linux-kernel - Re: [PATCH 7/7] exec: Implement kernel

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Message-ID: <202007141446.A72A4437C@keescook>
Date:   Tue, 14 Jul 2020 14:49:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Al Viro <viro@...iv.linux.org.uk>,
        Luis Chamberlain <mcgrof@...nel.org>,
        linux-fsdevel@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-security-module@...r.kernel.org,
        "Serge E. Hallyn" <serge@...lyn.com>,
        James Morris <jmorris@...ei.org>,
        Kentaro Takeda <takedakn@...data.co.jp>,
        Casey Schaufler <casey@...aufler-ca.com>,
        John Johansen <john.johansen@...onical.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH 7/7] exec: Implement kernel_execve

On Tue, Jul 14, 2020 at 08:31:40AM -0500, Eric W. Biederman wrote:
> +static int count_strings_kernel(const char *const *argv)
> +{
> +	int i;
> +
> +	if (!argv)
> +		return 0;
> +
> +	for (i = 0; argv[i]; ++i) {
> +		if (i >= MAX_ARG_STRINGS)
> +			return -E2BIG;
> +		if (fatal_signal_pending(current))
> +			return -ERESTARTNOHAND;
> +		cond_resched();
> +	}
> +	return i;
> +}

I notice count() is only ever called with MAX_ARG_STRINGS. Perhaps
refactor that too? (And maybe rename it to count_strings_user()?)

Otherwise, looks good:

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook