scep: name the issuing CA in the GetCertInitial IssuerAndSubject

[yosuke-wolfssl]

Problem

wolfcert_scep_issuer_and_subject copied the subject Name out of the certificate it was handed into the issuer field of the RFC 8894 section 3.3.2 IssuerAndSubject, and both call sites pass ra_cert. In a split RA/CA deployment — Microsoft NDES, or any RA-fronted CA — ra_cert is an end-entity RA certificate, so a GetCertInitial poll named the RA instead of the issuing CA. A server that locates a pending request by DN cannot find it, and one that cross-checks the pair rejects the poll outright.

That is the deployment where it matters most: an RA with manual approval is what returns PENDING and drives a client into GetCertInitial in the first place. Nothing caught it because every test certificate in the tree is self-signed, which makes subject and issuer indistinguishable.

Fix (src/scep/scep_msg.c)

The issuer Name is selected from the certificate itself:

if (ic.extBasicConstSet && ic.isCA) {
    issuer_name     = ic.subjectRaw;    /* a CA issues under its own name */
    issuer_name_len = ic.subjectRawLen;
}
else {
    issuer_name     = ic.issuerRaw;     /* an RA: its issuer is the CA */
    issuer_name_len = ic.issuerRawLen;
}

ra_cert	issuer Name	before
RA certificate (end entity)	its issuer, i.e. the CA	wrong — named the RA
self-signed CA	its own subject	correct
sub-CA under an offline root	its own subject	correct

The third row is why a blind subjectRaw → issuerRaw swap is not the fix: it would name the root instead of the actual issuer. ca_bundle is not consulted — issuerRaw already is the CA's subject DN, byte for byte, so no signature or public API change is needed. The parameter is renamed ra_cert_der/ra_cert_len to match what callers pass, and the function is WOLFCERT_TEST_VIS so tests can link it.

Closes f-8022.

Tests (tests/unit/test_scep_msg.c)

make_signed_cert() issues a certificate under the existing make_ca() CA with its own subject and a settable CA flag — the first helper in the tree producing issuer ≠ subject. test_issuer_and_subject_issuer_name() builds the structure for all three targets above and compares both Names byte for byte.

Verification

• 26/26 ctest pass, including scep_poll_roundtrip.
• Negative control: before the fix the new test fails on the split-RA case only; the single-CA and sub-CA cases pass throughout.

[Copilot]

Pull request overview

This PR fixes SCEP GetCertInitial polling in split RA/CA deployments by ensuring the RFC 8894 IssuerAndSubject “issuer” Name identifies the issuing CA (not the RA end-entity), and adds unit coverage for issuer≠subject scenarios.

Changes:

• Update wolfcert_scep_issuer_and_subject() to select the issuer Name from either subjectRaw (CA) or issuerRaw (RA end-entity).
• Expose wolfcert_scep_issuer_and_subject() to in-tree tests via WOLFCERT_TEST_VIS and clarify its contract in comments.
• Add new unit-test helpers to create CA-signed certificates (issuer ≠ subject) and validate issuer/subject Name bytes for split-RA, self-signed CA, and sub-CA cases.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/scep/scep_msg.c	Corrects IssuerAndSubject issuer Name selection (CA vs RA certificate).
src/internal.h	Updates internal/test-visible prototype and documentation for IssuerAndSubject builder.
tests/unit/test_scep_msg.c	Adds certificate-issuing helper and new unit test covering issuer-name selection across deployment shapes.

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[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #21

Scan targets checked: wolfcert-bugs, wolfcert-src

No new issues found in the changed files. ✅