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

[Jorge Lopez]

On Tue, May 9, 2023 at 8:15 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
> > ---
> >  .../x86/hp/hp-bioscfg/ordered-attributes.c    | 443 ++++++++++++++++++
> >  1 file changed, 443 insertions(+)
> >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> >
> > diff --git a/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c b/drivers/platform/x86/hp/hp-bioscfg/ordered-attributes.c
> > new file mode 100644

<snip>

> > +     strscpy(ordered_list_data->common.display_name_language_code,
> > +             LANG_CODE_STR,
> > +             sizeof(ordered_list_data->common.display_name_language_code));
> > +
> > +     for (elem = 1, eloc = 1; elem < order_obj_count; elem++, eloc++) {
> > +             /* ONLY look at the first ORDERED_ELEM_CNT elements */
> > +             if (eloc == ORD_ELEM_CNT)
> > +                     goto exit_list_package;
> > +
> > +             switch (order_obj[elem].type) {
> > +             case ACPI_TYPE_STRING:
> > +
>
> Extra newline.

Done!
>
> > +                     if (elem != PREREQUISITES && elem != ORD_LIST_ELEMENTS) {
> > +                             ret = convert_hexstr_to_str(order_obj[elem].string.pointer,
> > +                                                         order_obj[elem].string.length,
> > +                                                         &str_value, &value_len);
> > +                             if (ret)
> > +                                     continue;
> > +                     }
> > +                     break;
> > +             case ACPI_TYPE_INTEGER:
> > +                     int_value = (u32)order_obj[elem].integer.value;
> > +                     break;
> > +             default:
> > +                     pr_warn("Unsupported object type [%d]\n", order_obj[elem].type);
> > +                     continue;
> > +             }
> > +
> > +             /* Check that both expected and read object type match */
> > +             if (expected_order_types[eloc] != order_obj[elem].type) {
> > +                     pr_err("Error expected type %d for elem  %d, but got type %d instead\n",
>
> Extra space before %d.
Done!
>
> > +                            expected_order_types[eloc], elem, order_obj[elem].type);
> > +                     return -EIO;
> > +             }
> > +
<snip>
> > +                     kfree(tmpstr);
> > +                     break;
> > +             default:
> > +                     pr_warn("Invalid element: %d found in Ordered_List attribute or data may be malformed\n", elem);
> > +                     break;
> > +             }
> > +             kfree(tmpstr);
> > +             kfree(str_value);
> > +     }
> > +
> > +exit_list_package:
> > +     kfree(tmpstr);
> > +     kfree(str_value);
> > +     return 0;
> > +}
>
> Looks double and triple frees in this function.

Done!
>
> After reading the about same things once again, I started to wonder if
> some of that switch content could be moved into a common helper (which
> takes e.g. the xx->common pointer as parameter and perhaps some other
> carefully selected pointers). There's a lots of duplication.
>

I will look into how the common data can be implemented with a helper.

> > +/**
> > + * populate_ordered_list_buffer_data() - Populate all properties of an
> > + * instance under ordered list attribute
> > + *
> > + * @buffer_ptr: Buffer pointer
> > + * @buffer_size: Buffer size
> > + * @instance_id: The instance to enumerate
> > + * @attr_name_kobj: The parent kernel object
> > + */
> > +int populate_ordered_list_buffer_data(u8 *buffer_ptr, u32 *buffer_size, int instance_id,
> > +                                   struct kobject *attr_name_kobj)
> > +{
> > +     struct ordered_list_data *ordered_list_data = &bioscfg_drv.ordered_list_data[instance_id];
> > +
> > +     ordered_list_data->attr_name_kobj = attr_name_kobj;
> > +
> > +     /* Populate ordered list elements */
> > +     populate_ordered_list_elements_from_buffer(buffer_ptr, buffer_size,
> > +                                                instance_id);
> > +     update_attribute_permissions(ordered_list_data->common.is_readonly,
> > +                                  &ordered_list_current_val);
> > +     friendly_user_name_update(ordered_list_data->common.path,
> > +                               attr_name_kobj->name,
> > +                               ordered_list_data->common.display_name,
> > +                               sizeof(ordered_list_data->common.display_name));
> > +
> > +     return sysfs_create_group(attr_name_kobj, &ordered_list_attr_group);
> > +}
> > +
> > +int populate_ordered_list_elements_from_buffer(u8 *buffer_ptr, u32 *buffer_size,
> > +                                            int instance_id)
> > +{
> > +     int reqs;
> > +     int values;
> > +     struct ordered_list_data *ordered_list_data = &bioscfg_drv.ordered_list_data[instance_id];
> > +
> > +     strscpy(ordered_list_data->common.display_name_language_code,
> > +             LANG_CODE_STR,
> > +             sizeof(ordered_list_data->common.display_name_language_code));
> > +
> > +     // VALUE:
> > +     get_string_from_buffer(&buffer_ptr, buffer_size, ordered_list_data->current_value,
> > +                            sizeof(ordered_list_data->current_value));
> > +
> > +     // PATH:
> > +     get_string_from_buffer(&buffer_ptr, buffer_size, ordered_list_data->common.path,
> > +                            sizeof(ordered_list_data->common.path));
> > +
> > +     // IS_READONLY:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.is_readonly);
> > +
> > +     //DISPLAY_IN_UI:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.display_in_ui);
> > +
> > +     // REQUIRES_PHYSICAL_PRESENCE:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.requires_physical_presence);
> > +
> > +     // SEQUENCE:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.sequence);
> > +
> > +     // PREREQUISITES_SIZE:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.prerequisites_size);
> > +
> > +     if (ordered_list_data->common.prerequisites_size > MAX_PREREQUISITES_SIZE) {
> > +             /* Report a message and limit prerequisite size to maximum value */
> > +             pr_warn("String Prerequisites size value exceeded the maximum number of elements supported or data may be malformed\n");
> > +             ordered_list_data->common.prerequisites_size = MAX_PREREQUISITES_SIZE;
> > +     }
> > +
> > +     // PREREQUISITES:
> > +     for (reqs = 0;
> > +          reqs < ordered_list_data->common.prerequisites_size && reqs < MAX_PREREQUISITES_SIZE;
> > +          reqs++)
> > +             get_string_from_buffer(&buffer_ptr, buffer_size,
> > +                                    ordered_list_data->common.prerequisites[reqs],
> > +                                    sizeof(ordered_list_data->common.prerequisites[reqs]));
> > +
> > +     // SECURITY_LEVEL:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->common.security_level);
> > +
> > +     // ORD_LIST_SIZE:
> > +     get_integer_from_buffer(&buffer_ptr, buffer_size,
> > +                             &ordered_list_data->elements_size);
> > +
> > +     if (ordered_list_data->elements_size > MAX_ELEMENTS_SIZE) {
> > +             /* Report a message and limit elements size to maximum value */
> > +             pr_warn("Ordered List size value exceeded the maximum number of elements supported or data may be malformed\n");
> > +             ordered_list_data->elements_size = MAX_ELEMENTS_SIZE;
> > +     }
> > +
> > +     // ORD_LIST_ELEMENTS:
> > +     for (values = 0; values < ordered_list_data->elements_size && values < MAX_ELEMENTS_SIZE;
> > +          values++)
> > +             get_string_from_buffer(&buffer_ptr, buffer_size,
> > +                                    ordered_list_data->elements[values],
> > +                                    sizeof(ordered_list_data->elements[values]));
> > +
> > +     return 0;
> > +}
>
> Same here. Pass buffer, buffer_size and common into a helper? Maybe some
> other parameters too to cover many/all of the cases?

I will investigate how I can use more helpers to minimize the duplication

>
> > +
> > +/**
> > + * exit_ordered_list_attributes() - Clear all attribute data
> > + *
> > + * Clears all data allocated for this group of attributes
> > + */
> > +void exit_ordered_list_attributes(void)
> > +{
> > +     int instance_id;
> > +
> > +     for (instance_id = 0; instance_id < bioscfg_drv.ordered_list_instances_count;
> > +          instance_id++) {
> > +             struct kobject *attr_name_kobj =
> > +                     bioscfg_drv.ordered_list_data[instance_id].attr_name_kobj;
> > +
> > +             if (attr_name_kobj)
> > +                     sysfs_remove_group(attr_name_kobj,
> > +                                        &ordered_list_attr_group);
> > +     }
> > +     bioscfg_drv.ordered_list_instances_count = 0;
> > +
> > +     kfree(bioscfg_drv.ordered_list_data);
> > +     bioscfg_drv.ordered_list_data = NULL;
> > +}
> >
>
> --
>  i.