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Date: Mon, 5 Oct 2020 08:41:56 +0000
From: "Wu, Hao" <hao.wu@...el.com>
To: "Weight, Russell H" <russell.h.weight@...el.com>,
"mdf@...nel.org" <mdf@...nel.org>,
"linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "trix@...hat.com" <trix@...hat.com>,
"lgoncalv@...hat.com" <lgoncalv@...hat.com>,
"Xu, Yilun" <yilun.xu@...el.com>,
"Gerlach, Matthew" <matthew.gerlach@...el.com>,
"Weight, Russell H" <russell.h.weight@...el.com>
Subject: RE: [PATCH v2 3/7] fpga: sec-mgr: expose sec-mgr update status
> Subject: [PATCH v2 3/7] fpga: sec-mgr: expose sec-mgr update status
>
> Extend the Intel Security Manager class driver to
> include an update/status sysfs node that can be polled
> and read to monitor the progress of an ongoing secure
> update. Sysfs_notify() is used to signal transitions
> between different phases of the update process.
>
> Signed-off-by: Russ Weight <russell.h.weight@...el.com>
> ---
> v2:
> - Bumped documentation date and version
> - Changed progress state "read_file" to "reading"
> ---
> .../ABI/testing/sysfs-class-ifpga-sec-mgr | 11 +++++
> drivers/fpga/ifpga-sec-mgr.c | 40 +++++++++++++++++--
> 2 files changed, 47 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> index 4f375f132c34..73a5246fea1b 100644
> --- a/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> +++ b/Documentation/ABI/testing/sysfs-class-ifpga-sec-mgr
> @@ -78,3 +78,14 @@ Description: Write only. Write the filename of an
> Intel image
> BMC images, BMC firmware, Static Region images,
> and Root Entry Hashes, and to cancel Code Signing
> Keys (CSK).
> +
> +What: /sys/class/ifpga_sec_mgr/ifpga_secX/update/status
> +Date: Oct 2020
> +KernelVersion: 5.11
> +Contact: Russ Weight <russell.h.weight@...el.com>
> +Description: Read-only. Returns a string describing the current
> + status of an update. The string will be one of the
> + following: idle, reading, preparing, writing,
> + programming. Userspace code can poll on this file,
> + as it will be signaled by sysfs_notify() on each
> + state change.
> diff --git a/drivers/fpga/ifpga-sec-mgr.c b/drivers/fpga/ifpga-sec-mgr.c
> index 7d5a4979554b..ad918fb42dc2 100644
> --- a/drivers/fpga/ifpga-sec-mgr.c
> +++ b/drivers/fpga/ifpga-sec-mgr.c
> @@ -139,6 +139,13 @@ static struct attribute *sec_mgr_security_attrs[] = {
> NULL,
> };
>
> +static void update_progress(struct ifpga_sec_mgr *imgr,
> + enum ifpga_sec_prog new_progress)
> +{
> + imgr->progress = new_progress;
> + sysfs_notify(&imgr->dev.kobj, "update", "status");
> +}
> +
> static void ifpga_sec_dev_error(struct ifpga_sec_mgr *imgr,
> enum ifpga_sec_err err_code)
> {
> @@ -149,7 +156,7 @@ static void ifpga_sec_dev_error(struct ifpga_sec_mgr
> *imgr,
> static void progress_complete(struct ifpga_sec_mgr *imgr)
> {
> mutex_lock(&imgr->lock);
> - imgr->progress = IFPGA_SEC_PROG_IDLE;
> + update_progress(imgr, IFPGA_SEC_PROG_IDLE);
> complete_all(&imgr->update_done);
> mutex_unlock(&imgr->lock);
> }
> @@ -177,14 +184,14 @@ static void ifpga_sec_mgr_update(struct
> work_struct *work)
> goto release_fw_exit;
> }
>
> - imgr->progress = IFPGA_SEC_PROG_PREPARING;
> + update_progress(imgr, IFPGA_SEC_PROG_PREPARING);
> ret = imgr->iops->prepare(imgr);
> if (ret) {
> ifpga_sec_dev_error(imgr, ret);
> goto modput_exit;
> }
>
> - imgr->progress = IFPGA_SEC_PROG_WRITING;
> + update_progress(imgr, IFPGA_SEC_PROG_WRITING);
> size = imgr->remaining_size;
> while (size) {
> blk_size = min_t(u32, size, WRITE_BLOCK_SIZE);
> @@ -199,7 +206,7 @@ static void ifpga_sec_mgr_update(struct work_struct
> *work)
> offset += blk_size;
> }
>
> - imgr->progress = IFPGA_SEC_PROG_PROGRAMMING;
> + update_progress(imgr, IFPGA_SEC_PROG_PROGRAMMING);
> ret = imgr->iops->poll_complete(imgr);
> if (ret) {
> ifpga_sec_dev_error(imgr, ret);
> @@ -259,6 +266,30 @@ static struct attribute_group
> sec_mgr_security_attr_group = {
> .is_visible = sec_mgr_visible,
> };
>
> +static const char * const sec_mgr_prog_str[] = {
> + "idle", /* IFPGA_SEC_PROG_IDLE */
> + "reading", /* IFPGA_SEC_PROG_READING */
> + "preparing", /* IFPGA_SEC_PROG_PREPARING */
> + "writing", /* IFPGA_SEC_PROG_WRITING */
> + "programming" /* IFPGA_SEC_PROG_PROGRAMMING */
> +};
> +
> +static ssize_t
> +status_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct ifpga_sec_mgr *imgr = to_sec_mgr(dev);
> + const char *status = "unknown-status";
> +
> + if (imgr->progress < IFPGA_SEC_PROG_MAX)
> + status = sec_mgr_prog_str[imgr->progress];
I am not sure if this would be a problem that as there is no lock protection for
the progress value. If someone changes imgr->progress into a bad value just
after the first check imgr->progress < IFPGA_SEC_PROG_MAX passed.
> + else
> + dev_warn(dev, "Invalid status during secure update: %d\n",
> + imgr->progress);
One minor thing, dev_err or even WARN_ON should be better, and I think
if it hits this, that will be a critical issue in the driver, isn't it?
Thanks
Hao
> +
> + return sprintf(buf, "%s\n", status);
> +}
> +static DEVICE_ATTR_RO(status);
> +
> static ssize_t filename_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> @@ -293,6 +324,7 @@ static DEVICE_ATTR_WO(filename);
>
> static struct attribute *sec_mgr_update_attrs[] = {
> &dev_attr_filename.attr,
> + &dev_attr_status.attr,
> NULL,
> };
>
> --
> 2.17.1
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