From 528b3fd9bef74a408ae42fc2bd03c02ed3b45b52 Mon Sep 17 00:00:00 2001
From: Remi Tricot-Le Breton <rlebreton@haproxy.com>
Date: Tue, 12 Apr 2022 11:31:54 +0200
Subject: [PATCH] MINOR: ssl: Use DH parameters defined in RFC7919 instead of
 hard coded ones

RFC7919 defined sets of DH parameters supposedly strong enough to be
used safely. We will then use them when we can instead of our hard coded
ones (namely the ffdhe2048 and ffdhe4096 named groups).
The ffdhe2048 and ffdhe4096 named groups were integrated in OpenSSL
starting with version 1.1.1. Instead of duplicating those parameters in
haproxy for older versions of OpenSSL, we will keep using our own
parameters when they are not provided by the SSL library.
We will also need to keep our 1024 bits DH parameters since they are
considered not safe enough to have a dedicated named group in RFC7919
but we must still keep it for retrocompatibility with old Java clients.

This request was described in GitHub issue #1604.
---
 src/ssl_sock.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/ssl_sock.c b/src/ssl_sock.c
index 4e1ae5801..ceb4a067c 100644
--- a/src/ssl_sock.c
+++ b/src/ssl_sock.c
@@ -2954,6 +2954,41 @@ end:
 #endif
 }
 
+static inline HASSL_DH *ssl_get_dh_by_nid(int nid)
+{
+#if (HA_OPENSSL_VERSION_NUMBER >= 0x3000000fL)
+	OSSL_PARAM params[2];
+	EVP_PKEY *pkey = NULL;
+	EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_from_name(NULL, "DH", NULL);
+	const char *named_group = NULL;
+
+	if (!pctx)
+		goto end;
+
+	named_group = OBJ_nid2ln(nid);
+
+	if (!named_group)
+		goto end;
+
+	params[0] = OSSL_PARAM_construct_utf8_string("group", (char*)named_group, 0);
+	params[1] = OSSL_PARAM_construct_end();
+
+	if (EVP_PKEY_keygen_init(pctx) && EVP_PKEY_CTX_set_params(pctx, params))
+		EVP_PKEY_generate(pctx, &pkey);
+
+end:
+	EVP_PKEY_CTX_free(pctx);
+	return pkey;
+#else
+
+	HASSL_DH *dh = NULL;
+#if (HA_OPENSSL_VERSION_NUMBER >= 0x10101000L)
+	dh = DH_new_by_nid(nid);
+#endif
+	return dh;
+#endif
+}
+
 
 static HASSL_DH * ssl_get_dh_1024(void)
 {
@@ -2990,6 +3025,7 @@ static HASSL_DH * ssl_get_dh_1024(void)
 
 static HASSL_DH *ssl_get_dh_2048(void)
 {
+#if (HA_OPENSSL_VERSION_NUMBER < 0x10101000L)
 	static unsigned char dh2048_p[]={
 		0xEC,0x86,0xF8,0x70,0xA0,0x33,0x16,0xEC,0x05,0x1A,0x73,0x59,
 		0xCD,0x1F,0x8B,0xF8,0x29,0xE4,0xD2,0xCF,0x52,0xDD,0xC2,0x24,
@@ -3030,10 +3066,14 @@ static HASSL_DH *ssl_get_dh_2048(void)
 		dh = ssl_new_dh_fromdata(p, g);
 
 	return dh;
+#else
+	return ssl_get_dh_by_nid(NID_ffdhe2048);
+#endif
 }
 
 static HASSL_DH *ssl_get_dh_4096(void)
 {
+#if (HA_OPENSSL_VERSION_NUMBER < 0x10101000L)
 	static unsigned char dh4096_p[]={
 		0xDE,0x16,0x94,0xCD,0x99,0x58,0x07,0xF1,0xF7,0x32,0x96,0x11,
 		0x04,0x82,0xD4,0x84,0x72,0x80,0x99,0x06,0xCA,0xF0,0xA3,0x68,
@@ -3095,6 +3135,9 @@ static HASSL_DH *ssl_get_dh_4096(void)
 		dh = ssl_new_dh_fromdata(p, g);
 
 	return dh;
+#else
+	return ssl_get_dh_by_nid(NID_ffdhe4096);
+#endif
 }
 
 static HASSL_DH *ssl_get_tmp_dh(EVP_PKEY *pkey)