On Mon, 20 May 2019 at 21:55, Matthew Garrett <matthewgarr...@google.com> wrote:
>
> From: Matthew Garrett <mj...@google.com>
>
> Right now we only attempt to obtain the SHA1-only event log. The
> protocol also supports a crypto agile log format, which contains digests
> for all algorithms in use. Attempt to obtain this first, and fall back
> to obtaining the older format if the system doesn't support it. This is
> lightly complicated by the event sizes being variable (as we don't know
> in advance which algorithms are in use), and the interface giving us
> back a pointer to the start of the final entry rather than a pointer to
> the end of the log - as a result, we need to parse the final entry to
> figure out its length in order to know how much data to copy up to the
> OS.
>
> Signed-off-by: Matthew Garrett <mj...@google.com>
Provided that this gets a tested-by from Bartosz,
Acked-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> ---
> drivers/firmware/efi/libstub/tpm.c | 50 ++++++++++++++++++++----------
> 1 file changed, 33 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/tpm.c
> b/drivers/firmware/efi/libstub/tpm.c
> index 5bd04f75d8d6..6b3b507a54eb 100644
> --- a/drivers/firmware/efi/libstub/tpm.c
> +++ b/drivers/firmware/efi/libstub/tpm.c
> @@ -57,7 +57,7 @@ void efi_enable_reset_attack_mitigation(efi_system_table_t
> *sys_table_arg)
>
> #endif
>
> -static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> +void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg)
> {
> efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
> efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID;
> @@ -67,6 +67,7 @@ static void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> unsigned long first_entry_addr, last_entry_addr;
> size_t log_size, last_entry_size;
> efi_bool_t truncated;
> + int version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
> void *tcg2_protocol = NULL;
>
> status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
> @@ -74,14 +75,20 @@ static void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> if (status != EFI_SUCCESS)
> return;
>
> - status = efi_call_proto(efi_tcg2_protocol, get_event_log,
> tcg2_protocol,
> - EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2,
> - &log_location, &log_last_entry, &truncated);
> - if (status != EFI_SUCCESS)
> - return;
> + status = efi_call_proto(efi_tcg2_protocol, get_event_log,
> + tcg2_protocol, version, &log_location,
> + &log_last_entry, &truncated);
> +
> + if (status != EFI_SUCCESS || !log_location) {
> + version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> + status = efi_call_proto(efi_tcg2_protocol, get_event_log,
> + tcg2_protocol, version, &log_location,
> + &log_last_entry, &truncated);
> + if (status != EFI_SUCCESS || !log_location)
> + return;
> +
> + }
>
> - if (!log_location)
> - return;
> first_entry_addr = (unsigned long) log_location;
>
> /*
> @@ -96,8 +103,23 @@ static void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> * We need to calculate its size to deduce the full size of
> * the logs.
> */
> - last_entry_size = sizeof(struct tcpa_event) +
> - ((struct tcpa_event *) last_entry_addr)->event_size;
> + if (version == EFI_TCG2_EVENT_LOG_FORMAT_TCG_2) {
> + /*
> + * The TCG2 log format has variable length entries,
> + * and the information to decode the hash algorithms
> + * back into a size is contained in the first entry -
> + * pass a pointer to the final entry (to calculate its
> + * size) and the first entry (so we know how long each
> + * digest is)
> + */
> + last_entry_size =
> + __calc_tpm2_event_size((void
> *)last_entry_addr,
> + (void
> *)(long)log_location,
> + false);
> + } else {
> + last_entry_size = sizeof(struct tcpa_event) +
> + ((struct tcpa_event *)
> last_entry_addr)->event_size;
> + }
> log_size = log_last_entry - log_location + last_entry_size;
> }
>
> @@ -114,7 +136,7 @@ static void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
>
> memset(log_tbl, 0, sizeof(*log_tbl) + log_size);
> log_tbl->size = log_size;
> - log_tbl->version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
> + log_tbl->version = version;
> memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
>
> status = efi_call_early(install_configuration_table,
> @@ -126,9 +148,3 @@ static void
> efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
> err_free:
> efi_call_early(free_pool, log_tbl);
> }
> -
> -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);
> -}
> --
> 2.21.0.1020.gf2820cf01a-goog
>
