crypto: add support for generating initialization vectors

There are a number of different algorithms that can be used
to generate initialization vectors for disk encryption. This
introduces a simple internal QCryptoBlockIV object to provide
a consistent internal API to the different algorithms. The
initially implemented algorithms are 'plain', 'plain64' and
'essiv', each matching the same named algorithm provided
by the Linux kernel dm-crypt driver.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/crypto/ivgen-plain.c b/crypto/ivgen-plain.c
new file mode 100644
index 0000000000..6a85256cac
--- /dev/null
+++ b/crypto/ivgen-plain.c
@@ -0,0 +1,59 @@
+/*
+ * QEMU Crypto block IV generator - plain
+ *
+ * Copyright (c) 2015-2016 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 "qemu/osdep.h"
+#include "crypto/ivgen-plain.h"
+
+static int qcrypto_ivgen_plain_init(QCryptoIVGen *ivgen,
+                                    const uint8_t *key, size_t nkey,
+                                    Error **errp)
+{
+    return 0;
+}
+
+static int qcrypto_ivgen_plain_calculate(QCryptoIVGen *ivgen,
+                                         uint64_t sector,
+                                         uint8_t *iv, size_t niv,
+                                         Error **errp)
+{
+    size_t ivprefix;
+    uint32_t shortsector = cpu_to_le32((sector & 0xffffffff));
+    ivprefix = sizeof(shortsector);
+    if (ivprefix > niv) {
+        ivprefix = niv;
+    }
+    memcpy(iv, &shortsector, ivprefix);
+    if (ivprefix < niv) {
+        memset(iv + ivprefix, 0, niv - ivprefix);
+    }
+    return 0;
+}
+
+static void qcrypto_ivgen_plain_cleanup(QCryptoIVGen *ivgen)
+{
+}
+
+
+struct QCryptoIVGenDriver qcrypto_ivgen_plain = {
+    .init = qcrypto_ivgen_plain_init,
+    .calculate = qcrypto_ivgen_plain_calculate,
+    .cleanup = qcrypto_ivgen_plain_cleanup,
+};
+