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

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Message-ID: <92771fa9-e5a8-2721-519b-f91da21deb3e@gmail.com>
Date:	Wed, 11 May 2016 17:17:10 -0700
From:	Tadeusz Struk <tstruk@...il.com>
To:	Mat Martineau <mathew.j.martineau@...ux.intel.com>,
	David Howells <dhowells@...hat.com>
Cc:	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 05/11/2016 04:50 PM, Mat Martineau 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.

Hi Mat,
Since all the operations performed are mod key->n the output will never be bigger
than size of pkey->n, which is the return value from crypto_akcipher_maxsize(tfm)
for a given key.
Thanks,
-- 
TS