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
21 #ifdef DEBUG_CONNTRACK
22 #define inline
23 #endif
24
25 #if !defined(__ANDROID__) && (!defined(__GLIBC__) || (__GLIBC__ < 2))
26 typedef unsigned int socklen_t;
27 #endif
28
29 #include "libiptc/libiptc.h"
30
31 #define IP_VERSION 4
32 #define IP_OFFSET 0x1FFF
33
34 #define HOOK_PRE_ROUTING NF_IP_PRE_ROUTING
35 #define HOOK_LOCAL_IN NF_IP_LOCAL_IN
36 #define HOOK_FORWARD NF_IP_FORWARD
37 #define HOOK_LOCAL_OUT NF_IP_LOCAL_OUT
38 #define HOOK_POST_ROUTING NF_IP_POST_ROUTING
39
40 #define STRUCT_ENTRY_TARGET struct xt_entry_target
41 #define STRUCT_ENTRY struct ipt_entry
42 #define STRUCT_ENTRY_MATCH struct xt_entry_match
43 #define STRUCT_GETINFO struct ipt_getinfo
44 #define STRUCT_GET_ENTRIES struct ipt_get_entries
45 #define STRUCT_COUNTERS struct xt_counters
46 #define STRUCT_COUNTERS_INFO struct xt_counters_info
47 #define STRUCT_STANDARD_TARGET struct xt_standard_target
48 #define STRUCT_REPLACE struct ipt_replace
49
50 #define ENTRY_ITERATE IPT_ENTRY_ITERATE
51 #define TABLE_MAXNAMELEN XT_TABLE_MAXNAMELEN
52 #define FUNCTION_MAXNAMELEN XT_FUNCTION_MAXNAMELEN
53
54 #define GET_TARGET ipt_get_target
55
56 #define ERROR_TARGET XT_ERROR_TARGET
57 #define NUMHOOKS NF_IP_NUMHOOKS
58
59 #define IPT_CHAINLABEL xt_chainlabel
60
61 #define TC_DUMP_ENTRIES dump_entries
62 #define TC_IS_CHAIN iptc_is_chain
63 #define TC_FIRST_CHAIN iptc_first_chain
64 #define TC_NEXT_CHAIN iptc_next_chain
65 #define TC_FIRST_RULE iptc_first_rule
66 #define TC_NEXT_RULE iptc_next_rule
67 #define TC_GET_TARGET iptc_get_target
68 #define TC_BUILTIN iptc_builtin
69 #define TC_GET_POLICY iptc_get_policy
70 #define TC_INSERT_ENTRY iptc_insert_entry
71 #define TC_REPLACE_ENTRY iptc_replace_entry
72 #define TC_APPEND_ENTRY iptc_append_entry
73 #define TC_CHECK_ENTRY iptc_check_entry
74 #define TC_DELETE_ENTRY iptc_delete_entry
75 #define TC_DELETE_NUM_ENTRY iptc_delete_num_entry
76 #define TC_FLUSH_ENTRIES iptc_flush_entries
77 #define TC_ZERO_ENTRIES iptc_zero_entries
78 #define TC_READ_COUNTER iptc_read_counter
79 #define TC_ZERO_COUNTER iptc_zero_counter
80 #define TC_SET_COUNTER iptc_set_counter
81 #define TC_CREATE_CHAIN iptc_create_chain
82 #define TC_GET_REFERENCES iptc_get_references
83 #define TC_DELETE_CHAIN iptc_delete_chain
84 #define TC_RENAME_CHAIN iptc_rename_chain
85 #define TC_SET_POLICY iptc_set_policy
86 #define TC_GET_RAW_SOCKET iptc_get_raw_socket
87 #define TC_INIT iptc_init
88 #define TC_FREE iptc_free
89 #define TC_COMMIT iptc_commit
90 #define TC_STRERROR iptc_strerror
91 #define TC_NUM_RULES iptc_num_rules
92 #define TC_GET_RULE iptc_get_rule
93 #define TC_OPS iptc_ops
94
95 #define TC_AF AF_INET
96 #define TC_IPPROTO IPPROTO_IP
97
98 #define SO_SET_REPLACE IPT_SO_SET_REPLACE
99 #define SO_SET_ADD_COUNTERS IPT_SO_SET_ADD_COUNTERS
100 #define SO_GET_INFO IPT_SO_GET_INFO
101 #define SO_GET_ENTRIES IPT_SO_GET_ENTRIES
102 #define SO_GET_VERSION IPT_SO_GET_VERSION
103
104 #define STANDARD_TARGET XT_STANDARD_TARGET
105 #define LABEL_RETURN IPTC_LABEL_RETURN
106 #define LABEL_ACCEPT IPTC_LABEL_ACCEPT
107 #define LABEL_DROP IPTC_LABEL_DROP
108 #define LABEL_QUEUE IPTC_LABEL_QUEUE
109
110 #define ALIGN XT_ALIGN
111 #define RETURN XT_RETURN
112
113 #include "libiptc.c"
114
115 #define IP_PARTS_NATIVE(n) \
116 (unsigned int)((n)>>24)&0xFF, \
117 (unsigned int)((n)>>16)&0xFF, \
118 (unsigned int)((n)>>8)&0xFF, \
119 (unsigned int)((n)&0xFF)
120
121 #define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n))
122
123 static int
dump_entry(struct ipt_entry * e,struct xtc_handle * const handle)124 dump_entry(struct ipt_entry *e, struct xtc_handle *const handle)
125 {
126 size_t i;
127 STRUCT_ENTRY_TARGET *t;
128
129 printf("Entry %u (%lu):\n", iptcb_entry2index(handle, e),
130 iptcb_entry2offset(handle, e));
131 printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
132 IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr));
133 printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
134 IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr));
135 printf("Interface: `%s'/", e->ip.iniface);
136 for (i = 0; i < IFNAMSIZ; i++)
137 printf("%c", e->ip.iniface_mask[i] ? 'X' : '.');
138 printf("to `%s'/", e->ip.outiface);
139 for (i = 0; i < IFNAMSIZ; i++)
140 printf("%c", e->ip.outiface_mask[i] ? 'X' : '.');
141 printf("\nProtocol: %u\n", e->ip.proto);
142 printf("Flags: %02X\n", e->ip.flags);
143 printf("Invflags: %02X\n", e->ip.invflags);
144 printf("Counters: %llu packets, %llu bytes\n",
145 (unsigned long long)e->counters.pcnt, (unsigned long long)e->counters.bcnt);
146 printf("Cache: %08X\n", e->nfcache);
147
148 IPT_MATCH_ITERATE(e, print_match);
149
150 t = GET_TARGET(e);
151 printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
152 if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) {
153 const unsigned char *data = t->data;
154 int pos = *(const int *)data;
155 if (pos < 0)
156 printf("verdict=%s\n",
157 pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
158 : pos == -NF_DROP-1 ? "NF_DROP"
159 : pos == -NF_QUEUE-1 ? "NF_QUEUE"
160 : pos == RETURN ? "RETURN"
161 : "UNKNOWN");
162 else
163 printf("verdict=%u\n", pos);
164 } else if (strcmp(t->u.user.name, XT_ERROR_TARGET) == 0)
165 printf("error=`%s'\n", t->data);
166
167 printf("\n");
168 return 0;
169 }
170
171 static unsigned char *
is_same(const STRUCT_ENTRY * a,const STRUCT_ENTRY * b,unsigned char * matchmask)172 is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask)
173 {
174 unsigned int i;
175 unsigned char *mptr;
176
177 /* Always compare head structures: ignore mask here. */
178 if (a->ip.src.s_addr != b->ip.src.s_addr
179 || a->ip.dst.s_addr != b->ip.dst.s_addr
180 || a->ip.smsk.s_addr != b->ip.smsk.s_addr
181 || a->ip.dmsk.s_addr != b->ip.dmsk.s_addr
182 || a->ip.proto != b->ip.proto
183 || a->ip.flags != b->ip.flags
184 || a->ip.invflags != b->ip.invflags)
185 return NULL;
186
187 for (i = 0; i < IFNAMSIZ; i++) {
188 if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i])
189 return NULL;
190 if ((a->ip.iniface[i] & a->ip.iniface_mask[i])
191 != (b->ip.iniface[i] & b->ip.iniface_mask[i]))
192 return NULL;
193 if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i])
194 return NULL;
195 if ((a->ip.outiface[i] & a->ip.outiface_mask[i])
196 != (b->ip.outiface[i] & b->ip.outiface_mask[i]))
197 return NULL;
198 }
199
200 if (a->target_offset != b->target_offset
201 || a->next_offset != b->next_offset)
202 return NULL;
203
204 mptr = matchmask + sizeof(STRUCT_ENTRY);
205 if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
206 return NULL;
207 mptr += XT_ALIGN(sizeof(struct xt_entry_target));
208
209 return mptr;
210 }
211
212 #if 0
213 /***************************** DEBUGGING ********************************/
214 static inline int
215 unconditional(const struct ipt_ip *ip)
216 {
217 unsigned int i;
218
219 for (i = 0; i < sizeof(*ip)/sizeof(uint32_t); i++)
220 if (((uint32_t *)ip)[i])
221 return 0;
222
223 return 1;
224 }
225
226 static inline int
227 check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off)
228 {
229 assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH));
230 assert(ALIGN(m->u.match_size) == m->u.match_size);
231
232 (*off) += m->u.match_size;
233 return 0;
234 }
235
236 static inline int
237 check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off,
238 unsigned int user_offset, int *was_return,
239 struct xtc_handle *h)
240 {
241 unsigned int toff;
242 STRUCT_STANDARD_TARGET *t;
243
244 assert(e->target_offset >= sizeof(STRUCT_ENTRY));
245 assert(e->next_offset >= e->target_offset
246 + sizeof(STRUCT_ENTRY_TARGET));
247 toff = sizeof(STRUCT_ENTRY);
248 IPT_MATCH_ITERATE(e, check_match, &toff);
249
250 assert(toff == e->target_offset);
251
252 t = (STRUCT_STANDARD_TARGET *)
253 GET_TARGET((STRUCT_ENTRY *)e);
254 /* next_offset will have to be multiple of entry alignment. */
255 assert(e->next_offset == ALIGN(e->next_offset));
256 assert(e->target_offset == ALIGN(e->target_offset));
257 assert(t->target.u.target_size == ALIGN(t->target.u.target_size));
258 assert(!TC_IS_CHAIN(t->target.u.user.name, h));
259
260 if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) {
261 assert(t->target.u.target_size
262 == ALIGN(sizeof(STRUCT_STANDARD_TARGET)));
263
264 assert(t->verdict == -NF_DROP-1
265 || t->verdict == -NF_ACCEPT-1
266 || t->verdict == RETURN
267 || t->verdict < (int)h->entries->size);
268
269 if (t->verdict >= 0) {
270 STRUCT_ENTRY *te = get_entry(h, t->verdict);
271 int idx;
272
273 idx = iptcb_entry2index(h, te);
274 assert(strcmp(GET_TARGET(te)->u.user.name,
275 XT_ERROR_TARGET)
276 != 0);
277 assert(te != e);
278
279 /* Prior node must be error node, or this node. */
280 assert(t->verdict == iptcb_entry2offset(h, e)+e->next_offset
281 || strcmp(GET_TARGET(index2entry(h, idx-1))
282 ->u.user.name, XT_ERROR_TARGET)
283 == 0);
284 }
285
286 if (t->verdict == RETURN
287 && unconditional(&e->ip)
288 && e->target_offset == sizeof(*e))
289 *was_return = 1;
290 else
291 *was_return = 0;
292 } else if (strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0) {
293 assert(t->target.u.target_size
294 == ALIGN(sizeof(struct ipt_error_target)));
295
296 /* If this is in user area, previous must have been return */
297 if (*off > user_offset)
298 assert(*was_return);
299
300 *was_return = 0;
301 }
302 else *was_return = 0;
303
304 if (*off == user_offset)
305 assert(strcmp(t->target.u.user.name, XT_ERROR_TARGET) == 0);
306
307 (*off) += e->next_offset;
308 (*i)++;
309 return 0;
310 }
311
312 #ifdef IPTC_DEBUG
313 /* Do every conceivable sanity check on the handle */
314 static void
315 do_check(struct xtc_handle *h, unsigned int line)
316 {
317 unsigned int i, n;
318 unsigned int user_offset; /* Offset of first user chain */
319 int was_return;
320
321 assert(h->changed == 0 || h->changed == 1);
322 if (strcmp(h->info.name, "filter") == 0) {
323 assert(h->info.valid_hooks
324 == (1 << NF_IP_LOCAL_IN
325 | 1 << NF_IP_FORWARD
326 | 1 << NF_IP_LOCAL_OUT));
327
328 /* Hooks should be first three */
329 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0);
330
331 n = get_chain_end(h, 0);
332 n += get_entry(h, n)->next_offset;
333 assert(h->info.hook_entry[NF_IP_FORWARD] == n);
334
335 n = get_chain_end(h, n);
336 n += get_entry(h, n)->next_offset;
337 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
338
339 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
340 } else if (strcmp(h->info.name, "nat") == 0) {
341 assert((h->info.valid_hooks
342 == (1 << NF_IP_PRE_ROUTING
343 | 1 << NF_IP_POST_ROUTING
344 | 1 << NF_IP_LOCAL_OUT)) ||
345 (h->info.valid_hooks
346 == (1 << NF_IP_PRE_ROUTING
347 | 1 << NF_IP_LOCAL_IN
348 | 1 << NF_IP_POST_ROUTING
349 | 1 << NF_IP_LOCAL_OUT)));
350
351 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
352
353 n = get_chain_end(h, 0);
354
355 n += get_entry(h, n)->next_offset;
356 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
357 n = get_chain_end(h, n);
358
359 n += get_entry(h, n)->next_offset;
360 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
361 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
362
363 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
364 n = get_chain_end(h, n);
365 n += get_entry(h, n)->next_offset;
366 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
367 user_offset = h->info.hook_entry[NF_IP_LOCAL_IN];
368 }
369
370 } else if (strcmp(h->info.name, "mangle") == 0) {
371 /* This code is getting ugly because linux < 2.4.18-pre6 had
372 * two mangle hooks, linux >= 2.4.18-pre6 has five mangle hooks
373 * */
374 assert((h->info.valid_hooks
375 == (1 << NF_IP_PRE_ROUTING
376 | 1 << NF_IP_LOCAL_OUT)) ||
377 (h->info.valid_hooks
378 == (1 << NF_IP_PRE_ROUTING
379 | 1 << NF_IP_LOCAL_IN
380 | 1 << NF_IP_FORWARD
381 | 1 << NF_IP_LOCAL_OUT
382 | 1 << NF_IP_POST_ROUTING)));
383
384 /* Hooks should be first five */
385 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
386
387 n = get_chain_end(h, 0);
388
389 if (h->info.valid_hooks & (1 << NF_IP_LOCAL_IN)) {
390 n += get_entry(h, n)->next_offset;
391 assert(h->info.hook_entry[NF_IP_LOCAL_IN] == n);
392 n = get_chain_end(h, n);
393 }
394
395 if (h->info.valid_hooks & (1 << NF_IP_FORWARD)) {
396 n += get_entry(h, n)->next_offset;
397 assert(h->info.hook_entry[NF_IP_FORWARD] == n);
398 n = get_chain_end(h, n);
399 }
400
401 n += get_entry(h, n)->next_offset;
402 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
403 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
404
405 if (h->info.valid_hooks & (1 << NF_IP_POST_ROUTING)) {
406 n = get_chain_end(h, n);
407 n += get_entry(h, n)->next_offset;
408 assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
409 user_offset = h->info.hook_entry[NF_IP_POST_ROUTING];
410 }
411 } else if (strcmp(h->info.name, "raw") == 0) {
412 assert(h->info.valid_hooks
413 == (1 << NF_IP_PRE_ROUTING
414 | 1 << NF_IP_LOCAL_OUT));
415
416 /* Hooks should be first three */
417 assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
418
419 n = get_chain_end(h, n);
420 n += get_entry(h, n)->next_offset;
421 assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
422
423 user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
424 } else {
425 fprintf(stderr, "Unknown table `%s'\n", h->info.name);
426 abort();
427 }
428
429 /* User chain == end of last builtin + policy entry */
430 user_offset = get_chain_end(h, user_offset);
431 user_offset += get_entry(h, user_offset)->next_offset;
432
433 /* Overflows should be end of entry chains, and unconditional
434 policy nodes. */
435 for (i = 0; i < NUMHOOKS; i++) {
436 STRUCT_ENTRY *e;
437 STRUCT_STANDARD_TARGET *t;
438
439 if (!(h->info.valid_hooks & (1 << i)))
440 continue;
441 assert(h->info.underflow[i]
442 == get_chain_end(h, h->info.hook_entry[i]));
443
444 e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
445 assert(unconditional(&e->ip));
446 assert(e->target_offset == sizeof(*e));
447 t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
448 assert(t->target.u.target_size == ALIGN(sizeof(*t)));
449 assert(e->next_offset == sizeof(*e) + ALIGN(sizeof(*t)));
450
451 assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
452 assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
453
454 /* Hooks and underflows must be valid entries */
455 entry2index(h, get_entry(h, h->info.hook_entry[i]));
456 entry2index(h, get_entry(h, h->info.underflow[i]));
457 }
458
459 assert(h->info.size
460 >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
461 +sizeof(STRUCT_STANDARD_TARGET)));
462
463 assert(h->entries.size
464 >= (h->new_number
465 * (sizeof(STRUCT_ENTRY)
466 + sizeof(STRUCT_STANDARD_TARGET))));
467 assert(strcmp(h->info.name, h->entries.name) == 0);
468
469 i = 0; n = 0;
470 was_return = 0;
471 /* Check all the entries. */
472 ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
473 check_entry, &i, &n, user_offset, &was_return, h);
474
475 assert(i == h->new_number);
476 assert(n == h->entries.size);
477
478 /* Final entry must be error node */
479 assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
480 ->u.user.name,
481 ERROR_TARGET) == 0);
482 }
483 #endif /*IPTC_DEBUG*/
484
485 #endif
486