qcrypto/core: add generic infrastructure for crypto options amendment

This will be used first to implement luks keyslot management.

block_crypto_amend_opts_init will be used to convert
qemu-img cmdline to QCryptoBlockAmendOptions

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-2-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

block/crypto.c

@@ -202,6 +202,23 @@ block_crypto_create_opts_init(QDict *opts, Error **errp)
     return ret;
 }
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp)
+{
+    Visitor *v;
+    QCryptoBlockAmendOptions *ret;
+
+    v = qobject_input_visitor_new_flat_confused(opts, errp);
+    if (!v) {
+        return NULL;
+    }
+
+    visit_type_QCryptoBlockAmendOptions(v, NULL, &ret, errp);
+
+    visit_free(v);
+    return ret;
+}
+
 
 static int block_crypto_open_generic(QCryptoBlockFormat format,
                                      QemuOptsList *opts_spec,

block/crypto.h

@@ -91,6 +91,9 @@
 QCryptoBlockCreateOptions *
 block_crypto_create_opts_init(QDict *opts, Error **errp);
 
+QCryptoBlockAmendOptions *
+block_crypto_amend_opts_init(QDict *opts, Error **errp);
+
 QCryptoBlockOpenOptions *
 block_crypto_open_opts_init(QDict *opts, Error **errp);
 

crypto/block.c

@@ -150,6 +150,35 @@ qcrypto_block_calculate_payload_offset(QCryptoBlockCreateOptions *create_opts,
     return crypto != NULL;
 }
 
+int qcrypto_block_amend_options(QCryptoBlock *block,
+                                QCryptoBlockReadFunc readfunc,
+                                QCryptoBlockWriteFunc writefunc,
+                                void *opaque,
+                                QCryptoBlockAmendOptions *options,
+                                bool force,
+                                Error **errp)
+{
+    if (options->format != block->format) {
+        error_setg(errp,
+                   "Cannot amend encryption format");
+        return -1;
+    }
+
+    if (!block->driver->amend) {
+        error_setg(errp,
+                   "Crypto format %s doesn't support format options amendment",
+                   QCryptoBlockFormat_str(block->format));
+        return -1;
+    }
+
+    return block->driver->amend(block,
+                                readfunc,
+                                writefunc,
+                                opaque,
+                                options,
+                                force,
+                                errp);
+}
 
 QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
                                          Error **errp)

crypto/blockpriv.h

@@ -62,6 +62,14 @@ struct QCryptoBlockDriver {
                   void *opaque,
                   Error **errp);
 
+    int (*amend)(QCryptoBlock *block,
+                 QCryptoBlockReadFunc readfunc,
+                 QCryptoBlockWriteFunc writefunc,
+                 void *opaque,
+                 QCryptoBlockAmendOptions *options,
+                 bool force,
+                 Error **errp);
+
     int (*get_info)(QCryptoBlock *block,
                     QCryptoBlockInfo *info,
                     Error **errp);

include/crypto/block.h

@@ -144,6 +144,28 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
                                    void *opaque,
                                    Error **errp);
 
+/**
+ * qcrypto_block_amend_options:
+ * @block: the block encryption object
+ *
+ * @readfunc: callback for reading data from the volume header
+ * @writefunc: callback for writing data to the volume header
+ * @opaque: data to pass to @readfunc and @writefunc
+ * @options: the new/amended encryption options
+ * @force: hint for the driver to allow unsafe operation
+ * @errp: error pointer
+ *
+ * Changes the crypto options of the encryption format
+ *
+ */
+int qcrypto_block_amend_options(QCryptoBlock *block,
+                                QCryptoBlockReadFunc readfunc,
+                                QCryptoBlockWriteFunc writefunc,
+                                void *opaque,
+                                QCryptoBlockAmendOptions *options,
+                                bool force,
+                                Error **errp);
+
 
 /**
  * qcrypto_block_calculate_payload_offset:

qapi/crypto.json

@@ -309,3 +309,19 @@
   'base': 'QCryptoBlockInfoBase',
   'discriminator': 'format',
   'data': { 'luks': 'QCryptoBlockInfoLUKS' } }
+
+
+
+##
+# @QCryptoBlockAmendOptions:
+#
+# The options that are available for all encryption formats
+# when amending encryption settings
+#
+# Since: 5.1
+##
+{ 'union': 'QCryptoBlockAmendOptions',
+  'base': 'QCryptoBlockOptionsBase',
+  'discriminator': 'format',
+  'data': {
+            } }