diff options
Diffstat (limited to 'include/linux/tpm_eventlog.h')
| -rw-r--r-- | include/linux/tpm_eventlog.h | 152 |
1 files changed, 152 insertions, 0 deletions
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 |