Harden SSL_set_session_ticket_ext and add docs

Reviewed-by: Matt Caswell <matt@openssl.foundation>
Reviewed-by: Tomas Mraz <tomas@openssl.foundation>
MergeDate: Mon May 18 07:27:55 2026
(Merged from https://github.com/openssl/openssl/pull/31022)

diff --git a/doc/man3/SSL_set_session_secret_cb.pod b/doc/man3/SSL_set_session_secret_cb.pod
index e79d81d40a3ff3de15195aaaff8d69aaf2ae0040..e40479ce1ff3c5f05d41391baab49c849a4d904d 100644 (file)
--- a/doc/man3/SSL_set_session_secret_cb.pod
+++ b/doc/man3/SSL_set_session_secret_cb.pod
@@ -2,8 +2,10 @@
 
 =head1 NAME
 
-SSL_set_session_secret_cb, tls_session_secret_cb_fn
-- set the session secret callback
+SSL_set_session_secret_cb, tls_session_secret_cb_fn,
+SSL_set_session_ticket_ext, SSL_set_session_ticket_ext_cb,
+tls_session_ticket_ext_cb_fn
+- set the session secret and EAP-FAST session ticket extension callbacks
 
 =head1 SYNOPSIS
 
@@ -17,6 +19,15 @@ SSL_set_session_secret_cb, tls_session_secret_cb_fn
                                tls_session_secret_cb_fn session_secret_cb,
                                void *arg);
 
+ typedef int (*tls_session_ticket_ext_cb_fn)(SSL *s, const unsigned char *data,
+                                             int len, void *arg);
+
+ int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len);
+
+ int SSL_set_session_ticket_ext_cb(SSL *s,
+                                   tls_session_ticket_ext_cb_fn cb,
+                                   void *arg);
+
 =head1 DESCRIPTION
 
 SSL_set_session_secret_cb() sets the session secret callback to be used
@@ -44,13 +55,29 @@ server.
 The callback is also supplied with an additional argument in I<arg> which is the
 argument that was provided to the original SSL_set_session_secret_cb() call.
 
+SSL_set_session_ticket_ext() is used on the client-side to set the session ticket
+extension data for EAP-FAST (RFC4851). The I<ext_data> argument is a pointer to
+the extension data, and I<ext_len> is the length of that data. I<ext_len> must
+be between 0 and 65535. If I<ext_data> is NULL, then the session ticket
+extension will not be sent.
+
+SSL_set_session_ticket_ext_cb() is used on the server-side to set a callback
+(I<cb>) that will be called when a session ticket extension is received. The
+callback is supplied with the extension data in I<data> and its length in
+I<len>, as well as the additional argument I<arg> that was provided when the
+callback was set.
+
 =head1 RETURN VALUES
 
-SSL_set_session_secret_cb() returns 1 on success and 0 on failure.
+SSL_set_session_secret_cb(), SSL_set_session_ticket_ext(), and
+SSL_set_session_ticket_ext_cb() return 1 on success and 0 on failure.
+
+If the session secret callback returns 1 then this indicates it has successfully
+set the secret. A return value of 0 indicates that the secret has not been set.
+On the client this will cause an immediate abort of the handshake.
 
-If the callback returns 1 then this indicates it has successfully set the
-secret. A return value of 0 indicates that the secret has not been set. On the
-client this will cause an immediate abort of the handshake.
+The session ticket extension callback should return 1 for success. A return value
+of 0 indicates failure and will cause the handshake to abort immediately.
 
 =head1 SEE ALSO
 
@@ -59,7 +86,7 @@ L<SSL_get_session(3)>
 
 =head1 COPYRIGHT
 
-Copyright 2024 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2024-2026 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy

diff --git a/ssl/ssl_sess.c b/ssl/ssl_sess.c
index 82d5d7435256f6ae4382bf6ef044c009255ec548..7892873ecf93ee7e6d0d1074c12e2b1fd275c592 100644 (file)
--- a/ssl/ssl_sess.c
+++ b/ssl/ssl_sess.c
@@ -1172,30 +1172,24 @@ int SSL_set_session_ticket_ext_cb(SSL *s, tls_session_ticket_ext_cb_fn cb,
 int SSL_set_session_ticket_ext(SSL *s, void *ext_data, int ext_len)
 {
     SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL(s);
-
-    if (sc == NULL)
+    if (sc == NULL || ext_len < 0 || ext_len > 0xffff)
         return 0;
-
-    if (sc->version >= TLS1_VERSION) {
-        OPENSSL_free(sc->ext.session_ticket);
-        sc->ext.session_ticket = NULL;
+    OPENSSL_free(sc->ext.session_ticket);
+    if (ext_data != NULL) {
         sc->ext.session_ticket = OPENSSL_malloc(sizeof(TLS_SESSION_TICKET_EXT) + ext_len);
         if (sc->ext.session_ticket == NULL)
             return 0;
-
-        if (ext_data != NULL) {
-            sc->ext.session_ticket->length = ext_len;
-            sc->ext.session_ticket->data = sc->ext.session_ticket + 1;
-            memcpy(sc->ext.session_ticket->data, ext_data, ext_len);
-        } else {
-            sc->ext.session_ticket->length = 0;
-            sc->ext.session_ticket->data = NULL;
-        }
-
-        return 1;
+        sc->ext.session_ticket->length = ext_len;
+        sc->ext.session_ticket->data = sc->ext.session_ticket + 1;
+        memcpy(sc->ext.session_ticket->data, ext_data, ext_len);
+    } else {
+        sc->ext.session_ticket = OPENSSL_malloc(sizeof(TLS_SESSION_TICKET_EXT));
+        if (sc->ext.session_ticket == NULL)
+            return 0;
+        sc->ext.session_ticket->data = NULL;
+        sc->ext.session_ticket->length = 0;
     }
-
-    return 0;
+    return 1;
 }
 
 #ifndef OPENSSL_NO_DEPRECATED_3_4

diff --git a/util/missingssl.txt b/util/missingssl.txt
index 8da9842a0b57da61749ccd65aea7901e10f88afa..0ab346fe5723297425c9cbc32e148536a3a6d544 100644 (file)
--- a/util/missingssl.txt
+++ b/util/missingssl.txt
@@ -25,7 +25,5 @@ SSL_get_peer_finished(3)
 SSL_set_SSL_CTX(3)
 SSL_set_debug(3)
 SSL_set_not_resumable_session_callback(3)
-SSL_set_session_ticket_ext(3)
-SSL_set_session_ticket_ext_cb(3)
 SSL_srp_server_param_with_username(3)
 SSL_test_functions(3)

diff --git a/util/other.syms b/util/other.syms
index dc34638f09363afdb2026554a60f5150115505f2..b61353ff32806a76dccb5541c9c0ad23047c2ce9 100644 (file)
--- a/util/other.syms
+++ b/util/other.syms
@@ -160,6 +160,7 @@ custom_ext_parse_cb                     datatype
 pem_password_cb                         datatype
 ssl_ct_validation_cb                    datatype
 tls_session_secret_cb_fn                datatype
+tls_session_ticket_ext_cb_fn            datatype
 ASYNC_stack_alloc_fn                    datatype
 ASYNC_stack_free_fn                     datatype
 PKCS12_create_cb                        datatype