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Add support for new IntegrityRegisters field
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The latest DICE Attestation Architecture adds support for the
IntegrityRegisters field. Use this for Cumulative measurements instead
of adding a fwid.
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@jhand2
jhand2 committed Jan 24, 2025
1 parent 44a2307 commit 12e2838
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Showing 3 changed files with 89 additions and 36 deletions.
75 changes: 56 additions & 19 deletions dpe/src/x509.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -363,16 +363,21 @@ impl CertWriter<'_> {
supports_recursive: bool,
tagged: bool,
) -> Result<usize, DpeErrorCode> {
let fwid0_size = Self::get_fwid_size(&node.tci_current.0, /*tagged=*/ true)?;
let fwid1_size = if supports_recursive {
Self::get_fwid_size(&node.tci_cumulative.0, /*tagged=*/ true)?
let fwid_size = Self::get_fwid_size(&node.tci_current.0, /*tagged=*/ true)?;
let integrity_registers_size = if supports_recursive {
let fwid_size = Self::get_fwid_size(&node.tci_cumulative.0, /*tagged=*/ true)?;
let fwid_list_size = Self::get_structure_size(fwid_size, /*tagged=*/ true)?;
let integrity_register_size =
Self::get_structure_size(fwid_list_size, /*tagged=*/ true)?;
Self::get_structure_size(integrity_register_size, /*tagged=*/ true)?
} else {
0
};
let fwids_size = Self::get_structure_size(fwid0_size + fwid1_size, /*tagged=*/ true)?;
let fwids_size = Self::get_structure_size(fwid_size, /*tagged=*/ true)?;

let size = fwids_size
+ (2 * Self::get_structure_size(core::mem::size_of::<u32>(), /*tagged=*/ true)?); // vendorInfo and type
+ (2 * Self::get_structure_size(core::mem::size_of::<u32>(), /*tagged=*/ true)?) // vendorInfo and type
+ integrity_registers_size;

Self::get_structure_size(size, tagged)
}
Expand Down Expand Up @@ -1221,21 +1226,11 @@ impl CertWriter<'_> {
// IMPLICIT [6] Constructed
let fwid_size = Self::get_fwid_size(&node.tci_current.0, /*tagged=*/ true)?;
bytes_written += self.encode_byte(Self::CONTEXT_SPECIFIC | Self::CONSTRUCTED | 0x06)?;
if supports_recursive {
bytes_written += self.encode_size_field(fwid_size * 2)?;
} else {
bytes_written += self.encode_size_field(fwid_size)?;
}
bytes_written += self.encode_size_field(fwid_size)?;

// fwid[0] current measurement
bytes_written += self.encode_fwid(&node.tci_current)?;

// fwid[1] journey measurement
// Omit fwid[1] from tcb_info if DPE_PROFILE does not support recursive
if supports_recursive {
bytes_written += self.encode_fwid(&node.tci_cumulative)?;
}

// vendorInfo OCTET STRING
// IMPLICIT[8] Primitive
let vinfo = &node.locality.to_be_bytes();
Expand All @@ -1249,6 +1244,32 @@ impl CertWriter<'_> {
bytes_written += self.encode_size_field(core::mem::size_of::<u32>())?;
bytes_written += self.encode_bytes(node.tci_type.as_bytes())?;

// Omit integrityRegisters from tcb_info if DPE_PROFILE does not support recursive
if supports_recursive {
// integrityRegisters SEQUENCE OF
// IMPLICIT [10] Constructed
let fwid_size = Self::get_fwid_size(&node.tci_cumulative.0, /*tagged=*/ true)?;
let fwid_list_size = Self::get_structure_size(fwid_size, /*tagged=*/ true)?;
let integrity_register_size =
Self::get_structure_size(fwid_list_size, /*tagged=*/ true)?;

bytes_written += self.encode_byte(Self::CONTEXT_SPECIFIC | Self::CONSTRUCTED | 0xa)?;
bytes_written += self.encode_size_field(integrity_register_size)?;

// integrityRegusters[0] SEQUENCE
bytes_written += self.encode_byte(Self::SEQUENCE_TAG)?;
bytes_written += self.encode_size_field(fwid_list_size)?;

// IMPLICIT [2] Constructed
// registerDigests SEQUENCE OF FWID
// cumulative measurement
// Note: registerName and registerNum are omitted because DPE only
// supports a single register.
bytes_written += self.encode_byte(Self::CONTEXT_SPECIFIC | Self::CONSTRUCTED | 0x02)?;
bytes_written += self.encode_size_field(fwid_size)?;
bytes_written += self.encode_fwid(&node.tci_cumulative)?;
}

Ok(bytes_written)
}

Expand Down Expand Up @@ -1582,7 +1603,7 @@ impl CertWriter<'_> {
/// AuthorityKeyIdentifier ::= SEQUENCE {
/// keyIdentifier [0] KeyIdentifier OPTIONAL,
/// authorityCertIssuer [1] GeneralNames OPTIONAL,
/// authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL
/// authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL
/// }
fn encode_authority_key_identifier_extension(
&mut self,
Expand Down Expand Up @@ -2248,6 +2269,16 @@ pub(crate) mod tests {
pub(crate) digest: &'a [u8],
}

#[derive(asn1::Asn1Read)]
pub struct IntegrityRegister<'a> {
#[implicit(0)]
_register_name: Option<asn1::IA5String<'a>>,
#[implicit(1)]
_register_num: Option<u64>,
#[implicit(2)]
pub register_digests: Option<asn1::SequenceOf<'a, Fwid<'a>>>,
}

#[derive(asn1::Asn1Read)]
pub struct TcbInfo<'a> {
#[implicit(0)]
Expand All @@ -2270,6 +2301,8 @@ pub(crate) mod tests {
pub vendor_info: Option<&'a [u8]>,
#[implicit(9)]
pub tci_type: Option<&'a [u8]>,
#[implicit(10)]
pub integrity_registers: Option<asn1::SequenceOf<'a, IntegrityRegister<'a>>>,
}

#[derive(asn1::Asn1Read)]
Expand Down Expand Up @@ -2394,16 +2427,20 @@ pub(crate) mod tests {
// FWIDs
let mut fwid_itr = parsed_tcb_info.fwids.unwrap();
let expected_current = fwid_itr.next().unwrap().digest;
let expected_cumulative = fwid_itr.next().unwrap().digest;
assert_eq!(expected_current, node.tci_current.0);
assert_eq!(expected_cumulative, node.tci_cumulative.0);

assert_eq!(parsed_tcb_info.tci_type.unwrap(), node.tci_type.as_bytes());
assert_eq!(
parsed_tcb_info.vendor_info.unwrap(),
node.locality.to_be_bytes()
);

// Integrity registers
let mut ir_itr = parsed_tcb_info.integrity_registers.unwrap();
let mut fwid_itr = ir_itr.next().unwrap().register_digests.unwrap();
let expected_cumulative = fwid_itr.next().unwrap().digest;
assert_eq!(expected_cumulative, node.tci_cumulative.0);

// test tbs_info with supports_recursive = false
supports_recursive = false;
w = CertWriter::new(&mut cert, true);
Expand Down
36 changes: 26 additions & 10 deletions verification/testing/certifyKey.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ type Fwid struct {
// flags [7] IMPLICIT OperationalFlags OPTIONAL,
// vendorInfo [8] IMPLICIT OCTET STRING OPTIONAL,
// type [9] IMPLICIT OCTET STRING OPTIONAL,
// integrityRegisters [10] IMPLICIT IrList OPTIONAL,
// }
//
// FWIDLIST ::== SEQUENCE SIZE (1..MAX) OF FWID
Expand All @@ -91,17 +92,32 @@ type Fwid struct {
// recovery (2),
// debug (3)
// }
//
// IrList ::= SEQUENCE SIZE (1..MAX) OF IntegrityRegister
// IntegrityRegister ::= SEQUENCE {
// registerName [0] IMPLICIT IA5String OPTIONAL,
// registerNum [1] IMPLICIT INTEGER OPTIONAL,
// registerDigests [2] IMPLICIT FWIDLIST
// }

type DiceTcbInfo struct {
Vendor string `asn1:"optional,tag:0,utf8"`
Model string `asn1:"optional,tag:1,utf8"`
Version string `asn1:"optional,tag:2,utf8"`
SVN int `asn1:"optional,tag:3"`
Layer int `asn1:"optional,tag:4"`
Index int `asn1:"optional,tag:5"`
Fwids []Fwid `asn1:"optional,tag:6"`
Flags OperationalFlag `asn1:"optional,tag:7"`
VendorInfo []byte `asn1:"optional,tag:8"`
Type []byte `asn1:"optional,tag:9"`
Vendor string `asn1:"optional,tag:0,utf8"`
Model string `asn1:"optional,tag:1,utf8"`
Version string `asn1:"optional,tag:2,utf8"`
SVN int `asn1:"optional,tag:3"`
Layer int `asn1:"optional,tag:4"`
Index int `asn1:"optional,tag:5"`
Fwids []Fwid `asn1:"optional,tag:6"`
Flags OperationalFlag `asn1:"optional,tag:7"`
VendorInfo []byte `asn1:"optional,tag:8"`
Type []byte `asn1:"optional,tag:9"`
IntegrityRegisters []IntegrityRegister `asn1:"optional,tag:10"`
}

type IntegrityRegister struct {
RegisterName string `asn1:"optional,tag:0,ia5"`
RegisterNum int `asn1:"optional,tag:1"`
RegisterDigests []Fwid `asn1:"optional,tag:2"`
}

// OperationalFlag represents the TCBInfo Operational Flags field
Expand Down
14 changes: 7 additions & 7 deletions verification/testing/deriveContext.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -356,7 +356,7 @@ func TestDeriveContextRecursive(d client.TestDPEInstance, c client.DPEClient, t
if err != nil {
t.Fatal(err)
}
lastCumulative := tcbInfo.Fwids[1].Digest
lastCumulative := tcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest

// Set current TCI value
_, err = c.DeriveContext(handle,
Expand Down Expand Up @@ -440,12 +440,12 @@ func TestDeriveContextRecursiveOnDerivedContexts(d client.TestDPEInstance, c cli

// Check TCI_CUMULATIVE after creating child context
wantCumulativeTCI := computeExpectedCumulative(make([]byte, digestLen), childTcbInfo.Fwids[0].Digest)
if !bytes.Equal(childTcbInfo.Fwids[1].Digest, wantCumulativeTCI) {
t.Errorf("[ERROR]: Child node's cumulative TCI %x, expected %x", childTcbInfo.Fwids[1].Digest, wantCumulativeTCI)
if !bytes.Equal(childTcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest, wantCumulativeTCI) {
t.Errorf("[ERROR]: Child node's cumulative TCI %x, expected %x", childTcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest, wantCumulativeTCI)
}

// Set current TCI value
lastCumulative := childTcbInfo.Fwids[1].Digest
lastCumulative := childTcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest
resp, err := c.DeriveContext(childHandle,
extendTciValue,
client.DeriveContextFlags(client.Recursive),
Expand All @@ -465,8 +465,8 @@ func TestDeriveContextRecursiveOnDerivedContexts(d client.TestDPEInstance, c cli
}

wantCumulativeTCI = computeExpectedCumulative(lastCumulative, extendTciValue)
if !bytes.Equal(childTcbInfo.Fwids[1].Digest, wantCumulativeTCI) {
t.Errorf("[ERROR]: Child node's cumulative TCI %x, expected %x", childTcbInfo.Fwids[1].Digest, wantCumulativeTCI)
if !bytes.Equal(childTcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest, wantCumulativeTCI) {
t.Errorf("[ERROR]: Child node's cumulative TCI %x, expected %x", childTcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest, wantCumulativeTCI)
}
}

Expand All @@ -491,7 +491,7 @@ func verifyMeasurements(c client.DPEClient, t *testing.T, handle *client.Context

// Check that the last TcbInfo current/cumulative are as expected
current := tcbInfo.Fwids[0].Digest
cumulative := tcbInfo.Fwids[1].Digest
cumulative := tcbInfo.IntegrityRegisters[0].RegisterDigests[0].Digest
if !bytes.Equal(current, expectedCurrent) {
t.Errorf("[ERROR]: Unexpected TCI_CURRENT digest, want %v but got %v", expectedCurrent, current)
}
Expand Down

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