Adding option to force client auth on the server SSL creds.

include/grpc++/server_credentials.h

@@ -64,6 +64,7 @@ struct SslServerCredentialsOptions {
   };
   grpc::string pem_root_certs;
   std::vector<PemKeyCertPair> pem_key_cert_pairs;
+  bool force_client_auth;
 };
 
 // Builds SSL ServerCredentials given SSL specific options

include/grpc/grpc_security.h

@@ -177,10 +177,13 @@ void grpc_server_credentials_release(grpc_server_credentials *creds);
    - pem_key_cert_pairs is an array private key / certificate chains of the
      server. This parameter cannot be NULL.
    - num_key_cert_pairs indicates the number of items in the private_key_files
-     and cert_chain_files parameters. It should be at least 1. */
+     and cert_chain_files parameters. It should be at least 1.
+   - force_client_auth, if set to non-zero will force the client to authenticate
+     with an SSL cert. Note that this option is ignored if pem_root_certs is
+     NULL. */
 grpc_server_credentials *grpc_ssl_server_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs);
+    size_t num_key_cert_pairs, int force_client_auth);
 
 /* Creates a fake server transport security credentials object for testing. */
 grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(

src/core/security/credentials.c

@@ -259,8 +259,10 @@ static void ssl_build_config(const char *pem_root_certs,
 
 static void ssl_build_server_config(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs, grpc_ssl_server_config *config) {
+    size_t num_key_cert_pairs, int force_client_auth,
+    grpc_ssl_server_config *config) {
   size_t i;
+  config->force_client_auth = force_client_auth;
   if (pem_root_certs != NULL) {
     ssl_copy_key_material(pem_root_certs, &config->pem_root_certs,
                           &config->pem_root_certs_size);
@@ -302,14 +304,14 @@ grpc_credentials *grpc_ssl_credentials_create(
 
 grpc_server_credentials *grpc_ssl_server_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pairs,
-    size_t num_key_cert_pairs) {
+    size_t num_key_cert_pairs, int force_client_auth) {
   grpc_ssl_server_credentials *c =
       gpr_malloc(sizeof(grpc_ssl_server_credentials));
   memset(c, 0, sizeof(grpc_ssl_server_credentials));
   c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
   c->base.vtable = &ssl_server_vtable;
   ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
-                          num_key_cert_pairs, &c->config);
+                          num_key_cert_pairs, force_client_auth, &c->config);
   return &c->base;
 }
 

src/core/security/security_connector.c

@@ -653,9 +653,10 @@ grpc_security_status grpc_ssl_server_security_connector_create(
       config->pem_private_keys_sizes,
       (const unsigned char **)config->pem_cert_chains,
       config->pem_cert_chains_sizes, config->num_key_cert_pairs,
-      config->pem_root_certs, config->pem_root_certs_size, ssl_cipher_suites(),
-      alpn_protocol_strings, alpn_protocol_string_lengths,
-      (uint16_t)num_alpn_protocols, &c->handshaker_factory);
+      config->pem_root_certs, config->pem_root_certs_size,
+      config->force_client_auth, ssl_cipher_suites(), alpn_protocol_strings,
+      alpn_protocol_string_lengths, (uint16_t)num_alpn_protocols,
+      &c->handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));

src/core/security/security_connector.h

@@ -201,6 +201,7 @@ typedef struct {
   size_t num_key_cert_pairs;
   unsigned char *pem_root_certs;
   size_t pem_root_certs_size;
+  int force_client_auth;
 } grpc_ssl_server_config;
 
 /* Creates an SSL server_security_connector.

src/core/tsi/ssl_transport_security.c

@@ -1293,8 +1293,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
     const size_t* pem_private_keys_sizes, const unsigned char** pem_cert_chains,
     const size_t* pem_cert_chains_sizes, size_t key_cert_pair_count,
     const unsigned char* pem_client_root_certs,
-    size_t pem_client_root_certs_size, const char* cipher_list,
-    const unsigned char** alpn_protocols,
+    size_t pem_client_root_certs_size, int force_client_auth,
+    const char* cipher_list, const unsigned char** alpn_protocols,
     const unsigned char* alpn_protocols_lengths, uint16_t num_alpn_protocols,
     tsi_ssl_handshaker_factory** factory) {
   tsi_ssl_server_handshaker_factory* impl = NULL;
@@ -1349,6 +1349,7 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
       if (result != TSI_OK) break;
 
       if (pem_client_root_certs != NULL) {
+        int flags = SSL_VERIFY_PEER;
         STACK_OF(X509_NAME)* root_names = NULL;
         result = ssl_ctx_load_verification_certs(
             impl->ssl_contexts[i], pem_client_root_certs,
@@ -1358,7 +1359,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
           break;
         }
         SSL_CTX_set_client_CA_list(impl->ssl_contexts[i], root_names);
-        SSL_CTX_set_verify(impl->ssl_contexts[i], SSL_VERIFY_PEER, NULL);
+        if (force_client_auth) flags |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
+        SSL_CTX_set_verify(impl->ssl_contexts[i], flags, NULL);
         /* TODO(jboeuf): Add revocation verification. */
       }
 

src/core/tsi/ssl_transport_security.h

@@ -107,10 +107,14 @@ tsi_result tsi_create_ssl_client_handshaker_factory(
    - key_cert_pair_count indicates the number of items in the private_key_files
      and cert_chain_files parameters.
    - pem_client_roots is the buffer containing the PEM encoding of the client
-     root certificates. This parameter may be NULL in which case the server
-     will not ask the client to authenticate itself with a certificate (server-
-     only authentication mode).
-   - pem_client_roots_size is the size of the associated buffer.
+     root certificates. This parameter may be NULL in which case the server will
+     not authenticate the client. If not NULL, the force_client_auth parameter
+     specifies if the server will accept only authenticated clients or both
+     authenticated and non-authenticated clients.
+   - pem_client_root_certs_size is the size of the associated buffer.
+   - force_client_auth, if set to non-zero will force the client to authenticate
+     with an SSL cert. Note that this option is ignored if pem_client_root_certs
+     is NULL or pem_client_roots_certs_size is 0
    - cipher_suites contains an optional list of the ciphers that the server
      supports. The format of this string is described in:
      https://www.openssl.org/docs/apps/ciphers.html.
@@ -131,8 +135,8 @@ tsi_result tsi_create_ssl_server_handshaker_factory(
     const size_t* pem_private_keys_sizes, const unsigned char** pem_cert_chains,
     const size_t* pem_cert_chains_sizes, size_t key_cert_pair_count,
     const unsigned char* pem_client_root_certs,
-    size_t pem_client_root_certs_size, const char* cipher_suites,
-    const unsigned char** alpn_protocols,
+    size_t pem_client_root_certs_size, int force_client_auth,
+    const char* cipher_suites, const unsigned char** alpn_protocols,
     const unsigned char* alpn_protocols_lengths, uint16_t num_alpn_protocols,
     tsi_ssl_handshaker_factory** factory);
 

src/cpp/server/secure_server_credentials.cc

@@ -51,7 +51,8 @@ std::shared_ptr<ServerCredentials> SslServerCredentials(
   }
   grpc_server_credentials* c_creds = grpc_ssl_server_credentials_create(
       options.pem_root_certs.empty() ? nullptr : options.pem_root_certs.c_str(),
-      &pem_key_cert_pairs[0], pem_key_cert_pairs.size());
+      &pem_key_cert_pairs[0], pem_key_cert_pairs.size(),
+      options.force_client_auth);
   return std::shared_ptr<ServerCredentials>(
       new SecureServerCredentials(c_creds));
 }

src/csharp/ext/grpc_csharp_ext.c

@@ -718,8 +718,9 @@ grpcsharp_ssl_server_credentials_create(
       key_cert_pairs[i].private_key = key_cert_pair_private_key_array[i];
     }
   }
+  /* TODO: Add a force_client_auth parameter and pass it here. */
   creds = grpc_ssl_server_credentials_create(pem_root_certs, key_cert_pairs,
-                                             num_key_cert_pairs);
+                                             num_key_cert_pairs, 0);
   gpr_free(key_cert_pairs);
   return creds;
 }

src/node/ext/server_credentials.cc

@@ -140,8 +140,10 @@ NAN_METHOD(ServerCredentials::CreateSsl) {
     return NanThrowTypeError("createSsl's third argument must be a Buffer");
   }
   key_cert_pair.cert_chain = ::node::Buffer::Data(args[2]);
+  // TODO Add a force_client_auth parameter and pass it as the last parameter
+  // here.
   NanReturnValue(WrapStruct(
-      grpc_ssl_server_credentials_create(root_certs, &key_cert_pair, 1)));
+      grpc_ssl_server_credentials_create(root_certs, &key_cert_pair, 1, 0)));
 }
 
 NAN_METHOD(ServerCredentials::CreateFake) {

src/php/ext/grpc/server_credentials.c

@@ -115,8 +115,10 @@ PHP_METHOD(ServerCredentials, createSsl) {
                          "createSsl expects 3 strings", 1 TSRMLS_CC);
     return;
   }
-  grpc_server_credentials *creds =
-      grpc_ssl_server_credentials_create(pem_root_certs, &pem_key_cert_pair, 1);
+  /* TODO: add a force_client_auth field in ServerCredentials and pass it as
+   * the last parameter. */
+  grpc_server_credentials *creds = grpc_ssl_server_credentials_create(
+      pem_root_certs, &pem_key_cert_pair, 1, 0);
   zval *creds_object = grpc_php_wrap_server_credentials(creds);
   RETURN_DESTROY_ZVAL(creds_object);
 }

src/python/src/grpc/_adapter/_c/types/server_credentials.c

@@ -131,8 +131,10 @@ ServerCredentials *pygrpc_ServerCredentials_ssl(
   }
 
   self = (ServerCredentials *)type->tp_alloc(type, 0);
+  /* TODO: Add a force_client_auth parameter in the python object and pass it
+     here as the last arg. */
   self->c_creds = grpc_ssl_server_credentials_create(
-      root_certs, key_cert_pairs, num_key_cert_pairs);
+      root_certs, key_cert_pairs, num_key_cert_pairs, 0);
   gpr_free(key_cert_pairs);
   return self;
 }

src/ruby/ext/grpc/rb_server_credentials.c

@@ -176,11 +176,12 @@ static VALUE grpc_rb_server_credentials_init(VALUE self, VALUE pem_root_certs,
   }
   key_cert_pair.private_key = RSTRING_PTR(pem_private_key);
   key_cert_pair.cert_chain = RSTRING_PTR(pem_cert_chain);
+  /* TODO Add a force_client_auth parameter and pass it here. */
   if (pem_root_certs == Qnil) {
-    creds = grpc_ssl_server_credentials_create(NULL, &key_cert_pair, 1);
+    creds = grpc_ssl_server_credentials_create(NULL, &key_cert_pair, 1, 0);
   } else {
     creds = grpc_ssl_server_credentials_create(RSTRING_PTR(pem_root_certs),
-                                               &key_cert_pair, 1);
+                                               &key_cert_pair, 1, 0);
   }
   if (creds == NULL) {
     rb_raise(rb_eRuntimeError, "could not create a credentials, not sure why");

test/core/end2end/fixtures/chttp2_simple_ssl_fullstack.c

@@ -115,7 +115,7 @@ static void chttp2_init_server_simple_ssl_secure_fullstack(
   grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
                                                   test_server1_cert};
   grpc_server_credentials *ssl_creds =
-      grpc_ssl_server_credentials_create(NULL, &pem_cert_key_pair, 1);
+      grpc_ssl_server_credentials_create(NULL, &pem_cert_key_pair, 1, 0);
   chttp2_init_server_secure_fullstack(f, server_args, ssl_creds);
 }
 

test/core/end2end/fixtures/chttp2_simple_ssl_fullstack_with_poll.c

@@ -115,7 +115,7 @@ static void chttp2_init_server_simple_ssl_secure_fullstack(
   grpc_ssl_pem_key_cert_pair pem_cert_key_pair = {test_server1_key,
                                                   test_server1_cert};
   grpc_server_credentials *ssl_creds =
-      grpc_ssl_server_credentials_create(NULL, &pem_cert_key_pair, 1);
+      grpc_ssl_server_credentials_create(NULL, &pem_cert_key_pair, 1, 0);
   chttp2_init_server_secure_fullstack(f, server_args, ssl_creds);
 }
 

test/core/end2end/fixtures/chttp2_simple_ssl_with_oauth2_fullstack.c

@@ -120,7 +120,7 @@ static void chttp2_init_server_simple_ssl_secure_fullstack(
   grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {test_server1_key,
                                                   test_server1_cert};
   grpc_server_credentials *ssl_creds =
-      grpc_ssl_server_credentials_create(NULL, &pem_key_cert_pair, 1);
+      grpc_ssl_server_credentials_create(NULL, &pem_key_cert_pair, 1, 0);
   chttp2_init_server_secure_fullstack(f, server_args, ssl_creds);
 }
 

test/core/fling/server.c

@@ -210,7 +210,7 @@ int main(int argc, char **argv) {
     grpc_ssl_pem_key_cert_pair pem_key_cert_pair = {test_server1_key,
                                                     test_server1_cert};
     grpc_server_credentials *ssl_creds =
-        grpc_ssl_server_credentials_create(NULL, &pem_key_cert_pair, 1);
+        grpc_ssl_server_credentials_create(NULL, &pem_key_cert_pair, 1, 0);
     server = grpc_server_create(NULL);
     GPR_ASSERT(grpc_server_add_secure_http2_port(server, addr, ssl_creds));
     grpc_server_credentials_release(ssl_creds);