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Date: Thu, 08 Mar 2018 13:50:30 -0500
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Tycho Andersen <tycho@...ho.ws>,
Andy Shevchenko
<andy.shevchenko@...il.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
linux-integrity@...r.kernel.org,
Linux Kernel Mailing List
<linux-kernel@...r.kernel.org>,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH] ima: drop vla in ima_audit_measurement()
On Thu, 2018-03-08 at 11:37 -0700, Tycho Andersen wrote:
> On Thu, Mar 08, 2018 at 07:47:37PM +0200, Andy Shevchenko wrote:
> > On Thu, Mar 8, 2018 at 7:14 PM, Tycho Andersen <tycho@...ho.ws> wrote:
> > > In keeping with the directive to get rid of VLAs [1], let's drop the VLA
> > > from ima_audit_measurement(). We need to adjust the return type of
> > > ima_audit_measurement, because now this function can fail if an allocation
> > > fails.
> >
> >
> >
> > > + algo_hash_len = hash_len + strlen(algo_name) + 2;
> > > + algo_hash = kzalloc(algo_hash_len, GFP_KERNEL);
> >
> > > - snprintf(algo_hash, sizeof(algo_hash), "%s:%s", algo_name, hash);
> > > + snprintf(algo_hash, algo_hash_len, "%s:%s", algo_name, hash);
> >
> > kasprintf() ?
>
> Sure, in fact I think we could just do:
>
> - snprintf(algo_hash, algo_hash_len, "%s:%s", algo_name, hash);
> - audit_log_untrustedstring(ab, algo_hash);
> + audit_log_untrustedstring(ab, algo_name);
> + audit_log_format(ab, ":");
> + audit_log_untrustedstring(ab, hash);
>
> and get rid of the allocation entirely. I'll test and make sure it
> works and then re-send.
The hash algorithm name is an enumeration that comes from the kernel.
It's defined in crypto/hash_info.c: hash_algo_name. Why do we need
to use audit_log_untrustedstring()?
Mimi
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