filter.c revision 171169 
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
42enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
43
44int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
45    u_int16_t);
46int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
47    struct sockaddr_in *);
48int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
49    struct sockaddr_in6 *);
50
51static struct pfioc_pooladdr	pfp;
52static struct pfioc_rule	pfr;
53static struct pfioc_trans	pft;
54static struct pfioc_trans_e	pfte[TRANS_SIZE];
55static int dev, rule_log;
56static char *qname;
57
58int
59add_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
77int
78add_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
111int
112add_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
143int
144do_commit(void)
145{
146	if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
147		return (-1);
148
149	return (0);
150}
151
152int
153do_rollback(void)
154{
155	if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
156		return (-1);
157
158	return (0);
159}
160
161void
162init_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
182int
183prepare_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
220int
221prepare_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
317int
318server_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
333int
334server_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
361int
362server_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