1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2019 Isilon Systems, LLC. 5 * Copyright (c) 2005-2014 Sandvine Incorporated. All rights reserved. 6 * Copyright (c) 2000 Darrell Anderson 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 __FBSDID("$FreeBSD$"); 33 34 #include "opt_inet.h" 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/errno.h> 39 #include <sys/socket.h> 40 #include <sys/sysctl.h> 41 42 #include <net/ethernet.h> 43 #include <net/if.h> 44 #include <net/if_arp.h> 45 #include <net/if_dl.h> 46 #include <net/if_types.h> 47 #include <net/if_var.h> 48 49 #include <netinet/in.h> 50 #include <netinet/in_systm.h> 51 #include <netinet/in_var.h> 52 #include <netinet/ip.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/ip_options.h> 55 #include <netinet/udp.h> 56 #include <netinet/udp_var.h> 57 58 #include <machine/in_cksum.h> 59 #include <machine/pcb.h> 60 61 #include <net/debugnet.h> 62 #define DEBUGNET_INTERNAL 63 #include <net/debugnet_int.h> 64 65 int debugnet_arp_nretries = 3; 66 SYSCTL_INT(_net_debugnet, OID_AUTO, arp_nretries, CTLFLAG_RWTUN, 67 &debugnet_arp_nretries, 0, 68 "Number of ARP attempts before giving up"); 69 70 /* 71 * Handler for IP packets: checks their sanity and then processes any debugnet 72 * ACK packets it finds. 73 * 74 * It needs to partially replicate the behaviour of ip_input() and udp_input(). 75 * 76 * Parameters: 77 * pcb a pointer to the live debugnet PCB 78 * mb a pointer to an mbuf * containing the packet received 79 * Updates *mb if m_pullup et al change the pointer 80 * Assumes the calling function will take care of freeing the mbuf 81 */ 82 void 83 debugnet_handle_ip(struct debugnet_pcb *pcb, struct mbuf **mb) 84 { 85 struct ip *ip; 86 struct mbuf *m; 87 unsigned short hlen; 88 89 /* IP processing. */ 90 m = *mb; 91 if (m->m_pkthdr.len < sizeof(struct ip)) { 92 DNETDEBUG("dropping packet too small for IP header\n"); 93 return; 94 } 95 if (m->m_len < sizeof(struct ip)) { 96 m = m_pullup(m, sizeof(struct ip)); 97 *mb = m; 98 if (m == NULL) { 99 DNETDEBUG("m_pullup failed\n"); 100 return; 101 } 102 } 103 ip = mtod(m, struct ip *); 104 105 /* IP version. */ 106 if (ip->ip_v != IPVERSION) { 107 DNETDEBUG("bad IP version %d\n", ip->ip_v); 108 return; 109 } 110 111 /* Header length. */ 112 hlen = ip->ip_hl << 2; 113 if (hlen < sizeof(struct ip)) { 114 DNETDEBUG("bad IP header length (%hu)\n", hlen); 115 return; 116 } 117 if (hlen > m->m_len) { 118 m = m_pullup(m, hlen); 119 *mb = m; 120 if (m == NULL) { 121 DNETDEBUG("m_pullup failed\n"); 122 return; 123 } 124 ip = mtod(m, struct ip *); 125 } 126 /* Ignore packets with IP options. */ 127 if (hlen > sizeof(struct ip)) { 128 DNETDEBUG("drop packet with IP options\n"); 129 return; 130 } 131 132 #ifdef INVARIANTS 133 if ((IN_LOOPBACK(ntohl(ip->ip_dst.s_addr)) || 134 IN_LOOPBACK(ntohl(ip->ip_src.s_addr))) && 135 (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) { 136 DNETDEBUG("Bad IP header (RFC1122)\n"); 137 return; 138 } 139 #endif 140 141 /* Checksum. */ 142 if ((m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) != 0) { 143 if ((m->m_pkthdr.csum_flags & CSUM_IP_VALID) == 0) { 144 DNETDEBUG("bad IP checksum\n"); 145 return; 146 } 147 } else { 148 /* XXX */ ; 149 } 150 151 /* Convert fields to host byte order. */ 152 ip->ip_len = ntohs(ip->ip_len); 153 if (ip->ip_len < hlen) { 154 DNETDEBUG("IP packet smaller (%hu) than header (%hu)\n", 155 ip->ip_len, hlen); 156 return; 157 } 158 if (m->m_pkthdr.len < ip->ip_len) { 159 DNETDEBUG("IP packet bigger (%hu) than ethernet packet (%d)\n", 160 ip->ip_len, m->m_pkthdr.len); 161 return; 162 } 163 if (m->m_pkthdr.len > ip->ip_len) { 164 /* Truncate the packet to the IP length. */ 165 if (m->m_len == m->m_pkthdr.len) { 166 m->m_len = ip->ip_len; 167 m->m_pkthdr.len = ip->ip_len; 168 } else 169 m_adj(m, ip->ip_len - m->m_pkthdr.len); 170 } 171 172 ip->ip_off = ntohs(ip->ip_off); 173 174 /* Check that the source is the server's IP. */ 175 if (ip->ip_src.s_addr != pcb->dp_server) { 176 DNETDEBUG("drop packet not from server (from 0x%x)\n", 177 ip->ip_src.s_addr); 178 return; 179 } 180 181 /* Check if the destination IP is ours. */ 182 if (ip->ip_dst.s_addr != pcb->dp_client) { 183 DNETDEBUGV("drop packet not to our IP\n"); 184 return; 185 } 186 187 if (ip->ip_p != IPPROTO_UDP) { 188 DNETDEBUG("drop non-UDP packet\n"); 189 return; 190 } 191 192 /* Do not deal with fragments. */ 193 if ((ip->ip_off & (IP_MF | IP_OFFMASK)) != 0) { 194 DNETDEBUG("drop fragmented packet\n"); 195 return; 196 } 197 198 if ((m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) != 0) { 199 if ((m->m_pkthdr.csum_flags & CSUM_DATA_VALID) == 0) { 200 DNETDEBUG("bad UDP checksum\n"); 201 return; 202 } 203 } else { 204 /* XXX */ ; 205 } 206 207 /* UDP custom is to have packet length not include IP header. */ 208 ip->ip_len -= hlen; 209 210 /* Checked above before decoding IP header. */ 211 MPASS(m->m_pkthdr.len >= sizeof(struct ipovly)); 212 213 /* Put the UDP header at start of chain. */ 214 m_adj(m, sizeof(struct ipovly)); 215 debugnet_handle_udp(pcb, mb); 216 } 217 218 /* 219 * Builds and sends a single ARP request to locate the L2 address for a given 220 * INET address. 221 * 222 * Return value: 223 * 0 on success 224 * errno on error 225 */ 226 static int 227 debugnet_send_arp(struct debugnet_pcb *pcb, in_addr_t dst) 228 { 229 struct ether_addr bcast; 230 struct arphdr *ah; 231 struct ifnet *ifp; 232 struct mbuf *m; 233 int pktlen; 234 235 ifp = pcb->dp_ifp; 236 237 /* Fill-up a broadcast address. */ 238 memset(&bcast, 0xFF, ETHER_ADDR_LEN); 239 m = m_gethdr(M_NOWAIT, MT_DATA); 240 if (m == NULL) { 241 printf("%s: Out of mbufs\n", __func__); 242 return (ENOBUFS); 243 } 244 pktlen = arphdr_len2(ETHER_ADDR_LEN, sizeof(struct in_addr)); 245 m->m_len = pktlen; 246 m->m_pkthdr.len = pktlen; 247 MH_ALIGN(m, pktlen); 248 ah = mtod(m, struct arphdr *); 249 ah->ar_hrd = htons(ARPHRD_ETHER); 250 ah->ar_pro = htons(ETHERTYPE_IP); 251 ah->ar_hln = ETHER_ADDR_LEN; 252 ah->ar_pln = sizeof(struct in_addr); 253 ah->ar_op = htons(ARPOP_REQUEST); 254 memcpy(ar_sha(ah), IF_LLADDR(ifp), ETHER_ADDR_LEN); 255 ((struct in_addr *)ar_spa(ah))->s_addr = pcb->dp_client; 256 bzero(ar_tha(ah), ETHER_ADDR_LEN); 257 ((struct in_addr *)ar_tpa(ah))->s_addr = dst; 258 return (debugnet_ether_output(m, ifp, bcast, ETHERTYPE_ARP)); 259 } 260 261 /* 262 * Handler for ARP packets: checks their sanity and then 263 * 1. If the ARP is a request for our IP, respond with our MAC address 264 * 2. If the ARP is a response from our server, record its MAC address 265 * 266 * It needs to replicate partially the behaviour of arpintr() and 267 * in_arpinput(). 268 * 269 * Parameters: 270 * pcb a pointer to the live debugnet PCB 271 * mb a pointer to an mbuf * containing the packet received 272 * Updates *mb if m_pullup et al change the pointer 273 * Assumes the calling function will take care of freeing the mbuf 274 */ 275 void 276 debugnet_handle_arp(struct debugnet_pcb *pcb, struct mbuf **mb) 277 { 278 char buf[INET_ADDRSTRLEN]; 279 struct in_addr isaddr, itaddr; 280 struct ether_addr dst; 281 struct mbuf *m; 282 struct arphdr *ah; 283 struct ifnet *ifp; 284 uint8_t *enaddr; 285 int req_len, op; 286 287 m = *mb; 288 ifp = m->m_pkthdr.rcvif; 289 if (m->m_len < sizeof(struct arphdr)) { 290 m = m_pullup(m, sizeof(struct arphdr)); 291 *mb = m; 292 if (m == NULL) { 293 DNETDEBUG("runt packet: m_pullup failed\n"); 294 return; 295 } 296 } 297 298 ah = mtod(m, struct arphdr *); 299 if (ntohs(ah->ar_hrd) != ARPHRD_ETHER) { 300 DNETDEBUG("unknown hardware address 0x%2D)\n", 301 (unsigned char *)&ah->ar_hrd, ""); 302 return; 303 } 304 if (ntohs(ah->ar_pro) != ETHERTYPE_IP) { 305 DNETDEBUG("drop ARP for unknown protocol %d\n", 306 ntohs(ah->ar_pro)); 307 return; 308 } 309 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr)); 310 if (m->m_len < req_len) { 311 m = m_pullup(m, req_len); 312 *mb = m; 313 if (m == NULL) { 314 DNETDEBUG("runt packet: m_pullup failed\n"); 315 return; 316 } 317 } 318 ah = mtod(m, struct arphdr *); 319 320 op = ntohs(ah->ar_op); 321 memcpy(&isaddr, ar_spa(ah), sizeof(isaddr)); 322 memcpy(&itaddr, ar_tpa(ah), sizeof(itaddr)); 323 enaddr = (uint8_t *)IF_LLADDR(ifp); 324 325 if (memcmp(ar_sha(ah), enaddr, ifp->if_addrlen) == 0) { 326 DNETDEBUG("ignoring ARP from myself\n"); 327 return; 328 } 329 330 if (isaddr.s_addr == pcb->dp_client) { 331 printf("%s: %*D is using my IP address %s!\n", __func__, 332 ifp->if_addrlen, (u_char *)ar_sha(ah), ":", 333 inet_ntoa_r(isaddr, buf)); 334 return; 335 } 336 337 if (memcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen) == 0) { 338 DNETDEBUG("ignoring ARP from broadcast address\n"); 339 return; 340 } 341 342 if (op == ARPOP_REPLY) { 343 if (isaddr.s_addr != pcb->dp_gateway && 344 isaddr.s_addr != pcb->dp_server) { 345 inet_ntoa_r(isaddr, buf); 346 DNETDEBUG("ignoring ARP reply from %s (not configured" 347 " server or gateway)\n", buf); 348 return; 349 } 350 memcpy(pcb->dp_gw_mac.octet, ar_sha(ah), 351 min(ah->ar_hln, ETHER_ADDR_LEN)); 352 353 DNETDEBUG("got server MAC address %6D\n", 354 pcb->dp_gw_mac.octet, ":"); 355 356 MPASS(pcb->dp_state == DN_STATE_INIT); 357 pcb->dp_state = DN_STATE_HAVE_GW_MAC; 358 return; 359 } 360 361 if (op != ARPOP_REQUEST) { 362 DNETDEBUG("ignoring ARP non-request/reply\n"); 363 return; 364 } 365 366 if (itaddr.s_addr != pcb->dp_client) { 367 DNETDEBUG("ignoring ARP not to our IP\n"); 368 return; 369 } 370 371 memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln); 372 memcpy(ar_sha(ah), enaddr, ah->ar_hln); 373 memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln); 374 memcpy(ar_spa(ah), &itaddr, ah->ar_pln); 375 ah->ar_op = htons(ARPOP_REPLY); 376 ah->ar_pro = htons(ETHERTYPE_IP); 377 m->m_flags &= ~(M_BCAST|M_MCAST); 378 m->m_len = arphdr_len(ah); 379 m->m_pkthdr.len = m->m_len; 380 381 memcpy(dst.octet, ar_tha(ah), ETHER_ADDR_LEN); 382 debugnet_ether_output(m, ifp, dst, ETHERTYPE_ARP); 383 *mb = NULL; 384 } 385 386 /* 387 * Sends ARP requests to locate the server and waits for a response. 388 * We first try to ARP the server itself, and fall back to the provided 389 * gateway if the server appears to be off-link. 390 * 391 * Return value: 392 * 0 on success 393 * errno on error 394 */ 395 int 396 debugnet_arp_gw(struct debugnet_pcb *pcb) 397 { 398 in_addr_t dst; 399 int error, polls, retries; 400 401 dst = pcb->dp_server; 402 restart: 403 for (retries = 0; retries < debugnet_arp_nretries; retries++) { 404 error = debugnet_send_arp(pcb, dst); 405 if (error != 0) 406 return (error); 407 for (polls = 0; polls < debugnet_npolls && 408 pcb->dp_state < DN_STATE_HAVE_GW_MAC; polls++) { 409 debugnet_network_poll(pcb); 410 DELAY(500); 411 } 412 if (pcb->dp_state >= DN_STATE_HAVE_GW_MAC) 413 break; 414 printf("(ARP retry)"); 415 } 416 if (pcb->dp_state >= DN_STATE_HAVE_GW_MAC) 417 return (0); 418 if (dst == pcb->dp_server) { 419 printf("\nFailed to ARP server"); 420 if (pcb->dp_gateway != INADDR_ANY) { 421 printf(", trying to reach gateway...\n"); 422 dst = pcb->dp_gateway; 423 goto restart; 424 } else 425 printf(".\n"); 426 } else 427 printf("\nFailed to ARP gateway.\n"); 428 429 return (ETIMEDOUT); 430 } 431 432 /* 433 * Unreliable IPv4 transmission of an mbuf chain to the debugnet server 434 * Note: can't handle fragmentation; fails if the packet is larger than 435 * ifp->if_mtu after adding the UDP/IP headers 436 * 437 * Parameters: 438 * pcb The debugnet context block 439 * m mbuf chain 440 * 441 * Returns: 442 * int see errno.h, 0 for success 443 */ 444 int 445 debugnet_ip_output(struct debugnet_pcb *pcb, struct mbuf *m) 446 { 447 struct udphdr *udp; 448 struct ifnet *ifp; 449 struct ip *ip; 450 451 MPASS(pcb->dp_state >= DN_STATE_HAVE_GW_MAC); 452 453 ifp = pcb->dp_ifp; 454 455 M_PREPEND(m, sizeof(*ip), M_NOWAIT); 456 if (m == NULL) { 457 printf("%s: out of mbufs\n", __func__); 458 return (ENOBUFS); 459 } 460 461 if (m->m_pkthdr.len > ifp->if_mtu) { 462 printf("%s: Packet is too big: %d > MTU %u\n", __func__, 463 m->m_pkthdr.len, ifp->if_mtu); 464 m_freem(m); 465 return (ENOBUFS); 466 } 467 468 ip = mtod(m, void *); 469 udp = (void *)(ip + 1); 470 471 memset(ip, 0, offsetof(struct ip, ip_p)); 472 ip->ip_p = IPPROTO_UDP; 473 ip->ip_sum = udp->uh_ulen; 474 ip->ip_src = (struct in_addr) { pcb->dp_client }; 475 ip->ip_dst = (struct in_addr) { pcb->dp_server }; 476 477 /* Compute UDP-IPv4 checksum. */ 478 udp->uh_sum = in_cksum(m, m->m_pkthdr.len); 479 if (udp->uh_sum == 0) 480 udp->uh_sum = 0xffff; 481 482 ip->ip_v = IPVERSION; 483 ip->ip_hl = sizeof(*ip) >> 2; 484 ip->ip_tos = 0; 485 ip->ip_len = htons(m->m_pkthdr.len); 486 ip->ip_id = 0; 487 ip->ip_off = htons(IP_DF); 488 ip->ip_ttl = 255; 489 ip->ip_sum = 0; 490 ip->ip_sum = in_cksum(m, sizeof(struct ip)); 491 492 return (debugnet_ether_output(m, ifp, pcb->dp_gw_mac, ETHERTYPE_IP)); 493 } 494