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

Sources/OpenVPN3/openvpn/crypto/ovpnhmac.hpp

@@ -0,0 +1,240 @@
+//    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/>.
+
+// OpenVPN HMAC classes
+
+#ifndef OPENVPN_CRYPTO_OVPNHMAC_H
+#define OPENVPN_CRYPTO_OVPNHMAC_H
+
+#include <string>
+
+#include <openvpn/common/size.hpp>
+#include <openvpn/common/exception.hpp>
+#include <openvpn/common/rc.hpp>
+#include <openvpn/common/memneq.hpp>
+#include <openvpn/crypto/static_key.hpp>
+#include <openvpn/crypto/cryptoalgs.hpp>
+
+namespace openvpn {
+
+  // OpenVPN protocol HMAC usage for HMAC/CBC integrity checking and tls-auth
+
+  template <typename CRYPTO_API>
+  class OvpnHMAC
+  {
+  public:
+    OPENVPN_SIMPLE_EXCEPTION(ovpn_hmac_context_digest_size);
+    OPENVPN_SIMPLE_EXCEPTION(ovpn_hmac_context_bad_sizing);
+
+  public:
+    OvpnHMAC() {}
+
+    OvpnHMAC(const CryptoAlgs::Type digest, const StaticKey& key)
+    {
+      init(digest, key);
+    }
+
+    bool defined() const { return ctx.is_initialized(); }
+
+    // size of out buffer to pass to hmac
+    size_t output_size() const
+    {
+      return ctx.size();
+    }
+
+    void init(const CryptoAlgs::Type digest, const StaticKey& key)
+    {
+      const CryptoAlgs::Alg& alg = CryptoAlgs::get(digest);
+
+      // check that key is large enough
+      if (key.size() < alg.size())
+	throw ovpn_hmac_context_digest_size();
+
+      // initialize HMAC context with digest type and key
+      ctx.init(digest, key.data(), alg.size());
+    }
+
+    void hmac(unsigned char *out, const size_t out_size,
+	      const unsigned char *in, const size_t in_size)
+    {
+      ctx.reset();
+      ctx.update(in, in_size);
+      ctx.final(out);
+    }
+
+    // Special HMAC for OpenVPN control packets
+
+    void ovpn_hmac_gen(unsigned char *data, const size_t data_size,
+		       const size_t l1, const size_t l2, const size_t l3)
+    {
+      if (ovpn_hmac_pre(data, data_size, l1, l2, l3))
+	ctx.final(data + l1);
+      else
+	throw ovpn_hmac_context_bad_sizing();
+    }
+
+    // verify the HMAC generated by ovpn_hmac_gen, return true if verified
+    bool ovpn_hmac_cmp(const unsigned char *data, const size_t data_size,
+		       const size_t l1, const size_t l2, const size_t l3)
+    {
+      unsigned char local_hmac[CRYPTO_API::HMACContext::MAX_HMAC_SIZE];
+      if (ovpn_hmac_pre(data, data_size, l1, l2, l3))
+	{
+	  ctx.final(local_hmac);
+	  return !crypto::memneq(data + l1, local_hmac, l2);
+	}
+      else
+	return false;
+    }
+
+  private:
+    // Convoluting OpenVPN control channel packets for HMAC:
+    // <-- L1  -->   <-L2>   <L3>
+    // [OP]  [PSID]  [HMAC]  [PID] [...]  -> canonical order
+    //
+    // [HMAC] [PID] [OP] [PSID] [...]     -> HMAC order
+
+    bool ovpn_hmac_pre(const unsigned char *data, const size_t data_size,
+		       const size_t l1, const size_t l2, const size_t l3)
+    {
+      const size_t lsum = l1 + l2 + l3;
+      if (lsum > data_size || l2 != ctx.size())
+	return false;
+      ctx.reset();
+      ctx.update(data + l1 + l2, l3);
+      ctx.update(data, l1);
+      ctx.update(data + lsum, data_size - lsum);
+      return true;
+    }
+
+    typename CRYPTO_API::HMACContext ctx;
+  };
+
+  // OvpnHMAC wrapper API using dynamic polymorphism
+
+  class OvpnHMACInstance : public RC<thread_unsafe_refcount>
+  {
+  public:
+    typedef RCPtr<OvpnHMACInstance> Ptr;
+
+    virtual void init(const StaticKey& key) = 0;
+
+    virtual size_t output_size() const = 0;
+
+    virtual void ovpn_hmac_gen(unsigned char *data, const size_t data_size,
+			       const size_t l1, const size_t l2, const size_t l3) = 0;
+
+    virtual bool ovpn_hmac_cmp(const unsigned char *data, const size_t data_size,
+			       const size_t l1, const size_t l2, const size_t l3) = 0;
+  };
+
+  class OvpnHMACContext : public RC<thread_unsafe_refcount>
+  {
+  public:
+    typedef RCPtr<OvpnHMACContext> Ptr;
+
+    virtual size_t size() const = 0;
+
+    virtual OvpnHMACInstance::Ptr new_obj() = 0;
+  };
+
+  class OvpnHMACFactory : public RC<thread_unsafe_refcount>
+  {
+  public:
+    typedef RCPtr<OvpnHMACFactory> Ptr;
+
+    virtual OvpnHMACContext::Ptr new_obj(const CryptoAlgs::Type digest_type) = 0;
+  };
+
+  // OvpnHMAC wrapper implementation using dynamic polymorphism
+
+  template <typename CRYPTO_API>
+  class CryptoOvpnHMACInstance : public OvpnHMACInstance
+  {
+  public:
+    CryptoOvpnHMACInstance(const CryptoAlgs::Type digest_arg)
+      : digest(digest_arg)
+    {
+    }
+
+    virtual void init(const StaticKey& key)
+    {
+      ovpn_hmac.init(digest, key);
+    }
+
+    virtual size_t output_size() const
+    {
+      return ovpn_hmac.output_size();
+    }
+
+    virtual void ovpn_hmac_gen(unsigned char *data, const size_t data_size,
+			       const size_t l1, const size_t l2, const size_t l3)
+    {
+      ovpn_hmac.ovpn_hmac_gen(data, data_size, l1, l2, l3);
+    }
+
+    virtual bool ovpn_hmac_cmp(const unsigned char *data, const size_t data_size,
+			       const size_t l1, const size_t l2, const size_t l3)
+    {
+      return ovpn_hmac.ovpn_hmac_cmp(data, data_size, l1, l2, l3);
+    }
+
+  private:
+    typename CryptoAlgs::Type digest;
+    OvpnHMAC<CRYPTO_API> ovpn_hmac;
+  };
+
+  template <typename CRYPTO_API>
+  class CryptoOvpnHMACContext : public OvpnHMACContext
+  {
+  public:
+    CryptoOvpnHMACContext(const CryptoAlgs::Type digest_type)
+      : digest(CryptoAlgs::legal_dc_digest(digest_type))
+    {
+    }
+
+    virtual size_t size() const
+    {
+      return CryptoAlgs::size(digest);
+    }
+
+    virtual OvpnHMACInstance::Ptr new_obj()
+    {
+      return new CryptoOvpnHMACInstance<CRYPTO_API>(digest);
+    }
+
+  private:
+    CryptoAlgs::Type digest;
+  };
+
+  template <typename CRYPTO_API>
+  class CryptoOvpnHMACFactory : public OvpnHMACFactory
+  {
+  public:
+    virtual OvpnHMACContext::Ptr new_obj(const CryptoAlgs::Type digest_type)
+    {
+      return new CryptoOvpnHMACContext<CRYPTO_API>(digest_type);
+    }
+  };
+
+}
+
+#endif