Support disabling any or all TLS or DTLS versions

Some users want to disable SSL 3.0/TLS 1.0/TLS 1.1, and enable just
TLS 1.2.  In the future they might want to disable TLS 1.2 and
enable just TLS 1.3, ...

This commit makes it possible to disable any or all of the TLS or
DTLS protocols.  It also considerably simplifies the SSL/TLS tests,
by auto-generating the min/max version tests based on the set of
supported protocols (425 explicitly written out tests got replaced
by two loops that generate all 425 tests if all protocols are
enabled, fewer otherwise).

Reviewed-by: Richard Levitte <levitte@openssl.org>

1 files changed, 107 insertions, 13 deletions

diff --git a/Configure b/Configure
index 908fe73fec..30e90b71e2 100755
--- a/Configure
+++ b/Configure
@@ -820,6 +820,10 @@ my $default_ranlib;
 my $perl;
 my $fips=0;
 
+# Known TLS and DTLS protocols
+my @tls = qw(ssl3 tls1 tls1_1 tls1_2);
+my @dtls = qw(dtls1 dtls1_2);
+
 # Explicitelly known options that are possible to disable.  They can
 # be regexps, and will be used like this: /^no-${option}$/
 # For developers: keep it sorted alphabetically
@@ -847,6 +851,8 @@ my @disablables = (
     "dynamic[-_]engine",
     "ec",
     "ec2m",
+    "ecdh",
+    "ecdsa",
     "ec_nistp_64_gcc_128",
     "engine",
     "err",			# Really???
@@ -887,20 +893,22 @@ my @disablables = (
     "srtp",
     "sse2",
     "ssl",
-    "ssl3",
-    "ssl3-method",
     "ssl-trace",
     "static-engine",
     "stdio",
     "store",
     "threads",
     "tls",
-    "tls1",
     "unit-test",
     "whirlpool",
     "zlib",
     "zlib-dynamic",
     );
+foreach my $proto ((@tls, @dtls))
+	{
+	push(@disablables, $proto);
+	push(@disablables, "$proto-method");
+	}
 
 # All of the following is disabled by default (RC5 was enabled before 0.9.8):
 
@@ -1000,19 +1008,35 @@ PROCESS_ARGS:
 			{
 			if (!($disabled{$1} eq "experimental"))
 				{
-				if ($1 eq "ssl")
+				foreach my $proto ((@tls, @dtls))
 					{
-					$disabled{"ssl3"} = "option(ssl)";
+					if ($1 eq "$proto-method")
+						{
+						$disabled{"$proto"} = "option($proto-method)";
+						last;
+						}
 					}
-				elsif ($1 eq "tls")
+				if ($1 eq "dtls")
 					{
-					$disabled{"tls1"} = "option(tls)"
+                                        foreach my $proto (@dtls)
+						{
+						$disabled{$proto} = "option(dtls)";
+						}
 					}
-				elsif ($1 eq "ssl3-method")
+				elsif ($1 eq "ssl")
 					{
-					$disabled{"ssl3-method"} = "option(ssl)";
+					# Last one of its kind
 					$disabled{"ssl3"} = "option(ssl)";
 					}
+				elsif ($1 eq "tls")
+					{
+                                        # XXX: Tests will fail if all SSL/TLS
+                                        # protocols are disabled.
+                                        foreach my $proto (@tls)
+						{
+						$disabled{$proto} = "option(tls)";
+						}
+					}
 				else
 					{
 					$disabled{$1} = "option";
@@ -1216,19 +1240,89 @@ if (defined($disabled{"ec"}))
 	$disabled{"ecdh"} = "forced";
 	}
 
-# SSL 3.0 and TLS requires MD5 and SHA and either RSA or DSA+DH
+# SSL 3.0 requires MD5 and SHA and either RSA or DSA+DH
 if (defined($disabled{"md5"}) || defined($disabled{"sha"})
     || (defined($disabled{"rsa"})
-        && (defined($disabled{"dsa"}) || defined($disabled{"dh"}))))
+	&& (defined($disabled{"dsa"}) || defined($disabled{"dh"}))))
 	{
 	$disabled{"ssl3"} = "forced";
+	$disabled{"ssl"} = "forced";
+	}
+
+# (D)TLS 1.0 and TLS 1.1 require MD5 and SHA and either RSA or DSA+DH
+# or ECDSA + ECDH.  (XXX: We don't support PSK-only builds).
+#
+if (defined($disabled{"md5"}) || defined($disabled{"sha"})
+    || (defined($disabled{"rsa"})
+	&& (defined($disabled{"dsa"}) || defined($disabled{"dh"}))
+	&& (defined($disabled{"ecdsa"}) || defined($disabled{"ecdh"}))))
+	{
 	$disabled{"tls1"} = "forced";
+	$disabled{"dtls1"} = "forced";
+	$disabled{"tls1_1"} = "forced";
+	}
+
+# (D)TLS 1.2 requires either RSA or DSA+DH or ECDSA + ECDH
+# So if all are missing, we can't do either TLS or DTLS.
+# (XXX: We don't support PSK-only builds).
+#
+if (defined($disabled{"rsa"})
+    && (defined($disabled{"dsa"}) || defined($disabled{"dh"}))
+    && (defined($disabled{"ecdsa"}) || defined($disabled{"ecdh"})))
+	{
+	$disabled{"tls"} = "forced";
+	$disabled{"dtls"} = "forced";
+	foreach my $proto ((@tls, @dtls))
+		{
+		$disabled{"$proto"} = "forced";
+		}
+	}
+
+
+# Avoid protocol support holes.  Also disable all versions below N, if version
+# N is disabled while N+1 is enabled.
+#
+my $prev_disabled = 1;
+my $force_disable = 0;
+foreach my $proto (reverse(@tls))
+	{
+	if ($force_disable)
+		{
+		$disabled{$proto} = 1;
+		}
+	elsif (! defined($disabled{$proto}))
+		{
+		$prev_disabled = 0;
+		}
+	elsif (! $prev_disabled)
+		{
+		$force_disable = 1;
+		}
+	}
+my $prev_disabled = 1;
+my $force_disable = 0;
+foreach my $proto (reverse(@dtls))
+	{
+	if ($force_disable)
+		{
+		$disabled{$proto} = 1;
+		}
+	elsif (! defined($disabled{$proto}))
+		{
+		$prev_disabled = 0;
+		}
+	elsif (! $prev_disabled)
+		{
+		$force_disable = 1;
+		}
 	}
 
 if (defined($disabled{"dgram"}))
 	{
-        $disabled{"dtls"} = "forced";
-        }
+	$disabled{"dtls"} = "forced";
+	$disabled{"dtls1"} = "forced";
+	$disabled{"dtls1_2"} = "forced";
+	}
 
 if (defined($disabled{"ec"}) || defined($disabled{"dsa"})
     || defined($disabled{"dh"}) || defined($disabled{"stdio"}))