The SSL 3.0 protocol is disabled on compile time by default

It can be re-enabled by specifying --enable-ssl3-support on configure script.
This is the first step before removing support for the protocol completely.

Relates #103

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

6 files changed, 19 insertions, 8 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 230b0a043c..a73e42a8df 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -109,13 +109,13 @@ minimal.Fedora.x86_64:
   except:
   - tags
 
-no-SSL-3.0.Fedora.x86_64:
+SSL-3.0.Fedora.x86_64:
   stage: stage1-testing
   image: $CI_REGISTRY/$BUILD_IMAGES_PROJECT:$FEDORA_BUILD
   script:
   - ./bootstrap
   - mkdir -p build && cd build &&
-    dash ../configure --disable-gcc-warnings --cache-file ../cache/config.cache --disable-ssl3-support --disable-ssl2-support --disable-full-test-suite --enable-seccomp-tests --disable-doc --disable-guile &&
+    dash ../configure --disable-gcc-warnings --cache-file ../cache/config.cache --enable-ssl3-support --disable-ssl2-support --disable-full-test-suite --enable-seccomp-tests --disable-doc --disable-guile &&
     make -j$(nproc) && make check -j$(nproc)
   - cd ..
   tags:
@@ -138,7 +138,7 @@ TLS1.3/interop:
   script:
   - git submodule update --init --no-fetch
   - ./bootstrap
-  - dash ./configure --enable-tls13-support --disable-gcc-warnings --cache-file cache/config.cache --disable-ssl3-support --disable-ssl2-support --disable-full-test-suite --enable-seccomp-tests --disable-doc --disable-guile &&
+  - dash ./configure --enable-tls13-support --disable-gcc-warnings --cache-file cache/config.cache --disable-full-test-suite --enable-seccomp-tests --disable-doc --disable-guile &&
     make -j$(nproc)
   - cd devel/openssl && ./config enable-tls1_3 && make -j$(nproc) && cd ../..
   - make -C tests/suite TESTS=testcompat-tls13-openssl.sh check
diff --git a/NEWS b/NEWS
index 304508eefe..ff32cf7cc6 100644
--- a/NEWS
+++ b/NEWS
@@ -31,6 +31,9 @@ See the end for copying conditions.
    priority strings, as they are undefined under TLS1.3 and they provide not advantage
    over other options in earlier protocols.
 
+** The SSL 3.0 protocol is disabled on compile-time by default. It can be re-enabled
+   by specifying --enable-ssl3-support on configure script.
+
 ** libgnutls: Introduced function to switch the current FIPS140-2 operational
    mode, i.e., strict vs a more lax mode which will allow certain non FIPS140-2
    operations.
diff --git a/doc/cha-library.texi b/doc/cha-library.texi
index 7fe7fb7297..354bb0a769 100644
--- a/doc/cha-library.texi
+++ b/doc/cha-library.texi
@@ -15,7 +15,7 @@ include:
 
 @itemize
 
-@item Support for TLS 1.3, TLS 1.2, TLS 1.1, TLS 1.0 and SSL 3.0 protocols.
+@item Support for TLS 1.3, TLS 1.2, TLS 1.1, TLS 1.0 and optionally SSL 3.0 protocols.
 
 @item Support for Datagram TLS 1.0 and 1.2.
 
diff --git a/doc/cha-upgrade.texi b/doc/cha-upgrade.texi
index 3e593dffb7..83e1120840 100644
--- a/doc/cha-upgrade.texi
+++ b/doc/cha-upgrade.texi
@@ -194,6 +194,11 @@ however, there are minor differences, listed below.
 @item The priority strings "+COMP" are a no-op
 @tab TLS compression is no longer available.
 
+@item The SSL 3.0 protocol is a no-op
+@tab SSL 3.0 is no longer compiled in by default. It is a legacy protocol
+which is completely eliminated from public internet. As such it was removed
+to reduce the attack vector for applications using the library.
+
 @item The hash function SHA2-224 is a no-op for TLS1.2
 @tab TLS 1.3 no longer uses SHA2-224, and it was never a widespread hash
 algorithm. As such it was removed for simplicity.
diff --git a/lib/cipher-cbc.c b/lib/cipher-cbc.c
index 22b9390596..741119223b 100644
--- a/lib/cipher-cbc.c
+++ b/lib/cipher-cbc.c
@@ -84,7 +84,9 @@ int cbc_mac_verify(gnutls_session_t session, record_parameters_st *params,
 	const uint8_t *tag_ptr = NULL;
 	unsigned preamble_size;
 	uint8_t tag[MAX_HASH_SIZE];
+#ifdef ENABLE_SSL3
 	unsigned blocksize = _gnutls_cipher_get_block_size(params->cipher);
+#endif
 
 	pad = data[data_size - 1];	/* pad */
 
diff --git a/m4/hooks.m4 b/m4/hooks.m4
index fcd6f9cd80..fe8d9a2dde 100644
--- a/m4/hooks.m4
+++ b/m4/hooks.m4
@@ -157,11 +157,11 @@ LIBTASN1_MINIMUM=4.9
   fi
   AM_CONDITIONAL(ALLOW_SHA1, test "$ac_allow_sha1" != "no")
 
-  ac_enable_ssl3=yes
+  ac_enable_ssl3=no
   AC_MSG_CHECKING([whether to disable the SSL 3.0 protocol])
   AC_ARG_ENABLE(ssl3-support,
-    AS_HELP_STRING([--disable-ssl3-support],
-                   [disable support for the SSL 3.0 protocol]),
+    AS_HELP_STRING([--enable-ssl3-support],
+                   [enable support for the SSL 3.0 protocol]),
     ac_enable_ssl3=$enableval)
   if test x$ac_enable_ssl3 != xno; then
    AC_MSG_RESULT(no)
@@ -170,6 +170,7 @@ LIBTASN1_MINIMUM=4.9
    ac_full=0
    AC_MSG_RESULT(yes)
   fi
+
   AM_CONDITIONAL(ENABLE_SSL3, test "$ac_enable_ssl3" != "no")
 
   ac_enable_tls13=no
@@ -200,7 +201,7 @@ LIBTASN1_MINIMUM=4.9
    ac_full=0
    AC_MSG_RESULT(yes)
   fi
-  AM_CONDITIONAL(ENABLE_SSL3, test "$ac_enable_ssl2" != "no")
+  AM_CONDITIONAL(ENABLE_SSL2, test "$ac_enable_ssl2" != "no")
 
   ac_enable_srtp=yes
   AC_MSG_CHECKING([whether to disable DTLS-SRTP extension])