On 05/19/2016 05:00 AM, Peter Krempa wrote:
> On Wed, May 18, 2016 at 19:52:32 -0400, John Ferlan wrote:
>> Introduce virCryptoHaveEncrypt and virCryptoEncryptSecret to handle
>> performing encryption.
>>
>> virCryptoHaveEncrypt:
>> Boolean function to determine whether the requested encryption
>> API is available. It's expected this API will be called prior to
>> virCryptoEncryptSecret. It will return true/false.
>>
>> virCryptoEncryptSecret:
>> Based on the requested encryption type, call the specific encryption
>> API to encrypt the data.
>>
>> Currently the only algorithm support is the AES 256 CBC encryption.
>>
>> Adjust tests for the API's
>>
>> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
>> ---
>> configure.ac | 1 +
>> src/libvirt_private.syms | 2 +
>> src/util/vircrypto.c | 189 ++++++++++++++++++++++++++++++++++++++++++++++-
>> src/util/vircrypto.h | 20 ++++-
>> tests/vircryptotest.c | 86 +++++++++++++++++++++
>> 5 files changed, 296 insertions(+), 2 deletions(-)
>>
>
> [...]
>
>> diff --git a/src/util/vircrypto.c b/src/util/vircrypto.c
>> index 39a479a..05bd167 100644
>> --- a/src/util/vircrypto.c
>> +++ b/src/util/vircrypto.c
>
> [...]
>
>> @@ -76,3 +85,181 @@ virCryptoHashString(virCryptoHash hash,
>>
>> return 0;
>> }
>> +
>> +
>> +/* virCryptoHaveEncrypt:
>> + * @algorithm: Specific encryption algorithm desired
>> + *
>> + * Expected to be called prior to virCryptoEncryptData in order
>> + * to determine whether the requested encryption option is available,
>> + * so that "other" alternatives can be taken if the algorithm is
>> + * not available.
>> + *
>> + * Returns true if we can support the encryption.
>> + */
>> +bool
>> +virCryptoHaveEncrypt(virCryptoEncrypt algorithm)
>
> Cipher rather than Encrypt
>
Fine -
>> +{
>> + switch (algorithm) {
>> +
>> + case VIR_CRYPTO_ENCRYPT_AES256CBC:
>> +#ifdef HAVE_GNUTLS_CIPHER_ENCRYPT
>> + return true;
>> +#else
>> + return false;
>> +#endif
>> +
>> + case VIR_CRYPTO_ENCRYPT_NONE:
>> + case VIR_CRYPTO_ENCRYPT_LAST:
>> + break;
>> + };
>> +
>> + return false;
>> +}
>> +
>> +
>> +/* virCryptoEncryptDataAESgntuls:
>> + *
>> + * Performs the AES gnutls encryption - parameters essentially the
>> + * same as virCryptoEncryptSecret, except the libvirt algorithm is
>> + * converted to the gnutls_cipher_algorithm_t
>> + *
>> + * Same input as virCryptoEncryptData, but ensures encryption key and
>> + * initialization vector lengths are correct.
>> + *
>> + * The data buffer will be cleared as soon as it has been prepared for
>> + * encryption.
>> + *
>> + * Encrypts the @data buffer using the @enckey and if available the @iv
>> + *
>> + * Returns 0 on success with the ciphertext being filled. It is the
>> + * caller's responsibility to clear and free it. Returns -1 on failure
>> + * w/ error set.
>> + */
>> +static int
>> +virCryptoEncryptDataAESgnutls(gnutls_cipher_algorithm_t gnutls_enc_alg,
>> + uint8_t *enckey,
>> + size_t enckeylen,
>> + uint8_t *iv,
>> + size_t ivlen,
>> + uint8_t *data,
>> + size_t datalen,
>> + uint8_t **ciphertextret,
>> + size_t *ciphertextlenret)
>> +{
>> + int rc;
>> + size_t i;
>> + gnutls_cipher_hd_t handle = NULL;
>> + gnutls_datum_t enc_key;
>> + gnutls_datum_t iv_key;
>
> As pointed out last time, even here it won't compile with gnutls.
>
I was more focused on getting the framework right. I'll add #ifdef
HAVE_GNUTLS_CIPHER_ENCRYPT around the virCryptoEncryptDataAESgnutls
function and around the calling spot where the #else will be a
VIR_ERR_OPERATION_UNSUPPORTED error. I did point out in my cover that
this probably should have been an RFC, but seeing as it's the setup for
the other AES patches - I just went with a v1.
>> + uint8_t *ciphertext;
>> + size_t ciphertextlen;
>> +
>> + /* Allocate a padded buffer, copy in the data, padding the buffer with
^^^^^^^^^^^^^^^^^
>> + * the size of the padding size which is required for decryption, then
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> + * clear the data buffer when we're done. */
>> + ciphertextlen = VIR_ROUND_UP(datalen, 16);
>> + if (VIR_ALLOC_N(ciphertext, ciphertextlen) < 0)
>> + return -1;
>> + memcpy(ciphertext, data, datalen);
>> + for (i = datalen; i < ciphertextlen; i++)
>
> And this still isn't documented.
>
It was, but I'll move it to make it more obvious.
>> + ciphertext[i] = ciphertextlen - datalen;
>> + memset(data, 0, datalen);
>
> The caller should ensure sanitization. Especially sinc its _NOT_ done if
> the above allocation fails. In such case the caller still needs to do
> it.
>
Fine
>> +
>> + /* Initialize the gnutls cipher */
>> + enc_key.size = enckeylen;
>> + enc_key.data = enckey;
>> + if (iv) {
>> + iv_key.size = ivlen;
>> + iv_key.data = iv;
>> + }
>> + if ((rc = gnutls_cipher_init(&handle, gnutls_enc_alg,
>> + &enc_key, &iv_key)) < 0) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR,
>> + _("failed to initialize cipher: '%s'"),
>> + gnutls_strerror(rc));
>> + goto error;
>> + }
>> +
>> + /* Encrypt the data and free the memory for cipher operations */
>> + rc = gnutls_cipher_encrypt(handle, ciphertext, ciphertextlen);
>> + gnutls_cipher_deinit(handle);
>> + if (rc < 0) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR,
>> + _("failed to encrypt the data: '%s'"),
>> + gnutls_strerror(rc));
>> + goto error;
>> + }
>> +
>> + *ciphertextret = ciphertext;
>> + *ciphertextlenret = ciphertextlen;
>> + return 0;
>> +
>> + error:
>> + VIR_DISPOSE_N(ciphertext, ciphertextlen);
>> + return -1;
>> +}
>> +
>> +
>> +/* virCryptoEncryptData:
>> + * @algorithm: algoritm desired for encryption
>> + * @enckey: encryption key
>> + * @enckeylen: encription key length
>> + * @iv: initialization vector
>> + * @ivlen: length of initialization vector
>> + * @data: data to encrypt
>> + * @datalen: length of data
>> + * @ciphertext: stream of bytes allocated to store ciphertext
>> + * @ciphertextlen: size of the stream of bytes
>> + *
>> + * If available, attempt and return the requested encryption type
>> + * using the parameters passed.
>> + *
>> + * Returns 0 on success, -1 on failure with error set
>> + */
>> +int
>> +virCryptoEncryptData(virCryptoEncrypt algorithm,
>> + uint8_t *enckey,
>> + size_t enckeylen,
>> + uint8_t *iv,
>> + size_t ivlen,
>> + uint8_t *data,
>> + size_t datalen,
>> + uint8_t **ciphertext,
>> + size_t *ciphertextlen)
>> +{
>> + switch (algorithm) {
>> + case VIR_CRYPTO_ENCRYPT_AES256CBC:
>> + if (enckeylen != 32) {
>> + virReportError(VIR_ERR_INVALID_ARG,
>> + _("AES256CBC encryption invalid keylen=%zu"),
>> + enckeylen);
>> + return -1;
>> + }
>> +
>> + if (ivlen != 16) {
>> + virReportError(VIR_ERR_INVALID_ARG,
>> + _("AES246CBC initialization vector invalid len=%zu"),
>
> AES256CBC
>
OK
>> + ivlen);
>> + return -1;
>> + }
>> +
>> + /*
>> + * Encrypt the data buffer using an encryption key and
>> + * initialization vector via the gnutls_cipher_encrypt API
>> + * for GNUTLS_CIPHER_AES_256_CBC.
>> + */
>> + return virCryptoEncryptDataAESgnutls(GNUTLS_CIPHER_AES_256_CBC,
>> + enckey, enckeylen, iv, ivlen,
>> + data, datalen,
>> + ciphertext, ciphertextlen);
>> +
>> + case VIR_CRYPTO_ENCRYPT_NONE:
>> + case VIR_CRYPTO_ENCRYPT_LAST:
>> + break;
>> + }
>> +
>> + virReportError(VIR_ERR_INVALID_ARG,
>> + _("algorithm=%d is not supported"), algorithm);
>> + return -1;
>> +}
>> diff --git a/src/util/vircrypto.h b/src/util/vircrypto.h
>> index f67d49d..7d0829e 100644
>> --- a/src/util/vircrypto.h
>> +++ b/src/util/vircrypto.h
>
> [...]
>
>> @@ -30,6 +30,14 @@ typedef enum {
>> VIR_CRYPTO_HASH_LAST
>> } virCryptoHash;
>>
>> +
>> +typedef enum {
>> + VIR_CRYPTO_ENCRYPT_NONE = 0,
>> + VIR_CRYPTO_ENCRYPT_AES256CBC,
>> +
>> + VIR_CRYPTO_ENCRYPT_LAST
>> +} virCryptoEncrypt;
>
> This can be used for decryption too. Thus virCryptoCipher.
>
Sure and the symbols change toe _CIPHER_ as well. That's fine.
>> +
>> int
>> virCryptoHashString(virCryptoHash hash,
>> const char *input,
>
> [...]
>
>> diff --git a/tests/vircryptotest.c b/tests/vircryptotest.c
>> index bfc47db..038eb7a 100644
>> --- a/tests/vircryptotest.c
>> +++ b/tests/vircryptotest.c
>
> [...]
>
>> @@ -56,10 +57,74 @@ testCryptoHash(const void *opaque)
>> }
>>
>>
>> +struct testCryptoEncryptData {
>> + virCryptoEncrypt algorithm;
>> + uint8_t *input;
>> + size_t inputlen;
>> + const char *base64;
>> +};
>> +
>> +static int
>> +testCryptoEncrypt(const void *opaque)
>> +{
>> + const struct testCryptoEncryptData *data = opaque;
>> + size_t i;
>> + uint8_t *enckey = NULL;
>> + size_t enckeylen = 32;
>> + uint8_t *iv = NULL;
>> + size_t ivlen = 16;
>> + uint8_t *ciphertext = NULL;
>> + size_t ciphertextlen = 0;
>> + char *actual = NULL;
>> + int ret = -1;
>> +
>> + if (!virCryptoHaveEncrypt(data->algorithm)) {
>> + fprintf(stderr, "Invalid encryption algorithm=%d\n", data->algorithm);
>> + return -1;
>> + }
>> +
>> + if (VIR_ALLOC_N(enckey, enckeylen) < 0 ||
>> + VIR_ALLOC_N(iv, ivlen) < 0)
>> + goto cleanup;
>> +
>> + /* To be replaced by mock if I can get it to work */
>
> Why not keep it this way? This is testing the encryption not the key
> generation.
>
Well I was *hoping* to get the mock to work... Something covered between
patch 2 and the cover (which IIRC you don't read covers).
>> + for (i = 0; i < enckeylen; i++)
>> + enckey[i] = i;
>> + for (i = 0; i < ivlen; i++)
>> + iv[i] = i;
>> +
>> + if (virCryptoEncryptData(data->algorithm, enckey, enckeylen, iv, ivlen,
>> + data->input, data->inputlen,
>> + &ciphertext, &ciphertextlen) < 0)
>> + goto cleanup;
>> +
>> + /* Comparing the encoded ciphertext would be what is desired in
>> + * the long run and easier to read/format the expected ciphertext */
>
> Read? nobody is going to read it if it doesn't match.
>
OK - so I took the other route - passing in an expected cipher value.
>> + if (!(actual = virStringEncodeBase64(ciphertext, ciphertextlen)))
>> + goto cleanup;
>> +
>> + if (STRNEQ(data->base64, actual)) {
>> + fprintf(stderr, "Expected encoded encryption '%s' but got '%s'\n",
>> + data->base64, NULLSTR(actual));
>
> and it definitely doesn't make sense to print it. It's just binary
> garbage.
>
I forgot the STRNEQ_NULLABLE too.. hrmph.
>> + goto cleanup;
>> + }
>> +
>> + ret = 0;
>> + cleanup:
>> + VIR_DISPOSE_N(enckey, enckeylen);
>> + VIR_DISPOSE_N(iv, ivlen);
>> + VIR_DISPOSE_N(ciphertext, ciphertextlen);
>
> This isn't really necessary for demo keys. You can also lose the lenght
> variables.
>
OK
>> + VIR_FREE(actual);
>> +
>
> I won't review further versions until you fix the issue with compiling
> without gnutls. I've pointed it out far too many times.
>
I didn't expect v1 to be the last - figured it was more important to get
the structure as expected.
John
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