[PATCH 4/6] efi_loader: Replace config option for initrd loading
Heinrich Schuchardt
xypron.glpk at gmx.de
Thu Mar 11 13:23:05 CET 2021
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 at 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?
> + /* 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.
> 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;
> +}
>
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