linux-kernel - Re: [RFC PATCH 5/8] KEYS: Provide software public key query function [ver 3]

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Date:	Thu, 12 May 2016 10:01:05 -0700 (PDT)
From:	Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:	David Howells <dhowells@...hat.com>
cc:	Mat Martineau <mathew.j.martineau@...ux.intel.com>,
	tadeusz.struk@...el.com, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, keyrings@...r.kernel.org,
	linux-crypto@...r.kernel.org, dwmw2@...radead.org
Subject: Re: [RFC PATCH 5/8] KEYS: Provide software public key query function
 [ver 3]


On Thu, 12 May 2016, David Howells wrote:

> Mat Martineau <mathew.j.martineau@...ux.intel.com> wrote:
>
>>> +	len = crypto_akcipher_maxsize(tfm);
>>> +	info->key_size = len * 8;
>>> +	info->max_data_size = len;
>>> +	info->max_sig_size = len;
>>> +	info->max_enc_size = len;
>>> +	info->max_dec_size = len;
>>
>> If len > UINT16_MAX, should UINT16_MAX be reported as the max size? Similar
>> question for len*8 and key_size.
>
> key_size is 32 bits, but the other sizes are all 16 bits, so you would need a
> 524288-bit key to exceed their capacity.  I'm not sure that's likely anytime
> soon, but should I just make all the sizes 32-bit anyway?

Given that cryto_akcipher_maxsize() returns an int and keyctl_pkey_query 
is part of the userspace API, I support bumping the sizes to 32-bit.

--
Mat Martineau
Intel OTC