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Subject: [PATCH v12 01/13] HP BIOSCFG driver - Documentation

2023-05-05 22:30:05

by Jorge Lopez

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Subject: [PATCH v12 09/13] HP BIOSCFG driver - enum-attributes

2023-05-05 22:35:10

by Jorge Lopez

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Subject: [PATCH v12 10/13] HP BIOSCFG driver - spmobj-attributes

2023-05-05 22:35:10

by Jorge Lopez

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Subject: [PATCH v12 03/13] HP BIOSCFG driver - bioscfg

HP BIOS Configuration driver purpose is to provide a driver supporting
the latest sysfs class firmware attributes framework allowing the user
to change BIOS settings and security solutions on HP Inc.’s commercial
notebooks.

Many features of HP Commercial notebooks can be managed using Windows
Management Instrumentation (WMI). WMI is an implementation of Web-Based
Enterprise Management (WBEM) that provides a standards-based interface
for changing and monitoring system settings. HP BIOSCFG driver provides
a native Linux solution and the exposed features facilitates the
migration to Linux environments.

The Linux security features to be provided in hp-bioscfg driver enables
managing the BIOS settings and security solutions via sysfs, a virtual
filesystem that can be used by user-mode applications. The new
documentation cover HP-specific firmware sysfs attributes such Secure
Platform Management and Sure Start. Each section provides security
feature description and identifies sysfs directories and files exposed
by the driver.

Many HP Commercial notebooks include a feature called Secure Platform
Management (SPM), which replaces older password-based BIOS settings
management with public key cryptography. PC secure product management
begins when a target system is provisioned with cryptographic keys
that are used to ensure the integrity of communications between system
management utilities and the BIOS.

HP Commercial notebooks have several BIOS settings that control its
behaviour and capabilities, many of which are related to security.
To prevent unauthorized changes to these settings, the system can
be configured to use a cryptographic signature-based authorization
string that the BIOS will use to verify authorization to modify the
setting.

Linux Security components are under development and not published yet.
The only linux component is the driver (hp bioscfg) at this time.
Other published security components are under Windows.

Signed-off-by: Jorge Lopez <[email protected]>

---
Based on the latest platform-drivers-x86.git/for-next
---
drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 982 +++++++++++++++++++
1 file changed, 982 insertions(+)
create mode 100644 drivers/platform/x86/hp/hp-bioscfg/bioscfg.c

diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
new file mode 100644
index 000000000000..0079aedaded5
--- /dev/null
+++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
@@ -0,0 +1,982 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Common methods for use with hp-bioscfg driver
+ *
+ * Copyright (c) 2022 HP Development Company, L.P.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/wmi.h>
+#include "bioscfg.h"
+#include "../../firmware_attributes_class.h"
+#include <linux/nls.h>
+#include <linux/errno.h>
+
+MODULE_AUTHOR("Jorge Lopez <[email protected]>");
+MODULE_DESCRIPTION("HP BIOS Configuration Driver");
+MODULE_LICENSE("GPL");
+
+struct bioscfg_priv bioscfg_drv = {
+ .mutex = __MUTEX_INITIALIZER(bioscfg_drv.mutex),
+};
+
+static struct class *fw_attr_class;
+
+int get_integer_from_buffer(u8 **buffer, u32 *buffer_size, u32 *integer)
+{
+ int *ptr = PTR_ALIGN((int *)*buffer, 4);
+
+ /* Ensure there is enough space remaining to read the integer */
+ if (*buffer_size < sizeof(int))
+ return -EINVAL;
+
+ *integer = *(ptr++);
+ *buffer = (u8 *)ptr;
+ *buffer_size -= sizeof(int);
+
+ return 0;
+}
+
+int get_string_from_buffer(u8 **buffer, u32 *buffer_size, char *dst, u32 dst_size)
+{
+ u16 *src = (u16 *)*buffer;
+ u16 src_size;
+
+ u16 size;
+ int i;
+ int conv_dst_size;
+
+ if (*buffer_size < sizeof(u16))
+ return -EINVAL;
+
+ src_size = *(src++);
+ /* size value in u16 chars */
+ size = src_size / sizeof(u16);
+
+ /* Ensure there is enough space remaining to read and convert
+ * the string
+ */
+ if (*buffer_size < src_size)
+ return -EINVAL;
+
+ for (i = 0; i < size; i++)
+ if (src[i] == '\\' ||
+ src[i] == '\r' ||
+ src[i] == '\n' ||
+ src[i] == '\t')
+ size++;
+
+ /*
+ * Conversion is limited to destination string max number of
+ * bytes.
+ */
+ conv_dst_size = size;
+ if (size > dst_size)
+ conv_dst_size = dst_size - 1;
+
+ /*
+ * convert from UTF-16 unicode to ASCII
+ */
+ utf16s_to_utf8s(src, src_size, UTF16_HOST_ENDIAN, dst, conv_dst_size);
+ dst[conv_dst_size] = 0;
+
+ for (i = 0; i < size && i < conv_dst_size; i++) {
+ if (*src == '\\' ||
+ *src == '\r' ||
+ *src == '\n' ||
+ *src == '\t')
+ dst[i++] = '\\';
+
+ if (*src == '\r')
+ dst[i] = 'r';
+ else if (*src == '\n')
+ dst[i] = 'n';
+ else if (*src == '\t')
+ dst[i] = 't';
+ else if (*src == '"')
+ dst[i] = '\'';
+ else
+ dst[i] = *src;
+ src++;
+ }
+
+ *buffer = (u8 *)src;
+ *buffer_size -= size * sizeof(u16);
+
+ return size;
+}
+
+int enforce_single_line_input(char *buf, size_t count)
+{
+ char *p;
+
+ p = memchr(buf, '\n', count);
+
+ if (p == buf + count - 1)
+ *p = '\0'; /* strip trailing newline */
+ else if (p)
+ return -EINVAL; /* enforce single line input */
+
+ return 0;
+}
+
+/* Set pending reboot value and generate KOBJ_NAME event */
+void set_reboot_and_signal_event(void)
+{
+ bioscfg_drv.pending_reboot = true;
+ kobject_uevent(&bioscfg_drv.class_dev->kobj, KOBJ_CHANGE);
+}
+
+/*
+ * calculate_string_buffer() - determines size of string buffer for
+ * use with BIOS communication
+ *
+ * @str: the string to calculate based upon
+ */
+size_t hp_calculate_string_buffer(const char *str)
+{
+ int length = strlen(str);
+
+ /* BIOS expects 4 bytes when an empty string is found */
+ if (length == 0)
+ return 4;
+
+ /* u16 length field + one UTF16 char for each input char */
+ return sizeof(u16) + strlen(str) * sizeof(u16);
+}
+
+int hp_wmi_error_and_message(int error_code)
+{
+ char *error_msg = NULL;
+ int ret;
+
+ switch (error_code) {
+ case SUCCESS:
+ error_msg = "Success";
+ ret = 0;
+ break;
+ case CMD_FAILED:
+ error_msg = "Command failed";
+ ret = -EINVAL;
+ break;
+ case INVALID_SIGN:
+ error_msg = "Invalid signature";
+ ret = -EINVAL;
+ break;
+ case INVALID_CMD_VALUE:
+ error_msg = "Invalid command value/Feature not supported";
+ ret = -EOPNOTSUPP;
+ break;
+ case INVALID_CMD_TYPE:
+ error_msg = "Invalid command type";
+ ret = -EINVAL;
+ break;
+ case INVALID_DATA_SIZE:
+ error_msg = "Invalid data size";
+ ret = -EINVAL;
+ break;
+ case INVALID_CMD_PARAM:
+ error_msg = "Invalid command parameter";
+ ret = -EINVAL;
+ break;
+ case ENCRYP_CMD_REQUIRED:
+ error_msg = "Secure/encrypted command required";
+ ret = -EACCES;
+ break;
+ case NO_SECURE_SESSION:
+ error_msg = "No secure session established";
+ ret = -EACCES;
+ break;
+ case SECURE_SESSION_FOUND:
+ error_msg = "Secure session already established";
+ ret = -EACCES;
+ break;
+ case SECURE_SESSION_FAILED:
+ error_msg = "Secure session failed";
+ ret = -EIO;
+ break;
+ case AUTH_FAILED:
+ error_msg = "Other permission/Authentication failed";
+ ret = -EACCES;
+ break;
+ case INVALID_BIOS_AUTH:
+ error_msg = "Invalid BIOS administrator password";
+ ret = -EINVAL;
+ break;
+ case NONCE_DID_NOT_MATCH:
+ error_msg = "Nonce did not match";
+ ret = -EINVAL;
+ break;
+ case GENERIC_ERROR:
+ error_msg = "Generic/Other error";
+ ret = -EIO;
+ break;
+ case BIOS_ADMIN_POLICY_NOT_MET:
+ error_msg = "BIOS Admin password does not meet password policy requirements";
+ ret = -EINVAL;
+ break;
+ case BIOS_ADMIN_NOT_SET:
+ error_msg = "BIOS Setup password is not set.";
+ ret = -EPERM;
+ break;
+ case P21_NO_PROVISIONED:
+ error_msg = "P21 is not provisioned";
+ ret = -EPERM;
+ break;
+ case P21_PROVISION_IN_PROGRESS:
+ error_msg = "P21 is already provisioned or provisioning is in progress and a signing key has already been sent.";
+ ret = -EINPROGRESS;
+ break;
+ case P21_IN_USE:
+ error_msg = "P21 in use (cannot deprovision)";
+ ret = -EPERM;
+ break;
+ case HEP_NOT_ACTIVE:
+ error_msg = "HEP not activated";
+ ret = -EPERM;
+ break;
+ case HEP_ALREADY_SET:
+ error_msg = "HEP Transport already set";
+ ret = -EINVAL;
+ break;
+ case HEP_CHECK_STATE:
+ error_msg = "Check the current HEP state";
+ ret = -EINVAL;
+ break;
+ default:
+ error_msg = "Generic/Other error";
+ ret = -EIO;
+ break;
+ }
+
+ if (error_code)
+ pr_warn_ratelimited("Returned error 0x%x, \"%s\"\n", error_code, error_msg);
+
+ return ret;
+}
+
+static ssize_t pending_reboot_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ return sysfs_emit(buf, "%d\n", bioscfg_drv.pending_reboot);
+}
+
+static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
+
+/*
+ * create_attributes_level_sysfs_files() - Creates pending_reboot attributes
+ */
+static int create_attributes_level_sysfs_files(void)
+{
+ return sysfs_create_file(&bioscfg_drv.main_dir_kset->kobj,
+ &pending_reboot.attr);
+}
+
+static void attr_name_release(struct kobject *kobj)
+{
+ kfree(kobj);
+}
+
+static const struct kobj_type attr_name_ktype = {
+ .release = attr_name_release,
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+/*
+ * get_wmiobj_pointer() - Get Content of WMI block for particular instance
+ *
+ * @instance_id: WMI instance ID
+ * @guid_string: WMI GUID (in str form)
+ *
+ * Fetches the content for WMI block (instance_id) under GUID (guid_string)
+ * Caller must kfree the return
+ */
+union acpi_object *get_wmiobj_pointer(int instance_id, const char *guid_string)
+{
+ struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
+ acpi_status status;
+
+ status = wmi_query_block(guid_string, instance_id, &out);
+ return ACPI_SUCCESS(status) ? (union acpi_object *)out.pointer : NULL;
+}
+
+/*
+ * get_instance_count() - Compute total number of instances under guid_string
+ *
+ * @guid_string: WMI GUID (in string form)
+ */
+int get_instance_count(const char *guid_string)
+{
+ union acpi_object *wmi_obj = NULL;
+ int i = 0;
+
+ do {
+ kfree(wmi_obj);
+ wmi_obj = get_wmiobj_pointer(i, guid_string);
+ i++;
+ } while (wmi_obj);
+
+ return i - 1;
+}
+
+/*
+ * alloc_attributes_data() - Allocate attributes data for a particular type
+ *
+ * @attr_type: Attribute type to allocate
+ */
+static int alloc_attributes_data(int attr_type)
+{
+ switch (attr_type) {
+ case HPWMI_STRING_TYPE:
+ return alloc_string_data();
+
+ case HPWMI_INTEGER_TYPE:
+ return alloc_integer_data();
+
+ case HPWMI_ENUMERATION_TYPE:
+ return alloc_enumeration_data();
+
+ case HPWMI_ORDERED_LIST_TYPE:
+ return alloc_ordered_list_data();
+
+ case HPWMI_PASSWORD_TYPE:
+ return alloc_password_data();
+
+ default:
+ return 0;
+ }
+}
+
+int convert_hexstr_to_str(const char *input, u32 input_len, char **str, int *len)
+{
+ int ret = 0;
+ int new_len = 0;
+ char tmp[] = "0x00";
+ char *new_str = NULL;
+ long ch;
+ int i;
+
+ if (input_len <= 0 || !input || !str || !len)
+ return -EINVAL;
+
+ *len = 0;
+ *str = NULL;
+
+ new_str = kmalloc(input_len, GFP_KERNEL);
+ if (!new_str)
+ return -ENOMEM;
+
+ for (i = 0; i < input_len; i += 5) {
+ strncpy(tmp, input + i, strlen(tmp));
+ if (kstrtol(tmp, 16, &ch) == 0) {
+ // escape char
+ if (ch == '\\' ||
+ ch == '\r' ||
+ ch == '\n' || ch == '\t') {
+ if (ch == '\r')
+ ch = 'r';
+ else if (ch == '\n')
+ ch = 'n';
+ else if (ch == '\t')
+ ch = 't';
+ new_str[new_len++] = '\\';
+ }
+ new_str[new_len++] = ch;
+ if (ch == '\0')
+ break;
+ }
+ }
+
+ if (new_len) {
+ new_str[new_len] = '\0';
+ *str = krealloc(new_str, (new_len + 1) * sizeof(char),
+ GFP_KERNEL);
+ if (*str)
+ *len = new_len;
+ else
+ ret = -ENOMEM;
+ } else {
+ ret = -EFAULT;
+ }
+
+ if (ret)
+ kfree(new_str);
+ return ret;
+}
+
+/* map output size to the corresponding WMI method id */
+int encode_outsize_for_pvsz(int outsize)
+{
+ if (outsize > 4096)
+ return -EINVAL;
+ if (outsize > 1024)
+ return 5;
+ if (outsize > 128)
+ return 4;
+ if (outsize > 4)
+ return 3;
+ if (outsize > 0)
+ return 2;
+ return 1;
+}
+
+/*
+ * Update friendly display name for several attributes associated to
+ * 'Schedule Power-On'
+ */
+void friendly_user_name_update(char *path, const char *attr_name,
+ char *attr_display, int attr_size)
+{
+ if (strstr(path, SCHEDULE_POWER_ON))
+ snprintf(attr_display,
+ attr_size,
+ "%s - %s",
+ SCHEDULE_POWER_ON,
+ attr_name);
+ else
+ strscpy(attr_display, attr_name, attr_size);
+}
+
+/*
+ * update_attribute_permissions() - Update attributes permissions when
+ * isReadOnly value is 1
+ *
+ * @isReadOnly: ReadOnly value
+ * @current_val: kobj_attribute corresponding to attribute.
+ *
+ */
+void update_attribute_permissions(u32 is_readonly, struct kobj_attribute *current_val)
+{
+ if (is_readonly)
+ current_val->attr.mode = 0444;
+ else
+ current_val->attr.mode = 0644;
+}
+
+/**
+ * destroy_attribute_objs() - Free a kset of kobjects
+ * @kset: The kset to destroy
+ *
+ * Fress kobjects created for each attribute_name under attribute type kset
+ */
+static void destroy_attribute_objs(struct kset *kset)
+{
+ struct kobject *pos, *next;
+
+ list_for_each_entry_safe(pos, next, &kset->list, entry)
+ kobject_put(pos);
+}
+
+/**
+ * release_attributes_data() - Clean-up all sysfs directories and files created
+ */
+static void release_attributes_data(void)
+{
+ mutex_lock(&bioscfg_drv.mutex);
+
+ exit_string_attributes();
+ exit_integer_attributes();
+ exit_enumeration_attributes();
+ exit_ordered_list_attributes();
+ exit_password_attributes();
+ exit_sure_start_attributes();
+ exit_secure_platform_attributes();
+
+ if (bioscfg_drv.authentication_dir_kset) {
+ destroy_attribute_objs(bioscfg_drv.authentication_dir_kset);
+ kset_unregister(bioscfg_drv.authentication_dir_kset);
+ bioscfg_drv.authentication_dir_kset = NULL;
+ }
+ if (bioscfg_drv.main_dir_kset) {
+ sysfs_remove_file(&bioscfg_drv.main_dir_kset->kobj, &pending_reboot.attr);
+ destroy_attribute_objs(bioscfg_drv.main_dir_kset);
+ kset_unregister(bioscfg_drv.main_dir_kset);
+ bioscfg_drv.main_dir_kset = NULL;
+ }
+ mutex_unlock(&bioscfg_drv.mutex);
+}
+
+/*
+ * hp_add_other_attributes - Initialize HP custom attributes not reported by
+ * BIOS and required to support Secure Platform, Sure Start, and Sure
+ * Admin.
+ * @attr_type: Custom HP attribute not reported by BIOS
+ *
+ * Initialize all 2 types of attributes: Platform and Sure Start
+ * object. Populates each attribute types respective properties
+ * under sysfs files.
+ *
+ * Returns zero(0) if successful. Otherwise, a negative value.
+ */
+static int hp_add_other_attributes(int attr_type)
+{
+ struct kobject *attr_name_kobj;
+ union acpi_object *obj = NULL;
+ int retval;
+ char *attr_name;
+
+ mutex_lock(&bioscfg_drv.mutex);
+
+ attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
+ if (!attr_name_kobj) {
+ retval = -ENOMEM;
+ goto err_other_attr_init;
+ }
+
+ /* Check if attribute type is supported */
+ switch (attr_type) {
+ case HPWMI_SECURE_PLATFORM_TYPE:
+ attr_name_kobj->kset = bioscfg_drv.authentication_dir_kset;
+ attr_name = SPM_STR;
+ break;
+
+ case HPWMI_SURE_START_TYPE:
+ attr_name_kobj->kset = bioscfg_drv.main_dir_kset;
+ attr_name = SURE_START_STR;
+ break;
+
+ default:
+ pr_err("Error: Unknown attr_type: %d\n", attr_type);
+ retval = -EINVAL;
+ goto err_other_attr_init;
+ }
+
+ retval = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
+ NULL, "%s", attr_name);
+ if (retval) {
+ pr_err("Error encountered [%d]\n", retval);
+ kobject_put(attr_name_kobj);
+ goto err_other_attr_init;
+ }
+
+ /* Populate attribute data */
+ switch (attr_type) {
+ case HPWMI_SECURE_PLATFORM_TYPE:
+ retval = populate_secure_platform_data(attr_name_kobj);
+ break;
+
+ case HPWMI_SURE_START_TYPE:
+ retval = populate_sure_start_data(attr_name_kobj);
+ break;
+
+ default:
+ goto err_other_attr_init;
+ }
+
+ mutex_unlock(&bioscfg_drv.mutex);
+ return 0;
+
+err_other_attr_init:
+ mutex_unlock(&bioscfg_drv.mutex);
+ kfree(obj);
+ return retval;
+}
+
+static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
+ union acpi_object *obj,
+ const char *guid, int min_elements,
+ int instance_id)
+{
+ struct kobject *attr_name_kobj;
+ union acpi_object *elements;
+ struct kset *temp_kset;
+
+ char *str_value = NULL;
+ int str_len;
+ int retval = 0;
+
+ /* Take action appropriate to each ACPI TYPE */
+ if (obj->package.count < min_elements) {
+ pr_err("ACPI-package does not have enough elements: %d < %d\n",
+ obj->package.count, min_elements);
+ goto pack_attr_exit;
+ }
+
+ elements = obj->package.elements;
+
+ /* sanity checking */
+ if (elements[NAME].type != ACPI_TYPE_STRING) {
+ pr_debug("incorrect element type\n");
+ goto pack_attr_exit;
+ }
+ if (strlen(elements[NAME].string.pointer) == 0) {
+ pr_debug("empty attribute found\n");
+ goto pack_attr_exit;
+ }
+
+ if (attr_type == HPWMI_PASSWORD_TYPE)
+ temp_kset = bioscfg_drv.authentication_dir_kset;
+ else
+ temp_kset = bioscfg_drv.main_dir_kset;
+
+ /* convert attribute name to string */
+ retval = convert_hexstr_to_str(elements[NAME].string.pointer,
+ elements[NAME].string.length,
+ &str_value, &str_len);
+
+ if (retval) {
+ pr_debug("Failed to populate integer package data. Error [0%0x]\n",
+ retval);
+ kfree(str_value);
+ return retval;
+ }
+
+ /* All duplicate attributes found are ignored */
+ if (kset_find_obj(temp_kset, str_value)) {
+ pr_debug("Duplicate attribute name found - %s\n",
+ str_value);
+ goto pack_attr_exit;
+ }
+
+ /* build attribute */
+ attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
+ if (!attr_name_kobj) {
+ retval = -ENOMEM;
+ goto pack_attr_exit;
+ }
+
+ attr_name_kobj->kset = temp_kset;
+
+ retval = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
+ NULL, "%s", str_value);
+
+ if (retval) {
+ kobject_put(attr_name_kobj);
+ goto pack_attr_exit;
+ }
+
+ /* enumerate all of these attributes */
+ switch (attr_type) {
+ case HPWMI_STRING_TYPE:
+ retval = populate_string_package_data(elements,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_INTEGER_TYPE:
+ retval = populate_integer_package_data(elements,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_ENUMERATION_TYPE:
+ retval = populate_enumeration_package_data(elements,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_ORDERED_LIST_TYPE:
+ retval = populate_ordered_list_package_data(elements,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_PASSWORD_TYPE:
+ retval = populate_password_package_data(elements,
+ instance_id,
+ attr_name_kobj);
+ break;
+ default:
+ pr_debug("Unknown attribute type found: 0x%x\n", attr_type);
+ break;
+ }
+
+pack_attr_exit:
+ kfree(str_value);
+ return retval;
+}
+
+static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
+ union acpi_object *obj,
+ const char *guid, int min_elements,
+ int instance_id)
+{
+ struct kobject *attr_name_kobj;
+ struct kset *temp_kset;
+ char str[MAX_BUFF];
+
+ char *temp_str = NULL;
+ char *str_value = NULL;
+ u8 *buffer_ptr = NULL;
+ int buffer_size;
+ int retval = 0;
+
+ buffer_size = obj->buffer.length;
+ buffer_ptr = obj->buffer.pointer;
+
+ retval = get_string_from_buffer(&buffer_ptr,
+ &buffer_size, str, MAX_BUFF);
+
+ if (retval < 0)
+ goto buff_attr_exit;
+
+ if (attr_type == HPWMI_PASSWORD_TYPE ||
+ attr_type == HPWMI_SECURE_PLATFORM_TYPE)
+ temp_kset = bioscfg_drv.authentication_dir_kset;
+ else
+ temp_kset = bioscfg_drv.main_dir_kset;
+
+ /* All duplicate attributes found are ignored */
+ if (kset_find_obj(temp_kset, str)) {
+ pr_debug("Duplicate attribute name found - %s\n", str);
+ goto buff_attr_exit;
+ }
+
+ /* build attribute */
+ attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
+ if (!attr_name_kobj) {
+ retval = -ENOMEM;
+ goto buff_attr_exit;
+ }
+
+ attr_name_kobj->kset = temp_kset;
+
+ temp_str = str;
+ if (attr_type == HPWMI_SECURE_PLATFORM_TYPE)
+ temp_str = "SPM";
+
+ retval = kobject_init_and_add(attr_name_kobj,
+ &attr_name_ktype, NULL, "%s",
+ temp_str);
+ if (retval) {
+ kobject_put(attr_name_kobj);
+ goto buff_attr_exit;
+ }
+
+ /* enumerate all of these attributes */
+ switch (attr_type) {
+ case HPWMI_STRING_TYPE:
+ retval = populate_string_buffer_data(buffer_ptr,
+ &buffer_size,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_INTEGER_TYPE:
+ retval = populate_integer_buffer_data(buffer_ptr,
+ &buffer_size,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_ENUMERATION_TYPE:
+ retval = populate_enumeration_buffer_data(buffer_ptr,
+ &buffer_size,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_ORDERED_LIST_TYPE:
+ retval = populate_ordered_list_buffer_data(buffer_ptr,
+ &buffer_size,
+ instance_id,
+ attr_name_kobj);
+ break;
+ case HPWMI_PASSWORD_TYPE:
+ retval = populate_password_buffer_data(buffer_ptr,
+ &buffer_size,
+ instance_id,
+ attr_name_kobj);
+ break;
+ default:
+ pr_debug("Unknown attribute type found: 0x%x\n", attr_type);
+ break;
+ }
+
+buff_attr_exit:
+ kfree(str_value);
+ return retval;
+}
+
+/*
+ * hp_init_bios_attributes - Initialize all attributes for a type
+ * @attr_type: The attribute type to initialize
+ * @guid: The WMI GUID associated with this type to initialize
+ *
+ * Initialiaze all 5 types of attributes: enumeration, integer,
+ * string, password, ordered list object. Populates each attrbute types
+ * respective properties under sysfs files
+ */
+static int hp_init_bios_attributes(enum hp_wmi_data_type attr_type, const char *guid)
+{
+ union acpi_object *obj = NULL;
+ int min_elements;
+
+ /* instance_id needs to be reset for each type GUID
+ * also, instance IDs are unique within GUID but not across
+ */
+ int instance_id = 0;
+ int retval = 0;
+
+ retval = alloc_attributes_data(attr_type);
+ if (retval)
+ return retval;
+
+ switch (attr_type) {
+ case HPWMI_STRING_TYPE:
+ min_elements = STR_ELEM_CNT;
+ break;
+ case HPWMI_INTEGER_TYPE:
+ min_elements = INT_ELEM_CNT;
+ break;
+ case HPWMI_ENUMERATION_TYPE:
+ min_elements = ENUM_ELEM_CNT;
+ break;
+ case HPWMI_ORDERED_LIST_TYPE:
+ min_elements = ORD_ELEM_CNT;
+ break;
+ case HPWMI_PASSWORD_TYPE:
+ min_elements = PSWD_ELEM_CNT;
+ break;
+ default:
+ pr_err("Error: Unknown attr_type: %d\n", attr_type);
+ return -EINVAL;
+ }
+
+ /* need to use specific instance_id and guid combination to get right data */
+ obj = get_wmiobj_pointer(instance_id, guid);
+ if (!obj)
+ return -ENODEV;
+
+ mutex_lock(&bioscfg_drv.mutex);
+ while (obj) {
+ /* Take action appropriate to each ACPI TYPE */
+ if (obj->type == ACPI_TYPE_PACKAGE) {
+ retval = hp_init_bios_package_attribute(attr_type, obj,
+ guid, min_elements,
+ instance_id);
+ if (retval)
+ goto err_attr_init;
+ } else if (obj->type == ACPI_TYPE_BUFFER) {
+ retval = hp_init_bios_buffer_attribute(attr_type, obj,
+ guid, min_elements,
+ instance_id);
+ if (retval)
+ goto err_attr_init;
+ } else {
+ pr_err("Expected ACPI-package or buffer type, got: %d\n",
+ obj->type);
+ retval = -EIO;
+ goto err_attr_init;
+ }
+
+ kfree(obj);
+ instance_id++;
+ obj = get_wmiobj_pointer(instance_id, guid);
+ }
+
+err_attr_init:
+ mutex_unlock(&bioscfg_drv.mutex);
+ kfree(obj);
+ return retval;
+}
+
+static int __init hp_init(void)
+{
+ int ret;
+ int hp_bios_capable = wmi_has_guid(HP_WMI_BIOS_GUID);
+ int set_bios_settings = wmi_has_guid(HP_WMI_SET_BIOS_SETTING_GUID);
+
+ if (!hp_bios_capable) {
+ pr_err("Unable to run on non-HP system\n");
+ return -ENODEV;
+ }
+
+ if (!set_bios_settings) {
+ pr_err("Unable to set BIOS settings on HP systems\n");
+ return -ENODEV;
+ }
+
+ ret = init_hp_attr_set_interface();
+ if (ret)
+ return ret;
+
+ ret = fw_attributes_class_get(&fw_attr_class);
+ if (ret)
+ goto err_unregister_class;
+
+ bioscfg_drv.class_dev = device_create(fw_attr_class, NULL, MKDEV(0, 0),
+ NULL, "%s", DRIVER_NAME);
+ if (IS_ERR(bioscfg_drv.class_dev)) {
+ ret = PTR_ERR(bioscfg_drv.class_dev);
+ goto err_unregister_class;
+ }
+
+ bioscfg_drv.main_dir_kset = kset_create_and_add("attributes", NULL,
+ &bioscfg_drv.class_dev->kobj);
+ if (!bioscfg_drv.main_dir_kset) {
+ ret = -ENOMEM;
+ pr_debug("Failed to create and add attributes\n");
+ goto err_destroy_classdev;
+ }
+
+ bioscfg_drv.authentication_dir_kset = kset_create_and_add("authentication", NULL,
+ &bioscfg_drv.class_dev->kobj);
+ if (!bioscfg_drv.authentication_dir_kset) {
+ ret = -ENOMEM;
+ pr_debug("Failed to create and add authentication\n");
+ goto err_release_attributes_data;
+ }
+
+ /*
+ * sysfs level attributes.
+ * - pending_reboot
+ */
+ ret = create_attributes_level_sysfs_files();
+ if (ret)
+ pr_debug("Failed to create sysfs level attributes\n");
+
+ ret = hp_init_bios_attributes(HPWMI_STRING_TYPE, HP_WMI_BIOS_STRING_GUID);
+ if (ret)
+ pr_debug("Failed to populate string type attributes\n");
+
+ ret = hp_init_bios_attributes(HPWMI_INTEGER_TYPE, HP_WMI_BIOS_INTEGER_GUID);
+ if (ret)
+ pr_debug("Failed to populate integer type attributes\n");
+
+ ret = hp_init_bios_attributes(HPWMI_ENUMERATION_TYPE, HP_WMI_BIOS_ENUMERATION_GUID);
+ if (ret)
+ pr_debug("Failed to populate enumeration type attributes\n");
+
+ ret = hp_init_bios_attributes(HPWMI_ORDERED_LIST_TYPE, HP_WMI_BIOS_ORDERED_LIST_GUID);
+ if (ret)
+ pr_debug("Failed to populate ordered list object type attributes\n");
+
+ ret = hp_init_bios_attributes(HPWMI_PASSWORD_TYPE, HP_WMI_BIOS_PASSWORD_GUID);
+ if (ret)
+ pr_debug("Failed to populate password object type attributes\n");
+
+ bioscfg_drv.spm_data.attr_name_kobj = NULL;
+ ret = hp_add_other_attributes(HPWMI_SECURE_PLATFORM_TYPE);
+ if (ret)
+ pr_debug("Failed to populate secure platform object type attribute\n");
+
+ bioscfg_drv.sure_start_attr_kobj = NULL;
+ ret = hp_add_other_attributes(HPWMI_SURE_START_TYPE);
+ if (ret)
+ pr_debug("Failed to populate sure start object type attribute\n");
+
+ return 0;
+
+err_release_attributes_data:
+ release_attributes_data();
+
+err_destroy_classdev:
+ device_destroy(fw_attr_class, MKDEV(0, 0));
+
+err_unregister_class:
+ fw_attributes_class_put();
+ exit_hp_attr_set_interface();
+
+ return ret;
+}
+
+static void __exit hp_exit(void)
+{
+ release_attributes_data();
+ device_destroy(fw_attr_class, MKDEV(0, 0));
+
+ fw_attributes_class_put();
+ exit_hp_attr_set_interface();
+}
+
+module_init(hp_init);
+module_exit(hp_exit);
--
2.34.1

2023-05-05 22:35:29

by Jorge Lopez

[permalink] [raw]

2023-05-08 15:03:05

by Ilpo Järvinen

[permalink] [raw]

On Fri, 5 May 2023, Jorge Lopez wrote:

> HP BIOS Configuration driver purpose is to provide a driver supporting
> the latest sysfs class firmware attributes framework allowing the user
> to change BIOS settings and security solutions on HP Inc.?s commercial
> notebooks.
>
> Many features of HP Commercial notebooks can be managed using Windows
> Management Instrumentation (WMI). WMI is an implementation of Web-Based
> Enterprise Management (WBEM) that provides a standards-based interface
> for changing and monitoring system settings. HP BIOSCFG driver provides
> a native Linux solution and the exposed features facilitates the
> migration to Linux environments.
>
> The Linux security features to be provided in hp-bioscfg driver enables
> managing the BIOS settings and security solutions via sysfs, a virtual
> filesystem that can be used by user-mode applications. The new
> documentation cover HP-specific firmware sysfs attributes such Secure
> Platform Management and Sure Start. Each section provides security
> feature description and identifies sysfs directories and files exposed
> by the driver.
>
> Many HP Commercial notebooks include a feature called Secure Platform
> Management (SPM), which replaces older password-based BIOS settings
> management with public key cryptography. PC secure product management
> begins when a target system is provisioned with cryptographic keys
> that are used to ensure the integrity of communications between system
> management utilities and the BIOS.
>
> HP Commercial notebooks have several BIOS settings that control its
> behaviour and capabilities, many of which are related to security.
> To prevent unauthorized changes to these settings, the system can
> be configured to use a cryptographic signature-based authorization
> string that the BIOS will use to verify authorization to modify the
> setting.
>
> Linux Security components are under development and not published yet.
> The only linux component is the driver (hp bioscfg) at this time.
> Other published security components are under Windows.
>
> Signed-off-by: Jorge Lopez <[email protected]>
>
> ---
> Based on the latest platform-drivers-x86.git/for-next

FYI, for me you don't need to reply into the comments where you'll be
following the review suggestion. It saves us both time if we focus on
points where there's more to discuss.

> ---
> .../x86/hp/hp-bioscfg/passwdobj-attributes.c | 584 ++++++++++++++++++
> 1 file changed, 584 insertions(+)
> create mode 100644 drivers/platform/x86/hp/hp-bioscfg/passwdobj-attributes.c
>
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/passwdobj-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/passwdobj-attributes.c
> new file mode 100644
> index 000000000000..7f3bd58ab3fd
> --- /dev/null
> +++ b/drivers/platform/x86/hp/hp-bioscfg/passwdobj-attributes.c
> @@ -0,0 +1,584 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Functions corresponding to password object type attributes under
> + * BIOS PASSWORD for use with hp-bioscfg driver.
> + *
> + * Copyright (c) 2022 HP Development Company, L.P.
> + */
> +
> +#include "bioscfg.h"
> +#include <asm-generic/posix_types.h>
> +
> +GET_INSTANCE_ID(password);
> +/*
> + * Clear all passwords copied to memory for a particular
> + * authentication instance
> + */
> +int clear_passwords(const int instance)
> +{
> + struct password_data *password_data = &bioscfg_drv.password_data[instance];
> +
> + if (!password_data->is_enabled)
> + return 0;
> +
> + memset(password_data->current_password,
> + 0, sizeof(password_data->current_password));
> + memset(password_data->new_password,
> + 0, sizeof(password_data->new_password));
> +
> + return 0;
> +}
> +
> +/*
> + * Clear all credentials copied to memory for both Power-ON and Setup
> + * BIOS instances
> + */
> +int clear_all_credentials(void)
> +{
> + int instance;
> +
> + /* clear all passwords */
> + for (instance = 0; instance < bioscfg_drv.password_instances_count; instance++)
> + clear_passwords(instance);
> +
> + /* clear auth_token */
> + kfree(bioscfg_drv.spm_data.auth_token);
> + bioscfg_drv.spm_data.auth_token = NULL;
> +
> + return 0;
> +}
> +
> +int get_password_instance_for_type(const char *name)
> +{
> + int count = bioscfg_drv.password_instances_count;
> + int instance;
> +
> + for (instance = 0; instance < count; instance++) {

Perhaps the loops could have the same form, either this or the one in the
prev function.

> + if (strcmp(bioscfg_drv.password_data[instance].common.display_name, name) == 0)

!strcmp(...)

> + return instance;
> + }
> + return -EINVAL;
> +}
> +
> +int validate_password_input(int instance_id, const char *buf)
> +{
> + int length;
> + struct password_data *password_data = &bioscfg_drv.password_data[instance_id];
> +
> + length = strlen(buf);
> + if (buf[length - 1] == '\n')
> + length--;
> +
> + if (length > MAX_PASSWD_SIZE)
> + return INVALID_BIOS_AUTH;
> +
> + if (password_data->min_password_length > length ||
> + password_data->max_password_length < length)
> + return INVALID_BIOS_AUTH;
> + return SUCCESS;
> +}
> +
> +ATTRIBUTE_N_PROPERTY_SHOW(is_enabled, password);
> +static struct kobj_attribute password_is_password_set = __ATTR_RO(is_enabled);
> +
> +static ssize_t current_password_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + char *buf_cp;
> + int id, ret = 0;
> +
> + buf_cp = kstrdup(buf, GFP_KERNEL);
> + if (!buf_cp) {
> + ret = -ENOMEM;
> + goto exit_password;

return -ENOMEM; directly.

> + }
> +
> + ret = enforce_single_line_input(buf_cp, count);
> + if (!ret) {
> + id = get_password_instance_id(kobj);
> + if (id >= 0)
> + ret = validate_password_input(id, buf_cp);
> + }
> +
> + if (!ret) {

Convert the error handling above to < 0 + goto pairs instead.

Should this function really return 0 when get_password_instance_id()
returns error?

It can also write to -EIO index here when get_poassword_instance_id()
fails:

> + strscpy(bioscfg_drv.password_data[id].current_password,
> + buf_cp,
> + sizeof(bioscfg_drv.password_data[id].current_password));
> + /*
> + * set pending reboot flag depending on
> + * "RequiresPhysicalPresence" value
> + */
> + if (bioscfg_drv.password_data[id].common.requires_physical_presence)
> + set_reboot_and_signal_event();
> + }

> +
> +exit_password:
> + kfree(buf_cp);
> + return ret ? ret : count;
> +}
> +
> +static struct kobj_attribute password_current_password = __ATTR_WO(current_password);
> +
> +static ssize_t new_password_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + char *buf_cp = NULL;
> + int id = 0;
> + int ret = -EIO;
> +
> + buf_cp = kstrdup(buf, GFP_KERNEL);
> + if (!buf_cp) {
> + ret = -ENOMEM;
> + goto exit_password;

return -ENOMEM;

> + }
> +
> + ret = enforce_single_line_input(buf_cp, count);
> + if (!ret) {
> + id = get_password_instance_id(kobj);
> +
> + if (id >= 0)
> + ret = validate_password_input(id, buf_cp);
> + }
> +
> + if (!ret)
> + strscpy(bioscfg_drv.password_data[id].new_password,
> + buf_cp,
> + sizeof(bioscfg_drv.password_data[id].new_password));
> +

Duplicated code with the previous function? If so, add a helper.

> + if (!ret)
> + ret = hp_set_attribute(kobj->name, buf_cp);
> +
> +exit_password:
> + /*
> + * Regardless of the results both new and current passwords
> + * will be set to zero and avoid security issues
> + */
> + clear_passwords(id);
> +
> + kfree(buf_cp);
> + return ret ? ret : count;
> +}
> +
> +static struct kobj_attribute password_new_password = __ATTR_WO(new_password);
> +
> +ATTRIBUTE_N_PROPERTY_SHOW(min_password_length, password);
> +static struct kobj_attribute password_min_password_length = __ATTR_RO(min_password_length);
> +
> +ATTRIBUTE_N_PROPERTY_SHOW(max_password_length, password);
> +static struct kobj_attribute password_max_password_length = __ATTR_RO(max_password_length);
> +
> +static ssize_t role_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *buf)
> +{
> + if (strcmp(kobj->name, SETUP_PASSWD) == 0)

Use !strcmp() instead, please check the rest yourself, I won't mark them
all.

> + return sysfs_emit(buf, "%s\n", BIOS_ADMIN);
> +
> + if (strcmp(kobj->name, POWER_ON_PASSWD) == 0)
> + return sysfs_emit(buf, "%s\n", POWER_ON);
> +
> + return -EIO;
> +}
> +
> +static struct kobj_attribute password_role = __ATTR_RO(role);
> +
> +static ssize_t mechanism_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *buf)
> +{
> + int i = get_password_instance_id(kobj);
> +
> + if (i < 0)
> + return i;
> +
> + if (bioscfg_drv.password_data[i].mechanism != PASSWORD)
> + return -EINVAL;
> +
> + return sysfs_emit(buf, "%s\n", PASSWD_MECHANISM_TYPES);
> +}
> +
> +static struct kobj_attribute password_mechanism = __ATTR_RO(mechanism);
> +
> +ATTRIBUTE_VALUES_PROPERTY_SHOW(encodings, password, SEMICOLON_SEP);
> +static struct kobj_attribute password_encodings_val =
> + __ATTR_RO(encodings);
> +
> +static struct attribute *password_attrs[] = {
> + &password_is_password_set.attr,
> + &password_min_password_length.attr,
> + &password_max_password_length.attr,
> + &password_current_password.attr,
> + &password_new_password.attr,
> + &password_role.attr,
> + &password_mechanism.attr,
> + &password_encodings_val.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group password_attr_group = {
> + .attrs = password_attrs
> +};
> +
> +int alloc_password_data(void)
> +{
> + int ret = 0;
> +
> + bioscfg_drv.password_instances_count = get_instance_count(HP_WMI_BIOS_PASSWORD_GUID);
> + bioscfg_drv.password_data = kcalloc(bioscfg_drv.password_instances_count,
> + sizeof(struct password_data), GFP_KERNEL);
> + if (!bioscfg_drv.password_data) {
> + bioscfg_drv.password_instances_count = 0;
> + ret = -ENOMEM;
> + }
> +
> + return ret;
> +}
> +
> +/*
> + * populate_password_package_data -
> + * Populate all properties for an instance under password attribute
> + *
> + * @password_obj: ACPI object with password data
> + * @instance_id: The instance to enumerate
> + * @attr_name_kobj: The parent kernel object

Is kerneldoc happy with the extra line between func and its parameters,
IIRC it might not like that?

> + */
> +int populate_password_package_data(union acpi_object *password_obj, int instance_id,
> + struct kobject *attr_name_kobj)
> +{
> + struct password_data *password_data = &bioscfg_drv.password_data[instance_id];
> +
> + password_data->attr_name_kobj = attr_name_kobj;
> +
> + populate_password_elements_from_package(password_obj,
> + password_obj->package.count,
> + instance_id);
> +
> + if (strcmp(attr_name_kobj->name, SETUP_PASSWD) == 0) {
> + /* Save system authentication instance for easy access */

Extra space.

> + return sysfs_create_group(attr_name_kobj, &password_attr_group);
> + }
> +
> + return sysfs_create_group(attr_name_kobj, &password_attr_group);
> +}
> +
> +/* Expected Values types associated with each element */
> +static const acpi_object_type expected_password_types[] = {
> + [NAME] = ACPI_TYPE_STRING,
> + [VALUE] = ACPI_TYPE_STRING,
> + [PATH] = ACPI_TYPE_STRING,
> + [IS_READONLY] = ACPI_TYPE_INTEGER,
> + [DISPLAY_IN_UI] = ACPI_TYPE_INTEGER,
> + [REQUIRES_PHYSICAL_PRESENCE] = ACPI_TYPE_INTEGER,
> + [SEQUENCE] = ACPI_TYPE_INTEGER,
> + [PREREQUISITES_SIZE] = ACPI_TYPE_INTEGER,
> + [PREREQUISITES] = ACPI_TYPE_STRING,
> + [SECURITY_LEVEL] = ACPI_TYPE_INTEGER,
> + [PSWD_MIN_LENGTH] = ACPI_TYPE_INTEGER,
> + [PSWD_MAX_LENGTH] = ACPI_TYPE_INTEGER,
> + [PSWD_SIZE] = ACPI_TYPE_INTEGER,
> + [PSWD_ENCODINGS] = ACPI_TYPE_STRING,
> + [PSWD_IS_SET] = ACPI_TYPE_INTEGER,
> +};
> +
> +int populate_password_elements_from_package(union acpi_object *password_obj,
> + int password_obj_count,
> + int instance_id)
> +{
> + char *str_value = NULL;
> + int value_len;
> + int ret;
> + u32 size;
> + u32 int_value;
> + int elem;
> + int reqs;
> + int eloc;
> + int pos_values;
> + struct password_data *password_data = &bioscfg_drv.password_data[instance_id];
> +
> + if (!password_obj)
> + return -EINVAL;
> +
> + for (elem = 1, eloc = 1; elem < password_obj_count; elem++, eloc++) {
> + /* ONLY look at the first PASSWORD_ELEM_CNT elements */
> + if (eloc == PSWD_ELEM_CNT)
> + goto exit_package;
> +
> + switch (password_obj[elem].type) {
> + case ACPI_TYPE_STRING:
> +

Extra newline.

> + if (PREREQUISITES != elem && PSWD_ENCODINGS != elem) {
> + ret = convert_hexstr_to_str(password_obj[elem].string.pointer,
> + password_obj[elem].string.length,
> + &str_value, &value_len);
> + if (ret)
> + continue;
> + }
> + break;
> + case ACPI_TYPE_INTEGER:
> + int_value = (u32)password_obj[elem].integer.value;
> + break;
> + default:
> + pr_warn("Unsupported object type [%d]\n", password_obj[elem].type);
> + continue;
> + }
> +
> + /* Check that both expected and read object type match */
> + if (expected_password_types[eloc] != password_obj[elem].type) {
> + pr_err("Error expected type %d for elem %d, but got type %d instead\n",
> + expected_password_types[eloc], elem, password_obj[elem].type);
> + return -EIO;
> + }
> +
> + /* Assign appropriate element value to corresponding field*/
> + switch (eloc) {
> + case VALUE:
> + break;
> + case PATH:
> + strscpy(password_data->common.path, str_value,
> + sizeof(password_data->common.path));
> + break;
> + case IS_READONLY:
> + password_data->common.is_readonly = int_value;
> + break;
> + case DISPLAY_IN_UI:
> + password_data->common.display_in_ui = int_value;
> + break;
> + case REQUIRES_PHYSICAL_PRESENCE:
> + password_data->common.requires_physical_presence = int_value;
> + break;
> + case SEQUENCE:
> + password_data->common.sequence = int_value;
> + break;
> + case PREREQUISITES_SIZE:
> + password_data->common.prerequisites_size = int_value;
> + if (int_value > MAX_PREREQUISITES_SIZE)
> + pr_warn("Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
> + /*
> + * This HACK is needed to keep the expected
> + * element list pointing to the right obj[elem].type
> + * when the size is zero. PREREQUISITES

Please remove all these double space from your patches (should be easy
to find them with grep). Please check if your editor adds them e.g., when
reflowing text.

> + * object is omitted by BIOS when the size is
> + * zero.
> + */
> + if (int_value == 0)
> + eloc++;
> + break;
> + case PREREQUISITES:
> + size = password_data->common.prerequisites_size;
> +
> + for (reqs = 0; reqs < size; reqs++) {
> + ret = convert_hexstr_to_str(password_obj[elem + reqs].string.pointer,
> + password_obj[elem + reqs].string.length,
> + &str_value, &value_len);
> +

Extra newline

> + if (ret)
> + break;
> +
> + strscpy(password_data->common.prerequisites[reqs],
> + str_value,
> + sizeof(password_data->common.prerequisites[reqs]));
> +
> + kfree(str_value);
> + }
> + break;
> +
> + case SECURITY_LEVEL:
> + password_data->common.security_level = int_value;
> + break;
> +
> + case PSWD_MIN_LENGTH:
> + password_data->min_password_length = int_value;
> + break;
> + case PSWD_MAX_LENGTH:
> + password_data->max_password_length = int_value;
> + break;
> + case PSWD_SIZE:
> + password_data->encodings_size = int_value;
> + if (int_value > MAX_ENCODINGS_SIZE)
> + pr_warn("Password Encoding size value exceeded the maximum number of elements supported or data may be malformed\n");
> +
> + /*
> + * This HACK is needed to keep the expected
> + * element list pointing to the right obj[elem].type
> + * when the size is zero. PSWD_ENCODINGS
> + * object is omitted by BIOS when the size is
> + * zero.
> + */
> + if (int_value == 0)
> + eloc++;
> + break;
> +
> + case PSWD_ENCODINGS:
> + size = password_data->encodings_size;
> +
> + for (pos_values = 0; pos_values < size && pos_values < MAX_ENCODINGS_SIZE;

Do
size = min(password_data->encodings_size, MAX_ENCODINGS_SIZE);
instead of &&. Then put the for () into single line.

> + pos_values++) {
> + ret = convert_hexstr_to_str(password_obj[elem + pos_values].string.pointer,
> + password_obj[elem + pos_values].string.length,
> + &str_value, &value_len);
> + if (ret)
> + break;
> +
> + strscpy(password_data->encodings[pos_values],
> + str_value,
> + sizeof(password_data->encodings[pos_values]));
> + kfree(str_value);
> + }
> + break;
> + case PSWD_IS_SET:
> + password_data->is_enabled = int_value;
> + break;
> +
> + default:
> + pr_warn("Invalid element: %d found in Password attribute or data may be malformed\n", elem);
> + break;
> + }
> + kfree(str_value);
> + }
> +
> +exit_package:
> + kfree(str_value);

I suspect there are double frees paths in this function.

> + return 0;
> +}
> +
> +/**
> + * populate_password_buffer_data -
> + * Populate all properties for an instance under password object attribute
> + *
> + * @buffer_ptr: Buffer pointer
> + * @buffer_size: Buffer size
> + * @instance_id: The instance to enumerate
> + * @attr_name_kobj: The parent kernel object
> + */
> +int populate_password_buffer_data(u8 *buffer_ptr, u32 *buffer_size, int instance_id,
> + struct kobject *attr_name_kobj)
> +{
> + struct password_data *password_data = &bioscfg_drv.password_data[instance_id];
> +
> + password_data->attr_name_kobj = attr_name_kobj;
> +
> + /* Populate Password attributes */
> + populate_password_elements_from_buffer(buffer_ptr, buffer_size,
> + instance_id);
> + friendly_user_name_update(password_data->common.path,
> + attr_name_kobj->name,
> + password_data->common.display_name,
> + sizeof(password_data->common.display_name));
> + if (strcmp(attr_name_kobj->name, "Setup Password") == 0)
> + return sysfs_create_group(attr_name_kobj, &password_attr_group);
> +
> + return sysfs_create_group(attr_name_kobj, &password_attr_group);
> +}
> +
> +int populate_password_elements_from_buffer(u8 *buffer_ptr, u32 *buffer_size,
> + int instance_id)
> +{
> + int reqs;
> + int values;
> + struct password_data *password_data = &bioscfg_drv.password_data[instance_id];
> +
> + // VALUE:
> + get_string_from_buffer(&buffer_ptr, buffer_size, password_data->current_password,
> + sizeof(password_data->current_password));
> +
> + // PATH:
> + get_string_from_buffer(&buffer_ptr, buffer_size, password_data->common.path,
> + sizeof(password_data->common.path));
> +
> + // IS_READONLY:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.is_readonly);
> +
> + //DISPLAY_IN_UI:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.display_in_ui);
> +
> + // REQUIRES_PHYSICAL_PRESENCE:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.requires_physical_presence);
> +
> + // SEQUENCE:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.sequence);
> +
> + // PREREQUISITES_SIZE:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.prerequisites_size);
> +
> + if (password_data->common.prerequisites_size > MAX_PREREQUISITES_SIZE) {
> + /* Report a message and limit prerequisite size to maximum value */
> + pr_warn("Password Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
> + password_data->common.prerequisites_size = MAX_PREREQUISITES_SIZE;
> + }
> +
> + // PREREQUISITES:
> + for (reqs = 0;
> + reqs < password_data->common.prerequisites_size && reqs < MAX_PREREQUISITES_SIZE;

MAX_... enforced above.

> + reqs++)
> + get_string_from_buffer(&buffer_ptr, buffer_size,
> + password_data->common.prerequisites[reqs],
> + sizeof(password_data->common.prerequisites[reqs]));
> +
> + // SECURITY_LEVEL:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->common.security_level);
> +
> + // PSWD_MIN_LENGTH:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->min_password_length);
> +
> + // PSWD_MAX_LENGTH:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->max_password_length);
> +
> + // PSWD_SIZE:
> + if (password_data->encodings_size > MAX_ENCODINGS_SIZE) {
> + /* Report a message and limit possible values size to maximum value */
> + pr_warn("Password Encoding size value exceeded the maximum number of elements supported or data may be malformed\n");
> + password_data->encodings_size = MAX_ENCODINGS_SIZE;
> + }
> +
> + // PSWD_ENCODINGS:
> +

Extra newline.

> + for (values = 0;
> + values < password_data->encodings_size && values < MAX_VALUES_SIZE;

Hmm... Is the variation here from MAX_ENCODINGS_SIZE (above) ->
MAX_VALUES_SIZE intentional? They're both 16 anyway.

> + values++)
> + get_string_from_buffer(&buffer_ptr, buffer_size,
> + password_data->encodings[values],
> + sizeof(password_data->encodings[values]));
> +
> + // PSWD_IS_SET:
> + get_integer_from_buffer(&buffer_ptr, buffer_size,
> + &password_data->is_enabled);
> +
> + return 0;
> +}
> +
> +/*
> + * exit_password_attributes() - Clear all attribute data
> + *
> + * Clears all data allocated for this group of attributes
> + */
> +void exit_password_attributes(void)
> +{
> + int instance_id;
> +
> + for (instance_id = 0; instance_id < bioscfg_drv.password_instances_count;
> + instance_id++) {
> + struct kobject *attr_name_kobj =
> + bioscfg_drv.password_data[instance_id].attr_name_kobj;
> +
> + if (attr_name_kobj) {
> + if (strcmp(attr_name_kobj->name, SETUP_PASSWD) == 0)
> + sysfs_remove_group(attr_name_kobj,
> + &password_attr_group);
> + else
> + sysfs_remove_group(attr_name_kobj,
> + &password_attr_group);

Eh, same content in both if and else blocks???? :-)

> + }
> + }
> + bioscfg_drv.password_instances_count = 0;
> + kfree(bioscfg_drv.password_data);
> + bioscfg_drv.password_data = NULL;
> +}
>

--
i.

2023-05-09 13:22:30

by Ilpo Järvinen

[permalink] [raw]

Subject: Re: [PATCH v12 05/13] HP BIOSCFG driver - ordered-attributes

2023-05-09 13:26:16

by Ilpo Järvinen

[permalink] [raw]

Subject: Re: [PATCH v12 07/13] HP BIOSCFG driver - string-attributes

2023-05-09 13:58:11

by Ilpo Järvinen

[permalink] [raw]

Subject: Re: [PATCH v12 10/13] HP BIOSCFG driver - spmobj-attributes

2023-05-09 14:20:28

by Ilpo Järvinen

[permalink] [raw]

On Thu, May 11, 2023 at 4:23 AM Ilpo Järvinen
<[email protected]> wrote:
>
> On Wed, 10 May 2023, Jorge Lopez wrote:
>
> > On Tue, May 9, 2023 at 8:48 AM Ilpo Järvinen
> > <[email protected]> wrote:
> > >
> > > On Fri, 5 May 2023, Jorge Lopez wrote:
> > >
> > > > HP BIOS Configuration driver purpose is to provide a driver supporting
> > > > the latest sysfs class firmware attributes framework allowing the user
> > > > to change BIOS settings and security solutions on HP Inc.’s commercial
> > > > notebooks.
> > > >
> > > > Many features of HP Commercial notebooks can be managed using Windows
> > > > Management Instrumentation (WMI). WMI is an implementation of Web-Based
> > > > Enterprise Management (WBEM) that provides a standards-based interface
> > > > for changing and monitoring system settings. HP BIOSCFG driver provides
> > > > a native Linux solution and the exposed features facilitates the
> > > > migration to Linux environments.
> > > >
> > > > The Linux security features to be provided in hp-bioscfg driver enables
> > > > managing the BIOS settings and security solutions via sysfs, a virtual
> > > > filesystem that can be used by user-mode applications. The new
> > > > documentation cover HP-specific firmware sysfs attributes such Secure
> > > > Platform Management and Sure Start. Each section provides security
> > > > feature description and identifies sysfs directories and files exposed
> > > > by the driver.
> > > >
> > > > Many HP Commercial notebooks include a feature called Secure Platform
> > > > Management (SPM), which replaces older password-based BIOS settings
> > > > management with public key cryptography. PC secure product management
> > > > begins when a target system is provisioned with cryptographic keys
> > > > that are used to ensure the integrity of communications between system
> > > > management utilities and the BIOS.
> > > >
> > > > HP Commercial notebooks have several BIOS settings that control its
> > > > behaviour and capabilities, many of which are related to security.
> > > > To prevent unauthorized changes to these settings, the system can
> > > > be configured to use a cryptographic signature-based authorization
> > > > string that the BIOS will use to verify authorization to modify the
> > > > setting.
> > > >
> > > > Linux Security components are under development and not published yet.
> > > > The only linux component is the driver (hp bioscfg) at this time.
> > > > Other published security components are under Windows.
> > > >
> > > > Signed-off-by: Jorge Lopez <[email protected]>
> > > >
> > > > ---
>
>
> > > > + } else {
> > > > + /*
> > > > + * UTF-16 prefix is append to the * buffer when a BIOS
> > >
> > > What is "the * buffer" ?
> >
> > It is the data stored in 'buffer' variable which is composed of three
> > strings concatenated together to be submitted to BIOS via WMI call.
> > 'Buffer' will looks something as [size attribute][attribute][size
> > value][value][auth size][auth payload]
> > size is the length in bytes, attribute/value/auth are string represented in u16
>
> Even after this explanation I don't understand why it's called "the *
> buffer". Is that common terminology in this domain (in which case it's
> fine, I just haven't come across such term before)?
>

Point taken. Replaced 'buffer' variable name to 'authbuf'

> > > > + * admin password is configured in BIOS
> > > > + */
> > > > +
>
> [...snip...]
>
> > > > +/*
> > > > + * status_show - Reads SPM status
> > > > + */
> > > > +static ssize_t status_show(struct kobject *kobj, struct kobj_attribute
> > > > + *attr, char *buf)
> > > > +{
> > > > + int ret, i;
> > > > + struct secureplatform_provisioning_data data;
> > > > +
> > > > + ret = statusbin(kobj, attr, &data);
> > > > + if (ret < 0)
> > > > + goto status_exit;
> > >
> > > Can you calculate strnlen() from buf at this point, or is the result
> > > garbage? Should you return ret instead here?
> >
> > It should return the error instead.
Done!

> > >
> > > > +
> > > > + sysfs_emit(buf, "%s{\n", buf);
> > > > + sysfs_emit(buf, "%s\t\"State\": \"%s\",\n", buf,
> > > > + spm_state_types[data.state]);
> > > > + sysfs_emit(buf, "%s\t\"Version\": \"%d.%d\",\n", buf, data.version[0],
> > > > + data.version[1]);
> > > > +
> > > > + /*
> > > > + * state == 0 means secure platform management
> > > > + * feature is not configured in BIOS.
> > > > + */
> > > > + if (data.state == 0)
> > > > + goto status_exit;
> > > > +
> > > > + sysfs_emit(buf, "%s\t\"Nonce\": %d,\n", buf, data.nonce);
> > > > + sysfs_emit(buf, "%s\t\"FeaturesInUse\": %d,\n", buf, data.features);
> > > > + sysfs_emit(buf, "%s\t\"EndorsementKeyMod\": \"", buf);
> > > > +
> > > > + for (i = 255; i >= 0; i--)
> > > > + sysfs_emit(buf, "%s %u", buf, data.kek_mod[i]);
> > > > +
> > > > + sysfs_emit(buf, "%s \",\n", buf);
> > > > + sysfs_emit(buf, "%s\t\"SigningKeyMod\": \"", buf);
> > > > +
> > > > + for (i = 255; i >= 0; i--)
> > > > + sysfs_emit(buf, "%s %u", buf, data.sk_mod[i]);
> > > > +
> > > > + /* Return buf contents */
> > > > +
> > > > + sysfs_emit(buf, "%s \"\n", buf);
> > > > + sysfs_emit(buf, "%s}\n", buf);
> > > > +
> > > > +status_exit:
> > > > + return strnlen(buf, PAGE_SIZE);
> > > > +}
> > >
> > > Emit buf into buf? There's sysfs_emit_at(), however,
> > >
> > > while I'm far from sysfs formatting expert, this feels something that
> > > tries to expose more than one thing over same sysfs file. Shouldn't they
> > > be each in their own files?
> >
> > This concern was brought up in earlier reviews but it was decided to
> > allow returning the information as a single json file.
> > Because the information is part of the same structure and received in
> > a single WMI call, separating the components into multiple files can
> > cause the data read in one field to be stale by the time is read.
>
> Okay, makes more sense. Maybe add a comment that the return is a json
> string because that's not very obvious (I only realized now when you told
> me).
>
A comment will be added.

> The other point is still valid though, you should keep length in a
> variable and use sysfs_emit_at() to avoid printing buf into buf on
> every line.
>
I will update the function as indicated.

>
> --
> i.