Re: mutt fetch-mail ssl error

On Tue, May 31, 2022 at 03:00:48PM +0100, Stuart Henderson wrote:
> I've been able to replicate this now, but I'm not seeing any recent
> change in behaviour, I've tried with mutt versions going back to 2.0.7
> with the libressl version in 7.1, and on 7.0 with the current version
> of mutt in packages for release, and they all behave the same.
>
> It's not specific to any particular mail server but requires
> ssl_usesystemcerts=no.
>
> Avon: to workaround your problem, remove "set ssl_usesystemcerts=no",
> it will then validate against /etc/ssl/cert.pem and avoid asking you
> each time. But I don't see what could have changed recently that is
> triggering it.
>
> Test case:
>
> $ cat .muttrc-test
> set certificate_file="~/.mutt_test_certificates"
> set pop_host="pops://test_libressl_issue@mail.spacehopper.org:995"
> set ssl_usesystemcerts=no
>
> $ rm .mutt_test_certificates
> $ mutt -F .muttrc-test
>
> <hit G, "fetch-mail">
> <hit a, "accept always">
> ^C, exit
> repeat trying to fetch mail
>
> With the "ssl_usesystermcerts=no" config, I would expect that mutt would
> need to save all of (server, intermediate, CA) certificates to its cert
> file, in order that it can verify in future.
>
> What actually happens is the server certificate is saved, not the CA
> or intermediate certificate, and *somehow* the validation succeeds if you
> append _any_ self-signed certificate (e.g. tail -25 /etc/ssl/cert.pem >>
> .mutt_test_certificates).
>
> Not sure if this is a Mutt problem or a LibreSSL one. I haven't compared
> with a build done against OpenSSL rather than LibreSSL yet (the only
> other install I have handy right now is Debian and their Mutt packages
> use gnutls instead which don't support setting ssl_usesystemcerts at all).

It seems to be another issue with the new verifier. I cannot reproduce
with mutt linked against eopenssl11 and I cannot reproduce with the
legacy verifier.

x509_verify_ctx_validate_legacy_chain() fails because PARTIAL_CHAIN
isn't set and trust is X509_TRUST_UNTRUSTED.

The connection works with the new verifier if the above muttrc is
extended with 'set ssl_verify_partial_chains=yes'.