[src/trunk]: src/sys Don't wait until the pool *fills* to rekey anything that...

[tls <tls%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/903fe1712c58
branches:  trunk
changeset: 781424:903fe1712c58
user:      tls <tls%NetBSD.org@localhost>
date:      Wed Sep 05 18:57:33 2012 +0000

description:
Don't wait until the pool *fills* to rekey anything that was keyed with
insufficient entropy at boot: key it as soon as it makes any request after
we hit the minimum entropy threshold.

This too should help avoid predictable output at boot time.

diffstat:

 sys/kern/kern_rndq.c  |  14 +++++++-------
 sys/kern/subr_cprng.c |  12 +++++++++---
 sys/sys/rnd.h         |   3 ++-
 3 files changed, 18 insertions(+), 11 deletions(-)

diffs (118 lines):

diff -r 8250c8e80e6d -r 903fe1712c58 sys/kern/kern_rndq.c
--- a/sys/kern/kern_rndq.c      Wed Sep 05 18:06:52 2012 +0000
+++ b/sys/kern/kern_rndq.c      Wed Sep 05 18:57:33 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_rndq.c,v 1.4 2012/09/05 18:06:52 tls Exp $        */
+/*     $NetBSD: kern_rndq.c,v 1.5 2012/09/05 18:57:34 tls Exp $        */
 
 /*-
  * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.4 2012/09/05 18:06:52 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_rndq.c,v 1.5 2012/09/05 18:57:34 tls Exp $");
 
 #include <sys/param.h>
 #include <sys/ioctl.h>
@@ -168,7 +168,7 @@
                                        uint32_t, uint32_t, uint32_t);
 
 int                    rnd_ready = 0;
-static int             rnd_have_entropy = 0;
+int                    rnd_initial_entropy = 0;
 
 #ifdef DIAGNOSTIC
 static int             rnd_tested = 0;
@@ -255,11 +255,11 @@
         */
        if (rndpool_get_entropy_count(&rnd_pool) > RND_ENTROPY_THRESHOLD * 8) {
 #ifdef RND_VERBOSE
-               if (!rnd_have_entropy)
+               if (!rnd_initial_entropy)
                        printf("rnd: have initial entropy (%u)\n",
                               rndpool_get_entropy_count(&rnd_pool));
 #endif
-               rnd_have_entropy = 1;
+               rnd_initial_entropy = 1;
                mutex_spin_exit(&rndpool_mtx);
        } else {
                mutex_spin_exit(&rndpool_mtx);
@@ -447,7 +447,7 @@
                                             RND_POOLBITS / 2));
                if (rndpool_get_entropy_count(&rnd_pool) >
                    RND_ENTROPY_THRESHOLD * 8) {
-                       rnd_have_entropy = 1;
+                       rnd_initial_entropy = 1;
                }
                 mutex_spin_exit(&rndpool_mtx);
 #ifdef RND_VERBOSE
@@ -914,7 +914,7 @@
                }
                timed_in++;
        }
-       if (__predict_false(!rnd_have_entropy)) {
+       if (__predict_false(!rnd_initial_entropy)) {
                u_int32_t c;
 
 #ifdef RND_VERBOSE
diff -r 8250c8e80e6d -r 903fe1712c58 sys/kern/subr_cprng.c
--- a/sys/kern/subr_cprng.c     Wed Sep 05 18:06:52 2012 +0000
+++ b/sys/kern/subr_cprng.c     Wed Sep 05 18:57:33 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_cprng.c,v 1.9 2012/05/19 16:00:41 tls Exp $ */
+/*     $NetBSD: subr_cprng.c,v 1.10 2012/09/05 18:57:34 tls Exp $ */
 
 /*-
  * Copyright (c) 2011 The NetBSD Foundation, Inc.
@@ -46,7 +46,7 @@
 
 #include <sys/cprng.h>
 
-__KERNEL_RCSID(0, "$NetBSD: subr_cprng.c,v 1.9 2012/05/19 16:00:41 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_cprng.c,v 1.10 2012/09/05 18:57:34 tls Exp $");
 
 void
 cprng_init(void)
@@ -171,7 +171,7 @@
        c->reseed.state = RSTATE_IDLE;
        c->reseed.cb = cprng_strong_reseed;
        c->reseed.arg = c;
-       c->entropy_serial = rnd_filled;
+       c->entropy_serial = rnd_initial_entropy ? rnd_filled : -1;
        mutex_init(&c->reseed.mtx, MUTEX_DEFAULT, IPL_VM);
        strlcpy(c->reseed.name, name, sizeof(c->reseed.name));
 
@@ -228,8 +228,14 @@
        }
        mutex_enter(&c->mtx);
 
+       /* If we were initialized with the pool empty, rekey ASAP */
+       if (__predict_false(c->entropy_serial == -1) && rnd_initial_entropy) {
+               goto rekeyany;          /* We have _some_ entropy, use it. */
+       }
+               
        if (nist_ctr_drbg_generate(&c->drbg, p, len, &cc, sizeof(cc))) {
                /* A generator failure really means we hit the hard limit. */
+rekeyany:
                if (c->flags & CPRNG_REKEY_ANY) {
                        uint8_t key[NIST_BLOCK_KEYLEN_BYTES];
 
diff -r 8250c8e80e6d -r 903fe1712c58 sys/sys/rnd.h
--- a/sys/sys/rnd.h     Wed Sep 05 18:06:52 2012 +0000
+++ b/sys/sys/rnd.h     Wed Sep 05 18:57:33 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rnd.h,v 1.32 2012/04/20 21:57:34 tls Exp $     */
+/*     $NetBSD: rnd.h,v 1.33 2012/09/05 18:57:33 tls Exp $     */
 
 /*-
  * Copyright (c) 1997 The NetBSD Foundation, Inc.
@@ -187,6 +187,7 @@
 
 extern int     rnd_full;
 extern int     rnd_filled;
+extern int     rnd_initial_entropy;
 
 #endif /* _KERNEL */