After some complaints about the dir names, the random device is

now in dirs called sys/*/random/ instead of sys/*/randomdev/*.

Introduce blocking, but only at startup; the random device will
block until the first reseed happens to prevent clients from
using untrustworthy output.

Provide a read_random() call for the rest of the kernel so that
the entropy device does not need to be present. This means that
things like IPX no longer need to have "device random" hardcoded
into thir kernel config. The downside is that read_random() will
provide very poor output until the entropy device is loaded and
reseeded. It is recommended that developers do NOT use the
read_random() call; instead, they should use arc4random() which
internally uses read_random().

Clean up the mutex and locking code a bit; this makes it possible
to unload the module again.

1 files changed, 60 insertions, 17 deletions

diff --git a/sys/dev/random/harvest.c b/sys/dev/random/harvest.c
index 4bfac55..2f9ac2b 100644
--- a/sys/dev/random/harvest.c
+++ b/sys/dev/random/harvest.c
@@ -31,30 +31,38 @@
 #include <sys/types.h>
 #include <sys/queue.h>
 #include <sys/kthread.h>
+#include <sys/poll.h>
+#include <sys/select.h>
 #include <sys/random.h>
 #include <sys/time.h>
+#include <machine/mutex.h>
 #include <crypto/blowfish/blowfish.h>
 
-#include <dev/randomdev/hash.h>
-#include <dev/randomdev/yarrow.h>
+#include <dev/random/hash.h>
+#include <dev/random/yarrow.h>
+
+static u_int read_random_phony(void *, u_int);
 
 /* hold the address of the routine which is actually called if
  * the ramdomdev is loaded
  */
-static void (*reap)(struct timespec *, void *, u_int, u_int, u_int, u_int) = NULL;
+static void (*reap_func)(struct timespec *, void *, u_int, u_int, u_int, u_int) = NULL;
+static u_int (*read_func)(void *, u_int) = read_random_phony;
 
 /* Initialise the harvester at load time */
 void
-random_init_harvester(void (*reaper)(struct timespec *, void *, u_int, u_int, u_int, u_int))
+random_init_harvester(void (*reaper)(struct timespec *, void *, u_int, u_int, u_int, u_int), u_int (*reader)(void *, u_int))
 {
-	reap = reaper;
+	reap_func = reaper;
+	read_func = reader;
 }
 
 /* Deinitialise the harvester at unload time */
 void
 random_deinit_harvester(void)
 {
-	reap = NULL;
+	reap_func = NULL;
+	read_func = read_random_phony;
 }
 
 /* Entropy harvesting routine. This is supposed to be fast; do
@@ -67,25 +75,60 @@ random_harvest(void *entropy, u_int count, u_int bits, u_int frac, u_int origin)
 {
 	struct timespec timebuf;
 
-	if (reap) {
+	if (reap_func) {
 		nanotime(&timebuf);
-		(*reap)(&timebuf, entropy, count, bits, frac, origin);
+		(*reap_func)(&timebuf, entropy, count, bits, frac, origin);
 	}
 }
 
-/* Helper routines to enable kthread_exit() to work while the module is
- * being (or has been) unloaded.
+/* Userland-visible version of read_random */
+u_int
+read_random(void *buf, u_int count)
+{
+	return (*read_func)(buf, count);
+}
+
+/* If the entropy device is not loaded, make a token effort to
+ * provide _some_ kind of randomness. This should only be used
+ * inside other RNG's, like arc4random(9).
  */
-void
-random_set_wakeup(int *var, int value)
+static u_int
+read_random_phony(void *buf, u_int count)
 {
-	*var = value;
-	wakeup(var);
+	struct timespec timebuf;
+	u_long randval;
+	int size, i;
+	static int initialised = 0;
+
+	/* Try to give random(9) a half decent initialisation
+	 * DO not make the mistake of thinking this is secure!!
+	 */
+	if (!initialised) {
+		nanotime(&timebuf);
+		srandom((u_long)(timebuf.tv_sec ^ timebuf.tv_nsec));
+	}
+
+	/* Fill buf[] with random(9) output */
+	for (i = 0; i < count; i+= sizeof(u_long)) {
+		randval = random();
+		size = (count - i) < sizeof(u_long) ? (count - i) : sizeof(u_long);
+		memcpy(&((char *)buf)[i], &randval, size);
+	}
+
+	return count;
 }
 
+/* Helper routine to enable kthread_exit() to work while the module is
+ * being (or has been) unloaded.
+ * This routine is in this file because it is always linked into the kernel,
+ * and will thus never be unloaded. This is critical for unloadable modules
+ * that have threads.
+ */
 void
-random_set_wakeup_exit(int *var, int value, int exitval)
+random_set_wakeup_exit(void *control)
 {
-	random_set_wakeup(var, value);
-	kthread_exit(exitval);
+	wakeup(control);
+	mtx_enter(&Giant, MTX_DEF);
+	kthread_exit(0);
+	/* NOTREACHED */
 }