@@ -3,6 +3,12 @@ Overview of changes in 2.5
New features
------------
+Client-specific tls-crypt keys (``--tls-crypt-v2``)
+ ``tls-crypt-v2`` adds the ability to supply each client with a unique
+ tls-crypt key. This allows large organisations and VPN providers to profit
+ from the same DoS and TLS stack protection that small deployments can
+ already achieve using ``tls-auth`` or ``tls-crypt``.
+
ChaCha20-Poly1305 cipher support
Added support for using the ChaCha20-Poly1305 cipher in the OpenVPN data
channel.
@@ -5310,9 +5310,38 @@ If supplied, include the supplied
in the wrapped client key. This metadata must be supplied in base64\-encoded
form. The metadata must be at most 735 bytes long (980 bytes in base64).
-.B TODO
-Metadata handling is not yet implemented. This text will be updated by the
-commit that introduces metadata handling.
+If no metadata is supplied, OpenVPN will use a 64\-bit unix timestamp
+representing the current time in UTC, encoded in network order, as metadata for
+the generated key.
+
+Servers can use
+.B \-\-tls\-crypt\-v2\-verify
+to specify a metadata verification command.
+.\"*********************************************************
+.TP
+.B \-\-tls\-crypt\-v2\-verify cmd
+
+Run command
+.B cmd
+to verify the metadata of the client\-specific tls\-crypt\-v2 key of a
+connecting client. This allows server administrators to reject client
+connections, before exposing the TLS stack (including the notoriously dangerous
+X.509 and ASN.1 stacks) to the connecting client.
+
+OpenVPN supplies the following env vars to the command:
+.RS
+.IP \[bu] 2
+script_type is set to "tls\-crypt\-v2\-verify"
+.IP \[bu]
+metadata_type is set to "0" if the metadata was user supplied, or "1" if it's a
+64\-bit unix timestamp representing the key creation time.
+.IP \[bu]
+metadata_file contains the filename of a temporary file that contains the client
+metadata.
+.RE
+
+.IP
+The command can reject the connection by exiting with a non-zero exit code.
.\"*********************************************************
.TP
.B \-\-askpass [file]
@@ -2903,6 +2903,7 @@ do_init_crypto_tls(struct context *c, const unsigned int flags)
if (options->tls_server)
{
to.tls_wrap.tls_crypt_v2_server_key = c->c1.ks.tls_crypt_v2_server_key;
+ to.tls_crypt_v2_verify_script = c->options.tls_crypt_v2_verify_script;
}
}
@@ -629,6 +629,8 @@ static const char usage_message[] =
"--tls-crypt-v2-genkey client|server keyfile [base64 metadata]: Generate a\n"
" fresh tls-crypt-v2 client or server key, and store to\n"
" keyfile. If supplied, include metadata in wrapped key.\n"
+ "--tls-crypt-v2-verify cmd : Run command cmd to verify the metadata of the\n"
+ " client-supplied tls-crypt-v2 client key\n"
"--askpass [file]: Get PEM password from controlling tty before we daemonize.\n"
"--auth-nocache : Don't cache --askpass or --auth-user-pass passwords.\n"
"--crl-verify crl ['dir']: Check peer certificate against a CRL.\n"
@@ -8131,6 +8133,11 @@ add_option(struct options *options,
options->tls_crypt_v2_metadata = p[3];
}
}
+ else if (streq(p[0], "tls-crypt-v2-verify") && p[1] && !p[2])
+ {
+ VERIFY_PERMISSION(OPT_P_GENERAL);
+ options->tls_crypt_v2_verify_script = p[1];
+ }
else if (streq(p[0], "key-method") && p[1] && !p[2])
{
int key_method;
@@ -591,6 +591,8 @@ struct options
const char *tls_crypt_v2_genkey_file;
const char *tls_crypt_v2_metadata;
+ const char *tls_crypt_v2_verify_script;
+
/* Allow only one session */
bool single_session;
@@ -1048,23 +1048,6 @@ tls_session_user_pass_enabled(struct tls_session *session)
/** @addtogroup control_processor
* @{ */
-/** Free the elements of a tls_wrap_ctx structure */
-static void tls_wrap_free(struct tls_wrap_ctx *tls_wrap)
-{
- if (packet_id_initialized(&tls_wrap->opt.packet_id))
- {
- packet_id_free(&tls_wrap->opt.packet_id);
- }
-
- if (tls_wrap->cleanup_key_ctx)
- {
- free_key_ctx_bi(&tls_wrap->opt.key_ctx_bi);
- }
-
- free_buf(&tls_wrap->tls_crypt_v2_metadata);
- free_buf(&tls_wrap->work);
-}
-
/** @name Functions for initialization and cleanup of tls_session structures
* @{ */
@@ -1534,14 +1517,15 @@ write_control_auth(struct tls_session *session,
static bool
read_control_auth(struct buffer *buf,
struct tls_wrap_ctx *ctx,
- const struct link_socket_actual *from)
+ const struct link_socket_actual *from,
+ const struct tls_options *opt)
{
struct gc_arena gc = gc_new();
bool ret = false;
const uint8_t opcode = *(BPTR(buf)) >> P_OPCODE_SHIFT;
if (opcode == P_CONTROL_HARD_RESET_CLIENT_V3
- && !tls_crypt_v2_extract_client_key(buf, ctx))
+ && !tls_crypt_v2_extract_client_key(buf, ctx, opt))
{
msg (D_TLS_ERRORS,
"TLS Error: can not extract tls-crypt-v2 client key from %s",
@@ -3622,7 +3606,8 @@ tls_pre_decrypt(struct tls_multi *multi,
goto error;
}
- if (!read_control_auth(buf, &session->tls_wrap, from))
+ if (!read_control_auth(buf, &session->tls_wrap, from,
+ session->opt))
{
goto error;
}
@@ -3675,7 +3660,8 @@ tls_pre_decrypt(struct tls_multi *multi,
if (op == P_CONTROL_SOFT_RESET_V1
&& DECRYPT_KEY_ENABLED(multi, ks))
{
- if (!read_control_auth(buf, &session->tls_wrap, from))
+ if (!read_control_auth(buf, &session->tls_wrap, from,
+ session->opt))
{
goto error;
}
@@ -3696,7 +3682,8 @@ tls_pre_decrypt(struct tls_multi *multi,
do_burst = true;
}
- if (!read_control_auth(buf, &session->tls_wrap, from))
+ if (!read_control_auth(buf, &session->tls_wrap, from,
+ session->opt))
{
goto error;
}
@@ -3898,8 +3885,9 @@ tls_pre_decrypt_lite(const struct tls_auth_standalone *tas,
bool status;
/* HMAC test, if --tls-auth was specified */
- status = read_control_auth(&newbuf, &tls_wrap_tmp, from);
+ status = read_control_auth(&newbuf, &tls_wrap_tmp, from, NULL);
free_buf(&newbuf);
+ free_buf(&tls_wrap_tmp.tls_crypt_v2_metadata);
if (tls_wrap_tmp.cleanup_key_ctx)
{
free_key_ctx_bi(&tls_wrap_tmp.opt.key_ctx_bi);
@@ -527,6 +527,24 @@ bool tls_item_in_cipher_list(const char *item, const char *list);
* inline functions
*/
+/** Free the elements of a tls_wrap_ctx structure */
+static inline void
+tls_wrap_free(struct tls_wrap_ctx *tls_wrap)
+{
+ if (packet_id_initialized(&tls_wrap->opt.packet_id))
+ {
+ packet_id_free(&tls_wrap->opt.packet_id);
+ }
+
+ if (tls_wrap->cleanup_key_ctx)
+ {
+ free_key_ctx_bi(&tls_wrap->opt.key_ctx_bi);
+ }
+
+ free_buf(&tls_wrap->tls_crypt_v2_metadata);
+ free_buf(&tls_wrap->work);
+}
+
static inline bool
tls_initial_packet_received(const struct tls_multi *multi)
{
@@ -293,6 +293,7 @@ struct tls_options
bool ncp_enabled;
bool tls_crypt_v2;
+ const char *tls_crypt_v2_verify_script;
/** TLS handshake wrapping state */
struct tls_wrap_ctx tls_wrap;
@@ -29,9 +29,11 @@
#include "syshead.h"
+#include "argv.h"
#include "base64.h"
#include "crypto.h"
#include "platform.h"
+#include "run_command.h"
#include "session_id.h"
#include "ssl.h"
@@ -544,9 +546,69 @@ error_exit:
return ret;
}
+static bool
+tls_crypt_v2_verify_metadata(const struct tls_wrap_ctx *ctx,
+ const struct tls_options *opt)
+{
+ bool ret = false;
+ struct gc_arena gc = gc_new();
+ const char *tmp_file = NULL;
+ struct buffer metadata = ctx->tls_crypt_v2_metadata;
+ int metadata_type = buf_read_u8(&metadata);
+ if (metadata_type < 0)
+ {
+ msg(M_WARN, "ERROR: no metadata type");
+ goto cleanup;
+ }
+
+ tmp_file = platform_create_temp_file(opt->tmp_dir, "tls_crypt_v2_metadata_",
+ &gc);
+ if (!tmp_file || !buffer_write_file(tmp_file, &metadata))
+ {
+ msg(M_WARN, "ERROR: could not write metadata to file");
+ goto cleanup;
+ }
+
+ char metadata_type_str[4] = { 0 }; /* Max value: 255 */
+ openvpn_snprintf(metadata_type_str, sizeof(metadata_type_str),
+ "%i", metadata_type);
+ struct env_set *es = env_set_create(NULL);
+ setenv_str(es, "script_type", "tls-crypt-v2-verify");
+ setenv_str(es, "metadata_type", metadata_type_str);
+ setenv_str(es, "metadata_file", tmp_file);
+
+ struct argv argv = argv_new();
+ argv_parse_cmd(&argv, opt->tls_crypt_v2_verify_script);
+ argv_msg_prefix(D_TLS_DEBUG, &argv, "Executing tls-crypt-v2-verify");
+
+ ret = openvpn_run_script(&argv, es, 0, "--tls-crypt-v2-verify");
+
+ argv_reset(&argv);
+ env_set_destroy(es);
+
+ if (!platform_unlink(tmp_file))
+ {
+ msg(M_WARN, "WARNING: failed to remove temp file '%s", tmp_file);
+ }
+
+ if (ret)
+ {
+ msg(D_HANDSHAKE, "TLS CRYPT V2 VERIFY SCRIPT OK");
+ }
+ else
+ {
+ msg(D_HANDSHAKE, "TLS CRYPT V2 VERIFY SCRIPT ERROR");
+ }
+
+cleanup:
+ gc_free(&gc);
+ return ret;
+}
+
bool
tls_crypt_v2_extract_client_key(struct buffer *buf,
- struct tls_wrap_ctx *ctx)
+ struct tls_wrap_ctx *ctx,
+ const struct tls_options *opt)
{
if (!ctx->tls_crypt_v2_server_key.cipher)
{
@@ -597,6 +659,11 @@ tls_crypt_v2_extract_client_key(struct buffer *buf,
/* Remove client key from buffer so tls-crypt code can unwrap message */
ASSERT(buf_inc_len(buf, -(BLEN(&wrapped_client_key))));
+ if (opt && opt->tls_crypt_v2_verify_script)
+ {
+ return tls_crypt_v2_verify_metadata(ctx, opt);
+ }
+
return true;
}
@@ -195,7 +195,8 @@ void tls_crypt_v2_init_client_key(struct key_ctx_bi *key,
* @returns true if a key was successfully extracted.
*/
bool tls_crypt_v2_extract_client_key(struct buffer *buf,
- struct tls_wrap_ctx *ctx);
+ struct tls_wrap_ctx *ctx,
+ const struct tls_options *opt);
/**
* Generate a tls-crypt-v2 server key, and write to file.
@@ -6,7 +6,10 @@ if HAVE_LD_WRAP_SUPPORT
check_PROGRAMS += argv_testdriver buffer_testdriver
endif
-check_PROGRAMS += crypto_testdriver packet_id_testdriver tls_crypt_testdriver
+check_PROGRAMS += crypto_testdriver packet_id_testdriver
+if HAVE_LD_WRAP_SUPPORT
+check_PROGRAMS += tls_crypt_testdriver
+endif
TESTS = $(check_PROGRAMS)
@@ -52,13 +55,16 @@ packet_id_testdriver_SOURCES = test_packet_id.c mock_msg.c \
tls_crypt_testdriver_CFLAGS = @TEST_CFLAGS@ \
-I$(openvpn_includedir) -I$(compat_srcdir) -I$(openvpn_srcdir)
-tls_crypt_testdriver_LDFLAGS = @TEST_LDFLAGS@
+tls_crypt_testdriver_LDFLAGS = @TEST_LDFLAGS@ -Wl,--wrap=parse_line
tls_crypt_testdriver_SOURCES = test_tls_crypt.c mock_msg.c \
+ $(openvpn_srcdir)/argv.c \
$(openvpn_srcdir)/base64.c \
$(openvpn_srcdir)/buffer.c \
$(openvpn_srcdir)/crypto.c \
$(openvpn_srcdir)/crypto_mbedtls.c \
$(openvpn_srcdir)/crypto_openssl.c \
+ $(openvpn_srcdir)/env_set.c \
$(openvpn_srcdir)/otime.c \
$(openvpn_srcdir)/packet_id.c \
- $(openvpn_srcdir)/platform.c
+ $(openvpn_srcdir)/platform.c \
+ $(openvpn_srcdir)/run_command.c
@@ -43,8 +43,24 @@
#define TESTBUF_SIZE 128
+/* Defines for use in the tests and the mock parse_line() */
+#define PATH1 "/s p a c e"
+#define PATH2 "/foo bar/baz"
+#define PARAM1 "param1"
+#define PARAM2 "param two"
+
const char plaintext_short[1];
+int
+__wrap_parse_line(const char *line, char **p, const int n, const char *file,
+ const int line_num, int msglevel, struct gc_arena *gc)
+{
+ p[0] = PATH1 PATH2;
+ p[1] = PARAM1;
+ p[2] = PARAM2;
+ return 3;
+}
+
struct test_tls_crypt_context {
struct crypto_options co;
struct key_type kt;
@@ -351,7 +367,8 @@ tls_crypt_v2_wrap_unwrap_max_metadata(void **state) {
.mode = TLS_WRAP_CRYPT,
.tls_crypt_v2_server_key = ctx->server_keys.encrypt,
};
- assert_true(tls_crypt_v2_extract_client_key(&ctx->wkc, &wrap_ctx));
+ assert_true(tls_crypt_v2_extract_client_key(&ctx->wkc, &wrap_ctx, NULL));
+ tls_wrap_free(&wrap_ctx);
}
/**