[PATCH v5 16/17] bootmenu: add removable media entries
Masahisa Kojima
masahisa.kojima at linaro.org
Mon May 9 10:23:11 CEST 2022
On Fri, 29 Apr 2022 at 01:53, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> 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?
OK, I will only allocate 16 bytes for 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.
I don't catch your point.
This efi_bootmenu_delete_invalid_boot_option() function
does not copy the variable, only keeps the variable 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.
Yes, I need to check the size of optional_data.
Thanks,
Masahisa Kojima
>
> 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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