1 files changed, 213 insertions, 1 deletions

diff --git a/src/lib/libssl/tls13_client.c b/src/lib/libssl/tls13_client.c
index 6578438c78..d15ab65105 100644
--- a/src/lib/libssl/tls13_client.c
+++ b/src/lib/libssl/tls13_client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_client.c,v 1.5 2019/02/09 15:26:15 jsing Exp $ */
+/* $OpenBSD: tls13_client.c,v 1.6 2019/02/11 17:48:15 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -343,3 +343,215 @@ tls13_server_encrypted_extensions_recv(struct tls13_ctx *ctx)
 
         return 0;
 }
+
+int
+tls13_server_certificate_request_recv(struct tls13_ctx *ctx)
+{
+        /*
+         * Thanks to poor state design in the RFC, this function can be called
+         * when we actually have a certificate message instead of a certificate
+         * request... in that case we call the certificate handler after
+         * switching state, to avoid advancing state.
+         */
+        if (tls13_handshake_msg_type(ctx->hs_msg) == TLS13_MT_CERTIFICATE) {
+                ctx->handshake_stage.hs_type |= WITHOUT_CR;
+                return tls13_server_certificate_recv(ctx);
+        }
+
+        /* XXX - unimplemented. */
+
+        return 0;
+}
+
+int
+tls13_server_certificate_recv(struct tls13_ctx *ctx)
+{
+        CBS cbs, cert_request_context, cert_list, cert_data, cert_exts;
+        struct stack_st_X509 *certs = NULL;
+        SSL *s = ctx->ssl;
+        X509 *cert = NULL;
+        EVP_PKEY *pkey;
+        const uint8_t *p;
+        int cert_idx;
+        int ret = 0;
+
+        if ((certs = sk_X509_new_null()) == NULL)
+                goto err;
+
+        if (!tls13_handshake_msg_content(ctx->hs_msg, &cbs))
+                goto err;
+
+        if (!CBS_get_u8_length_prefixed(&cbs, &cert_request_context))
+                goto err;
+        if (CBS_len(&cert_request_context) != 0)
+                goto err;
+        if (!CBS_get_u24_length_prefixed(&cbs, &cert_list))
+                goto err;
+        if (CBS_len(&cbs) != 0)
+                goto err;
+
+        while (CBS_len(&cert_list) > 0) {
+                if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data))
+                        goto err;
+                if (!CBS_get_u16_length_prefixed(&cert_list, &cert_exts))
+                        goto err;
+
+                p = CBS_data(&cert_data);
+                if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL)
+                        goto err;
+                if (p != CBS_data(&cert_data) + CBS_len(&cert_data))
+                        goto err;
+
+                if (!sk_X509_push(certs, cert))
+                        goto err;
+
+                cert = NULL;
+        }
+
+        /*
+         * At this stage we still have no proof of possession. As such, it would
+         * be preferable to keep the chain and verify once we have successfully
+         * processed the CertificateVerify message.
+         */
+        if (ssl_verify_cert_chain(s, certs) <= 0 &&
+            s->verify_mode != SSL_VERIFY_NONE) {
+                /* XXX send alert */
+                goto err;
+        }
+        ERR_clear_error();
+
+        cert = sk_X509_value(certs, 0);
+        X509_up_ref(cert);
+
+        if ((pkey = X509_get0_pubkey(cert)) == NULL)
+                goto err;
+        if (EVP_PKEY_missing_parameters(pkey))
+                goto err;
+        if ((cert_idx = ssl_cert_type(cert, pkey)) < 0)
+                goto err;
+
+        ssl_sess_cert_free(SSI(s)->sess_cert);
+        if ((SSI(s)->sess_cert = ssl_sess_cert_new()) == NULL)
+                goto err;
+
+        SSI(s)->sess_cert->cert_chain = certs;
+        certs = NULL;
+
+        X509_up_ref(cert);
+        SSI(s)->sess_cert->peer_pkeys[cert_idx].x509 = cert;
+        SSI(s)->sess_cert->peer_key = &(SSI(s)->sess_cert->peer_pkeys[cert_idx]);
+
+        X509_free(s->session->peer);
+
+        X509_up_ref(cert);
+        s->session->peer = cert;
+        s->session->verify_result = s->verify_result;
+
+        ret = 1;
+
+ err:
+        sk_X509_pop_free(certs, X509_free);
+        X509_free(cert);
+
+        return ret;
+}
+
+/*
+ * Certificate Verify padding - RFC 8446 section 4.4.3.
+ */
+static uint8_t cert_verify_pad[64] = {
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+        0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 
+};
+
+static uint8_t server_cert_verify_context[] = "TLS 1.3, server CertificateVerify";
+
+int
+tls13_server_certificate_verify_recv(struct tls13_ctx *ctx)
+{
+        const struct ssl_sigalg *sigalg;
+        uint16_t signature_scheme;
+        uint8_t *sig_content = NULL;
+        size_t sig_content_len;
+        EVP_MD_CTX *mdctx = NULL;
+        EVP_PKEY_CTX *pctx;
+        EVP_PKEY *pkey;
+        X509 *cert;
+        CBS cbs, signature;
+        CBB cbb;
+        int ret = 0;
+
+        memset(&cbb, 0, sizeof(cbb));
+
+        if (!tls13_handshake_msg_content(ctx->hs_msg, &cbs))
+                goto err;
+
+        if (!CBS_get_u16(&cbs, &signature_scheme))
+                goto err;
+        if (!CBS_get_u16_length_prefixed(&cbs, &signature))
+                goto err;
+        if (CBS_len(&cbs) != 0)
+                goto err;
+
+        if ((sigalg = ssl_sigalg(signature_scheme, tls13_sigalgs,
+            tls13_sigalgs_len)) == NULL)
+                goto err;
+
+        if (!CBB_init(&cbb, 0))
+                goto err;
+        if (!CBB_add_bytes(&cbb, cert_verify_pad, sizeof(cert_verify_pad)))
+                goto err;
+        if (!CBB_add_bytes(&cbb, server_cert_verify_context,
+            strlen(server_cert_verify_context)))
+                goto err;
+        if (!CBB_add_u8(&cbb, 0))
+                goto err;
+        if (!CBB_add_bytes(&cbb, ctx->hs->transcript_hash,
+            ctx->hs->transcript_hash_len))
+                goto err;
+        if (!CBB_finish(&cbb, &sig_content, &sig_content_len))
+                goto err;
+
+        if ((cert = ctx->ssl->session->peer) == NULL)
+                goto err;
+        if ((pkey = X509_get0_pubkey(cert)) == NULL)
+                goto err;
+        if (!ssl_sigalg_pkey_ok(sigalg, pkey))
+                goto err;
+
+        if (CBS_len(&signature) > EVP_PKEY_size(pkey))
+                goto err;
+
+        if ((mdctx = EVP_MD_CTX_new()) == NULL)
+                goto err;
+        if (!EVP_DigestVerifyInit(mdctx, &pctx, sigalg->md(), NULL, pkey))
+                goto err;
+        if (sigalg->flags & SIGALG_FLAG_RSA_PSS) {
+                if (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING))
+                        goto err;
+                if (!EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1))
+                        goto err;
+        }
+        if (!EVP_DigestVerifyUpdate(mdctx, sig_content, sig_content_len))
+                goto err;
+        if (EVP_DigestVerifyFinal(mdctx, CBS_data(&signature),
+            CBS_len(&signature)) <= 0) {
+                /* XXX - send alert. */
+                goto err;
+        }
+
+        ret = 1;
+
+ err:
+        CBB_cleanup(&cbb);
+        EVP_MD_CTX_free(mdctx);
+        free(sig_content);
+
+        return ret;
+}