On Thu, Sep 08, 2016 at 12:44:55PM -0500, Eric Blake wrote:
> On 09/08/2016 11:27 AM, Daniel P. Berrange wrote:
> > As protection against bruteforcing passphrases, the PBKDF
> > algorithm is tuned by counting the number of iterations
> > needed to produce 1 second of running time. If the machine
> > that the image will be used on is much faster than the
> > machine where the image is created, it can be desirable
> > to raise the number of limits. This adds a new 'iter-time'
>
> s/limits/iterations/ ?
>
> > property that allows the user to choose the iteration
> > wallclock time.
> >
> > Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
> > ---
> > block/crypto.c | 6 ++++++
> > crypto/block-luks.c | 32 +++++++++++++++++++++++---------
> > qapi/crypto.json | 6 +++++-
> > 3 files changed, 34 insertions(+), 10 deletions(-)
> >
>
> > +++ b/crypto/block-luks.c
> > @@ -917,8 +917,12 @@ qcrypto_block_luks_create(QCryptoBlock *block,
> > const char *hash_alg;
> > char *cipher_mode_spec = NULL;
> > QCryptoCipherAlgorithm ivcipheralg = 0;
> > + uint64_t iters;
> >
> > memcpy(&luks_opts, &options->u.luks, sizeof(luks_opts));
> > + if (!luks_opts.has_iter_time) {
> > + luks_opts.iter_time = 1000;
> > + }
> > if (!luks_opts.has_cipher_alg) {
> > luks_opts.cipher_alg = QCRYPTO_CIPHER_ALG_AES_256;
> > }
> > @@ -1064,7 +1068,7 @@ qcrypto_block_luks_create(QCryptoBlock *block,
> > /* Determine how many iterations we need to hash the master
> > * key, in order to have 1 second of compute time used
> > */
> > - luks->header.master_key_iterations =
> > + iters = luks_opts.iter_time *
> > qcrypto_pbkdf2_count_iters(luks_opts.hash_alg,
>
> luks_opts.iter_time is a user-provided 64-bit value, so this
> multiplication can overflow...
Oh doh, there I was thinkig it was just a 32bit int...
Regards,
Daniel
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