[PATCH v3 0/2] efi_loader: identify EFI system partition
For storing UEFI variables we need to know where the EFI system partition is located.
With the patches the first available EFI system partition is determined both for MBR and GPT partition tables.
v3: adjust gpt command adjust commit message v2: BIT() macro to define bit mask
Heinrich Schuchardt (2): part: detect EFI system partition efi_loader: identify EFI system partition
cmd/gpt.c | 4 ++-- disk/part_dos.c | 14 ++++++++++---- disk/part_efi.c | 16 ++++++++++------ include/efi_loader.h | 7 +++++++ include/part.h | 11 ++++++++++- lib/efi_loader/efi_disk.c | 20 ++++++++++++++++++++ 6 files changed, 59 insertions(+), 13 deletions(-)
-- 2.26.1
Up to now for MBR and GPT partitions the info field 'bootable' was set to 1 if either the partition was an EFI system partition or the bootable flag was set.
Turn info field 'bootable' into a bit mask with separate bits for bootable and EFI system partition.
This will allow us to identify the EFI system partition in the UEFI sub-system.
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- v3: adjust gpt command to use only the boot flag not the EFI system partition v2: used BIT() macro to define bit mask --- cmd/gpt.c | 4 ++-- disk/part_dos.c | 14 ++++++++++---- disk/part_efi.c | 16 ++++++++++------ include/part.h | 11 ++++++++++- 4 files changed, 32 insertions(+), 13 deletions(-)
diff --git a/cmd/gpt.c b/cmd/gpt.c index efaf1bcecb..b94f0051cd 100644 --- a/cmd/gpt.c +++ b/cmd/gpt.c @@ -245,7 +245,7 @@ static void print_gpt_info(void) printf("Block size %lu, name %s\n", curr->gpt_part_info.blksz, curr->gpt_part_info.name); printf("Type %s, bootable %d\n", curr->gpt_part_info.type, - curr->gpt_part_info.bootable); + curr->gpt_part_info.bootable & PART_BOOTABLE); #ifdef CONFIG_PARTITION_UUIDS printf("UUID %s\n", curr->gpt_part_info.uuid); #endif @@ -535,7 +535,7 @@ static int set_gpt_info(struct blk_desc *dev_desc,
/* bootable */ if (found_key(tok, "bootable")) - parts[i].bootable = 1; + parts[i].bootable = PART_BOOTABLE; }
*parts_count = p_count; diff --git a/disk/part_dos.c b/disk/part_dos.c index 83ff40d310..813379f851 100644 --- a/disk/part_dos.c +++ b/disk/part_dos.c @@ -45,9 +45,15 @@ static inline int is_extended(int part_type) part_type == 0x85); }
-static inline int is_bootable(dos_partition_t *p) +static int get_bootable(dos_partition_t *p) { - return (p->sys_ind == 0xef) || (p->boot_ind == 0x80); + int ret = 0; + + if (p->sys_ind == 0xef) + ret |= PART_EFI_SYSTEM_PARTITION; + if (p->boot_ind == 0x80) + ret |= PART_BOOTABLE; + return ret; }
static void print_one_part(dos_partition_t *p, lbaint_t ext_part_sector, @@ -60,7 +66,7 @@ static void print_one_part(dos_partition_t *p, lbaint_t ext_part_sector, "u\t%08x-%02x\t%02x%s%s\n", part_num, lba_start, lba_size, disksig, part_num, p->sys_ind, (is_extended(p->sys_ind) ? " Extd" : ""), - (is_bootable(p) ? " Boot" : "")); + (get_bootable(p) ? " Boot" : "")); }
static int test_block_type(unsigned char *buffer) @@ -258,7 +264,7 @@ static int part_get_info_extended(struct blk_desc *dev_desc, (char *)info->name); /* sprintf(info->type, "%d, pt->sys_ind); */ strcpy((char *)info->type, "U-Boot"); - info->bootable = is_bootable(pt); + info->bootable = get_bootable(pt); #if CONFIG_IS_ENABLED(PARTITION_UUIDS) sprintf(info->uuid, "%08x-%02x", disksig, part_num); #endif diff --git a/disk/part_efi.c b/disk/part_efi.c index b2e157d9c1..83876a7bd9 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -71,11 +71,15 @@ static char *print_efiname(gpt_entry *pte)
static const efi_guid_t system_guid = PARTITION_SYSTEM_GUID;
-static inline int is_bootable(gpt_entry *p) +static int get_bootable(gpt_entry *p) { - return p->attributes.fields.legacy_bios_bootable || - !memcmp(&(p->partition_type_guid), &system_guid, - sizeof(efi_guid_t)); + int ret = 0; + + if (!memcmp(&p->partition_type_guid, &system_guid, sizeof(efi_guid_t))) + ret |= PART_EFI_SYSTEM_PARTITION; + if (p->attributes.fields.legacy_bios_bootable) + ret |= PART_BOOTABLE; + return ret; }
static int validate_gpt_header(gpt_header *gpt_h, lbaint_t lba, @@ -286,7 +290,7 @@ int part_get_info_efi(struct blk_desc *dev_desc, int part, snprintf((char *)info->name, sizeof(info->name), "%s", print_efiname(&gpt_pte[part - 1])); strcpy((char *)info->type, "U-Boot"); - info->bootable = is_bootable(&gpt_pte[part - 1]); + info->bootable = get_bootable(&gpt_pte[part - 1]); #if CONFIG_IS_ENABLED(PARTITION_UUIDS) uuid_bin_to_str(gpt_pte[part - 1].unique_partition_guid.b, info->uuid, UUID_STR_FORMAT_GUID); @@ -501,7 +505,7 @@ int gpt_fill_pte(struct blk_desc *dev_desc, memset(&gpt_e[i].attributes, 0, sizeof(gpt_entry_attributes));
- if (partitions[i].bootable) + if (partitions[i].bootable & PART_BOOTABLE) gpt_e[i].attributes.fields.legacy_bios_bootable = 1;
/* partition name */ diff --git a/include/part.h b/include/part.h index 0b5cf3d5e8..3693527397 100644 --- a/include/part.h +++ b/include/part.h @@ -51,13 +51,22 @@ struct block_drvr { #define PART_TYPE_LEN 32 #define MAX_SEARCH_PARTITIONS 64
+#define PART_BOOTABLE ((int)BIT(0)) +#define PART_EFI_SYSTEM_PARTITION ((int)BIT(1)) + typedef struct disk_partition { lbaint_t start; /* # of first block in partition */ lbaint_t size; /* number of blocks in partition */ ulong blksz; /* block size in bytes */ uchar name[PART_NAME_LEN]; /* partition name */ uchar type[PART_TYPE_LEN]; /* string type description */ - int bootable; /* Active/Bootable flag is set */ + /* + * The bootable is a bitmask with the following fields: + * + * PART_BOOTABLE the MBR bootable flag is set + * PART_EFI_SYSTEM_PARTITION the partition is an EFI system partition + */ + int bootable; #if CONFIG_IS_ENABLED(PARTITION_UUIDS) char uuid[UUID_STR_LEN + 1]; /* filesystem UUID as string, if exists */ #endif -- 2.26.1
In subsequent patches UEFI variables shalled be stored on the EFI system partition. Hence we need to identify the EFI system partition.
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- v3: adjust commit message v2: no change --- include/efi_loader.h | 7 +++++++ lib/efi_loader/efi_disk.c | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/efi_loader.h b/include/efi_loader.h index 0ba9a1f702..b7bccf50b3 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -47,6 +47,13 @@ static inline void *guidcpy(void *dst, const void *src) /* Root node */ extern efi_handle_t efi_root;
+/* EFI system partition */ +extern struct efi_system_partition { + enum if_type if_type; + int devnum; + u8 part; +} efi_system_partition; + int __efi_entry_check(void); int __efi_exit_check(void); const char *__efi_nesting(void); diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c index fd8fe17567..fd3df80b0b 100644 --- a/lib/efi_loader/efi_disk.c +++ b/lib/efi_loader/efi_disk.c @@ -13,6 +13,8 @@ #include <part.h> #include <malloc.h>
+struct efi_system_partition efi_system_partition; + const efi_guid_t efi_block_io_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
/** @@ -418,6 +420,24 @@ static efi_status_t efi_disk_add_dev( diskobj->ops.media = &diskobj->media; if (disk) *disk = diskobj; + + /* Store first EFI system partition */ + if (part && !efi_system_partition.if_type) { + int r; + disk_partition_t info; + + r = part_get_info(desc, part, &info); + if (r) + return EFI_DEVICE_ERROR; + if (info.bootable & PART_EFI_SYSTEM_PARTITION) { + efi_system_partition.if_type = desc->if_type; + efi_system_partition.devnum = desc->devnum; + efi_system_partition.part = part; + EFI_PRINT("EFI system partition: %s %d:%d\n", + blk_get_if_type_name(desc->if_type), + desc->devnum, part); + } + } return EFI_SUCCESS; }
-- 2.26.1
Heinrich,
On Wed, Apr 22, 2020 at 07:51:33PM +0200, Heinrich Schuchardt wrote:
In subsequent patches UEFI variables shalled be stored on the EFI system partition. Hence we need to identify the EFI system partition.
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de
v3: adjust commit message
I said 'no' along with my counter proposals[1], and you haven't replied yet.
[1] https://lists.denx.de/pipermail/u-boot/2020-April/406678.html
-Takahiro Akashi
v2: no change
include/efi_loader.h | 7 +++++++ lib/efi_loader/efi_disk.c | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/efi_loader.h b/include/efi_loader.h index 0ba9a1f702..b7bccf50b3 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -47,6 +47,13 @@ static inline void *guidcpy(void *dst, const void *src) /* Root node */ extern efi_handle_t efi_root;
+/* EFI system partition */ +extern struct efi_system_partition {
- enum if_type if_type;
- int devnum;
- u8 part;
+} efi_system_partition;
int __efi_entry_check(void); int __efi_exit_check(void); const char *__efi_nesting(void); diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c index fd8fe17567..fd3df80b0b 100644 --- a/lib/efi_loader/efi_disk.c +++ b/lib/efi_loader/efi_disk.c @@ -13,6 +13,8 @@ #include <part.h> #include <malloc.h>
+struct efi_system_partition efi_system_partition;
const efi_guid_t efi_block_io_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
/** @@ -418,6 +420,24 @@ static efi_status_t efi_disk_add_dev( diskobj->ops.media = &diskobj->media; if (disk) *disk = diskobj;
- /* Store first EFI system partition */
- if (part && !efi_system_partition.if_type) {
int r;disk_partition_t info;r = part_get_info(desc, part, &info);if (r)return EFI_DEVICE_ERROR;if (info.bootable & PART_EFI_SYSTEM_PARTITION) {efi_system_partition.if_type = desc->if_type;efi_system_partition.devnum = desc->devnum;efi_system_partition.part = part;EFI_PRINT("EFI system partition: %s %d:%d\n",blk_get_if_type_name(desc->if_type),desc->devnum, part);}- } return EFI_SUCCESS;
}
-- 2.26.1
On 4/23/20 2:19 AM, AKASHI Takahiro wrote:
Heinrich,
On Wed, Apr 22, 2020 at 07:51:33PM +0200, Heinrich Schuchardt wrote:
In subsequent patches UEFI variables shalled be stored on the EFI system partition. Hence we need to identify the EFI system partition.
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de
v3: adjust commit message
I said 'no' along with my counter proposals[1], and you haven't replied yet.
[1] https://lists.denx.de/pipermail/u-boot/2020-April/406678.html
For some scenarios it may make sense to be able to specify a boot device containing variables via a Kconfig option. This patch does not stop us for implementing this.
If you take a Linux distribution that can either be installed on eMMC or on an SD-card of the same board, autodetection of the EFI system partition may be a more a better choice than providing multiple U-Boot builds.
Both approaches have there merits and both could be enabled via Kconfig.
Best regards
Heinrich
-Takahiro Akashi
v2: no change
include/efi_loader.h | 7 +++++++ lib/efi_loader/efi_disk.c | 20 ++++++++++++++++++++ 2 files changed, 27 insertions(+)
diff --git a/include/efi_loader.h b/include/efi_loader.h index 0ba9a1f702..b7bccf50b3 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -47,6 +47,13 @@ static inline void *guidcpy(void *dst, const void *src) /* Root node */ extern efi_handle_t efi_root;
+/* EFI system partition */ +extern struct efi_system_partition {
- enum if_type if_type;
- int devnum;
- u8 part;
+} efi_system_partition;
int __efi_entry_check(void); int __efi_exit_check(void); const char *__efi_nesting(void); diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c index fd8fe17567..fd3df80b0b 100644 --- a/lib/efi_loader/efi_disk.c +++ b/lib/efi_loader/efi_disk.c @@ -13,6 +13,8 @@ #include <part.h> #include <malloc.h>
+struct efi_system_partition efi_system_partition;
const efi_guid_t efi_block_io_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
/** @@ -418,6 +420,24 @@ static efi_status_t efi_disk_add_dev( diskobj->ops.media = &diskobj->media; if (disk) *disk = diskobj;
- /* Store first EFI system partition */
- if (part && !efi_system_partition.if_type) {
int r;disk_partition_t info;r = part_get_info(desc, part, &info);if (r)return EFI_DEVICE_ERROR;if (info.bootable & PART_EFI_SYSTEM_PARTITION) {efi_system_partition.if_type = desc->if_type;efi_system_partition.devnum = desc->devnum;efi_system_partition.part = part;EFI_PRINT("EFI system partition: %s %d:%d\n",blk_get_if_type_name(desc->if_type),desc->devnum, part);}- } return EFI_SUCCESS;
}
-- 2.26.1
On Wed, Apr 22, 2020 at 07:51:33PM +0200, Heinrich Schuchardt wrote:
In subsequent patches UEFI variables shalled be stored on the EFI system partition. Hence we need to identify the EFI system partition.
Hi,
I'm sorry, but, I'm wondering if this is a good idea? The EFI system partition is just some FAT-Partition, and if the system is using secure boot and someone happens to manage to mount that partition, then the variables can be changed pretty easily.
Also I guess changing variables using the Runtime Services would then try to access the partition? What if the OS is accessing the partition as well at the same time?
I'm currently storing the U-Boot environment, including the UEFI Secure Boot environment, on a eMMC partition with a temporary write protect. This means I cannot change the variables with Runtime Services after leaving U-Boot, but it also means that an exploit on my OS doesn't allow the attacker to change the variables, because they are write- protected until the machine reboots and enters U-Boot again.
I hope we will keep the possibility to store the UEFI variables in the U-Boot environment, or in some raw sector on the MMC partition, since otherwise the safety of those variables could be in danger.
Best regards, Patrick
participants (3)
-
AKASHI Takahiro -
Heinrich Schuchardt -
Patrick Wildt