linux-kernel - Re: [PATCH v3 4/6] tpm: TPM 2.0 sysfs attributes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20141016160358.GB12979@intel.com>
Date:	Thu, 16 Oct 2014 18:03:58 +0200
From:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:	Greg KH <greg@...ah.com>
Cc:	Peter Huewe <peterhuewe@....de>, Ashley Lai <ashley@...leylai.com>,
	Marcel Selhorst <tpmdd@...horst.net>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	linux-api@...r.kernel.org, josh.triplett@...el.com,
	christophe.ricard@...il.com, will.c.arthur@...el.com,
	monty.wiseman@...el.com
Subject: Re: [PATCH v3 4/6] tpm: TPM 2.0 sysfs attributes

On Thu, Oct 16, 2014 at 11:31:46AM +0200, Greg KH wrote:
> On Wed, Oct 15, 2014 at 01:35:14PM +0200, Jarkko Sakkinen wrote:
> > +int tpm2_sysfs_add_device(struct tpm_chip *chip)
> > +{
> > +	struct pcr_bank *pcr_bank;
> > +	struct kobject *pcrs_kobj;
> > +	struct device *dev = chip->dev;
> > +	int rc;
> > +
> > +	rc = sysfs_create_group(&chip->vendor.miscdev.this_device->kobj,
> > +				&tpm_dev_group);
> > +	if (rc) {
> > +		dev_err(dev, "failed to create sysfs attributes, %d\n", rc);
> > +		return rc;
> > +	}
> 
> You just raced and created sysfs files _after_ userspace saw that your
> device was enabled.

Here the options are limited because misc_register already spawns
KOBJ_ADD. Not much to do unless we would wipe the current use of 
misc driver completely.

> 
> > +	pcrs_kobj = kobject_create_and_add("pcrs",
> > +					   &chip->vendor.miscdev.this_device->kobj);
> 
> Ick, no no no no.  Never create a kobject under a 'struct device'.  You
> just lost all libudev support for any attribute you created under here,
> not good at all.  Use a "real" device if you really want a sub-device,
> not a kobject.

Ack, will rework this.

> thanks,
> 
> greg k-h

/Jarkko
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/