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 #endif 63 64 #include <netgraph/ng_ipfw.h> 65 66 #include <netpfil/ipfw/ip_fw_private.h> 67 68 #include <machine/in_cksum.h> 69 70 static VNET_DEFINE(int, fw_enable) = 1; 71 #define V_fw_enable VNET(fw_enable) 72 73 #ifdef INET6 74 static VNET_DEFINE(int, fw6_enable) = 1; 75 #define V_fw6_enable VNET(fw6_enable) 76 #endif 77 78 static VNET_DEFINE(int, fwlink_enable) = 0; 79 #define V_fwlink_enable VNET(fwlink_enable) 80 81 int ipfw_chg_hook(SYSCTL_HANDLER_ARGS); 82 83 /* Forward declarations. */ 84 static int ipfw_divert(struct mbuf **, int, struct ipfw_rule_ref *, int); 85 int ipfw_check_packet(void *, struct mbuf **, struct ifnet *, int, 86 struct inpcb *); 87 int ipfw_check_frame(void *, struct mbuf **, struct ifnet *, int, 88 struct inpcb *); 89 90 #ifdef SYSCTL_NODE 91 92 SYSBEGIN(f1) 93 94 SYSCTL_DECL(_net_inet_ip_fw); 95 SYSCTL_PROC(_net_inet_ip_fw, OID_AUTO, enable, 96 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, 97 &VNET_NAME(fw_enable), 0, ipfw_chg_hook, "I", "Enable ipfw"); 98 #ifdef INET6 99 SYSCTL_DECL(_net_inet6_ip6_fw); 100 SYSCTL_PROC(_net_inet6_ip6_fw, OID_AUTO, enable, 101 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, 102 &VNET_NAME(fw6_enable), 0, ipfw_chg_hook, "I", "Enable ipfw+6"); 103 #endif /* INET6 */ 104 105 SYSCTL_DECL(_net_link_ether); 106 SYSCTL_PROC(_net_link_ether, OID_AUTO, ipfw, 107 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, 108 &VNET_NAME(fwlink_enable), 0, ipfw_chg_hook, "I", 109 "Pass ether pkts through firewall"); 110 111 SYSEND 112 113 #endif /* SYSCTL_NODE */ 114 115 /* 116 * The pfilter hook to pass packets to ipfw_chk and then to 117 * dummynet, divert, netgraph or other modules. 118 * The packet may be consumed. 119 */ 120 int 121 ipfw_check_packet(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir, 122 struct inpcb *inp) 123 { 124 struct ip_fw_args args; 125 struct m_tag *tag; 126 int ipfw; 127 int ret; 128 129 /* convert dir to IPFW values */ 130 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; 131 bzero(&args, sizeof(args)); 132 133 again: 134 /* 135 * extract and remove the tag if present. If we are left 136 * with onepass, optimize the outgoing path. 137 */ 138 tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); 139 if (tag != NULL) { 140 args.rule = *((struct ipfw_rule_ref *)(tag+1)); 141 m_tag_delete(*m0, tag); 142 if (args.rule.info & IPFW_ONEPASS) 143 return (0); 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, ("%s: m0 is NULL", 154 __func__)); 155 156 /* breaking out of the switch means drop */ 157 ret = 0; /* default return value for pass */ 158 switch (ipfw) { 159 case IP_FW_PASS: 160 /* next_hop may be set by ipfw_chk */ 161 if (args.next_hop == NULL && args.next_hop6 == NULL) 162 break; /* pass */ 163 #if (!defined(INET6) && !defined(INET)) 164 ret = EACCES; 165 #else 166 { 167 struct m_tag *fwd_tag; 168 size_t len; 169 170 KASSERT(args.next_hop == NULL || args.next_hop6 == NULL, 171 ("%s: both next_hop=%p and next_hop6=%p not NULL", __func__, 172 args.next_hop, args.next_hop6)); 173 #ifdef INET6 174 if (args.next_hop6 != NULL) 175 len = sizeof(struct sockaddr_in6); 176 #endif 177 #ifdef INET 178 if (args.next_hop != NULL) 179 len = sizeof(struct sockaddr_in); 180 #endif 181 182 /* Incoming packets should not be tagged so we do not 183 * m_tag_find. Outgoing packets may be tagged, so we 184 * reuse the tag if present. 185 */ 186 fwd_tag = (dir == DIR_IN) ? NULL : 187 m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL); 188 if (fwd_tag != NULL) { 189 m_tag_unlink(*m0, fwd_tag); 190 } else { 191 fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD, len, 192 M_NOWAIT); 193 if (fwd_tag == NULL) { 194 ret = EACCES; 195 break; /* i.e. drop */ 196 } 197 } 198 #ifdef INET6 199 if (args.next_hop6 != NULL) { 200 bcopy(args.next_hop6, (fwd_tag+1), len); 201 if (in6_localip(&args.next_hop6->sin6_addr)) 202 (*m0)->m_flags |= M_FASTFWD_OURS; 203 (*m0)->m_flags |= M_IP6_NEXTHOP; 204 } 205 #endif 206 #ifdef INET 207 if (args.next_hop != NULL) { 208 bcopy(args.next_hop, (fwd_tag+1), len); 209 if (in_localip(args.next_hop->sin_addr)) 210 (*m0)->m_flags |= M_FASTFWD_OURS; 211 (*m0)->m_flags |= M_IP_NEXTHOP; 212 } 213 #endif 214 m_tag_prepend(*m0, fwd_tag); 215 } 216 #endif /* INET || INET6 */ 217 break; 218 219 case IP_FW_DENY: 220 ret = EACCES; 221 break; /* i.e. drop */ 222 223 case IP_FW_DUMMYNET: 224 ret = EACCES; 225 if (ip_dn_io_ptr == NULL) 226 break; /* i.e. drop */ 227 if (mtod(*m0, struct ip *)->ip_v == 4) 228 ret = ip_dn_io_ptr(m0, dir, &args); 229 else if (mtod(*m0, struct ip *)->ip_v == 6) 230 ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args); 231 else 232 break; /* drop it */ 233 /* 234 * XXX should read the return value. 235 * dummynet normally eats the packet and sets *m0=NULL 236 * unless the packet can be sent immediately. In this 237 * case args is updated and we should re-run the 238 * check without clearing args. 239 */ 240 if (*m0 != NULL) 241 goto again; 242 break; 243 244 case IP_FW_TEE: 245 case IP_FW_DIVERT: 246 if (ip_divert_ptr == NULL) { 247 ret = EACCES; 248 break; /* i.e. drop */ 249 } 250 ret = ipfw_divert(m0, dir, &args.rule, 251 (ipfw == IP_FW_TEE) ? 1 : 0); 252 /* continue processing for the original packet (tee). */ 253 if (*m0) 254 goto again; 255 break; 256 257 case IP_FW_NGTEE: 258 case IP_FW_NETGRAPH: 259 if (ng_ipfw_input_p == NULL) { 260 ret = EACCES; 261 break; /* i.e. drop */ 262 } 263 ret = ng_ipfw_input_p(m0, dir, &args, 264 (ipfw == IP_FW_NGTEE) ? 1 : 0); 265 if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */ 266 goto again; /* continue with packet */ 267 break; 268 269 case IP_FW_NAT: 270 /* honor one-pass in case of successful nat */ 271 if (V_fw_one_pass) 272 break; /* ret is already 0 */ 273 goto again; 274 275 case IP_FW_REASS: 276 goto again; /* continue with packet */ 277 278 default: 279 KASSERT(0, ("%s: unknown retval", __func__)); 280 } 281 282 if (ret != 0) { 283 if (*m0) 284 FREE_PKT(*m0); 285 *m0 = NULL; 286 } 287 288 return ret; 289 } 290 291 /* 292 * ipfw processing for ethernet packets (in and out). 293 * Inteface is NULL from ether_demux, and ifp from 294 * ether_output_frame. 295 */ 296 int 297 ipfw_check_frame(void *arg, struct mbuf **m0, struct ifnet *dst, int dir, 298 struct inpcb *inp) 299 { 300 struct ether_header *eh; 301 struct ether_header save_eh; 302 struct mbuf *m; 303 int i, ret; 304 struct ip_fw_args args; 305 struct m_tag *mtag; 306 307 /* fetch start point from rule, if any */ 308 mtag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); 309 if (mtag == NULL) { 310 args.rule.slot = 0; 311 } else { 312 /* dummynet packet, already partially processed */ 313 struct ipfw_rule_ref *r; 314 315 /* XXX can we free it after use ? */ 316 mtag->m_tag_id = PACKET_TAG_NONE; 317 r = (struct ipfw_rule_ref *)(mtag + 1); 318 if (r->info & IPFW_ONEPASS) 319 return (0); 320 args.rule = *r; 321 } 322 323 /* I need some amt of data to be contiguous */ 324 m = *m0; 325 i = min(m->m_pkthdr.len, max_protohdr); 326 if (m->m_len < i) { 327 m = m_pullup(m, i); 328 if (m == NULL) { 329 *m0 = m; 330 return (0); 331 } 332 } 333 eh = mtod(m, struct ether_header *); 334 save_eh = *eh; /* save copy for restore below */ 335 m_adj(m, ETHER_HDR_LEN); /* strip ethernet header */ 336 337 args.m = m; /* the packet we are looking at */ 338 args.oif = dir == PFIL_OUT ? dst: NULL; /* destination, if any */ 339 args.next_hop = NULL; /* we do not support forward yet */ 340 args.next_hop6 = NULL; /* we do not support forward yet */ 341 args.eh = &save_eh; /* MAC header for bridged/MAC packets */ 342 args.inp = NULL; /* used by ipfw uid/gid/jail rules */ 343 i = ipfw_chk(&args); 344 m = args.m; 345 if (m != NULL) { 346 /* 347 * Restore Ethernet header, as needed, in case the 348 * mbuf chain was replaced by ipfw. 349 */ 350 M_PREPEND(m, ETHER_HDR_LEN, M_NOWAIT); 351 if (m == NULL) { 352 *m0 = NULL; 353 return (0); 354 } 355 if (eh != mtod(m, struct ether_header *)) 356 bcopy(&save_eh, mtod(m, struct ether_header *), 357 ETHER_HDR_LEN); 358 } 359 *m0 = m; 360 361 ret = 0; 362 /* Check result of ipfw_chk() */ 363 switch (i) { 364 case IP_FW_PASS: 365 break; 366 367 case IP_FW_DENY: 368 ret = EACCES; 369 break; /* i.e. drop */ 370 371 case IP_FW_DUMMYNET: 372 ret = EACCES; 373 int dir; 374 375 if (ip_dn_io_ptr == NULL) 376 break; /* i.e. drop */ 377 378 *m0 = NULL; 379 dir = PROTO_LAYER2 | (dst ? DIR_OUT : DIR_IN); 380 ip_dn_io_ptr(&m, dir, &args); 381 return 0; 382 383 default: 384 KASSERT(0, ("%s: unknown retval", __func__)); 385 } 386 387 if (ret != 0) { 388 if (*m0) 389 FREE_PKT(*m0); 390 *m0 = NULL; 391 } 392 393 return ret; 394 } 395 396 /* do the divert, return 1 on error 0 on success */ 397 static int 398 ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule, 399 int tee) 400 { 401 /* 402 * ipfw_chk() has already tagged the packet with the divert tag. 403 * If tee is set, copy packet and return original. 404 * If not tee, consume packet and send it to divert socket. 405 */ 406 struct mbuf *clone; 407 struct ip *ip = mtod(*m0, struct ip *); 408 struct m_tag *tag; 409 410 /* Cloning needed for tee? */ 411 if (tee == 0) { 412 clone = *m0; /* use the original mbuf */ 413 *m0 = NULL; 414 } else { 415 clone = m_dup(*m0, M_NOWAIT); 416 /* If we cannot duplicate the mbuf, we sacrifice the divert 417 * chain and continue with the tee-ed packet. 418 */ 419 if (clone == NULL) 420 return 1; 421 } 422 423 /* 424 * Divert listeners can normally handle non-fragmented packets, 425 * but we can only reass in the non-tee case. 426 * This means that listeners on a tee rule may get fragments, 427 * and have to live with that. 428 * Note that we now have the 'reass' ipfw option so if we care 429 * we can do it before a 'tee'. 430 */ 431 if (!tee) switch (ip->ip_v) { 432 case IPVERSION: 433 if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) { 434 int hlen; 435 struct mbuf *reass; 436 437 reass = ip_reass(clone); /* Reassemble packet. */ 438 if (reass == NULL) 439 return 0; /* not an error */ 440 /* if reass = NULL then it was consumed by ip_reass */ 441 /* 442 * IP header checksum fixup after reassembly and leave header 443 * in network byte order. 444 */ 445 ip = mtod(reass, struct ip *); 446 hlen = ip->ip_hl << 2; 447 ip->ip_sum = 0; 448 if (hlen == sizeof(struct ip)) 449 ip->ip_sum = in_cksum_hdr(ip); 450 else 451 ip->ip_sum = in_cksum(reass, hlen); 452 clone = reass; 453 } 454 break; 455 #ifdef INET6 456 case IPV6_VERSION >> 4: 457 { 458 struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *); 459 460 if (ip6->ip6_nxt == IPPROTO_FRAGMENT) { 461 int nxt, off; 462 463 off = sizeof(struct ip6_hdr); 464 nxt = frag6_input(&clone, &off, 0); 465 if (nxt == IPPROTO_DONE) 466 return (0); 467 } 468 break; 469 } 470 #endif 471 } 472 473 /* attach a tag to the packet with the reinject info */ 474 tag = m_tag_alloc(MTAG_IPFW_RULE, 0, 475 sizeof(struct ipfw_rule_ref), M_NOWAIT); 476 if (tag == NULL) { 477 FREE_PKT(clone); 478 return 1; 479 } 480 *((struct ipfw_rule_ref *)(tag+1)) = *rule; 481 m_tag_prepend(clone, tag); 482 483 /* Do the dirty job... */ 484 ip_divert_ptr(clone, incoming); 485 return 0; 486 } 487 488 /* 489 * attach or detach hooks for a given protocol family 490 */ 491 static int 492 ipfw_hook(int onoff, int pf) 493 { 494 struct pfil_head *pfh; 495 void *hook_func; 496 497 pfh = pfil_head_get(PFIL_TYPE_AF, pf); 498 if (pfh == NULL) 499 return ENOENT; 500 501 hook_func = (pf == AF_LINK) ? ipfw_check_frame : ipfw_check_packet; 502 503 (void) (onoff ? pfil_add_hook : pfil_remove_hook) 504 (hook_func, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh); 505 506 return 0; 507 } 508 509 int 510 ipfw_attach_hooks(int arg) 511 { 512 int error = 0; 513 514 if (arg == 0) /* detach */ 515 ipfw_hook(0, AF_INET); 516 else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) { 517 error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */ 518 printf("ipfw_hook() error\n"); 519 } 520 #ifdef INET6 521 if (arg == 0) /* detach */ 522 ipfw_hook(0, AF_INET6); 523 else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) { 524 error = ENOENT; 525 printf("ipfw6_hook() error\n"); 526 } 527 #endif 528 if (arg == 0) /* detach */ 529 ipfw_hook(0, AF_LINK); 530 else if (V_fwlink_enable && ipfw_hook(1, AF_LINK) != 0) { 531 error = ENOENT; 532 printf("ipfw_link_hook() error\n"); 533 } 534 return error; 535 } 536 537 int 538 ipfw_chg_hook(SYSCTL_HANDLER_ARGS) 539 { 540 int newval; 541 int error; 542 int af; 543 544 if (arg1 == &V_fw_enable) 545 af = AF_INET; 546 #ifdef INET6 547 else if (arg1 == &V_fw6_enable) 548 af = AF_INET6; 549 #endif 550 else if (arg1 == &V_fwlink_enable) 551 af = AF_LINK; 552 else 553 return (EINVAL); 554 555 newval = *(int *)arg1; 556 /* Handle sysctl change */ 557 error = sysctl_handle_int(oidp, &newval, 0, req); 558 559 if (error) 560 return (error); 561 562 /* Formalize new value */ 563 newval = (newval) ? 1 : 0; 564 565 if (*(int *)arg1 == newval) 566 return (0); 567 568 error = ipfw_hook(newval, af); 569 if (error) 570 return (error); 571 *(int *)arg1 = newval; 572 573 return (0); 574 } 575 /* end of file */ 576