1 /* Shared library add-on to iptables for DCCP matching
2 *
3 * (C) 2005 by Harald Welte <laforge@netfilter.org>
4 *
5 * This program is distributed under the terms of GNU GPL v2, 1991
6 *
7 */
8 #include <stdint.h>
9 #include <stdio.h>
10 #include <string.h>
11 #include <stdlib.h>
12 #include <netdb.h>
13 #include <arpa/inet.h>
14 #include <xtables.h>
15 #include <linux/dccp.h>
16 #include <linux/netfilter/x_tables.h>
17 #include <linux/netfilter/xt_dccp.h>
18
19 #if 0
20 #define DEBUGP(format, first...) printf(format, ##first)
21 #define static
22 #else
23 #define DEBUGP(format, fist...)
24 #endif
25
26 enum {
27 O_SOURCE_PORT = 0,
28 O_DEST_PORT,
29 O_DCCP_TYPES,
30 O_DCCP_OPTION,
31 };
32
dccp_help(void)33 static void dccp_help(void)
34 {
35 printf(
36 "dccp match options\n"
37 "[!] --source-port port[:port] match source port(s)\n"
38 " --sport ...\n"
39 "[!] --destination-port port[:port] match destination port(s)\n"
40 " --dport ...\n"
41 "[!] --dccp-types type[,...] match when packet is one of the given types\n"
42 "[!] --dccp-option option match if option (by number!) is set\n"
43 );
44 }
45
46 #define s struct xt_dccp_info
47 static const struct xt_option_entry dccp_opts[] = {
48 {.name = "source-port", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
49 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
50 {.name = "sport", .id = O_SOURCE_PORT, .type = XTTYPE_PORTRC,
51 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, spts)},
52 {.name = "destination-port", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
53 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
54 {.name = "dport", .id = O_DEST_PORT, .type = XTTYPE_PORTRC,
55 .flags = XTOPT_INVERT | XTOPT_PUT, XTOPT_POINTER(s, dpts)},
56 {.name = "dccp-types", .id = O_DCCP_TYPES, .type = XTTYPE_STRING,
57 .flags = XTOPT_INVERT},
58 {.name = "dccp-option", .id = O_DCCP_OPTION, .type = XTTYPE_UINT8,
59 .min = 1, .max = UINT8_MAX, .flags = XTOPT_INVERT | XTOPT_PUT,
60 XTOPT_POINTER(s, option)},
61 XTOPT_TABLEEND,
62 };
63 #undef s
64
65 static const char *const dccp_pkt_types[] = {
66 [DCCP_PKT_REQUEST] = "REQUEST",
67 [DCCP_PKT_RESPONSE] = "RESPONSE",
68 [DCCP_PKT_DATA] = "DATA",
69 [DCCP_PKT_ACK] = "ACK",
70 [DCCP_PKT_DATAACK] = "DATAACK",
71 [DCCP_PKT_CLOSEREQ] = "CLOSEREQ",
72 [DCCP_PKT_CLOSE] = "CLOSE",
73 [DCCP_PKT_RESET] = "RESET",
74 [DCCP_PKT_SYNC] = "SYNC",
75 [DCCP_PKT_SYNCACK] = "SYNCACK",
76 [DCCP_PKT_INVALID] = "INVALID",
77 };
78
79 /* Bits for type values 11-15 */
80 #define INVALID_OTHER_TYPE_MASK 0xf800
81
82 static uint16_t
parse_dccp_types(const char * typestring)83 parse_dccp_types(const char *typestring)
84 {
85 uint16_t typemask = 0;
86 char *ptr, *buffer;
87
88 buffer = strdup(typestring);
89
90 for (ptr = strtok(buffer, ","); ptr; ptr = strtok(NULL, ",")) {
91 unsigned int i;
92 for (i = 0; i < ARRAY_SIZE(dccp_pkt_types); ++i)
93 if (!strcasecmp(dccp_pkt_types[i], ptr)) {
94 typemask |= (1 << i);
95 break;
96 }
97 if (i == ARRAY_SIZE(dccp_pkt_types))
98 xtables_error(PARAMETER_PROBLEM,
99 "Unknown DCCP type `%s'", ptr);
100 }
101 if (typemask & (1 << DCCP_PKT_INVALID))
102 typemask |= INVALID_OTHER_TYPE_MASK;
103
104
105 free(buffer);
106 return typemask;
107 }
108
dccp_parse(struct xt_option_call * cb)109 static void dccp_parse(struct xt_option_call *cb)
110 {
111 struct xt_dccp_info *einfo = cb->data;
112
113 xtables_option_parse(cb);
114 switch (cb->entry->id) {
115 case O_SOURCE_PORT:
116 einfo->flags |= XT_DCCP_SRC_PORTS;
117 if (cb->invert)
118 einfo->invflags |= XT_DCCP_SRC_PORTS;
119 break;
120 case O_DEST_PORT:
121 einfo->flags |= XT_DCCP_DEST_PORTS;
122 if (cb->invert)
123 einfo->invflags |= XT_DCCP_DEST_PORTS;
124 break;
125 case O_DCCP_TYPES:
126 einfo->flags |= XT_DCCP_TYPE;
127 einfo->typemask = parse_dccp_types(cb->arg);
128 if (cb->invert)
129 einfo->invflags |= XT_DCCP_TYPE;
130 break;
131 case O_DCCP_OPTION:
132 einfo->flags |= XT_DCCP_OPTION;
133 if (cb->invert)
134 einfo->invflags |= XT_DCCP_OPTION;
135 break;
136 }
137 }
138
139 static const char *
port_to_service(int port)140 port_to_service(int port)
141 {
142 const struct servent *service;
143
144 if ((service = getservbyport(htons(port), "dccp")))
145 return service->s_name;
146
147 return NULL;
148 }
149
150 static void
print_port(uint16_t port,int numeric)151 print_port(uint16_t port, int numeric)
152 {
153 const char *service;
154
155 if (numeric || (service = port_to_service(port)) == NULL)
156 printf("%u", port);
157 else
158 printf("%s", service);
159 }
160
161 static void
print_ports(const char * name,uint16_t min,uint16_t max,int invert,int numeric)162 print_ports(const char *name, uint16_t min, uint16_t max,
163 int invert, int numeric)
164 {
165 const char *inv = invert ? "!" : "";
166
167 if (min != 0 || max != 0xFFFF || invert) {
168 printf(" %s", name);
169 if (min == max) {
170 printf(":%s", inv);
171 print_port(min, numeric);
172 } else {
173 printf("s:%s", inv);
174 print_port(min, numeric);
175 printf(":");
176 print_port(max, numeric);
177 }
178 }
179 }
180
181 static void
print_types(uint16_t types,int inverted,int numeric)182 print_types(uint16_t types, int inverted, int numeric)
183 {
184 int have_type = 0;
185
186 if (inverted)
187 printf(" !");
188
189 printf(" ");
190 while (types) {
191 unsigned int i;
192
193 for (i = 0; !(types & (1 << i)); i++);
194
195 if (have_type)
196 printf(",");
197 else
198 have_type = 1;
199
200 if (numeric)
201 printf("%u", i);
202 else {
203 printf("%s", dccp_pkt_types[i]);
204
205 if (i == DCCP_PKT_INVALID)
206 break;
207 }
208
209 types &= ~(1 << i);
210 }
211 }
212
213 static void
print_option(uint8_t option,int invert,int numeric)214 print_option(uint8_t option, int invert, int numeric)
215 {
216 if (option || invert)
217 printf(" option=%s%u", invert ? "!" : "", option);
218 }
219
220 static void
dccp_print(const void * ip,const struct xt_entry_match * match,int numeric)221 dccp_print(const void *ip, const struct xt_entry_match *match, int numeric)
222 {
223 const struct xt_dccp_info *einfo =
224 (const struct xt_dccp_info *)match->data;
225
226 printf(" dccp");
227
228 if (einfo->flags & XT_DCCP_SRC_PORTS) {
229 print_ports("spt", einfo->spts[0], einfo->spts[1],
230 einfo->invflags & XT_DCCP_SRC_PORTS,
231 numeric);
232 }
233
234 if (einfo->flags & XT_DCCP_DEST_PORTS) {
235 print_ports("dpt", einfo->dpts[0], einfo->dpts[1],
236 einfo->invflags & XT_DCCP_DEST_PORTS,
237 numeric);
238 }
239
240 if (einfo->flags & XT_DCCP_TYPE) {
241 print_types(einfo->typemask,
242 einfo->invflags & XT_DCCP_TYPE,
243 numeric);
244 }
245
246 if (einfo->flags & XT_DCCP_OPTION) {
247 print_option(einfo->option,
248 einfo->invflags & XT_DCCP_OPTION, numeric);
249 }
250 }
251
dccp_save(const void * ip,const struct xt_entry_match * match)252 static void dccp_save(const void *ip, const struct xt_entry_match *match)
253 {
254 const struct xt_dccp_info *einfo =
255 (const struct xt_dccp_info *)match->data;
256
257 if (einfo->flags & XT_DCCP_SRC_PORTS) {
258 if (einfo->invflags & XT_DCCP_SRC_PORTS)
259 printf(" !");
260 if (einfo->spts[0] != einfo->spts[1])
261 printf(" --sport %u:%u",
262 einfo->spts[0], einfo->spts[1]);
263 else
264 printf(" --sport %u", einfo->spts[0]);
265 }
266
267 if (einfo->flags & XT_DCCP_DEST_PORTS) {
268 if (einfo->invflags & XT_DCCP_DEST_PORTS)
269 printf(" !");
270 if (einfo->dpts[0] != einfo->dpts[1])
271 printf(" --dport %u:%u",
272 einfo->dpts[0], einfo->dpts[1]);
273 else
274 printf(" --dport %u", einfo->dpts[0]);
275 }
276
277 if (einfo->flags & XT_DCCP_TYPE) {
278 printf("%s --dccp-types",
279 einfo->invflags & XT_DCCP_TYPE ? " !" : "");
280 print_types(einfo->typemask, false, 0);
281 }
282
283 if (einfo->flags & XT_DCCP_OPTION) {
284 printf("%s --dccp-option %u",
285 einfo->invflags & XT_DCCP_OPTION ? " !" : "",
286 einfo->option);
287 }
288 }
289
290 static const char *const dccp_pkt_types_xlate[] = {
291 [DCCP_PKT_REQUEST] = "request",
292 [DCCP_PKT_RESPONSE] = "response",
293 [DCCP_PKT_DATA] = "data",
294 [DCCP_PKT_ACK] = "ack",
295 [DCCP_PKT_DATAACK] = "dataack",
296 [DCCP_PKT_CLOSEREQ] = "closereq",
297 [DCCP_PKT_CLOSE] = "close",
298 [DCCP_PKT_RESET] = "reset",
299 [DCCP_PKT_SYNC] = "sync",
300 [DCCP_PKT_SYNCACK] = "syncack",
301 [DCCP_PKT_INVALID] = "10-15",
302 };
303
dccp_type_xlate(const struct xt_dccp_info * einfo,struct xt_xlate * xl)304 static int dccp_type_xlate(const struct xt_dccp_info *einfo,
305 struct xt_xlate *xl)
306 {
307 bool have_type = false, set_need = false;
308 uint16_t types = einfo->typemask;
309
310 if (types & INVALID_OTHER_TYPE_MASK) {
311 types &= ~INVALID_OTHER_TYPE_MASK;
312 types |= 1 << DCCP_PKT_INVALID;
313 }
314
315 if ((types != 0) && !(types == (types & -types))) {
316 xt_xlate_add(xl, "{");
317 set_need = true;
318 }
319
320 while (types) {
321 unsigned int i;
322
323 for (i = 0; !(types & (1 << i)); i++);
324
325 if (have_type)
326 xt_xlate_add(xl, ", ");
327 else
328 have_type = true;
329
330 xt_xlate_add(xl, "%s", dccp_pkt_types_xlate[i]);
331
332 types &= ~(1 << i);
333 }
334
335 if (set_need)
336 xt_xlate_add(xl, "}");
337
338 return 1;
339 }
340
dccp_xlate(struct xt_xlate * xl,const struct xt_xlate_mt_params * params)341 static int dccp_xlate(struct xt_xlate *xl,
342 const struct xt_xlate_mt_params *params)
343 {
344 const struct xt_dccp_info *einfo =
345 (const struct xt_dccp_info *)params->match->data;
346 char *space = "";
347 int ret = 1;
348
349 if (einfo->flags & XT_DCCP_SRC_PORTS) {
350 xt_xlate_add(xl, "dccp sport%s %u",
351 einfo->invflags & XT_DCCP_SRC_PORTS ? " !=" : "",
352 einfo->spts[0]);
353
354 if (einfo->spts[0] != einfo->spts[1])
355 xt_xlate_add(xl, "-%u", einfo->spts[1]);
356
357 space = " ";
358 }
359
360 if (einfo->flags & XT_DCCP_DEST_PORTS) {
361 xt_xlate_add(xl, "%sdccp dport%s %u", space,
362 einfo->invflags & XT_DCCP_DEST_PORTS ? " !=" : "",
363 einfo->dpts[0]);
364
365 if (einfo->dpts[0] != einfo->dpts[1])
366 xt_xlate_add(xl, "-%u", einfo->dpts[1]);
367
368 space = " ";
369 }
370
371 if (einfo->flags & XT_DCCP_TYPE && einfo->typemask) {
372 xt_xlate_add(xl, "%sdccp type%s ", space,
373 einfo->invflags & XT_DCCP_TYPE ? " !=" : "");
374 ret = dccp_type_xlate(einfo, xl);
375
376 space = " ";
377 }
378
379 /* FIXME: no dccp option support in nftables yet */
380 if (einfo->flags & XT_DCCP_OPTION)
381 ret = 0;
382
383 return ret;
384 }
385 static struct xtables_match dccp_match = {
386 .name = "dccp",
387 .family = NFPROTO_UNSPEC,
388 .version = XTABLES_VERSION,
389 .size = XT_ALIGN(sizeof(struct xt_dccp_info)),
390 .userspacesize = XT_ALIGN(sizeof(struct xt_dccp_info)),
391 .help = dccp_help,
392 .print = dccp_print,
393 .save = dccp_save,
394 .x6_parse = dccp_parse,
395 .x6_options = dccp_opts,
396 .xlate = dccp_xlate,
397 };
398
_init(void)399 void _init(void)
400 {
401 xtables_register_match(&dccp_match);
402 }
403