Rewrite session ticket TLS extension handling using CBB/CBS and the new

extension framework.

ok jsing@ beck@

3 files changed, 145 insertions, 65 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index c050224c70..1813d46f41 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.6 2017/08/11 20:14:13 doug Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.7 2017/08/12 21:17:03 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -492,6 +492,131 @@ tlsext_sni_serverhello_parse(SSL *s, CBS *cbs, int *alert)
         return 1;
 }
 
+/*
+ * SessionTicket extension - RFC 5077 section 3.2
+ */
+int
+tlsext_sessionticket_clienthello_needs(SSL *s)
+{
+        /*
+         * Send session ticket extension when enabled and not overridden.
+         *
+         * When renegotiating, send an empty session ticket to indicate support.
+         */
+        if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0)
+                return 0;
+
+        if (s->internal->new_session)
+                return 1;
+
+        if (s->internal->tlsext_session_ticket != NULL &&
+            s->internal->tlsext_session_ticket->data == NULL)
+                return 0;
+
+        return 1;
+}
+
+int
+tlsext_sessionticket_clienthello_build(SSL *s, CBB *cbb)
+{
+        /*
+         * Signal that we support session tickets by sending an empty
+         * extension when renegotiating or no session found.
+         */
+        if (s->internal->new_session || s->session == NULL)
+                return 1;
+
+        if (s->session->tlsext_tick != NULL) {
+                /* Attempt to resume with an existing session ticket */
+                if (!CBB_add_bytes(cbb, s->session->tlsext_tick,
+                    s->session->tlsext_ticklen))
+                        return 0;
+
+        } else if (s->internal->tlsext_session_ticket != NULL) {
+                /*
+                 * Attempt to resume with a custom provided session ticket set
+                 * by SSL_set_session_ticket_ext().
+                 */
+                if (s->internal->tlsext_session_ticket->length > 0) {
+                        size_t ticklen = s->internal->tlsext_session_ticket->length;
+
+                        if ((s->session->tlsext_tick = malloc(ticklen)) == NULL)
+                                return 0;
+                        memcpy(s->session->tlsext_tick,
+                            s->internal->tlsext_session_ticket->data,
+                            ticklen);
+                        s->session->tlsext_ticklen = ticklen;
+
+                        if (!CBB_add_bytes(cbb, s->session->tlsext_tick,
+                            s->session->tlsext_ticklen))
+                                return 0;
+                }
+        }
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
+}
+
+int
+tlsext_sessionticket_clienthello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        if (s->internal->tls_session_ticket_ext_cb) {
+                if (!s->internal->tls_session_ticket_ext_cb(s, CBS_data(cbs),
+                    (int)CBS_len(cbs),
+                    s->internal->tls_session_ticket_ext_cb_arg)) {
+                        *alert = TLS1_AD_INTERNAL_ERROR;
+                        return 0;
+                }
+        }
+
+        /* We need to signal that this was processed fully */
+        if (!CBS_skip(cbs, CBS_len(cbs))) {
+                *alert = TLS1_AD_INTERNAL_ERROR;
+                return 0;
+        }
+
+        return 1;
+}
+
+int
+tlsext_sessionticket_serverhello_needs(SSL *s)
+{
+        return (s->internal->tlsext_ticket_expected &&
+            !(SSL_get_options(s) & SSL_OP_NO_TICKET));
+}
+
+int
+tlsext_sessionticket_serverhello_build(SSL *s, CBB *cbb)
+{
+        /* Empty ticket */
+
+        return 1;
+}
+
+int
+tlsext_sessionticket_serverhello_parse(SSL *s, CBS *cbs, int *alert)
+{
+        if (s->internal->tls_session_ticket_ext_cb) {
+                if (!s->internal->tls_session_ticket_ext_cb(s, CBS_data(cbs),
+                    (int)CBS_len(cbs),
+                    s->internal->tls_session_ticket_ext_cb_arg)) {
+                        *alert = TLS1_AD_INTERNAL_ERROR;
+                        return 0;
+                }
+        }
+
+        if ((SSL_get_options(s) & SSL_OP_NO_TICKET) != 0 || CBS_len(cbs) > 0) {
+                *alert = TLS1_AD_UNSUPPORTED_EXTENSION;
+                return 0;
+        }
+
+        s->internal->tlsext_ticket_expected = 1;
+
+        return 1;
+}
+
 struct tls_extension {
         uint16_t type;
         int (*clienthello_needs)(SSL *s);
@@ -539,6 +664,15 @@ static struct tls_extension tls_extensions[] = {
                 .serverhello_build = tlsext_ec_serverhello_build,
                 .serverhello_parse = tlsext_ec_serverhello_parse,
         },
+        {
+                .type = TLSEXT_TYPE_session_ticket,
+                .clienthello_needs = tlsext_sessionticket_clienthello_needs,
+                .clienthello_build = tlsext_sessionticket_clienthello_build,
+                .clienthello_parse = tlsext_sessionticket_clienthello_parse,
+                .serverhello_needs = tlsext_sessionticket_serverhello_needs,
+                .serverhello_build = tlsext_sessionticket_serverhello_build,
+                .serverhello_parse = tlsext_sessionticket_serverhello_parse,
+        },
 };
 
 #define N_TLS_EXTENSIONS (sizeof(tls_extensions) / sizeof(*tls_extensions))
diff --git a/src/lib/libssl/ssl_tlsext.h b/src/lib/libssl/ssl_tlsext.h
index 38f8ffaa65..1e701e941a 100644
--- a/src/lib/libssl/ssl_tlsext.h
+++ b/src/lib/libssl/ssl_tlsext.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.h,v 1.5 2017/08/11 20:14:13 doug Exp $ */
+/* $OpenBSD: ssl_tlsext.h,v 1.6 2017/08/12 21:17:03 doug Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -44,6 +44,12 @@ int tlsext_ecpf_serverhello_needs(SSL *s);
 int tlsext_ecpf_serverhello_build(SSL *s, CBB *cbb);
 int tlsext_ecpf_serverhello_parse(SSL *s, CBS *cbs, int *alert);
 
+int tlsext_sessionticket_clienthello_needs(SSL *s);
+int tlsext_sessionticket_clienthello_build(SSL *s, CBB *cbb);
+int tlsext_sessionticket_clienthello_parse(SSL *s, CBS *cbs, int *alert);
+int tlsext_sessionticket_serverhello_needs(SSL *s);
+int tlsext_sessionticket_serverhello_build(SSL *s, CBB *cbb);
+int tlsext_sessionticket_serverhello_parse(SSL *s, CBS *cbs, int *alert);
 
 int tlsext_clienthello_build(SSL *s, CBB *cbb);
 int tlsext_clienthello_parse_one(SSL *s, CBS *cbs, uint16_t tlsext_type,
diff --git a/src/lib/libssl/t1_lib.c b/src/lib/libssl/t1_lib.c
index 911e8d3f4e..63d401c337 100644
--- a/src/lib/libssl/t1_lib.c
+++ b/src/lib/libssl/t1_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: t1_lib.c,v 1.128 2017/08/12 21:03:08 jsing Exp $ */
+/* $OpenBSD: t1_lib.c,v 1.129 2017/08/12 21:17:03 doug Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -690,39 +690,6 @@ ssl_add_clienthello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
                 return NULL;
         ret += len;
 
-        if (!(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
-                int ticklen;
-                if (!s->internal->new_session && s->session && s->session->tlsext_tick)
-                        ticklen = s->session->tlsext_ticklen;
-                else if (s->session && s->internal->tlsext_session_ticket &&
-                    s->internal->tlsext_session_ticket->data) {
-                        ticklen = s->internal->tlsext_session_ticket->length;
-                        s->session->tlsext_tick = malloc(ticklen);
-                        if (!s->session->tlsext_tick)
-                                return NULL;
-                        memcpy(s->session->tlsext_tick,
-                            s->internal->tlsext_session_ticket->data, ticklen);
-                        s->session->tlsext_ticklen = ticklen;
-                } else
-                        ticklen = 0;
-                if (ticklen == 0 && s->internal->tlsext_session_ticket &&
-                    s->internal->tlsext_session_ticket->data == NULL)
-                        goto skip_ext;
-                /* Check for enough room 2 for extension type, 2 for len
-                 * rest for ticket
-                 */
-                if ((size_t)(limit - ret) < 4 + ticklen)
-                        return NULL;
-                s2n(TLSEXT_TYPE_session_ticket, ret);
-
-                s2n(ticklen, ret);
-                if (ticklen) {
-                        memcpy(ret, s->session->tlsext_tick, ticklen);
-                        ret += ticklen;
-                }
-        }
-skip_ext:
-
         if (TLS1_get_client_version(s) >= TLS1_2_VERSION) {
                 if ((size_t)(limit - ret) < sizeof(tls12_sigalgs) + 6)
                         return NULL;
@@ -884,15 +851,6 @@ ssl_add_serverhello_tlsext(SSL *s, unsigned char *p, unsigned char *limit)
          * extension.
          */
 
-        if (s->internal->tlsext_ticket_expected &&
-            !(SSL_get_options(s) & SSL_OP_NO_TICKET)) {
-                if ((size_t)(limit - ret) < 4)
-                        return NULL;
-
-                s2n(TLSEXT_TYPE_session_ticket, ret);
-                s2n(0, ret);
-        }
-
         if (s->internal->tlsext_status_expected) {
                 if ((size_t)(limit - ret) < 4)
                         return NULL;
@@ -1068,13 +1026,7 @@ ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
                 if (!tlsext_clienthello_parse_one(s, &cbs, type, al))
                         return 0;
 
-                if (type == TLSEXT_TYPE_session_ticket) {
-                        if (s->internal->tls_session_ticket_ext_cb &&
-                            !s->internal->tls_session_ticket_ext_cb(s, data, size, s->internal->tls_session_ticket_ext_cb_arg)) {
-                                *al = TLS1_AD_INTERNAL_ERROR;
-                                return 0;
-                        }
-                } else if (type == TLSEXT_TYPE_signature_algorithms) {
+                if (type == TLSEXT_TYPE_signature_algorithms) {
                         int dsize;
                         if (sigalg_seen || size < 2) {
                                 *al = SSL_AD_DECODE_ERROR;
@@ -1277,19 +1229,7 @@ ssl_parse_serverhello_tlsext(SSL *s, unsigned char **p, size_t n, int *al)
                 if (!tlsext_serverhello_parse_one(s, &cbs, type, al))
                         return 0;
 
-                if (type == TLSEXT_TYPE_session_ticket) {
-                        if (s->internal->tls_session_ticket_ext_cb &&
-                            !s->internal->tls_session_ticket_ext_cb(s, data, size, s->internal->tls_session_ticket_ext_cb_arg)) {
-                                *al = TLS1_AD_INTERNAL_ERROR;
-                                return 0;
-                        }
-                        if ((SSL_get_options(s) & SSL_OP_NO_TICKET) || (size > 0)) {
-                                *al = TLS1_AD_UNSUPPORTED_EXTENSION;
-                                return 0;
-                        }
-                        s->internal->tlsext_ticket_expected = 1;
-                }
-                else if (type == TLSEXT_TYPE_status_request &&
+                if (type == TLSEXT_TYPE_status_request &&
                     s->version != DTLS1_VERSION) {
                         /* MUST be empty and only sent if we've requested
                          * a status request message.