Commit b4f1874c authored by Loïc Yhuel's avatar Loïc Yhuel Committed by Ard Biesheuvel

tpm: check event log version before reading final events

This fixes the boot issues since 5.3 on several Dell models when the TPM
is enabled. Depending on the exact grub binary, booting the kernel would
freeze early, or just report an error parsing the final events log.

We get an event log in the SHA-1 format, which doesn't have a
tcg_efi_specid_event_head in the first event, and there is a final events
table which doesn't match the crypto agile format.
__calc_tpm2_event_size reads bad "count" and "efispecid->num_algs", and
either fails, or loops long enough for the machine to be appear frozen.

So we now only parse the final events table, which is per the spec always
supposed to be in the crypto agile format, when we got a event log in this
format.

Fixes: c46f3405 ("tpm: Reserve the TPM final events table")
Fixes: 166a2809 ("tpm: Don't duplicate events from the final event log in the TCG2 log")
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1779611Signed-off-by: default avatarLoïc Yhuel <loic.yhuel@gmail.com>
Link: https://lore.kernel.org/r/20200512040113.277768-1-loic.yhuel@gmail.comReviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Reviewed-by: default avatarJerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: default avatarMatthew Garrett <mjg59@google.com>
[ardb: warn when final events table is missing or in the wrong format]
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent e8da08a0
......@@ -54,7 +54,7 @@ void efi_retrieve_tpm2_eventlog(void)
efi_status_t status;
efi_physical_addr_t log_location = 0, log_last_entry = 0;
struct linux_efi_tpm_eventlog *log_tbl = NULL;
struct efi_tcg2_final_events_table *final_events_table;
struct efi_tcg2_final_events_table *final_events_table = NULL;
unsigned long first_entry_addr, last_entry_addr;
size_t log_size, last_entry_size;
efi_bool_t truncated;
......@@ -127,6 +127,7 @@ void efi_retrieve_tpm2_eventlog(void)
* Figure out whether any events have already been logged to the
* final events structure, and if so how much space they take up
*/
if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
final_events_table = get_efi_config_table(LINUX_EFI_TPM_FINAL_LOG_GUID);
if (final_events_table && final_events_table->nr_events) {
struct tcg_pcr_event2_head *header;
......
......@@ -62,8 +62,11 @@ int __init efi_tpm_eventlog_init(void)
tbl_size = sizeof(*log_tbl) + log_tbl->size;
memblock_reserve(efi.tpm_log, tbl_size);
if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR)
if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
log_tbl->version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
pr_warn(FW_BUG "TPM Final Events table missing or invalid\n");
goto out;
}
final_tbl = early_memremap(efi.tpm_final_log, sizeof(*final_tbl));
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment