xref: /openbmc/qemu/crypto/tlssession.c (revision 0b8f7448) 
1 /*
2  * QEMU crypto TLS session support
3  *
4  * Copyright (c) 2015 Red Hat, Inc.
5  *
6  * This library is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2 of the License, or (at your option) any later version.
10  *
11  * This library is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18  *
19  */
20 
21 #include "qemu/osdep.h"
22 #include "crypto/tlssession.h"
23 #include "crypto/tlscredsanon.h"
24 #include "crypto/tlscredspsk.h"
25 #include "crypto/tlscredsx509.h"
26 #include "qapi/error.h"
27 #include "qemu/acl.h"
28 #include "trace.h"
29 
30 #ifdef CONFIG_GNUTLS
31 
32 
33 #include <gnutls/x509.h>
34 
35 
36 struct QCryptoTLSSession {
37     QCryptoTLSCreds *creds;
38     gnutls_session_t handle;
39     char *hostname;
40     char *aclname;
41     bool handshakeComplete;
42     QCryptoTLSSessionWriteFunc writeFunc;
43     QCryptoTLSSessionReadFunc readFunc;
44     void *opaque;
45     char *peername;
46 };
47 
48 
49 void
50 qcrypto_tls_session_free(QCryptoTLSSession *session)
51 {
52     if (!session) {
53         return;
54     }
55 
56     gnutls_deinit(session->handle);
57     g_free(session->hostname);
58     g_free(session->peername);
59     g_free(session->aclname);
60     object_unref(OBJECT(session->creds));
61     g_free(session);
62 }
63 
64 
65 static ssize_t
66 qcrypto_tls_session_push(void *opaque, const void *buf, size_t len)
67 {
68     QCryptoTLSSession *session = opaque;
69 
70     if (!session->writeFunc) {
71         errno = EIO;
72         return -1;
73     };
74 
75     return session->writeFunc(buf, len, session->opaque);
76 }
77 
78 
79 static ssize_t
80 qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
81 {
82     QCryptoTLSSession *session = opaque;
83 
84     if (!session->readFunc) {
85         errno = EIO;
86         return -1;
87     };
88 
89     return session->readFunc(buf, len, session->opaque);
90 }
91 
92 #define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
93 #define TLS_PRIORITY_ADDITIONAL_PSK "+ECDHE-PSK:+DHE-PSK:+PSK"
94 
95 QCryptoTLSSession *
96 qcrypto_tls_session_new(QCryptoTLSCreds *creds,
97                         const char *hostname,
98                         const char *aclname,
99                         QCryptoTLSCredsEndpoint endpoint,
100                         Error **errp)
101 {
102     QCryptoTLSSession *session;
103     int ret;
104 
105     session = g_new0(QCryptoTLSSession, 1);
106     trace_qcrypto_tls_session_new(
107         session, creds, hostname ? hostname : "<none>",
108         aclname ? aclname : "<none>", endpoint);
109 
110     if (hostname) {
111         session->hostname = g_strdup(hostname);
112     }
113     if (aclname) {
114         session->aclname = g_strdup(aclname);
115     }
116     session->creds = creds;
117     object_ref(OBJECT(creds));
118 
119     if (creds->endpoint != endpoint) {
120         error_setg(errp, "Credentials endpoint doesn't match session");
121         goto error;
122     }
123 
124     if (endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
125         ret = gnutls_init(&session->handle, GNUTLS_SERVER);
126     } else {
127         ret = gnutls_init(&session->handle, GNUTLS_CLIENT);
128     }
129     if (ret < 0) {
130         error_setg(errp, "Cannot initialize TLS session: %s",
131                    gnutls_strerror(ret));
132         goto error;
133     }
134 
135     if (object_dynamic_cast(OBJECT(creds),
136                             TYPE_QCRYPTO_TLS_CREDS_ANON)) {
137         QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
138         char *prio;
139 
140         if (creds->priority != NULL) {
141             prio = g_strdup_printf("%s:%s",
142                                    creds->priority,
143                                    TLS_PRIORITY_ADDITIONAL_ANON);
144         } else {
145             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
146                             TLS_PRIORITY_ADDITIONAL_ANON);
147         }
148 
149         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
150         if (ret < 0) {
151             error_setg(errp, "Unable to set TLS session priority %s: %s",
152                        prio, gnutls_strerror(ret));
153             g_free(prio);
154             goto error;
155         }
156         g_free(prio);
157         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
158             ret = gnutls_credentials_set(session->handle,
159                                          GNUTLS_CRD_ANON,
160                                          acreds->data.server);
161         } else {
162             ret = gnutls_credentials_set(session->handle,
163                                          GNUTLS_CRD_ANON,
164                                          acreds->data.client);
165         }
166         if (ret < 0) {
167             error_setg(errp, "Cannot set session credentials: %s",
168                        gnutls_strerror(ret));
169             goto error;
170         }
171     } else if (object_dynamic_cast(OBJECT(creds),
172                                    TYPE_QCRYPTO_TLS_CREDS_PSK)) {
173         QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
174         char *prio;
175 
176         if (creds->priority != NULL) {
177             prio = g_strdup_printf("%s:%s",
178                                    creds->priority,
179                                    TLS_PRIORITY_ADDITIONAL_PSK);
180         } else {
181             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
182                             TLS_PRIORITY_ADDITIONAL_PSK);
183         }
184 
185         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
186         if (ret < 0) {
187             error_setg(errp, "Unable to set TLS session priority %s: %s",
188                        prio, gnutls_strerror(ret));
189             g_free(prio);
190             goto error;
191         }
192         g_free(prio);
193         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
194             ret = gnutls_credentials_set(session->handle,
195                                          GNUTLS_CRD_PSK,
196                                          pcreds->data.server);
197         } else {
198             ret = gnutls_credentials_set(session->handle,
199                                          GNUTLS_CRD_PSK,
200                                          pcreds->data.client);
201         }
202         if (ret < 0) {
203             error_setg(errp, "Cannot set session credentials: %s",
204                        gnutls_strerror(ret));
205             goto error;
206         }
207     } else if (object_dynamic_cast(OBJECT(creds),
208                                    TYPE_QCRYPTO_TLS_CREDS_X509)) {
209         QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
210         const char *prio = creds->priority;
211         if (!prio) {
212             prio = CONFIG_TLS_PRIORITY;
213         }
214 
215         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
216         if (ret < 0) {
217             error_setg(errp, "Cannot set default TLS session priority %s: %s",
218                        prio, gnutls_strerror(ret));
219             goto error;
220         }
221         ret = gnutls_credentials_set(session->handle,
222                                      GNUTLS_CRD_CERTIFICATE,
223                                      tcreds->data);
224         if (ret < 0) {
225             error_setg(errp, "Cannot set session credentials: %s",
226                        gnutls_strerror(ret));
227             goto error;
228         }
229 
230         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
231             /* This requests, but does not enforce a client cert.
232              * The cert checking code later does enforcement */
233             gnutls_certificate_server_set_request(session->handle,
234                                                   GNUTLS_CERT_REQUEST);
235         }
236     } else {
237         error_setg(errp, "Unsupported TLS credentials type %s",
238                    object_get_typename(OBJECT(creds)));
239         goto error;
240     }
241 
242     gnutls_transport_set_ptr(session->handle, session);
243     gnutls_transport_set_push_function(session->handle,
244                                        qcrypto_tls_session_push);
245     gnutls_transport_set_pull_function(session->handle,
246                                        qcrypto_tls_session_pull);
247 
248     return session;
249 
250  error:
251     qcrypto_tls_session_free(session);
252     return NULL;
253 }
254 
255 static int
256 qcrypto_tls_session_check_certificate(QCryptoTLSSession *session,
257                                       Error **errp)
258 {
259     int ret;
260     unsigned int status;
261     const gnutls_datum_t *certs;
262     unsigned int nCerts, i;
263     time_t now;
264     gnutls_x509_crt_t cert = NULL;
265 
266     now = time(NULL);
267     if (now == ((time_t)-1)) {
268         error_setg_errno(errp, errno, "Cannot get current time");
269         return -1;
270     }
271 
272     ret = gnutls_certificate_verify_peers2(session->handle, &status);
273     if (ret < 0) {
274         error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
275         return -1;
276     }
277 
278     if (status != 0) {
279         const char *reason = "Invalid certificate";
280 
281         if (status & GNUTLS_CERT_INVALID) {
282             reason = "The certificate is not trusted";
283         }
284 
285         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
286             reason = "The certificate hasn't got a known issuer";
287         }
288 
289         if (status & GNUTLS_CERT_REVOKED) {
290             reason = "The certificate has been revoked";
291         }
292 
293         if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
294             reason = "The certificate uses an insecure algorithm";
295         }
296 
297         error_setg(errp, "%s", reason);
298         return -1;
299     }
300 
301     certs = gnutls_certificate_get_peers(session->handle, &nCerts);
302     if (!certs) {
303         error_setg(errp, "No certificate peers");
304         return -1;
305     }
306 
307     for (i = 0; i < nCerts; i++) {
308         ret = gnutls_x509_crt_init(&cert);
309         if (ret < 0) {
310             error_setg(errp, "Cannot initialize certificate: %s",
311                        gnutls_strerror(ret));
312             return -1;
313         }
314 
315         ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
316         if (ret < 0) {
317             error_setg(errp, "Cannot import certificate: %s",
318                        gnutls_strerror(ret));
319             goto error;
320         }
321 
322         if (gnutls_x509_crt_get_expiration_time(cert) < now) {
323             error_setg(errp, "The certificate has expired");
324             goto error;
325         }
326 
327         if (gnutls_x509_crt_get_activation_time(cert) > now) {
328             error_setg(errp, "The certificate is not yet activated");
329             goto error;
330         }
331 
332         if (gnutls_x509_crt_get_activation_time(cert) > now) {
333             error_setg(errp, "The certificate is not yet activated");
334             goto error;
335         }
336 
337         if (i == 0) {
338             size_t dnameSize = 1024;
339             session->peername = g_malloc(dnameSize);
340         requery:
341             ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
342             if (ret < 0) {
343                 if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
344                     session->peername = g_realloc(session->peername,
345                                                   dnameSize);
346                     goto requery;
347                 }
348                 error_setg(errp, "Cannot get client distinguished name: %s",
349                            gnutls_strerror(ret));
350                 goto error;
351             }
352             if (session->aclname) {
353                 qemu_acl *acl = qemu_acl_find(session->aclname);
354                 int allow;
355                 if (!acl) {
356                     error_setg(errp, "Cannot find ACL %s",
357                                session->aclname);
358                     goto error;
359                 }
360 
361                 allow = qemu_acl_party_is_allowed(acl, session->peername);
362 
363                 if (!allow) {
364                     error_setg(errp, "TLS x509 ACL check for %s is denied",
365                                session->peername);
366                     goto error;
367                 }
368             }
369             if (session->hostname) {
370                 if (!gnutls_x509_crt_check_hostname(cert, session->hostname)) {
371                     error_setg(errp,
372                                "Certificate does not match the hostname %s",
373                                session->hostname);
374                     goto error;
375                 }
376             }
377         }
378 
379         gnutls_x509_crt_deinit(cert);
380     }
381 
382     return 0;
383 
384  error:
385     gnutls_x509_crt_deinit(cert);
386     return -1;
387 }
388 
389 
390 int
391 qcrypto_tls_session_check_credentials(QCryptoTLSSession *session,
392                                       Error **errp)
393 {
394     if (object_dynamic_cast(OBJECT(session->creds),
395                             TYPE_QCRYPTO_TLS_CREDS_ANON)) {
396         trace_qcrypto_tls_session_check_creds(session, "nop");
397         return 0;
398     } else if (object_dynamic_cast(OBJECT(session->creds),
399                             TYPE_QCRYPTO_TLS_CREDS_PSK)) {
400         trace_qcrypto_tls_session_check_creds(session, "nop");
401         return 0;
402     } else if (object_dynamic_cast(OBJECT(session->creds),
403                             TYPE_QCRYPTO_TLS_CREDS_X509)) {
404         if (session->creds->verifyPeer) {
405             int ret = qcrypto_tls_session_check_certificate(session,
406                                                             errp);
407             trace_qcrypto_tls_session_check_creds(session,
408                                                   ret == 0 ? "pass" : "fail");
409             return ret;
410         } else {
411             trace_qcrypto_tls_session_check_creds(session, "skip");
412             return 0;
413         }
414     } else {
415         trace_qcrypto_tls_session_check_creds(session, "error");
416         error_setg(errp, "Unexpected credential type %s",
417                    object_get_typename(OBJECT(session->creds)));
418         return -1;
419     }
420 }
421 
422 
423 void
424 qcrypto_tls_session_set_callbacks(QCryptoTLSSession *session,
425                                   QCryptoTLSSessionWriteFunc writeFunc,
426                                   QCryptoTLSSessionReadFunc readFunc,
427                                   void *opaque)
428 {
429     session->writeFunc = writeFunc;
430     session->readFunc = readFunc;
431     session->opaque = opaque;
432 }
433 
434 
435 ssize_t
436 qcrypto_tls_session_write(QCryptoTLSSession *session,
437                           const char *buf,
438                           size_t len)
439 {
440     ssize_t ret = gnutls_record_send(session->handle, buf, len);
441 
442     if (ret < 0) {
443         switch (ret) {
444         case GNUTLS_E_AGAIN:
445             errno = EAGAIN;
446             break;
447         case GNUTLS_E_INTERRUPTED:
448             errno = EINTR;
449             break;
450         default:
451             errno = EIO;
452             break;
453         }
454         ret = -1;
455     }
456 
457     return ret;
458 }
459 
460 
461 ssize_t
462 qcrypto_tls_session_read(QCryptoTLSSession *session,
463                          char *buf,
464                          size_t len)
465 {
466     ssize_t ret = gnutls_record_recv(session->handle, buf, len);
467 
468     if (ret < 0) {
469         switch (ret) {
470         case GNUTLS_E_AGAIN:
471             errno = EAGAIN;
472             break;
473         case GNUTLS_E_INTERRUPTED:
474             errno = EINTR;
475             break;
476         default:
477             errno = EIO;
478             break;
479         }
480         ret = -1;
481     }
482 
483     return ret;
484 }
485 
486 
487 int
488 qcrypto_tls_session_handshake(QCryptoTLSSession *session,
489                               Error **errp)
490 {
491     int ret = gnutls_handshake(session->handle);
492     if (ret == 0) {
493         session->handshakeComplete = true;
494     } else {
495         if (ret == GNUTLS_E_INTERRUPTED ||
496             ret == GNUTLS_E_AGAIN) {
497             ret = 1;
498         } else {
499             error_setg(errp, "TLS handshake failed: %s",
500                        gnutls_strerror(ret));
501             ret = -1;
502         }
503     }
504 
505     return ret;
506 }
507 
508 
509 QCryptoTLSSessionHandshakeStatus
510 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
511 {
512     if (session->handshakeComplete) {
513         return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
514     } else if (gnutls_record_get_direction(session->handle) == 0) {
515         return QCRYPTO_TLS_HANDSHAKE_RECVING;
516     } else {
517         return QCRYPTO_TLS_HANDSHAKE_SENDING;
518     }
519 }
520 
521 
522 int
523 qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
524                                  Error **errp)
525 {
526     gnutls_cipher_algorithm_t cipher;
527     int ssf;
528 
529     cipher = gnutls_cipher_get(session->handle);
530     ssf = gnutls_cipher_get_key_size(cipher);
531     if (!ssf) {
532         error_setg(errp, "Cannot get TLS cipher key size");
533         return -1;
534     }
535     return ssf;
536 }
537 
538 
539 char *
540 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
541 {
542     if (session->peername) {
543         return g_strdup(session->peername);
544     }
545     return NULL;
546 }
547 
548 
549 #else /* ! CONFIG_GNUTLS */
550 
551 
552 QCryptoTLSSession *
553 qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
554                         const char *hostname G_GNUC_UNUSED,
555                         const char *aclname G_GNUC_UNUSED,
556                         QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
557                         Error **errp)
558 {
559     error_setg(errp, "TLS requires GNUTLS support");
560     return NULL;
561 }
562 
563 
564 void
565 qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
566 {
567 }
568 
569 
570 int
571 qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
572                                       Error **errp)
573 {
574     error_setg(errp, "TLS requires GNUTLS support");
575     return -1;
576 }
577 
578 
579 void
580 qcrypto_tls_session_set_callbacks(
581     QCryptoTLSSession *sess G_GNUC_UNUSED,
582     QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
583     QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
584     void *opaque G_GNUC_UNUSED)
585 {
586 }
587 
588 
589 ssize_t
590 qcrypto_tls_session_write(QCryptoTLSSession *sess,
591                           const char *buf,
592                           size_t len)
593 {
594     errno = -EIO;
595     return -1;
596 }
597 
598 
599 ssize_t
600 qcrypto_tls_session_read(QCryptoTLSSession *sess,
601                          char *buf,
602                          size_t len)
603 {
604     errno = -EIO;
605     return -1;
606 }
607 
608 
609 int
610 qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
611                               Error **errp)
612 {
613     error_setg(errp, "TLS requires GNUTLS support");
614     return -1;
615 }
616 
617 
618 QCryptoTLSSessionHandshakeStatus
619 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
620 {
621     return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
622 }
623 
624 
625 int
626 qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
627                                  Error **errp)
628 {
629     error_setg(errp, "TLS requires GNUTLS support");
630     return -1;
631 }
632 
633 
634 char *
635 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
636 {
637     return NULL;
638 }
639 
640 #endif
641