Revert to OpenSSL (#233)

* Use an OpenSSL binary without Bitcode
* Restore TLS security level override
* Disable Bitcode completely in Demo

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Changed
+
+- Revert to OpenSSL. [#233](https://github.com/passepartoutvpn/tunnelkit/pull/233)
+
 ## 4.0.1 (2021-11-18)
 
 ### Fixed

Demo/TunnelKit.xcodeproj/project.pbxproj

@@ -884,6 +884,7 @@
 				COPY_PHASE_STRIP = NO;
 				CURRENT_PROJECT_VERSION = 902;
 				DEBUG_INFORMATION_FORMAT = dwarf;
+				ENABLE_BITCODE = NO;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
 				ENABLE_TESTABILITY = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu11;
@@ -949,6 +950,7 @@
 				COPY_PHASE_STRIP = NO;
 				CURRENT_PROJECT_VERSION = 902;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
+				ENABLE_BITCODE = NO;
 				ENABLE_NS_ASSERTIONS = NO;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu11;

Package.resolved

@@ -2,21 +2,12 @@
   "object": {
     "pins": [
       {
-        "package": "swift-nio",
+        "package": "openssl-apple",
-        "repositoryURL": "https://github.com/apple/swift-nio.git",
+        "repositoryURL": "https://github.com/passepartoutvpn/openssl-apple",
         "state": {
           "branch": null,
-          "revision": "addf69cfe60376c325397c8926589415576b1dd1",
+          "revision": "7fe4127c8ef5a06a2040f521ff1b4c2a9a38f417",
-          "version": "2.34.0"
+          "version": "1.1.112-no-bitcode"
-        }
-      },
-      {
-        "package": "swift-nio-ssl",
-        "repositoryURL": "https://github.com/apple/swift-nio-ssl",
-        "state": {
-          "branch": null,
-          "revision": "08e701df9a3b9108c56f1aef5d9ef9a78fda2846",
-          "version": "2.16.2"
         }
       },
       {

Package.swift

@@ -35,7 +35,7 @@ let package = Package(
         // Dependencies declare other packages that this package depends on.
         // .package(url: /* package url */, from: "1.0.0"),
         .package(url: "https://github.com/SwiftyBeaver/SwiftyBeaver", from: "1.9.0"),
-        .package(url: "https://github.com/apple/swift-nio-ssl", from: "2.0.0")
+        .package(url: "https://github.com/passepartoutvpn/openssl-apple", .exact("1.1.112-no-bitcode"))
     ],
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
@@ -124,7 +124,7 @@ let package = Package(
             dependencies: [
                 "CTunnelKitCore",
                 "CTunnelKitOpenVPNCore",
-                .product(name: "NIOSSL", package: "swift-nio-ssl")
+                "openssl-apple"
             ]),
         .target(
             name: "__TunnelKitUtils",

README.md

@@ -1,10 +1,10 @@
-![iOS 12+](https://img.shields.io/badge/ios-12+-green.svg)
+![iOS 11+](https://img.shields.io/badge/ios-11+-green.svg)
 ![macOS 10.15+](https://img.shields.io/badge/macos-10.15+-green.svg)
 [![License GPLv3](https://img.shields.io/badge/license-GPLv3-lightgray.svg)](LICENSE)
 
 # TunnelKit
 
-This library provides a generic framework for VPN development and a simplified Swift/Obj-C implementation of the OpenVPN® protocol for the Apple platforms. The crypto layer is built on top of [BoringSSL][dep-boringssl] (as seen in [SwiftNIO SSL][dep-swiftniossl]), which in turn enables support for a certain range of encryption and digest algorithms.
+This library provides a generic framework for VPN development and a simplified Swift/Obj-C implementation of the OpenVPN® protocol for the Apple platforms. The crypto layer is built on top of [OpenSSL 1.1.1][dep-openssl], which in turn enables support for a certain range of encryption and digest algorithms.
 
 ## Getting started
 
@@ -70,12 +70,14 @@ Many other flags are ignored too but it's normally not an issue.
 
 ### Requirements
 
-- iOS 13.0+ / macOS 10.15+
+- iOS 11.0+ / macOS 10.15+
 - SwiftPM 5.3
 - Git (preinstalled with Xcode Command Line Tools)
 
 It's highly recommended to use the Git package provided by [Homebrew][dep-brew].
 
+Make sure to disable Bitcode in "Release" targets (iOS), otherwise the library [would not be able to locate OpenSSL][about-pr-bitcode].
+
 ### Demo
 
 Download the library codebase locally:
@@ -142,7 +144,7 @@ Here you find `NativeProvider`, a generic way to manage a VPN profile based on t
 
 #### Protocol
 
-Here are the low-level entities on top of which an OpenVPN connection is established. Code is mixed Swift and Obj-C, most of it is not exposed to consumers. The protocol implementation in particular depends on BoringSSL.
+Here are the low-level entities on top of which an OpenVPN connection is established. Code is mixed Swift and Obj-C, most of it is not exposed to consumers. The protocol implementation in particular depends on OpenSSL.
 
 The entry point is the `OpenVPNSession` class. The networking layer is fully abstract and delegated externally with the use of opaque `IOInterface` (`LinkInterface` and `TunnelInterface`) and `OpenVPNSessionDelegate` protocols.
 
@@ -162,7 +164,7 @@ Due to the restrictive license (GPLv2), LZO support is provided as an optional c
 
 ## License
 
-Copyright (c) 2020 Davide De Rosa. All rights reserved.
+Copyright (c) 2021 Davide De Rosa. All rights reserved.
 
 ### Part I
 
@@ -205,8 +207,6 @@ Website: [passepartoutvpn.app][about-website]
 [openvpn]: https://openvpn.net/index.php/open-source/overview.html
 
 [dep-brew]: https://brew.sh/
-[dep-boringssl]: https://boringssl.googlesource.com/boringssl/
-[dep-swiftniossl]: https://github.com/apple/swift-nio-ssl
 [dep-openssl]: https://www.openssl.org/
 
 [ne-home]: https://developer.apple.com/documentation/networkextension
@@ -227,6 +227,7 @@ Website: [passepartoutvpn.app][about-website]
 [ppl-xmb5]: https://github.com/XMB5
 [ppl-xmb5-xor]: https://github.com/passepartoutvpn/tunnelkit/pull/170
 [about-tunnelblick-xor]: https://tunnelblick.net/cOpenvpn_xorpatch.html
+[about-pr-bitcode]: https://github.com/passepartoutvpn/tunnelkit/issues/51
 
 [about-twitter]: https://twitter.com/keeshux
 [about-website]: https://passepartoutvpn.app

Sources/CTunnelKitOpenVPNProtocol/CryptoAEAD.m

@@ -34,7 +34,7 @@
 //      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-@import CNIOBoringSSL;
+#import <openssl/evp.h>
 
 #import "CryptoAEAD.h"
 #import "CryptoMacros.h"

Sources/CTunnelKitOpenVPNProtocol/CryptoBox.m

@@ -34,7 +34,9 @@
 //      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-@import CNIOBoringSSL;
+#import <openssl/evp.h>
+#import <openssl/hmac.h>
+#import <openssl/rand.h>
 
 #import "CryptoBox.h"
 #import "CryptoMacros.h"
@@ -168,7 +170,7 @@
     int code = 1;
 
     HMAC_CTX *ctx = HMAC_CTX_new();
-    HMAC_CTX_reset(ctx);
+    TUNNEL_CRYPTO_TRACK_STATUS(code) HMAC_CTX_reset(ctx);
     TUNNEL_CRYPTO_TRACK_STATUS(code) HMAC_Init_ex(ctx, secret, (int)secretLength, EVP_get_digestbyname([digestName cStringUsingEncoding:NSASCIIStringEncoding]), NULL);
     TUNNEL_CRYPTO_TRACK_STATUS(code) HMAC_Update(ctx, data, dataLength);
     TUNNEL_CRYPTO_TRACK_STATUS(code) HMAC_Final(ctx, hmac, &l);

Sources/CTunnelKitOpenVPNProtocol/CryptoCBC.m

@@ -34,7 +34,9 @@
 //      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-@import CNIOBoringSSL;
+#import <openssl/evp.h>
+#import <openssl/hmac.h>
+#import <openssl/rand.h>
 
 #import "CryptoCBC.h"
 #import "CryptoMacros.h"

Sources/CTunnelKitOpenVPNProtocol/CryptoCTR.m

@@ -23,7 +23,8 @@
 //  along with TunnelKit.  If not, see <http://www.gnu.org/licenses/>.
 //
 
-@import CNIOBoringSSL;
+#import <openssl/evp.h>
+#import <openssl/hmac.h>
 
 #import "CryptoCTR.h"
 #import "CryptoMacros.h"

Sources/CTunnelKitOpenVPNProtocol/TLSBox.m

@@ -34,7 +34,9 @@
 //      THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-@import CNIOBoringSSL;
+#import <openssl/ssl.h>
+#import <openssl/x509v3.h>
+#import <openssl/err.h>
 
 #import "TLSBox.h"
 #import "Allocation.h"
@@ -56,6 +58,8 @@ int TLSBoxVerifyPeer(int ok, X509_STORE_CTX *ctx) {
     return ok;
 }
 
+const NSInteger TLSBoxDefaultSecurityLevel = 0;
+
 @interface TLSBox ()
 
 @property (nonatomic, strong) NSString *caPath;
@@ -179,6 +183,7 @@ int TLSBoxVerifyPeer(int ok, X509_STORE_CTX *ctx) {
         self.checksEKU = checksEKU;
         self.checksSANHost = checksSANHost;
         self.bufferCipherText = allocate_safely(TLSBoxMaxBufferLength);
+        self.securityLevel = TLSBoxDefaultSecurityLevel;
         self.hostname = hostname;
     }
     return self;
@@ -205,6 +210,10 @@ int TLSBoxVerifyPeer(int ok, X509_STORE_CTX *ctx) {
     self.ctx = SSL_CTX_new(TLS_client_method());
     SSL_CTX_set_options(self.ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_COMPRESSION);
     SSL_CTX_set_verify(self.ctx, SSL_VERIFY_PEER, TLSBoxVerifyPeer);
+    if (self.securityLevel != TLSBoxDefaultSecurityLevel) {
+        SSL_CTX_set_security_level(self.ctx, (int)self.securityLevel);
+    }
+
     if (!SSL_CTX_load_verify_locations(self.ctx, [self.caPath cStringUsingEncoding:NSASCIIStringEncoding], NULL)) {
         ERR_print_errors_fp(stdout);
         if (error) {

Sources/CTunnelKitOpenVPNProtocol/include/TLSBox.h

@@ -42,6 +42,8 @@ extern const NSInteger TLSBoxMaxBufferLength;
 
 extern NSString *const TLSBoxPeerVerificationErrorNotification;
 
+extern const NSInteger TLSBoxDefaultSecurityLevel;
+
 //
 // cipher text is safe within NSData
 // plain text might be sensitive and must avoid NSData
@@ -50,6 +52,8 @@ extern NSString *const TLSBoxPeerVerificationErrorNotification;
 //
 @interface TLSBox : NSObject
 
+@property (nonatomic, assign) NSInteger securityLevel; // TLSBoxDefaultSecurityLevel for default
+
 + (nullable NSString *)md5ForCertificatePath:(NSString *)path error:(NSError **)error;
 + (nullable NSString *)decryptedPrivateKeyFromPath:(NSString *)path passphrase:(NSString *)passphrase error:(NSError **)error;
 + (nullable NSString *)decryptedPrivateKeyFromPEM:(NSString *)pem passphrase:(NSString *)passphrase error:(NSError **)error;

Sources/TunnelKitOpenVPNCore/Configuration.swift

@@ -201,6 +201,9 @@ extension OpenVPN {
         /// The optional TLS wrapping.
         public var tlsWrap: TLSWrap?
         
+        /// If set, overrides TLS security level (0 = lowest).
+        public var tlsSecurityLevel: Int?
+
         /// Sends periodical keep-alive packets if set.
         public var keepAliveInterval: TimeInterval?
         
@@ -316,6 +319,7 @@ extension OpenVPN {
                 clientCertificate: clientCertificate,
                 clientKey: clientKey,
                 tlsWrap: tlsWrap,
+                tlsSecurityLevel: tlsSecurityLevel,
                 keepAliveInterval: keepAliveInterval,
                 keepAliveTimeout: keepAliveTimeout,
                 renegotiatesAfter: renegotiatesAfter,
@@ -394,6 +398,9 @@ extension OpenVPN {
         /// - Seealso: `ConfigurationBuilder.tlsWrap`
         public let tlsWrap: TLSWrap?
 
+        /// - Seealso: `ConfigurationBuilder.tlsSecurityLevel`
+        public let tlsSecurityLevel: Int?
+
         /// - Seealso: `ConfigurationBuilder.keepAliveInterval`
         public let keepAliveInterval: TimeInterval?
         
@@ -508,6 +515,7 @@ extension OpenVPN.Configuration {
         builder.clientCertificate = clientCertificate
         builder.clientKey = clientKey
         builder.tlsWrap = tlsWrap
+        builder.tlsSecurityLevel = tlsSecurityLevel
         builder.keepAliveInterval = keepAliveInterval
         builder.keepAliveTimeout = keepAliveTimeout
         builder.renegotiatesAfter = renegotiatesAfter
@@ -565,6 +573,11 @@ extension OpenVPN.Configuration {
         } else {
             log.info("\tTLS wrapping: disabled")
         }
+        if let tlsSecurityLevel = tlsSecurityLevel {
+            log.info("\tTLS security level: \(tlsSecurityLevel)")
+        } else {
+            log.info("\tTLS security level: default")
+        }
         if let keepAliveSeconds = keepAliveInterval, keepAliveSeconds > 0 {
             log.info("\tKeep-alive interval: \(keepAliveSeconds.asTimeString)")
         } else {

Sources/TunnelKitOpenVPNProtocol/OpenVPNSession.swift

@@ -796,6 +796,9 @@ public class OpenVPNSession: Session {
                 checksSANHost: configuration.checksSANHost ?? false,
                 hostname: configuration.sanHost
             )
+            if let tlsSecurityLevel = configuration.tlsSecurityLevel {
+                tls.securityLevel = tlsSecurityLevel
+            }
             negotiationKey.tlsOptional = tls
             do {
                 try negotiationKey.tls.start()