linux-kernel - Re: [PATCH v5 2/9] proc/sysctl: Provide additional ctl

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Date:   Sat, 17 Mar 2018 00:54:58 +0000
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Waiman Long <longman@...hat.com>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Matthew Wilcox <willy@...radead.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH v5 2/9] proc/sysctl: Provide additional ctl_table.flags
 checks

On Fri, Mar 16, 2018 at 02:13:43PM -0400, Waiman Long wrote:
> Checking code is added to provide the following additional
> ctl_table.flags checks:
> 
>  1) No unknown flag is allowed.
>  2) Minimum of a range cannot be larger than the maximum value.
>  3) The signed and unsigned flags are mutually exclusive.
>  4) The proc_handler should be consistent with the signed or unsigned
>     flags.
> 
> Two new flags are added to indicate if the min/max values are signed
> or unsigned - CTL_FLAGS_SIGNED_RANGE & CTL_FLAGS_UNSIGNED_RANGE.
> These 2 flags can be optionally enabled for range checking purpose.
> But either one of them must be set with CTL_FLAGS_CLAMP_RANGE.
> 
> Signed-off-by: Waiman Long <longman@...hat.com>
> ---

> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index e446e1f..088f032 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -134,14 +134,26 @@ struct ctl_table
>   *	the input value. No lower bound or upper bound checking will be
>   *	done if the corresponding minimum or maximum value isn't provided.
>   *
> + * @CTL_FLAGS_SIGNED_RANGE: Set to indicate that the extra1 and extra2
> + *	fields are pointers to minimum and maximum signed values of
> + *	an allowable range.
> + *
> + * @CTL_FLAGS_UNSIGNED_RANGE: Set to indicate that the extra1 and extra2
> + *	fields are pointers to minimum and maximum unsigned values of
> + *	an allowable range.
> + *
>   * At most 16 different flags are allowed.
>   */
>  enum ctl_table_flags {
>  	CTL_FLAGS_CLAMP_RANGE		= BIT(0),
> -	__CTL_FLAGS_MAX			= BIT(1),
> +	CTL_FLAGS_SIGNED_RANGE		= BIT(1),
> +	CTL_FLAGS_UNSIGNED_RANGE	= BIT(2),
> +	__CTL_FLAGS_MAX			= BIT(3),
>  };

You are adding new flags which the user can set, and yet these are used
internally.

It would be best if internal flags are just that, not flags that a user can set.

This patch should be folded with the first one.

I'm starting to loose hope on these patch sets.

  Luis