qemu/crypto/secret_common.c
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   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
  31static 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
 127static 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
 140static void
 141qcrypto_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
 194static bool
 195qcrypto_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
 203static void
 204qcrypto_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
 213static int
 214qcrypto_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
 222static void
 223qcrypto_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
 234static char *
 235qcrypto_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
 243static void
 244qcrypto_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
 255static char *
 256qcrypto_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
 264static void
 265qcrypto_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
 274static void
 275qcrypto_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
 298int 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
 337char *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
 362char *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
 382static 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
 397static void
 398qcrypto_secret_register_types(void)
 399{
 400    type_register_static(&qcrypto_secret_info);
 401}
 402
 403
 404type_init(qcrypto_secret_register_types);
 405