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SubjectRe: [PATCH v3 4/5] efi: call get_event_log before ExitBootServices
Hi Thiebaud

On Wed, Sep 20, 2017 at 10:13 AM, Thiebaud Weksteen <tweek@google.com> wrote:
> With TPM 2.0 specification, the event logs may only be accessible by
> calling an EFI Boot Service. Modify the EFI stub to copy the log area to
> a new Linux-specific EFI configuration table so it remains accessible
> once booted.
>
> When calling this service, it is possible to specify the expected format
> of the logs: TPM 1.2 (SHA1) or TPM 2.0 ("Crypto Agile"). For now, only the
> first format is retrieved.
>

Do you have plans to add support for the crypto-agile format? I am
working on uefi/ovmf support, and I am wondering if it is at all
necessary to add support for the 1.2 format. What do you think? I can
eventually try to work on 2.0 format support.

Thanks

> Signed-off-by: Thiebaud Weksteen <tweek@google.com>
> ---
> arch/x86/boot/compressed/eboot.c | 1 +
> drivers/firmware/efi/Makefile | 2 +-
> drivers/firmware/efi/efi.c | 4 ++
> drivers/firmware/efi/libstub/Makefile | 3 +-
> drivers/firmware/efi/libstub/tpm.c | 81 +++++++++++++++++++++++++++++++++++
> drivers/firmware/efi/tpm.c | 40 +++++++++++++++++
> include/linux/efi.h | 46 ++++++++++++++++++++
> 7 files changed, 174 insertions(+), 3 deletions(-)
> create mode 100644 drivers/firmware/efi/tpm.c
>
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index a1686f3dc295..ef6abe8b3788 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -999,6 +999,7 @@ struct boot_params *efi_main(struct efi_config *c,
>
> /* Ask the firmware to clear memory on unclean shutdown */
> efi_enable_reset_attack_mitigation(sys_table);
> + efi_retrieve_tpm2_eventlog(sys_table);
>
> setup_graphics(boot_params);
>
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index 0329d319d89a..2f074b5cde87 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -10,7 +10,7 @@
> KASAN_SANITIZE_runtime-wrappers.o := n
>
> obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
> -obj-$(CONFIG_EFI) += efi.o vars.o reboot.o memattr.o
> +obj-$(CONFIG_EFI) += efi.o vars.o reboot.o memattr.o tpm.o
> obj-$(CONFIG_EFI) += capsule.o memmap.o
> obj-$(CONFIG_EFI_VARS) += efivars.o
> obj-$(CONFIG_EFI_ESRT) += esrt.o
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index f97f272e16ee..0308acfaaf76 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -52,6 +52,7 @@ struct efi __read_mostly efi = {
> .properties_table = EFI_INVALID_TABLE_ADDR,
> .mem_attr_table = EFI_INVALID_TABLE_ADDR,
> .rng_seed = EFI_INVALID_TABLE_ADDR,
> + .tpm_log = EFI_INVALID_TABLE_ADDR
> };
> EXPORT_SYMBOL(efi);
>
> @@ -444,6 +445,7 @@ static __initdata efi_config_table_type_t common_tables[] = {
> {EFI_PROPERTIES_TABLE_GUID, "PROP", &efi.properties_table},
> {EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi.mem_attr_table},
> {LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
> + {LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
> {NULL_GUID, NULL, NULL},
> };
>
> @@ -532,6 +534,8 @@ int __init efi_config_parse_tables(void *config_tables, int count, int sz,
> if (efi_enabled(EFI_MEMMAP))
> efi_memattr_init();
>
> + efi_tpm_eventlog_init();
> +
> /* Parse the EFI Properties table if it exists */
> if (efi.properties_table != EFI_INVALID_TABLE_ADDR) {
> efi_properties_table_t *tbl;
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index dedf9bde44db..2abe6d22dc5f 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -29,8 +29,7 @@ OBJECT_FILES_NON_STANDARD := y
> # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
> KCOV_INSTRUMENT := n
>
> -lib-y := efi-stub-helper.o gop.o secureboot.o
> -lib-$(CONFIG_RESET_ATTACK_MITIGATION) += tpm.o
> +lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o
>
> # include the stub's generic dependencies from lib/ when building for ARM/arm64
> arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c
> diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c
> index 6224cdbc9669..da661bf8cb96 100644
> --- a/drivers/firmware/efi/libstub/tpm.c
> +++ b/drivers/firmware/efi/libstub/tpm.c
> @@ -4,15 +4,18 @@
> * Copyright (C) 2016 CoreOS, Inc
> * Copyright (C) 2017 Google, Inc.
> * Matthew Garrett <mjg59@google.com>
> + * Thiebaud Weksteen <tweek@google.com>
> *
> * This file is part of the Linux kernel, and is made available under the
> * terms of the GNU General Public License version 2.
> */
> #include <linux/efi.h>
> +#include <linux/tpm_eventlog.h>
> #include <asm/efi.h>
>
> #include "efistub.h"
>
> +#ifdef CONFIG_RESET_ATTACK_MITIGATION
> static const efi_char16_t efi_MemoryOverWriteRequest_name[] = {
> 'M', 'e', 'm', 'o', 'r', 'y', 'O', 'v', 'e', 'r', 'w', 'r', 'i', 't',
> 'e', 'R', 'e', 'q', 'u', 'e', 's', 't', 'C', 'o', 'n', 't', 'r', 'o',
> @@ -56,3 +59,81 @@ void efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg)
> EFI_VARIABLE_BOOTSERVICE_ACCESS |
> EFI_VARIABLE_RUNTIME_ACCESS, sizeof(val), &val);
> }
> +
> +#endif
> +
> +void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> +{
> + efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
> + efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
> + efi_status_t status;
> + efi_physical_addr_t log_location, log_last_entry;
> + struct linux_efi_tpm_eventlog *log_tbl;
> + unsigned long first_entry_addr, last_entry_addr;
> + size_t log_size, last_entry_size;
> + efi_bool_t truncated;
> + void *tcg2_protocol;
> +
> + status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
> + &tcg2_protocol);
> + if (status != EFI_SUCCESS)
> + return;
> +
> + status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
> + EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
> + &log_location, &log_last_entry, &truncated);
> + if (status != EFI_SUCCESS)
> + return;
> +
> + if (!log_location)
> + return;
> + first_entry_addr = (unsigned long) log_location;
> +
> + /*
> + * We populate the EFI table even if the logs are empty.
> + */
> + if (!log_last_entry) {
> + log_size = 0;
> + } else {
> + last_entry_addr = (unsigned long) log_last_entry;
> + /*
> + * get_event_log only returns the address of the last entry.
> + * We need to calculate its size to deduce the full size of
> + * the logs.
> + */
> + last_entry_size = sizeof(struct tcpa_event) +
> + ((struct tcpa_event *) last_entry_addr)->event_size;
> + log_size = log_last_entry - log_location + last_entry_size;
> + }
> +
> + /* Allocate space for the logs and copy them. */
> + status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
> + sizeof(*log_tbl) + log_size,
> + (void **) &log_tbl);
> +
> + if (status != EFI_SUCCESS) {
> + efi_printk(sys_table_arg,
> + "Unable to allocate memory for event log\n");
> + return;
> + }
> +
> + memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
> + log_tbl->size = log_size;
> + log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> + memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
> +
> + status = efi_call_early(install_configuration_table,
> + &linux_eventlog_guid, log_tbl);
> + if (status != EFI_SUCCESS)
> + goto err_free;
> + return;
> +
> +err_free:
> + efi_call_early(free_pool, log_tbl);
> +}
> +
> +void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
> +{
> + /* Only try to retrieve the logs in 1.2 format. */
> + efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
> +}
> diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
> new file mode 100644
> index 000000000000..0cbeb3d46b18
> --- /dev/null
> +++ b/drivers/firmware/efi/tpm.c
> @@ -0,0 +1,40 @@
> +/*
> + * Copyright (C) 2017 Google, Inc.
> + * Thiebaud Weksteen <tweek@google.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/efi.h>
> +#include <linux/init.h>
> +#include <linux/memblock.h>
> +
> +#include <asm/early_ioremap.h>
> +
> +/*
> + * Reserve the memory associated with the TPM Event Log configuration table.
> + */
> +int __init efi_tpm_eventlog_init(void)
> +{
> + struct linux_efi_tpm_eventlog *log_tbl;
> + unsigned int tbl_size;
> +
> + if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
> + return 0;
> +
> + log_tbl = early_memremap(efi.tpm_log, sizeof(*log_tbl));
> + if (!log_tbl) {
> + pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
> + efi.tpm_log);
> + efi.tpm_log = EFI_INVALID_TABLE_ADDR;
> + return -ENOMEM;
> + }
> +
> + tbl_size = sizeof(*log_tbl) + log_tbl->size;
> + memblock_reserve(efi.tpm_log, tbl_size);
> + early_memunmap(log_tbl, sizeof(*log_tbl));
> + return 0;
> +}
> +
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 8dc3d94a3e3c..c5805eb601b1 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -472,6 +472,39 @@ typedef struct {
> u64 get_all;
> } apple_properties_protocol_64_t;
>
> +typedef struct {
> + u32 get_capability;
> + u32 get_event_log;
> + u32 hash_log_extend_event;
> + u32 submit_command;
> + u32 get_active_pcr_banks;
> + u32 set_active_pcr_banks;
> + u32 get_result_of_set_active_pcr_banks;
> +} efi_tcg2_protocol_32_t;
> +
> +typedef struct {
> + u64 get_capability;
> + u64 get_event_log;
> + u64 hash_log_extend_event;
> + u64 submit_command;
> + u64 get_active_pcr_banks;
> + u64 set_active_pcr_banks;
> + u64 get_result_of_set_active_pcr_banks;
> +} efi_tcg2_protocol_64_t;
> +
> +typedef u32 efi_tcg2_event_log_format;
> +
> +typedef struct {
> + void *get_capability;
> + efi_status_t (*get_event_log)(efi_handle_t, efi_tcg2_event_log_format,
> + efi_physical_addr_t *, efi_physical_addr_t *, efi_bool_t *);
> + void *hash_log_extend_event;
> + void *submit_command;
> + void *get_active_pcr_banks;
> + void *set_active_pcr_banks;
> + void *get_result_of_set_active_pcr_banks;
> +} efi_tcg2_protocol_t;
> +
> /*
> * Types and defines for EFI ResetSystem
> */
> @@ -622,6 +655,7 @@ void efi_native_runtime_setup(void);
> #define EFI_MEMORY_ATTRIBUTES_TABLE_GUID EFI_GUID(0xdcfa911d, 0x26eb, 0x469f, 0xa2, 0x20, 0x38, 0xb7, 0xdc, 0x46, 0x12, 0x20)
> #define EFI_CONSOLE_OUT_DEVICE_GUID EFI_GUID(0xd3b36f2c, 0xd551, 0x11d4, 0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
> #define APPLE_PROPERTIES_PROTOCOL_GUID EFI_GUID(0x91bd12fe, 0xf6c3, 0x44fb, 0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 0xe0)
> +#define EFI_TCG2_PROTOCOL_GUID EFI_GUID(0x607f766c, 0x7455, 0x42be, 0x93, 0x0b, 0xe4, 0xd7, 0x6d, 0xb2, 0x72, 0x0f)
>
> #define EFI_IMAGE_SECURITY_DATABASE_GUID EFI_GUID(0xd719b2cb, 0x3d3a, 0x4596, 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f)
> #define EFI_SHIM_LOCK_GUID EFI_GUID(0x605dab50, 0xe046, 0x4300, 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23)
> @@ -634,6 +668,7 @@ void efi_native_runtime_setup(void);
> #define LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID EFI_GUID(0xe03fc20a, 0x85dc, 0x406e, 0xb9, 0x0e, 0x4a, 0xb5, 0x02, 0x37, 0x1d, 0x95)
> #define LINUX_EFI_LOADER_ENTRY_GUID EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf, 0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f)
> #define LINUX_EFI_RANDOM_SEED_TABLE_GUID EFI_GUID(0x1ce1e5bc, 0x7ceb, 0x42f2, 0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b)
> +#define LINUX_EFI_TPM_EVENT_LOG_GUID EFI_GUID(0xb7799cb0, 0xeca2, 0x4943, 0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa)
>
> typedef struct {
> efi_guid_t guid;
> @@ -908,6 +943,7 @@ extern struct efi {
> unsigned long properties_table; /* properties table */
> unsigned long mem_attr_table; /* memory attributes table */
> unsigned long rng_seed; /* UEFI firmware random seed */
> + unsigned long tpm_log; /* TPM2 Event Log table */
> efi_get_time_t *get_time;
> efi_set_time_t *set_time;
> efi_get_wakeup_time_t *get_wakeup_time;
> @@ -1504,6 +1540,8 @@ static inline void
> efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg) { }
> #endif
>
> +void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table);
> +
> /*
> * Arch code can implement the following three template macros, avoiding
> * reptition for the void/non-void return cases of {__,}efi_call_virt():
> @@ -1571,4 +1609,12 @@ struct linux_efi_random_seed {
> u8 bits[];
> };
>
> +struct linux_efi_tpm_eventlog {
> + u32 size;
> + u8 version;
> + u8 log[];
> +};
> +
> +extern int efi_tpm_eventlog_init(void);
> +
> #endif /* _LINUX_EFI_H */
> --
> 2.14.1.821.g8fa685d3b7-goog
>



--
Marc-André Lureau

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