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efi/libstub: Use TPM event typedefs from the TCG PC Client spec

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Our efi_tcg2_tagged_event is not defined in the EFI spec, but it is not
a local invention either: it was taken from the TCG PC Client spec,
where it is called TCG_PCClientTaggedEvent.

Note that this spec also contains some guidance on how to populate it,
which is not being followed closely at the moment; it claims that the
event size should cover the TCG_PCClientTaggedEvent and its payload
only, but it currently covers the preceding efi_tcg2_event too.

However, this directly contradicts the TCG EFI protocol specification,
which states very clearly that the event size should cover the entire
data structure, including the leading efi_tcg2_event_t struct.

So rename the struct and document its provenance, but retain the
existing logic to populate the size field.

Link: https://lore.kernel.org/all/20240308085754.476197-8-ardb+git@google.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel
2024-03-08 09:17:07 +01:00
parent 841c351693
commit 3e0b0f880e
2 changed files with 17 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/firmware/efi/libstub/efi-stub-helper.c
+11 -9
View File
@@ -11,6 +11,7 @@
#include <linux/efi.h>
#include <linux/kernel.h>
#include <linux/overflow.h>
#include <asm/efi.h>
#include <asm/setup.h>
@@ -219,23 +220,24 @@ static const struct {
},
};
struct efistub_measured_event {
efi_tcg2_event_t event_data;
TCG_PCClientTaggedEvent tagged_event __packed;
};
static efi_status_t efi_measure_tagged_event(unsigned long load_addr,
unsigned long load_size,
enum efistub_event event)
{
struct efistub_measured_event *evt;
int size = struct_size(evt, tagged_event.tagged_event_data,
events[event].event_data_len);
efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
efi_tcg2_protocol_t *tcg2 = NULL;
efi_status_t status;
efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2);
if (tcg2) {
struct efi_measured_event {
efi_tcg2_event_t event_data;
efi_tcg2_tagged_event_t tagged_event;
u8 tagged_event_data[];
} *evt;
int size = sizeof(*evt) + events[event].event_data_len;
status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
(void **)&evt);
if (status != EFI_SUCCESS)
@@ -249,12 +251,12 @@ static efi_status_t efi_measure_tagged_event(unsigned long load_addr,
.event_header.event_type = EV_EVENT_TAG,
};
evt->tagged_event = (struct efi_tcg2_tagged_event){
evt->tagged_event = (TCG_PCClientTaggedEvent){
.tagged_event_id = events[event].event_id,
.tagged_event_data_size = events[event].event_data_len,
};
memcpy(evt->tagged_event_data, events[event].event_data,
memcpy(evt->tagged_event.tagged_event_data, events[event].event_data,
events[event].event_data_len);
status = efi_call_proto(tcg2, hash_log_extend_event, 0,
drivers/firmware/efi/libstub/efistub.h
+6 -6
View File
@@ -843,14 +843,14 @@ struct efi_tcg2_event {
/* u8[] event follows here */
} __packed;
struct efi_tcg2_tagged_event {
u32 tagged_event_id;
u32 tagged_event_data_size;
/* u8 tagged event data follows here */
} __packed;
/* from TCG PC Client Platform Firmware Profile Specification */
typedef struct tdTCG_PCClientTaggedEvent {
u32 tagged_event_id;
u32 tagged_event_data_size;
u8 tagged_event_data[];
} TCG_PCClientTaggedEvent;
typedef struct efi_tcg2_event efi_tcg2_event_t;
typedef struct efi_tcg2_tagged_event efi_tcg2_tagged_event_t;
typedef union efi_tcg2_protocol efi_tcg2_protocol_t;
union efi_tcg2_protocol {