linux-kernel - Re: [PATCH v4 1/1] use crc32 instead of md5 for hibernation e820 integrity check

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Message-ID: <822eaebf-4ef9-d469-4238-54107c8ba6a6@redhat.com>
Date:   Fri, 9 Apr 2021 15:28:15 -0400
From:   Chris von Recklinghausen <crecklin@...hat.com>
To:     David Laight <David.Laight@...LAB.COM>,
        "ardb@...nel.org" <ardb@...nel.org>,
        "simo@...hat.com" <simo@...hat.com>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "decui@...rosoft.com" <decui@...rosoft.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 1/1] use crc32 instead of md5 for hibernation e820
 integrity check

On 4/9/21 12:56 PM, David Laight wrote:
> From: Chris von Recklinghausen
>> Sent: 08 April 2021 11:46
>>
>> Suspend fails on a system in fips mode because md5 is used for the e820
>> integrity check and is not available. Use crc32 instead.
>>
>> Prior to this patch, MD5 is used only to create a digest to ensure integrity of
>> the region, no actual encryption is done. This patch set changes the integrity
>> check to use crc32 instead of md5 since crc32 is available in both FIPS and
>> non-FIPS modes.
>>
>> Note that the digest is only used as an integrity check. No actual encryption
>> is done.
> If crc32 is good enough, would a 1's compliment sum be good enough?
> It is likely to be faster to calculate and not need special
> functions be built into the kernel at all.


Eric Biggers <ebiggers@...nel.org> suggested using crc32_le() which is 
in the library interface (lib/crc32.c) and will always be available 
without any special ifdefs. That's what my next version will be based on.

Thanks,

Chris


>
> 	David
>
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