[PATCH v3 1/3] efi_loader: add SMBIOS table measurement

Simon Glass sjg at chromium.org
Tue Nov 2 15:56:03 CET 2021


Hi Masahisa,

On Thu, 21 Oct 2021 at 07:41, Masahisa Kojima
<masahisa.kojima at linaro.org> wrote:
>
>  is
>
> On Thu, 21 Oct 2021 at 22:04, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >
> >
> >
> > On 10/21/21 14:52, Masahisa Kojima wrote:
> > > On Thu, 21 Oct 2021 at 17:49, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > >>
> > >>
> > >>
> > >> On 10/21/21 10:38, Masahisa Kojima wrote:
> > >>> On Thu, 21 Oct 2021 at 09:17, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > >>>>
> > >>>> On 10/1/21 1:18 PM, Masahisa Kojima wrote:
> > >>>>> TCG PC Client spec requires to measure the SMBIOS
> > >>>>
> > >>>> I guess you mean the "TCG PC Client Platform Firmware Profile
> > >>>> Specification"? Please, provide the full name in the commit message.
> > >>>
> > >>> Sorry, I will write full spec name.
> > >>>
> > >>>>
> > >>>>> table that contain static configuration information
> > >>>>> (e.g. Platform Manufacturer Enterprise Number assigned by IANA,
> > >>>>> platform model number, Vendor and Device IDs for each SMBIOS table).
> > >>>>>
> > >>>>> The device- and environment-dependent information such as
> > >>>>> serial number is cleared to zero or space character for
> > >>>>> the measurement.
> > >>>>
> > >>>> This contradicts the spec requiring the device IDs (i.e. the serial
> > >>>> number) to be measured. You don't want to get the same measurement when
> > >>>> the device is swapped.
> > >>>
> > >>> In my understanding, the same measurement result is expected
> > >>> among one product. Even if the device is swapped, measurement is the same.
> > >>> If device unique information such as serial number
> > >>> is included in the measurement, attestation process will be very complicated.
> > >>>
> > >>>>
> > >>>>>
> > >>>>> Existing smbios_string() function returns pointer to the string
> > >>>>> with const qualifier, but exisintg use case is updating version
> > >>>>> string and const qualifier must be removed.
> > >>>>> This commit removes const qualifier from smbios_string()
> > >>>>> return value and reuses to clear the strings for the measurement.
> > >>>>>
> > >>>>> This commit also fixes the following compiler warning:
> > >>>>>
> > >>>>> lib/smbios-parser.c:59:39: warning: cast to pointer from integer of
> > >>>>> different size [-Wint-to-pointer-cast]
> > >>>>>      const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
> > >>>>>
> > >>>>> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> > >>>>> ---
> > >>>>>
> > >>>>> Changes in v3:
> > >>>>> - TCG spec says EV_SEPARATOR must be the last,
> > >>>>>      swap the order of measurement
> > >>>>>
> > >>>>> Changes in v2:
> > >>>>> - use flexible array for table_entry field
> > >>>>> - modify funtion name to find_smbios_table()
> > >>>>> - remove unnecessary const qualifier from smbios_string()
> > >>>>> - create non-const version of next_header()
> > >>>>>
> > >>>>>     include/efi_loader.h          |   2 +
> > >>>>>     include/efi_tcg2.h            |  15 ++++
> > >>>>>     include/smbios.h              |  17 +++-
> > >>>>>     lib/efi_loader/Kconfig        |   1 +
> > >>>>>     lib/efi_loader/efi_boottime.c |   2 +
> > >>>>>     lib/efi_loader/efi_smbios.c   |   2 -
> > >>>>>     lib/efi_loader/efi_tcg2.c     |  84 +++++++++++++++++++
> > >>>>>     lib/smbios-parser.c           | 152 +++++++++++++++++++++++++++++++---
> > >>>>>     8 files changed, 261 insertions(+), 14 deletions(-)
> > >>>>>
> > >>>>> diff --git a/include/efi_loader.h b/include/efi_loader.h
> > >>>>> index c440962fe5..13f0c24058 100644
> > >>>>> --- a/include/efi_loader.h
> > >>>>> +++ b/include/efi_loader.h
> > >>>>> @@ -308,6 +308,8 @@ extern const efi_guid_t efi_guid_capsule_report;
> > >>>>>     extern const efi_guid_t efi_guid_firmware_management_protocol;
> > >>>>>     /* GUID for the ESRT */
> > >>>>>     extern const efi_guid_t efi_esrt_guid;
> > >>>>> +/* GUID of the SMBIOS table */
> > >>>>> +extern const efi_guid_t smbios_guid;
> > >>>>>
> > >>>>>     extern char __efi_runtime_start[], __efi_runtime_stop[];
> > >>>>>     extern char __efi_runtime_rel_start[], __efi_runtime_rel_stop[];
> > >>>>> diff --git a/include/efi_tcg2.h b/include/efi_tcg2.h
> > >>>>> index 8f02d4fb0b..ca66695b39 100644
> > >>>>> --- a/include/efi_tcg2.h
> > >>>>> +++ b/include/efi_tcg2.h
> > >>>>> @@ -210,6 +210,21 @@ struct efi_tcg2_uefi_variable_data {
> > >>>>>         u8 variable_data[1];
> > >>>>>     };
> > >>>>>
> > >>>>> +/**
> > >>>>> + * struct tdUEFI_HANDOFF_TABLE_POINTERS2 - event log structure of SMBOIS tables
> > >>>>> + * @table_description_size:  size of table description
> > >>>>> + * @table_description:               table description
> > >>>>> + * @number_of_tables:                number of uefi configuration table
> > >>>>> + * @table_entry:             uefi configuration table entry
> > >>>>> + */
> > >>>>> +#define SMBIOS_HANDOFF_TABLE_DESC  "SmbiosTable"
> > >>>>> +struct smbios_handoff_table_pointers2 {
> > >>>>> +     u8 table_description_size;
> > >>>>> +     u8 table_description[sizeof(SMBIOS_HANDOFF_TABLE_DESC)];
> > >>>>> +     u64 number_of_tables;
> > >>>>> +     struct efi_configuration_table table_entry[];
> > >>>>> +} __packed;
> > >>>>> +
> > >>>>>     struct efi_tcg2_protocol {
> > >>>>>         efi_status_t (EFIAPI * get_capability)(struct efi_tcg2_protocol *this,
> > >>>>>                                                struct efi_tcg2_boot_service_capability *capability);
> > >>>>> diff --git a/include/smbios.h b/include/smbios.h
> > >>>>> index aa6b6f3849..acfcbfe2ca 100644
> > >>>>> --- a/include/smbios.h
> > >>>>> +++ b/include/smbios.h
> > >>>>> @@ -260,9 +260,9 @@ const struct smbios_header *smbios_header(const struct smbios_entry *entry, int
> > >>>>>      *
> > >>>>>      * @header:    pointer to struct smbios_header
> > >>>>>      * @index:     string index
> > >>>>> - * @return:    NULL or a valid const char pointer
> > >>>>> + * @return:    NULL or a valid char pointer
> > >>>>>      */
> > >>>>> -const char *smbios_string(const struct smbios_header *header, int index);
> > >>>>> +char *smbios_string(const struct smbios_header *header, int index);
> > >>>>
> > >>>> This looks wrong. Your code is changing the actual SMBIOS table that we
> > >>>> will pass via an UEFI configuration table. Why would you do this? For
> > >>>> instance the serial number is an information that you actually want to
> > >>>> see in the operating system. I think you should first copy the string
> > >>>> and then manipulate the copy if this is necessary for the measurement.
> > >>>
> > >>> No, I prepare the copied SMBIOS table and update it for the measurement.
> > >>
> > >> Then why do you move from const char * to char *?
> > >>
> > >> You are passing in a const struct smbios_header *header. This implies
> > >> that every part of this structure is const. This is a contract with the
> > >> caller that every part of the table will be treated as const. You should
> > >> not return anything as not const.
> > >
> > > struct smbios_header only has following members.
> > >
> > > struct __packed smbios_header {
> > >          u8 type;
> > >          u8 length;
> > >          u16 handle;
> > > };
> > >
> > > SMBIOS table is like following.
> > >
> > > struct smbios_header;
> > > struct type0_specific_info;
> > > "index1 string\0"
> > > "index2 string\0"
> > > "\0\0"
> > > struct smbios_header;
> > > struct type1_specific_info;
> > > "index1 string\0"
> > > ...
> > >
> > > + char *smbios_string(const struct smbios_header *header, int index)
> > >
> > > smbios_string() function will not update input smbios_header, and return
> > > the char pointer to the string specified by "index" argument, to
> > > update the string
> > > by caller.
> > > So I think there is no problem.
> >
> > I would prefer if you leave the signature as is.
> >
> > If header points to a copy that your code has created, you can cast the
> > return value to (char *). That way the function does what is expected
> > and the deviation will be restricted to your specific usage.
>
> There is one existing use case of smbios_string() in
> smbios-parser.c::smbios_update_version_full().
> smbios_update_version_full() uses smbios_string() to get the
> version string pointer to update the version string.
> So I think smbios_string() is designed to return the non-const char*.

Not really, but as you say there is a cast when updating the version.
Perhaps we should have a non-const version of the function?


- Simon


> I also think removing const by type cast is unsafe.
>
> Best Regards,
> Masahisa Kojima
>
> >
> > Best regards
> >
> > Heinrich
> >
> > >
> > > Best Regards,
> > > Masahisa Kojima
> > >
> > >
> > > Thanks,
> > > Masahisa Kojima
> > >
> > >>
> > >> Best regards
> > >>
> > >> Heinrich
> > >>
> > >>>
> > >>> tcg2_measure_smbios():
> > >>> +       smbios_copy = (struct smbios_header
> > >>> *)((uintptr_t)&event->table_entry[0].table);
> > >>> +       memcpy(&event->table_entry[0].table,
> > >>> +              (void *)((uintptr_t)entry->struct_table_address),
> > >>> +              entry->struct_table_length);
> > >>> +
> > >>> +       smbios_prepare_measurement(entry, smbios_copy);
> > >>>
> > >>> I have tested that linux can show the original SMBIOS table
> > >>> by "dmidocode" command.
> > >>>
> > >>> Thanks,
> > >>> Masahisa Kojima
> > >>>
> > >>>>
> > >>>> Best regards
> > >>>>
> > >>>> Heinrich
> > >>>>
> > >>>>>
> > >>>>>     /**
> > >>>>>      * smbios_update_version() - Update the version string
> > >>>>> @@ -292,4 +292,17 @@ int smbios_update_version(const char *version);
> > >>>>>      */
> > >>>>>     int smbios_update_version_full(void *smbios_tab, const char *version);
> > >>>>>
> > >>>>> +/**
> > >>>>> + * smbios_prepare_measurement() - Update smbios table for the measurement
> > >>>>> + *
> > >>>>> + * TCG specification requires to measure static configuration information.
> > >>>>> + * This function clear the device dependent parameters such as
> > >>>>> + * serial number for the measurement.
> > >>>>> + *
> > >>>>> + * @entry: pointer to a struct smbios_entry
> > >>>>> + * @header: pointer to a struct smbios_header
> > >>>>> + */
> > >>>>> +void smbios_prepare_measurement(const struct smbios_entry *entry,
> > >>>>> +                             struct smbios_header *header);
> > >>>>> +
> > >>>>>     #endif /* _SMBIOS_H_ */
> > >>>>> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > >>>>> index f48d9e8b51..e691b1ea96 100644
> > >>>>> --- a/lib/efi_loader/Kconfig
> > >>>>> +++ b/lib/efi_loader/Kconfig
> > >>>>> @@ -320,6 +320,7 @@ config EFI_TCG2_PROTOCOL
> > >>>>>         select SHA384
> > >>>>>         select SHA512
> > >>>>>         select HASH
> > >>>>> +     select SMBIOS_PARSER
> > >>>>>         help
> > >>>>>           Provide a EFI_TCG2_PROTOCOL implementation using the TPM hardware
> > >>>>>           of the platform.
> > >>>>> diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
> > >>>>> index f0283b539e..701e2212c8 100644
> > >>>>> --- a/lib/efi_loader/efi_boottime.c
> > >>>>> +++ b/lib/efi_loader/efi_boottime.c
> > >>>>> @@ -86,6 +86,8 @@ const efi_guid_t efi_guid_event_group_reset_system =
> > >>>>>     /* GUIDs of the Load File and Load File2 protocols */
> > >>>>>     const efi_guid_t efi_guid_load_file_protocol = EFI_LOAD_FILE_PROTOCOL_GUID;
> > >>>>>     const efi_guid_t efi_guid_load_file2_protocol = EFI_LOAD_FILE2_PROTOCOL_GUID;
> > >>>>> +/* GUID of the SMBIOS table */
> > >>>>> +const efi_guid_t smbios_guid = SMBIOS_TABLE_GUID;
> > >>>>>
> > >>>>>     static efi_status_t EFIAPI efi_disconnect_controller(
> > >>>>>                                         efi_handle_t controller_handle,
> > >>>>> diff --git a/lib/efi_loader/efi_smbios.c b/lib/efi_loader/efi_smbios.c
> > >>>>> index 2eb4cb1c1a..fc0b23397c 100644
> > >>>>> --- a/lib/efi_loader/efi_smbios.c
> > >>>>> +++ b/lib/efi_loader/efi_smbios.c
> > >>>>> @@ -13,8 +13,6 @@
> > >>>>>     #include <mapmem.h>
> > >>>>>     #include <smbios.h>
> > >>>>>
> > >>>>> -static const efi_guid_t smbios_guid = SMBIOS_TABLE_GUID;
> > >>>>> -
> > >>>>>     /*
> > >>>>>      * Install the SMBIOS table as a configuration table.
> > >>>>>      *
> > >>>>> diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> > >>>>> index d3b8f93f14..f14d4d6da1 100644
> > >>>>> --- a/lib/efi_loader/efi_tcg2.c
> > >>>>> +++ b/lib/efi_loader/efi_tcg2.c
> > >>>>> @@ -14,6 +14,7 @@
> > >>>>>     #include <efi_tcg2.h>
> > >>>>>     #include <log.h>
> > >>>>>     #include <malloc.h>
> > >>>>> +#include <smbios.h>
> > >>>>>     #include <version.h>
> > >>>>>     #include <tpm-v2.h>
> > >>>>>     #include <u-boot/hash-checksum.h>
> > >>>>> @@ -1455,6 +1456,81 @@ error:
> > >>>>>         return ret;
> > >>>>>     }
> > >>>>>
> > >>>>> +/**
> > >>>>> + * tcg2_measure_smbios() - measure smbios table
> > >>>>> + *
> > >>>>> + * @dev:     TPM device
> > >>>>> + * @entry:   pointer to the smbios_entry structure
> > >>>>> + *
> > >>>>> + * Return:   status code
> > >>>>> + */
> > >>>>> +static efi_status_t
> > >>>>> +tcg2_measure_smbios(struct udevice *dev,
> > >>>>> +                 const struct smbios_entry *entry)
> > >>>>> +{
> > >>>>> +     efi_status_t ret;
> > >>>>> +     struct smbios_header *smbios_copy;
> > >>>>> +     struct smbios_handoff_table_pointers2 *event = NULL;
> > >>>>> +     u32 event_size;
> > >>>>> +
> > >>>>> +     /*
> > >>>>> +      * TCG PC Client PFP Spec says
> > >>>>> +      * "SMBIOS structures that contain static configuration information
> > >>>>> +      * (e.g. Platform Manufacturer Enterprise Number assigned by IANA,
> > >>>>> +      * platform model number, Vendor and Device IDs for each SMBIOS table)
> > >>>>> +      * that is relevant to the security of the platform MUST be measured".
> > >>>>> +      * Device dependent parameters such as serial number are cleared to
> > >>>>> +      * zero or spaces for the measurement.
> > >>>>> +      */
> > >>>>> +     event_size = sizeof(struct smbios_handoff_table_pointers2) +
> > >>>>> +                  FIELD_SIZEOF(struct efi_configuration_table, guid) +
> > >>>>> +                  entry->struct_table_length;
> > >>>>> +     event = calloc(1, event_size);
> > >>>>> +     if (!event) {
> > >>>>> +             ret = EFI_OUT_OF_RESOURCES;
> > >>>>> +             goto out;
> > >>>>> +     }
> > >>>>> +
> > >>>>> +     event->table_description_size = sizeof(SMBIOS_HANDOFF_TABLE_DESC);
> > >>>>> +     memcpy(event->table_description, SMBIOS_HANDOFF_TABLE_DESC,
> > >>>>> +            sizeof(SMBIOS_HANDOFF_TABLE_DESC));
> > >>>>> +     put_unaligned_le64(1, &event->number_of_tables);
> > >>>>> +     guidcpy(&event->table_entry[0].guid, &smbios_guid);
> > >>>>> +     smbios_copy = (struct smbios_header *)((uintptr_t)&event->table_entry[0].table);
> > >>>>> +     memcpy(&event->table_entry[0].table,
> > >>>>> +            (void *)((uintptr_t)entry->struct_table_address),
> > >>>>> +            entry->struct_table_length);
> > >>>>> +
> > >>>>> +     smbios_prepare_measurement(entry, smbios_copy);
> > >>>>> +
> > >>>>> +     ret = tcg2_measure_event(dev, 1, EV_EFI_HANDOFF_TABLES2, event_size,
> > >>>>> +                              (u8 *)event);
> > >>>>> +     if (ret != EFI_SUCCESS)
> > >>>>> +             goto out;
> > >>>>> +
> > >>>>> +out:
> > >>>>> +     free(event);
> > >>>>> +
> > >>>>> +     return ret;
> > >>>>> +}
> > >>>>> +
> > >>>>> +/**
> > >>>>> + * find_smbios_table() - find smbios table
> > >>>>> + *
> > >>>>> + * Return:   pointer to the smbios table
> > >>>>> + */
> > >>>>> +static void *find_smbios_table(void)
> > >>>>> +{
> > >>>>> +     u32 i;
> > >>>>> +
> > >>>>> +     for (i = 0; i < systab.nr_tables; i++) {
> > >>>>> +             if (!guidcmp(&smbios_guid, &systab.tables[i].guid))
> > >>>>> +                     return systab.tables[i].table;
> > >>>>> +     }
> > >>>>> +
> > >>>>> +     return NULL;
> > >>>>> +}
> > >>>>> +
> > >>>>>     /**
> > >>>>>      * efi_tcg2_measure_efi_app_invocation() - measure efi app invocation
> > >>>>>      *
> > >>>>> @@ -1466,6 +1542,7 @@ efi_status_t efi_tcg2_measure_efi_app_invocation(void)
> > >>>>>         u32 pcr_index;
> > >>>>>         struct udevice *dev;
> > >>>>>         u32 event = 0;
> > >>>>> +     struct smbios_entry *entry;
> > >>>>>
> > >>>>>         if (tcg2_efi_app_invoked)
> > >>>>>                 return EFI_SUCCESS;
> > >>>>> @@ -1484,6 +1561,13 @@ efi_status_t efi_tcg2_measure_efi_app_invocation(void)
> > >>>>>         if (ret != EFI_SUCCESS)
> > >>>>>                 goto out;
> > >>>>>
> > >>>>> +     entry = (struct smbios_entry *)find_smbios_table();
> > >>>>> +     if (entry) {
> > >>>>> +             ret = tcg2_measure_smbios(dev, entry);
> > >>>>> +             if (ret != EFI_SUCCESS)
> > >>>>> +                     goto out;
> > >>>>> +     }
> > >>>>> +
> > >>>>>         for (pcr_index = 0; pcr_index <= 7; pcr_index++) {
> > >>>>>                 ret = tcg2_measure_event(dev, pcr_index, EV_SEPARATOR,
> > >>>>>                                          sizeof(event), (u8 *)&event);
> > >>>>> diff --git a/lib/smbios-parser.c b/lib/smbios-parser.c
> > >>>>> index 34203f952c..596a967302 100644
> > >>>>> --- a/lib/smbios-parser.c
> > >>>>> +++ b/lib/smbios-parser.c
> > >>>>> @@ -39,10 +39,8 @@ const struct smbios_entry *smbios_entry(u64 address, u32 size)
> > >>>>>         return entry;
> > >>>>>     }
> > >>>>>
> > >>>>> -static const struct smbios_header *next_header(const struct smbios_header *curr)
> > >>>>> +static u8 *find_next_header(u8 *pos)
> > >>>>>     {
> > >>>>> -     u8 *pos = ((u8 *)curr) + curr->length;
> > >>>>> -
> > >>>>>         /* search for _double_ NULL bytes */
> > >>>>>         while (!((*pos == 0) && (*(pos + 1) == 0)))
> > >>>>>                 pos++;
> > >>>>> @@ -50,13 +48,27 @@ static const struct smbios_header *next_header(const struct smbios_header *curr)
> > >>>>>         /* step behind the double NULL bytes */
> > >>>>>         pos += 2;
> > >>>>>
> > >>>>> -     return (struct smbios_header *)pos;
> > >>>>> +     return pos;
> > >>>>> +}
> > >>>>> +
> > >>>>> +static struct smbios_header *get_next_header(struct smbios_header *curr)
> > >>>>> +{
> > >>>>> +     u8 *pos = ((u8 *)curr) + curr->length;
> > >>>>> +
> > >>>>> +     return (struct smbios_header *)find_next_header(pos);
> > >>>>> +}
> > >>>>> +
> > >>>>> +static const struct smbios_header *next_header(const struct smbios_header *curr)
> > >>>>> +{
> > >>>>> +     u8 *pos = ((u8 *)curr) + curr->length;
> > >>>>> +
> > >>>>> +     return (struct smbios_header *)find_next_header(pos);
> > >>>>>     }
> > >>>>>
> > >>>>>     const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type)
> > >>>>>     {
> > >>>>>         const unsigned int num_header = entry->struct_count;
> > >>>>> -     const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
> > >>>>> +     const struct smbios_header *header = (struct smbios_header *)((uintptr_t)entry->struct_table_address);
> > >>>>>
> > >>>>>         for (unsigned int i = 0; i < num_header; i++) {
> > >>>>>                 if (header->type == type)
> > >>>>> @@ -68,8 +80,8 @@ const struct smbios_header *smbios_header(const struct smbios_entry *entry, int
> > >>>>>         return NULL;
> > >>>>>     }
> > >>>>>
> > >>>>> -static const char *string_from_smbios_table(const struct smbios_header *header,
> > >>>>> -                                           int idx)
> > >>>>> +static char *string_from_smbios_table(const struct smbios_header *header,
> > >>>>> +                                   int idx)
> > >>>>>     {
> > >>>>>         unsigned int i = 1;
> > >>>>>         u8 *pos;
> > >>>>> @@ -86,10 +98,10 @@ static const char *string_from_smbios_table(const struct smbios_header *header,
> > >>>>>                 pos++;
> > >>>>>         }
> > >>>>>
> > >>>>> -     return (const char *)pos;
> > >>>>> +     return (char *)pos;
> > >>>>>     }
> > >>>>>
> > >>>>> -const char *smbios_string(const struct smbios_header *header, int index)
> > >>>>> +char *smbios_string(const struct smbios_header *header, int index)
> > >>>>>     {
> > >>>>>         if (!header)
> > >>>>>                 return NULL;
> > >>>>> @@ -109,7 +121,7 @@ int smbios_update_version_full(void *smbios_tab, const char *version)
> > >>>>>         if (!hdr)
> > >>>>>                 return log_msg_ret("tab", -ENOENT);
> > >>>>>         bios = (struct smbios_type0 *)hdr;
> > >>>>> -     ptr = (char *)smbios_string(hdr, bios->bios_ver);
> > >>>>> +     ptr = smbios_string(hdr, bios->bios_ver);
> > >>>>>         if (!ptr)
> > >>>>>                 return log_msg_ret("str", -ENOMEDIUM);
> > >>>>>
> > >>>>> @@ -132,3 +144,123 @@ int smbios_update_version_full(void *smbios_tab, const char *version)
> > >>>>>
> > >>>>>         return 0;
> > >>>>>     }
> > >>>>> +
> > >>>>> +struct smbios_filter_param {
> > >>>>> +     u32 offset;
> > >>>>> +     u32 size;
> > >>>>> +     bool is_string;
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_table {
> > >>>>> +     int type;
> > >>>>> +     struct smbios_filter_param *params;
> > >>>>> +     u32 count;
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_param smbios_type1_filter_params[] = {
> > >>>>> +     {offsetof(struct smbios_type1, serial_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type1, serial_number), true},
> > >>>>> +     {offsetof(struct smbios_type1, uuid),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type1, uuid), false},
> > >>>>> +     {offsetof(struct smbios_type1, wakeup_type),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type1, wakeup_type), false},
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_param smbios_type2_filter_params[] = {
> > >>>>> +     {offsetof(struct smbios_type2, serial_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type2, serial_number), true},
> > >>>>> +     {offsetof(struct smbios_type2, chassis_location),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type2, chassis_location), false},
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_param smbios_type3_filter_params[] = {
> > >>>>> +     {offsetof(struct smbios_type3, serial_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type3, serial_number), true},
> > >>>>> +     {offsetof(struct smbios_type3, asset_tag_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type3, asset_tag_number), true},
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_param smbios_type4_filter_params[] = {
> > >>>>> +     {offsetof(struct smbios_type4, serial_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, serial_number), true},
> > >>>>> +     {offsetof(struct smbios_type4, asset_tag),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, asset_tag), true},
> > >>>>> +     {offsetof(struct smbios_type4, part_number),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, part_number), true},
> > >>>>> +     {offsetof(struct smbios_type4, core_count),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, core_count), false},
> > >>>>> +     {offsetof(struct smbios_type4, core_enabled),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, core_enabled), false},
> > >>>>> +     {offsetof(struct smbios_type4, thread_count),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, thread_count), false},
> > >>>>> +     {offsetof(struct smbios_type4, core_count2),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, core_count2), false},
> > >>>>> +     {offsetof(struct smbios_type4, core_enabled2),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, core_enabled2), false},
> > >>>>> +     {offsetof(struct smbios_type4, thread_count),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, thread_count2), false},
> > >>>>> +     {offsetof(struct smbios_type4, voltage),
> > >>>>> +      FIELD_SIZEOF(struct smbios_type4, voltage), false},
> > >>>>> +};
> > >>>>> +
> > >>>>> +struct smbios_filter_table smbios_filter_tables[] = {
> > >>>>> +     {SMBIOS_SYSTEM_INFORMATION, smbios_type1_filter_params,
> > >>>>> +      ARRAY_SIZE(smbios_type1_filter_params)},
> > >>>>> +     {SMBIOS_BOARD_INFORMATION, smbios_type2_filter_params,
> > >>>>> +      ARRAY_SIZE(smbios_type2_filter_params)},
> > >>>>> +     {SMBIOS_SYSTEM_ENCLOSURE, smbios_type3_filter_params,
> > >>>>> +      ARRAY_SIZE(smbios_type3_filter_params)},
> > >>>>> +     {SMBIOS_PROCESSOR_INFORMATION, smbios_type4_filter_params,
> > >>>>> +      ARRAY_SIZE(smbios_type4_filter_params)},
> > >>>>> +};
> > >>>>> +
> > >>>>> +static void clear_smbios_table(struct smbios_header *header,
> > >>>>> +                            struct smbios_filter_param *filter,
> > >>>>> +                            u32 count)
> > >>>>> +{
> > >>>>> +     u32 i;
> > >>>>> +     char *str;
> > >>>>> +     u8 string_id;
> > >>>>> +
> > >>>>> +     for (i = 0; i < count; i++) {
> > >>>>> +             if (filter[i].is_string) {
> > >>>>> +                     string_id = *((u8 *)header + filter[i].offset);
> > >>>>> +                     if (string_id == 0) /* string is empty */
> > >>>>> +                             continue;
> > >>>>> +
> > >>>>> +                     str = smbios_string(header, string_id);
> > >>>>> +                     if (!str)
> > >>>>> +                             continue;
> > >>>>> +
> > >>>>> +                     /* string is cleared to space, keep '\0' terminator */
> > >>>>> +                     memset(str, ' ', strlen(str));
> > >>>>> +
> > >>>>> +             } else {
> > >>>>> +                     memset((void *)((u8 *)header + filter[i].offset),
> > >>>>> +                            0, filter[i].size);
> > >>>>> +             }
> > >>>>> +     }
> > >>>>> +}
> > >>>>> +
> > >>>>> +void smbios_prepare_measurement(const struct smbios_entry *entry,
> > >>>>> +                             struct smbios_header *smbios_copy)
> > >>>>> +{
> > >>>>> +     u32 i, j;
> > >>>>> +     struct smbios_header *header;
> > >>>>> +
> > >>>>> +     for (i = 0; i < ARRAY_SIZE(smbios_filter_tables); i++) {
> > >>>>> +             header = smbios_copy;
> > >>>>> +             for (j = 0; j < entry->struct_count; j++) {
> > >>>>> +                     if (header->type == smbios_filter_tables[i].type)
> > >>>>> +                             break;
> > >>>>> +
> > >>>>> +                     header = get_next_header(header);
> > >>>>> +             }
> > >>>>> +             if (j >= entry->struct_count)
> > >>>>> +                     continue;
> > >>>>> +
> > >>>>> +             clear_smbios_table(header,
> > >>>>> +                                smbios_filter_tables[i].params,
> > >>>>> +                                smbios_filter_tables[i].count);
> > >>>>> +     }
> > >>>>> +}
> > >>>>>
> > >>>>


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