Re: [PATCH v21 4/5] fpga: m10bmc-sec: expose max10 canceled keys in sysfs

[Xu Yilun <yilun.xu@intel.com>]

On Fri, May 20, 2022 at 05:36:06PM -0700, Russ Weight wrote:
> Extend the MAX10 BMC Secure Update driver to provide sysfs files to
> expose the 128 bit code signing key (CSK) cancellation vectors. These use
> the standard bitmap list format (e.g. 1,2-6,9).
> 
> Each CSK is assigned an ID, a number between 0-127, during the signing
> process. CSK ID cancellation information is stored in 128-bit fields in
> write-once locations in flash.  The cancellation of a CSK can be used
> to prevent the card from being rolled back to older images that were
> signed with a CSK that is now cancelled.
> 
> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> Reviewed-by: Tom Rix <trix@redhat.com>

Acked-by: Xu Yilun <yilun.xu@intel.com>

> ---
> v21:
>   - Replace WARN_ON(size % stride) with a more elaborate test. Return
>     -EINVAL and write a message to the kernel log. Call WARN_ON_ONCE().
> v20:
>   - Added text to the commit message to further describe the cancellation of
>     code signing keys.
> v19:
>   - Change "card bmc" naming back to "m10 bmc" naming to be consistent
>     with the parent driver.
> v18:
>   - No change
> v17:
>   - Update the Date and KernelVersion for the ABI documentation to Jul 2022
>     and 5.19 respectively.
>   - Change "m10bmc" in symbol names to "cardbmc" to reflect the fact that the
>     future devices will not necessarily use the MAX10.
> v16:
>   - No Change
> v15:
>   - Updated the Dates and KernelVersions in the ABI documentation
> v14:
>   - No changes
> v13:
>   - Updated ABI documentation date and kernel version
> v12:
>   - Updated Date and KernelVersion fields in ABI documentation
> v11:
>   - No change
> 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 4/6, otherwise no change
> v7:
>   - Updated Date and KernelVersion in ABI documentation
> v6:
>   - Added WARN_ON() call for (size / stride) to ensure
>     that the proper count is passed to regmap_bulk_read().
> v5:
>   - No change
> v4:
>   - Moved sysfs files for displaying the code-signing-key (CSK)
>     cancellation vectors from the FPGA Security Manger class driver
>     to here. The m10bmc_csk_vector() and m10bmc_csk_cancel_nbits()
>     functions are removed and the functionality from these functions
>     is moved into a show_canceled_csk() function for for displaying
>     the CSK vectors.
>   - Added ABI documentation for new sysfs entries
> v3:
>   - 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.
>   - Renamed get_csk_vector() to m10bmc_csk_vector()
> v2:
>   - Replaced small function-creation macros for explicit function
>     declarations.
>   - Fixed get_csk_vector() function to properly apply the stride
>     variable in calls to m10bmc_raw_bulk_read()
>   - Added m10bmc_ prefix to functions in m10bmc_iops structure
> ---
>  .../sysfs-driver-intel-m10-bmc-sec-update     | 24 +++++++++
>  drivers/fpga/intel-m10-bmc-sec-update.c       | 54 +++++++++++++++++++
>  2 files changed, 78 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> index 1132e39b2125..ca5a34c1c31f 100644
> --- a/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> +++ b/Documentation/ABI/testing/sysfs-driver-intel-m10-bmc-sec-update
> @@ -28,6 +28,30 @@ Description:	Read only. Returns the root entry hash for the BMC image
>  		underlying device supports it.
>  		Format: string.
>  
> +What:		/sys/bus/platform/drivers/intel-m10bmc-sec-update/.../security/sr_canceled_csks
> +Date:		Jul 2022
> +KernelVersion:	5.19
> +Contact:	Russ Weight <russell.h.weight@intel.com>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the static region. The standard bitmap
> +		list format is used (e.g. "1,2-6,9").
> +
> +What:		/sys/bus/platform/drivers/intel-m10bmc-sec-update/.../security/pr_canceled_csks
> +Date:		Jul 2022
> +KernelVersion:	5.19
> +Contact:	Russ Weight <russell.h.weight@intel.com>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the partial reconfiguration region. The
> +		standard bitmap list format is used (e.g. "1,2-6,9").
> +
> +What:		/sys/bus/platform/drivers/intel-m10bmc-sec-update/.../security/bmc_canceled_csks
> +Date:		Jul 2022
> +KernelVersion:	5.19
> +Contact:	Russ Weight <russell.h.weight@intel.com>
> +Description:	Read only. Returns a list of indices for canceled code
> +		signing keys for the BMC.  The standard bitmap list format
> +		is used (e.g. "1,2-6,9").
> +
>  What:		/sys/bus/platform/drivers/intel-m10bmc-sec-update/.../security/flash_count
>  Date:		Jul 2022
>  KernelVersion:	5.19
> diff --git a/drivers/fpga/intel-m10-bmc-sec-update.c b/drivers/fpga/intel-m10-bmc-sec-update.c
> index 25b21f116976..65fec2a70901 100644
> --- a/drivers/fpga/intel-m10-bmc-sec-update.c
> +++ b/drivers/fpga/intel-m10-bmc-sec-update.c
> @@ -78,6 +78,57 @@ 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);
>  
> +#define CSK_BIT_LEN		128U
> +#define CSK_32ARRAY_SIZE	DIV_ROUND_UP(CSK_BIT_LEN, 32)
> +
> +static ssize_t
> +show_canceled_csk(struct device *dev, u32 addr, char *buf)
> +{
> +	unsigned int i, stride, size = CSK_32ARRAY_SIZE * sizeof(u32);
> +	struct m10bmc_sec *sec = dev_get_drvdata(dev);
> +	DECLARE_BITMAP(csk_map, CSK_BIT_LEN);
> +	__le32 csk_le32[CSK_32ARRAY_SIZE];
> +	u32 csk32[CSK_32ARRAY_SIZE];
> +	int ret;
> +
> +	stride = regmap_get_reg_stride(sec->m10bmc->regmap);
> +	if (size % stride) {
> +		dev_err(sec->dev,
> +			"CSK vector size (0x%x) not aligned to stride (0x%x)\n",
> +			size, stride);
> +		WARN_ON_ONCE(1);
> +		return -EINVAL;
> +	}
> +
> +	ret = regmap_bulk_read(sec->m10bmc->regmap, addr, csk_le32,
> +			       size / stride);
> +	if (ret) {
> +		dev_err(sec->dev, "failed to read CSK vector: %x cnt %x: %d\n",
> +			addr, size / stride, ret);
> +		return ret;
> +	}
> +
> +	for (i = 0; i < CSK_32ARRAY_SIZE; i++)
> +		csk32[i] = le32_to_cpu(((csk_le32[i])));
> +
> +	bitmap_from_arr32(csk_map, csk32, CSK_BIT_LEN);
> +	bitmap_complement(csk_map, csk_map, CSK_BIT_LEN);
> +	return bitmap_print_to_pagebuf(1, buf, csk_map, CSK_BIT_LEN);
> +}
> +
> +#define DEVICE_ATTR_SEC_CSK_RO(_name, _addr) \
> +static ssize_t _name##_canceled_csks_show(struct device *dev, \
> +					  struct device_attribute *attr, \
> +					  char *buf) \
> +{ return show_canceled_csk(dev, _addr, buf); } \
> +static DEVICE_ATTR_RO(_name##_canceled_csks)
> +
> +#define CSK_VEC_OFFSET 0x34
> +
> +DEVICE_ATTR_SEC_CSK_RO(bmc, BMC_PROG_ADDR + CSK_VEC_OFFSET);
> +DEVICE_ATTR_SEC_CSK_RO(sr, SR_PROG_ADDR + CSK_VEC_OFFSET);
> +DEVICE_ATTR_SEC_CSK_RO(pr, PR_PROG_ADDR + CSK_VEC_OFFSET);
> +
>  #define FLASH_COUNT_SIZE 4096	/* count stored as inverted bit vector */
>  
>  static ssize_t flash_count_show(struct device *dev,
> @@ -125,6 +176,9 @@ 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,
> +	&dev_attr_sr_canceled_csks.attr,
> +	&dev_attr_pr_canceled_csks.attr,
> +	&dev_attr_bmc_canceled_csks.attr,
>  	NULL,
>  };
>  
> -- 
> 2.25.1