ip_fw_pfil.c revision 225793
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: head/sys/netinet/ipfw/ip_fw_pfil.c 225793 2011-09-27 13:27:17Z bz $"); 29 30#include "opt_ipfw.h" 31#if !defined(KLD_MODULE) 32#include "opt_ipdn.h" 33#include "opt_inet.h" 34#include "opt_inet6.h" 35#ifndef INET 36#error IPFIREWALL requires INET. 37#endif /* INET */ 38#endif /* KLD_MODULE */ 39 40#include <sys/param.h> 41#include <sys/systm.h> 42#include <sys/malloc.h> 43#include <sys/mbuf.h> 44#include <sys/module.h> 45#include <sys/kernel.h> 46#include <sys/lock.h> 47#include <sys/rwlock.h> 48#include <sys/socket.h> 49#include <sys/sysctl.h> 50 51#include <net/if.h> 52#include <net/route.h> 53#include <net/pfil.h> 54#include <net/vnet.h> 55 56#include <netinet/in.h> 57#include <netinet/in_systm.h> 58#include <netinet/ip.h> 59#include <netinet/ip_var.h> 60#include <netinet/ip_fw.h> 61#ifdef INET6 62#include <netinet/ip6.h> 63#include <netinet6/ip6_var.h> 64#endif 65#include <netinet/ipfw/ip_fw_private.h> 66#include <netgraph/ng_ipfw.h> 67 68#include <machine/in_cksum.h> 69 70static VNET_DEFINE(int, fw_enable) = 1; 71#define V_fw_enable VNET(fw_enable) 72 73#ifdef INET6 74static VNET_DEFINE(int, fw6_enable) = 1; 75#define V_fw6_enable VNET(fw6_enable) 76#endif 77 78int ipfw_chg_hook(SYSCTL_HANDLER_ARGS); 79 80/* Forward declarations. */ 81static int ipfw_divert(struct mbuf **, int, struct ipfw_rule_ref *, int); 82 83#ifdef SYSCTL_NODE 84 85SYSBEGIN(f1) 86 87SYSCTL_DECL(_net_inet_ip_fw); 88SYSCTL_VNET_PROC(_net_inet_ip_fw, OID_AUTO, enable, 89 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, &VNET_NAME(fw_enable), 0, 90 ipfw_chg_hook, "I", "Enable ipfw"); 91#ifdef INET6 92SYSCTL_DECL(_net_inet6_ip6_fw); 93SYSCTL_VNET_PROC(_net_inet6_ip6_fw, OID_AUTO, enable, 94 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE3, &VNET_NAME(fw6_enable), 0, 95 ipfw_chg_hook, "I", "Enable ipfw+6"); 96#endif /* INET6 */ 97 98SYSEND 99 100#endif /* SYSCTL_NODE */ 101 102/* 103 * The pfilter hook to pass packets to ipfw_chk and then to 104 * dummynet, divert, netgraph or other modules. 105 * The packet may be consumed. 106 */ 107int 108ipfw_check_hook(void *arg, struct mbuf **m0, struct ifnet *ifp, int dir, 109 struct inpcb *inp) 110{ 111 struct ip_fw_args args; 112 struct m_tag *tag; 113 int ipfw; 114 int ret; 115 116 /* all the processing now uses ip_len in net format */ 117 if (mtod(*m0, struct ip *)->ip_v == 4) 118 SET_NET_IPLEN(mtod(*m0, struct ip *)); 119 120 /* convert dir to IPFW values */ 121 dir = (dir == PFIL_IN) ? DIR_IN : DIR_OUT; 122 bzero(&args, sizeof(args)); 123 124again: 125 /* 126 * extract and remove the tag if present. If we are left 127 * with onepass, optimize the outgoing path. 128 */ 129 tag = m_tag_locate(*m0, MTAG_IPFW_RULE, 0, NULL); 130 if (tag != NULL) { 131 args.rule = *((struct ipfw_rule_ref *)(tag+1)); 132 m_tag_delete(*m0, tag); 133 if (args.rule.info & IPFW_ONEPASS) { 134 if (mtod(*m0, struct ip *)->ip_v == 4) 135 SET_HOST_IPLEN(mtod(*m0, struct ip *)); 136 return (0); 137 } 138 } 139 140 args.m = *m0; 141 args.oif = dir == DIR_OUT ? ifp : NULL; 142 args.inp = inp; 143 144 ipfw = ipfw_chk(&args); 145 *m0 = args.m; 146 147 KASSERT(*m0 != NULL || ipfw == IP_FW_DENY, ("%s: m0 is NULL", 148 __func__)); 149 150 /* breaking out of the switch means drop */ 151 ret = 0; /* default return value for pass */ 152 switch (ipfw) { 153 case IP_FW_PASS: 154 /* next_hop may be set by ipfw_chk */ 155 if (args.next_hop == NULL && args.next_hop6 == NULL) 156 break; /* pass */ 157#if !defined(IPFIREWALL_FORWARD) || (!defined(INET6) && !defined(INET)) 158 ret = EACCES; 159#else 160 { 161 struct m_tag *fwd_tag; 162 size_t len; 163 164 KASSERT(args.next_hop == NULL || args.next_hop6 == NULL, 165 ("%s: both next_hop=%p and next_hop6=%p not NULL", __func__, 166 args.next_hop, args.next_hop6)); 167#ifdef INET6 168 if (args.next_hop6 != NULL) 169 len = sizeof(struct sockaddr_in6); 170#endif 171#ifdef INET 172 if (args.next_hop != NULL) 173 len = sizeof(struct sockaddr_in); 174#endif 175 176 /* Incoming packets should not be tagged so we do not 177 * m_tag_find. Outgoing packets may be tagged, so we 178 * reuse the tag if present. 179 */ 180 fwd_tag = (dir == DIR_IN) ? NULL : 181 m_tag_find(*m0, PACKET_TAG_IPFORWARD, NULL); 182 if (fwd_tag != NULL) { 183 m_tag_unlink(*m0, fwd_tag); 184 } else { 185 fwd_tag = m_tag_get(PACKET_TAG_IPFORWARD, len, 186 M_NOWAIT); 187 if (fwd_tag == NULL) { 188 ret = EACCES; 189 break; /* i.e. drop */ 190 } 191 } 192#ifdef INET6 193 if (args.next_hop6 != NULL) { 194 bcopy(args.next_hop6, (fwd_tag+1), len); 195 if (in6_localip(&args.next_hop6->sin6_addr)) 196 (*m0)->m_flags |= M_FASTFWD_OURS; 197 } 198#endif 199#ifdef INET 200 if (args.next_hop != NULL) { 201 bcopy(args.next_hop, (fwd_tag+1), len); 202 if (in_localip(args.next_hop->sin_addr)) 203 (*m0)->m_flags |= M_FASTFWD_OURS; 204 } 205#endif 206 m_tag_prepend(*m0, fwd_tag); 207 } 208#endif /* IPFIREWALL_FORWARD */ 209 break; 210 211 case IP_FW_DENY: 212 ret = EACCES; 213 break; /* i.e. drop */ 214 215 case IP_FW_DUMMYNET: 216 ret = EACCES; 217 if (ip_dn_io_ptr == NULL) 218 break; /* i.e. drop */ 219 if (mtod(*m0, struct ip *)->ip_v == 4) 220 ret = ip_dn_io_ptr(m0, dir, &args); 221 else if (mtod(*m0, struct ip *)->ip_v == 6) 222 ret = ip_dn_io_ptr(m0, dir | PROTO_IPV6, &args); 223 else 224 break; /* drop it */ 225 /* 226 * XXX should read the return value. 227 * dummynet normally eats the packet and sets *m0=NULL 228 * unless the packet can be sent immediately. In this 229 * case args is updated and we should re-run the 230 * check without clearing args. 231 */ 232 if (*m0 != NULL) 233 goto again; 234 break; 235 236 case IP_FW_TEE: 237 case IP_FW_DIVERT: 238 if (ip_divert_ptr == NULL) { 239 ret = EACCES; 240 break; /* i.e. drop */ 241 } 242 ret = ipfw_divert(m0, dir, &args.rule, 243 (ipfw == IP_FW_TEE) ? 1 : 0); 244 /* continue processing for the original packet (tee). */ 245 if (*m0) 246 goto again; 247 break; 248 249 case IP_FW_NGTEE: 250 case IP_FW_NETGRAPH: 251 if (ng_ipfw_input_p == NULL) { 252 ret = EACCES; 253 break; /* i.e. drop */ 254 } 255 ret = ng_ipfw_input_p(m0, dir, &args, 256 (ipfw == IP_FW_NGTEE) ? 1 : 0); 257 if (ipfw == IP_FW_NGTEE) /* ignore errors for NGTEE */ 258 goto again; /* continue with packet */ 259 break; 260 261 case IP_FW_NAT: 262 /* honor one-pass in case of successful nat */ 263 if (V_fw_one_pass) 264 break; /* ret is already 0 */ 265 goto again; 266 267 case IP_FW_REASS: 268 goto again; /* continue with packet */ 269 270 default: 271 KASSERT(0, ("%s: unknown retval", __func__)); 272 } 273 274 if (ret != 0) { 275 if (*m0) 276 FREE_PKT(*m0); 277 *m0 = NULL; 278 } 279 if (*m0 && mtod(*m0, struct ip *)->ip_v == 4) 280 SET_HOST_IPLEN(mtod(*m0, struct ip *)); 281 return ret; 282} 283 284/* do the divert, return 1 on error 0 on success */ 285static int 286ipfw_divert(struct mbuf **m0, int incoming, struct ipfw_rule_ref *rule, 287 int tee) 288{ 289 /* 290 * ipfw_chk() has already tagged the packet with the divert tag. 291 * If tee is set, copy packet and return original. 292 * If not tee, consume packet and send it to divert socket. 293 */ 294 struct mbuf *clone; 295 struct ip *ip = mtod(*m0, struct ip *); 296 struct m_tag *tag; 297 298 /* Cloning needed for tee? */ 299 if (tee == 0) { 300 clone = *m0; /* use the original mbuf */ 301 *m0 = NULL; 302 } else { 303 clone = m_dup(*m0, M_DONTWAIT); 304 /* If we cannot duplicate the mbuf, we sacrifice the divert 305 * chain and continue with the tee-ed packet. 306 */ 307 if (clone == NULL) 308 return 1; 309 } 310 311 /* 312 * Divert listeners can normally handle non-fragmented packets, 313 * but we can only reass in the non-tee case. 314 * This means that listeners on a tee rule may get fragments, 315 * and have to live with that. 316 * Note that we now have the 'reass' ipfw option so if we care 317 * we can do it before a 'tee'. 318 */ 319 if (!tee) switch (ip->ip_v) { 320 case IPVERSION: 321 if (ntohs(ip->ip_off) & (IP_MF | IP_OFFMASK)) { 322 int hlen; 323 struct mbuf *reass; 324 325 SET_HOST_IPLEN(ip); /* ip_reass wants host order */ 326 reass = ip_reass(clone); /* Reassemble packet. */ 327 if (reass == NULL) 328 return 0; /* not an error */ 329 /* if reass = NULL then it was consumed by ip_reass */ 330 /* 331 * IP header checksum fixup after reassembly and leave header 332 * in network byte order. 333 */ 334 ip = mtod(reass, struct ip *); 335 hlen = ip->ip_hl << 2; 336 SET_NET_IPLEN(ip); 337 ip->ip_sum = 0; 338 if (hlen == sizeof(struct ip)) 339 ip->ip_sum = in_cksum_hdr(ip); 340 else 341 ip->ip_sum = in_cksum(reass, hlen); 342 clone = reass; 343 } 344 break; 345#ifdef INET6 346 case IPV6_VERSION >> 4: 347 { 348 struct ip6_hdr *const ip6 = mtod(clone, struct ip6_hdr *); 349 350 if (ip6->ip6_nxt == IPPROTO_FRAGMENT) { 351 int nxt, off; 352 353 off = sizeof(struct ip6_hdr); 354 nxt = frag6_input(&clone, &off, 0); 355 if (nxt == IPPROTO_DONE) 356 return (0); 357 } 358 break; 359 } 360#endif 361 } 362 363 /* attach a tag to the packet with the reinject info */ 364 tag = m_tag_alloc(MTAG_IPFW_RULE, 0, 365 sizeof(struct ipfw_rule_ref), M_NOWAIT); 366 if (tag == NULL) { 367 FREE_PKT(clone); 368 return 1; 369 } 370 *((struct ipfw_rule_ref *)(tag+1)) = *rule; 371 m_tag_prepend(clone, tag); 372 373 /* Do the dirty job... */ 374 ip_divert_ptr(clone, incoming); 375 return 0; 376} 377 378/* 379 * attach or detach hooks for a given protocol family 380 */ 381static int 382ipfw_hook(int onoff, int pf) 383{ 384 struct pfil_head *pfh; 385 386 pfh = pfil_head_get(PFIL_TYPE_AF, pf); 387 if (pfh == NULL) 388 return ENOENT; 389 390 (void) (onoff ? pfil_add_hook : pfil_remove_hook) 391 (ipfw_check_hook, NULL, PFIL_IN | PFIL_OUT | PFIL_WAITOK, pfh); 392 393 return 0; 394} 395 396int 397ipfw_attach_hooks(int arg) 398{ 399 int error = 0; 400 401 if (arg == 0) /* detach */ 402 ipfw_hook(0, AF_INET); 403 else if (V_fw_enable && ipfw_hook(1, AF_INET) != 0) { 404 error = ENOENT; /* see ip_fw_pfil.c::ipfw_hook() */ 405 printf("ipfw_hook() error\n"); 406 } 407#ifdef INET6 408 if (arg == 0) /* detach */ 409 ipfw_hook(0, AF_INET6); 410 else if (V_fw6_enable && ipfw_hook(1, AF_INET6) != 0) { 411 error = ENOENT; 412 printf("ipfw6_hook() error\n"); 413 } 414#endif 415 return error; 416} 417 418int 419ipfw_chg_hook(SYSCTL_HANDLER_ARGS) 420{ 421 int enable; 422 int oldenable; 423 int error; 424 int af; 425 426 if (arg1 == &VNET_NAME(fw_enable)) { 427 enable = V_fw_enable; 428 af = AF_INET; 429 } 430#ifdef INET6 431 else if (arg1 == &VNET_NAME(fw6_enable)) { 432 enable = V_fw6_enable; 433 af = AF_INET6; 434 } 435#endif 436 else 437 return (EINVAL); 438 439 oldenable = enable; 440 441 error = sysctl_handle_int(oidp, &enable, 0, req); 442 443 if (error) 444 return (error); 445 446 enable = (enable) ? 1 : 0; 447 448 if (enable == oldenable) 449 return (0); 450 451 error = ipfw_hook(enable, af); 452 if (error) 453 return (error); 454 if (af == AF_INET) 455 V_fw_enable = enable; 456#ifdef INET6 457 else if (af == AF_INET6) 458 V_fw6_enable = enable; 459#endif 460 461 return (0); 462} 463/* end of file */ 464