xref: /openbsd-src/usr.sbin/ftp-proxy/filter.c (revision 87d85e29180d27346c55765a03d2d2bce4db363c)
1 /*	$OpenBSD: filter.c,v 1.5 2006/12/01 07:31:21 camield 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 <fcntl.h>
32 #include <stdio.h>
33 #include <string.h>
34 #include <unistd.h>
35 
36 #include "filter.h"
37 
38 /* From netinet/in.h, but only _KERNEL_ gets them. */
39 #define satosin(sa)	((struct sockaddr_in *)(sa))
40 #define satosin6(sa)	((struct sockaddr_in6 *)(sa))
41 
42 enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
43 
44 int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
45     u_int16_t);
46 int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
47     struct sockaddr_in *);
48 int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
49     struct sockaddr_in6 *);
50 
51 static struct pfioc_pooladdr	pfp;
52 static struct pfioc_rule	pfr;
53 static struct pfioc_trans	pft;
54 static struct pfioc_trans_e	pfte[TRANS_SIZE];
55 static int dev, rule_log;
56 static char *qname;
57 
58 int
59 add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
60     struct sockaddr *dst, u_int16_t d_port)
61 {
62 	if (!src || !dst || !d_port) {
63 		errno = EINVAL;
64 		return (-1);
65 	}
66 
67 	if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port) == -1)
68 		return (-1);
69 
70 	pfr.rule.direction = dir;
71 	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
72 		return (-1);
73 
74 	return (0);
75 }
76 
77 int
78 add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
79     u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
80     u_int16_t nat_range_high)
81 {
82 	if (!src || !dst || !d_port || !nat || !nat_range_low ||
83 	    (src->sa_family != nat->sa_family)) {
84 		errno = EINVAL;
85 		return (-1);
86 	}
87 
88 	if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port) == -1)
89 		return (-1);
90 
91 	if (nat->sa_family == AF_INET) {
92 		memcpy(&pfp.addr.addr.v.a.addr.v4,
93 		    &satosin(nat)->sin_addr.s_addr, 4);
94 		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
95 	} else {
96 		memcpy(&pfp.addr.addr.v.a.addr.v6,
97 		    &satosin6(nat)->sin6_addr.s6_addr, 16);
98 		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
99 	}
100 	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
101 		return (-1);
102 
103 	pfr.rule.rpool.proxy_port[0] = nat_range_low;
104 	pfr.rule.rpool.proxy_port[1] = nat_range_high;
105 	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
106 		return (-1);
107 
108 	return (0);
109 }
110 
111 int
112 add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
113     u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port)
114 {
115 	if (!src || !dst || !d_port || !rdr || !rdr_port ||
116 	    (src->sa_family != rdr->sa_family)) {
117 		errno = EINVAL;
118 		return (-1);
119 	}
120 
121 	if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port) == -1)
122 		return (-1);
123 
124 	if (rdr->sa_family == AF_INET) {
125 		memcpy(&pfp.addr.addr.v.a.addr.v4,
126 		    &satosin(rdr)->sin_addr.s_addr, 4);
127 		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
128 	} else {
129 		memcpy(&pfp.addr.addr.v.a.addr.v6,
130 		    &satosin6(rdr)->sin6_addr.s6_addr, 16);
131 		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
132 	}
133 	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
134 		return (-1);
135 
136 	pfr.rule.rpool.proxy_port[0] = rdr_port;
137 	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
138 		return (-1);
139 
140 	return (0);
141 }
142 
143 int
144 do_commit(void)
145 {
146 	if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
147 		return (-1);
148 
149 	return (0);
150 }
151 
152 int
153 do_rollback(void)
154 {
155 	if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
156 		return (-1);
157 
158 	return (0);
159 }
160 
161 void
162 init_filter(char *opt_qname, int opt_verbose)
163 {
164 	struct pf_status status;
165 
166 	qname = opt_qname;
167 
168 	if (opt_verbose == 1)
169 		rule_log = PF_LOG;
170 	else if (opt_verbose == 2)
171 		rule_log = PF_LOG_ALL;
172 
173 	dev = open("/dev/pf", O_RDWR);
174 	if (dev == -1)
175 		err(1, "/dev/pf");
176 	if (ioctl(dev, DIOCGETSTATUS, &status) == -1)
177 		err(1, "DIOCGETSTATUS");
178 	if (!status.running)
179 		errx(1, "pf is disabled");
180 }
181 
182 int
183 prepare_commit(u_int32_t id)
184 {
185 	char an[PF_ANCHOR_NAME_SIZE];
186 	int i;
187 
188 	memset(&pft, 0, sizeof pft);
189 	pft.size = TRANS_SIZE;
190 	pft.esize = sizeof pfte[0];
191 	pft.array = pfte;
192 
193 	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
194 	    getpid(), id);
195 	for (i = 0; i < TRANS_SIZE; i++) {
196 		memset(&pfte[i], 0, sizeof pfte[0]);
197 		strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
198 		switch (i) {
199 		case TRANS_FILTER:
200 			pfte[i].rs_num = PF_RULESET_FILTER;
201 			break;
202 		case TRANS_NAT:
203 			pfte[i].rs_num = PF_RULESET_NAT;
204 			break;
205 		case TRANS_RDR:
206 			pfte[i].rs_num = PF_RULESET_RDR;
207 			break;
208 		default:
209 			errno = EINVAL;
210 			return (-1);
211 		}
212 	}
213 
214 	if (ioctl(dev, DIOCXBEGIN, &pft) == -1)
215 		return (-1);
216 
217 	return (0);
218 }
219 
220 int
221 prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
222     struct sockaddr *dst, u_int16_t d_port)
223 {
224 	char an[PF_ANCHOR_NAME_SIZE];
225 
226 	if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
227 	    (src->sa_family != dst->sa_family)) {
228 	    	errno = EPROTONOSUPPORT;
229 		return (-1);
230 	}
231 
232 	memset(&pfp, 0, sizeof pfp);
233 	memset(&pfr, 0, sizeof pfr);
234 	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
235 	    getpid(), id);
236 	strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
237 	strlcpy(pfr.anchor, an, PF_ANCHOR_NAME_SIZE);
238 
239 	switch (rs_num) {
240 	case PF_RULESET_FILTER:
241 		pfr.ticket = pfte[TRANS_FILTER].ticket;
242 		break;
243 	case PF_RULESET_NAT:
244 		pfr.ticket = pfte[TRANS_NAT].ticket;
245 		break;
246 	case PF_RULESET_RDR:
247 		pfr.ticket = pfte[TRANS_RDR].ticket;
248 		break;
249 	default:
250 		errno = EINVAL;
251 		return (-1);
252 	}
253 	if (ioctl(dev, DIOCBEGINADDRS, &pfp) == -1)
254 		return (-1);
255 	pfr.pool_ticket = pfp.ticket;
256 
257 	/* Generic for all rule types. */
258 	pfr.rule.af = src->sa_family;
259 	pfr.rule.proto = IPPROTO_TCP;
260 	pfr.rule.src.addr.type = PF_ADDR_ADDRMASK;
261 	pfr.rule.dst.addr.type = PF_ADDR_ADDRMASK;
262 	if (src->sa_family == AF_INET) {
263 		memcpy(&pfr.rule.src.addr.v.a.addr.v4,
264 		    &satosin(src)->sin_addr.s_addr, 4);
265 		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 4);
266 		memcpy(&pfr.rule.dst.addr.v.a.addr.v4,
267 		    &satosin(dst)->sin_addr.s_addr, 4);
268 		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 4);
269 	} else {
270 		memcpy(&pfr.rule.src.addr.v.a.addr.v6,
271 		    &satosin6(src)->sin6_addr.s6_addr, 16);
272 		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 16);
273 		memcpy(&pfr.rule.dst.addr.v.a.addr.v6,
274 		    &satosin6(dst)->sin6_addr.s6_addr, 16);
275 		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 16);
276 	}
277 	pfr.rule.dst.port_op = PF_OP_EQ;
278 	pfr.rule.dst.port[0] = htons(d_port);
279 
280 	switch (rs_num) {
281 	case PF_RULESET_FILTER:
282 		/*
283 		 * pass quick [log] inet[6] proto tcp \
284 		 *     from $src to $dst port = $d_port flags S/SA keep state
285 		 *     (max 1) [queue qname]
286 		 */
287 		pfr.rule.action = PF_PASS;
288 		pfr.rule.quick = 1;
289 		pfr.rule.log = rule_log;
290 		pfr.rule.keep_state = 1;
291 		pfr.rule.flags = TH_SYN;
292 		pfr.rule.flagset = (TH_SYN|TH_ACK);
293 		pfr.rule.max_states = 1;
294 		if (qname != NULL)
295 			strlcpy(pfr.rule.qname, qname, sizeof pfr.rule.qname);
296 		break;
297 	case PF_RULESET_NAT:
298 		/*
299 		 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
300 		 */
301 		pfr.rule.action = PF_NAT;
302 		break;
303 	case PF_RULESET_RDR:
304 		/*
305 		 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
306 		 */
307 		pfr.rule.action = PF_RDR;
308 		break;
309 	default:
310 		errno = EINVAL;
311 		return (-1);
312 	}
313 
314 	return (0);
315 }
316 
317 int
318 server_lookup(struct sockaddr *client, struct sockaddr *proxy,
319     struct sockaddr *server)
320 {
321 	if (client->sa_family == AF_INET)
322 		return (server_lookup4(satosin(client), satosin(proxy),
323 		    satosin(server)));
324 
325 	if (client->sa_family == AF_INET6)
326 		return (server_lookup6(satosin6(client), satosin6(proxy),
327 		    satosin6(server)));
328 
329 	errno = EPROTONOSUPPORT;
330 	return (-1);
331 }
332 
333 int
334 server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
335     struct sockaddr_in *server)
336 {
337 	struct pfioc_natlook pnl;
338 
339 	memset(&pnl, 0, sizeof pnl);
340 	pnl.direction = PF_OUT;
341 	pnl.af = AF_INET;
342 	pnl.proto = IPPROTO_TCP;
343 	memcpy(&pnl.saddr.v4, &client->sin_addr.s_addr, sizeof pnl.saddr.v4);
344 	memcpy(&pnl.daddr.v4, &proxy->sin_addr.s_addr, sizeof pnl.daddr.v4);
345 	pnl.sport = client->sin_port;
346 	pnl.dport = proxy->sin_port;
347 
348 	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
349 		return (-1);
350 
351 	memset(server, 0, sizeof(struct sockaddr_in));
352 	server->sin_len = sizeof(struct sockaddr_in);
353 	server->sin_family = AF_INET;
354 	memcpy(&server->sin_addr.s_addr, &pnl.rdaddr.v4,
355 	    sizeof server->sin_addr.s_addr);
356 	server->sin_port = pnl.rdport;
357 
358 	return (0);
359 }
360 
361 int
362 server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
363     struct sockaddr_in6 *server)
364 {
365 	struct pfioc_natlook pnl;
366 
367 	memset(&pnl, 0, sizeof pnl);
368 	pnl.direction = PF_OUT;
369 	pnl.af = AF_INET6;
370 	pnl.proto = IPPROTO_TCP;
371 	memcpy(&pnl.saddr.v6, &client->sin6_addr.s6_addr, sizeof pnl.saddr.v6);
372 	memcpy(&pnl.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof pnl.daddr.v6);
373 	pnl.sport = client->sin6_port;
374 	pnl.dport = proxy->sin6_port;
375 
376 	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
377 		return (-1);
378 
379 	memset(server, 0, sizeof(struct sockaddr_in6));
380 	server->sin6_len = sizeof(struct sockaddr_in6);
381 	server->sin6_family = AF_INET6;
382 	memcpy(&server->sin6_addr.s6_addr, &pnl.rdaddr.v6,
383 	    sizeof server->sin6_addr);
384 	server->sin6_port = pnl.rdport;
385 
386 	return (0);
387 }
388