[PATCH] block/rbd: Add support for rbd image encryption

[Or Ozeri <oro@il.ibm.com>]

Starting from ceph Pacific, RBD has built-in support for image-level encryption.
Currently supported formats are LUKS version 1 and 2.

There are 2 new relevant librbd APIs for controlling encryption, both expect an
open image context:

rbd_encryption_format: formats an image (i.e. writes the LUKS header)
rbd_encryption_load: loads encryptor/decryptor to the image IO stack

This commit extends the qemu rbd driver API to support the above.

Signed-off-by: Or Ozeri <oro@il.ibm.com>
---
 block/rbd.c          | 380 ++++++++++++++++++++++++++++++++++++++++++-
 qapi/block-core.json | 110 ++++++++++++-
 2 files changed, 484 insertions(+), 6 deletions(-)

diff --git a/block/rbd.c b/block/rbd.c
index f098a89c7b..dadecaf3da 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -73,6 +73,18 @@
 #define LIBRBD_USE_IOVEC 0
 #endif
 
+#define RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN 8
+
+static const char rbd_luks_header_verification[
+        RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN] = {
+    'L', 'U', 'K', 'S', 0xBA, 0xBE, 0, 1
+};
+
+static const char rbd_luks2_header_verification[
+        RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN] = {
+    'L', 'U', 'K', 'S', 0xBA, 0xBE, 0, 2
+};
+
 typedef enum {
     RBD_AIO_READ,
     RBD_AIO_WRITE,
@@ -106,6 +118,7 @@ typedef struct BDRVRBDState {
     char *snap;
     char *namespace;
     uint64_t image_size;
+    ImageInfoSpecificRbd image_info;
 } BDRVRBDState;
 
 static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx,
@@ -341,6 +354,207 @@ static void qemu_rbd_memset(RADOSCB *rcb, int64_t offs)
     }
 }
 
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION
+static int qemu_rbd_convert_luks_options(
+        RbdEncryptionOptionsLUKSBase *luks_opts,
+        char **passphrase,
+        size_t *passphrase_len,
+        Error **errp)
+{
+    return qcrypto_secret_lookup(luks_opts->key_secret, (uint8_t **)passphrase,
+                                 passphrase_len, errp);
+}
+
+static int qemu_rbd_convert_luks_create_options(
+        RbdEncryptionCreateOptionsLUKSBase *luks_opts,
+        rbd_encryption_algorithm_t *alg,
+        char **passphrase,
+        size_t *passphrase_len,
+        Error **errp)
+{
+    int r = 0;
+
+    r = qemu_rbd_convert_luks_options(
+            qapi_RbdEncryptionCreateOptionsLUKSBase_base(luks_opts),
+            passphrase, passphrase_len, errp);
+    if (r < 0) {
+        return r;
+    }
+
+    if (luks_opts->has_cipher_alg) {
+        switch (luks_opts->cipher_alg) {
+            case QCRYPTO_CIPHER_ALG_AES_128: {
+                *alg = RBD_ENCRYPTION_ALGORITHM_AES128;
+                break;
+            }
+            case QCRYPTO_CIPHER_ALG_AES_256: {
+                *alg = RBD_ENCRYPTION_ALGORITHM_AES256;
+                break;
+            }
+            default: {
+                r = -ENOTSUP;
+                error_setg_errno(errp, -r, "unknown encryption algorithm: %u",
+                                 luks_opts->cipher_alg);
+                return r;
+            }
+        }
+    } else {
+        /* default alg */
+        *alg = RBD_ENCRYPTION_ALGORITHM_AES256;
+    }
+
+    return 0;
+}
+
+static int qemu_rbd_encryption_format(rbd_image_t image,
+                                      RbdEncryptionCreateOptions *encrypt,
+                                      Error **errp)
+{
+    int r = 0;
+    g_autofree char *passphrase = NULL;
+    size_t passphrase_len;
+    rbd_encryption_format_t format;
+    rbd_encryption_options_t opts;
+    rbd_encryption_luks1_format_options_t luks_opts;
+    rbd_encryption_luks2_format_options_t luks2_opts;
+    size_t opts_size;
+    uint64_t raw_size, effective_size;
+
+    r = rbd_get_size(image, &raw_size);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "cannot get raw image size");
+        return r;
+    }
+
+    switch (encrypt->format) {
+        case RBD_IMAGE_ENCRYPTION_FORMAT_LUKS: {
+            memset(&luks_opts, 0, sizeof(luks_opts));
+            format = RBD_ENCRYPTION_FORMAT_LUKS1;
+            opts = &luks_opts;
+            opts_size = sizeof(luks_opts);
+            r = qemu_rbd_convert_luks_create_options(
+                    qapi_RbdEncryptionCreateOptionsLUKS_base(&encrypt->u.luks),
+                    &luks_opts.alg, &passphrase, &passphrase_len, errp);
+            if (r < 0) {
+                return r;
+            }
+            luks_opts.passphrase = passphrase;
+            luks_opts.passphrase_size = passphrase_len;
+            break;
+        }
+        case RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2: {
+            memset(&luks2_opts, 0, sizeof(luks2_opts));
+            format = RBD_ENCRYPTION_FORMAT_LUKS2;
+            opts = &luks2_opts;
+            opts_size = sizeof(luks2_opts);
+            r = qemu_rbd_convert_luks_create_options(
+                    qapi_RbdEncryptionCreateOptionsLUKS2_base(
+                            &encrypt->u.luks2),
+                    &luks2_opts.alg, &passphrase, &passphrase_len, errp);
+            if (r < 0) {
+                return r;
+            }
+            luks2_opts.passphrase = passphrase;
+            luks2_opts.passphrase_size = passphrase_len;
+            break;
+        }
+        default: {
+            r = -ENOTSUP;
+            error_setg_errno(
+                    errp, -r, "unknown image encryption format: %u",
+                    encrypt->format);
+            return r;
+        }
+    }
+
+    r = rbd_encryption_format(image, format, opts, opts_size);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "encryption format fail");
+        return r;
+    }
+
+    r = rbd_get_size(image, &effective_size);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "cannot get effective image size");
+        return r;
+    }
+
+    r = rbd_resize(image, raw_size + (raw_size - effective_size));
+    if (r < 0) {
+        error_setg_errno(errp, -r, "cannot resize image after format");
+        return r;
+    }
+
+    return 0;
+}
+
+static int qemu_rbd_encryption_load(rbd_image_t image,
+                                    RbdEncryptionOptions *encrypt,
+                                    ImageInfoSpecificRbd *image_info,
+                                    Error **errp)
+{
+    int r = 0;
+    g_autofree char *passphrase = NULL;
+    size_t passphrase_len;
+    rbd_encryption_luks1_format_options_t luks_opts;
+    rbd_encryption_luks2_format_options_t luks2_opts;
+    rbd_encryption_format_t format;
+    rbd_encryption_options_t opts;
+    size_t opts_size;
+
+    switch (encrypt->format) {
+        case RBD_IMAGE_ENCRYPTION_FORMAT_LUKS: {
+            memset(&luks_opts, 0, sizeof(luks_opts));
+            format = RBD_ENCRYPTION_FORMAT_LUKS1;
+            opts = &luks_opts;
+            opts_size = sizeof(luks_opts);
+            r = qemu_rbd_convert_luks_options(
+                    qapi_RbdEncryptionOptionsLUKS_base(&encrypt->u.luks),
+                    &passphrase, &passphrase_len, errp);
+            if (r < 0) {
+                return r;
+            }
+            luks_opts.passphrase = passphrase;
+            luks_opts.passphrase_size = passphrase_len;
+            image_info->encryption_format = RBD_IMAGE_ENCRYPTION_FORMAT_LUKS;
+            break;
+        }
+        case RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2: {
+            memset(&luks2_opts, 0, sizeof(luks2_opts));
+            format = RBD_ENCRYPTION_FORMAT_LUKS2;
+            opts = &luks2_opts;
+            opts_size = sizeof(luks2_opts);
+            r = qemu_rbd_convert_luks_options(
+                    qapi_RbdEncryptionOptionsLUKS2_base(&encrypt->u.luks2),
+                    &passphrase, &passphrase_len, errp);
+            if (r < 0) {
+                return r;
+            }
+            luks2_opts.passphrase = passphrase;
+            luks2_opts.passphrase_size = passphrase_len;
+            image_info->encryption_format = RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2;
+            break;
+        }
+        default: {
+            r = -ENOTSUP;
+            error_setg_errno(
+                    errp, -r, "unknown image encryption format: %u",
+                    encrypt->format);
+            return r;
+        }
+    }
+
+    r = rbd_encryption_load(image, format, opts, opts_size);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "encryption load fail");
+        return r;
+    }
+
+    image_info->has_encryption_format = true;
+    return 0;
+}
+#endif
+
 /* FIXME Deprecate and remove keypairs or make it available in QMP. */
 static int qemu_rbd_do_create(BlockdevCreateOptions *options,
                               const char *keypairs, const char *password_secret,
@@ -358,6 +572,13 @@ static int qemu_rbd_do_create(BlockdevCreateOptions *options,
         return -EINVAL;
     }
 
+#ifndef LIBRBD_SUPPORTS_ENCRYPTION
+    if (opts->has_encrypt) {
+        error_setg(errp, "RBD library does not support image encryption");
+        return -ENOTSUP;
+    }
+#endif
+
     if (opts->has_cluster_size) {
         int64_t objsize = opts->cluster_size;
         if ((objsize - 1) & objsize) {    /* not a power of 2? */
@@ -383,6 +604,28 @@ static int qemu_rbd_do_create(BlockdevCreateOptions *options,
         goto out;
     }
 
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION
+    if (opts->has_encrypt) {
+        rbd_image_t image;
+
+        ret = rbd_open(io_ctx, opts->location->image, &image, NULL);
+        if (ret < 0) {
+            error_setg_errno(errp, -ret,
+                             "error opening image '%s' for encryption format",
+                             opts->location->image);
+            goto out;
+        }
+
+        ret = qemu_rbd_encryption_format(image, opts->encrypt, errp);
+        rbd_close(image);
+        if (ret < 0) {
+            /* encryption format fail, try removing the image */
+            rbd_remove(io_ctx, opts->location->image);
+            goto out;
+        }
+    }
+#endif
+
     ret = 0;
 out:
     rados_ioctx_destroy(io_ctx);
@@ -395,6 +638,43 @@ static int qemu_rbd_co_create(BlockdevCreateOptions *options, Error **errp)
     return qemu_rbd_do_create(options, NULL, NULL, errp);
 }
 
+static int qemu_rbd_extract_encryption_create_options(
+        QemuOpts *opts,
+        RbdEncryptionCreateOptions **spec,
+        Error **errp)
+{
+    QDict *opts_qdict;
+    QDict *encrypt_qdict;
+    Visitor *v;
+    int ret = 0;
+
+    opts_qdict = qemu_opts_to_qdict(opts, NULL);
+    qdict_extract_subqdict(opts_qdict, &encrypt_qdict, "encrypt.");
+    qobject_unref(opts_qdict);
+    if (!qdict_size(encrypt_qdict)) {
+        *spec = NULL;
+        goto exit;
+    }
+
+    /* Convert options into a QAPI object */
+    v = qobject_input_visitor_new_flat_confused(encrypt_qdict, errp);
+    if (!v) {
+        ret = -EINVAL;
+        goto exit;
+    }
+
+    visit_type_RbdEncryptionCreateOptions(v, NULL, spec, errp);
+    visit_free(v);
+    if (!*spec) {
+        ret = -EINVAL;
+        goto exit;
+    }
+
+exit:
+    qobject_unref(encrypt_qdict);
+    return ret;
+}
+
 static int coroutine_fn qemu_rbd_co_create_opts(BlockDriver *drv,
                                                 const char *filename,
                                                 QemuOpts *opts,
@@ -403,6 +683,7 @@ static int coroutine_fn qemu_rbd_co_create_opts(BlockDriver *drv,
     BlockdevCreateOptions *create_options;
     BlockdevCreateOptionsRbd *rbd_opts;
     BlockdevOptionsRbd *loc;
+    RbdEncryptionCreateOptions *encrypt = NULL;
     Error *local_err = NULL;
     const char *keypairs, *password_secret;
     QDict *options = NULL;
@@ -431,6 +712,13 @@ static int coroutine_fn qemu_rbd_co_create_opts(BlockDriver *drv,
         goto exit;
     }
 
+    ret = qemu_rbd_extract_encryption_create_options(opts, &encrypt, errp);
+    if (ret < 0) {
+        goto exit;
+    }
+    rbd_opts->encrypt     = encrypt;
+    rbd_opts->has_encrypt = !!encrypt;
+
     /*
      * Caution: while qdict_get_try_str() is fine, getting non-string
      * types would require more care.  When @options come from -blockdev
@@ -756,12 +1044,26 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
         goto failed_open;
     }
 
+    s->image_info.has_encryption_format = false;
+    if (opts->has_encrypt) {
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION
+        r = qemu_rbd_encryption_load(s->image, opts->encrypt, &s->image_info,
+                                     errp);
+        if (r < 0) {
+            goto failed_post_open;
+        }
+#else
+        r = -ENOTSUP;
+        error_setg(errp, "RBD library does not support image encryption");
+        goto failed_post_open;
+#endif
+    }
+
     r = rbd_get_size(s->image, &s->image_size);
     if (r < 0) {
         error_setg_errno(errp, -r, "error getting image size from %s",
                          s->image_name);
-        rbd_close(s->image);
-        goto failed_open;
+        goto failed_post_open;
     }
 
     /* If we are using an rbd snapshot, we must be r/o, otherwise
@@ -769,8 +1071,7 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
     if (s->snap != NULL) {
         r = bdrv_apply_auto_read_only(bs, "rbd snapshots are read-only", errp);
         if (r < 0) {
-            rbd_close(s->image);
-            goto failed_open;
+            goto failed_post_open;
         }
     }
 
@@ -780,6 +1081,8 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
     r = 0;
     goto out;
 
+failed_post_open:
+    rbd_close(s->image);
 failed_open:
     rados_ioctx_destroy(s->io_ctx);
     g_free(s->snap);
@@ -1050,6 +1353,58 @@ static int qemu_rbd_getinfo(BlockDriverState *bs, BlockDriverInfo *bdi)
     return 0;
 }
 
+static ImageInfoSpecific *qemu_rbd_get_specific_info(BlockDriverState *bs,
+                                                     Error **errp)
+{
+    BDRVRBDState *s = bs->opaque;
+    ImageInfoSpecific *spec_info;
+    char buf[RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN] = {0};
+    int r;
+
+    if (s->image_info.has_encryption_format) {
+        spec_info = g_new(ImageInfoSpecific, 1);
+        *spec_info = (ImageInfoSpecific){
+            .type  = IMAGE_INFO_SPECIFIC_KIND_RBD,
+            .u.rbd.data = g_new0(ImageInfoSpecificRbd, 1),
+        };
+        spec_info->u.rbd.data->has_encryption_format = true;
+        spec_info->u.rbd.data->encryption_format =
+                s->image_info.encryption_format;
+        return spec_info;
+    }
+
+    if (s->image_size >= RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN) {
+        r = rbd_read(s->image, 0,
+                     RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN, buf);
+        if (r < 0) {
+            error_setg_errno(errp, -r, "cannot read image start for probe");
+            return NULL;
+        }
+    }
+
+    spec_info = g_new(ImageInfoSpecific, 1);
+    *spec_info = (ImageInfoSpecific){
+        .type  = IMAGE_INFO_SPECIFIC_KIND_RBD,
+        .u.rbd.data = g_new0(ImageInfoSpecificRbd, 1),
+    };
+
+    if (memcmp(buf, rbd_luks_header_verification,
+               RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN) == 0) {
+        spec_info->u.rbd.data->encryption_format =
+                RBD_IMAGE_ENCRYPTION_FORMAT_LUKS;
+        spec_info->u.rbd.data->has_encryption_format = true;
+    } else if (memcmp(buf, rbd_luks2_header_verification,
+               RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN) == 0) {
+        spec_info->u.rbd.data->encryption_format =
+                RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2;
+        spec_info->u.rbd.data->has_encryption_format = true;
+    } else {
+        spec_info->u.rbd.data->has_encryption_format = false;
+    }
+
+    return spec_info;
+}
+
 static int64_t qemu_rbd_getlength(BlockDriverState *bs)
 {
     BDRVRBDState *s = bs->opaque;
@@ -1243,6 +1598,22 @@ static QemuOptsList qemu_rbd_create_opts = {
             .type = QEMU_OPT_STRING,
             .help = "ID of secret providing the password",
         },
+        {
+            .name = "encrypt.format",
+            .type = QEMU_OPT_STRING,
+            .help = "Encrypt the image, format choices: 'luks', 'luks2'",
+        },
+        {
+            .name = "encrypt.cipher-alg",
+            .type = QEMU_OPT_STRING,
+            .help = "Name of encryption cipher algorithm"
+                    " (allowed values: aes-128, aes-256)",
+        },
+        {
+            .name = "encrypt.key-secret",
+            .type = QEMU_OPT_STRING,
+            .help = "ID of secret providing LUKS passphrase",
+        },
         { /* end of list */ }
     }
 };
@@ -1272,6 +1643,7 @@ static BlockDriver bdrv_rbd = {
     .bdrv_co_create_opts    = qemu_rbd_co_create_opts,
     .bdrv_has_zero_init     = bdrv_has_zero_init_1,
     .bdrv_get_info          = qemu_rbd_getinfo,
+    .bdrv_get_specific_info = qemu_rbd_get_specific_info,
     .create_opts            = &qemu_rbd_create_opts,
     .bdrv_getlength         = qemu_rbd_getlength,
     .bdrv_co_truncate       = qemu_rbd_co_truncate,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 6d227924d0..6cf67d796e 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -127,6 +127,18 @@
       'extents': ['ImageInfo']
   } }
 
+##
+# @ImageInfoSpecificRbd:
+#
+# @encryption-format: Image encryption format
+#
+# Since: 6.1
+##
+{ 'struct': 'ImageInfoSpecificRbd',
+  'data': {
+      '*encryption-format': 'RbdImageEncryptionFormat'
+  } }
+
 ##
 # @ImageInfoSpecific:
 #
@@ -141,7 +153,8 @@
       # If we need to add block driver specific parameters for
       # LUKS in future, then we'll subclass QCryptoBlockInfoLUKS
       # to define a ImageInfoSpecificLUKS
-      'luks': 'QCryptoBlockInfoLUKS'
+      'luks': 'QCryptoBlockInfoLUKS',
+      'rbd': 'ImageInfoSpecificRbd'
   } }
 
 ##
@@ -3609,6 +3622,94 @@
 { 'enum': 'RbdAuthMode',
   'data': [ 'cephx', 'none' ] }
 
+##
+# @RbdImageEncryptionFormat:
+#
+# Since: 6.1
+##
+{ 'enum': 'RbdImageEncryptionFormat',
+  'data': [ 'luks', 'luks2' ] }
+
+##
+# @RbdEncryptionOptionsLUKSBase:
+#
+# @key-secret: ID of a QCryptoSecret object providing a passphrase
+#              for unlocking the encryption
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionOptionsLUKSBase',
+  'data': { 'key-secret': 'str' } }
+
+##
+# @RbdEncryptionCreateOptionsLUKSBase:
+#
+# @cipher-alg: The encryption algorithm
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionCreateOptionsLUKSBase',
+  'base': 'RbdEncryptionOptionsLUKSBase',
+  'data': { '*cipher-alg': 'QCryptoCipherAlgorithm' } }
+
+##
+# @RbdEncryptionOptionsLUKS:
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionOptionsLUKS',
+  'base': 'RbdEncryptionOptionsLUKSBase',
+  'data': { } }
+
+##
+# @RbdEncryptionOptionsLUKS2:
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionOptionsLUKS2',
+  'base': 'RbdEncryptionOptionsLUKSBase',
+  'data': { } }
+
+##
+# @RbdEncryptionCreateOptionsLUKS:
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionCreateOptionsLUKS',
+  'base': 'RbdEncryptionCreateOptionsLUKSBase',
+  'data': { } }
+
+##
+# @RbdEncryptionCreateOptionsLUKS2:
+#
+# Since: 6.1
+##
+{ 'struct': 'RbdEncryptionCreateOptionsLUKS2',
+  'base': 'RbdEncryptionCreateOptionsLUKSBase',
+  'data': { } }
+
+##
+# @RbdEncryptionOptions:
+#
+# Since: 6.1
+##
+{ 'union': 'RbdEncryptionOptions',
+  'base': { 'format': 'RbdImageEncryptionFormat' },
+  'discriminator': 'format',
+  'data': { 'luks': 'RbdEncryptionOptionsLUKS',
+            'luks2': 'RbdEncryptionOptionsLUKS2' } }
+
+##
+# @RbdEncryptionCreateOptions:
+#
+# Since: 6.1
+##
+{ 'union': 'RbdEncryptionCreateOptions',
+  'base': { 'format': 'RbdImageEncryptionFormat' },
+  'discriminator': 'format',
+  'data': { 'luks': 'RbdEncryptionCreateOptionsLUKS',
+            'luks2': 'RbdEncryptionCreateOptionsLUKS2' } }
+
 ##
 # @BlockdevOptionsRbd:
 #
@@ -3624,6 +3725,8 @@
 #
 # @snapshot: Ceph snapshot name.
 #
+# @encrypt: Image encryption options. (Since 6.1)
+#
 # @user: Ceph id name.
 #
 # @auth-client-required: Acceptable authentication modes.
@@ -3646,6 +3749,7 @@
             'image': 'str',
             '*conf': 'str',
             '*snapshot': 'str',
+            '*encrypt': 'RbdEncryptionOptions',
             '*user': 'str',
             '*auth-client-required': ['RbdAuthMode'],
             '*key-secret': 'str',
@@ -4418,13 +4522,15 @@
 #            point to a snapshot.
 # @size: Size of the virtual disk in bytes
 # @cluster-size: RBD object size
+# @encrypt: Image encryption options. (Since 6.1)
 #
 # Since: 2.12
 ##
 { 'struct': 'BlockdevCreateOptionsRbd',
   'data': { 'location':         'BlockdevOptionsRbd',
             'size':             'size',
-            '*cluster-size' :   'size' } }
+            '*cluster-size' :   'size',
+            '*encrypt' :        'RbdEncryptionCreateOptions' } }
 
 ##
 # @BlockdevVmdkSubformat:
-- 
2.27.0