hishtory/client/lib/slsa.go

94 lines
2.4 KiB
Go

package lib
import (
"context"
"crypto/sha256"
"encoding/hex"
"fmt"
"io"
"os"
"github.com/sigstore/cosign/cmd/cosign/cli/rekor"
"github.com/slsa-framework/slsa-verifier/pkg"
)
var defaultRekorAddr = "https://rekor.sigstore.dev"
// Verify SLSA provenance of the downloaded binary
// Copied from https://github.com/slsa-framework/slsa-verifier/blob/aee753f/main.go
// Once the slsa-verifier supports being used as a library, this can be removed
func verify(provenance []byte, artifactHash, source, branch, versionTag string) error {
rClient, err := rekor.NewClient(defaultRekorAddr)
if err != nil {
return err
}
// Get Rekor entries corresponding to the binary artifact in the provenance.
uuids, err := pkg.GetRekorEntries(rClient, artifactHash)
if err != nil {
return err
}
env, err := pkg.EnvelopeFromBytes(provenance)
if err != nil {
return err
}
// Verify the provenance and return the signing certificate.
cert, err := pkg.FindSigningCertificate(context.Background(), uuids, *env, rClient)
if err != nil {
return err
}
// Get the workflow info given the certificate information.
workflowInfo, err := pkg.GetWorkflowInfoFromCertificate(cert)
if err != nil {
return err
}
// Unpack and verify info in the provenance, including the Subject Digest.
if err := pkg.VerifyProvenance(env, artifactHash); err != nil {
return err
}
// Verify the workflow identity.
if err := pkg.VerifyWorkflowIdentity(workflowInfo, source); err != nil {
return err
}
// Verify the branch.
// TODO: This started failing for some reason? base_ref was null
// if err := pkg.VerifyBranch(env, branch); err != nil {
// return err
// }
// Verify the tag.
if err := pkg.VerifyTag(env, versionTag); err != nil {
return err
}
return nil
}
func verifyBinary(binaryPath, attestationPath, versionTag string) error {
// TODO: Also verify that the version is newer and this isn't a downgrade
attestation, err := os.ReadFile(attestationPath)
if err != nil {
return fmt.Errorf("failed to read attestation file: %v", err)
}
binaryFile, err := os.Open(binaryPath)
if err != nil {
return fmt.Errorf("failed to read binary for verification purposes: %v", err)
}
defer binaryFile.Close()
hasher := sha256.New()
if _, err := io.Copy(hasher, binaryFile); err != nil {
return fmt.Errorf("failed to hash binary: %v", err)
}
hash := hex.EncodeToString(hasher.Sum(nil))
return verify(attestation, hash, "github.com/ddworken/hishtory", "master", versionTag)
}