mirror of https://github.com/openssl/openssl.git
0c3eb2793b
The client-side cert verification callback function may not only return as usual for success or 0 for failure, but also -1, typically on failure verifying the server certificate. This makes the handshake suspend and return control to the calling application with SSL_ERROR_WANT_RETRY_VERIFY. The app can for instance fetch further certificates or cert status information needed for the verification. Calling SSL_connect() again resumes the connection attempt by retrying the server certificate verification step. This process may even be repeated if need be. The core implementation of the feature is in ssl/statem/statem_clnt.c, splitting tls_process_server_certificate() into a preparation step that just copies the certificates received from the server to s->session->peer_chain (rather than having them in a local variable at first) and returns to the state machine, and a post-processing step in tls_post_process_server_certificate() that can be repeated: Try verifying the current contents of s->session->peer_chain basically as before, but give the verification callback function the chance to pause connecting and make the TLS state machine later call tls_post_process_server_certificate() again. Otherwise processing continues as usual. The documentation of the new feature is added to SSL_CTX_set_cert_verify_callback.pod and SSL_want.pod. This adds two tests: * A generic test in test/helpers/handshake.c on the usability of the new server cert verification retry feature. It is triggered via test/ssl-tests/03-custom_verify.cnf.in (while the bulky auto- generated changes to test/ssl-tests/03-custom_verify.cnf can be basically ignored). * A test in test/sslapitest.c that demonstrates the effectiveness of the approach for augmenting the cert chain provided by the server in between SSL_connect() calls. Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/13906) |
||
|---|---|---|
| .. | ||
| cmp_testlib.c | ||
| cmp_testlib.h | ||
| handshake.c | ||
| handshake.h | ||
| pkcs12.c | ||
| pkcs12.h | ||
| predefined_dhparams.c | ||
| predefined_dhparams.h | ||
| ssl_test_ctx.c | ||
| ssl_test_ctx.h | ||
| ssltestlib.c | ||
| ssltestlib.h | ||