crypto/secret_common.c

   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_ALGO_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_complete(UserCreatable *uc, Error **errp)
 142 {
 143     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(uc);
 144     QCryptoSecretCommonClass *sec_class
 145                                 = QCRYPTO_SECRET_COMMON_GET_CLASS(uc);
 146
 147     Error *local_err = NULL;
 148     uint8_t *input = NULL;
 149     size_t inputlen = 0;
 150     uint8_t *output = NULL;
 151     size_t outputlen = 0;
 152
 153     if (sec_class->load_data) {
 154         sec_class->load_data(secret, &input, &inputlen, &local_err);
 155         if (local_err) {
 156             error_propagate(errp, local_err);
 157             return;
 158         }
 159     } else {
 160         error_setg(errp, "%s provides no 'load_data' method'",
 161                          object_get_typename(OBJECT(uc)));
 162         return;
 163     }
 164
 165     if (secret->keyid) {
 166         qcrypto_secret_decrypt(secret, input, inputlen,
 167                                &output, &outputlen, &local_err);
 168         g_free(input);
 169         if (local_err) {
 170             error_propagate(errp, local_err);
 171             return;
 172         }
 173         input = output;
 174         inputlen = outputlen;
 175     } else {
 176         if (secret->format == QCRYPTO_SECRET_FORMAT_BASE64) {
 177             qcrypto_secret_decode(input, inputlen,
 178                                   &output, &outputlen, &local_err);
 179             g_free(input);
 180             if (local_err) {
 181                 error_propagate(errp, local_err);
 182                 return;
 183             }
 184             input = output;
 185             inputlen = outputlen;
 186         }
 187     }
 188
 189     secret->rawdata = input;
 190     secret->rawlen = inputlen;
 191 }
 192
 193
 194 static bool
 195 qcrypto_secret_prop_get_loaded(Object *obj,
 196                                Error **errp G_GNUC_UNUSED)
 197 {
 198     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 199     return secret->rawdata != NULL;
 200 }
 201
 202
 203 static void
 204 qcrypto_secret_prop_set_format(Object *obj,
 205                                int value,
 206                                Error **errp G_GNUC_UNUSED)
 207 {
 208     QCryptoSecretCommon *creds = QCRYPTO_SECRET_COMMON(obj);
 209     creds->format = value;
 210 }
 211
 212
 213 static int
 214 qcrypto_secret_prop_get_format(Object *obj,
 215                                Error **errp G_GNUC_UNUSED)
 216 {
 217     QCryptoSecretCommon *creds = QCRYPTO_SECRET_COMMON(obj);
 218     return creds->format;
 219 }
 220
 221
 222 static void
 223 qcrypto_secret_prop_set_iv(Object *obj,
 224                            const char *value,
 225                            Error **errp)
 226 {
 227     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 228
 229     g_free(secret->iv);
 230     secret->iv = g_strdup(value);
 231 }
 232
 233
 234 static char *
 235 qcrypto_secret_prop_get_iv(Object *obj,
 236                            Error **errp)
 237 {
 238     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 239     return g_strdup(secret->iv);
 240 }
 241
 242
 243 static void
 244 qcrypto_secret_prop_set_keyid(Object *obj,
 245                               const char *value,
 246                               Error **errp)
 247 {
 248     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 249
 250     g_free(secret->keyid);
 251     secret->keyid = g_strdup(value);
 252 }
 253
 254
 255 static char *
 256 qcrypto_secret_prop_get_keyid(Object *obj,
 257                               Error **errp)
 258 {
 259     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 260     return g_strdup(secret->keyid);
 261 }
 262
 263
 264 static void
 265 qcrypto_secret_finalize(Object *obj)
 266 {
 267     QCryptoSecretCommon *secret = QCRYPTO_SECRET_COMMON(obj);
 268
 269     g_free(secret->iv);
 270     g_free(secret->keyid);
 271     g_free(secret->rawdata);
 272 }
 273
 274 static void
 275 qcrypto_secret_class_init(ObjectClass *oc, void *data)
 276 {
 277     UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
 278
 279     ucc->complete = qcrypto_secret_complete;
 280
 281     object_class_property_add_bool(oc, "loaded",
 282                                    qcrypto_secret_prop_get_loaded,
 283                                    NULL);
 284     object_class_property_add_enum(oc, "format",
 285                                    "QCryptoSecretFormat",
 286                                    &QCryptoSecretFormat_lookup,
 287                                    qcrypto_secret_prop_get_format,
 288                                    qcrypto_secret_prop_set_format);
 289     object_class_property_add_str(oc, "keyid",
 290                                   qcrypto_secret_prop_get_keyid,
 291                                   qcrypto_secret_prop_set_keyid);
 292     object_class_property_add_str(oc, "iv",
 293                                   qcrypto_secret_prop_get_iv,
 294                                   qcrypto_secret_prop_set_iv);
 295 }
 296
 297
 298 int qcrypto_secret_lookup(const char *secretid,
 299                           uint8_t **data,
 300                           size_t *datalen,
 301                           Error **errp)
 302 {
 303     Object *obj;
 304     QCryptoSecretCommon *secret;
 305
 306     obj = object_resolve_path_component(
 307         object_get_objects_root(), secretid);
 308     if (!obj) {
 309         error_setg(errp, "No secret with id '%s'", secretid);
 310         return -1;
 311     }
 312
 313     secret = (QCryptoSecretCommon *)
 314         object_dynamic_cast(obj,
 315                             TYPE_QCRYPTO_SECRET_COMMON);
 316     if (!secret) {
 317         error_setg(errp, "Object with id '%s' is not a secret",
 318                    secretid);
 319         return -1;
 320     }
 321
 322     if (!secret->rawdata) {
 323         error_setg(errp, "Secret with id '%s' has no data",
 324                    secretid);
 325         return -1;
 326     }
 327
 328     *data = g_new0(uint8_t, secret->rawlen + 1);
 329     memcpy(*data, secret->rawdata, secret->rawlen);
 330     (*data)[secret->rawlen] = '\0';
 331     *datalen = secret->rawlen;
 332
 333     return 0;
 334 }
 335
 336
 337 char *qcrypto_secret_lookup_as_utf8(const char *secretid,
 338                                     Error **errp)
 339 {
 340     uint8_t *data;
 341     size_t datalen;
 342
 343     if (qcrypto_secret_lookup(secretid,
 344                               &data,
 345                               &datalen,
 346                               errp) < 0) {
 347         return NULL;
 348     }
 349
 350     if (!g_utf8_validate((const gchar *)data, datalen, NULL)) {
 351         error_setg(errp,
 352                    "Data from secret %s is not valid UTF-8",
 353                    secretid);
 354         g_free(data);
 355         return NULL;
 356     }
 357
 358     return (char *)data;
 359 }
 360
 361
 362 char *qcrypto_secret_lookup_as_base64(const char *secretid,
 363                                       Error **errp)
 364 {
 365     uint8_t *data;
 366     size_t datalen;
 367     char *ret;
 368
 369     if (qcrypto_secret_lookup(secretid,
 370                               &data,
 371                               &datalen,
 372                               errp) < 0) {
 373         return NULL;
 374     }
 375
 376     ret = g_base64_encode(data, datalen);
 377     g_free(data);
 378     return ret;
 379 }
 380
 381
 382 static const TypeInfo qcrypto_secret_info = {
 383     .parent = TYPE_OBJECT,
 384     .name = TYPE_QCRYPTO_SECRET_COMMON,
 385     .instance_size = sizeof(QCryptoSecretCommon),
 386     .instance_finalize = qcrypto_secret_finalize,
 387     .class_size = sizeof(QCryptoSecretCommonClass),
 388     .class_init = qcrypto_secret_class_init,
 389     .abstract = true,
 390     .interfaces = (InterfaceInfo[]) {
 391         { TYPE_USER_CREATABLE },
 392         { }
 393     }
 394 };
 395
 396
 397 static void
 398 qcrypto_secret_register_types(void)
 399 {
 400     type_register_static(&qcrypto_secret_info);
 401 }
 402
 403
 404 type_init(qcrypto_secret_register_types);