From ef643cc7bdb24fbff4740192a7fc1fc768fb7693 Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Wed, 25 Dec 2013 15:00:39 +0000
Subject: [PATCH] Use rdrand as additional entropy source.

If available rdrand is used as an additional entropy source for the
PRNG and for additional input in FIPS mode.
---
 crypto/rand/md_rand.c  | 79 ++++++++++++++++++++++++++++++++++++++++++
 crypto/rand/rand_lcl.h |  1 +
 crypto/rand/rand_lib.c |  1 +
 3 files changed, 81 insertions(+)

diff --git a/crypto/rand/md_rand.c b/crypto/rand/md_rand.c
index 2d6a55f6ed..7158d30d8f 100644
--- a/crypto/rand/md_rand.c
+++ b/crypto/rand/md_rand.c
@@ -167,6 +167,8 @@ int rand_predictable=0;
 
 const char RAND_version[]="RAND" OPENSSL_VERSION_PTEXT;
 
+static void rand_hw_seed(EVP_MD_CTX *ctx);
+
 static void ssleay_rand_cleanup(void);
 static int ssleay_rand_seed(const void *buf, int num);
 static int ssleay_rand_add(const void *buf, int num, double add_entropy);
@@ -531,6 +533,7 @@ static int ssleay_rand_bytes(unsigned char *buf, int num, int pseudo)
 				       sizeof tv))
 				goto err;
 			curr_time = 0;
+			rand_hw_seed(&m);
 			}
 		if (!MD_Update(&m,local_md,MD_DIGEST_LENGTH))
 			goto err;
@@ -663,3 +666,79 @@ static int ssleay_rand_status(void)
 	
 	return ret;
 	}
+
+/* rand_hw_seed: get seed data from any available hardware RNG.
+ * only currently supports rdrand.
+ */
+
+/* Adapted from eng_rdrand.c */
+
+#if (defined(__i386)   || defined(__i386__)   || defined(_M_IX86) || \
+     defined(__x86_64) || defined(__x86_64__) || \
+     defined(_M_AMD64) || defined (_M_X64)) && defined(OPENSSL_CPUID_OBJ)
+
+#define RDRAND_CALLS	4
+
+size_t OPENSSL_ia32_rdrand(void);
+extern unsigned int OPENSSL_ia32cap_P[];
+
+static void rand_hw_seed(EVP_MD_CTX *ctx)
+	{
+	int i;
+	if (!(OPENSSL_ia32cap_P[1] & (1<<(62-32))))
+		return;
+	for (i = 0; i < RDRAND_CALLS; i++)
+		{
+		size_t rnd;
+		rnd = OPENSSL_ia32_rdrand();
+		if (rnd == 0)
+			return;
+		MD_Update(ctx, (unsigned char *)rnd, sizeof(size_t));
+		}
+	}
+
+/* XOR an existing buffer with random data */
+
+void rand_hw_xor(unsigned char *buf, size_t num)
+	{
+	size_t rnd;
+	if (!(OPENSSL_ia32cap_P[1] & (1<<(62-32))))
+		return;
+	while (num >= sizeof(size_t))
+		{
+		rnd = OPENSSL_ia32_rdrand();
+		if (rnd == 0)
+			return;
+		*((size_t *)buf) ^= rnd;
+		buf += sizeof(size_t);
+		num -= sizeof(size_t);
+		}
+	if (num)
+		{
+		rnd = OPENSSL_ia32_rdrand();
+		if (rnd == 0)
+			return;
+		while(num)
+			{
+			*buf ^= rnd & 0xff;
+			rnd >>= 8;
+			buf++;
+			num--;
+			}
+		}
+	}
+
+
+#else
+
+static void rand_hw_seed(EVP_MD_CTX *ctx)
+	{
+	return;
+	}
+
+void rand_hw_xor(unsigned char *buf, size_t num)
+	{
+	return;
+	}
+
+#endif
diff --git a/crypto/rand/rand_lcl.h b/crypto/rand/rand_lcl.h
index 618a8ec899..6696b8057b 100644
--- a/crypto/rand/rand_lcl.h
+++ b/crypto/rand/rand_lcl.h
@@ -154,5 +154,6 @@
 #define	MD(a,b,c)		EVP_Digest(a,b,c,NULL,EVP_md2(), NULL)
 #endif
 
+void rand_hw_xor(unsigned char *buf, size_t num);
 
 #endif
diff --git a/crypto/rand/rand_lib.c b/crypto/rand/rand_lib.c
index e8957dbb30..4aa6486c81 100644
--- a/crypto/rand/rand_lib.c
+++ b/crypto/rand/rand_lib.c
@@ -227,6 +227,7 @@ static size_t drbg_get_adin(DRBG_CTX *ctx, unsigned char **pout)
 	static unsigned char buf[16];
 	static unsigned long counter;
 	FIPS_get_timevec(buf, &counter);
+	rand_hw_xor(buf, sizeof(buf));
 	*pout = buf;
 	return sizeof(buf);
 	}
-- 
2.25.1