move chacha context and buffer out of bss and allow mmap to place them

wherever it decides it would like them. first step. ok deraadt dlg djm

src/lib/libc/crypt/arc4random.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: arc4random.c,v 1.27 2014/05/04 20:40:08 deraadt Exp $	*/
+/*	$OpenBSD: arc4random.c,v 1.28 2014/05/06 02:31:45 tedu Exp $	*/
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -31,6 +31,8 @@
 #include <sys/param.h>
 #include <sys/time.h>
 #include <sys/sysctl.h>
+#include <sys/mman.h>
+
 #include "thread_private.h"
 
 #define KEYSTREAM_ONLY
@@ -48,8 +50,8 @@
 #define RSBUFSZ	(16*BLOCKSZ)
 static int rs_initialized;
 static pid_t rs_stir_pid;
-static chacha_ctx rs;		/* chacha context for random keystream */
-static u_char rs_buf[RSBUFSZ];	/* keystream blocks */
+static chacha_ctx *rs;		/* chacha context for random keystream */
+static u_char *rs_buf;		/* keystream blocks */
 static size_t rs_have;		/* valid bytes at end of rs_buf */
 static size_t rs_count;		/* bytes till reseed */
 
@@ -60,8 +62,16 @@ _rs_init(u_char *buf, size_t n)
 {
 	if (n < KEYSZ + IVSZ)
 		return;
-	chacha_keysetup(&rs, buf, KEYSZ * 8, 0);
-	chacha_ivsetup(&rs, buf + KEYSZ);
+
+	if ((rs = mmap(NULL, sizeof(*rs), PROT_READ|PROT_WRITE,
+	    MAP_ANON, -1, 0)) == MAP_FAILED)
+		abort();
+	if ((rs_buf = mmap(NULL, RSBUFSZ, PROT_READ|PROT_WRITE,
+	    MAP_ANON, -1, 0)) == MAP_FAILED)
+		abort();
+
+	chacha_keysetup(rs, buf, KEYSZ * 8, 0);
+	chacha_ivsetup(rs, buf + KEYSZ);
 }
 
 static void
@@ -110,7 +120,7 @@ _rs_rekey(u_char *dat, size_t datlen)
 	memset(rs_buf, 0,RSBUFSZ);
 #endif
 	/* fill rs_buf with the keystream */
-	chacha_encrypt_bytes(&rs, rs_buf, rs_buf, RSBUFSZ);
+	chacha_encrypt_bytes(rs, rs_buf, rs_buf, RSBUFSZ);
 	/* mix in optional user provided data */
 	if (dat) {
 		size_t i, m;