Add -groups option to openssl(1) s_server.

This allows supported EC groups to be configured, which will also control
which TLSv1.3 key shares we'll accept. While here, deprecate the rather
useless -named_curve option, which is effectively the same as -groups with
a single group. Also stop setting a single default group of P-256 via
SSL_CTX_set_tmp_ecdh() - use the library defaults instead.

ok beck@ inoguchi@

1 files changed, 29 insertions, 33 deletions

diff --git a/src/usr.bin/openssl/s_server.c b/src/usr.bin/openssl/s_server.c
index 2026e72942..65cd36c54e 100644
--- a/src/usr.bin/openssl/s_server.c
+++ b/src/usr.bin/openssl/s_server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: s_server.c,v 1.32 2019/10/04 09:47:34 bcook Exp $ */
+/* $OpenBSD: s_server.c,v 1.33 2020/04/19 17:05:55 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -288,9 +288,6 @@ sv_usage(void)
         BIO_printf(bio_err, " -dpass arg    - second private key file pass phrase source\n");
         BIO_printf(bio_err, " -dhparam arg  - DH parameter file to use, in cert file if not specified\n");
         BIO_printf(bio_err, "                 or a default set of parameters is used\n");
-        BIO_printf(bio_err, " -named_curve arg  - Elliptic curve name to use for ephemeral ECDH keys.\n" \
-            "                 Use \"openssl ecparam -list_curves\" for all names\n" \
-            "                 (default is nistp256).\n");
         BIO_printf(bio_err, " -nbio         - Run with non-blocking IO\n");
         BIO_printf(bio_err, " -nbio_test    - test with the non-blocking test bio\n");
         BIO_printf(bio_err, " -crlf         - convert LF from terminal into CRLF\n");
@@ -333,7 +330,8 @@ sv_usage(void)
         BIO_printf(bio_err, "                 not specified (default is %s)\n", TEST_CERT2);
         BIO_printf(bio_err, " -tlsextdebug  - hex dump of all TLS extensions received\n");
         BIO_printf(bio_err, " -no_ticket    - disable use of RFC4507bis session tickets\n");
-        BIO_printf(bio_err," -alpn arg  - set the advertised protocols for the ALPN extension (comma-separated list)\n");
+        BIO_printf(bio_err, " -alpn arg     - set the advertised protocols for the ALPN extension (comma-separated list)\n");
+        BIO_printf(bio_err, " -groups arg   - specify EC groups (colon-separated list)\n");
 #ifndef OPENSSL_NO_SRTP
         BIO_printf(bio_err, " -use_srtp profiles - Offer SRTP key management with a colon-separated profile list\n");
 #endif
@@ -581,6 +579,7 @@ s_server_main(int argc, char *argv[])
         X509 *s_cert2 = NULL;
         tlsextctx tlsextcbp = {NULL, NULL, SSL_TLSEXT_ERR_ALERT_WARNING};
         const char *alpn_in = NULL;
+        const char *groups_in = NULL;
         tlsextalpnctx alpn_ctx = { NULL, 0 };
 
         if (single_execution) {
@@ -656,13 +655,11 @@ s_server_main(int argc, char *argv[])
                         if (--argc < 1)
                                 goto bad;
                         dhfile = *(++argv);
-                }
-                else if (strcmp(*argv, "-named_curve") == 0) {
+                } else if (strcmp(*argv, "-named_curve") == 0) {
                         if (--argc < 1)
                                 goto bad;
                         named_curve = *(++argv);
-                }
-                else if (strcmp(*argv, "-dcertform") == 0) {
+                } else if (strcmp(*argv, "-dcertform") == 0) {
                         if (--argc < 1)
                                 goto bad;
                         s_dcert_format = str2fmt(*(++argv));
@@ -831,6 +828,10 @@ s_server_main(int argc, char *argv[])
                         if (--argc < 1)
                                 goto bad;
                         alpn_in = *(++argv);
+                } else if (strcmp(*argv, "-groups") == 0) {
+                        if (--argc < 1)
+                                goto bad;
+                        groups_in = *(++argv);
                 }
 #ifndef OPENSSL_NO_SRTP
                 else if (strcmp(*argv, "-use_srtp") == 0) {
@@ -1055,6 +1056,14 @@ s_server_main(int argc, char *argv[])
         if (alpn_ctx.data)
                 SSL_CTX_set_alpn_select_cb(ctx, alpn_cb, &alpn_ctx);
 
+        if (groups_in != NULL) {
+                if (SSL_CTX_set1_groups_list(ctx, groups_in) != 1) {
+                        BIO_printf(bio_err, "Failed to set groups '%s'\n",
+                            groups_in);
+                        goto end;
+                }
+        }
+
 #ifndef OPENSSL_NO_DH
         if (!no_dhe) {
                 DH *dh = NULL;
@@ -1108,34 +1117,21 @@ s_server_main(int argc, char *argv[])
         }
 #endif
 
-        if (!no_ecdhe) {
+        if (!no_ecdhe && named_curve != NULL) {
                 EC_KEY *ecdh = NULL;
+                int nid;
 
-                if (named_curve) {
-                        int nid = OBJ_sn2nid(named_curve);
-
-                        if (nid == 0) {
-                                BIO_printf(bio_err, "unknown curve name (%s)\n",
-                                    named_curve);
-                                goto end;
-                        }
-                        ecdh = EC_KEY_new_by_curve_name(nid);
-                        if (ecdh == NULL) {
-                                BIO_printf(bio_err, "unable to create curve (%s)\n",
-                                    named_curve);
-                                goto end;
-                        }
+                if ((nid = OBJ_sn2nid(named_curve)) == 0) {
+                        BIO_printf(bio_err, "unknown curve name (%s)\n",
+                            named_curve);
+                        goto end;
                 }
-                if (ecdh != NULL) {
-                        BIO_printf(bio_s_out, "Setting temp ECDH parameters\n");
-                } else {
-                        BIO_printf(bio_s_out, "Using default temp ECDH parameters\n");
-                        ecdh = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
-                        if (ecdh == NULL) {
-                                BIO_printf(bio_err, "unable to create curve (nistp256)\n");
-                                goto end;
-                        }
+                if ((ecdh = EC_KEY_new_by_curve_name(nid)) == NULL) {
+                        BIO_printf(bio_err, "unable to create curve (%s)\n",
+                            named_curve);
+                        goto end;
                 }
+                BIO_printf(bio_s_out, "Setting temp ECDH parameters\n");
                 (void) BIO_flush(bio_s_out);
 
                 SSL_CTX_set_tmp_ecdh(ctx, ecdh);