Re: [PATCH v14 1/4] fpga: m10bmc-sec: create max10 bmc secure update driver

[Russ Weight]

On 9/10/21 8:13 AM, Xu Yilun wrote:
> On Thu, Sep 09, 2021 at 04:33:01PM -0700, Russ Weight wrote:
>> Create a sub driver for the FPGA Card BMC in order to support secure
>> updates.  This sub-driver will invoke an instance of the FPGA Image Load
>> class driver for the image load portion of the update.
>>
>> This patch creates the MAX10 BMC Secure Update driver and provides sysfs
>> files for displaying the current root entry hashes for the FPGA static
>> region, the FPGA PR region, and the MAX10 BMC.
>>
>> Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
>> Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
>> ---
>> v14:
>>   - Changed symbol and text references to reflect the renaming of the
>>     Security Manager Class driver to FPGA Image Load.
>> v13:
>>   - Updated copyright to 2021
>>   - Updated ABI documentation date and kernel version
>>   - Call updated fpga_sec_mgr_register() and fpga_sec_mgr_unregister()
>>     functions instead of devm_fpga_sec_mgr_create() and
>>     devm_fpga_sec_mgr_register().
>> v12:
>>   - Updated Date and KernelVersion fields in ABI documentation
>> v11:
>>   - Added Reviewed-by tag
>> v10:
>>   - Changed the path expressions in the sysfs documentation to
>>     replace the n3000 reference with something more generic to
>>     accomodate other devices that use the same driver.
>> v9:
>>   - Rebased to 5.12-rc2 next
>>   - Updated Date and KernelVersion in ABI documentation
>> v8:
>>   - Previously patch 2/6, otherwise no change
>> v7:
>>   - Updated Date and KernelVersion in ABI documentation
>> v6:
>>   - Added WARN_ON() call for (sha_num_bytes / stride) to assert
>>     that the proper count is passed to regmap_bulk_read().
>> v5:
>>   - No change
>> v4:
>>   - Moved sysfs files for displaying the root entry hashes (REH)
>>     from the FPGA Security Manager class driver to here. The
>>     m10bmc_reh() and m10bmc_reh_size() functions are removed and
>>     the functionality from these functions is moved into a
>>     show_root_entry_hash() function for displaying the REHs.
>>   - Added ABI documentation for the new sysfs entries:
>>     sysfs-driver-intel-m10-bmc-secure
>>   - Updated the MAINTAINERS file to add the new ABI documentation
>>     file: sysfs-driver-intel-m10-bmc-secure
>>   - Removed unnecessary ret variable from m10bmc_secure_probe()
>>   - Incorporated new devm_fpga_sec_mgr_register() function into
>>     m10bmc_secure_probe() and removed the m10bmc_secure_remove()
>>     function.
>> v3:
>>   - Changed from "Intel FPGA Security Manager" to FPGA Security Manager"
>>   - Changed: iops -> sops, imgr -> smgr, IFPGA_ -> FPGA_, ifpga_ to fpga_
>>   - Changed "MAX10 BMC Secure Engine driver" to "MAX10 BMC Secure
>>     Update driver"
>>   - Removed wrapper functions (m10bmc_raw_*, m10bmc_sys_*). The
>>     underlying functions are now called directly.
>>   - Changed "_root_entry_hash" to "_reh", with a comment explaining
>>     what reh is.
>> v2:
>>   - Added drivers/fpga/intel-m10-bmc-secure.c file to MAINTAINERS.
>>   - Switched to GENMASK(31, 16) for a couple of mask definitions.
>>   - Moved MAX10 BMC address and function definitions to a separate
>>     patch.
>>   - Replaced small function-creation macros with explicit function
>>     declarations.
>>   - Removed ifpga_sec_mgr_init() and ifpga_sec_mgr_uinit() functions.
>>   - Adapted to changes in the Intel FPGA Security Manager by splitting
>>     the single call to ifpga_sec_mgr_register() into two function
>>     calls: devm_ifpga_sec_mgr_create() and ifpga_sec_mgr_register().
>> ---
>>  .../testing/sysfs-driver-intel-m10-bmc-secure |  29 ++++
>>  MAINTAINERS                                   |   2 +
>>  drivers/fpga/Kconfig                          |  11 ++
>>  drivers/fpga/Makefile                         |   3 +
>>  drivers/fpga/intel-m10-bmc-secure.c           | 145 ++++++++++++++++++
>>  5 files changed, 190 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
>>  create mode 100644 drivers/fpga/intel-m10-bmc-secure.c
>>
>> diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
>> new file mode 100644
>> index 000000000000..363403ce992d
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
>> @@ -0,0 +1,29 @@
>> +What:		/sys/bus/platform/drivers/intel-m10bmc-secure/.../security/sr_root_entry_hash
>> +Date:		Aug 2021
>> +KernelVersion:	5.15
>> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
>> +Description:	Read only. Returns the root entry hash for the static
>> +		region if one is programmed, else it returns the
>> +		string: "hash not programmed".  This file is only
>> +		visible if the underlying device supports it.
>> +		Format: "0x%x".
>> +
>> +What:		/sys/bus/platform/drivers/intel-m10bmc-secure/.../security/pr_root_entry_hash
>> +Date:		Aug 2021
>> +KernelVersion:	5.15
>> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
>> +Description:	Read only. Returns the root entry hash for the partial
>> +		reconfiguration region if one is programmed, else it
>> +		returns the string: "hash not programmed".  This file
>> +		is only visible if the underlying device supports it.
>> +		Format: "0x%x".
>> +
>> +What:		/sys/bus/platform/drivers/intel-m10bmc-secure/.../security/bmc_root_entry_hash
>> +Date:		Aug 2021
>> +KernelVersion:	5.15
>> +Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
>> +Description:	Read only. Returns the root entry hash for the BMC image
>> +		if one is programmed, else it returns the string:
>> +		"hash not programmed".  This file is only visible if the
>> +		underlying device supports it.
>> +		Format: "0x%x".
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index e3fbc1bde9bc..cf93835b4775 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -7363,8 +7363,10 @@ M:	Russ Weight <russell.h.weight@xxxxxxxxx>
>>  L:	linux-fpga@xxxxxxxxxxxxxxx
>>  S:	Maintained
>>  F:	Documentation/ABI/testing/sysfs-class-fpga-image-load
>> +F:	Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-secure
> Should we change the name of the driver? Some keywords like "image load"
> or "firmware update" should be in the name.

I considered that. The image-upload functionality is a subset of  this
driver. It also exposes security collateral via sysfs, and the image-load
triggers and power-on-image sysfs files will probably end up in this
driver too.

The current driver name is intel-m10-bmc-secure. Do we need to keep
"intel-m10-bmc" in the name?

intel-m10-bmc-sec-fw-update?
intel-m10-bmc-sec-update?

What do you think? Any other suggestions?

- Russ
>
> Thanks,
> Yilun
>
>>  F:	Documentation/fpga/fpga-image-load.rst
>>  F:	drivers/fpga/fpga-image-load.c
>> +F:	drivers/fpga/intel-m10-bmc-secure.c
>>  F:	include/linux/fpga/fpga-image-load.h
>>  F:	include/uapi/linux/fpga-image-load.h
>>  
>> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
>> index c12a14e62fff..9d25b1ec03cd 100644
>> --- a/drivers/fpga/Kconfig
>> +++ b/drivers/fpga/Kconfig
>> @@ -253,4 +253,15 @@ config FPGA_IMAGE_LOAD
>>  	  and/or the device itself to authenticate and disposition the
>>  	  image data.
>>  
>> +config FPGA_M10_BMC_SECURE
>> +	tristate "Intel MAX10 BMC Secure Update driver"
>> +	depends on MFD_INTEL_M10_BMC && FPGA_IMAGE_LOAD
>> +	help
>> +	  Secure update support for the Intel MAX10 board management
>> +	  controller.
>> +
>> +	  This is a subdriver of the Intel MAX10 board management controller
>> +	  (BMC) and provides support for secure updates for the BMC image,
>> +	  the FPGA image, the Root Entry Hashes, etc.
>> +
>>  endif # FPGA
>> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
>> index adf228ee4f5e..8d4c1869ac4c 100644
>> --- a/drivers/fpga/Makefile
>> +++ b/drivers/fpga/Makefile
>> @@ -25,6 +25,9 @@ obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
>>  # FPGA Image Load Framework
>>  obj-$(CONFIG_FPGA_IMAGE_LOAD)		+= fpga-image-load.o
>>  
>> +# FPGA Secure Update Drivers
>> +obj-$(CONFIG_FPGA_M10_BMC_SECURE)	+= intel-m10-bmc-secure.o
>> +
>>  # FPGA Bridge Drivers
>>  obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
>>  obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)	+= altera-hps2fpga.o altera-fpga2sdram.o
>> diff --git a/drivers/fpga/intel-m10-bmc-secure.c b/drivers/fpga/intel-m10-bmc-secure.c
>> new file mode 100644
>> index 000000000000..03fc571f40f2
>> --- /dev/null
>> +++ b/drivers/fpga/intel-m10-bmc-secure.c
>> @@ -0,0 +1,145 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Intel Max10 Board Management Controller Secure Update Driver
>> + *
>> + * Copyright (C) 2019-2021 Intel Corporation. All rights reserved.
>> + *
>> + */
>> +#include <linux/bitfield.h>
>> +#include <linux/device.h>
>> +#include <linux/fpga/fpga-image-load.h>
>> +#include <linux/mfd/intel-m10-bmc.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +
>> +struct m10bmc_sec {
>> +	struct device *dev;
>> +	struct intel_m10bmc *m10bmc;
>> +	struct fpga_image_load *imgld;
>> +};
>> +
>> +/* Root Entry Hash (REH) support */
>> +#define REH_SHA256_SIZE		32
>> +#define REH_SHA384_SIZE		48
>> +#define REH_MAGIC		GENMASK(15, 0)
>> +#define REH_SHA_NUM_BYTES	GENMASK(31, 16)
>> +
>> +static ssize_t
>> +show_root_entry_hash(struct device *dev, u32 exp_magic,
>> +		     u32 prog_addr, u32 reh_addr, char *buf)
>> +{
>> +	struct m10bmc_sec *sec = dev_get_drvdata(dev);
>> +	unsigned int stride = regmap_get_reg_stride(sec->m10bmc->regmap);
>> +	int sha_num_bytes, i, cnt, ret;
>> +	u8 hash[REH_SHA384_SIZE];
>> +	u32 magic;
>> +
>> +	ret = m10bmc_raw_read(sec->m10bmc, prog_addr, &magic);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(dev, "%s magic 0x%08x\n", __func__, magic);
>> +
>> +	if (FIELD_GET(REH_MAGIC, magic) != exp_magic)
>> +		return sysfs_emit(buf, "hash not programmed\n");
>> +
>> +	sha_num_bytes = FIELD_GET(REH_SHA_NUM_BYTES, magic) / 8;
>> +	if (sha_num_bytes != REH_SHA256_SIZE &&
>> +	    sha_num_bytes != REH_SHA384_SIZE)   {
>> +		dev_err(sec->dev, "%s bad sha num bytes %d\n", __func__,
>> +			sha_num_bytes);
>> +		return -EINVAL;
>> +	}
>> +
>> +	WARN_ON(sha_num_bytes % stride);
>> +	ret = regmap_bulk_read(sec->m10bmc->regmap, reh_addr,
>> +			       hash, sha_num_bytes / stride);
>> +	if (ret) {
>> +		dev_err(dev, "failed to read root entry hash: %x cnt %x: %d\n",
>> +			reh_addr, sha_num_bytes / stride, ret);
>> +		return ret;
>> +	}
>> +
>> +	cnt = sprintf(buf, "0x");
>> +	for (i = 0; i < sha_num_bytes; i++)
>> +		cnt += sprintf(buf + cnt, "%02x", hash[i]);
>> +	cnt += sprintf(buf + cnt, "\n");
>> +
>> +	return cnt;
>> +}
>> +
>> +#define DEVICE_ATTR_SEC_REH_RO(_name, _magic, _prog_addr, _reh_addr) \
>> +static ssize_t _name##_root_entry_hash_show(struct device *dev, \
>> +					    struct device_attribute *attr, \
>> +					    char *buf) \
>> +{ return show_root_entry_hash(dev, _magic, _prog_addr, _reh_addr, buf); } \
>> +static DEVICE_ATTR_RO(_name##_root_entry_hash)
>> +
>> +DEVICE_ATTR_SEC_REH_RO(bmc, BMC_PROG_MAGIC, BMC_PROG_ADDR, BMC_REH_ADDR);
>> +DEVICE_ATTR_SEC_REH_RO(sr, SR_PROG_MAGIC, SR_PROG_ADDR, SR_REH_ADDR);
>> +DEVICE_ATTR_SEC_REH_RO(pr, PR_PROG_MAGIC, PR_PROG_ADDR, PR_REH_ADDR);
>> +
>> +static struct attribute *m10bmc_security_attrs[] = {
>> +	&dev_attr_bmc_root_entry_hash.attr,
>> +	&dev_attr_sr_root_entry_hash.attr,
>> +	&dev_attr_pr_root_entry_hash.attr,
>> +	NULL,
>> +};
>> +
>> +static struct attribute_group m10bmc_security_attr_group = {
>> +	.name = "security",
>> +	.attrs = m10bmc_security_attrs,
>> +};
>> +
>> +static const struct attribute_group *m10bmc_sec_attr_groups[] = {
>> +	&m10bmc_security_attr_group,
>> +	NULL,
>> +};
>> +
>> +static const struct fpga_image_load_ops m10bmc_lops = { };
>> +
>> +static int m10bmc_secure_probe(struct platform_device *pdev)
>> +{
>> +	struct fpga_image_load *imgld;
>> +	struct m10bmc_sec *sec;
>> +
>> +	sec = devm_kzalloc(&pdev->dev, sizeof(*sec), GFP_KERNEL);
>> +	if (!sec)
>> +		return -ENOMEM;
>> +
>> +	sec->dev = &pdev->dev;
>> +	sec->m10bmc = dev_get_drvdata(pdev->dev.parent);
>> +	dev_set_drvdata(&pdev->dev, sec);
>> +
>> +	imgld = fpga_image_load_register(sec->dev, &m10bmc_lops, sec);
>> +	if (IS_ERR(imgld)) {
>> +		dev_err(sec->dev, "FPGA Image Load driver failed to start\n");
>> +		return PTR_ERR(imgld);
>> +	}
>> +
>> +	sec->imgld = imgld;
>> +	return 0;
>> +}
>> +
>> +static int m10bmc_secure_remove(struct platform_device *pdev)
>> +{
>> +	struct m10bmc_sec *sec = dev_get_drvdata(&pdev->dev);
>> +
>> +	fpga_image_load_unregister(sec->imgld);
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver intel_m10bmc_secure_driver = {
>> +	.probe = m10bmc_secure_probe,
>> +	.remove = m10bmc_secure_remove,
>> +	.driver = {
>> +		.name = "n3000bmc-secure",
>> +		.dev_groups = m10bmc_sec_attr_groups,
>> +	},
>> +};
>> +module_platform_driver(intel_m10bmc_secure_driver);
>> +
>> +MODULE_ALIAS("platform:n3000bmc-secure");
>> +MODULE_AUTHOR("Intel Corporation");
>> +MODULE_DESCRIPTION("Intel MAX10 BMC Secure Update");
>> +MODULE_LICENSE("GPL v2");
>> -- 
>> 2.25.1