diff options
Diffstat (limited to 'libvncclient')
| -rw-r--r-- | libvncclient/tls_gnutls.c | 102 | ||||
| -rw-r--r-- | libvncclient/tls_openssl.c | 249 |
2 files changed, 256 insertions, 95 deletions
diff --git a/libvncclient/tls_gnutls.c b/libvncclient/tls_gnutls.c index 75bde35..f146d2a 100644 --- a/libvncclient/tls_gnutls.c +++ b/libvncclient/tls_gnutls.c @@ -18,6 +18,7 @@ */ #include <gnutls/gnutls.h> +#include <gnutls/x509.h> #include <rfb/rfbclient.h> #include <errno.h> #ifdef WIN32 @@ -39,6 +40,98 @@ static gnutls_dh_params_t rfbDHParams; static rfbBool rfbTLSInitialized = FALSE; +static int +verify_certificate_callback (gnutls_session_t session) +{ + unsigned int status; + const gnutls_datum_t *cert_list; + unsigned int cert_list_size; + int ret; + gnutls_x509_crt_t cert; + rfbClient *sptr; + char *hostname; + + sptr = (rfbClient *)gnutls_session_get_ptr(session); + if (!sptr) { + rfbClientLog("Failed to validate certificate - missing client data\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + hostname = sptr->serverHost; + if (!hostname) { + rfbClientLog("No server hostname found for client\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + /* This verification function uses the trusted CAs in the credentials + * structure. So you must have installed one or more CA certificates. + */ + ret = gnutls_certificate_verify_peers2 (session, &status); + if (ret < 0) + { + rfbClientLog ("Certificate validation call failed\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + if (status & GNUTLS_CERT_INVALID) + rfbClientLog("The certificate is not trusted.\n"); + + if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) + rfbClientLog("The certificate hasn't got a known issuer.\n"); + + if (status & GNUTLS_CERT_REVOKED) + rfbClientLog("The certificate has been revoked.\n"); + + if (status & GNUTLS_CERT_EXPIRED) + rfbClientLog("The certificate has expired\n"); + + if (status & GNUTLS_CERT_NOT_ACTIVATED) + rfbClientLog("The certificate is not yet activated\n"); + + if (status) + return GNUTLS_E_CERTIFICATE_ERROR; + + /* Up to here the process is the same for X.509 certificates and + * OpenPGP keys. From now on X.509 certificates are assumed. This can + * be easily extended to work with openpgp keys as well. + */ + if (gnutls_certificate_type_get (session) != GNUTLS_CRT_X509) { + rfbClientLog("The certificate was not X509\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + if (gnutls_x509_crt_init (&cert) < 0) + { + rfbClientLog("Error initialising certificate structure\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + cert_list = gnutls_certificate_get_peers (session, &cert_list_size); + if (cert_list == NULL) + { + rfbClientLog("No certificate was found!\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + if (gnutls_x509_crt_import (cert, &cert_list[0], GNUTLS_X509_FMT_DER) < 0) + { + rfbClientLog("Error parsing certificate\n"); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + if (!gnutls_x509_crt_check_hostname (cert, hostname)) + { + rfbClientLog("The certificate's owner does not match hostname '%s'\n", + hostname); + return GNUTLS_E_CERTIFICATE_ERROR; + } + + gnutls_x509_crt_deinit (cert); + + /* notify gnutls to continue handshake normally */ + return 0; +} + static rfbBool InitializeTLS(void) { @@ -52,7 +145,7 @@ InitializeTLS(void) rfbClientLog("Failed to initialized GnuTLS: %s.\n", gnutls_strerror(ret)); return FALSE; } - rfbClientLog("GnuTLS initialized.\n"); + rfbClientLog("GnuTLS version %s initialized.\n", gnutls_check_version(NULL)); rfbTLSInitialized = TRUE; return TRUE; } @@ -200,6 +293,7 @@ HandshakeTLS(rfbClient* client) continue; } rfbClientLog("TLS handshake failed: %s.\n", gnutls_strerror(ret)); + FreeTLS(client); return FALSE; } @@ -456,6 +550,10 @@ HandleVeNCryptAuth(rfbClient* client) } else { + /* Set the certificate verification callback. */ + gnutls_certificate_set_verify_function (x509_cred, verify_certificate_callback); + gnutls_session_set_ptr ((gnutls_session_t)client->tlsSession, (void *)client); + if ((ret = gnutls_credentials_set((gnutls_session_t)client->tlsSession, GNUTLS_CRD_CERTIFICATE, x509_cred)) < 0) { rfbClientLog("Cannot set x509 credential: %s.\n", gnutls_strerror(ret)); @@ -466,8 +564,6 @@ HandleVeNCryptAuth(rfbClient* client) if (!HandshakeTLS(client)) return FALSE; - /* TODO: validate certificate */ - /* We are done here. The caller should continue with client->subAuthScheme * to do actual sub authentication. */ diff --git a/libvncclient/tls_openssl.c b/libvncclient/tls_openssl.c index 4f758d0..fe60147 100644 --- a/libvncclient/tls_openssl.c +++ b/libvncclient/tls_openssl.c @@ -168,53 +168,11 @@ InitializeTLS(void) SSLeay_add_ssl_algorithms(); RAND_load_file("/dev/urandom", 1024); - rfbClientLog("OpenSSL initialized.\n"); + rfbClientLog("OpenSSL version %s initialized.\n", SSLeay_version(SSLEAY_VERSION)); rfbTLSInitialized = TRUE; return TRUE; } -static int -ssl_verify (int ok, X509_STORE_CTX *ctx) -{ - unsigned char md5sum[16], fingerprint[40], *f; - rfbClient *client; - int err, i; - unsigned int md5len; - //char buf[257]; - X509 *cert; - SSL *ssl; - - if (ok) - return TRUE; - - ssl = X509_STORE_CTX_get_ex_data (ctx, SSL_get_ex_data_X509_STORE_CTX_idx ()); - - client = SSL_CTX_get_app_data (SSL_get_SSL_CTX(ssl)); - - cert = X509_STORE_CTX_get_current_cert (ctx); - err = X509_STORE_CTX_get_error (ctx); - - /* calculate the MD5 hash of the raw certificate */ - md5len = sizeof (md5sum); - X509_digest (cert, EVP_md5 (), md5sum, &md5len); - for (i = 0, f = fingerprint; i < 16; i++, f += 3) - sprintf ((char *) f, "%.2x%c", md5sum[i], i != 15 ? ':' : '\0'); - -#define GET_STRING(name) X509_NAME_oneline (name, buf, 256) - - /* TODO: Don't just ignore certificate checks - - fingerprint = key to check in db - - GET_STRING (X509_get_issuer_name (cert)); - GET_STRING (X509_get_subject_name (cert)); - cert->valid (bool: GOOD or BAD) */ - - ok = TRUE; - - return ok; -} - static int sock_read_ready(SSL *ssl, uint32_t ms) { int r = 0; @@ -251,8 +209,12 @@ static int wait_for_data(SSL *ssl, int ret, int timeout) } break; - default: + default: retval = 3; + long verify_res = SSL_get_verify_result(ssl); + if (verify_res != X509_V_OK) + rfbClientLog("Could not verify server certificate: %s.\n", + X509_verify_cert_error_string(verify_res)); break; } @@ -261,17 +223,131 @@ static int wait_for_data(SSL *ssl, int ret, int timeout) return retval; } +static rfbBool +load_crls_from_file(char *file, SSL_CTX *ssl_ctx) +{ + X509_STORE *st; + X509_CRL *crl; + int i; + int count = 0; + BIO *bio; + STACK_OF(X509_INFO) *xis = NULL; + X509_INFO *xi; + + st = SSL_CTX_get_cert_store(ssl_ctx); + + int rv = 0; + + bio = BIO_new_file(file, "r"); + if (bio == NULL) + return FALSE; + + xis = PEM_X509_INFO_read_bio(bio, NULL, NULL, NULL); + BIO_free(bio); + + for (i = 0; i < sk_X509_INFO_num(xis); i++) + { + xi = sk_X509_INFO_value(xis, i); + if (xi->crl) + { + X509_STORE_add_crl(st, xi->crl); + xi->crl = NULL; + count++; + } + } + + sk_X509_INFO_pop_free(xis, X509_INFO_free); + + if (count > 0) + return TRUE; + else + return FALSE; +} + static SSL * -open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS) +open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS, rfbCredential *cred) { SSL_CTX *ssl_ctx = NULL; SSL *ssl = NULL; int n, finished = 0; + X509_VERIFY_PARAM *param; + uint8_t verify_crls = cred->x509Credential.x509CrlVerifyMode; - ssl_ctx = SSL_CTX_new (SSLv23_client_method ()); - SSL_CTX_set_default_verify_paths (ssl_ctx); - SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, &ssl_verify); - ssl = SSL_new (ssl_ctx); + if (!(ssl_ctx = SSL_CTX_new(SSLv23_client_method()))) + { + rfbClientLog("Could not create new SSL context.\n"); + return NULL; + } + + param = X509_VERIFY_PARAM_new(); + + /* Setup verification if not anonymous */ + if (!anonTLS) + { + if (cred->x509Credential.x509CACertFile) + { + if (!SSL_CTX_load_verify_locations(ssl_ctx, cred->x509Credential.x509CACertFile, NULL)) + { + rfbClientLog("Failed to load CA certificate from %s.\n", + cred->x509Credential.x509CACertFile); + goto error_free_ctx; + } + } else { + rfbClientLog("Using default paths for certificate verification.\n"); + SSL_CTX_set_default_verify_paths (ssl_ctx); + } + + if (cred->x509Credential.x509CACrlFile) + { + if (!load_crls_from_file(cred->x509Credential.x509CACrlFile, ssl_ctx)) + { + rfbClientLog("CRLs could not be loaded.\n"); + goto error_free_ctx; + } + if (verify_crls == rfbX509CrlVerifyNone) verify_crls = rfbX509CrlVerifyAll; + } + + if (cred->x509Credential.x509ClientCertFile && cred->x509Credential.x509ClientKeyFile) + { + if (SSL_CTX_use_certificate_chain_file(ssl_ctx, cred->x509Credential.x509ClientCertFile) != 1) + { + rfbClientLog("Client certificate could not be loaded.\n"); + goto error_free_ctx; + } + + if (SSL_CTX_use_PrivateKey_file(ssl_ctx, cred->x509Credential.x509ClientKeyFile, + SSL_FILETYPE_PEM) != 1) + { + rfbClientLog("Client private key could not be loaded.\n"); + goto error_free_ctx; + } + + if (SSL_CTX_check_private_key(ssl_ctx) == 0) { + rfbClientLog("Client certificate and private key do not match.\n"); + goto error_free_ctx; + } + } + + SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, NULL); + + if (verify_crls == rfbX509CrlVerifyClient) + X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK); + else if (verify_crls == rfbX509CrlVerifyAll) + X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL); + + if(!X509_VERIFY_PARAM_set1_host(param, client->serverHost, strlen(client->serverHost))) + { + rfbClientLog("Could not set server name for verification.\n"); + goto error_free_ctx; + } + SSL_CTX_set1_param(ssl_ctx, param); + } + + if (!(ssl = SSL_new (ssl_ctx))) + { + rfbClientLog("Could not create a new SSL session.\n"); + goto error_free_ctx; + } /* TODO: finetune this list, take into account anonTLS bool */ SSL_set_cipher_list(ssl, "ALL"); @@ -289,24 +365,32 @@ open_ssl_connection (rfbClient *client, int sockfd, rfbBool anonTLS) { finished = 1; SSL_shutdown(ssl); - SSL_free(ssl); - SSL_CTX_free(ssl_ctx); - return NULL; + goto error_free_ssl; } } } while( n != 1 && finished != 1 ); + X509_VERIFY_PARAM_free(param); return ssl; + +error_free_ssl: + SSL_free(ssl); + +error_free_ctx: + X509_VERIFY_PARAM_free(param); + SSL_CTX_free(ssl_ctx); + + return NULL; } static rfbBool -InitializeTLSSession(rfbClient* client, rfbBool anonTLS) +InitializeTLSSession(rfbClient* client, rfbBool anonTLS, rfbCredential *cred) { if (client->tlsSession) return TRUE; - client->tlsSession = open_ssl_connection (client, client->sock, anonTLS); + client->tlsSession = open_ssl_connection (client, client->sock, anonTLS, cred); if (!client->tlsSession) return FALSE; @@ -317,13 +401,6 @@ InitializeTLSSession(rfbClient* client, rfbBool anonTLS) } static rfbBool -SetTLSAnonCredential(rfbClient* client) -{ - rfbClientLog("TLS anonymous credential created.\n"); - return TRUE; -} - -static rfbBool HandshakeTLS(rfbClient* client) { int timeout = 15; @@ -344,7 +421,8 @@ return TRUE; timeout--; continue; } - rfbClientLog("TLS handshake failed: -.\n"); + rfbClientLog("TLS handshake failed.\n"); + FreeTLS(client); return FALSE; } @@ -433,22 +511,31 @@ ReadVeNCryptSecurityType(rfbClient* client, uint32_t *result) rfbBool HandleAnonTLSAuth(rfbClient* client) { - if (!InitializeTLS() || !InitializeTLSSession(client, TRUE)) return FALSE; - - if (!SetTLSAnonCredential(client)) return FALSE; + if (!InitializeTLS() || !InitializeTLSSession(client, TRUE, NULL)) return FALSE; if (!HandshakeTLS(client)) return FALSE; return TRUE; } +static void +FreeX509Credential(rfbCredential *cred) +{ + if (cred->x509Credential.x509CACertFile) free(cred->x509Credential.x509CACertFile); + if (cred->x509Credential.x509CACrlFile) free(cred->x509Credential.x509CACrlFile); + if (cred->x509Credential.x509ClientCertFile) free(cred->x509Credential.x509ClientCertFile); + if (cred->x509Credential.x509ClientKeyFile) free(cred->x509Credential.x509ClientKeyFile); + free(cred); +} + rfbBool HandleVeNCryptAuth(rfbClient* client) { uint8_t major, minor, status; uint32_t authScheme; rfbBool anonTLS; -// gnutls_certificate_credentials_t x509_cred = NULL; + rfbCredential *cred = NULL; + rfbBool result = TRUE; if (!InitializeTLS()) return FALSE; @@ -506,7 +593,6 @@ HandleVeNCryptAuth(rfbClient* client) /* Get X509 Credentials if it's not anonymous */ if (!anonTLS) { - rfbCredential *cred; if (!client->GetCredential) { @@ -519,39 +605,18 @@ HandleVeNCryptAuth(rfbClient* client) rfbClientLog("Reading credential failed\n"); return FALSE; } - - /* TODO: don't just ignore this - x509_cred = CreateX509CertCredential(cred); - FreeX509Credential(cred); - if (!x509_cred) return FALSE; */ } /* Start up the TLS session */ - if (!InitializeTLSSession(client, anonTLS)) return FALSE; + if (!InitializeTLSSession(client, anonTLS, cred)) result = FALSE; - if (anonTLS) - { - if (!SetTLSAnonCredential(client)) return FALSE; - } - else - { -/* TODO: don't just ignore this - if ((ret = gnutls_credentials_set(client->tlsSession, GNUTLS_CRD_CERTIFICATE, x509_cred)) < 0) - { - rfbClientLog("Cannot set x509 credential: %s.\n", gnutls_strerror(ret)); - FreeTLS(client); */ - return FALSE; - // } - } - - if (!HandshakeTLS(client)) return FALSE; - - /* TODO: validate certificate */ + if (!HandshakeTLS(client)) result = FALSE; /* We are done here. The caller should continue with client->subAuthScheme * to do actual sub authentication. */ - return TRUE; + if (cred) FreeX509Credential(cred); + return result; } int |