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"

2 files changed, 162 insertions, 0 deletions

diff --git a/include/linux/efi.h b/include/linux/efi.h
index 6ebc2098cfe1..f87fabea4a85 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -689,6 +689,7 @@ void efi_native_runtime_setup(void);
 #define LINUX_EFI_LOADER_ENTRY_GUID		EFI_GUID(0x4a67b082, 0x0a4c, 0x41cf,  0xb6, 0xc7, 0x44, 0x0b, 0x29, 0xbb, 0x8c, 0x4f)
 #define LINUX_EFI_RANDOM_SEED_TABLE_GUID	EFI_GUID(0x1ce1e5bc, 0x7ceb, 0x42f2,  0x81, 0xe5, 0x8a, 0xad, 0xf1, 0x80, 0xf5, 0x7b)
 #define LINUX_EFI_TPM_EVENT_LOG_GUID		EFI_GUID(0xb7799cb0, 0xeca2, 0x4943,  0x96, 0x67, 0x1f, 0xae, 0x07, 0xb7, 0x47, 0xfa)
+#define LINUX_EFI_TPM_FINAL_LOG_GUID		EFI_GUID(0x1e2ed096, 0x30e2, 0x4254,  0xbd, 0x89, 0x86, 0x3b, 0xbe, 0xf8, 0x23, 0x25)
 #define LINUX_EFI_MEMRESERVE_TABLE_GUID		EFI_GUID(0x888eb0c6, 0x8ede, 0x4ff5,  0xa8, 0xf0, 0x9a, 0xee, 0x5c, 0xb9, 0x77, 0xc2)
 
 typedef struct {
@@ -996,6 +997,7 @@ extern struct efi {
 	unsigned long mem_attr_table;	/* memory attributes table */
 	unsigned long rng_seed;		/* UEFI firmware random seed */
 	unsigned long tpm_log;		/* TPM2 Event Log table */
+	unsigned long tpm_final_log;	/* TPM2 Final Events Log table */
 	unsigned long mem_reserve;	/* Linux EFI memreserve table */
 	efi_get_time_t *get_time;
 	efi_set_time_t *set_time;
@@ -1706,12 +1708,20 @@ struct linux_efi_random_seed {
 
 struct linux_efi_tpm_eventlog {
 	u32	size;
+	u32	final_events_preboot_size;
 	u8	version;
 	u8	log[];
 };
 
 extern int efi_tpm_eventlog_init(void);
 
+struct efi_tcg2_final_events_table {
+	u64 version;
+	u64 nr_events;
+	u8 events[];
+};
+extern int efi_tpm_final_log_size;
+
 /*
  * efi_runtime_service() function identifiers.
  * "NONE" is used by efi_recover_from_page_fault() to check if the page
diff --git a/include/linux/tpm_eventlog.h b/include/linux/tpm_eventlog.h
index 81519f163211..63238c84dc0b 100644
--- a/include/linux/tpm_eventlog.h
+++ b/include/linux/tpm_eventlog.h
@@ -112,4 +112,156 @@ struct tcg_pcr_event2_head {
 	struct tpm_digest digests[];
 } __packed;
 
+struct tcg_algorithm_size {
+	u16 algorithm_id;
+	u16 algorithm_size;
+};
+
+struct tcg_algorithm_info {
+	u8 signature[16];
+	u32 platform_class;
+	u8 spec_version_minor;
+	u8 spec_version_major;
+	u8 spec_errata;
+	u8 uintn_size;
+	u32 number_of_algorithms;
+	struct tcg_algorithm_size digest_sizes[];
+};
+
+#ifndef TPM_MEMREMAP
+#define TPM_MEMREMAP(start, size) NULL
+#endif
+
+#ifndef TPM_MEMUNMAP
+#define TPM_MEMUNMAP(start, size) do{} while(0)
+#endif
+
+/**
+ * __calc_tpm2_event_size - calculate the size of a TPM2 event log entry
+ * @event:        Pointer to the event whose size should be calculated
+ * @event_header: Pointer to the initial event containing the digest lengths
+ * @do_mapping:   Whether or not the event needs to be mapped
+ *
+ * The TPM2 event log format can contain multiple digests corresponding to
+ * separate PCR banks, and also contains a variable length of the data that
+ * was measured. This requires knowledge of how long each digest type is,
+ * and this information is contained within the first event in the log.
+ *
+ * We calculate the length by examining the number of events, and then looking
+ * at each event in turn to determine how much space is used for events in
+ * total. Once we've done this we know the offset of the data length field,
+ * and can calculate the total size of the event.
+ *
+ * Return: size of the event on success, <0 on failure
+ */
+
+static inline int __calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
+					 struct tcg_pcr_event *event_header,
+					 bool do_mapping)
+{
+	struct tcg_efi_specid_event_head *efispecid;
+	struct tcg_event_field *event_field;
+	void *mapping = NULL;
+	int mapping_size;
+	void *marker;
+	void *marker_start;
+	u32 halg_size;
+	size_t size;
+	u16 halg;
+	int i;
+	int j;
+
+	marker = event;
+	marker_start = marker;
+	marker = marker + sizeof(event->pcr_idx) + sizeof(event->event_type)
+		+ sizeof(event->count);
+
+	/* Map the event header */
+	if (do_mapping) {
+		mapping_size = marker - marker_start;
+		mapping = TPM_MEMREMAP((unsigned long)marker_start,
+				       mapping_size);
+		if (!mapping) {
+			size = 0;
+			goto out;
+		}
+	} else {
+		mapping = marker_start;
+	}
+
+	event = (struct tcg_pcr_event2_head *)mapping;
+
+	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;
+
+	/* Check if event is malformed. */
+	if (event->count > efispecid->num_algs) {
+		size = 0;
+		goto out;
+	}
+
+	for (i = 0; i < event->count; i++) {
+		halg_size = sizeof(event->digests[i].alg_id);
+
+		/* Map the digest's algorithm identifier */
+		if (do_mapping) {
+			TPM_MEMUNMAP(mapping, mapping_size);
+			mapping_size = halg_size;
+			mapping = TPM_MEMREMAP((unsigned long)marker,
+					     mapping_size);
+			if (!mapping) {
+				size = 0;
+				goto out;
+			}
+		} else {
+			mapping = marker;
+		}
+
+		memcpy(&halg, mapping, halg_size);
+		marker = marker + halg_size;
+
+		for (j = 0; j < efispecid->num_algs; j++) {
+			if (halg == efispecid->digest_sizes[j].alg_id) {
+				marker +=
+					efispecid->digest_sizes[j].digest_size;
+				break;
+			}
+		}
+		/* Algorithm without known length. Such event is unparseable. */
+		if (j == efispecid->num_algs) {
+			size = 0;
+			goto out;
+		}
+	}
+
+	/*
+	 * Map the event size - we don't read from the event itself, so
+	 * we don't need to map it
+	 */
+	if (do_mapping) {
+		TPM_MEMUNMAP(mapping, mapping_size);
+		mapping_size += sizeof(event_field->event_size);
+		mapping = TPM_MEMREMAP((unsigned long)marker,
+				       mapping_size);
+		if (!mapping) {
+			size = 0;
+			goto out;
+		}
+	} else {
+		mapping = marker;
+	}
+
+	event_field = (struct tcg_event_field *)mapping;
+
+	marker = marker + sizeof(event_field->event_size)
+		+ event_field->event_size;
+	size = marker - marker_start;
+
+	if ((event->event_type == 0) && (event_field->event_size == 0))
+		size = 0;
+out:
+	if (do_mapping)
+		TPM_MEMUNMAP(mapping, mapping_size);
+	return size;
+}
+
 #endif