In srandomdev(), if we can't access /dev/arandom, use the sysctl() instead.

We don't want to use the sysctl() by default since we are reading more
than just a few bytes of entropy when setting up the state.

1 files changed, 27 insertions, 10 deletions

diff --git a/src/lib/libc/stdlib/random.c b/src/lib/libc/stdlib/random.c
index 5ce7c90ee9..787581fe58 100644
--- a/src/lib/libc/stdlib/random.c
+++ b/src/lib/libc/stdlib/random.c
@@ -32,10 +32,11 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
-static char *rcsid = "$OpenBSD: random.c,v 1.9 2000/04/04 14:27:00 millert Exp $";
+static char *rcsid = "$OpenBSD: random.c,v 1.10 2002/12/06 17:43:34 millert Exp $";
 #endif /* LIBC_SCCS and not lint */
 
-#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/sysctl.h>
 #include <sys/time.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -237,7 +238,7 @@ srandom(x)
 void
 srandomdev()
 {
-        int fd;
+        int fd, i, mib[2], n;
         size_t len;
 
         if (rand_type == TYPE_0)
@@ -245,19 +246,35 @@ srandomdev()
         else
                 len = rand_deg * sizeof(state[0]);
 
+        /*
+         * To get seed data, first try reading from /dev/arandom.
+         * If that fails, try the KERN_ARND sysctl() (one int at a time).
+         * As a last resort, call srandom().
+         */
         if ((fd = open("/dev/arandom", O_RDONLY, 0)) != -1 &&
             read(fd, (void *) state, len) == (ssize_t) len) {
                 close(fd);
         } else {
-                struct timeval tv;
-                u_int junk;
-
-                /* XXX - this could be better */
-                gettimeofday(&tv, NULL);
-                srandom(getpid() ^ tv.tv_sec ^ tv.tv_usec ^ junk);
                 if (fd != -1)
                         close(fd);
-                return;
+                mib[0] = CTL_KERN;
+                mib[1] = KERN_ARND;
+                n = len / sizeof(int);
+                len = sizeof(int);
+                for (i = 0; i < n; i++) {
+                        if (sysctl(mib, 2, (char *)((int *)state + i), &len,
+                            NULL, 0) == -1)
+                                break;
+                }
+                if (i != n) {
+                        struct timeval tv;
+                        u_int junk;
+
+                        /* XXX - this could be better */
+                        gettimeofday(&tv, NULL);
+                        srandom(getpid() ^ tv.tv_sec ^ tv.tv_usec ^ junk);
+                        return;
+                }
         }
 
         if (rand_type != TYPE_0) {