1 /* $OpenBSD: filter.c,v 1.1 2005/12/28 19:07:07 jcs Exp $ */
2 /* $FreeBSD$ */
3
4 /*
5 * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <syslog.h>
21
22 #include <sys/ioctl.h>
23 #include <sys/types.h>
24 #include <sys/socket.h>
25
26 #include <net/if.h>
27 #include <net/pfvar.h>
28 #include <netinet/in.h>
29 #include <netinet/tcp.h>
30 #include <arpa/inet.h>
31
32 #include <err.h>
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <libpfctl.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <unistd.h>
40
41 #include "filter.h"
42
43 /* From netinet/in.h, but only _KERNEL_ gets them. */
44 #define satosin(sa) ((struct sockaddr_in *)(sa))
45 #define satosin6(sa) ((struct sockaddr_in6 *)(sa))
46
47 enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
48
49 int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
50 u_int16_t, u_int8_t);
51 int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
52 struct sockaddr_in *, u_int8_t);
53 int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
54 struct sockaddr_in6 *, u_int8_t);
55
56 static struct pfioc_pooladdr pfp;
57 static struct pfctl_rule pfrule;
58 static uint32_t pfticket;
59 static uint32_t pfpool_ticket;
60 static char pfanchor[PF_ANCHOR_NAME_SIZE];
61 static char pfanchor_call[PF_ANCHOR_NAME_SIZE];
62 static struct pfioc_trans pft;
63 static struct pfioc_trans_e pfte[TRANS_SIZE];
64 static int rule_log;
65 static struct pfctl_handle *pfh = NULL;
66 static char *qname;
67
68 int
add_filter(u_int32_t id,u_int8_t dir,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port,u_int8_t proto)69 add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
70 struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
71 {
72 if (!src || !dst || !d_port || !proto) {
73 errno = EINVAL;
74 return (-1);
75 }
76
77 if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port, proto) == -1)
78 return (-1);
79
80 pfrule.direction = dir;
81 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
82 pfticket, pfpool_ticket))
83 return (-1);
84
85 return (0);
86 }
87
88 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,u_int8_t proto)89 add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
90 u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
91 u_int16_t nat_range_high, u_int8_t proto)
92 {
93 if (!src || !dst || !d_port || !nat || !nat_range_low || !proto ||
94 (src->sa_family != nat->sa_family)) {
95 errno = EINVAL;
96 return (-1);
97 }
98
99 if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port, proto) == -1)
100 return (-1);
101
102 if (nat->sa_family == AF_INET) {
103 memcpy(&pfp.addr.addr.v.a.addr.v4,
104 &satosin(nat)->sin_addr.s_addr, 4);
105 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
106 } else {
107 memcpy(&pfp.addr.addr.v.a.addr.v6,
108 &satosin6(nat)->sin6_addr.s6_addr, 16);
109 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
110 }
111 if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
112 return (-1);
113
114 pfrule.rpool.proxy_port[0] = nat_range_low;
115 pfrule.rpool.proxy_port[1] = nat_range_high;
116 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
117 pfticket, pfpool_ticket))
118 return (-1);
119
120 return (0);
121 }
122
123 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,u_int8_t proto)124 add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
125 u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port, u_int8_t proto)
126 {
127 if (!src || !dst || !d_port || !rdr || !rdr_port || !proto ||
128 (src->sa_family != rdr->sa_family)) {
129 errno = EINVAL;
130 return (-1);
131 }
132
133 if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port, proto) == -1)
134 return (-1);
135
136 if (rdr->sa_family == AF_INET) {
137 memcpy(&pfp.addr.addr.v.a.addr.v4,
138 &satosin(rdr)->sin_addr.s_addr, 4);
139 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
140 } else {
141 memcpy(&pfp.addr.addr.v.a.addr.v6,
142 &satosin6(rdr)->sin6_addr.s6_addr, 16);
143 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
144 }
145 if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
146 return (-1);
147
148 pfrule.rpool.proxy_port[0] = rdr_port;
149 if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
150 pfticket, pfpool_ticket))
151 return (-1);
152
153 return (0);
154 }
155
156 int
do_commit(void)157 do_commit(void)
158 {
159 if (ioctl(pfctl_fd(pfh), DIOCXCOMMIT, &pft) == -1)
160 return (-1);
161
162 return (0);
163 }
164
165 int
do_rollback(void)166 do_rollback(void)
167 {
168 if (ioctl(pfctl_fd(pfh), DIOCXROLLBACK, &pft) == -1)
169 return (-1);
170
171 return (0);
172 }
173
174 void
init_filter(char * opt_qname,int opt_verbose)175 init_filter(char *opt_qname, int opt_verbose)
176 {
177 struct pfctl_status *status;
178
179 qname = opt_qname;
180
181 if (opt_verbose == 1)
182 rule_log = PF_LOG;
183 else if (opt_verbose == 2)
184 rule_log = PF_LOG_ALL;
185
186 pfh = pfctl_open(PF_DEVICE);
187 if (pfh == NULL) {
188 syslog(LOG_ERR, "can't pfctl_open()");
189 exit(1);
190 }
191 status = pfctl_get_status_h(pfh);
192 if (status == NULL) {
193 syslog(LOG_ERR, "DIOCGETSTATUS");
194 exit(1);
195 }
196 if (!status->running) {
197 syslog(LOG_ERR, "pf is disabled");
198 exit(1);
199 }
200
201 pfctl_free_status(status);
202 }
203
204 int
prepare_commit(u_int32_t id)205 prepare_commit(u_int32_t id)
206 {
207 char an[PF_ANCHOR_NAME_SIZE];
208 int i;
209
210 memset(&pft, 0, sizeof pft);
211 pft.size = TRANS_SIZE;
212 pft.esize = sizeof pfte[0];
213 pft.array = pfte;
214
215 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
216 getpid(), id);
217 for (i = 0; i < TRANS_SIZE; i++) {
218 memset(&pfte[i], 0, sizeof pfte[0]);
219 strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
220 switch (i) {
221 case TRANS_FILTER:
222 pfte[i].rs_num = PF_RULESET_FILTER;
223 break;
224 case TRANS_NAT:
225 pfte[i].rs_num = PF_RULESET_NAT;
226 break;
227 case TRANS_RDR:
228 pfte[i].rs_num = PF_RULESET_RDR;
229 break;
230 default:
231 errno = EINVAL;
232 return (-1);
233 }
234 }
235
236 if (ioctl(pfctl_fd(pfh), DIOCXBEGIN, &pft) == -1)
237 return (-1);
238
239 return (0);
240 }
241
242 int
prepare_rule(u_int32_t id,int rs_num,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port,u_int8_t proto)243 prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
244 struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
245 {
246 char an[PF_ANCHOR_NAME_SIZE];
247
248 if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
249 (src->sa_family != dst->sa_family)) {
250 errno = EPROTONOSUPPORT;
251 return (-1);
252 }
253
254 memset(&pfp, 0, sizeof pfp);
255 memset(&pfrule, 0, sizeof pfrule);
256 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
257 getpid(), id);
258 strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
259 strlcpy(pfanchor, an, PF_ANCHOR_NAME_SIZE);
260
261 switch (rs_num) {
262 case PF_RULESET_FILTER:
263 pfticket = pfte[TRANS_FILTER].ticket;
264 break;
265 case PF_RULESET_NAT:
266 pfticket = pfte[TRANS_NAT].ticket;
267 break;
268 case PF_RULESET_RDR:
269 pfticket = pfte[TRANS_RDR].ticket;
270 break;
271 default:
272 errno = EINVAL;
273 return (-1);
274 }
275 if (pfctl_begin_addrs(pfh, &pfp.ticket))
276 return (-1);
277 pfpool_ticket = pfp.ticket;
278
279 /* Generic for all rule types. */
280 pfrule.af = src->sa_family;
281 pfrule.proto = proto;
282 pfrule.src.addr.type = PF_ADDR_ADDRMASK;
283 pfrule.dst.addr.type = PF_ADDR_ADDRMASK;
284 if (src->sa_family == AF_INET) {
285 memcpy(&pfrule.src.addr.v.a.addr.v4,
286 &satosin(src)->sin_addr.s_addr, 4);
287 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 4);
288 memcpy(&pfrule.dst.addr.v.a.addr.v4,
289 &satosin(dst)->sin_addr.s_addr, 4);
290 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 4);
291 } else {
292 memcpy(&pfrule.src.addr.v.a.addr.v6,
293 &satosin6(src)->sin6_addr.s6_addr, 16);
294 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 16);
295 memcpy(&pfrule.dst.addr.v.a.addr.v6,
296 &satosin6(dst)->sin6_addr.s6_addr, 16);
297 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 16);
298 }
299 pfrule.dst.port_op = PF_OP_EQ;
300 pfrule.dst.port[0] = htons(d_port);
301
302 switch (rs_num) {
303 case PF_RULESET_FILTER:
304 /*
305 * pass quick [log] inet[6] proto tcp \
306 * from $src to $dst port = $d_port flags S/SAFR keep state
307 * (max 1) [queue qname]
308 */
309 pfrule.action = PF_PASS;
310 pfrule.quick = 1;
311 pfrule.log = rule_log;
312 pfrule.keep_state = 1;
313 #ifdef __FreeBSD__
314 pfrule.flags = (proto == IPPROTO_TCP ? TH_SYN : 0);
315 pfrule.flagset = (proto == IPPROTO_TCP ?
316 (TH_SYN|TH_ACK|TH_FIN|TH_RST) : 0);
317 #else
318 pfrule.flags = (proto == IPPROTO_TCP ? TH_SYN : NULL);
319 pfrule.flagset = (proto == IPPROTO_TCP ?
320 (TH_SYN|TH_ACK|TH_FIN|TH_RST) : NULL);
321 #endif
322 pfrule.max_states = 1;
323 if (qname != NULL)
324 strlcpy(pfrule.qname, qname, sizeof pfrule.qname);
325 break;
326 case PF_RULESET_NAT:
327 /*
328 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
329 */
330 pfrule.action = PF_NAT;
331 break;
332 case PF_RULESET_RDR:
333 /*
334 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
335 */
336 pfrule.action = PF_RDR;
337 break;
338 default:
339 errno = EINVAL;
340 return (-1);
341 }
342
343 return (0);
344 }
345
346 int
server_lookup(struct sockaddr * client,struct sockaddr * proxy,struct sockaddr * server,u_int8_t proto)347 server_lookup(struct sockaddr *client, struct sockaddr *proxy,
348 struct sockaddr *server, u_int8_t proto)
349 {
350 if (client->sa_family == AF_INET)
351 return (server_lookup4(satosin(client), satosin(proxy),
352 satosin(server), proto));
353
354 if (client->sa_family == AF_INET6)
355 return (server_lookup6(satosin6(client), satosin6(proxy),
356 satosin6(server), proto));
357
358 errno = EPROTONOSUPPORT;
359 return (-1);
360 }
361
362 int
server_lookup4(struct sockaddr_in * client,struct sockaddr_in * proxy,struct sockaddr_in * server,u_int8_t proto)363 server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
364 struct sockaddr_in *server, u_int8_t proto)
365 {
366 struct pfctl_natlook_key k = {};
367 struct pfctl_natlook r = {};
368
369 k.direction = PF_OUT;
370 k.af = AF_INET;
371 k.proto = proto;
372 memcpy(&k.saddr.v4, &client->sin_addr.s_addr, sizeof(k.saddr.v4));
373 memcpy(&k.daddr.v4, &proxy->sin_addr.s_addr, sizeof(k.daddr.v4));
374 k.sport = client->sin_port;
375 k.dport = proxy->sin_port;
376
377 if (pfctl_natlook(pfh, &k, &r))
378 return (-1);
379
380 memset(server, 0, sizeof(struct sockaddr_in));
381 server->sin_len = sizeof(struct sockaddr_in);
382 server->sin_family = AF_INET;
383 memcpy(&server->sin_addr.s_addr, &r.daddr.v4,
384 sizeof server->sin_addr.s_addr);
385 server->sin_port = r.dport;
386
387 return (0);
388 }
389
390 int
server_lookup6(struct sockaddr_in6 * client,struct sockaddr_in6 * proxy,struct sockaddr_in6 * server,u_int8_t proto)391 server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
392 struct sockaddr_in6 *server, u_int8_t proto)
393 {
394 struct pfctl_natlook_key k = {};
395 struct pfctl_natlook r = {};
396
397 k.direction = PF_OUT;
398 k.af = AF_INET6;
399 k.proto = proto;
400 memcpy(&k.saddr.v6, &client->sin6_addr.s6_addr, sizeof k.saddr.v6);
401 memcpy(&k.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof k.daddr.v6);
402 k.sport = client->sin6_port;
403 k.dport = proxy->sin6_port;
404
405 if (pfctl_natlook(pfh, &k, &r))
406 return (-1);
407
408 memset(server, 0, sizeof(struct sockaddr_in6));
409 server->sin6_len = sizeof(struct sockaddr_in6);
410 server->sin6_family = AF_INET6;
411 memcpy(&server->sin6_addr.s6_addr, &r.daddr.v6,
412 sizeof server->sin6_addr);
413 server->sin6_port = r.dport;
414
415 return (0);
416 }
417