Re: [PATCH 4/6] efi_loader: Replace config option for initrd loading

On 11.03.21 13:30, Ilias Apalodimas wrote:

On Thu, Mar 11, 2021 at 01:23:05PM +0100, Heinrich Schuchardt wrote:

...

On 05.03.21 23:23, Ilias Apalodimas wrote:

...

Up to now we install EFI_LOAD_FILE2_PROTOCOL to load an initrd unconditionally. Although we correctly return various EFI exit codes depending on the file status (i.e EFI_NO_MEDIA, EFI_NOT_FOUND etc), the kernel loader, only falls back to the cmdline interpreted initrd if the protocol is not installed.

This creates a problem for EFI installers, since they won't be able to load their own initrd and continue the installation. It also makes the feature hard to use, since we can either have a single initrd or we have to recompile u-boot if the filename changes.

So let's introduce a different logic that will decouple the initrd path from the config option we currently have. When defining a UEFI BootXXXX we can use the filepathlist and store a file path pointing to our initrd. Specifically the EFI spec describes:

"The first element of the array is a device path that describes the device and location of the Image for this load option. Other device paths may optionally exist in the FilePathList, but their usage is OSV specific"

When the EFI application is launched through the bootmgr, we'll try to interpret the extra device path. If that points to a file that exists on our disk, we'll now install the load_file2 and the efi-stub will be able to use it.

This opens up another path using U-Boot and defines a new boot flow. A user will be able to control the kernel/initrd pairs without explicit cmdline args or GRUB.

Signed-off-by: Ilias Apalodimas ilias.apalodimas@linaro.org

cmd/bootefi.c | 3 + include/efi_loader.h | 1 + lib/efi_loader/Kconfig | 15 +-- lib/efi_loader/efi_bootmgr.c | 3 + lib/efi_loader/efi_load_initrd.c | 209 +++++++++++++++++++++---------- 5 files changed, 152 insertions(+), 79 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c index 271b385edea6..cba81ffe75e4 100644 --- a/cmd/bootefi.c +++ b/cmd/bootefi.c @@ -358,6 +358,9 @@ static efi_status_t do_bootefi_exec(efi_handle_t handle, void *load_options)

free(load_options);

• if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD))

• efi_initrd_deregister();
  

• return ret;

}

diff --git a/include/efi_loader.h b/include/efi_loader.h index eb11a8c7d4b1..0d4f5d9acc9f 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -431,6 +431,7 @@ efi_status_t efi_net_register(void); /* Called by bootefi to make the watchdog available */ efi_status_t efi_watchdog_register(void); efi_status_t efi_initrd_register(void); +void efi_initrd_deregister(void); /* Called by bootefi to make SMBIOS tables available */ /**

• efi_acpi_register() - write out ACPI tables

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig index e729f727df11..029f0e515f57 100644 --- a/lib/efi_loader/Kconfig +++ b/lib/efi_loader/Kconfig @@ -317,16 +317,11 @@ config EFI_LOAD_FILE2_INITRD bool "EFI_FILE_LOAD2_PROTOCOL for Linux initial ramdisk" default n help

•  Expose a EFI_FILE_LOAD2_PROTOCOL that the Linux UEFI stub can
  

•  use to load the initial ramdisk. Once this is enabled using
  

•  initrd=<ramdisk> will stop working.
  

-config EFI_INITRD_FILESPEC

• string "initramfs path"
• default "host 0:1 initrd"
• depends on EFI_LOAD_FILE2_INITRD
• help

•  Full path of the initramfs file, e.g. mmc 0:2 initramfs.cpio.gz.
  

• Linux v5.7 and later can make use of this option. If the boot option
  

• selected by the UEFI boot manager specifies an existing file to be used
  

• as initial RAM disk, a Linux specific Load File2 protocol will be
  

• installed and Linux 5.7+ will ignore any initrd=<ramdisk> command line
  

• argument.
  
  

config EFI_SECURE_BOOT bool "Enable EFI secure boot support" diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c index 25f5cebfdb67..d1baa8c71a4d 100644 --- a/lib/efi_loader/efi_bootmgr.c +++ b/lib/efi_loader/efi_bootmgr.c @@ -118,6 +118,9 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t *handle, ret = efi_set_variable_int(L"BootCurrent", &efi_global_variable_guid, attributes, sizeof(n), &n, false);

Why would you continue if BootCurrent is not set?

Because the bitops below is just trying to simplify the code reading, since both must call efi_unload_image(). Calling efi_initrd_register() without a BootCurrent is guaranteed to fail as well.

...

...

• /* try to register load file2 for initrd's */
  

• if (IS_ENABLED(CONFIG_EFI_LOAD_FILE2_INITRD))
  

• 	ret |= efi_initrd_register();
  

ret is not a boolean. So |= does not make sense to me here.

Uhm? It's an unsigned long though and you can hav bitops properly?

EFI_DEVICE_ERROR | EFI_INVALID_PARAMETER => EFI_ACCESS_DENIED

That does not make much sense.

Best regards

Heinrich

...

...

if (ret != EFI_SUCCESS) {
	if (EFI_CALL(efi_unload_image(*handle))
	    != EFI_SUCCESS)

diff --git a/lib/efi_loader/efi_load_initrd.c b/lib/efi_loader/efi_load_initrd.c index b9ee8839054f..b11c5ee293fe 100644 --- a/lib/efi_loader/efi_load_initrd.c +++ b/lib/efi_loader/efi_load_initrd.c @@ -5,7 +5,9 @@

#include <common.h> #include <efi_loader.h> +#include <efi_helper.h> #include <efi_load_initrd.h> +#include <efi_variable.h> #include <fs.h> #include <malloc.h> #include <mapmem.h> @@ -39,41 +41,71 @@ static const struct efi_initrd_dp dp = { } };

+static efi_handle_t efi_initrd_handle;

/**

• • get_file_size() - retrieve the size of initramfs, set efi status on error

• • get_initrd_fp() - Get initrd device path from a FilePathList device path

• • @dev: device to read from, e.g. "mmc"
• • @part: device partition, e.g. "0:1"
• • @file: name of file
• • @status: EFI exit code in case of failure

• • @initrd_fp: the final initrd filepath

• • Return: size of file

• • Return: status code
  */

-static loff_t get_file_size(const char *dev, const char *part, const char *file,

• 	    efi_status_t *status)
  

+static efi_status_t get_initrd_fp(struct efi_device_path **initrd_fp) {

• loff_t sz = 0;
• int ret;

• const efi_guid_t lf2_initrd_guid = EFI_INITRD_MEDIA_GUID;
• struct efi_device_path *cur = NULL;
• struct efi_device_path *dp = NULL;
• struct efi_device_path *tmp_dp;
• efi_uintn_t ret;
• efi_uintn_t size;

• ret = fs_set_blk_dev(dev, part, FS_TYPE_ANY);
• if (ret) {

• *status = EFI_NO_MEDIA;
  

gg/> + /*

...

• * if bootmgr is setup with and initrd, the device path will be
  

• * in the FilePathList[] of our load options in Boot####.
  

• * The first device path of the multi instance device path will
  

• * start with a VenMedia and the initrds will follow.
  

• *
  

• * If the device path is not found return EFI_INVALID_PARAMETER.
  

• * We can then use this specific return value and not install the
  

• * protocol, while allowing the boot to continue
  

• */
  

• dp = efi_get_dp_from_boot(lf2_initrd_guid);
• if (!dp) {

• ret = EFI_INVALID_PARAMETER;
  

  goto out; }

• ret = fs_size(file, &sz);
• if (ret) {

• sz = 0;
  

• *status = EFI_NOT_FOUND;
  

• tmp_dp = dp;

• cur = efi_dp_get_next_instance(&tmp_dp, &size);

• if (!cur) {

• ret = EFI_OUT_OF_RESOURCES;
  

  goto out; }

• /*

• * We don't care if the file path is eventually NULL here. The
  

• * callers will try to load a file from it and eventually fail
  

• * but let's be explicit with our return values
  

• */
  

• if (!tmp_dp) {

• *initrd_fp = NULL;
  

• ret = EFI_NOT_FOUND;
  

• } else {

• *initrd_fp = efi_dp_dup(tmp_dp);
  

• if (*initrd_fp)
  

• 	ret = EFI_SUCCESS;
  

• else
  

• 	ret = EFI_OUT_OF_RESOURCES;
  

• }

out:

• return sz;

• efi_free_pool(cur);
• efi_free_pool(dp);
• return ret;

}

/**

• • efi_load_file2initrd() - load initial RAM disk

• • efi_load_file2_initrd() - load initial RAM disk
  • This function implements the LoadFile service of the EFI_LOAD_FILE2_PROTOCOL
  • in order to load an initial RAM disk requested by the Linux kernel stub.

@@ -93,98 +125,131 @@ efi_load_file2_initrd(struct efi_load_file_protocol *this, struct efi_device_path *file_path, bool boot_policy, efi_uintn_t *buffer_size, void *buffer) {

• char *filespec;
• efi_status_t status = EFI_NOT_FOUND;
• loff_t file_sz = 0, read_sz = 0;
• char *dev, *part, *file;
• char *pos;
• int ret;

• struct efi_device_path *initrd_fp = NULL;

• struct efi_file_info *info = NULL;

• efi_status_t ret = EFI_NOT_FOUND;

• struct efi_file_handle *f;

• efi_uintn_t bs;

  EFI_ENTRY("%p, %p, %d, %p, %p", this, file_path, boot_policy, buffer_size, buffer);

• filespec = strdup(CONFIG_EFI_INITRD_FILESPEC);
• if (!filespec)

• goto out;
  

• pos = filespec;
• if (!this || this != &efi_lf2_protocol || !buffer_size) {

• status = EFI_INVALID_PARAMETER;
  

• ret = EFI_INVALID_PARAMETER;
  

  goto out; }

  if (file_path->type != dp.end.type || file_path->sub_type != dp.end.sub_type) {

• status = EFI_INVALID_PARAMETER;
  

• ret = EFI_INVALID_PARAMETER;
  

  goto out; }

  if (boot_policy) {

• status = EFI_UNSUPPORTED;
  

• ret = EFI_UNSUPPORTED;
  

  goto out; }

• /*

• * expect a string with three space separated parts:
  

• *
  

• * * a block device type, e.g. "mmc"
  

• * * a device and partition identifier, e.g. "0:1"
  

• * * a file path on the block device, e.g. "/boot/initrd.cpio.gz"
  

• */
  

• dev = strsep(&pos, " ");
• if (!dev)

• ret = get_initrd_fp(&initrd_fp);
• if (ret != EFI_SUCCESS) goto out;

• part = strsep(&pos, " ");
• if (!part)

• /* Open file */
• f = efi_file_from_path(initrd_fp);
• if (!f) {

• ret = EFI_NOT_FOUND;
  

  goto out;

• file = strsep(&pos, " ");
• if (!file)

• }
• /* Get file size */
• bs = 0;
• EFI_CALL(ret = f->getinfo(f, (efi_guid_t *)&efi_file_info_guid,

• 		  &bs, info));
  

Please, use

ret = EFI_CALL(f-> ...);

througout the code.

In efi_load_image_from_file() and efi_capsule_read_file() we also retrieve the file size. We should factor out a function efi_get_file_size().

...

• if (ret != EFI_BUFFER_TOO_SMALL) {

• ret = EFI_DEVICE_ERROR;
  

  goto out;
• }

• file_sz = get_file_size(dev, part, file, &status);
• if (!file_sz)

• info = malloc(bs);
• EFI_CALL(ret = f->getinfo(f, (efi_guid_t *)&efi_file_info_guid, &bs,

• 		  info));
  

• if (ret != EFI_SUCCESS) goto out;

• if (!buffer || *buffer_size < file_sz) {

• status = EFI_BUFFER_TOO_SMALL;
  

• *buffer_size = file_sz;
  

• bs = info->file_size;
• if (!buffer || *buffer_size < bs) {

• ret = EFI_BUFFER_TOO_SMALL;
  

• *buffer_size = bs;
  

  } else {

• ret = fs_set_blk_dev(dev, part, FS_TYPE_ANY);
  

• if (ret) {
  

• 	status = EFI_NO_MEDIA;
  

• 	goto out;
  

• }
  

• ret = fs_read(file, map_to_sysmem(buffer), 0, *buffer_size,
  

• 	      &read_sz);
  

• if (ret || read_sz != file_sz)
  

• 	goto out;
  

• *buffer_size = read_sz;
  

• status = EFI_SUCCESS;
  

• EFI_CALL(ret = f->read(f, &bs, (void *)(uintptr_t)buffer));
  

• *buffer_size = bs;
  

  }

out:

• free(filespec);
• return EFI_EXIT(status);

• free(info);
• efi_free_pool(initrd_fp);
• EFI_CALL(f->close(f));
• return EFI_EXIT(ret);

+}

+/**

• • check_initrd() - Determine if the file defined as an initrd in Boot####

• •     load_options device path is present
    

• • Return: status code
• */

+static efi_status_t check_initrd(void) +{

• struct efi_device_path *initrd_fp = NULL;
• struct efi_file_handle *f;
• efi_status_t ret;
• ret = get_initrd_fp(&initrd_fp);
• if (ret != EFI_SUCCESS)

• goto out;
  

• /*

• * If the file is not found, but the file path is set, return an error
  

• * and trigger the bootmgr fallback
  

• */
  

• f = efi_file_from_path(initrd_fp);
• if (!f) {

This deserves a log_warning().

...

• ret = EFI_NOT_FOUND;
  

• goto out;
  

• }
• EFI_CALL(f->close(f));

+out:

• efi_free_pool(initrd_fp);
• return ret;

}

/**

• efi_initrd_register() - create handle for loading initial RAM disk
• This function creates a new handle and installs a Linux specific vendor

• • device path and an EFI_LOAD_FILE_2_PROTOCOL. Linux uses the device path

• • device path and an EFI_LOAD_FILE2_PROTOCOL. Linux uses the device path
  • to identify the handle and then calls the LoadFile service of the

• • EFI_LOAD_FILE_2_PROTOCOL to read the initial RAM disk.

• • EFI_LOAD_FILE2_PROTOCOL to read the initial RAM disk.
  • Return: status code
  */

efi_status_t efi_initrd_register(void) {

• efi_handle_t efi_initrd_handle = NULL; efi_status_t ret;

• /*

• * Allow the user to continue if Boot#### file path is not set for
  

• * an initrd
  

• */
  

• ret = check_initrd();
• if (ret == EFI_INVALID_PARAMETER)

• return EFI_SUCCESS;
  

• if (ret != EFI_SUCCESS)

• return ret;
  

• ret = EFI_CALL(efi_install_multiple_protocol_interfaces (&efi_initrd_handle, /* initramfs */

@@ -196,3 +261,9 @@ efi_status_t efi_initrd_register(void)

return ret; }

+void efi_initrd_deregister(void)

Missing description of an exported function.

Best regards

Heinrich

...

+{

• efi_delete_handle(efi_initrd_handle);
• efi_initrd_handle = NULL;

+}