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iof-bird-daemon / proto / ospf / packet.c @ 6f8bbaa1

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1
/*
2
 *        BIRD -- OSPF
3
 *
4
 *        (c) 1999--2005 Ondrej Filip <feela@network.cz>
5
 *        (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>
6
 *        (c) 2009--2014 CZ.NIC z.s.p.o.
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 *
8
 *        Can be freely distributed and used under the terms of the GNU GPL.
9
 */
10

    
11
#include "ospf.h"
12
#include "nest/password.h"
13
#include "lib/md5.h"
14

    
15
void
16
ospf_pkt_fill_hdr(struct ospf_iface *ifa, void *buf, u8 h_type)
17
{
18
  struct ospf_proto *p = ifa->oa->po;
19
  struct ospf_packet *pkt;
20

    
21
  pkt = (struct ospf_packet *) buf;
22

    
23
  pkt->version = ospf_get_version(p);
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  pkt->type = h_type;
25
  pkt->length = htons(ospf_pkt_maxsize(ifa));
26
  pkt->routerid = htonl(p->router_id);
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  pkt->areaid = htonl(ifa->oa->areaid);
28
  pkt->checksum = 0;
29
  pkt->instance_id = ifa->instance_id;
30
  pkt->autype = ifa->autype;
31
}
32

    
33
uint
34
ospf_pkt_maxsize(struct ospf_iface *ifa)
35
{
36
  uint headers = SIZE_OF_IP_HEADER;
37

    
38
  /* Relevant just for OSPFv2 */
39
  if (ifa->autype == OSPF_AUTH_CRYPT)
40
    headers += OSPF_AUTH_CRYPT_SIZE;
41

    
42
  return ifa->tx_length - headers;
43
}
44

    
45
/* We assume OSPFv2 in ospf_pkt_finalize() */
46
static void
47
ospf_pkt_finalize(struct ospf_iface *ifa, struct ospf_packet *pkt)
48
{
49
  struct password_item *passwd = NULL;
50
  union ospf_auth *auth = (void *) (pkt + 1);
51
  uint plen = ntohs(pkt->length);
52

    
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  pkt->checksum = 0;
54
  pkt->autype = ifa->autype;
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  bzero(auth, sizeof(union ospf_auth));
56

    
57
  /* Compatibility note: auth may contain anything if autype is
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     none, but nonzero values do not work with Mikrotik OSPF */
59

    
60
  switch (ifa->autype)
61
  {
62
  case OSPF_AUTH_SIMPLE:
63
    passwd = password_find(ifa->passwords, 1);
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    if (!passwd)
65
    {
66
      log(L_ERR "No suitable password found for authentication");
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      return;
68
    }
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    strncpy(auth->password, passwd->password, sizeof(auth->password));
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  case OSPF_AUTH_NONE:
72
    {
73
      void *body = (void *) (auth + 1);
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      uint blen = plen - sizeof(struct ospf_packet) - sizeof(union ospf_auth);
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      pkt->checksum = ipsum_calculate(pkt, sizeof(struct ospf_packet), body, blen, NULL);
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    }
77
    break;
78

    
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  case OSPF_AUTH_CRYPT:
80
    passwd = password_find(ifa->passwords, 0);
81
    if (!passwd)
82
    {
83
      log(L_ERR "No suitable password found for authentication");
84
      return;
85
    }
86

    
87
    /* Perhaps use random value to prevent replay attacks after
88
       reboot when system does not have independent RTC? */
89
    if (!ifa->csn)
90
    {
91
      ifa->csn = (u32) now;
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      ifa->csn_use = now;
93
    }
94

    
95
    /* We must have sufficient delay between sending a packet and increasing
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       CSN to prevent reordering of packets (in a network) with different CSNs */
97
    if ((now - ifa->csn_use) > 1)
98
      ifa->csn++;
99

    
100
    ifa->csn_use = now;
101

    
102
    auth->md5.zero = 0;
103
    auth->md5.keyid = passwd->id;
104
    auth->md5.len = OSPF_AUTH_CRYPT_SIZE;
105
    auth->md5.csn = htonl(ifa->csn);
106

    
107
    void *tail = ((void *) pkt) + plen;
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    char password[OSPF_AUTH_CRYPT_SIZE];
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    strncpy(password, passwd->password, sizeof(password));
110

    
111
    struct MD5Context ctxt;
112
    MD5Init(&ctxt);
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    MD5Update(&ctxt, (char *) pkt, plen);
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    MD5Update(&ctxt, password, OSPF_AUTH_CRYPT_SIZE);
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    MD5Final(tail, &ctxt);
116
    break;
117

    
118
  default:
119
    bug("Unknown authentication type");
120
  }
121
}
122

    
123

    
124
/* We assume OSPFv2 in ospf_pkt_checkauth() */
125
static int
126
ospf_pkt_checkauth(struct ospf_neighbor *n, struct ospf_iface *ifa, struct ospf_packet *pkt, int len)
127
{
128
  struct ospf_proto *p = ifa->oa->po;
129
  union ospf_auth *auth = (void *) (pkt + 1);
130
  struct password_item *pass = NULL;
131
  const char *err_dsc = NULL;
132
  uint err_val = 0;
133

    
134
  uint plen = ntohs(pkt->length);
135
  u8 autype = pkt->autype;
136

    
137
  if (autype != ifa->autype)
138
    DROP("authentication method mismatch", autype);
139

    
140
  switch (autype)
141
  {
142
  case OSPF_AUTH_NONE:
143
    return 1;
144

    
145
  case OSPF_AUTH_SIMPLE:
146
    pass = password_find(ifa->passwords, 1);
147
    if (!pass)
148
      DROP1("no password found");
149

    
150
    if (!password_verify(pass, auth->password, sizeof(auth->password)))
151
      DROP("wrong password", pass->id);
152

    
153
    return 1;
154

    
155
  case OSPF_AUTH_CRYPT:
156
    if (auth->md5.len != OSPF_AUTH_CRYPT_SIZE)
157
      DROP("invalid MD5 digest length", auth->md5.len);
158

    
159
    if (plen + OSPF_AUTH_CRYPT_SIZE > len)
160
      DROP("length mismatch", len);
161

    
162
    u32 rcv_csn = ntohl(auth->md5.csn);
163
    if (n && (rcv_csn < n->csn))
164
      // DROP("lower sequence number", rcv_csn);
165
    {
166
      /* We want to report both new and old CSN */
167
      LOG_PKT_AUTH("Authentication failed for nbr %R on %s - "
168
                   "lower sequence number (rcv %u, old %u)",
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                   n->rid, ifa->ifname, rcv_csn, n->csn);
170
      return 0;
171
    }
172

    
173
    pass = password_find_by_id(ifa->passwords, auth->md5.keyid);
174
    if (!pass)
175
      DROP("no suitable password found", auth->md5.keyid);
176

    
177
    void *tail = ((void *) pkt) + plen;
178
    char passwd[OSPF_AUTH_CRYPT_SIZE];
179
    char md5sum[OSPF_AUTH_CRYPT_SIZE];
180

    
181
    strncpy(passwd, pass->password, OSPF_AUTH_CRYPT_SIZE);
182

    
183
    struct MD5Context ctxt;
184
    MD5Init(&ctxt);
185
    MD5Update(&ctxt, (char *) pkt, plen);
186
    MD5Update(&ctxt, passwd, OSPF_AUTH_CRYPT_SIZE);
187
    MD5Final(md5sum, &ctxt);
188

    
189
    if (memcmp(md5sum, tail, OSPF_AUTH_CRYPT_SIZE))
190
      DROP("wrong MD5 digest", pass->id);
191

    
192
    if (n)
193
      n->csn = rcv_csn;
194

    
195
    return 1;
196

    
197
  default:
198
    bug("Unknown authentication type");
199
  }
200

    
201
drop:
202
  LOG_PKT_AUTH("Authentication failed for nbr %R on %s - %s (%u)",
203
               (n ? n->rid : ntohl(pkt->routerid)), ifa->ifname, err_dsc, err_val);
204

    
205
  return 0;
206
}
207

    
208
/**
209
 * ospf_rx_hook
210
 * @sk: socket we received the packet.
211
 * @size: size of the packet
212
 *
213
 * This is the entry point for messages from neighbors. Many checks (like
214
 * authentication, checksums, size) are done before the packet is passed to
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 * non generic functions.
216
 */
217
int
218
ospf_rx_hook(sock *sk, int len)
219
{
220
  /* We want just packets from sk->iface. Unfortunately, on BSD we cannot filter
221
     out other packets at kernel level and we receive all packets on all sockets */
222
  if (sk->lifindex != sk->iface->index)
223
    return 1;
224

    
225
  DBG("OSPF: RX hook called (iface %s, src %I, dst %I)\n",
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      sk->ifname, sk->faddr, sk->laddr);
227

    
228
  /* Initially, the packet is associated with the 'master' iface */
229
  struct ospf_iface *ifa = sk->data;
230
  struct ospf_proto *p = ifa->oa->po;
231
  const char *err_dsc = NULL;
232
  uint err_val = 0;
233

    
234
  int src_local, dst_local, dst_mcast;
235
  src_local = ipa_in_net(sk->faddr, ifa->addr->prefix, ifa->addr->pxlen);
236
  dst_local = ipa_equal(sk->laddr, ifa->addr->ip);
237
  dst_mcast = ipa_equal(sk->laddr, ifa->all_routers) || ipa_equal(sk->laddr, ifa->des_routers);
238

    
239
  if (ospf_is_v2(p))
240
  {
241
    /* First, we eliminate packets with strange address combinations.
242
     * In OSPFv2, they might be for other ospf_ifaces (with different IP
243
     * prefix) on the same real iface, so we don't log it. We enforce
244
     * that (src_local || dst_local), therefore we are eliminating all
245
     * such cases.
246
     */
247
    if (dst_mcast && !src_local)
248
      return 1;
249
    if (!dst_mcast && !dst_local)
250
      return 1;
251

    
252
    /* Ignore my own broadcast packets */
253
    if (ifa->cf->real_bcast && ipa_equal(sk->faddr, ifa->addr->ip))
254
      return 1;
255
  }
256
  else
257
  {
258
    /* In OSPFv3, src_local and dst_local mean link-local.
259
     * RFC 5340 says that local (non-vlink) packets use
260
     * link-local src address, but does not enforce it. Strange.
261
     */
262
    if (dst_mcast && !src_local)
263
      LOG_PKT_WARN("Multicast packet received from non-link-local %I via %s",
264
                   sk->faddr, ifa->ifname);
265
  }
266

    
267
  /* Second, we check packet length, checksum, and the protocol version */
268
  struct ospf_packet *pkt = (void *) sk_rx_buffer(sk, &len);
269

    
270

    
271
  if (pkt == NULL)
272
    DROP("bad IP header", len);
273

    
274
  if (ifa->check_ttl && (sk->rcv_ttl < 255))
275
    DROP("wrong TTL", sk->rcv_ttl);
276

    
277
  if (len < sizeof(struct ospf_packet))
278
    DROP("too short", len);
279

    
280
  if (pkt->version != ospf_get_version(p))
281
    DROP("version mismatch", pkt->version);
282

    
283
  uint plen = ntohs(pkt->length);
284
  if ((plen < sizeof(struct ospf_packet)) || ((plen % 4) != 0))
285
    DROP("invalid length", plen);
286

    
287
  if (sk->flags & SKF_TRUNCATED)
288
  {
289
    /* If we have dynamic buffers and received truncated message, we expand RX buffer */
290

    
291
    uint bs = plen + 256;
292
    bs = BIRD_ALIGN(bs, 1024);
293

    
294
    if (!ifa->cf->rx_buffer && (bs > sk->rbsize))
295
      sk_set_rbsize(sk, bs);
296

    
297
    DROP("truncated", plen);
298
  }
299

    
300
  if (plen > len)
301
    DROP("length mismatch", plen);
302

    
303
  if (ospf_is_v2(p) && (pkt->autype != OSPF_AUTH_CRYPT))
304
  {
305
    uint hlen = sizeof(struct ospf_packet) + sizeof(union ospf_auth);
306
    uint blen = plen - hlen;
307
    void *body = ((void *) pkt) + hlen;
308

    
309
    if (!ipsum_verify(pkt, sizeof(struct ospf_packet), body, blen, NULL))
310
      DROP1("invalid checksum");
311
  }
312

    
313
  /* Third, we resolve associated iface and handle vlinks. */
314

    
315
  u32 areaid = ntohl(pkt->areaid);
316
  u32 rid = ntohl(pkt->routerid);
317
  u8 instance_id = pkt->instance_id;
318

    
319
  if (areaid == ifa->oa->areaid)
320
  {
321
    /* Matching area ID */
322

    
323
    if (instance_id != ifa->instance_id)
324
      return 1;
325

    
326
    /* It is real iface, source should be local (in OSPFv2) */
327
    if (ospf_is_v2(p) && !src_local)
328
      DROP1("strange source address");
329

    
330
    goto found;
331
  }
332
  else if ((areaid == 0) && !dst_mcast)
333
  {
334
    /* Backbone area ID and possible vlink packet */
335

    
336
    if ((p->areano == 1) || !oa_is_ext(ifa->oa))
337
      return 1;
338

    
339
    struct ospf_iface *iff = NULL;
340
    WALK_LIST(iff, p->iface_list)
341
    {
342
      if ((iff->type == OSPF_IT_VLINK) &&
343
          (iff->voa == ifa->oa) &&
344
          (iff->instance_id == instance_id) &&
345
          (iff->vid == rid))
346
      {
347
        /* Vlink should be UP */
348
        if (iff->state != OSPF_IS_PTP)
349
          return 1;
350

    
351
        ifa = iff;
352
        goto found;
353
      }
354
    }
355

    
356
    /*
357
     * Cannot find matching vlink. It is either misconfigured vlink; NBMA or
358
     * PtMP with misconfigured area ID, or packet for some other instance (that
359
     * is possible even if instance_id == ifa->instance_id, because it may be
360
     * also vlink packet in the other instance, which is different namespace).
361
     */
362

    
363
    return 1;
364
  }
365
  else
366
  {
367
    /* Non-matching area ID but cannot be vlink packet */
368

    
369
    if (instance_id != ifa->instance_id)
370
      return 1;
371

    
372
    DROP("area mismatch", areaid);
373
  }
374

    
375

    
376
found:
377
  if (ifa->stub)            /* This shouldn't happen */
378
    return 1;
379

    
380
  if (ipa_equal(sk->laddr, ifa->des_routers) && (ifa->sk_dr == 0))
381
    return 1;
382

    
383
  if (rid == p->router_id)
384
    DROP1("my own router ID");
385

    
386
  if (rid == 0)
387
    DROP1("zero router ID");
388

    
389
  /* In OSPFv2, neighbors are identified by either IP or Router ID, based on network type */
390
  uint t = ifa->type;
391
  struct ospf_neighbor *n;
392
  if (ospf_is_v2(p) && ((t == OSPF_IT_BCAST) || (t == OSPF_IT_NBMA) || (t == OSPF_IT_PTMP)))
393
    n = find_neigh_by_ip(ifa, sk->faddr);
394
  else
395
    n = find_neigh(ifa, rid);
396

    
397
  if (!n && (pkt->type != HELLO_P))
398
  {
399
    OSPF_TRACE(D_PACKETS, "Non-HELLO packet received from unknown nbr %R on %s, src %I",
400
               rid, ifa->ifname, sk->faddr);
401
    return 1;
402
  }
403

    
404
  /* ospf_pkt_checkauth() has its own error logging */
405
  if (ospf_is_v2(p) && !ospf_pkt_checkauth(n, ifa, pkt, len))
406
    return 1;
407

    
408
  switch (pkt->type)
409
  {
410
  case HELLO_P:
411
    ospf_receive_hello(pkt, ifa, n, sk->faddr);
412
    break;
413

    
414
  case DBDES_P:
415
    ospf_receive_dbdes(pkt, ifa, n);
416
    break;
417

    
418
  case LSREQ_P:
419
    ospf_receive_lsreq(pkt, ifa, n);
420
    break;
421

    
422
  case LSUPD_P:
423
    ospf_receive_lsupd(pkt, ifa, n);
424
    break;
425

    
426
  case LSACK_P:
427
    ospf_receive_lsack(pkt, ifa, n);
428
    break;
429

    
430
  default:
431
    DROP("invalid packet type", pkt->type);
432
  };
433
  return 1;
434

    
435
drop:
436
  LOG_PKT("Bad packet from %I via %s - %s (%u)",
437
          sk->faddr, ifa->ifname, err_dsc, err_val);
438

    
439
  return 1;
440
}
441

    
442
/*
443
void
444
ospf_tx_hook(sock * sk)
445
{
446
  struct ospf_iface *ifa= (struct ospf_iface *) (sk->data);
447
//  struct proto *p = (struct proto *) (ifa->oa->p);
448
  log(L_ERR "OSPF: TX hook called on %s", ifa->ifname);
449
}
450
*/
451

    
452
void
453
ospf_err_hook(sock * sk, int err)
454
{
455
  struct ospf_iface *ifa= (struct ospf_iface *) (sk->data);
456
  struct ospf_proto *p = ifa->oa->po;
457
  log(L_ERR "%s: Socket error on %s: %M", p->p.name, ifa->ifname, err);
458
}
459

    
460
void
461
ospf_verr_hook(sock *sk, int err)
462
{
463
  struct ospf_proto *p = (struct ospf_proto *) (sk->data);
464
  log(L_ERR "%s: Vlink socket error: %M", p->p.name, err);
465
}
466

    
467
void
468
ospf_send_to(struct ospf_iface *ifa, ip_addr dst)
469
{
470
  sock *sk = ifa->sk;
471
  struct ospf_packet *pkt = (struct ospf_packet *) sk->tbuf;
472
  int plen = ntohs(pkt->length);
473

    
474
  if (ospf_is_v2(ifa->oa->po))
475
  {
476
    if (ifa->autype == OSPF_AUTH_CRYPT)
477
      plen += OSPF_AUTH_CRYPT_SIZE;
478

    
479
    ospf_pkt_finalize(ifa, pkt);
480
  }
481

    
482
  int done = sk_send_to(sk, plen, dst, 0);
483
  if (!done)
484
    log(L_WARN "OSPF: TX queue full on %s", ifa->ifname);
485
}
486

    
487
void
488
ospf_send_to_agt(struct ospf_iface *ifa, u8 state)
489
{
490
  struct ospf_neighbor *n;
491

    
492
  WALK_LIST(n, ifa->neigh_list)
493
    if (n->state >= state)
494
      ospf_send_to(ifa, n->ip);
495
}
496

    
497
void
498
ospf_send_to_bdr(struct ospf_iface *ifa)
499
{
500
  if (ipa_nonzero(ifa->drip))
501
    ospf_send_to(ifa, ifa->drip);
502
  if (ipa_nonzero(ifa->bdrip))
503
    ospf_send_to(ifa, ifa->bdrip);
504
}