FreeBSD/Linux Kernel Cross Reference
sys/netinet/ip_fw.c
1 /*
2 * Copyright (c) 1993 Daniel Boulet
3 * Copyright (c) 1994 Ugen J.S.Antsilevich
4 * Copyright (c) 1996 Alex Nash
5 *
6 * Redistribution and use in source forms, with and without modification,
7 * are permitted provided that this entire comment appears intact.
8 *
9 * Redistribution in binary form may occur without any restrictions.
10 * Obviously, it would be nice if you gave credit where credit is due
11 * but requiring it would be too onerous.
12 *
13 * This software is provided ``AS IS'' without any warranties of any kind.
14 *
15 * $FreeBSD: src/sys/netinet/ip_fw.c,v 1.51.2.25 1999/09/05 08:18:28 peter Exp $
16 */
17
18 /*
19 * Implement IP packet firewall
20 */
21
22 #ifndef IPFIREWALL_MODULE
23 #include "opt_ipfw.h"
24 #endif
25
26 #include <sys/param.h>
27 #include <sys/systm.h>
28 #include <sys/malloc.h>
29 #include <sys/mbuf.h>
30 #include <sys/queue.h>
31 #include <sys/kernel.h>
32 #include <sys/socket.h>
33 #include <sys/time.h>
34 #include <sys/sysctl.h>
35 #include <net/if.h>
36 #include <net/route.h>
37 #include <netinet/in.h>
38 #include <netinet/in_systm.h>
39 #include <netinet/ip.h>
40 #include <netinet/ip_var.h>
41 #include <netinet/ip_icmp.h>
42 #include <netinet/ip_fw.h>
43 #ifdef DUMMYNET
44 #include <netinet/ip_dummynet.h>
45 #endif
46 #include <netinet/tcp.h>
47 #include <netinet/tcp_timer.h>
48 #include <netinet/tcp_var.h>
49 #include <netinet/tcpip.h>
50 #include <netinet/udp.h>
51
52 #include <netinet/if_ether.h> /* XXX ethertype_ip */
53
54 static int fw_debug = 1;
55 #ifdef IPFIREWALL_VERBOSE
56 static int fw_verbose = 1;
57 #else
58 static int fw_verbose = 0;
59 #endif
60 #ifdef IPFIREWALL_VERBOSE_LIMIT
61 static int fw_verbose_limit = IPFIREWALL_VERBOSE_LIMIT;
62 #else
63 static int fw_verbose_limit = 0;
64 #endif
65 static int fw_one_pass = 1;
66
67 LIST_HEAD (ip_fw_head, ip_fw_chain) ip_fw_chain;
68
69 #ifdef SYSCTL_NODE
70 SYSCTL_NODE(_net_inet_ip, OID_AUTO, fw, CTLFLAG_RW, 0, "Firewall");
71 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, debug, CTLFLAG_RW, &fw_debug, 0, "");
72 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, one_pass, CTLFLAG_RW, &fw_one_pass, 0, "");
73 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose, CTLFLAG_RW, &fw_verbose, 0, "");
74 SYSCTL_INT(_net_inet_ip_fw, OID_AUTO, verbose_limit, CTLFLAG_RW, &fw_verbose_limit, 0, "");
75 #endif
76
77 #define dprintf(a) if (!fw_debug); else printf a
78
79 #define print_ip(a) printf("%ld.%ld.%ld.%ld",(ntohl(a.s_addr)>>24)&0xFF,\
80 (ntohl(a.s_addr)>>16)&0xFF,\
81 (ntohl(a.s_addr)>>8)&0xFF,\
82 (ntohl(a.s_addr))&0xFF);
83
84 #define dprint_ip(a) if (!fw_debug); else print_ip(a)
85
86 static int add_entry __P((struct ip_fw_head *chainptr, struct ip_fw *frwl));
87 static int del_entry __P((struct ip_fw_head *chainptr, u_short number));
88 static int zero_entry __P((struct mbuf *m));
89 static struct ip_fw *check_ipfw_struct __P((struct ip_fw *m));
90 static struct ip_fw *check_ipfw_mbuf __P((struct mbuf *fw));
91 static int ipopts_match __P((struct ip *ip, struct ip_fw *f));
92 static int port_match __P((u_short *portptr, int nports, u_short port,
93 int range_flag));
94 static int tcpflg_match __P((struct tcphdr *tcp, struct ip_fw *f));
95 static int icmptype_match __P((struct icmp * icmp, struct ip_fw * f));
96 static void ipfw_report __P((struct ip_fw *f, struct ip *ip,
97 struct ifnet *rif, struct ifnet *oif));
98
99 static void flush_rule_ptrs(void);
100
101 #ifdef IPFIREWALL_MODULE
102 static ip_fw_chk_t *old_chk_ptr;
103 static ip_fw_ctl_t *old_ctl_ptr;
104 #endif
105
106 static int ip_fw_chk __P((struct ip **pip, int hlen,
107 struct ifnet *oif, u_int16_t *cookie,
108 struct mbuf **m, struct ip_fw_chain **));
109 static int ip_fw_ctl __P((int stage, struct mbuf **mm));
110
111 static char err_prefix[] = "ip_fw_ctl:";
112
113 /*
114 * Returns 1 if the port is matched by the vector, 0 otherwise
115 */
116 static inline int
117 port_match(u_short *portptr, int nports, u_short port, int range_flag)
118 {
119 if (!nports)
120 return 1;
121 if (range_flag) {
122 if (portptr[0] <= port && port <= portptr[1]) {
123 return 1;
124 }
125 nports -= 2;
126 portptr += 2;
127 }
128 while (nports-- > 0) {
129 if (*portptr++ == port) {
130 return 1;
131 }
132 }
133 return 0;
134 }
135
136 static int
137 tcpflg_match(struct tcphdr *tcp, struct ip_fw *f)
138 {
139 u_char flg_set, flg_clr;
140
141 if ((f->fw_tcpf & IP_FW_TCPF_ESTAB) &&
142 (tcp->th_flags & (IP_FW_TCPF_RST | IP_FW_TCPF_ACK)))
143 return 1;
144
145 flg_set = tcp->th_flags & f->fw_tcpf;
146 flg_clr = tcp->th_flags & f->fw_tcpnf;
147
148 if (flg_set != f->fw_tcpf)
149 return 0;
150 if (flg_clr)
151 return 0;
152
153 return 1;
154 }
155
156 static int
157 icmptype_match(struct icmp *icmp, struct ip_fw *f)
158 {
159 int type;
160
161 if (!(f->fw_flg & IP_FW_F_ICMPBIT))
162 return(1);
163
164 type = icmp->icmp_type;
165
166 /* check for matching type in the bitmap */
167 if (type < IP_FW_ICMPTYPES_DIM * sizeof(unsigned) * 8 &&
168 (f->fw_icmptypes[type / (sizeof(unsigned) * 8)] &
169 (1U << (type % (8 * sizeof(unsigned))))))
170 return(1);
171
172 return(0); /* no match */
173 }
174
175 static int
176 is_icmp_query(struct ip *ip)
177 {
178 const struct icmp *icmp;
179 int icmp_type;
180
181 icmp = (struct icmp *)((u_long *)ip + ip->ip_hl);
182 icmp_type = icmp->icmp_type;
183
184 if (icmp_type == ICMP_ECHO || icmp_type == ICMP_ROUTERSOLICIT ||
185 icmp_type == ICMP_TSTAMP || icmp_type == ICMP_IREQ ||
186 icmp_type == ICMP_MASKREQ)
187 return(1);
188
189 return(0);
190 }
191
192 static int
193 ipopts_match(struct ip *ip, struct ip_fw *f)
194 {
195 register u_char *cp;
196 int opt, optlen, cnt;
197 u_char opts, nopts, nopts_sve;
198
199 cp = (u_char *)(ip + 1);
200 cnt = (ip->ip_hl << 2) - sizeof (struct ip);
201 opts = f->fw_ipopt;
202 nopts = nopts_sve = f->fw_ipnopt;
203
204 for (; cnt > 0; cnt -= optlen, cp += optlen) {
205 opt = cp[IPOPT_OPTVAL];
206 if (opt == IPOPT_EOL)
207 break;
208 if (opt == IPOPT_NOP)
209 optlen = 1;
210 else {
211 optlen = cp[IPOPT_OLEN];
212 if (optlen <= 0 || optlen > cnt) {
213 return 0; /*XXX*/
214 }
215 }
216 switch (opt) {
217
218 default:
219 break;
220
221 case IPOPT_LSRR:
222 opts &= ~IP_FW_IPOPT_LSRR;
223 nopts &= ~IP_FW_IPOPT_LSRR;
224 break;
225
226 case IPOPT_SSRR:
227 opts &= ~IP_FW_IPOPT_SSRR;
228 nopts &= ~IP_FW_IPOPT_SSRR;
229 break;
230
231 case IPOPT_RR:
232 opts &= ~IP_FW_IPOPT_RR;
233 nopts &= ~IP_FW_IPOPT_RR;
234 break;
235 case IPOPT_TS:
236 opts &= ~IP_FW_IPOPT_TS;
237 nopts &= ~IP_FW_IPOPT_TS;
238 break;
239 }
240 if (opts == nopts)
241 break;
242 }
243 if (opts == 0 && nopts == nopts_sve)
244 return 1;
245 else
246 return 0;
247 }
248
249 static inline int
250 iface_match(struct ifnet *ifp, union ip_fw_if *ifu, int byname)
251 {
252 /* Check by name or by IP address */
253 if (byname) {
254 /* Check unit number (-1 is wildcard) */
255 if (ifu->fu_via_if.unit != -1
256 && ifp->if_unit != ifu->fu_via_if.unit)
257 return(0);
258 /* Check name */
259 if (strncmp(ifp->if_name, ifu->fu_via_if.name, FW_IFNLEN))
260 return(0);
261 return(1);
262 } else if (ifu->fu_via_ip.s_addr != 0) { /* Zero == wildcard */
263 struct ifaddr *ia;
264
265 for (ia = ifp->if_addrlist; ia; ia = ia->ifa_next) {
266 if (ia->ifa_addr == NULL)
267 continue;
268 if (ia->ifa_addr->sa_family != AF_INET)
269 continue;
270 if (ifu->fu_via_ip.s_addr != ((struct sockaddr_in *)
271 (ia->ifa_addr))->sin_addr.s_addr)
272 continue;
273 return(1);
274 }
275 return(0);
276 }
277 return(1);
278 }
279
280 static void
281 ipfw_report(struct ip_fw *f, struct ip *ip,
282 struct ifnet *rif, struct ifnet *oif)
283 {
284 if (ip) {
285 static int counter;
286 struct tcphdr *const tcp = (struct tcphdr *) ((u_long *) ip+ ip->ip_hl);
287 struct udphdr *const udp = (struct udphdr *) ((u_long *) ip+ ip->ip_hl);
288 struct icmp *const icmp = (struct icmp *) ((u_long *) ip + ip->ip_hl);
289 int count;
290
291 count = f ? f->fw_pcnt : ++counter;
292 if (fw_verbose_limit != 0 && count > fw_verbose_limit)
293 return;
294
295 /* Print command name */
296 printf("ipfw: %d ", f ? f->fw_number : -1);
297 if (!f)
298 printf("Refuse");
299 else
300 switch (f->fw_flg & IP_FW_F_COMMAND) {
301 case IP_FW_F_DENY:
302 printf("Deny");
303 break;
304 case IP_FW_F_REJECT:
305 if (f->fw_reject_code == IP_FW_REJECT_RST)
306 printf("Reset");
307 else
308 printf("Unreach");
309 break;
310 case IP_FW_F_ACCEPT:
311 printf("Accept");
312 break;
313 case IP_FW_F_COUNT:
314 printf("Count");
315 break;
316 case IP_FW_F_DIVERT:
317 printf("Divert %d", f->fw_divert_port);
318 break;
319 case IP_FW_F_TEE:
320 printf("Tee %d", f->fw_divert_port);
321 break;
322 case IP_FW_F_SKIPTO:
323 printf("SkipTo %d", f->fw_skipto_rule);
324 break;
325 case IP_FW_F_PIPE:
326 printf("Pipe %d", f->fw_skipto_rule);
327 break;
328 default:
329 printf("UNKNOWN");
330 break;
331 }
332 printf(" ");
333
334 switch (ip->ip_p) {
335 case IPPROTO_TCP:
336 printf("TCP ");
337 print_ip(ip->ip_src);
338 if ((ip->ip_off & IP_OFFMASK) == 0)
339 printf(":%d ", ntohs(tcp->th_sport));
340 else
341 printf(" ");
342 print_ip(ip->ip_dst);
343 if ((ip->ip_off & IP_OFFMASK) == 0)
344 printf(":%d", ntohs(tcp->th_dport));
345 break;
346 case IPPROTO_UDP:
347 printf("UDP ");
348 print_ip(ip->ip_src);
349 if ((ip->ip_off & IP_OFFMASK) == 0)
350 printf(":%d ", ntohs(udp->uh_sport));
351 else
352 printf(" ");
353 print_ip(ip->ip_dst);
354 if ((ip->ip_off & IP_OFFMASK) == 0)
355 printf(":%d", ntohs(udp->uh_dport));
356 break;
357 case IPPROTO_ICMP:
358 if ((ip->ip_off & IP_OFFMASK) == 0)
359 printf("ICMP:%u.%u ", icmp->icmp_type, icmp->icmp_code);
360 else
361 printf("ICMP ");
362 print_ip(ip->ip_src);
363 printf(" ");
364 print_ip(ip->ip_dst);
365 break;
366 default:
367 printf("P:%d ", ip->ip_p);
368 print_ip(ip->ip_src);
369 printf(" ");
370 print_ip(ip->ip_dst);
371 break;
372 }
373 if (oif)
374 printf(" out via %s%d", oif->if_name, oif->if_unit);
375 else if (rif)
376 printf(" in via %s%d", rif->if_name, rif->if_unit);
377 if ((ip->ip_off & IP_OFFMASK))
378 printf(" Fragment = %d",ip->ip_off & IP_OFFMASK);
379 printf("\n");
380 if (fw_verbose_limit != 0 && count == fw_verbose_limit)
381 printf("ipfw: limit reached on rule #%d\n",
382 f ? f->fw_number : -1);
383 }
384 }
385
386 /*
387 * given an ip_fw_chain *, lookup_next_rule will return a pointer
388 * of the same type to the next one. This can be either the jump
389 * target (for skipto instructions) or the next one in the chain (in
390 * all other cases including a missing jump target).
391 * Backward jumps are not allowed, so start looking from the next
392 * rule...
393 */
394 static struct ip_fw_chain * lookup_next_rule(struct ip_fw_chain *me);
395
396 static struct ip_fw_chain *
397 lookup_next_rule(struct ip_fw_chain *me)
398 {
399 struct ip_fw_chain *chain ;
400 int rule = me->rule->fw_skipto_rule ; /* guess... */
401
402 if ( (me->rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_SKIPTO )
403 for (chain = me->chain.le_next; chain ; chain = chain->chain.le_next )
404 if (chain->rule->fw_number >= rule)
405 return chain ;
406 /*
407 * note the above matches any rule >= the jump target. I
408 * don't think this is a particularly good idea, but it is
409 * how ipfw always worked.
410 */
411 return me->chain.le_next ; /* failure or not a skipto */
412 }
413
414 /*
415 * Parameters:
416 *
417 * pip Pointer to packet header (struct ip **)
418 * bridge_ipfw extension: pip = NULL means a complete ethernet packet
419 * including ethernet header in the mbuf. Other fields
420 * are ignored/invalid.
421 *
422 * hlen Packet header length
423 * oif Outgoing interface, or NULL if packet is incoming
424 * #ifndef IPFW_DIVERT_RESTART
425 * *cookie Ignore all divert/tee rules to this port (if non-zero)
426 * #else
427 * *cookie Skip up to the first rule past this rule number;
428 * #endif
429 * *m The packet; we set to NULL when/if we nuke it.
430 * *flow_id pointer to the last matching rule (in/out)
431 *
432 * Return value:
433 *
434 * 0 The packet is to be accepted and routed normally OR
435 * the packet was denied/rejected and has been dropped;
436 * in the latter case, *m is equal to NULL upon return.
437 * port Divert the packet to port.
438 */
439
440 static int
441 ip_fw_chk(struct ip **pip, int hlen,
442 struct ifnet *oif, u_int16_t *cookie, struct mbuf **m,
443 struct ip_fw_chain **flow_id)
444 {
445 struct ip_fw_chain *chain;
446 struct ip_fw *rule = NULL;
447 struct ip *ip = NULL ;
448 struct ifnet *const rif = (*m)->m_pkthdr.rcvif;
449 u_short offset = 0 ;
450 u_short src_port, dst_port;
451 #ifdef IPFW_DIVERT_RESTART
452 u_int16_t skipto = *cookie;
453 #else
454 u_int16_t ignport = ntohs(*cookie);
455 #endif
456
457 if (pip) { /* normal ip packet */
458 ip = *pip;
459 offset = (ip->ip_off & IP_OFFMASK);
460 } else { /* bridged or non-ip packet */
461 struct ether_header *eh = mtod(*m, struct ether_header *);
462 switch (ntohs(eh->ether_type)) {
463 case ETHERTYPE_IP :
464 if ((*m)->m_len<sizeof(struct ether_header) + sizeof(struct ip))
465 goto non_ip ;
466 ip = (struct ip *)(eh + 1 );
467 if (ip->ip_v != IPVERSION)
468 goto non_ip ;
469 hlen = ip->ip_hl << 2;
470 if (hlen < sizeof(struct ip)) /* minimum header length */
471 goto non_ip ;
472 if ((*m)->m_len < 14 + hlen + 14) {
473 printf("-- m_len %d, need more...\n", (*m)->m_len);
474 goto non_ip ;
475 }
476 offset = (ip->ip_off & IP_OFFMASK);
477 break ;
478 default :
479 non_ip: ip = NULL ;
480 break ;
481 }
482 }
483
484 if (*flow_id) {
485 if (fw_one_pass)
486 return 0 ; /* accept if passed first test */
487 /*
488 * pkt has already been tagged. Look for the next rule
489 * to restart processing
490 */
491 if ( (chain = (*flow_id)->rule->next_rule_ptr) == NULL )
492 chain = (*flow_id)->rule->next_rule_ptr =
493 lookup_next_rule(*flow_id) ;
494 if (!chain)
495 goto dropit;
496 } else {
497 chain=LIST_FIRST(&ip_fw_chain);
498 #ifdef IPFW_DIVERT_RESTART
499 if ( skipto ) {
500 /*
501 * If we've been asked to start at a given rule immediatly,
502 * do so.
503 */
504 if (skipto >= 65535)
505 goto dropit;
506 while (chain && (chain->rule->fw_number <= skipto)) {
507 chain = LIST_NEXT(chain, chain);
508 }
509 if (! chain)
510 goto dropit;
511 }
512 #endif /* IPFW_DIVERT_RESTART */
513 }
514 *cookie = 0;
515 for (; chain; chain = LIST_NEXT(chain, chain)) {
516 register struct ip_fw *f;
517 again:
518 f = chain->rule;
519
520 if (oif) {
521 /* Check direction outbound */
522 if (!(f->fw_flg & IP_FW_F_OUT))
523 continue;
524 } else {
525 /* Check direction inbound */
526 if (!(f->fw_flg & IP_FW_F_IN))
527 continue;
528 }
529
530 if (ip == NULL ) {
531 /*
532 * do relevant checks for non-ip packets:
533 * after this, only goto got_match or continue
534 */
535 struct ether_header *eh = mtod(*m, struct ether_header *);
536 int i, h, l ;
537 #if 0
538 printf("-- ip_fw: rule %d(%d) for %6D <- %6D type 0x%04x\n",
539 f->fw_number, IP_FW_GETNSRCP(f),
540 eh->ether_dhost, ".", eh->ether_shost, ".",
541 ntohs(eh->ether_type) );
542 #endif
543 /*
544 * make default rule always match or we have a panic
545 */
546 if (f->fw_number == 65535)
547 goto got_match ;
548
549 /*
550 * temporary hack:
551 * udp from 0.0.0.0 means this rule applies.
552 * 1 src port is match ether type
553 * 2 src ports (interval) is match ether type
554 * 3 src ports is match ether address
555 */
556 if (f->fw_src.s_addr != 0 || f->fw_prot != IPPROTO_UDP
557 || f->fw_smsk.s_addr != 0xffffffff )
558 continue ;
559 switch (IP_FW_GETNSRCP(f)) {
560 case 1: /* match one type */
561 if ( /* ( (f->fw_flg & IP_FW_F_INVSRC) != 0) ^ */
562 ( f->fw_pts[0] == ntohs(eh->ether_type) ) ) {
563 goto got_match ;
564 }
565 default:
566 break ;
567 }
568 continue;
569 }
570 /* Fragments */
571 if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 )
572 continue;
573
574 /* If src-addr doesn't match, not this rule. */
575 if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((ip->ip_src.s_addr
576 & f->fw_smsk.s_addr) != f->fw_src.s_addr))
577 continue;
578
579 /* If dest-addr doesn't match, not this rule. */
580 if (((f->fw_flg & IP_FW_F_INVDST) != 0) ^ ((ip->ip_dst.s_addr
581 & f->fw_dmsk.s_addr) != f->fw_dst.s_addr))
582 continue;
583
584 /* Interface check */
585 if ((f->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
586 struct ifnet *const iface = oif ? oif : rif;
587
588 /* Backwards compatibility hack for "via" */
589 if (!iface || !iface_match(iface,
590 &f->fw_in_if, f->fw_flg & IP_FW_F_OIFNAME))
591 continue;
592 } else {
593 /* Check receive interface */
594 if ((f->fw_flg & IP_FW_F_IIFACE)
595 && (!rif || !iface_match(rif,
596 &f->fw_in_if, f->fw_flg & IP_FW_F_IIFNAME)))
597 continue;
598 /* Check outgoing interface */
599 if ((f->fw_flg & IP_FW_F_OIFACE)
600 && (!oif || !iface_match(oif,
601 &f->fw_out_if, f->fw_flg & IP_FW_F_OIFNAME)))
602 continue;
603 }
604
605 /* Check IP options */
606 if (f->fw_ipopt != f->fw_ipnopt && !ipopts_match(ip, f))
607 continue;
608
609 /* Check protocol; if wildcard, match */
610 if (f->fw_prot == IPPROTO_IP)
611 goto got_match;
612
613 /* If different, don't match */
614 if (ip->ip_p != f->fw_prot)
615 continue;
616
617 /*
618 * here, pip==NULL for bridged pkts -- they include the ethernet
619 * header so i have to adjust lengths accordingly
620 */
621 #define PULLUP_TO(l) do { \
622 int len = (pip ? l : l + 14 ) ; \
623 if ((*m)->m_len < (len) ) { \
624 if ( (*m = m_pullup(*m, (len))) == 0) \
625 goto bogusfrag; \
626 ip = mtod(*m, struct ip *); \
627 if (pip) \
628 *pip = ip ; \
629 else \
630 ip = (struct ip *)((int)ip + 14); \
631 offset = (ip->ip_off & IP_OFFMASK); \
632 } \
633 } while (0)
634
635 /* Protocol specific checks */
636 switch (ip->ip_p) {
637 case IPPROTO_TCP:
638 {
639 struct tcphdr *tcp;
640
641 if (offset == 1) /* cf. RFC 1858 */
642 goto bogusfrag;
643 if (offset != 0) {
644 /*
645 * TCP flags and ports aren't available in this
646 * packet -- if this rule specified either one,
647 * we consider the rule a non-match.
648 */
649 if (f->fw_nports != 0 ||
650 f->fw_tcpf != f->fw_tcpnf)
651 continue;
652
653 break;
654 }
655 PULLUP_TO(hlen + 14);
656 tcp = (struct tcphdr *) ((u_long *)ip + ip->ip_hl);
657 if (f->fw_tcpf != f->fw_tcpnf && !tcpflg_match(tcp, f))
658 continue;
659 src_port = ntohs(tcp->th_sport);
660 dst_port = ntohs(tcp->th_dport);
661 goto check_ports;
662 }
663
664 case IPPROTO_UDP:
665 {
666 struct udphdr *udp;
667
668 if (offset != 0) {
669 /*
670 * Port specification is unavailable -- if this
671 * rule specifies a port, we consider the rule
672 * a non-match.
673 */
674 if (f->fw_nports != 0)
675 continue;
676
677 break;
678 }
679 PULLUP_TO(hlen + 4);
680 udp = (struct udphdr *) ((u_long *)ip + ip->ip_hl);
681 src_port = ntohs(udp->uh_sport);
682 dst_port = ntohs(udp->uh_dport);
683 check_ports:
684 if (!port_match(&f->fw_pts[0],
685 IP_FW_GETNSRCP(f), src_port,
686 f->fw_flg & IP_FW_F_SRNG))
687 continue;
688 if (!port_match(&f->fw_pts[IP_FW_GETNSRCP(f)],
689 IP_FW_GETNDSTP(f), dst_port,
690 f->fw_flg & IP_FW_F_DRNG))
691 continue;
692 break;
693 }
694
695 case IPPROTO_ICMP:
696 {
697 struct icmp *icmp;
698
699 if (offset != 0) /* Type isn't valid */
700 break;
701 PULLUP_TO(hlen + 2);
702 icmp = (struct icmp *) ((u_long *)ip + ip->ip_hl);
703 if (!icmptype_match(icmp, f))
704 continue;
705 break;
706 }
707 #undef PULLUP_TO
708
709 bogusfrag:
710 if (fw_verbose)
711 ipfw_report(NULL, ip, rif, oif);
712 goto dropit;
713 }
714
715 got_match:
716 *flow_id = chain ; /* XXX set flow id */
717 #ifndef IPFW_DIVERT_RESTART
718 /* Ignore divert/tee rule if socket port is "ignport" */
719 switch (f->fw_flg & IP_FW_F_COMMAND) {
720 case IP_FW_F_DIVERT:
721 case IP_FW_F_TEE:
722 if (f->fw_divert_port == ignport)
723 continue; /* ignore this rule */
724 break;
725 }
726
727 #endif /* IPFW_DIVERT_RESTART */
728 /* Update statistics */
729 f->fw_pcnt += 1;
730 if (ip)
731 f->fw_bcnt += ip->ip_len ;
732 f->timestamp = time.tv_sec;
733
734 /* Log to console if desired */
735 if ((f->fw_flg & IP_FW_F_PRN) && fw_verbose)
736 ipfw_report(f, ip, rif, oif);
737
738 /* Take appropriate action */
739 switch (f->fw_flg & IP_FW_F_COMMAND) {
740 case IP_FW_F_ACCEPT:
741 return(0);
742 case IP_FW_F_COUNT:
743 continue;
744 #ifdef IPDIVERT
745 case IP_FW_F_DIVERT:
746 #ifdef IPFW_DIVERT_RESTART
747 *cookie = f->fw_number;
748 #else
749 *cookie = htons(f->fw_divert_port);
750 #endif /* IPFW_DIVERT_RESTART */
751 return(f->fw_divert_port);
752 #endif
753 case IP_FW_F_TEE:
754 /*
755 * XXX someday tee packet here, but beware that you
756 * can't use m_copym() or m_copypacket() because
757 * the divert input routine modifies the mbuf
758 * (and these routines only increment reference
759 * counts in the case of mbuf clusters), so need
760 * to write custom routine.
761 */
762 continue;
763 case IP_FW_F_SKIPTO: /* XXX check */
764 if ( f->next_rule_ptr )
765 chain = f->next_rule_ptr ;
766 else
767 chain = lookup_next_rule(chain) ;
768 if (!chain)
769 goto dropit;
770 goto again ;
771 #ifdef DUMMYNET
772 case IP_FW_F_PIPE:
773 return(f->fw_pipe_nr | 0x10000 );
774 #endif
775 }
776
777 /* Deny/reject this packet using this rule */
778 rule = f;
779 break;
780 }
781
782 #ifdef DIAGNOSTIC
783 /* Rule 65535 should always be there and should always match */
784 if (!chain)
785 panic("ip_fw: chain");
786 #endif
787
788 /*
789 * At this point, we're going to drop the packet.
790 * Send a reject notice if all of the following are true:
791 *
792 * - The packet matched a reject rule
793 * - The packet is not an ICMP packet, or is an ICMP query packet
794 * - The packet is not a multicast or broadcast packet
795 */
796 if ((rule->fw_flg & IP_FW_F_COMMAND) == IP_FW_F_REJECT
797 && ip
798 && (ip->ip_p != IPPROTO_ICMP || is_icmp_query(ip))
799 && !((*m)->m_flags & (M_BCAST|M_MCAST))
800 && !IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
801 switch (rule->fw_reject_code) {
802 case IP_FW_REJECT_RST:
803 {
804 struct tcphdr *const tcp =
805 (struct tcphdr *) ((u_long *)ip + ip->ip_hl);
806 struct tcpiphdr ti, *const tip = (struct tcpiphdr *) ip;
807
808 if (offset != 0 || (tcp->th_flags & TH_RST))
809 break;
810 ti.ti_i = *((struct ipovly *) ip);
811 ti.ti_t = *tcp;
812 bcopy(&ti, ip, sizeof(ti));
813 NTOHL(tip->ti_seq);
814 NTOHL(tip->ti_ack);
815 tip->ti_len = ip->ip_len - hlen - (tip->ti_off << 2);
816 if (tcp->th_flags & TH_ACK) {
817 tcp_respond(NULL, tip, *m,
818 (tcp_seq)0, ntohl(tcp->th_ack), TH_RST);
819 } else {
820 if (tcp->th_flags & TH_SYN)
821 tip->ti_len++;
822 tcp_respond(NULL, tip, *m, tip->ti_seq
823 + tip->ti_len, (tcp_seq)0, TH_RST|TH_ACK);
824 }
825 *m = NULL;
826 break;
827 }
828 default: /* Send an ICMP unreachable using code */
829 icmp_error(*m, ICMP_UNREACH,
830 rule->fw_reject_code, 0L, 0);
831 *m = NULL;
832 break;
833 }
834 }
835
836 dropit:
837 /*
838 * Finally, drop the packet.
839 */
840 if (*m) {
841 m_freem(*m);
842 *m = NULL;
843 }
844 return(0);
845 }
846
847 /*
848 * when a rule is added/deleted, zero the direct pointers within
849 * all firewall rules. These will be reconstructed on the fly
850 * as packets are matched.
851 * Must be called at splnet().
852 */
853 static void
854 flush_rule_ptrs()
855 {
856 struct ip_fw_chain *fcp ;
857
858 for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next) {
859 fcp->rule->next_rule_ptr = NULL ;
860 }
861 }
862
863 static int
864 add_entry(struct ip_fw_head *chainptr, struct ip_fw *frwl)
865 {
866 struct ip_fw *ftmp = 0;
867 struct ip_fw_chain *fwc = 0, *fcp, *fcpl = 0;
868 u_short nbr = 0;
869 int s;
870
871 fwc = malloc(sizeof *fwc, M_IPFW, M_DONTWAIT);
872 ftmp = malloc(sizeof *ftmp, M_IPFW, M_DONTWAIT);
873 if (!fwc || !ftmp) {
874 dprintf(("%s malloc said no\n", err_prefix));
875 if (fwc) free(fwc, M_IPFW);
876 if (ftmp) free(ftmp, M_IPFW);
877 return (ENOSPC);
878 }
879
880 bcopy(frwl, ftmp, sizeof(struct ip_fw));
881 ftmp->fw_in_if.fu_via_if.name[FW_IFNLEN - 1] = '\0';
882 ftmp->fw_pcnt = 0L;
883 ftmp->fw_bcnt = 0L;
884 ftmp->next_rule_ptr = NULL ;
885 ftmp->pipe_ptr = NULL ;
886 fwc->rule = ftmp;
887
888 s = splnet();
889
890 if (!chainptr->lh_first) {
891 LIST_INSERT_HEAD(chainptr, fwc, chain);
892 splx(s);
893 return(0);
894 } else if (ftmp->fw_number == (u_short)-1) {
895 if (fwc) free(fwc, M_IPFW);
896 if (ftmp) free(ftmp, M_IPFW);
897 splx(s);
898 dprintf(("%s bad rule number\n", err_prefix));
899 return (EINVAL);
900 }
901
902 /* If entry number is 0, find highest numbered rule and add 100 */
903 if (ftmp->fw_number == 0) {
904 for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
905 if (fcp->rule->fw_number != (u_short)-1)
906 nbr = fcp->rule->fw_number;
907 else
908 break;
909 }
910 if (nbr < (u_short)-1 - 100)
911 nbr += 100;
912 ftmp->fw_number = nbr;
913 }
914
915 /* Got a valid number; now insert it, keeping the list ordered */
916 for (fcp = chainptr->lh_first; fcp; fcp = fcp->chain.le_next) {
917 if (fcp->rule->fw_number > ftmp->fw_number) {
918 if (fcpl) {
919 LIST_INSERT_AFTER(fcpl, fwc, chain);
920 } else {
921 LIST_INSERT_HEAD(chainptr, fwc, chain);
922 }
923 break;
924 } else {
925 fcpl = fcp;
926 }
927 }
928 flush_rule_ptrs();
929
930 splx(s);
931 return (0);
932 }
933
934 static int
935 del_entry(struct ip_fw_head *chainptr, u_short number)
936 {
937 struct ip_fw_chain *fcp;
938 int s;
939
940 s = splnet();
941
942 fcp = chainptr->lh_first;
943 if (number != (u_short)-1) {
944 for (; fcp; fcp = fcp->chain.le_next) {
945 if (fcp->rule->fw_number == number) {
946 LIST_REMOVE(fcp, chain);
947 #ifdef DUMMYNET
948 dn_rule_delete(fcp) ;
949 #endif
950 flush_rule_ptrs();
951 splx(s);
952 free(fcp->rule, M_IPFW);
953 free(fcp, M_IPFW);
954 return 0;
955 }
956 }
957 }
958
959 splx(s);
960 return (EINVAL);
961 }
962
963 static int
964 zero_entry(struct mbuf *m)
965 {
966 struct ip_fw *frwl;
967 struct ip_fw_chain *fcp;
968 int s;
969
970 if (m) {
971 if (m->m_len != sizeof(struct ip_fw))
972 return(EINVAL);
973 frwl = mtod(m, struct ip_fw *);
974 }
975 else
976 frwl = NULL;
977
978 /*
979 * It's possible to insert multiple chain entries with the
980 * same number, so we don't stop after finding the first
981 * match if zeroing a specific entry.
982 */
983 s = splnet();
984 for (fcp = ip_fw_chain.lh_first; fcp; fcp = fcp->chain.le_next)
985 if (!frwl || frwl->fw_number == fcp->rule->fw_number) {
986 fcp->rule->fw_bcnt = fcp->rule->fw_pcnt = 0;
987 fcp->rule->timestamp = 0;
988 }
989 splx(s);
990
991 if (fw_verbose) {
992 if (frwl)
993 printf("ipfw: Entry %d cleared.\n", frwl->fw_number);
994 else
995 printf("ipfw: Accounting cleared.\n");
996 }
997
998 return(0);
999 }
1000
1001 static struct ip_fw *
1002 check_ipfw_mbuf(struct mbuf *m)
1003 {
1004 /* Check length */
1005 if (m->m_len != sizeof(struct ip_fw)) {
1006 dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
1007 sizeof(struct ip_fw)));
1008 return (NULL);
1009 }
1010 return(check_ipfw_struct(mtod(m, struct ip_fw *)));
1011 }
1012
1013 static struct ip_fw *
1014 check_ipfw_struct(struct ip_fw *frwl)
1015 {
1016 /* Check for invalid flag bits */
1017 if ((frwl->fw_flg & ~IP_FW_F_MASK) != 0) {
1018 dprintf(("%s undefined flag bits set (flags=%x)\n",
1019 err_prefix, frwl->fw_flg));
1020 return (NULL);
1021 }
1022 /* Must apply to incoming or outgoing (or both) */
1023 if (!(frwl->fw_flg & (IP_FW_F_IN | IP_FW_F_OUT))) {
1024 dprintf(("%s neither in nor out\n", err_prefix));
1025 return (NULL);
1026 }
1027 /* Empty interface name is no good */
1028 if (((frwl->fw_flg & IP_FW_F_IIFNAME)
1029 && !*frwl->fw_in_if.fu_via_if.name)
1030 || ((frwl->fw_flg & IP_FW_F_OIFNAME)
1031 && !*frwl->fw_out_if.fu_via_if.name)) {
1032 dprintf(("%s empty interface name\n", err_prefix));
1033 return (NULL);
1034 }
1035 /* Sanity check interface matching */
1036 if ((frwl->fw_flg & IF_FW_F_VIAHACK) == IF_FW_F_VIAHACK) {
1037 ; /* allow "via" backwards compatibility */
1038 } else if ((frwl->fw_flg & IP_FW_F_IN)
1039 && (frwl->fw_flg & IP_FW_F_OIFACE)) {
1040 dprintf(("%s outgoing interface check on incoming\n",
1041 err_prefix));
1042 return (NULL);
1043 }
1044 /* Sanity check port ranges */
1045 if ((frwl->fw_flg & IP_FW_F_SRNG) && IP_FW_GETNSRCP(frwl) < 2) {
1046 dprintf(("%s src range set but n_src_p=%d\n",
1047 err_prefix, IP_FW_GETNSRCP(frwl)));
1048 return (NULL);
1049 }
1050 if ((frwl->fw_flg & IP_FW_F_DRNG) && IP_FW_GETNDSTP(frwl) < 2) {
1051 dprintf(("%s dst range set but n_dst_p=%d\n",
1052 err_prefix, IP_FW_GETNDSTP(frwl)));
1053 return (NULL);
1054 }
1055 if (IP_FW_GETNSRCP(frwl) + IP_FW_GETNDSTP(frwl) > IP_FW_MAX_PORTS) {
1056 dprintf(("%s too many ports (%d+%d)\n",
1057 err_prefix, IP_FW_GETNSRCP(frwl), IP_FW_GETNDSTP(frwl)));
1058 return (NULL);
1059 }
1060 /*
1061 * Protocols other than TCP/UDP don't use port range
1062 */
1063 if ((frwl->fw_prot != IPPROTO_TCP) &&
1064 (frwl->fw_prot != IPPROTO_UDP) &&
1065 (IP_FW_GETNSRCP(frwl) || IP_FW_GETNDSTP(frwl))) {
1066 dprintf(("%s port(s) specified for non TCP/UDP rule\n",
1067 err_prefix));
1068 return(NULL);
1069 }
1070
1071 /*
1072 * Rather than modify the entry to make such entries work,
1073 * we reject this rule and require user level utilities
1074 * to enforce whatever policy they deem appropriate.
1075 */
1076 if ((frwl->fw_src.s_addr & (~frwl->fw_smsk.s_addr)) ||
1077 (frwl->fw_dst.s_addr & (~frwl->fw_dmsk.s_addr))) {
1078 dprintf(("%s rule never matches\n", err_prefix));
1079 return(NULL);
1080 }
1081
1082 if ((frwl->fw_flg & IP_FW_F_FRAG) &&
1083 (frwl->fw_prot == IPPROTO_UDP || frwl->fw_prot == IPPROTO_TCP)) {
1084 if (frwl->fw_nports) {
1085 dprintf(("%s cannot mix 'frag' and ports\n", err_prefix));
1086 return(NULL);
1087 }
1088 if (frwl->fw_prot == IPPROTO_TCP &&
1089 frwl->fw_tcpf != frwl->fw_tcpnf) {
1090 dprintf(("%s cannot mix 'frag' with TCP flags\n", err_prefix));
1091 return(NULL);
1092 }
1093 }
1094
1095 /* Check command specific stuff */
1096 switch (frwl->fw_flg & IP_FW_F_COMMAND)
1097 {
1098 case IP_FW_F_REJECT:
1099 if (frwl->fw_reject_code >= 0x100
1100 && !(frwl->fw_prot == IPPROTO_TCP
1101 && frwl->fw_reject_code == IP_FW_REJECT_RST)) {
1102 dprintf(("%s unknown reject code\n", err_prefix));
1103 return(NULL);
1104 }
1105 break;
1106 case IP_FW_F_DIVERT: /* Diverting to port zero is invalid */
1107 case IP_FW_F_PIPE: /* piping through 0 is invalid */
1108 case IP_FW_F_TEE:
1109 if (frwl->fw_divert_port == 0) {
1110 dprintf(("%s can't divert to port 0\n", err_prefix));
1111 return (NULL);
1112 }
1113 break;
1114 case IP_FW_F_DENY:
1115 case IP_FW_F_ACCEPT:
1116 case IP_FW_F_COUNT:
1117 case IP_FW_F_SKIPTO:
1118 break;
1119 default:
1120 dprintf(("%s invalid command\n", err_prefix));
1121 return(NULL);
1122 }
1123
1124 return frwl;
1125 }
1126
1127 static int
1128 ip_fw_ctl(int stage, struct mbuf **mm)
1129 {
1130 int error;
1131 struct mbuf *m;
1132
1133 if (stage == IP_FW_GET) {
1134 struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
1135 *mm = m = m_get(M_WAIT, MT_SOOPTS);
1136 for (; fcp; fcp = fcp->chain.le_next) {
1137 memcpy(m->m_data, fcp->rule, sizeof *(fcp->rule));
1138 m->m_len = sizeof *(fcp->rule);
1139 m->m_next = m_get(M_WAIT, MT_SOOPTS);
1140 m = m->m_next;
1141 m->m_len = 0;
1142 }
1143 return (0);
1144 }
1145 m = *mm;
1146 /* only allow get calls if secure mode > 2 */
1147 if (securelevel > 2) {
1148 if (m) (void)m_free(m);
1149 return(EPERM);
1150 }
1151 if (stage == IP_FW_FLUSH) {
1152 while (ip_fw_chain.lh_first != NULL &&
1153 ip_fw_chain.lh_first->rule->fw_number != (u_short)-1) {
1154 struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
1155 int s = splnet();
1156 LIST_REMOVE(ip_fw_chain.lh_first, chain);
1157 #ifdef DUMMYNET
1158 dn_rule_delete(fcp);
1159 #endif
1160 splx(s);
1161 free(fcp->rule, M_IPFW);
1162 free(fcp, M_IPFW);
1163 }
1164 if (m) (void)m_free(m);
1165 return (0);
1166 }
1167 if (stage == IP_FW_ZERO) {
1168 error = zero_entry(m);
1169 if (m) (void)m_free(m);
1170 return (error);
1171 }
1172 if (m == NULL) {
1173 printf("%s NULL mbuf ptr\n", err_prefix);
1174 return (EINVAL);
1175 }
1176
1177 if (stage == IP_FW_ADD) {
1178 struct ip_fw *frwl = check_ipfw_mbuf(m);
1179
1180 if (!frwl)
1181 error = EINVAL;
1182 else
1183 error = add_entry(&ip_fw_chain, frwl);
1184 if (m) (void)m_free(m);
1185 return error;
1186 }
1187 if (stage == IP_FW_DEL) {
1188 if (m->m_len != sizeof(struct ip_fw)) {
1189 dprintf(("%s len=%d, want %d\n", err_prefix, m->m_len,
1190 sizeof(struct ip_fw)));
1191 error = EINVAL;
1192 } else if (mtod(m, struct ip_fw *)->fw_number == (u_short)-1) {
1193 dprintf(("%s can't delete rule 65535\n", err_prefix));
1194 error = EINVAL;
1195 } else
1196 error = del_entry(&ip_fw_chain,
1197 mtod(m, struct ip_fw *)->fw_number);
1198 if (m) (void)m_free(m);
1199 return error;
1200 }
1201
1202 dprintf(("%s unknown request %d\n", err_prefix, stage));
1203 if (m) (void)m_free(m);
1204 return (EINVAL);
1205 }
1206
1207 struct ip_fw_chain *ip_fw_default_rule ;
1208
1209 void
1210 ip_fw_init(void)
1211 {
1212 struct ip_fw default_rule;
1213
1214 ip_fw_chk_ptr = ip_fw_chk;
1215 ip_fw_ctl_ptr = ip_fw_ctl;
1216 LIST_INIT(&ip_fw_chain);
1217
1218 bzero(&default_rule, sizeof default_rule);
1219 default_rule.fw_prot = IPPROTO_IP;
1220 default_rule.fw_number = (u_short)-1;
1221 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
1222 default_rule.fw_flg |= IP_FW_F_ACCEPT;
1223 #else
1224 default_rule.fw_flg |= IP_FW_F_DENY;
1225 #endif
1226 default_rule.fw_flg |= IP_FW_F_IN | IP_FW_F_OUT;
1227 if (check_ipfw_struct(&default_rule) == NULL ||
1228 add_entry(&ip_fw_chain, &default_rule))
1229 panic(__FUNCTION__);
1230
1231 ip_fw_default_rule = ip_fw_chain.lh_first ;
1232 printf("IP packet filtering initialized, "
1233 #ifdef IPDIVERT
1234 "divert enabled, ");
1235 #else
1236 "divert disabled, ");
1237 #endif
1238 #ifdef IPFIREWALL_DEFAULT_TO_ACCEPT
1239 printf("default to accept, ");
1240 #endif
1241 #ifndef IPFIREWALL_VERBOSE
1242 printf("logging disabled\n");
1243 #else
1244 if (fw_verbose_limit == 0)
1245 printf("unlimited logging\n");
1246 else
1247 printf("logging limited to %d packets/entry\n",
1248 fw_verbose_limit);
1249 #endif
1250 }
1251
1252 #ifdef IPFIREWALL_MODULE
1253
1254 #include <sys/exec.h>
1255 #include <sys/sysent.h>
1256 #include <sys/lkm.h>
1257
1258 MOD_MISC(ipfw);
1259
1260 static int
1261 ipfw_load(struct lkm_table *lkmtp, int cmd)
1262 {
1263 int s=splnet();
1264
1265 old_chk_ptr = ip_fw_chk_ptr;
1266 old_ctl_ptr = ip_fw_ctl_ptr;
1267
1268 ip_fw_init();
1269 splx(s);
1270 return 0;
1271 }
1272
1273 static int
1274 ipfw_unload(struct lkm_table *lkmtp, int cmd)
1275 {
1276 int s=splnet();
1277
1278 ip_fw_chk_ptr = old_chk_ptr;
1279 ip_fw_ctl_ptr = old_ctl_ptr;
1280
1281 while (ip_fw_chain.lh_first != NULL) {
1282 struct ip_fw_chain *fcp = ip_fw_chain.lh_first;
1283 LIST_REMOVE(ip_fw_chain.lh_first, chain);
1284 free(fcp->rule, M_IPFW);
1285 free(fcp, M_IPFW);
1286 }
1287
1288 splx(s);
1289 printf("IP firewall unloaded\n");
1290 return 0;
1291 }
1292
1293 int
1294 ipfw_mod(struct lkm_table *lkmtp, int cmd, int ver)
1295 {
1296 DISPATCH(lkmtp, cmd, ver, ipfw_load, ipfw_unload, lkm_nullcmd);
1297 }
1298 #endif
Cache object: 18208015bec872c7b110a3852d9604b6
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