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Subject[PATCH v3 4/5] efi: call get_event_log before ExitBootServices
From
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.

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
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