Implement close-notify and SSL_shutdown() handling for the TLSv1.3 client.

ok beck@ inoguchi@ tb@

3 files changed, 76 insertions, 9 deletions

diff --git a/src/lib/libssl/tls13_internal.h b/src/lib/libssl/tls13_internal.h
index 3ee73782ec..7fee37f5dd 100644
--- a/src/lib/libssl/tls13_internal.h
+++ b/src/lib/libssl/tls13_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_internal.h,v 1.39 2020/01/21 12:08:04 jsing Exp $ */
+/* $OpenBSD: tls13_internal.h,v 1.40 2020/01/22 01:02:28 jsing Exp $ */
 /*
  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -126,6 +126,7 @@ int tls13_record_layer_set_read_traffic_key(struct tls13_record_layer *rl,
     struct tls13_secret *read_key);
 int tls13_record_layer_set_write_traffic_key(struct tls13_record_layer *rl,
     struct tls13_secret *write_key);
+ssize_t tls13_record_layer_send_pending(struct tls13_record_layer *rl);
 ssize_t tls13_record_layer_phh(struct tls13_record_layer *rl, CBS *cbs);
 
 ssize_t tls13_read_handshake_data(struct tls13_record_layer *rl, uint8_t *buf, size_t n);
@@ -181,6 +182,9 @@ struct tls13_ctx {
         struct tls13_handshake_stage handshake_stage;
         int handshake_completed;
 
+        int close_notify_sent;
+        int close_notify_recv;
+
         const EVP_AEAD *aead;
         const EVP_MD *hash;
 
@@ -215,6 +219,7 @@ ssize_t tls13_legacy_wire_write_cb(const void *buf, size_t n, void *arg);
 int tls13_legacy_read_bytes(SSL *ssl, int type, unsigned char *buf, int len,
     int peek);
 int tls13_legacy_write_bytes(SSL *ssl, int type, const void *buf, int len);
+int tls13_legacy_shutdown(SSL *ssl);
 
 /*
  * Message Types - RFC 8446, Section B.3.
diff --git a/src/lib/libssl/tls13_lib.c b/src/lib/libssl/tls13_lib.c
index 451e798cb8..bb749a9b68 100644
--- a/src/lib/libssl/tls13_lib.c
+++ b/src/lib/libssl/tls13_lib.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: tls13_lib.c,v 1.16 2020/01/21 05:19:02 jsing Exp $ */
+/*      $OpenBSD: tls13_lib.c,v 1.17 2020/01/22 01:02:28 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2019 Bob Beck <beck@openbsd.org>
@@ -69,6 +69,7 @@ tls13_alert_received_cb(uint8_t alert_desc, void *arg)
         SSL *s = ctx->ssl;
 
         if (alert_desc == SSL_AD_CLOSE_NOTIFY) {
+                ctx->close_notify_recv = 1;
                 ctx->ssl->internal->shutdown |= SSL_RECEIVED_SHUTDOWN;
                 S3I(ctx->ssl)->warn_alert = alert_desc;
                 return;
@@ -482,3 +483,52 @@ tls13_legacy_write_bytes(SSL *ssl, int type, const void *vbuf, int len)
                 n -= ret;
         }
 }
+
+int
+tls13_legacy_shutdown(SSL *ssl)
+{
+        struct tls13_ctx *ctx = ssl->internal->tls13;
+        uint8_t buf[512]; /* XXX */
+        ssize_t ret;
+
+        /*
+         * We need to return 0 when we have sent a close-notify but have not
+         * yet received one. We return 1 only once we have sent and received
+         * close-notify alerts. All other cases return -1 and set internal
+         * state appropriately.
+         */
+        if (ctx == NULL || ssl->internal->quiet_shutdown) {
+                ssl->internal->shutdown = SSL_SENT_SHUTDOWN | SSL_RECEIVED_SHUTDOWN;
+                return 1;
+        }
+
+        /* Send close notify. */
+        if (!ctx->close_notify_sent) {
+                ctx->close_notify_sent = 1;
+                if ((ret = tls13_send_alert(ctx->rl, SSL_AD_CLOSE_NOTIFY)) < 0)
+                        return tls13_legacy_return_code(ssl, ret);
+        }
+
+        /* Ensure close notify has been sent. */
+        if ((ret = tls13_record_layer_send_pending(ctx->rl)) != TLS13_IO_SUCCESS)
+                return tls13_legacy_return_code(ssl, ret);
+
+        /* Receive close notify. */
+        if (!ctx->close_notify_recv) {
+                /*
+                 * If there is still application data pending then we have no
+                 * option but to discard it here. The application should have
+                 * continued to call SSL_read() instead of SSL_shutdown().
+                 */
+                /* XXX - tls13_drain_application_data()? */
+                if ((ret = tls13_read_application_data(ctx->rl, buf, sizeof(buf))) > 0)
+                        ret = TLS13_IO_WANT_POLLIN;
+                if (ret != TLS13_IO_EOF)
+                        return tls13_legacy_return_code(ssl, ret);
+        }
+
+        if (ctx->close_notify_recv)
+                return 1;
+
+        return 0;
+}
diff --git a/src/lib/libssl/tls13_record_layer.c b/src/lib/libssl/tls13_record_layer.c
index a6b00a83b3..dff5cd2bbe 100644
--- a/src/lib/libssl/tls13_record_layer.c
+++ b/src/lib/libssl/tls13_record_layer.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_record_layer.c,v 1.18 2020/01/21 12:08:04 jsing Exp $ */
+/* $OpenBSD: tls13_record_layer.c,v 1.19 2020/01/22 01:02:28 jsing Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -51,6 +51,8 @@ struct tls13_record_layer {
         /* Pending alert messages. */
         uint8_t *alert_data;
         size_t alert_len;
+        uint8_t alert_level;
+        uint8_t alert_desc;
 
         /* Pending post-handshake handshake messages (RFC 8446, section 4.6). */
         CBS phh_cbs;
@@ -281,12 +283,19 @@ tls13_record_layer_send_alert(struct tls13_record_layer *rl)
         rl->alert_data = NULL;
         rl->alert_len = 0;
 
-        /* XXX - only close write channel when sending close notify. */
-        rl->read_closed = 1;
-        rl->write_closed = 1;
+        if (rl->alert_desc == SSL_AD_CLOSE_NOTIFY) {
+                rl->write_closed = 1;
+                ret = TLS13_IO_SUCCESS;
+        } else if (rl->alert_desc == SSL_AD_USER_CANCELLED) {
+                /* Ignored at the record layer. */
+                ret = TLS13_IO_SUCCESS;
+        } else {
+                rl->read_closed = 1;
+                rl->write_closed = 1;
+                ret = TLS13_IO_SUCCESS; /* XXX - ALERT? */
+        }
 
-        /* XXX - we may want a TLS13_IO_ALERT (or handle as errors). */
-        return TLS13_IO_FAILURE;
+        return ret;
 }
 
 static ssize_t
@@ -314,7 +323,7 @@ tls13_record_layer_send_phh(struct tls13_record_layer *rl)
         return TLS13_IO_SUCCESS;
 }
 
-static ssize_t
+ssize_t
 tls13_record_layer_send_pending(struct tls13_record_layer *rl)
 {
         /*
@@ -354,6 +363,9 @@ tls13_record_layer_alert(struct tls13_record_layer *rl,
         if (!CBB_finish(&cbb, &rl->alert_data, &rl->alert_len))
                 goto err;
 
+        rl->alert_level = alert_level;
+        rl->alert_desc = alert_desc;
+
         return tls13_record_layer_send_pending(rl);
 
  err: