Hi,
On 11/9/22 21:00, Jorge Lopez wrote:
> Hi Hans,
>
> On Wed, Nov 9, 2022 at 12:10 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>>
>> Hi,
>>
>> On 11/9/22 18:24, Jorge Lopez wrote:
>>> HI Hans,
>>>
>>> Please see questions and comments below.
>>>
>>> On Tue, Nov 8, 2022 at 8:51 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>>>>
>>>> Hi Jorge,
>>>>
>>>> Review comments inline.
>>>>
>>>> On 10/20/22 22:10, Jorge Lopez wrote:
>>>>> The purpose for this patch is submit HP BIOSCFG driver to be list of
>>>>> HP Linux kernel drivers. The driver include a total of 12 files
>>>>> broken in several patches. This is set 1 of 4.
>>>>>
>>>>> 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 PC’s 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 BISOCFG 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 features such Secure Platform Management, Sure
>>>>> Admin, and Sure Start. Each section provides security feature
>>>>> description and identifies sysfs directories and files exposed by
>>>>> the driver.
>>>>>
>>>>> Many HP Commercial PC’s 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 PC’s 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 Sure Admin cryptographic signature-based authorization string
>>>>> that the BIOS will use to verify authorization to modify the setting.
>>>>>
>>>>> Signed-off-by: Jorge Lopez <jorge.lopez2@xxxxxx>
>>>>>
>>>>> ---
>>>>> Based on the latest platform-drivers-x86.git/for-next
>>>>> ---
>>>>> .../x86/hp/hp-bioscfg/biosattr-interface.c | 285 ++++++++
>>>>> drivers/platform/x86/hp/hp-bioscfg/bioscfg.h | 671 ++++++++++++++++++
>>>>> .../x86/hp/hp-bioscfg/enum-attributes.c | 521 ++++++++++++++
>>>>> 3 files changed, 1477 insertions(+)
>>>>> create mode 100644 drivers/platform/x86/hp/hp-bioscfg/biosattr-interface.c
>>>>> create mode 100644 drivers/platform/x86/hp/hp-bioscfg/bioscfg.h
>>>>> create mode 100644 drivers/platform/x86/hp/hp-bioscfg/enum-attributes.c
>>>>>
>>>>> diff --git a/drivers/platform/x86/hp/hp-bioscfg/biosattr-interface.c b/drivers/platform/x86/hp/hp-bioscfg/biosattr-interface.c
>>>>> new file mode 100644
>>>>> index 000000000000..f0c919bf3ab0
>>>>> --- /dev/null
>>>>> +++ b/drivers/platform/x86/hp/hp-bioscfg/biosattr-interface.c
>>>>> @@ -0,0 +1,285 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>> +/*
>>>>> + * Functions corresponding to methods under BIOS interface GUID
>>>>> + * for use with hp-bioscfg driver.
>>>>> + *
>>>>> + * Copyright (c) 2022 Hewlett-Packard Inc.
>>>>> + */
>>>>> +
>>>>> +#include <linux/wmi.h>
>>>>> +#include "bioscfg.h"
>>>>> +
>>>>> +#define SET_DEFAULT_VALUES_METHOD_ID 0x02
>>>>> +#define SET_BIOS_DEFAULTS_METHOD_ID 0x03
>>>>> +#define SET_ATTRIBUTE_METHOD_ID 0x04
>>>>> +
>>>>> +/*
>>>>> + * set_attribute() - Update an attribute value
>>>>> + * @a_name: The attribute name
>>>>> + * @a_value: The attribute value
>>>>> + *
>>>>> + * Sets an attribute to new value
>>>>> + */
>>>>> +int hp_set_attribute(const char *a_name, const char *a_value)
>>>>> +{
>>>>> + size_t security_area_size;
>>>>> + size_t a_name_size, a_value_size;
>>>>> + u16 *buffer = NULL;
>>>>> + u16 *start = NULL;
>>>>> + int buffer_size;
>>>>
>>>> You have 2 spaces between int and buffer_size here, please drop
>>>> one.
>>>>
>>>>
>>>>> + int ret;
>>>>> + int instance;
>>>>> + char *auth_empty_value = " ";
>>>>> +
>>>>> + mutex_lock(&bioscfg_drv.mutex);
>>>>> + if (!bioscfg_drv.bios_attr_wdev) {
>>>>> + ret = -ENODEV;
>>>>> + goto out_set_attribute;
>>>>> + }
>>>>> +
>>>>> + instance = get_password_instance_for_type(SETUP_PASSWD);
>>>>> + if (instance < 0)
>>>>> + goto out_set_attribute;
>>>>> +
>>>>> + if (strlen(bioscfg_drv.password_data[instance].current_password) == 0)
>>>>> + strncpy(bioscfg_drv.password_data[instance].current_password,
>>>>> + auth_empty_value,
>>>>> + sizeof(bioscfg_drv.password_data[instance].current_password));
>>>>
>>>> strncpy does not guarantee 0 termination of the destination buffer,
>>>> please use strscpy.
>>>>
>>>>> +
>>>>> + a_name_size = calculate_string_buffer(a_name);
>>>>> + a_value_size = calculate_string_buffer(a_value);
>>>>> + security_area_size = calculate_security_buffer(bioscfg_drv.password_data[instance].current_password);
>>>>> + buffer_size = a_name_size + a_value_size + security_area_size;
>>>>> +
>>>>> + buffer = kzalloc(buffer_size, GFP_KERNEL);
>>>>> + if (!buffer) {
>>>>> + ret = -ENOMEM;
>>>>> + goto out_set_attribute;
>>>>> + }
>>>>> +
>>>>> + /* build variables to set */
>>>>> + start = buffer;
>>>>> + start = ascii_to_utf16_unicode(start, a_name);
>>>>> + if (!start)
>>>>> + goto out_set_attribute;
>>>>> +
>>>>> + start = ascii_to_utf16_unicode(start, a_value);
>>>>> + if (!start)
>>>>> + goto out_set_attribute;
>>>>> +
>>>>> + populate_security_buffer(start, bioscfg_drv.password_data[instance].current_password);
>>>>> + ret = hp_wmi_set_bios_setting(buffer, buffer_size);
>>>>> +
>>>>> +
>>>>> +out_set_attribute:
>>>>> + kfree(buffer);
>>>>> + mutex_unlock(&bioscfg_drv.mutex);
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * hp_wmi_perform_query
>>>>> + *
>>>>> + * query: The commandtype (enum hp_wmi_commandtype)
>>>>> + * write: The command (enum hp_wmi_command)
>>>>> + * buffer: Buffer used as input and/or output
>>>>> + * insize: Size of input buffer
>>>>> + * outsize: Size of output buffer
>>>>> + *
>>>>> + * returns zero on success
>>>>> + * an HP WMI query specific error code (which is positive)
>>>>> + * -EINVAL if the query was not successful at all
>>>>> + * -EINVAL if the output buffer size exceeds buffersize
>>>>> + *
>>>>> + * Note: The buffersize must at least be the maximum of the input and output
>>>>> + * size. E.g. Battery info query is defined to have 1 byte input
>>>>> + * and 128 byte output. The caller would do:
>>>>> + * buffer = kzalloc(128, GFP_KERNEL);
>>>>> + * ret = hp_wmi_perform_query(HPWMI_BATTERY_QUERY, HPWMI_READ, buffer, 1, 128)
>>>>> + */
>>>>> +int hp_wmi_perform_query(int query, enum hp_wmi_command command, void *buffer, int insize, int outsize)
>>>>> +{
>>>>> + struct acpi_buffer input, output = { ACPI_ALLOCATE_BUFFER, NULL };
>>>>> + struct bios_return *bios_return;
>>>>> + union acpi_object *obj = NULL;
>>>>> + struct bios_args *args = NULL;
>>>>> + int mid, actual_insize, actual_outsize;
>>>>> + size_t bios_args_size;
>>>>> + int ret;
>>>>> +
>>>>> + mid = encode_outsize_for_pvsz(outsize);
>>>>> + if (WARN_ON(mid < 0))
>>>>> + return mid;
>>>>> +
>>>>> + actual_insize = insize;
>>>>> + bios_args_size = struct_size(args, data, insize);
>>>>> + args = kmalloc(bios_args_size, GFP_KERNEL);
>>>>> + if (!args)
>>>>> + return -ENOMEM;
>>>>> +
>>>>> + input.length = bios_args_size;
>>>>> + input.pointer = args;
>>>>> +
>>>>> + args->signature = 0x55434553;
>>>>> + args->command = command;
>>>>> + args->commandtype = query;
>>>>> + args->datasize = insize;
>>>>> + memcpy(args->data, buffer, flex_array_size(args, data, insize));
>>>>> +
>>>>> + ret = wmi_evaluate_method(HP_WMI_BIOS_GUID, 0, mid, &input, &output);
>>>>> + bioscfg_drv.last_wmi_status = ret;
>>>>> + if (ret)
>>>>> + goto out_free;
>>>>> +
>>>>> + obj = output.pointer;
>>>>> + if (!obj) {
>>>>> + ret = -EINVAL;
>>>>> + goto out_free;
>>>>> + }
>>>>> +
>>>>
>>>> You need to check the type of obj here before dereferencing
>>>> obj as if it is a buffer.
>>>>
>>>>> + bios_return = (struct bios_return *)obj->buffer.pointer;
>>>>> + ret = bios_return->return_code;
>>>>> + bioscfg_drv.last_wmi_status = ret;
>>>>> + if (ret) {
>>>>> + if (ret != HPWMI_RET_UNKNOWN_COMMAND &&
>>>>> + ret != HPWMI_RET_UNKNOWN_CMDTYPE)
>>>>> + pr_warn("query 0x%x returned error 0x%x\n", query, ret);
>>>>> + goto out_free;
>>>>> + }
>>>>> +
>>>>> + /* Ignore output data of zero size */
>>>>> + if (!outsize)
>>>>> + goto out_free;
>>>>> +
>>>>> + actual_outsize = min(outsize, (int)(obj->buffer.length - sizeof(*bios_return)));
>>>>> + memcpy(buffer, obj->buffer.pointer + sizeof(*bios_return), actual_outsize);
>>>>> + memset(buffer + actual_outsize, 0, outsize - actual_outsize);
>>>>> +
>>>>> +out_free:
>>>>> + kfree(obj);
>>>>> + kfree(args);
>>>>> + return ret;
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * ascii_to_utf16_unicode - Convert ascii string to UTF-16 unicode
>>>>> + *
>>>>> + * @p: Unicode buffer address
>>>>> + * @str: string to convert to unicode
>>>>> + *
>>>>> + * Returns a void pointer to the buffer containing unicode string
>>>>> + */
>>>>> +void *ascii_to_utf16_unicode(u16 *p, const u8 *str)
>>>>> +{
>>>>> + int len = strlen(str);
>>>>> + int ret;
>>>>> +
>>>>> + /*
>>>>> + * Add null character when reading an empty string
>>>>> + */
>>>>> + if (len == 0) {
>>>>> + *p++ = 2;
>>>>> + *p++ = (u8)0x00;
>>>>> + return p;
>>>>
>>>> This does not match with calculate_string_buffer() which will
>>>> return 2 for a 0 length string while you are using 4 bytes here.
>>>>
>>>> I guess this may also be why you need to use " " for
>>>> auth_empty_value above, so as to avoid this bug.
>>>>
>>> HP BIOS expects 2 characters when an empty string is being converted
>>> to u16 hence the reason for returning 2 instead of zero. This is an
>>> intended behavior and needed when allocating a buffer and writing to
>>> BIOS.
>>
>> Right I understand that, it wants 2 characters for the 16 bit length
>> word, but why not write 0 to that 16 bit length word. Why actually
>> say the string-buffer length is 2 bytes long / and then write
>> a 16-bit word with value 0?
>>
>> What you are doing now creates a 4 byte buffer like this:
>>
>> u8 buf[4] = { 0x02, 0x00, 0x00, 0x00 }
>>
>> Why not just create a 2 byte buffer like this:
>>
>> u8 buf[2] = { 0x00, 0x00 }
>>
>> ?
>>
>>
>> Also I'm wondering why the empty auth string is " " and
>> not "" ?
>>
>>
>
> The string returned for an empty string is 4 bytes. The returned
> string includes two bytes for the string size in bytes and the
> remaining bytes are the string.
> Size = 0x02, 0x00
> String = 0x00, 0x00
>
> All strings return include the string size in bytes followed by the u16 string
Right I understand that, but why is the "String = 0x00, 0x00"
there ? All the non-0-length strings are not 0 terminated,
why does the zero length string needs to be specified as length 2
(1 u16) and then have that u16 be a 0 terminator ?
Have you tried just using Size[2] = 0x00, 0x00 and String[0] for
an empty string?
###
Also you did not answer this separate question:
I'm wondering why the empty auth string is " " and not "" ?
Regards,
Hans
