[PATCH v5 16/17] bootmenu: add removable media entries
Heinrich Schuchardt
xypron.glpk at gmx.de
Thu Apr 28 18:53:07 CEST 2022
On 4/28/22 10:09, 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. This automatically generated UEFI boot option
> has the dedicated guid in the optional_data to distinguish it from
> the UEFI boot option user adds manually.
>
> This commit also provides the BOOT#### variable maintenance feature.
> Depending on the system hardware setup, some devices
> may not exist at a later system boot, so bootmenu checks the
> available device in each bootmenu invocation and automatically
> removes the BOOT#### variable corrensponding to the non-existent
> media device.
>
> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> ---
> Changes in v5:
> - Return EFI_SUCCESS if there is no BootOrder defined
> - correctly handle the case if no removable device found
> - use guid to identify the automatically generated entry by bootmenu
>
> Newly created in v4
>
> cmd/bootmenu.c | 94 +++++++++++++++
> include/efi_loader.h | 20 ++++
> lib/efi_loader/efi_bootmenu_maintenance.c | 139 ++++++++++++++++++++++
> 3 files changed, 253 insertions(+)
>
> diff --git a/cmd/bootmenu.c b/cmd/bootmenu.c
> index 860cb83182..970db3ee01 100644
> --- a/cmd/bootmenu.c
> +++ b/cmd/bootmenu.c
> @@ -396,6 +396,89 @@ static int is_blk_device_available(char *token)
> return -ENODEV;
> }
>
> +/**
> + * prepare_media_device_entry() - generate the media device entries
> + *
> + * This function enumerates all devices supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL
> + * and generate the bootmenu entries.
> + * This function also provide the BOOT#### variable maintenance for
> + * the media device entries.
> + * - Automatically create the BOOT#### variable for the newly detected device,
> + * this BOOT#### variable is distinguished by the special GUID
> + * stored in the EFI_LOAD_OPTION.optional_data
> + * - If the device is not attached to the system, the associated BOOT#### variable
> + * is automatically deleted.
> + *
> + * Return: status code
> + */
> +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);
> + 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;
> +}
> +
> /**
> * prepare_distro_boot_entry() - generate the distro boot entries
> *
> @@ -500,6 +583,7 @@ static int prepare_distro_boot_entry(struct bootmenu_data *menu,
> static struct bootmenu_data *bootmenu_create(int delay)
> {
> int ret;
> + efi_status_t efi_ret;
> unsigned short int i = 0;
> struct bootmenu_data *menu;
> struct bootmenu_entry *iter = NULL;
> @@ -523,6 +607,16 @@ 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.
> + */
> + efi_ret = prepare_media_device_entry();
> + if (efi_ret != EFI_SUCCESS && efi_ret != EFI_NOT_FOUND)
> + 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 533618341b..bef492ccb9 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -928,6 +928,22 @@ 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);
> @@ -1076,6 +1092,10 @@ 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 8c3f94c695..33b37fd11a 100644
> --- a/lib/efi_loader/efi_bootmenu_maintenance.c
> +++ b/lib/efi_loader/efi_bootmenu_maintenance.c
> @@ -26,6 +26,13 @@ static struct efi_simple_text_output_protocol *cout;
> #define EFI_BOOTMENU_BOOT_NAME_MAX 32
> #define EFI_BOOT_ORDER_MAX_SIZE_IN_DECIMAL 6
>
> +#define EFI_BOOTMENU_AUTO_GENERATED_ENTRY_GUID \
> + EFI_GUID(0x38c1acc1, 0x9fc0, 0x41f0, \
> + 0xb9, 0x01, 0xfa, 0x74, 0xd6, 0xd6, 0xe4, 0xde)
> +
> +static const efi_guid_t efi_guid_bootmenu_auto_generated =
> + EFI_BOOTMENU_AUTO_GENERATED_ENTRY_GUID;
> +
> typedef efi_status_t (*efi_bootmenu_entry_func)(void *data, bool *exit);
>
> /**
> @@ -1104,3 +1111,135 @@ 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++) {
> + char *optional_data;
> + 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);
> + /*
> + * Set the dedicated guid to optional_data, it is used to identify
> + * the boot option that automatically generated by the bootmenu.
> + * efi_serialize_load_option() expects optional_data is null-terminated
> + * utf8 string, so set the "dummystr" string to allocate enough space
> + * to store guid, instead of realloc the load_option.
> + *
> + * This will allocate 16 bytes for guid plus trailing 0x0000.
> + * The guid does not require trailing 0x0000, but it is for safety
> + * in case some program handle the optional_data as u16 string.
> + */
> + lo.optional_data = "dummystr";
Why do you want to reserve 18 bytes when 16 are enough for the GUID?
> + 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;
> + }
> + /* set the guid */
> + optional_data = (char *)opt[i].lo + (opt[i].size - u16_strsize(u"dummystr"));
> + memcpy(optional_data, &efi_guid_bootmenu_auto_generated, sizeof(efi_guid_t));
> + 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_SUCCESS; /* BootOrder is not defined, nothing to do */
> +
> + 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;
This copying of variables is superfluous. Just keep size.
> + ret = efi_deserialize_load_option(&lo, load_option, &tmp);
> + if (ret != EFI_SUCCESS)
> + goto next;
> +
> + if (guidcmp(lo.optional_data, &efi_guid_bootmenu_auto_generated) == 0) {
You must avoid a buffer overrun. Check size >= 16.
Best regards
Heinrich
> + 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;
> +}
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