1 /* 2 * Copyright (c) 1982, 1986, 1988, 1993 3 * The Regents of the University of California. 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 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: src/sys/netinet/ip_divert.c,v 1.42.2.6 2003/01/23 21:06:45 sam Exp $ 30 */ 31 32 #define _IP_VHL 33 34 #include "opt_inet.h" 35 #include "opt_ipdivert.h" 36 37 #ifndef INET 38 #error "IPDIVERT requires INET." 39 #endif 40 41 #include <sys/param.h> 42 #include <sys/kernel.h> 43 #include <sys/malloc.h> 44 #include <sys/mbuf.h> 45 #include <sys/socket.h> 46 #include <sys/protosw.h> 47 #include <sys/socketvar.h> 48 #include <sys/socketvar2.h> 49 #include <sys/sysctl.h> 50 #include <sys/systm.h> 51 #include <sys/proc.h> 52 #include <sys/priv.h> 53 #include <sys/in_cksum.h> 54 #include <sys/lock.h> 55 #include <sys/msgport.h> 56 57 #include <net/if.h> 58 #include <net/route.h> 59 60 #include <net/netmsg2.h> 61 #include <net/netisr2.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_systm.h> 65 #include <netinet/ip.h> 66 #include <netinet/in_pcb.h> 67 #include <netinet/in_var.h> 68 #include <netinet/ip_var.h> 69 #include <netinet/ip_divert.h> 70 71 /* 72 * Divert sockets 73 */ 74 75 /* 76 * Allocate enough space to hold a full IP packet 77 */ 78 #define DIVSNDQ (65536 + 100) 79 #define DIVRCVQ (65536 + 100) 80 81 #define DIV_IS_OUTPUT(sin) ((sin) == NULL || (sin)->sin_addr.s_addr == 0) 82 83 #define DIV_OUTPUT 0x10000 84 #define DIV_INPUT 0x20000 85 86 /* 87 * Divert sockets work in conjunction with ipfw, see the divert(4) 88 * manpage for features. 89 * Internally, packets selected by ipfw in ip_input() or ip_output(), 90 * and never diverted before, are passed to the input queue of the 91 * divert socket with a given 'divert_port' number (as specified in 92 * the matching ipfw rule), and they are tagged with a 16 bit cookie 93 * (representing the rule number of the matching ipfw rule), which 94 * is passed to process reading from the socket. 95 * 96 * Packets written to the divert socket are again tagged with a cookie 97 * (usually the same as above) and a destination address. 98 * If the destination address is INADDR_ANY then the packet is 99 * treated as outgoing and sent to ip_output(), otherwise it is 100 * treated as incoming and sent to ip_input(). 101 * In both cases, the packet is tagged with the cookie. 102 * 103 * On reinjection, processing in ip_input() and ip_output() 104 * will be exactly the same as for the original packet, except that 105 * ipfw processing will start at the rule number after the one 106 * written in the cookie (so, tagging a packet with a cookie of 0 107 * will cause it to be effectively considered as a standard packet). 108 */ 109 110 /* Internal variables */ 111 static struct inpcbinfo divcbinfo; 112 static struct inpcbportinfo divcbportinfo; 113 114 static u_long div_sendspace = DIVSNDQ; /* XXX sysctl ? */ 115 static u_long div_recvspace = DIVRCVQ; /* XXX sysctl ? */ 116 117 static struct mbuf *ip_divert(struct mbuf *, int, int); 118 119 /* 120 * Initialize divert connection block queue. 121 */ 122 void 123 div_init(void) 124 { 125 in_pcbinfo_init(&divcbinfo, 0, FALSE); 126 in_pcbportinfo_init(&divcbportinfo, 1, 0); 127 /* 128 * XXX We don't use the hash list for divert IP, but it's easier 129 * to allocate a one entry hash list than it is to check all 130 * over the place for hashbase == NULL. 131 */ 132 divcbinfo.hashbase = hashinit(1, M_PCB, &divcbinfo.hashmask); 133 in_pcbportinfo_set(&divcbinfo, &divcbportinfo, 1); 134 divcbinfo.wildcardhashbase = hashinit(1, M_PCB, 135 &divcbinfo.wildcardhashmask); 136 divcbinfo.ipi_size = sizeof(struct inpcb); 137 ip_divert_p = ip_divert; 138 } 139 140 /* 141 * IPPROTO_DIVERT is not a real IP protocol; don't allow any packets 142 * with that protocol number to enter the system from the outside. 143 */ 144 int 145 div_input(struct mbuf **mp, int *offp, int proto) 146 { 147 struct mbuf *m = *mp; 148 149 ipstat.ips_noproto++; 150 m_freem(m); 151 return(IPPROTO_DONE); 152 } 153 154 /* 155 * Divert a packet by passing it up to the divert socket at port 'port'. 156 * 157 * Setup generic address and protocol structures for div_input routine, 158 * then pass them along with mbuf chain. 159 */ 160 static void 161 div_packet(struct mbuf *m, int incoming, int port) 162 { 163 struct sockaddr_in divsrc = { sizeof divsrc, AF_INET }; 164 struct inpcb *inp; 165 struct socket *sa; 166 struct m_tag *mtag; 167 struct divert_info *divinfo; 168 u_int16_t nport; 169 170 ASSERT_NETISR0; 171 172 /* Locate the divert info */ 173 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 174 divinfo = m_tag_data(mtag); 175 divsrc.sin_port = divinfo->skipto; 176 177 /* 178 * Record receive interface address, if any. 179 * But only for incoming packets. 180 */ 181 divsrc.sin_addr.s_addr = 0; 182 if (incoming) { 183 struct ifaddr_container *ifac; 184 185 /* Find IP address for receive interface */ 186 TAILQ_FOREACH(ifac, &m->m_pkthdr.rcvif->if_addrheads[mycpuid], 187 ifa_link) { 188 struct ifaddr *ifa = ifac->ifa; 189 190 if (ifa->ifa_addr == NULL) 191 continue; 192 if (ifa->ifa_addr->sa_family != AF_INET) 193 continue; 194 divsrc.sin_addr = 195 ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr; 196 break; 197 } 198 } 199 /* 200 * Record the incoming interface name whenever we have one. 201 */ 202 if (m->m_pkthdr.rcvif) { 203 /* 204 * Hide the actual interface name in there in the 205 * sin_zero array. XXX This needs to be moved to a 206 * different sockaddr type for divert, e.g. 207 * sockaddr_div with multiple fields like 208 * sockaddr_dl. Presently we have only 7 bytes 209 * but that will do for now as most interfaces 210 * are 4 or less + 2 or less bytes for unit. 211 * There is probably a faster way of doing this, 212 * possibly taking it from the sockaddr_dl on the iface. 213 * This solves the problem of a P2P link and a LAN interface 214 * having the same address, which can result in the wrong 215 * interface being assigned to the packet when fed back 216 * into the divert socket. Theoretically if the daemon saves 217 * and re-uses the sockaddr_in as suggested in the man pages, 218 * this iface name will come along for the ride. 219 * (see div_output for the other half of this.) 220 */ 221 ksnprintf(divsrc.sin_zero, sizeof divsrc.sin_zero, "%s", 222 m->m_pkthdr.rcvif->if_xname); 223 } 224 225 /* Put packet on socket queue, if any */ 226 sa = NULL; 227 nport = htons((u_int16_t)port); 228 229 /* 230 * Following loop to locate the inpcb is MPSAFE since the inpcb 231 * insertion/removal happens on the same CPU (CPU0). 232 */ 233 LIST_FOREACH(inp, &divcbinfo.pcblisthead, inp_list) { 234 if (inp->inp_flags & INP_PLACEMARKER) 235 continue; 236 if (inp->inp_lport == nport) 237 sa = inp->inp_socket; 238 } 239 if (sa) { 240 lwkt_gettoken(&sa->so_rcv.ssb_token); 241 if (ssb_appendaddr(&sa->so_rcv, (struct sockaddr *)&divsrc, m, NULL) == 0) { 242 m_freem(m); 243 soroverflow(sa); 244 } else 245 sorwakeup(sa); 246 lwkt_reltoken(&sa->so_rcv.ssb_token); 247 } else { 248 m_freem(m); 249 ipstat.ips_noproto++; 250 ipstat.ips_delivered--; 251 } 252 } 253 254 static void 255 div_packet_handler(netmsg_t msg) 256 { 257 struct mbuf *m; 258 int port, incoming = 0; 259 260 m = msg->packet.nm_packet; 261 262 port = msg->lmsg.u.ms_result32 & 0xffff; 263 if (msg->lmsg.u.ms_result32 & DIV_INPUT) 264 incoming = 1; 265 div_packet(m, incoming, port); 266 /* no reply, msg embedded in mbuf */ 267 } 268 269 static void 270 divert_packet(struct mbuf *m, int incoming) 271 { 272 struct m_tag *mtag; 273 struct divert_info *divinfo; 274 int port; 275 276 M_ASSERTPKTHDR(m); 277 278 /* Assure header */ 279 if (m->m_len < sizeof(struct ip) && 280 (m = m_pullup(m, sizeof(struct ip))) == NULL) 281 return; 282 283 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 284 KASSERT(mtag != NULL, ("%s no divert tag!", __func__)); 285 divinfo = m_tag_data(mtag); 286 287 port = divinfo->port; 288 KASSERT(port != 0, ("%s: port=0", __func__)); 289 290 if (mycpuid != 0) { 291 struct netmsg_packet *nmp; 292 293 nmp = &m->m_hdr.mh_netmsg; 294 netmsg_init(&nmp->base, NULL, &netisr_apanic_rport, 295 0, div_packet_handler); 296 nmp->nm_packet = m; 297 298 nmp->base.lmsg.u.ms_result32 = port; /* port is 16bits */ 299 if (incoming) 300 nmp->base.lmsg.u.ms_result32 |= DIV_INPUT; 301 else 302 nmp->base.lmsg.u.ms_result32 |= DIV_OUTPUT; 303 304 lwkt_sendmsg(netisr_cpuport(0), &nmp->base.lmsg); 305 } else { 306 div_packet(m, incoming, port); 307 } 308 } 309 310 /* 311 * Deliver packet back into the IP processing machinery. 312 * 313 * If no address specified, or address is 0.0.0.0, send to ip_output(); 314 * otherwise, send to ip_input() and mark as having been received on 315 * the interface with that address. 316 */ 317 static int 318 div_output(struct socket *so, struct mbuf *m, 319 struct sockaddr_in *sin, struct mbuf *control) 320 { 321 int error = 0; 322 struct m_tag *mtag; 323 struct divert_info *divinfo; 324 325 ASSERT_NETISR0; 326 327 if (control) 328 m_freem(control); /* XXX */ 329 330 /* 331 * Prepare the tag for divert info. Note that a packet 332 * with a 0 tag in mh_data is effectively untagged, 333 * so we could optimize that case. 334 */ 335 mtag = m_tag_get(PACKET_TAG_IPFW_DIVERT, sizeof(*divinfo), M_NOWAIT); 336 if (mtag == NULL) { 337 error = ENOBUFS; 338 goto cantsend; 339 } 340 m_tag_prepend(m, mtag); 341 342 /* Loopback avoidance and state recovery */ 343 divinfo = m_tag_data(mtag); 344 if (sin) 345 divinfo->skipto = sin->sin_port; 346 else 347 divinfo->skipto = 0; 348 349 /* Reinject packet into the system as incoming or outgoing */ 350 if (DIV_IS_OUTPUT(sin)) { 351 struct ip *const ip = mtod(m, struct ip *); 352 353 /* Don't allow packet length sizes that will crash */ 354 if ((u_short)ntohs(ip->ip_len) > m->m_pkthdr.len) { 355 error = EINVAL; 356 goto cantsend; 357 } 358 359 /* Convert fields to host order for ip_output() */ 360 ip->ip_len = ntohs(ip->ip_len); 361 ip->ip_off = ntohs(ip->ip_off); 362 363 /* Send packet to output processing */ 364 ipstat.ips_rawout++; /* XXX */ 365 error = ip_output(m, NULL, NULL, 366 (so->so_options & SO_DONTROUTE) | 367 IP_ALLOWBROADCAST | IP_RAWOUTPUT, 368 NULL, NULL); 369 } else { 370 ip_input(m); 371 } 372 return error; 373 374 cantsend: 375 m_freem(m); 376 return error; 377 } 378 379 static void 380 div_attach(netmsg_t msg) 381 { 382 struct socket *so = msg->attach.base.nm_so; 383 int proto = msg->attach.nm_proto; 384 struct pru_attach_info *ai = msg->attach.nm_ai; 385 struct inpcb *inp; 386 int error; 387 388 ASSERT_NETISR0; 389 390 inp = so->so_pcb; 391 if (inp) 392 panic("div_attach"); 393 error = priv_check_cred(ai->p_ucred, PRIV_ROOT, NULL_CRED_OKAY); 394 if (error) 395 goto out; 396 397 error = soreserve(so, div_sendspace, div_recvspace, ai->sb_rlimit); 398 if (error) 399 goto out; 400 error = in_pcballoc(so, &divcbinfo); 401 if (error) 402 goto out; 403 inp = (struct inpcb *)so->so_pcb; 404 inp->inp_ip_p = proto; 405 inp->inp_flags |= INP_HDRINCL; 406 /* 407 * The socket is always "connected" because 408 * we always know "where" to send the packet. 409 */ 410 sosetstate(so, SS_ISCONNECTED); 411 error = 0; 412 out: 413 lwkt_replymsg(&msg->attach.base.lmsg, error); 414 } 415 416 static void 417 div_detach(netmsg_t msg) 418 { 419 struct socket *so = msg->detach.base.nm_so; 420 struct inpcb *inp; 421 422 ASSERT_NETISR0; 423 424 inp = so->so_pcb; 425 if (inp == NULL) 426 panic("div_detach"); 427 in_pcbdetach(inp); 428 lwkt_replymsg(&msg->detach.base.lmsg, 0); 429 } 430 431 static void 432 div_abort(netmsg_t msg) 433 { 434 /* 435 * Divert socket does not support listen(2), 436 * so this should never be called. 437 */ 438 panic("div_abort is called"); 439 } 440 441 static void 442 div_disconnect(netmsg_t msg) 443 { 444 struct socket *so = msg->disconnect.base.nm_so; 445 int error; 446 447 ASSERT_NETISR0; 448 449 if (so->so_state & SS_ISCONNECTED) { 450 soisdisconnected(so); 451 error = 0; 452 } else { 453 error = ENOTCONN; 454 } 455 lwkt_replymsg(&msg->disconnect.base.lmsg, error); 456 } 457 458 static void 459 div_bind(netmsg_t msg) 460 { 461 struct socket *so = msg->bind.base.nm_so; 462 struct sockaddr *nam = msg->bind.nm_nam; 463 int error; 464 465 ASSERT_NETISR0; 466 467 /* 468 * in_pcbbind assumes that nam is a sockaddr_in 469 * and in_pcbbind requires a valid address. Since divert 470 * sockets don't we need to make sure the address is 471 * filled in properly. 472 * XXX -- divert should not be abusing in_pcbind 473 * and should probably have its own family. 474 */ 475 if (nam->sa_family != AF_INET) { 476 error = EAFNOSUPPORT; 477 } else { 478 ((struct sockaddr_in *)nam)->sin_addr.s_addr = INADDR_ANY; 479 error = in_pcbbind(so->so_pcb, nam, msg->bind.nm_td); 480 } 481 lwkt_replymsg(&msg->bind.base.lmsg, error); 482 } 483 484 static void 485 div_shutdown(netmsg_t msg) 486 { 487 struct socket *so = msg->shutdown.base.nm_so; 488 489 ASSERT_NETISR0; 490 491 socantsendmore(so); 492 493 lwkt_replymsg(&msg->shutdown.base.lmsg, 0); 494 } 495 496 static void 497 div_send(netmsg_t msg) 498 { 499 struct socket *so = msg->send.base.nm_so; 500 struct mbuf *m = msg->send.nm_m; 501 struct sockaddr *nam = msg->send.nm_addr; 502 struct mbuf *control = msg->send.nm_control; 503 int error; 504 505 /* Length check already done in ip_hashfn() */ 506 KASSERT(m->m_len >= sizeof(struct ip), ("IP header not in one mbuf")); 507 508 /* Send packet */ 509 error = div_output(so, m, (struct sockaddr_in *)nam, control); 510 lwkt_replymsg(&msg->send.base.lmsg, error); 511 } 512 513 SYSCTL_DECL(_net_inet_divert); 514 SYSCTL_PROC(_net_inet_divert, OID_AUTO, pcblist, CTLFLAG_RD, &divcbinfo, 1, 515 in_pcblist_range, "S,xinpcb", "List of active divert sockets"); 516 517 struct pr_usrreqs div_usrreqs = { 518 .pru_abort = div_abort, 519 .pru_accept = pr_generic_notsupp, 520 .pru_attach = div_attach, 521 .pru_bind = div_bind, 522 .pru_connect = pr_generic_notsupp, 523 .pru_connect2 = pr_generic_notsupp, 524 .pru_control = in_control_dispatch, 525 .pru_detach = div_detach, 526 .pru_disconnect = div_disconnect, 527 .pru_listen = pr_generic_notsupp, 528 .pru_peeraddr = in_setpeeraddr_dispatch, 529 .pru_rcvd = pr_generic_notsupp, 530 .pru_rcvoob = pr_generic_notsupp, 531 .pru_send = div_send, 532 .pru_sense = pru_sense_null, 533 .pru_shutdown = div_shutdown, 534 .pru_sockaddr = in_setsockaddr_dispatch, 535 .pru_sosend = sosend, 536 .pru_soreceive = soreceive 537 }; 538 539 static struct mbuf * 540 ip_divert_out(struct mbuf *m, int tee) 541 { 542 struct mbuf *clone = NULL; 543 struct ip *ip = mtod(m, struct ip *); 544 545 /* Clone packet if we're doing a 'tee' */ 546 if (tee) 547 clone = m_dup(m, M_NOWAIT); 548 549 /* 550 * XXX 551 * delayed checksums are not currently compatible 552 * with divert sockets. 553 */ 554 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) { 555 in_delayed_cksum(m); 556 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA; 557 } 558 559 /* Restore packet header fields to original values */ 560 ip->ip_len = htons(ip->ip_len); 561 ip->ip_off = htons(ip->ip_off); 562 563 /* Deliver packet to divert input routine */ 564 divert_packet(m, 0); 565 566 /* If 'tee', continue with original packet */ 567 return clone; 568 } 569 570 static struct mbuf * 571 ip_divert_in(struct mbuf *m, int tee) 572 { 573 struct mbuf *clone = NULL; 574 struct ip *ip = mtod(m, struct ip *); 575 struct m_tag *mtag; 576 577 if (ip->ip_off & (IP_MF | IP_OFFMASK)) { 578 const struct divert_info *divinfo; 579 u_short frag_off; 580 int hlen; 581 582 /* 583 * Only trust divert info in the fragment 584 * at offset 0. 585 */ 586 frag_off = ip->ip_off << 3; 587 if (frag_off != 0) { 588 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 589 m_tag_delete(m, mtag); 590 } 591 592 /* 593 * Attempt reassembly; if it succeeds, proceed. 594 * ip_reass() will return a different mbuf. 595 */ 596 m = ip_reass(m); 597 if (m == NULL) 598 return NULL; 599 ip = mtod(m, struct ip *); 600 601 /* Caller need to redispatch the packet, if it is for us */ 602 m->m_pkthdr.fw_flags |= FW_MBUF_REDISPATCH; 603 604 /* 605 * Get the header length of the reassembled 606 * packet 607 */ 608 hlen = IP_VHL_HL(ip->ip_vhl) << 2; 609 610 /* 611 * Restore original checksum before diverting 612 * packet 613 */ 614 ip->ip_len += hlen; 615 ip->ip_len = htons(ip->ip_len); 616 ip->ip_off = htons(ip->ip_off); 617 ip->ip_sum = 0; 618 if (hlen == sizeof(struct ip)) 619 ip->ip_sum = in_cksum_hdr(ip); 620 else 621 ip->ip_sum = in_cksum(m, hlen); 622 ip->ip_off = ntohs(ip->ip_off); 623 ip->ip_len = ntohs(ip->ip_len); 624 625 /* 626 * Only use the saved divert info 627 */ 628 mtag = m_tag_find(m, PACKET_TAG_IPFW_DIVERT, NULL); 629 if (mtag == NULL) { 630 /* Wrongly configured ipfw */ 631 kprintf("ip_input no divert info\n"); 632 m_freem(m); 633 return NULL; 634 } 635 divinfo = m_tag_data(mtag); 636 tee = divinfo->tee; 637 } 638 639 /* 640 * Divert or tee packet to the divert protocol if 641 * required. 642 */ 643 644 /* Clone packet if we're doing a 'tee' */ 645 if (tee) 646 clone = m_dup(m, M_NOWAIT); 647 648 /* 649 * Restore packet header fields to original 650 * values 651 */ 652 ip->ip_len = htons(ip->ip_len); 653 ip->ip_off = htons(ip->ip_off); 654 655 /* Deliver packet to divert input routine */ 656 divert_packet(m, 1); 657 658 /* Catch invalid reference */ 659 m = NULL; 660 ip = NULL; 661 662 ipstat.ips_delivered++; 663 664 /* If 'tee', continue with original packet */ 665 if (clone != NULL) { 666 /* 667 * Complete processing of the packet. 668 * XXX Better safe than sorry, remove the DIVERT tag. 669 */ 670 mtag = m_tag_find(clone, PACKET_TAG_IPFW_DIVERT, NULL); 671 KKASSERT(mtag != NULL); 672 m_tag_delete(clone, mtag); 673 } 674 return clone; 675 } 676 677 static struct mbuf * 678 ip_divert(struct mbuf *m, int tee, int incoming) 679 { 680 struct mbuf *ret; 681 682 if (incoming) 683 ret = ip_divert_in(m, tee); 684 else 685 ret = ip_divert_out(m, tee); 686 return ret; 687 } 688