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    SubjectRe: [PATCH v2 03/18] crypto: dh - optimize domain parameter serialization for well-known groups
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    On 12/13/21 11:06 AM, Nicolai Stange wrote:
    > Hannes Reinecke <hare@suse.de> writes:
    >
    >> On 12/9/21 10:03 AM, Nicolai Stange wrote:
    >>> diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c
    >>> index aabc91e4f63f..9f21204e5dee 100644
    >>> --- a/crypto/dh_helper.c
    >>> +++ b/crypto/dh_helper.c
    >>> @@ -45,18 +72,24 @@ int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
    >>> .type = CRYPTO_KPP_SECRET_TYPE_DH,
    >>> .len = len
    >>> };
    >>> + int group_id;
    >>>
    >>> if (unlikely(!len))
    >>> return -EINVAL;
    >>>
    >>> ptr = dh_pack_data(ptr, end, &secret, sizeof(secret));
    >>> + group_id = (int)params->group_id;
    >>> + ptr = dh_pack_data(ptr, end, &group_id, sizeof(group_id));
    >>
    >> Me being picky again.
    >> To my knowledge, 'int' doesn't have a fixed width, but is rather only
    >> guaranteed to hold certain values.
    >> So as soon as one relies on any fixed size (as this one does) I tend to
    >> use fixed size type like 'u32' to make it absolutely clear what is to be
    >> expected here.
    >>
    >> But the I don't know the conventions in the crypto code; if an 'int' is
    >> assumed to be 32 bits throughout the crypto code I guess we should be fine.
    >
    > Yes, I thought about this, too. However, the other, already existing
    > fields like ->key_size and ->p_size are getting serialized as unsigned
    > ints and I decided to stick to that for ->group_id as well. Except for
    > the testmgr vectors, the encoding is internal to the
    > crypto_dh_encode_key() and crypto_dh_decode_key() pair anyway -- all
    > that would happen if sizeof(int) != 4 is that the tests would fail.
    >
    > So, IMO, making the serialization of struct dh to use u32 throughout is
    > not really in scope for this series and would probably deserve a patch
    > on its own, if desired.
    >
    As I thought.

    So that's okay, then.

    Reviewed-by: Hannes Reinecke <hare@suse.de>

    Cheers,

    Hannes
    --
    Dr. Hannes Reinecke Kernel Storage Architect
    hare@suse.de +49 911 74053 688
    SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
    HRB 36809 (AG Nürnberg), GF: Felix Imendörffer

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