tpmdd updates for Linux v5.3

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Merge tag 'tpmdd-next-20190625' of git://git.infradead.org/users/jjs/linux-tpmdd

Pull tpm updates from Jarkko Sakkinen:
 "This contains two critical bug fixes and support for obtaining TPM
  events triggered by ExitBootServices().

  For the latter I have to give a quite verbose explanation not least
  because I had to revisit all the details myself to remember what was
  going on in Matthew's patches.

  The preboot software stack maintains an event log that gets entries
  every time something gets hashed to any of the PCR registers. What
  gets hashed could be a component to be run or perhaps log of some
  actions taken just to give couple of coarse examples. In general,
  anything relevant for the boot process that the preboot software does
  gets hashed and a log entry with a specific event type [1].

  The main application for this is remote attestation and the reason why
  it is useful is nicely put in the very first section of [1]:

     "Attestation is used to provide information about the platform’s
      state to a challenger. However, PCR contents are difficult to
      interpret; therefore, attestation is typically more useful when
      the PCR contents are accompanied by a measurement log. While not
      trusted on their own, the measurement log contains a richer set of
      information than do the PCR contents. The PCR contents are used to
      provide the validation of the measurement log."

  Because EFI_TCG2_PROTOCOL.GetEventLog() is not available after calling
  ExitBootServices(), Linux EFI stub copies the event log to a custom
  configuration table. Unfortunately, ExitBootServices() also generates
  events and obviously these events do not get copied to that table.
  Luckily firmware does this for us by providing a configuration table
  identified by EFI_TCG2_FINAL_EVENTS_TABLE_GUID.

  This essentially contains necessary changes to provide the full event
  log for the use the user space that is concatenated from these two
  partial event logs [2]"

[1] https://trustedcomputinggroup.org/resource/pc-client-specific-platform-firmware-profile-specification/
[2] The final concatenation is done in drivers/char/tpm/eventlog/efi.c

* tag 'tpmdd-next-20190625' of git://git.infradead.org/users/jjs/linux-tpmdd:
  tpm: Don't duplicate events from the final event log in the TCG2 log
  Abstract out support for locating an EFI config table
  tpm: Fix TPM 1.2 Shutdown sequence to prevent future TPM operations
  efi: Attempt to get the TCG2 event log in the boot stub
  tpm: Append the final event log to the TPM event log
  tpm: Reserve the TPM final events table
  tpm: Abstract crypto agile event size calculations
  tpm: Actually fail on TPM errors during "get random"

drivers/firmware/efi/efi.c

@@ -52,6 +52,7 @@ struct efi __read_mostly efi = {
 	.mem_attr_table		= EFI_INVALID_TABLE_ADDR,
 	.rng_seed		= EFI_INVALID_TABLE_ADDR,
 	.tpm_log		= EFI_INVALID_TABLE_ADDR,
+	.tpm_final_log		= EFI_INVALID_TABLE_ADDR,
 	.mem_reserve		= EFI_INVALID_TABLE_ADDR,
 };
 EXPORT_SYMBOL(efi);
@@ -484,6 +485,7 @@ static __initdata efi_config_table_type_t common_tables[] = {
 	{EFI_MEMORY_ATTRIBUTES_TABLE_GUID, "MEMATTR", &efi.mem_attr_table},
 	{LINUX_EFI_RANDOM_SEED_TABLE_GUID, "RNG", &efi.rng_seed},
 	{LINUX_EFI_TPM_EVENT_LOG_GUID, "TPMEventLog", &efi.tpm_log},
+	{LINUX_EFI_TPM_FINAL_LOG_GUID, "TPMFinalLog", &efi.tpm_final_log},
 	{LINUX_EFI_MEMRESERVE_TABLE_GUID, "MEMRESERVE", &efi.mem_reserve},
 	{NULL_GUID, NULL, NULL},
 };

drivers/firmware/efi/libstub/efi-stub-helper.c

@@ -926,3 +926,18 @@ free_map:
 fail:
 	return status;
 }
+
+void *get_efi_config_table(efi_system_table_t *sys_table, efi_guid_t guid)
+{
+	efi_config_table_t *tables = (efi_config_table_t *)sys_table->tables;
+	int i;
+
+	for (i = 0; i < sys_table->nr_tables; i++) {
+		if (efi_guidcmp(tables[i].guid, guid) != 0)
+			continue;
+
+		return (void *)tables[i].table;
+	}
+
+	return NULL;
+}

drivers/firmware/efi/libstub/efistub.h

@@ -65,6 +65,8 @@ efi_status_t check_platform_features(efi_system_table_t *sys_table_arg);
 
 efi_status_t efi_random_get_seed(efi_system_table_t *sys_table_arg);
 
+void *get_efi_config_table(efi_system_table_t *sys_table, efi_guid_t guid);
+
 /* Helper macros for the usual case of using simple C variables: */
 #ifndef fdt_setprop_inplace_var
 #define fdt_setprop_inplace_var(fdt, node_offset, name, var) \

drivers/firmware/efi/libstub/fdt.c

@@ -363,26 +363,17 @@ fail:
 
 void *get_fdt(efi_system_table_t *sys_table, unsigned long *fdt_size)
 {
-	efi_guid_t fdt_guid = DEVICE_TREE_GUID;
-	efi_config_table_t *tables;
-	int i;
+	void *fdt;
 
-	tables = (efi_config_table_t *)sys_table->tables;
+	fdt = get_efi_config_table(sys_table, DEVICE_TREE_GUID);
 
-	for (i = 0; i < sys_table->nr_tables; i++) {
-		void *fdt;
+	if (!fdt)
+		return NULL;
 
-		if (efi_guidcmp(tables[i].guid, fdt_guid) != 0)
-			continue;
-
-		fdt = (void *)tables[i].table;
-		if (fdt_check_header(fdt) != 0) {
-			pr_efi_err(sys_table, "Invalid header detected on UEFI supplied FDT, ignoring ...\n");
-			return NULL;
-		}
-		*fdt_size = fdt_totalsize(fdt);
-		return fdt;
+	if (fdt_check_header(fdt) != 0) {
+		pr_efi_err(sys_table, "Invalid header detected on UEFI supplied FDT, ignoring ...\n");
+		return NULL;
 	}
-
-	return NULL;
+	*fdt_size = fdt_totalsize(fdt);
+	return fdt;
 }

drivers/firmware/efi/libstub/tpm.c

@@ -57,31 +57,40 @@ 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;
 	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;
 	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;
+	int final_events_size = 0;
 
 	status = efi_call_early(locate_protocol, &tcg2_guid, NULL,
 				&tcg2_protocol);
 	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 +105,23 @@ 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;
 	}
 
@@ -112,9 +136,37 @@ static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg)
 		return;
 	}
 
+	/*
+	 * Figure out whether any events have already been logged to the
+	 * final events structure, and if so how much space they take up
+	 */
+	final_events_table = get_efi_config_table(sys_table_arg,
+						LINUX_EFI_TPM_FINAL_LOG_GUID);
+	if (final_events_table && final_events_table->nr_events) {
+		struct tcg_pcr_event2_head *header;
+		int offset;
+		void *data;
+		int event_size;
+		int i = final_events_table->nr_events;
+
+		data = (void *)final_events_table;
+		offset = sizeof(final_events_table->version) +
+			sizeof(final_events_table->nr_events);
+
+		while (i > 0) {
+			header = data + offset + final_events_size;
+			event_size = __calc_tpm2_event_size(header,
+						   (void *)(long)log_location,
+						   false);
+			final_events_size += event_size;
+			i--;
+		}
+	}
+
 	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->final_events_preboot_size = final_events_size;
+	log_tbl->version = version;
 	memcpy(log_tbl->log, (void *) first_entry_addr, log_size);
 
 	status = efi_call_early(install_configuration_table,
@@ -126,9 +178,3 @@ 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);
-}

drivers/firmware/efi/tpm.c

@@ -4,11 +4,34 @@
  *     Thiebaud Weksteen <tweek@google.com>
  */
 
+#define TPM_MEMREMAP(start, size) early_memremap(start, size)
+#define TPM_MEMUNMAP(start, size) early_memunmap(start, size)
+
+#include <asm/early_ioremap.h>
 #include <linux/efi.h>
 #include <linux/init.h>
 #include <linux/memblock.h>
+#include <linux/tpm_eventlog.h>
 
-#include <asm/early_ioremap.h>
+int efi_tpm_final_log_size;
+EXPORT_SYMBOL(efi_tpm_final_log_size);
+
+static int tpm2_calc_event_log_size(void *data, int count, void *size_info)
+{
+	struct tcg_pcr_event2_head *header;
+	int event_size, size = 0;
+
+	while (count > 0) {
+		header = data + size;
+		event_size = __calc_tpm2_event_size(header, size_info, true);
+		if (event_size == 0)
+			return -1;
+		size += event_size;
+		count--;
+	}
+
+	return size;
+}
 
 /*
  * Reserve the memory associated with the TPM Event Log configuration table.
@@ -16,22 +39,54 @@
 int __init efi_tpm_eventlog_init(void)
 {
 	struct linux_efi_tpm_eventlog *log_tbl;
+	struct efi_tcg2_final_events_table *final_tbl;
 	unsigned int tbl_size;
+	int ret = 0;
 
-	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
+	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR) {
+		/*
+		 * We can't calculate the size of the final events without the
+		 * first entry in the TPM log, so bail here.
+		 */
 		return 0;
+	}
 
 	log_tbl = early_memremap(efi.tpm_log, sizeof(*log_tbl));
 	if (!log_tbl) {
 		pr_err("Failed to map TPM Event Log table @ 0x%lx\n",
-			efi.tpm_log);
+		       efi.tpm_log);
 		efi.tpm_log = EFI_INVALID_TABLE_ADDR;
 		return -ENOMEM;
 	}
 
 	tbl_size = sizeof(*log_tbl) + log_tbl->size;
 	memblock_reserve(efi.tpm_log, tbl_size);
+
+	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR)
+		goto out;
+
+	final_tbl = early_memremap(efi.tpm_final_log, sizeof(*final_tbl));
+
+	if (!final_tbl) {
+		pr_err("Failed to map TPM Final Event Log table @ 0x%lx\n",
+		       efi.tpm_final_log);
+		efi.tpm_final_log = EFI_INVALID_TABLE_ADDR;
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	tbl_size = tpm2_calc_event_log_size((void *)efi.tpm_final_log
+					    + sizeof(final_tbl->version)
+					    + sizeof(final_tbl->nr_events),
+					    final_tbl->nr_events,
+					    log_tbl->log);
+	memblock_reserve((unsigned long)final_tbl,
+			 tbl_size + sizeof(*final_tbl));
+	early_memunmap(final_tbl, sizeof(*final_tbl));
+	efi_tpm_final_log_size = tbl_size;
+
+out:
 	early_memunmap(log_tbl, sizeof(*log_tbl));
-	return 0;
+	return ret;
 }