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Subject[PATCH 29/40] efi: A misc char interface to update EFI firmware
Date
From: "Kweh, Hock Leong" <hock.leong.kweh@intel.com>

This patch introduces a kernel module to expose a capsule loader
interface (misc char device file note) for users to upload capsule
binaries.

Example:
cat firmware.bin > /dev/efi_capsule_loader

Any upload error will be returned while doing "cat" through file
operation write() function call.

Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: joeyli <jlee@suse.com>
[ Update comments and Kconfig text ]
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
drivers/firmware/efi/Kconfig | 10 +
drivers/firmware/efi/Makefile | 1 +
drivers/firmware/efi/capsule-loader.c | 343 ++++++++++++++++++++++++++++++++++
3 files changed, 354 insertions(+)
create mode 100644 drivers/firmware/efi/capsule-loader.c

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 0b0b635aa101..6394152f648f 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -102,6 +102,16 @@ config EFI_BOOTLOADER_CONTROL
bootloader reads this reboot reason and takes particular
action according to its policy.

+config EFI_CAPSULE_LOADER
+ tristate "EFI capsule loader"
+ depends on EFI
+ help
+ This option exposes a loader interface "/dev/efi_capsule_loader" for
+ users to load EFI capsules. This driver requires working runtime
+ capsule support in the firmware, which many OEMs do not provide.
+
+ Most users should say N.
+
endmenu

config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index fb8ad5db6547..a219640f881f 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o
arm-obj-$(CONFIG_EFI) := arm-init.o arm-runtime.o
obj-$(CONFIG_ARM) += $(arm-obj-y)
obj-$(CONFIG_ARM64) += $(arm-obj-y)
+obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
diff --git a/drivers/firmware/efi/capsule-loader.c b/drivers/firmware/efi/capsule-loader.c
new file mode 100644
index 000000000000..c99c24bc79b0
--- /dev/null
+++ b/drivers/firmware/efi/capsule-loader.c
@@ -0,0 +1,343 @@
+/*
+ * EFI capsule loader driver.
+ *
+ * Copyright 2015 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) "efi: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/efi.h>
+
+#define NO_FURTHER_WRITE_ACTION -1
+
+struct capsule_info {
+ bool header_obtained;
+ int reset_type;
+ long index;
+ size_t count;
+ size_t total_size;
+ struct page **pages;
+ size_t page_bytes_remain;
+};
+
+/**
+ * efi_free_all_buff_pages - free all previous allocated buffer pages
+ * @cap_info: pointer to current instance of capsule_info structure
+ *
+ * In addition to freeing buffer pages, it flags NO_FURTHER_WRITE_ACTION
+ * to cease processing data in subsequent write(2) calls until close(2)
+ * is called.
+ **/
+static void efi_free_all_buff_pages(struct capsule_info *cap_info)
+{
+ while (cap_info->index > 0)
+ __free_page(cap_info->pages[--cap_info->index]);
+
+ cap_info->index = NO_FURTHER_WRITE_ACTION;
+}
+
+/**
+ * efi_capsule_setup_info - obtain the efi capsule header in the binary and
+ * setup capsule_info structure
+ * @cap_info: pointer to current instance of capsule_info structure
+ * @kbuff: a mapped first page buffer pointer
+ * @hdr_bytes: the total received number of bytes for efi header
+ **/
+static ssize_t efi_capsule_setup_info(struct capsule_info *cap_info,
+ void *kbuff, size_t hdr_bytes)
+{
+ efi_capsule_header_t *cap_hdr;
+ size_t pages_needed;
+ int ret;
+ void *temp_page;
+
+ /* Only process data block that is larger than efi header size */
+ if (hdr_bytes < sizeof(efi_capsule_header_t))
+ return 0;
+
+ /* Reset back to the correct offset of header */
+ cap_hdr = kbuff - cap_info->count;
+ pages_needed = ALIGN(cap_hdr->imagesize, PAGE_SIZE) >> PAGE_SHIFT;
+
+ if (pages_needed == 0) {
+ pr_err("%s: pages count invalid\n", __func__);
+ return -EINVAL;
+ }
+
+ /* Check if the capsule binary supported */
+ ret = efi_capsule_supported(cap_hdr->guid, cap_hdr->flags,
+ cap_hdr->imagesize,
+ &cap_info->reset_type);
+ if (ret) {
+ pr_err("%s: efi_capsule_supported() failed\n",
+ __func__);
+ return ret;
+ }
+
+ cap_info->total_size = cap_hdr->imagesize;
+ temp_page = krealloc(cap_info->pages,
+ pages_needed * sizeof(void *),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!temp_page) {
+ pr_debug("%s: krealloc() failed\n", __func__);
+ return -ENOMEM;
+ }
+
+ cap_info->pages = temp_page;
+ cap_info->header_obtained = true;
+
+ return 0;
+}
+
+/**
+ * efi_capsule_submit_update - invoke the efi_capsule_update API once binary
+ * upload done
+ * @cap_info: pointer to current instance of capsule_info structure
+ **/
+static ssize_t efi_capsule_submit_update(struct capsule_info *cap_info)
+{
+ int ret;
+ void *cap_hdr_temp;
+
+ cap_hdr_temp = kmap(cap_info->pages[0]);
+ if (!cap_hdr_temp) {
+ pr_debug("%s: kmap() failed\n", __func__);
+ return -EFAULT;
+ }
+
+ ret = efi_capsule_update(cap_hdr_temp, cap_info->pages);
+ kunmap(cap_info->pages[0]);
+ if (ret) {
+ pr_err("%s: efi_capsule_update() failed\n", __func__);
+ return ret;
+ }
+
+ /* Indicate capsule binary uploading is done */
+ cap_info->index = NO_FURTHER_WRITE_ACTION;
+ pr_info("%s: Successfully upload capsule file with reboot type '%s'\n",
+ __func__, !cap_info->reset_type ? "RESET_COLD" :
+ cap_info->reset_type == 1 ? "RESET_WARM" :
+ "RESET_SHUTDOWN");
+ return 0;
+}
+
+/**
+ * efi_capsule_write - store the capsule binary and pass it to
+ * efi_capsule_update() API
+ * @file: file pointer
+ * @buff: buffer pointer
+ * @count: number of bytes in @buff
+ * @offp: not used
+ *
+ * Expectation:
+ * - A user space tool should start at the beginning of capsule binary and
+ * pass data in sequentially.
+ * - Users should close and re-open this file note in order to upload more
+ * capsules.
+ * - After an error returned, user should close the file and restart the
+ * operation for the next try otherwise -EIO will be returned until the
+ * file is closed.
+ * - An EFI capsule header must be located at the beginning of capsule
+ * binary file and passed in as first block data of write operation.
+ **/
+static ssize_t efi_capsule_write(struct file *file, const char __user *buff,
+ size_t count, loff_t *offp)
+{
+ int ret = 0;
+ struct capsule_info *cap_info = file->private_data;
+ struct page *page;
+ void *kbuff = NULL;
+ size_t write_byte;
+
+ if (count == 0)
+ return 0;
+
+ /* Return error while NO_FURTHER_WRITE_ACTION is flagged */
+ if (cap_info->index < 0)
+ return -EIO;
+
+ /* Only alloc a new page when previous page is full */
+ if (!cap_info->page_bytes_remain) {
+ page = alloc_page(GFP_KERNEL);
+ if (!page) {
+ pr_debug("%s: alloc_page() failed\n", __func__);
+ ret = -ENOMEM;
+ goto failed;
+ }
+
+ cap_info->pages[cap_info->index++] = page;
+ cap_info->page_bytes_remain = PAGE_SIZE;
+ }
+
+ page = cap_info->pages[cap_info->index - 1];
+
+ kbuff = kmap(page);
+ if (!kbuff) {
+ pr_debug("%s: kmap() failed\n", __func__);
+ ret = -EFAULT;
+ goto failed;
+ }
+ kbuff += PAGE_SIZE - cap_info->page_bytes_remain;
+
+ /* Copy capsule binary data from user space to kernel space buffer */
+ write_byte = min_t(size_t, count, cap_info->page_bytes_remain);
+ if (copy_from_user(kbuff, buff, write_byte)) {
+ pr_debug("%s: copy_from_user() failed\n", __func__);
+ ret = -EFAULT;
+ goto fail_unmap;
+ }
+ cap_info->page_bytes_remain -= write_byte;
+
+ /* Setup capsule binary info structure */
+ if (!cap_info->header_obtained) {
+ ret = efi_capsule_setup_info(cap_info, kbuff,
+ cap_info->count + write_byte);
+ if (ret)
+ goto fail_unmap;
+ }
+
+ cap_info->count += write_byte;
+ kunmap(page);
+
+ /* Submit the full binary to efi_capsule_update() API */
+ if (cap_info->header_obtained &&
+ cap_info->count >= cap_info->total_size) {
+ if (cap_info->count > cap_info->total_size) {
+ pr_err("%s: upload size exceeded header defined size\n",
+ __func__);
+ ret = -EINVAL;
+ goto failed;
+ }
+
+ ret = efi_capsule_submit_update(cap_info);
+ if (ret)
+ goto failed;
+ }
+
+ return write_byte;
+
+fail_unmap:
+ kunmap(page);
+failed:
+ efi_free_all_buff_pages(cap_info);
+ return ret;
+}
+
+/**
+ * efi_capsule_flush - called by file close or file flush
+ * @file: file pointer
+ * @id: not used
+ *
+ * If a capsule is being partially uploaded then calling this function
+ * will be treated as upload termination and will free those completed
+ * buffer pages and -ECANCELED will be returned.
+ **/
+static int efi_capsule_flush(struct file *file, fl_owner_t id)
+{
+ int ret = 0;
+ struct capsule_info *cap_info = file->private_data;
+
+ if (cap_info->index > 0) {
+ pr_err("%s: capsule upload not complete\n", __func__);
+ efi_free_all_buff_pages(cap_info);
+ ret = -ECANCELED;
+ }
+
+ return ret;
+}
+
+/**
+ * efi_capsule_release - called by file close
+ * @inode: not used
+ * @file: file pointer
+ *
+ * We will not free successfully submitted pages since efi update
+ * requires data to be maintained across system reboot.
+ **/
+static int efi_capsule_release(struct inode *inode, struct file *file)
+{
+ struct capsule_info *cap_info = file->private_data;
+
+ kfree(cap_info->pages);
+ kfree(file->private_data);
+ file->private_data = NULL;
+ return 0;
+}
+
+/**
+ * efi_capsule_open - called by file open
+ * @inode: not used
+ * @file: file pointer
+ *
+ * Will allocate each capsule_info memory for each file open call.
+ * This provided the capability to support multiple file open feature
+ * where user is not needed to wait for others to finish in order to
+ * upload their capsule binary.
+ **/
+static int efi_capsule_open(struct inode *inode, struct file *file)
+{
+ struct capsule_info *cap_info;
+
+ cap_info = kzalloc(sizeof(*cap_info), GFP_KERNEL);
+ if (!cap_info)
+ return -ENOMEM;
+
+ cap_info->pages = kzalloc(sizeof(void *), GFP_KERNEL);
+ if (!cap_info->pages) {
+ kfree(cap_info);
+ return -ENOMEM;
+ }
+
+ file->private_data = cap_info;
+
+ return 0;
+}
+
+static const struct file_operations efi_capsule_fops = {
+ .owner = THIS_MODULE,
+ .open = efi_capsule_open,
+ .write = efi_capsule_write,
+ .flush = efi_capsule_flush,
+ .release = efi_capsule_release,
+ .llseek = no_llseek,
+};
+
+static struct miscdevice efi_capsule_misc = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "efi_capsule_loader",
+ .fops = &efi_capsule_fops,
+};
+
+static int __init efi_capsule_loader_init(void)
+{
+ int ret;
+
+ if (!efi_enabled(EFI_RUNTIME_SERVICES))
+ return -ENODEV;
+
+ ret = misc_register(&efi_capsule_misc);
+ if (ret)
+ pr_err("%s: Failed to register misc char file note\n",
+ __func__);
+
+ return ret;
+}
+module_init(efi_capsule_loader_init);
+
+static void __exit efi_capsule_loader_exit(void)
+{
+ misc_deregister(&efi_capsule_misc);
+}
+module_exit(efi_capsule_loader_exit);
+
+MODULE_DESCRIPTION("EFI capsule firmware binary loader");
+MODULE_LICENSE("GPL v2");
--
2.7.3
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