linux-kernel - Re: [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig for init command line

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Date:   Sat, 1 Aug 2020 22:33:18 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Frank Rowand <frowand.list@...il.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Tim Bird <Tim.Bird@...y.com>, Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Rob Herring <robh+dt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig
 for init command line

On Fri, Feb 07, 2020 at 02:46:03PM -0500, Steven Rostedt wrote:
> 
> diff --git a/init/main.c b/init/main.c
> index 491f1cdb3105..113c8244e5f0 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -142,6 +142,15 @@ static char *extra_command_line;
>  /* Extra init arguments */
>  static char *extra_init_args;
>  
> +#ifdef CONFIG_BOOT_CONFIG
> +/* Is bootconfig on command line? */
> +static bool bootconfig_found;
> +static bool initargs_found;
> +#else
> +# define bootconfig_found false
> +# define initargs_found false
> +#endif
> +
>  static char *execute_command;
>  static char *ramdisk_execute_command;
>  
> @@ -336,17 +345,32 @@ u32 boot_config_checksum(unsigned char *p, u32 size)
>  	return ret;
>  }
>  
> +static int __init bootconfig_params(char *param, char *val,
> +				    const char *unused, void *arg)
> +{
> +	if (strcmp(param, "bootconfig") == 0) {
> +		bootconfig_found = true;
> +	} else if (strcmp(param, "--") == 0) {
> +		initargs_found = true;
> +	}
> +	return 0;
> +}
> +

I came across this as I was poking around some of the command line
parsing. AFAICT, initargs_found will never be set to true here, because
parse_args handles "--" itself by immediately returning: it doesn't
invoke the callback for it. So you'd instead have to check the return of
parse_args("bootconfig"...) to detect the initargs_found case.

>  static void __init setup_boot_config(const char *cmdline)
>  {
> +	static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata;
>  	u32 size, csum;
>  	char *data, *copy;
>  	const char *p;
>  	u32 *hdr;
>  	int ret;
>  
> -	p = strstr(cmdline, "bootconfig");
> -	if (!p || (p != cmdline && !isspace(*(p-1))) ||
> -	    (p[10] && !isspace(p[10])))
> +	/* All fall through to do_early_param. */
> +	strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
> +	parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
> +		   bootconfig_params);
> +
> +	if (!bootconfig_found)
>  		return;