ucert.c

   1 /*
   2  * Copyright (C) 2018 Daniel Golle <daniel@makrotopia.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 3
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define _GNU_SOURCE
  15
  16 #include <fcntl.h>
  17 #include <dlfcn.h>
  18 #include <stdio.h>
  19 #include <stdbool.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <getopt.h>
  23 #include <stdint.h>
  24 #include <unistd.h>
  25 #include <inttypes.h>
  26 #include <sys/stat.h>
  27 #include <sys/wait.h>
  28
  29 #include <json-c/json.h>
  30 #include <libubox/blob.h>
  31 #include <libubox/utils.h>
  32 #include <libubox/list.h>
  33 #include <libubox/vlist.h>
  34 #include <libubox/blobmsg_json.h>
  35
  36 #include "usign.h"
  37
  38 #define CERT_BUF_LEN 4096
  39
  40 static enum {
  41         CMD_APPEND,
  42         CMD_DUMP,
  43         CMD_ISSUE,
  44         CMD_REVOKE,
  45         CMD_VERIFY,
  46         CMD_NONE,
  47 } cmd = CMD_NONE;
  48
  49 static bool quiet;
  50
  51 enum cert_attr {
  52         CERT_ATTR_SIGNATURE,
  53         CERT_ATTR_PAYLOAD,
  54         CERT_ATTR_MAX
  55 };
  56
  57 static const struct blob_attr_info cert_policy[CERT_ATTR_MAX] = {
  58         [CERT_ATTR_SIGNATURE] = { .type = BLOB_ATTR_BINARY },
  59         [CERT_ATTR_PAYLOAD] = { .type = BLOB_ATTR_NESTED },
  60 };
  61
  62 enum cert_cont_attr {
  63         CERT_CT_ATTR_PAYLOAD,
  64         CERT_CT_ATTR_MAX
  65 };
  66
  67 static const struct blobmsg_policy cert_cont_policy[CERT_CT_ATTR_MAX] = {
  68         [CERT_CT_ATTR_PAYLOAD] = { .name = "ucert", .type = BLOBMSG_TYPE_TABLE },
  69 };
  70
  71 enum cert_payload_attr {
  72         CERT_PL_ATTR_CERTTYPE,
  73         CERT_PL_ATTR_CERTID,
  74         CERT_PL_ATTR_VALIDFROMTIME,
  75         CERT_PL_ATTR_EXPIRETIME,
  76         CERT_PL_ATTR_PUBKEY,
  77         CERT_PL_ATTR_KEY_FINGERPRINT,
  78         CERT_PL_ATTR_MAX
  79 };
  80
  81 enum certtype_id {
  82         CERTTYPE_UNSPEC,
  83         CERTTYPE_AUTH,
  84         CERTTYPE_REVOKE
  85 };
  86
  87 static const struct blobmsg_policy cert_payload_policy[CERT_PL_ATTR_MAX] = {
  88         [CERT_PL_ATTR_CERTTYPE] = { .name = "certtype", .type = BLOBMSG_TYPE_INT32 },
  89         [CERT_PL_ATTR_CERTID] = { .name = "certid", .type = BLOBMSG_TYPE_INT32 },
  90         [CERT_PL_ATTR_VALIDFROMTIME] = { .name = "validfrom", .type = BLOBMSG_TYPE_INT64 },
  91         [CERT_PL_ATTR_EXPIRETIME] = { .name = "expiresat", .type = BLOBMSG_TYPE_INT64 },
  92         [CERT_PL_ATTR_PUBKEY] = { .name = "pubkey", .type = BLOBMSG_TYPE_STRING },
  93         [CERT_PL_ATTR_KEY_FINGERPRINT] = { .name = "fingerprint", .type = BLOBMSG_TYPE_STRING },
  94 };
  95
  96 struct cert_object {
  97         struct list_head list;
  98         struct blob_attr **cert;
  99 };
 100
 101 static int write_file(const char *filename, void *buf, size_t len, bool append) {
 102         FILE *f;
 103         size_t outlen;
 104
 105         f = fopen(filename, append?"a":"w");
 106         if (!f)
 107                 return 1;
 108
 109         outlen = fwrite(buf, 1, len, f);
 110         fclose(f);
 111         return (outlen == len);
 112 }
 113
 114 static int cert_load(const char *certfile, struct list_head *chain) {
 115         FILE *f;
 116         struct blob_attr *certtb[CERT_ATTR_MAX];
 117         struct cert_object *cobj;
 118         char filebuf[CERT_BUF_LEN];
 119         int ret = 0;
 120         int len;
 121
 122         f = fopen(certfile, "r");
 123         if (!f)
 124                 return 1;
 125
 126         len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f);
 127         if (len < 64)
 128                 return 1;
 129
 130         ret = ferror(f) || !feof(f);
 131         fclose(f);
 132         if (ret)
 133                 return 1;
 134
 135         /* TODO: read more than one blob from file */
 136         ret = blob_parse(filebuf, certtb, cert_policy, CERT_ATTR_MAX);
 137         cobj = calloc(1, sizeof(*cobj));
 138         cobj->cert = &certtb;
 139         list_add_tail(&cobj->list, chain);
 140
 141         return (ret <= 0);
 142 }
 143
 144 static int cert_append(const char *certfile, const char *pubkeyfile, const char *sigfile) {
 145         fprintf(stderr, "not implemented\n");
 146         return 1;
 147 }
 148
 149 static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX],
 150                        const char *pubkeyfile, const char *pubkeydir) {
 151         int i;
 152         char msgfname[256], sigfname[256];
 153         int ret;
 154         char tmpdir[] = "/tmp/ucert-XXXXXX";
 155
 156         if (mkdtemp(tmpdir) == NULL)
 157                 return errno;
 158
 159         snprintf(msgfname, sizeof(msgfname) - 1, "%s/%s", tmpdir, "payload");
 160         snprintf(sigfname, sizeof(sigfname) - 1, "%s/%s", tmpdir, "payload.sig");
 161
 162         for (i = 0; i < CERT_ATTR_MAX; i++) {
 163                 struct blob_attr *v = cert[i];
 164
 165                 if (!v)
 166                         break;
 167
 168                 switch(cert_policy[i].type) {
 169                 case BLOB_ATTR_BINARY:
 170                         write_file(sigfname, blob_data(v), blob_len(v), false);
 171                         break;
 172                 case BLOB_ATTR_NESTED:
 173                         write_file(msgfname, blob_data(v), blob_len(v), false);
 174                         break;
 175                 }
 176         }
 177
 178         ret = usign_v(msgfname, pubkeyfile, pubkeydir, sigfname, quiet);
 179
 180         unlink(msgfname);
 181         unlink(sigfname);
 182         rmdir(tmpdir);
 183
 184         return ret;
 185 }
 186
 187 static int chain_verify(const char *msgfile, const char *pubkeyfile,
 188                         const char *pubkeydir, struct list_head *chain) {
 189         struct cert_object *cobj;
 190         struct blob_attr *containertb[CERT_CT_ATTR_MAX];
 191         struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
 192         char tmpdir[] = "/tmp/ucert-XXXXXX";
 193         char chainedpubkey[256] = {0};
 194         char extsigfile[256] = {0};
 195         int ret = 1;
 196         int checkmsg = 0;
 197
 198         if (mkdtemp(tmpdir) == NULL)
 199                 return errno;
 200
 201         if (msgfile)
 202                 checkmsg = -1;
 203
 204         list_for_each_entry(cobj, chain, list) {
 205                 ret = cert_verify_blob(cobj->cert, chainedpubkey[0]?chainedpubkey:pubkeyfile, pubkeydir);
 206                 if (ret)
 207                         goto clean_and_return;
 208
 209                 if (cobj->cert[CERT_ATTR_PAYLOAD]) {
 210                         struct timeval tv;
 211                         uint64_t validfrom;
 212                         uint64_t expiresat;
 213                         uint32_t certtype;
 214
 215                         blobmsg_parse(cert_cont_policy,
 216                                       ARRAY_SIZE(cert_cont_policy),
 217                                       containertb,
 218                                       blob_data(cobj->cert[CERT_ATTR_PAYLOAD]),
 219                                       blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
 220                         if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
 221                                 ret = 1;
 222                                 fprintf(stderr, "no ucert in signed payload\n");
 223                                 goto clean_and_return;
 224                         }
 225                         blobmsg_parse(cert_payload_policy,
 226                                       ARRAY_SIZE(cert_payload_policy),
 227                                       payloadtb,
 228                                       blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]),
 229                                       blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD]));
 230
 231                         if (!payloadtb[CERT_PL_ATTR_CERTTYPE] ||
 232                             !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] ||
 233                             !payloadtb[CERT_PL_ATTR_EXPIRETIME] ||
 234                             !payloadtb[CERT_PL_ATTR_PUBKEY]) {
 235                                 ret = 1;
 236                                 fprintf(stderr, "missing mandatory ucert attributes\n");
 237                                 goto clean_and_return;
 238                         }
 239                         certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
 240                         validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
 241                         expiresat = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_EXPIRETIME]);
 242
 243                         if (certtype != CERTTYPE_AUTH) {
 244                                 ret = 2;
 245                                 fprintf(stderr, "wrong certificate type\n");
 246                                 goto clean_and_return;
 247                         }
 248
 249                         gettimeofday(&tv, NULL);
 250                         if (tv.tv_sec < validfrom ||
 251                             tv.tv_sec >= expiresat) {
 252                                 ret = 3;
 253                                 fprintf(stderr, "certificate expired\n");
 254                                 goto clean_and_return;
 255                         }
 256
 257                         snprintf(chainedpubkey, sizeof(chainedpubkey) - 1, "%s/%s", tmpdir, "chained-pubkey");
 258                         write_file(chainedpubkey,
 259                                    blobmsg_data(payloadtb[CERT_PL_ATTR_PUBKEY]),
 260                                    blobmsg_data_len(payloadtb[CERT_PL_ATTR_PUBKEY]),
 261                                    false);
 262                 } else {
 263                         if (msgfile) {
 264                                 snprintf(extsigfile, sizeof(extsigfile) - 1, "%s/%s", tmpdir, "ext-sig");
 265                                 write_file(extsigfile,
 266                                            blob_data(cobj->cert[CERT_ATTR_SIGNATURE]),
 267                                            blob_len(cobj->cert[CERT_ATTR_SIGNATURE]),
 268                                            false);
 269                                 checkmsg = ret = usign_v(msgfile,
 270                                               chainedpubkey[0]?chainedpubkey:pubkeyfile,
 271                                               pubkeydir, extsigfile, quiet);
 272                                 unlink(extsigfile);
 273                         } else {
 274                                 fprintf(stderr, "stray trailing signature without anything to verify!\n");
 275                                 ret = 1;
 276                         };
 277                 }
 278         }
 279
 280         if (checkmsg == -1)
 281                 fprintf(stderr, "missing signature to verify message!\n");
 282
 283 clean_and_return:
 284         if (chainedpubkey[0])
 285                 unlink(chainedpubkey);
 286         rmdir(tmpdir);
 287         return ret | checkmsg;
 288 }
 289
 290 static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) {
 291         int i;
 292
 293         for (i = 0; i < CERT_ATTR_MAX; i++) {
 294                 struct blob_attr *v = cert[i];
 295
 296                 if (!v)
 297                         continue;
 298
 299                 switch(cert_policy[i].type) {
 300                 case BLOB_ATTR_BINARY:
 301                         fprintf(stdout, "signature:\n---\n%s\n---\n", (char *) blob_data(v));
 302                         break;
 303                 case BLOB_ATTR_NESTED:
 304                         fprintf(stdout, "payload:\n---\n%s\n---\n", blobmsg_format_json_indent(blob_data(v), false, 0));
 305                         break;
 306                 }
 307         }
 308 }
 309
 310 static int cert_dump(const char *certfile) {
 311         struct cert_object *cobj;
 312         static LIST_HEAD(certchain);
 313
 314         if (cert_load(certfile, &certchain)) {
 315                 fprintf(stderr, "cannot parse cert\n");
 316                 return 1;
 317         }
 318
 319         list_for_each_entry(cobj, &certchain, list)
 320                 cert_dump_blob(cobj->cert);
 321
 322         return 0;
 323 }
 324
 325 static int cert_issue(const char *certfile, const char *pubkeyfile, const char *seckeyfile) {
 326         struct blob_buf certbuf;
 327         struct blob_buf payloadbuf;
 328         struct timeval tv;
 329         struct stat st;
 330         int pklen, siglen;
 331         int revoker = 1;
 332         void *c;
 333         FILE *pkf, *sigf;
 334         char pkb[512];
 335         char sigb[512];
 336         char fname[256], sfname[256];
 337         char pkfp[17];
 338         char tmpdir[] = "/tmp/ucert-XXXXXX";
 339
 340         if (stat(certfile, &st) == 0) {
 341                 fprintf(stderr, "certfile %s exists, won't overwrite.\n", certfile);
 342                 return -1;
 343         }
 344
 345         pkf = fopen(pubkeyfile, "r");
 346         if (!pkf)
 347                 return -1;
 348
 349         pklen = fread(pkb, 1, 512, pkf);
 350         pkb[pklen] = '\0';
 351
 352         if (pklen < 32)
 353                 return -1;
 354
 355         fclose(pkf);
 356
 357         if (usign_f_pubkey(pkfp, pubkeyfile))
 358                 return -1;
 359
 360         gettimeofday(&tv, NULL);
 361
 362         if (mkdtemp(tmpdir) == NULL)
 363                 return errno;
 364
 365         while (revoker >= 0) {
 366                 blob_buf_init(&payloadbuf, 0);
 367                 c = blobmsg_open_table(&payloadbuf, "ucert");
 368                 blobmsg_add_u32(&payloadbuf, "certtype", revoker?CERTTYPE_REVOKE:CERTTYPE_AUTH);
 369                 blobmsg_add_u64(&payloadbuf, "validfrom", tv.tv_sec);
 370                 if (!revoker) {
 371                         blobmsg_add_u64(&payloadbuf, "expiresat", tv.tv_sec + 60 * 60 * 24 * 365);
 372                         blobmsg_add_string(&payloadbuf, "pubkey", pkb);
 373                 } else {
 374                         blobmsg_add_string(&payloadbuf, "fingerprint", pkfp);
 375                 }
 376
 377                 blobmsg_close_table(&payloadbuf, c);
 378
 379                 snprintf(fname, sizeof(fname) - 1, "%s/%s", tmpdir, revoker?"revoker":"payload");
 380                 write_file(fname, blob_data(payloadbuf.head), blob_len(payloadbuf.head), false);
 381
 382                 snprintf(sfname, sizeof(sfname) - 1, "%s/%s", tmpdir, revoker?"revoker.sig":"payload.sig");
 383                 if (usign_s(fname, seckeyfile, sfname, quiet))
 384                         return 1;
 385
 386                 sigf = fopen(sfname, "r");
 387                 if (!sigf)
 388                         return 1;
 389
 390                 siglen = fread(sigb, 1, 1024, sigf);
 391                 if (siglen < 1)
 392                         return 1;
 393
 394                 sigb[siglen-1] = '\0';
 395                 fclose(sigf);
 396
 397                 unlink(fname);
 398                 unlink(sfname);
 399
 400                 blob_buf_init(&certbuf, 0);
 401                 blob_put(&certbuf, CERT_ATTR_SIGNATURE, sigb, siglen);
 402                 blob_put(&certbuf, CERT_ATTR_PAYLOAD, blob_data(payloadbuf.head), blob_len(payloadbuf.head));
 403                 snprintf(fname, sizeof(fname) - 1, "%s%s", certfile, revoker?".revoke":"");
 404                 write_file(fname, certbuf.head, blob_raw_len(certbuf.head), false);
 405                 revoker--;
 406         }
 407
 408         rmdir(tmpdir);
 409
 410         return 0;
 411 }
 412
 413 static int cert_process_revoker(const char *certfile) {
 414         fprintf(stderr, "not implemented\n");
 415         return 1;
 416 }
 417
 418 static int cert_verify(const char *certfile, const char *pubkeyfile, const char *pubkeydir, const char *msgfile) {
 419         static LIST_HEAD(certchain);
 420
 421         if (cert_load(certfile, &certchain)) {
 422                 fprintf(stderr, "cannot parse cert\n");
 423                 return 1;
 424         }
 425
 426         return chain_verify(msgfile, pubkeyfile, pubkeydir, &certchain);
 427 }
 428
 429 static int usage(const char *cmd)
 430 {
 431         fprintf(stderr,
 432                 "Usage: %s <command> <options>\n"
 433                 "Commands:\n"
 434                 "  -A:                  append (needs -c and -p and/or -x)\n"
 435                 "  -D:                  dump\n"
 436                 "  -I:                  issue cert and revoker (needs -c and -p and -s)\n"
 437                 "  -R:                  process revoker certificate (needs -c)\n"
 438                 "  -V:                  verify (needs -c and -p|-P)\n"
 439                 "Options:\n"
 440                 "  -c <file>:           certificate file\n"
 441                 "  -m <file>:           message file (verify only)\n"
 442                 "  -p <file>:           public key file\n"
 443                 "  -P <path>:           public key directory (verify only)\n"
 444                 "  -q:                  quiet (do not print verification result, use return code only)\n"
 445                 "  -s <file>:           secret key file (issue only)\n"
 446                 "  -x <file>:           signature file\n"
 447                 "\n",
 448                 cmd);
 449         return 1;
 450 }
 451
 452 int main(int argc, char *argv[]) {
 453         int ch;
 454         const char *msgfile = NULL;
 455         const char *sigfile = NULL;
 456         const char *pubkeyfile = NULL;
 457         const char *pubkeydir = NULL;
 458         const char *certfile = NULL;
 459         const char *seckeyfile = NULL;
 460
 461         quiet = false;
 462         while ((ch = getopt(argc, argv, "ADIRVc:m:p:P:qs:x:")) != -1) {
 463                 switch (ch) {
 464                 case 'A':
 465                         cmd = CMD_APPEND;
 466                         break;
 467                 case 'D':
 468                         cmd = CMD_DUMP;
 469                         break;
 470                 case 'I':
 471                         cmd = CMD_ISSUE;
 472                         break;
 473                 case 'R':
 474                         cmd = CMD_REVOKE;
 475                         break;
 476                 case 'V':
 477                         cmd = CMD_VERIFY;
 478                         break;
 479                 case 'c':
 480                         certfile = optarg;
 481                         break;
 482                 case 'm':
 483                         msgfile = optarg;
 484                         break;
 485                 case 'p':
 486                         pubkeyfile = optarg;
 487                         break;
 488                 case 'P':
 489                         pubkeydir = optarg;
 490                         break;
 491                 case 's':
 492                         seckeyfile = optarg;
 493                         break;
 494                 case 'q':
 495                         quiet = true;
 496                         break;
 497                 case 'x':
 498                         sigfile = optarg;
 499                         break;
 500                 default:
 501                         return usage(argv[0]);
 502                 }
 503         }
 504
 505         switch (cmd) {
 506         case CMD_APPEND:
 507                 if (certfile && (pubkeyfile || sigfile))
 508                         return cert_append(certfile, pubkeyfile, sigfile);
 509                 else
 510                         return usage(argv[0]);
 511         case CMD_DUMP:
 512                 if (certfile)
 513                         return cert_dump(certfile);
 514                 else
 515                         return usage(argv[0]);
 516         case CMD_ISSUE:
 517                 if (certfile && pubkeyfile && seckeyfile)
 518                         return cert_issue(certfile, pubkeyfile, seckeyfile);
 519                 else
 520                         return usage(argv[0]);
 521         case CMD_REVOKE:
 522                 if (certfile)
 523                         return cert_process_revoker(certfile);
 524                 else
 525                         return usage(argv[0]);
 526         case CMD_VERIFY:
 527                 if (certfile && (pubkeyfile || pubkeydir))
 528                         return cert_verify(certfile, pubkeyfile, pubkeydir, msgfile);
 529                 else
 530                         return usage(argv[0]);
 531         case CMD_NONE:
 532                 return usage(argv[0]);
 533         }
 534
 535         /* unreachable */
 536         return usage(argv[0]);
 537 }