fs/cifs/asn1.c

   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 static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
  81 static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
  82
  83 /*
  84  * ASN.1 context.
  85  */
  86 struct asn1_ctx {
  87         int error;              /* Error condition */
  88         unsigned char *pointer; /* Octet just to be decoded */
  89         unsigned char *begin;   /* First octet */
  90         unsigned char *end;     /* Octet after last octet */
  91 };
  92
  93 /*
  94  * Octet string (not null terminated)
  95  */
  96 struct asn1_octstr {
  97         unsigned char *data;
  98         unsigned int len;
  99 };
 100
 101 static void
 102 asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
 103 {
 104         ctx->begin = buf;
 105         ctx->end = buf + len;
 106         ctx->pointer = buf;
 107         ctx->error = ASN1_ERR_NOERROR;
 108 }
 109
 110 static unsigned char
 111 asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
 112 {
 113         if (ctx->pointer >= ctx->end) {
 114                 ctx->error = ASN1_ERR_DEC_EMPTY;
 115                 return 0;
 116         }
 117         *ch = *(ctx->pointer)++;
 118         return 1;
 119 }
 120
 121 static unsigned char
 122 asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
 123 {
 124         unsigned char ch;
 125
 126         *tag = 0;
 127
 128         do {
 129                 if (!asn1_octet_decode(ctx, &ch))
 130                         return 0;
 131                 *tag <<= 7;
 132                 *tag |= ch & 0x7F;
 133         } while ((ch & 0x80) == 0x80);
 134         return 1;
 135 }
 136
 137 static unsigned char
 138 asn1_id_decode(struct asn1_ctx *ctx,
 139                unsigned int *cls, unsigned int *con, unsigned int *tag)
 140 {
 141         unsigned char ch;
 142
 143         if (!asn1_octet_decode(ctx, &ch))
 144                 return 0;
 145
 146         *cls = (ch & 0xC0) >> 6;
 147         *con = (ch & 0x20) >> 5;
 148         *tag = (ch & 0x1F);
 149
 150         if (*tag == 0x1F) {
 151                 if (!asn1_tag_decode(ctx, tag))
 152                         return 0;
 153         }
 154         return 1;
 155 }
 156
 157 static unsigned char
 158 asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
 159 {
 160         unsigned char ch, cnt;
 161
 162         if (!asn1_octet_decode(ctx, &ch))
 163                 return 0;
 164
 165         if (ch == 0x80)
 166                 *def = 0;
 167         else {
 168                 *def = 1;
 169
 170                 if (ch < 0x80)
 171                         *len = ch;
 172                 else {
 173                         cnt = (unsigned char) (ch & 0x7F);
 174                         *len = 0;
 175
 176                         while (cnt > 0) {
 177                                 if (!asn1_octet_decode(ctx, &ch))
 178                                         return 0;
 179                                 *len <<= 8;
 180                                 *len |= ch;
 181                                 cnt--;
 182                         }
 183                 }
 184         }
 185         return 1;
 186 }
 187
 188 static unsigned char
 189 asn1_header_decode(struct asn1_ctx *ctx,
 190                    unsigned char **eoc,
 191                    unsigned int *cls, unsigned int *con, unsigned int *tag)
 192 {
 193         unsigned int def = 0;
 194         unsigned int len = 0;
 195
 196         if (!asn1_id_decode(ctx, cls, con, tag))
 197                 return 0;
 198
 199         if (!asn1_length_decode(ctx, &def, &len))
 200                 return 0;
 201
 202         if (def)
 203                 *eoc = ctx->pointer + len;
 204         else
 205                 *eoc = NULL;
 206         return 1;
 207 }
 208
 209 static unsigned char
 210 asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
 211 {
 212         unsigned char ch;
 213
 214         if (eoc == NULL) {
 215                 if (!asn1_octet_decode(ctx, &ch))
 216                         return 0;
 217
 218                 if (ch != 0x00) {
 219                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 220                         return 0;
 221                 }
 222
 223                 if (!asn1_octet_decode(ctx, &ch))
 224                         return 0;
 225
 226                 if (ch != 0x00) {
 227                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 228                         return 0;
 229                 }
 230                 return 1;
 231         } else {
 232                 if (ctx->pointer != eoc) {
 233                         ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
 234                         return 0;
 235                 }
 236                 return 1;
 237         }
 238 }
 239
 240 /* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
 241                                       unsigned char *eoc)
 242 {
 243         ctx->pointer = eoc;
 244         return 1;
 245 }
 246
 247 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
 248                                       unsigned char *eoc, long *integer)
 249 {
 250         unsigned char ch;
 251         unsigned int len;
 252
 253         if (!asn1_octet_decode(ctx, &ch))
 254                 return 0;
 255
 256         *integer = (signed char) ch;
 257         len = 1;
 258
 259         while (ctx->pointer < eoc) {
 260                 if (++len > sizeof(long)) {
 261                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 262                         return 0;
 263                 }
 264
 265                 if (!asn1_octet_decode(ctx, &ch))
 266                         return 0;
 267
 268                 *integer <<= 8;
 269                 *integer |= ch;
 270         }
 271         return 1;
 272 }
 273
 274 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
 275                                       unsigned char *eoc,
 276                                       unsigned int *integer)
 277 {
 278         unsigned char ch;
 279         unsigned int len;
 280
 281         if (!asn1_octet_decode(ctx, &ch))
 282                 return 0;
 283
 284         *integer = ch;
 285         if (ch == 0)
 286                 len = 0;
 287         else
 288                 len = 1;
 289
 290         while (ctx->pointer < eoc) {
 291                 if (++len > sizeof(unsigned int)) {
 292                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 293                         return 0;
 294                 }
 295
 296                 if (!asn1_octet_decode(ctx, &ch))
 297                         return 0;
 298
 299                 *integer <<= 8;
 300                 *integer |= ch;
 301         }
 302         return 1;
 303 }
 304
 305 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
 306                                        unsigned char *eoc,
 307                                        unsigned long *integer)
 308 {
 309         unsigned char ch;
 310         unsigned int len;
 311
 312         if (!asn1_octet_decode(ctx, &ch))
 313                 return 0;
 314
 315         *integer = ch;
 316         if (ch == 0)
 317                 len = 0;
 318         else
 319                 len = 1;
 320
 321         while (ctx->pointer < eoc) {
 322                 if (++len > sizeof(unsigned long)) {
 323                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 324                         return 0;
 325                 }
 326
 327                 if (!asn1_octet_decode(ctx, &ch))
 328                         return 0;
 329
 330                 *integer <<= 8;
 331                 *integer |= ch;
 332         }
 333         return 1;
 334 }
 335
 336 static unsigned char
 337 asn1_octets_decode(struct asn1_ctx *ctx,
 338                    unsigned char *eoc,
 339                    unsigned char **octets, unsigned int *len)
 340 {
 341         unsigned char *ptr;
 342
 343         *len = 0;
 344
 345         *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
 346         if (*octets == NULL) {
 347                 return 0;
 348         }
 349
 350         ptr = *octets;
 351         while (ctx->pointer < eoc) {
 352                 if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
 353                         kfree(*octets);
 354                         *octets = NULL;
 355                         return 0;
 356                 }
 357                 (*len)++;
 358         }
 359         return 1;
 360 } */
 361
 362 static unsigned char
 363 asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
 364 {
 365         unsigned char ch;
 366
 367         *subid = 0;
 368
 369         do {
 370                 if (!asn1_octet_decode(ctx, &ch))
 371                         return 0;
 372
 373                 *subid <<= 7;
 374                 *subid |= ch & 0x7F;
 375         } while ((ch & 0x80) == 0x80);
 376         return 1;
 377 }
 378
 379 static int
 380 asn1_oid_decode(struct asn1_ctx *ctx,
 381                 unsigned char *eoc, unsigned long **oid, unsigned int *len)
 382 {
 383         unsigned long subid;
 384         unsigned int size;
 385         unsigned long *optr;
 386
 387         size = eoc - ctx->pointer + 1;
 388         *oid = kmalloc(size * sizeof (unsigned long), GFP_ATOMIC);
 389         if (*oid == NULL) {
 390                 return 0;
 391         }
 392
 393         optr = *oid;
 394
 395         if (!asn1_subid_decode(ctx, &subid)) {
 396                 kfree(*oid);
 397                 *oid = NULL;
 398                 return 0;
 399         }
 400
 401         if (subid < 40) {
 402                 optr[0] = 0;
 403                 optr[1] = subid;
 404         } else if (subid < 80) {
 405                 optr[0] = 1;
 406                 optr[1] = subid - 40;
 407         } else {
 408                 optr[0] = 2;
 409                 optr[1] = subid - 80;
 410         }
 411
 412         *len = 2;
 413         optr += 2;
 414
 415         while (ctx->pointer < eoc) {
 416                 if (++(*len) > size) {
 417                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 418                         kfree(*oid);
 419                         *oid = NULL;
 420                         return 0;
 421                 }
 422
 423                 if (!asn1_subid_decode(ctx, optr++)) {
 424                         kfree(*oid);
 425                         *oid = NULL;
 426                         return 0;
 427                 }
 428         }
 429         return 1;
 430 }
 431
 432 static int
 433 compare_oid(unsigned long *oid1, unsigned int oid1len,
 434             unsigned long *oid2, unsigned int oid2len)
 435 {
 436         unsigned int i;
 437
 438         if (oid1len != oid2len)
 439                 return 0;
 440         else {
 441                 for (i = 0; i < oid1len; i++) {
 442                         if (oid1[i] != oid2[i])
 443                                 return 0;
 444                 }
 445                 return 1;
 446         }
 447 }
 448
 449         /* BB check for endian conversion issues here */
 450
 451 int
 452 decode_negTokenInit(unsigned char *security_blob, int length,
 453                     enum securityEnum *secType)
 454 {
 455         struct asn1_ctx ctx;
 456         unsigned char *end;
 457         unsigned char *sequence_end;
 458         unsigned long *oid = NULL;
 459         unsigned int cls, con, tag, oidlen, rc;
 460         int use_ntlmssp = FALSE;
 461
 462         *secType = NTLM; /* BB eventually make Kerberos or NLTMSSP the default*/
 463
 464         /* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
 465
 466         asn1_open(&ctx, security_blob, length);
 467
 468         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 469                 cFYI(1, ("Error decoding negTokenInit header"));
 470                 return 0;
 471         } else if ((cls != ASN1_APL) || (con != ASN1_CON)
 472                    || (tag != ASN1_EOC)) {
 473                 cFYI(1, ("cls = %d con = %d tag = %d", cls, con, tag));
 474                 return 0;
 475         } else {
 476                 /*      remember to free obj->oid */
 477                 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 478                 if (rc) {
 479                         if ((tag == ASN1_OJI) && (cls == ASN1_PRI)) {
 480                                 rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
 481                                 if (rc) {
 482                                         rc = compare_oid(oid, oidlen,
 483                                                          SPNEGO_OID,
 484                                                          SPNEGO_OID_LEN);
 485                                         kfree(oid);
 486                                 }
 487                         } else
 488                                 rc = 0;
 489                 }
 490
 491                 if (!rc) {
 492                         cFYI(1, ("Error decoding negTokenInit header"));
 493                         return 0;
 494                 }
 495
 496                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 497                         cFYI(1, ("Error decoding negTokenInit"));
 498                         return 0;
 499                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 500                            || (tag != ASN1_EOC)) {
 501                         cFYI(1,
 502                              ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
 503                               cls, con, tag, end, *end));
 504                         return 0;
 505                 }
 506
 507                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 508                         cFYI(1, ("Error decoding negTokenInit"));
 509                         return 0;
 510                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 511                            || (tag != ASN1_SEQ)) {
 512                         cFYI(1,
 513                              ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
 514                               cls, con, tag, end, *end));
 515                         return 0;
 516                 }
 517
 518                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 519                         cFYI(1, ("Error decoding 2nd part of negTokenInit"));
 520                         return 0;
 521                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 522                            || (tag != ASN1_EOC)) {
 523                         cFYI(1,
 524                              ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
 525                               cls, con, tag, end, *end));
 526                         return 0;
 527                 }
 528
 529                 if (asn1_header_decode
 530                     (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
 531                         cFYI(1, ("Error decoding 2nd part of negTokenInit"));
 532                         return 0;
 533                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 534                            || (tag != ASN1_SEQ)) {
 535                         cFYI(1,
 536                              ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
 537                               cls, con, tag, end, *end));
 538                         return 0;
 539                 }
 540
 541                 while (!asn1_eoc_decode(&ctx, sequence_end)) {
 542                         rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 543                         if (!rc) {
 544                                 cFYI(1,
 545                                      ("Error decoding negTokenInit hdr exit2"));
 546                                 return 0;
 547                         }
 548                         if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
 549                                 rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
 550                                 if (rc) {
 551                                         cFYI(1,
 552                                           ("OID len = %d oid = 0x%lx 0x%lx "
 553                                            "0x%lx 0x%lx",
 554                                            oidlen, *oid, *(oid + 1),
 555                                            *(oid + 2), *(oid + 3)));
 556                                         rc = compare_oid(oid, oidlen,
 557                                                  NTLMSSP_OID, NTLMSSP_OID_LEN);
 558                                         kfree(oid);
 559                                         if (rc)
 560                                                 use_ntlmssp = TRUE;
 561                                 }
 562                         } else {
 563                                 cFYI(1, ("Should be an oid what is going on?"));
 564                         }
 565                 }
 566
 567                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 568                         cFYI(1,
 569                              ("Error decoding last part negTokenInit exit3"));
 570                         return 0;
 571                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
 572                         /* tag = 3 indicating mechListMIC */
 573                         cFYI(1,
 574                              ("Exit 4 cls = %d con = %d tag = %d end = %p (%d)",
 575                               cls, con, tag, end, *end));
 576                         return 0;
 577                 }
 578                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 579                         cFYI(1,
 580                              ("Error decoding last part negTokenInit exit5"));
 581                         return 0;
 582                 } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 583                            || (tag != ASN1_SEQ)) {
 584                         cFYI(1,
 585                              ("Exit 6 cls = %d con = %d tag = %d end = %p (%d)",
 586                               cls, con, tag, end, *end));
 587                 }
 588
 589                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 590                         cFYI(1,
 591                              ("Error decoding last part negTokenInit exit 7"));
 592                         return 0;
 593                 } else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
 594                         cFYI(1,
 595                              ("Exit 8 cls = %d con = %d tag = %d end = %p (%d)",
 596                               cls, con, tag, end, *end));
 597                         return 0;
 598                 }
 599                 if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 600                         cFYI(1,
 601                              ("Error decoding last part negTokenInit exit9"));
 602                         return 0;
 603                 } else if ((cls != ASN1_UNI) || (con != ASN1_PRI)
 604                            || (tag != ASN1_GENSTR)) {
 605                         cFYI(1,
 606                              ("Exit10 cls = %d con = %d tag = %d end = %p (%d)",
 607                               cls, con, tag, end, *end));
 608                         return 0;
 609                 }
 610                 cFYI(1, ("Need to call asn1_octets_decode() function for %s",
 611                          ctx.pointer)); /* is this UTF-8 or ASCII? */
 612         }
 613
 614         /* if (use_kerberos)
 615            *secType = Kerberos
 616            else */
 617         if (use_ntlmssp) {
 618                 *secType = NTLMSSP;
 619         }
 620
 621         return 1;
 622 }