[PATCH v3 1/3] efi_loader: add SMBIOS table measurement
Masahisa Kojima
masahisa.kojima at linaro.org
Thu Oct 21 14:52:03 CEST 2021
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.
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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