if /dev/arandom is not available for seeding, use data from sysctl

kern.arandom.

1 files changed, 22 insertions, 5 deletions

diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
index 5279c21518..b3d65abe68 100644
--- a/src/lib/libc/crypt/arc4random.c
+++ b/src/lib/libc/crypt/arc4random.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random.c,v 1.3 1998/03/22 19:01:16 niklas Exp $   */
+/*      $OpenBSD: arc4random.c,v 1.4 1999/06/29 23:54:05 provos Exp $   */
 
 /*
  * Arc4 random number generator for OpenBSD.
@@ -29,7 +29,9 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/types.h>
+#include <sys/param.h>
 #include <sys/time.h>
+#include <sys/sysctl.h>
 
 #ifdef __GNUC__
 #define inline __inline
@@ -84,17 +86,32 @@ arc4_stir(as)
         int     fd;
         struct {
                 struct timeval tv;
-                u_int8_t rnd[128 - sizeof(struct timeval)];
+                u_int rnd[(128 - sizeof(struct timeval)) / sizeof(u_int)];
         }       rdat;
 
         gettimeofday(&rdat.tv, NULL);
         fd = open("/dev/arandom", O_RDONLY);
-        if (fd >= 0) {
+        if (fd != -1) {
                 read(fd, rdat.rnd, sizeof(rdat.rnd));
                 close(fd);
+        } else {
+                int i, mib[2];
+                size_t len;
+
+                /* Device could not be opened, we might be chrooted, take
+                 * randomness from sysctl. */
+
+                mib[0] = CTL_KERN;
+                mib[1] = KERN_ARND;
+
+                for (i = 0; i < sizeof(rdat.rnd) / sizeof(u_int); i ++) {
+                        len = sizeof(u_int);
+                        if (sysctl(mib, 2, &rdat.rnd[i], &len, NULL, 0) == -1)
+                                break;
+                }
         }
-        /* fd < 0?  Ah, what the heck. We'll just take whatever was on the
-         * stack... */
+        /* fd < 0 or failed sysctl ?  Ah, what the heck. We'll just take
+         * whatever was on the stack... */
 
         arc4_addrandom(as, (void *) &rdat, sizeof(rdat));
 }