crypto: add block encryption framework

Add a generic framework for supporting different block encryption
formats. Upon instantiating a QCryptoBlock object, it will read
the encryption header and extract the encryption keys. It is
then possible to call methods to encrypt/decrypt data buffers.

There is also a mode whereby it will create/initialize a new
encryption header on a previously unformatted volume.

The initial framework comes with support for the legacy QCow
AES based encryption. This enables code in the QCow driver to
be consolidated later.

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

5 files changed, 553 insertions, 0 deletions

diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index e6590dc..3ddeb42 100644
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -19,6 +19,8 @@ crypto-obj-y += ivgen-plain.o
 crypto-obj-y += ivgen-plain64.o
 crypto-obj-y += afsplit.o
 crypto-obj-y += xts.o
+crypto-obj-y += block.o
+crypto-obj-y += block-qcow.o
 
 # Let the userspace emulators avoid linking gnutls/etc
 crypto-aes-obj-y = aes.o
diff --git a/crypto/block-qcow.c b/crypto/block-qcow.c
new file mode 100644
index 0000000..9f378e8
--- /dev/null
+++ b/crypto/block-qcow.c
@@ -0,0 +1,173 @@
+/*
+ * QEMU Crypto block device encryption QCow/QCow2 AES-CBC format
+ *
+ * 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/>.
+ *
+ */
+
+/*
+ * Note that the block encryption implemented in this file is broken
+ * by design. This exists only to allow data to be liberated from
+ * existing qcow[2] images and should not be used in any new areas.
+ */
+
+#include "qemu/osdep.h"
+
+#include "crypto/block-qcow.h"
+#include "crypto/secret.h"
+
+#define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512
+
+
+static bool
+qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
+                              size_t buf_size G_GNUC_UNUSED)
+{
+    return false;
+}
+
+
+static int
+qcrypto_block_qcow_init(QCryptoBlock *block,
+                        const char *keysecret,
+                        Error **errp)
+{
+    char *password;
+    int ret;
+    uint8_t keybuf[16];
+    int len;
+
+    memset(keybuf, 0, 16);
+
+    password = qcrypto_secret_lookup_as_utf8(keysecret, errp);
+    if (!password) {
+        return -1;
+    }
+
+    len = strlen(password);
+    memcpy(keybuf, password, MIN(len, sizeof(keybuf)));
+    g_free(password);
+
+    block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
+                                           QCRYPTO_CIPHER_MODE_CBC);
+    block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64,
+                                     0, 0, NULL, 0, errp);
+    if (!block->ivgen) {
+        ret = -ENOTSUP;
+        goto fail;
+    }
+
+    block->cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128,
+                                       QCRYPTO_CIPHER_MODE_CBC,
+                                       keybuf, G_N_ELEMENTS(keybuf),
+                                       errp);
+    if (!block->cipher) {
+        ret = -ENOTSUP;
+        goto fail;
+    }
+
+    block->payload_offset = 0;
+
+    return 0;
+
+ fail:
+    qcrypto_cipher_free(block->cipher);
+    qcrypto_ivgen_free(block->ivgen);
+    return ret;
+}
+
+
+static int
+qcrypto_block_qcow_open(QCryptoBlock *block,
+                        QCryptoBlockOpenOptions *options,
+                        QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,
+                        void *opaque G_GNUC_UNUSED,
+                        unsigned int flags,
+                        Error **errp)
+{
+    if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
+        return 0;
+    } else {
+        if (!options->u.qcow.key_secret) {
+            error_setg(errp,
+                       "Parameter 'key-secret' is required for cipher");
+            return -1;
+        }
+        return qcrypto_block_qcow_init(block,
+                                       options->u.qcow.key_secret, errp);
+    }
+}
+
+
+static int
+qcrypto_block_qcow_create(QCryptoBlock *block,
+                          QCryptoBlockCreateOptions *options,
+                          QCryptoBlockInitFunc initfunc G_GNUC_UNUSED,
+                          QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED,
+                          void *opaque G_GNUC_UNUSED,
+                          Error **errp)
+{
+    if (!options->u.qcow.key_secret) {
+        error_setg(errp, "Parameter 'key-secret' is required for cipher");
+        return -1;
+    }
+    /* QCow2 has no special header, since everything is hardwired */
+    return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp);
+}
+
+
+static void
+qcrypto_block_qcow_cleanup(QCryptoBlock *block)
+{
+}
+
+
+static int
+qcrypto_block_qcow_decrypt(QCryptoBlock *block,
+                           uint64_t startsector,
+                           uint8_t *buf,
+                           size_t len,
+                           Error **errp)
+{
+    return qcrypto_block_decrypt_helper(block->cipher,
+                                        block->niv, block->ivgen,
+                                        QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
+                                        startsector, buf, len, errp);
+}
+
+
+static int
+qcrypto_block_qcow_encrypt(QCryptoBlock *block,
+                           uint64_t startsector,
+                           uint8_t *buf,
+                           size_t len,
+                           Error **errp)
+{
+    return qcrypto_block_encrypt_helper(block->cipher,
+                                        block->niv, block->ivgen,
+                                        QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
+                                        startsector, buf, len, errp);
+}
+
+
+const QCryptoBlockDriver qcrypto_block_driver_qcow = {
+    .open = qcrypto_block_qcow_open,
+    .create = qcrypto_block_qcow_create,
+    .cleanup = qcrypto_block_qcow_cleanup,
+    .decrypt = qcrypto_block_qcow_decrypt,
+    .encrypt = qcrypto_block_qcow_encrypt,
+    .has_format = qcrypto_block_qcow_has_format,
+};
diff --git a/crypto/block-qcow.h b/crypto/block-qcow.h
new file mode 100644
index 0000000..569f836
--- /dev/null
+++ b/crypto/block-qcow.h
@@ -0,0 +1,28 @@
+/*
+ * QEMU Crypto block device encryption QCow/QCow2 AES-CBC format
+ *
+ * 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/>.
+ *
+ */
+
+#ifndef QCRYPTO_BLOCK_QCOW_H__
+#define QCRYPTO_BLOCK_QCOW_H__
+
+#include "crypto/blockpriv.h"
+
+extern const QCryptoBlockDriver qcrypto_block_driver_qcow;
+
+#endif /* QCRYPTO_BLOCK_QCOW_H__ */
diff --git a/crypto/block.c b/crypto/block.c
new file mode 100644
index 0000000..3c27ef0
--- /dev/null
+++ b/crypto/block.c
@@ -0,0 +1,258 @@
+/*
+ * QEMU Crypto block device encryption
+ *
+ * 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/blockpriv.h"
+#include "crypto/block-qcow.h"
+
+static const QCryptoBlockDriver *qcrypto_block_drivers[] = {
+    [Q_CRYPTO_BLOCK_FORMAT_QCOW] = &qcrypto_block_driver_qcow,
+};
+
+
+bool qcrypto_block_has_format(QCryptoBlockFormat format,
+                              const uint8_t *buf,
+                              size_t len)
+{
+    const QCryptoBlockDriver *driver;
+
+    if (format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
+        !qcrypto_block_drivers[format]) {
+        return false;
+    }
+
+    driver = qcrypto_block_drivers[format];
+
+    return driver->has_format(buf, len);
+}
+
+
+QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
+                                 QCryptoBlockReadFunc readfunc,
+                                 void *opaque,
+                                 unsigned int flags,
+                                 Error **errp)
+{
+    QCryptoBlock *block = g_new0(QCryptoBlock, 1);
+
+    block->format = options->format;
+
+    if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
+        !qcrypto_block_drivers[options->format]) {
+        error_setg(errp, "Unsupported block driver %d", options->format);
+        g_free(block);
+        return NULL;
+    }
+
+    block->driver = qcrypto_block_drivers[options->format];
+
+    if (block->driver->open(block, options,
+                            readfunc, opaque, flags, errp) < 0) {
+        g_free(block);
+        return NULL;
+    }
+
+    return block;
+}
+
+
+QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
+                                   QCryptoBlockInitFunc initfunc,
+                                   QCryptoBlockWriteFunc writefunc,
+                                   void *opaque,
+                                   Error **errp)
+{
+    QCryptoBlock *block = g_new0(QCryptoBlock, 1);
+
+    block->format = options->format;
+
+    if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
+        !qcrypto_block_drivers[options->format]) {
+        error_setg(errp, "Unsupported block driver %d", options->format);
+        g_free(block);
+        return NULL;
+    }
+
+    block->driver = qcrypto_block_drivers[options->format];
+
+    if (block->driver->create(block, options, initfunc,
+                              writefunc, opaque, errp) < 0) {
+        g_free(block);
+        return NULL;
+    }
+
+    return block;
+}
+
+
+int qcrypto_block_decrypt(QCryptoBlock *block,
+                          uint64_t startsector,
+                          uint8_t *buf,
+                          size_t len,
+                          Error **errp)
+{
+    return block->driver->decrypt(block, startsector, buf, len, errp);
+}
+
+
+int qcrypto_block_encrypt(QCryptoBlock *block,
+                          uint64_t startsector,
+                          uint8_t *buf,
+                          size_t len,
+                          Error **errp)
+{
+    return block->driver->encrypt(block, startsector, buf, len, errp);
+}
+
+
+QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block)
+{
+    return block->cipher;
+}
+
+
+QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block)
+{
+    return block->ivgen;
+}
+
+
+QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block)
+{
+    return block->kdfhash;
+}
+
+
+uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block)
+{
+    return block->payload_offset;
+}
+
+
+void qcrypto_block_free(QCryptoBlock *block)
+{
+    if (!block) {
+        return;
+    }
+
+    block->driver->cleanup(block);
+
+    qcrypto_cipher_free(block->cipher);
+    qcrypto_ivgen_free(block->ivgen);
+    g_free(block);
+}
+
+
+int qcrypto_block_decrypt_helper(QCryptoCipher *cipher,
+                                 size_t niv,
+                                 QCryptoIVGen *ivgen,
+                                 int sectorsize,
+                                 uint64_t startsector,
+                                 uint8_t *buf,
+                                 size_t len,
+                                 Error **errp)
+{
+    uint8_t *iv;
+    int ret = -1;
+
+    iv = niv ? g_new0(uint8_t, niv) : NULL;
+
+    while (len > 0) {
+        size_t nbytes;
+        if (niv) {
+            if (qcrypto_ivgen_calculate(ivgen,
+                                        startsector,
+                                        iv, niv,
+                                        errp) < 0) {
+                goto cleanup;
+            }
+
+            if (qcrypto_cipher_setiv(cipher,
+                                     iv, niv,
+                                     errp) < 0) {
+                goto cleanup;
+            }
+        }
+
+        nbytes = len > sectorsize ? sectorsize : len;
+        if (qcrypto_cipher_decrypt(cipher, buf, buf,
+                                   nbytes, errp) < 0) {
+            goto cleanup;
+        }
+
+        startsector++;
+        buf += nbytes;
+        len -= nbytes;
+    }
+
+    ret = 0;
+ cleanup:
+    g_free(iv);
+    return ret;
+}
+
+
+int qcrypto_block_encrypt_helper(QCryptoCipher *cipher,
+                                 size_t niv,
+                                 QCryptoIVGen *ivgen,
+                                 int sectorsize,
+                                 uint64_t startsector,
+                                 uint8_t *buf,
+                                 size_t len,
+                                 Error **errp)
+{
+    uint8_t *iv;
+    int ret = -1;
+
+    iv = niv ? g_new0(uint8_t, niv) : NULL;
+
+    while (len > 0) {
+        size_t nbytes;
+        if (niv) {
+            if (qcrypto_ivgen_calculate(ivgen,
+                                        startsector,
+                                        iv, niv,
+                                        errp) < 0) {
+                goto cleanup;
+            }
+
+            if (qcrypto_cipher_setiv(cipher,
+                                     iv, niv,
+                                     errp) < 0) {
+                goto cleanup;
+            }
+        }
+
+        nbytes = len > sectorsize ? sectorsize : len;
+        if (qcrypto_cipher_encrypt(cipher, buf, buf,
+                                   nbytes, errp) < 0) {
+            goto cleanup;
+        }
+
+        startsector++;
+        buf += nbytes;
+        len -= nbytes;
+    }
+
+    ret = 0;
+ cleanup:
+    g_free(iv);
+    return ret;
+}
diff --git a/crypto/blockpriv.h b/crypto/blockpriv.h
new file mode 100644
index 0000000..6297085
--- /dev/null
+++ b/crypto/blockpriv.h
@@ -0,0 +1,92 @@
+/*
+ * QEMU Crypto block device encryption
+ *
+ * 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/>.
+ *
+ */
+
+#ifndef QCRYPTO_BLOCK_PRIV_H__
+#define QCRYPTO_BLOCK_PRIV_H__
+
+#include "crypto/block.h"
+
+typedef struct QCryptoBlockDriver QCryptoBlockDriver;
+
+struct QCryptoBlock {
+    QCryptoBlockFormat format;
+
+    const QCryptoBlockDriver *driver;
+    void *opaque;
+
+    QCryptoCipher *cipher;
+    QCryptoIVGen *ivgen;
+    QCryptoHashAlgorithm kdfhash;
+    size_t niv;
+    uint64_t payload_offset; /* In bytes */
+};
+
+struct QCryptoBlockDriver {
+    int (*open)(QCryptoBlock *block,
+                QCryptoBlockOpenOptions *options,
+                QCryptoBlockReadFunc readfunc,
+                void *opaque,
+                unsigned int flags,
+                Error **errp);
+
+    int (*create)(QCryptoBlock *block,
+                  QCryptoBlockCreateOptions *options,
+                  QCryptoBlockInitFunc initfunc,
+                  QCryptoBlockWriteFunc writefunc,
+                  void *opaque,
+                  Error **errp);
+
+    void (*cleanup)(QCryptoBlock *block);
+
+    int (*encrypt)(QCryptoBlock *block,
+                   uint64_t startsector,
+                   uint8_t *buf,
+                   size_t len,
+                   Error **errp);
+    int (*decrypt)(QCryptoBlock *block,
+                   uint64_t startsector,
+                   uint8_t *buf,
+                   size_t len,
+                   Error **errp);
+
+    bool (*has_format)(const uint8_t *buf,
+                       size_t buflen);
+};
+
+
+int qcrypto_block_decrypt_helper(QCryptoCipher *cipher,
+                                 size_t niv,
+                                 QCryptoIVGen *ivgen,
+                                 int sectorsize,
+                                 uint64_t startsector,
+                                 uint8_t *buf,
+                                 size_t len,
+                                 Error **errp);
+
+int qcrypto_block_encrypt_helper(QCryptoCipher *cipher,
+                                 size_t niv,
+                                 QCryptoIVGen *ivgen,
+                                 int sectorsize,
+                                 uint64_t startsector,
+                                 uint8_t *buf,
+                                 size_t len,
+                                 Error **errp);
+
+#endif /* QCRYPTO_BLOCK_PRIV_H__ */