1/*	$OpenBSD: filter.c,v 1.8 2008/06/13 07:25:26 claudio 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 <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
43enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
44
45int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
46    u_int16_t);
47int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
48    struct sockaddr_in *);
49int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
50    struct sockaddr_in6 *);
51
52static struct pfioc_pooladdr	pfp;
53static struct pfctl_rule	pfrule;
54static char			pfanchor[PF_ANCHOR_NAME_SIZE];
55static char			pfanchor_call[PF_ANCHOR_NAME_SIZE];
56static uint32_t			pfticket;
57static uint32_t			pfpool_ticket;
58static struct pfioc_trans	pft;
59static struct pfioc_trans_e	pfte[TRANS_SIZE];
60static int rule_log;
61static struct pfctl_handle *pfh = NULL;
62static const char *qname, *tagname;
63
64int
65add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
66    struct sockaddr *dst, u_int16_t d_port)
67{
68	if (!src || !dst || !d_port) {
69		errno = EINVAL;
70		return (-1);
71	}
72
73	if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port) == -1)
74		return (-1);
75
76	pfrule.direction = dir;
77	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
78	    pfticket, pfpool_ticket))
79		return (-1);
80
81	return (0);
82}
83
84int
85add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
86    u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
87    u_int16_t nat_range_high)
88{
89	if (!src || !dst || !d_port || !nat || !nat_range_low ||
90	    (src->sa_family != nat->sa_family)) {
91		errno = EINVAL;
92		return (-1);
93	}
94
95	if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port) == -1)
96		return (-1);
97
98	if (nat->sa_family == AF_INET) {
99		memcpy(&pfp.addr.addr.v.a.addr.v4,
100		    &satosin(nat)->sin_addr.s_addr, 4);
101		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
102	} else {
103		memcpy(&pfp.addr.addr.v.a.addr.v6,
104		    &satosin6(nat)->sin6_addr.s6_addr, 16);
105		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
106	}
107	if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
108		return (-1);
109
110	pfrule.rpool.proxy_port[0] = nat_range_low;
111	pfrule.rpool.proxy_port[1] = nat_range_high;
112	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
113	    pfticket, pfpool_ticket))
114		return (-1);
115
116	return (0);
117}
118
119int
120add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
121    u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port)
122{
123	if (!src || !dst || !d_port || !rdr || !rdr_port ||
124	    (src->sa_family != rdr->sa_family)) {
125		errno = EINVAL;
126		return (-1);
127	}
128
129	if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port) == -1)
130		return (-1);
131
132	if (rdr->sa_family == AF_INET) {
133		memcpy(&pfp.addr.addr.v.a.addr.v4,
134		    &satosin(rdr)->sin_addr.s_addr, 4);
135		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
136	} else {
137		memcpy(&pfp.addr.addr.v.a.addr.v6,
138		    &satosin6(rdr)->sin6_addr.s6_addr, 16);
139		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
140	}
141	if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
142		return (-1);
143
144	pfrule.rpool.proxy_port[0] = rdr_port;
145	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
146	    pfticket, pfpool_ticket))
147		return (-1);
148
149	return (0);
150}
151
152int
153do_commit(void)
154{
155	if (ioctl(pfctl_fd(pfh), DIOCXCOMMIT, &pft) == -1)
156		return (-1);
157
158	return (0);
159}
160
161int
162do_rollback(void)
163{
164	if (ioctl(pfctl_fd(pfh), DIOCXROLLBACK, &pft) == -1)
165		return (-1);
166
167	return (0);
168}
169
170void
171init_filter(const char *opt_qname, const char *opt_tagname, int opt_verbose)
172{
173	struct pfctl_status *status;
174
175	qname = opt_qname;
176	tagname = opt_tagname;
177
178	if (opt_verbose == 1)
179		rule_log = PF_LOG;
180	else if (opt_verbose == 2)
181		rule_log = PF_LOG_ALL;
182
183	pfh = pfctl_open(PF_DEVICE);
184	if (pfh == NULL)
185		err(1, "pfctl_open");
186	status = pfctl_get_status_h(pfh);
187	if (status == NULL)
188		err(1, "DIOCGETSTATUS");
189	if (!status->running)
190		errx(1, "pf is disabled");
191
192	pfctl_free_status(status);
193}
194
195int
196prepare_commit(u_int32_t id)
197{
198	char an[PF_ANCHOR_NAME_SIZE];
199	int i;
200
201	memset(&pft, 0, sizeof pft);
202	pft.size = TRANS_SIZE;
203	pft.esize = sizeof pfte[0];
204	pft.array = pfte;
205
206	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
207	    getpid(), id);
208	for (i = 0; i < TRANS_SIZE; i++) {
209		memset(&pfte[i], 0, sizeof pfte[0]);
210		strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
211		switch (i) {
212		case TRANS_FILTER:
213			pfte[i].rs_num = PF_RULESET_FILTER;
214			break;
215		case TRANS_NAT:
216			pfte[i].rs_num = PF_RULESET_NAT;
217			break;
218		case TRANS_RDR:
219			pfte[i].rs_num = PF_RULESET_RDR;
220			break;
221		default:
222			errno = EINVAL;
223			return (-1);
224		}
225	}
226
227	if (ioctl(pfctl_fd(pfh), DIOCXBEGIN, &pft) == -1)
228		return (-1);
229
230	return (0);
231}
232
233int
234prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
235    struct sockaddr *dst, u_int16_t d_port)
236{
237	char an[PF_ANCHOR_NAME_SIZE];
238
239	if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
240	    (src->sa_family != dst->sa_family)) {
241	    	errno = EPROTONOSUPPORT;
242		return (-1);
243	}
244
245	memset(&pfp, 0, sizeof pfp);
246	memset(&pfrule, 0, sizeof pfrule);
247	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
248	    getpid(), id);
249	strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
250	strlcpy(pfanchor, an, PF_ANCHOR_NAME_SIZE);
251
252	switch (rs_num) {
253	case PF_RULESET_FILTER:
254		pfticket = pfte[TRANS_FILTER].ticket;
255		break;
256	case PF_RULESET_NAT:
257		pfticket = pfte[TRANS_NAT].ticket;
258		break;
259	case PF_RULESET_RDR:
260		pfticket = pfte[TRANS_RDR].ticket;
261		break;
262	default:
263		errno = EINVAL;
264		return (-1);
265	}
266	if (ioctl(pfctl_fd(pfh), DIOCBEGINADDRS, &pfp) == -1)
267		return (-1);
268	pfpool_ticket = pfp.ticket;
269
270	/* Generic for all rule types. */
271	pfrule.af = src->sa_family;
272	pfrule.proto = IPPROTO_TCP;
273	pfrule.src.addr.type = PF_ADDR_ADDRMASK;
274	pfrule.dst.addr.type = PF_ADDR_ADDRMASK;
275	if (src->sa_family == AF_INET) {
276		memcpy(&pfrule.src.addr.v.a.addr.v4,
277		    &satosin(src)->sin_addr.s_addr, 4);
278		memset(&pfrule.src.addr.v.a.mask.addr8, 255, 4);
279		memcpy(&pfrule.dst.addr.v.a.addr.v4,
280		    &satosin(dst)->sin_addr.s_addr, 4);
281		memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 4);
282	} else {
283		memcpy(&pfrule.src.addr.v.a.addr.v6,
284		    &satosin6(src)->sin6_addr.s6_addr, 16);
285		memset(&pfrule.src.addr.v.a.mask.addr8, 255, 16);
286		memcpy(&pfrule.dst.addr.v.a.addr.v6,
287		    &satosin6(dst)->sin6_addr.s6_addr, 16);
288		memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 16);
289	}
290	pfrule.dst.port_op = PF_OP_EQ;
291	pfrule.dst.port[0] = htons(d_port);
292
293	switch (rs_num) {
294	case PF_RULESET_FILTER:
295		/*
296		 * pass [quick] [log] inet[6] proto tcp \
297		 *     from $src to $dst port = $d_port flags S/SA keep state
298		 *     (max 1) [queue qname] [tag tagname]
299		 */
300		pfrule.action = PF_PASS;
301		pfrule.quick = 1;
302		pfrule.log = rule_log;
303		pfrule.keep_state = 1;
304		pfrule.flags = TH_SYN;
305		pfrule.flagset = (TH_SYN|TH_ACK);
306		pfrule.max_states = 1;
307		if (qname != NULL)
308			strlcpy(pfrule.qname, qname, sizeof pfrule.qname);
309		if (tagname != NULL) {
310			pfrule.quick = 0;
311			strlcpy(pfrule.tagname, tagname,
312                                sizeof pfrule.tagname);
313		}
314		break;
315	case PF_RULESET_NAT:
316		/*
317		 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
318		 */
319		pfrule.action = PF_NAT;
320		break;
321	case PF_RULESET_RDR:
322		/*
323		 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
324		 */
325		pfrule.action = PF_RDR;
326		break;
327	default:
328		errno = EINVAL;
329		return (-1);
330	}
331
332	return (0);
333}
334
335int
336server_lookup(struct sockaddr *client, struct sockaddr *proxy,
337    struct sockaddr *server)
338{
339	if (client->sa_family == AF_INET)
340		return (server_lookup4(satosin(client), satosin(proxy),
341		    satosin(server)));
342
343	if (client->sa_family == AF_INET6)
344		return (server_lookup6(satosin6(client), satosin6(proxy),
345		    satosin6(server)));
346
347	errno = EPROTONOSUPPORT;
348	return (-1);
349}
350
351int
352server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
353    struct sockaddr_in *server)
354{
355	struct pfctl_natlook_key k = {};
356	struct pfctl_natlook r = {};
357
358	k.direction = PF_OUT;
359	k.af = AF_INET;
360	k.proto = IPPROTO_TCP;
361	memcpy(&k.saddr.v4, &client->sin_addr.s_addr, sizeof(k.saddr.v4));
362	memcpy(&k.daddr.v4, &proxy->sin_addr.s_addr, sizeof(k.daddr.v4));
363	k.sport = client->sin_port;
364	k.dport = proxy->sin_port;
365
366	if (pfctl_natlook(pfh, &k, &r))
367		return (-1);
368
369	memset(server, 0, sizeof(struct sockaddr_in));
370	server->sin_len = sizeof(struct sockaddr_in);
371	server->sin_family = AF_INET;
372	memcpy(&server->sin_addr.s_addr, &r.daddr.v4,
373	    sizeof(server->sin_addr.s_addr));
374	server->sin_port = r.dport;
375
376	return (0);
377}
378
379int
380server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
381    struct sockaddr_in6 *server)
382{
383	struct pfctl_natlook_key k = {};
384	struct pfctl_natlook r = {};
385
386	k.direction = PF_OUT;
387	k.af = AF_INET6;
388	k.proto = IPPROTO_TCP;
389	memcpy(&k.saddr.v6, &client->sin6_addr.s6_addr, sizeof(k.saddr.v6));
390	memcpy(&k.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof(k.daddr.v6));
391	k.sport = client->sin6_port;
392	k.dport = proxy->sin6_port;
393
394	if (pfctl_natlook(pfh, &k, &r))
395		return (-1);
396
397	memset(server, 0, sizeof(struct sockaddr_in6));
398	server->sin6_len = sizeof(struct sockaddr_in6);
399	server->sin6_family = AF_INET6;
400	memcpy(&server->sin6_addr.s6_addr, &r.daddr.v6,
401	    sizeof(server->sin6_addr));
402	server->sin6_port = r.dport;
403
404	return (0);
405}
406