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 <netinet/in.h>
21
22 #ifdef DEBUG_CONNTRACK
23 #define inline
24 #endif
25
26 #include "libiptc/libiptc.h"
27
28 #define IP_VERSION 4
29 #define IP_OFFSET 0x1FFF
30
31 #define HOOK_PRE_ROUTING NF_IP_PRE_ROUTING
32 #define HOOK_LOCAL_IN NF_IP_LOCAL_IN
33 #define HOOK_FORWARD NF_IP_FORWARD
34 #define HOOK_LOCAL_OUT NF_IP_LOCAL_OUT
35 #define HOOK_POST_ROUTING NF_IP_POST_ROUTING
36 #ifdef NF_IP_DROPPING
37 #define HOOK_DROPPING NF_IP_DROPPING
38 #endif
39
40 #define STRUCT_ENTRY_TARGET struct ipt_entry_target
41 #define STRUCT_ENTRY struct ipt_entry
42 #define STRUCT_ENTRY_MATCH struct ipt_entry_match
43 #define STRUCT_GETINFO struct ipt_getinfo
44 #define STRUCT_GET_ENTRIES struct ipt_get_entries
45 #define STRUCT_COUNTERS struct ipt_counters
46 #define STRUCT_COUNTERS_INFO struct ipt_counters_info
47 #define STRUCT_STANDARD_TARGET struct ipt_standard_target
48 #define STRUCT_REPLACE struct ipt_replace
49
50 #define STRUCT_TC_HANDLE struct iptc_handle
51 #define TC_HANDLE_T iptc_handle_t
52
53 #define ENTRY_ITERATE IPT_ENTRY_ITERATE
54 #define TABLE_MAXNAMELEN IPT_TABLE_MAXNAMELEN
55 #define FUNCTION_MAXNAMELEN IPT_FUNCTION_MAXNAMELEN
56
57 #define GET_TARGET ipt_get_target
58
59 #define ERROR_TARGET IPT_ERROR_TARGET
60 #define NUMHOOKS NF_IP_NUMHOOKS
61
62 #define IPT_CHAINLABEL ipt_chainlabel
63
64 #define TC_DUMP_ENTRIES dump_entries
65 #define TC_IS_CHAIN iptc_is_chain
66 #define TC_FIRST_CHAIN iptc_first_chain
67 #define TC_NEXT_CHAIN iptc_next_chain
68 #define TC_FIRST_RULE iptc_first_rule
69 #define TC_NEXT_RULE iptc_next_rule
70 #define TC_GET_TARGET iptc_get_target
71 #define TC_BUILTIN iptc_builtin
72 #define TC_GET_POLICY iptc_get_policy
73 #define TC_INSERT_ENTRY iptc_insert_entry
74 #define TC_REPLACE_ENTRY iptc_replace_entry
75 #define TC_APPEND_ENTRY iptc_append_entry
76 #define TC_DELETE_ENTRY iptc_delete_entry
77 #define TC_DELETE_NUM_ENTRY iptc_delete_num_entry
78 #define TC_CHECK_PACKET iptc_check_packet
79 #define TC_FLUSH_ENTRIES iptc_flush_entries
80 #define TC_ZERO_ENTRIES iptc_zero_entries
81 #define TC_READ_COUNTER iptc_read_counter
82 #define TC_ZERO_COUNTER iptc_zero_counter
83 #define TC_SET_COUNTER iptc_set_counter
84 #define TC_CREATE_CHAIN iptc_create_chain
85 #define TC_GET_REFERENCES iptc_get_references
86 #define TC_DELETE_CHAIN iptc_delete_chain
87 #define TC_RENAME_CHAIN iptc_rename_chain
88 #define TC_SET_POLICY iptc_set_policy
89 #define TC_GET_RAW_SOCKET iptc_get_raw_socket
90 #define TC_INIT iptc_init
91 #define TC_FREE iptc_free
92 #define TC_COMMIT iptc_commit
93 #define TC_STRERROR iptc_strerror
94 #define TC_NUM_RULES iptc_num_rules
95 #define TC_GET_RULE iptc_get_rule
96
97 #define TC_AF AF_INET
98 #define TC_IPPROTO IPPROTO_IP
99
100 #define SO_SET_REPLACE IPT_SO_SET_REPLACE
101 #define SO_SET_ADD_COUNTERS IPT_SO_SET_ADD_COUNTERS
102 #define SO_GET_INFO IPT_SO_GET_INFO
103 #define SO_GET_ENTRIES IPT_SO_GET_ENTRIES
104 #define SO_GET_VERSION IPT_SO_GET_VERSION
105
106 #define STANDARD_TARGET IPT_STANDARD_TARGET
107 #define LABEL_RETURN IPTC_LABEL_RETURN
108 #define LABEL_ACCEPT IPTC_LABEL_ACCEPT
109 #define LABEL_DROP IPTC_LABEL_DROP
110 #define LABEL_QUEUE IPTC_LABEL_QUEUE
111
112 #define ALIGN IPT_ALIGN
113 #define RETURN IPT_RETURN
114
115 #include "libiptc.c"
116
117 #define IP_PARTS_NATIVE(n) \
118 (unsigned int)((n)>>24)&0xFF, \
119 (unsigned int)((n)>>16)&0xFF, \
120 (unsigned int)((n)>>8)&0xFF, \
121 (unsigned int)((n)&0xFF)
122
123 #define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n))
124
125 int
dump_entry(STRUCT_ENTRY * e,const TC_HANDLE_T handle)126 dump_entry(STRUCT_ENTRY *e, const TC_HANDLE_T handle)
127 {
128 size_t i;
129 STRUCT_ENTRY_TARGET *t;
130
131 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
132 iptcb_entry2offset(handle, e));
133 printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
134 IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr));
135 printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
136 IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr));
137 printf("Interface: `%s'/", e->ip.iniface);
138 for (i = 0; i < IFNAMSIZ; i++)
139 printf("%c", e->ip.iniface_mask[i] ? 'X' : '.');
140 printf("to `%s'/", e->ip.outiface);
141 for (i = 0; i < IFNAMSIZ; i++)
142 printf("%c", e->ip.outiface_mask[i] ? 'X' : '.');
143 printf("\nProtocol: %u\n", e->ip.proto);
144 printf("Flags: %02X\n", e->ip.flags);
145 printf("Invflags: %02X\n", e->ip.invflags);
146 printf("Counters: %llu packets, %llu bytes\n",
147 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
148 printf("Cache: %08X ", e->nfcache);
149 if (e->nfcache & NFC_ALTERED) printf("ALTERED ");
150 if (e->nfcache & NFC_UNKNOWN) printf("UNKNOWN ");
151 printf("\n");
152
153 IPT_MATCH_ITERATE(e, print_match);
154
155 t = GET_TARGET(e);
156 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
157 if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) {
158 int pos = *(int *)t->data;
159 if (pos < 0)
160 printf("verdict=%s\n",
161 pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
162 : pos == -NF_DROP-1 ? "NF_DROP"
163 : pos == -NF_QUEUE-1 ? "NF_QUEUE"
164 : pos == RETURN ? "RETURN"
165 : "UNKNOWN");
166 else
167 printf("verdict=%u\n", pos);
168 } else if (strcmp(t->u.user.name, IPT_ERROR_TARGET) == 0)
169 printf("error=`%s'\n", t->data);
170
171 printf("\n");
172 return 0;
173 }
174
175 static unsigned char *
is_same(const STRUCT_ENTRY * a,const STRUCT_ENTRY * b,unsigned char * matchmask)176 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask)
177 {
178 unsigned int i;
179 unsigned char *mptr;
180
181 /* Always compare head structures: ignore mask here. */
182 if (a->ip.src.s_addr != b->ip.src.s_addr
183 || a->ip.dst.s_addr != b->ip.dst.s_addr
184 || a->ip.smsk.s_addr != b->ip.smsk.s_addr
185 || a->ip.dmsk.s_addr != b->ip.dmsk.s_addr
186 || a->ip.proto != b->ip.proto
187 || a->ip.flags != b->ip.flags
188 || a->ip.invflags != b->ip.invflags)
189 return NULL;
190
191 for (i = 0; i < IFNAMSIZ; i++) {
192 if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i])
193 return NULL;
194 if ((a->ip.iniface[i] & a->ip.iniface_mask[i])
195 != (b->ip.iniface[i] & b->ip.iniface_mask[i]))
196 return NULL;
197 if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i])
198 return NULL;
199 if ((a->ip.outiface[i] & a->ip.outiface_mask[i])
200 != (b->ip.outiface[i] & b->ip.outiface_mask[i]))
201 return NULL;
202 }
203
204 if (a->nfcache != b->nfcache
205 || a->target_offset != b->target_offset
206 || a->next_offset != b->next_offset)
207 return NULL;
208
209 mptr = matchmask + sizeof(STRUCT_ENTRY);
210 if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
211 return NULL;
212 mptr += IPT_ALIGN(sizeof(struct ipt_entry_target));
213
214 return mptr;
215 }
216
217 #if 0
218 /***************************** DEBUGGING ********************************/
219 static inline int
220 unconditional(const struct ipt_ip *ip)
221 {
222 unsigned int i;
223
224 for (i = 0; i < sizeof(*ip)/sizeof(u_int32_t); i++)
225 if (((u_int32_t *)ip)[i])
226 return 0;
227
228 return 1;
229 }
230
231 static inline int
232 check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off)
233 {
234 assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH));
235 assert(ALIGN(m->u.match_size) == m->u.match_size);
236
237 (*off) += m->u.match_size;
238 return 0;
239 }
240
241 static inline int
242 check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off,
243 unsigned int user_offset, int *was_return,
244 TC_HANDLE_T h)
245 {
246 unsigned int toff;
247 STRUCT_STANDARD_TARGET *t;
248
249 assert(e->target_offset >= sizeof(STRUCT_ENTRY));
250 assert(e->next_offset >= e->target_offset
251 + sizeof(STRUCT_ENTRY_TARGET));
252 toff = sizeof(STRUCT_ENTRY);
253 IPT_MATCH_ITERATE(e, check_match, &toff);
254
255 assert(toff == e->target_offset);
256
257 t = (STRUCT_STANDARD_TARGET *)
258 GET_TARGET((STRUCT_ENTRY *)e);
259 /* next_offset will have to be multiple of entry alignment. */
260 assert(e->next_offset == ALIGN(e->next_offset));
261 assert(e->target_offset == ALIGN(e->target_offset));
262 assert(t->target.u.target_size == ALIGN(t->target.u.target_size));
263 assert(!TC_IS_CHAIN(t->target.u.user.name, h));
264
265 if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) {
266 assert(t->target.u.target_size
267 == ALIGN(sizeof(STRUCT_STANDARD_TARGET)));
268
269 assert(t->verdict == -NF_DROP-1
270 || t->verdict == -NF_ACCEPT-1
271 || t->verdict == RETURN
272 || t->verdict < (int)h->entries->size);
273
274 if (t->verdict >= 0) {
275 STRUCT_ENTRY *te = get_entry(h, t->verdict);
276 int idx;
277
278 idx = iptcb_entry2index(h, te);
279 assert(strcmp(GET_TARGET(te)->u.user.name,
280 IPT_ERROR_TARGET)
281 != 0);
282 assert(te != e);
283
284 /* Prior node must be error node, or this node. */
285 assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset
286 || strcmp(GET_TARGET(index2entry(h, idx-1))
287 ->u.user.name, IPT_ERROR_TARGET)
288 == 0);
289 }
290
291 if (t->verdict == RETURN
292 && unconditional(&e->ip)
293 && e->target_offset == sizeof(*e))
294 *was_return = 1;
295 else
296 *was_return = 0;
297 } else if (strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0) {
298 assert(t->target.u.target_size
299 == ALIGN(sizeof(struct ipt_error_target)));
300
301 /* If this is in user area, previous must have been return */
302 if (*off > user_offset)
303 assert(*was_return);
304
305 *was_return = 0;
306 }
307 else *was_return = 0;
308
309 if (*off == user_offset)
310 assert(strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0);
311
312 (*off) += e->next_offset;
313 (*i)++;
314 return 0;
315 }
316
317 #ifdef IPTC_DEBUG
318 /* Do every conceivable sanity check on the handle */
319 static void
320 do_check(TC_HANDLE_T h, unsigned int line)
321 {
322 unsigned int i, n;
323 unsigned int user_offset; /* Offset of first user chain */
324 int was_return;
325
326 assert(h->changed == 0 || h->changed == 1);
327 if (strcmp(h->info.name, "filter") == 0) {
328 assert(h->info.valid_hooks
329 == (1 << NF_IP_LOCAL_IN
330 | 1 << NF_IP_FORWARD
331 | 1 << NF_IP_LOCAL_OUT));
332
333 /* Hooks should be first three */
334 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0);
335
336 n = get_chain_end(h, 0);
337 n += get_entry(h, n)->next_offset;
338 assert(h->info.hook_entry[NF_IP_FORWARD] == n);
339
340 n = get_chain_end(h, n);
341 n += get_entry(h, n)->next_offset;
342 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
343
344 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
345 } else if (strcmp(h->info.name, "nat") == 0) {
346 assert((h->info.valid_hooks
347 == (1 << NF_IP_PRE_ROUTING
348 | 1 << NF_IP_POST_ROUTING
349 | 1 << NF_IP_LOCAL_OUT)) ||
350 (h->info.valid_hooks
351 == (1 << NF_IP_PRE_ROUTING
352 | 1 << NF_IP_LOCAL_IN
353 | 1 << NF_IP_POST_ROUTING
354 | 1 << NF_IP_LOCAL_OUT)));
355
356 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
357
358 n = get_chain_end(h, 0);
359
360 n += get_entry(h, n)->next_offset;
361 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
362 n = get_chain_end(h, n);
363
364 n += get_entry(h, n)->next_offset;
365 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
366 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
367
368 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
369 n = get_chain_end(h, n);
370 n += get_entry(h, n)->next_offset;
371 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
372 user_offset = h->info.hook_entry[NF_IP_LOCAL_IN];
373 }
374
375 } else if (strcmp(h->info.name, "mangle") == 0) {
376 /* This code is getting ugly because linux < 2.4.18-pre6 had
377 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
378 * */
379 assert((h->info.valid_hooks
380 == (1 << NF_IP_PRE_ROUTING
381 | 1 << NF_IP_LOCAL_OUT)) ||
382 (h->info.valid_hooks
383 == (1 << NF_IP_PRE_ROUTING
384 | 1 << NF_IP_LOCAL_IN
385 | 1 << NF_IP_FORWARD
386 | 1 << NF_IP_LOCAL_OUT
387 | 1 << NF_IP_POST_ROUTING)));
388
389 /* Hooks should be first five */
390 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
391
392 n = get_chain_end(h, 0);
393
394 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
395 n += get_entry(h, n)->next_offset;
396 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
397 n = get_chain_end(h, n);
398 }
399
400 if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) {
401 n += get_entry(h, n)->next_offset;
402 assert(h->info.hook_entry[NF_IP_FORWARD] == n);
403 n = get_chain_end(h, n);
404 }
405
406 n += get_entry(h, n)->next_offset;
407 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
408 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
409
410 if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) {
411 n = get_chain_end(h, n);
412 n += get_entry(h, n)->next_offset;
413 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
414 user_offset = h->info.hook_entry[NF_IP_POST_ROUTING];
415 }
416 } else if (strcmp(h->info.name, "raw") == 0) {
417 assert(h->info.valid_hooks
418 == (1 << NF_IP_PRE_ROUTING
419 | 1 << NF_IP_LOCAL_OUT));
420
421 /* Hooks should be first three */
422 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
423
424 n = get_chain_end(h, n);
425 n += get_entry(h, n)->next_offset;
426 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
427
428 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
429
430 #ifdef NF_IP_DROPPING
431 } else if (strcmp(h->info.name, "drop") == 0) {
432 assert(h->info.valid_hooks == (1 << NF_IP_DROPPING));
433
434 /* Hook should be first */
435 assert(h->info.hook_entry[NF_IP_DROPPING] == 0);
436 user_offset = 0;
437 #endif
438 } else {
439 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
440 abort();
441 }
442
443 /* User chain == end of last builtin + policy entry */
444 user_offset = get_chain_end(h, user_offset);
445 user_offset += get_entry(h, user_offset)->next_offset;
446
447 /* Overflows should be end of entry chains, and unconditional
448 policy nodes. */
449 for (i = 0; i < NUMHOOKS; i++) {
450 STRUCT_ENTRY *e;
451 STRUCT_STANDARD_TARGET *t;
452
453 if (!(h->info.valid_hooks & (1 << i)))
454 continue;
455 assert(h->info.underflow[i]
456 == get_chain_end(h, h->info.hook_entry[i]));
457
458 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
459 assert(unconditional(&e->ip));
460 assert(e->target_offset == sizeof(*e));
461 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
462 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
463 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
464
465 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
466 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
467
468 /* Hooks and underflows must be valid entries */
469 entry2index(h, get_entry(h, h->info.hook_entry[i]));
470 entry2index(h, get_entry(h, h->info.underflow[i]));
471 }
472
473 assert(h->info.size
474 >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
475 +sizeof(STRUCT_STANDARD_TARGET)));
476
477 assert(h->entries.size
478 >= (h->new_number
479 * (sizeof(STRUCT_ENTRY)
480 + sizeof(STRUCT_STANDARD_TARGET))));
481 assert(strcmp(h->info.name, h->entries.name) == 0);
482
483 i = 0; n = 0;
484 was_return = 0;
485 /* Check all the entries. */
486 ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
487 check_entry, &i, &n, user_offset, &was_return, h);
488
489 assert(i == h->new_number);
490 assert(n == h->entries.size);
491
492 /* Final entry must be error node */
493 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
494 ->u.user.name,
495 ERROR_TARGET) == 0);
496 }
497 #endif /*IPTC_DEBUG*/
498
499 #endif
500