crypto: add a nettle cipher implementation

If we are linking to gnutls already and gnutls is built against
nettle, then we should use nettle as a cipher backend in
preference to our built-in backend.

This will be used when linking against some GNUTLS 2.x versions
and all GNUTLS 3.x versions.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-7-git-send-email-berrange@redhat.com>
[Change "#elif" to "#elif defined". - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 210 insertions, 2 deletions

diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c
new file mode 100644
index 0000000000..e5a14bc139
--- /dev/null
+++ b/crypto/cipher-nettle.c
@@ -0,0 +1,206 @@
+/*
+ * QEMU Crypto cipher nettle 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 <nettle/nettle-types.h>
+#include <nettle/aes.h>
+#include <nettle/des.h>
+#include <nettle/cbc.h>
+
+typedef struct QCryptoCipherNettle QCryptoCipherNettle;
+struct QCryptoCipherNettle {
+    void *ctx_encrypt;
+    void *ctx_decrypt;
+    nettle_crypt_func *alg_encrypt;
+    nettle_crypt_func *alg_decrypt;
+    uint8_t *iv;
+    size_t niv;
+};
+
+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;
+    QCryptoCipherNettle *ctx;
+    uint8_t *rfbkey;
+
+    switch (mode) {
+    case QCRYPTO_CIPHER_MODE_ECB:
+    case QCRYPTO_CIPHER_MODE_CBC:
+        break;
+    default:
+        error_setg(errp, "Unsupported cipher mode %d", mode);
+        return NULL;
+    }
+
+    if (!qcrypto_cipher_validate_key_length(alg, nkey, errp)) {
+        return NULL;
+    }
+
+    cipher = g_new0(QCryptoCipher, 1);
+    cipher->alg = alg;
+    cipher->mode = mode;
+
+    ctx = g_new0(QCryptoCipherNettle, 1);
+
+    switch (alg) {
+    case QCRYPTO_CIPHER_ALG_DES_RFB:
+        ctx->ctx_encrypt = g_new0(struct des_ctx, 1);
+        ctx->ctx_decrypt = NULL; /* 1 ctx can do both */
+        rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
+        des_set_key(ctx->ctx_encrypt, rfbkey);
+        g_free(rfbkey);
+
+        ctx->alg_encrypt = (nettle_crypt_func *)des_encrypt;
+        ctx->alg_decrypt = (nettle_crypt_func *)des_decrypt;
+
+        ctx->niv = DES_BLOCK_SIZE;
+        break;
+
+    case QCRYPTO_CIPHER_ALG_AES_128:
+    case QCRYPTO_CIPHER_ALG_AES_192:
+    case QCRYPTO_CIPHER_ALG_AES_256:
+        ctx->ctx_encrypt = g_new0(struct aes_ctx, 1);
+        ctx->ctx_decrypt = g_new0(struct aes_ctx, 1);
+
+        aes_set_encrypt_key(ctx->ctx_encrypt, nkey, key);
+        aes_set_decrypt_key(ctx->ctx_decrypt, nkey, key);
+
+        ctx->alg_encrypt = (nettle_crypt_func *)aes_encrypt;
+        ctx->alg_decrypt = (nettle_crypt_func *)aes_decrypt;
+
+        ctx->niv = AES_BLOCK_SIZE;
+        break;
+    default:
+        error_setg(errp, "Unsupported cipher algorithm %d", alg);
+        goto error;
+    }
+
+    ctx->iv = g_new0(uint8_t, ctx->niv);
+    cipher->opaque = ctx;
+
+    return cipher;
+
+ error:
+    g_free(cipher);
+    g_free(ctx);
+    return NULL;
+}
+
+
+void qcrypto_cipher_free(QCryptoCipher *cipher)
+{
+    QCryptoCipherNettle *ctx;
+
+    if (!cipher) {
+        return;
+    }
+
+    ctx = cipher->opaque;
+    g_free(ctx->iv);
+    g_free(ctx->ctx_encrypt);
+    g_free(ctx->ctx_decrypt);
+    g_free(ctx);
+    g_free(cipher);
+}
+
+
+int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
+                           const void *in,
+                           void *out,
+                           size_t len,
+                           Error **errp)
+{
+    QCryptoCipherNettle *ctx = cipher->opaque;
+
+    switch (cipher->mode) {
+    case QCRYPTO_CIPHER_MODE_ECB:
+        ctx->alg_encrypt(ctx->ctx_encrypt, len, out, in);
+        break;
+
+    case QCRYPTO_CIPHER_MODE_CBC:
+        cbc_encrypt(ctx->ctx_encrypt, ctx->alg_encrypt,
+                    ctx->niv, ctx->iv,
+                    len, out, in);
+        break;
+    default:
+        error_setg(errp, "Unsupported cipher algorithm %d",
+                   cipher->alg);
+        return -1;
+    }
+    return 0;
+}
+
+
+int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
+                           const void *in,
+                           void *out,
+                           size_t len,
+                           Error **errp)
+{
+    QCryptoCipherNettle *ctx = cipher->opaque;
+
+    switch (cipher->mode) {
+    case QCRYPTO_CIPHER_MODE_ECB:
+        ctx->alg_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
+                         len, out, in);
+        break;
+
+    case QCRYPTO_CIPHER_MODE_CBC:
+        cbc_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
+                    ctx->alg_decrypt, ctx->niv, ctx->iv,
+                    len, out, in);
+        break;
+    default:
+        error_setg(errp, "Unsupported cipher algorithm %d",
+                   cipher->alg);
+        return -1;
+    }
+    return 0;
+}
+
+int qcrypto_cipher_setiv(QCryptoCipher *cipher,
+                         const uint8_t *iv, size_t niv,
+                         Error **errp)
+{
+    QCryptoCipherNettle *ctx = cipher->opaque;
+    if (niv != ctx->niv) {
+        error_setg(errp, "Expected IV size %zu not %zu",
+                   ctx->niv, niv);
+        return -1;
+    }
+    memcpy(ctx->iv, iv, niv);
+    return 0;
+}
diff --git a/crypto/cipher.c b/crypto/cipher.c
index ed4d854a13..024a00cb54 100644
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -47,7 +47,7 @@ qcrypto_cipher_validate_key_length(QCryptoCipherAlgorithm alg,
     return true;
 }
 
-#if defined(CONFIG_GNUTLS_GCRYPT)
+#if defined(CONFIG_GNUTLS_GCRYPT) || defined(CONFIG_GNUTLS_NETTLE)
 static uint8_t *
 qcrypto_cipher_munge_des_rfb_key(const uint8_t *key,
                                  size_t nkey)
@@ -63,10 +63,12 @@ qcrypto_cipher_munge_des_rfb_key(const uint8_t *key,
     }
     return ret;
 }
-#endif /* CONFIG_GNUTLS_GCRYPT */
+#endif /* CONFIG_GNUTLS_GCRYPT || CONFIG_GNUTLS_NETTLE */
 
 #ifdef CONFIG_GNUTLS_GCRYPT
 #include "crypto/cipher-gcrypt.c"
+#elif defined CONFIG_GNUTLS_NETTLE
+#include "crypto/cipher-nettle.c"
 #else
 #include "crypto/cipher-builtin.c"
 #endif