Hi Heinrich,
On Fri, 26 Nov 2021 at 13:01, Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 11/26/21 06:00, Ruchika Gupta wrote:
Platforms may have support to measure their initial firmware components and pass the event log to u-boot. The event log address can be passed in property tpm_event_log_addr and tpm_event_log_size of the tpm node. Platforms may choose their own specific mechanism to do so. A weak function is added to check if even log has been passed to u-boot from earlier firmware components. If available, the eventlog is parsed to check for its correctness and further event logs are appended to the passed log.
Signed-off-by: Ruchika Gupta ruchika.gupta@linaro.org Tested-by: Ilias Apalodimas ilias.apalodimas@linaro.org Reviewed-by: Ilias Apalodimas ilias.apalodimas@linaro.org
v6: No change
v5: Shift the efi_init_event_log() to a different location in the file. This help fixes compilation issue introduced by calling
efi_append_scrtm_version()
from it.
v4: Add SCRTM version to log only if previous firmware doesn't pass the
eventlog
v3: Return as soon as you detect error
v2: Moved firmware eventlog code parsing to tcg2_get_fw_eventlog()
lib/efi_loader/efi_tcg2.c | 438 ++++++++++++++++++++++++++++++++------ 1 file changed, 369 insertions(+), 69 deletions(-)
diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c index 8c1f22e337..a789c44660 100644 --- a/lib/efi_loader/efi_tcg2.c +++ b/lib/efi_loader/efi_tcg2.c @@ -324,6 +324,45 @@ __weak efi_status_t platform_get_tpm2_device(struct
udevice **dev)
return EFI_NOT_FOUND;}
+/**
- platform_get_eventlog() - retrieve the eventlog address and size
- This function retrieves the eventlog address and size if the
underlying
- firmware has done some measurements and passed them.
- This function may be overridden based on platform specific method of
- passing the eventlog address and size.
- @dev: udevice
- @addr: eventlog address
- @sz: eventlog size
- Return: status code
- */
+__weak efi_status_t platform_get_eventlog(struct udevice *dev, u64
*addr,
u32 *sz)This function must be declared in a header to be overridden.
+{
const u64 *basep;const u32 *sizep;basep = dev_read_prop(dev, "tpm_event_log_addr", NULL);if (!basep)return EFI_NOT_FOUND;*addr = be64_to_cpup((__force __be64 *)basep);sizep = dev_read_prop(dev, "tpm_event_log_size", NULL);if (!sizep)return EFI_NOT_FOUND;*sz = be32_to_cpup((__force __be32 *)sizep);if (*sz == 0) {log_debug("event log empty\n");return EFI_NOT_FOUND;}return EFI_SUCCESS;+}
- /**
- tpm2_get_max_command_size() - get the supported max command size
@@ -1181,6 +1220,250 @@ static const struct efi_tcg2_protocol
efi_tcg2_protocol = {
.get_result_of_set_active_pcr_banks =efi_tcg2_get_result_of_set_active_pcr_banks,
};
+/**
- parse_event_log_header() - Parse and verify the event log header
fields
- @buffer: Pointer to the event header
- @size: Size of the eventlog
- @pos: Position in buffer after event log header
- Return: status code
- */
+efi_status_t parse_event_log_header(void *buffer, u32 size, u32 *pos)
This function should be declared in a header or be static.
Should buffer have type struct tcg_pcr_event *?
Since buffer points to the complete eventlog, it would be probably better to keep it as it is i.e void *. I will correct the description of this parameter in the function description to avoid confusion.
+{
struct tcg_pcr_event *event_header = (struct tcg_pcr_event*)buffer;
int i = 0;if (size < sizeof(*event_header))return EFI_COMPROMISED_DATA;if (get_unaligned_le32(&event_header->pcr_index) != 0 ||get_unaligned_le32(&event_header->event_type) != EV_NO_ACTION)return EFI_COMPROMISED_DATA;for (i = 0; i < sizeof(event_header->digest); i++) {if (event_header->digest[i] != 0)if (event_header->digest[i])
return EFI_COMPROMISED_DATA;}*pos += sizeof(*event_header);Do you re
Probably you are asking about parameter pos here. pos points to the offset in the buffer where the next event starts (after the event header)
return EFI_SUCCESS;+}
+/**
- parse_specid_event() - Parse and verify the specID Event in the
eventlog
- @dev: udevice
- @buffer: Pointer to the start of the eventlog
- @log_size: Size of the eventlog
- @pos: Offset in the evenlog where specID event starts
- Return: status code
- @pos Offset in the eventlog where the specID
event ends
Duplicate line
- @digest_list: list of digests in the event
Misplaced line
- */
+efi_status_t parse_specid_event(struct udevice *dev, void *buffer, u32
log_size,
u32 *pos,struct tpml_digest_values *digest_list)+{
This function should be declared in a header or be static.
struct tcg_efi_spec_id_event *spec_event;struct tcg_pcr_event *event_header = (struct tcg_pcr_event*)buffer;
size_t spec_event_size;u32 active = 0, supported = 0, pcr_count = 0, alg_count = 0;u32 spec_active = 0;u16 hash_alg, hash_sz;u8 vendor_sz;int err, i;/* Check specID event data */spec_event = (struct tcg_efi_spec_id_event *)((uintptr_t)buffer +*pos);
/* Check for signature */if (memcmp(spec_event->signature,TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03,
sizeof(TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03))) {log_err("specID Event: Signature mismatch\n");return EFI_COMPROMISED_DATA;}if (spec_event->spec_version_minor !=TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MINOR_TPM2 ||spec_event->spec_version_major !=TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MAJOR_TPM2)return EFI_COMPROMISED_DATA;if (spec_event->number_of_algorithms > MAX_HASH_COUNT ||spec_event->number_of_algorithms < 1) {log_err("specID Event: Number of algorithms incorrect\n");return EFI_COMPROMISED_DATA;}alg_count = spec_event->number_of_algorithms;err = tpm2_get_pcr_info(dev, &supported, &active, &pcr_count);if (err)return EFI_DEVICE_ERROR;digest_list->count = 0;/** We may need to worry about the order of algs in this structureas
%s/algs/algorithms/
* subsequent entries in event should be in same order"We need to worry" sounds like a FIXME. Is there anything to fix or do you mean:
We have to take care that the sequence of algorithms that we record in digest_list matches the sequence in the event log.
*/for (i = 0; i < alg_count; i++) {hash_alg =get_unaligned_le16(&spec_event->digest_sizes[i].algorithm_id);
hash_sz =get_unaligned_le16(&spec_event->digest_sizes[i].digest_size);
if (!(supported & alg_to_mask(hash_alg))) {log_err("specID Event: Unsupported algorithm\n");return EFI_COMPROMISED_DATA;}digest_list->digests[digest_list->count++].hash_alg =hash_alg;
spec_active |= alg_to_mask(hash_alg);}/* TCG spec expects the event log to have hashes for all activePCR's */
The TCG specification
if (spec_active != active) {/** Previous stage bootloader should know all the activePCR's
* and use them in the Eventlog.*/log_err("specID Event: All active hash alg not present\n");return EFI_COMPROMISED_DATA;}/** the size of the spec event and placement of vendor_info_size* depends on supported algoriths*/spec_event_size =offsetof(struct tcg_efi_spec_id_event, digest_sizes) +alg_count * sizeof(spec_event->digest_sizes[0]);vendor_sz = *(uint8_t *)((uintptr_t)buffer + *pos +spec_event_size);
spec_event_size += sizeof(vendor_sz) + vendor_sz;*pos += spec_event_size;if (get_unaligned_le32(&event_header->event_size) !=spec_event_size) {
log_err("specID event: header event size mismatch\n");/* Right way to handle this can be to call SetActive PCR's*/
return EFI_COMPROMISED_DATA;}return EFI_SUCCESS;+}
Missing function description
+efi_status_t tcg2_parse_event(struct udevice *dev, void *buffer, u32
log_size,
u32 *offset, struct tpml_digest_values*digest_list,
u32 *pcr)Exported functions should be declared in a header. Or should this function be static?
+{
struct tcg_pcr_event2 *event = NULL;u32 event_type, count, size, event_size;size_t pos;if (*offset > log_size)return EFI_COMPROMISED_DATA;event = (struct tcg_pcr_event2 *)((uintptr_t)buffer + *offset);*pcr = get_unaligned_le32(&event->pcr_index);event_size = tcg_event_final_size(digest_list);if (*offset + event_size > log_size) {log_err("Event exceeds log size\n");return EFI_COMPROMISED_DATA;}event_type = get_unaligned_le32(&event->event_type);/* get the count */count = get_unaligned_le32(&event->digests.count);if (count != digest_list->count)return EFI_COMPROMISED_DATA;pos = offsetof(struct tcg_pcr_event2, digests);pos += offsetof(struct tpml_digest_values, digests);for (int i = 0; i < digest_list->count; i++) {u16 alg;u16 hash_alg = digest_list->digests[i].hash_alg;u8 *digest = (u8 *)&digest_list->digests[i].digest;alg = get_unaligned_le16((void *)((uintptr_t)event + pos));if (alg != hash_alg)return EFI_COMPROMISED_DATA;pos += offsetof(struct tpmt_ha, digest);memcpy(digest, (void *)((uintptr_t)event + pos),alg_to_len(hash_alg));
pos += alg_to_len(hash_alg);}size = get_unaligned_le32((void *)((uintptr_t)event + pos));event_size += size;pos += sizeof(u32); /* tcg_pcr_event2 event_size*/pos += size;/* make sure the calculated buffer is what we checked against */if (pos != event_size)return EFI_COMPROMISED_DATA;if (pos > log_size)return EFI_COMPROMISED_DATA;*offset += pos;return EFI_SUCCESS;+}
Missing function description.
+efi_status_t tcg2_get_fw_eventlog(struct udevice *dev, void *log_buffer,
size_t *log_sz)This function should be declared in a header or should be static.
+{
struct tpml_digest_values digest_list;void *buffer;efi_status_t ret;u32 pcr, pos;u64 base;u32 sz;ret = platform_get_eventlog(dev, &base, &sz);if (ret != EFI_SUCCESS)return ret;if (sz > TPM2_EVENT_LOG_SIZE)return EFI_VOLUME_FULL;buffer = (void *)base;Superfluous conversion.
Sorry, I didn't get this comment. If you meant removing the typecast, base is u64 so when assigning it to a void pointer, cast would be needed.
On removing the case, I get this warning buffer = base; lib/efi_loader/efi_tcg2.c:1518:9: warning: assignment to ‘void *’ from ‘u64’ {aka ‘long long unsigned int’} makes pointer from integer without a cast [-Wint-conversion] 1518 | buffer = base;
[...]
Regards, Ruchika