Add checks to ensure we do not initiate or negotiate handshakes with

versions below the minimum required by the security level.

input & ok jsing

5 files changed, 34 insertions, 7 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index d49d8ef056..604b55277c 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.148 2022/06/29 08:34:04 tb Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.149 2022/06/30 11:17:49 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -221,6 +221,13 @@ ssl3_connect(SSL *s)
                                 goto end;
                         }
 
+                        if (!ssl_security_version(s,
+                            s->s3->hs.our_min_tls_version)) {
+                                SSLerror(s, SSL_R_VERSION_TOO_LOW);
+                                ret = -1;
+                                goto end;
+                        }
+
                         if (!ssl3_setup_init_buffer(s)) {
                                 ret = -1;
                                 goto end;
diff --git a/src/lib/libssl/ssl_locl.h b/src/lib/libssl/ssl_locl.h
index b46e37f5eb..d466b59642 100644
--- a/src/lib/libssl/ssl_locl.h
+++ b/src/lib/libssl/ssl_locl.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_locl.h,v 1.407 2022/06/29 21:18:04 tb Exp $ */
+/* $OpenBSD: ssl_locl.h,v 1.408 2022/06/30 11:17:49 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1301,6 +1301,7 @@ int ssl_ctx_security(const SSL_CTX *ctx, int op, int bits, int nid,
 int ssl_security(const SSL *ssl, int op, int bits, int nid, void *other);
 int ssl_ctx_security_dh(const SSL_CTX *ctx, DH *dh);
 int ssl_security_dh(const SSL *ssl, DH *dh);
+int ssl_security_version(const SSL *ssl, int version);
 int ssl_security_cert(const SSL_CTX *ctx, const SSL *ssl, X509 *x509,
     int is_peer, int *out_error);
 int ssl_security_cert_chain(const SSL *ssl, STACK_OF(X509) *sk,
diff --git a/src/lib/libssl/ssl_seclevel.c b/src/lib/libssl/ssl_seclevel.c
index b174f57f0c..2fe6e3f222 100644
--- a/src/lib/libssl/ssl_seclevel.c
+++ b/src/lib/libssl/ssl_seclevel.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: ssl_seclevel.c,v 1.11 2022/06/30 07:09:45 tb Exp $ */
+/*      $OpenBSD: ssl_seclevel.c,v 1.12 2022/06/30 11:17:49 tb Exp $ */
 /*
  * Copyright (c) 2020 Theo Buehler <tb@openbsd.org>
  *
@@ -233,6 +233,12 @@ ssl_security(const SSL *ssl, int op, int bits, int nid, void *other)
 }
 
 int
+ssl_security_version(const SSL *ssl, int tls_version)
+{
+        return ssl_security(ssl, SSL_SECOP_VERSION, 0, tls_version, NULL);
+}
+
+int
 ssl_ctx_security_dh(const SSL_CTX *ctx, DH *dh)
 {
 #if defined(LIBRESSL_HAS_SECURITY_LEVEL)
diff --git a/src/lib/libssl/ssl_srvr.c b/src/lib/libssl/ssl_srvr.c
index e37f9cfdb7..8f110831e4 100644
--- a/src/lib/libssl/ssl_srvr.c
+++ b/src/lib/libssl/ssl_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_srvr.c,v 1.145 2022/06/29 08:27:51 tb Exp $ */
+/* $OpenBSD: ssl_srvr.c,v 1.146 2022/06/30 11:17:50 tb Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -223,6 +223,13 @@ ssl3_accept(SSL *s)
                                 goto end;
                         }
 
+                        if (!ssl_security_version(s,
+                            s->s3->hs.our_min_tls_version)) {
+                                SSLerror(s, SSL_R_VERSION_TOO_LOW);
+                                ret = -1;
+                                goto end;
+                        }
+
                         if (!ssl3_setup_init_buffer(s)) {
                                 ret = -1;
                                 goto end;
diff --git a/src/lib/libssl/ssl_versions.c b/src/lib/libssl/ssl_versions.c
index 4069670dc9..06e26b8059 100644
--- a/src/lib/libssl/ssl_versions.c
+++ b/src/lib/libssl/ssl_versions.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_versions.c,v 1.22 2022/02/05 14:54:10 jsing Exp $ */
+/* $OpenBSD: ssl_versions.c,v 1.23 2022/06/30 11:17:50 tb Exp $ */
 /*
  * Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
  *
@@ -329,6 +329,9 @@ ssl_max_shared_version(SSL *s, uint16_t peer_ver, uint16_t *max_ver)
                         return 0;
         }
 
+        if (!ssl_security_version(s, shared_version))
+                return 0;
+
         *max_ver = shared_version;
 
         return 1;
@@ -352,8 +355,11 @@ ssl_check_version_from_server(SSL *s, uint16_t server_version)
             &max_tls_version))
                 return 0;
 
-        return (server_tls_version >= min_tls_version &&
-            server_tls_version <= max_tls_version);
+        if (server_tls_version < min_tls_version ||
+            server_tls_version > max_tls_version)
+                return 0;
+
+        return ssl_security_version(s, server_tls_version);
 }
 
 int