[PATCH V3 3/4] tpm: Append the final event log to the TPM event log

[Matthew Garrett <matthewgarrett@google.com>]

From: Matthew Garrett <mjg59@google.com>

Any events that are logged after GetEventsLog() is called are logged to
the EFI Final Events table. These events are defined as being in the
crypto agile log format, so we can just append them directly to the
existing log if it's in the same format. In theory we can also construct
old-style SHA1 log entries for devices that only return logs in that
format, but EDK2 doesn't generate the final event log in that case so
it doesn't seem worth it at the moment.

Signed-off-by: Matthew Garrett <mjg59@google.com>
---
 drivers/char/tpm/eventlog/efi.c | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/eventlog/efi.c b/drivers/char/tpm/eventlog/efi.c
index 3e673ab22cb4..80e9ec28a9be 100644
--- a/drivers/char/tpm/eventlog/efi.c
+++ b/drivers/char/tpm/eventlog/efi.c
@@ -21,10 +21,12 @@
 int tpm_read_log_efi(struct tpm_chip *chip)
 {
 
+	struct efi_tcg2_final_events_table *final_tbl = NULL;
 	struct linux_efi_tpm_eventlog *log_tbl;
 	struct tpm_bios_log *log;
 	u32 log_size;
 	u8 tpm_log_version;
+	void *tmp;
 
 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 		return -ENODEV;
@@ -55,12 +57,41 @@ int tpm_read_log_efi(struct tpm_chip *chip)
 	if (!log->bios_event_log)
 		goto err_memunmap;
 	log->bios_event_log_end = log->bios_event_log + log_size;
-
 	tpm_log_version = log_tbl->version;
+
+	if (efi.tpm_final_log != EFI_INVALID_TABLE_ADDR &&
+	    efi_tpm_final_log_size != 0) {
+		if (tpm_log_version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
+			final_tbl = memremap(efi.tpm_final_log,
+				   sizeof(*final_tbl) + efi_tpm_final_log_size,
+				   MEMREMAP_WB);
+			if (!final_tbl) {
+				pr_err("Could not map UEFI TPM final log\n");
+				kfree(log->bios_event_log);
+				goto err_memunmap;
+			}
+
+			tmp = krealloc(log->bios_event_log,
+				       log_size + efi_tpm_final_log_size,
+				       GFP_KERNEL);
+			if (!tmp) {
+				kfree(log->bios_event_log);
+				goto err_memunmap;
+			}
+
+			log->bios_event_log = tmp;
+			memcpy((void *)log->bios_event_log + log_size,
+			       final_tbl->events, efi_tpm_final_log_size);
+			log->bios_event_log_end = log->bios_event_log +
+				log_size + efi_tpm_final_log_size;
+		}
+	}
+	memunmap(final_tbl);
 	memunmap(log_tbl);
 	return tpm_log_version;
 
 err_memunmap:
+	memunmap(final_tbl);
 	memunmap(log_tbl);
 	return -ENOMEM;
 }
-- 
2.20.1.791.gb4d0f1c61a-goog