On Tue, May 9, 2023 at 7:34 AM Ilpo Järvinen
<ilpo.jarvinen@xxxxxxxxxxxxxxx> 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 <jorge.lopez2@xxxxxx>
> >
> > ---
> > 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
<snip>
> > +
> > +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;
> > +}
Done!
> > +
> > +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.
>
Done!
> > + }
> > +
> > + 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:
>
get_password_instance_id() now returns -EIO when the instance is not
found otherwise it returns values 0...n
I will change all checks for ret value to ret < 0 to handle the
operation correctly.
> > + 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;
>
Done!
>
> > + }
> > +
> > + 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.
Done!
>
> > + 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.
Will do.
>
> > + 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?
Documentation was correct to avoid flags from kerneldoc.
>
> > + */
> > +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.
Done!
>
> > + 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.
What double spaces are you referring to?
>
> > + * 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
Done!
>
> > + 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.
Done!
>
> > + 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.
Done! I will correct it in all affected files.
>
> > + 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.
Done!
>
> > + 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???? :-)
Done!
>
> > + }
> > + }
> > + bioscfg_drv.password_instances_count = 0;
> > + kfree(bioscfg_drv.password_data);
> > + bioscfg_drv.password_data = NULL;
> > +}
> >
>
> --
> i.
