linux-kernel - Re: [PATCH v1 2/2] kselftest: vm: add tests for memory-deny-write-execute

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Message-ID: <202210281316.C83D6B5649@keescook>
Date:   Fri, 28 Oct 2022 13:19:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Joey Gouly <joey.gouly@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Lennart Poettering <lennart@...ttering.net>,
        Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Szabolcs Nagy <szabolcs.nagy@....com>,
        Mark Brown <broonie@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Topi Miettinen <toiwoton@...il.com>, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-abi-devel@...ts.sourceforge.net, nd@....com, shuah@...nel.org
Subject: Re: [PATCH v1 2/2] kselftest: vm: add tests for
 memory-deny-write-execute

On Wed, Oct 26, 2022 at 04:04:57PM +0100, Joey Gouly wrote:
> [...]
> +# define PR_MDWE_FLAG_MMAP              1
> [...]
> +	// Enable MDWE and then run the tests again.
> +	ret = prctl(PR_SET_MDWE, PR_MDWE_FLAG_MMAP, 0, 0, 0);
> +	if (ret < 0) {
> +		ksft_print_msg("PR_SET_MDWE failed or unsupported!\n");
> +		goto exit;
> +	}
> +
> +	ret = prctl(PR_GET_MDWE, PR_MDWE_FLAG_MMAP, 0, 0, 0);
> +	if (ret == 0)
> +		ksft_exit_fail_msg("PR_GET_MDWE failed!");

This flag (PR_MDWE_FLAG_MMAP), while defined in uapi, wasn't actually
being used in the proposed prctl() api. :)

-- 
Kees Cook