drivers/char/tpm/tpm_bios.c

/*
 * Copyright (C) 2005 IBM Corporation
 *
 * Authors:
 *	Seiji Munetoh <munetoh@jp.ibm.com>
 *	Stefan Berger <stefanb@us.ibm.com>
 *	Reiner Sailer <sailer@watson.ibm.com>
 *	Kylene Hall <kjhall@us.ibm.com>
 *
 * Access to the eventlog extended by the TCG BIOS of PC platform
 *
 * 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 <acpi/acpi.h>
#include <acpi/actypes.h>
#include <acpi/actbl.h>
#include "tpm.h"

#define TCG_EVENT_NAME_LEN_MAX	255
#define MAX_TEXT_EVENT		1000	/* Max event string length */
#define ACPI_TCPA_SIG		"TCPA"	/* 0x41504354 /'TCPA' */

struct tpm_bios_log {
	void *bios_event_log;
	void *bios_event_log_end;
};

struct acpi_tcpa {
	struct acpi_table_header hdr;
	u16 reserved;
	u32 log_max_len __attribute__ ((packed));
	u32 log_start_addr __attribute__ ((packed));
};

struct tcpa_event {
	u32 pcr_index;
	u32 event_type;
	u8 pcr_value[20];	/* SHA1 */
	u32 event_size;
	u8 event_data[0];
};

enum tcpa_event_types {
	PREBOOT = 0,
	POST_CODE,
	UNUSED,
	NO_ACTION,
	SEPARATOR,
	ACTION,
	EVENT_TAG,
	SCRTM_CONTENTS,
	SCRTM_VERSION,
	CPU_MICROCODE,
	PLATFORM_CONFIG_FLAGS,
	TABLE_OF_DEVICES,
	COMPACT_HASH,
	IPL,
	IPL_PARTITION_DATA,
	NONHOST_CODE,
	NONHOST_CONFIG,
	NONHOST_INFO,
};

static const char* tcpa_event_type_strings[] = {
	"PREBOOT",
	"POST CODE",
	"",
	"NO ACTION",
	"SEPARATOR",
	"ACTION",
	"EVENT TAG",
	"S-CRTM Contents",
	"S-CRTM Version",
	"CPU Microcode",
	"Platform Config Flags",
	"Table of Devices",
	"Compact Hash",
	"IPL",
	"IPL Partition Data",
	"Non-Host Code",
	"Non-Host Config",
	"Non-Host Info"
};

enum tcpa_pc_event_ids {
	SMBIOS = 1,
	BIS_CERT,
	POST_BIOS_ROM,
	ESCD,
	CMOS,
	NVRAM,
	OPTION_ROM_EXEC,
	OPTION_ROM_CONFIG,
	OPTION_ROM_MICROCODE,
	S_CRTM_VERSION,
	S_CRTM_CONTENTS,
	POST_CONTENTS,
};

static const char* tcpa_pc_event_id_strings[] = {
	""
	"SMBIOS",
	"BIS Certificate",
	"POST BIOS ",
	"ESCD ",
	"CMOS",
	"NVRAM",
	"Option ROM",
	"Option ROM config",
	"Option ROM microcode",
	"S-CRTM Version",
	"S-CRTM Contents",
	"S-CRTM POST Contents",
	"POST Contents",
};

/* returns pointer to start of pos. entry of tcg log */
static void *tpm_bios_measurements_start(struct seq_file *m, loff_t *pos)
{
	loff_t i;
	struct tpm_bios_log *log = m->private;
	void *addr = log->bios_event_log;
	void *limit = log->bios_event_log_end;
	struct tcpa_event *event;

	/* read over *pos measurements */
	for (i = 0; i < *pos; i++) {
		event = addr;

		if ((addr + sizeof(struct tcpa_event)) < limit) {
			if (event->event_type == 0 && event->event_size == 0)
				return NULL;
			addr += sizeof(struct tcpa_event) + event->event_size;
		}
	}

	/* now check if current entry is valid */
	if ((addr + sizeof(struct tcpa_event)) >= limit)
		return NULL;

	event = addr;

	if ((event->event_type == 0 && event->event_size == 0) ||
	    ((addr + sizeof(struct tcpa_event) + event->event_size) >= limit))
		return NULL;

	return addr;
}

static void *tpm_bios_measurements_next(struct seq_file *m, void *v,
					loff_t *pos)
{
	struct tcpa_event *event = v;
	struct tpm_bios_log *log = m->private;
	void *limit = log->bios_event_log_end;

	v += sizeof(struct tcpa_event) + event->event_size;

	/* now check if current entry is valid */
	if ((v + sizeof(struct tcpa_event)) >= limit)
		return NULL;

	event = v;

	if (event->event_type == 0 && event->event_size == 0)
		return NULL;

	if ((event->event_type == 0 && event->event_size == 0) ||
	    ((v + sizeof(struct tcpa_event) + event->event_size) >= limit))
		return NULL;

	(*pos)++;
	return v;
}

static void tpm_bios_measurements_stop(struct seq_file *m, void *v)
{
}

static int get_event_name(char *dest, struct tcpa_event *event,
			unsigned char * event_entry)
{
	const char *name = "";
	char data[40] = "";
	int i, n_len = 0, d_len = 0;
	u32 event_id;

	switch(event->event_type) {
	case PREBOOT:
	case POST_CODE:
	case UNUSED:
	case NO_ACTION:
	case SCRTM_CONTENTS:
	case SCRTM_VERSION:
	case CPU_MICROCODE:
	case PLATFORM_CONFIG_FLAGS:
	case TABLE_OF_DEVICES:
	case COMPACT_HASH:
	case IPL:
	case IPL_PARTITION_DATA:
	case NONHOST_CODE:
	case NONHOST_CONFIG:
	case NONHOST_INFO:
		name = tcpa_event_type_strings[event->event_type];
		n_len = strlen(name);
		break;
	case SEPARATOR:
	case ACTION:
		if (MAX_TEXT_EVENT > event->event_size) {
			name = event_entry;
			n_len = event->event_size;
		}
		break;
	case EVENT_TAG:
		event_id = be32_to_cpu(*((u32 *)event_entry));

		/* ToDo Row data -> Base64 */

		switch (event_id) {
		case SMBIOS:
		case BIS_CERT:
		case CMOS:
		case NVRAM:
		case OPTION_ROM_EXEC:
		case OPTION_ROM_CONFIG:
		case OPTION_ROM_MICROCODE:
		case S_CRTM_VERSION:
		case S_CRTM_CONTENTS:
		case POST_CONTENTS:
			name = tcpa_pc_event_id_strings[event_id];
			n_len = strlen(name);
			break;
		case POST_BIOS_ROM:
		case ESCD:
			name = tcpa_pc_event_id_strings[event_id];
			n_len = strlen(name);
			for (i = 0; i < 20; i++)
				d_len += sprintf(data, "%02x",
						event_entry[8 + i]);
			break;
		default:
			break;
		}
	default:
		break;
	}

	return snprintf(dest, MAX_TEXT_EVENT, "[%.*s%.*s]",
			n_len, name, d_len, data);

}

static int tpm_binary_bios_measurements_show(struct seq_file *m, void *v)
{

	char *eventname;
	char data[4];
	u32 help;
	int i, len;
	struct tcpa_event *event = (struct tcpa_event *) v;
	unsigned char *event_entry =
	    (unsigned char *) (v + sizeof(struct tcpa_event));

	eventname = kmalloc(MAX_TEXT_EVENT, GFP_KERNEL);
	if (!eventname) {
		printk(KERN_ERR "%s: ERROR - No Memory for event name\n ",
		       __func__);
		return -ENOMEM;
	}

	/* 1st: PCR used is in little-endian format (4 bytes) */
	help = le32_to_cpu(event->pcr_index);
	memcpy(data, &help, 4);
	for (i = 0; i < 4; i++)
		seq_putc(m, data[i]);

	/* 2nd: SHA1 (20 bytes) */
	for (i = 0; i < 20; i++)
		seq_putc(m, event->pcr_value[i]);

	/* 3rd: event type identifier (4 bytes) */
	help = le32_to_cpu(event->event_type);
	memcpy(data, &help, 4);
	for (i = 0; i < 4; i++)
		seq_putc(m, data[i]);

	len = 0;

	len += get_event_name(eventname, event, event_entry);

	/* 4th:  filename <= 255 + \'0' delimiter */
	if (len > TCG_EVENT_NAME_LEN_MAX)
		len = TCG_EVENT_NAME_LEN_MAX;

	for (i = 0; i < len; i++)
		seq_putc(m, eventname[i]);

	/* 5th: delimiter */
	seq_putc(m, '\0');

	kfree(eventname);
	return 0;
}

static int tpm_bios_measurements_release(struct inode *inode,
					 struct file *file)
{
	struct seq_file *seq = file->private_data;
	struct tpm_bios_log *log = seq->private;

	if (log) {
		kfree(log->bios_event_log);
		kfree(log);
	}

	return seq_release(inode, file);
}

static int tpm_ascii_bios_measurements_show(struct seq_file *m, void *v)
{
	int len = 0;
	int i;
	char *eventname;
	struct tcpa_event *event = v;
	unsigned char *event_entry =
	    (unsigned char *) (v + sizeof(struct tcpa_event));

	eventname = kmalloc(MAX_TEXT_EVENT, GFP_KERNEL);
	if (!eventname) {
		printk(KERN_ERR "%s: ERROR - No Memory for event name\n ",
		       __func__);
		return -EFAULT;
	}

	seq_printf(m, "%2d ", event->pcr_index);

	/* 2nd: SHA1 */
	for (i = 0; i < 20; i++)
		seq_printf(m, "%02x", event->pcr_value[i]);

	/* 3rd: event type identifier */
	seq_printf(m, " %02x", event->event_type);

	len += get_event_name(eventname, event, event_entry);

	/* 4th: eventname <= max + \'0' delimiter */
	seq_printf(m, " %s\n", eventname);

	kfree(eventname);
	return 0;
}

static struct seq_operations tpm_ascii_b_measurments_seqops = {
	.start = tpm_bios_measurements_start,
	.next = tpm_bios_measurements_next,
	.stop = tpm_bios_measurements_stop,
	.show = tpm_ascii_bios_measurements_show,
};

static struct seq_operations tpm_binary_b_measurments_seqops = {
	.start = tpm_bios_measurements_start,
	.next = tpm_bios_measurements_next,
	.stop = tpm_bios_measurements_stop,
	.show = tpm_binary_bios_measurements_show,
};

/* read binary bios log */
static int read_log(struct tpm_bios_log *log)
{
	struct acpi_tcpa *buff;
	acpi_status status;
	struct acpi_table_header *virt;

	if (log->bios_event_log != NULL) {
		printk(KERN_ERR
		       "%s: ERROR - Eventlog already initialized\n",
		       __func__);
		return -EFAULT;
	}

	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
	status = acpi_get_firmware_table(ACPI_TCPA_SIG, 1,
					 ACPI_LOGICAL_ADDRESSING,
					 (struct acpi_table_header **)
					 &buff);

	if (ACPI_FAILURE(status)) {
		printk(KERN_ERR "%s: ERROR - Could not get TCPA table\n",
		       __func__);
		return -EIO;
	}

	if (buff->log_max_len == 0) {
		printk(KERN_ERR "%s: ERROR - TCPA log area empty\n", __func__);
		return -EIO;
	}

	/* malloc EventLog space */
	log->bios_event_log = kmalloc(buff->log_max_len, GFP_KERNEL);
	if (!log->bios_event_log) {
		printk
		    ("%s: ERROR - Not enough  Memory for BIOS measurements\n",
		     __func__);
		return -ENOMEM;
	}

	log->bios_event_log_end = log->bios_event_log + buff->log_max_len;

	acpi_os_map_memory(buff->log_start_addr, buff->log_max_len, (void *) &virt);

	memcpy(log->bios_event_log, virt, buff->log_max_len);

	acpi_os_unmap_memory(virt, buff->log_max_len);
	return 0;
}

static int tpm_ascii_bios_measurements_open(struct inode *inode,
					    struct file *file)
{
	int err;
	struct tpm_bios_log *log;
	struct seq_file *seq;

	log = kzalloc(sizeof(struct tpm_bios_log), GFP_KERNEL);
	if (!log)
		return -ENOMEM;

	if ((err = read_log(log)))
		return err;

	/* now register seq file */
	err = seq_open(file, &tpm_ascii_b_measurments_seqops);
	if (!err) {
		seq = file->private_data;
		seq->private = log;
	} else {
		kfree(log->bios_event_log);
		kfree(log);
	}
	return err;
}

struct file_operations tpm_ascii_bios_measurements_ops = {
	.open = tpm_ascii_bios_measurements_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = tpm_bios_measurements_release,
};

static int tpm_binary_bios_measurements_open(struct inode *inode,
					     struct file *file)
{
	int err;
	struct tpm_bios_log *log;
	struct seq_file *seq;

	log = kzalloc(sizeof(struct tpm_bios_log), GFP_KERNEL);
	if (!log)
		return -ENOMEM;

	if ((err = read_log(log)))
		return err;

	/* now register seq file */
	err = seq_open(file, &tpm_binary_b_measurments_seqops);
	if (!err) {
		seq = file->private_data;
		seq->private = log;
	} else {
		kfree(log->bios_event_log);
		kfree(log);
	}
	return err;
}

struct file_operations tpm_binary_bios_measurements_ops = {
	.open = tpm_binary_bios_measurements_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = tpm_bios_measurements_release,
};

static int is_bad(void *p)
{
	if (!p)
		return 1;
	if (IS_ERR(p) && (PTR_ERR(p) != -ENODEV))
		return 1;
	return 0;
}

struct dentry **tpm_bios_log_setup(char *name)
{
	struct dentry **ret = NULL, *tpm_dir, *bin_file, *ascii_file;

	tpm_dir = securityfs_create_dir(name, NULL);
	if (is_bad(tpm_dir))
		goto out;

	bin_file =
	    securityfs_create_file("binary_bios_measurements",
				   S_IRUSR | S_IRGRP, tpm_dir, NULL,
				   &tpm_binary_bios_measurements_ops);
	if (is_bad(bin_file))
		goto out_tpm;

	ascii_file =
	    securityfs_create_file("ascii_bios_measurements",
				   S_IRUSR | S_IRGRP, tpm_dir, NULL,
				   &tpm_ascii_bios_measurements_ops);
	if (is_bad(ascii_file))
		goto out_bin;

	ret = kmalloc(3 * sizeof(struct dentry *), GFP_KERNEL);
	if (!ret)
		goto out_ascii;

	ret[0] = ascii_file;
	ret[1] = bin_file;
	ret[2] = tpm_dir;

	return ret;

out_ascii:
	securityfs_remove(ascii_file);
out_bin:
	securityfs_remove(bin_file);
out_tpm:
	securityfs_remove(tpm_dir);
out:
	return NULL;
}
EXPORT_SYMBOL_GPL(tpm_bios_log_setup);

void tpm_bios_log_teardown(struct dentry **lst)
{
	int i;

	for (i = 0; i < 3; i++)
		securityfs_remove(lst[i]);
}
EXPORT_SYMBOL_GPL(tpm_bios_log_teardown);
MODULE_LICENSE("GPL");