1 /* $OpenBSD: filter.c,v 1.8 2008/06/13 07:25:26 claudio Exp $ */
2
3 /*
4 * Copyright (c) 2004, 2005 Camiel Dobbelaar, <[email protected]>
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 dev, rule_log;
61 static const char *qname, *tagname;
62
63 int
add_filter(u_int32_t id,u_int8_t dir,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port)64 add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
65 struct sockaddr *dst, u_int16_t d_port)
66 {
67 if (!src || !dst || !d_port) {
68 errno = EINVAL;
69 return (-1);
70 }
71
72 if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port) == -1)
73 return (-1);
74
75 pfrule.direction = dir;
76 if (pfctl_add_rule(dev, &pfrule, pfanchor, pfanchor_call,
77 pfticket, pfpool_ticket))
78 return (-1);
79
80 return (0);
81 }
82
83 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)84 add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
85 u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
86 u_int16_t nat_range_high)
87 {
88 if (!src || !dst || !d_port || !nat || !nat_range_low ||
89 (src->sa_family != nat->sa_family)) {
90 errno = EINVAL;
91 return (-1);
92 }
93
94 if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port) == -1)
95 return (-1);
96
97 if (nat->sa_family == AF_INET) {
98 memcpy(&pfp.addr.addr.v.a.addr.v4,
99 &satosin(nat)->sin_addr.s_addr, 4);
100 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
101 } else {
102 memcpy(&pfp.addr.addr.v.a.addr.v6,
103 &satosin6(nat)->sin6_addr.s6_addr, 16);
104 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
105 }
106 if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
107 return (-1);
108
109 pfrule.rpool.proxy_port[0] = nat_range_low;
110 pfrule.rpool.proxy_port[1] = nat_range_high;
111 if (pfctl_add_rule(dev, &pfrule, pfanchor, pfanchor_call,
112 pfticket, pfpool_ticket))
113 return (-1);
114
115 return (0);
116 }
117
118 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)119 add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
120 u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port)
121 {
122 if (!src || !dst || !d_port || !rdr || !rdr_port ||
123 (src->sa_family != rdr->sa_family)) {
124 errno = EINVAL;
125 return (-1);
126 }
127
128 if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port) == -1)
129 return (-1);
130
131 if (rdr->sa_family == AF_INET) {
132 memcpy(&pfp.addr.addr.v.a.addr.v4,
133 &satosin(rdr)->sin_addr.s_addr, 4);
134 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
135 } else {
136 memcpy(&pfp.addr.addr.v.a.addr.v6,
137 &satosin6(rdr)->sin6_addr.s6_addr, 16);
138 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
139 }
140 if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
141 return (-1);
142
143 pfrule.rpool.proxy_port[0] = rdr_port;
144 if (pfctl_add_rule(dev, &pfrule, pfanchor, pfanchor_call,
145 pfticket, pfpool_ticket))
146 return (-1);
147
148 return (0);
149 }
150
151 int
do_commit(void)152 do_commit(void)
153 {
154 if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
155 return (-1);
156
157 return (0);
158 }
159
160 int
do_rollback(void)161 do_rollback(void)
162 {
163 if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
164 return (-1);
165
166 return (0);
167 }
168
169 void
init_filter(const char * opt_qname,const char * opt_tagname,int opt_verbose)170 init_filter(const char *opt_qname, const char *opt_tagname, int opt_verbose)
171 {
172 struct pf_status status;
173
174 qname = opt_qname;
175 tagname = opt_tagname;
176
177 if (opt_verbose == 1)
178 rule_log = PF_LOG;
179 else if (opt_verbose == 2)
180 rule_log = PF_LOG_ALL;
181
182 dev = open("/dev/pf", O_RDWR);
183 if (dev == -1)
184 err(1, "open /dev/pf");
185 if (ioctl(dev, DIOCGETSTATUS, &status) == -1)
186 err(1, "DIOCGETSTATUS");
187 if (!status.running)
188 errx(1, "pf is disabled");
189 }
190
191 int
prepare_commit(u_int32_t id)192 prepare_commit(u_int32_t id)
193 {
194 char an[PF_ANCHOR_NAME_SIZE];
195 int i;
196
197 memset(&pft, 0, sizeof pft);
198 pft.size = TRANS_SIZE;
199 pft.esize = sizeof pfte[0];
200 pft.array = pfte;
201
202 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
203 getpid(), id);
204 for (i = 0; i < TRANS_SIZE; i++) {
205 memset(&pfte[i], 0, sizeof pfte[0]);
206 strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
207 switch (i) {
208 case TRANS_FILTER:
209 pfte[i].rs_num = PF_RULESET_FILTER;
210 break;
211 case TRANS_NAT:
212 pfte[i].rs_num = PF_RULESET_NAT;
213 break;
214 case TRANS_RDR:
215 pfte[i].rs_num = PF_RULESET_RDR;
216 break;
217 default:
218 errno = EINVAL;
219 return (-1);
220 }
221 }
222
223 if (ioctl(dev, DIOCXBEGIN, &pft) == -1)
224 return (-1);
225
226 return (0);
227 }
228
229 int
prepare_rule(u_int32_t id,int rs_num,struct sockaddr * src,struct sockaddr * dst,u_int16_t d_port)230 prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
231 struct sockaddr *dst, u_int16_t d_port)
232 {
233 char an[PF_ANCHOR_NAME_SIZE];
234
235 if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
236 (src->sa_family != dst->sa_family)) {
237 errno = EPROTONOSUPPORT;
238 return (-1);
239 }
240
241 memset(&pfp, 0, sizeof pfp);
242 memset(&pfrule, 0, sizeof pfrule);
243 snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
244 getpid(), id);
245 strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
246 strlcpy(pfanchor, an, PF_ANCHOR_NAME_SIZE);
247
248 switch (rs_num) {
249 case PF_RULESET_FILTER:
250 pfticket = pfte[TRANS_FILTER].ticket;
251 break;
252 case PF_RULESET_NAT:
253 pfticket = pfte[TRANS_NAT].ticket;
254 break;
255 case PF_RULESET_RDR:
256 pfticket = pfte[TRANS_RDR].ticket;
257 break;
258 default:
259 errno = EINVAL;
260 return (-1);
261 }
262 if (ioctl(dev, DIOCBEGINADDRS, &pfp) == -1)
263 return (-1);
264 pfpool_ticket = pfp.ticket;
265
266 /* Generic for all rule types. */
267 pfrule.af = src->sa_family;
268 pfrule.proto = IPPROTO_TCP;
269 pfrule.src.addr.type = PF_ADDR_ADDRMASK;
270 pfrule.dst.addr.type = PF_ADDR_ADDRMASK;
271 if (src->sa_family == AF_INET) {
272 memcpy(&pfrule.src.addr.v.a.addr.v4,
273 &satosin(src)->sin_addr.s_addr, 4);
274 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 4);
275 memcpy(&pfrule.dst.addr.v.a.addr.v4,
276 &satosin(dst)->sin_addr.s_addr, 4);
277 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 4);
278 } else {
279 memcpy(&pfrule.src.addr.v.a.addr.v6,
280 &satosin6(src)->sin6_addr.s6_addr, 16);
281 memset(&pfrule.src.addr.v.a.mask.addr8, 255, 16);
282 memcpy(&pfrule.dst.addr.v.a.addr.v6,
283 &satosin6(dst)->sin6_addr.s6_addr, 16);
284 memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 16);
285 }
286 pfrule.dst.port_op = PF_OP_EQ;
287 pfrule.dst.port[0] = htons(d_port);
288
289 switch (rs_num) {
290 case PF_RULESET_FILTER:
291 /*
292 * pass [quick] [log] inet[6] proto tcp \
293 * from $src to $dst port = $d_port flags S/SA keep state
294 * (max 1) [queue qname] [tag tagname]
295 */
296 pfrule.action = PF_PASS;
297 pfrule.quick = 1;
298 pfrule.log = rule_log;
299 pfrule.keep_state = 1;
300 pfrule.flags = TH_SYN;
301 pfrule.flagset = (TH_SYN|TH_ACK);
302 pfrule.max_states = 1;
303 if (qname != NULL)
304 strlcpy(pfrule.qname, qname, sizeof pfrule.qname);
305 if (tagname != NULL) {
306 pfrule.quick = 0;
307 strlcpy(pfrule.tagname, tagname,
308 sizeof pfrule.tagname);
309 }
310 break;
311 case PF_RULESET_NAT:
312 /*
313 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
314 */
315 pfrule.action = PF_NAT;
316 break;
317 case PF_RULESET_RDR:
318 /*
319 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
320 */
321 pfrule.action = PF_RDR;
322 break;
323 default:
324 errno = EINVAL;
325 return (-1);
326 }
327
328 return (0);
329 }
330
331 int
server_lookup(struct sockaddr * client,struct sockaddr * proxy,struct sockaddr * server)332 server_lookup(struct sockaddr *client, struct sockaddr *proxy,
333 struct sockaddr *server)
334 {
335 if (client->sa_family == AF_INET)
336 return (server_lookup4(satosin(client), satosin(proxy),
337 satosin(server)));
338
339 if (client->sa_family == AF_INET6)
340 return (server_lookup6(satosin6(client), satosin6(proxy),
341 satosin6(server)));
342
343 errno = EPROTONOSUPPORT;
344 return (-1);
345 }
346
347 int
server_lookup4(struct sockaddr_in * client,struct sockaddr_in * proxy,struct sockaddr_in * server)348 server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
349 struct sockaddr_in *server)
350 {
351 struct pfioc_natlook pnl;
352
353 memset(&pnl, 0, sizeof pnl);
354 pnl.direction = PF_OUT;
355 pnl.af = AF_INET;
356 pnl.proto = IPPROTO_TCP;
357 memcpy(&pnl.saddr.v4, &client->sin_addr.s_addr, sizeof pnl.saddr.v4);
358 memcpy(&pnl.daddr.v4, &proxy->sin_addr.s_addr, sizeof pnl.daddr.v4);
359 pnl.sport = client->sin_port;
360 pnl.dport = proxy->sin_port;
361
362 if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
363 return (-1);
364
365 memset(server, 0, sizeof(struct sockaddr_in));
366 server->sin_len = sizeof(struct sockaddr_in);
367 server->sin_family = AF_INET;
368 memcpy(&server->sin_addr.s_addr, &pnl.rdaddr.v4,
369 sizeof server->sin_addr.s_addr);
370 server->sin_port = pnl.rdport;
371
372 return (0);
373 }
374
375 int
server_lookup6(struct sockaddr_in6 * client,struct sockaddr_in6 * proxy,struct sockaddr_in6 * server)376 server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
377 struct sockaddr_in6 *server)
378 {
379 struct pfioc_natlook pnl;
380
381 memset(&pnl, 0, sizeof pnl);
382 pnl.direction = PF_OUT;
383 pnl.af = AF_INET6;
384 pnl.proto = IPPROTO_TCP;
385 memcpy(&pnl.saddr.v6, &client->sin6_addr.s6_addr, sizeof pnl.saddr.v6);
386 memcpy(&pnl.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof pnl.daddr.v6);
387 pnl.sport = client->sin6_port;
388 pnl.dport = proxy->sin6_port;
389
390 if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
391 return (-1);
392
393 memset(server, 0, sizeof(struct sockaddr_in6));
394 server->sin6_len = sizeof(struct sockaddr_in6);
395 server->sin6_family = AF_INET6;
396 memcpy(&server->sin6_addr.s6_addr, &pnl.rdaddr.v6,
397 sizeof server->sin6_addr);
398 server->sin6_port = pnl.rdport;
399
400 return (0);
401 }
402