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   1 /*
   2  * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
   3  * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
   4  *
   5  * Copyright (c) 2000 RP Internet (www.rpi.net.au).
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  18  */
  19
  20 #include <linux/module.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/mm.h>
  24 #include <linux/slab.h>
  25 #include "cifspdu.h"
  26 #include "cifsglob.h"
  27 #include "cifs_debug.h"
  28 #include "cifsproto.h"
  29
  30 /*****************************************************************************
  31  *
  32  * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
  33  *
  34  *****************************************************************************/
  35
  36 /* Class */
  37 #define ASN1_UNI        0       /* Universal */
  38 #define ASN1_APL        1       /* Application */
  39 #define ASN1_CTX        2       /* Context */
  40 #define ASN1_PRV        3       /* Private */
  41
  42 /* Tag */
  43 #define ASN1_EOC        0       /* End Of Contents or N/A */
  44 #define ASN1_BOL        1       /* Boolean */
  45 #define ASN1_INT        2       /* Integer */
  46 #define ASN1_BTS        3       /* Bit String */
  47 #define ASN1_OTS        4       /* Octet String */
  48 #define ASN1_NUL        5       /* Null */
  49 #define ASN1_OJI        6       /* Object Identifier  */
  50 #define ASN1_OJD        7       /* Object Description */
  51 #define ASN1_EXT        8       /* External */
  52 #define ASN1_SEQ        16      /* Sequence */
  53 #define ASN1_SET        17      /* Set */
  54 #define ASN1_NUMSTR     18      /* Numerical String */
  55 #define ASN1_PRNSTR     19      /* Printable String */
  56 #define ASN1_TEXSTR     20      /* Teletext String */
  57 #define ASN1_VIDSTR     21      /* Video String */
  58 #define ASN1_IA5STR     22      /* IA5 String */
  59 #define ASN1_UNITIM     23      /* Universal Time */
  60 #define ASN1_GENTIM     24      /* General Time */
  61 #define ASN1_GRASTR     25      /* Graphical String */
  62 #define ASN1_VISSTR     26      /* Visible String */
  63 #define ASN1_GENSTR     27      /* General String */
  64
  65 /* Primitive / Constructed methods*/
  66 #define ASN1_PRI        0       /* Primitive */
  67 #define ASN1_CON        1       /* Constructed */
  68
  69 /*
  70  * Error codes.
  71  */
  72 #define ASN1_ERR_NOERROR                0
  73 #define ASN1_ERR_DEC_EMPTY              2
  74 #define ASN1_ERR_DEC_EOC_MISMATCH       3
  75 #define ASN1_ERR_DEC_LENGTH_MISMATCH    4
  76 #define ASN1_ERR_DEC_BADVALUE           5
  77
  78 #define SPNEGO_OID_LEN 7
  79 #define NTLMSSP_OID_LEN  10
  80 #define KRB5_OID_LEN  7
  81 #define MSKRB5_OID_LEN  7
  82 static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
  83 static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
  84 static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
  85 static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };
  86
  87 /*
  88  * ASN.1 context.
  89  */
  90 struct asn1_ctx {
  91         int error;              /* Error condition */
  92         unsigned char *pointer; /* Octet just to be decoded */
  93         unsigned char *begin;   /* First octet */
  94         unsigned char *end;     /* Octet after last octet */
  95 };
  96
  97 /*
  98  * Octet string (not null terminated)
  99  */
 100 struct asn1_octstr {
 101         unsigned char *data;
 102         unsigned int len;
 103 };
 104
 105 static void
 106 asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
 107 {
 108         ctx->begin = buf;
 109         ctx->end = buf + len;
 110         ctx->pointer = buf;
 111         ctx->error = ASN1_ERR_NOERROR;
 112 }
 113
 114 static unsigned char
 115 asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
 116 {
 117         if (ctx->pointer >= ctx->end) {
 118                 ctx->error = ASN1_ERR_DEC_EMPTY;
 119                 return 0;
 120         }
 121         *ch = *(ctx->pointer)++;
 122         return 1;
 123 }
 124
 125 static unsigned char
 126 asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
 127 {
 128         unsigned char ch;
 129
 130         *tag = 0;
 131
 132         do {
 133                 if (!asn1_octet_decode(ctx, &ch))
 134                         return 0;
 135                 *tag <<= 7;
 136                 *tag |= ch & 0x7F;
 137         } while ((ch & 0x80) == 0x80);
 138         return 1;
 139 }
 140
 141 static unsigned char
 142 asn1_id_decode(struct asn1_ctx *ctx,
 143                unsigned int *cls, unsigned int *con, unsigned int *tag)
 144 {
 145         unsigned char ch;
 146
 147         if (!asn1_octet_decode(ctx, &ch))
 148                 return 0;
 149
 150         *cls = (ch & 0xC0) >> 6;
 151         *con = (ch & 0x20) >> 5;
 152         *tag = (ch & 0x1F);
 153
 154         if (*tag == 0x1F) {
 155                 if (!asn1_tag_decode(ctx, tag))
 156                         return 0;
 157         }
 158         return 1;
 159 }
 160
 161 static unsigned char
 162 asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
 163 {
 164         unsigned char ch, cnt;
 165
 166         if (!asn1_octet_decode(ctx, &ch))
 167                 return 0;
 168
 169         if (ch == 0x80)
 170                 *def = 0;
 171         else {
 172                 *def = 1;
 173
 174                 if (ch < 0x80)
 175                         *len = ch;
 176                 else {
 177                         cnt = (unsigned char) (ch & 0x7F);
 178                         *len = 0;
 179
 180                         while (cnt > 0) {
 181                                 if (!asn1_octet_decode(ctx, &ch))
 182                                         return 0;
 183                                 *len <<= 8;
 184                                 *len |= ch;
 185                                 cnt--;
 186                         }
 187                 }
 188         }
 189         return 1;
 190 }
 191
 192 static unsigned char
 193 asn1_header_decode(struct asn1_ctx *ctx,
 194                    unsigned char **eoc,
 195                    unsigned int *cls, unsigned int *con, unsigned int *tag)
 196 {
 197         unsigned int def = 0;
 198         unsigned int len = 0;
 199
 200         if (!asn1_id_decode(ctx, cls, con, tag))
 201                 return 0;
 202
 203         if (!asn1_length_decode(ctx, &def, &len))
 204                 return 0;
 205
 206         if (def)
 207                 *eoc = ctx->pointer + len;
 208         else
 209                 *eoc = NULL;
 210         return 1;
 211 }
 212
 213 static unsigned char
 214 asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
 215 {
 216         unsigned char ch;
 217
 218         if (eoc == NULL) {
 219                 if (!asn1_octet_decode(ctx, &ch))
 220                         return 0;
 221
 222                 if (ch != 0x00) {
 223                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 224                         return 0;
 225                 }
 226
 227                 if (!asn1_octet_decode(ctx, &ch))
 228                         return 0;
 229
 230                 if (ch != 0x00) {
 231                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 232                         return 0;
 233                 }
 234                 return 1;
 235         } else {
 236                 if (ctx->pointer != eoc) {
 237                         ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
 238                         return 0;
 239                 }
 240                 return 1;
 241         }
 242 }
 243
 244 /* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
 245                                       unsigned char *eoc)
 246 {
 247         ctx->pointer = eoc;
 248         return 1;
 249 }
 250
 251 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
 252                                       unsigned char *eoc, long *integer)
 253 {
 254         unsigned char ch;
 255         unsigned int len;
 256
 257         if (!asn1_octet_decode(ctx, &ch))
 258                 return 0;
 259
 260         *integer = (signed char) ch;
 261         len = 1;
 262
 263         while (ctx->pointer < eoc) {
 264                 if (++len > sizeof(long)) {
 265                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 266                         return 0;
 267                 }
 268
 269                 if (!asn1_octet_decode(ctx, &ch))
 270                         return 0;
 271
 272                 *integer <<= 8;
 273                 *integer |= ch;
 274         }
 275         return 1;
 276 }
 277
 278 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
 279                                       unsigned char *eoc,
 280                                       unsigned int *integer)
 281 {
 282         unsigned char ch;
 283         unsigned int len;
 284
 285         if (!asn1_octet_decode(ctx, &ch))
 286                 return 0;
 287
 288         *integer = ch;
 289         if (ch == 0)
 290                 len = 0;
 291         else
 292                 len = 1;
 293
 294         while (ctx->pointer < eoc) {
 295                 if (++len > sizeof(unsigned int)) {
 296                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 297                         return 0;
 298                 }
 299
 300                 if (!asn1_octet_decode(ctx, &ch))
 301                         return 0;
 302
 303                 *integer <<= 8;
 304                 *integer |= ch;
 305         }
 306         return 1;
 307 }
 308
 309 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
 310                                        unsigned char *eoc,
 311                                        unsigned long *integer)
 312 {
 313         unsigned char ch;
 314         unsigned int len;
 315
 316         if (!asn1_octet_decode(ctx, &ch))
 317                 return 0;
 318
 319         *integer = ch;
 320         if (ch == 0)
 321                 len = 0;
 322         else
 323                 len = 1;
 324
 325         while (ctx->pointer < eoc) {
 326                 if (++len > sizeof(unsigned long)) {
 327                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 328                         return 0;
 329                 }
 330
 331                 if (!asn1_octet_decode(ctx, &ch))
 332                         return 0;
 333
 334                 *integer <<= 8;
 335                 *integer |= ch;
 336         }
 337         return 1;
 338 }
 339
 340 static unsigned char
 341 asn1_octets_decode(struct asn1_ctx *ctx,
 342                    unsigned char *eoc,
 343                    unsigned char **octets, unsigned int *len)
 344 {
 345         unsigned char *ptr;
 346
 347         *len = 0;
 348
 349         *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
 350         if (*octets == NULL) {
 351                 return 0;
 352         }
 353
 354         ptr = *octets;
 355         while (ctx->pointer < eoc) {
 356                 if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
 357                         kfree(*octets);
 358                         *octets = NULL;
 359                         return 0;
 360                 }
 361                 (*len)++;
 362         }
 363         return 1;
 364 } */
 365
 366 static unsigned char
 367 asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
 368 {
 369         unsigned char ch;
 370
 371         *subid = 0;
 372
 373         do {
 374                 if (!asn1_octet_decode(ctx, &ch))
 375                         return 0;
 376
 377                 *subid <<= 7;
 378                 *subid |= ch & 0x7F;
 379         } while ((ch & 0x80) == 0x80);
 380         return 1;
 381 }
 382
 383 static int
 384 asn1_oid_decode(struct asn1_ctx *ctx,
 385                 unsigned char *eoc, unsigned long **oid, unsigned int *len)
 386 {
 387         unsigned long subid;
 388         unsigned int size;
 389         unsigned long *optr;
 390
 391         size = eoc - ctx->pointer + 1;
 392         *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
 393         if (*oid == NULL)
 394                 return 0;
 395
 396         optr = *oid;
 397
 398         if (!asn1_subid_decode(ctx, &subid)) {
 399                 kfree(*oid);
 400                 *oid = NULL;
 401                 return 0;
 402         }
 403
 404         if (subid < 40) {
 405                 optr[0] = 0;
 406                 optr[1] = subid;
 407         } else if (subid < 80) {
 408                 optr[0] = 1;
 409                 optr[1] = subid - 40;
 410         } else {
 411                 optr[0] = 2;
 412                 optr[1] = subid - 80;
 413         }
 414
 415         *len = 2;
 416         optr += 2;
 417
 418         while (ctx->pointer < eoc) {
 419                 if (++(*len) > size) {
 420                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 421                         kfree(*oid);
 422                         *oid = NULL;
 423                         return 0;
 424                 }
 425
 426                 if (!asn1_subid_decode(ctx, optr++)) {
 427                         kfree(*oid);
 428                         *oid = NULL;
 429                         return 0;
 430                 }
 431         }
 432         return 1;
 433 }
 434
 435 static int
 436 compare_oid(unsigned long *oid1, unsigned int oid1len,
 437             unsigned long *oid2, unsigned int oid2len)
 438 {
 439         unsigned int i;
 440
 441         if (oid1len != oid2len)
 442                 return 0;
 443         else {
 444                 for (i = 0; i < oid1len; i++) {
 445                         if (oid1[i] != oid2[i])
 446                                 return 0;
 447                 }
 448                 return 1;
 449         }
 450 }
 451
 452         /* BB check for endian conversion issues here */
 453
 454 int
 455 decode_negTokenInit(unsigned char *security_blob, int length,
 456                     enum securityEnum *secType)
 457 {
 458         struct asn1_ctx ctx;
 459         unsigned char *end;
 460         unsigned char *sequence_end;
 461         unsigned long *oid = NULL;
 462         unsigned int cls, con, tag, oidlen, rc;
 463         int use_ntlmssp = FALSE;
 464         int use_kerberos = FALSE;
 465
 466         *secType = NTLM; /* BB eventually make Kerberos or NLTMSSP the default*/
 467
 468         /* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
 469
 470         asn1_open(&ctx, security_blob, length);
 471
 472         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 473                 cFYI(1, ("Error decoding negTokenInit header"));
 474                 return 0;
 475         } else if ((cls != ASN1_APL) || (con != ASN1_CON)
 476                    || (tag != ASN1_EOC)) {
 477                 cFYI(1, ("cls = %d con = %d tag = %d", cls, con, tag));
 478                 return 0;
 479         } else {
 480                 /*      remember to free obj->oid */
 481                 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 482                 if (rc) {
 483                         if ((tag == ASN1_OJI) && (cls == ASN1_PRI)) {
 484                                 rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
 485                                 if (rc) {
 486                                         rc = compare_oid(oid, oidlen,
 487                                                          SPNEGO_OID,
 488                                                          SPNEGO_OID_LEN);
 489                                         kfree(oid);
 490                                 }
 491                         } else
 492                                 rc = 0;
 493                 }
 494
 495                 if (!rc) {
 496                         cFYI(1, ("Error decoding negTokenInit header"));
 497                         return 0;
 498                 }
 499
 500                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 501                         cFYI(1, ("Error decoding negTokenInit"));
 502                         return 0;
 503                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 504                            || (tag != ASN1_EOC)) {
 505                         cFYI(1,
 506                              ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
 507                               cls, con, tag, end, *end));
 508                         return 0;
 509                 }
 510
 511                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 512                         cFYI(1, ("Error decoding negTokenInit"));
 513                         return 0;
 514                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 515                            || (tag != ASN1_SEQ)) {
 516                         cFYI(1,
 517                              ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
 518                               cls, con, tag, end, *end));
 519                         return 0;
 520                 }
 521
 522                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 523                         cFYI(1, ("Error decoding 2nd part of negTokenInit"));
 524                         return 0;
 525                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 526                            || (tag != ASN1_EOC)) {
 527                         cFYI(1,
 528                              ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
 529                               cls, con, tag, end, *end));
 530                         return 0;
 531                 }
 532
 533                 if (asn1_header_decode
 534                     (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
 535                         cFYI(1, ("Error decoding 2nd part of negTokenInit"));
 536                         return 0;
 537                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 538                            || (tag != ASN1_SEQ)) {
 539                         cFYI(1,
 540                              ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
 541                               cls, con, tag, end, *end));
 542                         return 0;
 543                 }
 544
 545                 while (!asn1_eoc_decode(&ctx, sequence_end)) {
 546                         rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 547                         if (!rc) {
 548                                 cFYI(1,
 549                                      ("Error decoding negTokenInit hdr exit2"));
 550                                 return 0;
 551                         }
 552                         if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
 553                                 if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
 554
 555                                         cFYI(1,
 556                                           ("OID len = %d oid = 0x%lx 0x%lx "
 557                                            "0x%lx 0x%lx",
 558                                            oidlen, *oid, *(oid + 1),
 559                                            *(oid + 2), *(oid + 3)));
 560
 561                                         if (compare_oid(oid, oidlen,
 562                                                         MSKRB5_OID,
 563                                                         MSKRB5_OID_LEN))
 564                                                 use_kerberos = TRUE;
 565                                         else if (compare_oid(oid, oidlen,
 566                                                              KRB5_OID,
 567                                                              KRB5_OID_LEN))
 568                                                 use_kerberos = TRUE;
 569                                         else if (compare_oid(oid, oidlen,
 570                                                              NTLMSSP_OID,
 571                                                              NTLMSSP_OID_LEN))
 572                                                 use_ntlmssp = TRUE;
 573
 574                                         kfree(oid);
 575                                 }
 576                         } else {
 577                                 cFYI(1, ("Should be an oid what is going on?"));
 578                         }
 579                 }
 580
 581                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 582                         cFYI(1,
 583                              ("Error decoding last part negTokenInit exit3"));
 584                         return 0;
 585                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
 586                         /* tag = 3 indicating mechListMIC */
 587                         cFYI(1,
 588                              ("Exit 4 cls = %d con = %d tag = %d end = %p (%d)",
 589                               cls, con, tag, end, *end));
 590                         return 0;
 591                 }
 592                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 593                         cFYI(1,
 594                              ("Error decoding last part negTokenInit exit5"));
 595                         return 0;
 596                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 597                            || (tag != ASN1_SEQ)) {
 598                         cFYI(1, ("cls = %d con = %d tag = %d end = %p (%d)",
 599                                 cls, con, tag, end, *end));
 600                 }
 601
 602                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 603                         cFYI(1,
 604                              ("Error decoding last part negTokenInit exit 7"));
 605                         return 0;
 606                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
 607                         cFYI(1,
 608                              ("Exit 8 cls = %d con = %d tag = %d end = %p (%d)",
 609                               cls, con, tag, end, *end));
 610                         return 0;
 611                 }
 612                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 613                         cFYI(1,
 614                              ("Error decoding last part negTokenInit exit9"));
 615                         return 0;
 616                 } else if ((cls != ASN1_UNI) || (con != ASN1_PRI)
 617                            || (tag != ASN1_GENSTR)) {
 618                         cFYI(1,
 619                              ("Exit10 cls = %d con = %d tag = %d end = %p (%d)",
 620                               cls, con, tag, end, *end));
 621                         return 0;
 622                 }
 623                 cFYI(1, ("Need to call asn1_octets_decode() function for %s",
 624                          ctx.pointer)); /* is this UTF-8 or ASCII? */
 625         }
 626
 627         if (use_kerberos)
 628                 *secType = Kerberos;
 629         else if (use_ntlmssp)
 630                 *secType = NTLMSSP;
 631
 632         return 1;
 633 }