From 55d894bbfbb992482d4fbeac3b03f3bb5b2b258b Mon Sep 17 00:00:00 2001
From: Markus Minichmayr <markus@tapkey.com>
Date: Tue, 21 Nov 2023 23:50:54 +0100
Subject: [PATCH] Document `SSL_OP_PREFER_NO_DHE_KEX` option.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22794)
---
 doc/man1/openssl-s_client.pod.in |  1 +
 doc/man1/openssl-s_server.pod.in |  1 +
 doc/man3/SSL_CONF_cmd.pod        | 11 +++++++++++
 doc/man3/SSL_CTX_set_options.pod |  6 ++++++
 doc/perlvars.pm                  |  4 +++-
 5 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/doc/man1/openssl-s_client.pod.in b/doc/man1/openssl-s_client.pod.in
index 84cf6fdd81..f8db2658be 100644
--- a/doc/man1/openssl-s_client.pod.in
+++ b/doc/man1/openssl-s_client.pod.in
@@ -93,6 +93,7 @@ B<openssl> B<s_client>
 [B<-legacy_server_connect>]
 [B<-no_legacy_server_connect>]
 [B<-allow_no_dhe_kex>]
+[B<-prefer_no_dhe_kex>]
 [B<-sigalgs> I<sigalglist>]
 [B<-curves> I<curvelist>]
 [B<-cipher> I<cipherlist>]
diff --git a/doc/man1/openssl-s_server.pod.in b/doc/man1/openssl-s_server.pod.in
index 611b410cfd..9726a5c871 100644
--- a/doc/man1/openssl-s_server.pod.in
+++ b/doc/man1/openssl-s_server.pod.in
@@ -102,6 +102,7 @@ B<openssl> B<s_server>
 [B<-no_renegotiation>]
 [B<-no_resumption_on_reneg>]
 [B<-allow_no_dhe_kex>]
+[B<-prefer_no_dhe_kex>]
 [B<-prioritize_chacha>]
 [B<-strict>]
 [B<-sigalgs> I<val>]
diff --git a/doc/man3/SSL_CONF_cmd.pod b/doc/man3/SSL_CONF_cmd.pod
index 7ffd731410..a0e4d52892 100644
--- a/doc/man3/SSL_CONF_cmd.pod
+++ b/doc/man3/SSL_CONF_cmd.pod
@@ -95,6 +95,12 @@ Only used by servers. Requires B<-serverpref>.
 In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means
 that there will be no forward secrecy for the resumed session.
 
+=item B<-prefer_no_dhe_kex>
+
+In TLSv1.3, on resumption let the server prefer a non-(ec)dhe based key
+exchange mode over an (ec)dhe based one. Requires B<-allow_no_dhe_kex>.
+Equivalent to B<SSL_OP_PREFER_NO_DHE_KEX>. Only used by servers.
+
 =item B<-strict>
 
 Enables strict mode protocol handling. Equivalent to setting
@@ -523,6 +529,11 @@ B<AllowNoDHEKEX>: In TLSv1.3 allow a non-(ec)dhe based key exchange mode on
 resumption. This means that there will be no forward secrecy for the resumed
 session. Equivalent to B<SSL_OP_ALLOW_NO_DHE_KEX>.
 
+B<PreferNoDHEKEX>: In TLSv1.3, on resumption let the server prefer a
+non-(ec)dhe based key exchange mode over an (ec)dhe based one. Requires
+B<AllowNoDHEKEX>. Equivalent to B<SSL_OP_PREFER_NO_DHE_KEX>. Only used by
+servers.
+
 B<MiddleboxCompat>: If set then dummy Change Cipher Spec (CCS) messages are sent
 in TLSv1.3. This has the effect of making TLSv1.3 look more like TLSv1.2 so that
 middleboxes that do not understand TLSv1.3 will not drop the connection. This
diff --git a/doc/man3/SSL_CTX_set_options.pod b/doc/man3/SSL_CTX_set_options.pod
index 56695e4abd..272b2a93e4 100644
--- a/doc/man3/SSL_CTX_set_options.pod
+++ b/doc/man3/SSL_CTX_set_options.pod
@@ -110,6 +110,12 @@ this option to enable it.
 In TLSv1.3 allow a non-(ec)dhe based key exchange mode on resumption. This means
 that there will be no forward secrecy for the resumed session.
 
+=item SSL_OP_PREFER_NO_DHE_KEX
+
+In TLSv1.3, on resumption let the server prefer a non-(ec)dhe based key
+exchange mode over an (ec)dhe based one. Ignored without B<SSL_OP_ALLOW_NO_DHE_KEX>
+being set as well. Always ignored on the client.
+
 =item SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
 
 Allow legacy insecure renegotiation between OpenSSL and unpatched clients or
diff --git a/doc/perlvars.pm b/doc/perlvars.pm
index f4c20aa392..06dac990cf 100644
--- a/doc/perlvars.pm
+++ b/doc/perlvars.pm
@@ -187,6 +187,7 @@ $OpenSSL::safe::opt_s_synopsis = ""
 . "[B<-no_legacy_server_connect>]\n"
 . "[B<-no_etm>]\n"
 . "[B<-allow_no_dhe_kex>]\n"
+. "[B<-prefer_no_dhe_kex>]\n"
 . "[B<-prioritize_chacha>]\n"
 . "[B<-strict>]\n"
 . "[B<-sigalgs> I<algs>]\n"
@@ -207,7 +208,8 @@ $OpenSSL::safe::opt_s_item = ""
 . "B<-legacy_renegotiation>, B<-no_renegotiation>,\n"
 . "B<-no_resumption_on_reneg>,\n"
 . "B<-legacy_server_connect>, B<-no_legacy_server_connect>, B<-no_etm>\n"
-. "B<-allow_no_dhe_kex>, B<-prioritize_chacha>, B<-strict>, B<-sigalgs>\n"
+. "B<-allow_no_dhe_kex>, B<-prefer_no_dhe_kex>,\n"
+. "B<-prioritize_chacha>, B<-strict>, B<-sigalgs>\n"
 . "I<algs>, B<-client_sigalgs> I<algs>, B<-groups> I<groups>, B<-curves>\n"
 . "I<curves>, B<-named_curve> I<curve>, B<-cipher> I<ciphers>, B<-ciphersuites>\n"
 . "I<1.3ciphers>, B<-min_protocol> I<minprot>, B<-max_protocol> I<maxprot>,\n"