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Update az snp / tdx vtpm dependency to 0.5 #293

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merged 4 commits into from
Feb 7, 2024
Merged

Update az snp / tdx vtpm dependency to 0.5 #293

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8a31788
AS-verifier: Fix typo in error string
surajssd Jan 25, 2024
27d82d3
AS-Verifier: Update az-cvm-vtpm to 0.5.1
surajssd Jan 23, 2024
c36b036
verifier-az-cvm-vtpm: Fix tests to updated library
surajssd Jan 24, 2024
05039ea
AS-verifier: Add PCR verification to Azure vTPM
surajssd Feb 1, 2024
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473 changes: 182 additions & 291 deletions Cargo.lock
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4 changes: 2 additions & 2 deletions attestation-service/verifier/Cargo.toml
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Expand Up @@ -18,8 +18,8 @@ cca-verifier = [ "ear", "veraison-apiclient" ]
anyhow.workspace = true
asn1-rs = { version = "0.5.1", optional = true }
async-trait.workspace = true
az-snp-vtpm = { version = "0.4.1", default-features = false, features = ["verifier"], optional = true }
az-tdx-vtpm = { version = "0.4.1", default-features = false, features = ["verifier"], optional = true }
az-snp-vtpm = { version = "0.5.1", default-features = false, features = ["verifier"], optional = true }
az-tdx-vtpm = { version = "0.5.1", default-features = false, features = ["verifier"], optional = true }
base64 = "0.21"
bincode = "1.3.3"
byteorder = "1"
Expand Down
107 changes: 74 additions & 33 deletions attestation-service/verifier/src/az_snp_vtpm/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,9 +48,10 @@ impl Verifier for AzSnpVtpm {
/// The following verification steps are performed:
/// 1. TPM Quote has been signed by AK included in the HCL variable data
/// 2. Attestation report_data matches TPM Quote nonce
/// 3. SNP report's report_data field matches hashed HCL variable data
/// 4. SNP Report is genuine
/// 5. SNP Report has been issued in VMPL 0
/// 3. TPM PCRs' digest matches the digest in the Quote
/// 4. SNP report's report_data field matches hashed HCL variable data
/// 5. SNP Report is genuine
/// 6. SNP Report has been issued in VMPL 0
async fn evaluate(
&self,
evidence: &[u8],
Expand All @@ -73,6 +74,8 @@ impl Verifier for AzSnpVtpm {

verify_nonce(&evidence.quote, expected_report_data)?;

verify_pcrs(&evidence.quote)?;

let var_data_hash = hcl_report.var_data_sha256();
let snp_report = hcl_report.try_into()?;
verify_report_data(&var_data_hash, &snp_report)?;
Expand Down Expand Up @@ -106,6 +109,14 @@ fn verify_signature(quote: &Quote, hcl_report: &HclReport) -> Result<()> {
Ok(())
}

fn verify_pcrs(quote: &Quote) -> Result<()> {
quote
.verify_pcrs()
.context("Digest of PCRs does not match digest in Quote")?;
debug!("PCR verification completed successfully");
Ok(())
}

fn verify_report_data(var_data_hash: &[u8; 32], snp_report: &AttestationReport) -> Result<()> {
if *var_data_hash != snp_report.report_data[..32] {
bail!("SNP report report_data mismatch");
Expand Down Expand Up @@ -133,10 +144,10 @@ fn verify_snp_report(
#[cfg(test)]
mod tests {
use super::*;
use az_snp_vtpm::vtpm::VerifyError;

const REPORT: &[u8; 2048] = include_bytes!("../../test_data/az-snp-vtpm/hcl-report.bin");
const SIGNATURE: &[u8; 256] = include_bytes!("../../test_data/az-snp-vtpm/tpm-quote.sig");
const MESSAGE: &[u8; 122] = include_bytes!("../../test_data/az-snp-vtpm/tpm-quote.msg");
const REPORT: &[u8; 2600] = include_bytes!("../../test_data/az-snp-vtpm/hcl-report.bin");
const QUOTE: &[u8; 1362] = include_bytes!("../../test_data/az-snp-vtpm/quote.bin");
const REPORT_DATA: &[u8] = "challenge".as_bytes();

#[test]
Expand All @@ -152,12 +163,17 @@ mod tests {
fn test_verify_snp_report_failure() {
let mut wrong_report = REPORT.clone();
// messing with snp report
wrong_report[0x00b0] = 0;
wrong_report[0x01a6] = 0;
let hcl_report = HclReport::new(wrong_report.to_vec()).unwrap();
let snp_report = hcl_report.try_into().unwrap();
let vcek = Vcek::from_pem(include_str!("../../test_data/az-snp-vtpm/vcek.pem")).unwrap();
let vendor_certs = load_milan_cert_chain().as_ref().unwrap();
verify_snp_report(&snp_report, &vcek, vendor_certs).unwrap_err();
assert_eq!(
verify_snp_report(&snp_report, &vcek, vendor_certs)
.unwrap_err()
.to_string(),
"SNP version mismatch",
);
}

#[test]
Expand All @@ -175,61 +191,86 @@ mod tests {
let hcl_report = HclReport::new(wrong_report.to_vec()).unwrap();
let var_data_hash = hcl_report.var_data_sha256();
let snp_report = hcl_report.try_into().unwrap();
verify_report_data(&var_data_hash, &snp_report).unwrap_err();
assert_eq!(
verify_report_data(&var_data_hash, &snp_report)
.unwrap_err()
.to_string(),
"SNP report report_data mismatch"
);
}

#[test]
fn test_verify_signature() {
let quote = Quote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let hcl_report = HclReport::new(REPORT.to_vec()).unwrap();
verify_signature(&quote, &hcl_report).unwrap();
}

#[test]
fn test_verify_quote_signature_failure() {
let mut wrong_message = MESSAGE.clone();
wrong_message.reverse();
let wrong_quote = Quote {
signature: SIGNATURE.to_vec(),
message: wrong_message.to_vec(),
};
let mut quote = QUOTE.clone();
quote[0x030] = 0;
let wrong_quote: Quote = bincode::deserialize(&quote).unwrap();

let hcl_report = HclReport::new(REPORT.to_vec()).unwrap();
verify_signature(&wrong_quote, &hcl_report).unwrap_err();
assert_eq!(
verify_signature(&wrong_quote, &hcl_report)
.unwrap_err()
.downcast_ref::<VerifyError>()
.unwrap()
.to_string(),
VerifyError::SignatureMismatch.to_string()
);
}

#[test]
fn test_verify_akpub_failure() {
let quote = Quote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let mut wrong_report = REPORT.clone();
// messing with AKpub in var data
wrong_report[0x0540] = 0;
let wrong_hcl_report = HclReport::new(wrong_report.to_vec()).unwrap();
verify_signature(&quote, &wrong_hcl_report).unwrap_err();
assert_eq!(
verify_signature(&quote, &wrong_hcl_report)
.unwrap_err()
.to_string(),
"Failed to get AKpub",
);
}

#[test]
fn test_verify_quote_nonce() {
let quote = Quote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
verify_nonce(&quote, &REPORT_DATA).unwrap();
}

#[test]
fn test_verify_quote_nonce_failure() {
let quote = Quote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let mut wrong_report_data = REPORT_DATA.to_vec();
wrong_report_data.reverse();
verify_nonce(&quote, &wrong_report_data).unwrap_err();
}

#[test]
fn test_verify_pcrs() {
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
verify_pcrs(&quote).unwrap();
}

#[test]
fn test_verify_pcrs_failure() {
let mut quote = QUOTE.clone();
quote[0x0169] = 0;
let wrong_quote: Quote = bincode::deserialize(&quote).unwrap();

assert_eq!(
verify_pcrs(&wrong_quote)
.unwrap_err()
.downcast_ref::<VerifyError>()
.unwrap()
.to_string(),
VerifyError::PcrMismatch.to_string()
);
}
}
85 changes: 60 additions & 25 deletions attestation-service/verifier/src/az_tdx_vtpm/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,9 @@ impl Verifier for AzTdxVtpm {
/// The following verification steps are performed:
/// 1. TPM Quote has been signed by AK included in the HCL variable data
/// 2. Attestation nonce matches TPM Quote nonce
/// 3. TD Quote is genuine
/// 4. TD Report's report_data field matches hashed HCL variable data
/// 3. TPM PCRs' digest matches the digest in the Quote
/// 4. TD Quote is genuine
/// 5. TD Report's report_data field matches hashed HCL variable data
async fn evaluate(
&self,
evidence: &[u8],
Expand All @@ -54,6 +55,8 @@ impl Verifier for AzTdxVtpm {

verify_tpm_nonce(&evidence.tpm_quote, expected_report_data)?;

verify_pcrs(&evidence.tpm_quote)?;

ecdsa_quote_verification(&evidence.td_quote).await?;
let td_quote = parse_tdx_quote(&evidence.td_quote)?;

Expand Down Expand Up @@ -84,6 +87,14 @@ fn verify_tpm_signature(quote: &TpmQuote, hcl_report: &HclReport) -> Result<()>
Ok(())
}

fn verify_pcrs(quote: &TpmQuote) -> Result<()> {
quote
.verify_pcrs()
.context("Digest of PCRs does not match digest in Quote")?;
debug!("PCR verification completed successfully");
Ok(())
}

fn verify_tpm_nonce(quote: &TpmQuote, report_data: &[u8]) -> Result<()> {
let nonce = quote.nonce()?;
if nonce != report_data[..] {
Expand All @@ -96,10 +107,11 @@ fn verify_tpm_nonce(quote: &TpmQuote, report_data: &[u8]) -> Result<()> {
#[cfg(test)]
mod tests {
use super::*;
use az_tdx_vtpm::vtpm::Quote;
use az_tdx_vtpm::vtpm::VerifyError;

const REPORT: &[u8; 2600] = include_bytes!("../../test_data/az-tdx-vtpm/hcl-report.bin");
const SIGNATURE: &[u8; 256] = include_bytes!("../../test_data/az-tdx-vtpm/tpm-quote.sig");
const MESSAGE: &[u8; 126] = include_bytes!("../../test_data/az-tdx-vtpm/tpm-quote.msg");
const QUOTE: &[u8; 1362] = include_bytes!("../../test_data/az-tdx-vtpm/quote.bin");
const TD_QUOTE: &[u8; 5006] = include_bytes!("../../test_data/az-tdx-vtpm/td-quote.bin");

#[test]
Expand All @@ -115,48 +127,71 @@ mod tests {
wrong_report[0x0880] += 1;
let hcl_report = HclReport::new(wrong_report.to_vec()).unwrap();
let td_quote = parse_tdx_quote(TD_QUOTE).unwrap();
verify_hcl_var_data(&hcl_report, &td_quote).unwrap_err();
assert_eq!(
verify_hcl_var_data(&hcl_report, &td_quote)
.unwrap_err()
.to_string(),
"TDX Quote report data mismatch"
);
}

#[test]
fn test_verify_tpm_signature() {
let quote = TpmQuote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let hcl_report = HclReport::new(REPORT.to_vec()).unwrap();
verify_tpm_signature(&quote, &hcl_report).unwrap();
}

#[test]
fn test_verify_tpm_signature_failure() {
let mut wrong_message = MESSAGE.clone();
wrong_message.reverse();
let wrong_quote = TpmQuote {
signature: SIGNATURE.to_vec(),
message: wrong_message.to_vec(),
};
let mut quote = QUOTE.clone();
quote[0x020] = 0;
let wrong_quote: Quote = bincode::deserialize(&quote).unwrap();

let hcl_report = HclReport::new(REPORT.to_vec()).unwrap();
verify_tpm_signature(&wrong_quote, &hcl_report).unwrap_err();
assert_eq!(
verify_tpm_signature(&wrong_quote, &hcl_report)
.unwrap_err()
.downcast_ref::<VerifyError>()
.unwrap()
.to_string(),
VerifyError::SignatureMismatch.to_string()
);
}

#[test]
fn test_verify_tpm_nonce() {
let quote = TpmQuote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let nonce = "tdx challenge".as_bytes();
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let nonce = "challenge".as_bytes();
verify_tpm_nonce(&quote, nonce).unwrap();
}

#[test]
fn test_verify_tpm_nonce_failure() {
let quote = TpmQuote {
signature: SIGNATURE.to_vec(),
message: MESSAGE.to_vec(),
};
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
let wrong_nonce = "wrong".as_bytes();
verify_tpm_nonce(&quote, wrong_nonce).unwrap_err();
}

#[test]
fn test_verify_pcrs() {
let quote: Quote = bincode::deserialize(QUOTE).unwrap();
verify_pcrs(&quote).unwrap();
}

#[test]
fn test_verify_pcrs_failure() {
let mut quote = QUOTE.clone();
quote[0x0169] = 0;
let wrong_quote: Quote = bincode::deserialize(&quote).unwrap();

assert_eq!(
verify_pcrs(&wrong_quote)
.unwrap_err()
.downcast_ref::<VerifyError>()
.unwrap()
.to_string(),
VerifyError::PcrMismatch.to_string()
);
}
}
8 changes: 4 additions & 4 deletions attestation-service/verifier/src/snp/mod.rs
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Expand Up @@ -173,19 +173,19 @@ pub(crate) fn verify_report_signature(
// tcb version
// these integer extensions are 3 bytes with the last byte as the data
if get_oid_int(&parsed_vcek, UCODE_SPL_OID)? != report.reported_tcb.microcode {
return Err(anyhow!("Microcode verion mismatch"));
return Err(anyhow!("Microcode version mismatch"));
}

if get_oid_int(&parsed_vcek, SNP_SPL_OID)? != report.reported_tcb.snp {
return Err(anyhow!("SNP verion mismatch"));
return Err(anyhow!("SNP version mismatch"));
}

if get_oid_int(&parsed_vcek, TEE_SPL_OID)? != report.reported_tcb.tee {
return Err(anyhow!("TEE verion mismatch"));
return Err(anyhow!("TEE version mismatch"));
}

if get_oid_int(&parsed_vcek, LOADER_SPL_OID)? != report.reported_tcb.bootloader {
return Err(anyhow!("Boot loader verion mismatch"));
return Err(anyhow!("Boot loader version mismatch"));
}

// verify report signature
Expand Down
Binary file modified attestation-service/verifier/test_data/az-snp-vtpm/hcl-report.bin
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Binary file added attestation-service/verifier/test_data/az-snp-vtpm/quote.bin
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