1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
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 #include "opt_inet.h"
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/errno.h>
37 #include <sys/socket.h>
38 #include <sys/sysctl.h>
39
40 #include <net/ethernet.h>
41 #include <net/if.h>
42 #include <net/if_arp.h>
43 #include <net/if_dl.h>
44 #include <net/if_types.h>
45 #include <net/if_var.h>
46 #include <net/if_private.h>
47
48 #include <netinet/in.h>
49 #include <netinet/in_systm.h>
50 #include <netinet/in_var.h>
51 #include <netinet/ip.h>
52 #include <netinet/ip_var.h>
53 #include <netinet/ip_options.h>
54 #include <netinet/udp.h>
55
56 #include <machine/in_cksum.h>
57 #include <machine/pcb.h>
58
59 #include <net/debugnet.h>
60 #define DEBUGNET_INTERNAL
61 #include <net/debugnet_int.h>
62
63 int debugnet_arp_nretries = 3;
64 SYSCTL_INT(_net_debugnet, OID_AUTO, arp_nretries, CTLFLAG_RWTUN,
65 &debugnet_arp_nretries, 0,
66 "Number of ARP attempts before giving up");
67
68 /*
69 * Handler for IP packets: checks their sanity and then processes any debugnet
70 * ACK packets it finds.
71 *
72 * It needs to partially replicate the behaviour of ip_input() and udp_input().
73 *
74 * Parameters:
75 * pcb a pointer to the live debugnet PCB
76 * mb a pointer to an mbuf * containing the packet received
77 * Updates *mb if m_pullup et al change the pointer
78 * Assumes the calling function will take care of freeing the mbuf
79 */
80 void
debugnet_handle_ip(struct debugnet_pcb * pcb,struct mbuf ** mb)81 debugnet_handle_ip(struct debugnet_pcb *pcb, struct mbuf **mb)
82 {
83 struct ip *ip;
84 struct mbuf *m;
85 unsigned short hlen;
86
87 if (pcb->dp_state < DN_STATE_HAVE_GW_MAC)
88 return;
89
90 /* IP processing. */
91 m = *mb;
92 if (m->m_pkthdr.len < sizeof(struct ip)) {
93 DNETDEBUG("dropping packet too small for IP header\n");
94 return;
95 }
96 if (m->m_len < sizeof(struct ip)) {
97 m = m_pullup(m, sizeof(struct ip));
98 *mb = m;
99 if (m == NULL) {
100 DNETDEBUG("m_pullup failed\n");
101 return;
102 }
103 }
104 ip = mtod(m, struct ip *);
105
106 /* IP version. */
107 if (ip->ip_v != IPVERSION) {
108 DNETDEBUG("bad IP version %d\n", ip->ip_v);
109 return;
110 }
111
112 /* Header length. */
113 hlen = ip->ip_hl << 2;
114 if (hlen < sizeof(struct ip)) {
115 DNETDEBUG("bad IP header length (%hu)\n", hlen);
116 return;
117 }
118 if (hlen > m->m_len) {
119 m = m_pullup(m, hlen);
120 *mb = m;
121 if (m == NULL) {
122 DNETDEBUG("m_pullup failed\n");
123 return;
124 }
125 ip = mtod(m, struct ip *);
126 }
127 /* Ignore packets with IP options. */
128 if (hlen > sizeof(struct ip)) {
129 DNETDEBUG("drop packet with IP options\n");
130 return;
131 }
132
133 #ifdef INVARIANTS
134 if ((IN_LOOPBACK(ntohl(ip->ip_dst.s_addr)) ||
135 IN_LOOPBACK(ntohl(ip->ip_src.s_addr))) &&
136 (m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
137 DNETDEBUG("Bad IP header (RFC1122)\n");
138 return;
139 }
140 #endif
141
142 /* Checksum. */
143 if ((m->m_pkthdr.csum_flags & CSUM_IP_CHECKED) != 0) {
144 if ((m->m_pkthdr.csum_flags & CSUM_IP_VALID) == 0) {
145 DNETDEBUG("bad IP checksum\n");
146 return;
147 }
148 } else {
149 /* XXX */ ;
150 }
151
152 /* Convert fields to host byte order. */
153 ip->ip_len = ntohs(ip->ip_len);
154 if (ip->ip_len < hlen) {
155 DNETDEBUG("IP packet smaller (%hu) than header (%hu)\n",
156 ip->ip_len, hlen);
157 return;
158 }
159 if (m->m_pkthdr.len < ip->ip_len) {
160 DNETDEBUG("IP packet bigger (%hu) than ethernet packet (%d)\n",
161 ip->ip_len, m->m_pkthdr.len);
162 return;
163 }
164 if (m->m_pkthdr.len > ip->ip_len) {
165 /* Truncate the packet to the IP length. */
166 if (m->m_len == m->m_pkthdr.len) {
167 m->m_len = ip->ip_len;
168 m->m_pkthdr.len = ip->ip_len;
169 } else
170 m_adj(m, ip->ip_len - m->m_pkthdr.len);
171 }
172
173 ip->ip_off = ntohs(ip->ip_off);
174
175 /* Check that the source is the server's IP. */
176 if (ip->ip_src.s_addr != pcb->dp_server) {
177 DNETDEBUG("drop packet not from server (from 0x%x)\n",
178 ip->ip_src.s_addr);
179 return;
180 }
181
182 /* Check if the destination IP is ours. */
183 if (ip->ip_dst.s_addr != pcb->dp_client) {
184 DNETDEBUGV("drop packet not to our IP\n");
185 return;
186 }
187
188 if (ip->ip_p != IPPROTO_UDP) {
189 DNETDEBUG("drop non-UDP packet\n");
190 return;
191 }
192
193 /* Do not deal with fragments. */
194 if ((ip->ip_off & (IP_MF | IP_OFFMASK)) != 0) {
195 DNETDEBUG("drop fragmented packet\n");
196 return;
197 }
198
199 if ((m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) != 0) {
200 if ((m->m_pkthdr.csum_flags & CSUM_DATA_VALID) == 0) {
201 DNETDEBUG("bad UDP checksum\n");
202 return;
203 }
204 } else {
205 /* XXX */ ;
206 }
207
208 /* UDP custom is to have packet length not include IP header. */
209 ip->ip_len -= hlen;
210
211 /* Checked above before decoding IP header. */
212 MPASS(m->m_pkthdr.len >= sizeof(struct ipovly));
213
214 /* Put the UDP header at start of chain. */
215 m_adj(m, sizeof(struct ipovly));
216 debugnet_handle_udp(pcb, mb);
217 }
218
219 /*
220 * Builds and sends a single ARP request to locate the L2 address for a given
221 * INET address.
222 *
223 * Return value:
224 * 0 on success
225 * errno on error
226 */
227 static int
debugnet_send_arp(struct debugnet_pcb * pcb,in_addr_t dst)228 debugnet_send_arp(struct debugnet_pcb *pcb, in_addr_t dst)
229 {
230 struct ether_addr bcast;
231 struct arphdr *ah;
232 struct ifnet *ifp;
233 struct mbuf *m;
234 int pktlen;
235
236 ifp = pcb->dp_ifp;
237
238 /* Fill-up a broadcast address. */
239 memset(&bcast, 0xFF, ETHER_ADDR_LEN);
240 m = m_gethdr(M_NOWAIT, MT_DATA);
241 if (m == NULL) {
242 printf("%s: Out of mbufs\n", __func__);
243 return (ENOBUFS);
244 }
245 pktlen = arphdr_len2(ETHER_ADDR_LEN, sizeof(struct in_addr));
246 m->m_len = pktlen;
247 m->m_pkthdr.len = pktlen;
248 MH_ALIGN(m, pktlen);
249 ah = mtod(m, struct arphdr *);
250 ah->ar_hrd = htons(ARPHRD_ETHER);
251 ah->ar_pro = htons(ETHERTYPE_IP);
252 ah->ar_hln = ETHER_ADDR_LEN;
253 ah->ar_pln = sizeof(struct in_addr);
254 ah->ar_op = htons(ARPOP_REQUEST);
255 memcpy(ar_sha(ah), IF_LLADDR(ifp), ETHER_ADDR_LEN);
256 ((struct in_addr *)ar_spa(ah))->s_addr = pcb->dp_client;
257 bzero(ar_tha(ah), ETHER_ADDR_LEN);
258 ((struct in_addr *)ar_tpa(ah))->s_addr = dst;
259 return (debugnet_ether_output(m, ifp, bcast, ETHERTYPE_ARP));
260 }
261
262 /*
263 * Handler for ARP packets: checks their sanity and then
264 * 1. If the ARP is a request for our IP, respond with our MAC address
265 * 2. If the ARP is a response from our server, record its MAC address
266 *
267 * It needs to replicate partially the behaviour of arpintr() and
268 * in_arpinput().
269 *
270 * Parameters:
271 * pcb a pointer to the live debugnet PCB
272 * mb a pointer to an mbuf * containing the packet received
273 * Updates *mb if m_pullup et al change the pointer
274 * Assumes the calling function will take care of freeing the mbuf
275 */
276 void
debugnet_handle_arp(struct debugnet_pcb * pcb,struct mbuf ** mb)277 debugnet_handle_arp(struct debugnet_pcb *pcb, struct mbuf **mb)
278 {
279 char buf[INET_ADDRSTRLEN];
280 struct in_addr isaddr, itaddr;
281 struct ether_addr dst;
282 struct mbuf *m;
283 struct arphdr *ah;
284 struct ifnet *ifp;
285 uint8_t *enaddr;
286 int req_len, op;
287
288 m = *mb;
289 ifp = m->m_pkthdr.rcvif;
290 if (m->m_len < sizeof(struct arphdr)) {
291 m = m_pullup(m, sizeof(struct arphdr));
292 *mb = m;
293 if (m == NULL) {
294 DNETDEBUG("runt packet: m_pullup failed\n");
295 return;
296 }
297 }
298
299 ah = mtod(m, struct arphdr *);
300 if (ntohs(ah->ar_hrd) != ARPHRD_ETHER) {
301 DNETDEBUG("unknown hardware address 0x%2D)\n",
302 (unsigned char *)&ah->ar_hrd, "");
303 return;
304 }
305 if (ntohs(ah->ar_pro) != ETHERTYPE_IP) {
306 DNETDEBUG("drop ARP for unknown protocol %d\n",
307 ntohs(ah->ar_pro));
308 return;
309 }
310 req_len = arphdr_len2(ifp->if_addrlen, sizeof(struct in_addr));
311 if (m->m_len < req_len) {
312 m = m_pullup(m, req_len);
313 *mb = m;
314 if (m == NULL) {
315 DNETDEBUG("runt packet: m_pullup failed\n");
316 return;
317 }
318 }
319 ah = mtod(m, struct arphdr *);
320
321 op = ntohs(ah->ar_op);
322 memcpy(&isaddr, ar_spa(ah), sizeof(isaddr));
323 memcpy(&itaddr, ar_tpa(ah), sizeof(itaddr));
324 enaddr = (uint8_t *)IF_LLADDR(ifp);
325
326 if (memcmp(ar_sha(ah), enaddr, ifp->if_addrlen) == 0) {
327 DNETDEBUG("ignoring ARP from myself\n");
328 return;
329 }
330
331 if (isaddr.s_addr == pcb->dp_client) {
332 printf("%s: %*D is using my IP address %s!\n", __func__,
333 ifp->if_addrlen, (u_char *)ar_sha(ah), ":",
334 inet_ntoa_r(isaddr, buf));
335 return;
336 }
337
338 if (memcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen) == 0) {
339 DNETDEBUG("ignoring ARP from broadcast address\n");
340 return;
341 }
342
343 if (op == ARPOP_REPLY) {
344 if (isaddr.s_addr != pcb->dp_gateway &&
345 isaddr.s_addr != pcb->dp_server) {
346 inet_ntoa_r(isaddr, buf);
347 DNETDEBUG("ignoring ARP reply from %s (not configured"
348 " server or gateway)\n", buf);
349 return;
350 }
351 if (pcb->dp_state >= DN_STATE_HAVE_GW_MAC) {
352 inet_ntoa_r(isaddr, buf);
353 DNETDEBUG("ignoring server ARP reply from %s (already"
354 " have gateway address)\n", buf);
355 return;
356 }
357 MPASS(pcb->dp_state == DN_STATE_INIT);
358 memcpy(pcb->dp_gw_mac.octet, ar_sha(ah),
359 min(ah->ar_hln, ETHER_ADDR_LEN));
360
361 DNETDEBUG("got server MAC address %6D\n",
362 pcb->dp_gw_mac.octet, ":");
363
364 pcb->dp_state = DN_STATE_HAVE_GW_MAC;
365 return;
366 }
367
368 if (op != ARPOP_REQUEST) {
369 DNETDEBUG("ignoring ARP non-request/reply\n");
370 return;
371 }
372
373 if (itaddr.s_addr != pcb->dp_client) {
374 DNETDEBUG("ignoring ARP not to our IP\n");
375 return;
376 }
377
378 memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
379 memcpy(ar_sha(ah), enaddr, ah->ar_hln);
380 memcpy(ar_tpa(ah), ar_spa(ah), ah->ar_pln);
381 memcpy(ar_spa(ah), &itaddr, ah->ar_pln);
382 ah->ar_op = htons(ARPOP_REPLY);
383 ah->ar_pro = htons(ETHERTYPE_IP);
384 m->m_flags &= ~(M_BCAST|M_MCAST);
385 m->m_len = arphdr_len(ah);
386 m->m_pkthdr.len = m->m_len;
387
388 memcpy(dst.octet, ar_tha(ah), ETHER_ADDR_LEN);
389 debugnet_ether_output(m, ifp, dst, ETHERTYPE_ARP);
390 *mb = NULL;
391 }
392
393 /*
394 * Sends ARP requests to locate the server and waits for a response.
395 * We first try to ARP the server itself, and fall back to the provided
396 * gateway if the server appears to be off-link.
397 *
398 * Return value:
399 * 0 on success
400 * errno on error
401 */
402 int
debugnet_arp_gw(struct debugnet_pcb * pcb)403 debugnet_arp_gw(struct debugnet_pcb *pcb)
404 {
405 in_addr_t dst;
406 int error, polls, retries;
407
408 dst = pcb->dp_server;
409 restart:
410 for (retries = 0; retries < debugnet_arp_nretries; retries++) {
411 error = debugnet_send_arp(pcb, dst);
412 if (error != 0)
413 return (error);
414 for (polls = 0; polls < debugnet_npolls &&
415 pcb->dp_state < DN_STATE_HAVE_GW_MAC; polls++) {
416 debugnet_network_poll(pcb);
417 DELAY(500);
418 }
419 if (pcb->dp_state >= DN_STATE_HAVE_GW_MAC)
420 break;
421 printf("(ARP retry)");
422 }
423 if (pcb->dp_state >= DN_STATE_HAVE_GW_MAC)
424 return (0);
425 if (dst == pcb->dp_server) {
426 printf("\nFailed to ARP server");
427 if (pcb->dp_gateway != INADDR_ANY) {
428 printf(", trying to reach gateway...\n");
429 dst = pcb->dp_gateway;
430 goto restart;
431 } else
432 printf(".\n");
433 } else
434 printf("\nFailed to ARP gateway.\n");
435
436 return (ETIMEDOUT);
437 }
438
439 /*
440 * Unreliable IPv4 transmission of an mbuf chain to the debugnet server
441 * Note: can't handle fragmentation; fails if the packet is larger than
442 * ifp->if_mtu after adding the UDP/IP headers
443 *
444 * Parameters:
445 * pcb The debugnet context block
446 * m mbuf chain
447 *
448 * Returns:
449 * int see errno.h, 0 for success
450 */
451 int
debugnet_ip_output(struct debugnet_pcb * pcb,struct mbuf * m)452 debugnet_ip_output(struct debugnet_pcb *pcb, struct mbuf *m)
453 {
454 struct udphdr *udp;
455 struct ifnet *ifp;
456 struct ip *ip;
457
458 MPASS(pcb->dp_state >= DN_STATE_HAVE_GW_MAC);
459
460 ifp = pcb->dp_ifp;
461
462 M_PREPEND(m, sizeof(*ip), M_NOWAIT);
463 if (m == NULL) {
464 printf("%s: out of mbufs\n", __func__);
465 return (ENOBUFS);
466 }
467
468 if (m->m_pkthdr.len > ifp->if_mtu) {
469 printf("%s: Packet is too big: %d > MTU %u\n", __func__,
470 m->m_pkthdr.len, ifp->if_mtu);
471 m_freem(m);
472 return (ENOBUFS);
473 }
474
475 ip = mtod(m, void *);
476 udp = (void *)(ip + 1);
477
478 memset(ip, 0, offsetof(struct ip, ip_p));
479 ip->ip_p = IPPROTO_UDP;
480 ip->ip_sum = udp->uh_ulen;
481 ip->ip_src = (struct in_addr) { pcb->dp_client };
482 ip->ip_dst = (struct in_addr) { pcb->dp_server };
483
484 /* Compute UDP-IPv4 checksum. */
485 udp->uh_sum = in_cksum(m, m->m_pkthdr.len);
486 if (udp->uh_sum == 0)
487 udp->uh_sum = 0xffff;
488
489 ip->ip_v = IPVERSION;
490 ip->ip_hl = sizeof(*ip) >> 2;
491 ip->ip_tos = 0;
492 ip->ip_len = htons(m->m_pkthdr.len);
493 ip->ip_id = 0;
494 ip->ip_off = htons(IP_DF);
495 ip->ip_ttl = 255;
496 ip->ip_sum = 0;
497 ip->ip_sum = in_cksum(m, sizeof(struct ip));
498
499 return (debugnet_ether_output(m, ifp, pcb->dp_gw_mac, ETHERTYPE_IP));
500 }
501