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Date:   Mon, 16 Oct 2023 11:14:38 +0200
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Subject: Re: [PATCH v2 1/2] nvme-auth: use transformed key size to create resp
To:     Mark O'Donovan <shiftee@posteo.net>, linux-kernel@vger.kernel.org
Cc:     linux-nvme@lists.infradead.org, sagi@grimberg.me, hch@lst.de,
        axboe@kernel.dk, kbusch@kernel.org,
        Akash Appaiah <Akash.Appaiah@dell.com>
References: <20231016085715.3068974-1-shiftee@posteo.net>
 <20231016085715.3068974-2-shiftee@posteo.net>
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From:   Hannes Reinecke <hare@suse.de>
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In-Reply-To: <20231016085715.3068974-2-shiftee@posteo.net>
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On 10/16/23 10:57, Mark O'Donovan wrote:
> This does not change current behaviour as the driver currently
> verifies that the secret size is the same size as the length of
> the transformation hash.
> 
> Co-developed-by: Akash Appaiah <Akash.Appaiah@dell.com>
> Signed-off-by: Akash Appaiah <Akash.Appaiah@dell.com>
> Signed-off-by: Mark O'Donovan <shiftee@posteo.net>
> ---
> V1 -> V2: support target implementation and controller secrets also
> 
>   drivers/nvme/common/auth.c | 6 +++++-
>   drivers/nvme/host/auth.c   | 4 ++--
>   drivers/nvme/target/auth.c | 4 ++--
>   include/linux/nvme-auth.h  | 3 ++-
>   4 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c
> index d90e4f0c08b7..26a7fbdf4d55 100644
> --- a/drivers/nvme/common/auth.c
> +++ b/drivers/nvme/common/auth.c
> @@ -243,6 +243,8 @@ u8 *nvme_auth_transform_key(struct nvme_dhchap_key *key, char *nqn)
>   	}
>   	if (key->hash == 0) {
>   		transformed_key = kmemdup(key->key, key->len, GFP_KERNEL);
> +		if (transformed_key)
> +			key->transformed_len = key->len;
>   		return transformed_key ? transformed_key : ERR_PTR(-ENOMEM);

Hmm. But now we're inconsistent.
The input structure 'key' doesn't know (nor does care) if the key has 
been transformed; the transformation itself is returned in a different 
structure.

If we were to go that way the it'll be better to return a 'struct 
nvme_dhchap_key' from nvme_auth_transform_key(), which will then 
encapsulate the data and the correct length.

Which probably is not a bad idea, seeing that a key transform really 
should generate a new key.

Hmm?

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Frankenstr. 146, 90461 Nürnberg
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