update x509-limbo to latest, fix empty name constraint seq handling - #535
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This brings in new tests for empty permittedSubtrees name constraints. The non-empty control passes as expected, but webpki treats an empty permittedSubtrees sequence as absent. Add the invalid empty case to exceptions.
RFC 5280 requires NameConstraints to contain at least one of permittedSubtrees or excludedSubtrees. Both fields use GeneralSubtrees, which is defined as a sequence with one or more entries. A present but empty field is therefore invalid. Reject these encodings as malformed name constraints. This allows the x509-limbo cases for an empty extension, two empty subtree fields, and an empty permittedSubtrees alongside excludedSubtrees to pass without exceptions.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
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djc
approved these changes
Sep 2, 2026
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Nice! |
ctz
approved these changes
Sep 2, 2026
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Updates x509-limbo to latest. Notably this adds a testcase (C2SP/x509-limbo#658) for an empty permittedSubtrees sequence (
rfc5280::nc::permitted-empty-sequence-excluded-nonempty) that webpki previously accepted.In a subsequent commit the behavior is fixed so that we reject this new case as expected (and the related
webpki::nc::intermediate-permitted-excluded-subtrees-both-nullandwebpki::nc::intermediate-permitted-excluded-subtrees-both-empty-sequencescases we had pre-existing exceptions for). I think is pretty straight forward spec compliance and since NCs are rare in practice should have no meaningful user impact.This also checks off one of the #70 entries, "RFC5280 s4.2.1.10 'Conforming CAs MUST NOT issue certificates where name constraints is an empty sequence.'".