1 /*-
2 * Copyright (c) 2004 Andre Oppermann, Internet Business Solutions AG
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29
30 #include "opt_ipfw.h"
31 #include "opt_inet.h"
32 #include "opt_inet6.h"
33 #ifndef INET
34 #error IPFIREWALL requires INET.
35 #endif /* INET */
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/malloc.h>
40 #include <sys/mbuf.h>
41 #include <sys/module.h>
42 #include <sys/kernel.h>
43 #include <sys/lock.h>
44 #include <sys/rwlock.h>
45 #include <sys/socket.h>
46 #include <sys/sysctl.h>
47
48 #include <net/if.h>
49 #include <net/route.h>
50 #include <net/ethernet.h>
51 #include <net/pfil.h>
52 #include <net/vnet.h>
53
54 #include <netinet/in.h>
55 #include <netinet/in_systm.h>
56 #include <netinet/ip.h>
57 #include <netinet/ip_var.h>
58 #include <netinet/ip_fw.h>
59 #ifdef INET6
60 #include <netinet/ip6.h>
61 #include <netinet6/ip6_var.h>
62 #include <netinet6/scope6_var.h>
63 #endif
64
65 #include <netgraph/ng_ipfw.h>
66
67 #include <netpfil/ipfw/ip_fw_private.h>
68
69 #include <machine/in_cksum.h>
70
71 static VNET_DEFINE(int, fw_enable) = 1;
72 #define V_fw_enable VNET(fw_enable)
73
74 #ifdef INET6
75 static VNET_DEFINE(int, fw6_enable) = 1;
76 #define V_fw6_enable VNET(fw6_enable)
77 #endif
78
79 static VNET_DEFINE(int, fwlink_enable) = 0;
80 #define V_fwlink_enable VNET(fwlink_enable)
81
82 int ipfw_chg_hook(SYSCTL_HANDLER_ARGS);
83
84 /* Forward declarations. */
85 static int ipfw_divert(struct mbuf **, int, struct ipfw_rule_ref *, int);
86 int ipfw_check_packet(void *, struct mbuf **, struct ifnet *, int,
87 struct inpcb *);
88 int ipfw_check_frame(void *, struct mbuf **, struct ifnet *, int,
89 struct inpcb *);
90
91 #ifdef SYSCTL_NODE
92
93 SYSBEGIN(f1)
94
95 SYSCTL_DECL(_net_inet_ip_fw);
96 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, enable,
97 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
98 &VNET_NAME(fw_enable), 0, ipfw_chg_hook, "I", "Enable ipfw");
99 #ifdef INET6
100 SYSCTL_DECL(_net_inet6_ip6_fw);
101 SYSCTL_PROC(_net_inet6_ip6_fw, OID_AUTO, enable,
102 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
103 &VNET_NAME(fw6_enable), 0, ipfw_chg_hook, "I", "Enable ipfw+6");
104 #endif /* INET6 */
105
106 SYSCTL_DECL(_net_link_ether);
107 SYSCTL_PROC(_net_link_ether, OID_AUTO, ipfw,
108 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3,
109 &VNET_NAME(fwlink_enable), 0, ipfw_chg_hook, "I",
110 "Pass ether pkts through firewall");
111
112 SYSEND
113
114 #endif /* SYSCTL_NODE */
115
116 /*
117 * The pfilter hook to pass packets to ipfw_chk and then to
118 * dummynet, divert, netgraph or other modules.
119 * The packet may be consumed.
120 */
121 int
ipfw_check_packet(void * arg,struct mbuf ** m0,struct ifnet * ifp,int dir,struct inpcb * inp)122 ipfw_check_packet(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
123 struct inpcb *inp)
124 {
125 struct ip_fw_args args;
126 struct m_tag *tag;
127 int ipfw, ret;
128
129 /* convert dir to IPFW values */
130 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT;
131 args.flags = 0;
132 again:
133 /*
134 * extract and remove the tag if present. If we are left
135 * with onepass, optimize the outgoing path.
136 */
137 tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL);
138 if (tag != NULL) {
139 args.rule = *((struct ipfw_rule_ref *)(tag+1));
140 m_tag_delete(*m0, tag);
141 if (args.rule.info & IPFW_ONEPASS)
142 return (0);
143 args.flags |= IPFW_ARGS_REF;
144 }
145
146 args.m = *m0;
147 args.oif = dir == DIR_OUT ? ifp : NULL;
148 args.inp = inp;
149
150 ipfw = ipfw_chk(&args);
151 *m0 = args.m;
152
153 KASSERT(*m0 != NULL || ipfw == IP_FW_DENY ||
154 ipfw == IP_FW_NAT64, ("%s: m0 is NULL", __func__));
155
156 /* breaking out of the switch means drop */
157 switch (ipfw) {
158 case IP_FW_PASS:
159 /* next_hop may be set by ipfw_chk */
160 if ((args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR |
161 IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) == 0) {
162 ret = 0;
163 break;
164 }
165 #if (!defined(INET6) && !defined(INET))
166 ret = EACCES;
167 #else
168 {
169 void *psa;
170 size_t len;
171 #ifdef INET
172 if (args.flags & (IPFW_ARGS_NH4 | IPFW_ARGS_NH4PTR)) {
173 MPASS((args.flags & (IPFW_ARGS_NH4 |
174 IPFW_ARGS_NH4PTR)) != (IPFW_ARGS_NH4 |
175 IPFW_ARGS_NH4PTR));
176 MPASS((args.flags & (IPFW_ARGS_NH6 |
177 IPFW_ARGS_NH6PTR)) == 0);
178 len = sizeof(struct sockaddr_in);
179 psa = (args.flags & IPFW_ARGS_NH4) ?
180 &args.hopstore : args.next_hop;
181 if (in_localip(satosin(psa)->sin_addr))
182 (*m0)->m_flags |= M_FASTFWD_OURS;
183 (*m0)->m_flags |= M_IP_NEXTHOP;
184 }
185 #endif /* INET */
186 #ifdef INET6
187 if (args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) {
188 MPASS((args.flags & (IPFW_ARGS_NH6 |
189 IPFW_ARGS_NH6PTR)) != (IPFW_ARGS_NH6 |
190 IPFW_ARGS_NH6PTR));
191 MPASS((args.flags & (IPFW_ARGS_NH4 |
192 IPFW_ARGS_NH4PTR)) == 0);
193 len = sizeof(struct sockaddr_in6);
194 psa = args.next_hop6;
195 (*m0)->m_flags |= M_IP6_NEXTHOP;
196 }
197 #endif /* INET6 */
198 /*
199 * Incoming packets should not be tagged so we do not
200 * m_tag_find. Outgoing packets may be tagged, so we
201 * reuse the tag if present.
202 */
203 tag = (dir == DIR_IN) ? NULL :
204 m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL);
205 if (tag != NULL) {
206 m_tag_unlink(*m0, tag);
207 } else {
208 tag = m_tag_get(PACKET_TAG_IPFORWARD, len,
209 M_NOWAIT);
210 if (tag == NULL) {
211 ret = EACCES;
212 break; /* i.e. drop */
213 }
214 }
215 if ((args.flags & IPFW_ARGS_NH6) == 0)
216 bcopy(psa, tag + 1, len);
217 m_tag_prepend(*m0, tag);
218 ret = 0;
219 #ifdef INET6
220 /* IPv6 next hop needs additional handling */
221 if (args.flags & (IPFW_ARGS_NH6 | IPFW_ARGS_NH6PTR)) {
222 struct sockaddr_in6 *sa6;
223
224 sa6 = satosin6(tag + 1);
225 if (args.flags & IPFW_ARGS_NH6) {
226 sa6->sin6_family = AF_INET6;
227 sa6->sin6_len = sizeof(*sa6);
228 sa6->sin6_addr = args.hopstore6.sin6_addr;
229 sa6->sin6_port = args.hopstore6.sin6_port;
230 sa6->sin6_scope_id =
231 args.hopstore6.sin6_scope_id;
232 }
233 /*
234 * If nh6 address is link-local we should convert
235 * it to kernel internal form before doing any
236 * comparisons.
237 */
238 if (sa6_embedscope(sa6, V_ip6_use_defzone) != 0) {
239 ret = EACCES;
240 break;
241 }
242 if (in6_localip(&sa6->sin6_addr))
243 (*m0)->m_flags |= M_FASTFWD_OURS;
244 }
245 #endif /* INET6 */
246 }
247 #endif /* INET || INET6 */
248 break;
249
250 case IP_FW_DENY:
251 ret = EACCES;
252 break; /* i.e. drop */
253
254 case IP_FW_DUMMYNET:
255 ret = EACCES;
256 if (ip_dn_io_ptr == NULL)
257 break; /* i.e. drop */
258 MPASS(args.flags & IPFW_ARGS_REF);
259 if (mtod(*m0, struct ip *)->ip_v == 4)
260 ret = ip_dn_io_ptr(m0, dir, &args);
261 else if (mtod(*m0, struct ip *)->ip_v == 6)
262 ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args);
263 else
264 break; /* drop it */
265 /*
266 * XXX should read the return value.
267 * dummynet normally eats the packet and sets *m0=NULL
268 * unless the packet can be sent immediately. In this
269 * case args is updated and we should re-run the
270 * check without clearing args.
271 */
272 if (*m0 != NULL)
273 goto again;
274 break;
275
276 case IP_FW_TEE:
277 case IP_FW_DIVERT:
278 if (ip_divert_ptr == NULL) {
279 ret = EACCES;
280 break; /* i.e. drop */
281 }
282 MPASS(args.flags & IPFW_ARGS_REF);
283 ret = ipfw_divert(m0, dir, &args.rule,
284 (ipfw == IP_FW_TEE) ? 1 : 0);
285 /* continue processing for the original packet (tee). */
286 if (*m0)
287 goto again;
288 break;
289
290 case IP_FW_NGTEE:
291 case IP_FW_NETGRAPH:
292 if (ng_ipfw_input_p == NULL) {
293 ret = EACCES;
294 break; /* i.e. drop */
295 }
296 MPASS(args.flags & IPFW_ARGS_REF);
297 ret = ng_ipfw_input_p(m0, dir, &args,
298 (ipfw == IP_FW_NGTEE) ? 1 : 0);
299 if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */
300 goto again; /* continue with packet */
301 break;
302
303 case IP_FW_NAT:
304 /* honor one-pass in case of successful nat */
305 if (V_fw_one_pass) {
306 ret = 0;
307 break;
308 }
309 goto again;
310
311 case IP_FW_REASS:
312 goto again; /* continue with packet */
313
314 case IP_FW_NAT64:
315 ret = 0;
316 break;
317
318 default:
319 KASSERT(0, ("%s: unknown retval", __func__));
320 }
321
322 if (ret != 0) {
323 if (*m0)
324 FREE_PKT(*m0);
325 *m0 = NULL;
326 }
327
328 return (ret);
329 }
330
331 /*
332 * ipfw processing for ethernet packets (in and out).
333 */
334 int
ipfw_check_frame(void * arg,struct mbuf ** m0,struct ifnet * ifp,int dir,struct inpcb * inp)335 ipfw_check_frame(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir,
336 struct inpcb *inp)
337 {
338 struct ip_fw_args args;
339 struct ether_header save_eh;
340 struct ether_header *eh;
341 struct m_tag *mtag;
342 struct mbuf *m;
343 int i, ret;
344
345 args.flags = IPFW_ARGS_ETHER;
346 again:
347 /* fetch start point from rule, if any. remove the tag if present. */
348 mtag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL);
349 if (mtag != NULL) {
350 args.rule = *((struct ipfw_rule_ref *)(mtag+1));
351 m_tag_delete(*m0, mtag);
352 if (args.rule.info & IPFW_ONEPASS)
353 return (0);
354 args.flags |= IPFW_ARGS_REF;
355 }
356
357 /* I need some amt of data to be contiguous */
358 m = *m0;
359 i = min(m->m_pkthdr.len, max_protohdr);
360 if (m->m_len < i) {
361 m = m_pullup(m, i);
362 if (m == NULL) {
363 *m0 = m;
364 return (0);
365 }
366 }
367 eh = mtod(m, struct ether_header *);
368 save_eh = *eh; /* save copy for restore below */
369 m_adj(m, ETHER_HDR_LEN); /* strip ethernet header */
370
371 args.m = m; /* the packet we are looking at */
372 args.oif = dir == PFIL_OUT ? ifp: NULL; /* destination, if any */
373 args.eh = &save_eh; /* MAC header for bridged/MAC packets */
374 args.inp = inp; /* used by ipfw uid/gid/jail rules */
375 i = ipfw_chk(&args);
376 m = args.m;
377 if (m != NULL) {
378 /*
379 * Restore Ethernet header, as needed, in case the
380 * mbuf chain was replaced by ipfw.
381 */
382 M_PREPEND(m, ETHER_HDR_LEN, M_NOWAIT);
383 if (m == NULL) {
384 *m0 = NULL;
385 return (0);
386 }
387 if (eh != mtod(m, struct ether_header *))
388 bcopy(&save_eh, mtod(m, struct ether_header *),
389 ETHER_HDR_LEN);
390 }
391 *m0 = m;
392
393 ret = 0;
394 /* Check result of ipfw_chk() */
395 switch (i) {
396 case IP_FW_PASS:
397 break;
398
399 case IP_FW_DENY:
400 ret = EACCES;
401 break; /* i.e. drop */
402
403 case IP_FW_DUMMYNET:
404 ret = EACCES;
405
406 if (ip_dn_io_ptr == NULL)
407 break; /* i.e. drop */
408
409 *m0 = NULL;
410 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT;
411 MPASS(args.flags & IPFW_ARGS_REF);
412 ip_dn_io_ptr(&m, dir | PROTO_LAYER2, &args);
413 return 0;
414
415 case IP_FW_NGTEE:
416 case IP_FW_NETGRAPH:
417 if (ng_ipfw_input_p == NULL) {
418 ret = EACCES;
419 break; /* i.e. drop */
420 }
421 MPASS(args.flags & IPFW_ARGS_REF);
422 ret = ng_ipfw_input_p(m0, (dir == PFIL_IN) ? DIR_IN : DIR_OUT,
423 &args, (i == IP_FW_NGTEE) ? 1 : 0);
424 if (i == IP_FW_NGTEE) /* ignore errors for NGTEE */
425 goto again; /* continue with packet */
426 break;
427
428 default:
429 KASSERT(0, ("%s: unknown retval", __func__));
430 }
431
432 if (ret != 0) {
433 if (*m0)
434 FREE_PKT(*m0);
435 *m0 = NULL;
436 }
437
438 return (ret);
439 }
440
441 /* do the divert, return 1 on error 0 on success */
442 static int
ipfw_divert(struct mbuf ** m0,int incoming,struct ipfw_rule_ref * rule,int tee)443 ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule,
444 int tee)
445 {
446 /*
447 * ipfw_chk() has already tagged the packet with the divert tag.
448 * If tee is set, copy packet and return original.
449 * If not tee, consume packet and send it to divert socket.
450 */
451 struct mbuf *clone;
452 struct ip *ip = mtod(*m0, struct ip *);
453 struct m_tag *tag;
454
455 /* Cloning needed for tee? */
456 if (tee == 0) {
457 clone = *m0; /* use the original mbuf */
458 *m0 = NULL;
459 } else {
460 clone = m_dup(*m0, M_NOWAIT);
461 /* If we cannot duplicate the mbuf, we sacrifice the divert
462 * chain and continue with the tee-ed packet.
463 */
464 if (clone == NULL)
465 return 1;
466 }
467
468 /*
469 * Divert listeners can normally handle non-fragmented packets,
470 * but we can only reass in the non-tee case.
471 * This means that listeners on a tee rule may get fragments,
472 * and have to live with that.
473 * Note that we now have the 'reass' ipfw option so if we care
474 * we can do it before a 'tee'.
475 */
476 if (!tee) switch (ip->ip_v) {
477 case IPVERSION:
478 if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) {
479 int hlen;
480 struct mbuf *reass;
481
482 reass = ip_reass(clone); /* Reassemble packet. */
483 if (reass == NULL)
484 return 0; /* not an error */
485 /* if reass = NULL then it was consumed by ip_reass */
486 /*
487 * IP header checksum fixup after reassembly and leave header
488 * in network byte order.
489 */
490 ip = mtod(reass, struct ip *);
491 hlen = ip->ip_hl << 2;
492 ip->ip_sum = 0;
493 if (hlen == sizeof(struct ip))
494 ip->ip_sum = in_cksum_hdr(ip);
495 else
496 ip->ip_sum = in_cksum(reass, hlen);
497 clone = reass;
498 }
499 break;
500 #ifdef INET6
501 case IPV6_VERSION >> 4:
502 {
503 struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *);
504
505 if (ip6->ip6_nxt == IPPROTO_FRAGMENT) {
506 int nxt, off;
507
508 off = sizeof(struct ip6_hdr);
509 nxt = frag6_input(&clone, &off, 0);
510 if (nxt == IPPROTO_DONE)
511 return (0);
512 }
513 break;
514 }
515 #endif
516 }
517
518 /* attach a tag to the packet with the reinject info */
519 tag = m_tag_alloc(MTAG_IPFW_RULE, 0,
520 sizeof(struct ipfw_rule_ref), M_NOWAIT);
521 if (tag == NULL) {
522 FREE_PKT(clone);
523 return 1;
524 }
525 *((struct ipfw_rule_ref *)(tag+1)) = *rule;
526 m_tag_prepend(clone, tag);
527
528 /* Do the dirty job... */
529 ip_divert_ptr(clone, incoming);
530 return 0;
531 }
532
533 /*
534 * attach or detach hooks for a given protocol family
535 */
536 static int
ipfw_hook(int onoff,int pf)537 ipfw_hook(int onoff, int pf)
538 {
539 struct pfil_head *pfh;
540 pfil_func_t hook_func;
541
542 pfh = pfil_head_get(PFIL_TYPE_AF, pf);
543 if (pfh == NULL)
544 return ENOENT;
545
546 hook_func = (pf == AF_LINK) ? ipfw_check_frame : ipfw_check_packet;
547
548 (void) (onoff ? pfil_add_hook : pfil_remove_hook)
549 (hook_func, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh);
550
551 return 0;
552 }
553
554 int
ipfw_attach_hooks(int arg)555 ipfw_attach_hooks(int arg)
556 {
557 int error = 0;
558
559 if (arg == 0) /* detach */
560 ipfw_hook(0, AF_INET);
561 else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) {
562 error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */
563 printf("ipfw_hook() error\n");
564 }
565 #ifdef INET6
566 if (arg == 0) /* detach */
567 ipfw_hook(0, AF_INET6);
568 else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) {
569 error = ENOENT;
570 printf("ipfw6_hook() error\n");
571 }
572 #endif
573 if (arg == 0) /* detach */
574 ipfw_hook(0, AF_LINK);
575 else if (V_fwlink_enable && ipfw_hook(1, AF_LINK) != 0) {
576 error = ENOENT;
577 printf("ipfw_link_hook() error\n");
578 }
579 return error;
580 }
581
582 int
ipfw_chg_hook(SYSCTL_HANDLER_ARGS)583 ipfw_chg_hook(SYSCTL_HANDLER_ARGS)
584 {
585 int newval;
586 int error;
587 int af;
588
589 if (arg1 == &V_fw_enable)
590 af = AF_INET;
591 #ifdef INET6
592 else if (arg1 == &V_fw6_enable)
593 af = AF_INET6;
594 #endif
595 else if (arg1 == &V_fwlink_enable)
596 af = AF_LINK;
597 else
598 return (EINVAL);
599
600 newval = *(int *)arg1;
601 /* Handle sysctl change */
602 error = sysctl_handle_int(oidp, &newval, 0, req);
603
604 if (error)
605 return (error);
606
607 /* Formalize new value */
608 newval = (newval) ? 1 : 0;
609
610 if (*(int *)arg1 == newval)
611 return (0);
612
613 error = ipfw_hook(newval, af);
614 if (error)
615 return (error);
616 *(int *)arg1 = newval;
617
618 return (0);
619 }
620 /* end of file */
621