linux-kernel - Re: [PATCH] bootconfig: Use parse_args() to find bootconfig and '--'

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Date:   Sat, 8 Feb 2020 10:41:11 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Kees Cook <keescook@...omium.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
Subject: Re: [PATCH] bootconfig: Use parse_args() to find bootconfig and
 '--'

On Fri, 7 Feb 2020 19:26:32 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> 
> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
> 
> The current implementation does a naive search of "bootconfig" on the kernel
> command line. But this could find "bootconfig" that is part of another
> option in quotes (although highly unlikely). But it also needs to find '--'
> on the kernel command line to know if it should append a '--' or not when a
> bootconfig in the initrd file has an "init" section. The check uses the
> naive strstr() to find to see if it exists. But this can return a false
> positive if it exists in an option and then the "init" section in the initrd
> will not be appended properly.
> 
> Using parse_args() to find both of these will solve both of these problems.

Thanks Steve and Kees! This looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thank you,


> 
> Link: https://lore.kernel.org/r/202002070954.C18E7F58B@keescook
> 
> Fixes: 7495e0926fdf3 ("bootconfig: Only load bootconfig if "bootconfig" is on the kernel cmdline")
> Fixes: 1319916209ce8 ("bootconfig: init: Allow admin to use bootconfig for init command line")
> Reported-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
>  init/main.c | 36 ++++++++++++++++++++++++++++++------
>  1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/init/main.c b/init/main.c
> index 491f1cdb3105..e7261f1a3523 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 +345,31 @@ 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;
> +}
> +
>  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])))
> +	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;
>  
>  	if (!initrd_end)
> @@ -563,11 +586,12 @@ static void __init setup_command_line(char *command_line)
>  		 * to init.
>  		 */
>  		len = strlen(saved_command_line);
> -		if (!strstr(boot_command_line, " -- ")) {
> +		if (initargs_found) {
> +			saved_command_line[len++] = ' ';
> +		} else {
>  			strcpy(saved_command_line + len, " -- ");
>  			len += 4;
> -		} else
> -			saved_command_line[len++] = ' ';
> +		}
>  
>  		strcpy(saved_command_line + len, extra_init_args);
>  	}
> -- 
> 2.20.1
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>