1 /* Library which manipulates firewall rules. Version 0.1. */
2
3 /* Architecture of firewall rules is as follows:
4 *
5 * Chains go INPUT, FORWARD, OUTPUT then user chains.
6 * Each user chain starts with an ERROR node.
7 * Every chain ends with an unconditional jump: a RETURN for user chains,
8 * and a POLICY for built-ins.
9 */
10
11 /* (C)1999 Paul ``Rusty'' Russell - Placed under the GNU GPL (See
12 COPYING for details). */
13
14 #include <assert.h>
15 #include <string.h>
16 #include <errno.h>
17 #include <stdlib.h>
18 #include <stdio.h>
19 #include <unistd.h>
20 #include <arpa/inet.h>
21
22 #ifdef DEBUG_CONNTRACK
23 #define inline
24 #endif
25
26 #if !defined(__ANDROID__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
27 typedef unsigned int socklen_t;
28 #endif
29
30 #include "libiptc/libip6tc.h"
31
32 #define HOOK_PRE_ROUTING NF_IP6_PRE_ROUTING
33 #define HOOK_LOCAL_IN NF_IP6_LOCAL_IN
34 #define HOOK_FORWARD NF_IP6_FORWARD
35 #define HOOK_LOCAL_OUT NF_IP6_LOCAL_OUT
36 #define HOOK_POST_ROUTING NF_IP6_POST_ROUTING
37
38 #define STRUCT_ENTRY_TARGET struct xt_entry_target
39 #define STRUCT_ENTRY struct ip6t_entry
40 #define STRUCT_ENTRY_MATCH struct xt_entry_match
41 #define STRUCT_GETINFO struct ip6t_getinfo
42 #define STRUCT_GET_ENTRIES struct ip6t_get_entries
43 #define STRUCT_COUNTERS struct xt_counters
44 #define STRUCT_COUNTERS_INFO struct xt_counters_info
45 #define STRUCT_STANDARD_TARGET struct xt_standard_target
46 #define STRUCT_REPLACE struct ip6t_replace
47
48 #define ENTRY_ITERATE IP6T_ENTRY_ITERATE
49 #define TABLE_MAXNAMELEN XT_TABLE_MAXNAMELEN
50 #define FUNCTION_MAXNAMELEN XT_FUNCTION_MAXNAMELEN
51
52 #define GET_TARGET ip6t_get_target
53
54 #define ERROR_TARGET XT_ERROR_TARGET
55 #define NUMHOOKS NF_IP6_NUMHOOKS
56
57 #define IPT_CHAINLABEL xt_chainlabel
58
59 #define TC_DUMP_ENTRIES dump_entries6
60 #define TC_IS_CHAIN ip6tc_is_chain
61 #define TC_FIRST_CHAIN ip6tc_first_chain
62 #define TC_NEXT_CHAIN ip6tc_next_chain
63 #define TC_FIRST_RULE ip6tc_first_rule
64 #define TC_NEXT_RULE ip6tc_next_rule
65 #define TC_GET_TARGET ip6tc_get_target
66 #define TC_BUILTIN ip6tc_builtin
67 #define TC_GET_POLICY ip6tc_get_policy
68 #define TC_INSERT_ENTRY ip6tc_insert_entry
69 #define TC_REPLACE_ENTRY ip6tc_replace_entry
70 #define TC_APPEND_ENTRY ip6tc_append_entry
71 #define TC_CHECK_ENTRY ip6tc_check_entry
72 #define TC_DELETE_ENTRY ip6tc_delete_entry
73 #define TC_DELETE_NUM_ENTRY ip6tc_delete_num_entry
74 #define TC_FLUSH_ENTRIES ip6tc_flush_entries
75 #define TC_ZERO_ENTRIES ip6tc_zero_entries
76 #define TC_ZERO_COUNTER ip6tc_zero_counter
77 #define TC_READ_COUNTER ip6tc_read_counter
78 #define TC_SET_COUNTER ip6tc_set_counter
79 #define TC_CREATE_CHAIN ip6tc_create_chain
80 #define TC_GET_REFERENCES ip6tc_get_references
81 #define TC_DELETE_CHAIN ip6tc_delete_chain
82 #define TC_RENAME_CHAIN ip6tc_rename_chain
83 #define TC_SET_POLICY ip6tc_set_policy
84 #define TC_GET_RAW_SOCKET ip6tc_get_raw_socket
85 #define TC_INIT ip6tc_init
86 #define TC_FREE ip6tc_free
87 #define TC_COMMIT ip6tc_commit
88 #define TC_STRERROR ip6tc_strerror
89 #define TC_NUM_RULES ip6tc_num_rules
90 #define TC_GET_RULE ip6tc_get_rule
91 #define TC_OPS ip6tc_ops
92
93 #define TC_AF AF_INET6
94 #define TC_IPPROTO IPPROTO_IPV6
95
96 #define SO_SET_REPLACE IP6T_SO_SET_REPLACE
97 #define SO_SET_ADD_COUNTERS IP6T_SO_SET_ADD_COUNTERS
98 #define SO_GET_INFO IP6T_SO_GET_INFO
99 #define SO_GET_ENTRIES IP6T_SO_GET_ENTRIES
100 #define SO_GET_VERSION IP6T_SO_GET_VERSION
101
102 #define STANDARD_TARGET XT_STANDARD_TARGET
103 #define LABEL_RETURN IP6TC_LABEL_RETURN
104 #define LABEL_ACCEPT IP6TC_LABEL_ACCEPT
105 #define LABEL_DROP IP6TC_LABEL_DROP
106 #define LABEL_QUEUE IP6TC_LABEL_QUEUE
107
108 #define ALIGN XT_ALIGN
109 #define RETURN XT_RETURN
110
111 #include "libiptc.c"
112
113 #define BIT6(a, l) \
114 ((ntohl(a->s6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
115
116 static int
ipv6_prefix_length(const struct in6_addr * a)117 ipv6_prefix_length(const struct in6_addr *a)
118 {
119 int l, i;
120 for (l = 0; l < 128; l++) {
121 if (BIT6(a, l) == 0)
122 break;
123 }
124 for (i = l + 1; i < 128; i++) {
125 if (BIT6(a, i) == 1)
126 return -1;
127 }
128 return l;
129 }
130
131 static int
dump_entry(struct ip6t_entry * e,struct xtc_handle * const handle)132 dump_entry(struct ip6t_entry *e, struct xtc_handle *const handle)
133 {
134 size_t i;
135 char buf[40];
136 int len;
137 struct xt_entry_target *t;
138
139 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
140 iptcb_entry2offset(handle, e));
141 puts("SRC IP: ");
142 inet_ntop(AF_INET6, &e->ipv6.src, buf, sizeof buf);
143 puts(buf);
144 putchar('/');
145 len = ipv6_prefix_length(&e->ipv6.smsk);
146 if (len != -1)
147 printf("%d", len);
148 else {
149 inet_ntop(AF_INET6, &e->ipv6.smsk, buf, sizeof buf);
150 puts(buf);
151 }
152 putchar('\n');
153
154 puts("DST IP: ");
155 inet_ntop(AF_INET6, &e->ipv6.dst, buf, sizeof buf);
156 puts(buf);
157 putchar('/');
158 len = ipv6_prefix_length(&e->ipv6.dmsk);
159 if (len != -1)
160 printf("%d", len);
161 else {
162 inet_ntop(AF_INET6, &e->ipv6.dmsk, buf, sizeof buf);
163 puts(buf);
164 }
165 putchar('\n');
166
167 printf("Interface: `%s'/", e->ipv6.iniface);
168 for (i = 0; i < IFNAMSIZ; i++)
169 printf("%c", e->ipv6.iniface_mask[i] ? 'X' : '.');
170 printf("to `%s'/", e->ipv6.outiface);
171 for (i = 0; i < IFNAMSIZ; i++)
172 printf("%c", e->ipv6.outiface_mask[i] ? 'X' : '.');
173 printf("\nProtocol: %u\n", e->ipv6.proto);
174 if (e->ipv6.flags & IP6T_F_TOS)
175 printf("TOS: %u\n", e->ipv6.tos);
176 printf("Flags: %02X\n", e->ipv6.flags);
177 printf("Invflags: %02X\n", e->ipv6.invflags);
178 printf("Counters: %llu packets, %llu bytes\n",
179 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
180 printf("Cache: %08X\n", e->nfcache);
181
182 IP6T_MATCH_ITERATE(e, print_match);
183
184 t = ip6t_get_target(e);
185 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
186 if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0) {
187 const unsigned char *data = t->data;
188 int pos = *(const int *)data;
189 if (pos < 0)
190 printf("verdict=%s\n",
191 pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
192 : pos == -NF_DROP-1 ? "NF_DROP"
193 : pos == XT_RETURN ? "RETURN"
194 : "UNKNOWN");
195 else
196 printf("verdict=%u\n", pos);
197 } else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0)
198 printf("error=`%s'\n", t->data);
199
200 printf("\n");
201 return 0;
202 }
203
204 static unsigned char *
is_same(const STRUCT_ENTRY * a,const STRUCT_ENTRY * b,unsigned char * matchmask)205 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
206 unsigned char *matchmask)
207 {
208 unsigned int i;
209 unsigned char *mptr;
210
211 /* Always compare head structures: ignore mask here. */
212 if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
213 || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
214 || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
215 || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
216 || a->ipv6.proto != b->ipv6.proto
217 || a->ipv6.tos != b->ipv6.tos
218 || a->ipv6.flags != b->ipv6.flags
219 || a->ipv6.invflags != b->ipv6.invflags)
220 return NULL;
221
222 for (i = 0; i < IFNAMSIZ; i++) {
223 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
224 return NULL;
225 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
226 != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
227 return NULL;
228 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
229 return NULL;
230 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
231 != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
232 return NULL;
233 }
234
235 if (a->target_offset != b->target_offset
236 || a->next_offset != b->next_offset)
237 return NULL;
238
239 mptr = matchmask + sizeof(STRUCT_ENTRY);
240 if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
241 return NULL;
242 mptr += XT_ALIGN(sizeof(struct xt_entry_target));
243
244 return mptr;
245 }
246
247 /* All zeroes == unconditional rule. */
248 static inline int
unconditional(const struct ip6t_ip6 * ipv6)249 unconditional(const struct ip6t_ip6 *ipv6)
250 {
251 unsigned int i;
252
253 for (i = 0; i < sizeof(*ipv6); i++)
254 if (((char *)ipv6)[i])
255 break;
256
257 return (i == sizeof(*ipv6));
258 }
259
260 #ifdef IPTC_DEBUG
261 /* Do every conceivable sanity check on the handle */
262 static void
do_check(struct xtc_handle * h,unsigned int line)263 do_check(struct xtc_handle *h, unsigned int line)
264 {
265 unsigned int i, n;
266 unsigned int user_offset; /* Offset of first user chain */
267 int was_return;
268
269 assert(h->changed == 0 || h->changed == 1);
270 if (strcmp(h->info.name, "filter") == 0) {
271 assert(h->info.valid_hooks
272 == (1 << NF_IP6_LOCAL_IN
273 | 1 << NF_IP6_FORWARD
274 | 1 << NF_IP6_LOCAL_OUT));
275
276 /* Hooks should be first three */
277 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
278
279 n = get_chain_end(h, 0);
280 n += get_entry(h, n)->next_offset;
281 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
282
283 n = get_chain_end(h, n);
284 n += get_entry(h, n)->next_offset;
285 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
286
287 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
288 } else if (strcmp(h->info.name, "nat") == 0) {
289 assert((h->info.valid_hooks
290 == (1 << NF_IP6_PRE_ROUTING
291 | 1 << NF_IP6_LOCAL_OUT
292 | 1 << NF_IP6_POST_ROUTING)) ||
293 (h->info.valid_hooks
294 == (1 << NF_IP6_PRE_ROUTING
295 | 1 << NF_IP6_LOCAL_IN
296 | 1 << NF_IP6_LOCAL_OUT
297 | 1 << NF_IP6_POST_ROUTING)));
298
299 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
300
301 n = get_chain_end(h, 0);
302
303 n += get_entry(h, n)->next_offset;
304 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
305 n = get_chain_end(h, n);
306
307 n += get_entry(h, n)->next_offset;
308 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
309 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
310
311 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
312 n = get_chain_end(h, n);
313 n += get_entry(h, n)->next_offset;
314 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
315 user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
316 }
317
318 } else if (strcmp(h->info.name, "mangle") == 0) {
319 /* This code is getting ugly because linux < 2.4.18-pre6 had
320 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
321 * */
322 assert((h->info.valid_hooks
323 == (1 << NF_IP6_PRE_ROUTING
324 | 1 << NF_IP6_LOCAL_OUT)) ||
325 (h->info.valid_hooks
326 == (1 << NF_IP6_PRE_ROUTING
327 | 1 << NF_IP6_LOCAL_IN
328 | 1 << NF_IP6_FORWARD
329 | 1 << NF_IP6_LOCAL_OUT
330 | 1 << NF_IP6_POST_ROUTING)));
331
332 /* Hooks should be first five */
333 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
334
335 n = get_chain_end(h, 0);
336
337 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
338 n += get_entry(h, n)->next_offset;
339 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
340 n = get_chain_end(h, n);
341 }
342
343 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
344 n += get_entry(h, n)->next_offset;
345 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
346 n = get_chain_end(h, n);
347 }
348
349 n += get_entry(h, n)->next_offset;
350 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
351 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
352
353 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
354 n = get_chain_end(h, n);
355 n += get_entry(h, n)->next_offset;
356 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
357 user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
358 }
359 } else if (strcmp(h->info.name, "raw") == 0) {
360 assert(h->info.valid_hooks
361 == (1 << NF_IP6_PRE_ROUTING
362 | 1 << NF_IP6_LOCAL_OUT));
363
364 /* Hooks should be first three */
365 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
366
367 n = get_chain_end(h, n);
368 n += get_entry(h, n)->next_offset;
369 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
370
371 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
372 } else {
373 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
374 abort();
375 }
376
377 /* User chain == end of last builtin + policy entry */
378 user_offset = get_chain_end(h, user_offset);
379 user_offset += get_entry(h, user_offset)->next_offset;
380
381 /* Overflows should be end of entry chains, and unconditional
382 policy nodes. */
383 for (i = 0; i < NUMHOOKS; i++) {
384 STRUCT_ENTRY *e;
385 STRUCT_STANDARD_TARGET *t;
386
387 if (!(h->info.valid_hooks & (1 << i)))
388 continue;
389 assert(h->info.underflow[i]
390 == get_chain_end(h, h->info.hook_entry[i]));
391
392 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
393 assert(unconditional(&e->ipv6));
394 assert(e->target_offset == sizeof(*e));
395 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
396 printf("target_size=%u, align=%u\n",
397 t->target.u.target_size, ALIGN(sizeof(*t)));
398 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
399 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
400
401 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
402 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
403
404 /* Hooks and underflows must be valid entries */
405 iptcb_entry2index(h, get_entry(h, h->info.hook_entry[i]));
406 iptcb_entry2index(h, get_entry(h, h->info.underflow[i]));
407 }
408
409 assert(h->info.size
410 >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
411 +sizeof(STRUCT_STANDARD_TARGET)));
412
413 assert(h->entries.size
414 >= (h->new_number
415 * (sizeof(STRUCT_ENTRY)
416 + sizeof(STRUCT_STANDARD_TARGET))));
417 assert(strcmp(h->info.name, h->entries.name) == 0);
418
419 i = 0; n = 0;
420 was_return = 0;
421
422 #if 0
423 /* Check all the entries. */
424 ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
425 check_entry, &i, &n, user_offset, &was_return, h);
426
427 assert(i == h->new_number);
428 assert(n == h->entries.size);
429
430 /* Final entry must be error node */
431 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
432 ->u.user.name,
433 ERROR_TARGET) == 0);
434 #endif
435 }
436 #endif /*IPTC_DEBUG*/
437