Re: [tpmdd-devel] [PATCH v7 03/10] tpm: fix multiple race conditions in tpm_ppi.c

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 11/11/2014 08:45 AM, Jarkko Sakkinen wrote:
> Traversal of the ACPI device tree was not done right. It should lookup
> PPI only under the ACPI device that it is associated. Otherwise, it could
> match to a wrong PPI interface if there are two TPM devices in the device
> tree.
>
> Removed global ACPI handle and version string from tpm_ppi.c as this
> is racy. Instead they should be associated with the chip.
>
> Additionally, added the missing copyright platter to tpm_ppi.c.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>   drivers/char/tpm/tpm-chip.c |   4 +-
>   drivers/char/tpm/tpm.h      |  16 ++++--
>   drivers/char/tpm/tpm_ppi.c  | 136 +++++++++++++++++++++++++++-----------------
>   drivers/char/tpm/tpm_tis.c  |  15 +++--
>   4 files changed, 108 insertions(+), 63 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index cf3ad24..647867c 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -148,7 +148,7 @@ int tpm_chip_register(struct tpm_chip *chip)
>   	if (rc)
>   		goto del_misc;
>
> -	rc = tpm_add_ppi(&chip->dev->kobj);
> +	rc = tpm_add_ppi(chip);
>   	if (rc)
>   		goto del_sysfs;
>
> @@ -186,7 +186,7 @@ void tpm_chip_unregister(struct tpm_chip *chip)
>   	synchronize_rcu();
>
>   	tpm_sysfs_del_device(chip);
> -	tpm_remove_ppi(&chip->dev->kobj);
> +	tpm_remove_ppi(chip);
>
>   	if (chip->bios_dir)
>   		tpm_bios_log_teardown(chip->bios_dir);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 9880681..69f4003 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -27,6 +27,7 @@
>   #include <linux/platform_device.h>
>   #include <linux/io.h>
>   #include <linux/tpm.h>
> +#include <linux/acpi.h>
>
>   enum tpm_const {
>   	TPM_MINOR = 224,	/* officially assigned */
> @@ -94,6 +95,8 @@ struct tpm_vendor_specific {
>   #define TPM_VID_WINBOND  0x1050
>   #define TPM_VID_STM      0x104A
>
> +#define TPM_PPI_VERSION_LEN		3
> +
>   struct tpm_chip {
>   	struct device *dev;	/* Device stuff */
>   	const struct tpm_class_ops *ops;
> @@ -109,6 +112,11 @@ struct tpm_chip {
>
>   	struct dentry **bios_dir;
>
> +#ifdef CONFIG_ACPI
> +	acpi_handle acpi_dev_handle;
> +	char ppi_version[TPM_PPI_VERSION_LEN + 1];
> +#endif /* CONFIG_ACPI */
> +
>   	struct list_head list;
>   };
>
> @@ -340,15 +348,15 @@ void tpm_sysfs_del_device(struct tpm_chip *chip);
>   int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
>
>   #ifdef CONFIG_ACPI
> -extern int tpm_add_ppi(struct kobject *);
> -extern void tpm_remove_ppi(struct kobject *);
> +extern int tpm_add_ppi(struct tpm_chip *chip);
> +extern void tpm_remove_ppi(struct tpm_chip *chip);
>   #else
> -static inline int tpm_add_ppi(struct kobject *parent)
> +static inline int tpm_add_ppi(struct tpm_chip *chip)
>   {
>   	return 0;
>   }
>
> -static inline void tpm_remove_ppi(struct kobject *parent)
> +static inline void tpm_remove_ppi(struct tpm_chip *chip)
>   {
>   }
>   #endif
> diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
> index 61dcc80..6acdb17 100644
> --- a/drivers/char/tpm/tpm_ppi.c
> +++ b/drivers/char/tpm/tpm_ppi.c
> @@ -1,3 +1,22 @@
> +/*
> + * Copyright (C) 2012-2014 Intel Corporation
> + *
> + * Authors:
> + * Xiaoyan Zhang <xiaoyan.zhang@intel.com>
> + * Jiang Liu <jiang.liu@linux.intel.com>
> + * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> + *
> + * Maintained by: <tpmdd-devel@lists.sourceforge.net>
> + *
> + * This file contains implementation of the sysfs interface for PPI.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; version 2
> + * of the License.
> + */
> +
> +
>   #include <linux/acpi.h>
>   #include "tpm.h"
>
> @@ -22,45 +41,22 @@ static const u8 tpm_ppi_uuid[] = {
>   	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
>   };
>
> -static char tpm_ppi_version[PPI_VERSION_LEN + 1];
> -static acpi_handle tpm_ppi_handle;
> -
> -static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
> -				void **return_value)
> -{
> -	union acpi_object *obj;
> -
> -	if (!acpi_check_dsm(handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
> -			    1 << TPM_PPI_FN_VERSION))
> -		return AE_OK;
> -
> -	/* Cache version string */
> -	obj = acpi_evaluate_dsm_typed(handle, tpm_ppi_uuid,
> -				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
> -				      NULL, ACPI_TYPE_STRING);
> -	if (obj) {
> -		strlcpy(tpm_ppi_version, obj->string.pointer,
> -			PPI_VERSION_LEN + 1);
> -		ACPI_FREE(obj);
> -	}
> -
> -	*return_value = handle;
> -
> -	return AE_CTRL_TERMINATE;
> -}
> -
>   static inline union acpi_object *
> -tpm_eval_dsm(int func, acpi_object_type type, union acpi_object *argv4)
> +tpm_eval_dsm(acpi_handle dev_handle, int func, acpi_object_type type,
> +	     union acpi_object *argv4)
>   {
> -	BUG_ON(!tpm_ppi_handle);
> -	return acpi_evaluate_dsm_typed(tpm_ppi_handle, tpm_ppi_uuid,
> -				       TPM_PPI_REVISION_ID, func, argv4, type);
> +	BUG_ON(!dev_handle);
> +	return acpi_evaluate_dsm_typed(dev_handle, tpm_ppi_uuid,
> +				       TPM_PPI_REVISION_ID,
> +				       func, argv4, type);
>   }
>
>   static ssize_t tpm_show_ppi_version(struct device *dev,
>   				    struct device_attribute *attr, char *buf)
>   {
> -	return scnprintf(buf, PAGE_SIZE, "%s\n", tpm_ppi_version);
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
> +
> +	return scnprintf(buf, PAGE_SIZE, "%s\n", chip->ppi_version);
>   }
>
>   static ssize_t tpm_show_ppi_request(struct device *dev,
> @@ -68,8 +64,10 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
>   {
>   	ssize_t size = -EINVAL;
>   	union acpi_object *obj;
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
>
> -	obj = tpm_eval_dsm(TPM_PPI_FN_GETREQ, ACPI_TYPE_PACKAGE, NULL);
> +	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETREQ,
> +			   ACPI_TYPE_PACKAGE, NULL);
>   	if (!obj)
>   		return -ENXIO;
>
> @@ -103,14 +101,15 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
>   	int func = TPM_PPI_FN_SUBREQ;
>   	union acpi_object *obj, tmp;
>   	union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
>
>   	/*
>   	 * the function to submit TPM operation request to pre-os environment
>   	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
>   	 * version 1.1
>   	 */
> -	if (acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
> -			   1 << TPM_PPI_FN_SUBREQ2))
> +	if (acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
> +			   TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_SUBREQ2))
>   		func = TPM_PPI_FN_SUBREQ2;
>
>   	/*
> @@ -119,7 +118,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
>   	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
>   	 * for compatibility, and use package type since 1.2 according to spec.
>   	 */
> -	if (strcmp(tpm_ppi_version, "1.2") < 0) {
> +	if (strcmp(chip->ppi_version, "1.2") < 0) {
>   		if (sscanf(buf, "%d", &req) != 1)
>   			return -EINVAL;
>   		argv4.type = ACPI_TYPE_BUFFER;
> @@ -131,7 +130,8 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
>   			return -EINVAL;
>   	}
>
> -	obj = tpm_eval_dsm(func, ACPI_TYPE_INTEGER, &argv4);
> +	obj = tpm_eval_dsm(chip->acpi_dev_handle, func, ACPI_TYPE_INTEGER,
> +			   &argv4);
>   	if (!obj) {
>   		return -ENXIO;
>   	} else {
> @@ -157,6 +157,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
>   		.buffer.length = 0,
>   		.buffer.pointer = NULL
>   	};
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
>
>   	static char *info[] = {
>   		"None",
> @@ -171,9 +172,10 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
>   	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
>   	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
>   	 */
> -	if (strcmp(tpm_ppi_version, "1.2") < 0)
> +	if (strcmp(chip->ppi_version, "1.2") < 0)
>   		obj = &tmp;
> -	obj = tpm_eval_dsm(TPM_PPI_FN_GETACT, ACPI_TYPE_INTEGER, obj);
> +	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETACT,
> +			   ACPI_TYPE_INTEGER, obj);
>   	if (!obj) {
>   		return -ENXIO;
>   	} else {
> @@ -196,8 +198,10 @@ static ssize_t tpm_show_ppi_response(struct device *dev,
>   	acpi_status status = -EINVAL;
>   	union acpi_object *obj, *ret_obj;
>   	u64 req, res;
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
>
> -	obj = tpm_eval_dsm(TPM_PPI_FN_GETRSP, ACPI_TYPE_PACKAGE, NULL);
> +	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETRSP,
> +			   ACPI_TYPE_PACKAGE, NULL);
>   	if (!obj)
>   		return -ENXIO;
>
> @@ -248,7 +252,8 @@ cleanup:
>   	return status;
>   }
>
> -static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
> +static ssize_t show_ppi_operations(acpi_handle dev_handle, char *buf, u32 start,
> +				   u32 end)
>   {
>   	int i;
>   	u32 ret;
> @@ -264,14 +269,15 @@ static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
>   		"User not required",
>   	};
>
> -	if (!acpi_check_dsm(tpm_ppi_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
> +	if (!acpi_check_dsm(dev_handle, tpm_ppi_uuid, TPM_PPI_REVISION_ID,
>   			    1 << TPM_PPI_FN_GETOPR))
>   		return -EPERM;
>
>   	tmp.integer.type = ACPI_TYPE_INTEGER;
>   	for (i = start; i <= end; i++) {
>   		tmp.integer.value = i;
> -		obj = tpm_eval_dsm(TPM_PPI_FN_GETOPR, ACPI_TYPE_INTEGER, &argv);
> +		obj = tpm_eval_dsm(dev_handle, TPM_PPI_FN_GETOPR,
> +				   ACPI_TYPE_INTEGER, &argv);
>   		if (!obj) {
>   			return -ENOMEM;
>   		} else {
> @@ -291,14 +297,20 @@ static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
>   					   struct device_attribute *attr,
>   					   char *buf)
>   {
> -	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
> +
> +	return show_ppi_operations(chip->acpi_dev_handle, buf, 0,
> +				   PPI_TPM_REQ_MAX);
>   }
>
>   static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
>   					  struct device_attribute *attr,
>   					  char *buf)
>   {
> -	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
> +	struct tpm_chip *chip = dev_get_drvdata(dev);
> +
> +	return show_ppi_operations(chip->acpi_dev_handle, buf, PPI_VS_REQ_START,
> +				   PPI_VS_REQ_END);
>   }
>
>   static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
> @@ -323,16 +335,34 @@ static struct attribute_group ppi_attr_grp = {
>   	.attrs = ppi_attrs
>   };
>
> -int tpm_add_ppi(struct kobject *parent)
> +int tpm_add_ppi(struct tpm_chip *chip)
>   {
> -	/* Cache TPM ACPI handle and version string */
> -	acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT, ACPI_UINT32_MAX,
> -			    ppi_callback, NULL, NULL, &tpm_ppi_handle);
> -	return tpm_ppi_handle ? sysfs_create_group(parent, &ppi_attr_grp) : 0;
> +	union acpi_object *obj;
> +
> +	if (!chip->acpi_dev_handle)
> +		return 0;
> +
> +	if (!acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
> +			    TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_VERSION))
> +		return 0;
> +
> +	/* Cache PPI version string. */
> +	obj = acpi_evaluate_dsm_typed(chip->acpi_dev_handle, tpm_ppi_uuid,
> +				      TPM_PPI_REVISION_ID, TPM_PPI_FN_VERSION,
> +				      NULL, ACPI_TYPE_STRING);
> +	if (!obj)
> +		return -ENOMEM;
> +
> +	strlcpy(chip->ppi_version, obj->string.pointer,
> +		PPI_VERSION_LEN + 1);

  sizeof(chip->ppi_version) would be better than PPI_VERSION_LEN + 1.

Rest looks ok to me.

     Stefan