crypto: Modify the qcrypto_block_create to support creation flags

Expand the signature of qcrypto_block_create to enable the
formation of LUKS volumes with detachable headers. To accomplish
that, introduce QCryptoBlockCreateFlags to instruct the creation
process to set the payload_offset_sector to 0.

Signed-off-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 21 insertions, 7 deletions

diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index 7e1235c..ab52c9d 100644
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -1315,6 +1315,7 @@ qcrypto_block_luks_create(QCryptoBlock *block,
     const char *hash_alg;
     g_autofree char *cipher_mode_spec = NULL;
     uint64_t iters;
+    uint64_t detached_header_size;
 
     memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
     if (!luks_opts.has_iter_time) {
@@ -1543,19 +1544,32 @@ qcrypto_block_luks_create(QCryptoBlock *block,
         slot->stripes = QCRYPTO_BLOCK_LUKS_STRIPES;
     }
 
-    /* The total size of the LUKS headers is the partition header + key
-     * slot headers, rounded up to the nearest sector, combined with
-     * the size of each master key material region, also rounded up
-     * to the nearest sector */
-    luks->header.payload_offset_sector = header_sectors +
-            QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS * split_key_sectors;
+    if (block->detached_header) {
+        /*
+         * For a detached LUKS header image, set the payload_offset_sector
+         * to 0 to specify the starting point for read/write
+         */
+        luks->header.payload_offset_sector = 0;
+    } else {
+        /*
+         * The total size of the LUKS headers is the partition header + key
+         * slot headers, rounded up to the nearest sector, combined with
+         * the size of each master key material region, also rounded up
+         * to the nearest sector
+         */
+        luks->header.payload_offset_sector = header_sectors +
+                QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS * split_key_sectors;
+    }
 
     block->sector_size = QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
     block->payload_offset = luks->header.payload_offset_sector *
         block->sector_size;
+    detached_header_size =
+        (header_sectors + QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS *
+         split_key_sectors) * block->sector_size;
 
     /* Reserve header space to match payload offset */
-    initfunc(block, block->payload_offset, opaque, &local_err);
+    initfunc(block, detached_header_size, opaque, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto error;