[PATCH v3 7/7] tpm: Adds securityfs support for TPM2.0 eventlog

[Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>]

Adds securityfs support for TPM2.0.
This patch add supports only for binary_bios_measurements.

Signed-off-by: Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
---
 drivers/char/tpm/Makefile            |   2 +-
 drivers/char/tpm/tpm2.h              |  85 +++++++++++++
 drivers/char/tpm/tpm2_eventlog.c     | 224 +++++++++++++++++++++++++++++++++++
 drivers/char/tpm/tpm_eventlog_init.c |  28 +++--
 drivers/char/tpm/tpm_of.c            |  42 ++++---
 5 files changed, 357 insertions(+), 24 deletions(-)
 create mode 100644 drivers/char/tpm/tpm2.h
 create mode 100644 drivers/char/tpm/tpm2_eventlog.c

diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 200b957..b10316d 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -3,7 +3,7 @@
 #
 obj-$(CONFIG_TCG_TPM) += tpm.o
 tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
-	tpm_eventlog.o tpm_eventlog_init.o
+	tpm_eventlog.o tpm_eventlog_init.o tpm2_eventlog.o
 
 tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
 tpm-$(CONFIG_OF) += tpm_of.o
diff --git a/drivers/char/tpm/tpm2.h b/drivers/char/tpm/tpm2.h
new file mode 100644
index 0000000..38a8073
--- /dev/null
+++ b/drivers/char/tpm/tpm2.h
@@ -0,0 +1,85 @@
+#ifndef __TPM2_H__
+#define __TPM2_H__
+
+#define TPM_ALG_SHA1_DIGEST_SIZE	20
+#define TPM_ALG_SHA256_DIGEST_SIZE	32
+#define TPM_ALG_SHA384_DIGEST_SIZE	48
+
+#define HASH_COUNT	3
+#define MAX_TPM_LOG_MSG	128
+
+/**
+ * All the structures related to Event Log are taken from TCG EFI Protocol
+ * Specification, Family "2.0". Document is available on link
+ * http://www.trustedcomputinggroup.org/tcg-efi-protocol-specification/
+ * Information is also available on TCG PC Client Platform Firmware Profile
+ * Specification, Family "2.0"
+ * Detailed digest structures for TPM2.0 are defined in document
+ * Trusted Platform Module Library Part 2: Structures, Family "2.0".
+ */
+
+/* Event log header algorithm spec. */
+struct tcg_efispecideventalgorithmsize {
+	u16	algorithm_id;
+	u16	digest_size;
+} __packed;
+
+/* Event log header data. */
+struct tcg_efispecideventstruct {
+	u8					signature[16];
+	u32					platform_class;
+	u8					spec_version_minor;
+	u8					spec_version_major;
+	u8					spec_errata;
+	u8					uintnsize;
+	u32					num_algs;
+	struct tcg_efispecideventalgorithmsize	digest_sizes[HASH_COUNT];
+	u8					vendor_info_size;
+	u8					vendor_info[0];
+} __packed;
+
+/* Header entry for eventlog. */
+struct tcg_pcr_event {
+	u32	pcr_index;
+	u32	event_type;
+	u8	digest[20];
+	u32	event_size;
+	u8	event[MAX_TPM_LOG_MSG];
+} __packed;
+
+/* Digest union for crypto agility. */
+union tpmu_ha {
+	u8	 sha1[TPM_ALG_SHA1_DIGEST_SIZE];
+	u8	 sha256[TPM_ALG_SHA256_DIGEST_SIZE];
+	u8	 sha384[TPM_ALG_SHA384_DIGEST_SIZE];
+} __packed;
+
+/* Crypto Agile algorithm and respective digest. */
+struct tpmt_ha {
+	u16		algorithm_id;
+	union tpmu_ha	digest;
+} __packed;
+
+/* Crypto agile digests list. */
+struct tpml_digest_values {
+	u32		count;
+	struct tpmt_ha	digests[HASH_COUNT];
+} __packed;
+
+/* Event field structure. */
+struct tcg_event_field {
+	u32	event_size;
+	u8      event[MAX_TPM_LOG_MSG];
+} __packed;
+
+/* Crypto agile log entry format for TPM 2.0. */
+struct tcg_pcr_event2 {
+	u32				pcr_index;
+	u32				event_type;
+	struct tpml_digest_values	digests;
+	struct tcg_event_field		event;
+} __packed;
+
+extern const struct seq_operations tpm2_binary_b_measurments_seqops;
+
+#endif
diff --git a/drivers/char/tpm/tpm2_eventlog.c b/drivers/char/tpm/tpm2_eventlog.c
new file mode 100644
index 0000000..f1e8c4a
--- /dev/null
+++ b/drivers/char/tpm/tpm2_eventlog.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2016 IBM Corporation
+ *
+ * Authors:
+ *      Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
+
+ * Access to TPM2.0 event log as written by Firmware.
+ * It assumes that writer of event log has followed TCG Spec 2.0
+ * has written the event struct data in little endian. With that,
+ * it doesn't need any endian conversion for structure content.
+ *
+ * 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/seq_file.h>
+#include <linux/fs.h>
+#include <linux/security.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "tpm.h"
+#include "tpm2.h"
+#include "tpm_eventlog.h"
+
+
+static int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
+		struct tcg_pcr_event *event_header)
+{
+	struct tcg_efispecideventstruct *efispecid;
+	struct tcg_event_field *event_field;
+	void *marker, *marker_start;
+	int j;
+	size_t size = 0;
+
+	/*
+	 * NOTE: TPM2.0 allows support for extend to multiple PCR Banks.
+	 * This implies that eventlog also has multiple digest values
+	 * one for each PCR Bank. This is called Crypto Agile Log Entry
+	 * Format. Current support implementation is for SHA1 and SHA256.
+	 * Number of digest values are identified by parsing first
+	 * structure stored in event log also called event header.
+	 * Further, the eventlog is written in packed form so to calculate
+	 * offset it is important to know the type of algorithm used.
+	 * Eg. 1:
+	 * digest_values.count = 1;
+	 * digest_values.digest[0].algorithm_id = sha1;
+	 * digest_values.digest[0].digest.sha1 = {20 bytes raw data};
+	 * Offset of eventsize is sizeof(count) + sizeof(algorithm_id) + 20
+	 *
+	 * Eg. 2:
+	 * digest_values.count = 1;
+	 * digest_values.digest[0].algorithm_id = sha256;
+	 * digest_values.digest[0].digest.sha1 = {32 bytes raw data};
+	 * Offset of eventsize is sizeof(count) + sizeof(algorithm_id) + 32
+
+	 * Eg. 3:
+	 * digest_values.count = 2;
+	 * digest_values.digest[0].algorithm_id = sha1;
+	 * digest_values.digest[0].digest.sha1 = {20 bytes raw data};
+	 * digest_values.digest[1].algorithm_id = sha256;
+	 * digest_values.digest[1].digest.sha256 = {32 bytes raw data};
+	 * Offset of eventsize is sizeof(count) + sizeof(algorithm_id) + 20
+	 *			+ sizeof(algorithm_id) + 32;
+	 *
+	 * So, it implies that offset of event_size can vary based on digest
+	 * values as defined by vendor. And so we have to calculate the
+	 * offset by parsing through number and type of digests being used.
+	 * And this is the purpose of using *marker to traverse the structure
+	 * and calculate the offset of event_size. This function uses *marker
+	 * to parse and calculate the dynamic size of the whole event structure.
+	 */
+
+	marker = event;
+	marker_start = marker;
+	marker = marker + sizeof(event->pcr_index) + sizeof(event->event_type)
+		+ sizeof(event->digests.count);
+
+	efispecid = (struct tcg_efispecideventstruct *) event_header->event;
+
+	for (j = 0; (j < efispecid->num_algs) && (j < HASH_COUNT); j++) {
+		marker = marker
+			+ sizeof(efispecid->digest_sizes[j].algorithm_id);
+		marker = marker + efispecid->digest_sizes[j].digest_size;
+	}
+
+	event_field = (struct tcg_event_field *) marker;
+	marker = marker + sizeof(event_field->event_size)
+		+ event_field->event_size;
+	size = marker - marker_start;
+
+	if ((event->event_type == 0) && (event_field->event_size == 0))
+		return 0;
+
+	return size;
+}
+
+static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
+{
+	struct tpm_bios_log *log = m->private;
+	void *addr = log->bios_event_log;
+	void *limit = log->bios_event_log_end;
+	struct tcg_pcr_event *event_header;
+	struct tcg_pcr_event2 *event;
+	int i;
+	size_t size = 0;
+
+	event_header = addr;
+
+	size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event)
+		+ event_header->event_size;
+
+
+	if (*pos == 0) {
+		if (addr + size < limit) {
+			if ((event_header->event_type == 0) &&
+					(event_header->event_size == 0))
+				return NULL;
+			return SEQ_START_TOKEN;
+		}
+	}
+
+	if (*pos > 0) {
+		addr += size;
+		event = addr;
+		size = calc_tpm2_event_size(event, event_header);
+		if ((addr + size >=  limit) || (size == 0))
+			return NULL;
+	}
+
+	/* read over *pos measurements */
+	for (i = 0; i < (*pos - 1); i++) {
+		event = addr;
+		size = calc_tpm2_event_size(event, event_header);
+
+		if ((addr + size >= limit) || (size == 0))
+			return NULL;
+		addr += size;
+	}
+
+	return addr;
+}
+
+static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
+		loff_t *pos)
+{
+	struct tcg_pcr_event *event_header;
+	struct tcg_pcr_event2 *event;
+	struct tpm_bios_log *log = m->private;
+	void *limit = log->bios_event_log_end;
+	void *marker;
+	size_t event_size = 0;
+
+	event_header = log->bios_event_log;
+
+	if (v == SEQ_START_TOKEN) {
+		event_size = sizeof(struct tcg_pcr_event)
+			- sizeof(event_header->event)
+			+ event_header->event_size;
+		marker = event_header;
+	} else {
+		event = v;
+		event_size = calc_tpm2_event_size(event, event_header);
+		if (event_size == 0)
+			return NULL;
+		marker =  event;
+	}
+
+	marker = marker + event_size;
+	if (marker >= limit)
+		return NULL;
+	v = marker;
+	event = v;
+
+	event_size = calc_tpm2_event_size(event, event_header);
+	if (((v + event_size) >= limit) || (event_size == 0))
+		return NULL;
+
+	(*pos)++;
+	return v;
+}
+
+static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
+{
+}
+
+static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
+{
+	struct tpm_bios_log *log = m->private;
+	struct tcg_pcr_event *event_header = log->bios_event_log;
+	struct tcg_pcr_event2 *event = v;
+	void *temp_ptr;
+	size_t size = 0;
+
+	if (v == SEQ_START_TOKEN) {
+
+		size = sizeof(struct tcg_pcr_event)
+			- sizeof(event_header->event)
+			+ event_header->event_size;
+
+		temp_ptr = event_header;
+
+		if (size > 0)
+			seq_write(m, temp_ptr, size);
+	} else {
+
+		size = calc_tpm2_event_size(event, event_header);
+
+		temp_ptr = event;
+		if (size > 0)
+			seq_write(m, temp_ptr, size);
+	}
+
+	return 0;
+}
+
+const struct seq_operations tpm2_binary_b_measurments_seqops = {
+	.start = tpm2_bios_measurements_start,
+	.next = tpm2_bios_measurements_next,
+	.stop = tpm2_bios_measurements_stop,
+	.show = tpm2_binary_bios_measurements_show,
+};
diff --git a/drivers/char/tpm/tpm_eventlog_init.c b/drivers/char/tpm/tpm_eventlog_init.c
index 038771a..9afeb3d 100644
--- a/drivers/char/tpm/tpm_eventlog_init.c
+++ b/drivers/char/tpm/tpm_eventlog_init.c
@@ -28,6 +28,7 @@
 #include <linux/slab.h>
 
 #include "tpm.h"
+#include "tpm2.h"
 #include "tpm_eventlog.h"
 
 static int tpm_bios_measurements_release(struct inode *inode,
@@ -94,6 +95,7 @@ int read_log(struct tpm_chip *chip)
 void tpm_bios_log_setup(struct tpm_chip *chip)
 {
 	const char *name = dev_name(&chip->dev);
+	void *seq_ops;
 	int rc = 0;
 
 	rc = read_log(chip);
@@ -108,23 +110,31 @@ void tpm_bios_log_setup(struct tpm_chip *chip)
 	chip->bios_dir[chip->bios_dir_count]->d_inode->i_private = chip;
 	chip->bios_dir_count++;
 
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		seq_ops = (void *)&tpm2_binary_b_measurments_seqops;
+	else
+		seq_ops = (void *)&tpm_binary_b_measurments_seqops;
+
+
 	chip->bios_dir[chip->bios_dir_count] =
 	    securityfs_create_file("binary_bios_measurements",
 				   S_IRUSR | S_IRGRP, chip->bios_dir[0],
-				   (void *)&tpm_binary_b_measurments_seqops,
+				   seq_ops,
 				   &tpm_bios_measurements_ops);
 	if (is_bad(chip->bios_dir[chip->bios_dir_count]))
 		goto err;
 	chip->bios_dir_count++;
 
-	chip->bios_dir[chip->bios_dir_count] =
-	    securityfs_create_file("ascii_bios_measurements",
-				   S_IRUSR | S_IRGRP, chip->bios_dir[0],
-				   (void *)&tpm_ascii_b_measurments_seqops,
-				   &tpm_bios_measurements_ops);
-	if (is_bad(chip->bios_dir[chip->bios_dir_count]))
-		goto err;
-	chip->bios_dir_count++;
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+		chip->bios_dir[chip->bios_dir_count] =
+			securityfs_create_file("ascii_bios_measurements",
+					S_IRUSR | S_IRGRP, chip->bios_dir[0],
+					(void *)&tpm_ascii_b_measurments_seqops,
+					&tpm_bios_measurements_ops);
+		if (is_bad(chip->bios_dir[chip->bios_dir_count]))
+			goto err;
+		chip->bios_dir_count++;
+	}
 
 	return;
 
diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
index 4e4eed7..2fc58fe 100644
--- a/drivers/char/tpm/tpm_of.c
+++ b/drivers/char/tpm/tpm_of.c
@@ -15,12 +15,10 @@
  *
  */
 
-#include <linux/seq_file.h>
-#include <linux/fs.h>
-#include <linux/security.h>
-#include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/of_device.h>
 #include <linux/of.h>
+#include <linux/string.h>
 
 #include "tpm.h"
 #include "tpm_eventlog.h"
@@ -30,44 +28,60 @@ int read_log_of(struct tpm_chip *chip)
 	struct device_node *np;
 	const u32 *sizep;
 	const u64 *basep;
+	const struct of_device_id *of_id;
+	const char *compat;
+	u32 log_size;
 
 	if (chip->dev.of_node)
 		np = chip->dev.of_node;
 	if (!np) {
-		dev_dbg(&chip->dev, "%s: ERROR - IBMVTPM not supported\n",
+		dev_dbg(&chip->dev, "%s: ERROR - TPM not supported\n",
 			__func__);
 		return -ENODEV;
 	}
 
+	compat = of_get_property(np, "compatible", NULL);
+	if (compat == NULL) {
+		dev_dbg(&chip->dev, "%s: ERROR - Compatible device not found",
+			__func__);
+		return -EIO;
+	}
+
 	sizep = of_get_property(np, "linux,sml-size", NULL);
 	if (sizep == NULL) {
 		dev_dbg(&chip->dev, "%s: ERROR - SML size not found\n",
 			__func__);
-		goto cleanup_eio;
+		return -EIO;
 	}
 	if (*sizep == 0) {
 		dev_dbg(&chip->dev, "%s: ERROR - event log area empty\n",
 			__func__);
-		goto cleanup_eio;
+		return -EIO;
 	}
 
+	if (!strcasecmp(compat, "IBM,vtpm"))
+		log_size = *sizep;
+	else
+		log_size = be32_to_cpup(sizep);
+
 	basep = of_get_property(np, "linux,sml-base", NULL);
 	if (basep == NULL) {
 		dev_dbg(&chip->dev, "%s: ERROR - SML not found\n", __func__);
-		goto cleanup_eio;
+		return -EIO;
 	}
 
-	chip->log.bios_event_log = kmalloc(*sizep, GFP_KERNEL);
+	chip->log.bios_event_log = kmalloc(log_size, GFP_KERNEL);
 	if (!chip->log.bios_event_log) {
 		return -ENOMEM;
 	}
 
-	chip->log.bios_event_log_end = chip->log.bios_event_log + *sizep;
+	chip->log.bios_event_log_end = chip->log.bios_event_log + log_size;
 
-	memcpy(chip->log.bios_event_log, __va(*basep), *sizep);
+	if (!strcasecmp(compat, "IBM,vtpm"))
+		memcpy(chip->log.bios_event_log, __va(*basep), log_size);
+	else
+		memcpy(chip->log.bios_event_log, __va(be64_to_cpup(basep)),
+				log_size);
 
 	return 0;
-
-cleanup_eio:
-	return -EIO;
 }
-- 
2.5.0


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