src/common/ssl_certificate.c

   1 /*
   2  * Claws Mail -- a GTK+ based, lightweight, and fast e-mail client
   3  * Copyright (C) 1999-2007 Colin Leroy <colin@colino.net>
   4  * and the Claws Mail team
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  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  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  18  *
  19  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #  include "config.h"
  23 #endif
  24
  25 #if (defined(USE_OPENSSL) || defined (USE_GNUTLS))
  26 #if USE_OPENSSL
  27 #include <openssl/ssl.h>
  28 #else
  29 #include <gnutls/gnutls.h>
  30 #include <gnutls/x509.h>
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <stdio.h>
  34 #include <unistd.h>
  35 #include <string.h>
  36 #endif
  37 #include <glib.h>
  38 #include <glib/gi18n.h>
  39
  40 #include "ssl_certificate.h"
  41 #include "utils.h"
  42 #include "log.h"
  43 #include "socket.h"
  44 #include "hooks.h"
  45 #include "defs.h"
  46
  47 static GHashTable *warned_expired = NULL;
  48
  49 gboolean prefs_common_unsafe_ssl_certs(void);
  50
  51 static gchar *get_certificate_path(const gchar *host, const gchar *port, const gchar *fp)
  52 {
  53         if (fp != NULL && prefs_common_unsafe_ssl_certs())
  54                 return g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
  55                           "certs", G_DIR_SEPARATOR_S,
  56                           host, ".", port, ".", fp, ".cert", NULL);
  57         else
  58                 return g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
  59                           "certs", G_DIR_SEPARATOR_S,
  60                           host, ".", port, ".cert", NULL);
  61 }
  62
  63 #if USE_OPENSSL
  64 static SSLCertificate *ssl_certificate_new_lookup(X509 *x509_cert, gchar *host, gushort port, gboolean lookup);
  65 #else
  66 static SSLCertificate *ssl_certificate_new_lookup(gnutls_x509_crt x509_cert, gchar *host, gushort port, gboolean lookup);
  67 #endif
  68 #if USE_OPENSSL
  69 /* from Courier */
  70 time_t asn1toTime(ASN1_TIME *asn1Time)
  71 {
  72         struct tm tm;
  73         int offset;
  74
  75         if (asn1Time == NULL || asn1Time->length < 13)
  76                 return 0;
  77
  78         memset(&tm, 0, sizeof(tm));
  79
  80 #define N2(n)   ((asn1Time->data[n]-'0')*10 + asn1Time->data[(n)+1]-'0')
  81
  82 #define CPY(f,n) (tm.f=N2(n))
  83
  84         CPY(tm_year,0);
  85
  86         if(tm.tm_year < 50)
  87                 tm.tm_year += 100; /* Sux */
  88
  89         CPY(tm_mon, 2);
  90         --tm.tm_mon;
  91         CPY(tm_mday, 4);
  92         CPY(tm_hour, 6);
  93         CPY(tm_min, 8);
  94         CPY(tm_sec, 10);
  95
  96         offset=0;
  97
  98         if (asn1Time->data[12] != 'Z')
  99         {
 100                 if (asn1Time->length < 17)
 101                         return 0;
 102
 103                 offset=N2(13)*3600+N2(15)*60;
 104
 105                 if (asn1Time->data[12] == '-')
 106                         offset= -offset;
 107         }
 108
 109 #undef N2
 110 #undef CPY
 111
 112         return mktime(&tm)-offset;
 113 }
 114 #endif
 115
 116 static char * get_fqdn(char *host)
 117 {
 118         struct hostent *hp;
 119
 120         if (host == NULL || strlen(host) == 0)
 121                 return g_strdup("");
 122
 123         hp = my_gethostbyname(host);
 124         if (hp == NULL)
 125                 return g_strdup(host); /*caller should free*/
 126         else
 127                 return g_strdup(hp->h_name);
 128 }
 129
 130 char * readable_fingerprint(unsigned char *src, int len)
 131 {
 132         int i=0;
 133         char * ret;
 134
 135         if (src == NULL)
 136                 return NULL;
 137         ret = g_strdup("");
 138         while (i < len) {
 139                 char *tmp2;
 140                 if(i>0)
 141                         tmp2 = g_strdup_printf("%s:%02X", ret, src[i]);
 142                 else
 143                         tmp2 = g_strdup_printf("%02X", src[i]);
 144                 g_free(ret);
 145                 ret = g_strdup(tmp2);
 146                 g_free(tmp2);
 147                 i++;
 148         }
 149         return ret;
 150 }
 151
 152 #if USE_GNUTLS
 153 static gnutls_x509_crt x509_crt_copy(gnutls_x509_crt src)
 154 {
 155     int ret;
 156     size_t size;
 157     gnutls_datum tmp;
 158     gnutls_x509_crt dest;
 159
 160     if (gnutls_x509_crt_init(&dest) != 0) {
 161         g_warning("couldn't gnutls_x509_crt_init\n");
 162         return NULL;
 163     }
 164
 165     if (gnutls_x509_crt_export(src, GNUTLS_X509_FMT_DER, NULL, &size)
 166         != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 167         g_warning("couldn't gnutls_x509_crt_export to get size\n");
 168         gnutls_x509_crt_deinit(dest);
 169         return NULL;
 170     }
 171
 172     tmp.data = malloc(size);
 173     memset(tmp.data, 0, size);
 174     ret = gnutls_x509_crt_export(src, GNUTLS_X509_FMT_DER, tmp.data, &size);
 175     if (ret == 0) {
 176         tmp.size = size;
 177         ret = gnutls_x509_crt_import(dest, &tmp, GNUTLS_X509_FMT_DER);
 178         if (ret) {
 179                 g_warning("couldn't gnutls_x509_crt_import for real (%d %s)\n", ret, gnutls_strerror(ret));
 180                 gnutls_x509_crt_deinit(dest);
 181                 dest = NULL;
 182         }
 183     } else {
 184         g_warning("couldn't gnutls_x509_crt_export for real (%d %s)\n", ret, gnutls_strerror(ret));
 185         gnutls_x509_crt_deinit(dest);
 186         dest = NULL;
 187     }
 188
 189     free(tmp.data);
 190     return dest;
 191 }
 192 #endif
 193
 194 #if USE_OPENSSL
 195 static SSLCertificate *ssl_certificate_new_lookup(X509 *x509_cert, gchar *host, gushort port, gboolean lookup)
 196 #else
 197 static SSLCertificate *ssl_certificate_new_lookup(gnutls_x509_crt x509_cert, gchar *host, gushort port, gboolean lookup)
 198 #endif
 199 {
 200         SSLCertificate *cert = g_new0(SSLCertificate, 1);
 201         unsigned int n;
 202         unsigned char md[128];
 203
 204         if (host == NULL || x509_cert == NULL) {
 205                 ssl_certificate_destroy(cert);
 206                 return NULL;
 207         }
 208 #if USE_OPENSSL
 209         cert->x509_cert = X509_dup(x509_cert);
 210 #else
 211         cert->x509_cert = x509_crt_copy(x509_cert);
 212         cert->status = (guint)-1;
 213 #endif
 214         if (lookup)
 215                 cert->host = get_fqdn(host);
 216         else
 217                 cert->host = g_strdup(host);
 218         cert->port = port;
 219
 220         /* fingerprint */
 221 #if USE_OPENSSL
 222         X509_digest(cert->x509_cert, EVP_md5(), md, &n);
 223         cert->fingerprint = readable_fingerprint(md, (int)n);
 224 #else
 225         gnutls_x509_crt_get_fingerprint(cert->x509_cert, GNUTLS_DIG_MD5, md, &n);
 226         cert->fingerprint = readable_fingerprint(md, (int)n);
 227 #endif
 228         return cert;
 229 }
 230
 231 #ifdef USE_GNUTLS
 232 static void i2d_X509_fp(FILE *fp, gnutls_x509_crt x509_cert)
 233 {
 234         char output[10*1024];
 235         size_t cert_size;
 236         int r;
 237
 238         if ((r = gnutls_x509_crt_export(x509_cert, GNUTLS_X509_FMT_DER, output, &cert_size)) < 0) {
 239                 g_warning("couldn't export cert %s\n", gnutls_strerror(r));
 240                 return;
 241         }
 242         debug_print("writing %zd bytes\n",cert_size);
 243         if (fwrite(&output, 1, cert_size, fp) < cert_size) {
 244                 g_warning("failed to write cert\n");
 245         }
 246 }
 247 static gnutls_x509_crt d2i_X509_fp(FILE *fp, int unused)
 248 {
 249         gnutls_x509_crt cert = NULL;
 250         gnutls_datum tmp;
 251         struct stat s;
 252         int r;
 253         if (fstat(fileno(fp), &s) < 0) {
 254                 perror("fstat");
 255                 return NULL;
 256         }
 257         tmp.data = malloc(s.st_size);
 258         memset(tmp.data, 0, s.st_size);
 259         tmp.size = s.st_size;
 260         if (fread (tmp.data, 1, s.st_size, fp) < s.st_size) {
 261                 perror("fread");
 262                 return NULL;
 263         }
 264
 265         gnutls_x509_crt_init(&cert);
 266         if ((r = gnutls_x509_crt_import(cert, &tmp, GNUTLS_X509_FMT_DER)) < 0) {
 267                 g_warning("import failed: %s\n", gnutls_strerror(r));
 268                 gnutls_x509_crt_deinit(cert);
 269                 cert = NULL;
 270         }
 271         debug_print("got cert! %p\n", cert);
 272         return cert;
 273 }
 274 #endif
 275
 276 static void ssl_certificate_save (SSLCertificate *cert)
 277 {
 278         gchar *file, *port;
 279         FILE *fp;
 280
 281         file = g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
 282                           "certs", G_DIR_SEPARATOR_S, NULL);
 283
 284         if (!is_dir_exist(file))
 285                 make_dir_hier(file);
 286         g_free(file);
 287
 288         port = g_strdup_printf("%d", cert->port);
 289         file = get_certificate_path(cert->host, port, cert->fingerprint);
 290
 291         g_free(port);
 292         fp = g_fopen(file, "wb");
 293         if (fp == NULL) {
 294                 g_free(file);
 295                 debug_print("Can't save certificate !\n");
 296                 return;
 297         }
 298         i2d_X509_fp(fp, cert->x509_cert);
 299         g_free(file);
 300         fclose(fp);
 301
 302 }
 303
 304 void ssl_certificate_destroy(SSLCertificate *cert)
 305 {
 306         if (cert == NULL)
 307                 return;
 308
 309         if (cert->x509_cert)
 310 #if USE_OPENSSL
 311                 X509_free(cert->x509_cert);
 312 #else
 313                 gnutls_x509_crt_deinit(cert->x509_cert);
 314 #endif
 315         g_free(cert->host);
 316         g_free(cert->fingerprint);
 317         g_free(cert);
 318         cert = NULL;
 319 }
 320
 321 void ssl_certificate_delete_from_disk(SSLCertificate *cert)
 322 {
 323         gchar *buf;
 324         gchar *file;
 325         buf = g_strdup_printf("%d", cert->port);
 326         file = get_certificate_path(cert->host, buf, cert->fingerprint);
 327         g_unlink (file);
 328         g_free(file);
 329         g_free(buf);
 330 }
 331
 332 SSLCertificate *ssl_certificate_find (gchar *host, gushort port, const gchar *fingerprint)
 333 {
 334         return ssl_certificate_find_lookup (host, port, fingerprint, TRUE);
 335 }
 336
 337 SSLCertificate *ssl_certificate_find_lookup (gchar *host, gushort port, const gchar *fingerprint, gboolean lookup)
 338 {
 339         gchar *file = NULL;
 340         gchar *buf;
 341         gchar *fqdn_host;
 342         SSLCertificate *cert = NULL;
 343 #if USE_OPENSSL
 344         X509 *tmp_x509;
 345 #else
 346         gnutls_x509_crt tmp_x509;
 347 #endif
 348         FILE *fp = NULL;
 349         gboolean must_rename = FALSE;
 350
 351         if (lookup)
 352                 fqdn_host = get_fqdn(host);
 353         else
 354                 fqdn_host = g_strdup(host);
 355
 356         buf = g_strdup_printf("%d", port);
 357
 358         if (fingerprint != NULL) {
 359                 file = get_certificate_path(fqdn_host, buf, fingerprint);
 360                 fp = g_fopen(file, "rb");
 361         }
 362         if (fp == NULL) {
 363                 /* see if we have the old one */
 364                 debug_print("didn't get %s\n", file);
 365                 g_free(file);
 366                 file = get_certificate_path(fqdn_host, buf, NULL);
 367                 fp = g_fopen(file, "rb");
 368
 369                 if (fp) {
 370                         debug_print("got %s\n", file);
 371                         must_rename = (fingerprint != NULL);
 372                 }
 373         } else {
 374                 debug_print("got %s first try\n", file);
 375         }
 376         if (fp == NULL) {
 377                 g_free(file);
 378                 g_free(fqdn_host);
 379                 g_free(buf);
 380                 return NULL;
 381         }
 382
 383         if ((tmp_x509 = d2i_X509_fp(fp, 0)) != NULL) {
 384                 cert = ssl_certificate_new_lookup(tmp_x509, fqdn_host, port, lookup);
 385                 debug_print("got cert %p\n", cert);
 386 #if USE_OPENSSL
 387                 X509_free(tmp_x509);
 388 #else
 389                 gnutls_x509_crt_deinit(tmp_x509);
 390 #endif
 391         }
 392         fclose(fp);
 393         g_free(file);
 394
 395         if (must_rename) {
 396                 gchar *old = get_certificate_path(fqdn_host, buf, NULL);
 397                 gchar *new = get_certificate_path(fqdn_host, buf, fingerprint);
 398                 if (strcmp(old, new))
 399                         move_file(old, new, TRUE);
 400                 g_free(old);
 401                 g_free(new);
 402         }
 403         g_free(buf);
 404         g_free(fqdn_host);
 405
 406         return cert;
 407 }
 408
 409 static gboolean ssl_certificate_compare (SSLCertificate *cert_a, SSLCertificate *cert_b)
 410 {
 411 #ifdef USE_OPENSSL
 412         if (cert_a == NULL || cert_b == NULL)
 413                 return FALSE;
 414         else if (!X509_cmp(cert_a->x509_cert, cert_b->x509_cert))
 415                 return TRUE;
 416         else
 417                 return FALSE;
 418 #else
 419         char *output_a;
 420         char *output_b;
 421         size_t cert_size_a, cert_size_b;
 422         int r;
 423
 424         if (cert_a == NULL || cert_b == NULL)
 425                 return FALSE;
 426
 427         if ((r = gnutls_x509_crt_export(cert_a->x509_cert, GNUTLS_X509_FMT_DER, NULL, &cert_size_a))
 428             != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 429                 g_warning("couldn't gnutls_x509_crt_export to get size a %s\n", gnutls_strerror(r));
 430                 return FALSE;
 431         }
 432
 433         if ((r = gnutls_x509_crt_export(cert_b->x509_cert, GNUTLS_X509_FMT_DER, NULL, &cert_size_b))
 434             != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 435                 g_warning("couldn't gnutls_x509_crt_export to get size b %s\n", gnutls_strerror(r));
 436                 return FALSE;
 437         }
 438
 439         output_a = malloc(cert_size_a);
 440         output_b = malloc(cert_size_b);
 441         if ((r = gnutls_x509_crt_export(cert_a->x509_cert, GNUTLS_X509_FMT_DER, output_a, &cert_size_a)) < 0) {
 442                 g_warning("couldn't gnutls_x509_crt_export a %s\n", gnutls_strerror(r));
 443                 return FALSE;
 444         }
 445         if ((r = gnutls_x509_crt_export(cert_b->x509_cert, GNUTLS_X509_FMT_DER, output_b, &cert_size_b)) < 0) {
 446                 g_warning("couldn't gnutls_x509_crt_export b %s\n", gnutls_strerror(r));
 447                 return FALSE;
 448         }
 449         if (cert_size_a != cert_size_b) {
 450                 g_warning("size differ %d %d\n", cert_size_a, cert_size_b);
 451                 return FALSE;
 452         }
 453         if (memcmp(output_a, output_b, cert_size_a)) {
 454                 g_warning("contents differ\n");
 455                 return FALSE;
 456         }
 457
 458         return TRUE;
 459 #endif
 460 }
 461
 462 #if USE_OPENSSL
 463 char *ssl_certificate_check_signer (X509 *cert)
 464 {
 465         X509_STORE_CTX store_ctx;
 466         X509_STORE *store;
 467         char *err_msg = NULL;
 468
 469         store = X509_STORE_new();
 470         if (store == NULL) {
 471                 g_print("Can't create X509_STORE\n");
 472                 return NULL;
 473         }
 474         if (!X509_STORE_set_default_paths(store)) {
 475                 X509_STORE_free (store);
 476                 return g_strdup(_("Couldn't load X509 default paths"));
 477         }
 478
 479         X509_STORE_CTX_init (&store_ctx, store, cert, NULL);
 480
 481         if(!X509_verify_cert (&store_ctx)) {
 482                 err_msg = g_strdup(X509_verify_cert_error_string(
 483                                         X509_STORE_CTX_get_error(&store_ctx)));
 484                 debug_print("Can't check signer: %s\n", err_msg);
 485                 X509_STORE_CTX_cleanup (&store_ctx);
 486                 X509_STORE_free (store);
 487                 return err_msg;
 488
 489         }
 490         X509_STORE_CTX_cleanup (&store_ctx);
 491         X509_STORE_free (store);
 492         return NULL;
 493 }
 494 #else
 495 char *ssl_certificate_check_signer (gnutls_x509_crt cert, guint status)
 496 {
 497         if (status == (guint)-1)
 498                 return g_strdup(_("Uncheckable"));
 499
 500         if (status & GNUTLS_CERT_INVALID) {
 501                 if (gnutls_x509_crt_check_issuer(cert, cert))
 502                         return g_strdup(_("Self-signed certificate"));
 503         }
 504         if (status & GNUTLS_CERT_REVOKED)
 505                 return g_strdup(_("Revoked certificate"));
 506         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
 507                 return g_strdup(_("No certificate issuer found"));
 508         if (status & GNUTLS_CERT_SIGNER_NOT_CA)
 509                 return g_strdup(_("Certificate issuer is not a CA"));
 510
 511
 512         return NULL;
 513 }
 514 #endif
 515
 516 #if USE_OPENSSL
 517 gboolean ssl_certificate_check (X509 *x509_cert, gchar *fqdn, gchar *host, gushort port)
 518 #else
 519 gboolean ssl_certificate_check (gnutls_x509_crt x509_cert, guint status, gchar *fqdn, gchar *host, gushort port)
 520 #endif
 521 {
 522         SSLCertificate *current_cert = NULL;
 523         SSLCertificate *known_cert;
 524         SSLCertHookData cert_hook_data;
 525         gchar *fqdn_host = NULL;
 526         gchar *fingerprint;
 527         unsigned int n;
 528         unsigned char md[128];
 529
 530         if (fqdn)
 531                 fqdn_host = g_strdup(fqdn);
 532         else if (host)
 533                 fqdn_host = get_fqdn(host);
 534         else {
 535                 g_warning("no host!\n");
 536                 return FALSE;
 537         }
 538
 539         current_cert = ssl_certificate_new_lookup(x509_cert, fqdn_host, port, FALSE);
 540
 541         if (current_cert == NULL) {
 542                 debug_print("Buggy certificate !\n");
 543                 g_free(fqdn_host);
 544                 return FALSE;
 545         }
 546
 547 #if USE_GNUTLS
 548         current_cert->status = status;
 549 #endif
 550         /* fingerprint */
 551 #if USE_OPENSSL
 552         X509_digest(x509_cert, EVP_md5(), md, &n);
 553         fingerprint = readable_fingerprint(md, (int)n);
 554 #else
 555         n = 128;
 556         gnutls_x509_crt_get_fingerprint(x509_cert, GNUTLS_DIG_MD5, md, &n);
 557         fingerprint = readable_fingerprint(md, (int)n);
 558 #endif
 559
 560         known_cert = ssl_certificate_find_lookup (fqdn_host, port, fingerprint, FALSE);
 561
 562         g_free(fingerprint);
 563         g_free(fqdn_host);
 564
 565         if (known_cert == NULL) {
 566                 cert_hook_data.cert = current_cert;
 567                 cert_hook_data.old_cert = NULL;
 568                 cert_hook_data.expired = FALSE;
 569                 cert_hook_data.accept = FALSE;
 570
 571                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 572
 573                 if (!cert_hook_data.accept) {
 574                         ssl_certificate_destroy(current_cert);
 575                         return FALSE;
 576                 } else {
 577                         ssl_certificate_save(current_cert);
 578                         ssl_certificate_destroy(current_cert);
 579                         return TRUE;
 580                 }
 581         } else if (!ssl_certificate_compare (current_cert, known_cert)) {
 582                 cert_hook_data.cert = current_cert;
 583                 cert_hook_data.old_cert = known_cert;
 584                 cert_hook_data.expired = FALSE;
 585                 cert_hook_data.accept = FALSE;
 586
 587                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 588
 589                 if (!cert_hook_data.accept) {
 590                         ssl_certificate_destroy(current_cert);
 591                         ssl_certificate_destroy(known_cert);
 592                         return FALSE;
 593                 } else {
 594                         ssl_certificate_save(current_cert);
 595                         ssl_certificate_destroy(current_cert);
 596                         ssl_certificate_destroy(known_cert);
 597                         return TRUE;
 598                 }
 599 #if USE_OPENSSL
 600         } else if (asn1toTime(X509_get_notAfter(current_cert->x509_cert)) < time(NULL)) {
 601 #else
 602         } else if (gnutls_x509_crt_get_expiration_time(current_cert->x509_cert) < time(NULL)) {
 603 #endif
 604                 gchar *tmp = g_strdup_printf("%s:%d", current_cert->host, current_cert->port);
 605
 606                 if (warned_expired == NULL)
 607                         warned_expired = g_hash_table_new(g_str_hash, g_str_equal);
 608
 609                 if (g_hash_table_lookup(warned_expired, tmp)) {
 610                         g_free(tmp);
 611                         ssl_certificate_destroy(current_cert);
 612                         ssl_certificate_destroy(known_cert);
 613                         return TRUE;
 614                 }
 615
 616                 cert_hook_data.cert = current_cert;
 617                 cert_hook_data.old_cert = NULL;
 618                 cert_hook_data.expired = TRUE;
 619                 cert_hook_data.accept = FALSE;
 620
 621                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 622
 623                 if (!cert_hook_data.accept) {
 624                         g_free(tmp);
 625                         ssl_certificate_destroy(current_cert);
 626                         ssl_certificate_destroy(known_cert);
 627                         return FALSE;
 628                 } else {
 629                         g_hash_table_insert(warned_expired, tmp, GINT_TO_POINTER(1));
 630                         ssl_certificate_destroy(current_cert);
 631                         ssl_certificate_destroy(known_cert);
 632                         return TRUE;
 633                 }
 634         }
 635
 636         ssl_certificate_destroy(current_cert);
 637         ssl_certificate_destroy(known_cert);
 638         return TRUE;
 639 }
 640
 641 #endif /* USE_OPENSSL */