Add a configuration option to measure the boot through the bootm function. Add the measurement state to the booti and bootz paths as well.
Signed-off-by: Eddie James eajames@linux.ibm.com Reviewed-by: Simon Glass sjg@chromium.org --- Changes since v8: - Added a configuration option to select to ignore any existing event log. This would only be selected for systems that know that U-Boot is the first stage bootloader. This is necessary because the reserved memory region may persist through resets and so U-Boot attempts to append to the previous boot's log.
Changes since v6: - Added comment for bootm_measure - Fixed line length in bootm_measure
boot/Kconfig | 32 +++++++++++++++++++++ boot/bootm.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++ cmd/booti.c | 1 + cmd/bootm.c | 2 ++ cmd/bootz.c | 1 + include/bootm.h | 11 ++++++++ include/image.h | 1 + 7 files changed, 122 insertions(+)
diff --git a/boot/Kconfig b/boot/Kconfig index a01e6cb8aa..abbc72f4cf 100644 --- a/boot/Kconfig +++ b/boot/Kconfig @@ -685,6 +685,38 @@ config LEGACY_IMAGE_FORMAT loaded. If a board needs the legacy image format support in this case, enable it here.
+config MEASURED_BOOT + bool "Measure boot images and configuration to TPM and event log" + depends on HASH && TPM_V2 + help + This option enables measurement of the boot process. Measurement + involves creating cryptographic hashes of the binary images that + are booting and storing them in the TPM. In addition, a log of + these hashes is stored in memory for the OS to verify the booted + images and configuration. Enable this if the OS has configured + some memory area for the event log and you intend to use some + attestation tools on your system. + +if MEASURED_BOOT + config MEASURE_DEVICETREE + bool "Measure the devicetree image" + default y if MEASURED_BOOT + help + On some platforms, the devicetree is not static as it may contain + random MAC addresses or other such data that changes each boot. + Therefore, it should not be measured into the TPM. In that case, + disable the measurement here. + + config MEASURE_IGNORE_LOG + bool "Ignore the existing event log" + default n + help + On platforms that use an event log memory region that persists + through system resets and are the first stage bootloader, then + this option should be enabled to ignore any existing data in the + event log memory region. +endif # MEASURED_BOOT + config SUPPORT_RAW_INITRD bool "Enable raw initrd images" help diff --git a/boot/bootm.c b/boot/bootm.c index b1c3afe0a3..11b6b3c292 100644 --- a/boot/bootm.c +++ b/boot/bootm.c @@ -22,6 +22,7 @@ #include <asm/global_data.h> #include <asm/io.h> #include <linux/sizes.h> +#include <tpm-v2.h> #if defined(CONFIG_CMD_USB) #include <usb.h> #endif @@ -673,6 +674,75 @@ int bootm_process_cmdline_env(int flags) return 0; }
+int bootm_measure(struct bootm_headers *images) +{ + int ret = 0; + + /* Skip measurement if EFI is going to do it */ + if (images->os.os == IH_OS_EFI && + IS_ENABLED(CONFIG_EFI_TCG2_PROTOCOL) && + IS_ENABLED(CONFIG_BOOTM_EFI)) + return ret; + + if (IS_ENABLED(CONFIG_MEASURED_BOOT)) { + struct tcg2_event_log elog; + struct udevice *dev; + void *initrd_buf; + void *image_buf; + const char *s; + u32 rd_len; + bool ign; + + elog.log_size = 0; + ign = IS_ENABLED(CONFIG_MEASURE_IGNORE_LOG); + ret = tcg2_measurement_init(&dev, &elog, ign); + if (ret) + return ret; + + image_buf = map_sysmem(images->os.image_start, + images->os.image_len); + ret = tcg2_measure_data(dev, &elog, 8, images->os.image_len, + image_buf, EV_COMPACT_HASH, + strlen("linux") + 1, (u8 *)"linux"); + if (ret) + goto unmap_image; + + rd_len = images->rd_end - images->rd_start; + initrd_buf = map_sysmem(images->rd_start, rd_len); + ret = tcg2_measure_data(dev, &elog, 9, rd_len, initrd_buf, + EV_COMPACT_HASH, strlen("initrd") + 1, + (u8 *)"initrd"); + if (ret) + goto unmap_initrd; + + if (IS_ENABLED(CONFIG_MEASURE_DEVICETREE)) { + ret = tcg2_measure_data(dev, &elog, 0, images->ft_len, + (u8 *)images->ft_addr, + EV_TABLE_OF_DEVICES, + strlen("dts") + 1, + (u8 *)"dts"); + if (ret) + goto unmap_initrd; + } + + s = env_get("bootargs"); + if (!s) + s = ""; + ret = tcg2_measure_data(dev, &elog, 1, strlen(s) + 1, (u8 *)s, + EV_PLATFORM_CONFIG_FLAGS, + strlen(s) + 1, (u8 *)s); + +unmap_initrd: + unmap_sysmem(initrd_buf); + +unmap_image: + unmap_sysmem(image_buf); + tcg2_measurement_term(dev, &elog, ret != 0); + } + + return ret; +} + /** * Execute selected states of the bootm command. * @@ -724,6 +794,10 @@ int do_bootm_states(struct cmd_tbl *cmdtp, int flag, int argc, if (!ret && (states & BOOTM_STATE_FINDOTHER)) ret = bootm_find_other(cmdtp, flag, argc, argv);
+ if (IS_ENABLED(CONFIG_MEASURED_BOOT) && !ret && + (states & BOOTM_STATE_MEASURE)) + bootm_measure(images); + /* Load the OS */ if (!ret && (states & BOOTM_STATE_LOADOS)) { iflag = bootm_disable_interrupts(); diff --git a/cmd/booti.c b/cmd/booti.c index 6ac39193db..659bb10549 100644 --- a/cmd/booti.c +++ b/cmd/booti.c @@ -127,6 +127,7 @@ int do_booti(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) #ifdef CONFIG_SYS_BOOT_RAMDISK_HIGH BOOTM_STATE_RAMDISK | #endif + BOOTM_STATE_MEASURE | BOOTM_STATE_OS_PREP | BOOTM_STATE_OS_FAKE_GO | BOOTM_STATE_OS_GO, &images, 1); diff --git a/cmd/bootm.c b/cmd/bootm.c index 7968415b6d..2bf2e9f676 100644 --- a/cmd/bootm.c +++ b/cmd/bootm.c @@ -147,6 +147,8 @@ int do_bootm(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) BOOTM_STATE_OS_GO; if (IS_ENABLED(CONFIG_SYS_BOOT_RAMDISK_HIGH)) states |= BOOTM_STATE_RAMDISK; + if (IS_ENABLED(CONFIG_MEASURED_BOOT)) + states |= BOOTM_STATE_MEASURE; if (IS_ENABLED(CONFIG_PPC) || IS_ENABLED(CONFIG_MIPS)) states |= BOOTM_STATE_OS_CMDLINE; ret = do_bootm_states(cmdtp, flag, argc, argv, states, &images, 1); diff --git a/cmd/bootz.c b/cmd/bootz.c index f1423573d2..87922bfc3c 100644 --- a/cmd/bootz.c +++ b/cmd/bootz.c @@ -81,6 +81,7 @@ int do_bootz(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) #ifdef CONFIG_SYS_BOOT_RAMDISK_HIGH BOOTM_STATE_RAMDISK | #endif + BOOTM_STATE_MEASURE | BOOTM_STATE_OS_PREP | BOOTM_STATE_OS_FAKE_GO | BOOTM_STATE_OS_GO, &images, 1); diff --git a/include/bootm.h b/include/bootm.h index c3c7336207..10a1bd65a7 100644 --- a/include/bootm.h +++ b/include/bootm.h @@ -56,6 +56,17 @@ ulong bootm_disable_interrupts(void); int bootm_find_images(int flag, int argc, char *const argv[], ulong start, ulong size);
+/* + * Measure the boot images. Measurement is the process of hashing some binary + * data and storing it into secure memory, i.e. TPM PCRs. In addition, each + * measurement is logged into the platform event log such that the operating + * system can access it and perform attestation of the boot. + * + * @images: The structure containing the various images to boot (linux, + * initrd, dts, etc.) + */ +int bootm_measure(struct bootm_headers *images); + int do_bootm_states(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[], int states, struct bootm_headers *images, int boot_progress); diff --git a/include/image.h b/include/image.h index 5f85bf84a2..2e3cf839ee 100644 --- a/include/image.h +++ b/include/image.h @@ -409,6 +409,7 @@ struct bootm_headers { #define BOOTM_STATE_OS_FAKE_GO 0x00000200 /* 'Almost' run the OS */ #define BOOTM_STATE_OS_GO 0x00000400 #define BOOTM_STATE_PRE_LOAD 0x00000800 +#define BOOTM_STATE_MEASURE 0x00001000 int state;
#if defined(CONFIG_LMB) && !defined(USE_HOSTCC)