libempathy/empathy-tls-verifier.c

   1 /*
   2  * empathy-tls-verifier.c - Source for EmpathyTLSVerifier
   3  * Copyright (C) 2010 Collabora Ltd.
   4  * @author Cosimo Cecchi <cosimo.cecchi@collabora.co.uk>
   5  * @author Stef Walter <stefw@collabora.co.uk>
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include <gnutls/gnutls.h>
  25 #include <gnutls/x509.h>
  26
  27 #include <telepathy-glib/util.h>
  28
  29 #include "empathy-tls-verifier.h"
  30
  31 #include <gcr/gcr.h>
  32
  33 #define DEBUG_FLAG EMPATHY_DEBUG_TLS
  34 #include "empathy-debug.h"
  35 #include "empathy-utils.h"
  36
  37 G_DEFINE_TYPE (EmpathyTLSVerifier, empathy_tls_verifier,
  38     G_TYPE_OBJECT)
  39
  40 #define GET_PRIV(obj) EMPATHY_GET_PRIV (obj, EmpathyTLSVerifier);
  41
  42 enum {
  43   PROP_TLS_CERTIFICATE = 1,
  44   PROP_HOSTNAME,
  45   PROP_REFERENCE_IDENTITIES,
  46
  47   LAST_PROPERTY,
  48 };
  49
  50 typedef struct {
  51   EmpathyTLSCertificate *certificate;
  52   gchar *hostname;
  53   gchar **reference_identities;
  54
  55   GSimpleAsyncResult *verify_result;
  56   GHashTable *details;
  57
  58   gboolean dispose_run;
  59 } EmpathyTLSVerifierPriv;
  60
  61 static gboolean
  62 verification_output_to_reason (gint res,
  63     guint verify_output,
  64     EmpTLSCertificateRejectReason *reason)
  65 {
  66   gboolean retval = TRUE;
  67
  68   g_assert (reason != NULL);
  69
  70   if (res != GNUTLS_E_SUCCESS)
  71     {
  72       retval = FALSE;
  73
  74       /* the certificate is not structurally valid */
  75       switch (res)
  76         {
  77         case GNUTLS_E_INSUFFICIENT_CREDENTIALS:
  78           *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_UNTRUSTED;
  79           break;
  80         case GNUTLS_E_CONSTRAINT_ERROR:
  81           *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_LIMIT_EXCEEDED;
  82           break;
  83         default:
  84           *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_UNKNOWN;
  85           break;
  86         }
  87
  88       goto out;
  89     }
  90
  91   /* the certificate is structurally valid, check for other errors. */
  92   if (verify_output & GNUTLS_CERT_INVALID)
  93     {
  94       retval = FALSE;
  95
  96       if (verify_output & GNUTLS_CERT_SIGNER_NOT_FOUND)
  97         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_SELF_SIGNED;
  98       else if (verify_output & GNUTLS_CERT_SIGNER_NOT_CA)
  99         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_UNTRUSTED;
 100       else if (verify_output & GNUTLS_CERT_INSECURE_ALGORITHM)
 101         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_INSECURE;
 102       else if (verify_output & GNUTLS_CERT_NOT_ACTIVATED)
 103         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_NOT_ACTIVATED;
 104       else if (verify_output & GNUTLS_CERT_EXPIRED)
 105         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_EXPIRED;
 106       else
 107         *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_UNKNOWN;
 108
 109       goto out;
 110     }
 111
 112  out:
 113   return retval;
 114 }
 115
 116 static void
 117 build_certificate_list_for_gnutls (GcrCertificateChain *chain,
 118         gnutls_x509_crt_t **list,
 119         guint *n_list,
 120         gnutls_x509_crt_t **anchors,
 121         guint *n_anchors)
 122 {
 123   GcrCertificate *cert;
 124   guint idx, length;
 125   gnutls_x509_crt_t *retval;
 126   gnutls_x509_crt_t gcert;
 127   gnutls_datum_t datum;
 128   gsize n_data;
 129
 130   g_assert (list);
 131   g_assert (n_list);
 132   g_assert (anchors);
 133   g_assert (n_anchors);
 134
 135   *list = *anchors = NULL;
 136   *n_list = *n_anchors = 0;
 137
 138   length = gcr_certificate_chain_get_length (chain);
 139   retval = g_malloc0 (sizeof (gnutls_x509_crt_t) * length);
 140
 141   /* Convert the main body of the chain to gnutls */
 142   for (idx = 0; idx < length; ++idx)
 143     {
 144       cert = gcr_certificate_chain_get_certificate (chain, idx);
 145       datum.data = (gpointer)gcr_certificate_get_der_data (cert, &n_data);
 146       datum.size = n_data;
 147
 148       gnutls_x509_crt_init (&gcert);
 149       if (gnutls_x509_crt_import (gcert, &datum, GNUTLS_X509_FMT_DER) < 0)
 150         g_return_if_reached ();
 151
 152       retval[idx] = gcert;
 153     }
 154
 155   *list = retval;
 156   *n_list = length;
 157
 158   /* See if we have an anchor */
 159   if (gcr_certificate_chain_get_status (chain) ==
 160           GCR_CERTIFICATE_CHAIN_ANCHORED)
 161     {
 162       cert = gcr_certificate_chain_get_anchor (chain);
 163       g_return_if_fail (cert);
 164
 165       datum.data = (gpointer)gcr_certificate_get_der_data (cert, &n_data);
 166       datum.size = n_data;
 167
 168       gnutls_x509_crt_init (&gcert);
 169       if (gnutls_x509_crt_import (gcert, &datum, GNUTLS_X509_FMT_DER) < 0)
 170         g_return_if_reached ();
 171
 172       retval = g_malloc0 (sizeof (gnutls_x509_crt_t) * 1);
 173       retval[0] = gcert;
 174       *anchors = retval;
 175       *n_anchors = 1;
 176     }
 177 }
 178
 179 static void
 180 free_certificate_list_for_gnutls (gnutls_x509_crt_t *list,
 181         guint n_list)
 182 {
 183   guint idx;
 184
 185   for (idx = 0; idx < n_list; idx++)
 186     gnutls_x509_crt_deinit (list[idx]);
 187   g_free (list);
 188 }
 189
 190 static void
 191 complete_verification (EmpathyTLSVerifier *self)
 192 {
 193   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 194
 195   DEBUG ("Verification successful, completing...");
 196
 197   g_simple_async_result_complete_in_idle (priv->verify_result);
 198
 199   tp_clear_object (&priv->verify_result);
 200 }
 201
 202 static void
 203 abort_verification (EmpathyTLSVerifier *self,
 204     EmpTLSCertificateRejectReason reason)
 205 {
 206   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 207
 208   DEBUG ("Verification error %u, aborting...", reason);
 209
 210   g_simple_async_result_set_error (priv->verify_result,
 211       G_IO_ERROR, reason, "TLS verification failed with reason %u",
 212       reason);
 213   g_simple_async_result_complete_in_idle (priv->verify_result);
 214
 215   tp_clear_object (&priv->verify_result);
 216 }
 217
 218 static void
 219 debug_certificate (GcrCertificate *cert)
 220 {
 221     gchar *subject = gcr_certificate_get_subject_dn (cert);
 222     DEBUG ("Certificate: %s", subject);
 223     g_free (subject);
 224 }
 225
 226 static void
 227 debug_certificate_chain (GcrCertificateChain *chain)
 228 {
 229     GEnumClass *enum_class;
 230     GEnumValue *enum_value;
 231     gint idx, length;
 232     GcrCertificate *cert;
 233
 234     enum_class = G_ENUM_CLASS
 235             (g_type_class_peek (GCR_TYPE_CERTIFICATE_CHAIN_STATUS));
 236     enum_value = g_enum_get_value (enum_class,
 237             gcr_certificate_chain_get_status (chain));
 238     length = gcr_certificate_chain_get_length (chain);
 239     DEBUG ("Certificate chain: length %u status %s",
 240             length, enum_value ? enum_value->value_nick : "XXX");
 241
 242     for (idx = 0; idx < length; ++idx)
 243       {
 244         cert = gcr_certificate_chain_get_certificate (chain, idx);
 245         debug_certificate (cert);
 246       }
 247 }
 248
 249 static void
 250 perform_verification (EmpathyTLSVerifier *self,
 251         GcrCertificateChain *chain)
 252 {
 253   gboolean ret = FALSE;
 254   EmpTLSCertificateRejectReason reason =
 255     EMP_TLS_CERTIFICATE_REJECT_REASON_UNKNOWN;
 256   gnutls_x509_crt_t *list, *anchors;
 257   guint n_list, n_anchors;
 258   guint verify_output;
 259   gint res;
 260   gchar **i;
 261   gboolean matched;
 262   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 263
 264   DEBUG ("Performing verification");
 265   debug_certificate_chain (chain);
 266
 267   list = anchors = NULL;
 268   n_list = n_anchors = 0;
 269
 270   /*
 271    * If the first certificate is an pinned certificate then we completely
 272    * ignore the rest of the verification process.
 273    */
 274   if (gcr_certificate_chain_get_status (chain) == GCR_CERTIFICATE_CHAIN_PINNED)
 275     {
 276       DEBUG ("Found pinned certificate for %s", priv->hostname);
 277       complete_verification (self);
 278       goto out;
 279   }
 280
 281   build_certificate_list_for_gnutls (chain, &list, &n_list,
 282           &anchors, &n_anchors);
 283   if (list == NULL || n_list == 0) {
 284       g_warn_if_reached ();
 285       abort_verification (self, EMP_TLS_CERTIFICATE_REJECT_REASON_UNKNOWN);
 286       goto out;
 287   }
 288
 289   verify_output = 0;
 290   res = gnutls_x509_crt_list_verify (list, n_list, anchors, n_anchors,
 291            NULL, 0, 0, &verify_output);
 292   ret = verification_output_to_reason (res, verify_output, &reason);
 293
 294   DEBUG ("Certificate verification gave result %d with reason %u", ret,
 295           reason);
 296
 297   if (!ret) {
 298       abort_verification (self, reason);
 299       goto out;
 300   }
 301
 302   /* now check if the certificate matches one of the reference identities. */
 303   for (i = priv->reference_identities, matched = FALSE; i && *i; ++i)
 304     {
 305       const gchar *identity = *i;
 306       if (gnutls_x509_crt_check_hostname (list[0], identity) == 1)
 307         {
 308           matched = TRUE;
 309           break;
 310         }
 311     }
 312
 313   if (!matched)
 314     {
 315       gchar *certified_hostname;
 316
 317       certified_hostname = empathy_get_x509_certificate_hostname (list[0]);
 318       tp_asv_set_string (priv->details,
 319           "expected-hostname", priv->hostname);
 320       tp_asv_set_string (priv->details,
 321           "certificate-hostname", certified_hostname);
 322
 323       DEBUG ("Hostname mismatch: got %s but expected %s",
 324           certified_hostname, priv->hostname);
 325
 326       g_free (certified_hostname);
 327       abort_verification (self,
 328               EMP_TLS_CERTIFICATE_REJECT_REASON_HOSTNAME_MISMATCH);
 329       goto out;
 330     }
 331
 332   DEBUG ("Hostname matched");
 333   complete_verification (self);
 334
 335  out:
 336   free_certificate_list_for_gnutls (list, n_list);
 337   free_certificate_list_for_gnutls (anchors, n_anchors);
 338 }
 339
 340 static void
 341 perform_verification_cb (GObject *object,
 342         GAsyncResult *res,
 343         gpointer user_data)
 344 {
 345   GError *error = NULL;
 346
 347   GcrCertificateChain *chain = GCR_CERTIFICATE_CHAIN (object);
 348   EmpathyTLSVerifier *self = EMPATHY_TLS_VERIFIER (user_data);
 349
 350   /* Even if building the chain fails, try verifying what we have */
 351   if (!gcr_certificate_chain_build_finish (chain, res, &error))
 352     {
 353       DEBUG ("Building of certificate chain failed: %s", error->message);
 354       g_clear_error (&error);
 355     }
 356
 357   perform_verification (self, chain);
 358
 359   /* Matches ref when staring chain build */
 360   g_object_unref (self);
 361 }
 362
 363 static void
 364 empathy_tls_verifier_get_property (GObject *object,
 365     guint property_id,
 366     GValue *value,
 367     GParamSpec *pspec)
 368 {
 369   EmpathyTLSVerifierPriv *priv = GET_PRIV (object);
 370
 371   switch (property_id)
 372     {
 373     case PROP_TLS_CERTIFICATE:
 374       g_value_set_object (value, priv->certificate);
 375       break;
 376     case PROP_HOSTNAME:
 377       g_value_set_string (value, priv->hostname);
 378       break;
 379     case PROP_REFERENCE_IDENTITIES:
 380       g_value_set_boxed (value, priv->reference_identities);
 381       break;
 382     default:
 383       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
 384       break;
 385     }
 386 }
 387
 388 static void
 389 empathy_tls_verifier_set_property (GObject *object,
 390     guint property_id,
 391     const GValue *value,
 392     GParamSpec *pspec)
 393 {
 394   EmpathyTLSVerifierPriv *priv = GET_PRIV (object);
 395
 396   switch (property_id)
 397     {
 398     case PROP_TLS_CERTIFICATE:
 399       priv->certificate = g_value_dup_object (value);
 400       break;
 401     case PROP_HOSTNAME:
 402       priv->hostname = g_value_dup_string (value);
 403       break;
 404     case PROP_REFERENCE_IDENTITIES:
 405       priv->reference_identities = g_value_dup_boxed (value);
 406       break;
 407     default:
 408       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
 409       break;
 410     }
 411 }
 412
 413 static void
 414 empathy_tls_verifier_dispose (GObject *object)
 415 {
 416   EmpathyTLSVerifierPriv *priv = GET_PRIV (object);
 417
 418   if (priv->dispose_run)
 419     return;
 420
 421   priv->dispose_run = TRUE;
 422
 423   tp_clear_object (&priv->certificate);
 424
 425   G_OBJECT_CLASS (empathy_tls_verifier_parent_class)->dispose (object);
 426 }
 427
 428 static void
 429 empathy_tls_verifier_finalize (GObject *object)
 430 {
 431   EmpathyTLSVerifierPriv *priv = GET_PRIV (object);
 432
 433   DEBUG ("%p", object);
 434
 435   tp_clear_boxed (G_TYPE_HASH_TABLE, &priv->details);
 436   g_free (priv->hostname);
 437   g_strfreev (priv->reference_identities);
 438
 439   G_OBJECT_CLASS (empathy_tls_verifier_parent_class)->finalize (object);
 440 }
 441
 442 static void
 443 empathy_tls_verifier_init (EmpathyTLSVerifier *self)
 444 {
 445   EmpathyTLSVerifierPriv *priv;
 446
 447   priv = self->priv = G_TYPE_INSTANCE_GET_PRIVATE (self,
 448       EMPATHY_TYPE_TLS_VERIFIER, EmpathyTLSVerifierPriv);
 449   priv->details = tp_asv_new (NULL, NULL);
 450 }
 451
 452 static void
 453 empathy_tls_verifier_class_init (EmpathyTLSVerifierClass *klass)
 454 {
 455   GParamSpec *pspec;
 456   GObjectClass *oclass = G_OBJECT_CLASS (klass);
 457
 458   g_type_class_add_private (klass, sizeof (EmpathyTLSVerifierPriv));
 459
 460   oclass->set_property = empathy_tls_verifier_set_property;
 461   oclass->get_property = empathy_tls_verifier_get_property;
 462   oclass->finalize = empathy_tls_verifier_finalize;
 463   oclass->dispose = empathy_tls_verifier_dispose;
 464
 465   pspec = g_param_spec_object ("certificate", "The EmpathyTLSCertificate",
 466       "The EmpathyTLSCertificate to be verified.",
 467       EMPATHY_TYPE_TLS_CERTIFICATE,
 468       G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
 469   g_object_class_install_property (oclass, PROP_TLS_CERTIFICATE, pspec);
 470
 471   pspec = g_param_spec_string ("hostname", "The hostname",
 472       "The hostname which is certified by the certificate.",
 473       NULL,
 474       G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
 475   g_object_class_install_property (oclass, PROP_HOSTNAME, pspec);
 476
 477   pspec = g_param_spec_boxed ("reference-identities",
 478       "The reference identities",
 479       "The certificate should certify one of these identities.",
 480       G_TYPE_STRV,
 481       G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
 482   g_object_class_install_property (oclass, PROP_REFERENCE_IDENTITIES, pspec);
 483 }
 484
 485 EmpathyTLSVerifier *
 486 empathy_tls_verifier_new (EmpathyTLSCertificate *certificate,
 487     const gchar *hostname, const gchar **reference_identities)
 488 {
 489   g_assert (EMPATHY_IS_TLS_CERTIFICATE (certificate));
 490   g_assert (hostname != NULL);
 491   g_assert (reference_identities != NULL);
 492
 493   return g_object_new (EMPATHY_TYPE_TLS_VERIFIER,
 494       "certificate", certificate,
 495       "hostname", hostname,
 496       "reference-identities", reference_identities,
 497       NULL);
 498 }
 499
 500 void
 501 empathy_tls_verifier_verify_async (EmpathyTLSVerifier *self,
 502     GAsyncReadyCallback callback,
 503     gpointer user_data)
 504 {
 505   GcrCertificateChain *chain;
 506   GcrCertificate *cert;
 507   GPtrArray *cert_data = NULL;
 508   GArray *data;
 509   guint idx;
 510   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 511
 512   DEBUG ("Starting verification");
 513
 514   g_return_if_fail (priv->verify_result == NULL);
 515
 516   g_object_get (priv->certificate, "cert-data", &cert_data, NULL);
 517   g_return_if_fail (cert_data);
 518
 519   priv->verify_result = g_simple_async_result_new (G_OBJECT (self),
 520       callback, user_data, NULL);
 521
 522   /* Create a certificate chain */
 523   chain = gcr_certificate_chain_new ();
 524   for (idx = 0; idx < cert_data->len; ++idx) {
 525     data = g_ptr_array_index (cert_data, idx);
 526     cert = gcr_simple_certificate_new (data->data, data->len);
 527     gcr_certificate_chain_add (chain, cert);
 528     g_object_unref (cert);
 529   }
 530
 531   gcr_certificate_chain_build_async (chain, GCR_PURPOSE_CLIENT_AUTH, priv->hostname, 0,
 532           NULL, perform_verification_cb, g_object_ref (self));
 533
 534   g_object_unref (chain);
 535   g_boxed_free (TP_ARRAY_TYPE_UCHAR_ARRAY_LIST, cert_data);
 536 }
 537
 538 gboolean
 539 empathy_tls_verifier_verify_finish (EmpathyTLSVerifier *self,
 540     GAsyncResult *res,
 541     EmpTLSCertificateRejectReason *reason,
 542     GHashTable **details,
 543     GError **error)
 544 {
 545   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 546
 547   if (g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res),
 548           error))
 549     {
 550       if (reason != NULL)
 551         *reason = (*error)->code;
 552
 553       if (details != NULL)
 554         {
 555           *details = tp_asv_new (NULL, NULL);
 556           tp_g_hash_table_update (*details, priv->details,
 557               (GBoxedCopyFunc) g_strdup,
 558               (GBoxedCopyFunc) tp_g_value_slice_dup);
 559         }
 560
 561       return FALSE;
 562     }
 563
 564   if (reason != NULL)
 565     *reason = EMP_TLS_CERTIFICATE_REJECT_REASON_UNKNOWN;
 566
 567   return TRUE;
 568 }
 569
 570 void
 571 empathy_tls_verifier_store_exception (EmpathyTLSVerifier *self)
 572 {
 573   GArray *data;
 574   GcrCertificate *cert;
 575   GPtrArray *cert_data = NULL;
 576   GError *error = NULL;
 577   EmpathyTLSVerifierPriv *priv = GET_PRIV (self);
 578
 579   g_object_get (priv->certificate, "cert-data", &cert_data, NULL);
 580   g_return_if_fail (cert_data);
 581
 582   if (!cert_data->len)
 583     {
 584       DEBUG ("No certificate to pin.");
 585       return;
 586     }
 587
 588   /* The first certificate in the chain is for the host */
 589   data = g_ptr_array_index (cert_data, 0);
 590   cert = gcr_simple_certificate_new ((gpointer)data->data, data->len);
 591
 592   DEBUG ("Storing pinned certificate:");
 593   debug_certificate (cert);
 594
 595   if (!gcr_trust_add_pinned_certificate (cert, GCR_PURPOSE_CLIENT_AUTH,
 596           priv->hostname, NULL, &error))
 597       DEBUG ("Can't store the pinned certificate: %s", error->message);
 598
 599   g_object_unref (cert);
 600   g_boxed_free (TP_ARRAY_TYPE_UCHAR_ARRAY_LIST, cert_data);
 601 }