From:   David Laight <David.Laight@ACULAB.COM>
To:     'Bhaskar Chowdhury' <unixbhaskar@gmail.com>,
        "masahiroy@kernel.org" <masahiroy@kernel.org>,
        "nicolas@fjasle.eu" <nicolas@fjasle.eu>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-kbuild@vger.kernel.org" <linux-kbuild@vger.kernel.org>
Subject: RE: [PATCH] Kbuild: Elevate sha1sum to sha256sum for atomic headers
 check
Thread-Topic: [PATCH] Kbuild: Elevate sha1sum to sha256sum for atomic headers
 check
Thread-Index: AQHZVz7+3Ra3OwIixEm7c88WA//5ha7+rdKg
Date:   Fri, 17 Mar 2023 08:58:09 +0000
Message-ID: <0bbdd88ca0cb465a85d7b90ebacb5e83@AcuMS.aculab.com>
References: <20230315130518.4496-1-unixbhaskar@gmail.com>
In-Reply-To: <20230315130518.4496-1-unixbhaskar@gmail.com>
Accept-Language: en-GB, en-US
MIME-Version: 1.0
Content-Language: en-US
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8BIT
Precedence: bulk

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.
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@gmail.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)