linux/drivers/char/tpm/tpm_ppi.c

#include <linux/acpi.h>
#include <acpi/acpi_drivers.h>
#include "tpm.h"

static const u8 tpm_ppi_uuid[] = {
	0xA6, 0xFA, 0xDD, 0x3D,
	0x1B, 0x36,
	0xB4, 0x4E,
	0xA4, 0x24,
	0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
};
static char *tpm_device_name = "TPM";

#define TPM_PPI_REVISION_ID	1
#define TPM_PPI_FN_VERSION	1
#define TPM_PPI_FN_SUBREQ	2
#define TPM_PPI_FN_GETREQ	3
#define TPM_PPI_FN_GETACT	4
#define TPM_PPI_FN_GETRSP	5
#define TPM_PPI_FN_SUBREQ2	7
#define TPM_PPI_FN_GETOPR	8
#define PPI_TPM_REQ_MAX		22
#define PPI_VS_REQ_START	128
#define PPI_VS_REQ_END		255
#define PPI_VERSION_LEN		3

static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
				void **return_value)
{
	acpi_status status;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
	if (strstr(buffer.pointer, context) != NULL) {
		*return_value = handle;
		kfree(buffer.pointer);
		return AE_CTRL_TERMINATE;
	}
	return AE_OK;
}

static inline void ppi_assign_params(union acpi_object params[4],
				     u64 function_num)
{
	params[0].type = ACPI_TYPE_BUFFER;
	params[0].buffer.length = sizeof(tpm_ppi_uuid);
	params[0].buffer.pointer = (char *)tpm_ppi_uuid;
	params[1].type = ACPI_TYPE_INTEGER;
	params[1].integer.value = TPM_PPI_REVISION_ID;
	params[2].type = ACPI_TYPE_INTEGER;
	params[2].integer.value = function_num;
	params[3].type = ACPI_TYPE_PACKAGE;
	params[3].package.count = 0;
	params[3].package.elements = NULL;
}

static ssize_t tpm_show_ppi_version(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *obj;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					 ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	obj = (union acpi_object *)output.pointer;
	status = scnprintf(buf, PAGE_SIZE, "%s\n", obj->string.pointer);
	kfree(output.pointer);
	return status;
}

static ssize_t tpm_show_ppi_request(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *ret_obj;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_GETREQ);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_PACKAGE);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	/*
	 * output.pointer should be of package type, including two integers.
	 * The first is function return code, 0 means success and 1 means
	 * error. The second is pending TPM operation requested by the OS, 0
	 * means none and >0 means operation value.
	 */
	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
	if (ret_obj->type == ACPI_TYPE_INTEGER) {
		if (ret_obj->integer.value) {
			status = -EFAULT;
			goto cleanup;
		}
		ret_obj++;
		if (ret_obj->type == ACPI_TYPE_INTEGER)
			status = scnprintf(buf, PAGE_SIZE, "%llu\n",
					   ret_obj->integer.value);
		else
			status = -EINVAL;
	} else {
		status = -EINVAL;
	}
cleanup:
	kfree(output.pointer);
	return status;
}

static ssize_t tpm_store_ppi_request(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, size_t count)
{
	char version[PPI_VERSION_LEN + 1];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object obj;
	u32 req;
	u64 ret;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	strncpy(version,
		((union acpi_object *)output.pointer)->string.pointer,
		PPI_VERSION_LEN);
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	/*
	 * the function to submit TPM operation request to pre-os environment
	 * is updated with function index from SUBREQ to SUBREQ2 since PPI
	 * version 1.1
	 */
	if (strcmp(version, "1.1") == -1)
		params[2].integer.value = TPM_PPI_FN_SUBREQ;
	else
		params[2].integer.value = TPM_PPI_FN_SUBREQ2;
	/*
	 * PPI spec defines params[3].type as ACPI_TYPE_PACKAGE. Some BIOS
	 * accept buffer/string/integer type, but some BIOS accept buffer/
	 * string/package type. For PPI version 1.0 and 1.1, use buffer type
	 * for compatibility, and use package type since 1.2 according to spec.
	 */
	if (strcmp(version, "1.2") == -1) {
		params[3].type = ACPI_TYPE_BUFFER;
		params[3].buffer.length = sizeof(req);
		sscanf(buf, "%d", &req);
		params[3].buffer.pointer = (char *)&req;
	} else {
		params[3].package.count = 1;
		obj.type = ACPI_TYPE_INTEGER;
		sscanf(buf, "%llu", &obj.integer.value);
		params[3].package.elements = &obj;
	}

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_INTEGER);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	ret = ((union acpi_object *)output.pointer)->integer.value;
	if (ret == 0)
		status = (acpi_status)count;
	else if (ret == 1)
		status = -EPERM;
	else
		status = -EFAULT;
	kfree(output.pointer);
	return status;
}

static ssize_t tpm_show_ppi_transition_action(struct device *dev,
					      struct device_attribute *attr,
					      char *buf)
{
	char version[PPI_VERSION_LEN + 1];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	u32 ret;
	char *info[] = {
		"None",
		"Shutdown",
		"Reboot",
		"OS Vendor-specific",
		"Error",
	};
	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	strncpy(version,
		((union acpi_object *)output.pointer)->string.pointer,
		PPI_VERSION_LEN);
	/*
	 * PPI spec defines params[3].type as empty package, but some platforms
	 * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
	 * compatibility, define params[3].type as buffer, if PPI version < 1.2
	 */
	if (strcmp(version, "1.2") == -1) {
		params[3].type = ACPI_TYPE_BUFFER;
		params[3].buffer.length =  0;
		params[3].buffer.pointer = NULL;
	}
	params[2].integer.value = TPM_PPI_FN_GETACT;
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_INTEGER);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	ret = ((union acpi_object *)output.pointer)->integer.value;
	if (ret < ARRAY_SIZE(info) - 1)
		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret, info[ret]);
	else
		status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret,
				   info[ARRAY_SIZE(info)-1]);
	kfree(output.pointer);
	return status;
}

static ssize_t tpm_show_ppi_response(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object *ret_obj;
	u64 req;

	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_GETRSP);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					    ACPI_TYPE_PACKAGE);
	if (ACPI_FAILURE(status))
		return -ENOMEM;
	/*
	 * parameter output.pointer should be of package type, including
	 * 3 integers. The first means function return code, the second means
	 * most recent TPM operation request, and the last means response to
	 * the most recent TPM operation request. Only if the first is 0, and
	 * the second integer is not 0, the response makes sense.
	 */
	ret_obj = ((union acpi_object *)output.pointer)->package.elements;
	if (ret_obj->type != ACPI_TYPE_INTEGER) {
		status = -EINVAL;
		goto cleanup;
	}
	if (ret_obj->integer.value) {
		status = -EFAULT;
		goto cleanup;
	}
	ret_obj++;
	if (ret_obj->type != ACPI_TYPE_INTEGER) {
		status = -EINVAL;
		goto cleanup;
	}
	if (ret_obj->integer.value) {
		req = ret_obj->integer.value;
		ret_obj++;
		if (ret_obj->type != ACPI_TYPE_INTEGER) {
			status = -EINVAL;
			goto cleanup;
		}
		if (ret_obj->integer.value == 0)
			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
					   "0: Success");
		else if (ret_obj->integer.value == 0xFFFFFFF0)
			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
					   "0xFFFFFFF0: User Abort");
		else if (ret_obj->integer.value == 0xFFFFFFF1)
			status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
					   "0xFFFFFFF1: BIOS Failure");
		else if (ret_obj->integer.value >= 1 &&
			 ret_obj->integer.value <= 0x00000FFF)
			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
					   req, ret_obj->integer.value,
					   "Corresponding TPM error");
		else
			status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
					   req, ret_obj->integer.value,
					   "Error");
	} else {
		status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
				   ret_obj->integer.value, "No Recent Request");
	}
cleanup:
	kfree(output.pointer);
	return status;
}

static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
{
	char *str = buf;
	char version[PPI_VERSION_LEN];
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object params[4];
	union acpi_object obj;
	int i;
	u32 ret;
	char *info[] = {
		"Not implemented",
		"BIOS only",
		"Blocked for OS by BIOS",
		"User required",
		"User not required",
	};
	input.count = 4;
	ppi_assign_params(params, TPM_PPI_FN_VERSION);
	input.pointer = params;
	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
				     ACPI_UINT32_MAX, ppi_callback, NULL,
				     tpm_device_name, &handle);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
					 ACPI_TYPE_STRING);
	if (ACPI_FAILURE(status))
		return -ENOMEM;

	strncpy(version,
		((union acpi_object *)output.pointer)->string.pointer,
		PPI_VERSION_LEN);
	kfree(output.pointer);
	output.length = ACPI_ALLOCATE_BUFFER;
	output.pointer = NULL;
	if (strcmp(version, "1.2") == -1)
		return -EPERM;

	params[2].integer.value = TPM_PPI_FN_GETOPR;
	params[3].package.count = 1;
	obj.type = ACPI_TYPE_INTEGER;
	params[3].package.elements = &obj;
	for (i = start; i <= end; i++) {
		obj.integer.value = i;
		status = acpi_evaluate_object_typed(handle, "_DSM",
			 &input, &output, ACPI_TYPE_INTEGER);
		if (ACPI_FAILURE(status))
			return -ENOMEM;

		ret = ((union acpi_object *)output.pointer)->integer.value;
		if (ret > 0 && ret < ARRAY_SIZE(info))
			str += scnprintf(str, PAGE_SIZE, "%d %d: %s\n",
					 i, ret, info[ret]);
		kfree(output.pointer);
		output.length = ACPI_ALLOCATE_BUFFER;
		output.pointer = NULL;
	}
	return str - buf;
}

static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{
	return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
}

static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
					  struct device_attribute *attr,
					  char *buf)
{
	return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
}

static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
static DEVICE_ATTR(request, S_IRUGO | S_IWUSR | S_IWGRP,
		   tpm_show_ppi_request, tpm_store_ppi_request);
static DEVICE_ATTR(transition_action, S_IRUGO,
		   tpm_show_ppi_transition_action, NULL);
static DEVICE_ATTR(response, S_IRUGO, tpm_show_ppi_response, NULL);
static DEVICE_ATTR(tcg_operations, S_IRUGO, tpm_show_ppi_tcg_operations, NULL);
static DEVICE_ATTR(vs_operations, S_IRUGO, tpm_show_ppi_vs_operations, NULL);

static struct attribute *ppi_attrs[] = {
	&dev_attr_version.attr,
	&dev_attr_request.attr,
	&dev_attr_transition_action.attr,
	&dev_attr_response.attr,
	&dev_attr_tcg_operations.attr,
	&dev_attr_vs_operations.attr, NULL,
};
static struct attribute_group ppi_attr_grp = {
	.attrs = ppi_attrs
};

ssize_t sys_add_ppi(struct kobject *parent)
{
	struct kobject *ppi;
	ppi = kobject_create_and_add("ppi", parent);
	if (sysfs_create_group(ppi, &ppi_attr_grp))
		return -EFAULT;
	else
		return 0;
}
EXPORT_SYMBOL_GPL(sys_add_ppi);

MODULE_LICENSE("GPL");