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Subject[PATCH 4/5] efi/libstub/tpm: Retrieve TPM event log in 2.0 format
Date
From: Bartosz Szczepanek <bsz@semihalf.com>

Currently, the only way to get TPM 2.0 event log from firmware is to use
device tree. Introduce efi_retrieve_tpm2_eventlog_2 function to enable
retrieving it from EFI structures.

Include lib/tpm.c into EFI stub to calculate event sizes using helper
function.

Signed-off-by: Bartosz Szczepanek <bsz@semihalf.com>
---
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/firmware/efi/libstub/tpm.c | 107 +++++++++++++++++++++++++++++++++-
2 files changed, 107 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d9845099635e..0d7d66ad916d 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -38,7 +38,8 @@ OBJECT_FILES_NON_STANDARD := y
# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
KCOV_INSTRUMENT := n

-lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o
+lib-y := efi-stub-helper.o gop.o secureboot.o tpm.o \
+ lib-tpm.o

# include the stub's generic dependencies from lib/ when building for ARM/arm64
arm-deps-y := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c
diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c
index a90b0b8fc69a..c8c2531be413 100644
--- a/drivers/firmware/efi/libstub/tpm.c
+++ b/drivers/firmware/efi/libstub/tpm.c
@@ -129,8 +129,111 @@ static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
efi_call_early(free_pool, log_tbl);
}

+static efi_status_t
+efi_calc_tpm2_eventlog_2_size(efi_system_table_t *sys_table_arg,
+ void *log, void *last_entry, ssize_t *log_size)
+{
+ struct tcg_pcr_event2 *event = last_entry;
+ struct tcg_efi_specid_event *efispecid;
+ struct tcg_pcr_event *log_header = log;
+ ssize_t last_entry_size;
+
+ efispecid = (struct tcg_efi_specid_event *) log_header->event;
+
+ if (last_entry == NULL || log_size == NULL)
+ return EFI_INVALID_PARAMETER;
+
+ if (log == last_entry) {
+ /*
+ * Only one entry (header) in the log.
+ */
+ *log_size = log_header->event_size +
+ sizeof(struct tcg_pcr_event);
+ return EFI_SUCCESS;
+ }
+
+ if (event->count > efispecid->num_algs) {
+ efi_printk(sys_table_arg,
+ "TCG2 event uses more algorithms than defined\n");
+ return EFI_INVALID_PARAMETER;
+ }
+
+ last_entry_size = calc_tpm2_event_size(last_entry, efispecid);
+ if (last_entry_size < 0) {
+ efi_printk(sys_table_arg,
+ "TCG2 log has invalid last entry size\n");
+ return EFI_INVALID_PARAMETER;
+ }
+
+ *log_size = last_entry + last_entry_size - log;
+ return EFI_SUCCESS;
+}
+
+static efi_status_t efi_retrieve_tpm2_eventlog_2(efi_system_table_t *sys_table_arg)
+{
+ efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
+ efi_physical_addr_t log_location = 0, log_last_entry = 0;
+ efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
+ efi_bool_t truncated;
+ efi_status_t status;
+ struct linux_efi_tpm_eventlog *log_tbl = NULL;
+ void *tcg2_protocol = NULL;
+ ssize_t log_size;
+
+ status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
+ &tcg2_protocol);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ status = efi_call_proto(efi_tcg2_protocol, get_event_log, tcg2_protocol,
+ EFI_TCG2_EVENT_LOG_FORMAT_TCG_2,
+ &log_location, &log_last_entry, &truncated);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ if (!log_location)
+ return EFI_NOT_FOUND;
+
+ status = efi_calc_tpm2_eventlog_2_size(sys_table_arg,
+ (void *)log_location,
+ (void *) log_last_entry,
+ &log_size);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ /* Allocate space for the logs and copy them. */
+ status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
+ sizeof(*log_tbl) + log_size,
+ (void **) &log_tbl);
+
+ if (status != EFI_SUCCESS) {
+ efi_printk(sys_table_arg,
+ "Unable to allocate memory for event log\n");
+ return status;
+ }
+
+ memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
+ log_tbl->size = log_size;
+ log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
+ memcpy(log_tbl->log, (void *) log_location, log_size);
+
+ status = efi_call_early(install_configuration_table,
+ &linux_eventlog_guid, log_tbl);
+ if (status != EFI_SUCCESS)
+ goto err_free;
+
+ return EFI_SUCCESS;
+
+err_free:
+ efi_call_early(free_pool, log_tbl);
+ return status;
+}
+
void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
{
- /* Only try to retrieve the logs in 1.2 format. */
- efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
+ efi_status_t status;
+
+ status = efi_retrieve_tpm2_eventlog_2(sys_table_arg);
+ if (status != EFI_SUCCESS)
+ efi_retrieve_tpm2_eventlog_1_2(sys_table_arg);
}
--
2.14.4
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