parsekey.c

   1 /*
   2  * parsekey.c - Routines to parse an OpenPGP key.
   3  *
   4  * Copyright 2002-2004,2007-2008,2011 Jonathan McDowell <noodles@earth.li>
   5  *
   6  * This program is free software: you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; version 2 of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  13  * more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along with
  16  * this program.  If not, see <https://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <stdbool.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23
  24 #include "keystructs.h"
  25 #include "ll.h"
  26 #include "mem.h"
  27 #include "onak.h"
  28 #include "openpgp.h"
  29 #include "parsekey.h"
  30
  31 /**
  32  *      parse_keys - Process a stream of packets for public keys + sigs.
  33  *      @packets: The packet list to parse.
  34  *      @keys: The returned list of public keys.
  35  *
  36  *      This function takes an list of OpenPGP packets and attempts to parse it
  37  *      into a list of public keys with signatures and subkeys.
  38  *
  39  *      Returns a count of how many keys we parsed.
  40  */
  41 int parse_keys(struct openpgp_packet_list *packets,
  42                 struct openpgp_publickey **keys)
  43 {
  44         struct openpgp_publickey *curkey = NULL;
  45         int count;
  46
  47         count = 0;
  48
  49         /*
  50          * If keys already has some keys in it then set curkey to the last one
  51          * so we add to the end of the list.
  52          */
  53         for (curkey = *keys; curkey != NULL && curkey->next != NULL;
  54                         curkey = curkey->next) ;
  55
  56         while (packets != NULL) {
  57                 switch (packets->packet->tag) {
  58                 case OPENPGP_PACKET_SIGNATURE:
  59                         /*
  60                          * It's a signature packet. Add it to either the public
  61                          * key, to the current UID or the current subkey.
  62                          */
  63                         if (curkey == NULL)
  64                                 return ONAK_E_INVALID_PARAM;
  65                         if (curkey->subkeys != NULL) {
  66                                 ADD_PACKET_TO_LIST_END(curkey->last_subkey,
  67                                         sig,
  68                                         packet_dup(packets->packet));
  69                         } else if (curkey->uids != NULL) {
  70                                 ADD_PACKET_TO_LIST_END(curkey->last_uid,
  71                                         sig,
  72                                         packet_dup(packets->packet));
  73                         } else {
  74                                 ADD_PACKET_TO_LIST_END(curkey,
  75                                         sig,
  76                                         packet_dup(packets->packet));
  77                                 /*
  78                                  * This is a signature on the public key; check
  79                                  * if it's a revocation.
  80                                  */
  81                                 if (packets->packet->data[0] == 3 &&
  82                                         packets->packet->data[2] ==
  83                                                 OPENPGP_SIGTYPE_KEY_REV) {
  84                                         /*
  85                                          * Type 3 key, 0x20 == revocation
  86                                          */
  87                                         curkey->revoked = true;
  88                                 } else if (packets->packet->data[0] == 4 &&
  89                                         packets->packet->data[1] ==
  90                                                 OPENPGP_SIGTYPE_KEY_REV) {
  91                                         /*
  92                                          * Type 4 key, 0x20 == revocation
  93                                          */
  94                                         curkey->revoked = true;
  95                                 }
  96                         }
  97                         break;
  98                 case OPENPGP_PACKET_PUBLICKEY:
  99                         /*
 100                          * It's a public key packet, so start a new key in our
 101                          * list.
 102                          */
 103                         if (curkey != NULL) {
 104                                 curkey->next = malloc(sizeof (*curkey));
 105                                 curkey = curkey->next;
 106                         } else {
 107                                 *keys = curkey =
 108                                         malloc(sizeof (*curkey));
 109                         }
 110                         memset(curkey, 0, sizeof(*curkey));
 111                         curkey->publickey = packet_dup(packets->packet);
 112                         count++;
 113                         break;
 114                 case OPENPGP_PACKET_UID:
 115                 case OPENPGP_PACKET_UAT:
 116                         /*
 117                          * It's a UID packet (or a photo id, which is similar).
 118                          */
 119                         if (curkey == NULL)
 120                                 return ONAK_E_INVALID_PARAM;
 121                         if (curkey->subkeys != NULL)
 122                                 return ONAK_E_INVALID_PARAM;
 123                         ADD_PACKET_TO_LIST_END(curkey,
 124                                 uid,
 125                                 packet_dup(packets->packet));
 126                         break;
 127                 case OPENPGP_PACKET_PUBLICSUBKEY:
 128                         /*
 129                          * It's a subkey packet.
 130                          */
 131                         if (curkey == NULL)
 132                                 return ONAK_E_INVALID_PARAM;
 133                         ADD_PACKET_TO_LIST_END(curkey,
 134                                 subkey,
 135                                 packet_dup(packets->packet));
 136                         break;
 137                 case OPENPGP_PACKET_TRUST:
 138                 case OPENPGP_PACKET_COMMENT:
 139                         /*
 140                          * One of:
 141                          *
 142                          * Trust packet. Ignore.
 143                          * Comment packet. Ignore.
 144                          */
 145                         break;
 146                 default:
 147                         /* Unsupported packet. Do what? Ignore for now. */
 148                         break;
 149                 }
 150                 packets = packets->next;
 151         }
 152
 153         return count;
 154 }
 155
 156 /**
 157  *      debug_packet - Print debug info about a packet
 158  *      @packet: The packet to display.
 159  *
 160  *      This function takes an OpenPGP packet and displays some information
 161  *      about it to stdout. Useful for debugging purposes or curiousity about
 162  *      an OpenPGP packet stream.
 163  */
 164 int debug_packet(struct openpgp_packet *packet)
 165 {
 166         printf("\tNew format: %d, Tag: %u, Length: %zd\n",
 167                         packet->newformat,
 168                         packet->tag,
 169                         packet->length);
 170
 171         return 0;
 172 }
 173
 174 /**
 175  *      read_openpgp_stream - Reads a stream of OpenPGP packets.
 176  *      @getchar_func: The function to get the next character from the stream.
 177  *      @ctx: A pointer to the context structure for getchar_func.
 178  *      @packets: The outputted list of packets.
 179  *      @maxnum: The maximum number of keys to read. 0 means unlimited.
 180  *
 181  *      This function uses getchar_func to read characters from an OpenPGP
 182  *      packet stream and reads the packets into a linked list of packets
 183  *      ready for parsing as a public key or whatever.
 184  */
 185 onak_status_t read_openpgp_stream(int (*getchar_func)(void *ctx, size_t count,
 186                                 void *c),
 187                                 void *ctx,
 188                                 struct openpgp_packet_list **packets,
 189                                 int maxnum)
 190 {
 191         unsigned char                    curchar = 0;
 192         struct openpgp_packet_list      *curpacket = NULL, **packetend = NULL;
 193         onak_status_t                    rc = ONAK_E_OK;
 194         int                              keys = 0;
 195
 196         if (packets == NULL)
 197                 return ONAK_E_INVALID_PARAM;
 198
 199         curpacket = *packets;
 200         if (curpacket != NULL) {
 201                 while (curpacket->next != NULL) {
 202                         curpacket = curpacket->next;
 203                 }
 204         }
 205
 206         while (rc == ONAK_E_OK && (maxnum == 0 || keys < maxnum) &&
 207                         !getchar_func(ctx, 1, &curchar)) {
 208                 if (curchar & 0x80) {
 209                         /*
 210                          * New packet. Allocate memory for it.
 211                          */
 212                         if (curpacket != NULL) {
 213                                 curpacket->next = malloc(sizeof (*curpacket));
 214                                 packetend = &curpacket->next;
 215                                 curpacket = curpacket->next;
 216                         } else {
 217                                 *packets = curpacket =
 218                                         malloc(sizeof (*curpacket));
 219                                 packetend = packets;
 220                         }
 221                         memset(curpacket, 0, sizeof(*curpacket));
 222                         curpacket->packet =
 223                                 malloc(sizeof (*curpacket->packet));
 224                         memset(curpacket->packet, 0,
 225                                         sizeof(*curpacket->packet));
 226
 227                         curpacket->packet->newformat = (curchar & 0x40);
 228
 229                         /*
 230                          * TODO: Better error checking on getchar_func.
 231                          */
 232                         if (curpacket->packet->newformat) {
 233                                 curpacket->packet->tag = (curchar & 0x3F);
 234                                 if (getchar_func(ctx, 1, &curchar)) {
 235                                         rc = ONAK_E_INVALID_PKT;
 236                                         break;
 237                                 }
 238                                 curpacket->packet->length = curchar;
 239                                 if (curpacket->packet->length > 191 &&
 240                                         curpacket->packet->length < 224) {
 241                                         rc = getchar_func(ctx, 1, &curchar);
 242                                         curpacket->packet->length -= 192;
 243                                         curpacket->packet->length <<= 8;
 244                                         curpacket->packet->length += curchar;
 245                                         curpacket->packet->length += 192;
 246                                 } else if (curpacket->packet->length > 223 &&
 247                                         curpacket->packet->length < 255) {
 248                                         free(curpacket->packet);
 249                                         curpacket->packet = NULL;
 250                                         rc = ONAK_E_UNSUPPORTED_FEATURE;
 251                                 } else if (curpacket->packet->length == 255) {
 252                                         /*
 253                                          * 5 byte length; ie 255 followed by 3
 254                                          * bytes of MSB length.
 255                                          */
 256                                         if (getchar_func(ctx, 1, &curchar)) {
 257                                                 rc = ONAK_E_INVALID_PKT;
 258                                                 break;
 259                                         }
 260                                         curpacket->packet->length = curchar;
 261                                         curpacket->packet->length <<= 8;
 262                                         if (getchar_func(ctx, 1, &curchar)) {
 263                                                 rc = ONAK_E_INVALID_PKT;
 264                                                 break;
 265                                         }
 266                                         curpacket->packet->length += curchar;
 267                                         curpacket->packet->length <<= 8;
 268                                         if (getchar_func(ctx, 1, &curchar)) {
 269                                                 rc = ONAK_E_INVALID_PKT;
 270                                                 break;
 271                                         }
 272                                         curpacket->packet->length += curchar;
 273                                         curpacket->packet->length <<= 8;
 274                                         if (getchar_func(ctx, 1, &curchar)) {
 275                                                 rc = ONAK_E_INVALID_PKT;
 276                                                 break;
 277                                         }
 278                                         curpacket->packet->length += curchar;
 279                                 }
 280                         } else {
 281                                 curpacket->packet->tag = (curchar & 0x3C) >> 2;
 282                                 switch (curchar & 3) {
 283                                 case 0:
 284                                         if (getchar_func(ctx, 1, &curchar)) {
 285                                                 rc = ONAK_E_INVALID_PKT;
 286                                                 break;
 287                                         }
 288                                         curpacket->packet->length = curchar;
 289                                         break;
 290                                 case 1:
 291                                         if (getchar_func(ctx, 1, &curchar)) {
 292                                                 rc = ONAK_E_INVALID_PKT;
 293                                                 break;
 294                                         }
 295                                         curpacket->packet->length = curchar;
 296                                         curpacket->packet->length <<= 8;
 297                                         if (getchar_func(ctx, 1, &curchar)) {
 298                                                 rc = ONAK_E_INVALID_PKT;
 299                                                 break;
 300                                         }
 301                                         curpacket->packet->length += curchar;
 302                                         break;
 303                                 case 2:
 304                                         if (getchar_func(ctx, 1, &curchar)) {
 305                                                 rc = ONAK_E_INVALID_PKT;
 306                                                 break;
 307                                         }
 308                                         curpacket->packet->length =
 309                                                 ((unsigned) curchar << 24);
 310                                         if (getchar_func(ctx, 1, &curchar)) {
 311                                                 rc = ONAK_E_INVALID_PKT;
 312                                                 break;
 313                                         }
 314                                         curpacket->packet->length +=
 315                                                 (curchar << 16);
 316                                         if (getchar_func(ctx, 1, &curchar)) {
 317                                                 rc = ONAK_E_INVALID_PKT;
 318                                                 break;
 319                                         }
 320                                         curpacket->packet->length +=
 321                                                 (curchar << 8);
 322                                         if (getchar_func(ctx, 1, &curchar)) {
 323                                                 rc = ONAK_E_INVALID_PKT;
 324                                                 break;
 325                                         }
 326                                         curpacket->packet->length += curchar;
 327                                         break;
 328                                 case 3:
 329                                         rc = ONAK_E_UNSUPPORTED_FEATURE;
 330                                         free(curpacket->packet);
 331                                         curpacket->packet = NULL;
 332                                         break;
 333                                 }
 334                         }
 335
 336                         if (rc == 0) {
 337                                 if (curpacket->packet->tag ==
 338                                                 OPENPGP_PACKET_PUBLICKEY) {
 339                                         keys++;
 340                                 }
 341                                 curpacket->packet->data =
 342                                         malloc(curpacket->packet->length *
 343                                         sizeof(unsigned char));
 344                                 if (curpacket->packet->data == NULL) {
 345                                         rc = ONAK_E_NOMEM;
 346                                 } else {
 347                                         rc = getchar_func(ctx,
 348                                                 curpacket->packet->length,
 349                                                 curpacket->packet->data);
 350                                 }
 351                         }
 352                 } else {
 353                         rc = ONAK_E_INVALID_PKT;
 354                 }
 355                 if (rc == ONAK_E_OK) {
 356                         /* Make sure the packet version is sane */
 357                         switch (curpacket->packet->tag) {
 358                         case OPENPGP_PACKET_ENCRYPTED_MDC:
 359                                 /* These packets must be v1 */
 360                                 if (curpacket->packet->data[0] != 1) {
 361                                         rc = ONAK_E_INVALID_PKT;
 362                                 }
 363                                 break;
 364                         case OPENPGP_PACKET_PKSESSIONKEY:
 365                         case OPENPGP_PACKET_ONEPASSSIG:
 366                                 /* These packets must be v3 */
 367                                 if (curpacket->packet->data[0] != 3) {
 368                                         rc = ONAK_E_INVALID_PKT;
 369                                 }
 370                                 break;
 371                         case OPENPGP_PACKET_SYMSESSIONKEY:
 372                                 /* These packets must be v4 */
 373                                 if (curpacket->packet->data[0] != 4) {
 374                                         rc = ONAK_E_INVALID_PKT;
 375                                 }
 376                                 break;
 377                         case OPENPGP_PACKET_SIGNATURE:
 378                         case OPENPGP_PACKET_SECRETKEY:
 379                         case OPENPGP_PACKET_PUBLICKEY:
 380                                 /* Must be v2 -> v5 */
 381                                 if (curpacket->packet->data[0] < 2 ||
 382                                         curpacket->packet->data[0] > 5) {
 383                                         rc = ONAK_E_INVALID_PKT;
 384                                 }
 385                                 break;
 386                         default:
 387                                 break;
 388                         }
 389                 }
 390         }
 391
 392         if (packetend != NULL) {
 393                 if ((*packetend)->packet != NULL) {
 394                         /* If we got an invalid final packet, discard it. */
 395                         if ((*packetend)->packet->data != NULL &&
 396                                         rc != ONAK_E_OK) {
 397                                 free((*packetend)->packet->data);
 398                                 (*packetend)->packet->data = NULL;
 399                         }
 400                         /* If we didn't get any data, clean it up. */
 401                         if ((*packetend)->packet->data == NULL) {
 402                                 free((*packetend)->packet);
 403                                 (*packetend)->packet = NULL;
 404                         }
 405                 }
 406                 /* Trim the last packet if it doesn't actually exist */
 407                 if ((*packetend)->packet == NULL) {
 408                         free(*packetend);
 409                         *packetend = NULL;
 410                 }
 411         }
 412
 413         return (rc);
 414 }
 415
 416 /**
 417  *      write_openpgp_stream - Reads a stream of OpenPGP packets.
 418  *      @putchar_func: The function to put the next character to the stream.
 419  *      @ctx: A pointer to the context structure for putchar_func.
 420  *      @packets: The list of packets.
 421  *
 422  *      This function uses putchar_func to write characters to an OpenPGP
 423  *      packet stream from a linked list of packets.
 424  */
 425 onak_status_t write_openpgp_stream(int (*putchar_func)(void *ctx, size_t count,
 426                                                 void *c),
 427                                 void *ctx,
 428                                 struct openpgp_packet_list *packets)
 429 {
 430         unsigned char   curchar = 0;
 431
 432         while (packets != NULL) {
 433                 curchar = 0x80;
 434                 if (packets->packet->newformat) {
 435                         curchar |= 0x40;
 436                         curchar |= packets->packet->tag;
 437                         putchar_func(ctx, 1, &curchar);
 438
 439                         if (packets->packet->length < 192) {
 440                                 curchar = packets->packet->length;
 441                                 putchar_func(ctx, 1, &curchar);
 442                         } else if (packets->packet->length > 191 &&
 443                                 packets->packet->length < 8383) {
 444                                 curchar = (((packets->packet->length - 192) &
 445                                          0xFF00) >> 8) + 192;
 446                                 putchar_func(ctx, 1, &curchar);
 447
 448                                 curchar = (packets->packet->length - 192) &
 449                                          0xFF;
 450                                 putchar_func(ctx, 1, &curchar);
 451                         } else if (packets->packet->length > 8382 &&
 452                                 packets->packet->length < 0xFFFFFFFF) {
 453                                 curchar = 255;
 454                                 putchar_func(ctx, 1, &curchar);
 455
 456                                 curchar = (packets->packet->length >> 24);
 457                                 curchar &= 0xFF;
 458                                 putchar_func(ctx, 1, &curchar);
 459
 460                                 curchar = (packets->packet->length >> 16);
 461                                 curchar &= 0xFF;
 462                                 putchar_func(ctx, 1, &curchar);
 463
 464                                 curchar = (packets->packet->length >> 8);
 465                                 curchar &= 0xFF;
 466                                 putchar_func(ctx, 1, &curchar);
 467
 468                                 curchar = packets->packet->length;
 469                                 curchar &= 0xFF;
 470                                 putchar_func(ctx, 1, &curchar);
 471                         } else {
 472                                 return ONAK_E_UNSUPPORTED_FEATURE;
 473                         }
 474                 } else {
 475                         curchar |= (packets->packet->tag << 2);
 476                         if (packets->packet->length < 256) {
 477                                 putchar_func(ctx, 1, &curchar);
 478                                 curchar = packets->packet->length;
 479                                 putchar_func(ctx, 1, &curchar);
 480                         } else if (packets->packet->length < 0x10000) {
 481                                 curchar |= 1;
 482                                 putchar_func(ctx, 1, &curchar);
 483                                 curchar = packets->packet->length >> 8;
 484                                 putchar_func(ctx, 1, &curchar);
 485                                 curchar = packets->packet->length & 0xFF;
 486                                 putchar_func(ctx, 1, &curchar);
 487                         } else {
 488                                 curchar |= 2;
 489                                 putchar_func(ctx, 1, &curchar);
 490                                 curchar = packets->packet->length >> 24;
 491                                 putchar_func(ctx, 1, &curchar);
 492                                 curchar = (packets->packet->length >> 16) & 0xFF;
 493                                 putchar_func(ctx, 1, &curchar);
 494                                 curchar = (packets->packet->length >> 8) & 0xFF;
 495                                 putchar_func(ctx, 1, &curchar);
 496                                 curchar = packets->packet->length & 0xFF;
 497                                 putchar_func(ctx, 1, &curchar);
 498                         }
 499                 }
 500
 501                 putchar_func(ctx, packets->packet->length,
 502                                 packets->packet->data);
 503                 packets = packets->next;
 504         }
 505
 506         return ONAK_E_OK;
 507 }
 508
 509 /**
 510  *      flatten_publickey - Convert a publickey to an OpenPGP packet list.
 511  *      @key: The public key.
 512  *      @packets: The outputted packet list.
 513  *
 514  *      This function converts public key structure to a linked list of OpenPGP
 515  *      packets ready for outputing or storage.
 516  */
 517 int flatten_publickey(struct openpgp_publickey *key,
 518                         struct openpgp_packet_list **packets,
 519                         struct openpgp_packet_list **list_end)
 520 {
 521         struct openpgp_signedpacket_list        *tmpsignedlist = NULL;
 522         struct openpgp_packet_list              *tmplist = NULL;
 523
 524         while (key != NULL) {
 525                 /*
 526                  * First write the public key packet out.
 527                  */
 528                 ADD_PACKET_TO_LIST((*list_end), packet_dup(key->publickey));
 529                 if (*packets == NULL) {
 530                         *packets = *list_end;
 531                 }
 532
 533                 /*
 534                  * Now do any signatures on the main key.
 535                  */
 536                 for (tmplist = key->sigs; tmplist != NULL;
 537                                 tmplist = tmplist->next) {
 538                         ADD_PACKET_TO_LIST((*list_end),
 539                                         packet_dup(tmplist->packet));
 540                 }
 541
 542                 /*
 543                  * Output any UIDs along with their signatures.
 544                  */
 545                 for (tmpsignedlist = key->uids; tmpsignedlist != NULL;
 546                                 tmpsignedlist = tmpsignedlist->next) {
 547
 548                         ADD_PACKET_TO_LIST((*list_end),
 549                                 packet_dup(tmpsignedlist->packet));
 550                         for (tmplist = tmpsignedlist->sigs; tmplist != NULL;
 551                                         tmplist = tmplist->next) {
 552                                 ADD_PACKET_TO_LIST((*list_end),
 553                                         packet_dup(tmplist->packet));
 554                         }
 555                 }
 556
 557                 /*
 558                  * Output any subkeys along with their signatures.
 559                  */
 560                 for (tmpsignedlist = key->subkeys; tmpsignedlist != NULL;
 561                                 tmpsignedlist = tmpsignedlist->next) {
 562
 563                         ADD_PACKET_TO_LIST((*list_end),
 564                                 packet_dup(tmpsignedlist->packet));
 565                         for (tmplist = tmpsignedlist->sigs; tmplist != NULL;
 566                                         tmplist = tmplist->next) {
 567                                 ADD_PACKET_TO_LIST((*list_end),
 568                                         packet_dup(tmplist->packet));
 569                         }
 570                 }
 571                 key = key->next;
 572         }
 573         return 0;
 574 }