From 3a661f1eabf7e8db66e28489884d9b54aacb94ea Mon Sep 17 00:00:00 2001
From: Daniel P. Berrange
Date: Fri, 16 Oct 2015 16:35:06 +0100
Subject: crypto: add sanity checking of plaintext/ciphertext length

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>
---
 crypto/cipher-nettle.c | 28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

(limited to 'crypto/cipher-nettle.c')

diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c
index b01cb1c857..7449338d3b 100644
--- a/crypto/cipher-nettle.c
+++ b/crypto/cipher-nettle.c
@@ -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);
-- 
cgit v1.2.3-55-g7522