linux-kernel - Re: [PATCH v6 3/6] KEYS: make partial key id matching as a dedicated function

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Message-id: <53B162C2.3070800@samsung.com>
Date:	Mon, 30 Jun 2014 16:14:42 +0300
From:	Dmitry Kasatkin <d.kasatkin@...sung.com>
To:	David Howells <dhowells@...hat.com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Cc:	keyrings <keyrings@...ux-nfs.org>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Josh Boyer <jwboyer@...hat.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Dmitry Kasatkin <dmitry.kasatkin@...il.com>
Subject: Re: [PATCH v6 3/6] KEYS: make partial key id matching as a dedicated
 function

On 27/06/14 16:38, David Howells wrote:
> Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote:
>
>> +	if (strncmp(id, "id:", 3) == 0)

>> Use memcmp() here.

'id' function parameter comes from "keys_ownerid" kernel parameter.
User can supply anything shorter than "id:".
Though comparing 3 bytes should not produce any memory access errors,
memcmp can access beyond the length of the string.
I think 'strcnmp' is more appropriate here...


>> -	kid += kidlen - idlen;
>> -	if (strcasecmp(id, kid) != 0)
>> -		return 0;
> This test is no longer applied in the "<subtype>:..." case.

I did not get fully what you comment here or ask to do..
But yes, with this patch, it is no longer the case.

Thanks,
Dmitry

> David
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