Deduplicate peer certificate chain processing code.

Rather than reimplement this in each TLS client and server, deduplicate it
into a single function. Furthermore, rather than dealing with the API
hazard that is SSL_get_peer_cert_chain() in this code, simply produce two
chains - one that has the leaf and one that does not.
SSL_get_peer_cert_chain() can then return the appropriate one.

This also moves the peer cert chain from the SSL_SESSION to the
SSL_HANDSHAKE, which makes more sense since it is not available on
resumption.

ok tb@

1 files changed, 3 insertions, 25 deletions

diff --git a/src/lib/libssl/tls13_server.c b/src/lib/libssl/tls13_server.c
index 5aee5f1a93..8f225433f0 100644
--- a/src/lib/libssl/tls13_server.c
+++ b/src/lib/libssl/tls13_server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_server.c,v 1.100 2022/07/24 14:16:29 jsing Exp $ */
+/* $OpenBSD: tls13_server.c,v 1.101 2022/08/17 07:39:19 jsing Exp $ */
 /*
  * Copyright (c) 2019, 2020 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2020 Bob Beck <beck@openbsd.org>
@@ -860,9 +860,7 @@ tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs)
         struct stack_st_X509 *certs = NULL;
         SSL *s = ctx->ssl;
         X509 *cert = NULL;
-        EVP_PKEY *pkey;
         const uint8_t *p;
-        int cert_type;
         int ret = 0;
 
         if (!CBS_get_u8_length_prefixed(cbs, &cert_request_context))
@@ -911,31 +909,11 @@ tls13_client_certificate_recv(struct tls13_ctx *ctx, CBS *cbs)
                     "failed to verify peer certificate", NULL);
                 goto err;
         }
+        s->session->verify_result = s->verify_result;
         ERR_clear_error();
 
-        /*
-         * Achtung! Due to API inconsistency, a client includes the peer's leaf
-         * certificate in the stored certificate chain, while a server does not.
-         */
-        cert = sk_X509_shift(certs);
-
-        if ((pkey = X509_get0_pubkey(cert)) == NULL)
+        if (!tls_process_peer_certs(s, certs))
                 goto err;
-        if (EVP_PKEY_missing_parameters(pkey))
-                goto err;
-        if ((cert_type = ssl_cert_type(pkey)) < 0)
-                goto err;
-
-        X509_up_ref(cert);
-        X509_free(s->session->peer_cert);
-        s->session->peer_cert = cert;
-        s->session->peer_cert_type = cert_type;
-
-        s->session->verify_result = s->verify_result;
-
-        sk_X509_pop_free(s->session->cert_chain, X509_free);
-        s->session->cert_chain = certs;
-        certs = NULL;
 
         ctx->handshake_stage.hs_type |= WITH_CCV;
         ret = 1;