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Add Eventlog as evidence to CWT certificate.
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Change-Id: I58540762720e643318e208e0723b68651e928291
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@souravdasgupta
souravdasgupta committed May 31, 2024
1 parent d43dc4d commit bcb942f
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Showing 3 changed files with 77 additions and 52 deletions.
2 changes: 2 additions & 0 deletions oak_dice/src/cert.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,8 @@ pub const LAYER_3_CODE_MEASUREMENT_ID: i64 = -4670569;
pub const FINAL_LAYER_CONFIG_MEASUREMENT_ID: i64 = -4670570;
/// The CWT private claim ID for SHA2_256 digests.
pub const SHA2_256_ID: i64 = -4670572;
/// The CWT private claim ID of the Event.
pub const EVENT_ID: i64 = -4670573;

/// String to be used as salt for generating Key IDs.
const ID_SALT: &[u8] = b"DICE_ID_SALT";
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12 changes: 12 additions & 0 deletions stage0/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -319,13 +319,24 @@ pub fn rust64_start(encrypted: u64) -> ! {
};

let event_log_proto = generate_event_log(stage0event);
let event_type_url_str = event_log_proto.events[0].event.as_ref().unwrap().type_url.as_str();
let eventlog_sha2_256_digest = measure_byte_slice(
format!(
"{}{}{:?}",
event_type_url_str.len(),
event_type_url_str,
event_log_proto.events[0].event.as_ref().unwrap().value.as_bytes()
)
.as_bytes(),
);

log::debug!("Kernel image digest: sha2-256:{}", hex::encode(kernel_info.measurement));
log::debug!("Kernel setup data digest: sha2-256:{}", hex::encode(setup_data_sha2_256_digest));
log::debug!("Kernel command-line: {}", cmdline);
log::debug!("Initial RAM disk digest: sha2-256:{}", hex::encode(ram_disk_sha2_256_digest));
log::debug!("ACPI table generation digest: sha2-256:{}", hex::encode(acpi_sha2_256_digest));
log::debug!("E820 table digest: sha2-256:{}", hex::encode(memory_map_sha2_256_digest));
log::debug!("Event Log digest: sha2-256:{}", hex::encode(eventlog_sha2_256_digest));

// TODO: b/331252282 - Remove temporary workaround for cmd line length.
let cmdline_max_len = 256;
Expand All @@ -341,6 +352,7 @@ pub fn rust64_start(encrypted: u64) -> ! {
ram_disk_sha2_256_digest,
setup_data_sha2_256_digest,
memory_map_sha2_256_digest,
eventlog_sha2_256_digest,
};

let tee_platform = if sev_status().contains(SevStatus::SNP_ACTIVE) {
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115 changes: 63 additions & 52 deletions stage0_dice/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ use hkdf::Hkdf;
use oak_dice::{
cert::{
derive_verifying_key_id, generate_ecdsa_key_pair, generate_signing_certificate,
verifying_key_to_cose_key, ACPI_MEASUREMENT_ID, INITRD_MEASUREMENT_ID,
verifying_key_to_cose_key, ACPI_MEASUREMENT_ID, EVENT_ID, INITRD_MEASUREMENT_ID,
KERNEL_COMMANDLINE_ID, KERNEL_COMMANDLINE_MEASUREMENT_ID, KERNEL_LAYER_ID,
KERNEL_MEASUREMENT_ID, MEMORY_MAP_MEASUREMENT_ID, SETUP_DATA_MEASUREMENT_ID, SHA2_256_ID,
},
Expand Down Expand Up @@ -62,6 +62,8 @@ pub struct Measurements {
/// The concatenated measurement of the command used for building the ACPI
/// tables.
pub acpi_sha2_256_digest: [u8; 32],
/// Eventlog measurement containing the hashes of other components
pub eventlog_sha2_256_digest: [u8; 32],
}

/// Generates an ECA certificate for use by the next boot stage (Stage 1).
Expand All @@ -72,57 +74,66 @@ fn generate_stage1_certificate(
) -> (CoseSign1, SigningKey) {
// Generate additional claims to cover the measurements.

let additional_claims = vec![(
ClaimName::PrivateUse(KERNEL_LAYER_ID),
Value::Map(vec![
(
Value::Integer(KERNEL_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.kernel_sha2_256_digest.into()),
)]),
),
(
Value::Integer(KERNEL_COMMANDLINE_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.cmdline_sha2_256_digest.into()),
)]),
),
(
Value::Integer(KERNEL_COMMANDLINE_ID.into()),
Value::Text(measurements.cmdline.clone()),
),
(
Value::Integer(SETUP_DATA_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.setup_data_sha2_256_digest.into()),
)]),
),
(
Value::Integer(INITRD_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.ram_disk_sha2_256_digest.into()),
)]),
),
(
Value::Integer(MEMORY_MAP_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.memory_map_sha2_256_digest.into()),
)]),
),
(
Value::Integer(ACPI_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.acpi_sha2_256_digest.into()),
)]),
),
]),
)];
let additional_claims = vec![
(
ClaimName::PrivateUse(KERNEL_LAYER_ID),
Value::Map(vec![
(
Value::Integer(KERNEL_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.kernel_sha2_256_digest.into()),
)]),
),
(
Value::Integer(KERNEL_COMMANDLINE_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.cmdline_sha2_256_digest.into()),
)]),
),
(
Value::Integer(KERNEL_COMMANDLINE_ID.into()),
Value::Text(measurements.cmdline.clone()),
),
(
Value::Integer(SETUP_DATA_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.setup_data_sha2_256_digest.into()),
)]),
),
(
Value::Integer(INITRD_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.ram_disk_sha2_256_digest.into()),
)]),
),
(
Value::Integer(MEMORY_MAP_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.memory_map_sha2_256_digest.into()),
)]),
),
(
Value::Integer(ACPI_MEASUREMENT_ID.into()),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.acpi_sha2_256_digest.into()),
)]),
),
]),
),
(
ClaimName::PrivateUse(EVENT_ID),
Value::Map(alloc::vec![(
Value::Integer(SHA2_256_ID.into()),
Value::Bytes(measurements.eventlog_sha2_256_digest.into()),
)]),
),
];

let (signing_key, verifying_key) = generate_ecdsa_key_pair();
(
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