Disable all TLS session tickets

danielgustafsson · danielgustafsson · commit 1f476bc75376 · 2024-07-26T11:09:45.000+02:00
OpenSSL supports two types of session tickets for TLSv1.3, stateless and stateful. The option we've used only turns off stateless tickets leaving stateful tickets active. Use the new API introduced in 1.1.1 to disable all types of tickets. Backpatch to all supported versions. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Reported-by: Andres Freund <andres@anarazel.de> Discussion: https://postgr.es/m/20240617173803.6alnafnxpiqvlh3g@awork3.anarazel.de Backpatch-through: v12
diff --git a/configure b/configure
@@ -12740,12 +12740,13 @@ fi
 done
 
   # Function introduced in OpenSSL 1.1.1.
-  for ac_func in X509_get_signature_info
+  for ac_func in X509_get_signature_info SSL_CTX_set_num_tickets
 do :
-  ac_fn_c_check_func "$LINENO" "X509_get_signature_info" "ac_cv_func_X509_get_signature_info"
-if test "x$ac_cv_func_X509_get_signature_info" = xyes; then :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_X509_GET_SIGNATURE_INFO 1
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
 _ACEOF
 
 fi
diff --git a/configure.in b/configure.in
@@ -1281,7 +1281,7 @@ if test "$with_openssl" = yes ; then
   # function was removed.
   AC_CHECK_FUNCS([CRYPTO_lock])
   # Function introduced in OpenSSL 1.1.1.
-  AC_CHECK_FUNCS([X509_get_signature_info])
+  AC_CHECK_FUNCS([X509_get_signature_info SSL_CTX_set_num_tickets])
 fi
 
 if test "$with_pam" = yes ; then
diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c
@@ -242,8 +242,20 @@ be_tls_init(bool isServerStart)
 		}
 	}
 
-	/* disallow SSL session tickets */
+	/*
+	 * Disallow SSL session tickets. OpenSSL use both stateful and stateless
+	 * tickets for TLSv1.3, and stateless ticket for TLSv1.2. SSL_OP_NO_TICKET
+	 * is available since 0.9.8f but only turns off stateless tickets. In
+	 * order to turn off stateful tickets we need SSL_CTX_set_num_tickets,
+	 * which is available since OpenSSL 1.1.1. LibreSSL 3.5.4 (from OpenBSD
+	 * 7.1) introduced this API for compatibility, but doesn't support session
+	 * tickets at all so it's a no-op there.
+	 */
+#ifdef HAVE_SSL_CTX_SET_NUM_TICKETS
+	SSL_CTX_set_num_tickets(context, 0);
+#else
 	SSL_CTX_set_options(context, SSL_OP_NO_TICKET);
+#endif
 
 	/* disallow SSL session caching, too */
 	SSL_CTX_set_session_cache_mode(context, SSL_SESS_CACHE_OFF);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
@@ -686,6 +686,9 @@
 /* Define to 1 if you have the `X509_get_signature_nid' function. */
 #undef HAVE_X509_GET_SIGNATURE_NID
 
+/* Define to 1 if you have the `SSL_CTX_set_num_tickets' function. */
+#undef HAVE_SSL_CTX_SET_NUM_TICKETS
+
 /* Define to 1 if the assembler supports X86_64's POPCNTQ instruction. */
 #undef HAVE_X86_64_POPCNTQ
 
