Change Post Handshake auth so that it is opt-in

Having post handshake auth automatically switched on breaks some
applications written for TLSv1.2. This changes things so that an explicit
function call is required for a client to indicate support for
post-handshake auth.

Fixes #6933.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6938)

15 files changed, 73 insertions, 66 deletions

diff --git a/apps/s_client.c b/apps/s_client.c
index 8f9ad9ddcf..dcaa10cf44 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -595,7 +595,7 @@ typedef enum OPTION_choice {
     OPT_CT, OPT_NOCT, OPT_CTLOG_FILE,
 #endif
     OPT_DANE_TLSA_RRDATA, OPT_DANE_EE_NO_NAME,
-    OPT_FORCE_PHA,
+    OPT_ENABLE_PHA,
     OPT_R_ENUM
 } OPTION_CHOICE;
 
@@ -786,7 +786,7 @@ const OPTIONS s_client_options[] = {
 #endif
     {"keylogfile", OPT_KEYLOG_FILE, '>', "Write TLS secrets to file"},
     {"early_data", OPT_EARLY_DATA, '<', "File to send as early data"},
-    {"force_pha", OPT_FORCE_PHA, '-', "Force-enable post-handshake-authentication"},
+    {"enable_pha", OPT_ENABLE_PHA, '-', "Enable post-handshake-authentication"},
     {NULL, OPT_EOF, 0x00, NULL}
 };
 
@@ -975,7 +975,7 @@ int s_client_main(int argc, char **argv)
     int isdtls = 0;
 #endif
     char *psksessf = NULL;
-    int force_pha = 0;
+    int enable_pha = 0;
 
     FD_ZERO(&readfds);
     FD_ZERO(&writefds);
@@ -1492,8 +1492,8 @@ int s_client_main(int argc, char **argv)
         case OPT_EARLY_DATA:
             early_data_file = opt_arg();
             break;
-        case OPT_FORCE_PHA:
-            force_pha = 1;
+        case OPT_ENABLE_PHA:
+            enable_pha = 1;
             break;
         }
     }
@@ -1944,8 +1944,8 @@ int s_client_main(int argc, char **argv)
     if (con == NULL)
         goto end;
 
-    if (force_pha)
-        SSL_force_post_handshake_auth(con);
+    if (enable_pha)
+        SSL_set_post_handshake_auth(con, 1);
 
     if (sess_in != NULL) {
         SSL_SESSION *sess;
diff --git a/doc/man1/s_client.pod b/doc/man1/s_client.pod
index 80152e1ba4..fa5cb0a92d 100644
--- a/doc/man1/s_client.pod
+++ b/doc/man1/s_client.pod
@@ -134,7 +134,7 @@ B<openssl> B<s_client>
 [B<-ctlogfile>]
 [B<-keylogfile file>]
 [B<-early_data file>]
-[B<-force_pha>]
+[B<-enable_pha>]
 [B<target>]
 
 =head1 DESCRIPTION
@@ -700,10 +700,10 @@ Reads the contents of the specified file and attempts to send it as early data
 to the server. This will only work with resumed sessions that support early
 data and when the server accepts the early data.
 
-=item B<-force_pha>
+=item B<-enable_pha>
 
-For TLSv1.3 only, always send the Post-Handshake Authentication extension,
-whether or not a certificate has been provided via B<-cert>.
+For TLSv1.3 only, send the Post-Handshake Authentication extension. This will
+happen whether or not a certificate has been provided via B<-cert>.
 
 =item B<[target]>
 
diff --git a/doc/man3/SSL_CTX_set_verify.pod b/doc/man3/SSL_CTX_set_verify.pod
index 7165547933..173f006eb6 100644
--- a/doc/man3/SSL_CTX_set_verify.pod
+++ b/doc/man3/SSL_CTX_set_verify.pod
@@ -7,7 +7,7 @@ SSL_CTX_set_verify, SSL_set_verify,
 SSL_CTX_set_verify_depth, SSL_set_verify_depth,
 SSL_verify_cb,
 SSL_verify_client_post_handshake,
-SSL_force_post_handshake_auth
+SSL_set_post_handshake_auth
 - set peer certificate verification parameters
 
 =head1 SYNOPSIS
@@ -24,7 +24,7 @@ SSL_force_post_handshake_auth
  void SSL_set_verify_depth(SSL *ssl, int depth);
 
  int SSL_verify_client_post_handshake(SSL *ssl);
- void SSL_force_post_handshake_auth(SSL *ssl);
+ void SSL_set_post_handshake_auth(SSL *ssl, int val);
 
 =head1 DESCRIPTION
 
@@ -48,11 +48,12 @@ verification that shall be allowed for B<ctx>.
 SSL_set_verify_depth() sets the maximum B<depth> for the certificate chain
 verification that shall be allowed for B<ssl>.
 
-SSL_force_post_handshake_auth() forces the Post-Handshake Authentication
-extension to be added to the ClientHello regardless of certificate configuration
-at the time of the initial handshake, such that post-handshake authentication
-can be requested by the server. A certificate callback will need to be set via
-SSL_CTX_set_client_cert_cb() if no certificate is provided at initialization.
+SSL_set_post_handshake_auth() enables the Post-Handshake Authentication
+extension to be added to the ClientHello such that post-handshake authentication
+can be requested by the server. If B<val> is 0 then the extension is not sent,
+otherwise it is. By default the extension is not sent. A certificate callback
+will need to be set via SSL_CTX_set_client_cert_cb() if no certificate is
+provided at initialization.
 
 SSL_verify_client_post_handshake() causes a CertificateRequest message to be
 sent by a server on the given B<ssl> connection. The SSL_VERIFY_PEER flag must
@@ -341,7 +342,7 @@ L<CRYPTO_get_ex_new_index(3)>
 =head1 HISTORY
 
 The SSL_VERIFY_POST_HANDSHAKE option, and the SSL_verify_client_post_handshake()
-and SSL_force_post_handshake_auth() functions were added in OpenSSL 1.1.1.
+and SSL_set_post_handshake_auth() functions were added in OpenSSL 1.1.1.
 
 =head1 COPYRIGHT
 
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 155d6515e1..b61119cc18 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1898,7 +1898,7 @@ int SSL_renegotiate_abbreviated(SSL *s);
 __owur int SSL_renegotiate_pending(SSL *s);
 int SSL_shutdown(SSL *s);
 __owur int SSL_verify_client_post_handshake(SSL *s);
-void SSL_force_post_handshake_auth(SSL *s);
+void SSL_set_post_handshake_auth(SSL *s, int val);
 
 __owur const SSL_METHOD *SSL_CTX_get_ssl_method(SSL_CTX *ctx);
 __owur const SSL_METHOD *SSL_get_ssl_method(SSL *s);
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index a486356c2a..89570fbe3a 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -5455,9 +5455,9 @@ int SSL_stateless(SSL *s)
     return -1;
 }
 
-void SSL_force_post_handshake_auth(SSL *ssl)
+void SSL_set_post_handshake_auth(SSL *ssl, int val)
 {
-    ssl->pha_forced = 1;
+    ssl->pha_enabled = val;
 }
 
 int SSL_verify_client_post_handshake(SSL *ssl)
diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index 6d6404ba3d..0d98110480 100644
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -1391,7 +1391,7 @@ struct ssl_st {
     int key_update;
     /* Post-handshake authentication state */
     SSL_PHA_STATE post_handshake_auth;
-    int pha_forced;
+    int pha_enabled;
     uint8_t* pha_context;
     size_t pha_context_len;
     int certreqs_sent;
diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index 86d6189ea1..2d5b60a737 100644
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -1193,23 +1193,8 @@ EXT_RETURN tls_construct_ctos_post_handshake_auth(SSL *s, WPACKET *pkt,
                                                   X509 *x, size_t chainidx)
 {
 #ifndef OPENSSL_NO_TLS1_3
-    if (!s->pha_forced) {
-        int i, n = 0;
-
-        /* check for cert, if present, we can do post-handshake auth */
-        if (s->cert == NULL)
-            return EXT_RETURN_NOT_SENT;
-
-        for (i = 0; i < SSL_PKEY_NUM; i++) {
-            if (s->cert->pkeys[i].x509 != NULL
-                    && s->cert->pkeys[i].privatekey != NULL)
-                n++;
-        }
-
-        /* no identity certificates, so no extension */
-        if (n == 0)
-            return EXT_RETURN_NOT_SENT;
-    }
+    if (!s->pha_enabled)
+        return EXT_RETURN_NOT_SENT;
 
     /* construct extension - 0 length, no contents */
     if (!WPACKET_put_bytes_u16(pkt, TLSEXT_TYPE_post_handshake_auth)
diff --git a/test/handshake_helper.c b/test/handshake_helper.c
index c40a0e7c92..a5b8d8007a 100644
--- a/test/handshake_helper.c
+++ b/test/handshake_helper.c
@@ -726,8 +726,8 @@ static void configure_handshake_ssl(SSL *server, SSL *client,
     if (extra->client.servername != SSL_TEST_SERVERNAME_NONE)
         SSL_set_tlsext_host_name(client,
                                  ssl_servername_name(extra->client.servername));
-    if (extra->client.force_pha)
-        SSL_force_post_handshake_auth(client);
+    if (extra->client.enable_pha)
+        SSL_set_post_handshake_auth(client, 1);
 }
 
 /* The status for each connection phase. */
diff --git a/test/recipes/70-test_tls13messages.t b/test/recipes/70-test_tls13messages.t
index 35f36b6c33..be6a2db5d6 100644
--- a/test/recipes/70-test_tls13messages.t
+++ b/test/recipes/70-test_tls13messages.t
@@ -214,7 +214,7 @@ SKIP: {
 
 #Test 6: A client auth handshake
 $proxy->clear();
-$proxy->clientflags("-cert ".srctop_file("apps", "server.pem"));
+$proxy->clientflags("-enable_pha -cert ".srctop_file("apps", "server.pem"));
 $proxy->serverflags("-Verify 5");
 $proxy->start();
 checkhandshake($proxy, checkhandshake::CLIENT_AUTH_HANDSHAKE,
diff --git a/test/ssl-tests/26-tls13_client_auth.conf b/test/ssl-tests/26-tls13_client_auth.conf
index 55361dde73..9c42391906 100644
--- a/test/ssl-tests/26-tls13_client_auth.conf
+++ b/test/ssl-tests/26-tls13_client_auth.conf
@@ -299,6 +299,10 @@ ExpectedClientSignHash = SHA256
 ExpectedClientSignType = RSA-PSS
 ExpectedResult = Success
 HandshakeMode = PostHandshakeAuth
+client = 8-client-auth-TLSv1.3-require-post-handshake-client-extra
+
+[8-client-auth-TLSv1.3-require-post-handshake-client-extra]
+EnablePHA = Yes
 
 
 # ===========================================================
@@ -337,6 +341,10 @@ ExpectedClientSignHash = SHA256
 ExpectedClientSignType = RSA-PSS
 ExpectedResult = Success
 HandshakeMode = PostHandshakeAuth
+client = 9-client-auth-TLSv1.3-require-non-empty-names-post-handshake-client-extra
+
+[9-client-auth-TLSv1.3-require-non-empty-names-post-handshake-client-extra]
+EnablePHA = Yes
 
 
 # ===========================================================
@@ -369,6 +377,10 @@ VerifyMode = Peer
 ExpectedResult = ServerFail
 ExpectedServerAlert = UnknownCA
 HandshakeMode = PostHandshakeAuth
+client = 10-client-auth-TLSv1.3-noroot-post-handshake-client-extra
+
+[10-client-auth-TLSv1.3-noroot-post-handshake-client-extra]
+EnablePHA = Yes
 
 
 # ===========================================================
@@ -401,7 +413,7 @@ HandshakeMode = PostHandshakeAuth
 client = 11-client-auth-TLSv1.3-request-force-client-post-handshake-client-extra
 
 [11-client-auth-TLSv1.3-request-force-client-post-handshake-client-extra]
-ForcePHA = Yes
+EnablePHA = Yes
 
 
 # ===========================================================
@@ -471,6 +483,6 @@ client = 13-client-auth-TLSv1.3-request-force-both-post-handshake-client-extra
 ForcePHA = Yes
 
 [13-client-auth-TLSv1.3-request-force-both-post-handshake-client-extra]
-ForcePHA = Yes
+EnablePHA = Yes
 
 
diff --git a/test/ssl-tests/26-tls13_client_auth.conf.in b/test/ssl-tests/26-tls13_client_auth.conf.in
index e53cda2304..018dd825be 100644
--- a/test/ssl-tests/26-tls13_client_auth.conf.in
+++ b/test/ssl-tests/26-tls13_client_auth.conf.in
@@ -176,6 +176,9 @@ our @tests = (
             "MaxProtocol" => "TLSv1.3",
             "Certificate" => test_pem("ee-client-chain.pem"),
             "PrivateKey" => test_pem("ee-key.pem"),
+            extra => {
+                "EnablePHA" => "Yes",
+            },
         },
         test => {
             "ExpectedResult" => "Success",
@@ -201,6 +204,9 @@ our @tests = (
             "MaxProtocol" => "TLSv1.3",
             "Certificate" => test_pem("ee-client-chain.pem"),
             "PrivateKey" => test_pem("ee-key.pem"),
+            extra => {
+                "EnablePHA" => "Yes",
+            },
         },
         test => {
             "ExpectedResult" => "Success",
@@ -223,6 +229,9 @@ our @tests = (
             "MaxProtocol" => "TLSv1.3",
             "Certificate" => test_pem("ee-client-chain.pem"),
             "PrivateKey" => test_pem("ee-key.pem"),
+            extra => {
+                "EnablePHA" => "Yes",
+            },
         },
         test => {
             "ExpectedResult" => "ServerFail",
@@ -240,9 +249,9 @@ our @tests = (
         client => {
             "MinProtocol" => "TLSv1.3",
             "MaxProtocol" => "TLSv1.3",
-	    extra => {
-		"ForcePHA" => "Yes",
-	    },
+            extra => {
+                "EnablePHA" => "Yes",
+            },
         },
         test => {
             "ExpectedResult" => "Success",
@@ -255,9 +264,9 @@ our @tests = (
             "MinProtocol" => "TLSv1.3",
             "MaxProtocol" => "TLSv1.3",
             "VerifyMode" => "RequestPostHandshake",
-	    extra => {
-		"ForcePHA" => "Yes",
-	    },
+            extra => {
+                "ForcePHA" => "Yes",
+            },
         },
         client => {
             "MinProtocol" => "TLSv1.3",
@@ -274,16 +283,16 @@ our @tests = (
             "MinProtocol" => "TLSv1.3",
             "MaxProtocol" => "TLSv1.3",
             "VerifyMode" => "RequestPostHandshake",
-	    extra => {
-		"ForcePHA" => "Yes",
-	    },
+            extra => {
+                "ForcePHA" => "Yes",
+            },
         },
         client => {
             "MinProtocol" => "TLSv1.3",
             "MaxProtocol" => "TLSv1.3",
-	    extra => {
-		"ForcePHA" => "Yes",
-	    },
+            extra => {
+                "EnablePHA" => "Yes",
+            },
         },
         test => {
             "ExpectedResult" => "Success",
diff --git a/test/ssl_test_ctx.c b/test/ssl_test_ctx.c
index cb4b8606e2..753338530d 100644
--- a/test/ssl_test_ctx.c
+++ b/test/ssl_test_ctx.c
@@ -629,9 +629,9 @@ __owur static int parse_expected_client_ca_names(SSL_TEST_CTX *test_ctx,
 
 IMPLEMENT_SSL_TEST_STRING_OPTION(SSL_TEST_CTX, test, expected_cipher)
 
-/* Client and Server ForcePHA */
+/* Client and Server PHA */
 
-IMPLEMENT_SSL_TEST_BOOL_OPTION(SSL_TEST_CLIENT_CONF, client, force_pha)
+IMPLEMENT_SSL_TEST_BOOL_OPTION(SSL_TEST_CLIENT_CONF, client, enable_pha)
 IMPLEMENT_SSL_TEST_BOOL_OPTION(SSL_TEST_SERVER_CONF, server, force_pha)
 
 /* Known test options and their corresponding parse methods. */
@@ -689,7 +689,7 @@ static const ssl_test_client_option ssl_test_client_options[] = {
     { "SRPUser", &parse_client_srp_user },
     { "SRPPassword", &parse_client_srp_password },
     { "MaxFragmentLenExt", &parse_max_fragment_len_mode },
-    { "ForcePHA", &parse_client_force_pha },
+    { "EnablePHA", &parse_client_enable_pha },
 };
 
 /* Nested server options. */
diff --git a/test/ssl_test_ctx.h b/test/ssl_test_ctx.h
index e26c207657..86d227d865 100644
--- a/test/ssl_test_ctx.h
+++ b/test/ssl_test_ctx.h
@@ -108,8 +108,8 @@ typedef struct {
     char *reneg_ciphers;
     char *srp_user;
     char *srp_password;
-    /* Forced PHA */
-    int force_pha;
+    /* PHA enabled */
+    int enable_pha;
 } SSL_TEST_CLIENT_CONF;
 
 typedef struct {
diff --git a/test/sslapitest.c b/test/sslapitest.c
index c65bf59ffd..81761f2f65 100644
--- a/test/sslapitest.c
+++ b/test/sslapitest.c
@@ -1270,7 +1270,7 @@ static int check_resumption(int idx, SSL_CTX *sctx, SSL_CTX *cctx, int succ)
                 || !TEST_true(SSL_set_session(clientssl, sesscache[i])))
             goto end;
 
-        SSL_force_post_handshake_auth(clientssl);
+        SSL_set_post_handshake_auth(clientssl, 1);
 
         if (!TEST_true(create_ssl_connection(serverssl, clientssl,
                                                     SSL_ERROR_NONE)))
@@ -1377,7 +1377,7 @@ static int test_tickets(int stateful, int idx)
                                           &clientssl, NULL, NULL)))
         goto end;
 
-    SSL_force_post_handshake_auth(clientssl);
+    SSL_set_post_handshake_auth(clientssl, 1);
 
     if (!TEST_true(create_ssl_connection(serverssl, clientssl,
                                                 SSL_ERROR_NONE))
@@ -4336,7 +4336,7 @@ static int test_pha_key_update(void)
                                       NULL, NULL)))
         goto end;
 
-    SSL_force_post_handshake_auth(clientssl);
+    SSL_set_post_handshake_auth(clientssl, 1);
 
     if (!TEST_true(create_ssl_connection(serverssl, clientssl,
                                          SSL_ERROR_NONE)))
diff --git a/util/libssl.num b/util/libssl.num
index 9b6d266144..521637f098 100644
--- a/util/libssl.num
+++ b/util/libssl.num
@@ -475,7 +475,7 @@ SSL_set_tlsext_max_fragment_length      475	1_1_1	EXIST::FUNCTION:
 SSL_SESSION_get_max_fragment_length     476	1_1_1	EXIST::FUNCTION:
 SSL_stateless                           477	1_1_1	EXIST::FUNCTION:
 SSL_verify_client_post_handshake        478	1_1_1	EXIST::FUNCTION:
-SSL_force_post_handshake_auth           479	1_1_1	EXIST::FUNCTION:
+SSL_set_post_handshake_auth             479	1_1_1	EXIST::FUNCTION:
 SSL_export_keying_material_early        480	1_1_1	EXIST::FUNCTION:
 SSL_CTX_use_cert_and_key                481	1_1_1	EXIST::FUNCTION:
 SSL_use_cert_and_key                    482	1_1_1	EXIST::FUNCTION: