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crypto: add sanity checking of plaintext/ciphertext length

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When encrypting/decrypting data, the plaintext/ciphertext
buffers are required to be a multiple of the cipher block
size. If this is not done, nettle will abort and gcrypt
will report an error. To get consistent behaviour add
explicit checks upfront for the buffer sizes.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrange 2015-10-16 16:35:06 +01:00
parent eb2a770b17
commit 3a661f1eab
4 changed files with 130 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

28
crypto/cipher-nettle.c
View file

@ -69,7 +69,7 @@ struct QCryptoCipherNettle {
nettle_cipher_func *alg_encrypt;
nettle_cipher_func *alg_decrypt;
uint8_t *iv;
size_t niv;
size_t blocksize;
};
bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
@ -125,7 +125,7 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
ctx->alg_encrypt = des_encrypt_wrapper;
ctx->alg_decrypt = des_decrypt_wrapper;
ctx->niv = DES_BLOCK_SIZE;
ctx->blocksize = DES_BLOCK_SIZE;
break;
case QCRYPTO_CIPHER_ALG_AES_128:
@ -140,14 +140,14 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
ctx->alg_encrypt = aes_encrypt_wrapper;
ctx->alg_decrypt = aes_decrypt_wrapper;
ctx->niv = AES_BLOCK_SIZE;
ctx->blocksize = AES_BLOCK_SIZE;
break;
default:
error_setg(errp, "Unsupported cipher algorithm %d", alg);
goto error;
}
ctx->iv = g_new0(uint8_t, ctx->niv);
ctx->iv = g_new0(uint8_t, ctx->blocksize);
cipher->opaque = ctx;
return cipher;
@ -184,6 +184,12 @@ int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
ctx->alg_encrypt(ctx->ctx_encrypt, len, out, in);
@ -191,7 +197,7 @@ int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
case QCRYPTO_CIPHER_MODE_CBC:
cbc_encrypt(ctx->ctx_encrypt, ctx->alg_encrypt,
ctx->niv, ctx->iv,
ctx->blocksize, ctx->iv,
len, out, in);
break;
default:
@ -211,6 +217,12 @@ int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
ctx->alg_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
@ -219,7 +231,7 @@ int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
case QCRYPTO_CIPHER_MODE_CBC:
cbc_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
ctx->alg_decrypt, ctx->niv, ctx->iv,
ctx->alg_decrypt, ctx->blocksize, ctx->iv,
len, out, in);
break;
default:
@ -235,9 +247,9 @@ int qcrypto_cipher_setiv(QCryptoCipher *cipher,
Error **errp)
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (niv != ctx->niv) {
if (niv != ctx->blocksize) {
error_setg(errp, "Expected IV size %zu not %zu",
ctx->niv, niv);
ctx->blocksize, niv);
return -1;
}
memcpy(ctx->iv, iv, niv);