linux-kernel - Re: [PATCH v2 5/5] LSM: LoadPin for kernel file loading restrictions

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Date:	Thu, 31 Mar 2016 17:24:02 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	Kees Cook <keescook@...omium.org>
Cc:	James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kalle Valo <kvalo@...eaurora.org>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Joe Perches <joe@...ches.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Jiri Slaby <jslaby@...e.com>, Paul Moore <pmoore@...hat.com>,
	Stephen Smalley <sds@...ho.nsa.gov>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Andreas Gruenbacher <agruenba@...hat.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Vitaly Kuznetsov <vkuznets@...hat.com>,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/5] LSM: LoadPin for kernel file loading restrictions

On Mon, 2016-03-28 at 14:14 -0700, Kees Cook wrote:

> +static const char *id_str[READING_MAX_ID] = {
> +	[READING_FIRMWARE] = "firmware",
> +	[READING_MODULE] = "kernel module",
> +	[READING_KEXEC_IMAGE] = "kexec image",
> +	[READING_KEXEC_INITRAMFS] = "kexec initramfs",
> +	[READING_POLICY] = "security policy",
> +};
> +
> +static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
> +{
> +	struct super_block *load_root;
> +	const char *origin;
> +
> +	if (id < 0 || id >= READING_MAX_ID)
> +		return -EINVAL;
> +

The kernel_read_file_id enumeration starts at 1.

> +	origin = id_str[id];
> +	if (!origin) {
> +		origin = "unknown";

Right, all the entries in the kernel_read_file_id enumeration are
currently listed in id_str.  Checking origin is needed for when id_str[]
isn't kept in sync with the enumeration.

Looks good!

Mimi