From 3aec89b8c207da644385f68b5bed2a2782c07f66 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Thu, 1 Apr 2021 14:00:11 +0200
Subject: [PATCH] Fix SSL tests scripts with recent OpenSSL server with
 Diffie-Hellman

Our interoperability tests fail with a recent OpenSSL server. The
reason is that they force 1024-bit Diffie-Hellman parameters, which
recent OpenSSL (e.g. 1.1.1f on Ubuntu 20.04) reject:
```
140072814650688:error:1408518A:SSL routines:ssl3_ctx_ctrl:dh key too small:../ssl/s3_lib.c:3782:
```

We've been passing custom DH parameters since
6195767554da332e9f81e6510b07f7565ff8a538 because OpenSSL <=1.0.2a
requires it. This is only concerns the version we use as
OPENSSL_LEGACY. So only use custom DH parameters for that version. In
compat.sh, use it based on the observed version of $OPENSSL_CMD.

This way, ssl-opt.sh and compat.sh work (barring other issues) for all
our reference versions of OpenSSL as well as for a modern system OpenSSL.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
---
 tests/compat.sh  | 15 ++++++++++++++-
 tests/ssl-opt.sh |  2 +-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/tests/compat.sh b/tests/compat.sh
index 6e0a8f963..29aa686f6 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -905,10 +905,23 @@ setup_arguments()
     fi
 
     M_SERVER_ARGS="server_port=$PORT server_addr=0.0.0.0 force_version=$MODE arc4=1"
-    O_SERVER_ARGS="-accept $PORT -cipher NULL,ALL -$MODE -dhparam data_files/dhparams.pem"
+    O_SERVER_ARGS="-accept $PORT -cipher NULL,ALL -$MODE"
     G_SERVER_ARGS="-p $PORT --http $G_MODE"
     G_SERVER_PRIO="NORMAL:${G_PRIO_CCM}+ARCFOUR-128:+NULL:+MD5:+PSK:+DHE-PSK:+ECDHE-PSK:+SHA256:+SHA384:+RSA-PSK:-VERS-TLS-ALL:$G_PRIO_MODE"
 
+    # The default prime for `openssl s_server` depends on the version:
+    # * OpenSSL <= 1.0.2a: 512-bit
+    # * OpenSSL 1.0.2b to 1.1.1b: 1024-bit
+    # * OpenSSL >= 1.1.1c: 2048-bit
+    # Mbed TLS wants >=1024, so force that for older versions. Don't force
+    # it for newer versions, which reject a 1024-bit prime. Indifferently
+    # force it or not for intermediate versions.
+    case $($OPENSSL_CMD version) in
+        "OpenSSL 1.0"*)
+            O_SERVER_ARGS="$O_SERVER_ARGS -dhparam data_files/dhparams.pem"
+            ;;
+    esac
+
     # with OpenSSL 1.0.1h, -www, -WWW and -HTTP break DTLS handshakes
     if is_dtls "$MODE"; then
         O_SERVER_ARGS="$O_SERVER_ARGS"
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 6c54900ce..310f9daf6 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -1139,7 +1139,7 @@ SRV_DELAY_SECONDS=0
 P_SRV="$P_SRV server_addr=127.0.0.1 server_port=$SRV_PORT"
 P_CLI="$P_CLI server_addr=127.0.0.1 server_port=+SRV_PORT"
 P_PXY="$P_PXY server_addr=127.0.0.1 server_port=$SRV_PORT listen_addr=127.0.0.1 listen_port=$PXY_PORT ${SEED:+"seed=$SEED"}"
-O_SRV="$O_SRV -accept $SRV_PORT -dhparam data_files/dhparams.pem"
+O_SRV="$O_SRV -accept $SRV_PORT"
 O_CLI="$O_CLI -connect localhost:+SRV_PORT"
 G_SRV="$G_SRV -p $SRV_PORT"
 G_CLI="$G_CLI -p +SRV_PORT"