fix(protocol): ensure attca is parsed correctly #280
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WalkthroughThe recent updates enhance the attestation validation process by adding a new conditional check in the Changes
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Review profile: CHILL
Files selected for processing (2)
- protocol/attestation.go (1 hunks)
- protocol/attestation_tpm.go (4 hunks)
Additional comments not posted (4)
protocol/attestation.go (1)
252-256: LGTM! But verify the SAN parsing logic.The changes correctly handle the
metadata.AttCAattestation type by parsing the SAN extension. Ensure that thetpmParseSANExtensionfunction is correctly implemented and integrated.protocol/attestation_tpm.go (3)
Line range hint
150-197:
Refactoring and error handling improvements look good!The refactoring of variable declarations and enhanced error handling improve readability and provide clearer error messages. Ensure that the new validation checks for EKU and Basic Constraints align with the specifications.
Verification successful
Validation checks for EKU and Basic Constraints are correctly implemented.
The OIDs for Extended Key Usage (2.5.29.37) and Basic Constraints (2.5.29.19) used in the code are standard and align with the specifications. The validation logic is correctly applied.
Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Verify the new validation checks for EKU and Basic Constraints. # Test: Search for the usage of EKU and Basic Constraints OIDs and ensure they align with specifications. rg --type go 'oidExtensionExtendedKeyUsage|oidExtensionBasicConstraints'Length of output: 406
390-399: New variable and type declarations are well-organized!The addition of OID variables and the
tpmBasicConstraintstype improves code readability and organization. Ensure these are used consistently and correctly throughout the code.Verification successful
New variable and type declarations are correctly used!
The new OID variables and the
tpmBasicConstraintstype are consistently and correctly used in the codebase. Their integration into conditional checks and type declarations aligns with their intended purpose, enhancing the code's structure and clarity.
- Usage confirmed in
protocol/attestation_tpm.go.Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Verify the usage of new OID variables and the `tpmBasicConstraints` type. # Test: Search for the usage of the newly added variables and type to ensure consistent and correct usage. rg --type go 'oidExtensionSubjectAltName|oidExtensionExtendedKeyUsage|oidExtensionBasicConstraints|tpmBasicConstraints'Length of output: 901
358-387: NewtpmParseSANExtensionfunction looks good!The function encapsulates the SAN parsing logic, improving modularity and error handling. Verify that the parsing logic correctly identifies and handles the required fields.
Verification successful
Verification Successful:
tpmParseSANExtensionFunctionThe
parseSANExtensionfunction is present and utilized withintpmParseSANExtension, ensuring that SAN parsing is handled methodically. This supports the robustness and modularity of thetpmParseSANExtensionfunction.
parseSANExtensionis implemented and used for SAN parsing.forEachSANis employed to iterate over SAN entries, indicating a structured parsing approach.Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Description: Verify the robustness of the `tpmParseSANExtension` function. # Test: Search for the function implementation and ensure it correctly handles SAN parsing. ast-grep --lang go --pattern $'func parseSANExtension($_) { $$$ }'Length of output: 69
Script:
#!/bin/bash # Description: Search for any function related to SAN parsing in the Go codebase. # Use ripgrep to search for functions that might be related to SAN parsing. rg --type go --pattern 'func.*SAN.*\(' -A 5Length of output: 457
Script:
#!/bin/bash # Description: Search for any function related to SAN parsing in the Go codebase. # Correct the ripgrep command to search for functions that might be related to SAN parsing. rg 'func.*SAN.*\(' --type go -A 5Length of output: 1215
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Files selected for processing (2)
- protocol/attestation.go (1 hunks)
- protocol/attestation_tpm.go (4 hunks)
Additional comments not posted (2)
protocol/attestation.go (1)
252-256: Review of new attestation type handling.The addition of a conditional check for
metadata.AttCAis a targeted enhancement to handle specific attestation types. This change seems to integrate well with the existing structure and should improve the attestation handling process by ensuring that the Subject Alternative Name (SAN) extension is parsed correctly when necessary.However, ensure that the
tpmParseSANExtensionfunction is robust and handles all possible edge cases, as errors in this function could lead to incorrect attestation data being accepted.protocol/attestation_tpm.go (1)
Line range hint
150-197: Review of changes toverifyTPMFormatfunction.The modifications to the
verifyTPMFormatfunction enhance the clarity and robustness of AIK certificate parsing and validation. The introduction of thetpmParseSANExtensionfunction as a separate method to handle SAN parsing is a good example of separation of concerns, which should make the code easier to maintain and extend.However, ensure that the error handling within the
tpmParseSANExtensionfunction is comprehensive and that all error messages provide clear, actionable information. Additionally, the consolidation of EKU checks and the handling of unprocessed critical extensions are significant changes that should be carefully reviewed to ensure they do not introduce new issues or overlook existing ones.Verification successful
Comprehensive Error Handling in
tpmParseSANExtensionFunction VerifiedThe
tpmParseSANExtensionfunction includes detailed error handling and provides clear, actionable error messages when parsing the Subject Alternative Name (SAN) extension. This ensures robustness in AIK certificate validation.Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash # Verify that the error handling within the `tpmParseSANExtension` function is comprehensive. # Test: Search for the function implementation and unit tests. Expect: Comprehensive error handling and clear error messages. rg --type go -A 5 $'tpmParseSANExtension'Length of output: 653
Script:
#!/bin/bash # Retrieve the full implementation of the `tpmParseSANExtension` function for review. ast-grep --lang go --pattern $'func tpmParseSANExtension($_) { $$$ }'Length of output: 72
Script:
#!/bin/bash # Use `rg` to capture the full implementation of the `tpmParseSANExtension` function. rg --type go -A 20 'func tpmParseSANExtension'Length of output: 1448
This fixes an issue where the attca attestation (TPM 2.0) was not properly parsed due to a nuance with how the AIK certificates conform to the spec and the critical extension parsing.
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🧹 Outside diff range and nitpick comments (6)
protocol/attestation.go (2)
252-256: Enhance error context for TPM attestation validationWhile the addition of TPM SAN extension parsing for AttCA attestation type is correct, the error handling could be improved to provide better context for debugging attestation failures.
Consider wrapping the error with additional context:
if attestationType == string(metadata.AttCA) { if err = tpmParseSANExtension(x5c); err != nil { - return err + return ErrInvalidAttestation.WithDetails(fmt.Sprintf("TPM attestation SAN extension validation failed: %v", err)) } }
252-256: Consider adding test coverage for TPM attestation validationThe new TPM attestation validation logic should be thoroughly tested with various test cases including:
- Valid TPM AttCA attestation with correct SAN extension
- Invalid SAN extension formats
- Missing SAN extension
- Non-TPM attestation types
Would you like me to help create comprehensive test cases for the TPM attestation validation?
protocol/attestation_tpm.go (4)
148-150: Initialize 'aikCert' directly without prior declaration.The variable
aikCertis declared at line 148 but immediately assigned in line 150. You can simplify the code by combining the declaration and assignment, which enhances readability.Apply this diff to streamline the variable initialization:
-var aikCert *x509.Certificate -if aikCert, err = x509.ParseCertificate(aikCertBytes); err != nil { +if aikCert, err := x509.ParseCertificate(aikCertBytes); err != nil { return "", nil, ErrAttestationFormat.WithDetails("Error parsing certificate from ASN.1") }
178-193: Refactor 'if-else' chain to a 'switch' statement for clarity.The series of
if-elseconditions starting at line 179 can be refactored into aswitchstatement. This change improves readability and makes future extensions easier to manage.Apply this diff to implement the refactoring:
for _, ext := range aikCert.Extensions { - if ext.Id.Equal(oidExtensionSubjectAltName) { + switch { + case ext.Id.Equal(oidExtensionSubjectAltName): if manufacturer, model, version, err = parseSANExtension(ext.Value); err != nil { return "", nil, err } - } else if ext.Id.Equal(oidExtensionExtendedKeyUsage) { + case ext.Id.Equal(oidExtensionExtendedKeyUsage): if rest, err = asn1.Unmarshal(ext.Value, &eku); len(rest) != 0 || err != nil || !eku[0].Equal(tcgKpAIKCertificate) { return "", nil, ErrAttestationFormat.WithDetails("AIK certificate EKU missing 2.23.133.8.3") } ekuValid = true - } else if ext.Id.Equal(oidExtensionBasicConstraints) { + case ext.Id.Equal(oidExtensionBasicConstraints): if rest, err = asn1.Unmarshal(ext.Value, &constraints); err != nil { return "", nil, ErrAttestationFormat.WithDetails("AIK certificate basic constraints malformed") } else if len(rest) != 0 { return "", nil, ErrAttestationFormat.WithDetails("AIK certificate basic constraints contains extra data") } + } }🧰 Tools
🪛 golangci-lint
178-178: ifElseChain: rewrite if-else to switch statement
(gocritic)
379-387: Preallocate 'unhandled' slice to optimize performance.At line 379, the
unhandledslice can be preallocated with the capacity of the originalUnhandledCriticalExtensionsslice. This optimization reduces memory reallocations during append operations.Apply this diff to preallocate the slice:
-var unhandled []asn1.ObjectIdentifier +unhandled := make([]asn1.ObjectIdentifier, 0, len(attestation.UnhandledCriticalExtensions))🧰 Tools
🪛 golangci-lint
379-379: Consider pre-allocating
unhandled(prealloc)
395-398: Group related OID constants together for better organization.The OID constants at lines 395-398 are related to certificate extensions. Grouping them together with a descriptive comment enhances code readability.
Consider adding a comment and grouping:
// OID constants for certificate extensions var ( oidExtensionSubjectAltName = []int{2, 5, 29, 17} oidExtensionExtendedKeyUsage = []int{2, 5, 29, 37} oidExtensionBasicConstraints = []int{2, 5, 29, 19} )
📜 Review details
Configuration used: CodeRabbit UI
Review profile: CHILL
📒 Files selected for processing (2)
protocol/attestation.go(1 hunks)protocol/attestation_tpm.go(3 hunks)
🧰 Additional context used
🪛 golangci-lint
protocol/attestation_tpm.go
178-178: ifElseChain: rewrite if-else to switch statement
(gocritic)
379-379: Consider pre-allocating unhandled
(prealloc)
🔇 Additional comments (3)
protocol/attestation.go (1)
252-256: Verify TPM attestation type handling
The code adds critical validation for TPM AttCA attestation type. Let's verify that this is the only attestation type that requires SAN extension parsing and that the tpmParseSANExtension function properly validates all required fields according to the TPM 2.0 specification.
✅ Verification successful
Based on the search results, I can now generate the final response:
TPM AttCA attestation type validation is correctly implemented
The code correctly handles TPM AttCA attestation type validation. The search results confirm:
- AttCA is a specific attestation type defined in metadata/types.go for PrivacyCA attestation
- SAN extension parsing is only used for TPM AttCA attestation (no other usage found)
- The tpmParseSANExtension function in attestation_tpm.go properly validates the SAN extension according to TPM 2.0 specification requirements, with appropriate error handling for invalid AIK certificate data
🏁 Scripts executed
The following scripts were executed for the analysis:
Script:
#!/bin/bash
# Description: Check for other TPM attestation types and SAN extension usage
# Search for TPM-related attestation type definitions
echo "Checking TPM attestation type definitions:"
rg -A 3 "type\s+(?:Att|Attestation)" --type go
# Search for other places where SAN extensions are parsed
echo "Checking SAN extension parsing usage:"
rg "ParseSANExtension|GetExtension.*subject.*alternative.*name" --type go
# Search for TPM-related constants and types
echo "Checking TPM-related code:"
rg "TPM|AttCA|AIK" --type go
Length of output: 10998
protocol/attestation_tpm.go (2)
375-377:
Enhance validation of SAN data fields for security compliance.
The check for empty manufacturer, model, or version strings ensures they are present but does not validate their content. Consider adding stricter validation to ensure these fields contain acceptable values, preventing potential security risks from malformed or malicious data.
Would you like assistance in implementing additional validation checks for these fields?
381-387:
Avoid modifying the slice while iterating over it.
Modifying attestation.UnhandledCriticalExtensions within the loop can lead to unexpected behavior. Instead of altering the original slice, consider creating a new slice for unhandled extensions.
Apply this diff to safely handle the unhandled critical extensions:
for _, uce := range attestation.UnhandledCriticalExtensions {
if uce.Equal(oidExtensionSubjectAltName) {
continue
}
- unhandled = append(unhandled, uce)
+ unhandled = append(unhandled, uce)
}
-attestation.UnhandledCriticalExtensions = unhandled
+attestation.UnhandledCriticalExtensions = unhandledEnsure that you're not modifying the slice being iterated over to prevent runtime errors.
Likely invalid or redundant comment.
This fixes an issue where the attca attestation (TPM 2.0) was not properly parsed due to a nuance with how the AIK certificates conform to the spec and the critical extension parsing.