[Qemu-devel] [PATCH v4 0/2] Report format specific info for LUKS block driver

[Qemu-devel] [PATCH v4 0/2] Report format specific info for LUKS block driver

[Daniel P. Berrange]

This is a followup to:

  v1: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg01723.html
  v2: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03642.html
  v3: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03885.html

The 'qemu-img info' tool has ability to print format specific
information, eg with qcow2 it reports two extra items:

  $ qemu-img info ~/VirtualMachines/demo.qcow2
  image: /home/berrange/VirtualMachines/demo.qcow2
  file format: qcow2
  virtual size: 3.0G (3221225472 bytes)
  disk size: 140K
  cluster_size: 65536
  Format specific information:
      compat: 0.10
      refcount bits: 16


This is not currently wired up for the LUKS driver. This patch
series adds that support so that we can report useful data about
the LUKS volume such as the crypto algorithm choices, key slot
usage and other volume metadata.

The first patch extends the crypto API to allow querying of the
format specific metadata

The second patches extends the block API to allow the LUKS driver
to report the format specific metadata.

    $ qemu-img info ~/VirtualMachines/demo.luks
    image: /home/berrange/VirtualMachines/demo.luks
    file format: luks
    virtual size: 98M (102760448 bytes)
    disk size: 100M
    encrypted: yes
    Format specific information:
        ivgen alg: plain64
        hash alg: sha1
        cipher alg: aes-128
        uuid: 6ddee74b-3a22-408c-8909-6789d4fa2594
        cipher mode: xts
        slots:
            [0]:
                active: true
                iters: 572706
                key offset: 4096
                stripes: 4000
            [1]:
                active: false
                key offset: 135168
            [2]:
                active: false
                key offset: 266240
            [3]:
                active: false
                key offset: 397312
            [4]:
                active: false
                key offset: 528384
            [5]:
                active: false
                key offset: 659456
            [6]:
                active: false
                key offset: 790528
            [7]:
                active: false
                key offset: 921600
        payload offset: 2097152
        master key iters: 142375

Technically most of the code changes here are in the crypto
layer, rather than the block layer. I'm fine with both patches
going through the block maintainer tree, or can submit a both
patches myself as, for sake of simplicity of merge.

Changed in v4:

 - Introduce an empty QCryptoBlockInfoQCow struct to keep
   QAPI generator happy (Eric)

Changed in v3:

 - Do full struct copy instead of field-by-field copy (Max)
 - Simplify handling of linked list pointers (Max)
 - Use g_strndup with uuid to guarantee null termination (Max)
 - Misc typos (Max)

Changed in v2:

 - Drop patches related to creating a text output visitor to
   format the ImageInfoSpecific data. This will be continued
   in a separate patch series
 - Fix key offset to be in bytes instead of sectors
 - Drop the duplicated ImageInfoSpecificLUKS type and just
   directly use QCryptoBlockInfoLUKS type in block layer
 - Skip reporting stripes/iters if keyslot is inactive
 - Add missing QAPI schema docs




Daniel P. Berrange (2):
  crypto: add support for querying parameters for block encryption
  block: export LUKS specific data to qemu-img info

 block/crypto.c         | 49 ++++++++++++++++++++++++++++
 crypto/block-luks.c    | 67 ++++++++++++++++++++++++++++++++++++++
 crypto/block.c         | 17 ++++++++++
 crypto/blockpriv.h     |  4 +++
 include/crypto/block.h | 16 ++++++++++
 qapi/block-core.json   |  6 +++-
 qapi/crypto.json       | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 245 insertions(+), 1 deletion(-)

-- 
2.7.4

[Qemu-devel] [PATCH v4 1/2] crypto: add support for querying parameters for block encryption

[Daniel P. Berrange]

When creating new block encryption volumes, we accept a list of
parameters to control the formatting process. It is useful to
be able to query what those parameters were for existing block
devices. Add a qcrypto_block_get_info() method which returns a
QCryptoBlockInfo instance to report this data.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 crypto/block-luks.c    | 67 ++++++++++++++++++++++++++++++++++++++
 crypto/block.c         | 17 ++++++++++
 crypto/blockpriv.h     |  4 +++
 include/crypto/block.h | 16 ++++++++++
 qapi/crypto.json       | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 191 insertions(+)

diff --git a/crypto/block-luks.c b/crypto/block-luks.c
index fcf3b04..aba4455 100644
--- a/crypto/block-luks.c
+++ b/crypto/block-luks.c
@@ -201,6 +201,15 @@ QEMU_BUILD_BUG_ON(sizeof(struct QCryptoBlockLUKSHeader) != 592);
 
 struct QCryptoBlockLUKS {
     QCryptoBlockLUKSHeader header;
+
+    /* Cache parsed versions of what's in header fields,
+     * as we can't rely on QCryptoBlock.cipher being
+     * non-NULL */
+    QCryptoCipherAlgorithm cipher_alg;
+    QCryptoCipherMode cipher_mode;
+    QCryptoIVGenAlgorithm ivgen_alg;
+    QCryptoHashAlgorithm ivgen_hash_alg;
+    QCryptoHashAlgorithm hash_alg;
 };
 
 
@@ -847,6 +856,12 @@ qcrypto_block_luks_open(QCryptoBlock *block,
     block->payload_offset = luks->header.payload_offset *
         QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
 
+    luks->cipher_alg = cipheralg;
+    luks->cipher_mode = ciphermode;
+    luks->ivgen_alg = ivalg;
+    luks->ivgen_hash_alg = ivhash;
+    luks->hash_alg = hash;
+
     g_free(masterkey);
     g_free(password);
 
@@ -1271,6 +1286,12 @@ qcrypto_block_luks_create(QCryptoBlock *block,
         goto error;
     }
 
+    luks->cipher_alg = luks_opts.cipher_alg;
+    luks->cipher_mode = luks_opts.cipher_mode;
+    luks->ivgen_alg = luks_opts.ivgen_alg;
+    luks->ivgen_hash_alg = luks_opts.ivgen_hash_alg;
+    luks->hash_alg = luks_opts.hash_alg;
+
     memset(masterkey, 0, luks->header.key_bytes);
     g_free(masterkey);
     memset(slotkey, 0, luks->header.key_bytes);
@@ -1305,6 +1326,51 @@ qcrypto_block_luks_create(QCryptoBlock *block,
 }
 
 
+static int qcrypto_block_luks_get_info(QCryptoBlock *block,
+                                       QCryptoBlockInfo *info,
+                                       Error **errp)
+{
+    QCryptoBlockLUKS *luks = block->opaque;
+    QCryptoBlockInfoLUKSSlot *slot;
+    QCryptoBlockInfoLUKSSlotList *slots = NULL, **prev = &info->u.luks.slots;
+    size_t i;
+
+    info->u.luks.cipher_alg = luks->cipher_alg;
+    info->u.luks.cipher_mode = luks->cipher_mode;
+    info->u.luks.ivgen_alg = luks->ivgen_alg;
+    if (info->u.luks.ivgen_alg == QCRYPTO_IVGEN_ALG_ESSIV) {
+        info->u.luks.has_ivgen_hash_alg = true;
+        info->u.luks.ivgen_hash_alg = luks->ivgen_hash_alg;
+    }
+    info->u.luks.hash_alg = luks->hash_alg;
+    info->u.luks.payload_offset = block->payload_offset;
+    info->u.luks.master_key_iters = luks->header.master_key_iterations;
+    info->u.luks.uuid = g_strndup((const char *)luks->header.uuid,
+                                  sizeof(luks->header.uuid));
+
+    for (i = 0; i < QCRYPTO_BLOCK_LUKS_NUM_KEY_SLOTS; i++) {
+        slots = g_new0(QCryptoBlockInfoLUKSSlotList, 1);
+        *prev = slots;
+
+        slots->value = slot = g_new0(QCryptoBlockInfoLUKSSlot, 1);
+        slot->active = luks->header.key_slots[i].active ==
+            QCRYPTO_BLOCK_LUKS_KEY_SLOT_ENABLED;
+        slot->key_offset = luks->header.key_slots[i].key_offset
+             * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE;
+        if (slot->active) {
+            slot->has_iters = true;
+            slot->iters = luks->header.key_slots[i].iterations;
+            slot->has_stripes = true;
+            slot->stripes = luks->header.key_slots[i].stripes;
+        }
+
+        prev = &slots->next;
+    }
+
+    return 0;
+}
+
+
 static void qcrypto_block_luks_cleanup(QCryptoBlock *block)
 {
     g_free(block->opaque);
@@ -1342,6 +1408,7 @@ qcrypto_block_luks_encrypt(QCryptoBlock *block,
 const QCryptoBlockDriver qcrypto_block_driver_luks = {
     .open = qcrypto_block_luks_open,
     .create = qcrypto_block_luks_create,
+    .get_info = qcrypto_block_luks_get_info,
     .cleanup = qcrypto_block_luks_cleanup,
     .decrypt = qcrypto_block_luks_decrypt,
     .encrypt = qcrypto_block_luks_encrypt,
diff --git a/crypto/block.c b/crypto/block.c
index da60eba..be823ee 100644
--- a/crypto/block.c
+++ b/crypto/block.c
@@ -105,6 +105,23 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
 }
 
 
+QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
+                                         Error **errp)
+{
+    QCryptoBlockInfo *info = g_new0(QCryptoBlockInfo, 1);
+
+    info->format = block->format;
+
+    if (block->driver->get_info &&
+        block->driver->get_info(block, info, errp) < 0) {
+        g_free(info);
+        return NULL;
+    }
+
+    return info;
+}
+
+
 int qcrypto_block_decrypt(QCryptoBlock *block,
                           uint64_t startsector,
                           uint8_t *buf,
diff --git a/crypto/blockpriv.h b/crypto/blockpriv.h
index 15b547d..68f0f06 100644
--- a/crypto/blockpriv.h
+++ b/crypto/blockpriv.h
@@ -53,6 +53,10 @@ struct QCryptoBlockDriver {
                   void *opaque,
                   Error **errp);
 
+    int (*get_info)(QCryptoBlock *block,
+                    QCryptoBlockInfo *info,
+                    Error **errp);
+
     void (*cleanup)(QCryptoBlock *block);
 
     int (*encrypt)(QCryptoBlock *block,
diff --git a/include/crypto/block.h b/include/crypto/block.h
index 8955211..b6971de 100644
--- a/include/crypto/block.h
+++ b/include/crypto/block.h
@@ -138,6 +138,22 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
                                    void *opaque,
                                    Error **errp);
 
+
+/**
+ * qcrypto_block_get_info:
+ * @block: the block encryption object
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Get information about the configuration options for the
+ * block encryption object. This includes details such as
+ * the cipher algorithms, modes, and initialization vector
+ * generators.
+ *
+ * Returns: a block encryption info object, or NULL on error
+ */
+QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
+                                         Error **errp);
+
 /**
  * @qcrypto_block_decrypt:
  * @block: the block encryption object
diff --git a/qapi/crypto.json b/qapi/crypto.json
index 4c4a3e0..34d2583 100644
--- a/qapi/crypto.json
+++ b/qapi/crypto.json
@@ -224,3 +224,90 @@
   'discriminator': 'format',
   'data': { 'qcow': 'QCryptoBlockOptionsQCow',
             'luks': 'QCryptoBlockCreateOptionsLUKS' } }
+
+
+##
+# QCryptoBlockInfoBase:
+#
+# The common information that applies to all full disk
+# encryption formats
+#
+# @format: the encryption format
+#
+# Since: 2.7
+##
+{ 'struct': 'QCryptoBlockInfoBase',
+  'data': { 'format': 'QCryptoBlockFormat' }}
+
+
+##
+# QCryptoBlockInfoLUKSSlot:
+#
+# Information about the LUKS block encryption key
+# slot options
+#
+# @active: whether the key slot is currently in use
+# @key-offset: offset to the key material in bytes
+# @iters: #optional number of PBKDF2 iterations for key material
+# @stripes: #optional number of stripes for splitting key material
+#
+# Since: 2.7
+##
+{ 'struct': 'QCryptoBlockInfoLUKSSlot',
+  'data': {'active': 'bool',
+           '*iters': 'int',
+           '*stripes': 'int',
+           'key-offset': 'int' } }
+
+
+##
+# QCryptoBlockInfoLUKS:
+#
+# Information about the LUKS block encryption options
+#
+# @cipher-alg: the cipher algorithm for data encryption
+# @cipher-mode: the cipher mode for data encryption
+# @ivgen-alg: the initialization vector generator
+# @ivgen-hash-alg: #optional the initialization vector generator hash
+# @hash-alg: the master key hash algorithm
+# @payload-offset: offset to the payload data in bytes
+# @master-key-iters: number of PBKDF2 iterations for key material
+# @uuid: unique identifier for the volume
+# @slots: information about each key slot
+#
+# Since: 2.7
+##
+{ 'struct': 'QCryptoBlockInfoLUKS',
+  'data': {'cipher-alg': 'QCryptoCipherAlgorithm',
+           'cipher-mode': 'QCryptoCipherMode',
+           'ivgen-alg': 'QCryptoIVGenAlgorithm',
+           '*ivgen-hash-alg': 'QCryptoHashAlgorithm',
+           'hash-alg': 'QCryptoHashAlgorithm',
+           'payload-offset': 'int',
+           'master-key-iters': 'int',
+           'uuid': 'str',
+           'slots': [ 'QCryptoBlockInfoLUKSSlot' ] }}
+
+##
+# QCryptoBlockInfoQCow:
+#
+# Information about the QCow block encryption options
+#
+# Since: 2.7
+##
+{ 'struct': 'QCryptoBlockInfoQCow',
+  'data': { }}
+
+
+##
+# QCryptoBlockInfo:
+#
+# Information about the block encryption options
+#
+# Since: 2.7
+##
+{ 'union': 'QCryptoBlockInfo',
+  'base': 'QCryptoBlockInfoBase',
+  'discriminator': 'format',
+  'data': { 'qcow': 'QCryptoBlockInfoQCow',
+            'luks': 'QCryptoBlockInfoLUKS' } }
-- 
2.7.4

[Qemu-devel] [PATCH v4 2/2] block: export LUKS specific data to qemu-img info

[Daniel P. Berrange]

The qemu-img info command has the ability to expose format
specific metadata about volumes. Wire up this facility for
the LUKS driver to report on cipher configuration and key
slot usage.

    $ qemu-img info ~/VirtualMachines/demo.luks
    image: /home/berrange/VirtualMachines/demo.luks
    file format: luks
    virtual size: 98M (102760448 bytes)
    disk size: 100M
    encrypted: yes
    Format specific information:
        ivgen alg: plain64
        hash alg: sha1
        cipher alg: aes-128
        uuid: 6ddee74b-3a22-408c-8909-6789d4fa2594
        cipher mode: xts
        slots:
            [0]:
                active: true
                iters: 572706
                key offset: 4096
                stripes: 4000
            [1]:
                active: false
                key offset: 135168
            [2]:
                active: false
                key offset: 266240
            [3]:
                active: false
                key offset: 397312
            [4]:
                active: false
                key offset: 528384
            [5]:
                active: false
                key offset: 659456
            [6]:
                active: false
                key offset: 790528
            [7]:
                active: false
                key offset: 921600
        payload offset: 2097152
        master key iters: 142375

One somewhat undesirable artifact is that the data fields are
printed out in (apparently) random order. This will be addressed
later by changing the way the block layer pretty-prints the
image specific data.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 block/crypto.c       | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 qapi/block-core.json |  6 +++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/block/crypto.c b/block/crypto.c
index 7eaa057..7f61e12 100644
--- a/block/crypto.c
+++ b/block/crypto.c
@@ -563,6 +563,53 @@ static int block_crypto_create_luks(const char *filename,
                                        filename, opts, errp);
 }
 
+static int block_crypto_get_info_luks(BlockDriverState *bs,
+                                      BlockDriverInfo *bdi)
+{
+    BlockDriverInfo subbdi;
+    int ret;
+
+    ret = bdrv_get_info(bs->file->bs, &subbdi);
+    if (ret != 0) {
+        return ret;
+    }
+
+    bdi->unallocated_blocks_are_zero = false;
+    bdi->can_write_zeroes_with_unmap = false;
+    bdi->cluster_size = subbdi.cluster_size;
+
+    return 0;
+}
+
+static ImageInfoSpecific *
+block_crypto_get_specific_info_luks(BlockDriverState *bs)
+{
+    BlockCrypto *crypto = bs->opaque;
+    ImageInfoSpecific *spec_info;
+    QCryptoBlockInfo *info;
+
+    info = qcrypto_block_get_info(crypto->block, NULL);
+    if (!info) {
+        return NULL;
+    }
+    if (info->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
+        qapi_free_QCryptoBlockInfo(info);
+        return NULL;
+    }
+
+    spec_info = g_new(ImageInfoSpecific, 1);
+    spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
+    spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
+    *spec_info->u.luks.data = info->u.luks;
+
+    /* Blank out pointers we've just stolen to avoid double free */
+    memset(&info->u.luks, 0, sizeof(info->u.luks));
+
+    qapi_free_QCryptoBlockInfo(info);
+
+    return spec_info;
+}
+
 BlockDriver bdrv_crypto_luks = {
     .format_name        = "luks",
     .instance_size      = sizeof(BlockCrypto),
@@ -576,6 +623,8 @@ BlockDriver bdrv_crypto_luks = {
     .bdrv_co_readv      = block_crypto_co_readv,
     .bdrv_co_writev     = block_crypto_co_writev,
     .bdrv_getlength     = block_crypto_getlength,
+    .bdrv_get_info      = block_crypto_get_info_luks,
+    .bdrv_get_specific_info = block_crypto_get_specific_info_luks,
 };
 
 static void block_crypto_init(void)
diff --git a/qapi/block-core.json b/qapi/block-core.json
index f462345..d4bab5d 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -85,7 +85,11 @@
 { 'union': 'ImageInfoSpecific',
   'data': {
       'qcow2': 'ImageInfoSpecificQCow2',
-      'vmdk': 'ImageInfoSpecificVmdk'
+      'vmdk': 'ImageInfoSpecificVmdk',
+      # If we need to add block driver specific parameters for
+      # LUKS in future, then we'll subclass QCryptoBlockInfoLUKS
+      # to define a ImageInfoSpecificLUKS
+      'luks': 'QCryptoBlockInfoLUKS'
   } }
 
 ##
-- 
2.7.4

Re: [Qemu-devel] [PATCH v4 0/2] Report format specific info for LUKS block driver

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1192 bytes --]

On 07/22/2016 06:53 AM, Daniel P. Berrange wrote:
> This is a followup to:
> 
>   v1: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg01723.html
>   v2: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03642.html
>   v3: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03885.html
> 
> The 'qemu-img info' tool has ability to print format specific
> information, eg with qcow2 it reports two extra items:
> 
>   $ qemu-img info ~/VirtualMachines/demo.qcow2
>   image: /home/berrange/VirtualMachines/demo.qcow2
>   file format: qcow2
>   virtual size: 3.0G (3221225472 bytes)
>   disk size: 140K
>   cluster_size: 65536
>   Format specific information:
>       compat: 0.10
>       refcount bits: 16
> 


> 
> Changed in v4:
> 
>  - Introduce an empty QCryptoBlockInfoQCow struct to keep
>    QAPI generator happy (Eric)

> 
> 
> Daniel P. Berrange (2):
>   crypto: add support for querying parameters for block encryption
>   block: export LUKS specific data to qemu-img info

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v4 0/2] Report format specific info for LUKS block driver

[Max Reitz]

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On 22.07.2016 14:53, Daniel P. Berrange wrote:
> This is a followup to:
> 
>   v1: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg01723.html
>   v2: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03642.html
>   v3: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg03885.html

Thanks, applied to my block tree for 2.7 (in the spirit of Kevin's
traditionally rather loose definition of "freeze"):

https://github.com/XanClic/qemu/commits/block

Max


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