From: "Kweh, Hock Leong" <hock.leong.kweh@xxxxxxxxx>
Introducing a kernel module to expose user helper interface for
user to upload capsule binaries. This module leverage the
request_firmware_nowait() to expose an interface to user.
Example steps to load the capsule binary:
1.) echo 1 > /sys/class/firmware/efi-capsule-file/loading
2.) cat capsule.bin > /sys/class/firmware/efi-capsule-file/data
3.) echo 0 > /sys/class/firmware/efi-capsule-file/loading
Whereas, this module does not allow the capsule binaries to be
obtained from the request_firmware library search path. If any
capsule binary loaded from firmware seach path, the module will
stop functioning.
Besides the request_firmware user helper interface, this module
also expose a 'capsule_loaded' file note for user to verify
the number of successfully uploaded capsule binaries. This
file note has the read only attribute.
Cc: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@xxxxxxxxx>
---
drivers/firmware/efi/Kconfig | 13 ++
drivers/firmware/efi/Makefile | 1 +
drivers/firmware/efi/efi-capsule-user-helper.c | 246 ++++++++++++++++++++++++
3 files changed, 260 insertions(+)
create mode 100644 drivers/firmware/efi/efi-capsule-user-helper.c
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index f712d47..7dc814e 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -60,6 +60,19 @@ config EFI_RUNTIME_WRAPPERS
config EFI_ARMSTUB
bool
+config EFI_CAPSULE_USER_HELPER
+ tristate "EFI capsule user mode helper"
+ depends on EFI
+ select FW_LOADER
+ select FW_LOADER_USER_HELPER
+ help
+ This option exposes the user mode helper interface for user to load
+ EFI capsule binary and update the EFI firmware after system reboot.
+ This feature does not support auto locating capsule binaries at the
+ firmware lib search path.
+
+ If unsure, say N.
+
endmenu
config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 698846e..63f6910 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_UEFI_CPER) += cper.o
obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o
obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o
obj-$(CONFIG_EFI_STUB) += libstub/
+obj-$(CONFIG_EFI_CAPSULE_USER_HELPER) += efi-capsule-user-helper.o
diff --git a/drivers/firmware/efi/efi-capsule-user-helper.c b/drivers/firmware/efi/efi-capsule-user-helper.c
new file mode 100644
index 0000000..84a1628
--- /dev/null
+++ b/drivers/firmware/efi/efi-capsule-user-helper.c
@@ -0,0 +1,246 @@
+/*
+ * EFI capsule user mode helper interface driver.
+ *
+ * Copyright 2014 Intel Corporation
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/reboot.h>
+#include <linux/efi.h>
+#include <linux/firmware.h>
+
+#define CAPSULE_NAME "efi-capsule-file"
+#define DEV_NAME "efi_capsule_user_helper"
+#define STRING_INTEGER_MAX_LENGTH 13
+
+static DEFINE_MUTEX(user_helper_lock);
+static int capsule_count;
+static int stop_request;
+static struct platform_device *efi_capsule_pdev;
+
+/*
+ * This function will store the capsule binary and pass it to
+ * efi_capsule_update() API in capsule.c
+ */
+static int efi_capsule_store(const struct firmware *fw)
+{
+ int i;
+ int ret;
+ int count = fw->size;
+ int copy_size = (fw->size > PAGE_SIZE) ? PAGE_SIZE : fw->size;
+ int pages_needed = ALIGN(fw->size, PAGE_SIZE) >> PAGE_SHIFT;
+ struct page **pages;
+ void *page_data;
+ efi_capsule_header_t *capsule = NULL;
+
+ pages = kmalloc_array(pages_needed, sizeof(void *), GFP_KERNEL);
+ if (!pages) {
+ pr_err("%s: kmalloc_array() failed\n", __func__);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < pages_needed; i++) {
+ pages[i] = alloc_page(GFP_KERNEL);
+ if (!pages[i]) {
+ pr_err("%s: alloc_page() failed\n", __func__);
+ --i;
+ ret = -ENOMEM;
+ goto failed;
+ }
+ }
+
+ for (i = 0; i < pages_needed; i++) {
+ page_data = kmap(pages[i]);
+ memcpy(page_data, fw->data + (i * PAGE_SIZE), copy_size);
+
+ if (i == 0)
+ capsule = (efi_capsule_header_t *)page_data;
+ else
+ kunmap(pages[i]);
+
+ count -= copy_size;
+ if (count < PAGE_SIZE)
+ copy_size = count;
+ }
+
+ ret = efi_capsule_update(capsule, pages);
+ if (ret) {
+ pr_err("%s: efi_capsule_update() failed\n", __func__);
+ --i;
+ goto failed;
+ }
+ ++capsule_count;
+ kunmap(pages[0]);
+
+ /*
+ * we cannot free the pages here due to reboot need that data
+ * maintained.
+ */
+ return 0;
+
+failed:
+ while (i >= 0)
+ __free_page(pages[i--]);
+ kfree(pages);
+ return ret;
+}
+
+/*
+ * This callback function will be called by request_firmware_nowait() when
+ * user has loaded the capsule binary or aborted user helper interface
+ */
+static void callbackfn_efi_capsule(const struct firmware *fw, void *context)
+{
+ int ret = 0;
+
+ if (fw) {
+ /*
+ * Binary not getting from user helper interface, fw->pages
+ * is equal to NULL
+ */
+ if (!fw->pages) {
+ pr_err("%s: ERROR: Capsule binary '%s' at %s\n",
+ __func__, CAPSULE_NAME,
+ "firmware lib search path are not supported");
+ pr_err("user helper interface disabled\n");
+ stop_request = 1;
+ } else {
+ efi_capsule_store(fw);
+ }
+ release_firmware(fw);
+ }
+
+ mutex_lock(&user_helper_lock);
+ if (!stop_request) {
+ ret = request_firmware_nowait(THIS_MODULE,
+ FW_ACTION_NOHOTPLUG,
+ CAPSULE_NAME,
+ &efi_capsule_pdev->dev,
+ GFP_KERNEL, NULL,
+ callbackfn_efi_capsule);
+ if (ret) {
+ pr_err("%s: request_firmware_nowait() failed\n",
+ __func__);
+ }
+ }
+ mutex_unlock(&user_helper_lock);
+}
+
+static ssize_t capsule_loaded_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return snprintf(buf, STRING_INTEGER_MAX_LENGTH, "%d\n", capsule_count);
+}
+
+static DEVICE_ATTR_RO(capsule_loaded);
+
+/* stop user helper interface for reboot or module unload */
+static void capsule_stop_user_helper(void)
+{
+ mutex_lock(&user_helper_lock);
+ stop_request = 1;
+ mutex_unlock(&user_helper_lock);
+ request_firmware_abort(CAPSULE_NAME);
+}
+
+/* reboot notifier for avoid deadlock with usermode_lock */
+static int capsule_shutdown_notify(struct notifier_block *nb,
+ unsigned long sys_state,
+ void *reboot_cmd)
+{
+ capsule_stop_user_helper();
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block capsule_shutdown_nb = {
+ .notifier_call = capsule_shutdown_notify,
+ /*
+ * In order to reboot properly, it is required to ensure the priority
+ * here is higher than firmware_class fw_shutdown_nb priority
+ */
+ .priority = 1,
+};
+
+/*
+ * Use request_firmware_nowait() exposing an user helper interface to obtain
+ * capsule binary from user space
+ */
+static int __init efi_capsule_user_helper_init(void)
+{
+ int ret;
+
+ register_reboot_notifier(&capsule_shutdown_nb);
+
+ efi_capsule_pdev = platform_device_register_simple(DEV_NAME,
+ PLATFORM_DEVID_NONE,
+ NULL, 0);
+ if (IS_ERR(efi_capsule_pdev)) {
+ pr_err("%s: platform_device_register_simple() failed\n",
+ __func__);
+ return PTR_ERR(efi_capsule_pdev);
+ }
+
+ /*
+ * create this file node for user to check the number of binaries that
+ * are successfully loaded
+ */
+ ret = device_create_file(&efi_capsule_pdev->dev,
+ &dev_attr_capsule_loaded);
+ if (ret) {
+ pr_err("%s: device_create_file() failed\n", __func__);
+ return ret;
+ }
+
+ ret = request_firmware_nowait(THIS_MODULE, FW_ACTION_NOHOTPLUG,
+ CAPSULE_NAME, &efi_capsule_pdev->dev,
+ GFP_KERNEL, NULL, callbackfn_efi_capsule);
+ if (ret) {
+ pr_err("%s: request_firmware_nowait() failed\n", __func__);
+ goto out;
+ }
+
+ return 0;
+
+out:
+ device_remove_file(&efi_capsule_pdev->dev, &dev_attr_capsule_loaded);
+ unregister_reboot_notifier(&capsule_shutdown_nb);
+ return ret;
+}
+module_init(efi_capsule_user_helper_init);
+
+/*
+ * rmmod app itself will stop you to remove the module if the user
+ * helper interface is still exposing. In order to remove this driver,
+ * you are require to do the command as below:
+ * rmmod -f efi_capsule_user_helper.ko
+ */
+static void __exit efi_capsule_user_helper_exit(void)
+{
+ unregister_reboot_notifier(&capsule_shutdown_nb);
+
+ capsule_stop_user_helper();
+ /*
+ * synchronization is needed to make sure request_firmware is fully
+ * aborted
+ */
+ while (efi_capsule_pdev->dev.kobj.kref.refcount.counter > 3)
+ msleep(20); /* avoid busy waiting for cooperative kernel */
+
+ device_remove_file(&efi_capsule_pdev->dev, &dev_attr_capsule_loaded);
+ platform_device_unregister(efi_capsule_pdev);
+}
+module_exit(efi_capsule_user_helper_exit);
+
+MODULE_DESCRIPTION("EFI Capsule user helper binary load utility");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5
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