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_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
 201static bool
 202qcrypto_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
 210static void
 211qcrypto_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
 220static int
 221qcrypto_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
 229static void
 230qcrypto_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
 241static char *
 242qcrypto_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
 250static void
 251qcrypto_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
 262static char *
 263qcrypto_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
 271static void
 272qcrypto_secret_complete(UserCreatable *uc, Error **errp)
 273{
 274    object_property_set_bool(OBJECT(uc), "loaded", true, errp);
 275}
 276
 277
 278static void
 279qcrypto_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
 288static void
 289qcrypto_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
 312int 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
 351char *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
 376char *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
 396static 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
 411static void
 412qcrypto_secret_register_types(void)
 413{
 414    type_register_static(&qcrypto_secret_info);
 415}
 416
 417
 418type_init(qcrypto_secret_register_types);
 419