libcli/auth/msrpc_parse.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    simple kerberos5/SPNEGO routines
   4    Copyright (C) Andrew Tridgell 2001
   5    Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2002
   6    Copyright (C) Andrew Bartlett 2002-2003
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "libcli/auth/msrpc_parse.h"
  24
  25 /*
  26   this is a tiny msrpc packet generator. I am only using this to
  27   avoid tying this code to a particular varient of our rpc code. This
  28   generator is not general enough for all our rpc needs, its just
  29   enough for the spnego/ntlmssp code
  30
  31   format specifiers are:
  32
  33   U = unicode string (input is unix string)
  34   a = address (input is char *unix_string)
  35       (1 byte type, 1 byte length, unicode/ASCII string, all inline)
  36   A = ASCII string (input is unix string)
  37   B = data blob (pointer + length)
  38   b = data blob in header (pointer + length)
  39   D
  40   d = word (4 bytes)
  41   C = constant ascii string
  42  */
  43 bool msrpc_gen(TALLOC_CTX *mem_ctx,
  44                DATA_BLOB *blob,
  45                const char *format, ...)
  46 {
  47         int i, j;
  48         bool ret;
  49         va_list ap;
  50         char *s;
  51         uint8_t *b;
  52         int head_size=0, data_size=0;
  53         int head_ofs, data_ofs;
  54         int *intargs;
  55         size_t n;
  56
  57         DATA_BLOB *pointers;
  58
  59         pointers = talloc_array(mem_ctx, DATA_BLOB, strlen(format));
  60         intargs = talloc_array(pointers, int, strlen(format));
  61
  62         /* first scan the format to work out the header and body size */
  63         va_start(ap, format);
  64         for (i=0; format[i]; i++) {
  65                 switch (format[i]) {
  66                 case 'U':
  67                         s = va_arg(ap, char *);
  68                         head_size += 8;
  69                         ret = push_ucs2_talloc(
  70                                 pointers,
  71                                 (smb_ucs2_t **)(void *)&pointers[i].data,
  72                                 s, &n);
  73                         if (!ret) {
  74                                 return false;
  75                         }
  76                         pointers[i].length = n;
  77                         pointers[i].length -= 2;
  78                         data_size += pointers[i].length;
  79                         break;
  80                 case 'A':
  81                         s = va_arg(ap, char *);
  82                         head_size += 8;
  83                         ret = push_ascii_talloc(
  84                                 pointers, (char **)(void *)&pointers[i].data,
  85                                 s, &n);
  86                         if (!ret) {
  87                                 return false;
  88                         }
  89                         pointers[i].length = n;
  90                         pointers[i].length -= 1;
  91                         data_size += pointers[i].length;
  92                         break;
  93                 case 'a':
  94                         j = va_arg(ap, int);
  95                         intargs[i] = j;
  96                         s = va_arg(ap, char *);
  97                         ret = push_ucs2_talloc(
  98                                 pointers,
  99                                 (smb_ucs2_t **)(void *)&pointers[i].data,
 100                                 s, &n);
 101                         if (!ret) {
 102                                 return false;
 103                         }
 104                         pointers[i].length = n;
 105                         pointers[i].length -= 2;
 106                         data_size += pointers[i].length + 4;
 107                         break;
 108                 case 'B':
 109                         b = va_arg(ap, uint8_t *);
 110                         head_size += 8;
 111                         pointers[i].data = b;
 112                         pointers[i].length = va_arg(ap, int);
 113                         data_size += pointers[i].length;
 114                         break;
 115                 case 'b':
 116                         b = va_arg(ap, uint8_t *);
 117                         pointers[i].data = b;
 118                         pointers[i].length = va_arg(ap, int);
 119                         head_size += pointers[i].length;
 120                         break;
 121                 case 'd':
 122                         j = va_arg(ap, int);
 123                         intargs[i] = j;
 124                         head_size += 4;
 125                         break;
 126                 case 'C':
 127                         s = va_arg(ap, char *);
 128                         pointers[i].data = (uint8_t *)s;
 129                         pointers[i].length = strlen(s)+1;
 130                         head_size += pointers[i].length;
 131                         break;
 132                 }
 133         }
 134         va_end(ap);
 135
 136         /* allocate the space, then scan the format again to fill in the values */
 137         *blob = data_blob_talloc(mem_ctx, NULL, head_size + data_size);
 138
 139         head_ofs = 0;
 140         data_ofs = head_size;
 141
 142         va_start(ap, format);
 143         for (i=0; format[i]; i++) {
 144                 switch (format[i]) {
 145                 case 'U':
 146                 case 'A':
 147                 case 'B':
 148                         n = pointers[i].length;
 149                         SSVAL(blob->data, head_ofs, n); head_ofs += 2;
 150                         SSVAL(blob->data, head_ofs, n); head_ofs += 2;
 151                         SIVAL(blob->data, head_ofs, data_ofs); head_ofs += 4;
 152                         if (pointers[i].data && n) /* don't follow null pointers... */
 153                                 memcpy(blob->data+data_ofs, pointers[i].data, n);
 154                         data_ofs += n;
 155                         break;
 156                 case 'a':
 157                         j = intargs[i];
 158                         SSVAL(blob->data, data_ofs, j); data_ofs += 2;
 159
 160                         n = pointers[i].length;
 161                         SSVAL(blob->data, data_ofs, n); data_ofs += 2;
 162                         if (n >= 0) {
 163                                 memcpy(blob->data+data_ofs, pointers[i].data, n);
 164                         }
 165                         data_ofs += n;
 166                         break;
 167                 case 'd':
 168                         j = intargs[i];
 169                         SIVAL(blob->data, head_ofs, j);
 170                         head_ofs += 4;
 171                         break;
 172                 case 'b':
 173                         n = pointers[i].length;
 174                         memcpy(blob->data + head_ofs, pointers[i].data, n);
 175                         head_ofs += n;
 176                         break;
 177                 case 'C':
 178                         n = pointers[i].length;
 179                         memcpy(blob->data + head_ofs, pointers[i].data, n);
 180                         head_ofs += n;
 181                         break;
 182                 }
 183         }
 184         va_end(ap);
 185
 186         talloc_free(pointers);
 187
 188         return true;
 189 }
 190
 191
 192 /* a helpful macro to avoid running over the end of our blob */
 193 #define NEED_DATA(amount) \
 194 if ((head_ofs + amount) > blob->length) { \
 195         return false; \
 196 }
 197
 198 /**
 199   this is a tiny msrpc packet parser. This the the partner of msrpc_gen
 200
 201   format specifiers are:
 202
 203   U = unicode string (output is unix string)
 204   A = ascii string
 205   B = data blob
 206   b = data blob in header
 207   d = word (4 bytes)
 208   C = constant ascii string
 209  */
 210
 211 bool msrpc_parse(TALLOC_CTX *mem_ctx,
 212                  const DATA_BLOB *blob,
 213                  const char *format, ...)
 214 {
 215         int i;
 216         va_list ap;
 217         char **ps, *s;
 218         DATA_BLOB *b;
 219         size_t head_ofs = 0;
 220         uint16_t len1, len2;
 221         uint32_t ptr;
 222         uint32_t *v;
 223         size_t p_len = 1024;
 224         char *p = talloc_array(mem_ctx, char, p_len);
 225         bool ret = true;
 226
 227         va_start(ap, format);
 228         for (i=0; format[i]; i++) {
 229                 switch (format[i]) {
 230                 case 'U':
 231                         NEED_DATA(8);
 232                         len1 = SVAL(blob->data, head_ofs); head_ofs += 2;
 233                         len2 = SVAL(blob->data, head_ofs); head_ofs += 2;
 234                         ptr =  IVAL(blob->data, head_ofs); head_ofs += 4;
 235
 236                         ps = va_arg(ap, char **);
 237                         if (len1 == 0 && len2 == 0) {
 238                                 *ps = (char *)discard_const("");
 239                         } else {
 240                                 /* make sure its in the right format - be strict */
 241                                 if ((len1 != len2) || (ptr + len1 < ptr) || (ptr + len1 < len1) || (ptr + len1 > blob->length)) {
 242                                         ret = false;
 243                                         goto cleanup;
 244                                 }
 245                                 if (len1 & 1) {
 246                                         /* if odd length and unicode */
 247                                         ret = false;
 248                                         goto cleanup;
 249                                 }
 250                                 if (blob->data + ptr < (uint8_t *)(uintptr_t)ptr ||
 251                                                 blob->data + ptr < blob->data) {
 252                                         ret = false;
 253                                         goto cleanup;
 254                                 }
 255
 256                                 if (0 < len1) {
 257                                         size_t pull_len;
 258                                         if (!convert_string_talloc(mem_ctx, CH_UTF16, CH_UNIX,
 259                                                                    blob->data + ptr, len1,
 260                                                                    ps, &pull_len, false)) {
 261                                                 ret = false;
 262                                                 goto cleanup;
 263                                         }
 264                                 } else {
 265                                         (*ps) = (char *)discard_const("");
 266                                 }
 267                         }
 268                         break;
 269                 case 'A':
 270                         NEED_DATA(8);
 271                         len1 = SVAL(blob->data, head_ofs); head_ofs += 2;
 272                         len2 = SVAL(blob->data, head_ofs); head_ofs += 2;
 273                         ptr =  IVAL(blob->data, head_ofs); head_ofs += 4;
 274
 275                         ps = (char **)va_arg(ap, char **);
 276                         /* make sure its in the right format - be strict */
 277                         if (len1 == 0 && len2 == 0) {
 278                                 *ps = (char *)discard_const("");
 279                         } else {
 280                                 if ((len1 != len2) || (ptr + len1 < ptr) || (ptr + len1 < len1) || (ptr + len1 > blob->length)) {
 281                                         ret = false;
 282                                         goto cleanup;
 283                                 }
 284
 285                                 if (blob->data + ptr < (uint8_t *)(uintptr_t)ptr ||
 286                                                 blob->data + ptr < blob->data) {
 287                                         ret = false;
 288                                         goto cleanup;
 289                                 }
 290
 291                                 if (0 < len1) {
 292                                         size_t pull_len;
 293
 294                                         if (!convert_string_talloc(mem_ctx, CH_DOS, CH_UNIX,
 295                                                                    blob->data + ptr, len1,
 296                                                                    ps, &pull_len, false)) {
 297                                                 ret = false;
 298                                                 goto cleanup;
 299                                         }
 300                                 } else {
 301                                         (*ps) = (char *)discard_const("");
 302                                 }
 303                         }
 304                         break;
 305                 case 'B':
 306                         NEED_DATA(8);
 307                         len1 = SVAL(blob->data, head_ofs); head_ofs += 2;
 308                         len2 = SVAL(blob->data, head_ofs); head_ofs += 2;
 309                         ptr =  IVAL(blob->data, head_ofs); head_ofs += 4;
 310
 311                         b = (DATA_BLOB *)va_arg(ap, void *);
 312                         if (len1 == 0 && len2 == 0) {
 313                                 *b = data_blob_talloc(mem_ctx, NULL, 0);
 314                         } else {
 315                                 /* make sure its in the right format - be strict */
 316                                 if ((len1 != len2) || (ptr + len1 < ptr) || (ptr + len1 < len1) || (ptr + len1 > blob->length)) {
 317                                         ret = false;
 318                                         goto cleanup;
 319                                 }
 320
 321                                 if (blob->data + ptr < (uint8_t *)(uintptr_t)ptr ||
 322                                                 blob->data + ptr < blob->data) {
 323                                         ret = false;
 324                                         goto cleanup;
 325                                 }
 326
 327                                 *b = data_blob_talloc(mem_ctx, blob->data + ptr, len1);
 328                         }
 329                         break;
 330                 case 'b':
 331                         b = (DATA_BLOB *)va_arg(ap, void *);
 332                         len1 = va_arg(ap, uint_t);
 333                         /* make sure its in the right format - be strict */
 334                         NEED_DATA(len1);
 335                         if (blob->data + head_ofs < (uint8_t *)head_ofs ||
 336                                         blob->data + head_ofs < blob->data) {
 337                                 ret = false;
 338                                 goto cleanup;
 339                         }
 340
 341                         *b = data_blob_talloc(mem_ctx, blob->data + head_ofs, len1);
 342                         head_ofs += len1;
 343                         break;
 344                 case 'd':
 345                         v = va_arg(ap, uint32_t *);
 346                         NEED_DATA(4);
 347                         *v = IVAL(blob->data, head_ofs); head_ofs += 4;
 348                         break;
 349                 case 'C':
 350                         s = va_arg(ap, char *);
 351
 352                         if (blob->data + head_ofs < (uint8_t *)head_ofs ||
 353                                         blob->data + head_ofs < blob->data ||
 354                             (head_ofs + (strlen(s) + 1)) > blob->length) {
 355                                 ret = false;
 356                                 goto cleanup;
 357                         }
 358
 359                         if (memcmp(blob->data + head_ofs, s, strlen(s)+1) != 0) {
 360                                 ret = false;
 361                                 goto cleanup;
 362                         }
 363                         head_ofs += (strlen(s) + 1);
 364
 365                         break;
 366                 }
 367         }
 368
 369 cleanup:
 370         va_end(ap);
 371         talloc_free(p);
 372         return ret;
 373 }