = info->zone,
226 .ct_events = info->ct_events,
227 .exp_events = info->exp_events,
228 };
229 int ret;
230
231 if (info->flags & ~XT_CT_NOTRACK)
232 return -EINVAL;
233
234 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
235
236 ret = xt_ct_tg_check(par, &info_v1);
237 if (ret < 0)
238 return ret;
239
240 info->ct = info_v1.ct;
241
242 return ret;
243 }
244
xt_ct_tg_check_v1(const struct xt_tgchk_param * par)245 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
246 {
247 struct xt_ct_target_info_v1 *info = par->targinfo;
248
249 if (info->flags & ~XT_CT_NOTRACK)
250 return -EINVAL;
251
252 return xt_ct_tg_check(par, par->targinfo);
253 }
254
xt_ct_tg_check_v2(const struct xt_tgchk_param * par)255 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
256 {
257 struct xt_ct_target_info_v1 *info = par->targinfo;
258
259 if (info->flags & ~XT_CT_MASK)
260 return -EINVAL;
261
262 return xt_ct_tg_check(par, par->targinfo);
263 }
264
xt_ct_tg_destroy(const struct xt_tgdtor_param * par,struct xt_ct_target_info_v1 * info)265 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
266 struct xt_ct_target_info_v1 *info)
267 {
268 struct nf_conn *ct = info->ct;
269 struct nf_conn_help *help;
270
271 if (ct) {
272 help = nfct_help(ct);
273 if (help)
274 nf_conntrack_helper_put(help->helper);
275
276 nf_ct_netns_put(par->net, par->family);
277
278 nf_ct_destroy_timeout(ct);
279 nf_ct_put(info->ct);
280 }
281 }
282
xt_ct_tg_destroy_v0(const struct xt_tgdtor_param * par)283 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
284 {
285 struct xt_ct_target_info *info = par->targinfo;
286 struct xt_ct_target_info_v1 info_v1 = {
287 .flags = info->flags,
288 .zone = info->zone,
289 .ct_events = info->ct_events,
290 .exp_events = info->exp_events,
291 .ct = info->ct,
292 };
293 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
294
295 xt_ct_tg_destroy(par, &info_v1);
296 }
297
xt_ct_tg_destroy_v1(const struct xt_tgdtor_param * par)298 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
299 {
300 xt_ct_tg_destroy(par, par->targinfo);
301 }
302
303 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
304 {
305 .name = "CT",
306 .family = NFPROTO_UNSPEC,
307 .targetsize = sizeof(struct xt_ct_target_info),
308 .usersize = offsetof(struct xt_ct_target_info, ct),
309 .checkentry = xt_ct_tg_check_v0,
310 .destroy = xt_ct_tg_destroy_v0,
311 .target = xt_ct_target_v0,
312 .table = "raw",
313 .me = THIS_MODULE,
314 },
315 {
316 .name = "CT",
317 .family = NFPROTO_UNSPEC,
318 .revision = 1,
319 .targetsize = sizeof(struct xt_ct_target_info_v1),
320 .usersize = offsetof(struct xt_ct_target_info, ct),
321 .checkentry = xt_ct_tg_check_v1,
322 .destroy = xt_ct_tg_destroy_v1,
323 .target = xt_ct_target_v1,
324 .table = "raw",
325 .me = THIS_MODULE,
326 },
327 {
328 .name = "CT",
329 .family = NFPROTO_UNSPEC,
330 .revision = 2,
331 .targetsize = sizeof(struct xt_ct_target_info_v1),
332 .usersize = offsetof(struct xt_ct_target_info, ct),
333 .checkentry = xt_ct_tg_check_v2,
334 .destroy = xt_ct_tg_destroy_v1,
335 .target = xt_ct_target_v1,
336 .table = "raw",
337 .me = THIS_MODULE,
338 },
339 };
340
341 static unsigned int
notrack_tg(struct sk_buff * skb,const struct xt_action_param * par)342 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
343 {
344 /* Previously seen (loopback)? Ignore. */
345 if (skb->_nfct != 0)
346 return XT_CONTINUE;
347
348 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
349
350 return XT_CONTINUE;
351 }
352
353 static struct xt_target notrack_tg_reg __read_mostly = {
354 .name = "NOTRACK",
355 .revision = 0,
356 .family = NFPROTO_UNSPEC,
357 .target = notrack_tg,
358 .table = "raw",
359 .me = THIS_MODULE,
360 };
361
xt_ct_tg_init(void)362 static int __init xt_ct_tg_init(void)
363 {
364 int ret;
365
366 ret = xt_register_target(¬rack_tg_reg);
367 if (ret < 0)
368 return ret;
369
370 ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
371 if (ret < 0) {
372 xt_unregister_target(¬rack_tg_reg);
373 return ret;
374 }
375 return 0;
376 }
377
xt_ct_tg_exit(void)378 static void __exit xt_ct_tg_exit(void)
379 {
380 xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
381 xt_unregister_target(¬rack_tg_reg);
382 }
383
384 module_init(xt_ct_tg_init);
385 module_exit(xt_ct_tg_exit);
386
387 MODULE_LICENSE("GPL");
388 MODULE_DESCRIPTION("Xtables: connection tracking target");
389 MODULE_ALIAS("ipt_CT");
390 MODULE_ALIAS("ip6t_CT");
391 MODULE_ALIAS("ipt_NOTRACK");
392 MODULE_ALIAS("ip6t_NOTRACK");
393