- (djm) [openbsd-compat/Makefile.in openbsd-compat/arc4random.c]

   [openbsd-compat/bsd-arc4random.c] Replace old RC4-based arc4random
   implementation with recent OpenBSD's ChaCha-based PRNG. ok dtucker@,
   tested tim@

1 files changed, 46 insertions, 13 deletions

diff --git a/openbsd-compat/arc4random.c b/openbsd-compat/arc4random.c
index 356e23181..eac073cc0 100644
--- a/openbsd-compat/arc4random.c
+++ b/openbsd-compat/arc4random.c
@@ -1,3 +1,5 @@
+/* OPENBSD ORIGINAL: lib/libc/crypto/arc4random.c */
+
 /*      $OpenBSD: arc4random.c,v 1.25 2013/10/01 18:34:57 markus Exp $  */
 
 /*
@@ -22,16 +24,19 @@
  * ChaCha based random number generator for OpenBSD.
  */
 
-#include <fcntl.h>
-#include <limits.h>
+#include "includes.h"
+
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/types.h>
-#include <sys/param.h>
-#include <sys/time.h>
-#include <sys/sysctl.h>
-#include "thread_private.h"
+
+#ifndef HAVE_ARC4RANDOM
+
+#include <openssl/rand.h>
+#include <openssl/err.h>
+
+#include "log.h"
 
 #define KEYSTREAM_ONLY
 #include "chacha_private.h"
@@ -42,6 +47,10 @@
 #define inline
 #endif                          /* !__GNUC__ */
 
+/* OpenSSH isn't multithreaded */
+#define _ARC4_LOCK()
+#define _ARC4_UNLOCK()
+
 #define KEYSZ   32
 #define IVSZ    8
 #define BLOCKSZ 64
@@ -67,15 +76,11 @@ _rs_init(u_char *buf, size_t n)
 static void
 _rs_stir(void)
 {
-        int     mib[2];
-        size_t  len;
         u_char rnd[KEYSZ + IVSZ];
 
-        mib[0] = CTL_KERN;
-        mib[1] = KERN_ARND;
-
-        len = sizeof(rnd);
-        sysctl(mib, 2, rnd, &len, NULL, 0);
+        if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
+                fatal("Couldn't obtain random bytes (error %ld)",
+                    ERR_get_error());
 
         if (!rs_initialized) {
                 rs_initialized = 1;
@@ -194,6 +199,11 @@ arc4random(void)
         return val;
 }
 
+/*
+ * If we are providing arc4random, then we can provide a more efficient 
+ * arc4random_buf().
+ */
+# ifndef HAVE_ARC4RANDOM_BUF
 void
 arc4random_buf(void *buf, size_t n)
 {
@@ -201,7 +211,29 @@ arc4random_buf(void *buf, size_t n)
         _rs_random_buf(buf, n);
         _ARC4_UNLOCK();
 }
+# endif /* !HAVE_ARC4RANDOM_BUF */
+#endif /* !HAVE_ARC4RANDOM */
+
+/* arc4random_buf() that uses platform arc4random() */
+#if !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM)
+void
+arc4random_buf(void *_buf, size_t n)
+{
+        size_t i;
+        u_int32_t r = 0;
+        char *buf = (char *)_buf;
+
+        for (i = 0; i < n; i++) {
+                if (i % 4 == 0)
+                        r = arc4random();
+                buf[i] = r & 0xff;
+                r >>= 8;
+        }
+        i = r = 0;
+}
+#endif /* !defined(HAVE_ARC4RANDOM_BUF) && defined(HAVE_ARC4RANDOM) */
 
+#ifndef HAVE_ARC4RANDOM_UNIFORM
 /*
  * Calculate a uniformly distributed random number less than upper_bound
  * avoiding "modulo bias".
@@ -237,6 +269,7 @@ arc4random_uniform(u_int32_t upper_bound)
 
         return r % upper_bound;
 }
+#endif /* !HAVE_ARC4RANDOM_UNIFORM */
 
 #if 0
 /*-------- Test code for i386 --------*/