userapps/opensource/net-snmp/snmplib/snmpksm.c

   1 /*
   2  * snmpksm.c
   3  *
   4  * This code implements the Kerberos Security Model (KSM) for SNMP.
   5  *
   6  * Security number - 2066432
   7  */
   8
   9 #include <net-snmp/net-snmp-config.h>
  10
  11 #include <sys/types.h>
  12 #if HAVE_WINSOCK_H
  13 #include <winsock.h>
  14 #endif
  15 #include <stdio.h>
  16 #ifdef HAVE_STDLIB_H
  17 #include <stdlib.h>
  18 #endif
  19 #if TIME_WITH_SYS_TIME
  20 # ifdef WIN32
  21 #  include <sys/timeb.h>
  22 # else
  23 #  include <sys/time.h>
  24 # endif
  25 # include <time.h>
  26 #else
  27 # if HAVE_SYS_TIME_H
  28 #  include <sys/time.h>
  29 # else
  30 #  include <time.h>
  31 # endif
  32 #endif
  33 #if HAVE_STRING_H
  34 #include <string.h>
  35 #else
  36 #include <strings.h>
  37 #endif
  38 #ifdef HAVE_NETINET_IN_H
  39 #include <netinet/in.h>
  40 #endif
  41 #include <errno.h>
  42
  43
  44 #if HAVE_DMALLOC_H
  45 #include <dmalloc.h>
  46 #endif
  47
  48 #include <krb5.h>
  49 #include <com_err.h>
  50
  51 #include <net-snmp/output_api.h>
  52 #include <net-snmp/config_api.h>
  53 #include <net-snmp/utilities.h>
  54
  55 #include <net-snmp/library/asn1.h>
  56 #include <net-snmp/library/snmp_api.h>
  57 #include <net-snmp/library/callback.h>
  58 #include <net-snmp/library/keytools.h>
  59 #include <net-snmp/library/snmpv3.h>
  60 #include <net-snmp/library/lcd_time.h>
  61 #include <net-snmp/library/scapi.h>
  62 #include <net-snmp/library/callback.h>
  63 #include <net-snmp/library/snmp_secmod.h>
  64 #include <net-snmp/library/snmpksm.h>
  65
  66 static krb5_context kcontext = NULL;
  67 static krb5_rcache rcache = NULL;
  68
  69 static int      ksm_session_init(netsnmp_session *);
  70 static void     ksm_free_state_ref(void *);
  71 static int      ksm_free_pdu(netsnmp_pdu *);
  72 static int      ksm_clone_pdu(netsnmp_pdu *, netsnmp_pdu *);
  73
  74 static int      ksm_insert_cache(long, krb5_auth_context, u_char *,
  75                                  size_t);
  76 static void     ksm_decrement_ref_count(long);
  77 static void     ksm_increment_ref_count(long);
  78 static struct ksm_cache_entry *ksm_get_cache(long);
  79
  80 #define HASHSIZE        64
  81
  82 /*
  83  * Our information stored for the response PDU.
  84  */
  85
  86 struct ksm_secStateRef {
  87     krb5_auth_context auth_context;
  88     krb5_cksumtype  cksumtype;
  89 };
  90
  91 /*
  92  * A KSM outgoing pdu cache entry
  93  */
  94
  95 struct ksm_cache_entry {
  96     long            msgid;
  97     int             refcount;
  98     krb5_auth_context auth_context;
  99     u_char         *secName;
 100     size_t          secNameLen;
 101     struct ksm_cache_entry *next;
 102 };
 103
 104 /*
 105  * Poor man's hash table
 106  */
 107
 108 static struct ksm_cache_entry *ksm_hash_table[HASHSIZE];
 109
 110 /*
 111  * Initialize all of the state required for Kerberos (right now, just call
 112  * krb5_init_context).
 113  */
 114
 115 void
 116 init_ksm(void)
 117 {
 118     krb5_error_code retval;
 119     struct snmp_secmod_def *def;
 120     int             i;
 121
 122     if (kcontext == NULL) {
 123         retval = krb5_init_context(&kcontext);
 124
 125         if (retval) {
 126             DEBUGMSGTL(("ksm", "krb5_init_context failed (%s), not "
 127                         "registering KSM\n", error_message(retval)));
 128             return;
 129         }
 130     }
 131
 132     for (i = 0; i < HASHSIZE; i++)
 133         ksm_hash_table[i] = NULL;
 134
 135     def = SNMP_MALLOC_STRUCT(snmp_secmod_def);
 136
 137     if (!def) {
 138         DEBUGMSGTL(("ksm", "Unable to malloc snmp_secmod struct, not "
 139                     "registering KSM\n"));
 140         return;
 141     }
 142
 143     def->encode_reverse = ksm_rgenerate_out_msg;
 144     def->decode = ksm_process_in_msg;
 145     def->session_open = ksm_session_init;
 146     def->pdu_free_state_ref = ksm_free_state_ref;
 147     def->pdu_free = ksm_free_pdu;
 148     def->pdu_clone = ksm_clone_pdu;
 149
 150     register_sec_mod(2066432, "ksm", def);
 151 }
 152
 153 /*
 154  * These routines implement a simple cache for information we need to
 155  * process responses.  When we send out a request, it contains an AP_REQ;
 156  * we get back an AP_REP, and we need the authorization context from the
 157  * AP_REQ to decrypt the AP_REP.  But because right now there's nothing
 158  * that gets preserved across calls to rgenerate_out_msg to process_in_msg,
 159  * we cache these internally based on the message ID (we also cache the
 160  * passed-in security name, for reasons that are mostly stupid).
 161  */
 162
 163 static int
 164 ksm_insert_cache(long msgid, krb5_auth_context auth_context,
 165                  u_char * secName, size_t secNameLen)
 166 {
 167     struct ksm_cache_entry *entry;
 168     int             bucket;
 169     int             retval;
 170
 171     entry = SNMP_MALLOC_STRUCT(ksm_cache_entry);
 172
 173     if (!entry)
 174         return SNMPERR_MALLOC;
 175
 176     entry->msgid = msgid;
 177     entry->auth_context = auth_context;
 178     entry->refcount = 1;
 179
 180     retval = memdup(&entry->secName, secName, secNameLen);
 181
 182     if (retval != SNMPERR_SUCCESS) {
 183         free(entry);
 184         return retval;
 185     }
 186
 187     entry->secNameLen = secNameLen;
 188
 189     bucket = msgid % HASHSIZE;
 190
 191     entry->next = ksm_hash_table[bucket];
 192     ksm_hash_table[bucket] = entry;
 193
 194     return SNMPERR_SUCCESS;
 195 }
 196
 197 static struct ksm_cache_entry *
 198 ksm_get_cache(long msgid)
 199 {
 200     struct ksm_cache_entry *entry;
 201     int             bucket;
 202
 203     bucket = msgid % HASHSIZE;
 204
 205     for (entry = ksm_hash_table[bucket]; entry != NULL;
 206          entry = entry->next)
 207         if (entry->msgid == msgid)
 208             return entry;
 209
 210     return NULL;
 211 }
 212
 213 static void
 214 ksm_decrement_ref_count(long msgid)
 215 {
 216     struct ksm_cache_entry *entry, *entry1;
 217     int             bucket;
 218
 219     bucket = msgid % HASHSIZE;
 220
 221     if (ksm_hash_table[bucket] && ksm_hash_table[bucket]->msgid == msgid) {
 222         entry = ksm_hash_table[bucket];
 223
 224         /*
 225          * If the reference count is zero, then free it
 226          */
 227
 228         if (--entry->refcount <= 0) {
 229             DEBUGMSGTL(("ksm", "Freeing entry for msgid %ld\n", msgid));
 230             krb5_auth_con_free(kcontext, entry->auth_context);
 231             free(entry->secName);
 232             ksm_hash_table[bucket] = entry->next;
 233             free(entry);
 234         }
 235
 236         return;
 237
 238     } else if (ksm_hash_table[bucket])
 239         for (entry1 = ksm_hash_table[bucket], entry = entry1->next;
 240              entry != NULL; entry1 = entry, entry = entry->next)
 241             if (entry->msgid == msgid) {
 242
 243                 if (--entry->refcount <= 0) {
 244                     DEBUGMSGTL(("ksm", "Freeing entry for msgid %ld\n",
 245                                 msgid));
 246                     krb5_auth_con_free(kcontext, entry->auth_context);
 247                     free(entry->secName);
 248                     entry1->next = entry->next;
 249                     free(entry);
 250                 }
 251
 252                 return;
 253             }
 254
 255     DEBUGMSGTL(("ksm",
 256                 "KSM: Unable to decrement cache entry for msgid %ld.\n",
 257                 msgid));
 258 }
 259
 260 static void
 261 ksm_increment_ref_count(long msgid)
 262 {
 263     struct ksm_cache_entry *entry = ksm_get_cache(msgid);
 264
 265     if (!entry) {
 266         DEBUGMSGTL(("ksm", "Unable to find cache entry for msgid %ld "
 267                     "for increment\n", msgid));
 268         return;
 269     }
 270
 271     entry->refcount++;
 272 }
 273
 274 /*
 275  * Initialize specific session information (right now, just set up things to
 276  * not do an engineID probe)
 277  */
 278
 279 static int
 280 ksm_session_init(netsnmp_session * sess)
 281 {
 282     DEBUGMSGTL(("ksm",
 283                 "KSM: Reached our session initialization callback\n"));
 284
 285     sess->flags |= SNMP_FLAGS_DONT_PROBE;
 286
 287     return SNMPERR_SUCCESS;
 288 }
 289
 290 /*
 291  * Free our state information (this is only done on the agent side)
 292  */
 293
 294 static void
 295 ksm_free_state_ref(void *ptr)
 296 {
 297     struct ksm_secStateRef *ref = (struct ksm_secStateRef *) ptr;
 298
 299     DEBUGMSGTL(("ksm", "KSM: Freeing state reference\n"));
 300
 301     krb5_auth_con_free(kcontext, ref->auth_context);
 302
 303     free(ref);
 304 }
 305
 306 /*
 307  * This is called when the PDU is freed; this will decrement reference counts
 308  * for entries in our state cache.
 309  */
 310
 311 static int
 312 ksm_free_pdu(netsnmp_pdu *pdu)
 313 {
 314     ksm_decrement_ref_count(pdu->msgid);
 315
 316     DEBUGMSGTL(("ksm", "Decrementing cache entry for PDU msgid %ld\n",
 317                 pdu->msgid));
 318
 319     return SNMPERR_SUCCESS;
 320 }
 321
 322 /*
 323  * This is called when a PDU is cloned (to increase reference counts)
 324  */
 325
 326 static int
 327 ksm_clone_pdu(netsnmp_pdu *pdu, netsnmp_pdu *pdu2)
 328 {
 329     ksm_increment_ref_count(pdu->msgid);
 330
 331     DEBUGMSGTL(("ksm", "Incrementing cache entry for PDU msgid %ld\n",
 332                 pdu->msgid));
 333
 334     return SNMPERR_SUCCESS;
 335 }
 336
 337 /****************************************************************************
 338  *
 339  * ksm_generate_out_msg
 340  *
 341  * Parameters:
 342  *      (See list below...)
 343  *
 344  * Returns:
 345  *      SNMPERR_GENERIC                        On success.
 346  *      SNMPERR_KRB5
 347  *      ... and others
 348  *
 349  *
 350  * Generate an outgoing message.
 351  *
 352  ****************************************************************************/
 353
 354 int
 355 ksm_rgenerate_out_msg(struct snmp_secmod_outgoing_params *parms)
 356 {
 357     krb5_auth_context auth_context = NULL;
 358     krb5_error_code retcode;
 359     krb5_ccache     cc = NULL;
 360     int             retval = SNMPERR_SUCCESS;
 361     krb5_data       outdata, ivector;
 362     krb5_keyblock  *subkey = NULL;
 363 #ifdef MIT_NEW_CRYPTO
 364     krb5_data       input;
 365     krb5_enc_data   output;
 366 #else                           /* MIT_NEW_CRYPTO */
 367     krb5_encrypt_block eblock;
 368 #endif                          /* MIT_NEW_CRYPTO */
 369     size_t          blocksize, encrypted_length;
 370     unsigned char  *encrypted_data = NULL;
 371     int             zero = 0, i;
 372     u_char         *cksum_pointer, *endp = *parms->wholeMsg;
 373     krb5_cksumtype  cksumtype = CKSUMTYPE_RSA_MD5_DES;
 374     krb5_checksum   pdu_checksum;
 375     u_char         **wholeMsg = parms->wholeMsg;
 376     size_t         *offset = parms->wholeMsgOffset, seq_offset;
 377     struct ksm_secStateRef *ksm_state = (struct ksm_secStateRef *)
 378         parms->secStateRef;
 379     int rc;
 380
 381     DEBUGMSGTL(("ksm", "Starting KSM processing\n"));
 382
 383     outdata.length = 0;
 384     outdata.data = NULL;
 385     ivector.length = 0;
 386     ivector.data = NULL;
 387     pdu_checksum.contents = NULL;
 388
 389     if (!ksm_state) {
 390         /*
 391          * If we don't have a ksm_state, then we're a request.  Get a
 392          * credential cache and build a ap_req.
 393          */
 394         retcode = krb5_cc_default(kcontext, &cc);
 395
 396         if (retcode) {
 397             DEBUGMSGTL(("ksm", "KSM: krb5_cc_default failed: %s\n",
 398                         error_message(retcode)));
 399             snmp_set_detail(error_message(retcode));
 400             retval = SNMPERR_KRB5;
 401             goto error;
 402         }
 403
 404         DEBUGMSGTL(("ksm", "KSM: Set credential cache successfully\n"));
 405
 406         /*
 407          * This seems odd, since we don't need this until later (or earlier,
 408          * depending on how you look at it), but because the most likely
 409          * errors are Kerberos at this point, I'll get this now to save
 410          * time not encoding the rest of the packet.
 411          *
 412          * Also, we need the subkey to encrypt the PDU (if required).
 413          */
 414
 415         retcode =
 416             krb5_mk_req(kcontext, &auth_context,
 417                         AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
 418                         (char *) "host", parms->session->peername, NULL,
 419                         cc, &outdata);
 420
 421         if (retcode) {
 422             DEBUGMSGTL(("ksm", "KSM: krb5_mk_req failed: %s\n",
 423                         error_message(retcode)));
 424             snmp_set_detail(error_message(retcode));
 425             retval = SNMPERR_KRB5;
 426             goto error;
 427         }
 428
 429         DEBUGMSGTL(("ksm", "KSM: ticket retrieved successfully\n"));
 430
 431     } else {
 432
 433         /*
 434          * Grab the auth_context from our security state reference
 435          */
 436
 437         auth_context = ksm_state->auth_context;
 438
 439         /*
 440          * Bundle up an AP_REP.  Note that we do this only when we
 441          * have a security state reference (which means we're in an agent
 442          * and we're sending a response).
 443          */
 444
 445         DEBUGMSGTL(("ksm", "KSM: Starting reply processing.\n"));
 446
 447         retcode = krb5_mk_rep(kcontext, auth_context, &outdata);
 448
 449         if (retcode) {
 450             DEBUGMSGTL(("ksm", "KSM: krb5_mk_rep failed: %s\n",
 451                         error_message(retcode)));
 452             snmp_set_detail(error_message(retcode));
 453             retval = SNMPERR_KRB5;
 454             goto error;
 455         }
 456
 457         DEBUGMSGTL(("ksm", "KSM: Finished with krb5_mk_rep()\n"));
 458     }
 459
 460     /*
 461      * If we have to encrypt the PDU, do that now
 462      */
 463
 464     if (parms->secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
 465
 466         DEBUGMSGTL(("ksm", "KSM: Starting PDU encryption.\n"));
 467
 468         /*
 469          * It's weird -
 470          *
 471          * If we're on the manager, it's a local subkey (because that's in
 472          * our AP_REQ)
 473          *
 474          * If we're on the agent, it's a remote subkey (because that comes
 475          * FROM the received AP_REQ).
 476          */
 477
 478         if (ksm_state)
 479             retcode = krb5_auth_con_getremotesubkey(kcontext, auth_context,
 480                                                     &subkey);
 481         else
 482             retcode = krb5_auth_con_getlocalsubkey(kcontext, auth_context,
 483                                                    &subkey);
 484
 485         if (retcode) {
 486             DEBUGMSGTL(("ksm",
 487                         "KSM: krb5_auth_con_getlocalsubkey failed: %s\n",
 488                         error_message(retcode)));
 489             snmp_set_detail(error_message(retcode));
 490             retval = SNMPERR_KRB5;
 491             goto error;
 492         }
 493
 494         /*
 495          * Note that here we need to handle different things between the
 496          * old and new crypto APIs.  First, we need to get the final encrypted
 497          * length of the PDU.
 498          */
 499
 500 #ifdef MIT_NEW_CRYPTO
 501         retcode = krb5_c_encrypt_length(kcontext, subkey->enctype,
 502                                         parms->scopedPduLen,
 503                                         &encrypted_length);
 504
 505         if (retcode) {
 506             DEBUGMSGTL(("ksm",
 507                         "Encryption length calculation failed: %s\n",
 508                         error_message(retcode)));
 509             snmp_set_detail(error_message(retcode));
 510             retval = SNMPERR_KRB5;
 511             goto error;
 512         }
 513 #else                           /* MIT_NEW_CRYPTO */
 514
 515         krb5_use_enctype(kcontext, &eblock, subkey->enctype);
 516         retcode = krb5_process_key(kcontext, &eblock, subkey);
 517
 518         if (retcode) {
 519             DEBUGMSGTL(("ksm", "krb5_process_key failed: %s\n",
 520                         error_message(retcode)));
 521             snmp_set_detail(error_message(retcode));
 522             retval = SNMPERR_KRB5;
 523             goto error;
 524         }
 525
 526         encrypted_length = krb5_encrypt_size(parms->scopedPduLen,
 527                                              eblock.crypto_entry);
 528 #endif                          /* MIT_NEW_CRYPTO */
 529
 530         encrypted_data = malloc(encrypted_length);
 531
 532         if (!encrypted_data) {
 533             DEBUGMSGTL(("ksm",
 534                         "KSM: Unable to malloc %d bytes for encrypt "
 535                         "buffer: %s\n", parms->scopedPduLen,
 536                         strerror(errno)));
 537             retval = SNMPERR_MALLOC;
 538 #ifndef MIT_NEW_CRYPTO
 539             krb5_finish_key(kcontext, &eblock);
 540 #endif                          /* ! MIT_NEW_CRYPTO */
 541
 542             goto error;
 543         }
 544
 545         /*
 546          * We need to set up a blank initialization vector for the encryption.
 547          * Use a block of all zero's (which is dependent on the block size
 548          * of the encryption method).
 549          */
 550
 551 #ifdef MIT_NEW_CRYPTO
 552
 553         retcode = krb5_c_block_size(kcontext, subkey->enctype, &blocksize);
 554
 555         if (retcode) {
 556             DEBUGMSGTL(("ksm",
 557                         "Unable to determine crypto block size: %s\n",
 558                         error_message(retcode)));
 559             snmp_set_detail(error_message(retcode));
 560             retval = SNMPERR_KRB5;
 561             goto error;
 562         }
 563 #else                           /* MIT_NEW_CRYPTO */
 564
 565         blocksize =
 566             krb5_enctype_array[subkey->enctype]->system->block_length;
 567
 568 #endif                          /* MIT_NEW_CRYPTO */
 569
 570         ivector.data = malloc(blocksize);
 571
 572         if (!ivector.data) {
 573             DEBUGMSGTL(("ksm", "Unable to allocate %d bytes for ivector\n",
 574                         blocksize));
 575             retval = SNMPERR_MALLOC;
 576             goto error;
 577         }
 578
 579         ivector.length = blocksize;
 580         memset(ivector.data, 0, blocksize);
 581
 582         /*
 583          * Finally!  Do the encryption!
 584          */
 585
 586 #ifdef MIT_NEW_CRYPTO
 587
 588         input.data = (char *) parms->scopedPdu;
 589         input.length = parms->scopedPduLen;
 590         output.ciphertext.data = (char *) encrypted_data;
 591         output.ciphertext.length = encrypted_length;
 592
 593         retcode =
 594             krb5_c_encrypt(kcontext, subkey, KSM_KEY_USAGE_ENCRYPTION,
 595                            &ivector, &input, &output);
 596
 597 #else                           /* MIT_NEW_CRYPTO */
 598
 599         retcode = krb5_encrypt(kcontext, (krb5_pointer) parms->scopedPdu,
 600                                (krb5_pointer) encrypted_data,
 601                                parms->scopedPduLen, &eblock, ivector.data);
 602
 603         krb5_finish_key(kcontext, &eblock);
 604
 605 #endif                          /* MIT_NEW_CRYPTO */
 606
 607         if (retcode) {
 608             DEBUGMSGTL(("ksm", "KSM: krb5_encrypt failed: %s\n",
 609                         error_message(retcode)));
 610             retval = SNMPERR_KRB5;
 611             snmp_set_detail(error_message(retcode));
 612             goto error;
 613         }
 614
 615         *offset = 0;
 616
 617         rc = asn_realloc_rbuild_string(wholeMsg, parms->wholeMsgLen,
 618                                              offset, 1,
 619                                              (u_char) (ASN_UNIVERSAL |
 620                                                        ASN_PRIMITIVE |
 621                                                        ASN_OCTET_STR),
 622                                              encrypted_data,
 623                                              encrypted_length);
 624
 625         if (rc == 0) {
 626             DEBUGMSGTL(("ksm", "Building encrypted payload failed.\n"));
 627             retval = SNMPERR_TOO_LONG;
 628             goto error;
 629         }
 630
 631         DEBUGMSGTL(("ksm", "KSM: Encryption complete.\n"));
 632
 633     } else {
 634         /*
 635          * Plaintext PDU (not encrypted)
 636          */
 637
 638         if (*parms->wholeMsgLen < parms->scopedPduLen) {
 639             DEBUGMSGTL(("ksm", "Not enough room for plaintext PDU.\n"));
 640             retval = SNMPERR_TOO_LONG;
 641             goto error;
 642         }
 643     }
 644
 645     /*
 646      * Start encoding the msgSecurityParameters
 647      *
 648      * For now, use 0 for the response hint
 649      */
 650
 651     DEBUGMSGTL(("ksm", "KSM: scopedPdu added to payload\n"));
 652
 653     seq_offset = *offset;
 654
 655     rc = asn_realloc_rbuild_int(wholeMsg, parms->wholeMsgLen,
 656                                       offset, 1,
 657                                       (u_char) (ASN_UNIVERSAL |
 658                                                 ASN_PRIMITIVE |
 659                                                 ASN_INTEGER),
 660                                       (long *) &zero, sizeof(zero));
 661
 662     if (rc == 0) {
 663         DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
 664         retval = SNMPERR_TOO_LONG;
 665         goto error;
 666     }
 667
 668     rc = asn_realloc_rbuild_string(wholeMsg, parms->wholeMsgLen,
 669                                          offset, 1,
 670                                          (u_char) (ASN_UNIVERSAL |
 671                                                    ASN_PRIMITIVE |
 672                                                    ASN_OCTET_STR),
 673                                          (u_char *) outdata.data,
 674                                          outdata.length);
 675
 676     if (rc == 0) {
 677         DEBUGMSGTL(("ksm", "Building ksm AP_REQ failed.\n"));
 678         retval = SNMPERR_TOO_LONG;
 679         goto error;
 680     }
 681
 682     /*
 683      * Hardcode checksum type FOR NOW! XXX (but make sure the response
 684      * checksum type is the same as the request).
 685      *
 686      * Not sure what we're supposed to do about checksum negotiation.
 687      */
 688
 689     if (ksm_state)
 690         cksumtype = ksm_state->cksumtype;
 691
 692     if (!is_keyed_cksum(cksumtype)) {
 693         DEBUGMSGTL(("ksm", "Checksum type %d is not a keyed checksum\n",
 694                     cksumtype));
 695         snmp_set_detail("Checksum is not a keyed checksum");
 696         retval = SNMPERR_KRB5;
 697         goto error;
 698     }
 699
 700     if (!is_coll_proof_cksum(cksumtype)) {
 701         DEBUGMSGTL(("ksm", "Checksum type %d is not a collision-proof "
 702                     "checksum\n", cksumtype));
 703         snmp_set_detail("Checksum is not a collision-proof checksum");
 704         retval = SNMPERR_KRB5;
 705         goto error;
 706     }
 707 #ifdef MIT_NEW_CRYPTO
 708     retcode = krb5_c_checksum_length(kcontext, cksumtype, &blocksize);
 709
 710     if (retcode) {
 711         DEBUGMSGTL(("ksm", "Unable to determine checksum length: %s\n",
 712                     error_message(retcode)));
 713         snmp_set_detail(error_message(retcode));
 714         retval = SNMPERR_KRB5;
 715         goto error;
 716     }
 717
 718     pdu_checksum.length = blocksize;
 719
 720 #else                           /* MIT_NEW_CRYPTO */
 721
 722     pdu_checksum.length = krb5_checksum_size(kcontext, cksumtype);
 723     pdu_checksum.checksum_type = cksumtype;
 724
 725 #endif                          /* MIT_NEW_CRYPTO */
 726
 727     /*
 728      * Note that here, we're just leaving blank space for the checksum;
 729      * we remember where that is, and we'll fill it in later.
 730      */
 731
 732     *offset += pdu_checksum.length;
 733     memset(*wholeMsg + *parms->wholeMsgLen - *offset, 0, pdu_checksum.length);
 734
 735     cksum_pointer = *wholeMsg + *parms->wholeMsgLen - *offset;
 736
 737     rc = asn_realloc_rbuild_header(wholeMsg, parms->wholeMsgLen,
 738                                          parms->wholeMsgOffset, 1,
 739                                          (u_char) (ASN_UNIVERSAL |
 740                                                    ASN_PRIMITIVE |
 741                                                    ASN_OCTET_STR),
 742                                          pdu_checksum.length);
 743
 744     if (rc == 0) {
 745         DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
 746         retval = SNMPERR_TOO_LONG;
 747         goto error;
 748     }
 749
 750     rc = asn_realloc_rbuild_int(wholeMsg, parms->wholeMsgLen,
 751                                       parms->wholeMsgOffset, 1,
 752                                       (u_char) (ASN_UNIVERSAL |
 753                                                 ASN_PRIMITIVE |
 754                                                 ASN_OCTET_STR),
 755                                       (long *) &cksumtype,
 756                                       sizeof(cksumtype));
 757
 758     if (rc == 0) {
 759         DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
 760         retval = SNMPERR_TOO_LONG;
 761         goto error;
 762     }
 763
 764     rc = asn_realloc_rbuild_sequence(wholeMsg, parms->wholeMsgLen,
 765                                            parms->wholeMsgOffset, 1,
 766                                            (u_char) (ASN_SEQUENCE |
 767                                                      ASN_CONSTRUCTOR),
 768                                            *offset - seq_offset);
 769
 770     if (rc == 0) {
 771         DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
 772         retval = SNMPERR_TOO_LONG;
 773         goto error;
 774     }
 775
 776     rc = asn_realloc_rbuild_header(wholeMsg, parms->wholeMsgLen,
 777                                          parms->wholeMsgOffset, 1,
 778                                          (u_char) (ASN_UNIVERSAL |
 779                                                    ASN_PRIMITIVE |
 780                                                    ASN_OCTET_STR),
 781                                          *offset - seq_offset);
 782
 783     if (rc == 0) {
 784         DEBUGMSGTL(("ksm", "Building ksm security parameters failed.\n"));
 785         retval = SNMPERR_TOO_LONG;
 786         goto error;
 787     }
 788
 789     DEBUGMSGTL(("ksm", "KSM: Security parameter encoding completed\n"));
 790
 791     /*
 792      * We're done with the KSM security parameters - now we do the global
 793      * header and wrap up the whole PDU.
 794      */
 795
 796     if (*parms->wholeMsgLen < parms->globalDataLen) {
 797         DEBUGMSGTL(("ksm", "Building global data failed.\n"));
 798         retval = SNMPERR_TOO_LONG;
 799         goto error;
 800     }
 801
 802     *offset += parms->globalDataLen;
 803     memcpy(*wholeMsg + *parms->wholeMsgLen - *offset,
 804            parms->globalData, parms->globalDataLen);
 805
 806     rc = asn_realloc_rbuild_sequence(wholeMsg, parms->wholeMsgLen,
 807                                            offset, 1,
 808                                            (u_char) (ASN_SEQUENCE |
 809                                                      ASN_CONSTRUCTOR),
 810                                            *offset);
 811
 812     if (rc == 0) {
 813         DEBUGMSGTL(("ksm", "Building master packet sequence.\n"));
 814         retval = SNMPERR_TOO_LONG;
 815         goto error;
 816     }
 817
 818     DEBUGMSGTL(("ksm", "KSM: PDU master packet encoding complete.\n"));
 819
 820     /*
 821      * Now we need to checksum the entire PDU (since it's built).
 822      */
 823
 824     pdu_checksum.contents = malloc(pdu_checksum.length);
 825
 826     if (!pdu_checksum.contents) {
 827         DEBUGMSGTL(("ksm", "Unable to malloc %d bytes for checksum\n",
 828                     pdu_checksum.length));
 829         retval = SNMPERR_MALLOC;
 830         goto error;
 831     }
 832
 833     /*
 834      * If we didn't encrypt the packet, we haven't yet got the subkey.
 835      * Get that now.
 836      */
 837
 838     if (!subkey) {
 839         if (ksm_state)
 840             retcode = krb5_auth_con_getremotesubkey(kcontext, auth_context,
 841                                                     &subkey);
 842         else
 843             retcode = krb5_auth_con_getlocalsubkey(kcontext, auth_context,
 844                                                    &subkey);
 845         if (retcode) {
 846             DEBUGMSGTL(("ksm", "krb5_auth_con_getlocalsubkey failed: %s\n",
 847                         error_message(retcode)));
 848             snmp_set_detail(error_message(retcode));
 849             retval = SNMPERR_KRB5;
 850             goto error;
 851         }
 852     }
 853 #ifdef MIT_NEW_CRYPTO
 854
 855     input.data = (char *) (*wholeMsg + *parms->wholeMsgLen - *offset);
 856     input.length = *offset;
 857         retcode = krb5_c_make_checksum(kcontext, cksumtype, subkey,
 858                                        KSM_KEY_USAGE_CHECKSUM, &input,
 859                                        &pdu_checksum);
 860
 861 #else                           /* MIT_NEW_CRYPTO */
 862
 863     retcode = krb5_calculate_checksum(kcontext, cksumtype, *wholeMsg +
 864                                       *parms->wholeMsgLen - *offset,
 865                                       *offset,
 866                                       (krb5_pointer) subkey->contents,
 867                                       subkey->length, &pdu_checksum);
 868
 869 #endif                          /* MIT_NEW_CRYPTO */
 870
 871     if (retcode) {
 872         DEBUGMSGTL(("ksm", "Calculate checksum failed: %s\n",
 873                     error_message(retcode)));
 874         retval = SNMPERR_KRB5;
 875         snmp_set_detail(error_message(retcode));
 876         goto error;
 877     }
 878
 879     DEBUGMSGTL(("ksm", "KSM: Checksum calculation complete.\n"));
 880
 881     memcpy(cksum_pointer, pdu_checksum.contents, pdu_checksum.length);
 882
 883     DEBUGMSGTL(("ksm", "KSM: Writing checksum of %d bytes at offset %d\n",
 884                 pdu_checksum.length, cksum_pointer - (*wholeMsg + 1)));
 885
 886     DEBUGMSGTL(("ksm", "KSM: Checksum:"));
 887
 888     for (i = 0; i < pdu_checksum.length; i++)
 889         DEBUGMSG(("ksm", " %02x",
 890                   (unsigned int) pdu_checksum.contents[i]));
 891
 892     DEBUGMSG(("ksm", "\n"));
 893
 894     /*
 895      * If we're _not_ called as part of a response (null ksm_state),
 896      * then save the auth_context for later using our cache routines.
 897      */
 898
 899     if (!ksm_state) {
 900         if ((retval = ksm_insert_cache(parms->pdu->msgid, auth_context,
 901                                        (u_char *) parms->secName,
 902                                        parms->secNameLen)) !=
 903             SNMPERR_SUCCESS)
 904             goto error;
 905         auth_context = NULL;
 906     }
 907
 908     DEBUGMSGTL(("ksm", "KSM processing complete!\n"));
 909
 910   error:
 911
 912     if (pdu_checksum.contents)
 913 #ifdef MIT_NEW_CRYPTO
 914         krb5_free_checksum_contents(kcontext, &pdu_checksum);
 915 #else                           /* MIT_NEW_CRYPTO */
 916         free(pdu_checksum.contents);
 917 #endif                          /* MIT_NEW_CRYPTO */
 918
 919     if (ivector.data)
 920         free(ivector.data);
 921
 922     if (subkey)
 923         krb5_free_keyblock(kcontext, subkey);
 924
 925     if (encrypted_data)
 926         free(encrypted_data);
 927
 928     if (cc)
 929         krb5_cc_close(kcontext, cc);
 930
 931     if (auth_context && !ksm_state)
 932         krb5_auth_con_free(kcontext, auth_context);
 933
 934     return retval;
 935 }
 936
 937 /****************************************************************************
 938  *
 939  * ksm_process_in_msg
 940  *
 941  * Parameters:
 942  *      (See list below...)
 943  *
 944  * Returns:
 945  *      KSM_ERR_NO_ERROR                        On success.
 946  *      SNMPERR_KRB5
 947  *      KSM_ERR_GENERIC_ERROR
 948  *      KSM_ERR_UNSUPPORTED_SECURITY_LEVEL
 949  *
 950  *
 951  * Processes an incoming message.
 952  *
 953  ****************************************************************************/
 954
 955 int
 956 ksm_process_in_msg(struct snmp_secmod_incoming_params *parms)
 957 {
 958     long            temp;
 959     krb5_cksumtype  cksumtype;
 960     krb5_auth_context auth_context = NULL;
 961     krb5_error_code retcode;
 962     krb5_checksum   checksum;
 963     krb5_data       ap_req, ivector;
 964     krb5_flags      flags;
 965     krb5_keyblock  *subkey = NULL;
 966 #ifdef MIT_NEW_CRYPTO
 967     krb5_data       input, output;
 968     krb5_boolean    valid;
 969     krb5_enc_data   in_crypt;
 970 #else                           /* MIT_NEW_CRYPTO */
 971     krb5_encrypt_block eblock;
 972 #endif                          /* MIT_NEW_CRYPTO */
 973     krb5_ticket    *ticket = NULL;
 974     int             retval = SNMPERR_SUCCESS, response = 0;
 975     size_t          length =
 976         parms->wholeMsgLen - (u_int) (parms->secParams - parms->wholeMsg);
 977     u_char         *current = parms->secParams, type;
 978     size_t          cksumlength, blocksize;
 979     long            hint;
 980     char           *cname;
 981     struct ksm_secStateRef *ksm_state;
 982     struct ksm_cache_entry *entry;
 983
 984     DEBUGMSGTL(("ksm", "Processing has begun\n"));
 985
 986     checksum.contents = NULL;
 987     ap_req.data = NULL;
 988     ivector.length = 0;
 989     ivector.data = NULL;
 990
 991     /*
 992      * First, parse the security parameters (because we need the subkey inside
 993      * of the ticket to do anything
 994      */
 995
 996     if ((current = asn_parse_sequence(current, &length, &type,
 997                                       (ASN_UNIVERSAL | ASN_PRIMITIVE |
 998                                        ASN_OCTET_STR),
 999                                       "ksm first octet")) == NULL) {
1000         DEBUGMSGTL(("ksm", "Initial security paramter parsing failed\n"));
1001
1002         retval = SNMPERR_ASN_PARSE_ERR;
1003         goto error;
1004     }
1005
1006     if ((current = asn_parse_sequence(current, &length, &type,
1007                                       (ASN_SEQUENCE | ASN_CONSTRUCTOR),
1008                                       "ksm sequence")) == NULL) {
1009         DEBUGMSGTL(("ksm",
1010                     "Security parameter sequence parsing failed\n"));
1011
1012         retval = SNMPERR_ASN_PARSE_ERR;
1013         goto error;
1014     }
1015
1016     if ((current = asn_parse_int(current, &length, &type, &temp,
1017                                  sizeof(temp))) == NULL) {
1018         DEBUGMSGTL(("ksm", "Security parameter checksum type parsing"
1019                     "failed\n"));
1020
1021         retval = SNMPERR_ASN_PARSE_ERR;
1022         goto error;
1023     }
1024
1025     cksumtype = temp;
1026
1027     if (!valid_cksumtype(cksumtype)) {
1028         DEBUGMSGTL(("ksm", "Invalid checksum type (%d)\n", cksumtype));
1029
1030         retval = SNMPERR_KRB5;
1031         snmp_set_detail("Invalid checksum type");
1032         goto error;
1033     }
1034
1035     if (!is_keyed_cksum(cksumtype)) {
1036         DEBUGMSGTL(("ksm", "Checksum type %d is not a keyed checksum\n",
1037                     cksumtype));
1038         snmp_set_detail("Checksum is not a keyed checksum");
1039         retval = SNMPERR_KRB5;
1040         goto error;
1041     }
1042
1043     if (!is_coll_proof_cksum(cksumtype)) {
1044         DEBUGMSGTL(("ksm", "Checksum type %d is not a collision-proof "
1045                     "checksum\n", cksumtype));
1046         snmp_set_detail("Checksum is not a collision-proof checksum");
1047         retval = SNMPERR_KRB5;
1048         goto error;
1049     }
1050
1051     checksum.checksum_type = cksumtype;
1052
1053     cksumlength = length;
1054
1055     if ((current = asn_parse_sequence(current, &cksumlength, &type,
1056                                       (ASN_UNIVERSAL | ASN_PRIMITIVE |
1057                                        ASN_OCTET_STR), "ksm checksum")) ==
1058         NULL) {
1059         DEBUGMSGTL(("ksm",
1060                     "Security parameter checksum parsing failed\n"));
1061
1062         retval = SNMPERR_ASN_PARSE_ERR;
1063         goto error;
1064     }
1065
1066     checksum.contents = malloc(cksumlength);
1067     if (!checksum.contents) {
1068         DEBUGMSGTL(("ksm", "Unable to malloc %d bytes for checksum.\n",
1069                     cksumlength));
1070         retval = SNMPERR_MALLOC;
1071         goto error;
1072     }
1073
1074     memcpy(checksum.contents, current, cksumlength);
1075
1076     checksum.length = cksumlength;
1077     checksum.checksum_type = cksumtype;
1078
1079     /*
1080      * Zero out the checksum so the validation works correctly
1081      */
1082
1083     memset(current, 0, cksumlength);
1084
1085     current += cksumlength;
1086     length = parms->wholeMsgLen - (u_int) (current - parms->wholeMsg);
1087
1088     if ((current = asn_parse_sequence(current, &length, &type,
1089                                       (ASN_UNIVERSAL | ASN_PRIMITIVE |
1090                                        ASN_OCTET_STR), "ksm ap_req")) ==
1091         NULL) {
1092         DEBUGMSGTL(("ksm", "KSM security parameter AP_REQ/REP parsing "
1093                     "failed\n"));
1094
1095         retval = SNMPERR_ASN_PARSE_ERR;
1096         goto error;
1097     }
1098
1099     ap_req.length = length;
1100     ap_req.data = malloc(length);
1101     if (!ap_req.data) {
1102         DEBUGMSGTL(("ksm",
1103                     "KSM unable to malloc %d bytes for AP_REQ/REP.\n",
1104                     length));
1105         retval = SNMPERR_MALLOC;
1106         goto error;
1107     }
1108
1109     memcpy(ap_req.data, current, length);
1110
1111     current += length;
1112     length = parms->wholeMsgLen - (u_int) (current - parms->wholeMsg);
1113
1114     if ((current = asn_parse_int(current, &length, &type, &hint,
1115                                  sizeof(hint))) == NULL) {
1116         DEBUGMSGTL(("ksm",
1117                     "KSM security parameter hint parsing failed\n"));
1118
1119         retval = SNMPERR_ASN_PARSE_ERR;
1120         goto error;
1121     }
1122
1123     /*
1124      * Okay!  We've got it all!  Now try decoding the damn ticket.
1125      *
1126      * But of course there's a WRINKLE!  We need to figure out if we're
1127      * processing a AP_REQ or an AP_REP.  How do we do that?  We're going
1128      * to cheat, and look at the first couple of bytes (which is what
1129      * the Kerberos library routines do anyway).
1130      *
1131      * If there are ever new Kerberos message formats, we'll need to fix
1132      * this here.
1133      *
1134      * If it's a _response_, then we need to get the auth_context
1135      * from our cache.
1136      */
1137
1138     if (ap_req.length
1139         && (ap_req.data[0] == 0x6e || ap_req.data[0] == 0x4e)) {
1140
1141         /*
1142          * We need to initalize the authorization context, and set the
1143          * replay cache in it (and initialize the replay cache if we
1144          * haven't already
1145          */
1146
1147         retcode = krb5_auth_con_init(kcontext, &auth_context);
1148
1149         if (retcode) {
1150             DEBUGMSGTL(("ksm", "krb5_auth_con_init failed: %s\n",
1151                         error_message(retcode)));
1152             retval = SNMPERR_KRB5;
1153             snmp_set_detail(error_message(retcode));
1154             goto error;
1155         }
1156
1157         if (!rcache) {
1158             krb5_data       server;
1159             server.data = "host";
1160             server.length = strlen(server.data);
1161
1162             retcode = krb5_get_server_rcache(kcontext, &server, &rcache);
1163
1164             if (retcode) {
1165                 DEBUGMSGTL(("ksm", "krb5_get_server_rcache failed: %s\n",
1166                             error_message(retcode)));
1167                 retval = SNMPERR_KRB5;
1168                 snmp_set_detail(error_message(retcode));
1169                 goto error;
1170             }
1171         }
1172
1173         retcode = krb5_auth_con_setrcache(kcontext, auth_context, rcache);
1174
1175         if (retcode) {
1176             DEBUGMSGTL(("ksm", "krb5_auth_con_setrcache failed: %s\n",
1177                         error_message(retcode)));
1178             retval = SNMPERR_KRB5;
1179             snmp_set_detail(error_message(retcode));
1180             goto error;
1181         }
1182
1183         retcode = krb5_rd_req(kcontext, &auth_context, &ap_req, NULL,
1184                               NULL, &flags, &ticket);
1185
1186         krb5_auth_con_setrcache(kcontext, auth_context, NULL);
1187
1188         if (retcode) {
1189             DEBUGMSGTL(("ksm", "krb5_rd_req() failed: %s\n",
1190                         error_message(retcode)));
1191             retval = SNMPERR_KRB5;
1192             snmp_set_detail(error_message(retcode));
1193             goto error;
1194         }
1195
1196         retcode =
1197             krb5_unparse_name(kcontext, ticket->enc_part2->client, &cname);
1198
1199         if (retcode == 0) {
1200             DEBUGMSGTL(("ksm", "KSM authenticated principal name: %s\n",
1201                         cname));
1202             free(cname);
1203         }
1204
1205         /*
1206          * Check to make sure AP_OPTS_MUTUAL_REQUIRED was set
1207          */
1208
1209         if (!(flags & AP_OPTS_MUTUAL_REQUIRED)) {
1210             DEBUGMSGTL(("ksm",
1211                         "KSM MUTUAL_REQUIRED not set in request!\n"));
1212             retval = SNMPERR_KRB5;
1213             snmp_set_detail("MUTUAL_REQUIRED not set in message");
1214             goto error;
1215         }
1216
1217         retcode =
1218             krb5_auth_con_getremotesubkey(kcontext, auth_context, &subkey);
1219
1220         if (retcode) {
1221             DEBUGMSGTL(("ksm", "KSM remote subkey retrieval failed: %s\n",
1222                         error_message(retcode)));
1223             retval = SNMPERR_KRB5;
1224             snmp_set_detail(error_message(retcode));
1225             goto error;
1226         }
1227
1228     } else if (ap_req.length && (ap_req.data[0] == 0x6f ||
1229                                  ap_req.data[0] == 0x4f)) {
1230         /*
1231          * Looks like a response; let's see if we've got that auth_context
1232          * in our cache.
1233          */
1234
1235         krb5_ap_rep_enc_part *repl = NULL;
1236
1237         response = 1;
1238
1239         entry = ksm_get_cache(parms->pdu->msgid);
1240
1241         if (!entry) {
1242             DEBUGMSGTL(("ksm",
1243                         "KSM: Unable to find auth_context for PDU with "
1244                         "message ID of %ld\n", parms->pdu->msgid));
1245             retval = SNMPERR_KRB5;
1246             goto error;
1247         }
1248
1249         auth_context = entry->auth_context;
1250
1251         /*
1252          * In that case, let's call the rd_rep function
1253          */
1254
1255         retcode = krb5_rd_rep(kcontext, auth_context, &ap_req, &repl);
1256
1257         if (repl)
1258             krb5_free_ap_rep_enc_part(kcontext, repl);
1259
1260         if (retcode) {
1261             DEBUGMSGTL(("ksm", "KSM: krb5_rd_rep() failed: %s\n",
1262                         error_message(retcode)));
1263             retval = SNMPERR_KRB5;
1264             goto error;
1265         }
1266
1267         DEBUGMSGTL(("ksm", "KSM: krb5_rd_rep() decoded successfully.\n"));
1268
1269         retcode =
1270             krb5_auth_con_getlocalsubkey(kcontext, auth_context, &subkey);
1271
1272         if (retcode) {
1273             DEBUGMSGTL(("ksm", "Unable to retrieve local subkey: %s\n",
1274                         error_message(retcode)));
1275             retval = SNMPERR_KRB5;
1276             snmp_set_detail("Unable to retrieve local subkey");
1277             goto error;
1278         }
1279
1280     } else {
1281         DEBUGMSGTL(("ksm", "Unknown Kerberos message type (%02x)\n",
1282                     ap_req.data[0]));
1283         retval = SNMPERR_KRB5;
1284         snmp_set_detail("Unknown Kerberos message type");
1285         goto error;
1286     }
1287
1288 #ifdef MIT_NEW_CRYPTO
1289     input.data = (char *) parms->wholeMsg;
1290     input.length = parms->wholeMsgLen;
1291
1292     retcode =
1293         krb5_c_verify_checksum(kcontext, subkey, KSM_KEY_USAGE_CHECKSUM,
1294                                &input, &checksum, &valid);
1295 #else                           /* MIT_NEW_CRYPTO */
1296     retcode = krb5_verify_checksum(kcontext, cksumtype, &checksum,
1297                                    parms->wholeMsg, parms->wholeMsgLen,
1298                                    (krb5_pointer) subkey->contents,
1299                                    subkey->length);
1300 #endif                          /* MIT_NEW_CRYPTO */
1301
1302     if (retcode) {
1303         DEBUGMSGTL(("ksm", "KSM checksum verification failed: %s\n",
1304                     error_message(retcode)));
1305         retval = SNMPERR_KRB5;
1306         snmp_set_detail(error_message(retcode));
1307         goto error;
1308     }
1309
1310     /*
1311      * Don't ask me why they didn't simply return an error, but we have
1312      * to check to see if "valid" is false.
1313      */
1314
1315 #ifdef MIT_NEW_CRYPTO
1316     if (!valid) {
1317         DEBUGMSGTL(("ksm", "Computed checksum did not match supplied "
1318                     "checksum!\n"));
1319         retval = SNMPERR_KRB5;
1320         snmp_set_detail
1321             ("Computed checksum did not match supplied checksum");
1322         goto error;
1323     }
1324 #endif                          /* MIT_NEW_CRYPTO */
1325
1326     /*
1327      * Handle an encrypted PDU.  Note that it's an OCTET_STRING of the
1328      * output of whatever Kerberos cryptosystem you're using (defined by
1329      * the encryption type).  Note that this is NOT the EncryptedData
1330      * sequence - it's what goes in the "cipher" field of EncryptedData.
1331      */
1332
1333     if (parms->secLevel == SNMP_SEC_LEVEL_AUTHPRIV) {
1334
1335         if ((current = asn_parse_sequence(current, &length, &type,
1336                                           (ASN_UNIVERSAL | ASN_PRIMITIVE |
1337                                            ASN_OCTET_STR), "ksm pdu")) ==
1338             NULL) {
1339             DEBUGMSGTL(("ksm", "KSM sPDU octet decoding failed\n"));
1340             retval = SNMPERR_ASN_PARSE_ERR;
1341             goto error;
1342         }
1343
1344         /*
1345          * The PDU is now pointed at by "current", and the length is in
1346          * "length".
1347          */
1348
1349         DEBUGMSGTL(("ksm", "KSM starting sPDU decode\n"));
1350
1351         /*
1352          * We need to set up a blank initialization vector for the decryption.
1353          * Use a block of all zero's (which is dependent on the block size
1354          * of the encryption method).
1355          */
1356
1357 #ifdef MIT_NEW_CRYPTO
1358
1359         retcode = krb5_c_block_size(kcontext, subkey->enctype, &blocksize);
1360
1361         if (retcode) {
1362             DEBUGMSGTL(("ksm",
1363                         "Unable to determine crypto block size: %s\n",
1364                         error_message(retcode)));
1365             snmp_set_detail(error_message(retcode));
1366             retval = SNMPERR_KRB5;
1367             goto error;
1368         }
1369 #else                           /* MIT_NEW_CRYPTO */
1370
1371         blocksize =
1372             krb5_enctype_array[subkey->enctype]->system->block_length;
1373
1374 #endif                          /* MIT_NEW_CRYPTO */
1375
1376         ivector.data = malloc(blocksize);
1377
1378         if (!ivector.data) {
1379             DEBUGMSGTL(("ksm", "Unable to allocate %d bytes for ivector\n",
1380                         blocksize));
1381             retval = SNMPERR_MALLOC;
1382             goto error;
1383         }
1384
1385         ivector.length = blocksize;
1386         memset(ivector.data, 0, blocksize);
1387
1388 #ifndef MIT_NEW_CRYPTO
1389
1390         krb5_use_enctype(kcontext, &eblock, subkey->enctype);
1391
1392         retcode = krb5_process_key(kcontext, &eblock, subkey);
1393
1394         if (retcode) {
1395             DEBUGMSGTL(("ksm", "KSM key post-processing failed: %s\n",
1396                         error_message(retcode)));
1397             snmp_set_detail(error_message(retcode));
1398             retval = SNMPERR_KRB5;
1399             goto error;
1400         }
1401 #endif                          /* !MIT_NEW_CRYPTO */
1402
1403         if (length > *parms->scopedPduLen) {
1404             DEBUGMSGTL(("ksm", "KSM not enough room - have %d bytes to "
1405                         "decrypt but only %d bytes available\n", length,
1406                         *parms->scopedPduLen));
1407             retval = SNMPERR_TOO_LONG;
1408 #ifndef MIT_NEW_CRYPTO
1409             krb5_finish_key(kcontext, &eblock);
1410 #endif                          /* ! MIT_NEW_CRYPTO */
1411             goto error;
1412         }
1413 #ifdef MIT_NEW_CRYPTO
1414         in_crypt.ciphertext.data = (char *) current;
1415         in_crypt.ciphertext.length = length;
1416         in_crypt.enctype = subkey->enctype;
1417         output.data = (char *) *parms->scopedPdu;
1418         output.length = *parms->scopedPduLen;
1419
1420         retcode =
1421             krb5_c_decrypt(kcontext, subkey, KSM_KEY_USAGE_ENCRYPTION,
1422                            &ivector, &in_crypt, &output);
1423 #else                           /* MIT_NEW_CRYPTO */
1424
1425         retcode = krb5_decrypt(kcontext, (krb5_pointer) current,
1426                                *parms->scopedPdu, length, &eblock,
1427                                ivector.data);
1428
1429         krb5_finish_key(kcontext, &eblock);
1430
1431 #endif                          /* MIT_NEW_CRYPTO */
1432
1433         if (retcode) {
1434             DEBUGMSGTL(("ksm", "Decryption failed: %s\n",
1435                         error_message(retcode)));
1436             snmp_set_detail(error_message(retcode));
1437             retval = SNMPERR_KRB5;
1438             goto error;
1439         }
1440
1441         *parms->scopedPduLen = length;
1442
1443     } else {
1444         /*
1445          * Clear PDU
1446          */
1447
1448         *parms->scopedPdu = current;
1449         *parms->scopedPduLen =
1450             parms->wholeMsgLen - (current - parms->wholeMsg);
1451     }
1452
1453     /*
1454      * A HUGE GROSS HACK
1455      */
1456
1457     *parms->maxSizeResponse = parms->maxMsgSize - 200;
1458
1459     DEBUGMSGTL(("ksm", "KSM processing complete\n"));
1460
1461     /*
1462      * Set the secName to the right value (a hack for now).  But that's
1463      * only used for when we're processing a request, not a response.
1464      */
1465
1466     if (!response) {
1467
1468         retcode = krb5_unparse_name(kcontext, ticket->enc_part2->client,
1469                                     &cname);
1470
1471         if (retcode) {
1472             DEBUGMSGTL(("ksm", "KSM krb5_unparse_name failed: %s\n",
1473                         error_message(retcode)));
1474             snmp_set_detail(error_message(retcode));
1475             retval = SNMPERR_KRB5;
1476             goto error;
1477         }
1478
1479         if (strlen(cname) > *parms->secNameLen + 1) {
1480             DEBUGMSGTL(("ksm",
1481                         "KSM: Principal length (%d) is too long (%d)\n",
1482                         strlen(cname), parms->secNameLen));
1483             retval = SNMPERR_TOO_LONG;
1484             free(cname);
1485             goto error;
1486         }
1487
1488         strcpy(parms->secName, cname);
1489         *parms->secNameLen = strlen(cname);
1490
1491         free(cname);
1492
1493         /*
1494          * Also, if we're not a response, keep around our auth_context so we
1495          * can encode the reply message correctly
1496          */
1497
1498         ksm_state = SNMP_MALLOC_STRUCT(ksm_secStateRef);
1499
1500         if (!ksm_state) {
1501             DEBUGMSGTL(("ksm", "KSM unable to malloc memory for "
1502                         "ksm_secStateRef\n"));
1503             retval = SNMPERR_MALLOC;
1504             goto error;
1505         }
1506
1507         ksm_state->auth_context = auth_context;
1508         auth_context = NULL;
1509         ksm_state->cksumtype = cksumtype;
1510
1511         *parms->secStateRef = ksm_state;
1512     } else {
1513
1514         /*
1515          * We _still_ have to set the secName in process_in_msg().  Do
1516          * that now with what we were passed in before (we cached it,
1517          * remember?)
1518          */
1519
1520         memcpy(parms->secName, entry->secName, entry->secNameLen);
1521         *parms->secNameLen = entry->secNameLen;
1522     }
1523
1524     /*
1525      * Just in case
1526      */
1527
1528     parms->secEngineID = (u_char *) "";
1529     *parms->secEngineIDLen = 0;
1530
1531     auth_context = NULL;        /* So we don't try to free it on success */
1532
1533   error:
1534     if (retval == SNMPERR_ASN_PARSE_ERR &&
1535         snmp_increment_statistic(STAT_SNMPINASNPARSEERRS) == 0)
1536         DEBUGMSGTL(("ksm", "Failed to increment statistics.\n"));
1537
1538     if (subkey)
1539         krb5_free_keyblock(kcontext, subkey);
1540
1541     if (checksum.contents)
1542         free(checksum.contents);
1543
1544     if (ivector.data)
1545         free(ivector.data);
1546
1547     if (ticket)
1548         krb5_free_ticket(kcontext, ticket);
1549
1550     if (!response && auth_context)
1551         krb5_auth_con_free(kcontext, auth_context);
1552
1553     if (ap_req.data)
1554         free(ap_req.data);
1555
1556     return retval;
1557 }