linux-kernel - Re: [PATCH v9 2/4] tpm: Proxy driver for supporting multiple emulated TPMs

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Date:	Mon, 11 Apr 2016 12:14:03 -0600
From:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:	Stefan Berger <stefanb@...ux.vnet.ibm.com>,
	tpmdd-devel@...ts.sourceforge.net,
	linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v9 2/4] tpm: Proxy driver for supporting multiple
 emulated TPMs

On Mon, Apr 11, 2016 at 11:43:58AM +0300, Jarkko Sakkinen wrote:
> On Thu, Apr 07, 2016 at 11:49:44AM -0400, Stefan Berger wrote:
> > On 04/07/2016 08:35 AM, Jarkko Sakkinen wrote:
> > >On Tue, Mar 29, 2016 at 02:19:12PM -0400, Stefan Berger wrote:
> > >>This patch implements a proxy driver for supporting multiple emulated TPMs
> > >>in a system.
> > >>
> > >>The driver implements a device /dev/vtpmx that is used to created
> > >>a client device pair /dev/tpmX (e.g., /dev/tpm10) and a server side that
> > >>is accessed using a file descriptor returned by an ioctl.
> > >>The device /dev/tpmX is the usual TPM device created by the core TPM
> > >>driver. Applications or kernel subsystems can send TPM commands to it
> > >>and the corresponding server-side file descriptor receives these
> > >>commands and delivers them to an emulated TPM.
> > >>
> > >>Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>
> > >>CC: linux-kernel@...r.kernel.org
> > >>CC: linux-doc@...r.kernel.org
> > >>CC: linux-api@...r.kernel.org
> > >Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > >Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > 
> > Thanks. So I can post a v10 where I have to re-introduce the priv field but
> > put it into the tpm_chip struct. Obviously it needs this field. I am not
> > sure whether you'll let me take the Reviewed-by and Tested-by, though?
> 
> Lets hold for them then. I'll do retest when I get the new series.

Lets just fix the sysfs stuff the same way we fixed ppi and be done
with this issue.

Something that looks kinda like this untested thing:

diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
index a7c3473c3421..51e898be4307 100644
--- a/drivers/char/tpm/tpm-sysfs.c
+++ b/drivers/char/tpm/tpm-sysfs.c
@@ -36,7 +36,7 @@ static ssize_t pubek_show(struct device *dev, struct device_attribute *attr,
 	int i, rc;
 	char *str = buf;
 
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	tpm_cmd.header.in = tpm_readpubek_header;
 	err = tpm_transmit_cmd(chip, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
@@ -92,7 +92,7 @@ static ssize_t pcrs_show(struct device *dev, struct device_attribute *attr,
 	ssize_t rc;
 	int i, j, num_pcrs;
 	char *str = buf;
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	rc = tpm_getcap(dev, TPM_CAP_PROP_PCR, &cap,
 			"attempting to determine the number of PCRS");
@@ -222,7 +222,7 @@ static DEVICE_ATTR_RO(caps);
 static ssize_t cancel_store(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t count)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 	if (chip == NULL)
 		return 0;
 
@@ -234,7 +234,7 @@ static DEVICE_ATTR_WO(cancel);
 static ssize_t durations_show(struct device *dev, struct device_attribute *attr,
 			      char *buf)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	if (chip->duration[TPM_LONG] == 0)
 		return 0;
@@ -251,7 +251,7 @@ static DEVICE_ATTR_RO(durations);
 static ssize_t timeouts_show(struct device *dev, struct device_attribute *attr,
 			     char *buf)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	return sprintf(buf, "%d %d %d %d [%s]\n",
 		       jiffies_to_usecs(chip->timeout_a),
@@ -283,22 +283,33 @@ static const struct attribute_group tpm_dev_group = {
 
 int tpm_sysfs_add_device(struct tpm_chip *chip)
 {
-	int err;
-	err = sysfs_create_group(&chip->dev.parent->kobj,
-				 &tpm_dev_group);
+	const struct attribute **i;
 
-	if (err)
-		dev_err(&chip->dev,
-			"failed to create sysfs attributes, %d\n", err);
-	return err;
+	chip->groups[chip->groups_cnt++] = &tpm_dev_group;
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		return 0;
+
+	for (i = tpm_dev_attrs; *i != NULL; ++i) {
+		rc = __compat_only_sysfs_link_entry_to_kobj(
+		    &chip->dev.parent->kobj, &chip->dev.kobj, (*i)->name);
+		if (rc && rc != -ENOENT) {
+			tpm_sysfs_del_device(chip);
+			return rc;
+		}
+	}
+
+	return 0;
 }
 
 void tpm_sysfs_del_device(struct tpm_chip *chip)
 {
-	/* The sysfs routines rely on an implicit tpm_try_get_ops, this
-	 * function is called before ops is null'd and the sysfs core
-	 * synchronizes this removal so that no callbacks are running or can
-	 * run again
+	const struct attribute **i;
+
+	/* The sysfs routines rely on an implicit tpm_try_get_ops, device_del
+	 * is called before ops is null'd and the sysfs core synchronizes this
+	 * removal so that no callbacks are running or can run again
 	 */
-	sysfs_remove_group(&chip->dev.parent->kobj, &tpm_dev_group);
+
+	for (i = tpm_dev_attrs; *i != NULL; ++i)
+		sysfs_remove_link(&chip->dev.parent->kobj, (*i)->name);
 }