Restructure tpm2.h to avoid external includes in public headers

randombit · Jun 14, 2024 · 2ab6008 · 2ab6008
1 parent ed26467
commit 2ab6008
Show file tree

Hide file tree

Showing 5 changed files with 76 additions and 29 deletions.
diff --git a/src/lib/prov/tpm2/info.txt b/src/lib/prov/tpm2/info.txt
@@ -17,6 +17,10 @@ all -> tss2-esys,tss2-rc,tss2-tctildr
 rng
 </requires>
 
+<header:internal>
+tpm2_util.h
+</header:internal>
+
 <header:public>
 tpm2.h
 tpm2_rng.h

diff --git a/src/lib/prov/tpm2/tpm2.cpp b/src/lib/prov/tpm2/tpm2.cpp
@@ -9,19 +9,27 @@
 #include <botan/tpm2.h>
 
 #include <botan/internal/fmt.h>
+#include <botan/internal/tpm2_util.h>
 
 #include <tss2/tss2_esys.h>
+#include <tss2/tss2_tcti.h>
 #include <tss2/tss2_tctildr.h>
 
 namespace Botan {
 
-TPM2_Error::TPM2_Error(std::string_view location, TSS2_RC rc) :
+TPM2_Error::TPM2_Error(std::string_view location, uint32_t rc) :
       Exception(fmt("TPM2 Exception in {}: Code {} ({})", location, rc, Tss2_RC_Decode(rc))), m_rc(rc) {}
 
 std::string TPM2_Error::error_message() const {
    return Tss2_RC_Decode(m_rc);
 }
 
+class TPM2_Context::Impl {
+   public:
+      TSS2_TCTI_CONTEXT* m_tcti_ctx;
+      ESYS_CONTEXT* m_ctx;
+};
+
 std::shared_ptr<TPM2_Context> TPM2_Context::create(std::optional<std::string> tcti_nameconf) {
    const auto tcti_nameconf_ptr = [&]() -> const char* {
       if(tcti_nameconf.has_value()) {
@@ -30,30 +38,42 @@ std::shared_ptr<TPM2_Context> TPM2_Context::create(std::optional<std::string> tc
          return nullptr;
       }
    }();
+   // We cannot std::make_shared as the constructor is private
    return std::shared_ptr<TPM2_Context>(new TPM2_Context(tcti_nameconf_ptr));
 }
 
-TPM2_Context::TPM2_Context(const char* tcti_nameconf) {
-   check_tss2_rc("TCTI Initialization", Tss2_TctiLdr_Initialize(tcti_nameconf, &m_tcti_ctx));
-   check_tss2_rc("TPM2 Initialization", Esys_Initialize(&m_ctx, m_tcti_ctx, nullptr /* ABI version */));
+TPM2_Context::TPM2_Context(const char* tcti_nameconf) : m_impl(std::make_unique<Impl>()) {
+   check_tss2_rc("TCTI Initialization", Tss2_TctiLdr_Initialize(tcti_nameconf, &m_impl->m_tcti_ctx));
+   check_tss2_rc("TPM2 Initialization", Esys_Initialize(&m_impl->m_ctx, m_impl->m_tcti_ctx, nullptr /* ABI version */));
 }
 
-TPM2_Context::TPM2_Context(TPM2_Context&& ctx) noexcept : m_ctx(ctx.m_ctx) {
-   ctx.m_ctx = nullptr;
+TPM2_Context::TPM2_Context(TPM2_Context&& ctx) noexcept {
+   m_impl->m_ctx = ctx.m_impl->m_ctx;
+   m_impl->m_tcti_ctx = ctx.m_impl->m_tcti_ctx;
+
+   ctx.m_impl->m_ctx = nullptr;
+   ctx.m_impl->m_tcti_ctx = nullptr;
 }
 
 TPM2_Context& TPM2_Context::operator=(TPM2_Context&& ctx) noexcept {
    if(this != &ctx) {
-      m_ctx = ctx.m_ctx;
-      ctx.m_ctx = nullptr;
+      m_impl->m_ctx = ctx.m_impl->m_ctx;
+      m_impl->m_tcti_ctx = ctx.m_impl->m_tcti_ctx;
+
+      ctx.m_impl->m_ctx = nullptr;
+      ctx.m_impl->m_tcti_ctx = nullptr;
    }
 
    return *this;
 }
 
+void* TPM2_Context::get() {
+   return m_impl->m_ctx;
+}
+
 TPM2_Context::~TPM2_Context() {
-   Esys_Finalize(&m_ctx);
-   Tss2_TctiLdr_Finalize(&m_tcti_ctx);
+   Esys_Finalize(&m_impl->m_ctx);
+   Tss2_TctiLdr_Finalize(&m_impl->m_tcti_ctx);
 }
 
 }  // namespace Botan
diff --git a/src/lib/prov/tpm2/tpm2.h b/src/lib/prov/tpm2/tpm2.h
@@ -11,21 +11,16 @@
 
 #include <botan/exceptn.h>
 
-#include <memory>
 #include <optional>
 
-#include <tss2/tss2_esys.h>
-#include <tss2/tss2_rc.h>
-#include <tss2/tss2_tctildr.h>
-
 namespace Botan {
 class BOTAN_PUBLIC_API(3, 6) TPM2_Error final : public Exception {
    public:
-      TPM2_Error(std::string_view location, TSS2_RC rc);
+      TPM2_Error(std::string_view location, uint32_t rc);
 
       ErrorType error_type() const noexcept override { return ErrorType::TPMError; }
 
-      TSS2_RC code() const { return m_rc; }
+      uint32_t code() const { return m_rc; }
 
       int error_code() const noexcept override {
          // RC is uint32 but the maximum value is within int32 range as per tss2_common.h
@@ -35,15 +30,9 @@ class BOTAN_PUBLIC_API(3, 6) TPM2_Error final : public Exception {
       std::string error_message() const;
 
    private:
-      TSS2_RC m_rc;
+      uint32_t m_rc;
 };
 
-inline void check_tss2_rc(std::string_view location, TSS2_RC rc) {
-   if(rc != TSS2_RC_SUCCESS) {
-      throw TPM2_Error(location, rc);
-   }
-}
-
 class BOTAN_PUBLIC_API(3, 6) TPM2_Context final {
    public:
       /**
@@ -59,14 +48,15 @@ class BOTAN_PUBLIC_API(3, 6) TPM2_Context final {
       TPM2_Context& operator=(const TPM2_Context&) = delete;
       TPM2_Context& operator=(TPM2_Context&& ctx) noexcept;
 
-      ESYS_CONTEXT* get() { return m_ctx; }
+      // Return an ESYS_CONTEXT* for use in other TPM2 functions.
+      void* get();
 
    private:
       TPM2_Context(const char* tcti_nameconf);
 
    private:
-      TSS2_TCTI_CONTEXT* m_tcti_ctx;
-      ESYS_CONTEXT* m_ctx;
+      class Impl;  // PImpl to avoid TPM2-TSS includes in this header
+      std::unique_ptr<Impl> m_impl;
 };
 
 }  // namespace Botan

diff --git a/src/lib/prov/tpm2/tpm2_rng.cpp b/src/lib/prov/tpm2/tpm2_rng.cpp
@@ -9,6 +9,7 @@
 #include <botan/tpm2_rng.h>
 
 #include <botan/internal/stl_util.h>
+#include <botan/internal/tpm2_util.h>
 
 #include <source_location>
 #include <tss2/tss2_esys.h>
@@ -25,15 +26,22 @@ void TPM2_RNG::fill_bytes_with_input(std::span<uint8_t> output, std::span<const
       data.size = std::min(in.remaining(), MAX_STIR_RANDOM_SIZE);
       in.copy_into({data.buffer, data.size});
 
-      check_tss2_rc("StirRandom", Esys_StirRandom(m_ctx->get(), ESYS_TR_NONE, ESYS_TR_NONE, ESYS_TR_NONE, &data));
+      check_tss2_rc(
+         "StirRandom",
+         Esys_StirRandom(static_cast<ESYS_CONTEXT*>(m_ctx->get()), ESYS_TR_NONE, ESYS_TR_NONE, ESYS_TR_NONE, &data));
    }
 
    BufferStuffer out(output);
    while(!out.full()) {
       TPM2B_DIGEST* digest = nullptr;
       const auto requested_bytes = std::min(sizeof(digest->buffer), out.remaining_capacity());
       check_tss2_rc("GetRandom",
-                    Esys_GetRandom(m_ctx->get(), ESYS_TR_NONE, ESYS_TR_NONE, ESYS_TR_NONE, requested_bytes, &digest));
+                    Esys_GetRandom(static_cast<ESYS_CONTEXT*>(m_ctx->get()),
+                                   ESYS_TR_NONE,
+                                   ESYS_TR_NONE,
+                                   ESYS_TR_NONE,
+                                   requested_bytes,
+                                   &digest));
 
       // Ensure Esys_Free(digest) is called even if assertions fail and we leave this block
       auto clean_buffer = scoped_cleanup([&digest] { Esys_Free(digest); });

diff --git a/src/lib/prov/tpm2/tpm2_util.h b/src/lib/prov/tpm2/tpm2_util.h
@@ -0,0 +1,25 @@
+/*
+* TPM 2 internal utilities
+* (C) 2024 Jack Lloyd
+* (C) 2024 René Meusel, Amos Treiber - Rohde & Schwarz Cybersecurity GmbH
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_TPM2_UTIL_H_
+#define BOTAN_TPM2_UTIL_H_
+
+#include <botan/tpm2.h>
+
+#include <tss2/tss2_rc.h>
+
+namespace Botan {
+
+inline void check_tss2_rc(std::string_view location, TSS2_RC rc) {
+   if(rc != TSS2_RC_SUCCESS) {
+      throw TPM2_Error(location, rc);
+   }
+}
+}  // namespace Botan
+
+#endif