Snapshot. This passes the build test, but has not yet been finished or debugged.

Contains:

* Refactor the hardware RNG CPU instruction sources to feed into
the software mixer. This is unfinished. The actual harvesting needs
to be sorted out. Modified by me (see below).

* Remove 'frac' parameter from random_harvest(). This was never
used and adds extra code for no good reason.

* Remove device write entropy harvesting. This provided a weak
attack vector, was not very good at bootstrapping the device. To
follow will be a replacement explicit reseed knob.

* Separate out all the RANDOM_PURE sources into separate harvest
entities. This adds some secuity in the case where more than one
is present.

* Review all the code and fix anything obviously messy or inconsistent.
Address som review concerns while I'm here, like rename the pseudo-rng
to 'dummy'.

Submitted by:	Arthur Mesh <arthurmesh@gmail.com> (the first item)

1 files changed, 28 insertions, 50 deletions

diff --git a/sys/dev/random/randomdev.c b/sys/dev/random/randomdev.c
index 2d24dd5..990324e 100644
--- a/sys/dev/random/randomdev.c
+++ b/sys/dev/random/randomdev.c
@@ -1,6 +1,6 @@
 /*-
+ * Copyright (c) 2000-2013 Mark R V Murray
  * Copyright (c) 2013 Arthur Mesh <arthurmesh@gmail.com>
- * Copyright (c) 2000-2004 Mark R V Murray
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -44,6 +44,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/poll.h>
 #include <sys/priv.h>
 #include <sys/proc.h>
+#include <sys/random.h>
 #include <sys/selinfo.h>
 #include <sys/uio.h>
 #include <sys/unistd.h>
@@ -52,11 +53,11 @@ __FBSDID("$FreeBSD$");
 #include <machine/cpu.h>
 
 #include <dev/random/random_adaptors.h>
+#include <dev/random/live_entropy_sources.h>
 #include <dev/random/randomdev.h>
 
 #define RANDOM_MINOR	0
 
-static d_close_t random_close;
 static d_read_t random_read;
 static d_write_t random_write;
 static d_ioctl_t random_ioctl;
@@ -64,7 +65,6 @@ static d_poll_t random_poll;
 
 static struct cdevsw random_cdevsw = {
 	.d_version = D_VERSION,
-	.d_close = random_close,
 	.d_read = random_read,
 	.d_write = random_write,
 	.d_ioctl = random_ioctl,
@@ -72,34 +72,9 @@ static struct cdevsw random_cdevsw = {
 	.d_name = "random",
 };
 
-static eventhandler_tag attach_tag;
-static int random_inited;
-
 /* For use with make_dev(9)/destroy_dev(9). */
 static struct cdev *random_dev;
 
-struct random_adaptor *
-random_get_active_adaptor(void)
-{ 
-
-	return (random_adaptor);
-}
-
-/* ARGSUSED */
-static int
-random_close(struct cdev *dev __unused, int flags, int fmt __unused,
-    struct thread *td)
-{
-	if ((flags & FWRITE) && (priv_check(td, PRIV_RANDOM_RESEED) == 0)
-	    && (securelevel_gt(td->td_ucred, 0) == 0)) {
-		(*random_adaptor->reseed)();
-		random_adaptor->seeded = 1;
-		arc4rand(NULL, 0, 1);	/* Reseed arc4random as well. */
-	}
-
-	return (0);
-}
-
 /* ARGSUSED */
 static int
 random_read(struct cdev *dev __unused, struct uio *uio, int flag)
@@ -107,6 +82,10 @@ random_read(struct cdev *dev __unused, struct uio *uio, int flag)
 	int c, error = 0;
 	void *random_buf;
 
+	/* XXX: Harvest some entropy from live entropy sources, if available */
+	live_entropy_sources_feed(65); /* 65 is meaningless --
+					  need to decide appropriate value */
+
 	/* Blocking logic */
 	if (!random_adaptor->seeded)
 		error = (*random_adaptor->block)(flag);
@@ -121,6 +100,9 @@ random_read(struct cdev *dev __unused, struct uio *uio, int flag)
 			c = (*random_adaptor->read)(random_buf, c);
 			error = uiomove(random_buf, c, uio);
 		}
+		/* Finished reading; let the source know so it can do some
+		 * optional housekeeping */
+		(*random_adaptor->read)(NULL, 0);
 
 		free(random_buf, M_TEMP);
 
@@ -133,22 +115,16 @@ random_read(struct cdev *dev __unused, struct uio *uio, int flag)
 static int
 random_write(struct cdev *dev __unused, struct uio *uio, int flag __unused)
 {
-	int c, error = 0;
-	void *random_buf;
-
-	random_buf = (void *)malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
-
-	while (uio->uio_resid > 0) {
-		c = MIN((int)uio->uio_resid, PAGE_SIZE);
-		error = uiomove(random_buf, c, uio);
-		if (error)
-			break;
-		(*random_adaptor->write)(random_buf, c);
-	}
 
-	free(random_buf, M_TEMP);
+	/* We used to allow this to insert userland entropy.
+	 * We don't any more because (1) this so-called entropy
+	 * is usually lousy and (b) its vaguely possible to
+	 * mess with entropy harvesting by overdoing a write.
+	 * Now we just ignore input like /dev/null does.
+	 */
+	uio->uio_resid = 0;
 
-	return (error);
+	return (0);
 }
 
 /* ARGSUSED */
@@ -179,7 +155,7 @@ random_poll(struct cdev *dev __unused, int events, struct thread *td)
 		if (random_adaptor->seeded)
 			revents = events & (POLLIN | POLLRDNORM);
 		else
-			revents = (*random_adaptor->poll) (events,td);
+			revents = (*random_adaptor->poll)(events, td);
 	}
 	return (revents);
 }
@@ -187,6 +163,8 @@ random_poll(struct cdev *dev __unused, int events, struct thread *td)
 static void
 random_initialize(void *p, struct random_adaptor *s)
 {
+	static int random_inited = 0;
+
 	if (random_inited) {
 		printf("random: <%s> already initialized\n",
 		    random_adaptor->ident);
@@ -199,9 +177,10 @@ random_initialize(void *p, struct random_adaptor *s)
 
 	printf("random: <%s> initialized\n", s->ident);
 
+	/* Use an appropriately evil mode for those who are concerned
+	 * with daemons */
 	random_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &random_cdevsw,
 	    RANDOM_MINOR, NULL, UID_ROOT, GID_WHEEL, 0666, "random");
-	make_dev_alias(random_dev, "urandom");	/* XXX Deprecated */
 
 	/* mark random(4) as initialized, to avoid being called again */
 	random_inited = 1;
@@ -211,6 +190,7 @@ random_initialize(void *p, struct random_adaptor *s)
 static int
 random_modevent(module_t mod __unused, int type, void *data __unused)
 {
+	static eventhandler_tag attach_tag = NULL;
 	int error = 0;
 
 	switch (type) {
@@ -218,13 +198,12 @@ random_modevent(module_t mod __unused, int type, void *data __unused)
 		random_adaptor_choose(&random_adaptor);
 
 		if (random_adaptor == NULL) {
-			printf(
-       "random: No random adaptor attached, postponing initialization\n");
+			printf("random: No random adaptor attached, "
+			    "postponing initialization\n");
 			attach_tag = EVENTHANDLER_REGISTER(random_adaptor_attach,
 			    random_initialize, NULL, EVENTHANDLER_PRI_ANY);
-		} else {
+		} else
 			random_initialize(NULL, random_adaptor);
-		}
 
 		break;
 
@@ -234,10 +213,9 @@ random_modevent(module_t mod __unused, int type, void *data __unused)
 			destroy_dev(random_dev);
 		}
 		/* Unregister the event handler */
-		if (attach_tag != NULL) {
+		if (attach_tag != NULL)
 			EVENTHANDLER_DEREGISTER(random_adaptor_attach,
 			    attach_tag);
-		}
 
 		break;