1/*	$OpenBSD: filter.c,v 1.1 2005/12/28 19:07:07 jcs Exp $ */
2/*	$FreeBSD$ */
3
4/*
5 * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#include <syslog.h>
21
22#include <sys/ioctl.h>
23#include <sys/types.h>
24#include <sys/socket.h>
25
26#include <net/if.h>
27#include <net/pfvar.h>
28#include <netinet/in.h>
29#include <netinet/tcp.h>
30#include <arpa/inet.h>
31
32#include <err.h>
33#include <errno.h>
34#include <fcntl.h>
35#include <libpfctl.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <string.h>
39#include <unistd.h>
40
41#include "filter.h"
42
43/* From netinet/in.h, but only _KERNEL_ gets them. */
44#define satosin(sa)	((struct sockaddr_in *)(sa))
45#define satosin6(sa)	((struct sockaddr_in6 *)(sa))
46
47enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
48
49int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
50    u_int16_t, u_int8_t);
51int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
52    struct sockaddr_in *, u_int8_t);
53int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
54    struct sockaddr_in6 *, u_int8_t);
55
56static struct pfioc_pooladdr	pfp;
57static struct pfctl_rule	pfrule;
58static uint32_t			pfticket;
59static uint32_t			pfpool_ticket;
60static char			pfanchor[PF_ANCHOR_NAME_SIZE];
61static char			pfanchor_call[PF_ANCHOR_NAME_SIZE];
62static struct pfioc_trans	pft;
63static struct pfioc_trans_e	pfte[TRANS_SIZE];
64static int rule_log;
65static struct pfctl_handle *pfh = NULL;
66static char *qname;
67
68int
69add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
70    struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
71{
72	if (!src || !dst || !d_port || !proto) {
73		errno = EINVAL;
74		return (-1);
75	}
76
77	if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port, proto) == -1)
78		return (-1);
79
80	pfrule.direction = dir;
81	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
82	    pfticket, pfpool_ticket))
83		return (-1);
84
85	return (0);
86}
87
88int
89add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
90    u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
91    u_int16_t nat_range_high, u_int8_t proto)
92{
93	if (!src || !dst || !d_port || !nat || !nat_range_low || !proto ||
94	    (src->sa_family != nat->sa_family)) {
95		errno = EINVAL;
96		return (-1);
97	}
98
99	if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port, proto) == -1)
100		return (-1);
101
102	if (nat->sa_family == AF_INET) {
103		memcpy(&pfp.addr.addr.v.a.addr.v4,
104		    &satosin(nat)->sin_addr.s_addr, 4);
105		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
106	} else {
107		memcpy(&pfp.addr.addr.v.a.addr.v6,
108		    &satosin6(nat)->sin6_addr.s6_addr, 16);
109		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
110	}
111	if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
112		return (-1);
113
114	pfrule.rpool.proxy_port[0] = nat_range_low;
115	pfrule.rpool.proxy_port[1] = nat_range_high;
116	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
117	    pfticket, pfpool_ticket))
118		return (-1);
119
120	return (0);
121}
122
123int
124add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
125    u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port, u_int8_t proto)
126{
127	if (!src || !dst || !d_port || !rdr || !rdr_port || !proto ||
128	    (src->sa_family != rdr->sa_family)) {
129		errno = EINVAL;
130		return (-1);
131	}
132
133	if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port, proto) == -1)
134		return (-1);
135
136	if (rdr->sa_family == AF_INET) {
137		memcpy(&pfp.addr.addr.v.a.addr.v4,
138		    &satosin(rdr)->sin_addr.s_addr, 4);
139		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
140	} else {
141		memcpy(&pfp.addr.addr.v.a.addr.v6,
142		    &satosin6(rdr)->sin6_addr.s6_addr, 16);
143		memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
144	}
145	if (ioctl(pfctl_fd(pfh), DIOCADDADDR, &pfp) == -1)
146		return (-1);
147
148	pfrule.rpool.proxy_port[0] = rdr_port;
149	if (pfctl_add_rule_h(pfh, &pfrule, pfanchor, pfanchor_call,
150	    pfticket, pfpool_ticket))
151		return (-1);
152
153	return (0);
154}
155
156int
157do_commit(void)
158{
159	if (ioctl(pfctl_fd(pfh), DIOCXCOMMIT, &pft) == -1)
160		return (-1);
161
162	return (0);
163}
164
165int
166do_rollback(void)
167{
168	if (ioctl(pfctl_fd(pfh), DIOCXROLLBACK, &pft) == -1)
169		return (-1);
170
171	return (0);
172}
173
174void
175init_filter(char *opt_qname, int opt_verbose)
176{
177	struct pfctl_status *status;
178
179	qname = opt_qname;
180
181	if (opt_verbose == 1)
182		rule_log = PF_LOG;
183	else if (opt_verbose == 2)
184		rule_log = PF_LOG_ALL;
185
186	pfh = pfctl_open(PF_DEVICE);
187	if (pfh == NULL) {
188		syslog(LOG_ERR, "can't pfctl_open()");
189		exit(1);
190	}
191	status = pfctl_get_status_h(pfh);
192	if (status == NULL) {
193		syslog(LOG_ERR, "DIOCGETSTATUS");
194		exit(1);
195	}
196	if (!status->running) {
197		syslog(LOG_ERR, "pf is disabled");
198		exit(1);
199	}
200
201	pfctl_free_status(status);
202}
203
204int
205prepare_commit(u_int32_t id)
206{
207	char an[PF_ANCHOR_NAME_SIZE];
208	int i;
209
210	memset(&pft, 0, sizeof pft);
211	pft.size = TRANS_SIZE;
212	pft.esize = sizeof pfte[0];
213	pft.array = pfte;
214
215	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
216	    getpid(), id);
217	for (i = 0; i < TRANS_SIZE; i++) {
218		memset(&pfte[i], 0, sizeof pfte[0]);
219		strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
220		switch (i) {
221		case TRANS_FILTER:
222			pfte[i].rs_num = PF_RULESET_FILTER;
223			break;
224		case TRANS_NAT:
225			pfte[i].rs_num = PF_RULESET_NAT;
226			break;
227		case TRANS_RDR:
228			pfte[i].rs_num = PF_RULESET_RDR;
229			break;
230		default:
231			errno = EINVAL;
232			return (-1);
233		}
234	}
235
236	if (ioctl(pfctl_fd(pfh), DIOCXBEGIN, &pft) == -1)
237		return (-1);
238
239	return (0);
240}
241
242int
243prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
244    struct sockaddr *dst, u_int16_t d_port, u_int8_t proto)
245{
246	char an[PF_ANCHOR_NAME_SIZE];
247
248	if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
249	    (src->sa_family != dst->sa_family)) {
250	    	errno = EPROTONOSUPPORT;
251		return (-1);
252	}
253
254	memset(&pfp, 0, sizeof pfp);
255	memset(&pfrule, 0, sizeof pfrule);
256	snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
257	    getpid(), id);
258	strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
259	strlcpy(pfanchor, an, PF_ANCHOR_NAME_SIZE);
260
261	switch (rs_num) {
262	case PF_RULESET_FILTER:
263		pfticket = pfte[TRANS_FILTER].ticket;
264		break;
265	case PF_RULESET_NAT:
266		pfticket = pfte[TRANS_NAT].ticket;
267		break;
268	case PF_RULESET_RDR:
269		pfticket = pfte[TRANS_RDR].ticket;
270		break;
271	default:
272		errno = EINVAL;
273		return (-1);
274	}
275	if (ioctl(pfctl_fd(pfh), DIOCBEGINADDRS, &pfp) == -1)
276		return (-1);
277	pfpool_ticket = pfp.ticket;
278
279	/* Generic for all rule types. */
280	pfrule.af = src->sa_family;
281	pfrule.proto = proto;
282	pfrule.src.addr.type = PF_ADDR_ADDRMASK;
283	pfrule.dst.addr.type = PF_ADDR_ADDRMASK;
284	if (src->sa_family == AF_INET) {
285		memcpy(&pfrule.src.addr.v.a.addr.v4,
286		    &satosin(src)->sin_addr.s_addr, 4);
287		memset(&pfrule.src.addr.v.a.mask.addr8, 255, 4);
288		memcpy(&pfrule.dst.addr.v.a.addr.v4,
289		    &satosin(dst)->sin_addr.s_addr, 4);
290		memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 4);
291	} else {
292		memcpy(&pfrule.src.addr.v.a.addr.v6,
293		    &satosin6(src)->sin6_addr.s6_addr, 16);
294		memset(&pfrule.src.addr.v.a.mask.addr8, 255, 16);
295		memcpy(&pfrule.dst.addr.v.a.addr.v6,
296		    &satosin6(dst)->sin6_addr.s6_addr, 16);
297		memset(&pfrule.dst.addr.v.a.mask.addr8, 255, 16);
298	}
299	pfrule.dst.port_op = PF_OP_EQ;
300	pfrule.dst.port[0] = htons(d_port);
301
302	switch (rs_num) {
303	case PF_RULESET_FILTER:
304		/*
305		 * pass quick [log] inet[6] proto tcp \
306		 *     from $src to $dst port = $d_port flags S/SAFR keep state
307		 *     (max 1) [queue qname]
308		 */
309		pfrule.action = PF_PASS;
310		pfrule.quick = 1;
311		pfrule.log = rule_log;
312		pfrule.keep_state = 1;
313#ifdef __FreeBSD__
314		pfrule.flags = (proto == IPPROTO_TCP ? TH_SYN : 0);
315		pfrule.flagset = (proto == IPPROTO_TCP ?
316		    (TH_SYN|TH_ACK|TH_FIN|TH_RST) : 0);
317#else
318		pfrule.flags = (proto == IPPROTO_TCP ? TH_SYN : NULL);
319		pfrule.flagset = (proto == IPPROTO_TCP ?
320		    (TH_SYN|TH_ACK|TH_FIN|TH_RST) : NULL);
321#endif
322		pfrule.max_states = 1;
323		if (qname != NULL)
324			strlcpy(pfrule.qname, qname, sizeof pfrule.qname);
325		break;
326	case PF_RULESET_NAT:
327		/*
328		 * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
329		 */
330		pfrule.action = PF_NAT;
331		break;
332	case PF_RULESET_RDR:
333		/*
334		 * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
335		 */
336		pfrule.action = PF_RDR;
337		break;
338	default:
339		errno = EINVAL;
340		return (-1);
341	}
342
343	return (0);
344}
345
346int
347server_lookup(struct sockaddr *client, struct sockaddr *proxy,
348    struct sockaddr *server, u_int8_t proto)
349{
350	if (client->sa_family == AF_INET)
351		return (server_lookup4(satosin(client), satosin(proxy),
352		    satosin(server), proto));
353
354	if (client->sa_family == AF_INET6)
355		return (server_lookup6(satosin6(client), satosin6(proxy),
356		    satosin6(server), proto));
357
358	errno = EPROTONOSUPPORT;
359	return (-1);
360}
361
362int
363server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
364    struct sockaddr_in *server, u_int8_t proto)
365{
366	struct pfctl_natlook_key k = {};
367	struct pfctl_natlook r = {};
368
369	k.direction = PF_OUT;
370	k.af = AF_INET;
371	k.proto = proto;
372	memcpy(&k.saddr.v4, &client->sin_addr.s_addr, sizeof(k.saddr.v4));
373	memcpy(&k.daddr.v4, &proxy->sin_addr.s_addr, sizeof(k.daddr.v4));
374	k.sport = client->sin_port;
375	k.dport = proxy->sin_port;
376
377	if (pfctl_natlook(pfh, &k, &r))
378		return (-1);
379
380	memset(server, 0, sizeof(struct sockaddr_in));
381	server->sin_len = sizeof(struct sockaddr_in);
382	server->sin_family = AF_INET;
383	memcpy(&server->sin_addr.s_addr, &r.daddr.v4,
384	    sizeof server->sin_addr.s_addr);
385	server->sin_port = r.dport;
386
387	return (0);
388}
389
390int
391server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
392    struct sockaddr_in6 *server, u_int8_t proto)
393{
394	struct pfctl_natlook_key k = {};
395	struct pfctl_natlook r = {};
396
397	k.direction = PF_OUT;
398	k.af = AF_INET6;
399	k.proto = proto;
400	memcpy(&k.saddr.v6, &client->sin6_addr.s6_addr, sizeof k.saddr.v6);
401	memcpy(&k.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof k.daddr.v6);
402	k.sport = client->sin6_port;
403	k.dport = proxy->sin6_port;
404
405	if (pfctl_natlook(pfh, &k, &r))
406		return (-1);
407
408	memset(server, 0, sizeof(struct sockaddr_in6));
409	server->sin6_len = sizeof(struct sockaddr_in6);
410	server->sin6_family = AF_INET6;
411	memcpy(&server->sin6_addr.s6_addr, &r.daddr.v6,
412	    sizeof server->sin6_addr);
413	server->sin6_port = r.dport;
414
415	return (0);
416}
417