Change _rs_allocate so it can combine the two regions (rs and rsx)

into one if a system has an awesome getentropy().  In that case it
is valid to totally throw away the rsx state in the child.  If the
getentropy() is not very good and has a lazy reseed operation, this
combining is a bad idea, and the reseed should probably continue to
use the "something old, something new" mix.  _rs_allocate() can
accomodate either method, but not on the fly.
ok matthew

1 files changed, 8 insertions, 14 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
index d42022c455..3c80beb3b9 100644
--- a/src/lib/libc/crypt/arc4random.c
+++ b/src/lib/libc/crypt/arc4random.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random.c,v 1.47 2014/07/18 02:05:55 deraadt Exp $ */
+/*      $OpenBSD: arc4random.c,v 1.48 2014/07/19 00:08:41 deraadt Exp $ */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -57,17 +57,16 @@ static struct _rs {
         size_t          rs_count;       /* bytes till reseed */
 } *rs;
 
-static inline void *_rs_allocate(size_t len);
-static inline void _rs_forkdetect(void);
-static inline void _rs_forkdetectsetup(struct _rs *buf, size_t len);
-#include "arc4random.h"
-
-/* Preserved in fork children. */
-static struct {
+/* Maybe be preserved in fork children, if _rs_allocate() decides. */
+static struct _rsx {
         chacha_ctx      rs_chacha;      /* chacha context for random keystream */
         u_char          rs_buf[RSBUFSZ];        /* keystream blocks */
 } *rsx;
 
+static inline int _rs_allocate(struct _rs **, struct _rsx **);
+static inline void _rs_forkdetect(void);
+#include "arc4random.h"
+
 static inline void _rs_rekey(u_char *dat, size_t datlen);
 
 static inline void
@@ -77,12 +76,7 @@ _rs_init(u_char *buf, size_t n)
                 return;
 
         if (rs == NULL) {
-                if ((rs = _rs_allocate(sizeof(*rs))) == NULL)
-                        abort();
-                _rs_forkdetectsetup(rs, sizeof(*rs));
-        }
-        if (rsx == NULL) {
-                if ((rsx = _rs_allocate(sizeof(*rsx))) == NULL)
+                if (_rs_allocate(&rs, &rsx) == -1)
                         abort();
         }