Re: [PATCH v6 1/7] fpga: sec-mgr: fpga security manager class driver

[Moritz Fischer <mdf@kernel.org>]

Hi Russ,

On Thu, Nov 05, 2020 at 05:08:59PM -0800, Russ Weight wrote:
> Create the FPGA Security Manager class driver. The security
> manager provides interfaces to manage secure updates for the
> FPGA and BMC images that are stored in FLASH. The driver can
> also be used to update root entry hashes and to cancel code
> signing keys. The image type is encoded in the image file
> and is decoded by the HW/FW secure update engine.
> 
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> Reviewed-by: Tom Rix <trix@redhat.com>
> ---
> v6:
>   - Removed sysfs support and documentation for the display of the
>     flash count, root entry hashes, and code-signing-key cancelation
>     vectors.
> v5:
>   - Added the devm_fpga_sec_mgr_unregister() function, following recent
>     changes to the fpga_manager() implementation.
>   - Changed some *_show() functions to use sysfs_emit() instead of sprintf(
> v4:
>   - Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
>     and removed unnecessary references to "Intel".
>   - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
> v3:
>   - Modified sysfs handler check in check_sysfs_handler() to make
>     it more readable.
> v2:
>   - Bumped documentation dates and versions
>   - Added Documentation/fpga/ifpga-sec-mgr.rst 
>   - Removed references to bmc_flash_count & smbus_flash_count (not supported)
>   - Split ifpga_sec_mgr_register() into create() and register() functions
>   - Added devm_ifpga_sec_mgr_create()
>   - Removed typedefs for imgr ops
> ---
>  .../ABI/testing/sysfs-class-fpga-sec-mgr      |   5 +
>  Documentation/fpga/fpga-sec-mgr.rst           |  44 +++
>  Documentation/fpga/index.rst                  |   1 +
>  MAINTAINERS                                   |   9 +
>  drivers/fpga/Kconfig                          |   9 +
>  drivers/fpga/Makefile                         |   3 +
>  drivers/fpga/fpga-sec-mgr.c                   | 296 ++++++++++++++++++
>  include/linux/fpga/fpga-sec-mgr.h             |  44 +++
>  8 files changed, 411 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
>  create mode 100644 Documentation/fpga/fpga-sec-mgr.rst
>  create mode 100644 drivers/fpga/fpga-sec-mgr.c
>  create mode 100644 include/linux/fpga/fpga-sec-mgr.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> new file mode 100644
> index 000000000000..ecda22a3ff3b
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> @@ -0,0 +1,5 @@
> +What: 		/sys/class/fpga_sec_mgr/fpga_secX/name
> +Date:		Oct 2020
> +KernelVersion:  5.11
> +Contact:	Russ Weight <russell.h.weight@intel.com>
> +Description:	Name of low level fpga security manager driver.
> diff --git a/Documentation/fpga/fpga-sec-mgr.rst b/Documentation/fpga/fpga-sec-mgr.rst
> new file mode 100644
> index 000000000000..26dac599ead7
> --- /dev/null
> +++ b/Documentation/fpga/fpga-sec-mgr.rst
> @@ -0,0 +1,44 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +========================================
> +FPGA Security Manager Class Driver
> +========================================
> +
> +The FPGA Security Manager class driver provides a common
> +API for user-space tools to manage updates for secure FPGA
> +devices. Device drivers that instantiate the Security
> +Manager class driver will interact with a HW secure update
> +engine in order to transfer new FPGA and BMC images to FLASH so
> +that they will be automatically loaded when the FPGA card reboots.
> +
> +A significant difference between the FPGA Manager and the FPGA
> +Security Manager is that the FPGA Manager does a live update (Partial
> +Reconfiguration) to a device, whereas the FPGA Security Manager
> +updates the FLASH images for the Static Region and the BMC so that
> +they will be loaded the next time the FPGA card boots. Security is
> +enforced by hardware and firmware. The security manager interacts
> +with the firmware to initiate an update, pass in the necessary data,
> +and collect status on the update.

I've always wondered if we could've made this a functionality of an FPGA
manager 'non-volatile' node or something.

I guess there might be cases where you can only do either of them, i.e.
only update flash or only update at runtime.

> +
> +In addition to managing secure updates of the FPGA and BMC images,
> +the FPGA Security Manager update process may also used to
> +program root entry hashes and cancellation keys for the FPGA static
> +region, the FPGA partial reconfiguration region, and the BMC.
> +
> +Secure updates make use of the request_firmware framework, which
> +requires that image files are accessible under /lib/firmware. A request
> +for a secure update returns immediately, while the update itself
> +proceeds in the context of a kernel worker thread. Sysfs files provide
> +a means for monitoring the progress of a secure update and for
> +retrieving error information in the event of a failure.
> +
> +Sysfs Attributes
> +================
> +
> +The API includes a sysfs entry *name* to export the name of the parent
> +driver. It also includes an *update* sub-directory that can be used to
> +instantiate and monitor a secure update.
> +
> +See `<../ABI/testing/sysfs-class-fpga-sec-mgr>`__ for a full
> +description of the sysfs attributes for the FPGA Security
> +Manager.
> diff --git a/Documentation/fpga/index.rst b/Documentation/fpga/index.rst
> index f80f95667ca2..0b2f427042af 100644
> --- a/Documentation/fpga/index.rst
> +++ b/Documentation/fpga/index.rst
> @@ -8,6 +8,7 @@ fpga
>      :maxdepth: 1
>  
>      dfl
> +    fpga-sec-mgr
>  
>  .. only::  subproject and html
>  
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 87452fca5235..a434cd1921f7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6919,6 +6919,15 @@ F:	Documentation/fpga/
>  F:	drivers/fpga/
>  F:	include/linux/fpga/
>  
> +FPGA SECURITY MANAGER DRIVERS
> +M:	Russ Weight <russell.h.weight@intel.com>
> +L:	linux-fpga@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
> +F:	Documentation/fpga/fpga-sec-mgr.rst
> +F:	drivers/fpga/fpga-sec-mgr.c
> +F:	include/linux/fpga/fpga-sec-mgr.h
> +
>  FPU EMULATOR
>  M:	Bill Metzenthen <billm@melbpc.org.au>
>  S:	Maintained
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index 7cd5a29fc437..6810b23b178d 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -215,4 +215,13 @@ config FPGA_MGR_ZYNQMP_FPGA
>  	  to configure the programmable logic(PL) through PS
>  	  on ZynqMP SoC.
>  
> +config FPGA_SEC_MGR
> +	tristate "FPGA Security Manager"
> +	help
> +	  The Security Manager class driver presents a common
> +	  user API for managing secure updates for FPGA
> +	  devices, including flash images for the FPGA static
> +	  region and for the BMC. Select this option to enable
> +	  updates for secure FPGA devices.
> +
>  endif # FPGA
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index d8e21dfc6778..0e357262faed 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -21,6 +21,9 @@ obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE)         += altera-pr-ip-core.o
>  obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
>  
> +# FPGA Security Manager Framework
> +obj-$(CONFIG_FPGA_SEC_MGR)		+= fpga-sec-mgr.o
> +
>  # FPGA Bridge Drivers
>  obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
>  obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)	+= altera-hps2fpga.o altera-fpga2sdram.o
> diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
> new file mode 100644
> index 000000000000..468379e0c825
> --- /dev/null
> +++ b/drivers/fpga/fpga-sec-mgr.c
> @@ -0,0 +1,296 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * FPGA Security Manager
> + *
> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> + */
> +
> +#include <linux/fpga/fpga-sec-mgr.h>
> +#include <linux/idr.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/vmalloc.h>
> +
> +static DEFINE_IDA(fpga_sec_mgr_ida);
> +static struct class *fpga_sec_mgr_class;
> +
> +struct fpga_sec_mgr_devres {
> +	struct fpga_sec_mgr *smgr;
> +};
> +
> +#define to_sec_mgr(d) container_of(d, struct fpga_sec_mgr, dev)
> +
> +static ssize_t name_show(struct device *dev,
> +			 struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
> +
> +	return sysfs_emit(buf, "%s\n", smgr->name);
> +}
> +static DEVICE_ATTR_RO(name);
> +
> +static struct attribute *sec_mgr_attrs[] = {
> +	&dev_attr_name.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group sec_mgr_attr_group = {
> +	.attrs = sec_mgr_attrs,
> +};
> +
> +static const struct attribute_group *fpga_sec_mgr_attr_groups[] = {
> +	&sec_mgr_attr_group,
> +	NULL,
> +};
> +
> +/**
> + * fpga_sec_mgr_create - create and initialize an FPGA
> + *			  security manager struct
> + *
> + * @dev:  fpga security manager device from pdev
> + * @name: fpga security manager name
> + * @sops: pointer to a structure of fpga callback functions
> + * @priv: fpga security manager private data
> + *
> + * The caller of this function is responsible for freeing the struct
> + * with ifpg_sec_mgr_free(). Using devm_fpga_sec_mgr_create() instead
> + * is recommended.
> + *
> + * Return: pointer to struct fpga_sec_mgr or NULL
> + */
> +struct fpga_sec_mgr *
> +fpga_sec_mgr_create(struct device *dev, const char *name,
> +		    const struct fpga_sec_mgr_ops *sops, void *priv)
> +{
> +	struct fpga_sec_mgr *smgr;
> +	int id, ret;
> +
> +	if (!name || !strlen(name)) {
> +		dev_err(dev, "Attempt to register with no name!\n");
> +		return NULL;
> +	}
> +
> +	smgr = kzalloc(sizeof(*smgr), GFP_KERNEL);
> +	if (!smgr)
> +		return NULL;
> +
> +	id = ida_simple_get(&fpga_sec_mgr_ida, 0, 0, GFP_KERNEL);
> +	if (id < 0)
> +		goto error_kfree;
> +
> +	mutex_init(&smgr->lock);
> +
> +	smgr->name = name;
> +	smgr->priv = priv;
> +	smgr->sops = sops;
> +
> +	device_initialize(&smgr->dev);
> +	smgr->dev.class = fpga_sec_mgr_class;
> +	smgr->dev.parent = dev;
> +	smgr->dev.id = id;
> +
> +	ret = dev_set_name(&smgr->dev, "fpga_sec%d", id);
> +	if (ret) {
> +		dev_err(dev, "Failed to set device name: fpga_sec%d\n", id);
> +		goto error_device;
> +	}
> +
> +	return smgr;
> +
> +error_device:
> +	ida_simple_remove(&fpga_sec_mgr_ida, id);
> +
> +error_kfree:
> +	kfree(smgr);
> +
> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_create);
> +
> +/**
> + * fpga_sec_mgr_free - free an FPGA security manager created
> + *			with fpga_sec_mgr_create()
> + *
> + * @smgr:	FPGA security manager structure
> + */
> +void fpga_sec_mgr_free(struct fpga_sec_mgr *smgr)
> +{
> +	ida_simple_remove(&fpga_sec_mgr_ida, smgr->dev.id);
> +	kfree(smgr);
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_free);
> +
> +static void devm_fpga_sec_mgr_release(struct device *dev, void *res)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	fpga_sec_mgr_free(dr->smgr);
> +}
> +
> +/**
> + * devm_fpga_sec_mgr_create - create and initialize an FPGA
> + *			       security manager struct
> + *
> + * @dev:  fpga security manager device from pdev
> + * @name: fpga security manager name
> + * @sops: pointer to a structure of fpga callback functions
> + * @priv: fpga security manager private data
> + *
> + * This function is intended for use in a FPGA Security manager
> + * driver's probe function.  After the security manager driver creates
> + * the fpga_sec_mgr struct with devm_fpga_sec_mgr_create(), it should
> + * register it with devm_fpga_sec_mgr_register().
> + * The fpga_sec_mgr struct allocated with this function will be freed
> + * automatically on driver detach.
> + *
> + * Return: pointer to struct fpga_sec_mgr or NULL
> + */
> +struct fpga_sec_mgr *
> +devm_fpga_sec_mgr_create(struct device *dev, const char *name,
> +			 const struct fpga_sec_mgr_ops *sops, void *priv)
> +{
> +	struct fpga_sec_mgr_devres *dr;
> +
> +	dr = devres_alloc(devm_fpga_sec_mgr_release, sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return NULL;
> +
> +	dr->smgr = fpga_sec_mgr_create(dev, name, sops, priv);
> +	if (!dr->smgr) {
> +		devres_free(dr);
> +		return NULL;
> +	}
> +
> +	devres_add(dev, dr);
> +
> +	return dr->smgr;
> +}
> +EXPORT_SYMBOL_GPL(devm_fpga_sec_mgr_create);
> +
> +/**
> + * fpga_sec_mgr_register - register an FPGA security manager
> + *
> + * @smgr: fpga security manager struct
> + *
> + * Return: 0 on success, negative error code otherwise.
> + */
> +int fpga_sec_mgr_register(struct fpga_sec_mgr *smgr)
> +{
> +	int ret;
> +
> +	ret = device_add(&smgr->dev);
> +	if (ret)
> +		goto error_device;
> +
> +	dev_info(&smgr->dev, "%s registered\n", smgr->name);
> +
> +	return 0;
> +
> +error_device:
> +	ida_simple_remove(&fpga_sec_mgr_ida, smgr->dev.id);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_register);
> +
> +/**
> + * fpga_sec_mgr_unregister - unregister an FPGA security manager
> + *
> + * @mgr: fpga manager struct
> + *
> + * This function is intended for use in an FPGA security manager
> + * driver's remove() function.
> + */
> +void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr)
> +{
> +	dev_info(&smgr->dev, "%s %s\n", __func__, smgr->name);
> +
> +	device_unregister(&smgr->dev);
> +}
> +EXPORT_SYMBOL_GPL(fpga_sec_mgr_unregister);
> +
> +static int fpga_sec_mgr_devres_match(struct device *dev, void *res,
> +				     void *match_data)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	return match_data == dr->smgr;
> +}
> +
> +static void devm_fpga_sec_mgr_unregister(struct device *dev, void *res)
> +{
> +	struct fpga_sec_mgr_devres *dr = res;
> +
> +	fpga_sec_mgr_unregister(dr->smgr);
> +}
> +
> +/**
> + * devm_fpga_sec_mgr_register - resource managed variant of
> + *				fpga_sec_mgr_register()
> + *
> + * @dev: managing device for this FPGA security manager
> + * @smgr: fpga security manager struct
> + *
> + * This is the devres variant of fpga_sec_mgr_register() for which the
> + * unregister function will be called automatically when the managing
> + * device is detached.
> + */
> +int devm_fpga_sec_mgr_register(struct device *dev, struct fpga_sec_mgr *smgr)
> +{
> +	struct fpga_sec_mgr_devres *dr;
> +	int ret;
> +
> +	/*
> +	 * Make sure that the struct fpga_sec_mgr * that is passed in is
> +	 * managed itself.
> +	 */
> +	if (WARN_ON(!devres_find(dev, devm_fpga_sec_mgr_release,
> +				 fpga_sec_mgr_devres_match, smgr)))
> +		return -EINVAL;
> +
> +	dr = devres_alloc(devm_fpga_sec_mgr_unregister, sizeof(*dr), GFP_KERNEL);
> +	if (!dr)
> +		return -ENOMEM;
> +
> +	ret = fpga_sec_mgr_register(smgr);
> +	if (ret) {
> +		devres_free(dr);
> +		return ret;
> +	}
> +
> +	dr->smgr = smgr;
> +	devres_add(dev, dr);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(devm_fpga_sec_mgr_register);
> +
> +static void fpga_sec_mgr_dev_release(struct device *dev)
> +{
> +}
> +
> +static int __init fpga_sec_mgr_class_init(void)
> +{
> +	pr_info("FPGA Security Manager\n");
> +
> +	fpga_sec_mgr_class = class_create(THIS_MODULE, "fpga_sec_mgr");
> +	if (IS_ERR(fpga_sec_mgr_class))
> +		return PTR_ERR(fpga_sec_mgr_class);
> +
> +	fpga_sec_mgr_class->dev_groups = fpga_sec_mgr_attr_groups;
> +	fpga_sec_mgr_class->dev_release = fpga_sec_mgr_dev_release;
> +
> +	return 0;
> +}
> +
> +static void __exit fpga_sec_mgr_class_exit(void)
> +{
> +	class_destroy(fpga_sec_mgr_class);
> +	ida_destroy(&fpga_sec_mgr_ida);
> +}
> +
> +MODULE_DESCRIPTION("FPGA Security Manager Driver");
> +MODULE_LICENSE("GPL v2");
> +
> +subsys_initcall(fpga_sec_mgr_class_init);
> +module_exit(fpga_sec_mgr_class_exit)
> diff --git a/include/linux/fpga/fpga-sec-mgr.h b/include/linux/fpga/fpga-sec-mgr.h
> new file mode 100644
> index 000000000000..f85665b79b9d
> --- /dev/null
> +++ b/include/linux/fpga/fpga-sec-mgr.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Header file for FPGA Security Manager
> + *
> + * Copyright (C) 2019-2020 Intel Corporation, Inc.
> + */
> +#ifndef _LINUX_FPGA_SEC_MGR_H
> +#define _LINUX_FPGA_SEC_MGR_H
> +
> +#include <linux/device.h>
> +#include <linux/mutex.h>
> +#include <linux/types.h>
> +
> +struct fpga_sec_mgr;
> +
> +/**
> + * struct fpga_sec_mgr_ops - device specific operations
> + */
> +struct fpga_sec_mgr_ops {
> +};
> +
> +struct fpga_sec_mgr {
> +	const char *name;
> +	struct device dev;
> +	const struct fpga_sec_mgr_ops *sops;
> +	struct mutex lock;		/* protect data structure contents */
> +	void *priv;
> +};
> +
> +struct fpga_sec_mgr *
> +fpga_sec_mgr_create(struct device *dev, const char *name,
> +		    const struct fpga_sec_mgr_ops *sops, void *priv);
> +
> +struct fpga_sec_mgr *
> +devm_fpga_sec_mgr_create(struct device *dev, const char *name,
> +			 const struct fpga_sec_mgr_ops *sops, void *priv);
> +
> +int fpga_sec_mgr_register(struct fpga_sec_mgr *smgr);
> +int devm_fpga_sec_mgr_register(struct device *dev,
> +			       struct fpga_sec_mgr *smgr);
> +void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr);
> +void fpga_sec_mgr_free(struct fpga_sec_mgr *smgr);
> +
> +#endif
> -- 
> 2.25.1
> 
Looks good to me otherwise, let me look at the rest of the series,

Moritz