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 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; 128 int ret; 129 130 /* convert dir to IPFW values */ 131 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; 132 bzero(&args, sizeof(args)); 133 134 again: 135 /* 136 * extract and remove the tag if present. If we are left 137 * with onepass, optimize the outgoing path. 138 */ 139 tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); 140 if (tag != NULL) { 141 args.rule = *((struct ipfw_rule_ref *)(tag+1)); 142 m_tag_delete(*m0, tag); 143 if (args.rule.info & IPFW_ONEPASS) 144 return (0); 145 } 146 147 args.m = *m0; 148 args.oif = dir == DIR_OUT ? ifp : NULL; 149 args.inp = inp; 150 151 ipfw = ipfw_chk(&args); 152 *m0 = args.m; 153 154 KASSERT(*m0 != NULL || ipfw == IP_FW_DENY, ("%s: m0 is NULL", 155 __func__)); 156 157 /* breaking out of the switch means drop */ 158 ret = 0; /* default return value for pass */ 159 switch (ipfw) { 160 case IP_FW_PASS: 161 /* next_hop may be set by ipfw_chk */ 162 if (args.next_hop == NULL && args.next_hop6 == NULL) 163 break; /* pass */ 164 #if (!defined(INET6) && !defined(INET)) 165 ret = EACCES; 166 #else 167 { 168 struct m_tag *fwd_tag; 169 size_t len; 170 171 KASSERT(args.next_hop == NULL || args.next_hop6 == NULL, 172 ("%s: both next_hop=%p and next_hop6=%p not NULL", __func__, 173 args.next_hop, args.next_hop6)); 174 #ifdef INET6 175 if (args.next_hop6 != NULL) 176 len = sizeof(struct sockaddr_in6); 177 #endif 178 #ifdef INET 179 if (args.next_hop != NULL) 180 len = sizeof(struct sockaddr_in); 181 #endif 182 183 /* Incoming packets should not be tagged so we do not 184 * m_tag_find. Outgoing packets may be tagged, so we 185 * reuse the tag if present. 186 */ 187 fwd_tag = (dir == DIR_IN) ? NULL : 188 m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL); 189 if (fwd_tag != NULL) { 190 m_tag_unlink(*m0, fwd_tag); 191 } else { 192 fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD, len, 193 M_NOWAIT); 194 if (fwd_tag == NULL) { 195 ret = EACCES; 196 break; /* i.e. drop */ 197 } 198 } 199 #ifdef INET6 200 if (args.next_hop6 != NULL) { 201 struct sockaddr_in6 *sa6; 202 203 sa6 = (struct sockaddr_in6 *)(fwd_tag + 1); 204 bcopy(args.next_hop6, sa6, len); 205 /* 206 * If nh6 address is link-local we should convert 207 * it to kernel internal form before doing any 208 * comparisons. 209 */ 210 if (sa6_embedscope(sa6, V_ip6_use_defzone) != 0) { 211 ret = EACCES; 212 break; 213 } 214 if (in6_localip(&sa6->sin6_addr)) 215 (*m0)->m_flags |= M_FASTFWD_OURS; 216 (*m0)->m_flags |= M_IP6_NEXTHOP; 217 } 218 #endif 219 #ifdef INET 220 if (args.next_hop != NULL) { 221 bcopy(args.next_hop, (fwd_tag+1), len); 222 if (in_localip(args.next_hop->sin_addr)) 223 (*m0)->m_flags |= M_FASTFWD_OURS; 224 (*m0)->m_flags |= M_IP_NEXTHOP; 225 } 226 #endif 227 m_tag_prepend(*m0, fwd_tag); 228 } 229 #endif /* INET || INET6 */ 230 break; 231 232 case IP_FW_DENY: 233 ret = EACCES; 234 break; /* i.e. drop */ 235 236 case IP_FW_DUMMYNET: 237 ret = EACCES; 238 if (ip_dn_io_ptr == NULL) 239 break; /* i.e. drop */ 240 if (mtod(*m0, struct ip *)->ip_v == 4) 241 ret = ip_dn_io_ptr(m0, dir, &args); 242 else if (mtod(*m0, struct ip *)->ip_v == 6) 243 ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args); 244 else 245 break; /* drop it */ 246 /* 247 * XXX should read the return value. 248 * dummynet normally eats the packet and sets *m0=NULL 249 * unless the packet can be sent immediately. In this 250 * case args is updated and we should re-run the 251 * check without clearing args. 252 */ 253 if (*m0 != NULL) 254 goto again; 255 break; 256 257 case IP_FW_TEE: 258 case IP_FW_DIVERT: 259 if (ip_divert_ptr == NULL) { 260 ret = EACCES; 261 break; /* i.e. drop */ 262 } 263 ret = ipfw_divert(m0, dir, &args.rule, 264 (ipfw == IP_FW_TEE) ? 1 : 0); 265 /* continue processing for the original packet (tee). */ 266 if (*m0) 267 goto again; 268 break; 269 270 case IP_FW_NGTEE: 271 case IP_FW_NETGRAPH: 272 if (ng_ipfw_input_p == NULL) { 273 ret = EACCES; 274 break; /* i.e. drop */ 275 } 276 ret = ng_ipfw_input_p(m0, dir, &args, 277 (ipfw == IP_FW_NGTEE) ? 1 : 0); 278 if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */ 279 goto again; /* continue with packet */ 280 break; 281 282 case IP_FW_NAT: 283 /* honor one-pass in case of successful nat */ 284 if (V_fw_one_pass) 285 break; /* ret is already 0 */ 286 goto again; 287 288 case IP_FW_REASS: 289 goto again; /* continue with packet */ 290 291 default: 292 KASSERT(0, ("%s: unknown retval", __func__)); 293 } 294 295 if (ret != 0) { 296 if (*m0) 297 FREE_PKT(*m0); 298 *m0 = NULL; 299 } 300 301 return ret; 302 } 303 304 /* 305 * ipfw processing for ethernet packets (in and out). 306 */ 307 int 308 ipfw_check_frame(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir, 309 struct inpcb *inp) 310 { 311 struct ether_header *eh; 312 struct ether_header save_eh; 313 struct mbuf *m; 314 int i, ret; 315 struct ip_fw_args args; 316 struct m_tag *mtag; 317 318 /* fetch start point from rule, if any. remove the tag if present. */ 319 mtag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); 320 if (mtag == NULL) { 321 args.rule.slot = 0; 322 } else { 323 args.rule = *((struct ipfw_rule_ref *)(mtag+1)); 324 m_tag_delete(*m0, mtag); 325 if (args.rule.info & IPFW_ONEPASS) 326 return (0); 327 } 328 329 /* I need some amt of data to be contiguous */ 330 m = *m0; 331 i = min(m->m_pkthdr.len, max_protohdr); 332 if (m->m_len < i) { 333 m = m_pullup(m, i); 334 if (m == NULL) { 335 *m0 = m; 336 return (0); 337 } 338 } 339 eh = mtod(m, struct ether_header *); 340 save_eh = *eh; /* save copy for restore below */ 341 m_adj(m, ETHER_HDR_LEN); /* strip ethernet header */ 342 343 args.m = m; /* the packet we are looking at */ 344 args.oif = dir == PFIL_OUT ? ifp: NULL; /* destination, if any */ 345 args.next_hop = NULL; /* we do not support forward yet */ 346 args.next_hop6 = NULL; /* we do not support forward yet */ 347 args.eh = &save_eh; /* MAC header for bridged/MAC packets */ 348 args.inp = NULL; /* used by ipfw uid/gid/jail rules */ 349 i = ipfw_chk(&args); 350 m = args.m; 351 if (m != NULL) { 352 /* 353 * Restore Ethernet header, as needed, in case the 354 * mbuf chain was replaced by ipfw. 355 */ 356 M_PREPEND(m, ETHER_HDR_LEN, M_NOWAIT); 357 if (m == NULL) { 358 *m0 = NULL; 359 return (0); 360 } 361 if (eh != mtod(m, struct ether_header *)) 362 bcopy(&save_eh, mtod(m, struct ether_header *), 363 ETHER_HDR_LEN); 364 } 365 *m0 = m; 366 367 ret = 0; 368 /* Check result of ipfw_chk() */ 369 switch (i) { 370 case IP_FW_PASS: 371 break; 372 373 case IP_FW_DENY: 374 ret = EACCES; 375 break; /* i.e. drop */ 376 377 case IP_FW_DUMMYNET: 378 ret = EACCES; 379 380 if (ip_dn_io_ptr == NULL) 381 break; /* i.e. drop */ 382 383 *m0 = NULL; 384 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; 385 ip_dn_io_ptr(&m, dir | PROTO_LAYER2, &args); 386 return 0; 387 388 default: 389 KASSERT(0, ("%s: unknown retval", __func__)); 390 } 391 392 if (ret != 0) { 393 if (*m0) 394 FREE_PKT(*m0); 395 *m0 = NULL; 396 } 397 398 return ret; 399 } 400 401 /* do the divert, return 1 on error 0 on success */ 402 static int 403 ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule, 404 int tee) 405 { 406 /* 407 * ipfw_chk() has already tagged the packet with the divert tag. 408 * If tee is set, copy packet and return original. 409 * If not tee, consume packet and send it to divert socket. 410 */ 411 struct mbuf *clone; 412 struct ip *ip = mtod(*m0, struct ip *); 413 struct m_tag *tag; 414 415 /* Cloning needed for tee? */ 416 if (tee == 0) { 417 clone = *m0; /* use the original mbuf */ 418 *m0 = NULL; 419 } else { 420 clone = m_dup(*m0, M_NOWAIT); 421 /* If we cannot duplicate the mbuf, we sacrifice the divert 422 * chain and continue with the tee-ed packet. 423 */ 424 if (clone == NULL) 425 return 1; 426 } 427 428 /* 429 * Divert listeners can normally handle non-fragmented packets, 430 * but we can only reass in the non-tee case. 431 * This means that listeners on a tee rule may get fragments, 432 * and have to live with that. 433 * Note that we now have the 'reass' ipfw option so if we care 434 * we can do it before a 'tee'. 435 */ 436 if (!tee) switch (ip->ip_v) { 437 case IPVERSION: 438 if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) { 439 int hlen; 440 struct mbuf *reass; 441 442 reass = ip_reass(clone); /* Reassemble packet. */ 443 if (reass == NULL) 444 return 0; /* not an error */ 445 /* if reass = NULL then it was consumed by ip_reass */ 446 /* 447 * IP header checksum fixup after reassembly and leave header 448 * in network byte order. 449 */ 450 ip = mtod(reass, struct ip *); 451 hlen = ip->ip_hl << 2; 452 ip->ip_sum = 0; 453 if (hlen == sizeof(struct ip)) 454 ip->ip_sum = in_cksum_hdr(ip); 455 else 456 ip->ip_sum = in_cksum(reass, hlen); 457 clone = reass; 458 } 459 break; 460 #ifdef INET6 461 case IPV6_VERSION >> 4: 462 { 463 struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *); 464 465 if (ip6->ip6_nxt == IPPROTO_FRAGMENT) { 466 int nxt, off; 467 468 off = sizeof(struct ip6_hdr); 469 nxt = frag6_input(&clone, &off, 0); 470 if (nxt == IPPROTO_DONE) 471 return (0); 472 } 473 break; 474 } 475 #endif 476 } 477 478 /* attach a tag to the packet with the reinject info */ 479 tag = m_tag_alloc(MTAG_IPFW_RULE, 0, 480 sizeof(struct ipfw_rule_ref), M_NOWAIT); 481 if (tag == NULL) { 482 FREE_PKT(clone); 483 return 1; 484 } 485 *((struct ipfw_rule_ref *)(tag+1)) = *rule; 486 m_tag_prepend(clone, tag); 487 488 /* Do the dirty job... */ 489 ip_divert_ptr(clone, incoming); 490 return 0; 491 } 492 493 /* 494 * attach or detach hooks for a given protocol family 495 */ 496 static int 497 ipfw_hook(int onoff, int pf) 498 { 499 struct pfil_head *pfh; 500 pfil_func_t hook_func; 501 502 pfh = pfil_head_get(PFIL_TYPE_AF, pf); 503 if (pfh == NULL) 504 return ENOENT; 505 506 hook_func = (pf == AF_LINK) ? ipfw_check_frame : ipfw_check_packet; 507 508 (void) (onoff ? pfil_add_hook : pfil_remove_hook) 509 (hook_func, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh); 510 511 return 0; 512 } 513 514 int 515 ipfw_attach_hooks(int arg) 516 { 517 int error = 0; 518 519 if (arg == 0) /* detach */ 520 ipfw_hook(0, AF_INET); 521 else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) { 522 error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */ 523 printf("ipfw_hook() error\n"); 524 } 525 #ifdef INET6 526 if (arg == 0) /* detach */ 527 ipfw_hook(0, AF_INET6); 528 else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) { 529 error = ENOENT; 530 printf("ipfw6_hook() error\n"); 531 } 532 #endif 533 if (arg == 0) /* detach */ 534 ipfw_hook(0, AF_LINK); 535 else if (V_fwlink_enable && ipfw_hook(1, AF_LINK) != 0) { 536 error = ENOENT; 537 printf("ipfw_link_hook() error\n"); 538 } 539 return error; 540 } 541 542 int 543 ipfw_chg_hook(SYSCTL_HANDLER_ARGS) 544 { 545 int newval; 546 int error; 547 int af; 548 549 if (arg1 == &V_fw_enable) 550 af = AF_INET; 551 #ifdef INET6 552 else if (arg1 == &V_fw6_enable) 553 af = AF_INET6; 554 #endif 555 else if (arg1 == &V_fwlink_enable) 556 af = AF_LINK; 557 else 558 return (EINVAL); 559 560 newval = *(int *)arg1; 561 /* Handle sysctl change */ 562 error = sysctl_handle_int(oidp, &newval, 0, req); 563 564 if (error) 565 return (error); 566 567 /* Formalize new value */ 568 newval = (newval) ? 1 : 0; 569 570 if (*(int *)arg1 == newval) 571 return (0); 572 573 error = ipfw_hook(newval, af); 574 if (error) 575 return (error); 576 *(int *)arg1 = newval; 577 578 return (0); 579 } 580 /* end of file */ 581