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Subject[PATCH 1/2] efi: call get_event_log before ExitBootServices
From
With TPM 2.0, access to the event log is only possible by using the
EFI TPM2 Boot Service. Modify the EFI stub to copy the log area to a new
Linux-specific EFI table so it remains accessible for future use.

Signed-off-by: Thiebaud Weksteen <tweek@google.com>
---
arch/x86/boot/compressed/eboot.c | 1 +
drivers/char/tpm/tpm.h | 29 ++++++++++---
drivers/char/tpm/tpm_eventlog.h | 26 +++---------
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/tpm.c | 80 +++++++++++++++++++++++++++++++++++
include/linux/efi.h | 35 +++++++++++++++
6 files changed, 146 insertions(+), 28 deletions(-)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index a1686f3dc295..97bec8df36ff 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(boot_params, sys_table);

setup_graphics(boot_params);

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 04fbff2edbf3..efede7dc9340 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -40,6 +40,8 @@
#include <asm/intel-family.h>
#endif

+#include "tpm_eventlog.h"
+
enum tpm_const {
TPM_MINOR = 224, /* officially assigned */
TPM_BUFSIZE = 4096,
@@ -397,11 +399,6 @@ struct tpm_cmd_t {
tpm_cmd_params params;
} __packed;

-struct tpm2_digest {
- u16 alg_id;
- u8 digest[SHA512_DIGEST_SIZE];
-} __packed;
-
/* A string buffer type for constructing TPM commands. This is based on the
* ideas of string buffer code in security/keys/trusted.h but is heap based
* in order to keep the stack usage minimal.
@@ -581,4 +578,26 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u32 cc,
u8 *cmd);
int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
u32 cc, u8 *buf, size_t *bufsiz);
+
+extern const struct seq_operations tpm2_binary_b_measurements_seqops;
+
+#if defined(CONFIG_ACPI)
+int tpm_read_log_acpi(struct tpm_chip *chip);
+#else
+static inline int tpm_read_log_acpi(struct tpm_chip *chip)
+{
+ return -ENODEV;
+}
+#endif
+#if defined(CONFIG_OF)
+int tpm_read_log_of(struct tpm_chip *chip);
+#else
+static inline int tpm_read_log_of(struct tpm_chip *chip)
+{
+ return -ENODEV;
+}
+#endif
+
+int tpm_bios_log_setup(struct tpm_chip *chip);
+void tpm_bios_log_teardown(struct tpm_chip *chip);
#endif
diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
index b4b549559203..1009a2503985 100644
--- a/drivers/char/tpm/tpm_eventlog.h
+++ b/drivers/char/tpm/tpm_eventlog.h
@@ -104,6 +104,11 @@ struct tcg_event_field {
u8 event[0];
} __packed;

+struct tpm2_digest {
+ u16 alg_id;
+ u8 digest[SHA512_DIGEST_SIZE];
+} __packed;
+
struct tcg_pcr_event2 {
u32 pcr_idx;
u32 event_type;
@@ -112,26 +117,5 @@ struct tcg_pcr_event2 {
struct tcg_event_field event;
} __packed;

-extern const struct seq_operations tpm2_binary_b_measurements_seqops;
-
-#if defined(CONFIG_ACPI)
-int tpm_read_log_acpi(struct tpm_chip *chip);
-#else
-static inline int tpm_read_log_acpi(struct tpm_chip *chip)
-{
- return -ENODEV;
-}
-#endif
-#if defined(CONFIG_OF)
-int tpm_read_log_of(struct tpm_chip *chip);
-#else
-static inline int tpm_read_log_of(struct tpm_chip *chip)
-{
- return -ENODEV;
-}
-#endif
-
-int tpm_bios_log_setup(struct tpm_chip *chip);
-void tpm_bios_log_teardown(struct tpm_chip *chip);

#endif
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..ba2cb68833fb 100644
--- a/drivers/firmware/efi/libstub/tpm.c
+++ b/drivers/firmware/efi/libstub/tpm.c
@@ -4,6 +4,7 @@
* 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.
@@ -12,7 +13,9 @@
#include <asm/efi.h>

#include "efistub.h"
+#include "../../../char/tpm/tpm_eventlog.h"

+#if IS_ENABLED(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 +59,80 @@ 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(struct boot_params *boot_params,
+ 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;
+ 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;
+
+ /*
+ * If the logs are empty, we still populate the EFI table to surface
+ * this information to userland.
+ */
+ if (!log_last_entry) {
+ log_size = 0;
+ } else {
+ /*
+ * 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 *)log_last_entry)->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_RUNTIME_SERVICES_DATA,
+ sizeof(*log_tbl) + log_size, &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 *)log_location, 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(struct boot_params *boot_params,
+ efi_system_table_t *sys_table_arg)
+{
+ /* Only try to retrieve the logs in 1.2 format. */
+ efi_retrieve_tpm2_eventlog_1_2(boot_params, sys_table_arg);
+}
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 8dc3d94a3e3c..5eaaa68ac58a 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -472,6 +472,26 @@ 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;
+
/*
* Types and defines for EFI ResetSystem
*/
@@ -622,6 +642,7 @@ 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 +655,7 @@ 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 +1526,9 @@ static inline void
efi_enable_reset_attack_mitigation(efi_system_table_t *sys_table_arg) { }
#endif

+void efi_retrieve_tpm2_eventlog(struct boot_params *boot_params,
+ 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 +1596,14 @@ 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[];
+};
+
#endif /* _LINUX_EFI_H */
--
2.14.1.581.gf28d330327-goog
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