xref: /qemu/crypto/tlssession.c (revision 727385c4) 
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 2.1 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 "authz/base.h"
28 #include "tlscredspriv.h"
29 #include "trace.h"
30 
31 #ifdef CONFIG_GNUTLS
32 
33 
34 #include <gnutls/x509.h>
35 
36 
37 struct QCryptoTLSSession {
38     QCryptoTLSCreds *creds;
39     gnutls_session_t handle;
40     char *hostname;
41     char *authzid;
42     bool handshakeComplete;
43     QCryptoTLSSessionWriteFunc writeFunc;
44     QCryptoTLSSessionReadFunc readFunc;
45     void *opaque;
46     char *peername;
47 };
48 
49 
50 void
51 qcrypto_tls_session_free(QCryptoTLSSession *session)
52 {
53     if (!session) {
54         return;
55     }
56 
57     gnutls_deinit(session->handle);
58     g_free(session->hostname);
59     g_free(session->peername);
60     g_free(session->authzid);
61     object_unref(OBJECT(session->creds));
62     g_free(session);
63 }
64 
65 
66 static ssize_t
67 qcrypto_tls_session_push(void *opaque, const void *buf, size_t len)
68 {
69     QCryptoTLSSession *session = opaque;
70 
71     if (!session->writeFunc) {
72         errno = EIO;
73         return -1;
74     };
75 
76     return session->writeFunc(buf, len, session->opaque);
77 }
78 
79 
80 static ssize_t
81 qcrypto_tls_session_pull(void *opaque, void *buf, size_t len)
82 {
83     QCryptoTLSSession *session = opaque;
84 
85     if (!session->readFunc) {
86         errno = EIO;
87         return -1;
88     };
89 
90     return session->readFunc(buf, len, session->opaque);
91 }
92 
93 #define TLS_PRIORITY_ADDITIONAL_ANON "+ANON-DH"
94 #define TLS_PRIORITY_ADDITIONAL_PSK "+ECDHE-PSK:+DHE-PSK:+PSK"
95 
96 QCryptoTLSSession *
97 qcrypto_tls_session_new(QCryptoTLSCreds *creds,
98                         const char *hostname,
99                         const char *authzid,
100                         QCryptoTLSCredsEndpoint endpoint,
101                         Error **errp)
102 {
103     QCryptoTLSSession *session;
104     int ret;
105 
106     session = g_new0(QCryptoTLSSession, 1);
107     trace_qcrypto_tls_session_new(
108         session, creds, hostname ? hostname : "<none>",
109         authzid ? authzid : "<none>", endpoint);
110 
111     if (hostname) {
112         session->hostname = g_strdup(hostname);
113     }
114     if (authzid) {
115         session->authzid = g_strdup(authzid);
116     }
117     session->creds = creds;
118     object_ref(OBJECT(creds));
119 
120     if (creds->endpoint != endpoint) {
121         error_setg(errp, "Credentials endpoint doesn't match session");
122         goto error;
123     }
124 
125     if (endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
126         ret = gnutls_init(&session->handle, GNUTLS_SERVER);
127     } else {
128         ret = gnutls_init(&session->handle, GNUTLS_CLIENT);
129     }
130     if (ret < 0) {
131         error_setg(errp, "Cannot initialize TLS session: %s",
132                    gnutls_strerror(ret));
133         goto error;
134     }
135 
136     if (object_dynamic_cast(OBJECT(creds),
137                             TYPE_QCRYPTO_TLS_CREDS_ANON)) {
138         QCryptoTLSCredsAnon *acreds = QCRYPTO_TLS_CREDS_ANON(creds);
139         char *prio;
140 
141         if (creds->priority != NULL) {
142             prio = g_strdup_printf("%s:%s",
143                                    creds->priority,
144                                    TLS_PRIORITY_ADDITIONAL_ANON);
145         } else {
146             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
147                             TLS_PRIORITY_ADDITIONAL_ANON);
148         }
149 
150         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
151         if (ret < 0) {
152             error_setg(errp, "Unable to set TLS session priority %s: %s",
153                        prio, gnutls_strerror(ret));
154             g_free(prio);
155             goto error;
156         }
157         g_free(prio);
158         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
159             ret = gnutls_credentials_set(session->handle,
160                                          GNUTLS_CRD_ANON,
161                                          acreds->data.server);
162         } else {
163             ret = gnutls_credentials_set(session->handle,
164                                          GNUTLS_CRD_ANON,
165                                          acreds->data.client);
166         }
167         if (ret < 0) {
168             error_setg(errp, "Cannot set session credentials: %s",
169                        gnutls_strerror(ret));
170             goto error;
171         }
172     } else if (object_dynamic_cast(OBJECT(creds),
173                                    TYPE_QCRYPTO_TLS_CREDS_PSK)) {
174         QCryptoTLSCredsPSK *pcreds = QCRYPTO_TLS_CREDS_PSK(creds);
175         char *prio;
176 
177         if (creds->priority != NULL) {
178             prio = g_strdup_printf("%s:%s",
179                                    creds->priority,
180                                    TLS_PRIORITY_ADDITIONAL_PSK);
181         } else {
182             prio = g_strdup(CONFIG_TLS_PRIORITY ":"
183                             TLS_PRIORITY_ADDITIONAL_PSK);
184         }
185 
186         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
187         if (ret < 0) {
188             error_setg(errp, "Unable to set TLS session priority %s: %s",
189                        prio, gnutls_strerror(ret));
190             g_free(prio);
191             goto error;
192         }
193         g_free(prio);
194         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
195             ret = gnutls_credentials_set(session->handle,
196                                          GNUTLS_CRD_PSK,
197                                          pcreds->data.server);
198         } else {
199             ret = gnutls_credentials_set(session->handle,
200                                          GNUTLS_CRD_PSK,
201                                          pcreds->data.client);
202         }
203         if (ret < 0) {
204             error_setg(errp, "Cannot set session credentials: %s",
205                        gnutls_strerror(ret));
206             goto error;
207         }
208     } else if (object_dynamic_cast(OBJECT(creds),
209                                    TYPE_QCRYPTO_TLS_CREDS_X509)) {
210         QCryptoTLSCredsX509 *tcreds = QCRYPTO_TLS_CREDS_X509(creds);
211         const char *prio = creds->priority;
212         if (!prio) {
213             prio = CONFIG_TLS_PRIORITY;
214         }
215 
216         ret = gnutls_priority_set_direct(session->handle, prio, NULL);
217         if (ret < 0) {
218             error_setg(errp, "Cannot set default TLS session priority %s: %s",
219                        prio, gnutls_strerror(ret));
220             goto error;
221         }
222         ret = gnutls_credentials_set(session->handle,
223                                      GNUTLS_CRD_CERTIFICATE,
224                                      tcreds->data);
225         if (ret < 0) {
226             error_setg(errp, "Cannot set session credentials: %s",
227                        gnutls_strerror(ret));
228             goto error;
229         }
230 
231         if (creds->endpoint == QCRYPTO_TLS_CREDS_ENDPOINT_SERVER) {
232             /* This requests, but does not enforce a client cert.
233              * The cert checking code later does enforcement */
234             gnutls_certificate_server_set_request(session->handle,
235                                                   GNUTLS_CERT_REQUEST);
236         }
237     } else {
238         error_setg(errp, "Unsupported TLS credentials type %s",
239                    object_get_typename(OBJECT(creds)));
240         goto error;
241     }
242 
243     gnutls_transport_set_ptr(session->handle, session);
244     gnutls_transport_set_push_function(session->handle,
245                                        qcrypto_tls_session_push);
246     gnutls_transport_set_pull_function(session->handle,
247                                        qcrypto_tls_session_pull);
248 
249     return session;
250 
251  error:
252     qcrypto_tls_session_free(session);
253     return NULL;
254 }
255 
256 static int
257 qcrypto_tls_session_check_certificate(QCryptoTLSSession *session,
258                                       Error **errp)
259 {
260     int ret;
261     unsigned int status;
262     const gnutls_datum_t *certs;
263     unsigned int nCerts, i;
264     time_t now;
265     gnutls_x509_crt_t cert = NULL;
266     Error *err = NULL;
267 
268     now = time(NULL);
269     if (now == ((time_t)-1)) {
270         error_setg_errno(errp, errno, "Cannot get current time");
271         return -1;
272     }
273 
274     ret = gnutls_certificate_verify_peers2(session->handle, &status);
275     if (ret < 0) {
276         error_setg(errp, "Verify failed: %s", gnutls_strerror(ret));
277         return -1;
278     }
279 
280     if (status != 0) {
281         const char *reason = "Invalid certificate";
282 
283         if (status & GNUTLS_CERT_INVALID) {
284             reason = "The certificate is not trusted";
285         }
286 
287         if (status & GNUTLS_CERT_SIGNER_NOT_FOUND) {
288             reason = "The certificate hasn't got a known issuer";
289         }
290 
291         if (status & GNUTLS_CERT_REVOKED) {
292             reason = "The certificate has been revoked";
293         }
294 
295         if (status & GNUTLS_CERT_INSECURE_ALGORITHM) {
296             reason = "The certificate uses an insecure algorithm";
297         }
298 
299         error_setg(errp, "%s", reason);
300         return -1;
301     }
302 
303     certs = gnutls_certificate_get_peers(session->handle, &nCerts);
304     if (!certs) {
305         error_setg(errp, "No certificate peers");
306         return -1;
307     }
308 
309     for (i = 0; i < nCerts; i++) {
310         ret = gnutls_x509_crt_init(&cert);
311         if (ret < 0) {
312             error_setg(errp, "Cannot initialize certificate: %s",
313                        gnutls_strerror(ret));
314             return -1;
315         }
316 
317         ret = gnutls_x509_crt_import(cert, &certs[i], GNUTLS_X509_FMT_DER);
318         if (ret < 0) {
319             error_setg(errp, "Cannot import certificate: %s",
320                        gnutls_strerror(ret));
321             goto error;
322         }
323 
324         if (gnutls_x509_crt_get_expiration_time(cert) < now) {
325             error_setg(errp, "The certificate has expired");
326             goto error;
327         }
328 
329         if (gnutls_x509_crt_get_activation_time(cert) > now) {
330             error_setg(errp, "The certificate is not yet activated");
331             goto error;
332         }
333 
334         if (gnutls_x509_crt_get_activation_time(cert) > now) {
335             error_setg(errp, "The certificate is not yet activated");
336             goto error;
337         }
338 
339         if (i == 0) {
340             size_t dnameSize = 1024;
341             session->peername = g_malloc(dnameSize);
342         requery:
343             ret = gnutls_x509_crt_get_dn(cert, session->peername, &dnameSize);
344             if (ret < 0) {
345                 if (ret == GNUTLS_E_SHORT_MEMORY_BUFFER) {
346                     session->peername = g_realloc(session->peername,
347                                                   dnameSize);
348                     goto requery;
349                 }
350                 error_setg(errp, "Cannot get client distinguished name: %s",
351                            gnutls_strerror(ret));
352                 goto error;
353             }
354             if (session->authzid) {
355                 bool allow;
356 
357                 allow = qauthz_is_allowed_by_id(session->authzid,
358                                                 session->peername, &err);
359                 if (err) {
360                     error_propagate(errp, err);
361                     goto error;
362                 }
363                 if (!allow) {
364                     error_setg(errp, "TLS x509 authz 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         case GNUTLS_E_PREMATURE_TERMINATION:
477             errno = ECONNABORTED;
478             break;
479         default:
480             errno = EIO;
481             break;
482         }
483         ret = -1;
484     }
485 
486     return ret;
487 }
488 
489 
490 int
491 qcrypto_tls_session_handshake(QCryptoTLSSession *session,
492                               Error **errp)
493 {
494     int ret = gnutls_handshake(session->handle);
495     if (ret == 0) {
496         session->handshakeComplete = true;
497     } else {
498         if (ret == GNUTLS_E_INTERRUPTED ||
499             ret == GNUTLS_E_AGAIN) {
500             ret = 1;
501         } else {
502             error_setg(errp, "TLS handshake failed: %s",
503                        gnutls_strerror(ret));
504             ret = -1;
505         }
506     }
507 
508     return ret;
509 }
510 
511 
512 QCryptoTLSSessionHandshakeStatus
513 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *session)
514 {
515     if (session->handshakeComplete) {
516         return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
517     } else if (gnutls_record_get_direction(session->handle) == 0) {
518         return QCRYPTO_TLS_HANDSHAKE_RECVING;
519     } else {
520         return QCRYPTO_TLS_HANDSHAKE_SENDING;
521     }
522 }
523 
524 
525 int
526 qcrypto_tls_session_get_key_size(QCryptoTLSSession *session,
527                                  Error **errp)
528 {
529     gnutls_cipher_algorithm_t cipher;
530     int ssf;
531 
532     cipher = gnutls_cipher_get(session->handle);
533     ssf = gnutls_cipher_get_key_size(cipher);
534     if (!ssf) {
535         error_setg(errp, "Cannot get TLS cipher key size");
536         return -1;
537     }
538     return ssf;
539 }
540 
541 
542 char *
543 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *session)
544 {
545     if (session->peername) {
546         return g_strdup(session->peername);
547     }
548     return NULL;
549 }
550 
551 
552 #else /* ! CONFIG_GNUTLS */
553 
554 
555 QCryptoTLSSession *
556 qcrypto_tls_session_new(QCryptoTLSCreds *creds G_GNUC_UNUSED,
557                         const char *hostname G_GNUC_UNUSED,
558                         const char *authzid G_GNUC_UNUSED,
559                         QCryptoTLSCredsEndpoint endpoint G_GNUC_UNUSED,
560                         Error **errp)
561 {
562     error_setg(errp, "TLS requires GNUTLS support");
563     return NULL;
564 }
565 
566 
567 void
568 qcrypto_tls_session_free(QCryptoTLSSession *sess G_GNUC_UNUSED)
569 {
570 }
571 
572 
573 int
574 qcrypto_tls_session_check_credentials(QCryptoTLSSession *sess G_GNUC_UNUSED,
575                                       Error **errp)
576 {
577     error_setg(errp, "TLS requires GNUTLS support");
578     return -1;
579 }
580 
581 
582 void
583 qcrypto_tls_session_set_callbacks(
584     QCryptoTLSSession *sess G_GNUC_UNUSED,
585     QCryptoTLSSessionWriteFunc writeFunc G_GNUC_UNUSED,
586     QCryptoTLSSessionReadFunc readFunc G_GNUC_UNUSED,
587     void *opaque G_GNUC_UNUSED)
588 {
589 }
590 
591 
592 ssize_t
593 qcrypto_tls_session_write(QCryptoTLSSession *sess,
594                           const char *buf,
595                           size_t len)
596 {
597     errno = -EIO;
598     return -1;
599 }
600 
601 
602 ssize_t
603 qcrypto_tls_session_read(QCryptoTLSSession *sess,
604                          char *buf,
605                          size_t len)
606 {
607     errno = -EIO;
608     return -1;
609 }
610 
611 
612 int
613 qcrypto_tls_session_handshake(QCryptoTLSSession *sess,
614                               Error **errp)
615 {
616     error_setg(errp, "TLS requires GNUTLS support");
617     return -1;
618 }
619 
620 
621 QCryptoTLSSessionHandshakeStatus
622 qcrypto_tls_session_get_handshake_status(QCryptoTLSSession *sess)
623 {
624     return QCRYPTO_TLS_HANDSHAKE_COMPLETE;
625 }
626 
627 
628 int
629 qcrypto_tls_session_get_key_size(QCryptoTLSSession *sess,
630                                  Error **errp)
631 {
632     error_setg(errp, "TLS requires GNUTLS support");
633     return -1;
634 }
635 
636 
637 char *
638 qcrypto_tls_session_get_peer_name(QCryptoTLSSession *sess)
639 {
640     return NULL;
641 }
642 
643 #endif
644