linux-kernel - Re: [PATCH v6 2/4] powerpc: expose secure variables to userspace via sysfs

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Message-ID: <79a6a7de-360c-c5c9-04e9-807952098ae5@linux.microsoft.com>
Date:   Tue, 5 Nov 2019 19:22:19 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Eric Richter <erichte@...ux.ibm.com>, linuxppc-dev@...abs.org,
        linux-efi@...r.kernel.org, linux-integrity@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Jeremy Kerr <jk@...abs.org>,
        Matthew Garret <matthew.garret@...ula.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Claudio Carvalho <cclaudio@...ux.ibm.com>,
        George Wilson <gcwilson@...ux.ibm.com>,
        Elaine Palmer <erpalmer@...ibm.com>,
        Oliver O'Halloran <oohall@...il.com>,
        Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH v6 2/4] powerpc: expose secure variables to userspace via
 sysfs

On 11/5/2019 12:24 AM, Eric Richter wrote:

> From: Nayna Jain <nayna@...ux.ibm.com>
> 
> PowerNV secure variables, which store the keys used for OS kernel
> verification, are managed by the firmware. These secure variables need to
> be accessed by the userspace for addition/deletion of the certificates.
> 
> This patch adds the sysfs interface to expose secure variables for PowerNV
> secureboot. The users shall use this interface for manipulating
> the keys stored in the secure variables.

Can this patch be split into smaller set of changes:
1, Definitions of attribute functions like backend_show, size_show, etc.
2, secvar_sysfs_load
3, secvar_sysfs_init
4, secvar_sysfs_exit

> +static int secvar_sysfs_load(void)
> +{
> +	char *name;
> +	uint64_t namesize = 0;
> +	struct kobject *kobj;
> +	int rc;
> +
> +	name = kzalloc(NAME_MAX_SIZE, GFP_KERNEL);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	do {
> +		rc = secvar_ops->get_next(name, &namesize, NAME_MAX_SIZE);
> +		if (rc) {
> +			if (rc != -ENOENT)
> +				pr_err("error getting secvar from firmware %d\n",
> +					rc);
> +			break;
> +		}
> +
> +		kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
> +		if (!kobj) {
> +			rc = -ENOMEM;
> +			break;
> +		}
> +
> +		kobject_init(kobj, &secvar_ktype);
> +
> +		rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
> +		if (rc) {
> +			pr_warn("kobject_add error %d for attribute: %s\n", rc,
> +				name);
> +			kobject_put(kobj);
> +			kobj = NULL;
> +		}
> +
> +		if (kobj)
> +			kobject_uevent(kobj, KOBJ_ADD);

kobject_event() will add kobj and free the memory when done using the 
object?

  -lakshmi