--- /dev/null
+/* Copyright (c) 2017, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/ssl.h>
+
+#include <assert.h>
+
+#include <openssl/bytestring.h>
+#include <openssl/err.h>
+
+#include "internal.h"
+#include "../crypto/internal.h"
+
+
+namespace bssl {
+
+bool ssl_protocol_version_from_wire(uint16_t *out, uint16_t version) {
+ switch (version) {
+ case SSL3_VERSION:
+ case TLS1_VERSION:
+ case TLS1_1_VERSION:
+ case TLS1_2_VERSION:
+ *out = version;
+ return true;
+
+ case TLS1_3_DRAFT23_VERSION:
+ *out = TLS1_3_VERSION;
+ return true;
+
+ case DTLS1_VERSION:
+ // DTLS 1.0 is analogous to TLS 1.1, not TLS 1.0.
+ *out = TLS1_1_VERSION;
+ return true;
+
+ case DTLS1_2_VERSION:
+ *out = TLS1_2_VERSION;
+ return true;
+
+ default:
+ return false;
+ }
+}
+
+// The follow arrays are the supported versions for TLS and DTLS, in order of
+// decreasing preference.
+
+static const uint16_t kTLSVersions[] = {
+ TLS1_3_DRAFT23_VERSION,
+ TLS1_2_VERSION,
+ TLS1_1_VERSION,
+ TLS1_VERSION,
+ SSL3_VERSION,
+};
+
+static const uint16_t kDTLSVersions[] = {
+ DTLS1_2_VERSION,
+ DTLS1_VERSION,
+};
+
+static void get_method_versions(const SSL_PROTOCOL_METHOD *method,
+ const uint16_t **out, size_t *out_num) {
+ if (method->is_dtls) {
+ *out = kDTLSVersions;
+ *out_num = OPENSSL_ARRAY_SIZE(kDTLSVersions);
+ } else {
+ *out = kTLSVersions;
+ *out_num = OPENSSL_ARRAY_SIZE(kTLSVersions);
+ }
+}
+
+static bool method_supports_version(const SSL_PROTOCOL_METHOD *method,
+ uint16_t version) {
+ const uint16_t *versions;
+ size_t num_versions;
+ get_method_versions(method, &versions, &num_versions);
+ for (size_t i = 0; i < num_versions; i++) {
+ if (versions[i] == version) {
+ return true;
+ }
+ }
+ return false;
+}
+
+// The following functions map between API versions and wire versions. The
+// public API works on wire versions, except that TLS 1.3 draft versions all
+// appear as TLS 1.3. This will get collapsed back down when TLS 1.3 is
+// finalized.
+
+static const char *ssl_version_to_string(uint16_t version) {
+ switch (version) {
+ case TLS1_3_DRAFT23_VERSION:
+ return "TLSv1.3";
+
+ case TLS1_2_VERSION:
+ return "TLSv1.2";
+
+ case TLS1_1_VERSION:
+ return "TLSv1.1";
+
+ case TLS1_VERSION:
+ return "TLSv1";
+
+ case SSL3_VERSION:
+ return "SSLv3";
+
+ case DTLS1_VERSION:
+ return "DTLSv1";
+
+ case DTLS1_2_VERSION:
+ return "DTLSv1.2";
+
+ default:
+ return "unknown";
+ }
+}
+
+static uint16_t wire_version_to_api(uint16_t version) {
+ switch (version) {
+ // Report TLS 1.3 draft versions as TLS 1.3 in the public API.
+ case TLS1_3_DRAFT23_VERSION:
+ return TLS1_3_VERSION;
+ default:
+ return version;
+ }
+}
+
+// api_version_to_wire maps |version| to some representative wire version. In
+// particular, it picks an arbitrary TLS 1.3 representative. This should only be
+// used in context where that does not matter.
+static bool api_version_to_wire(uint16_t *out, uint16_t version) {
+ if (version == TLS1_3_DRAFT23_VERSION) {
+ return false;
+ }
+ if (version == TLS1_3_VERSION) {
+ version = TLS1_3_DRAFT23_VERSION;
+ }
+
+ // Check it is a real protocol version.
+ uint16_t unused;
+ if (!ssl_protocol_version_from_wire(&unused, version)) {
+ return false;
+ }
+
+ *out = version;
+ return true;
+}
+
+static bool set_version_bound(const SSL_PROTOCOL_METHOD *method, uint16_t *out,
+ uint16_t version) {
+ if (!api_version_to_wire(&version, version) ||
+ !method_supports_version(method, version) ||
+ !ssl_protocol_version_from_wire(out, version)) {
+ OPENSSL_PUT_ERROR(SSL, SSL_R_UNKNOWN_SSL_VERSION);
+ return false;
+ }
+
+ return true;
+}
+
+static bool set_min_version(const SSL_PROTOCOL_METHOD *method, uint16_t *out,
+ uint16_t version) {
+ // Zero is interpreted as the default minimum version.
+ if (version == 0) {
+ // SSL 3.0 is disabled by default and TLS 1.0 does not exist in DTLS.
+ *out = method->is_dtls ? TLS1_1_VERSION : TLS1_VERSION;
+ return true;
+ }
+
+ return set_version_bound(method, out, version);
+}
+
+static bool set_max_version(const SSL_PROTOCOL_METHOD *method, uint16_t *out,
+ uint16_t version) {
+ // Zero is interpreted as the default maximum version.
+ if (version == 0) {
+ *out = TLS1_2_VERSION;
+ return true;
+ }
+
+ return set_version_bound(method, out, version);
+}
+
+const struct {
+ uint16_t version;
+ uint32_t flag;
+} kProtocolVersions[] = {
+ {SSL3_VERSION, SSL_OP_NO_SSLv3},
+ {TLS1_VERSION, SSL_OP_NO_TLSv1},
+ {TLS1_1_VERSION, SSL_OP_NO_TLSv1_1},
+ {TLS1_2_VERSION, SSL_OP_NO_TLSv1_2},
+ {TLS1_3_VERSION, SSL_OP_NO_TLSv1_3},
+};
+
+bool ssl_get_version_range(const SSL *ssl, uint16_t *out_min_version,
+ uint16_t *out_max_version) {
+ // For historical reasons, |SSL_OP_NO_DTLSv1| aliases |SSL_OP_NO_TLSv1|, but
+ // DTLS 1.0 should be mapped to TLS 1.1.
+ uint32_t options = ssl->options;
+ if (SSL_is_dtls(ssl)) {
+ options &= ~SSL_OP_NO_TLSv1_1;
+ if (options & SSL_OP_NO_DTLSv1) {
+ options |= SSL_OP_NO_TLSv1_1;
+ }
+ }
+
+ uint16_t min_version = ssl->conf_min_version;
+ uint16_t max_version = ssl->conf_max_version;
+
+ // OpenSSL's API for controlling versions entails blacklisting individual
+ // protocols. This has two problems. First, on the client, the protocol can
+ // only express a contiguous range of versions. Second, a library consumer
+ // trying to set a maximum version cannot disable protocol versions that get
+ // added in a future version of the library.
+ //
+ // To account for both of these, OpenSSL interprets the client-side bitmask
+ // as a min/max range by picking the lowest contiguous non-empty range of
+ // enabled protocols. Note that this means it is impossible to set a maximum
+ // version of the higest supported TLS version in a future-proof way.
+ bool any_enabled = false;
+ for (size_t i = 0; i < OPENSSL_ARRAY_SIZE(kProtocolVersions); i++) {
+ // Only look at the versions already enabled.
+ if (min_version > kProtocolVersions[i].version) {
+ continue;
+ }
+ if (max_version < kProtocolVersions[i].version) {
+ break;
+ }
+
+ if (!(options & kProtocolVersions[i].flag)) {
+ // The minimum version is the first enabled version.
+ if (!any_enabled) {
+ any_enabled = true;
+ min_version = kProtocolVersions[i].version;
+ }
+ continue;
+ }
+
+ // If there is a disabled version after the first enabled one, all versions
+ // after it are implicitly disabled.
+ if (any_enabled) {
+ max_version = kProtocolVersions[i-1].version;
+ break;
+ }
+ }
+
+ if (!any_enabled) {
+ OPENSSL_PUT_ERROR(SSL, SSL_R_NO_SUPPORTED_VERSIONS_ENABLED);
+ return false;
+ }
+
+ *out_min_version = min_version;
+ *out_max_version = max_version;
+ return true;
+}
+
+static uint16_t ssl_version(const SSL *ssl) {
+ // In early data, we report the predicted version.
+ if (SSL_in_early_data(ssl) && !ssl->server) {
+ return ssl->s3->hs->early_session->ssl_version;
+ }
+ return ssl->version;
+}
+
+uint16_t ssl_protocol_version(const SSL *ssl) {
+ assert(ssl->s3->have_version);
+ uint16_t version;
+ if (!ssl_protocol_version_from_wire(&version, ssl->version)) {
+ // |ssl->version| will always be set to a valid version.
+ assert(0);
+ return 0;
+ }
+
+ return version;
+}
+
+bool ssl_supports_version(SSL_HANDSHAKE *hs, uint16_t version) {
+ SSL *const ssl = hs->ssl;
+ uint16_t protocol_version;
+ if (!method_supports_version(ssl->method, version) ||
+ !ssl_protocol_version_from_wire(&protocol_version, version) ||
+ hs->min_version > protocol_version ||
+ protocol_version > hs->max_version) {
+ return false;
+ }
+
+ // This logic is part of the TLS 1.3 variants mechanism used in TLS 1.3
+ // experimentation. Although we currently only have one variant, TLS 1.3 does
+ // not a final stable deployment yet, so leave the logic in place for now.
+ if (protocol_version != TLS1_3_VERSION ||
+ (ssl->tls13_variant == tls13_default &&
+ version == TLS1_3_DRAFT23_VERSION)) {
+ return true;
+ }
+
+ // The server, when not configured at |tls13_default|, should additionally
+ // enable all variants.
+ if (ssl->server && ssl->tls13_variant != tls13_default) {
+ return true;
+ }
+
+ return false;
+}
+
+bool ssl_add_supported_versions(SSL_HANDSHAKE *hs, CBB *cbb) {
+ const uint16_t *versions;
+ size_t num_versions;
+ get_method_versions(hs->ssl->method, &versions, &num_versions);
+ for (size_t i = 0; i < num_versions; i++) {
+ if (ssl_supports_version(hs, versions[i]) &&
+ !CBB_add_u16(cbb, versions[i])) {
+ return false;
+ }
+ }
+ return true;
+}
+
+bool ssl_negotiate_version(SSL_HANDSHAKE *hs, uint8_t *out_alert,
+ uint16_t *out_version, const CBS *peer_versions) {
+ const uint16_t *versions;
+ size_t num_versions;
+ get_method_versions(hs->ssl->method, &versions, &num_versions);
+ for (size_t i = 0; i < num_versions; i++) {
+ if (!ssl_supports_version(hs, versions[i])) {
+ continue;
+ }
+
+ CBS copy = *peer_versions;
+ while (CBS_len(©) != 0) {
+ uint16_t version;
+ if (!CBS_get_u16(©, &version)) {
+ OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+ *out_alert = SSL_AD_DECODE_ERROR;
+ return false;
+ }
+
+ if (version == versions[i]) {
+ *out_version = version;
+ return true;
+ }
+ }
+ }
+
+ OPENSSL_PUT_ERROR(SSL, SSL_R_UNSUPPORTED_PROTOCOL);
+ *out_alert = SSL_AD_PROTOCOL_VERSION;
+ return false;
+}
+
+} // namespace bssl
+
+using namespace bssl;
+
+int SSL_CTX_set_min_proto_version(SSL_CTX *ctx, uint16_t version) {
+ return set_min_version(ctx->method, &ctx->conf_min_version, version);
+}
+
+int SSL_CTX_set_max_proto_version(SSL_CTX *ctx, uint16_t version) {
+ return set_max_version(ctx->method, &ctx->conf_max_version, version);
+}
+
+int SSL_set_min_proto_version(SSL *ssl, uint16_t version) {
+ return set_min_version(ssl->method, &ssl->conf_min_version, version);
+}
+
+int SSL_set_max_proto_version(SSL *ssl, uint16_t version) {
+ return set_max_version(ssl->method, &ssl->conf_max_version, version);
+}
+
+int SSL_version(const SSL *ssl) {
+ return wire_version_to_api(ssl_version(ssl));
+}
+
+const char *SSL_get_version(const SSL *ssl) {
+ return ssl_version_to_string(ssl_version(ssl));
+}
+
+const char *SSL_SESSION_get_version(const SSL_SESSION *session) {
+ return ssl_version_to_string(session->ssl_version);
+}
+
+uint16_t SSL_SESSION_get_protocol_version(const SSL_SESSION *session) {
+ return wire_version_to_api(session->ssl_version);
+}
+
+int SSL_SESSION_set_protocol_version(SSL_SESSION *session, uint16_t version) {
+ // This picks a representative TLS 1.3 version, but this API should only be
+ // used on unit test sessions anyway.
+ return api_version_to_wire(&session->ssl_version, version);
+}
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