libxt_conntrack.c revision a80b6046fa216c26dbc18d587f6255afa8444885 
1/* Shared library add-on to iptables for conntrack matching support.
2 * GPL (C) 2001  Marc Boucher (marc@mbsi.ca).
3 */
4
5#include <ctype.h>
6#include <getopt.h>
7#include <netdb.h>
8#include <stdio.h>
9#include <stdlib.h>
10#include <string.h>
11#include <iptables.h>
12#include <linux/netfilter.h>
13#include <linux/netfilter/xt_conntrack.h>
14#include <linux/netfilter/nf_conntrack_common.h>
15
16/* Function which prints out usage message. */
17static void conntrack_mt_help(void)
18{
19	printf(
20"conntrack match options:\n"
21"[!] --ctstate {INVALID|ESTABLISHED|NEW|RELATED|UNTRACKED|SNAT|DNAT}[,...]\n"
22"                               State(s) to match\n"
23"[!] --ctproto proto            Protocol to match; by number or name, e.g. \"tcp\"\n"
24"[!] --ctorigsrc address[/mask]\n"
25"[!] --ctorigdst address[/mask]\n"
26"[!] --ctreplsrc address[/mask]\n"
27"[!] --ctrepldst address[/mask]\n"
28"                               Original/Reply source/destination address\n"
29"[!] --ctstatus {NONE|EXPECTED|SEEN_REPLY|ASSURED|CONFIRMED}[,...]\n"
30"                               Status(es) to match\n"
31"[!] --ctexpire time[:time]     Match remaining lifetime in seconds against\n"
32"                               value or range of values (inclusive)\n"
33"\n");
34}
35
36static const struct option conntrack_mt_opts[] = {
37	{.name = "ctstate",   .has_arg = true, .val = '1'},
38	{.name = "ctproto",   .has_arg = true, .val = '2'},
39	{.name = "ctorigsrc", .has_arg = true, .val = '3'},
40	{.name = "ctorigdst", .has_arg = true, .val = '4'},
41	{.name = "ctreplsrc", .has_arg = true, .val = '5'},
42	{.name = "ctrepldst", .has_arg = true, .val = '6'},
43	{.name = "ctstatus",  .has_arg = true, .val = '7'},
44	{.name = "ctexpire",  .has_arg = true, .val = '8'},
45	{},
46};
47
48static int
49parse_state(const char *state, size_t strlen, struct xt_conntrack_info *sinfo)
50{
51	if (strncasecmp(state, "INVALID", strlen) == 0)
52		sinfo->statemask |= XT_CONNTRACK_STATE_INVALID;
53	else if (strncasecmp(state, "NEW", strlen) == 0)
54		sinfo->statemask |= XT_CONNTRACK_STATE_BIT(IP_CT_NEW);
55	else if (strncasecmp(state, "ESTABLISHED", strlen) == 0)
56		sinfo->statemask |= XT_CONNTRACK_STATE_BIT(IP_CT_ESTABLISHED);
57	else if (strncasecmp(state, "RELATED", strlen) == 0)
58		sinfo->statemask |= XT_CONNTRACK_STATE_BIT(IP_CT_RELATED);
59	else if (strncasecmp(state, "UNTRACKED", strlen) == 0)
60		sinfo->statemask |= XT_CONNTRACK_STATE_UNTRACKED;
61	else if (strncasecmp(state, "SNAT", strlen) == 0)
62		sinfo->statemask |= XT_CONNTRACK_STATE_SNAT;
63	else if (strncasecmp(state, "DNAT", strlen) == 0)
64		sinfo->statemask |= XT_CONNTRACK_STATE_DNAT;
65	else
66		return 0;
67	return 1;
68}
69
70static void
71parse_states(const char *arg, struct xt_conntrack_info *sinfo)
72{
73	const char *comma;
74
75	while ((comma = strchr(arg, ',')) != NULL) {
76		if (comma == arg || !parse_state(arg, comma-arg, sinfo))
77			exit_error(PARAMETER_PROBLEM, "Bad ctstate `%s'", arg);
78		arg = comma+1;
79	}
80
81	if (strlen(arg) == 0 || !parse_state(arg, strlen(arg), sinfo))
82		exit_error(PARAMETER_PROBLEM, "Bad ctstate `%s'", arg);
83}
84
85static int
86parse_status(const char *status, size_t strlen, struct xt_conntrack_info *sinfo)
87{
88	if (strncasecmp(status, "NONE", strlen) == 0)
89		sinfo->statusmask |= 0;
90	else if (strncasecmp(status, "EXPECTED", strlen) == 0)
91		sinfo->statusmask |= IPS_EXPECTED;
92	else if (strncasecmp(status, "SEEN_REPLY", strlen) == 0)
93		sinfo->statusmask |= IPS_SEEN_REPLY;
94	else if (strncasecmp(status, "ASSURED", strlen) == 0)
95		sinfo->statusmask |= IPS_ASSURED;
96#ifdef IPS_CONFIRMED
97	else if (strncasecmp(status, "CONFIRMED", strlen) == 0)
98		sinfo->stausmask |= IPS_CONFIRMED;
99#endif
100	else
101		return 0;
102	return 1;
103}
104
105static void
106parse_statuses(const char *arg, struct xt_conntrack_info *sinfo)
107{
108	const char *comma;
109
110	while ((comma = strchr(arg, ',')) != NULL) {
111		if (comma == arg || !parse_status(arg, comma-arg, sinfo))
112			exit_error(PARAMETER_PROBLEM, "Bad ctstatus `%s'", arg);
113		arg = comma+1;
114	}
115
116	if (strlen(arg) == 0 || !parse_status(arg, strlen(arg), sinfo))
117		exit_error(PARAMETER_PROBLEM, "Bad ctstatus `%s'", arg);
118}
119
120static unsigned long
121parse_expire(const char *s)
122{
123	unsigned int len;
124
125	if (string_to_number(s, 0, 0, &len) == -1)
126		exit_error(PARAMETER_PROBLEM, "expire value invalid: `%s'\n", s);
127	else
128		return len;
129}
130
131/* If a single value is provided, min and max are both set to the value */
132static void
133parse_expires(const char *s, struct xt_conntrack_info *sinfo)
134{
135	char *buffer;
136	char *cp;
137
138	buffer = strdup(s);
139	if ((cp = strchr(buffer, ':')) == NULL)
140		sinfo->expires_min = sinfo->expires_max = parse_expire(buffer);
141	else {
142		*cp = '\0';
143		cp++;
144
145		sinfo->expires_min = buffer[0] ? parse_expire(buffer) : 0;
146		sinfo->expires_max = cp[0] ? parse_expire(cp) : -1;
147	}
148	free(buffer);
149
150	if (sinfo->expires_min > sinfo->expires_max)
151		exit_error(PARAMETER_PROBLEM,
152		           "expire min. range value `%lu' greater than max. "
153		           "range value `%lu'", sinfo->expires_min, sinfo->expires_max);
154}
155
156/* Function which parses command options; returns true if it
157   ate an option */
158static int conntrack_parse(int c, char **argv, int invert, unsigned int *flags,
159                           const void *entry, struct xt_entry_match **match)
160{
161	struct xt_conntrack_info *sinfo = (void *)(*match)->data;
162	char *protocol = NULL;
163	unsigned int naddrs = 0;
164	struct in_addr *addrs = NULL;
165
166
167	switch (c) {
168	case '1':
169		check_inverse(optarg, &invert, &optind, 0);
170
171		parse_states(argv[optind-1], sinfo);
172		if (invert) {
173			sinfo->invflags |= XT_CONNTRACK_STATE;
174		}
175		sinfo->flags |= XT_CONNTRACK_STATE;
176		break;
177
178	case '2':
179		check_inverse(optarg, &invert, &optind, 0);
180
181		if(invert)
182			sinfo->invflags |= XT_CONNTRACK_PROTO;
183
184		/* Canonicalize into lower case */
185		for (protocol = argv[optind-1]; *protocol; protocol++)
186			*protocol = tolower(*protocol);
187
188		protocol = argv[optind-1];
189		sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum = parse_protocol(protocol);
190
191		if (sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum == 0
192		    && (sinfo->invflags & XT_INV_PROTO))
193			exit_error(PARAMETER_PROBLEM,
194				   "rule would never match protocol");
195
196		sinfo->flags |= XT_CONNTRACK_PROTO;
197		break;
198
199	case '3':
200		check_inverse(optarg, &invert, &optind, 0);
201
202		if (invert)
203			sinfo->invflags |= XT_CONNTRACK_ORIGSRC;
204
205		parse_hostnetworkmask(argv[optind-1], &addrs,
206					&sinfo->sipmsk[IP_CT_DIR_ORIGINAL],
207					&naddrs);
208		if(naddrs > 1)
209			exit_error(PARAMETER_PROBLEM,
210				"multiple IP addresses not allowed");
211
212		if(naddrs == 1) {
213			sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip = addrs[0].s_addr;
214		}
215
216		sinfo->flags |= XT_CONNTRACK_ORIGSRC;
217		break;
218
219	case '4':
220		check_inverse(optarg, &invert, &optind, 0);
221
222		if (invert)
223			sinfo->invflags |= XT_CONNTRACK_ORIGDST;
224
225		parse_hostnetworkmask(argv[optind-1], &addrs,
226					&sinfo->dipmsk[IP_CT_DIR_ORIGINAL],
227					&naddrs);
228		if(naddrs > 1)
229			exit_error(PARAMETER_PROBLEM,
230				"multiple IP addresses not allowed");
231
232		if(naddrs == 1) {
233			sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip = addrs[0].s_addr;
234		}
235
236		sinfo->flags |= XT_CONNTRACK_ORIGDST;
237		break;
238
239	case '5':
240		check_inverse(optarg, &invert, &optind, 0);
241
242		if (invert)
243			sinfo->invflags |= XT_CONNTRACK_REPLSRC;
244
245		parse_hostnetworkmask(argv[optind-1], &addrs,
246					&sinfo->sipmsk[IP_CT_DIR_REPLY],
247					&naddrs);
248		if(naddrs > 1)
249			exit_error(PARAMETER_PROBLEM,
250				"multiple IP addresses not allowed");
251
252		if(naddrs == 1) {
253			sinfo->tuple[IP_CT_DIR_REPLY].src.ip = addrs[0].s_addr;
254		}
255
256		sinfo->flags |= XT_CONNTRACK_REPLSRC;
257		break;
258
259	case '6':
260		check_inverse(optarg, &invert, &optind, 0);
261
262		if (invert)
263			sinfo->invflags |= XT_CONNTRACK_REPLDST;
264
265		parse_hostnetworkmask(argv[optind-1], &addrs,
266					&sinfo->dipmsk[IP_CT_DIR_REPLY],
267					&naddrs);
268		if(naddrs > 1)
269			exit_error(PARAMETER_PROBLEM,
270				"multiple IP addresses not allowed");
271
272		if(naddrs == 1) {
273			sinfo->tuple[IP_CT_DIR_REPLY].dst.ip = addrs[0].s_addr;
274		}
275
276		sinfo->flags |= XT_CONNTRACK_REPLDST;
277		break;
278
279	case '7':
280		check_inverse(optarg, &invert, &optind, 0);
281
282		parse_statuses(argv[optind-1], sinfo);
283		if (invert) {
284			sinfo->invflags |= XT_CONNTRACK_STATUS;
285		}
286		sinfo->flags |= XT_CONNTRACK_STATUS;
287		break;
288
289	case '8':
290		check_inverse(optarg, &invert, &optind, 0);
291
292		parse_expires(argv[optind-1], sinfo);
293		if (invert) {
294			sinfo->invflags |= XT_CONNTRACK_EXPIRES;
295		}
296		sinfo->flags |= XT_CONNTRACK_EXPIRES;
297		break;
298
299	default:
300		return 0;
301	}
302
303	*flags = sinfo->flags;
304	return 1;
305}
306
307static void conntrack_mt_check(unsigned int flags)
308{
309	if (flags == 0)
310		exit_error(PARAMETER_PROBLEM, "You must specify one or more options");
311}
312
313static void
314print_state(unsigned int statemask)
315{
316	const char *sep = "";
317
318	if (statemask & XT_CONNTRACK_STATE_INVALID) {
319		printf("%sINVALID", sep);
320		sep = ",";
321	}
322	if (statemask & XT_CONNTRACK_STATE_BIT(IP_CT_NEW)) {
323		printf("%sNEW", sep);
324		sep = ",";
325	}
326	if (statemask & XT_CONNTRACK_STATE_BIT(IP_CT_RELATED)) {
327		printf("%sRELATED", sep);
328		sep = ",";
329	}
330	if (statemask & XT_CONNTRACK_STATE_BIT(IP_CT_ESTABLISHED)) {
331		printf("%sESTABLISHED", sep);
332		sep = ",";
333	}
334	if (statemask & XT_CONNTRACK_STATE_UNTRACKED) {
335		printf("%sUNTRACKED", sep);
336		sep = ",";
337	}
338	if (statemask & XT_CONNTRACK_STATE_SNAT) {
339		printf("%sSNAT", sep);
340		sep = ",";
341	}
342	if (statemask & XT_CONNTRACK_STATE_DNAT) {
343		printf("%sDNAT", sep);
344		sep = ",";
345	}
346	printf(" ");
347}
348
349static void
350print_status(unsigned int statusmask)
351{
352	const char *sep = "";
353
354	if (statusmask & IPS_EXPECTED) {
355		printf("%sEXPECTED", sep);
356		sep = ",";
357	}
358	if (statusmask & IPS_SEEN_REPLY) {
359		printf("%sSEEN_REPLY", sep);
360		sep = ",";
361	}
362	if (statusmask & IPS_ASSURED) {
363		printf("%sASSURED", sep);
364		sep = ",";
365	}
366#ifdef IPS_CONFIRMED
367	if (statusmask & IPS_CONFIRMED) {
368		printf("%sCONFIRMED", sep);
369		sep =",";
370	}
371#endif
372	if (statusmask == 0) {
373		printf("%sNONE", sep);
374		sep = ",";
375	}
376	printf(" ");
377}
378
379static void
380print_addr(struct in_addr *addr, struct in_addr *mask, int inv, int numeric)
381{
382	char buf[BUFSIZ];
383
384	if (inv)
385	       	printf("! ");
386
387	if (mask->s_addr == 0L && !numeric)
388		printf("%s ", "anywhere");
389	else {
390		if (numeric)
391			sprintf(buf, "%s", addr_to_dotted(addr));
392		else
393			sprintf(buf, "%s", addr_to_anyname(addr));
394		strcat(buf, mask_to_dotted(mask));
395		printf("%s ", buf);
396	}
397}
398
399/* Saves the matchinfo in parsable form to stdout. */
400static void
401matchinfo_print(const void *ip, const struct xt_entry_match *match, int numeric, const char *optpfx)
402{
403	struct xt_conntrack_info *sinfo = (void *)match->data;
404
405	if(sinfo->flags & XT_CONNTRACK_STATE) {
406        	if (sinfo->invflags & XT_CONNTRACK_STATE)
407                	printf("! ");
408		printf("%sctstate ", optpfx);
409		print_state(sinfo->statemask);
410	}
411
412	if(sinfo->flags & XT_CONNTRACK_PROTO) {
413        	if (sinfo->invflags & XT_CONNTRACK_PROTO)
414                	printf("! ");
415		printf("%sctproto ", optpfx);
416		printf("%u ", sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum);
417	}
418
419	if(sinfo->flags & XT_CONNTRACK_ORIGSRC) {
420		if (sinfo->invflags & XT_CONNTRACK_ORIGSRC)
421			printf("! ");
422		printf("%sctorigsrc ", optpfx);
423
424		print_addr(
425		    (struct in_addr *)&sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip,
426		    &sinfo->sipmsk[IP_CT_DIR_ORIGINAL],
427		    false,
428		    numeric);
429	}
430
431	if(sinfo->flags & XT_CONNTRACK_ORIGDST) {
432		if (sinfo->invflags & XT_CONNTRACK_ORIGDST)
433			printf("! ");
434		printf("%sctorigdst ", optpfx);
435
436		print_addr(
437		    (struct in_addr *)&sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip,
438		    &sinfo->dipmsk[IP_CT_DIR_ORIGINAL],
439		    false,
440		    numeric);
441	}
442
443	if(sinfo->flags & XT_CONNTRACK_REPLSRC) {
444		if (sinfo->invflags & XT_CONNTRACK_REPLSRC)
445			printf("! ");
446		printf("%sctreplsrc ", optpfx);
447
448		print_addr(
449		    (struct in_addr *)&sinfo->tuple[IP_CT_DIR_REPLY].src.ip,
450		    &sinfo->sipmsk[IP_CT_DIR_REPLY],
451		    false,
452		    numeric);
453	}
454
455	if(sinfo->flags & XT_CONNTRACK_REPLDST) {
456		if (sinfo->invflags & XT_CONNTRACK_REPLDST)
457			printf("! ");
458		printf("%sctrepldst ", optpfx);
459
460		print_addr(
461		    (struct in_addr *)&sinfo->tuple[IP_CT_DIR_REPLY].dst.ip,
462		    &sinfo->dipmsk[IP_CT_DIR_REPLY],
463		    false,
464		    numeric);
465	}
466
467	if(sinfo->flags & XT_CONNTRACK_STATUS) {
468        	if (sinfo->invflags & XT_CONNTRACK_STATUS)
469                	printf("! ");
470		printf("%sctstatus ", optpfx);
471		print_status(sinfo->statusmask);
472	}
473
474	if(sinfo->flags & XT_CONNTRACK_EXPIRES) {
475        	if (sinfo->invflags & XT_CONNTRACK_EXPIRES)
476                	printf("! ");
477		printf("%sctexpire ", optpfx);
478
479        	if (sinfo->expires_max == sinfo->expires_min)
480                	printf("%lu ", sinfo->expires_min);
481        	else
482                	printf("%lu:%lu ", sinfo->expires_min, sinfo->expires_max);
483	}
484}
485
486/* Prints out the matchinfo. */
487static void conntrack_print(const void *ip, const struct xt_entry_match *match,
488                            int numeric)
489{
490	matchinfo_print(ip, match, numeric, "");
491}
492
493/* Saves the matchinfo in parsable form to stdout. */
494static void conntrack_save(const void *ip, const struct xt_entry_match *match)
495{
496	matchinfo_print(ip, match, 1, "--");
497}
498
499static struct xtables_match conntrack_match = {
500	.version       = IPTABLES_VERSION,
501	.name          = "conntrack",
502	.revision      = 0,
503	.family        = AF_INET,
504	.size          = XT_ALIGN(sizeof(struct xt_conntrack_info)),
505	.userspacesize = XT_ALIGN(sizeof(struct xt_conntrack_info)),
506	.help          = conntrack_mt_help,
507	.parse         = conntrack_parse,
508	.final_check   = conntrack_mt_check,
509	.print         = conntrack_print,
510	.save          = conntrack_save,
511	.extra_opts    = conntrack_mt_opts,
512};
513
514void _init(void)
515{
516	xtables_register_match(&conntrack_match);
517}
518