[PATCH v2 3/3] tpm: parse TPM event logs based on EFI table

[Thiebaud Weksteen <tweek@google.com>]

If we are not able to retrieve the TPM event logs from the ACPI table,
check the EFI configuration table (Linux-specific GUID).

The format version of the log may be returned by the function. If not
specified (by previous implementation: tpm_acpi and tpm_of), we default
to the version of the chip (previous behaviour).

Signed-off-by: Thiebaud Weksteen <tweek@google.com>
---
 drivers/char/tpm/Makefile        |  2 +-
 drivers/char/tpm/tpm.h           |  8 +++++
 drivers/char/tpm/tpm1_eventlog.c | 15 +++++++--
 drivers/char/tpm/tpm_efi.c       | 66 ++++++++++++++++++++++++++++++++++++++++
 drivers/firmware/efi/efi.c       |  2 ++
 include/linux/efi.h              |  1 +
 6 files changed, 90 insertions(+), 4 deletions(-)
 create mode 100644 drivers/char/tpm/tpm_efi.c

diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 23681f01f95a..74182a63eef2 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -4,7 +4,7 @@
 obj-$(CONFIG_TCG_TPM) += tpm.o
 tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
 	 tpm-dev-common.o tpmrm-dev.o tpm1_eventlog.o tpm2_eventlog.o \
-         tpm2-space.o
+         tpm2-space.o tpm_efi.o
 tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
 tpm-$(CONFIG_OF) += tpm_of.o
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 46caccf6fd1a..1bd97e01df50 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -597,6 +597,14 @@ static inline int tpm_read_log_of(struct tpm_chip *chip)
 	return -ENODEV;
 }
 #endif
+#if defined(CONFIG_EFI)
+int tpm_read_log_efi(struct tpm_chip *chip);
+#else
+static inline int tpm_read_log_efi(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);
diff --git a/drivers/char/tpm/tpm1_eventlog.c b/drivers/char/tpm/tpm1_eventlog.c
index d6f70f365443..7e25e6bff6ce 100644
--- a/drivers/char/tpm/tpm1_eventlog.c
+++ b/drivers/char/tpm/tpm1_eventlog.c
@@ -21,6 +21,7 @@
  */
 
 #include <linux/seq_file.h>
+#include <linux/efi.h>
 #include <linux/fs.h>
 #include <linux/security.h>
 #include <linux/module.h>
@@ -371,6 +372,10 @@ static int tpm_read_log(struct tpm_chip *chip)
 	if (rc != -ENODEV)
 		return rc;
 
+	rc = tpm_read_log_efi(chip);
+	if (rc != -ENODEV)
+		return rc;
+
 	return tpm_read_log_of(chip);
 }
 
@@ -388,11 +393,13 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 {
 	const char *name = dev_name(&chip->dev);
 	unsigned int cnt;
-	int rc = 0;
+	int rc = 0, log_version;
+
 
 	rc = tpm_read_log(chip);
-	if (rc)
+	if (rc < 0)
 		return rc;
+	log_version = rc;
 
 	cnt = 0;
 	chip->bios_dir[cnt] = securityfs_create_dir(name, NULL);
@@ -404,7 +411,9 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 	cnt++;
 
 	chip->bin_log_seqops.chip = chip;
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+
+	if (log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 ||
+	    (!log_version && (chip->flags & TPM_CHIP_FLAG_TPM2)))
 		chip->bin_log_seqops.seqops =
 			&tpm2_binary_b_measurements_seqops;
 	else
diff --git a/drivers/char/tpm/tpm_efi.c b/drivers/char/tpm/tpm_efi.c
new file mode 100644
index 000000000000..c8247fc45bb0
--- /dev/null
+++ b/drivers/char/tpm/tpm_efi.c
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2017 Google
+ *
+ * Authors:
+ *      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
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/efi.h>
+#include <linux/tpm_eventlog.h>
+
+#include "tpm.h"
+
+/* read binary bios log from EFI configuration table */
+int tpm_read_log_efi(struct tpm_chip *chip)
+{
+
+	struct linux_efi_tpm_eventlog *log_tbl;
+	struct tpm_bios_log *log;
+	u32 log_size;
+	u8 tpm_log_version;
+
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
+		return -ENODEV;
+
+	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
+		return -ENODEV;
+
+	log = &chip->log;
+
+	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
+	if (!log_tbl) {
+		pr_err("Could not map UEFI TPM log table !\n");
+		return -ENOMEM;
+	}
+
+	log_size = log_tbl->size;
+	iounmap(log_tbl);
+
+	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
+			   MEMREMAP_WB);
+	if (!log_tbl) {
+		pr_err("Could not map UEFI TPM log table payload!\n");
+		return -ENOMEM;
+	}
+
+	/* malloc EventLog space */
+	log->bios_event_log = kmalloc(log_size, GFP_KERNEL);
+	if (!log->bios_event_log)
+		goto err_iounmap;
+	memcpy(log->bios_event_log, log_tbl->log, log_size);
+	log->bios_event_log_end = log->bios_event_log + log_size;
+
+	tpm_log_version = log_tbl->version;
+	iounmap(log_tbl);
+	return tpm_log_version;
+
+err_iounmap:
+	iounmap(log_tbl);
+	return -ENOMEM;
+}
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 03fbaf8eb248..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},
 };
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index e671ea9a462e..ab78950e6911 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -943,6 +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;
-- 
2.14.1.581.gf28d330327-goog