On Fri, 18 Dec, at 08:13:01PM, Kweh Hock Leong wrote:
> From: "Kweh, Hock Leong" <hock.leong.kweh@xxxxxxxxx>
>
> Introducing a kernel module to expose capsule loader interface
> (misc char device file note) for user to upload capsule binaries.
>
> Example method to load the capsule binary:
> cat firmware.bin > /dev/efi_capsule_loader
>
> This patch also export efi_capsule_supported() function symbol for
> verifying the submitted capsule header in this kernel module.
>
> Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@xxxxxxxxx>
> ---
> drivers/firmware/efi/Kconfig | 10
> drivers/firmware/efi/Makefile | 1
> drivers/firmware/efi/capsule-loader.c | 355 +++++++++++++++++++++++++++++++++
> drivers/firmware/efi/capsule.c | 1
> 4 files changed, 367 insertions(+)
> create mode 100644 drivers/firmware/efi/capsule-loader.c
[...]
> +#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;
> +};
> +
> +static DEFINE_MUTEX(capsule_loader_lock);
This mutex is not needed. It doesn't protect anything in your code.
> +/**
> + * efi_free_all_buff_pages - free all previous allocated buffer pages
> + * @cap_info: pointer to current instance of capsule_info structure
> + *
> + * Besides freeing the buffer pages, it also flagged an
> + * NO_FURTHER_WRITE_ACTION flag for indicating to the next write entries
> + * that there is a flaw happened and any subsequence actions are not
> + * valid unless close(2).
> + **/
> +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]);
> +
> + kfree(cap_info->pages);
> +
> + cap_info->index = NO_FURTHER_WRITE_ACTION;
> +}
> +
> +/**
> + * efi_capsule_setup_info - to 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 1st page buffer pointer
> + * @hdr_bytes: the total bytes of received efi header
> + **/
> +static ssize_t efi_capsule_setup_info(struct capsule_info *cap_info,
> + void *kbuff, size_t hdr_bytes)
> +{
> + int ret;
> + void *temp_page;
> +
> + /* Handling 1st block is less than header size */
> + if (hdr_bytes < sizeof(efi_capsule_header_t)) {
> + if (!cap_info->pages) {
> + cap_info->pages = kzalloc(sizeof(void *), GFP_KERNEL);
> + if (!cap_info->pages) {
> + pr_debug("%s: kzalloc() failed\n", __func__);
> + return -ENOMEM;
> + }
> + }
This function would be much more simple if you handled the above
condition differently.
Instead of having code in efi_capsule_setup_info() to allocate the
initial ->pages memory, why not just allocate it in efi_capsule_open()
at the same time as you allocate the private_data? You can then
free it in efi_capsule_release() (you're leaking it at the moment).
You are always going to need at least one element in ->pages for
successful operation, so you might as well allocate it up front.
> + } else {
> + /* Reset back to the correct offset of header */
> + efi_capsule_header_t *cap_hdr = kbuff - cap_info->count;
> + size_t 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 */
> + mutex_lock(&capsule_loader_lock);
> + ret = efi_capsule_supported(cap_hdr->guid, cap_hdr->flags,
> + cap_hdr->imagesize,
> + &cap_info->reset_type);
> + mutex_unlock(&capsule_loader_lock);
> + 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 = 1;
This should be 'true', not 1.
> + }
> +
> + 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;
> + }
> +
> + mutex_lock(&capsule_loader_lock);
> + ret = efi_capsule_update(cap_hdr_temp, cap_info->pages);
> + mutex_unlock(&capsule_loader_lock);
> + 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:
> + * - User space tool should start at the beginning of capsule binary and
> + * pass data in sequential.
> + * - User should close and re-open this file note in order to upload more
> + * capsules.
> + * - Any error occurred, user should close the file and restart the
> + * operation for the next try otherwise -EIO will be returned until the
> + * file is closed.
> + * - EFI capsule header must be located at the beginning of capsule binary
> + * file and passed in as 1st block write.
> + **/
> +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 *kbuff_page = NULL;
> + 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) {
> + kbuff_page = alloc_page(GFP_KERNEL);
> + if (!kbuff_page) {
> + pr_debug("%s: alloc_page() failed\n", __func__);
> + ret = -ENOMEM;
> + goto failed;
> + }
> + cap_info->page_bytes_remain = PAGE_SIZE;
> + } else {
> + kbuff_page = cap_info->pages[--cap_info->index];
> + }
This shuffling and unshuffling of cap_info->index seems kinda crazy to
me because you're treating the current page differently from the rest,
which complicates the error paths too (you shouldn't need
__free_page() *and* efi_free_all_buff_pages()).
Why not make cap_info->index always index the last page? That way you
could do,
if (!cap_info->page_bytes_remain) {
cap_info->pages[++cap_info->index] = alloc_page()
cap_info->page_bytes_remain = PAGE_SIZE;
}
kbuff_page = cap_info->pages[cap_info->index];
?
> +
> + kbuff = kmap(kbuff_page);
> + if (!kbuff) {
> + pr_debug("%s: kmap() failed\n", __func__);
> + ret = -EFAULT;
> + goto fail_freepage;
> + }
> + 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->pages[cap_info->index++] = kbuff_page;
> + cap_info->count += write_byte;
> + kunmap(kbuff_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(kbuff_page);
> +fail_freepage:
> + __free_page(kbuff_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 capsule being uploaded partially, calling this function will be
> + * treated as uploading canceled and will free up those completed buffer
> + * pages and then return -ECANCELED.
> + **/
> +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 would not free the successful submitted buffer pages here due to
> + * efi update require system reboot with data maintained.
> + **/
> +static int efi_capsule_release(struct inode *inode, struct file *file)
> +{
> + 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;
> +
> + file->private_data = cap_info;
> +
Please allocate one ->pages element here (void *). You need at least
one for this code to work and you can easily free it in
efi_capsule_release() if it still exists. It would also simplfy
efi_capsule_setup_info() immensely.
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