/* * QEMU VNC display driver: TLS helpers * * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws> * Copyright (C) 2006 Fabrice Bellard * Copyright (C) 2009 Red Hat, Inc * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "vnc.h" #include "qemu_socket.h" #if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2 /* Very verbose, so only enabled for _VNC_DEBUG >= 2 */ static void vnc_debug_gnutls_log(int level, const char* str) { VNC_DEBUG("%d %s", level, str); } #endif /* defined(_VNC_DEBUG) && _VNC_DEBUG >= 2 */ #define DH_BITS 1024 static gnutls_dh_params_t dh_params; static int vnc_tls_initialize(void) { static int tlsinitialized = 0; if (tlsinitialized) return 1; if (gnutls_global_init () < 0) return 0; /* XXX ought to re-generate diffie-hellmen params periodically */ if (gnutls_dh_params_init (&dh_params) < 0) return 0; if (gnutls_dh_params_generate2 (dh_params, DH_BITS) < 0) return 0; #if defined(_VNC_DEBUG) && _VNC_DEBUG >= 2 gnutls_global_set_log_level(10); gnutls_global_set_log_function(vnc_debug_gnutls_log); #endif tlsinitialized = 1; return 1; } static ssize_t vnc_tls_push(gnutls_transport_ptr_t transport, const void *data, size_t len) { struct VncState *vs = (struct VncState *)transport; int ret; retry: ret = send(vs->csock, data, len, 0); if (ret < 0) { if (errno == EINTR) goto retry; return -1; } return ret; } static ssize_t vnc_tls_pull(gnutls_transport_ptr_t transport, void *data, size_t len) { struct VncState *vs = (struct VncState *)transport; int ret; retry: ret = recv(vs->csock, data, len, 0); if (ret < 0) { if (errno == EINTR) goto retry; return -1; } return ret; } static gnutls_anon_server_credentials vnc_tls_initialize_anon_cred(void) { gnutls_anon_server_credentials anon_cred; int ret; if ((ret = gnutls_anon_allocate_server_credentials(&anon_cred)) < 0) { VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret)); return NULL; } gnutls_anon_set_server_dh_params(anon_cred, dh_params); return anon_cred; } static gnutls_certificate_credentials_t vnc_tls_initialize_x509_cred(VncDisplay *vd) { gnutls_certificate_credentials_t x509_cred; int ret; if (!vd->tls.x509cacert) { VNC_DEBUG("No CA x509 certificate specified\n"); return NULL; } if (!vd->tls.x509cert) { VNC_DEBUG("No server x509 certificate specified\n"); return NULL; } if (!vd->tls.x509key) { VNC_DEBUG("No server private key specified\n"); return NULL; } if ((ret = gnutls_certificate_allocate_credentials(&x509_cred)) < 0) { VNC_DEBUG("Cannot allocate credentials %s\n", gnutls_strerror(ret)); return NULL; } if ((ret = gnutls_certificate_set_x509_trust_file(x509_cred, vd->tls.x509cacert, GNUTLS_X509_FMT_PEM)) < 0) { VNC_DEBUG("Cannot load CA certificate %s\n", gnutls_strerror(ret)); gnutls_certificate_free_credentials(x509_cred); return NULL; } if ((ret = gnutls_certificate_set_x509_key_file (x509_cred, vd->tls.x509cert, vd->tls.x509key, GNUTLS_X509_FMT_PEM)) < 0) { VNC_DEBUG("Cannot load certificate & key %s\n", gnutls_strerror(ret)); gnutls_certificate_free_credentials(x509_cred); return NULL; } if (vd->tls.x509cacrl) { if ((ret = gnutls_certificate_set_x509_crl_file(x509_cred, vd->tls.x509cacrl, GNUTLS_X509_FMT_PEM)) < 0) { VNC_DEBUG("Cannot load CRL %s\n", gnutls_strerror(ret)); gnutls_certificate_free_credentials(x509_cred); return NULL; } } gnutls_certificate_set_dh_params (x509_cred, dh_params); return x509_cred; } int vnc_tls_validate_certificate(struct VncState *vs) { int ret; unsigned int status; const gnutls_datum_t *certs; unsigned int nCerts, i; time_t now; VNC_DEBUG("Validating client certificate\n"); if ((ret = gnutls_certificate_verify_peers2 (vs->tls.session, &status)) < 0) { VNC_DEBUG("Verify failed %s\n", gnutls_strerror(ret)); return -1; } if ((now = time(NULL)) == ((time_t)-1)) { return -1; } if (status != 0) { if (status & GNUTLS_CERT_INVALID) VNC_DEBUG("The certificate is not trusted.\n"); if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) VNC_DEBUG("The certificate hasn't got a known issuer.\n"); if (status & GNUTLS_CERT_REVOKED) VNC_DEBUG("The certificate has been revoked.\n"); if (status & GNUTLS_CERT_INSECURE_ALGORITHM) VNC_DEBUG("The certificate uses an insecure algorithm\n"); return -1; } else { VNC_DEBUG("Certificate is valid!\n"); } /* Only support x509 for now */ if (gnutls_certificate_type_get(vs->tls.session) != GNUTLS_CRT_X509) return -1; if (!(certs = gnutls_certificate_get_peers(vs->tls.session, &nCerts))) return -1; for (i = 0 ; i < nCerts ; i++) { gnutls_x509_crt_t cert; VNC_DEBUG ("Checking certificate chain %d\n", i); if (gnutls_x509_crt_init (&cert) < 0) return -1; if (gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER) < 0) { gnutls_x509_crt_deinit (cert); return -1; } if (gnutls_x509_crt_get_expiration_time (cert) < now) { VNC_DEBUG("The certificate has expired\n"); gnutls_x509_crt_deinit (cert); return -1; } if (gnutls_x509_crt_get_activation_time (cert) > now) { VNC_DEBUG("The certificate is not yet activated\n"); gnutls_x509_crt_deinit (cert); return -1; } if (gnutls_x509_crt_get_activation_time (cert) > now) { VNC_DEBUG("The certificate is not yet activated\n"); gnutls_x509_crt_deinit (cert); return -1; } if (i == 0) { size_t dnameSize = 1024; vs->tls.dname = qemu_malloc(dnameSize); requery: if ((ret = gnutls_x509_crt_get_dn (cert, vs->tls.dname, &dnameSize)) != 0) { if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) { vs->tls.dname = qemu_realloc(vs->tls.dname, dnameSize); goto requery; } gnutls_x509_crt_deinit (cert); VNC_DEBUG("Cannot get client distinguished name: %s", gnutls_strerror (ret)); return -1; } if (vs->vd->tls.x509verify) { int allow; if (!vs->vd->tls.acl) { VNC_DEBUG("no ACL activated, allowing access"); gnutls_x509_crt_deinit (cert); continue; } allow = qemu_acl_party_is_allowed(vs->vd->tls.acl, vs->tls.dname); VNC_DEBUG("TLS x509 ACL check for %s is %s\n", vs->tls.dname, allow ? "allowed" : "denied"); if (!allow) { gnutls_x509_crt_deinit (cert); return -1; } } } gnutls_x509_crt_deinit (cert); } return 0; } int vnc_tls_client_setup(struct VncState *vs, int needX509Creds) { static const int cert_type_priority[] = { GNUTLS_CRT_X509, 0 }; static const int protocol_priority[]= { GNUTLS_TLS1_1, GNUTLS_TLS1_0, GNUTLS_SSL3, 0 }; static const int kx_anon[] = {GNUTLS_KX_ANON_DH, 0}; static const int kx_x509[] = {GNUTLS_KX_DHE_DSS, GNUTLS_KX_RSA, GNUTLS_KX_DHE_RSA, GNUTLS_KX_SRP, 0}; VNC_DEBUG("Do TLS setup\n"); if (vnc_tls_initialize() < 0) { VNC_DEBUG("Failed to init TLS\n"); vnc_client_error(vs); return -1; } if (vs->tls.session == NULL) { if (gnutls_init(&vs->tls.session, GNUTLS_SERVER) < 0) { vnc_client_error(vs); return -1; } if (gnutls_set_default_priority(vs->tls.session) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (gnutls_kx_set_priority(vs->tls.session, needX509Creds ? kx_x509 : kx_anon) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (gnutls_certificate_type_set_priority(vs->tls.session, cert_type_priority) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (gnutls_protocol_set_priority(vs->tls.session, protocol_priority) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (needX509Creds) { gnutls_certificate_server_credentials x509_cred = vnc_tls_initialize_x509_cred(vs->vd); if (!x509_cred) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_CERTIFICATE, x509_cred) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; gnutls_certificate_free_credentials(x509_cred); vnc_client_error(vs); return -1; } if (vs->vd->tls.x509verify) { VNC_DEBUG("Requesting a client certificate\n"); gnutls_certificate_server_set_request (vs->tls.session, GNUTLS_CERT_REQUEST); } } else { gnutls_anon_server_credentials anon_cred = vnc_tls_initialize_anon_cred(); if (!anon_cred) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; vnc_client_error(vs); return -1; } if (gnutls_credentials_set(vs->tls.session, GNUTLS_CRD_ANON, anon_cred) < 0) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; gnutls_anon_free_server_credentials(anon_cred); vnc_client_error(vs); return -1; } } gnutls_transport_set_ptr(vs->tls.session, (gnutls_transport_ptr_t)vs); gnutls_transport_set_push_function(vs->tls.session, vnc_tls_push); gnutls_transport_set_pull_function(vs->tls.session, vnc_tls_pull); } return 0; } void vnc_tls_client_cleanup(struct VncState *vs) { if (vs->tls.session) { gnutls_deinit(vs->tls.session); vs->tls.session = NULL; } vs->tls.wiremode = VNC_WIREMODE_CLEAR; free(vs->tls.dname); } static int vnc_set_x509_credential(VncDisplay *vd, const char *certdir, const char *filename, char **cred, int ignoreMissing) { struct stat sb; if (*cred) { qemu_free(*cred); *cred = NULL; } *cred = qemu_malloc(strlen(certdir) + strlen(filename) + 2); strcpy(*cred, certdir); strcat(*cred, "/"); strcat(*cred, filename); VNC_DEBUG("Check %s\n", *cred); if (stat(*cred, &sb) < 0) { qemu_free(*cred); *cred = NULL; if (ignoreMissing && errno == ENOENT) return 0; return -1; } return 0; } #define X509_CA_CERT_FILE "ca-cert.pem" #define X509_CA_CRL_FILE "ca-crl.pem" #define X509_SERVER_KEY_FILE "server-key.pem" #define X509_SERVER_CERT_FILE "server-cert.pem" int vnc_tls_set_x509_creds_dir(VncDisplay *vd, const char *certdir) { if (vnc_set_x509_credential(vd, certdir, X509_CA_CERT_FILE, &vd->tls.x509cacert, 0) < 0) goto cleanup; if (vnc_set_x509_credential(vd, certdir, X509_CA_CRL_FILE, &vd->tls.x509cacrl, 1) < 0) goto cleanup; if (vnc_set_x509_credential(vd, certdir, X509_SERVER_CERT_FILE, &vd->tls.x509cert, 0) < 0) goto cleanup; if (vnc_set_x509_credential(vd, certdir, X509_SERVER_KEY_FILE, &vd->tls.x509key, 0) < 0) goto cleanup; return 0; cleanup: qemu_free(vd->tls.x509cacert); qemu_free(vd->tls.x509cacrl); qemu_free(vd->tls.x509cert); qemu_free(vd->tls.x509key); vd->tls.x509cacert = vd->tls.x509cacrl = vd->tls.x509cert = vd->tls.x509key = NULL; return -1; }