On Sun, Jul 20, 2014 at 1:44 PM, Antti Kantee <[email protected]> wrote:
> On 20/07/14 11:47, Justin Cormack wrote:
>>>
>>> As a mid-term hack, might just make the implementation always read from
>>> /dev/urandom and return some sensible amount of data.
>>
>>
>> Attached is a suggested draft patch (only patrially tested) that
>> defaults to arc4random or /dev/urandom, but can be overridden,
>> supports a max read length, removes the flaky srand stuff, and shares
>> all the code between the standard and fiber implementations.
>
>
> What is the benefit of using arc4random? Why not just use urandom on all
> platforms all the time?
arc4random is more performant, has no failure cases, and on eg freebsd
/dev/urandom is just a symlink to /dev/random so thats probably not
what you want.
> I recognize the problem you are trying to solve, but I'm not convinced that
> adding switches and configuration variables is the right way -- it almost
> never is. For one, I think we are at least morally obliged to keep
> supporting all sorts of configuration switches and variables we introduce.
> Also, RUMP_FOO makes me think they apply to _all_ platforms, not just
> userspace. As a general note, we should make it obvious if a parameter
> applies to rump kernels on any platforms, or is platform specific.
>
> Again, I'd use the part from your patch where /dev/urandom is used, and
> strip out the rest. _If_ some actual problems appear from the use of
> /dev/urandom, we can try to apply band-aid and bubblegum. But, really,
> should try to fix the issue properly by looking at the NetBSD kernel side of
> the code, and thinking how to best make it cope with short-lived,
> multi-instance virtual environments. Only if the result of that
> investigation is that it's not possible, would I be happy with configuration
> toggles.
Well here is a simpler version without config, well the config is
"change the code" and its fairly easy to change if you want to. if you
wanted you could compile non BSD with -lbsd to get arc4random support
too.
diff -urN src/lib/librumpuser/Makefile rsrc/lib/librumpuser/Makefile
--- src/lib/librumpuser/Makefile 2014-07-20 12:39:21.515438184 +0100
+++ rsrc/lib/librumpuser/Makefile 2014-07-19 15:08:48.468971040 +0100
@@ -41,7 +41,7 @@
.error Unsupported rumpuser threading type: ${RUMPUSER_THREADS}
.endif
-SRCS+= rumpuser_component.c
+SRCS+= rumpuser_component.c rumpuser_random.c
SRCS+= rumpuser_file.c rumpuser_mem.c
SRCS+= rumpuser_errtrans.c rumpuser_sigtrans.c
diff -urN src/lib/librumpuser/rumpfiber.c rsrc/lib/librumpuser/rumpfiber.c
--- src/lib/librumpuser/rumpfiber.c 2014-07-20 12:39:21.515438184 +0100
+++ rsrc/lib/librumpuser/rumpfiber.c 2014-07-20 10:06:55.261029402 +0100
@@ -416,21 +416,6 @@
return 1;
}
-#ifdef RUMPUSER_USE_DEVRANDOM
- uint32_t rv;
- int fd;
-
- if ((fd = open("/dev/urandom", O_RDONLY)) == -1) {
- srandom(time(NULL));
- } else {
- if (read(fd, &rv, sizeof(rv)) != sizeof(rv))
- srandom(time(NULL));
- else
- srandom(rv);
- close(fd);
- }
-#endif
-
rumpuser__hyp = *hyp;
init_sched();
@@ -570,26 +555,6 @@
return 0;
}
-int
-rumpuser_getrandom(void *buf, size_t buflen, int flags, size_t *retp)
-{
- size_t origlen = buflen;
- uint32_t *p = buf;
- uint32_t tmp;
- int chunk;
-
- do {
- chunk = buflen < 4 ? buflen : 4; /* portable MIN ... */
- tmp = RUMPUSER_RANDOM();
- memcpy(p, &tmp, chunk);
- p++;
- buflen -= chunk;
- } while (chunk);
-
- *retp = origlen;
- ET(0);
-}
-
/* thread functions */
TAILQ_HEAD(waithead, waiter);
diff -urN src/lib/librumpuser/rumpuser.c rsrc/lib/librumpuser/rumpuser.c
--- src/lib/librumpuser/rumpuser.c 2014-07-20 12:39:21.515438184 +0100
+++ rsrc/lib/librumpuser/rumpuser.c 2014-07-19 14:54:18.580937960 +0100
@@ -63,21 +63,6 @@
return 1;
}
-#ifdef RUMPUSER_USE_DEVRANDOM
- uint32_t rv;
- int fd;
-
- if ((fd = open("/dev/urandom", O_RDONLY)) == -1) {
- srandom(time(NULL));
- } else {
- if (read(fd, &rv, sizeof(rv)) != sizeof(rv))
- srandom(time(NULL));
- else
- srandom(rv);
- close(fd);
- }
-#endif
-
rumpuser__thrinit();
rumpuser__hyp = *hyp;
@@ -275,23 +260,3 @@
raise(sig);
return 0;
}
-
-int
-rumpuser_getrandom(void *buf, size_t buflen, int flags, size_t *retp)
-{
- size_t origlen = buflen;
- uint32_t *p = buf;
- uint32_t tmp;
- int chunk;
-
- do {
- chunk = buflen < 4 ? buflen : 4; /* portable MIN ... */
- tmp = RUMPUSER_RANDOM();
- memcpy(p, &tmp, chunk);
- p++;
- buflen -= chunk;
- } while (chunk);
-
- *retp = origlen;
- ET(0);
-}
diff -urN src/lib/librumpuser/rumpuser_port.h
rsrc/lib/librumpuser/rumpuser_port.h
--- src/lib/librumpuser/rumpuser_port.h 2014-07-20 12:39:21.515438184 +0100
+++ rsrc/lib/librumpuser/rumpuser_port.h 2014-07-20 14:50:55.955077711
+0100
@@ -218,11 +218,8 @@
#define __STRING(x) #x
#endif
-#if defined(__linux__) || defined(__sun__) || defined (__CYGWIN__)
-#define RUMPUSER_RANDOM() random()
-#define RUMPUSER_USE_DEVRANDOM
-#else
-#define RUMPUSER_RANDOM() arc4random()
+#if defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__) ||
defined(__DragonFly__)
+#define PLATFORM_HAS_ARC4RANDOM
#endif
#ifndef __NetBSD_Prereq__
diff -urN src/lib/librumpuser/rumpuser_random.c
rsrc/lib/librumpuser/rumpuser_random.c
--- src/lib/librumpuser/rumpuser_random.c 1970-01-01 01:00:00.000000000
+0100
+++ rsrc/lib/librumpuser/rumpuser_random.c 2014-07-20 15:22:46.006990495
+0100
@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2014 Justin Cormack. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "rumpuser_port.h"
+
+#if !defined(lint)
+__RCSID("$NetBSD$");
+#endif /* !lint */
+
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <rump/rumpuser.h>
+
+#include "rumpuser_int.h"
+
+#ifndef PLATFORM_HAS_ARC4RANDOM
+static int random_init = 0;
+static const char *random_device = "/dev/urandom";
+static const size_t random_maxread = 1024;
+static int random_fd = -1;
+#endif
+
+int
+rumpuser_getrandom(void *buf, size_t buflen, int flags, size_t *retp)
+{
+#ifndef PLATFORM_HAS_ARC4RANDOM
+ ssize_t rv;
+
+ if (__predict_false(random_init == 0)) {
+ random_fd = open(random_device, O_RDONLY);
+ if (random_fd < 0) {
+ abort();
+ }
+ random_init = 1;
+ }
+#endif
+
+#ifdef PLATFORM_HAS_ARC4RANDOM
+ arc4random_buf(buf, buflen);
+ *retp = buflen;
+#else
+ rv = read(random_fd, buf, buflen > random_maxread ? random_maxread :
buflen);
+ if (rv < 0) {
+ ET(rv);
+ }
+ *retp = rv;
+#endif
+
+ ET(0);
+}
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