[PATCH v5 3/3] tpm: add securityfs support for TPM 2.0 firmware event log

[Nayna Jain]

Unlike the device driver support for TPM 1.2, the TPM 2.0 does
not support the securityfs pseudo files for displaying the
firmware event log.

This patch enables support for providing the TPM 2.0 event log in
binary form. TPM 2.0 event log supports a crypto agile format that
records multiple digests, which is different from TPM 1.2. This
patch enables the tpm_bios_log_setup for TPM 2.0  and adds the
event log parser which understand the TPM 2.0 crypto agile format.

Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
---
 drivers/char/tpm/Makefile            |   2 +-
 drivers/char/tpm/tpm2_eventlog.c     | 214 +++++++++++++++++++++++++++++++++++
 drivers/char/tpm/tpm_eventlog.h      |  69 +++++++++++
 drivers/char/tpm/tpm_eventlog_init.c |  43 +++----
 4 files changed, 308 insertions(+), 20 deletions(-)
 create mode 100644 drivers/char/tpm/tpm2_eventlog.c

diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 1dc2671..f185a6a5 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-$(CONFIG_OF) += tpm_of.o
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
diff --git a/drivers/char/tpm/tpm2_eventlog.c b/drivers/char/tpm/tpm2_eventlog.c
new file mode 100644
index 0000000..865e70e
--- /dev/null
+++ b/drivers/char/tpm/tpm2_eventlog.c
@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2016 IBM Corporation
+ *
+ * Authors:
+ *      Nayna Jain <nayna@xxxxxxxxxxxxxxxxxx>
+ *
+ * Access to TPM 2.0 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 "tpm_eventlog.h"
+
+static int calc_tpm2_event_size(struct tcg_pcr_event2 *event,
+		struct tcg_pcr_event *event_header)
+{
+	struct tcg_efi_specid_event *efispecid;
+	struct tcg_event_field *event_field;
+	void *marker, *marker_start;
+	int i, j;
+	u16 halg;
+	u32 halg_size;
+	size_t size = 0;
+
+	/*
+	 * NOTE: TPM 2.0 supports extend to multiple PCR Banks. This implies
+	 * event log also has multiple digest values, one for each PCR Bank.
+	 * This is called Crypto Agile Log Entry Format.
+	 * TCG EFI Protocol Specification defines the procedure to parse
+	 * the event log. Below code implements this procedure to parse
+	 * correctly the Crypto agile log entry format.
+	 * Example of Crypto Agile Log Digests Format :
+	 * digest_values.count = 2;
+	 * digest_values.digest[0].alg_id = sha1;
+	 * digest_values.digest[0].digest.sha1 = {20 bytes raw data};
+	 * digest_values.digest[1].alg_id = sha256;
+	 * digest_values.digest[1].digest.sha256 = {32 bytes raw data};
+	 * Offset of eventsize is sizeof(count) + sizeof(alg_id) + 20
+	 *			+ sizeof(alg_id) + 32;
+	 *
+	 * Since, offset of event_size can vary based on digests count, offset
+	 * has to be calculated at run time. void *marker is used to traverse
+	 * the dynamic structure and calculate the offset of event_size.
+	 */
+
+	marker = event;
+	marker_start = marker;
+	marker = marker + sizeof(event->pcr_idx) + sizeof(event->event_type)
+		+ sizeof(event->digests.count);
+
+	efispecid = (struct tcg_efi_specid_event *) event_header->event;
+
+	for (i = 0; (i < event->digests.count) && (i < HASH_COUNT); i++) {
+		halg_size = sizeof(event->digests.digests[i].alg_id);
+		memcpy(&halg, marker, halg_size);
+		marker = marker + halg_size;
+		for (j = 0; (j < efispecid->num_algs); j++) {
+			if (halg == efispecid->digest_sizes[j].alg_id) {
+				marker = marker +
+					efispecid->digest_sizes[j].digest_size;
+				break;
+			}
+		}
+	}
+
+	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_chip *chip = m->private;
+	struct tpm_bios_log *log = &chip->log;
+	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_chip *chip = m->private;
+	struct tpm_bios_log *log = &chip->log;
+	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_chip *chip = m->private;
+	struct tpm_bios_log *log = &chip->log;
+	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_measurements_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.h b/drivers/char/tpm/tpm_eventlog.h
index 155467d..0780f1e 100644
--- a/drivers/char/tpm/tpm_eventlog.h
+++ b/drivers/char/tpm/tpm_eventlog.h
@@ -5,6 +5,9 @@
 #define TCG_EVENT_NAME_LEN_MAX	255
 #define MAX_TEXT_EVENT		1000	/* Max event string length */
 #define ACPI_TCPA_SIG		"TCPA"	/* 0x41504354 /'TCPA' */
+#define HASH_COUNT		3
+#define MAX_TPM_LOG_MSG		128
+#define MAX_DIGEST_SIZE		64
 
 #ifdef CONFIG_PPC64
 #define do_endian_conversion(x) be32_to_cpu(x)
@@ -73,8 +76,74 @@ enum tcpa_pc_event_ids {
 	HOST_TABLE_OF_DEVICES,
 };
 
+/*
+ * All the structures related to TPM 2.0 Event Log are taken from TCG EFIi
+ * 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 TPM 2.0 are defined in document
+ * Trusted Platform Module Library Part 2: Structures, Family "2.0".
+ */
+
+/* TPM 2.0 Event log header algorithm spec. */
+struct tcg_efi_specid_event_algs {
+	u16     alg_id;
+	u16     digest_size;
+} __packed;
+
+/* TPM 2.0 Event log header data. */
+struct tcg_efi_specid_event {
+	u8      signature[16];
+	u32     platform_class;
+	u8      spec_version_minor;
+	u8      spec_version_major;
+	u8      spec_errata;
+	u8      uintnsize;
+	u32     num_algs;
+	struct tcg_efi_specid_event_algs   digest_sizes[HASH_COUNT];
+	u8      vendor_info_size;
+	u8      vendor_info[0];
+} __packed;
+
+/* TPM 2.0 Event Log Header. */
+struct tcg_pcr_event {
+	u32     pcr_idx;
+	u32     event_type;
+	u8      digest[20];
+	u32     event_size;
+	u8      event[MAX_TPM_LOG_MSG];
+} __packed;
+
+/* TPM 2.0 Crypto agile algorithm and respective digest. */
+struct tpmt_ha {
+	u16     alg_id;
+	u8      digest[MAX_DIGEST_SIZE];
+} __packed;
+
+/* TPM 2.0 Crypto agile digests list. */
+struct tpml_digest_values {
+	u32     count;
+	struct tpmt_ha  digests[HASH_COUNT];
+} __packed;
+
+/* TPM 2.0 Event field structure. */
+struct tcg_event_field {
+	u32     event_size;
+	u8      event[MAX_TPM_LOG_MSG];
+} __packed;
+
+/* TPM 2.0 Crypto agile log entry format. */
+struct tcg_pcr_event2 {
+	u32     pcr_idx;
+	u32     event_type;
+	struct tpml_digest_values digests;
+	struct tcg_event_field  event;
+} __packed;
+
 extern const struct seq_operations tpm_ascii_b_measurements_seqops;
 extern const struct seq_operations tpm_binary_b_measurements_seqops;
+extern const struct seq_operations tpm2_binary_b_measurements_seqops;
 
 #if defined(CONFIG_ACPI)
 int tpm_read_log_acpi(struct tpm_chip *chip);
diff --git a/drivers/char/tpm/tpm_eventlog_init.c b/drivers/char/tpm/tpm_eventlog_init.c
index ae42f46..d1fe83e 100644
--- a/drivers/char/tpm/tpm_eventlog_init.c
+++ b/drivers/char/tpm/tpm_eventlog_init.c
@@ -121,9 +121,6 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 	unsigned int cnt;
 	int rc = 0;
 
-	if (chip->flags & TPM_CHIP_FLAG_TPM2)
-		return 0;
-
 	rc = tpm_read_log(chip);
 	if (rc)
 		return rc;
@@ -135,28 +132,36 @@ int tpm_bios_log_setup(struct tpm_chip *chip)
 	cnt++;
 
 	chip->bin_log_seqops.chip = chip;
-	chip->bin_log_seqops.seqops = &tpm_binary_b_measurements_seqops;
+	if (chip->flags & TPM_CHIP_FLAG_TPM2)
+		chip->bin_log_seqops.seqops =
+			&tpm2_binary_b_measurements_seqops;
+	else
+		chip->bin_log_seqops.seqops =
+			&tpm_binary_b_measurements_seqops;
 
 	chip->bios_dir[cnt] =
-	    securityfs_create_file("binary_bios_measurements",
-				   0440, chip->bios_dir[0],
-				   (void *)&chip->bin_log_seqops,
-				   &tpm_bios_measurements_ops);
+		securityfs_create_file("binary_bios_measurements",
+				       0440, chip->bios_dir[0],
+				       (void *)&chip->bin_log_seqops,
+				       &tpm_bios_measurements_ops);
 	if (is_bad(chip->bios_dir[cnt]))
 		goto err;
 	cnt++;
 
-	chip->ascii_log_seqops.chip = chip;
-	chip->ascii_log_seqops.seqops = &tpm_ascii_b_measurements_seqops;
-
-	chip->bios_dir[cnt] =
-	    securityfs_create_file("ascii_bios_measurements",
-				   0440, chip->bios_dir[0],
-				   (void *)&chip->ascii_log_seqops,
-				   &tpm_bios_measurements_ops);
-	if (is_bad(chip->bios_dir[cnt]))
-		goto err;
-	cnt++;
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+		chip->ascii_log_seqops.chip = chip;
+		chip->ascii_log_seqops.seqops =
+			&tpm_ascii_b_measurements_seqops;
+
+		chip->bios_dir[cnt] =
+			securityfs_create_file("ascii_bios_measurements",
+					       0440, chip->bios_dir[0],
+					       (void *)&chip->ascii_log_seqops,
+					       &tpm_bios_measurements_ops);
+		if (is_bad(chip->bios_dir[cnt]))
+			goto err;
+		cnt++;
+	}
 
 	return 0;
 
-- 
2.5.0