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fix: use tpm2 hash algorithm constants and allow non-SHA-256 PCRs #7811

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merged 1 commit into from
Oct 3, 2023
Merged

fix: use tpm2 hash algorithm constants and allow non-SHA-256 PCRs #7811

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33 changes: 10 additions & 23 deletions internal/pkg/secureboot/tpm2/pcr.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ package tpm2

import (
"bytes"
"crypto"
"crypto/sha256"
"fmt"
"log"
Expand Down Expand Up @@ -164,30 +163,18 @@ func validatePCRBanks(t transport.TPM) error {
}

for _, s := range assignedPCRs.PCRSelections {
h, err := s.Hash.Hash()
if err != nil {
return fmt.Errorf("failed to parse hash algorithm: %v", err)
if s.Hash != tpm2.TPMAlgSHA256 {
continue
}

switch h { //nolint:exhaustive
case crypto.SHA1:
continue
case crypto.SHA256:
// check if 24 banks are available
if len(s.PCRSelect) != 24/8 {
return fmt.Errorf("unexpected number of PCR banks: %d", len(s.PCRSelect))
}

// check if all banks are available
if s.PCRSelect[0] != 0xff || s.PCRSelect[1] != 0xff || s.PCRSelect[2] != 0xff {
return fmt.Errorf("unexpected PCR banks: %v", s.PCRSelect)
}
case crypto.SHA384:
continue
case crypto.SHA512:
continue
default:
return fmt.Errorf("unsupported hash algorithm: %s", h.String())
// check if 24 banks are available
if len(s.PCRSelect) != 24/8 {
return fmt.Errorf("unexpected number of PCR banks: %d", len(s.PCRSelect))
}

// check if all banks are available
if s.PCRSelect[0] != 0xff || s.PCRSelect[1] != 0xff || s.PCRSelect[2] != 0xff {
return fmt.Errorf("unexpected PCR banks: %v", s.PCRSelect)
}
}

Expand Down