Re: [Qemu-block] [PATCH 08/13] qcrypto: add the plumbing for encryption management

[Maxim Levitsky]

On Thu, 2019-08-22 at 12:16 +0100, Daniel P. Berrangé wrote:
> On Wed, Aug 14, 2019 at 11:22:14PM +0300, Maxim Levitsky wrote:
> > This adds qcrypto_block_manage_encryption, which
> >  is thin wrapper around manage_encryption of the crypto driver
> >  which is also added
> > 
> > Signed-off-by: Maxim Levitsky <address@hidden>
> > ---
> >  crypto/block.c         | 29 +++++++++++++++++++++++++++++
> >  crypto/blockpriv.h     |  9 +++++++++
> >  include/crypto/block.h | 27 +++++++++++++++++++++++++++
> >  3 files changed, 65 insertions(+)
> > 
> > diff --git a/crypto/block.c b/crypto/block.c
> > index ee96759f7d..5916e49aba 100644
> > --- a/crypto/block.c
> > +++ b/crypto/block.c
> > @@ -20,6 +20,7 @@
> >  
> >  #include "qemu/osdep.h"
> >  #include "qapi/error.h"
> > +
> >  #include "blockpriv.h"
> >  #include "block-qcow.h"
> >  #include "block-luks.h"
> > @@ -282,6 +283,34 @@ void qcrypto_block_free(QCryptoBlock *block)
> >  }
> >  
> >  
> > +int qcrypto_block_setup_encryption(QCryptoBlock *block,
> > +                                   QCryptoBlockReadFunc readfunc,
> > +                                   QCryptoBlockWriteFunc writefunc,
> > +                                   void *opaque,
> > +                                   enum BlkSetupEncryptionAction action,
> > +                                   QCryptoEncryptionSetupOptions *options,
> > +                                   bool force,
> > +                                   Error **errp)
> > +{
> > +    if (!block->driver->setup_encryption) {
> > +        error_setg(errp,
> > +                "Crypto format %s doesn't support management of encryption 
> > keys",
> > +                QCryptoBlockFormat_str(block->format));
> > +        return -1;
> > +    }
> > +
> > +    return block->driver->setup_encryption(block,
> > +                                           readfunc,
> > +                                           writefunc,
> > +                                           opaque,
> > +                                           action,
> > +                                           options,
> > +                                           force,
> > +                                           errp);
> > +}
> > +
> > +
> > +
> >  typedef int (*QCryptoCipherEncDecFunc)(QCryptoCipher *cipher,
> >                                          const void *in,
> >                                          void *out,
> > diff --git a/crypto/blockpriv.h b/crypto/blockpriv.h
> > index 71c59cb542..804965dca3 100644
> > --- a/crypto/blockpriv.h
> > +++ b/crypto/blockpriv.h
> > @@ -81,6 +81,15 @@ struct QCryptoBlockDriver {
> >  
> >      bool (*has_format)(const uint8_t *buf,
> >                         size_t buflen);
> > +
> > +    int (*setup_encryption)(QCryptoBlock *block,
> > +                            QCryptoBlockReadFunc readfunc,
> > +                            QCryptoBlockWriteFunc writefunc,
> > +                            void *opaque,
> > +                            enum BlkSetupEncryptionAction action,
> > +                            QCryptoEncryptionSetupOptions *options,
> > +                            bool force,
> > +                            Error **errp);
> >  };
> >  
> >  
> > diff --git a/include/crypto/block.h b/include/crypto/block.h
> > index fe12899831..60d46e3efc 100644
> > --- a/include/crypto/block.h
> > +++ b/include/crypto/block.h
> > @@ -23,6 +23,7 @@
> >  
> >  #include "crypto/cipher.h"
> >  #include "crypto/ivgen.h"
> > +#include "block/block.h"
> >  
> >  typedef struct QCryptoBlock QCryptoBlock;
> >  
> > @@ -268,4 +269,30 @@ uint64_t qcrypto_block_get_sector_size(QCryptoBlock 
> > *block);
> >   */
> >  void qcrypto_block_free(QCryptoBlock *block);
> >  
> > +
> > +/**
> > + * qcrypto_block_setup_encryption:
> > + * @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
> > + * @action: tell the driver the setup action (add/erase currently)
> > + * @options: driver specific options, that specify
> > + *           what encryption settings to manage
> > + * @force: hint for the driver to allow unsafe operation
> > + * @errp: error pointer
> > + *
> > + * Adds/Erases a new encryption key using @options
> 
> I'd prefer to see separate APIs for add + erase instead
> of overloading. It'll lead to a clearer API from callers
> POV to see exactly which parameters are for each action.


The downside of this is some duplication of code in the middle layers.
I don't mind doing that if you are OK with that.

Also note that if we go with amend options, we will have to use the single
API.


Best regards,
        Maxim Levitsky