This patch adds functionality to pass device-specific information that will be hashed to generate a persistent unique machine id. It is then available as global.machine_id. It can be overwritten with nv.machine_id if necessary. Passing the machine id to the kernel is done in a separate patch.
Note: if multiple sources provide hashable device-specific information (via machine_id_set_hashable()) the information provided by the last call prior to the late initcall set_machine_id() is used to generate the machine id from. Thus when updating barebox the machine id might change. Signed-off-by: Bastian Krause <[email protected]> --- common/Kconfig | 18 ++++++++++++ common/Makefile | 1 + common/machine_id.c | 69 ++++++++++++++++++++++++++++++++++++++++++++ include/machine_id.h | 16 ++++++++++ 4 files changed, 104 insertions(+) create mode 100644 common/machine_id.c create mode 100644 include/machine_id.h diff --git a/common/Kconfig b/common/Kconfig index cafaadb3d4..7c56eb469e 100644 --- a/common/Kconfig +++ b/common/Kconfig @@ -982,6 +982,24 @@ config RESET_SOURCE of the reset and why the bootloader is currently running. It can be useful for any kind of system recovery or repair. +config MACHINE_ID + bool "pass machine-id to kernel" + depends on FLEXIBLE_BOOTARGS + depends on SHA1 + help + Sets the linux.bootargs.machine_id global variable with a value of + systemd.machine_id=UID. The UID is a persistent device-specific + id. It is a hash over device-specific information provided by various + sources. + + Note: if multiple sources provide hashable device-specific information + (via machine_id_set_hashable()) the information provided by the last call + prior to the late initcall set_machine_id() is used to generate the + machine id from. Thus when updating barebox the machine id might change. + + Note: if no hashable information is available no machine id will be passed + to the kernel. + endmenu menu "Debugging" diff --git a/common/Makefile b/common/Makefile index a284655fc1..10960169f9 100644 --- a/common/Makefile +++ b/common/Makefile @@ -11,6 +11,7 @@ obj-y += bootsource.o obj-$(CONFIG_ELF) += elf.o obj-y += restart.o obj-y += poweroff.o +obj-$(CONFIG_MACHINE_ID) += machine_id.o obj-$(CONFIG_AUTO_COMPLETE) += complete.o obj-y += version.o obj-$(CONFIG_BAREBOX_UPDATE) += bbu.o diff --git a/common/machine_id.c b/common/machine_id.c new file mode 100644 index 0000000000..e678bb7fe8 --- /dev/null +++ b/common/machine_id.c @@ -0,0 +1,69 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019 Pengutronix, Bastian Krause <[email protected]> + */ + +#include <common.h> +#include <init.h> +#include <digest.h> +#include <globalvar.h> +#include <magicvar.h> +#include <crypto/sha.h> +#include <machine_id.h> + +#define MACHINE_ID_LENGTH 32 + +static void *__machine_id_hashable; +static size_t __machine_id_hashable_length; + + +void machine_id_set_hashable(const void *hashable, size_t len) +{ + + __machine_id_hashable = xmemdup(hashable, len); + __machine_id_hashable_length = len; +} + +static int machine_id_set_bootarg(void) +{ + struct digest *digest = NULL; + unsigned char machine_id[SHA1_DIGEST_SIZE]; + char hex_machine_id[MACHINE_ID_LENGTH]; + char *env_machine_id; + int ret = 0; + + /* nothing to do if no hashable information provided */ + if (!__machine_id_hashable) + goto out; + + digest = digest_alloc_by_algo(HASH_ALGO_SHA1); + ret = digest_init(digest); + if (ret) + goto out; + + ret = digest_update(digest, __machine_id_hashable, + __machine_id_hashable_length); + if (ret) + goto out; + + ret = digest_final(digest, machine_id); + if (ret) + goto out; + + /* use the first 16 bytes of the sha1 hash as the machine id */ + bin2hex(hex_machine_id, machine_id, MACHINE_ID_LENGTH/2); + + env_machine_id = basprintf("%.*s", MACHINE_ID_LENGTH, hex_machine_id); + globalvar_add_simple("machine_id", env_machine_id); + free(env_machine_id); + +out: + globalvar_add_simple("machine_id", NULL); + + digest_free(digest); + return ret; + +} +late_initcall(machine_id_set_bootarg); + +BAREBOX_MAGICVAR_NAMED(global_machine_id, global.machine_id, "Persistent device-specific, hexadecimal, 32-character id"); diff --git a/include/machine_id.h b/include/machine_id.h new file mode 100644 index 0000000000..31d5e0bb28 --- /dev/null +++ b/include/machine_id.h @@ -0,0 +1,16 @@ +#ifndef __MACHINE_ID_H__ +#define __MACHINE_ID_H__ + +#if IS_ENABLED(CONFIG_MACHINE_ID) + +void machine_id_set_hashable(const void *hashable, size_t len); + +#else + +static inline void machine_id_set_hashable(const void *hashable, size_t len) +{ +} + +#endif /* CONFIG_MACHINE_ID */ + +#endif /* __MACHINE_ID_H__ */ -- 2.23.0 _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
