Provide RNG_WEAK quality random generator in rdrand

src/libstrongswan/plugins/rdrand/rdrand_rng.c

@@ -0,0 +1,277 @@
+/*
+ * Copyright (C) 2012 Martin Willi
+ * Copyright (C) 2012 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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 General Public License
+ * for more details.
+ */
+
+#include "rdrand_rng.h"
+
+typedef struct private_rdrand_rng_t private_rdrand_rng_t;
+
+/**
+ * Private data of an rdrand_rng_t object.
+ */
+struct private_rdrand_rng_t {
+
+	/**
+	 * Public rdrand_rng_t interface.
+	 */
+	rdrand_rng_t public;
+
+	/**
+	 * Quality we produce RNG data
+	 */
+	rng_quality_t quality;
+};
+
+/**
+ * Retries for failed RDRAND instructions
+ */
+#define MAX_TRIES 16
+
+/**
+ * Get a two byte word using RDRAND
+ */
+static bool rdrand16(u_int16_t *out)
+{
+	u_char res;
+	int i;
+
+	for (i = 0; i < MAX_TRIES; i++)
+	{
+		asm("rdrand %0;"
+			"setc %1;"
+			: "=r"(*out), "=qm"(res));
+
+		if (res)
+		{
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+/**
+ * Get a four byte word using RDRAND
+ */
+static bool rdrand32(u_int32_t *out)
+{
+	u_char res;
+	int i;
+
+	for (i = 0; i < MAX_TRIES; i++)
+	{
+		asm("rdrand %0;"
+			"setc %1;"
+			: "=r"(*out), "=qm"(res));
+
+		if (res)
+		{
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+#ifdef __x86_64__
+/**
+ * Get a eight byte word using RDRAND
+ */
+static bool rdrand64(u_int64_t *out)
+{
+	u_char res;
+	int i;
+
+	for (i = 0; i < MAX_TRIES; i++)
+	{
+		asm("rdrand %0;"
+			"setc %1;"
+			: "=r"(*out), "=qm"(res));
+
+		if (res)
+		{
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+#endif /* __x86_64__ */
+
+/**
+ * Get a one byte word using RDRAND
+ */
+static bool rdrand8(u_int8_t *out)
+{
+	u_int16_t u16;
+
+	if (!rdrand16(&u16))
+	{
+		return FALSE;
+	}
+	*out = u16;
+	return TRUE;
+}
+
+METHOD(rng_t, get_bytes, bool,
+	private_rdrand_rng_t *this, size_t bytes, u_int8_t *buffer)
+{
+	chunk_t chunk;
+
+	chunk = chunk_create(buffer, bytes);
+
+	/* align to 2 byte */
+	if (chunk.len >= sizeof(u_int8_t))
+	{
+		if ((uintptr_t)chunk.ptr % 2)
+		{
+			if (!rdrand8((u_int8_t*)chunk.ptr))
+			{
+				return FALSE;
+			}
+			chunk = chunk_skip(chunk, sizeof(u_int8_t));
+		}
+	}
+
+	/* align to 4 byte */
+	if (chunk.len >= sizeof(u_int16_t))
+	{
+		if ((uintptr_t)chunk.ptr % 4)
+		{
+			if (!rdrand16((u_int16_t*)chunk.ptr))
+			{
+				return FALSE;
+			}
+			chunk = chunk_skip(chunk, sizeof(u_int16_t));
+		}
+	}
+
+#ifdef __x86_64__
+
+	/* align to 8 byte */
+	if (chunk.len >= sizeof(u_int32_t))
+	{
+		if ((uintptr_t)chunk.ptr % 8)
+		{
+			if (!rdrand32((u_int32_t*)chunk.ptr))
+			{
+				return FALSE;
+			}
+			chunk = chunk_skip(chunk, sizeof(u_int32_t));
+		}
+	}
+
+	/* fill with 8 byte words */
+	while (chunk.len >= sizeof(u_int64_t))
+	{
+		if (!rdrand64((u_int64_t*)chunk.ptr))
+		{
+			return FALSE;
+		}
+		chunk = chunk_skip(chunk, sizeof(u_int64_t));
+	}
+
+	/* append 4 byte word */
+	if (chunk.len >= sizeof(u_int32_t))
+	{
+		if (!rdrand32((u_int32_t*)chunk.ptr))
+		{
+			return FALSE;
+		}
+		chunk = chunk_skip(chunk, sizeof(u_int32_t));
+	}
+
+#else /* __i386__ */
+
+	/* fill with 4 byte words */
+	while (chunk.len >= sizeof(u_int32_t))
+	{
+		if (!rdrand32((u_int32_t*)chunk.ptr))
+		{
+			return FALSE;
+		}
+		chunk = chunk_skip(chunk, sizeof(u_int32_t));
+	}
+
+#endif /* __x86_64__ / __i386__ */
+
+	/* append 2 byte word */
+	if (chunk.len >= sizeof(u_int16_t))
+	{
+		if (!rdrand16((u_int16_t*)chunk.ptr))
+		{
+			return FALSE;
+		}
+		chunk = chunk_skip(chunk, sizeof(u_int16_t));
+	}
+
+	/* append 1 byte word */
+	if (chunk.len >= sizeof(u_int8_t))
+	{
+		if (!rdrand8((u_int8_t*)chunk.ptr))
+		{
+			return FALSE;
+		}
+		chunk = chunk_skip(chunk, sizeof(u_int8_t));
+	}
+
+	return TRUE;
+}
+
+METHOD(rng_t, allocate_bytes, bool,
+	private_rdrand_rng_t *this, size_t bytes, chunk_t *chunk)
+{
+	*chunk = chunk_alloc(bytes);
+	if (get_bytes(this, bytes, chunk->ptr))
+	{
+		return TRUE;
+	}
+	free(chunk->ptr);
+	return FALSE;
+}
+
+METHOD(rng_t, destroy, void,
+	private_rdrand_rng_t *this)
+{
+	free(this);
+}
+
+/*
+ * Described in header.
+ */
+rdrand_rng_t *rdrand_rng_create(rng_quality_t quality)
+{
+	private_rdrand_rng_t *this;
+
+	switch (quality)
+	{
+		case RNG_WEAK:
+			break;
+		case RNG_STRONG:
+		case RNG_TRUE:
+		default:
+			/* not yet */
+			return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.rng = {
+				.get_bytes = _get_bytes,
+				.allocate_bytes = _allocate_bytes,
+				.destroy = _destroy,
+			},
+		},
+		.quality = quality,
+	);
+
+	return &this->public;
+}