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 ip6t_entry_target
39 #define STRUCT_ENTRY struct ip6t_entry
40 #define STRUCT_ENTRY_MATCH struct ip6t_entry_match
41 #define STRUCT_GETINFO struct ip6t_getinfo
42 #define STRUCT_GET_ENTRIES struct ip6t_get_entries
43 #define STRUCT_COUNTERS struct ip6t_counters
44 #define STRUCT_COUNTERS_INFO struct ip6t_counters_info
45 #define STRUCT_STANDARD_TARGET struct ip6t_standard_target
46 #define STRUCT_REPLACE struct ip6t_replace
47
48 #define STRUCT_TC_HANDLE struct ip6tc_handle
49 #define xtc_handle ip6tc_handle
50
51 #define ENTRY_ITERATE IP6T_ENTRY_ITERATE
52 #define TABLE_MAXNAMELEN IP6T_TABLE_MAXNAMELEN
53 #define FUNCTION_MAXNAMELEN IP6T_FUNCTION_MAXNAMELEN
54
55 #define GET_TARGET ip6t_get_target
56
57 #define ERROR_TARGET IP6T_ERROR_TARGET
58 #define NUMHOOKS NF_IP6_NUMHOOKS
59
60 #define IPT_CHAINLABEL ip6t_chainlabel
61
62 #define TC_DUMP_ENTRIES dump_entries6
63 #define TC_IS_CHAIN ip6tc_is_chain
64 #define TC_FIRST_CHAIN ip6tc_first_chain
65 #define TC_NEXT_CHAIN ip6tc_next_chain
66 #define TC_FIRST_RULE ip6tc_first_rule
67 #define TC_NEXT_RULE ip6tc_next_rule
68 #define TC_GET_TARGET ip6tc_get_target
69 #define TC_BUILTIN ip6tc_builtin
70 #define TC_GET_POLICY ip6tc_get_policy
71 #define TC_INSERT_ENTRY ip6tc_insert_entry
72 #define TC_REPLACE_ENTRY ip6tc_replace_entry
73 #define TC_APPEND_ENTRY ip6tc_append_entry
74 #define TC_CHECK_ENTRY ip6tc_check_entry
75 #define TC_DELETE_ENTRY ip6tc_delete_entry
76 #define TC_DELETE_NUM_ENTRY ip6tc_delete_num_entry
77 #define TC_FLUSH_ENTRIES ip6tc_flush_entries
78 #define TC_ZERO_ENTRIES ip6tc_zero_entries
79 #define TC_ZERO_COUNTER ip6tc_zero_counter
80 #define TC_READ_COUNTER ip6tc_read_counter
81 #define TC_SET_COUNTER ip6tc_set_counter
82 #define TC_CREATE_CHAIN ip6tc_create_chain
83 #define TC_GET_REFERENCES ip6tc_get_references
84 #define TC_DELETE_CHAIN ip6tc_delete_chain
85 #define TC_RENAME_CHAIN ip6tc_rename_chain
86 #define TC_SET_POLICY ip6tc_set_policy
87 #define TC_GET_RAW_SOCKET ip6tc_get_raw_socket
88 #define TC_INIT ip6tc_init
89 #define TC_FREE ip6tc_free
90 #define TC_COMMIT ip6tc_commit
91 #define TC_STRERROR ip6tc_strerror
92 #define TC_NUM_RULES ip6tc_num_rules
93 #define TC_GET_RULE ip6tc_get_rule
94
95 #define TC_AF AF_INET6
96 #define TC_IPPROTO IPPROTO_IPV6
97
98 #define SO_SET_REPLACE IP6T_SO_SET_REPLACE
99 #define SO_SET_ADD_COUNTERS IP6T_SO_SET_ADD_COUNTERS
100 #define SO_GET_INFO IP6T_SO_GET_INFO
101 #define SO_GET_ENTRIES IP6T_SO_GET_ENTRIES
102 #define SO_GET_VERSION IP6T_SO_GET_VERSION
103
104 #define STANDARD_TARGET IP6T_STANDARD_TARGET
105 #define LABEL_RETURN IP6TC_LABEL_RETURN
106 #define LABEL_ACCEPT IP6TC_LABEL_ACCEPT
107 #define LABEL_DROP IP6TC_LABEL_DROP
108 #define LABEL_QUEUE IP6TC_LABEL_QUEUE
109
110 #define ALIGN XT_ALIGN
111 #define RETURN IP6T_RETURN
112
113 #include "libiptc.c"
114
115 #define BIT6(a, l) \
116 ((ntohl(a->s6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
117
118 int
ipv6_prefix_length(const struct in6_addr * a)119 ipv6_prefix_length(const struct in6_addr *a)
120 {
121 int l, i;
122 for (l = 0; l < 128; l++) {
123 if (BIT6(a, l) == 0)
124 break;
125 }
126 for (i = l + 1; i < 128; i++) {
127 if (BIT6(a, i) == 1)
128 return -1;
129 }
130 return l;
131 }
132
133 static int
dump_entry(struct ip6t_entry * e,struct ip6tc_handle * const handle)134 dump_entry(struct ip6t_entry *e, struct ip6tc_handle *const handle)
135 {
136 size_t i;
137 char buf[40];
138 int len;
139 struct ip6t_entry_target *t;
140
141 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
142 iptcb_entry2offset(handle, e));
143 puts("SRC IP: ");
144 inet_ntop(AF_INET6, &e->ipv6.src, buf, sizeof buf);
145 puts(buf);
146 putchar('/');
147 len = ipv6_prefix_length(&e->ipv6.smsk);
148 if (len != -1)
149 printf("%d", len);
150 else {
151 inet_ntop(AF_INET6, &e->ipv6.smsk, buf, sizeof buf);
152 puts(buf);
153 }
154 putchar('\n');
155
156 puts("DST IP: ");
157 inet_ntop(AF_INET6, &e->ipv6.dst, buf, sizeof buf);
158 puts(buf);
159 putchar('/');
160 len = ipv6_prefix_length(&e->ipv6.dmsk);
161 if (len != -1)
162 printf("%d", len);
163 else {
164 inet_ntop(AF_INET6, &e->ipv6.dmsk, buf, sizeof buf);
165 puts(buf);
166 }
167 putchar('\n');
168
169 printf("Interface: `%s'/", e->ipv6.iniface);
170 for (i = 0; i < IFNAMSIZ; i++)
171 printf("%c", e->ipv6.iniface_mask[i] ? 'X' : '.');
172 printf("to `%s'/", e->ipv6.outiface);
173 for (i = 0; i < IFNAMSIZ; i++)
174 printf("%c", e->ipv6.outiface_mask[i] ? 'X' : '.');
175 printf("\nProtocol: %u\n", e->ipv6.proto);
176 if (e->ipv6.flags & IP6T_F_TOS)
177 printf("TOS: %u\n", e->ipv6.tos);
178 printf("Flags: %02X\n", e->ipv6.flags);
179 printf("Invflags: %02X\n", e->ipv6.invflags);
180 printf("Counters: %llu packets, %llu bytes\n",
181 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
182 printf("Cache: %08X\n", e->nfcache);
183
184 IP6T_MATCH_ITERATE(e, print_match);
185
186 t = ip6t_get_target(e);
187 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
188 if (strcmp(t->u.user.name, IP6T_STANDARD_TARGET) == 0) {
189 const unsigned char *data = t->data;
190 int pos = *(const int *)data;
191 if (pos < 0)
192 printf("verdict=%s\n",
193 pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
194 : pos == -NF_DROP-1 ? "NF_DROP"
195 : pos == IP6T_RETURN ? "RETURN"
196 : "UNKNOWN");
197 else
198 printf("verdict=%u\n", pos);
199 } else if (strcmp(t->u.user.name, IP6T_ERROR_TARGET) == 0)
200 printf("error=`%s'\n", t->data);
201
202 printf("\n");
203 return 0;
204 }
205
206 static unsigned char *
is_same(const STRUCT_ENTRY * a,const STRUCT_ENTRY * b,unsigned char * matchmask)207 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b,
208 unsigned char *matchmask)
209 {
210 unsigned int i;
211 unsigned char *mptr;
212
213 /* Always compare head structures: ignore mask here. */
214 if (memcmp(&a->ipv6.src, &b->ipv6.src, sizeof(struct in6_addr))
215 || memcmp(&a->ipv6.dst, &b->ipv6.dst, sizeof(struct in6_addr))
216 || memcmp(&a->ipv6.smsk, &b->ipv6.smsk, sizeof(struct in6_addr))
217 || memcmp(&a->ipv6.dmsk, &b->ipv6.dmsk, sizeof(struct in6_addr))
218 || a->ipv6.proto != b->ipv6.proto
219 || a->ipv6.tos != b->ipv6.tos
220 || a->ipv6.flags != b->ipv6.flags
221 || a->ipv6.invflags != b->ipv6.invflags)
222 return NULL;
223
224 for (i = 0; i < IFNAMSIZ; i++) {
225 if (a->ipv6.iniface_mask[i] != b->ipv6.iniface_mask[i])
226 return NULL;
227 if ((a->ipv6.iniface[i] & a->ipv6.iniface_mask[i])
228 != (b->ipv6.iniface[i] & b->ipv6.iniface_mask[i]))
229 return NULL;
230 if (a->ipv6.outiface_mask[i] != b->ipv6.outiface_mask[i])
231 return NULL;
232 if ((a->ipv6.outiface[i] & a->ipv6.outiface_mask[i])
233 != (b->ipv6.outiface[i] & b->ipv6.outiface_mask[i]))
234 return NULL;
235 }
236
237 if (a->target_offset != b->target_offset
238 || a->next_offset != b->next_offset)
239 return NULL;
240
241 mptr = matchmask + sizeof(STRUCT_ENTRY);
242 if (IP6T_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
243 return NULL;
244 mptr += XT_ALIGN(sizeof(struct ip6t_entry_target));
245
246 return mptr;
247 }
248
249 /* All zeroes == unconditional rule. */
250 static inline int
unconditional(const struct ip6t_ip6 * ipv6)251 unconditional(const struct ip6t_ip6 *ipv6)
252 {
253 unsigned int i;
254
255 for (i = 0; i < sizeof(*ipv6); i++)
256 if (((char *)ipv6)[i])
257 break;
258
259 return (i == sizeof(*ipv6));
260 }
261
262 #ifdef IPTC_DEBUG
263 /* Do every conceivable sanity check on the handle */
264 static void
do_check(struct xtc_handle * h,unsigned int line)265 do_check(struct xtc_handle *h, unsigned int line)
266 {
267 unsigned int i, n;
268 unsigned int user_offset; /* Offset of first user chain */
269 int was_return;
270
271 assert(h->changed == 0 || h->changed == 1);
272 if (strcmp(h->info.name, "filter") == 0) {
273 assert(h->info.valid_hooks
274 == (1 << NF_IP6_LOCAL_IN
275 | 1 << NF_IP6_FORWARD
276 | 1 << NF_IP6_LOCAL_OUT));
277
278 /* Hooks should be first three */
279 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == 0);
280
281 n = get_chain_end(h, 0);
282 n += get_entry(h, n)->next_offset;
283 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
284
285 n = get_chain_end(h, n);
286 n += get_entry(h, n)->next_offset;
287 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
288
289 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
290 } else if (strcmp(h->info.name, "nat") == 0) {
291 assert((h->info.valid_hooks
292 == (1 << NF_IP6_PRE_ROUTING
293 | 1 << NF_IP6_LOCAL_OUT
294 | 1 << NF_IP6_POST_ROUTING)) ||
295 (h->info.valid_hooks
296 == (1 << NF_IP6_PRE_ROUTING
297 | 1 << NF_IP6_LOCAL_IN
298 | 1 << NF_IP6_LOCAL_OUT
299 | 1 << NF_IP6_POST_ROUTING)));
300
301 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
302
303 n = get_chain_end(h, 0);
304
305 n += get_entry(h, n)->next_offset;
306 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
307 n = get_chain_end(h, n);
308
309 n += get_entry(h, n)->next_offset;
310 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
311 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
312
313 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
314 n = get_chain_end(h, n);
315 n += get_entry(h, n)->next_offset;
316 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
317 user_offset = h->info.hook_entry[NF_IP6_LOCAL_IN];
318 }
319
320 } else if (strcmp(h->info.name, "mangle") == 0) {
321 /* This code is getting ugly because linux < 2.4.18-pre6 had
322 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
323 * */
324 assert((h->info.valid_hooks
325 == (1 << NF_IP6_PRE_ROUTING
326 | 1 << NF_IP6_LOCAL_OUT)) ||
327 (h->info.valid_hooks
328 == (1 << NF_IP6_PRE_ROUTING
329 | 1 << NF_IP6_LOCAL_IN
330 | 1 << NF_IP6_FORWARD
331 | 1 << NF_IP6_LOCAL_OUT
332 | 1 << NF_IP6_POST_ROUTING)));
333
334 /* Hooks should be first five */
335 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
336
337 n = get_chain_end(h, 0);
338
339 if (h->info.valid_hooks & (1 << NF_IP6_LOCAL_IN)) {
340 n += get_entry(h, n)->next_offset;
341 assert(h->info.hook_entry[NF_IP6_LOCAL_IN] == n);
342 n = get_chain_end(h, n);
343 }
344
345 if (h->info.valid_hooks & (1 << NF_IP6_FORWARD)) {
346 n += get_entry(h, n)->next_offset;
347 assert(h->info.hook_entry[NF_IP6_FORWARD] == n);
348 n = get_chain_end(h, n);
349 }
350
351 n += get_entry(h, n)->next_offset;
352 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
353 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
354
355 if (h->info.valid_hooks & (1 << NF_IP6_POST_ROUTING)) {
356 n = get_chain_end(h, n);
357 n += get_entry(h, n)->next_offset;
358 assert(h->info.hook_entry[NF_IP6_POST_ROUTING] == n);
359 user_offset = h->info.hook_entry[NF_IP6_POST_ROUTING];
360 }
361 } else if (strcmp(h->info.name, "raw") == 0) {
362 assert(h->info.valid_hooks
363 == (1 << NF_IP6_PRE_ROUTING
364 | 1 << NF_IP6_LOCAL_OUT));
365
366 /* Hooks should be first three */
367 assert(h->info.hook_entry[NF_IP6_PRE_ROUTING] == 0);
368
369 n = get_chain_end(h, n);
370 n += get_entry(h, n)->next_offset;
371 assert(h->info.hook_entry[NF_IP6_LOCAL_OUT] == n);
372
373 user_offset = h->info.hook_entry[NF_IP6_LOCAL_OUT];
374 } else {
375 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
376 abort();
377 }
378
379 /* User chain == end of last builtin + policy entry */
380 user_offset = get_chain_end(h, user_offset);
381 user_offset += get_entry(h, user_offset)->next_offset;
382
383 /* Overflows should be end of entry chains, and unconditional
384 policy nodes. */
385 for (i = 0; i < NUMHOOKS; i++) {
386 STRUCT_ENTRY *e;
387 STRUCT_STANDARD_TARGET *t;
388
389 if (!(h->info.valid_hooks & (1 << i)))
390 continue;
391 assert(h->info.underflow[i]
392 == get_chain_end(h, h->info.hook_entry[i]));
393
394 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
395 assert(unconditional(&e->ipv6));
396 assert(e->target_offset == sizeof(*e));
397 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
398 printf("target_size=%u, align=%u\n",
399 t->target.u.target_size, ALIGN(sizeof(*t)));
400 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
401 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
402
403 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
404 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
405
406 /* Hooks and underflows must be valid entries */
407 iptcb_entry2index(h, get_entry(h, h->info.hook_entry[i]));
408 iptcb_entry2index(h, get_entry(h, h->info.underflow[i]));
409 }
410
411 assert(h->info.size
412 >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
413 +sizeof(STRUCT_STANDARD_TARGET)));
414
415 assert(h->entries.size
416 >= (h->new_number
417 * (sizeof(STRUCT_ENTRY)
418 + sizeof(STRUCT_STANDARD_TARGET))));
419 assert(strcmp(h->info.name, h->entries.name) == 0);
420
421 i = 0; n = 0;
422 was_return = 0;
423
424 #if 0
425 /* Check all the entries. */
426 ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
427 check_entry, &i, &n, user_offset, &was_return, h);
428
429 assert(i == h->new_number);
430 assert(n == h->entries.size);
431
432 /* Final entry must be error node */
433 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
434 ->u.user.name,
435 ERROR_TARGET) == 0);
436 #endif
437 }
438 #endif /*IPTC_DEBUG*/
439