tpm: Abstract crypto agile event size calculations (44038bc5) · Commits · 戴 / test

drivers/char/tpm/eventlog/tpm2.c

+1 −46

Original line number	Original line	Diff line number	Diff line
	@@ -36,52 +36,7 @@
	static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,		static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
	struct tcg_pcr_event *event_header)		struct tcg_pcr_event *event_header)
	{		{
	struct tcg_efi_specid_event_head *efispecid;		return __calc_tpm2_event_size(event, event_header);
	struct tcg_event_field *event_field;
	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);

	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;

	/* Check if event is malformed. */
	if (event->count > efispecid->num_algs)
	return 0;

	for (i = 0; i < event->count; i++) {
	halg_size = sizeof(event->digests[i].alg_id);
	memcpy(&halg, marker, 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)
	return 0;
	}

	event_field = (struct tcg_event_field *)marker;
	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))
	return 0;

	return size;
	}		}

	static void tpm2_bios_measurements_start(struct seq_file m, loff_t *pos)		static void tpm2_bios_measurements_start(struct seq_file m, loff_t *pos)

include/linux/tpm_eventlog.h

+68 −0

Original line number	Original line	Diff line number	Diff line
	@@ -112,4 +112,72 @@ struct tcg_pcr_event2_head {
	struct tpm_digest digests[];		struct tpm_digest digests[];
	} __packed;		} __packed;

			/**
			* __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
			*
			* 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)
			{
			struct tcg_efi_specid_event_head *efispecid;
			struct tcg_event_field *event_field;
			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);

			efispecid = (struct tcg_efi_specid_event_head *)event_header->event;

			/* Check if event is malformed. */
			if (event->count > efispecid->num_algs)
			return 0;

			for (i = 0; i < event->count; i++) {
			halg_size = sizeof(event->digests[i].alg_id);
			memcpy(&halg, marker, 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)
			return 0;
			}

			event_field = (struct tcg_event_field *)marker;
			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))
			return 0;

			return size;
			}
	#endif		#endif

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