Module Name: src
Committed By: tls
Date: Sat May 19 16:00:41 UTC 2012
Modified Files:
src/sys/dev: rndpseudo.c
src/sys/kern: subr_cprng.c
Log Message:
Fix two problems that could cause /dev/random to not wake up readers when
entropy became available.
To generate a diff of this commit:
cvs rdiff -u -r1.9 -r1.10 src/sys/dev/rndpseudo.c
cvs rdiff -u -r1.8 -r1.9 src/sys/kern/subr_cprng.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/rndpseudo.c
diff -u src/sys/dev/rndpseudo.c:1.9 src/sys/dev/rndpseudo.c:1.10
--- src/sys/dev/rndpseudo.c:1.9 Fri Apr 20 21:57:33 2012
+++ src/sys/dev/rndpseudo.c Sat May 19 16:00:41 2012
@@ -1,4 +1,4 @@
-/* $NetBSD: rndpseudo.c,v 1.9 2012/04/20 21:57:33 tls Exp $ */
+/* $NetBSD: rndpseudo.c,v 1.10 2012/05/19 16:00:41 tls Exp $ */
/*-
* Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.9 2012/04/20 21:57:33 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: rndpseudo.c,v 1.10 2012/05/19 16:00:41 tls Exp $");
#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
@@ -309,14 +309,23 @@ rnd_read(struct file * fp, off_t *offp,
/* XXX is this _really_ what's wanted? */
if (ctx->hard) {
n = MIN(want, strength - ctx->bytesonkey);
- ctx->bytesonkey += n;
+ if (n < 1) {
+ cprng_strong_deplete(cprng);
+ n = MIN(want, strength);
+ ctx->bytesonkey = 0;
+ membar_producer();
+ }
} else {
n = want;
}
nread = cprng_strong(cprng, bf, n,
(fp->f_flag & FNONBLOCK) ? FNONBLOCK : 0);
- if (nread != n) {
+
+ if (ctx->hard && nread > 0) {
+ atomic_add_int(&ctx->bytesonkey, nread);
+ }
+ if (nread < 1) {
if (fp->f_flag & FNONBLOCK) {
ret = EWOULDBLOCK;
} else {
@@ -331,12 +340,6 @@ rnd_read(struct file * fp, off_t *offp,
}
}
out:
- if (ctx->bytesonkey >= strength) {
- /* Force reseed of underlying DRBG (prediction resistance) */
- cprng_strong_deplete(cprng);
- ctx->bytesonkey = 0;
- }
-
pool_cache_put(rp_pc, bf);
return (ret);
}
Index: src/sys/kern/subr_cprng.c
diff -u src/sys/kern/subr_cprng.c:1.8 src/sys/kern/subr_cprng.c:1.9
--- src/sys/kern/subr_cprng.c:1.8 Tue Apr 17 02:50:39 2012
+++ src/sys/kern/subr_cprng.c Sat May 19 16:00:41 2012
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_cprng.c,v 1.8 2012/04/17 02:50:39 tls Exp $ */
+/* $NetBSD: subr_cprng.c,v 1.9 2012/05/19 16:00:41 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 1.8 2012/04/17 02:50:39 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_cprng.c,v 1.9 2012/05/19 16:00:41 tls Exp $");
void
cprng_init(void)
@@ -144,6 +144,9 @@ cprng_strong_reseed(void *const arg)
#ifdef RND_VERBOSE
printf("cprng: sink %s cprng busy, no reseed\n", c->reseed.name);
#endif
+ if (c->flags & CPRNG_USE_CV) { /* XXX if flags change? */
+ cv_broadcast(&c->cv);
+ }
return;
}
@@ -240,23 +243,32 @@ cprng_strong(cprng_strong_t *const c, vo
"failed.", c->name);
}
} else {
- if (!(flags & FNONBLOCK) &&
- (c->flags & CPRNG_USE_CV)) {
- int wr;
+ int wr;
+ do {
cprng_strong_sched_reseed(c);
- do {
- wr = cv_wait_sig(&c->cv, &c->mtx);
- if (wr == ERESTART) {
- mutex_exit(&c->mtx);
- return 0;
- }
- } while (nist_ctr_drbg_generate(&c->drbg, p,
- len, &cc,
- sizeof(cc)));
- } else {
- len = 0;
- }
+ if ((flags & FNONBLOCK) ||
+ !(c->flags & CPRNG_USE_CV)) {
+ len = 0;
+ break;
+ }
+ /*
+ * XXX There's a race with the cv_broadcast
+ * XXX in cprng_strong_sched_reseed, because
+ * XXX of the use of tryenter in that function.
+ * XXX This "timedwait" hack works around it,
+ * XXX at the expense of occasionaly polling
+ * XXX for success on a /dev/random rekey.
+ */
+ wr = cv_timedwait_sig(&c->cv, &c->mtx,
+ mstohz(100));
+ if (wr == ERESTART) {
+ mutex_exit(&c->mtx);
+ return 0;
+ }
+ } while (nist_ctr_drbg_generate(&c->drbg, p,
+ len, &cc,
+ sizeof(cc)));
}
}
