filter.c revision 171169 
1/*	$OpenBSD: filter.c,v 1.1 2005/12/28 19:07:07 jcs 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 <syslog.h>
20
21#include <sys/ioctl.h>
22#include <sys/types.h>
23#include <sys/socket.h>
24
25#include <net/if.h>
26#include <net/pfvar.h>
27#include <netinet/in.h>
28#include <netinet/tcp.h>
29#include <arpa/inet.h>
30
31#include <err.h>
32#include <errno.h>
33#include <fcntl.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <string.h>
37#include <unistd.h>
38
39#include "filter.h"
40
41/* From netinet/in.h, but only _KERNEL_ gets them. */
42#define satosin(sa)	((struct sockaddr_in *)(sa))
43#define satosin6(sa)	((struct sockaddr_in6 *)(sa))
44
45enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
46
47int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
48    u_int16_t, u_int8_t);
49int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
50    struct sockaddr_in *, u_int8_t);
51int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
52    struct sockaddr_in6 *, u_int8_t);
53
54static struct pfioc_pooladdr	pfp;
55static struct pfioc_rule	pfr;
56static struct pfioc_trans	pft;
57static struct pfioc_trans_e	pfte[TRANS_SIZE];
58static int dev, rule_log;
59static char *qname;
60
61int
62add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
63    struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
64{
65	if (!src || !dst || !d_port || !proto) {
66		errno = EINVAL;
67		return (-1);
68	}
69
70	if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port, proto) == -1)
71		return (-1);
72
73	pfr.rule.direction = dir;
74	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
75		return (-1);
76
77	return (0);
78}
79
80int
81add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
82    u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
83    u_int16_t nat_range_high, u_int8_t proto)
84{
85	if (!src || !dst || !d_port || !nat || !nat_range_low || !proto ||
86	    (src->sa_family != nat->sa_family)) {
87		errno = EINVAL;
88		return (-1);
89	}
90
91	if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port, proto) == -1)
92		return (-1);
93
94	if (nat->sa_family == AF_INET) {
95		memcpy(&pfp.addr.addr.v.a.addr.v4,
96		    &satosin(nat)->sin_addr.s_addr, 4);
97		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
98	} else {
99		memcpy(&pfp.addr.addr.v.a.addr.v6,
100		    &satosin6(nat)->sin6_addr.s6_addr, 16);
101		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
102	}
103	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
104		return (-1);
105
106	pfr.rule.rpool.proxy_port[0] = nat_range_low;
107	pfr.rule.rpool.proxy_port[1] = nat_range_high;
108	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
109		return (-1);
110
111	return (0);
112}
113
114int
115add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
116    u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port, u_int8_t proto)
117{
118	if (!src || !dst || !d_port || !rdr || !rdr_port || !proto ||
119	    (src->sa_family != rdr->sa_family)) {
120		errno = EINVAL;
121		return (-1);
122	}
123
124	if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port, proto) == -1)
125		return (-1);
126
127	if (rdr->sa_family == AF_INET) {
128		memcpy(&pfp.addr.addr.v.a.addr.v4,
129		    &satosin(rdr)->sin_addr.s_addr, 4);
130		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
131	} else {
132		memcpy(&pfp.addr.addr.v.a.addr.v6,
133		    &satosin6(rdr)->sin6_addr.s6_addr, 16);
134		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
135	}
136	if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
137		return (-1);
138
139	pfr.rule.rpool.proxy_port[0] = rdr_port;
140	if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
141		return (-1);
142
143	return (0);
144}
145
146int
147do_commit(void)
148{
149	if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
150		return (-1);
151
152	return (0);
153}
154
155int
156do_rollback(void)
157{
158	if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
159		return (-1);
160
161	return (0);
162}
163
164void
165init_filter(char *opt_qname, int opt_verbose)
166{
167	struct pf_status status;
168
169	qname = opt_qname;
170
171	if (opt_verbose == 1)
172		rule_log = PF_LOG;
173	else if (opt_verbose == 2)
174		rule_log = PF_LOG_ALL;
175
176	dev = open("/dev/pf", O_RDWR);
177	if (dev == -1) {
178		syslog(LOG_ERR, "can't open /dev/pf");
179		exit(1);
180	}
181	if (ioctl(dev, DIOCGETSTATUS, &status) == -1) {
182		syslog(LOG_ERR, "DIOCGETSTATUS");
183		exit(1);
184	}
185	if (!status.running) {
186		syslog(LOG_ERR, "pf is disabled");
187		exit(1);
188	}
189}
190
191int
192prepare_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
229int
230prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
231    struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
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(&pfr, 0, sizeof pfr);
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(pfr.anchor, an, PF_ANCHOR_NAME_SIZE);
247
248	switch (rs_num) {
249	case PF_RULESET_FILTER:
250		pfr.ticket = pfte[TRANS_FILTER].ticket;
251		break;
252	case PF_RULESET_NAT:
253		pfr.ticket = pfte[TRANS_NAT].ticket;
254		break;
255	case PF_RULESET_RDR:
256		pfr.ticket = 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	pfr.pool_ticket = pfp.ticket;
265
266	/* Generic for all rule types. */
267	pfr.rule.af = src->sa_family;
268	pfr.rule.proto = proto;
269	pfr.rule.src.addr.type = PF_ADDR_ADDRMASK;
270	pfr.rule.dst.addr.type = PF_ADDR_ADDRMASK;
271	if (src->sa_family == AF_INET) {
272		memcpy(&pfr.rule.src.addr.v.a.addr.v4,
273		    &satosin(src)->sin_addr.s_addr, 4);
274		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 4);
275		memcpy(&pfr.rule.dst.addr.v.a.addr.v4,
276		    &satosin(dst)->sin_addr.s_addr, 4);
277		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 4);
278	} else {
279		memcpy(&pfr.rule.src.addr.v.a.addr.v6,
280		    &satosin6(src)->sin6_addr.s6_addr, 16);
281		memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 16);
282		memcpy(&pfr.rule.dst.addr.v.a.addr.v6,
283		    &satosin6(dst)->sin6_addr.s6_addr, 16);
284		memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 16);
285	}
286	pfr.rule.dst.port_op = PF_OP_EQ;
287	pfr.rule.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/SAFR keep state
294		 *     (max 1) [queue qname]
295		 */
296		pfr.rule.action = PF_PASS;
297		pfr.rule.quick = 1;
298		pfr.rule.log = rule_log;
299		pfr.rule.keep_state = 1;
300		pfr.rule.flags = (proto == IPPROTO_TCP ? TH_SYN : NULL);
301		pfr.rule.flagset = (proto == IPPROTO_TCP ?
302		    (TH_SYN|TH_ACK|TH_FIN|TH_RST) : NULL);
303		pfr.rule.max_states = 1;
304		if (qname != NULL)
305			strlcpy(pfr.rule.qname, qname, sizeof pfr.rule.qname);
306		break;
307	case PF_RULESET_NAT:
308		/*
309		 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
310		 */
311		pfr.rule.action = PF_NAT;
312		break;
313	case PF_RULESET_RDR:
314		/*
315		 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
316		 */
317		pfr.rule.action = PF_RDR;
318		break;
319	default:
320		errno = EINVAL;
321		return (-1);
322	}
323
324	return (0);
325}
326
327int
328server_lookup(struct sockaddr *client, struct sockaddr *proxy,
329    struct sockaddr *server, u_int8_t proto)
330{
331	if (client->sa_family == AF_INET)
332		return (server_lookup4(satosin(client), satosin(proxy),
333		    satosin(server), proto));
334
335	if (client->sa_family == AF_INET6)
336		return (server_lookup6(satosin6(client), satosin6(proxy),
337		    satosin6(server), proto));
338
339	errno = EPROTONOSUPPORT;
340	return (-1);
341}
342
343int
344server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
345    struct sockaddr_in *server, u_int8_t proto)
346{
347	struct pfioc_natlook pnl;
348
349	memset(&pnl, 0, sizeof pnl);
350	pnl.direction = PF_OUT;
351	pnl.af = AF_INET;
352	pnl.proto = proto;
353	memcpy(&pnl.saddr.v4, &client->sin_addr.s_addr, sizeof pnl.saddr.v4);
354	memcpy(&pnl.daddr.v4, &proxy->sin_addr.s_addr, sizeof pnl.daddr.v4);
355	pnl.sport = client->sin_port;
356	pnl.dport = proxy->sin_port;
357
358	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
359		return (-1);
360
361	memset(server, 0, sizeof(struct sockaddr_in));
362	server->sin_len = sizeof(struct sockaddr_in);
363	server->sin_family = AF_INET;
364	memcpy(&server->sin_addr.s_addr, &pnl.rdaddr.v4,
365	    sizeof server->sin_addr.s_addr);
366	server->sin_port = pnl.rdport;
367
368	return (0);
369}
370
371int
372server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
373    struct sockaddr_in6 *server, u_int8_t proto)
374{
375	struct pfioc_natlook pnl;
376
377	memset(&pnl, 0, sizeof pnl);
378	pnl.direction = PF_OUT;
379	pnl.af = AF_INET6;
380	pnl.proto = proto;
381	memcpy(&pnl.saddr.v6, &client->sin6_addr.s6_addr, sizeof pnl.saddr.v6);
382	memcpy(&pnl.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof pnl.daddr.v6);
383	pnl.sport = client->sin6_port;
384	pnl.dport = proxy->sin6_port;
385
386	if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
387		return (-1);
388
389	memset(server, 0, sizeof(struct sockaddr_in6));
390	server->sin6_len = sizeof(struct sockaddr_in6);
391	server->sin6_family = AF_INET6;
392	memcpy(&server->sin6_addr.s6_addr, &pnl.rdaddr.v6,
393	    sizeof server->sin6_addr);
394	server->sin6_port = pnl.rdport;
395
396	return (0);
397}
398