linux-hardening - Re: [PATCH] checkpatch: Check for strcpy and strncpy too

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Date:   Wed, 17 May 2023 13:36:17 -0700
From:   Joe Perches <joe@...ches.com>
To:     Kees Cook <keescook@...omium.org>,
        Andy Whitcroft <apw@...onical.com>
Cc:     Dwaipayan Ray <dwaipayanray1@...il.com>,
        Lukas Bulwahn <lukas.bulwahn@...il.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] checkpatch: Check for strcpy and strncpy too

On Wed, 2023-05-17 at 13:13 -0700, Kees Cook wrote:
> Warn about strcpy(), strncpy(), and strlcpy(). Suggest strscpy() and
> include pointers to the open KSPP issues for each, which has further
> details and replacement procedures.
> 
> Cc: Andy Whitcroft <apw@...onical.com>
> Cc: Joe Perches <joe@...ches.com>
> Cc: Dwaipayan Ray <dwaipayanray1@...il.com>
> Cc: Lukas Bulwahn <lukas.bulwahn@...il.com>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  scripts/checkpatch.pl | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index b30114d637c4..a90e0ede53ad 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -6997,10 +6997,22 @@ sub process {
>  #			}
>  #		}
>  
> +# strcpy uses that should likely be strscpy
> +		if ($line =~ /\bstrcpy\s*\(/) {
> +			WARN("STRCPY",
> +			     "Use of strcpy has been replaced with strscpy - see: https://github.com/KSPP/linux/issues/88\n" . $herecurr);

I would prefer something like

			"Prefer strscpy over strcpy etc..."

as there are just too many existing uses of strcpy that can not
easily be converted.

$ git grep -w strcpy -- "*.[chS]" | wc -l
2015

> +		}
> +
>  # strlcpy uses that should likely be strscpy
>  		if ($line =~ /\bstrlcpy\s*\(/) {
>  			WARN("STRLCPY",
> -			     "Prefer strscpy over strlcpy - see: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw\@mail.gmail.com/\n" . $herecurr);
> +			     "Use of strlcpy has been replaced with strscpy - see: https://github.com/KSPP/linux/issues/89\n" . $herecurr);
> +		}
> +
> +# strncpy uses that should likely be strscpy or strscpy_pad
> +		if ($line =~ /\bstrncpy\s*\(/) {
> +			WARN("STRNCPY",
> +			     "Prefer strscpy, strscpy_pad, or __nonstring over strncpy - see: https://github.com/KSPP/linux/issues/90\n" . $herecurr);
>  		}
>  
>  # typecasts on min/max could be min_t/max_t