1 /* $OpenBSD: filter.c,v 1.8 2008/06/13 07:25:26 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/ioctl.h>
20 #include <sys/types.h>
21 #include <sys/socket.h>
22
23 #include <net/if.h>
24 #include <net/pfvar.h>
25 #include <netinet/in.h>
26 #include <netinet/tcp.h>
27 #include <arpa/inet.h>
28
29 #include <err.h>
30 #include <errno.h>
31 #include <libpfctl.h>
32 #include <fcntl.h>
33 #include <stdio.h>
34 #include <string.h>
35 #include <unistd.h>
36
37 #include "filter.h"
38
39 /* From netinet/in.h, but only _KERNEL_ gets them. */
40 #define satosin(sa) ((struct sockaddr_in *)(sa))
41 #define satosin6(sa) ((struct sockaddr_in6 *)(sa))
42
43 enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
44
45 int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
46 u_int16_t);
47 int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
48 struct sockaddr_in *);
49 int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
50 struct sockaddr_in6 *);
51
52 static struct pfioc_pooladdr pfp;
53 static struct pfctl_rule pfrule;
54 static char pfanchor[PF_ANCHOR_NAME_SIZE];
55 static char pfanchor_call[PF_ANCHOR_NAME_SIZE];
56 static uint32_t pfticket;
57 static uint32_t pfpool_ticket;
58 static struct pfioc_trans pft;
59 static struct pfioc_trans_e pfte[TRANS_SIZE];
60 static int rule_log;
61 static struct pfctl_handle *pfh = NULL;
62 static const char *qname, *tagname;
63
64 int
add_filter(u_int32_t id,u_int8_t dir,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port)65 add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
66 struct sockaddr *dst, u_int16_t d_port)
67 {
68 if (!src || !dst || !d_port) {
69 errno = EINVAL;
70 return (-1);
71 }
72
73 if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port) == -1)
74 return (-1);
75
76 pfrule.direction = dir;
77 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
78 pfticket, pfpool_ticket))
79 return (-1);
80
81 return (0);
82 }
83
84 int
add_nat(u_int32_t id,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port,struct sockaddr * nat,u_int16_t nat_range_low,u_int16_t nat_range_high)85 add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
86 u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
87 u_int16_t nat_range_high)
88 {
89 if (!src || !dst || !d_port || !nat || !nat_range_low ||
90 (src->sa_family != nat->sa_family)) {
91 errno = EINVAL;
92 return (-1);
93 }
94
95 if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port) == -1)
96 return (-1);
97
98 if (nat->sa_family == AF_INET) {
99 memcpy(&pfp.addr.addr.v.a.addr.v4,
100 &satosin(nat)->sin_addr.s_addr, 4);
101 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
102 } else {
103 memcpy(&pfp.addr.addr.v.a.addr.v6,
104 &satosin6(nat)->sin6_addr.s6_addr, 16);
105 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
106 }
107 if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
108 return (-1);
109
110 pfrule.rdr.proxy_port[0] = nat_range_low;
111 pfrule.rdr.proxy_port[1] = nat_range_high;
112 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
113 pfticket, pfpool_ticket))
114 return (-1);
115
116 return (0);
117 }
118
119 int
add_rdr(u_int32_t id,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port,struct sockaddr * rdr,u_int16_t rdr_port)120 add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
121 u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port)
122 {
123 if (!src || !dst || !d_port || !rdr || !rdr_port ||
124 (src->sa_family != rdr->sa_family)) {
125 errno = EINVAL;
126 return (-1);
127 }
128
129 if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port) == -1)
130 return (-1);
131
132 if (rdr->sa_family == AF_INET) {
133 memcpy(&pfp.addr.addr.v.a.addr.v4,
134 &satosin(rdr)->sin_addr.s_addr, 4);
135 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
136 } else {
137 memcpy(&pfp.addr.addr.v.a.addr.v6,
138 &satosin6(rdr)->sin6_addr.s6_addr, 16);
139 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
140 }
141 if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
142 return (-1);
143
144 pfrule.rdr.proxy_port[0] = rdr_port;
145 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
146 pfticket, pfpool_ticket))
147 return (-1);
148
149 return (0);
150 }
151
152 int
do_commit(void)153 do_commit(void)
154 {
155 if (ioctl(pfctl_fd(pfh), DIOCXCOMMIT, &pft) == -1)
156 return (-1);
157
158 return (0);
159 }
160
161 int
do_rollback(void)162 do_rollback(void)
163 {
164 if (ioctl(pfctl_fd(pfh), DIOCXROLLBACK, &pft) == -1)
165 return (-1);
166
167 return (0);
168 }
169
170 void
init_filter(const char * opt_qname,const char * opt_tagname,int opt_verbose)171 init_filter(const char *opt_qname, const char *opt_tagname, int opt_verbose)
172 {
173 struct pfctl_status *status;
174
175 qname = opt_qname;
176 tagname = opt_tagname;
177
178 if (opt_verbose == 1)
179 rule_log = PF_LOG;
180 else if (opt_verbose == 2)
181 rule_log = PF_LOG_ALL;
182
183 pfh = pfctl_open(PF_DEVICE);
184 if (pfh == NULL)
185 err(1, "pfctl_open");
186 status = pfctl_get_status_h(pfh);
187 if (status == NULL)
188 err(1, "DIOCGETSTATUS");
189 if (!status->running)
190 errx(1, "pf is disabled");
191
192 pfctl_free_status(status);
193 }
194
195 int
prepare_commit(u_int32_t id)196 prepare_commit(u_int32_t id)
197 {
198 char an[PF_ANCHOR_NAME_SIZE];
199 int i;
200
201 memset(&pft, 0, sizeof pft);
202 pft.size = TRANS_SIZE;
203 pft.esize = sizeof pfte[0];
204 pft.array = pfte;
205
206 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
207 getpid(), id);
208 for (i = 0; i < TRANS_SIZE; i++) {
209 memset(&pfte[i], 0, sizeof pfte[0]);
210 strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
211 switch (i) {
212 case TRANS_FILTER:
213 pfte[i].rs_num = PF_RULESET_FILTER;
214 break;
215 case TRANS_NAT:
216 pfte[i].rs_num = PF_RULESET_NAT;
217 break;
218 case TRANS_RDR:
219 pfte[i].rs_num = PF_RULESET_RDR;
220 break;
221 default:
222 errno = EINVAL;
223 return (-1);
224 }
225 }
226
227 if (ioctl(pfctl_fd(pfh), DIOCXBEGIN, &pft) == -1)
228 return (-1);
229
230 return (0);
231 }
232
233 int
prepare_rule(u_int32_t id,int rs_num,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port)234 prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
235 struct sockaddr *dst, u_int16_t d_port)
236 {
237 char an[PF_ANCHOR_NAME_SIZE];
238
239 if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
240 (src->sa_family != dst->sa_family)) {
241 errno = EPROTONOSUPPORT;
242 return (-1);
243 }
244
245 memset(&pfp, 0, sizeof pfp);
246 memset(&pfrule, 0, sizeof pfrule);
247 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
248 getpid(), id);
249 strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
250 strlcpy(pfanchor, an, PF_ANCHOR_NAME_SIZE);
251
252 switch (rs_num) {
253 case PF_RULESET_FILTER:
254 pfticket = pfte[TRANS_FILTER].ticket;
255 break;
256 case PF_RULESET_NAT:
257 pfticket = pfte[TRANS_NAT].ticket;
258 break;
259 case PF_RULESET_RDR:
260 pfticket = pfte[TRANS_RDR].ticket;
261 break;
262 default:
263 errno = EINVAL;
264 return (-1);
265 }
266 if (pfctl_begin_addrs(pfh, &pfp.ticket))
267 return (-1);
268 pfpool_ticket = pfp.ticket;
269
270 /* Generic for all rule types. */
271 pfrule.af = src->sa_family;
272 pfrule.proto = IPPROTO_TCP;
273 pfrule.src.addr.type = PF_ADDR_ADDRMASK;
274 pfrule.dst.addr.type = PF_ADDR_ADDRMASK;
275 if (src->sa_family == AF_INET) {
276 memcpy(&pfrule.src.addr.v.a.addr.v4,
277 &satosin(src)->sin_addr.s_addr, 4);
278 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 4);
279 memcpy(&pfrule.dst.addr.v.a.addr.v4,
280 &satosin(dst)->sin_addr.s_addr, 4);
281 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 4);
282 } else {
283 memcpy(&pfrule.src.addr.v.a.addr.v6,
284 &satosin6(src)->sin6_addr.s6_addr, 16);
285 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 16);
286 memcpy(&pfrule.dst.addr.v.a.addr.v6,
287 &satosin6(dst)->sin6_addr.s6_addr, 16);
288 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 16);
289 }
290 pfrule.dst.port_op = PF_OP_EQ;
291 pfrule.dst.port[0] = htons(d_port);
292
293 switch (rs_num) {
294 case PF_RULESET_FILTER:
295 /*
296 * pass [quick] [log] inet[6] proto tcp \
297 * from $src to $dst port = $d_port flags S/SA keep state
298 * (max 1) [queue qname] [tag tagname]
299 */
300 pfrule.action = PF_PASS;
301 pfrule.quick = 1;
302 pfrule.log = rule_log;
303 pfrule.keep_state = 1;
304 pfrule.flags = TH_SYN;
305 pfrule.flagset = (TH_SYN|TH_ACK);
306 pfrule.max_states = 1;
307 if (qname != NULL)
308 strlcpy(pfrule.qname, qname, sizeof pfrule.qname);
309 if (tagname != NULL) {
310 pfrule.quick = 0;
311 strlcpy(pfrule.tagname, tagname,
312 sizeof pfrule.tagname);
313 }
314 break;
315 case PF_RULESET_NAT:
316 /*
317 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
318 */
319 pfrule.action = PF_NAT;
320 break;
321 case PF_RULESET_RDR:
322 /*
323 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
324 */
325 pfrule.action = PF_RDR;
326 break;
327 default:
328 errno = EINVAL;
329 return (-1);
330 }
331
332 return (0);
333 }
334
335 int
server_lookup(struct sockaddr * client,struct sockaddr * proxy,struct sockaddr * server)336 server_lookup(struct sockaddr *client, struct sockaddr *proxy,
337 struct sockaddr *server)
338 {
339 if (client->sa_family == AF_INET)
340 return (server_lookup4(satosin(client), satosin(proxy),
341 satosin(server)));
342
343 if (client->sa_family == AF_INET6)
344 return (server_lookup6(satosin6(client), satosin6(proxy),
345 satosin6(server)));
346
347 errno = EPROTONOSUPPORT;
348 return (-1);
349 }
350
351 int
server_lookup4(struct sockaddr_in * client,struct sockaddr_in * proxy,struct sockaddr_in * server)352 server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
353 struct sockaddr_in *server)
354 {
355 struct pfctl_natlook_key k = {};
356 struct pfctl_natlook r = {};
357
358 k.direction = PF_OUT;
359 k.af = AF_INET;
360 k.proto = IPPROTO_TCP;
361 memcpy(&k.saddr.v4, &client->sin_addr.s_addr, sizeof(k.saddr.v4));
362 memcpy(&k.daddr.v4, &proxy->sin_addr.s_addr, sizeof(k.daddr.v4));
363 k.sport = client->sin_port;
364 k.dport = proxy->sin_port;
365
366 if (pfctl_natlook(pfh, &k, &r))
367 return (-1);
368
369 memset(server, 0, sizeof(struct sockaddr_in));
370 server->sin_len = sizeof(struct sockaddr_in);
371 server->sin_family = AF_INET;
372 memcpy(&server->sin_addr.s_addr, &r.daddr.v4,
373 sizeof(server->sin_addr.s_addr));
374 server->sin_port = r.dport;
375
376 return (0);
377 }
378
379 int
server_lookup6(struct sockaddr_in6 * client,struct sockaddr_in6 * proxy,struct sockaddr_in6 * server)380 server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
381 struct sockaddr_in6 *server)
382 {
383 struct pfctl_natlook_key k = {};
384 struct pfctl_natlook r = {};
385
386 k.direction = PF_OUT;
387 k.af = AF_INET6;
388 k.proto = IPPROTO_TCP;
389 memcpy(&k.saddr.v6, &client->sin6_addr.s6_addr, sizeof(k.saddr.v6));
390 memcpy(&k.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof(k.daddr.v6));
391 k.sport = client->sin6_port;
392 k.dport = proxy->sin6_port;
393
394 if (pfctl_natlook(pfh, &k, &r))
395 return (-1);
396
397 memset(server, 0, sizeof(struct sockaddr_in6));
398 server->sin6_len = sizeof(struct sockaddr_in6);
399 server->sin6_family = AF_INET6;
400 memcpy(&server->sin6_addr.s6_addr, &r.daddr.v6,
401 sizeof(server->sin6_addr));
402 server->sin6_port = r.dport;
403
404 return (0);
405 }
406