[glib-openssl] Add OCSP stapling capabilities

[Ignacio Casal Quinteiro <icq src gnome org>]

commit 15dae017bca73ca254657df105be2b70ae4733f5
Author: Joakim Tosteberg <joakim tosteberg zenterio com>
Date:   Fri Mar 16 09:59:02 2018 +0100

    Add OCSP stapling capabilities
    
    Add environment variables for enabling checking of certificate
    revocation through OCSP. Policy is to allow connection in case of no
    OCSP reply.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=794476

 tls/openssl/gtlsclientconnection-openssl.c |   12 +++
 tls/openssl/gtlsconnection-openssl.c       |   38 ++++++++++
 tls/openssl/gtlsfiledatabase-openssl.c     |  110 ++++++++++++++++++++++++++++
 tls/openssl/gtlsfiledatabase-openssl.h     |    4 +
 4 files changed, 164 insertions(+), 0 deletions(-)
---
diff --git a/tls/openssl/gtlsclientconnection-openssl.c b/tls/openssl/gtlsclientconnection-openssl.c
index 7aa47ce..57e72bd 100644
--- a/tls/openssl/gtlsclientconnection-openssl.c
+++ b/tls/openssl/gtlsclientconnection-openssl.c
@@ -466,6 +466,12 @@ set_curve_list (GTlsClientConnectionOpenssl *client)
 #endif
 
 static gboolean
+use_ocsp (void)
+{
+  return g_getenv ("G_TLS_OPENSSL_OCSP_ENABLED") != NULL;
+}
+
+static gboolean
 g_tls_client_connection_openssl_initable_init (GInitable       *initable,
                                                GCancellable    *cancellable,
                                                GError         **error)
@@ -551,6 +557,12 @@ g_tls_client_connection_openssl_initable_init (GInitable       *initable,
 
   SSL_set_connect_state (priv->ssl);
 
+#if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_TLSEXT) && \
+    !defined(OPENSSL_NO_OCSP)
+  if (use_ocsp())
+    SSL_set_tlsext_status_type (priv->ssl, TLSEXT_STATUSTYPE_ocsp);
+#endif
+
   if (!g_tls_client_connection_openssl_parent_initable_iface->
       init (initable, cancellable, error))
     return FALSE;
diff --git a/tls/openssl/gtlsconnection-openssl.c b/tls/openssl/gtlsconnection-openssl.c
index acc12b6..f3ecf4c 100644
--- a/tls/openssl/gtlsconnection-openssl.c
+++ b/tls/openssl/gtlsconnection-openssl.c
@@ -29,10 +29,15 @@
 #include <stdarg.h>
 #include <openssl/ssl.h>
 #include <openssl/err.h>
+#if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_OCSP)
+#include <openssl/ocsp.h>
+#endif
+
 
 #include "gtlsconnection-openssl.h"
 #include "gtlsbackend-openssl.h"
 #include "gtlscertificate-openssl.h"
+#include "gtlsfiledatabase-openssl.h"
 #include "gtlsbio.h"
 
 #include <glib/gi18n-lib.h>
@@ -271,6 +276,36 @@ get_peer_certificate (GTlsConnectionOpenssl *openssl)
 }
 
 static GTlsCertificateFlags
+verify_ocsp_response (GTlsConnectionOpenssl *openssl,
+                      GTlsDatabase          *database,
+                      GTlsCertificate       *peer_certificate)
+{
+#if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_TLSEXT) && \
+  !defined(OPENSSL_NO_OCSP)
+  SSL *ssl = NULL;
+  OCSP_RESPONSE *resp = NULL;
+  long len = 0;
+  const unsigned char *p = NULL;
+
+  ssl = g_tls_connection_openssl_get_ssl (openssl);
+  len = SSL_get_tlsext_status_ocsp_resp (ssl, &p);
+  /* Soft fail in case of no response is the best we can do */
+  if (p == NULL)
+    return 0;
+
+  resp = d2i_OCSP_RESPONSE (NULL, &p, len);
+  if (resp == NULL)
+    return G_TLS_CERTIFICATE_GENERIC_ERROR;
+
+  return g_tls_file_database_openssl_verify_ocsp_response (database,
+                                                           peer_certificate,
+                                                           resp);
+#else
+  return 0;
+#endif
+}
+
+static GTlsCertificateFlags
 verify_peer_certificate (GTlsConnectionOpenssl *openssl,
                          GTlsCertificate       *peer_certificate)
 {
@@ -315,6 +350,9 @@ verify_peer_certificate (GTlsConnectionOpenssl *openssl,
         }
     }
 
+  if (is_client && (errors == 0))
+    errors = verify_ocsp_response (openssl, database, peer_certificate);
+
   return errors;
 }
 
diff --git a/tls/openssl/gtlsfiledatabase-openssl.c b/tls/openssl/gtlsfiledatabase-openssl.c
index 10b5df7..b80b169 100644
--- a/tls/openssl/gtlsfiledatabase-openssl.c
+++ b/tls/openssl/gtlsfiledatabase-openssl.c
@@ -29,6 +29,9 @@
 #include <gio/gio.h>
 #include <glib/gi18n-lib.h>
 #include <openssl/ssl.h>
+#if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_OCSP)
+#include <openssl/ocsp.h>
+#endif
 
 typedef struct _GTlsFileDatabaseOpensslPrivate
 {
@@ -742,3 +745,110 @@ g_tls_file_database_openssl_initable_interface_init (GInitableIface *iface)
 {
   iface->init = g_tls_file_database_openssl_initable_init;
 }
+
+GTlsCertificateFlags
+g_tls_file_database_openssl_verify_ocsp_response (GTlsDatabase    *database,
+                                                  GTlsCertificate *chain,
+                                                  OCSP_RESPONSE   *resp)
+{
+  GTlsCertificateFlags errors = 0;
+#if (OPENSSL_VERSION_NUMBER >= 0x0090808fL) && !defined(OPENSSL_NO_TLSEXT) && \
+  !defined(OPENSSL_NO_OCSP)
+  GTlsFileDatabaseOpenssl *file_database;
+  GTlsFileDatabaseOpensslPrivate *priv;
+  STACK_OF(X509) *chain_openssl = NULL;
+  X509_STORE *store = NULL;
+  OCSP_BASICRESP *basic_resp = NULL;
+  int ocsp_status = 0;
+
+  ocsp_status = OCSP_response_status (resp);
+  if (ocsp_status != OCSP_RESPONSE_STATUS_SUCCESSFUL)
+    {
+      errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+      goto end;
+    }
+
+  basic_resp = OCSP_response_get1_basic (resp);
+  if (basic_resp == NULL)
+    {
+      errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+      goto end;
+    }
+
+  chain_openssl = convert_certificate_chain_to_openssl (G_TLS_CERTIFICATE_OPENSSL (chain));
+  file_database = G_TLS_FILE_DATABASE_OPENSSL (database);
+  priv = g_tls_file_database_openssl_get_instance_private (file_database);
+  store = X509_STORE_new ();
+  if ((chain_openssl == NULL) ||
+      (file_database == NULL) ||
+      (priv == NULL) ||
+      (priv->trusted == NULL) ||
+      (store == NULL))
+    {
+      errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+      goto end;
+    }
+
+  for (int i = 0; i < sk_X509_num (priv->trusted); i++)
+    {
+      X509_STORE_add_cert (store, sk_X509_value (priv->trusted, i));
+    }
+
+  if (OCSP_basic_verify (basic_resp, chain_openssl, store, 0) <= 0)
+    {
+      errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+      goto end;
+    }
+
+  for (int i = 0; i < OCSP_resp_count (basic_resp); i++)
+    {
+      OCSP_SINGLERESP *single_resp = OCSP_resp_get0 (basic_resp, i);
+      ASN1_GENERALIZEDTIME *revocation_time = NULL;
+      ASN1_GENERALIZEDTIME *this_update_time = NULL;
+      ASN1_GENERALIZEDTIME *next_update_time = NULL;
+      int crl_reason = 0;
+      int cert_status = 0;
+
+      if (single_resp == NULL)
+        continue;
+
+      cert_status = OCSP_single_get0_status (single_resp,
+                                             &crl_reason,
+                                             &revocation_time,
+                                             &this_update_time,
+                                             &next_update_time);
+      if (!OCSP_check_validity (this_update_time,
+                                next_update_time,
+                                300L,
+                                -1L))
+        {
+          errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+          goto end;
+        }
+
+      switch (cert_status)
+        {
+        case V_OCSP_CERTSTATUS_GOOD:
+          break;
+        case V_OCSP_CERTSTATUS_REVOKED:
+          errors = G_TLS_CERTIFICATE_REVOKED;
+          goto end;
+        case V_OCSP_CERTSTATUS_UNKNOWN:
+          errors = G_TLS_CERTIFICATE_GENERIC_ERROR;
+          goto end;
+        }
+    }
+
+end:
+  if (store != NULL)
+    X509_STORE_free (store);
+
+  if (basic_resp != NULL)
+    OCSP_BASICRESP_free (basic_resp);
+
+  if (resp != NULL)
+    OCSP_RESPONSE_free (resp);
+
+#endif
+  return errors;
+}
diff --git a/tls/openssl/gtlsfiledatabase-openssl.h b/tls/openssl/gtlsfiledatabase-openssl.h
index 2d3ccfb..ebb200f 100644
--- a/tls/openssl/gtlsfiledatabase-openssl.h
+++ b/tls/openssl/gtlsfiledatabase-openssl.h
@@ -57,6 +57,10 @@ struct _GTlsFileDatabaseOpenssl
 
 GType                        g_tls_file_database_openssl_get_type              (void) G_GNUC_CONST;
 
+GTlsCertificateFlags         g_tls_file_database_openssl_verify_ocsp_response  (GTlsDatabase    *database,
+                                                                                GTlsCertificate *chain,
+                                                                                OCSP_RESPONSE   *resp);
+
 G_END_DECLS
 
 #endif /* __G_TLS_FILE_DATABASE_OPENSSL_H___ */