[PATCH v23 4/5] fpga: m10bmc-sec: expose max10 canceled keys in sysfs

[Russ Weight]

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.

Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
Tested-by: Tianfei Zhang <tianfei.zhang@xxxxxxxxx>
Acked-by: Xu Yilun <yilun.xu@xxxxxxxxx>
Signed-off-by: Russ Weight <russell.h.weight@xxxxxxxxx>
---
v23:
  - Rebased for 5.19-rc1
v22:
  - Added Tested-by tag from Tianfei and Acked-by tag from Yilun.
  - Updated KernelVersion and Date in ABI documentation to 5.20 and
    Sep 2022 respectively.
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 6114e15885e5..0a41afe0ab4c 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:		Sep 2022
+KernelVersion:	5.20
+Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
+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:		Sep 2022
+KernelVersion:	5.20
+Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
+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:		Sep 2022
+KernelVersion:	5.20
+Contact:	Russ Weight <russell.h.weight@xxxxxxxxx>
+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:		Sep 2022
 KernelVersion:	5.20
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