crypto: add a gcrypt cipher implementation

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

This will be used when linking against GNUTLS 1.x and many
GNUTLS 2.x versions.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-6-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 195 insertions, 0 deletions

diff --git a/crypto/cipher-gcrypt.c b/crypto/cipher-gcrypt.c
new file mode 100644
index 0000000..8cfc562
--- /dev/null
+++ b/crypto/cipher-gcrypt.c
@@ -0,0 +1,195 @@
+/*
+ * QEMU Crypto cipher libgcrypt 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 <gcrypt.h>
+
+
+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;
+    gcry_cipher_hd_t handle;
+    gcry_error_t err;
+    int gcryalg, gcrymode;
+
+    switch (mode) {
+    case QCRYPTO_CIPHER_MODE_ECB:
+        gcrymode = GCRY_CIPHER_MODE_ECB;
+        break;
+    case QCRYPTO_CIPHER_MODE_CBC:
+        gcrymode = GCRY_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;
+    }
+
+    switch (alg) {
+    case QCRYPTO_CIPHER_ALG_DES_RFB:
+        gcryalg = GCRY_CIPHER_DES;
+        break;
+
+    case QCRYPTO_CIPHER_ALG_AES_128:
+        gcryalg = GCRY_CIPHER_AES128;
+        break;
+
+    case QCRYPTO_CIPHER_ALG_AES_192:
+        gcryalg = GCRY_CIPHER_AES192;
+        break;
+
+    case QCRYPTO_CIPHER_ALG_AES_256:
+        gcryalg = GCRY_CIPHER_AES256;
+        break;
+
+    default:
+        error_setg(errp, "Unsupported cipher algorithm %d", alg);
+        return NULL;
+    }
+
+    cipher = g_new0(QCryptoCipher, 1);
+    cipher->alg = alg;
+    cipher->mode = mode;
+
+    err = gcry_cipher_open(&handle, gcryalg, gcrymode, 0);
+    if (err != 0) {
+        error_setg(errp, "Cannot initialize cipher: %s",
+                   gcry_strerror(err));
+        goto error;
+    }
+
+    if (cipher->alg == QCRYPTO_CIPHER_ALG_DES_RFB) {
+        /* We're using standard DES cipher from gcrypt, so we need
+         * to munge the key so that the results are the same as the
+         * bizarre RFB variant of DES :-)
+         */
+        uint8_t *rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
+        err = gcry_cipher_setkey(handle, rfbkey, nkey);
+        g_free(rfbkey);
+    } else {
+        err = gcry_cipher_setkey(handle, key, nkey);
+    }
+    if (err != 0) {
+        error_setg(errp, "Cannot set key: %s",
+                   gcry_strerror(err));
+        goto error;
+    }
+
+    cipher->opaque = handle;
+    return cipher;
+
+ error:
+    gcry_cipher_close(handle);
+    g_free(cipher);
+    return NULL;
+}
+
+
+void qcrypto_cipher_free(QCryptoCipher *cipher)
+{
+    gcry_cipher_hd_t handle;
+    if (!cipher) {
+        return;
+    }
+    handle = cipher->opaque;
+    gcry_cipher_close(handle);
+    g_free(cipher);
+}
+
+
+int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
+                           const void *in,
+                           void *out,
+                           size_t len,
+                           Error **errp)
+{
+    gcry_cipher_hd_t handle = cipher->opaque;
+    gcry_error_t err;
+
+    err = gcry_cipher_encrypt(handle,
+                              out, len,
+                              in, len);
+    if (err != 0) {
+        error_setg(errp, "Cannot encrypt data: %s",
+                   gcry_strerror(err));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
+                           const void *in,
+                           void *out,
+                           size_t len,
+                           Error **errp)
+{
+    gcry_cipher_hd_t handle = cipher->opaque;
+    gcry_error_t err;
+
+    err = gcry_cipher_decrypt(handle,
+                              out, len,
+                              in, len);
+    if (err != 0) {
+        error_setg(errp, "Cannot decrypt data: %s",
+                   gcry_strerror(err));
+        return -1;
+    }
+
+    return 0;
+}
+
+int qcrypto_cipher_setiv(QCryptoCipher *cipher,
+                         const uint8_t *iv, size_t niv,
+                         Error **errp)
+{
+    gcry_cipher_hd_t handle = cipher->opaque;
+    gcry_error_t err;
+
+    gcry_cipher_reset(handle);
+    err = gcry_cipher_setiv(handle, iv, niv);
+    if (err != 0) {
+        error_setg(errp, "Cannot set IV: %s",
+                   gcry_strerror(err));
+        return -1;
+    }
+
+    return 0;
+}