Re: [PATCH v4 10/11] bootmenu: add removable media entries

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

On Thu, Mar 24, 2022 at 10:54:42PM +0900, Masahisa Kojima wrote:
> UEFI specification requires booting from removal media using
> a architecture-specific default image name such as BOOTAA64.EFI.
> This commit adds the removable media entries into bootmenu,
> so that user can select the removable media and boot with
> default image.
> 
> The bootmenu automatically enumerates the possible bootable
> media devices supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL,
> add it as new UEFI boot option(BOOT####) and update BootOrder
> variable. Depending on the system hardware setup, some devices
> may not exist at a later system boot, so invalid BOOT#### variable
> must be deleted.
> 
> Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
> ---
> Newly created in v4
> 
>  cmd/bootmenu.c                            |  78 +++++++++++++
>  include/efi_loader.h                      |  22 ++++
>  lib/efi_loader/efi_bootmenu_maintenance.c | 128 ++++++++++++++++++++++
>  3 files changed, 228 insertions(+)
> 
> diff --git a/cmd/bootmenu.c b/cmd/bootmenu.c
> index 458eb90b63..7357cfeae5 100644
> --- a/cmd/bootmenu.c
> +++ b/cmd/bootmenu.c
> @@ -304,6 +304,74 @@ static int prepare_uefi_bootorder_entry(struct bootmenu_data *menu,
>  	return 1;
>  }
>  
> +static efi_status_t prepare_media_device_entry(void)
> +{
> +	u32 i;
> +	efi_status_t ret;
> +	efi_uintn_t count;
> +	efi_handle_t *volume_handles = NULL;
> +	struct efi_bootmenu_media_boot_option *opt = NULL;
> +
> +	ret = efi_locate_handle_buffer_int(BY_PROTOCOL, &efi_simple_file_system_protocol_guid,
> +					   NULL, &count, (efi_handle_t **)&volume_handles);
> +	if (ret != EFI_SUCCESS)
> +		return ret;
> +
> +	opt = calloc(count, sizeof(struct efi_bootmenu_media_boot_option));
> +	if (!opt)
> +		goto out;
> +
> +	/* enumerate all devices supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL */
> +	ret = efi_bootmenu_enumerate_boot_option(opt, volume_handles, count);
> +	if (ret != EFI_SUCCESS)
> +		goto out;
> +
> +	/*
> +	 * System hardware configuration may vary depending on the user setup.
> +	 * The boot option is automatically added by the bootmenu.
> +	 * If the device is not attached to the system, the boot option needs
> +	 * to be deleted.
> +	 */
> +	ret = efi_bootmenu_delete_invalid_boot_option(opt, count);

Won't that fail on first boot if the BootOrder is undefined?
efi_bootmenu_delete_invalid_boot_option() should return EFI_SUCCESS if it
doesn't have a boot order maybe?

> +	if (ret != EFI_SUCCESS)
> +		goto out;
> +
> +	/* add non-existent boot option */
> +	for (i = 0; i < count; i++) {
> +		u32 boot_index;
> +		u16 var_name[9];
> +
> +		if (!opt[i].exist) {
> +			ret = efi_bootmenu_get_unused_bootoption(var_name, sizeof(var_name),
> +								 &boot_index);
> +			if (ret != EFI_SUCCESS)
> +				goto out;
> +
> +			ret = efi_set_variable_int(var_name, &efi_global_variable_guid,
> +						   EFI_VARIABLE_NON_VOLATILE |
> +						   EFI_VARIABLE_BOOTSERVICE_ACCESS |
> +						   EFI_VARIABLE_RUNTIME_ACCESS,
> +						   opt[i].size, opt[i].lo, false);
> +			if (ret != EFI_SUCCESS)
> +				goto out;
> +
> +			ret = efi_bootmenu_append_bootorder(boot_index);
> +			if (ret != EFI_SUCCESS)
> +				goto out;
> +		}
> +	}
> +
> +out:
> +	if (opt) {
> +		for (i = 0; i < count; i++)
> +			free(opt[i].lo);
> +	}
> +	free(opt);
> +	efi_free_pool(volume_handles);
> +
> +	return ret;
> +}
> +
>  static int prepare_distro_boot_entry(struct bootmenu_data *menu,
>  				     struct bootmenu_entry **current,
>  				     unsigned short int *index)
> @@ -408,6 +476,16 @@ static struct bootmenu_data *bootmenu_create(int delay)
>  		goto cleanup;
>  
>  	if (IS_ENABLED(CONFIG_CMD_BOOTEFI_BOOTMGR)) {
> +		if (i < MAX_DYNAMIC_ENTRY) {
> +			/*
> +			 * UEFI specification requires booting from removal media using
> +			 * a architecture-specific default image name such as BOOTAA64.EFI.
> +			 */
> +			ret = prepare_media_device_entry();
> +			if (ret != EFI_SUCCESS)
> +				goto cleanup;
> +		}
> +
>  		if (i < MAX_DYNAMIC_ENTRY) {
>  			ret = prepare_uefi_bootorder_entry(menu, &iter, &i);
>  			if (ret < 0 && ret != -ENOENT)
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 7b100ca030..c326dfdaf2 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -926,6 +926,22 @@ struct efi_signature_store {
>  struct x509_certificate;
>  struct pkcs7_message;
>  
> +/**
> + * struct efi_bootmenu_media_boot_option - boot option for (removable) media device
> + *
> + * This structure is used to enumerate possible boot option
> + *
> + * @lo:		Serialized load option data
> + * @size:	Size of serialized load option data
> + * @exist:	Flag to indicate the load option already exists
> + *		in Non-volatile load option
> + */
> +struct efi_bootmenu_media_boot_option {
> +	void *lo;
> +	efi_uintn_t size;
> +	bool exist;
> +};
> +
>  bool efi_signature_lookup_digest(struct efi_image_regions *regs,
>  				 struct efi_signature_store *db,
>  				 bool dbx);
> @@ -1038,6 +1054,12 @@ efi_status_t efi_console_get_u16_string
>  efi_status_t efi_bootmenu_get_unused_bootoption(u16 *buf,
>  						efi_uintn_t buf_size, u32 *index);
>  efi_status_t efi_bootmenu_append_bootorder(u16 index);
> +efi_status_t efi_bootmenu_enumerate_boot_option(
> +			struct efi_bootmenu_media_boot_option *opt,
> +			efi_handle_t *volume_handles, efi_status_t count);
> +efi_status_t efi_bootmenu_delete_invalid_boot_option(
> +			struct efi_bootmenu_media_boot_option *opt,
> +			efi_status_t count);
>  
>  efi_status_t efi_disk_get_device_name(struct efi_block_io *this, char *buf, int size);
>  
> diff --git a/lib/efi_loader/efi_bootmenu_maintenance.c b/lib/efi_loader/efi_bootmenu_maintenance.c
> index 2ce5a47b10..3a64cf767a 100644
> --- a/lib/efi_loader/efi_bootmenu_maintenance.c
> +++ b/lib/efi_loader/efi_bootmenu_maintenance.c
> @@ -24,6 +24,8 @@ static struct efi_simple_text_output_protocol *cout;
>  #define EFI_BOOTMENU_FILE_PATH_MAX 512
>  #define EFI_BOOTMENU_BOOT_NAME_MAX 32
>  #define EFI_BOOT_ORDER_MAX_SIZE_IN_DECIMAL 6
> +#define BOOTMENU_AUTO_ADD_OPTION_DATA "bootmenu"
> +#define BOOTMENU_AUTO_ADD_OPTION_DATA_U16 u"bootmenu"
>  
>  typedef efi_status_t (*efi_bootmenu_entry_func)(void *data, bool *exit);
>  
> @@ -1114,3 +1116,129 @@ efi_status_t efi_bootmenu_show_maintenance_menu(void)
>  					  ARRAY_SIZE(maintenance_menu_items),
>  					  -1);
>  }
> +
> +efi_status_t efi_bootmenu_enumerate_boot_option(
> +			struct efi_bootmenu_media_boot_option *opt,
> +			efi_handle_t *volume_handles, efi_status_t count)
> +{
> +	u32 i;
> +	struct efi_handler *handler;
> +	efi_status_t ret = EFI_SUCCESS;
> +
> +	for (i = 0; i < count; i++) {
> +		u16 *dev_name, *p;
> +		struct efi_load_option lo;
> +		struct efi_block_io *block_io;
> +		char buf[BOOTMENU_DEVICE_NAME_MAX];
> +		struct efi_device_path *device_path;
> +
> +		ret = efi_search_protocol(volume_handles[i], &efi_guid_device_path, &handler);
> +		if (ret != EFI_SUCCESS)
> +			continue;
> +		ret = efi_protocol_open(handler, (void **)&device_path,
> +					efi_root, NULL, EFI_OPEN_PROTOCOL_GET_PROTOCOL);
> +		if (ret != EFI_SUCCESS)
> +			continue;
> +
> +		ret = efi_search_protocol(volume_handles[i], &efi_block_io_guid, &handler);
> +		if (ret != EFI_SUCCESS)
> +			continue;
> +		ret = efi_protocol_open(handler, (void **)&block_io,
> +					efi_root, NULL, EFI_OPEN_PROTOCOL_GET_PROTOCOL);
> +		if (ret != EFI_SUCCESS)
> +			continue;
> +
> +		efi_disk_get_device_name(block_io, buf, BOOTMENU_DEVICE_NAME_MAX);
> +		dev_name = calloc(1, (strlen(buf) + 1) * sizeof(u16));
> +		if (!dev_name) {
> +			ret = EFI_OUT_OF_RESOURCES;
> +			goto out;
> +		}
> +		p = dev_name;
> +		utf8_utf16_strncpy(&p, buf, strlen(buf));
> +
> +		lo.label = dev_name;
> +		lo.attributes = LOAD_OPTION_ACTIVE;
> +		lo.file_path = device_path;
> +		lo.file_path_length = efi_dp_size(device_path) + sizeof(END);
> +		/*
> +		 * To identify the boot option that automatically added by
> +		 * the bootmenu, optional_data has special string.
> +		 * optional_data will be converted into u16 string
> +		 * in efi_serialize_load_option().
> +		 */
> +		lo.optional_data = BOOTMENU_AUTO_ADD_OPTION_DATA;
> +		opt[i].size = efi_serialize_load_option(&lo, (u8 **)&opt[i].lo);
> +		if (!opt[i].size) {
> +			ret = EFI_OUT_OF_RESOURCES;
> +			free(dev_name);
> +			goto out;
> +		}
> +		free(dev_name);
> +	}
> +
> +out:
> +	return ret;
> +}
> +
> +efi_status_t efi_bootmenu_delete_invalid_boot_option(
> +			struct efi_bootmenu_media_boot_option *opt,
> +			efi_status_t count)
> +{
> +	u16 *bootorder;
> +	u32 i, j;
> +	efi_status_t ret;
> +	efi_uintn_t num, size, bootorder_size;
> +	void *load_option;
> +	struct efi_load_option lo;
> +	u16 varname[] = u"Boot####";
> +
> +	bootorder = efi_get_var(u"BootOrder", &efi_global_variable_guid, &bootorder_size);
> +	if (!bootorder)
> +		return EFI_NOT_FOUND;
> +
> +	num = bootorder_size / sizeof(u16);
> +	for (i = 0; i < num;) {
> +		efi_uintn_t tmp;
> +
> +		efi_create_indexed_name(varname, sizeof(varname),
> +					"Boot", bootorder[i]);
> +		load_option = efi_get_var(varname, &efi_global_variable_guid, &size);
> +		if (!load_option)
> +			goto next;
> +
> +		tmp = size;
> +		ret = efi_deserialize_load_option(&lo, load_option, &tmp);
> +		if (ret != EFI_SUCCESS)
> +			goto next;
> +
> +		if (u16_strncmp((u16 *)lo.optional_data, BOOTMENU_AUTO_ADD_OPTION_DATA_U16,

You should convert the lo.optional_data to a u16 before doing the check
here, other wise this might cause an unaligned access

> +				u16_strlen(BOOTMENU_AUTO_ADD_OPTION_DATA_U16)) == 0) {
> +			for (j = 0; j < count; j++) {
> +				if (memcmp(opt[j].lo, load_option, size) == 0) {
> +					opt[j].exist = true;
> +					break;
> +				}
> +			}
> +
> +			if (j == count) {
> +				ret = delete_boot_option(bootorder, i, bootorder_size);
> +				if (ret != EFI_SUCCESS) {
> +					free(load_option);
> +					goto out;
> +				}
> +
> +				num--;
> +				bootorder_size -= sizeof(u16);
> +				free(load_option);
> +				continue;
> +			}
> +		}
> +next:
> +		free(load_option);
> +		i++;
> +	}
> +
> +out:
> +	return ret;
> +}
> -- 
> 2.17.1
> 

Thanks
/Ilias