Re: [Qemu-devel] [PULL 05/12] crypto: introduce generic cipher API & built-in implementation

[Aurelien Jarno <aurelien@aurel32.net>]

On 2015-07-07 16:12, Paolo Bonzini wrote:
> From: "Daniel P. Berrange" <berrange@redhat.com>
> 
> Introduce a generic cipher API and an implementation of it that
> supports only the built-in AES and DES-RFB algorithms.
> 
> The test suite checks the supported algorithms + modes to
> validate that every backend implementation is actually correctly
> complying with the specs.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> Message-Id: <1435770638-25715-5-git-send-email-berrange@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  crypto/Makefile.objs       |   1 +
>  crypto/cipher-builtin.c    | 398 +++++++++++++++++++++++++++++++++++++++++++++
>  crypto/cipher.c            |  50 ++++++
>  include/crypto/cipher.h    | 210 ++++++++++++++++++++++++
>  tests/.gitignore           |   1 +
>  tests/Makefile             |   2 +
>  tests/test-crypto-cipher.c | 290 +++++++++++++++++++++++++++++++++
>  7 files changed, 952 insertions(+)
>  create mode 100644 crypto/cipher-builtin.c
>  create mode 100644 crypto/cipher.c
>  create mode 100644 include/crypto/cipher.h
>  create mode 100644 tests/test-crypto-cipher.c
> 
> diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
> index 9f70294..b050138 100644
> --- a/crypto/Makefile.objs
> +++ b/crypto/Makefile.objs
> @@ -2,3 +2,4 @@ util-obj-y += init.o
>  util-obj-y += hash.o
>  util-obj-y += aes.o
>  util-obj-y += desrfb.o
> +util-obj-y += cipher.o
> diff --git a/crypto/cipher-builtin.c b/crypto/cipher-builtin.c
> new file mode 100644
> index 0000000..c625cb4
> --- /dev/null
> +++ b/crypto/cipher-builtin.c
> @@ -0,0 +1,398 @@
> +/*
> + * QEMU Crypto cipher built-in algorithms
> + *
> + * Copyright (c) 2015 Red Hat, Inc.
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +
> +#include "crypto/aes.h"
> +#include "crypto/desrfb.h"
> +
> +typedef struct QCryptoCipherBuiltinAES QCryptoCipherBuiltinAES;
> +struct QCryptoCipherBuiltinAES {
> +    AES_KEY encrypt_key;
> +    AES_KEY decrypt_key;
> +    uint8_t *iv;
> +    size_t niv;
> +};
> +typedef struct QCryptoCipherBuiltinDESRFB QCryptoCipherBuiltinDESRFB;
> +struct QCryptoCipherBuiltinDESRFB {
> +    uint8_t *key;
> +    size_t nkey;
> +};
> +
> +typedef struct QCryptoCipherBuiltin QCryptoCipherBuiltin;
> +struct QCryptoCipherBuiltin {
> +    union {
> +        QCryptoCipherBuiltinAES aes;
> +        QCryptoCipherBuiltinDESRFB desrfb;
> +    } state;
> +    void (*free)(QCryptoCipher *cipher);
> +    int (*setiv)(QCryptoCipher *cipher,
> +                 const uint8_t *iv, size_t niv,
> +                 Error **errp);
> +    int (*encrypt)(QCryptoCipher *cipher,
> +                   const void *in,
> +                   void *out,
> +                   size_t len,
> +                   Error **errp);
> +    int (*decrypt)(QCryptoCipher *cipher,
> +                   const void *in,
> +                   void *out,
> +                   size_t len,
> +                   Error **errp);
> +};
> +
> +
> +static void qcrypto_cipher_free_aes(QCryptoCipher *cipher)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +
> +    g_free(ctxt->state.aes.iv);
> +    g_free(ctxt);
> +    cipher->opaque = NULL;
> +}
> +
> +
> +static int qcrypto_cipher_encrypt_aes(QCryptoCipher *cipher,
> +                                      const void *in,
> +                                      void *out,
> +                                      size_t len,
> +                                      Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +
> +    if (cipher->mode == QCRYPTO_CIPHER_MODE_ECB) {
> +        const uint8_t *inptr = in;
> +        uint8_t *outptr = out;
> +        while (len) {
> +            if (len > AES_BLOCK_SIZE) {
> +                AES_encrypt(inptr, outptr, &ctxt->state.aes.encrypt_key);
> +                inptr += AES_BLOCK_SIZE;
> +                outptr += AES_BLOCK_SIZE;
> +                len -= AES_BLOCK_SIZE;
> +            } else {
> +                uint8_t tmp1[AES_BLOCK_SIZE], tmp2[AES_BLOCK_SIZE];
> +                memcpy(tmp1, inptr, len);
> +                /* Fill with 0 to avoid valgrind uninitialized reads */
> +                memset(tmp1 + len, 0, sizeof(tmp1) - len);
> +                AES_encrypt(tmp1, tmp2, &ctxt->state.aes.encrypt_key);
> +                memcpy(outptr, tmp2, len);
> +                len = 0;
> +            }
> +        }
> +    } else {
> +        AES_cbc_encrypt(in, out, len,
> +                        &ctxt->state.aes.encrypt_key,
> +                        ctxt->state.aes.iv, 1);
> +    }
> +
> +    return 0;
> +}
> +
> +
> +static int qcrypto_cipher_decrypt_aes(QCryptoCipher *cipher,
> +                                      const void *in,
> +                                      void *out,
> +                                      size_t len,
> +                                      Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +
> +    if (cipher->mode == QCRYPTO_CIPHER_MODE_ECB) {
> +        const uint8_t *inptr = in;
> +        uint8_t *outptr = out;
> +        while (len) {
> +            if (len > AES_BLOCK_SIZE) {
> +                AES_decrypt(inptr, outptr, &ctxt->state.aes.encrypt_key);
> +                inptr += AES_BLOCK_SIZE;
> +                outptr += AES_BLOCK_SIZE;
> +                len -= AES_BLOCK_SIZE;
> +            } else {
> +                uint8_t tmp1[AES_BLOCK_SIZE], tmp2[AES_BLOCK_SIZE];
> +                memcpy(tmp1, inptr, len);
> +                /* Fill with 0 to avoid valgrind uninitialized reads */
> +                memset(tmp1 + len, 0, sizeof(tmp1) - len);
> +                AES_decrypt(tmp1, tmp2, &ctxt->state.aes.encrypt_key);
> +                memcpy(outptr, tmp2, len);
> +                len = 0;
> +            }
> +        }
> +    } else {
> +        AES_cbc_encrypt(in, out, len,
> +                        &ctxt->state.aes.encrypt_key,
> +                        ctxt->state.aes.iv, 1);
> +    }
> +
> +    return 0;
> +}
> +
> +static int qcrypto_cipher_setiv_aes(QCryptoCipher *cipher,
> +                                     const uint8_t *iv, size_t niv,
> +                                     Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +    if (niv != 16) {
> +        error_setg(errp, "IV must be 16 bytes not %zu", niv);
> +        return -1;
> +    }
> +
> +    g_free(ctxt->state.aes.iv);
> +    ctxt->state.aes.iv = g_new0(uint8_t, niv);
> +    memcpy(ctxt->state.aes.iv, iv, niv);
> +    ctxt->state.aes.niv = niv;
> +
> +    return 0;
> +}
> +
> +
> +
> +
> +static int qcrypto_cipher_init_aes(QCryptoCipher *cipher,
> +                                   const uint8_t *key, size_t nkey,
> +                                   Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt;
> +
> +    if (cipher->mode != QCRYPTO_CIPHER_MODE_CBC &&
> +        cipher->mode != QCRYPTO_CIPHER_MODE_ECB) {
> +        error_setg(errp, "Unsupported cipher mode %d", cipher->mode);
> +        return -1;
> +    }
> +
> +    ctxt = g_new0(QCryptoCipherBuiltin, 1);
> +
> +    if (AES_set_encrypt_key(key, nkey * 8, &ctxt->state.aes.encrypt_key) != 0) {
> +        error_setg(errp, "Failed to set encryption key");
> +        goto error;
> +    }
> +
> +    if (AES_set_decrypt_key(key, nkey * 8, &ctxt->state.aes.decrypt_key) != 0) {
> +        error_setg(errp, "Failed to set decryption key");
> +        goto error;
> +    }
> +
> +    ctxt->free = qcrypto_cipher_free_aes;
> +    ctxt->setiv = qcrypto_cipher_setiv_aes;
> +    ctxt->encrypt = qcrypto_cipher_encrypt_aes;
> +    ctxt->decrypt = qcrypto_cipher_decrypt_aes;
> +
> +    cipher->opaque = ctxt;
> +
> +    return 0;
> +
> + error:
> +    g_free(ctxt);
> +    return -1;
> +}
> +
> +
> +static void qcrypto_cipher_free_des_rfb(QCryptoCipher *cipher)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +
> +    g_free(ctxt->state.desrfb.key);
> +    g_free(ctxt);
> +    cipher->opaque = NULL;
> +}
> +
> +
> +static int qcrypto_cipher_encrypt_des_rfb(QCryptoCipher *cipher,
> +                                          const void *in,
> +                                          void *out,
> +                                          size_t len,
> +                                          Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +    size_t i;
> +
> +    if (len % 8) {
> +        error_setg(errp, "Buffer size must be multiple of 8 not %zu",
> +                   len);
> +        return -1;
> +    }
> +
> +    deskey(ctxt->state.desrfb.key, EN0);
> +
> +    for (i = 0; i < len; i += 8) {
> +        des((void *)in + i, out + i);
> +    }
> +
> +    return 0;
> +}
> +
> +
> +static int qcrypto_cipher_decrypt_des_rfb(QCryptoCipher *cipher,
> +                                          const void *in,
> +                                          void *out,
> +                                          size_t len,
> +                                          Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;
> +    size_t i;
> +
> +    if (len % 8) {
> +        error_setg(errp, "Buffer size must be multiple of 8 not %zu",
> +                   len);
> +        return -1;
> +    }
> +
> +    deskey(ctxt->state.desrfb.key, DE1);
> +
> +    for (i = 0; i < len; i += 8) {
> +        des((void *)in + i, out + i);
> +    }
> +
> +    return 0;
> +}
> +
> +
> +static int qcrypto_cipher_setiv_des_rfb(QCryptoCipher *cipher,
> +                                        const uint8_t *iv, size_t niv,
> +                                        Error **errp)
> +{
> +    error_setg(errp, "Setting IV is not supported");
> +    return -1;
> +}
> +
> +
> +static int qcrypto_cipher_init_des_rfb(QCryptoCipher *cipher,
> +                                       const uint8_t *key, size_t nkey,
> +                                       Error **errp)
> +{
> +    QCryptoCipherBuiltin *ctxt;
> +
> +    if (cipher->mode != QCRYPTO_CIPHER_MODE_ECB) {
> +        error_setg(errp, "Unsupported cipher mode %d", cipher->mode);
> +        return -1;
> +    }
> +
> +    ctxt = g_new0(QCryptoCipherBuiltin, 1);
> +
> +    ctxt->state.desrfb.key = g_new0(uint8_t, nkey);
> +    memcpy(ctxt->state.desrfb.key, key, nkey);
> +    ctxt->state.desrfb.nkey = nkey;
> +
> +    ctxt->free = qcrypto_cipher_free_des_rfb;
> +    ctxt->setiv = qcrypto_cipher_setiv_des_rfb;
> +    ctxt->encrypt = qcrypto_cipher_encrypt_des_rfb;
> +    ctxt->decrypt = qcrypto_cipher_decrypt_des_rfb;
> +
> +    cipher->opaque = ctxt;
> +
> +    return 0;
> +}
> +
> +
> +bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
> +{
> +    switch (alg) {
> +    case QCRYPTO_CIPHER_ALG_DES_RFB:
> +    case QCRYPTO_CIPHER_ALG_AES_128:
> +    case QCRYPTO_CIPHER_ALG_AES_192:
> +    case QCRYPTO_CIPHER_ALG_AES_256:
> +        return true;
> +    default:
> +        return false;
> +    }
> +}
> +
> +
> +QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
> +                                  QCryptoCipherMode mode,
> +                                  const uint8_t *key, size_t nkey,
> +                                  Error **errp)
> +{
> +    QCryptoCipher *cipher;
> +
> +    cipher = g_new0(QCryptoCipher, 1);
> +    cipher->alg = alg;
> +    cipher->mode = mode;
> +
> +    if (!qcrypto_cipher_validate_key_length(alg, nkey, errp)) {
> +        goto error;
> +    }
> +
> +    switch (cipher->alg) {
> +    case QCRYPTO_CIPHER_ALG_DES_RFB:
> +        if (qcrypto_cipher_init_des_rfb(cipher, key, nkey, errp) < 0) {
> +            goto error;
> +        }
> +        break;
> +    case QCRYPTO_CIPHER_ALG_AES_128:
> +    case QCRYPTO_CIPHER_ALG_AES_192:
> +    case QCRYPTO_CIPHER_ALG_AES_256:
> +        if (qcrypto_cipher_init_aes(cipher, key, nkey, errp) < 0) {
> +            goto error;
> +        }
> +        break;
> +    default:
> +        error_setg(errp,
> +                   "Unsupported cipher algorithm %d", cipher->alg);
> +        goto error;
> +    }
> +
> +    return cipher;
> +
> + error:
> +    g_free(cipher);
> +    return NULL;
> +}
> +
> +void qcrypto_cipher_free(QCryptoCipher *cipher)
> +{
> +    QCryptoCipherBuiltin *ctxt = cipher->opaque;

The pointer is dereferenced here...

> +    if (!cipher) {
> +        return;
> +    }

... but the test for the NULL pointer is only done here. This causes a
crash on a MIPS host and prevents to use any disk image in qcow2
format.

> +    ctxt->free(cipher);
> +    g_free(cipher);
> +}

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                 http://www.aurel32.net