Merge GH #947 Add support for getentropy syscall

5 files changed, 79 insertions, 1 deletions

diff --git a/src/build-data/buildh.in b/src/build-data/buildh.in
index 1c389fe02..393bcc4fb 100644
--- a/src/build-data/buildh.in
+++ b/src/build-data/buildh.in
@@ -122,7 +122,7 @@
 * seriously broken system RNG.
 */
 #define BOTAN_ENTROPY_DEFAULT_SOURCES \
-   { "rdseed", "rdrand", "darwin_secrandom", "dev_random", \
+   { "rdseed", "rdrand", "darwin_secrandom", "getentropy", "dev_random", \
     "win32_cryptoapi", "proc_walk", "system_stats" }
 
 
diff --git a/src/lib/entropy/entropy_srcs.cpp b/src/lib/entropy/entropy_srcs.cpp
index 252be4fa1..d9d5cfe4b 100644
--- a/src/lib/entropy/entropy_srcs.cpp
+++ b/src/lib/entropy/entropy_srcs.cpp
@@ -36,6 +36,10 @@
   #include <botan/internal/darwin_secrandom.h>
 #endif
 
+#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
+  #include <botan/internal/getentropy.h>
+#endif
+
 namespace Botan {
 
 std::unique_ptr<Entropy_Source> Entropy_Source::create(const std::string& name)
@@ -61,6 +65,13 @@ std::unique_ptr<Entropy_Source> Entropy_Source::create(const std::string& name)
 #endif
       }
 
+   if(name == "getentropy")
+      {
+#if defined(BOTAN_HAS_ENTROPY_SRC_GETENTROPY)
+      return std::unique_ptr<Entropy_Source>(new Getentropy);
+#endif
+      }
+
    if(name == "dev_random")
       {
 #if defined(BOTAN_HAS_ENTROPY_SRC_DEV_RANDOM)
diff --git a/src/lib/entropy/getentropy/getentropy.cpp b/src/lib/entropy/getentropy/getentropy.cpp
new file mode 100644
index 000000000..56c356eba
--- /dev/null
+++ b/src/lib/entropy/getentropy/getentropy.cpp
@@ -0,0 +1,30 @@
+/*
+* System Call getentropy(2)
+* (C) 2017 Alexander Bluhm (genua GmbH)
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#include <botan/internal/getentropy.h>
+
+#include <unistd.h>
+
+namespace Botan {
+
+/**
+* Gather BOTAN_SYSTEM_RNG_POLL_REQUEST bytes entropy from getentropy(2).
+* This is 64 bytes, note that maximum buffer size is limited to 256 bytes.
+*/
+size_t Getentropy::poll(RandomNumberGenerator& rng)
+   {
+   secure_vector<uint8_t> buf(BOTAN_SYSTEM_RNG_POLL_REQUEST);
+
+   if(::getentropy(buf.data(), buf.size()) == 0)
+      {
+      rng.add_entropy(buf.data(), buf.size());
+      return buf.size() * 8;
+      }
+
+   return 0;
+   }
+}
diff --git a/src/lib/entropy/getentropy/getentropy.h b/src/lib/entropy/getentropy/getentropy.h
new file mode 100644
index 000000000..ebc49320b
--- /dev/null
+++ b/src/lib/entropy/getentropy/getentropy.h
@@ -0,0 +1,28 @@
+/*
+* Entropy Source Using OpenBSD getentropy(2) system call
+* (C) 2017 Alexander Bluhm (genua GmbH)
+*
+* Botan is released under the Simplified BSD License (see license.txt)
+*/
+
+#ifndef BOTAN_ENTROPY_SRC_GETENTROPY_H__
+#define BOTAN_ENTROPY_SRC_GETENTROPY_H__
+
+#include <botan/entropy_src.h>
+
+namespace Botan {
+
+/**
+* Entropy source using the getentropy(2) sustem call first introduced in
+* OpenBSD 5.6 and added to Solaris 11.3.
+*/
+class Getentropy final : public Entropy_Source
+   {
+   public:
+      std::string name() const override { return "getentropy"; }
+      size_t poll(RandomNumberGenerator& rng) override;
+   };
+
+}
+
+#endif
diff --git a/src/lib/entropy/getentropy/info.txt b/src/lib/entropy/getentropy/info.txt
new file mode 100644
index 000000000..89e7b120d
--- /dev/null
+++ b/src/lib/entropy/getentropy/info.txt
@@ -0,0 +1,9 @@
+define ENTROPY_SRC_GETENTROPY 20170327
+
+<header:internal>
+getentropy.h
+</header:internal>
+
+<os>
+openbsd
+</os>