Android: LibreSSL fails to load and use system CAs

[aberaud]

On Android, LibreSSL (used with Asio) fails to use the system CAs (at /etc/security/cacerts) and every certificate check fails with error 19 / unknown ca, despite calling:
ssl_ctx->set_default_verify_paths(); // calls SSL_CTX_set_default_verify_paths

The same code works fine on classic GNU/Linux systems.

I tried adding
ssl_ctx->add_verify_path("/etc/security/cacerts/"); // calls SSL_CTX_load_verify_locations
manually without success.

I noticed the source tree doesn't have any reference to /etc/security/cacerts.
I tried changing crypto/cryptlib.h to use /etc/security/cacerts for X509_CERT_DIR, without any luck.

Expected behavior:
LibreSSL should load Android system CAs when using set_default_verify_paths();

[kinichiro]

Hi, You can set directory when you configure libressl with cmake, like -DOPENSSLDIR=/etc/security

[aberaud]

Thanks,

however, this would not allow to set X509_CERT_DIR to the Android directory /etc/security/cacerts/ since "certs" is appended instead of "cacert".

[aberaud]

See for instance how this is handled by GnuTLS:
https://github.com/gnutls/gnutls/blob/master/lib/system/certs.c#L218

Not tested yet but current code suggests LibreSSL would also fail to use system CAs on iOS.

Have anyone tried to use LibreSSL on Android or iOS ?
Thanks

[aberaud]

Made a PR for this:
libressl/openbsd#116

However, even with the right path, LibreSSL was unable to use system CAs to verify server certificates (code working fine on GNU/Linux). Always error 19 and "tlsv1 alert unknown ca".

[aberaud]

Just noticed with great horror that no code exists to load system CAs for any other system than GNU/Linux.

That means various projects use tricks like:
https://github.com/sfackler/rust-native-tls/pull/31/files
to get certificate verification working with system CAs on Android.

iOS and macOS would also require system-specific code.

It sounds really insane that this is sill an unsolved problem in 2020. Am I missing something ?
Many thanks

[kinichiro]

Hi,

I have one question after reading all of your commets, again.
Do you have cert hash ((e.g., 9d66eef0.0) in your /etc/security/cacerts/ ?
Since you said "However, even with the right path, LibreSSL was unable to use system CAs to verify server certificates" after posting libressl/openbsd#116 .

https://man.openbsd.org/SSL_CTX_load_verify_locations.3 describes ;

The files are looked up by the CA subject name hash value, which must hence be available. If more than one CA certificate with the same name hash value exist, the extension must be different (e.g., 9d66eef0.0, 9d66eef0.1, etc.).

If you don't, you can create cert hash by openssl certhash -v <dir>.
And if you do, I think SSL_CTX_load_verify_locations(ctx, NULL, "/etc/security/cacerts") would work.

[kinichiro]

@aberaud do you have any update for this issue ?
I posted my investigation above, and I think cert hash is required for this case.

[aberaud]

Hi,
We ended up embedding our own CA file on Android instead of trying to use the system one.

It would be great if loading system CAs on major platforms was handled by libraries like LibreSSL (a bit like what GnuTLS does). We had to implement per-platform loading with different logic for every platform.

[kinichiro]

Thanks for your answering.
Can you close this issue now ?