libip4tc.c revision 10758b743d6aa076ebe2c3e8f855e73826841e71 
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
20#ifdef DEBUG_CONNTRACK
21#define inline
22#endif
23
24#if !defined(__GLIBC__) || (__GLIBC__ < 2)
25typedef unsigned int socklen_t;
26#endif
27
28#include "libiptc/libiptc.h"
29
30#define IP_VERSION	4
31#define IP_OFFSET	0x1FFF
32
33#define HOOK_PRE_ROUTING	NF_IP_PRE_ROUTING
34#define HOOK_LOCAL_IN		NF_IP_LOCAL_IN
35#define HOOK_FORWARD		NF_IP_FORWARD
36#define HOOK_LOCAL_OUT		NF_IP_LOCAL_OUT
37#define HOOK_POST_ROUTING	NF_IP_POST_ROUTING
38#ifdef NF_IP_DROPPING
39#define HOOK_DROPPING		NF_IP_DROPPING
40#endif
41
42#define STRUCT_ENTRY_TARGET	struct ipt_entry_target
43#define STRUCT_ENTRY		struct ipt_entry
44#define STRUCT_ENTRY_MATCH	struct ipt_entry_match
45#define STRUCT_GETINFO		struct ipt_getinfo
46#define STRUCT_GET_ENTRIES	struct ipt_get_entries
47#define STRUCT_COUNTERS		struct ipt_counters
48#define STRUCT_COUNTERS_INFO	struct ipt_counters_info
49#define STRUCT_STANDARD_TARGET	struct ipt_standard_target
50#define STRUCT_REPLACE		struct ipt_replace
51
52#define STRUCT_TC_HANDLE	struct iptc_handle
53#define TC_HANDLE_T		iptc_handle_t
54
55#define ENTRY_ITERATE		IPT_ENTRY_ITERATE
56#define TABLE_MAXNAMELEN	IPT_TABLE_MAXNAMELEN
57#define FUNCTION_MAXNAMELEN	IPT_FUNCTION_MAXNAMELEN
58
59#define GET_TARGET		ipt_get_target
60
61#define ERROR_TARGET		IPT_ERROR_TARGET
62#define NUMHOOKS		NF_IP_NUMHOOKS
63
64#define IPT_CHAINLABEL		ipt_chainlabel
65
66#define TC_DUMP_ENTRIES		dump_entries
67#define TC_IS_CHAIN		iptc_is_chain
68#define TC_FIRST_CHAIN		iptc_first_chain
69#define TC_NEXT_CHAIN		iptc_next_chain
70#define TC_FIRST_RULE		iptc_first_rule
71#define TC_NEXT_RULE		iptc_next_rule
72#define TC_GET_TARGET		iptc_get_target
73#define TC_BUILTIN		iptc_builtin
74#define TC_GET_POLICY		iptc_get_policy
75#define TC_INSERT_ENTRY		iptc_insert_entry
76#define TC_REPLACE_ENTRY	iptc_replace_entry
77#define TC_APPEND_ENTRY		iptc_append_entry
78#define TC_DELETE_ENTRY		iptc_delete_entry
79#define TC_DELETE_NUM_ENTRY	iptc_delete_num_entry
80#define TC_CHECK_PACKET		iptc_check_packet
81#define TC_FLUSH_ENTRIES	iptc_flush_entries
82#define TC_ZERO_ENTRIES		iptc_zero_entries
83#define TC_CREATE_CHAIN		iptc_create_chain
84#define TC_GET_REFERENCES	iptc_get_references
85#define TC_DELETE_CHAIN		iptc_delete_chain
86#define TC_RENAME_CHAIN		iptc_rename_chain
87#define TC_SET_POLICY		iptc_set_policy
88#define TC_GET_RAW_SOCKET	iptc_get_raw_socket
89#define TC_INIT			iptc_init
90#define TC_COMMIT		iptc_commit
91#define TC_STRERROR		iptc_strerror
92
93#define TC_AF			AF_INET
94#define TC_IPPROTO		IPPROTO_IP
95
96#define SO_SET_REPLACE		IPT_SO_SET_REPLACE
97#define SO_SET_ADD_COUNTERS	IPT_SO_SET_ADD_COUNTERS
98#define SO_GET_INFO		IPT_SO_GET_INFO
99#define SO_GET_ENTRIES		IPT_SO_GET_ENTRIES
100#define SO_GET_VERSION		IPT_SO_GET_VERSION
101
102#define STANDARD_TARGET		IPT_STANDARD_TARGET
103#define LABEL_RETURN		IPTC_LABEL_RETURN
104#define LABEL_ACCEPT		IPTC_LABEL_ACCEPT
105#define LABEL_DROP		IPTC_LABEL_DROP
106#define LABEL_QUEUE		IPTC_LABEL_QUEUE
107
108#define ALIGN			IPT_ALIGN
109#define RETURN			IPT_RETURN
110
111#include "libiptc.c"
112
113#define IP_PARTS_NATIVE(n)			\
114(unsigned int)((n)>>24)&0xFF,			\
115(unsigned int)((n)>>16)&0xFF,			\
116(unsigned int)((n)>>8)&0xFF,			\
117(unsigned int)((n)&0xFF)
118
119#define IP_PARTS(n) IP_PARTS_NATIVE(ntohl(n))
120
121int
122dump_entry(STRUCT_ENTRY *e, const TC_HANDLE_T handle)
123{
124	size_t i;
125	STRUCT_ENTRY_TARGET *t;
126
127	printf("Entry %u (%lu):\n", entry2index(handle, e),
128	       entry2offset(handle, e));
129	printf("SRC IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
130	       IP_PARTS(e->ip.src.s_addr),IP_PARTS(e->ip.smsk.s_addr));
131	printf("DST IP: %u.%u.%u.%u/%u.%u.%u.%u\n",
132	       IP_PARTS(e->ip.dst.s_addr),IP_PARTS(e->ip.dmsk.s_addr));
133	printf("Interface: `%s'/", e->ip.iniface);
134	for (i = 0; i < IFNAMSIZ; i++)
135		printf("%c", e->ip.iniface_mask[i] ? 'X' : '.');
136	printf("to `%s'/", e->ip.outiface);
137	for (i = 0; i < IFNAMSIZ; i++)
138		printf("%c", e->ip.outiface_mask[i] ? 'X' : '.');
139	printf("\nProtocol: %u\n", e->ip.proto);
140	printf("Flags: %02X\n", e->ip.flags);
141	printf("Invflags: %02X\n", e->ip.invflags);
142	printf("Counters: %llu packets, %llu bytes\n",
143	       e->counters.pcnt, e->counters.bcnt);
144	printf("Cache: %08X ", e->nfcache);
145	if (e->nfcache & NFC_ALTERED) printf("ALTERED ");
146	if (e->nfcache & NFC_UNKNOWN) printf("UNKNOWN ");
147	if (e->nfcache & NFC_IP_SRC) printf("IP_SRC ");
148	if (e->nfcache & NFC_IP_DST) printf("IP_DST ");
149	if (e->nfcache & NFC_IP_IF_IN) printf("IP_IF_IN ");
150	if (e->nfcache & NFC_IP_IF_OUT) printf("IP_IF_OUT ");
151	if (e->nfcache & NFC_IP_TOS) printf("IP_TOS ");
152	if (e->nfcache & NFC_IP_PROTO) printf("IP_PROTO ");
153	if (e->nfcache & NFC_IP_OPTIONS) printf("IP_OPTIONS ");
154	if (e->nfcache & NFC_IP_TCPFLAGS) printf("IP_TCPFLAGS ");
155	if (e->nfcache & NFC_IP_SRC_PT) printf("IP_SRC_PT ");
156	if (e->nfcache & NFC_IP_DST_PT) printf("IP_DST_PT ");
157	if (e->nfcache & NFC_IP_PROTO_UNKNOWN) printf("IP_PROTO_UNKNOWN ");
158	printf("\n");
159
160	IPT_MATCH_ITERATE(e, print_match);
161
162	t = GET_TARGET(e);
163	printf("Target name: `%s' [%u]\n", t->u.user.name, t->u.target_size);
164	if (strcmp(t->u.user.name, STANDARD_TARGET) == 0) {
165		int pos = *(int *)t->data;
166		if (pos < 0)
167			printf("verdict=%s\n",
168			       pos == -NF_ACCEPT-1 ? "NF_ACCEPT"
169			       : pos == -NF_DROP-1 ? "NF_DROP"
170			       : pos == -NF_QUEUE-1 ? "NF_QUEUE"
171			       : pos == RETURN ? "RETURN"
172			       : "UNKNOWN");
173		else
174			printf("verdict=%u\n", pos);
175	} else if (strcmp(t->u.user.name, IPT_ERROR_TARGET) == 0)
176		printf("error=`%s'\n", t->data);
177
178	printf("\n");
179	return 0;
180}
181
182static int
183is_same(const STRUCT_ENTRY *a, const STRUCT_ENTRY *b, unsigned char *matchmask)
184{
185	unsigned int i;
186	STRUCT_ENTRY_TARGET *ta, *tb;
187	unsigned char *mptr;
188
189	/* Always compare head structures: ignore mask here. */
190	if (a->ip.src.s_addr != b->ip.src.s_addr
191	    || a->ip.dst.s_addr != b->ip.dst.s_addr
192	    || a->ip.smsk.s_addr != b->ip.smsk.s_addr
193	    || a->ip.smsk.s_addr != b->ip.smsk.s_addr
194	    || a->ip.proto != b->ip.proto
195	    || a->ip.flags != b->ip.flags
196	    || a->ip.invflags != b->ip.invflags)
197		return 0;
198
199	for (i = 0; i < IFNAMSIZ; i++) {
200		if (a->ip.iniface_mask[i] != b->ip.iniface_mask[i])
201			return 0;
202		if ((a->ip.iniface[i] & a->ip.iniface_mask[i])
203		    != (b->ip.iniface[i] & b->ip.iniface_mask[i]))
204			return 0;
205		if (a->ip.outiface_mask[i] != b->ip.outiface_mask[i])
206			return 0;
207		if ((a->ip.outiface[i] & a->ip.outiface_mask[i])
208		    != (b->ip.outiface[i] & b->ip.outiface_mask[i]))
209			return 0;
210	}
211
212	if (a->nfcache != b->nfcache
213	    || a->target_offset != b->target_offset
214	    || a->next_offset != b->next_offset)
215		return 0;
216
217	mptr = matchmask + sizeof(STRUCT_ENTRY);
218	if (IPT_MATCH_ITERATE(a, match_different, a->elems, b->elems, &mptr))
219		return 0;
220
221	ta = GET_TARGET((STRUCT_ENTRY *)a);
222	tb = GET_TARGET((STRUCT_ENTRY *)b);
223	if (ta->u.target_size != tb->u.target_size)
224		return 0;
225	if (strcmp(ta->u.user.name, tb->u.user.name) != 0)
226		return 0;
227
228	mptr += sizeof(*ta);
229	if (target_different(ta->data, tb->data,
230			     ta->u.target_size - sizeof(*ta), mptr))
231		return 0;
232
233   	return 1;
234}
235
236/***************************** DEBUGGING ********************************/
237static inline int
238unconditional(const struct ipt_ip *ip)
239{
240	unsigned int i;
241
242	for (i = 0; i < sizeof(*ip)/sizeof(u_int32_t); i++)
243		if (((u_int32_t *)ip)[i])
244			return 0;
245
246	return 1;
247}
248
249static inline int
250check_match(const STRUCT_ENTRY_MATCH *m, unsigned int *off)
251{
252	assert(m->u.match_size >= sizeof(STRUCT_ENTRY_MATCH));
253	assert(ALIGN(m->u.match_size) == m->u.match_size);
254
255	(*off) += m->u.match_size;
256	return 0;
257}
258
259static inline int
260check_entry(const STRUCT_ENTRY *e, unsigned int *i, unsigned int *off,
261	    unsigned int user_offset, int *was_return,
262	    TC_HANDLE_T h)
263{
264	unsigned int toff;
265	STRUCT_STANDARD_TARGET *t;
266
267	assert(e->target_offset >= sizeof(STRUCT_ENTRY));
268	assert(e->next_offset >= e->target_offset
269	       + sizeof(STRUCT_ENTRY_TARGET));
270	toff = sizeof(STRUCT_ENTRY);
271	IPT_MATCH_ITERATE(e, check_match, &toff);
272
273	assert(toff == e->target_offset);
274
275	t = (STRUCT_STANDARD_TARGET *)
276		GET_TARGET((STRUCT_ENTRY *)e);
277	/* next_offset will have to be multiple of entry alignment. */
278	assert(e->next_offset == ALIGN(e->next_offset));
279	assert(e->target_offset == ALIGN(e->target_offset));
280	assert(t->target.u.target_size == ALIGN(t->target.u.target_size));
281	assert(!TC_IS_CHAIN(t->target.u.user.name, h));
282
283	if (strcmp(t->target.u.user.name, STANDARD_TARGET) == 0) {
284		assert(t->target.u.target_size
285		       == ALIGN(sizeof(STRUCT_STANDARD_TARGET)));
286
287		assert(t->verdict == -NF_DROP-1
288		       || t->verdict == -NF_ACCEPT-1
289		       || t->verdict == RETURN
290		       || t->verdict < (int)h->entries.size);
291
292		if (t->verdict >= 0) {
293			STRUCT_ENTRY *te = get_entry(h, t->verdict);
294			int idx;
295
296			idx = entry2index(h, te);
297			assert(strcmp(GET_TARGET(te)->u.user.name,
298				      IPT_ERROR_TARGET)
299			       != 0);
300			assert(te != e);
301
302			/* Prior node must be error node, or this node. */
303			assert(t->verdict == entry2offset(h, e)+e->next_offset
304			       || strcmp(GET_TARGET(index2entry(h, idx-1))
305					 ->u.user.name, IPT_ERROR_TARGET)
306			       == 0);
307		}
308
309		if (t->verdict == RETURN
310		    && unconditional(&e->ip)
311		    && e->target_offset == sizeof(*e))
312			*was_return = 1;
313		else
314			*was_return = 0;
315	} else if (strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0) {
316		assert(t->target.u.target_size
317		       == ALIGN(sizeof(struct ipt_error_target)));
318
319		/* If this is in user area, previous must have been return */
320		if (*off > user_offset)
321			assert(*was_return);
322
323		*was_return = 0;
324	}
325	else *was_return = 0;
326
327	if (*off == user_offset)
328		assert(strcmp(t->target.u.user.name, IPT_ERROR_TARGET) == 0);
329
330	(*off) += e->next_offset;
331	(*i)++;
332	return 0;
333}
334
335#ifndef NDEBUG
336/* Do every conceivable sanity check on the handle */
337static void
338do_check(TC_HANDLE_T h, unsigned int line)
339{
340	unsigned int i, n;
341	unsigned int user_offset; /* Offset of first user chain */
342	int was_return;
343
344	assert(h->changed == 0 || h->changed == 1);
345	if (strcmp(h->info.name, "filter") == 0) {
346		assert(h->info.valid_hooks
347		       == (1 << NF_IP_LOCAL_IN
348			   | 1 << NF_IP_FORWARD
349			   | 1 << NF_IP_LOCAL_OUT));
350
351		/* Hooks should be first three */
352		assert(h->info.hook_entry[NF_IP_LOCAL_IN] == 0);
353
354		n = get_chain_end(h, 0);
355		n += get_entry(h, n)->next_offset;
356		assert(h->info.hook_entry[NF_IP_FORWARD] == n);
357
358		n = get_chain_end(h, n);
359		n += get_entry(h, n)->next_offset;
360		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
361
362		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
363	} else if (strcmp(h->info.name, "nat") == 0) {
364		assert(h->info.valid_hooks
365		       == (1 << NF_IP_PRE_ROUTING
366			   | 1 << NF_IP_POST_ROUTING
367			   | 1 << NF_IP_LOCAL_OUT));
368
369		assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
370
371		n = get_chain_end(h, 0);
372		n += get_entry(h, n)->next_offset;
373		assert(h->info.hook_entry[NF_IP_POST_ROUTING] == n);
374
375		n = get_chain_end(h, n);
376		n += get_entry(h, n)->next_offset;
377		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
378
379		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
380	} else if (strcmp(h->info.name, "mangle") == 0) {
381		assert(h->info.valid_hooks
382		       == (1 << NF_IP_PRE_ROUTING
383			   | 1 << NF_IP_LOCAL_OUT));
384
385		/* Hooks should be first three */
386		assert(h->info.hook_entry[NF_IP_PRE_ROUTING] == 0);
387
388		n = get_chain_end(h, 0);
389		n += get_entry(h, n)->next_offset;
390		assert(h->info.hook_entry[NF_IP_LOCAL_OUT] == n);
391
392		user_offset = h->info.hook_entry[NF_IP_LOCAL_OUT];
393	} else
394		abort();
395
396	/* User chain == end of last builtin + policy entry */
397	user_offset = get_chain_end(h, user_offset);
398	user_offset += get_entry(h, user_offset)->next_offset;
399
400	/* Overflows should be end of entry chains, and unconditional
401           policy nodes. */
402	for (i = 0; i < NUMHOOKS; i++) {
403		STRUCT_ENTRY *e;
404		STRUCT_STANDARD_TARGET *t;
405
406		if (!(h->info.valid_hooks & (1 << i)))
407			continue;
408		assert(h->info.underflow[i]
409		       == get_chain_end(h, h->info.hook_entry[i]));
410
411		e = get_entry(h, get_chain_end(h, h->info.hook_entry[i]));
412		assert(unconditional(&e->ip));
413		assert(e->target_offset == sizeof(*e));
414		t = (STRUCT_STANDARD_TARGET *)GET_TARGET(e);
415		assert(t->target.u.target_size == IPT_ALIGN(sizeof(*t)));
416		assert(e->next_offset == sizeof(*e) + IPT_ALIGN(sizeof(*t)));
417
418		assert(strcmp(t->target.u.user.name, STANDARD_TARGET)==0);
419		assert(t->verdict == -NF_DROP-1 || t->verdict == -NF_ACCEPT-1);
420
421		/* Hooks and underflows must be valid entries */
422		entry2index(h, get_entry(h, h->info.hook_entry[i]));
423		entry2index(h, get_entry(h, h->info.underflow[i]));
424	}
425
426	assert(h->info.size
427	       >= h->info.num_entries * (sizeof(STRUCT_ENTRY)
428					 +sizeof(STRUCT_STANDARD_TARGET)));
429
430	assert(h->entries.size
431	       >= (h->new_number
432		   * (sizeof(STRUCT_ENTRY)
433		      + sizeof(STRUCT_STANDARD_TARGET))));
434	assert(strcmp(h->info.name, h->entries.name) == 0);
435
436	i = 0; n = 0;
437	was_return = 0;
438	/* Check all the entries. */
439	ENTRY_ITERATE(h->entries.entrytable, h->entries.size,
440		      check_entry, &i, &n, user_offset, &was_return, h);
441
442	assert(i == h->new_number);
443	assert(n == h->entries.size);
444
445	/* Final entry must be error node */
446	assert(strcmp(GET_TARGET(index2entry(h, h->new_number-1))
447		      ->u.user.name,
448		      IPT_ERROR_TARGET) == 0);
449}
450#endif /*NDEBUG*/
451