OpenSSL 1.1.1 introduces a separate list for TLS 1.3 ciphers. As these
interfaces are meant to be user facing or not exposed at all and we
expose the tls-cipher interface, we should also expose tls-cipherlist.
Combining both settings into tls-cipher would add a lot of glue logic
that needs to be maintained and is error prone. On top of that, users
should not set either settings unless absolutely required.
OpenSSL's own s_client/s_server also expose both settings and I believe
most other software will too:
-cipher val Specify TLSv1.2 and below cipher list to be used
-ciphersuites val Specify TLSv1.3 ciphersuites to be used
For mbed TLS only the future can tell if we will see a combined or also
two separate lists.
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <
20181007215539.32761-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg17626.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit
ea4ee31333a0cddb5c8dd4185f9426df13c76947)
.\"*********************************************************
.TP
.B \-\-tls\-cipher l
+.TQ
+.B \-\-tls\-ciphersuites l
A list
.B l
of allowable TLS ciphers delimited by a colon (":").
-This setting can be used to ensure that certain cipher suites are used (or
+These setting can be used to ensure that certain cipher suites are used (or
not used) for the TLS connection. OpenVPN uses TLS to secure the control
channel, over which the keys that are used to protect the actual VPN traffic
are exchanged.
simply supplied to the crypto library. Please see the OpenSSL and/or mbed TLS
documentation for details on the cipher list interpretation.
+For OpenSSL, the
+.B \-\-tls-cipher
+is used for TLS 1.2 and below. For TLS 1.3 and up, the
+.B \-\-tls\-ciphersuites
+setting is used. mbed TLS has no TLS 1.3 support yet and only the
+.B \-\-tls-cipher
+setting is used.
+
Use
.B \-\-show\-tls
to see a list of TLS ciphers supported by your crypto library.
Warning!
.B \-\-tls\-cipher
-is an expert feature, which \- if used correcly \- can improve the security of
-your VPN connection. But it is also easy to unwittingly use it to carefully
+and
+.B \-\-tls\-ciphersuites
+are expert features, which \- if used correcly \- can improve the security of
+your VPN connection. But it is also easy to unwittingly use them to carefully
align a gun with your foot, or just break your connection. Use with care!
The default for \-\-tls\-cipher is to use mbed TLS's default cipher list
when using mbed TLS or
"DEFAULT:!EXP:!LOW:!MEDIUM:!kDH:!kECDH:!DSS:!PSK:!SRP:!kRSA" when using
OpenSSL.
+
+The default for \-\-tls\-ciphersuites is to use the crypto library's default.
.\"*********************************************************
.TP
.B \-\-tls\-cert\-profile profile
SHOW_STR(cryptoapi_cert);
#endif
SHOW_STR(cipher_list);
+ SHOW_STR(cipher_list_tls13);
SHOW_STR(tls_cert_profile);
SHOW_STR(tls_verify);
SHOW_STR(tls_export_cert);
MUST_BE_UNDEF(pkcs12_file);
#endif
MUST_BE_UNDEF(cipher_list);
+ MUST_BE_UNDEF(cipher_list_tls13);
MUST_BE_UNDEF(tls_cert_profile);
MUST_BE_UNDEF(tls_verify);
MUST_BE_UNDEF(tls_export_cert);
VERIFY_PERMISSION(OPT_P_GENERAL);
options->tls_cert_profile = p[1];
}
+ else if (streq(p[0], "tls-ciphersuites") && p[1] && !p[2])
+ {
+ VERIFY_PERMISSION(OPT_P_GENERAL);
+ options->cipher_list_tls13 = p[1];
+ }
else if (streq(p[0], "crl-verify") && p[1] && ((p[2] && streq(p[2], "dir"))
|| (p[2] && streq(p[1], INLINE_FILE_TAG) ) || !p[2]) && !p[3])
{
const char *priv_key_file;
const char *pkcs12_file;
const char *cipher_list;
+ const char *cipher_list_tls13;
const char *tls_cert_profile;
const char *ecdh_curve;
const char *tls_verify;
tls_ctx_set_cert_profile(new_ctx, options->tls_cert_profile);
/* Allowable ciphers */
- /* Since @SECLEVEL also influces loading of certificates, set the
+ /* Since @SECLEVEL also influences loading of certificates, set the
* cipher restrictions before loading certificates */
tls_ctx_restrict_ciphers(new_ctx, options->cipher_list);
+ tls_ctx_restrict_ciphers_tls13(new_ctx, options->cipher_list_tls13);
if (!tls_ctx_set_options(new_ctx, options->ssl_flags))
{
bool tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags);
/**
- * Restrict the list of ciphers that can be used within the TLS context.
+ * Restrict the list of ciphers that can be used within the TLS context for TLS 1.2
+ * and below
*
* @param ctx TLS context to restrict, must be valid.
* @param ciphers String containing : delimited cipher names, or NULL to use
*/
void tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers);
+/**
+ * Restrict the list of ciphers that can be used within the TLS context for TLS 1.3
+ * and higher
+ *
+ * @param ctx TLS context to restrict, must be valid.
+ * @param ciphers String containing : delimited cipher names, or NULL to use
+ * sane defaults.
+ */
+void tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers);
+
/**
* Set the TLS certificate profile. The profile defines which crypto
* algorithms may be used in the supplied certificate.
return pair->iana_name;
}
+void
+tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers)
+{
+ if (ciphers == NULL)
+ {
+ /* Nothing to do, return without warning message */
+ return;
+ }
+
+ msg(M_WARN, "mbed TLS does not support setting tls-ciphersuites. "
+ "Ignoring TLS 1.3 cipher list: %s", ciphers);
+}
+
void
tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
{
}
}
+void
+convert_tls13_list_to_openssl(char* openssl_ciphers, size_t len, const char *ciphers)
+{
+ /*
+ * OpenSSL (and official IANA) cipher names have _ in them. We
+ * historically used names with - in them. Silently convert names
+ * with - to names with _ to support both
+ */
+ if (strlen(ciphers) >= (len - 1))
+ {
+ msg(M_FATAL,
+ "Failed to set restricted TLS 1.3 cipher list, too long (>%d).",
+ (int) (len - 1));
+ }
+
+ strncpy(openssl_ciphers, ciphers, len);
+
+ for (size_t i = 0; i < strlen(openssl_ciphers); i++)
+ {
+ if (openssl_ciphers[i] == '-')
+ {
+ openssl_ciphers[i] = '_';
+ }
+ }
+}
+
+void
+tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers)
+{
+ if (ciphers == NULL)
+ {
+ /* default cipher list of OpenSSL 1.1.1 is sane, do not set own
+ * default as we do with tls-cipher */
+ return;
+ }
+
+#if (OPENSSL_VERSION_NUMBER < 0x1010100fL)
+ crypto_msg(M_WARN, "Not compiled with OpenSSL 1.1.1 or higher. "
+ "Ignoring TLS 1.3 only tls-ciphersuites '%s' setting.",
+ ciphers);
+#else
+ ASSERT(NULL != ctx);
+
+ char openssl_ciphers[4096];
+ convert_tls13_list_to_openssl(openssl_ciphers, sizeof(openssl_ciphers),
+ ciphers);
+
+ if (!SSL_CTX_set_ciphersuites(ctx->ctx, openssl_ciphers))
+ {
+ crypto_msg(M_FATAL, "Failed to set restricted TLS 1.3 cipher list: %s",
+ openssl_ciphers);
+ }
+#endif
+}
+
void
tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile)
{
projects / thirdparty / openvpn.git / commitdiff
