[PATCH v1] block/rbd: Add support for layered encryption

[Or Ozeri]

Starting from ceph Reef, RBD has built-in support for layered encryption,
where each ancestor image (in a cloned image setting) can be possibly
encrypted using a unique passphrase.

A new function, rbd_encryption_load2, was added to librbd API.
This new function supports an array of passphrases (via "spec" structs).

This commit extends the qemu rbd driver API to use this new librbd API,
in order to support this new layered encryption feature.

Signed-off-by: Or Ozeri <oro@il.ibm.com>
---
 block/rbd.c          | 134 ++++++++++++++++++++++++++++++++++++++++++-
 qapi/block-core.json |  33 ++++++++++-
 2 files changed, 163 insertions(+), 4 deletions(-)

diff --git a/block/rbd.c b/block/rbd.c
index f826410f40..09953687c9 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -71,6 +71,16 @@ static const char rbd_luks2_header_verification[
     'L', 'U', 'K', 'S', 0xBA, 0xBE, 0, 2
 };
 
+static const char rbd_layered_luks_header_verification[
+        RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN] = {
+    'R', 'B', 'D', 'L', 0xBA, 0xBE, 0, 1
+};
+
+static const char rbd_layered_luks2_header_verification[
+        RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN] = {
+    'R', 'B', 'D', 'L', 0xBA, 0xBE, 0, 2
+};
+
 typedef enum {
     RBD_AIO_READ,
     RBD_AIO_WRITE,
@@ -470,6 +480,9 @@ static int qemu_rbd_encryption_load(rbd_image_t image,
     size_t passphrase_len;
     rbd_encryption_luks1_format_options_t luks_opts;
     rbd_encryption_luks2_format_options_t luks2_opts;
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION_LOAD2
+    rbd_encryption_luks_format_options_t luks_all_opts;
+#endif
     rbd_encryption_format_t format;
     rbd_encryption_options_t opts;
     size_t opts_size;
@@ -505,6 +518,23 @@ static int qemu_rbd_encryption_load(rbd_image_t image,
             luks2_opts.passphrase_size = passphrase_len;
             break;
         }
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION_LOAD2
+        case RBD_IMAGE_ENCRYPTION_FORMAT_LUKS_ALL: {
+            memset(&luks_all_opts, 0, sizeof(luks_all_opts));
+            format = RBD_ENCRYPTION_FORMAT_LUKS;
+            opts = &luks_all_opts;
+            opts_size = sizeof(luks_all_opts);
+            r = qemu_rbd_convert_luks_options(
+                    
qapi_RbdEncryptionOptionsLUKSAll_base(&encrypt->u.luks_all),
+                    &passphrase, &passphrase_len, errp);
+            if (r < 0) {
+                return r;
+            }
+            luks_all_opts.passphrase = passphrase;
+            luks_all_opts.passphrase_size = passphrase_len;
+            break;
+        }
+#endif
         default: {
             r = -ENOTSUP;
             error_setg_errno(
@@ -522,6 +552,87 @@ static int qemu_rbd_encryption_load(rbd_image_t image,
 
     return 0;
 }
+
+#ifdef LIBRBD_SUPPORTS_ENCRYPTION_LOAD2
+static int qemu_rbd_encryption_load2(rbd_image_t image,
+                                     RbdEncryptionOptions *encrypt,
+                                     Error **errp)
+{
+    int r = 0;
+    int encryption_options_count = 1;
+    int spec_count = 0;
+    int passphrase_count = 0;
+    int i;
+    RbdEncryptionOptions *curr_encrypt;
+    rbd_encryption_spec_t *specs;
+    rbd_encryption_spec_t *curr_spec;
+    rbd_encryption_luks_format_options_t* luks_all_opts;
+    char **passphrases;
+    char **curr_passphrase;
+
+    /* count encryption options */
+    for (curr_encrypt = encrypt; curr_encrypt->has_parent;
+         curr_encrypt = curr_encrypt->parent, ++encryption_options_count) {
+    }
+
+    specs = g_new0(rbd_encryption_spec_t, encryption_options_count);
+    passphrases = g_new0(char*, encryption_options_count);
+
+    curr_encrypt = encrypt;
+    for (i = 0; i < encryption_options_count; ++i) {
+        if (curr_encrypt->format != RBD_IMAGE_ENCRYPTION_FORMAT_LUKS_ALL) {
+            r = -ENOTSUP;
+            error_setg_errno(
+                    errp, -r, "unknown image encryption format: %u",
+                    curr_encrypt->format);
+            goto exit;
+        }
+
+        curr_spec = &specs[i];
+        curr_passphrase = &passphrases[i];
+        curr_spec->format = RBD_ENCRYPTION_FORMAT_LUKS;
+        curr_spec->opts_size = sizeof(rbd_encryption_luks_format_options_t);
+
+        luks_all_opts = g_new0(rbd_encryption_luks_format_options_t, 1);
+        curr_spec->opts = luks_all_opts;
+        ++spec_count;
+        memset(luks_all_opts, 0, sizeof(rbd_encryption_luks_format_options_t));
+
+        r = qemu_rbd_convert_luks_options(
+                qapi_RbdEncryptionOptionsLUKSAll_base(
+                        &curr_encrypt->u.luks_all),
+                curr_passphrase, &luks_all_opts->passphrase_size,
+                errp);
+        if (r < 0) {
+            goto exit;
+        }
+
+        ++passphrase_count;
+        luks_all_opts->passphrase = *curr_passphrase;
+
+        curr_encrypt = curr_encrypt->parent;
+    }
+
+    r = rbd_encryption_load2(image, specs, spec_count);
+    if (r < 0) {
+        error_setg_errno(errp, -r, "encryption load (2) fail");
+        goto exit;
+    }
+
+exit:
+    for (i = 0; i < spec_count; ++i) {
+        luks_all_opts = (rbd_encryption_luks_format_options_t*)(specs[i].opts);
+        if (passphrase_count > 0) {
+            g_free(passphrases[i]);
+            --passphrase_count;
+        }
+        g_free(luks_all_opts);
+    }
+    g_free(passphrases);
+    g_free(specs);
+    return r;
+}
+#endif
 #endif
 
 /* FIXME Deprecate and remove keypairs or make it available in QMP. */
@@ -993,7 +1104,18 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict 
*options, int flags,
 
     if (opts->has_encrypt) {
 #ifdef LIBRBD_SUPPORTS_ENCRYPTION
-        r = qemu_rbd_encryption_load(s->image, opts->encrypt, errp);
+        if (opts->encrypt->has_parent) {
+#ifndef LIBRBD_SUPPORTS_ENCRYPTION_LOAD2
+            r = -ENOTSUP;
+            error_setg(errp, "RBD library does not support"
+                             " specifying parent encryption");
+            goto failed_post_open;
+#else
+            r = qemu_rbd_encryption_load2(s->image, opts->encrypt, errp);
+#endif
+        } else {
+            r = qemu_rbd_encryption_load(s->image, opts->encrypt, errp);
+        }
         if (r < 0) {
             goto failed_post_open;
         }
@@ -1284,6 +1406,16 @@ static ImageInfoSpecific 
*qemu_rbd_get_specific_info(BlockDriverState *bs,
         spec_info->u.rbd.data->encryption_format =
                 RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2;
         spec_info->u.rbd.data->has_encryption_format = true;
+    } else if (memcmp(buf, rbd_layered_luks_header_verification,
+               RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN) == 0) {
+        spec_info->u.rbd.data->encryption_format =
+                RBD_IMAGE_ENCRYPTION_FORMAT_LUKS_LAYERED;
+        spec_info->u.rbd.data->has_encryption_format = true;
+    } else if (memcmp(buf, rbd_layered_luks2_header_verification,
+               RBD_ENCRYPTION_LUKS_HEADER_VERIFICATION_LEN) == 0) {
+        spec_info->u.rbd.data->encryption_format =
+                RBD_IMAGE_ENCRYPTION_FORMAT_LUKS2_LAYERED;
+        spec_info->u.rbd.data->has_encryption_format = true;
     } else {
         spec_info->u.rbd.data->has_encryption_format = false;
     }
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 882b266532..81ac58cd8a 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -3753,10 +3753,20 @@
 ##
 # @RbdImageEncryptionFormat:
 #
+# luks
+#
+# luks2
+#
+# luks-all: Used for opening either luks or luks2. (Since 7.2)
+#
+# luks-layered: Layered encryption. Only used for info. (Since 7.2)
+#
+# luks2-layered: Layered encryption. Only used for info. (Since 7.2)
+#
 # Since: 6.1
 ##
 { 'enum': 'RbdImageEncryptionFormat',
-  'data': [ 'luks', 'luks2' ] }
+  'data': [ 'luks', 'luks2', 'luks-all', 'luks-layered', 'luks2-layered' ] }
 
 ##
 # @RbdEncryptionOptionsLUKSBase:
@@ -3798,6 +3808,15 @@
   'base': 'RbdEncryptionOptionsLUKSBase',
   'data': { } }
 
+##
+# @RbdEncryptionOptionsLUKSAll:
+#
+# Since: 7.2
+##
+{ 'struct': 'RbdEncryptionOptionsLUKSAll',
+  'base': 'RbdEncryptionOptionsLUKSBase',
+  'data': { } }
+
 ##
 # @RbdEncryptionCreateOptionsLUKS:
 #
@@ -3819,13 +3838,21 @@
 ##
 # @RbdEncryptionOptions:
 #
+# @format: Encryption format.
+#
+# @parent: Parent image encryption options (for cloned images).
+#          Can be left unspecified if all ancestor images are encrypted
+#          the same way as the child image.  (Since 7.2)
+#
 # Since: 6.1
 ##
 { 'union': 'RbdEncryptionOptions',
-  'base': { 'format': 'RbdImageEncryptionFormat' },
+  'base': { 'format': 'RbdImageEncryptionFormat',
+            '*parent': 'RbdEncryptionOptions' },
   'discriminator': 'format',
   'data': { 'luks': 'RbdEncryptionOptionsLUKS',
-            'luks2': 'RbdEncryptionOptionsLUKS2' } }
+            'luks2': 'RbdEncryptionOptionsLUKS2',
+            'luks-all': 'RbdEncryptionOptionsLUKSAll'} }
 
 ##
 # @RbdEncryptionCreateOptions:
-- 
2.25.1