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_ENUM       10      /* Enumerated */
  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 #define KRB5_OID_LEN  7
  82 #define KRB5U2U_OID_LEN  8
  83 #define MSKRB5_OID_LEN  7
  84 static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
  85 static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
  86 static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
  87 static unsigned long KRB5U2U_OID[8] = { 1, 2, 840, 113554, 1, 2, 2, 3 };
  88 static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };
  89
  90 /*
  91  * ASN.1 context.
  92  */
  93 struct asn1_ctx {
  94         int error;              /* Error condition */
  95         unsigned char *pointer; /* Octet just to be decoded */
  96         unsigned char *begin;   /* First octet */
  97         unsigned char *end;     /* Octet after last octet */
  98 };
  99
 100 /*
 101  * Octet string (not null terminated)
 102  */
 103 struct asn1_octstr {
 104         unsigned char *data;
 105         unsigned int len;
 106 };
 107
 108 static void
 109 asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
 110 {
 111         ctx->begin = buf;
 112         ctx->end = buf + len;
 113         ctx->pointer = buf;
 114         ctx->error = ASN1_ERR_NOERROR;
 115 }
 116
 117 static unsigned char
 118 asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
 119 {
 120         if (ctx->pointer >= ctx->end) {
 121                 ctx->error = ASN1_ERR_DEC_EMPTY;
 122                 return 0;
 123         }
 124         *ch = *(ctx->pointer)++;
 125         return 1;
 126 }
 127
 128 #if 0 /* will be needed later by spnego decoding/encoding of ntlmssp */
 129 static unsigned char
 130 asn1_enum_decode(struct asn1_ctx *ctx, __le32 *val)
 131 {
 132         unsigned char ch;
 133
 134         if (ctx->pointer >= ctx->end) {
 135                 ctx->error = ASN1_ERR_DEC_EMPTY;
 136                 return 0;
 137         }
 138
 139         ch = *(ctx->pointer)++; /* ch has 0xa, ptr points to length octet */
 140         if ((ch) == ASN1_ENUM)  /* if ch value is ENUM, 0xa */
 141                 *val = *(++(ctx->pointer)); /* value has enum value */
 142         else
 143                 return 0;
 144
 145         ctx->pointer++;
 146         return 1;
 147 }
 148 #endif
 149
 150 static unsigned char
 151 asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
 152 {
 153         unsigned char ch;
 154
 155         *tag = 0;
 156
 157         do {
 158                 if (!asn1_octet_decode(ctx, &ch))
 159                         return 0;
 160                 *tag <<= 7;
 161                 *tag |= ch & 0x7F;
 162         } while ((ch & 0x80) == 0x80);
 163         return 1;
 164 }
 165
 166 static unsigned char
 167 asn1_id_decode(struct asn1_ctx *ctx,
 168                unsigned int *cls, unsigned int *con, unsigned int *tag)
 169 {
 170         unsigned char ch;
 171
 172         if (!asn1_octet_decode(ctx, &ch))
 173                 return 0;
 174
 175         *cls = (ch & 0xC0) >> 6;
 176         *con = (ch & 0x20) >> 5;
 177         *tag = (ch & 0x1F);
 178
 179         if (*tag == 0x1F) {
 180                 if (!asn1_tag_decode(ctx, tag))
 181                         return 0;
 182         }
 183         return 1;
 184 }
 185
 186 static unsigned char
 187 asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
 188 {
 189         unsigned char ch, cnt;
 190
 191         if (!asn1_octet_decode(ctx, &ch))
 192                 return 0;
 193
 194         if (ch == 0x80)
 195                 *def = 0;
 196         else {
 197                 *def = 1;
 198
 199                 if (ch < 0x80)
 200                         *len = ch;
 201                 else {
 202                         cnt = (unsigned char) (ch & 0x7F);
 203                         *len = 0;
 204
 205                         while (cnt > 0) {
 206                                 if (!asn1_octet_decode(ctx, &ch))
 207                                         return 0;
 208                                 *len <<= 8;
 209                                 *len |= ch;
 210                                 cnt--;
 211                         }
 212                 }
 213         }
 214
 215         /* don't trust len bigger than ctx buffer */
 216         if (*len > ctx->end - ctx->pointer)
 217                 return 0;
 218
 219         return 1;
 220 }
 221
 222 static unsigned char
 223 asn1_header_decode(struct asn1_ctx *ctx,
 224                    unsigned char **eoc,
 225                    unsigned int *cls, unsigned int *con, unsigned int *tag)
 226 {
 227         unsigned int def = 0;
 228         unsigned int len = 0;
 229
 230         if (!asn1_id_decode(ctx, cls, con, tag))
 231                 return 0;
 232
 233         if (!asn1_length_decode(ctx, &def, &len))
 234                 return 0;
 235
 236         /* primitive shall be definite, indefinite shall be constructed */
 237         if (*con == ASN1_PRI && !def)
 238                 return 0;
 239
 240         if (def)
 241                 *eoc = ctx->pointer + len;
 242         else
 243                 *eoc = NULL;
 244         return 1;
 245 }
 246
 247 static unsigned char
 248 asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
 249 {
 250         unsigned char ch;
 251
 252         if (eoc == NULL) {
 253                 if (!asn1_octet_decode(ctx, &ch))
 254                         return 0;
 255
 256                 if (ch != 0x00) {
 257                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 258                         return 0;
 259                 }
 260
 261                 if (!asn1_octet_decode(ctx, &ch))
 262                         return 0;
 263
 264                 if (ch != 0x00) {
 265                         ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
 266                         return 0;
 267                 }
 268                 return 1;
 269         } else {
 270                 if (ctx->pointer != eoc) {
 271                         ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
 272                         return 0;
 273                 }
 274                 return 1;
 275         }
 276 }
 277
 278 /* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
 279                                       unsigned char *eoc)
 280 {
 281         ctx->pointer = eoc;
 282         return 1;
 283 }
 284
 285 static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
 286                                       unsigned char *eoc, long *integer)
 287 {
 288         unsigned char ch;
 289         unsigned int len;
 290
 291         if (!asn1_octet_decode(ctx, &ch))
 292                 return 0;
 293
 294         *integer = (signed char) ch;
 295         len = 1;
 296
 297         while (ctx->pointer < eoc) {
 298                 if (++len > sizeof(long)) {
 299                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 300                         return 0;
 301                 }
 302
 303                 if (!asn1_octet_decode(ctx, &ch))
 304                         return 0;
 305
 306                 *integer <<= 8;
 307                 *integer |= ch;
 308         }
 309         return 1;
 310 }
 311
 312 static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
 313                                       unsigned char *eoc,
 314                                       unsigned int *integer)
 315 {
 316         unsigned char ch;
 317         unsigned int len;
 318
 319         if (!asn1_octet_decode(ctx, &ch))
 320                 return 0;
 321
 322         *integer = ch;
 323         if (ch == 0)
 324                 len = 0;
 325         else
 326                 len = 1;
 327
 328         while (ctx->pointer < eoc) {
 329                 if (++len > sizeof(unsigned int)) {
 330                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 331                         return 0;
 332                 }
 333
 334                 if (!asn1_octet_decode(ctx, &ch))
 335                         return 0;
 336
 337                 *integer <<= 8;
 338                 *integer |= ch;
 339         }
 340         return 1;
 341 }
 342
 343 static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
 344                                        unsigned char *eoc,
 345                                        unsigned long *integer)
 346 {
 347         unsigned char ch;
 348         unsigned int len;
 349
 350         if (!asn1_octet_decode(ctx, &ch))
 351                 return 0;
 352
 353         *integer = ch;
 354         if (ch == 0)
 355                 len = 0;
 356         else
 357                 len = 1;
 358
 359         while (ctx->pointer < eoc) {
 360                 if (++len > sizeof(unsigned long)) {
 361                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 362                         return 0;
 363                 }
 364
 365                 if (!asn1_octet_decode(ctx, &ch))
 366                         return 0;
 367
 368                 *integer <<= 8;
 369                 *integer |= ch;
 370         }
 371         return 1;
 372 }
 373
 374 static unsigned char
 375 asn1_octets_decode(struct asn1_ctx *ctx,
 376                    unsigned char *eoc,
 377                    unsigned char **octets, unsigned int *len)
 378 {
 379         unsigned char *ptr;
 380
 381         *len = 0;
 382
 383         *octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
 384         if (*octets == NULL) {
 385                 return 0;
 386         }
 387
 388         ptr = *octets;
 389         while (ctx->pointer < eoc) {
 390                 if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
 391                         kfree(*octets);
 392                         *octets = NULL;
 393                         return 0;
 394                 }
 395                 (*len)++;
 396         }
 397         return 1;
 398 } */
 399
 400 static unsigned char
 401 asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
 402 {
 403         unsigned char ch;
 404
 405         *subid = 0;
 406
 407         do {
 408                 if (!asn1_octet_decode(ctx, &ch))
 409                         return 0;
 410
 411                 *subid <<= 7;
 412                 *subid |= ch & 0x7F;
 413         } while ((ch & 0x80) == 0x80);
 414         return 1;
 415 }
 416
 417 static int
 418 asn1_oid_decode(struct asn1_ctx *ctx,
 419                 unsigned char *eoc, unsigned long **oid, unsigned int *len)
 420 {
 421         unsigned long subid;
 422         unsigned int size;
 423         unsigned long *optr;
 424
 425         size = eoc - ctx->pointer + 1;
 426
 427         /* first subid actually encodes first two subids */
 428         if (size < 2 || size > UINT_MAX/sizeof(unsigned long))
 429                 return 0;
 430
 431         *oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
 432         if (*oid == NULL)
 433                 return 0;
 434
 435         optr = *oid;
 436
 437         if (!asn1_subid_decode(ctx, &subid)) {
 438                 kfree(*oid);
 439                 *oid = NULL;
 440                 return 0;
 441         }
 442
 443         if (subid < 40) {
 444                 optr[0] = 0;
 445                 optr[1] = subid;
 446         } else if (subid < 80) {
 447                 optr[0] = 1;
 448                 optr[1] = subid - 40;
 449         } else {
 450                 optr[0] = 2;
 451                 optr[1] = subid - 80;
 452         }
 453
 454         *len = 2;
 455         optr += 2;
 456
 457         while (ctx->pointer < eoc) {
 458                 if (++(*len) > size) {
 459                         ctx->error = ASN1_ERR_DEC_BADVALUE;
 460                         kfree(*oid);
 461                         *oid = NULL;
 462                         return 0;
 463                 }
 464
 465                 if (!asn1_subid_decode(ctx, optr++)) {
 466                         kfree(*oid);
 467                         *oid = NULL;
 468                         return 0;
 469                 }
 470         }
 471         return 1;
 472 }
 473
 474 static int
 475 compare_oid(unsigned long *oid1, unsigned int oid1len,
 476             unsigned long *oid2, unsigned int oid2len)
 477 {
 478         unsigned int i;
 479
 480         if (oid1len != oid2len)
 481                 return 0;
 482         else {
 483                 for (i = 0; i < oid1len; i++) {
 484                         if (oid1[i] != oid2[i])
 485                                 return 0;
 486                 }
 487                 return 1;
 488         }
 489 }
 490
 491         /* BB check for endian conversion issues here */
 492
 493 int
 494 decode_negTokenInit(unsigned char *security_blob, int length,
 495                     struct TCP_Server_Info *server)
 496 {
 497         struct asn1_ctx ctx;
 498         unsigned char *end;
 499         unsigned char *sequence_end;
 500         unsigned long *oid = NULL;
 501         unsigned int cls, con, tag, oidlen, rc;
 502
 503         /* cifs_dump_mem(" Received SecBlob ", security_blob, length); */
 504
 505         asn1_open(&ctx, security_blob, length);
 506
 507         /* GSSAPI header */
 508         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 509                 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
 510                 return 0;
 511         } else if ((cls != ASN1_APL) || (con != ASN1_CON)
 512                    || (tag != ASN1_EOC)) {
 513                 cifs_dbg(FYI, "cls = %d con = %d tag = %d\n", cls, con, tag);
 514                 return 0;
 515         }
 516
 517         /* Check for SPNEGO OID -- remember to free obj->oid */
 518         rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 519         if (rc) {
 520                 if ((tag == ASN1_OJI) && (con == ASN1_PRI) &&
 521                     (cls == ASN1_UNI)) {
 522                         rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
 523                         if (rc) {
 524                                 rc = compare_oid(oid, oidlen, SPNEGO_OID,
 525                                                  SPNEGO_OID_LEN);
 526                                 kfree(oid);
 527                         }
 528                 } else
 529                         rc = 0;
 530         }
 531
 532         /* SPNEGO OID not present or garbled -- bail out */
 533         if (!rc) {
 534                 cifs_dbg(FYI, "Error decoding negTokenInit header\n");
 535                 return 0;
 536         }
 537
 538         /* SPNEGO */
 539         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 540                 cifs_dbg(FYI, "Error decoding negTokenInit\n");
 541                 return 0;
 542         } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 543                    || (tag != ASN1_EOC)) {
 544                 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 0\n",
 545                          cls, con, tag, end, *end);
 546                 return 0;
 547         }
 548
 549         /* negTokenInit */
 550         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 551                 cifs_dbg(FYI, "Error decoding negTokenInit\n");
 552                 return 0;
 553         } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 554                    || (tag != ASN1_SEQ)) {
 555                 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 1\n",
 556                          cls, con, tag, end, *end);
 557                 return 0;
 558         }
 559
 560         /* sequence */
 561         if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
 562                 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
 563                 return 0;
 564         } else if ((cls != ASN1_CTX) || (con != ASN1_CON)
 565                    || (tag != ASN1_EOC)) {
 566                 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 0\n",
 567                          cls, con, tag, end, *end);
 568                 return 0;
 569         }
 570
 571         /* sequence of */
 572         if (asn1_header_decode
 573             (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
 574                 cifs_dbg(FYI, "Error decoding 2nd part of negTokenInit\n");
 575                 return 0;
 576         } else if ((cls != ASN1_UNI) || (con != ASN1_CON)
 577                    || (tag != ASN1_SEQ)) {
 578                 cifs_dbg(FYI, "cls = %d con = %d tag = %d end = %p (%d) exit 1\n",
 579                          cls, con, tag, end, *end);
 580                 return 0;
 581         }
 582
 583         /* list of security mechanisms */
 584         while (!asn1_eoc_decode(&ctx, sequence_end)) {
 585                 rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
 586                 if (!rc) {
 587                         cifs_dbg(FYI, "Error decoding negTokenInit hdr exit2\n");
 588                         return 0;
 589                 }
 590                 if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
 591                         if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {
 592
 593                                 cifs_dbg(FYI, "OID len = %d oid = 0x%lx 0x%lx 0x%lx 0x%lx\n",
 594                                          oidlen, *oid, *(oid + 1), *(oid + 2),
 595                                          *(oid + 3));
 596
 597                                 if (compare_oid(oid, oidlen, MSKRB5_OID,
 598                                                 MSKRB5_OID_LEN))
 599                                         server->sec_mskerberos = true;
 600                                 else if (compare_oid(oid, oidlen, KRB5U2U_OID,
 601                                                      KRB5U2U_OID_LEN))
 602                                         server->sec_kerberosu2u = true;
 603                                 else if (compare_oid(oid, oidlen, KRB5_OID,
 604                                                      KRB5_OID_LEN))
 605                                         server->sec_kerberos = true;
 606                                 else if (compare_oid(oid, oidlen, NTLMSSP_OID,
 607                                                      NTLMSSP_OID_LEN))
 608                                         server->sec_ntlmssp = true;
 609
 610                                 kfree(oid);
 611                         }
 612                 } else {
 613                         cifs_dbg(FYI, "Should be an oid what is going on?\n");
 614                 }
 615         }
 616
 617         /*
 618          * We currently ignore anything at the end of the SPNEGO blob after
 619          * the mechTypes have been parsed, since none of that info is
 620          * used at the moment.
 621          */
 622         return 1;
 623 }