xref: /openbmc/qemu/crypto/secret_common.c (revision f6476697) 
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 2.1 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/secret_common.h"
23 #include "crypto/cipher.h"
24 #include "qapi/error.h"
25 #include "qom/object_interfaces.h"
26 #include "qemu/base64.h"
27 #include "qemu/module.h"
28 #include "trace.h"
29 
30 
31 static void qcrypto_secret_decrypt(QCryptoSecretCommon *secret,
32                                    const uint8_t *input,
33                                    size_t inputlen,
34                                    uint8_t **output,
35                                    size_t *outputlen,
36                                    Error **errp)
37 {
38     g_autofree uint8_t *iv = NULL;
39     g_autofree uint8_t *key = NULL;
40     g_autofree uint8_t *ciphertext = NULL;
41     size_t keylen, ciphertextlen, ivlen;
42     g_autoptr(QCryptoCipher) aes = NULL;
43     g_autofree uint8_t *plaintext = NULL;
44 
45     *output = NULL;
46     *outputlen = 0;
47 
48     if (qcrypto_secret_lookup(secret->keyid,
49                               &key, &keylen,
50                               errp) < 0) {
51         return;
52     }
53 
54     if (keylen != 32) {
55         error_setg(errp, "Key should be 32 bytes in length");
56         return;
57     }
58 
59     if (!secret->iv) {
60         error_setg(errp, "IV is required to decrypt secret");
61         return;
62     }
63 
64     iv = qbase64_decode(secret->iv, -1, &ivlen, errp);
65     if (!iv) {
66         return;
67     }
68     if (ivlen != 16) {
69         error_setg(errp, "IV should be 16 bytes in length not %zu",
70                    ivlen);
71         return;
72     }
73 
74     aes = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_256,
75                              QCRYPTO_CIPHER_MODE_CBC,
76                              key, keylen,
77                              errp);
78     if (!aes) {
79         return;
80     }
81 
82     if (qcrypto_cipher_setiv(aes, iv, ivlen, errp) < 0) {
83         return;
84     }
85 
86     if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
87         ciphertext = qbase64_decode((const gchar *)input,
88                                     inputlen,
89                                     &ciphertextlen,
90                                     errp);
91         if (!ciphertext) {
92             return;
93         }
94         plaintext = g_new0(uint8_t, ciphertextlen + 1);
95     } else {
96         ciphertextlen = inputlen;
97         plaintext = g_new0(uint8_t, inputlen + 1);
98     }
99     if (qcrypto_cipher_decrypt(aes,
100                                ciphertext ? ciphertext : input,
101                                plaintext,
102                                ciphertextlen,
103                                errp) < 0) {
104         return;
105     }
106 
107     if (plaintext[ciphertextlen - 1] > 16 ||
108         plaintext[ciphertextlen - 1] > ciphertextlen) {
109         error_setg(errp, "Incorrect number of padding bytes (%d) "
110                    "found on decrypted data",
111                    (int)plaintext[ciphertextlen - 1]);
112         return;
113     }
114 
115     /*
116      *  Even though plaintext may contain arbitrary NUL
117      * ensure it is explicitly NUL terminated.
118      */
119     ciphertextlen -= plaintext[ciphertextlen - 1];
120     plaintext[ciphertextlen] = '\0';
121 
122     *output = g_steal_pointer(&plaintext);
123     *outputlen = ciphertextlen;
124 }
125 
126 
127 static void qcrypto_secret_decode(const uint8_t *input,
128                                   size_t inputlen,
129                                   uint8_t **output,
130                                   size_t *outputlen,
131                                   Error **errp)
132 {
133     *output = qbase64_decode((const gchar *)input,
134                              inputlen,
135                              outputlen,
136                              errp);
137 }
138 
139 
140 static void
141 qcrypto_secret_prop_set_loaded(Object *obj,
142                                bool value,
143                                Error **errp)
144 {
145     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
146     QCryptoSecretCommonClass *sec_class
147                                 = QCRYPTO_SECRET_COMMON_GET_CLASS(obj);
148 
149     if (value) {
150         Error *local_err = NULL;
151         uint8_t *input = NULL;
152         size_t inputlen = 0;
153         uint8_t *output = NULL;
154         size_t outputlen = 0;
155 
156         if (sec_class->load_data) {
157             sec_class->load_data(secret, &input, &inputlen, &local_err);
158             if (local_err) {
159                 error_propagate(errp, local_err);
160                 return;
161             }
162         } else {
163             error_setg(errp, "%s provides no 'load_data' method'",
164                              object_get_typename(obj));
165             return;
166         }
167 
168         if (secret->keyid) {
169             qcrypto_secret_decrypt(secret, input, inputlen,
170                                    &output, &outputlen, &local_err);
171             g_free(input);
172             if (local_err) {
173                 error_propagate(errp, local_err);
174                 return;
175             }
176             input = output;
177             inputlen = outputlen;
178         } else {
179             if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
180                 qcrypto_secret_decode(input, inputlen,
181                                       &output, &outputlen, &local_err);
182                 g_free(input);
183                 if (local_err) {
184                     error_propagate(errp, local_err);
185                     return;
186                 }
187                 input = output;
188                 inputlen = outputlen;
189             }
190         }
191 
192         secret->rawdata = input;
193         secret->rawlen = inputlen;
194     } else if (secret->rawdata) {
195         error_setg(errp, "Cannot unload secret");
196         return;
197     }
198 }
199 
200 
201 static bool
202 qcrypto_secret_prop_get_loaded(Object *obj,
203                                Error **errp G_GNUC_UNUSED)
204 {
205     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
206     return secret->rawdata != NULL;
207 }
208 
209 
210 static void
211 qcrypto_secret_prop_set_format(Object *obj,
212                                int value,
213                                Error **errp G_GNUC_UNUSED)
214 {
215     QCryptoSecretCommon *creds = QCRYPTO_SECRET_COMMON(obj);
216     creds->format = value;
217 }
218 
219 
220 static int
221 qcrypto_secret_prop_get_format(Object *obj,
222                                Error **errp G_GNUC_UNUSED)
223 {
224     QCryptoSecretCommon *creds = QCRYPTO_SECRET_COMMON(obj);
225     return creds->format;
226 }
227 
228 
229 static void
230 qcrypto_secret_prop_set_iv(Object *obj,
231                            const char *value,
232                            Error **errp)
233 {
234     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
235 
236     g_free(secret->iv);
237     secret->iv = g_strdup(value);
238 }
239 
240 
241 static char *
242 qcrypto_secret_prop_get_iv(Object *obj,
243                            Error **errp)
244 {
245     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
246     return g_strdup(secret->iv);
247 }
248 
249 
250 static void
251 qcrypto_secret_prop_set_keyid(Object *obj,
252                               const char *value,
253                               Error **errp)
254 {
255     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
256 
257     g_free(secret->keyid);
258     secret->keyid = g_strdup(value);
259 }
260 
261 
262 static char *
263 qcrypto_secret_prop_get_keyid(Object *obj,
264                               Error **errp)
265 {
266     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
267     return g_strdup(secret->keyid);
268 }
269 
270 
271 static void
272 qcrypto_secret_complete(UserCreatable *uc, Error **errp)
273 {
274     object_property_set_bool(OBJECT(uc), "loaded", true, errp);
275 }
276 
277 
278 static void
279 qcrypto_secret_finalize(Object *obj)
280 {
281     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
282 
283     g_free(secret->iv);
284     g_free(secret->keyid);
285     g_free(secret->rawdata);
286 }
287 
288 static void
289 qcrypto_secret_class_init(ObjectClass *oc, void *data)
290 {
291     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
292 
293     ucc->complete = qcrypto_secret_complete;
294 
295     object_class_property_add_bool(oc, "loaded",
296                                    qcrypto_secret_prop_get_loaded,
297                                    qcrypto_secret_prop_set_loaded);
298     object_class_property_add_enum(oc, "format",
299                                    "QCryptoSecretFormat",
300                                    &QCryptoSecretFormat_lookup,
301                                    qcrypto_secret_prop_get_format,
302                                    qcrypto_secret_prop_set_format);
303     object_class_property_add_str(oc, "keyid",
304                                   qcrypto_secret_prop_get_keyid,
305                                   qcrypto_secret_prop_set_keyid);
306     object_class_property_add_str(oc, "iv",
307                                   qcrypto_secret_prop_get_iv,
308                                   qcrypto_secret_prop_set_iv);
309 }
310 
311 
312 int qcrypto_secret_lookup(const char *secretid,
313                           uint8_t **data,
314                           size_t *datalen,
315                           Error **errp)
316 {
317     Object *obj;
318     QCryptoSecretCommon *secret;
319 
320     obj = object_resolve_path_component(
321         object_get_objects_root(), secretid);
322     if (!obj) {
323         error_setg(errp, "No secret with id '%s'", secretid);
324         return -1;
325     }
326 
327     secret = (QCryptoSecretCommon *)
328         object_dynamic_cast(obj,
329                             TYPE_QCRYPTO_SECRET_COMMON);
330     if (!secret) {
331         error_setg(errp, "Object with id '%s' is not a secret",
332                    secretid);
333         return -1;
334     }
335 
336     if (!secret->rawdata) {
337         error_setg(errp, "Secret with id '%s' has no data",
338                    secretid);
339         return -1;
340     }
341 
342     *data = g_new0(uint8_t, secret->rawlen + 1);
343     memcpy(*data, secret->rawdata, secret->rawlen);
344     (*data)[secret->rawlen] = '\0';
345     *datalen = secret->rawlen;
346 
347     return 0;
348 }
349 
350 
351 char *qcrypto_secret_lookup_as_utf8(const char *secretid,
352                                     Error **errp)
353 {
354     uint8_t *data;
355     size_t datalen;
356 
357     if (qcrypto_secret_lookup(secretid,
358                               &data,
359                               &datalen,
360                               errp) < 0) {
361         return NULL;
362     }
363 
364     if (!g_utf8_validate((const gchar *)data, datalen, NULL)) {
365         error_setg(errp,
366                    "Data from secret %s is not valid UTF-8",
367                    secretid);
368         g_free(data);
369         return NULL;
370     }
371 
372     return (char *)data;
373 }
374 
375 
376 char *qcrypto_secret_lookup_as_base64(const char *secretid,
377                                       Error **errp)
378 {
379     uint8_t *data;
380     size_t datalen;
381     char *ret;
382 
383     if (qcrypto_secret_lookup(secretid,
384                               &data,
385                               &datalen,
386                               errp) < 0) {
387         return NULL;
388     }
389 
390     ret = g_base64_encode(data, datalen);
391     g_free(data);
392     return ret;
393 }
394 
395 
396 static const TypeInfo qcrypto_secret_info = {
397     .parent = TYPE_OBJECT,
398     .name = TYPE_QCRYPTO_SECRET_COMMON,
399     .instance_size = sizeof(QCryptoSecretCommon),
400     .instance_finalize = qcrypto_secret_finalize,
401     .class_size = sizeof(QCryptoSecretCommonClass),
402     .class_init = qcrypto_secret_class_init,
403     .abstract = true,
404     .interfaces = (InterfaceInfo[]) {
405         { TYPE_USER_CREATABLE },
406         { }
407     }
408 };
409 
410 
411 static void
412 qcrypto_secret_register_types(void)
413 {
414     type_register_static(&qcrypto_secret_info);
415 }
416 
417 
418 type_init(qcrypto_secret_register_types);
419