[v14,6/6] fpga: sec-mgr: enable cancel of secure update

Commit Message

Russ Weight July 27, 2021, 10:31 p.m. UTC

Extend the FPGA Security Manager class driver to include
an update/cancel sysfs file that can be written to request
that an update be canceled. The write may return EBUSY if
the update has progressed to the point that it cannot be
canceled by software or ENODEV if there is no update in
progress.

Signed-off-by: Russ Weight <[e-mail]>
Reviewed-by: Tom Rix <[e-mail]>
---
v14:
 - Updated ABI documentation date and kernel version
v13:
  - No change
v12:
  - Updated Date and KernelVersion fields in ABI documentation
v11:
  - No change
v10:
  - Rebased to 5.12-rc2 next
  - Updated Date and KernelVersion in ABI documentation
v9:
  - Updated Date and KernelVersion in ABI documentation
v8:
  - No change
v7:
  - Changed Date in documentation file to December 2020
v6:
  - No change
v5:
  - No change
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:
  - No change
v2:
  - Bumped documentation date and version
  - Minor code cleanup per review comments
---
 .../ABI/testing/sysfs-class-fpga-sec-mgr      | 10 ++++
 drivers/fpga/fpga-sec-mgr.c                   | 59 +++++++++++++++++--
 include/linux/fpga/fpga-sec-mgr.h             |  1 +
 3 files changed, 66 insertions(+), 4 deletions(-)

Patch

diff --git a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
index fc91c4341cee..25d01dbb34fc 100644
--- a/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
+++ b/Documentation/ABI/testing/sysfs-class-fpga-sec-mgr
@@ -11,6 +11,16 @@  Description:	Write only. Write the filename of an image
 		and Root Entry Hashes, and to cancel Code Signing
 		Keys (CSK).
 
+What: 		/sys/class/fpga_sec_mgr/fpga_secX/update/cancel
+Date:		Aug 2021
+KernelVersion:	5.15
+Contact:	Russ Weight <[e-mail]>
+Description:	Write-only. Write a "1" to this file to request
+		that a current update be canceled. This request
+		will be rejected (EBUSY) if the programming phase
+		has already started or (ENODEV) if there is no
+		update in progress.
+
 What: 		/sys/class/fpga_sec_mgr/fpga_secX/update/status
 Date:		Aug 2021
 KernelVersion:	5.15
diff --git a/drivers/fpga/fpga-sec-mgr.c b/drivers/fpga/fpga-sec-mgr.c
index 7acf712134dc..fd6f7e730a32 100644
--- a/drivers/fpga/fpga-sec-mgr.c
+++ b/drivers/fpga/fpga-sec-mgr.c
@@ -40,6 +40,23 @@  static void fpga_sec_dev_error(struct fpga_sec_mgr *smgr,
 	smgr->sops->cancel(smgr);
 }
 
+static int progress_transition(struct fpga_sec_mgr *smgr,
+			       enum fpga_sec_prog new_progress)
+{
+	int ret = 0;
+
+	mutex_lock(&smgr->lock);
+	if (smgr->request_cancel) {
+		fpga_sec_set_error(smgr, FPGA_SEC_ERR_CANCELED);
+		smgr->sops->cancel(smgr);
+		ret = -ECANCELED;
+	} else {
+		update_progress(smgr, new_progress);
+	}
+	mutex_unlock(&smgr->lock);
+	return ret;
+}
+
 static void progress_complete(struct fpga_sec_mgr *smgr)
 {
 	mutex_lock(&smgr->lock);
@@ -71,15 +88,19 @@  static void fpga_sec_mgr_update(struct work_struct *work)
 		goto release_fw_exit;
 	}
 
-	update_progress(smgr, FPGA_SEC_PROG_PREPARING);
+	if (progress_transition(smgr, FPGA_SEC_PROG_PREPARING))
+		goto modput_exit;
+
 	ret = smgr->sops->prepare(smgr);
 	if (ret != FPGA_SEC_ERR_NONE) {
 		fpga_sec_dev_error(smgr, ret);
 		goto modput_exit;
 	}
 
-	update_progress(smgr, FPGA_SEC_PROG_WRITING);
-	while (smgr->remaining_size) {
+	if (progress_transition(smgr, FPGA_SEC_PROG_WRITING))
+		goto done;
+
+	while (smgr->remaining_size && !smgr->request_cancel) {
 		ret = smgr->sops->write_blk(smgr, offset);
 		if (ret != FPGA_SEC_ERR_NONE) {
 			fpga_sec_dev_error(smgr, ret);
@@ -89,7 +110,9 @@  static void fpga_sec_mgr_update(struct work_struct *work)
 		offset = fw->size - smgr->remaining_size;
 	}
 
-	update_progress(smgr, FPGA_SEC_PROG_PROGRAMMING);
+	if (progress_transition(smgr, FPGA_SEC_PROG_PROGRAMMING))
+		goto done;
+
 	ret = smgr->sops->poll_complete(smgr);
 	if (ret != FPGA_SEC_ERR_NONE)
 		fpga_sec_dev_error(smgr, ret);
@@ -226,6 +249,7 @@  static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
 	}
 
 	smgr->err_code = FPGA_SEC_ERR_NONE;
+	smgr->request_cancel = false;
 	smgr->progress = FPGA_SEC_PROG_READING;
 	reinit_completion(&smgr->update_done);
 	schedule_work(&smgr->work);
@@ -236,8 +260,32 @@  static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_WO(filename);
 
+static ssize_t cancel_store(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	struct fpga_sec_mgr *smgr = to_sec_mgr(dev);
+	bool cancel;
+	int ret = count;
+
+	if (kstrtobool(buf, &cancel) || !cancel)
+		return -EINVAL;
+
+	mutex_lock(&smgr->lock);
+	if (smgr->progress == FPGA_SEC_PROG_PROGRAMMING)
+		ret = -EBUSY;
+	else if (smgr->progress == FPGA_SEC_PROG_IDLE)
+		ret = -ENODEV;
+	else
+		smgr->request_cancel = true;
+	mutex_unlock(&smgr->lock);
+
+	return ret;
+}
+static DEVICE_ATTR_WO(cancel);
+
 static struct attribute *sec_mgr_update_attrs[] = {
 	&dev_attr_filename.attr,
+	&dev_attr_cancel.attr,
 	&dev_attr_status.attr,
 	&dev_attr_error.attr,
 	&dev_attr_remaining_size.attr,
@@ -350,6 +398,9 @@  void fpga_sec_mgr_unregister(struct fpga_sec_mgr *smgr)
 		goto unregister;
 	}
 
+	if (smgr->progress != FPGA_SEC_PROG_PROGRAMMING)
+		smgr->request_cancel = true;
+
 	mutex_unlock(&smgr->lock);
 	wait_for_completion(&smgr->update_done);
 
diff --git a/include/linux/fpga/fpga-sec-mgr.h b/include/linux/fpga/fpga-sec-mgr.h
index ea6f1dd711ca..cb31ece6ab5e 100644
--- a/include/linux/fpga/fpga-sec-mgr.h
+++ b/include/linux/fpga/fpga-sec-mgr.h
@@ -71,6 +71,7 @@  struct fpga_sec_mgr {
 	enum fpga_sec_prog progress;
 	enum fpga_sec_prog err_state;	/* progress state at time of failure */
 	enum fpga_sec_err err_code;	/* security manager error code */
+	bool request_cancel;
 	bool driver_unload;
 	void *priv;
 };