include/crypto/secret.h

   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 #ifndef QCRYPTO_SECRET_H
  22 #define QCRYPTO_SECRET_H
  23
  24 #include "qom/object.h"
  25
  26 #define TYPE_QCRYPTO_SECRET "secret"
  27 #define QCRYPTO_SECRET(obj)                  \
  28     OBJECT_CHECK(QCryptoSecret, (obj), TYPE_QCRYPTO_SECRET)
  29
  30 typedef struct QCryptoSecret QCryptoSecret;
  31 typedef struct QCryptoSecretClass QCryptoSecretClass;
  32
  33 /**
  34  * QCryptoSecret:
  35  *
  36  * The QCryptoSecret object provides storage of secrets,
  37  * which may be user passwords, encryption keys or any
  38  * other kind of sensitive data that is represented as
  39  * a sequence of bytes.
  40  *
  41  * The sensitive data associated with the secret can
  42  * be provided directly via the 'data' property, or
  43  * indirectly via the 'file' property. In the latter
  44  * case there is support for file descriptor passing
  45  * via the usual /dev/fdset/NN syntax that QEMU uses.
  46  *
  47  * The data for a secret can be provided in two formats,
  48  * either as a UTF-8 string (the default), or as base64
  49  * encoded 8-bit binary data. The latter is appropriate
  50  * for raw encryption keys, while the former is appropriate
  51  * for user entered passwords.
  52  *
  53  * The data may be optionally encrypted with AES-256-CBC,
  54  * and the decryption key provided by another
  55  * QCryptoSecret instance identified by the 'keyid'
  56  * property. When passing sensitive data directly
  57  * via the 'data' property it is strongly recommended
  58  * to use the AES encryption facility to prevent the
  59  * sensitive data being exposed in the process listing
  60  * or system log files.
  61  *
  62  * Providing data directly, insecurely (suitable for
  63  * ad hoc developer testing only)
  64  *
  65  *  $QEMU -object secret,id=sec0,data=letmein
  66  *
  67  * Providing data indirectly:
  68  *
  69  *  # printf "letmein" > password.txt
  70  *  # $QEMU \
  71  *      -object secret,id=sec0,file=password.txt
  72  *
  73  * Using a master encryption key with data.
  74  *
  75  * The master key needs to be created as 32 secure
  76  * random bytes (optionally base64 encoded)
  77  *
  78  *  # openssl rand -base64 32 > key.b64
  79  *  # KEY=$(base64 -d key.b64 | hexdump  -v -e '/1 "%02X"')
  80  *
  81  * Each secret to be encrypted needs to have a random
  82  * initialization vector generated. These do not need
  83  * to be kept secret
  84  *
  85  *  # openssl rand -base64 16 > iv.b64
  86  *  # IV=$(base64 -d iv.b64 | hexdump  -v -e '/1 "%02X"')
  87  *
  88  * A secret to be defined can now be encrypted
  89  *
  90  *  # SECRET=$(printf "letmein" |
  91  *             openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
  92  *
  93  * When launching QEMU, create a master secret pointing
  94  * to key.b64 and specify that to be used to decrypt
  95  * the user password
  96  *
  97  *  # $QEMU \
  98  *      -object secret,id=secmaster0,format=base64,file=key.b64 \
  99  *      -object secret,id=sec0,keyid=secmaster0,format=base64,\
 100  *          data=$SECRET,iv=$(<iv.b64)
 101  *
 102  * When encrypting, the data can still be provided via an
 103  * external file, in which case it is possible to use either
 104  * raw binary data, or base64 encoded. This example uses
 105  * raw format
 106  *
 107  *  # printf "letmein" |
 108  *       openssl enc -aes-256-cbc -K $KEY -iv $IV -o pw.aes
 109  *  # $QEMU \
 110  *      -object secret,id=secmaster0,format=base64,file=key.b64 \
 111  *      -object secret,id=sec0,keyid=secmaster0,\
 112  *          file=pw.aes,iv=$(<iv.b64)
 113  *
 114  * Note that the ciphertext can be in either raw or base64
 115  * format, as indicated by the 'format' parameter, but the
 116  * plaintext resulting from decryption is expected to always
 117  * be in raw format.
 118  */
 119
 120 struct QCryptoSecret {
 121     Object parent_obj;
 122     uint8_t *rawdata;
 123     size_t rawlen;
 124     QCryptoSecretFormat format;
 125     char *data;
 126     char *file;
 127     char *keyid;
 128     char *iv;
 129 };
 130
 131
 132 struct QCryptoSecretClass {
 133     ObjectClass parent_class;
 134 };
 135
 136
 137 extern int qcrypto_secret_lookup(const char *secretid,
 138                                  uint8_t **data,
 139                                  size_t *datalen,
 140                                  Error **errp);
 141 extern char *qcrypto_secret_lookup_as_utf8(const char *secretid,
 142                                            Error **errp);
 143 extern char *qcrypto_secret_lookup_as_base64(const char *secretid,
 144                                              Error **errp);
 145
 146 #endif /* QCRYPTO_SECRET_H */