[PATCH v2 2/3] efi: call get_event_log before ExitBootServices

[Thiebaud Weksteen <tweek@google.com>]

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            |  2 +
 drivers/firmware/efi/libstub/Makefile |  3 +-
 drivers/firmware/efi/libstub/tpm.c    | 81 +++++++++++++++++++++++++++++++++++
 drivers/firmware/efi/tpm.c            | 39 +++++++++++++++++
 include/linux/efi.h                   | 49 +++++++++++++++++++++
 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..03fbaf8eb248 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -532,6 +532,8 @@ 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..07d217d68f47
--- /dev/null
+++ b/drivers/firmware/efi/tpm.c
@@ -0,0 +1,39 @@
+/*
+ * 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 *tbl;
+	unsigned int tbl_size;
+
+	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
+		return 0;
+
+	tbl = early_memremap(efi.tpm_log, sizeof(*tbl));
+	if (!tbl) {
+		pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
+			efi.tpm_log);
+		return -ENOMEM;
+	}
+
+	tbl_size = sizeof(*tbl) + tbl->size;
+	memblock_reserve(efi.tpm_log, tbl_size);
+	early_memunmap(tbl, sizeof(*tbl));
+	return 0;
+}
+
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8dc3d94a3e3c..e671ea9a462e 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;
@@ -1504,6 +1539,8 @@ 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 +1608,16 @@ struct linux_efi_random_seed {
 	u8	bits[];
 };
 
+
+#define EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2 0x1
+#define EFI_TCG2_EVENT_LOG_FORMAT_TCG_2   0x2
+
+struct linux_efi_tpm_eventlog {
+	u32	size;
+	u8	version;
+	u8	log[];
+};
+
+extern int efi_tpm_eventlog_init(void);
+
 #endif /* _LINUX_EFI_H */
-- 
2.14.1.581.gf28d330327-goog