fix: verify PKCS7 signature on Azure instance identity tokens#25286
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spikecurtis
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May 13, 2026
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Migrates Azure instance identity verification from
go.mozilla.org/pkcs7andgithub.com/fullsailor/pkcs7togithub.com/smallstep/pkcs7, usingVerifyWithChainAtTimeto validate both the PKCS7 signature and the certificate chain in one call. The previous code only verified the signer certificate against a set of intermediates/roots but did not verify that the PKCS7 signature itself covered the content, meaning tampered payloads could be accepted.The
Optionsstruct is restructured to acceptRoots,Intermediates, andCurrentTimeas explicit fields instead of embeddingx509.VerifyOptions. The test helperNewAzureInstanceIdentitynow builds a realistic 3-level certificate chain (Root CA -> Intermediate CA -> Signing Cert) matching real Azure trust hierarchy. New tests (TestValidate_TamperedContent,TestValidate_UntrustedCertWithValidSignature) confirm tampered and untrusted envelopes are rejected.Addresses GHSA-6x44-w3xg-hqqf.
Note
This PR was authored by Coder Agents.
Implementation Plan
Files Changed
coderd/azureidentity/azureidentity.gosigner.Verify()withVerifyWithChainAtTime; restructureOptionsstruct; addParseCertificates()helpercoderd/azureidentity/azureidentity_test.gotestCertChainbuilder, tampered-content and untrusted-cert tests; update existing tests for newOptionsAPIcoderd/coderd.goAzureCertificatesfield fromx509.VerifyOptionstoazureidentity.Optionscoderd/workspaceresourceauth.goapi.AzureCertificatesdirectly instead of wrappingcoderd/coderdtest/coderdtest.gosmallstep/pkcs7; build 3-level cert chain in test helpergo.mod/go.sumgithub.com/smallstep/pkcs7; removefullsailor/pkcs7andgo.mozilla.org/pkcs7