Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

2026-04-24 00:00:05 +08:00 · 2020-02-24 14:43:11 +03:00
parent 133b3756e6 86cc97e55f
commit 32f1555929
655 changed files with 146468 additions and 0 deletions
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+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    This program is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+// General-purpose OpenVPN protocol encrypt method (CBC/HMAC) that is independent of the underlying CRYPTO_API
+
+#ifndef OPENVPN_CRYPTO_ENCRYPT_CHM_H
+#define OPENVPN_CRYPTO_ENCRYPT_CHM_H
+
+#include <cstring>
+#include <utility>
+
+#include <openvpn/common/size.hpp>
+#include <openvpn/common/exception.hpp>
+#include <openvpn/buffer/buffer.hpp>
+#include <openvpn/random/randapi.hpp>
+#include <openvpn/frame/frame.hpp>
+#include <openvpn/crypto/cipher.hpp>
+#include <openvpn/crypto/ovpnhmac.hpp>
+#include <openvpn/crypto/static_key.hpp>
+#include <openvpn/crypto/packet_id.hpp>
+
+namespace openvpn {
+  template <typename CRYPTO_API>
+  class EncryptCHM {
+  public:
+    OPENVPN_SIMPLE_EXCEPTION(chm_unsupported_cipher_mode);
+
+    void encrypt(BufferAllocated& buf, const PacketID::time_t now)
+    {
+      // skip null packets
+      if (!buf.size())
+	return;
+
+      if (cipher.defined())
+	{
+	  // workspace for generating IV
+	  unsigned char iv_buf[CRYPTO_API::CipherContext::MAX_IV_LENGTH];
+	  const size_t iv_length = cipher.iv_length();
+
+	  // IV and packet ID are generated differently depending on cipher mode
+	  const int cipher_mode = cipher.cipher_mode();
+	  if (cipher_mode == CRYPTO_API::CipherContext::CIPH_CBC_MODE)
+	    {
+	      // in CBC mode, use an explicit, random IV
+	      prng->rand_bytes(iv_buf, iv_length);
+
+	      // generate fresh outgoing packet ID and prepend to cleartext buffer
+	      pid_send.write_next(buf, true, now);
+	    }
+	  else
+	    {
+	      throw chm_unsupported_cipher_mode();
+	    }
+
+	  // initialize work buffer
+	  frame->prepare(Frame::ENCRYPT_WORK, work);
+
+	  // encrypt from buf -> work
+	  const size_t encrypt_bytes = cipher.encrypt(iv_buf, work.data(), work.max_size(), buf.c_data(), buf.size());
+	  if (!encrypt_bytes)
+	    {
+	      buf.reset_size();
+	      return;
+	    }
+	  work.set_size(encrypt_bytes);
+
+	  // prepend the IV to the ciphertext
+	  work.prepend(iv_buf, iv_length);
+
+	  // HMAC the ciphertext
+	  prepend_hmac(work);
+
+	  // return ciphertext result in buf
+	  buf.swap(work);
+	}
+      else // no encryption
+	{
+	  // generate fresh outgoing packet ID and prepend to cleartext buffer
+	  pid_send.write_next(buf, true, now);
+
+	  // HMAC the cleartext
+	  prepend_hmac(buf);
+	}
+    }
+
+    void set_prng(RandomAPI::Ptr prng_arg)
+    {
+      prng_arg->assert_crypto();
+      prng = std::move(prng_arg);
+    }
+
+    Frame::Ptr frame;
+    CipherContext<CRYPTO_API> cipher;
+    OvpnHMAC<CRYPTO_API> hmac;
+    PacketIDSend pid_send;
+
+  private:
+    // compute HMAC signature of data buffer,
+    // then prepend the signature to the buffer.
+    void prepend_hmac(BufferAllocated& buf)
+    {
+      if (hmac.defined())
+	{
+	  const unsigned char *content = buf.data();
+	  const size_t content_size = buf.size();
+	  const size_t hmac_size = hmac.output_size();
+	  unsigned char *hmac_buf = buf.prepend_alloc(hmac_size);
+	  hmac.hmac(hmac_buf, hmac_size, content, content_size);
+	}
+    }
+
+    BufferAllocated work;
+    RandomAPI::Ptr prng;
+  };
+
+} // namespace openvpn
+
+#endif // OPENVPN_CRYPTO_ENCRYPT_H