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