linux-kernel - Re: [PATCH] Kbuild: Elevate sha1sum to sha256sum for atomic headers check

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Date:   Sat, 18 Mar 2023 08:56:45 +0530
From:   Bhaskar Chowdhury <unixbhaskar@...il.com>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     "masahiroy@...nel.org" <masahiroy@...nel.org>,
        "nicolas@...sle.eu" <nicolas@...sle.eu>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-kbuild@...r.kernel.org" <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH] Kbuild: Elevate sha1sum to sha256sum for atomic headers
 check

On 08:58 Fri 17 Mar 2023, David Laight wrote:
>From: Bhaskar Chowdhury
>> Sent: 15 March 2023 13:05
>>
>> Thought it would be a good idea to use a elevated mechanism i.e sha256sum
>
>How can this change possibly work.
>It is just a list of definitions read by another makefile.
>You've changed the name of a definition without changing where it is used.
>Also if the code is looking for a change, you'd need to change
>what it is compared against.

Gotcha. Thanks for the heads-up , David. I missed it.

>In any case no one is worried about malicious attempts to change
>things without being noticed, even sha1 is OTT.
>
>        David
>
>>
>> Signed-off-by: Bhaskar Chowdhury <unixbhaskar@...il.com>
>> ---
>>  Kbuild | 10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/Kbuild b/Kbuild
>> index 464b34a08f51..b74040346d76 100644
>> --- a/Kbuild
>> +++ b/Kbuild
>> @@ -45,14 +45,14 @@ missing-syscalls: scripts/checksyscalls.sh $(offsets-file)
>>
>>  # Check the manual modification of atomic headers
>>
>> -quiet_cmd_check_sha1 = CHKSHA1 $<
>> -      cmd_check_sha1 = \
>> -     if ! command -v sha1sum >/dev/null; then \
>> -             echo "warning: cannot check the header due to sha1sum missing"; \
>> +quiet_cmd_check_sha256 = CHKSHA256 $<
>> +      cmd_check_sha256 = \
>> +     if ! command -v sha256sum >/dev/null; then \
>> +             echo "warning: cannot check the header due to sha256sum missing"; \
>>               exit 0; \
>>       fi; \
>>       if [ "$$(sed -n '$$s:// ::p' $<)" != \
>> -          "$$(sed '$$d' $< | sha1sum | sed 's/ .*//')" ]; then \
>> +          "$$(sed '$$d' $< | sha256sum | sed 's/ .*//')" ]; then \
>>               echo "error: $< has been modified." >&2; \
>>               exit 1; \
>>       fi; \
>> --
>> 2.39.2
>
>-
>Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
>Registration No: 1397386 (Wales)
--
Thanks,
Bhaskar

"Here's looking at you kid"-- Casablanca
https://about.me/unixbhaskar

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