xref: /openbmc/qemu/crypto/secret.c (revision 520e210c) 
1 /*
2  * QEMU crypto secret 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/secret.h"
23 #include "crypto/cipher.h"
24 #include "qapi/error.h"
25 #include "qom/object_interfaces.h"
26 #include "qemu/base64.h"
27 #include "trace.h"
28 
29 
30 static void
31 qcrypto_secret_load_data(QCryptoSecret *secret,
32                          uint8_t **output,
33                          size_t *outputlen,
34                          Error **errp)
35 {
36     char *data = NULL;
37     size_t length = 0;
38     GError *gerr = NULL;
39 
40     *output = NULL;
41     *outputlen = 0;
42 
43     if (secret->file) {
44         if (secret->data) {
45             error_setg(errp,
46                        "'file' and 'data' are mutually exclusive");
47             return;
48         }
49         if (!g_file_get_contents(secret->file, &data, &length, &gerr)) {
50             error_setg(errp,
51                        "Unable to read %s: %s",
52                        secret->file, gerr->message);
53             g_error_free(gerr);
54             return;
55         }
56         *output = (uint8_t *)data;
57         *outputlen = length;
58     } else if (secret->data) {
59         *outputlen = strlen(secret->data);
60         *output = (uint8_t *)g_strdup(secret->data);
61     } else {
62         error_setg(errp, "Either 'file' or 'data' must be provided");
63     }
64 }
65 
66 
67 static void qcrypto_secret_decrypt(QCryptoSecret *secret,
68                                    const uint8_t *input,
69                                    size_t inputlen,
70                                    uint8_t **output,
71                                    size_t *outputlen,
72                                    Error **errp)
73 {
74     uint8_t *key = NULL, *ciphertext = NULL, *iv = NULL;
75     size_t keylen, ciphertextlen, ivlen;
76     QCryptoCipher *aes = NULL;
77     uint8_t *plaintext = NULL;
78 
79     *output = NULL;
80     *outputlen = 0;
81 
82     if (qcrypto_secret_lookup(secret->keyid,
83                               &key, &keylen,
84                               errp) < 0) {
85         goto cleanup;
86     }
87 
88     if (keylen != 32) {
89         error_setg(errp, "Key should be 32 bytes in length");
90         goto cleanup;
91     }
92 
93     if (!secret->iv) {
94         error_setg(errp, "IV is required to decrypt secret");
95         goto cleanup;
96     }
97 
98     iv = qbase64_decode(secret->iv, -1, &ivlen, errp);
99     if (!iv) {
100         goto cleanup;
101     }
102     if (ivlen != 16) {
103         error_setg(errp, "IV should be 16 bytes in length not %zu",
104                    ivlen);
105         goto cleanup;
106     }
107 
108     aes = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_256,
109                              QCRYPTO_CIPHER_MODE_CBC,
110                              key, keylen,
111                              errp);
112     if (!aes) {
113         goto cleanup;
114     }
115 
116     if (qcrypto_cipher_setiv(aes, iv, ivlen, errp) < 0) {
117         goto cleanup;
118     }
119 
120     if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
121         ciphertext = qbase64_decode((const gchar*)input,
122                                     inputlen,
123                                     &ciphertextlen,
124                                     errp);
125         if (!ciphertext) {
126             goto cleanup;
127         }
128         plaintext = g_new0(uint8_t, ciphertextlen + 1);
129     } else {
130         ciphertextlen = inputlen;
131         plaintext = g_new0(uint8_t, inputlen + 1);
132     }
133     if (qcrypto_cipher_decrypt(aes,
134                                ciphertext ? ciphertext : input,
135                                plaintext,
136                                ciphertextlen,
137                                errp) < 0) {
138         plaintext = NULL;
139         goto cleanup;
140     }
141 
142     if (plaintext[ciphertextlen - 1] > 16 ||
143         plaintext[ciphertextlen - 1] > ciphertextlen) {
144         error_setg(errp, "Incorrect number of padding bytes (%d) "
145                    "found on decrypted data",
146                    (int)plaintext[ciphertextlen - 1]);
147         g_free(plaintext);
148         plaintext = NULL;
149         goto cleanup;
150     }
151 
152     /* Even though plaintext may contain arbitrary NUL
153      * ensure it is explicitly NUL terminated.
154      */
155     ciphertextlen -= plaintext[ciphertextlen - 1];
156     plaintext[ciphertextlen] = '\0';
157 
158     *output = plaintext;
159     *outputlen = ciphertextlen;
160 
161  cleanup:
162     g_free(ciphertext);
163     g_free(iv);
164     g_free(key);
165     qcrypto_cipher_free(aes);
166 }
167 
168 
169 static void qcrypto_secret_decode(const uint8_t *input,
170                                   size_t inputlen,
171                                   uint8_t **output,
172                                   size_t *outputlen,
173                                   Error **errp)
174 {
175     *output = qbase64_decode((const gchar*)input,
176                              inputlen,
177                              outputlen,
178                              errp);
179 }
180 
181 
182 static void
183 qcrypto_secret_prop_set_loaded(Object *obj,
184                                bool value,
185                                Error **errp)
186 {
187     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
188 
189     if (value) {
190         Error *local_err = NULL;
191         uint8_t *input = NULL;
192         size_t inputlen = 0;
193         uint8_t *output = NULL;
194         size_t outputlen = 0;
195 
196         qcrypto_secret_load_data(secret, &input, &inputlen, &local_err);
197         if (local_err) {
198             error_propagate(errp, local_err);
199             return;
200         }
201 
202         if (secret->keyid) {
203             qcrypto_secret_decrypt(secret, input, inputlen,
204                                    &output, &outputlen, &local_err);
205             g_free(input);
206             if (local_err) {
207                 error_propagate(errp, local_err);
208                 return;
209             }
210             input = output;
211             inputlen = outputlen;
212         } else {
213             if (secret->format != QCRYPTO_SECRET_FORMAT_RAW) {
214                 qcrypto_secret_decode(input, inputlen,
215                                       &output, &outputlen, &local_err);
216                 g_free(input);
217                 if (local_err) {
218                     error_propagate(errp, local_err);
219                     return;
220                 }
221                 input = output;
222                 inputlen = outputlen;
223             }
224         }
225 
226         secret->rawdata = input;
227         secret->rawlen = inputlen;
228     } else {
229         g_free(secret->rawdata);
230         secret->rawlen = 0;
231     }
232 }
233 
234 
235 static bool
236 qcrypto_secret_prop_get_loaded(Object *obj,
237                                Error **errp G_GNUC_UNUSED)
238 {
239     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
240     return secret->data != NULL;
241 }
242 
243 
244 static void
245 qcrypto_secret_prop_set_format(Object *obj,
246                                int value,
247                                Error **errp G_GNUC_UNUSED)
248 {
249     QCryptoSecret *creds = QCRYPTO_SECRET(obj);
250 
251     creds->format = value;
252 }
253 
254 
255 static int
256 qcrypto_secret_prop_get_format(Object *obj,
257                                Error **errp G_GNUC_UNUSED)
258 {
259     QCryptoSecret *creds = QCRYPTO_SECRET(obj);
260 
261     return creds->format;
262 }
263 
264 
265 static void
266 qcrypto_secret_prop_set_data(Object *obj,
267                              const char *value,
268                              Error **errp)
269 {
270     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
271 
272     g_free(secret->data);
273     secret->data = g_strdup(value);
274 }
275 
276 
277 static char *
278 qcrypto_secret_prop_get_data(Object *obj,
279                              Error **errp)
280 {
281     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
282     return g_strdup(secret->data);
283 }
284 
285 
286 static void
287 qcrypto_secret_prop_set_file(Object *obj,
288                              const char *value,
289                              Error **errp)
290 {
291     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
292 
293     g_free(secret->file);
294     secret->file = g_strdup(value);
295 }
296 
297 
298 static char *
299 qcrypto_secret_prop_get_file(Object *obj,
300                              Error **errp)
301 {
302     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
303     return g_strdup(secret->file);
304 }
305 
306 
307 static void
308 qcrypto_secret_prop_set_iv(Object *obj,
309                            const char *value,
310                            Error **errp)
311 {
312     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
313 
314     g_free(secret->iv);
315     secret->iv = g_strdup(value);
316 }
317 
318 
319 static char *
320 qcrypto_secret_prop_get_iv(Object *obj,
321                            Error **errp)
322 {
323     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
324     return g_strdup(secret->iv);
325 }
326 
327 
328 static void
329 qcrypto_secret_prop_set_keyid(Object *obj,
330                               const char *value,
331                               Error **errp)
332 {
333     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
334 
335     g_free(secret->keyid);
336     secret->keyid = g_strdup(value);
337 }
338 
339 
340 static char *
341 qcrypto_secret_prop_get_keyid(Object *obj,
342                               Error **errp)
343 {
344     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
345     return g_strdup(secret->keyid);
346 }
347 
348 
349 static void
350 qcrypto_secret_complete(UserCreatable *uc, Error **errp)
351 {
352     object_property_set_bool(OBJECT(uc), true, "loaded", errp);
353 }
354 
355 
356 static void
357 qcrypto_secret_finalize(Object *obj)
358 {
359     QCryptoSecret *secret = QCRYPTO_SECRET(obj);
360 
361     g_free(secret->iv);
362     g_free(secret->file);
363     g_free(secret->keyid);
364     g_free(secret->rawdata);
365     g_free(secret->data);
366 }
367 
368 static void
369 qcrypto_secret_class_init(ObjectClass *oc, void *data)
370 {
371     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
372 
373     ucc->complete = qcrypto_secret_complete;
374 
375     object_class_property_add_bool(oc, "loaded",
376                                    qcrypto_secret_prop_get_loaded,
377                                    qcrypto_secret_prop_set_loaded,
378                                    NULL);
379     object_class_property_add_enum(oc, "format",
380                                    "QCryptoSecretFormat",
381                                    &QCryptoSecretFormat_lookup,
382                                    qcrypto_secret_prop_get_format,
383                                    qcrypto_secret_prop_set_format,
384                                    NULL);
385     object_class_property_add_str(oc, "data",
386                                   qcrypto_secret_prop_get_data,
387                                   qcrypto_secret_prop_set_data,
388                                   NULL);
389     object_class_property_add_str(oc, "file",
390                                   qcrypto_secret_prop_get_file,
391                                   qcrypto_secret_prop_set_file,
392                                   NULL);
393     object_class_property_add_str(oc, "keyid",
394                                   qcrypto_secret_prop_get_keyid,
395                                   qcrypto_secret_prop_set_keyid,
396                                   NULL);
397     object_class_property_add_str(oc, "iv",
398                                   qcrypto_secret_prop_get_iv,
399                                   qcrypto_secret_prop_set_iv,
400                                   NULL);
401 }
402 
403 
404 int qcrypto_secret_lookup(const char *secretid,
405                           uint8_t **data,
406                           size_t *datalen,
407                           Error **errp)
408 {
409     Object *obj;
410     QCryptoSecret *secret;
411 
412     obj = object_resolve_path_component(
413         object_get_objects_root(), secretid);
414     if (!obj) {
415         error_setg(errp, "No secret with id '%s'", secretid);
416         return -1;
417     }
418 
419     secret = (QCryptoSecret *)
420         object_dynamic_cast(obj,
421                             TYPE_QCRYPTO_SECRET);
422     if (!secret) {
423         error_setg(errp, "Object with id '%s' is not a secret",
424                    secretid);
425         return -1;
426     }
427 
428     if (!secret->rawdata) {
429         error_setg(errp, "Secret with id '%s' has no data",
430                    secretid);
431         return -1;
432     }
433 
434     *data = g_new0(uint8_t, secret->rawlen + 1);
435     memcpy(*data, secret->rawdata, secret->rawlen);
436     (*data)[secret->rawlen] = '\0';
437     *datalen = secret->rawlen;
438 
439     return 0;
440 }
441 
442 
443 char *qcrypto_secret_lookup_as_utf8(const char *secretid,
444                                     Error **errp)
445 {
446     uint8_t *data;
447     size_t datalen;
448 
449     if (qcrypto_secret_lookup(secretid,
450                               &data,
451                               &datalen,
452                               errp) < 0) {
453         return NULL;
454     }
455 
456     if (!g_utf8_validate((const gchar*)data, datalen, NULL)) {
457         error_setg(errp,
458                    "Data from secret %s is not valid UTF-8",
459                    secretid);
460         g_free(data);
461         return NULL;
462     }
463 
464     return (char *)data;
465 }
466 
467 
468 char *qcrypto_secret_lookup_as_base64(const char *secretid,
469                                       Error **errp)
470 {
471     uint8_t *data;
472     size_t datalen;
473     char *ret;
474 
475     if (qcrypto_secret_lookup(secretid,
476                               &data,
477                               &datalen,
478                               errp) < 0) {
479         return NULL;
480     }
481 
482     ret = g_base64_encode(data, datalen);
483     g_free(data);
484     return ret;
485 }
486 
487 
488 static const TypeInfo qcrypto_secret_info = {
489     .parent = TYPE_OBJECT,
490     .name = TYPE_QCRYPTO_SECRET,
491     .instance_size = sizeof(QCryptoSecret),
492     .instance_finalize = qcrypto_secret_finalize,
493     .class_size = sizeof(QCryptoSecretClass),
494     .class_init = qcrypto_secret_class_init,
495     .interfaces = (InterfaceInfo[]) {
496         { TYPE_USER_CREATABLE },
497         { }
498     }
499 };
500 
501 
502 static void
503 qcrypto_secret_register_types(void)
504 {
505     type_register_static(&qcrypto_secret_info);
506 }
507 
508 
509 type_init(qcrypto_secret_register_types);
510