[PATCH] efi_loader: Trigger capsule updates with automatically generated boot options
Balaji Selvanathan
balaji.selvanathan at oss.qualcomm.com
Thu Dec 4 05:42:35 CET 2025
On 12/2/2025 2:20 PM, Ilias Apalodimas wrote:
> The EFI spec in §8.5.5 says
> "The directory \EFI\UpdateCapsule is checked for capsules only within
> the EFI system partition on the device specified in the active boot
> option determine by reference to BootNext variable or BootOrder variable
> processing."
>
> Automatically generated boot options don't point to the ESP, they point to
> the disk itself and find_handle() won't match when searching for an ESP
> during a capsule update.
> This happens because find_handle() only matches device paths that are
> shorter or equal to the device path passed as an argument.
> Since the EFI spec allows it we want to allow capsule updates, when the
> boot option points to a disk, but that disk contains an ESP with a
> \EFI\UpdateCapsule directory.
>
> find_handle() implicitly changes it's behavior depending on the passed
> arguments as well. If the 'rem' ptr is not valid it will only search for
> an exact match. Otherwise it will match on the best match and return the
> remaining portion of the matched device path to 'rem'.
>
> Tweak this slightly and pass an enum with 3 options
> - EXACT - Exact match, as if 'rem' was NULL
> - SHORTER - Match a shorter device path and put the remainder in 'rem'
> - LONGER - Inverse the logic and match a longer device path. Put the
> remainder into 'rem'.
>
> To avoid any regressions, LONGER is only used during capsule updates and
> since 'rem' always carries the remainder of the matched device path we
> can plug it in with minimal changes.
>
> Reported-by: Balaji Selvanathan <balaji.selvanathan at oss.qualcomm.com>
> Reported-by: John Toomey <john.toomey at amd.com>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> ---
>
> John, Balaji, can you check if this fixes your problem?
Hi Ilias,
Thanks for this patch. This fixes the problem and have verified the patch.
Regards,
Balaji
>
> cmd/eficonfig.c | 2 +-
> include/efi_device_path.h | 10 +++---
> lib/efi_loader/efi_bootmgr.c | 6 ++--
> lib/efi_loader/efi_boottime.c | 5 +--
> lib/efi_loader/efi_capsule.c | 20 +++++++-----
> lib/efi_loader/efi_device_path.c | 55 +++++++++++++++++++++++++-------
> lib/efi_loader/efi_disk.c | 2 +-
> 7 files changed, 70 insertions(+), 30 deletions(-)
>
> diff --git a/cmd/eficonfig.c b/cmd/eficonfig.c
> index d8d946c87ac8..e317f3c90c14 100644
> --- a/cmd/eficonfig.c
> +++ b/cmd/eficonfig.c
> @@ -1321,7 +1321,7 @@ static efi_status_t prepare_file_selection_entry(struct efimenu *efi_menu, char
> return EFI_OUT_OF_RESOURCES;
>
> /* get the device name only when the user already selected the file path */
> - handle = efi_dp_find_obj(file_info->dp_volume, NULL, NULL);
> + handle = efi_dp_find_obj(file_info->dp_volume, NULL, NULL, false);
> if (handle) {
> ret = efi_disk_get_device_name(handle, devname, EFICONFIG_VOLUME_PATH_MAX);
> if (ret != EFI_SUCCESS)
> diff --git a/include/efi_device_path.h b/include/efi_device_path.h
> index aae85228f681..f9c538730c94 100644
> --- a/include/efi_device_path.h
> +++ b/include/efi_device_path.h
> @@ -73,13 +73,15 @@ struct efi_device_path *efi_dp_shorten(struct efi_device_path *dp);
> *
> * If @rem is provided, the handle with the longest partial match is returned.
> *
> - * @dp: device path to search
> - * @guid: GUID of protocol that must be installed on path or NULL
> - * @rem: pointer to receive remaining device path
> + * @dp: device path to search
> + * @guid: GUID of protocol that must be installed on path or NULL
> + * @rem: pointer to receive remaining device path
> + * @inversed_match: Match even if the dp is shorter. rem will stil hoild the
> + * remaining device path
> * Return: matching handle
> */
> efi_handle_t efi_dp_find_obj(struct efi_device_path *dp, const efi_guid_t *guid,
> - struct efi_device_path **rem);
> + struct efi_device_path **rem, bool inversed_match);
>
> /**
> * efi_dp_last_node() - Determine the last device path node before the end node
> diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> index a687f4d8e85c..df7500a94876 100644
> --- a/lib/efi_loader/efi_bootmgr.c
> +++ b/lib/efi_loader/efi_bootmgr.c
> @@ -84,7 +84,8 @@ struct efi_device_path *expand_media_path(struct efi_device_path *device_path)
> * booting from removable media.
> */
> handle = efi_dp_find_obj(device_path,
> - &efi_simple_file_system_protocol_guid, &rem);
> + &efi_simple_file_system_protocol_guid, &rem,
> + false);
> if (handle) {
> if (rem->type == DEVICE_PATH_TYPE_END) {
> char fname[30];
> @@ -625,7 +626,8 @@ static efi_status_t try_load_from_media(struct efi_device_path *file_path,
> struct efi_device_path *rem, *dp = NULL;
> struct efi_device_path *final_dp = file_path;
>
> - handle_blkdev = efi_dp_find_obj(file_path, &efi_block_io_guid, &rem);
> + handle_blkdev = efi_dp_find_obj(file_path, &efi_block_io_guid, &rem,
> + false);
> if (handle_blkdev) {
> if (rem->type == DEVICE_PATH_TYPE_END) {
> /* no file name present, try default file */
> diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
> index ddc935d22409..0391b92a8be4 100644
> --- a/lib/efi_loader/efi_boottime.c
> +++ b/lib/efi_loader/efi_boottime.c
> @@ -1816,7 +1816,8 @@ efi_status_t efi_setup_loaded_image(struct efi_device_path *device_path,
> info->system_table = &systab;
>
> if (device_path) {
> - info->device_handle = efi_dp_find_obj(device_path, NULL, NULL);
> + info->device_handle = efi_dp_find_obj(device_path, NULL, NULL,
> + false);
>
> dp = efi_dp_concat(device_path, file_path, 0);
> if (!dp) {
> @@ -2016,7 +2017,7 @@ efi_status_t efi_load_image_from_path(bool boot_policy,
> *size = 0;
>
> dp = file_path;
> - device = efi_dp_find_obj(dp, NULL, &rem);
> + device = efi_dp_find_obj(dp, NULL, &rem, false);
> ret = efi_search_protocol(device, &efi_simple_file_system_protocol_guid,
> NULL);
> if (ret == EFI_SUCCESS)
> diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c
> index eafc647f558f..103328c76a6e 100644
> --- a/lib/efi_loader/efi_capsule.c
> +++ b/lib/efi_loader/efi_capsule.c
> @@ -886,18 +886,18 @@ static efi_status_t get_dp_device(u16 *boot_var,
> * @dp device path
> * Return: true - yes, false - no
> */
> -static bool device_is_present_and_system_part(struct efi_device_path *dp)
> +static bool device_is_present_and_system_part(struct efi_device_path *dp,
> + struct efi_device_path **rem)
> {
> efi_handle_t handle;
> - struct efi_device_path *rem;
>
> /* Check device exists */
> - handle = efi_dp_find_obj(dp, NULL, NULL);
> + handle = efi_dp_find_obj(dp, NULL, NULL, false);
> if (!handle)
> return false;
>
> /* Check device is on system partition */
> - handle = efi_dp_find_obj(dp, &efi_system_partition_guid, &rem);
> + handle = efi_dp_find_obj(dp, &efi_system_partition_guid, rem, true);
> if (!handle)
> return false;
>
> @@ -919,7 +919,7 @@ static efi_status_t find_boot_device(void)
> efi_uintn_t size;
> int i, num;
> struct efi_simple_file_system_protocol *volume;
> - struct efi_device_path *boot_dev = NULL;
> + struct efi_device_path *boot_dev = NULL, *rem = NULL;
> efi_status_t ret;
>
> /* find active boot device in BootNext */
> @@ -940,7 +940,7 @@ static efi_status_t find_boot_device(void)
>
> ret = get_dp_device(boot_var16, &boot_dev);
> if (ret == EFI_SUCCESS) {
> - if (device_is_present_and_system_part(boot_dev)) {
> + if (device_is_present_and_system_part(boot_dev, &rem)) {
> goto found;
> } else {
> efi_free_pool(boot_dev);
> @@ -967,7 +967,7 @@ skip:
> if (ret != EFI_SUCCESS)
> continue;
>
> - if (device_is_present_and_system_part(boot_dev))
> + if (device_is_present_and_system_part(boot_dev, &rem))
> break;
>
> efi_free_pool(boot_dev);
> @@ -977,7 +977,11 @@ found:
> if (boot_dev) {
> log_debug("Boot device %pD\n", boot_dev);
>
> - volume = efi_fs_from_path(boot_dev);
> + if (rem->type == DEVICE_PATH_TYPE_END)
> + volume = efi_fs_from_path(boot_dev);
> + else
> + volume = efi_fs_from_path(rem);
> +
> if (!volume)
> ret = EFI_DEVICE_ERROR;
> else
> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
> index b3fb20b2501e..ad7f452c411b 100644
> --- a/lib/efi_loader/efi_device_path.c
> +++ b/lib/efi_loader/efi_device_path.c
> @@ -30,6 +30,12 @@ const struct efi_device_path EFI_DP_END = {
> .length = sizeof(EFI_DP_END),
> };
>
> +enum match {
> + EXACT,
> + SHORTER,
> + LONGER
> +};
> +
> #if defined(CONFIG_MMC)
> /*
> * Determine if an MMC device is an SD card.
> @@ -109,10 +115,11 @@ struct efi_device_path *efi_dp_shorten(struct efi_device_path *dp)
> */
> static efi_handle_t find_handle(struct efi_device_path *dp,
> const efi_guid_t *guid, bool short_path,
> - struct efi_device_path **rem)
> + struct efi_device_path **rem,
> + enum match match)
> {
> efi_handle_t handle, best_handle = NULL;
> - efi_uintn_t len, best_len = 0;
> + efi_uintn_t len, match_len = 0, best_len = 0;
>
> len = efi_dp_instance_size(dp);
>
> @@ -137,22 +144,35 @@ static efi_handle_t find_handle(struct efi_device_path *dp,
> if (!dp_current)
> continue;
> }
> - len_current = efi_dp_instance_size(dp_current);
> - if (rem) {
> +
> + match_len = len_current = efi_dp_instance_size(dp_current);
> + switch (match) {
> + case EXACT:
> + if (len_current != len)
> + continue;
> + break;
> + case SHORTER:
> if (len_current > len)
> continue;
> - } else {
> - if (len_current != len)
> + break;
> + case LONGER:
> + if (len_current < len)
> continue;
> + match_len = len;
> + break;
> }
> - if (memcmp(dp_current, dp, len_current))
> +
> + if (memcmp(dp_current, dp, match_len))
> continue;
> if (!rem)
> return handle;
> if (len_current > best_len) {
> best_len = len_current;
> best_handle = handle;
> - *rem = (void*)((u8 *)dp + len_current);
> + if (len_current <= len)
> + *rem = (void *)((uintptr_t)dp + len_current);
> + else
> + *rem = (void *)((uintptr_t)dp_current + match_len);
> }
> }
> return best_handle;
> @@ -160,14 +180,25 @@ static efi_handle_t find_handle(struct efi_device_path *dp,
>
> efi_handle_t efi_dp_find_obj(struct efi_device_path *dp,
> const efi_guid_t *guid,
> - struct efi_device_path **rem)
> + struct efi_device_path **rem, bool inversed_match)
> {
> efi_handle_t handle;
>
> - handle = find_handle(dp, guid, false, rem);
> + handle = find_handle(dp, guid, false, rem, EXACT);
> if (!handle)
> - /* Match short form device path */
> - handle = find_handle(dp, guid, true, rem);
> + handle = find_handle(dp, guid, true, rem, EXACT);
> + if (handle)
> + return handle;
> +
> + handle = find_handle(dp, guid, false, rem, SHORTER);
> + if (!handle)
> + handle = find_handle(dp, guid, true, rem, SHORTER);
> +
> + if (inversed_match && !handle) {
> + handle = find_handle(dp, guid, false, rem, LONGER);
> + if (!handle)
> + handle = find_handle(dp, guid, true, rem, LONGER);
> + }
>
> return handle;
> }
> diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
> index 130c4db9606f..0d3d7c187d72 100644
> --- a/lib/efi_loader/efi_disk.c
> +++ b/lib/efi_loader/efi_disk.c
> @@ -339,7 +339,7 @@ efi_fs_from_path(struct efi_device_path *full_path)
> efi_free_pool(file_path);
>
> /* Get the EFI object for the partition */
> - efiobj = efi_dp_find_obj(device_path, NULL, NULL);
> + efiobj = efi_dp_find_obj(device_path, NULL, NULL, false);
> efi_free_pool(device_path);
> if (!efiobj)
> return NULL;
> --
> 2.51.0
>
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