Re: [PATCH v2 07/14] block/crypto: implement the encryption key management

[Daniel P . Berrangé]

On Sun, Mar 08, 2020 at 05:18:56PM +0200, Maxim Levitsky wrote:
> This implements the encryption key management using the generic code in
> qcrypto layer and exposes it to the user via qemu-img
> 
> This code adds another 'write_func' because the initialization
> write_func works directly on the underlying file, and amend
> works on instance of luks device.
> 
> This commit also adds a 'hack/workaround' I and Kevin Wolf (thanks)
> made to make the driver both support write sharing (to avoid breaking the 
> users),
> and be safe against concurrent  metadata update (the keyslots)
> 
> Eventually the write sharing for luks driver will be deprecated
> and removed together with this hack.
> 
> The hack is that we ask (as a format driver) for BLK_PERM_CONSISTENT_READ
> and then when we want to update the keys, we unshare that permission.
> So if someone else has the image open, even readonly, encryption
> key update will fail gracefully.
> 
> Also thanks to Daniel Berrange for the idea of
> unsharing read, rather that write permission which allows
> to avoid cases when the other user had opened the image read-only.
> 
> Signed-off-by: Maxim Levitsky <address@hidden>
> ---
>  block/crypto.c | 127 +++++++++++++++++++++++++++++++++++++++++++++++--
>  block/crypto.h |  44 +++++++++++++++--
>  2 files changed, 163 insertions(+), 8 deletions(-)

Reviewed-by: Daniel P. Berrangé <address@hidden>


> @@ -661,6 +693,95 @@ block_crypto_get_specific_info_luks(BlockDriverState 
> *bs, Error **errp)
>      return spec_info;
>  }
>  
> +static int
> +block_crypto_amend_options_luks(BlockDriverState *bs,
> +                           QemuOpts *opts,
> +                           BlockDriverAmendStatusCB *status_cb,
> +                           void *cb_opaque,
> +                           bool force,
> +                           Error **errp)

Nitpick - align options after the "("


> @@ -81,11 +86,40 @@
>          .help = "Name of encryption hash algorithm",     \
>      }
>  
> -#define BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(prefix)           \
> -    {                                                         \
> -        .name = prefix BLOCK_CRYPTO_OPT_LUKS_ITER_TIME,       \
> -        .type = QEMU_OPT_NUMBER,                              \
> -        .help = "Time to spend in PBKDF in milliseconds",     \
> +#define BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(prefix)        \
> +    {                                                      \
> +        .name = prefix BLOCK_CRYPTO_OPT_LUKS_ITER_TIME,    \
> +        .type = QEMU_OPT_NUMBER,                           \
> +        .help = "Time to spend in PBKDF in milliseconds",  \
> +    }

Nitpick - no need to change whitespace here

Regards,
Daniel
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