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 #ifdef G_OS_WIN32
  41 #include "winsock2.h"
  42 #endif
  43 #include "ssl_certificate.h"
  44 #include "utils.h"
  45 #include "log.h"
  46 #include "socket.h"
  47 #include "hooks.h"
  48 #include "defs.h"
  49
  50 static GHashTable *warned_expired = NULL;
  51
  52 gboolean prefs_common_unsafe_ssl_certs(void);
  53
  54 static gchar *get_certificate_path(const gchar *host, const gchar *port, const gchar *fp)
  55 {
  56         if (fp != NULL && prefs_common_unsafe_ssl_certs())
  57                 return g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
  58                           "certs", G_DIR_SEPARATOR_S,
  59                           host, ".", port, ".", fp, ".cert", NULL);
  60         else
  61                 return g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
  62                           "certs", G_DIR_SEPARATOR_S,
  63                           host, ".", port, ".cert", NULL);
  64 }
  65
  66 #if USE_OPENSSL
  67 static SSLCertificate *ssl_certificate_new_lookup(X509 *x509_cert, gchar *host, gushort port, gboolean lookup);
  68 #else
  69 static SSLCertificate *ssl_certificate_new_lookup(gnutls_x509_crt x509_cert, gchar *host, gushort port, gboolean lookup);
  70 #endif
  71 #if USE_OPENSSL
  72 /* from Courier */
  73 time_t asn1toTime(ASN1_TIME *asn1Time)
  74 {
  75         struct tm tm;
  76         int offset;
  77
  78         if (asn1Time == NULL || asn1Time->length < 13)
  79                 return 0;
  80
  81         memset(&tm, 0, sizeof(tm));
  82
  83 #define N2(n)   ((asn1Time->data[n]-'0')*10 + asn1Time->data[(n)+1]-'0')
  84
  85 #define CPY(f,n) (tm.f=N2(n))
  86
  87         CPY(tm_year,0);
  88
  89         if(tm.tm_year < 50)
  90                 tm.tm_year += 100; /* Sux */
  91
  92         CPY(tm_mon, 2);
  93         --tm.tm_mon;
  94         CPY(tm_mday, 4);
  95         CPY(tm_hour, 6);
  96         CPY(tm_min, 8);
  97         CPY(tm_sec, 10);
  98
  99         offset=0;
 100
 101         if (asn1Time->data[12] != 'Z')
 102         {
 103                 if (asn1Time->length < 17)
 104                         return 0;
 105
 106                 offset=N2(13)*3600+N2(15)*60;
 107
 108                 if (asn1Time->data[12] == '-')
 109                         offset= -offset;
 110         }
 111
 112 #undef N2
 113 #undef CPY
 114
 115         return mktime(&tm)-offset;
 116 }
 117 #endif
 118
 119 static char * get_fqdn(char *host)
 120 {
 121         struct hostent *hp;
 122
 123         if (host == NULL || strlen(host) == 0)
 124                 return g_strdup("");
 125
 126         hp = my_gethostbyname(host);
 127         if (hp == NULL)
 128                 return g_strdup(host); /*caller should free*/
 129         else
 130                 return g_strdup(hp->h_name);
 131 }
 132
 133 char * readable_fingerprint(unsigned char *src, int len)
 134 {
 135         int i=0;
 136         char * ret;
 137
 138         if (src == NULL)
 139                 return NULL;
 140         ret = g_strdup("");
 141         while (i < len) {
 142                 char *tmp2;
 143                 if(i>0)
 144                         tmp2 = g_strdup_printf("%s:%02X", ret, src[i]);
 145                 else
 146                         tmp2 = g_strdup_printf("%02X", src[i]);
 147                 g_free(ret);
 148                 ret = g_strdup(tmp2);
 149                 g_free(tmp2);
 150                 i++;
 151         }
 152         return ret;
 153 }
 154
 155 #if USE_GNUTLS
 156 static gnutls_x509_crt x509_crt_copy(gnutls_x509_crt src)
 157 {
 158     int ret;
 159     size_t size;
 160     gnutls_datum tmp;
 161     gnutls_x509_crt dest;
 162
 163     if (gnutls_x509_crt_init(&dest) != 0) {
 164         g_warning("couldn't gnutls_x509_crt_init\n");
 165         return NULL;
 166     }
 167
 168     if (gnutls_x509_crt_export(src, GNUTLS_X509_FMT_DER, NULL, &size)
 169         != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 170         g_warning("couldn't gnutls_x509_crt_export to get size\n");
 171         gnutls_x509_crt_deinit(dest);
 172         return NULL;
 173     }
 174
 175     tmp.data = malloc(size);
 176     memset(tmp.data, 0, size);
 177     ret = gnutls_x509_crt_export(src, GNUTLS_X509_FMT_DER, tmp.data, &size);
 178     if (ret == 0) {
 179         tmp.size = size;
 180         ret = gnutls_x509_crt_import(dest, &tmp, GNUTLS_X509_FMT_DER);
 181         if (ret) {
 182                 g_warning("couldn't gnutls_x509_crt_import for real (%d %s)\n", ret, gnutls_strerror(ret));
 183                 gnutls_x509_crt_deinit(dest);
 184                 dest = NULL;
 185         }
 186     } else {
 187         g_warning("couldn't gnutls_x509_crt_export for real (%d %s)\n", ret, gnutls_strerror(ret));
 188         gnutls_x509_crt_deinit(dest);
 189         dest = NULL;
 190     }
 191
 192     free(tmp.data);
 193     return dest;
 194 }
 195 #endif
 196
 197 #if USE_OPENSSL
 198 static SSLCertificate *ssl_certificate_new_lookup(X509 *x509_cert, gchar *host, gushort port, gboolean lookup)
 199 #else
 200 static SSLCertificate *ssl_certificate_new_lookup(gnutls_x509_crt x509_cert, gchar *host, gushort port, gboolean lookup)
 201 #endif
 202 {
 203         SSLCertificate *cert = g_new0(SSLCertificate, 1);
 204         unsigned int n;
 205         unsigned char md[128];
 206
 207         if (host == NULL || x509_cert == NULL) {
 208                 ssl_certificate_destroy(cert);
 209                 return NULL;
 210         }
 211 #if USE_OPENSSL
 212         cert->x509_cert = X509_dup(x509_cert);
 213 #else
 214         cert->x509_cert = x509_crt_copy(x509_cert);
 215         cert->status = (guint)-1;
 216 #endif
 217         if (lookup)
 218                 cert->host = get_fqdn(host);
 219         else
 220                 cert->host = g_strdup(host);
 221         cert->port = port;
 222
 223         /* fingerprint */
 224 #if USE_OPENSSL
 225         X509_digest(cert->x509_cert, EVP_md5(), md, &n);
 226         cert->fingerprint = readable_fingerprint(md, (int)n);
 227 #else
 228         gnutls_x509_crt_get_fingerprint(cert->x509_cert, GNUTLS_DIG_MD5, md, &n);
 229         cert->fingerprint = readable_fingerprint(md, (int)n);
 230 #endif
 231         return cert;
 232 }
 233
 234 #ifdef USE_GNUTLS
 235 static void i2d_X509_fp(FILE *fp, gnutls_x509_crt x509_cert)
 236 {
 237         char output[10*1024];
 238         size_t cert_size = 10*1024;
 239         int r;
 240
 241         if ((r = gnutls_x509_crt_export(x509_cert, GNUTLS_X509_FMT_DER, output, &cert_size)) < 0) {
 242                 g_warning("couldn't export cert %s (%d)\n", gnutls_strerror(r), cert_size);
 243                 return;
 244         }
 245         debug_print("writing %zd bytes\n",cert_size);
 246         if (fwrite(&output, 1, cert_size, fp) < cert_size) {
 247                 g_warning("failed to write cert\n");
 248         }
 249 }
 250 static gnutls_x509_crt d2i_X509_fp(FILE *fp, int unused)
 251 {
 252         gnutls_x509_crt cert = NULL;
 253         gnutls_datum tmp;
 254         struct stat s;
 255         int r;
 256         if (fstat(fileno(fp), &s) < 0) {
 257                 perror("fstat");
 258                 return NULL;
 259         }
 260         tmp.data = malloc(s.st_size);
 261         memset(tmp.data, 0, s.st_size);
 262         tmp.size = s.st_size;
 263         if (fread (tmp.data, 1, s.st_size, fp) < s.st_size) {
 264                 perror("fread");
 265                 return NULL;
 266         }
 267
 268         gnutls_x509_crt_init(&cert);
 269         if ((r = gnutls_x509_crt_import(cert, &tmp, GNUTLS_X509_FMT_DER)) < 0) {
 270                 g_warning("import failed: %s\n", gnutls_strerror(r));
 271                 gnutls_x509_crt_deinit(cert);
 272                 cert = NULL;
 273         }
 274         debug_print("got cert! %p\n", cert);
 275         return cert;
 276 }
 277 #endif
 278
 279 static void ssl_certificate_save (SSLCertificate *cert)
 280 {
 281         gchar *file, *port;
 282         FILE *fp;
 283
 284         file = g_strconcat(get_rc_dir(), G_DIR_SEPARATOR_S,
 285                           "certs", G_DIR_SEPARATOR_S, NULL);
 286
 287         if (!is_dir_exist(file))
 288                 make_dir_hier(file);
 289         g_free(file);
 290
 291         port = g_strdup_printf("%d", cert->port);
 292         file = get_certificate_path(cert->host, port, cert->fingerprint);
 293
 294         g_free(port);
 295         fp = g_fopen(file, "wb");
 296         if (fp == NULL) {
 297                 g_free(file);
 298                 debug_print("Can't save certificate !\n");
 299                 return;
 300         }
 301         i2d_X509_fp(fp, cert->x509_cert);
 302         g_free(file);
 303         fclose(fp);
 304
 305 }
 306
 307 void ssl_certificate_destroy(SSLCertificate *cert)
 308 {
 309         if (cert == NULL)
 310                 return;
 311
 312         if (cert->x509_cert)
 313 #if USE_OPENSSL
 314                 X509_free(cert->x509_cert);
 315 #else
 316                 gnutls_x509_crt_deinit(cert->x509_cert);
 317 #endif
 318         g_free(cert->host);
 319         g_free(cert->fingerprint);
 320         g_free(cert);
 321         cert = NULL;
 322 }
 323
 324 void ssl_certificate_delete_from_disk(SSLCertificate *cert)
 325 {
 326         gchar *buf;
 327         gchar *file;
 328         buf = g_strdup_printf("%d", cert->port);
 329         file = get_certificate_path(cert->host, buf, cert->fingerprint);
 330         g_unlink (file);
 331         g_free(file);
 332         g_free(buf);
 333 }
 334
 335 SSLCertificate *ssl_certificate_find (gchar *host, gushort port, const gchar *fingerprint)
 336 {
 337         return ssl_certificate_find_lookup (host, port, fingerprint, TRUE);
 338 }
 339
 340 SSLCertificate *ssl_certificate_find_lookup (gchar *host, gushort port, const gchar *fingerprint, gboolean lookup)
 341 {
 342         gchar *file = NULL;
 343         gchar *buf;
 344         gchar *fqdn_host;
 345         SSLCertificate *cert = NULL;
 346 #if USE_OPENSSL
 347         X509 *tmp_x509;
 348 #else
 349         gnutls_x509_crt tmp_x509;
 350 #endif
 351         FILE *fp = NULL;
 352         gboolean must_rename = FALSE;
 353
 354         if (lookup)
 355                 fqdn_host = get_fqdn(host);
 356         else
 357                 fqdn_host = g_strdup(host);
 358
 359         buf = g_strdup_printf("%d", port);
 360
 361         if (fingerprint != NULL) {
 362                 file = get_certificate_path(fqdn_host, buf, fingerprint);
 363                 fp = g_fopen(file, "rb");
 364         }
 365         if (fp == NULL) {
 366                 /* see if we have the old one */
 367                 debug_print("didn't get %s\n", file);
 368                 g_free(file);
 369                 file = get_certificate_path(fqdn_host, buf, NULL);
 370                 fp = g_fopen(file, "rb");
 371
 372                 if (fp) {
 373                         debug_print("got %s\n", file);
 374                         must_rename = (fingerprint != NULL);
 375                 }
 376         } else {
 377                 debug_print("got %s first try\n", file);
 378         }
 379         if (fp == NULL) {
 380                 g_free(file);
 381                 g_free(fqdn_host);
 382                 g_free(buf);
 383                 return NULL;
 384         }
 385
 386         if ((tmp_x509 = d2i_X509_fp(fp, 0)) != NULL) {
 387                 cert = ssl_certificate_new_lookup(tmp_x509, fqdn_host, port, lookup);
 388                 debug_print("got cert %p\n", cert);
 389 #if USE_OPENSSL
 390                 X509_free(tmp_x509);
 391 #else
 392                 gnutls_x509_crt_deinit(tmp_x509);
 393 #endif
 394         }
 395         fclose(fp);
 396         g_free(file);
 397
 398         if (must_rename) {
 399                 gchar *old = get_certificate_path(fqdn_host, buf, NULL);
 400                 gchar *new = get_certificate_path(fqdn_host, buf, fingerprint);
 401                 if (strcmp(old, new))
 402                         move_file(old, new, TRUE);
 403                 g_free(old);
 404                 g_free(new);
 405         }
 406         g_free(buf);
 407         g_free(fqdn_host);
 408
 409         return cert;
 410 }
 411
 412 static gboolean ssl_certificate_compare (SSLCertificate *cert_a, SSLCertificate *cert_b)
 413 {
 414 #ifdef USE_OPENSSL
 415         if (cert_a == NULL || cert_b == NULL)
 416                 return FALSE;
 417         else if (!X509_cmp(cert_a->x509_cert, cert_b->x509_cert))
 418                 return TRUE;
 419         else
 420                 return FALSE;
 421 #else
 422         char *output_a;
 423         char *output_b;
 424         size_t cert_size_a = 0, cert_size_b = 0;
 425         int r;
 426
 427         if (cert_a == NULL || cert_b == NULL)
 428                 return FALSE;
 429
 430         if ((r = gnutls_x509_crt_export(cert_a->x509_cert, GNUTLS_X509_FMT_DER, NULL, &cert_size_a))
 431             != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 432                 g_warning("couldn't gnutls_x509_crt_export to get size a %s\n", gnutls_strerror(r));
 433                 return FALSE;
 434         }
 435
 436         if ((r = gnutls_x509_crt_export(cert_b->x509_cert, GNUTLS_X509_FMT_DER, NULL, &cert_size_b))
 437             != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 438                 g_warning("couldn't gnutls_x509_crt_export to get size b %s\n", gnutls_strerror(r));
 439                 return FALSE;
 440         }
 441
 442         output_a = malloc(cert_size_a);
 443         output_b = malloc(cert_size_b);
 444         if ((r = gnutls_x509_crt_export(cert_a->x509_cert, GNUTLS_X509_FMT_DER, output_a, &cert_size_a)) < 0) {
 445                 g_warning("couldn't gnutls_x509_crt_export a %s\n", gnutls_strerror(r));
 446                 return FALSE;
 447         }
 448         if ((r = gnutls_x509_crt_export(cert_b->x509_cert, GNUTLS_X509_FMT_DER, output_b, &cert_size_b)) < 0) {
 449                 g_warning("couldn't gnutls_x509_crt_export b %s\n", gnutls_strerror(r));
 450                 return FALSE;
 451         }
 452         if (cert_size_a != cert_size_b) {
 453                 g_warning("size differ %d %d\n", cert_size_a, cert_size_b);
 454                 return FALSE;
 455         }
 456         if (memcmp(output_a, output_b, cert_size_a)) {
 457                 g_warning("contents differ\n");
 458                 return FALSE;
 459         }
 460
 461         return TRUE;
 462 #endif
 463 }
 464
 465 #if USE_OPENSSL
 466 char *ssl_certificate_check_signer (X509 *cert)
 467 {
 468         X509_STORE_CTX store_ctx;
 469         X509_STORE *store;
 470         char *err_msg = NULL;
 471
 472         store = X509_STORE_new();
 473         if (store == NULL) {
 474                 g_print("Can't create X509_STORE\n");
 475                 return NULL;
 476         }
 477         if (!X509_STORE_set_default_paths(store)) {
 478                 X509_STORE_free (store);
 479                 return g_strdup(_("Couldn't load X509 default paths"));
 480         }
 481
 482         X509_STORE_CTX_init (&store_ctx, store, cert, NULL);
 483
 484         if(!X509_verify_cert (&store_ctx)) {
 485                 err_msg = g_strdup(X509_verify_cert_error_string(
 486                                         X509_STORE_CTX_get_error(&store_ctx)));
 487                 debug_print("Can't check signer: %s\n", err_msg);
 488                 X509_STORE_CTX_cleanup (&store_ctx);
 489                 X509_STORE_free (store);
 490                 return err_msg;
 491
 492         }
 493         X509_STORE_CTX_cleanup (&store_ctx);
 494         X509_STORE_free (store);
 495         return NULL;
 496 }
 497 #else
 498 char *ssl_certificate_check_signer (gnutls_x509_crt cert, guint status)
 499 {
 500         if (status == (guint)-1)
 501                 return g_strdup(_("Uncheckable"));
 502
 503         if (status & GNUTLS_CERT_INVALID) {
 504                 if (gnutls_x509_crt_check_issuer(cert, cert))
 505                         return g_strdup(_("Self-signed certificate"));
 506         }
 507         if (status & GNUTLS_CERT_REVOKED)
 508                 return g_strdup(_("Revoked certificate"));
 509         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
 510                 return g_strdup(_("No certificate issuer found"));
 511         if (status & GNUTLS_CERT_SIGNER_NOT_CA)
 512                 return g_strdup(_("Certificate issuer is not a CA"));
 513
 514
 515         return NULL;
 516 }
 517 #endif
 518
 519 #if USE_OPENSSL
 520 gboolean ssl_certificate_check (X509 *x509_cert, gchar *fqdn, gchar *host, gushort port)
 521 #else
 522 gboolean ssl_certificate_check (gnutls_x509_crt x509_cert, guint status, gchar *fqdn, gchar *host, gushort port)
 523 #endif
 524 {
 525         SSLCertificate *current_cert = NULL;
 526         SSLCertificate *known_cert;
 527         SSLCertHookData cert_hook_data;
 528         gchar *fqdn_host = NULL;
 529         gchar *fingerprint;
 530         unsigned int n;
 531         unsigned char md[128];
 532
 533         if (fqdn)
 534                 fqdn_host = g_strdup(fqdn);
 535         else if (host)
 536                 fqdn_host = get_fqdn(host);
 537         else {
 538                 g_warning("no host!\n");
 539                 return FALSE;
 540         }
 541
 542         current_cert = ssl_certificate_new_lookup(x509_cert, fqdn_host, port, FALSE);
 543
 544         if (current_cert == NULL) {
 545                 debug_print("Buggy certificate !\n");
 546                 g_free(fqdn_host);
 547                 return FALSE;
 548         }
 549
 550 #if USE_GNUTLS
 551         current_cert->status = status;
 552 #endif
 553         /* fingerprint */
 554 #if USE_OPENSSL
 555         X509_digest(x509_cert, EVP_md5(), md, &n);
 556         fingerprint = readable_fingerprint(md, (int)n);
 557 #else
 558         n = 128;
 559         gnutls_x509_crt_get_fingerprint(x509_cert, GNUTLS_DIG_MD5, md, &n);
 560         fingerprint = readable_fingerprint(md, (int)n);
 561 #endif
 562
 563         known_cert = ssl_certificate_find_lookup (fqdn_host, port, fingerprint, FALSE);
 564
 565         g_free(fingerprint);
 566         g_free(fqdn_host);
 567
 568         if (known_cert == NULL) {
 569                 cert_hook_data.cert = current_cert;
 570                 cert_hook_data.old_cert = NULL;
 571                 cert_hook_data.expired = FALSE;
 572                 cert_hook_data.accept = FALSE;
 573
 574                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 575
 576                 if (!cert_hook_data.accept) {
 577                         ssl_certificate_destroy(current_cert);
 578                         return FALSE;
 579                 } else {
 580                         ssl_certificate_save(current_cert);
 581                         ssl_certificate_destroy(current_cert);
 582                         return TRUE;
 583                 }
 584         } else if (!ssl_certificate_compare (current_cert, known_cert)) {
 585                 cert_hook_data.cert = current_cert;
 586                 cert_hook_data.old_cert = known_cert;
 587                 cert_hook_data.expired = FALSE;
 588                 cert_hook_data.accept = FALSE;
 589
 590                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 591
 592                 if (!cert_hook_data.accept) {
 593                         ssl_certificate_destroy(current_cert);
 594                         ssl_certificate_destroy(known_cert);
 595                         return FALSE;
 596                 } else {
 597                         ssl_certificate_save(current_cert);
 598                         ssl_certificate_destroy(current_cert);
 599                         ssl_certificate_destroy(known_cert);
 600                         return TRUE;
 601                 }
 602 #if USE_OPENSSL
 603         } else if (asn1toTime(X509_get_notAfter(current_cert->x509_cert)) < time(NULL)) {
 604 #else
 605         } else if (gnutls_x509_crt_get_expiration_time(current_cert->x509_cert) < time(NULL)) {
 606 #endif
 607                 gchar *tmp = g_strdup_printf("%s:%d", current_cert->host, current_cert->port);
 608
 609                 if (warned_expired == NULL)
 610                         warned_expired = g_hash_table_new(g_str_hash, g_str_equal);
 611
 612                 if (g_hash_table_lookup(warned_expired, tmp)) {
 613                         g_free(tmp);
 614                         ssl_certificate_destroy(current_cert);
 615                         ssl_certificate_destroy(known_cert);
 616                         return TRUE;
 617                 }
 618
 619                 cert_hook_data.cert = current_cert;
 620                 cert_hook_data.old_cert = NULL;
 621                 cert_hook_data.expired = TRUE;
 622                 cert_hook_data.accept = FALSE;
 623
 624                 hooks_invoke(SSLCERT_ASK_HOOKLIST, &cert_hook_data);
 625
 626                 if (!cert_hook_data.accept) {
 627                         g_free(tmp);
 628                         ssl_certificate_destroy(current_cert);
 629                         ssl_certificate_destroy(known_cert);
 630                         return FALSE;
 631                 } else {
 632                         g_hash_table_insert(warned_expired, tmp, GINT_TO_POINTER(1));
 633                         ssl_certificate_destroy(current_cert);
 634                         ssl_certificate_destroy(known_cert);
 635                         return TRUE;
 636                 }
 637         }
 638
 639         ssl_certificate_destroy(current_cert);
 640         ssl_certificate_destroy(known_cert);
 641         return TRUE;
 642 }
 643
 644 #endif /* USE_OPENSSL */