[src/trunk]: src/sbin/rndctl Accept both byte orders for random seed in `rndc...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/cbf18549fbdb
branches:  trunk
changeset: 931742:cbf18549fbdb
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Apr 30 03:24:48 2020 +0000

description:
Accept both byte orders for random seed in `rndctl -L'.

The file format was defined with a machine-dependent 32-bit integer
field (the estimated number of bits of entropy in the process that
generated it).  Take whichever byte order gives a number that is
reasonable, i.e. lower than the number of bits in the buffer.

Continue to have `rndctl -S' generate it in machine-dependent byte
order for now, so that if you roll back to an older rndctl(8) then
`rndctl -L' on the same machine will still be able to load it with
the right entropy estimate.  In a future revision, perhaps we can
change it to be little-endian.

diffstat:

 sbin/rndctl/rndctl.c |  21 ++++++++++++++++-----
 1 files changed, 16 insertions(+), 5 deletions(-)

diffs (55 lines):

diff -r 64aa90371387 -r cbf18549fbdb sbin/rndctl/rndctl.c
--- a/sbin/rndctl/rndctl.c      Thu Apr 30 03:24:28 2020 +0000
+++ b/sbin/rndctl/rndctl.c      Thu Apr 30 03:24:48 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: rndctl.c,v 1.31 2019/12/06 14:43:18 riastradh Exp $    */
+/*     $NetBSD: rndctl.c,v 1.32 2020/04/30 03:24:48 riastradh Exp $    */
 
 /*-
  * Copyright (c) 1997 Michael Graff.
@@ -33,13 +33,14 @@
 #include <sha1.h>
 
 #ifndef lint
-__RCSID("$NetBSD: rndctl.c,v 1.31 2019/12/06 14:43:18 riastradh Exp $");
+__RCSID("$NetBSD: rndctl.c,v 1.32 2020/04/30 03:24:48 riastradh Exp $");
 #endif
 
 
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/param.h>
+#include <sys/endian.h>
 #include <sys/rndio.h>
 #include <sys/sha3.h>
 
@@ -192,9 +193,8 @@
            MIN(sizeof(rs.data), UINT32_MAX/NBBY)*NBBY);
 
        /*
-        * Compute the checksum on the 32-bit entropy count, in host
-        * byte order (XXX this means it is not portable across
-        * different-endian platforms!), followed by the seed data.
+        * Compute the checksum on the 32-bit entropy count, followed
+        * by the seed data.
         */
        SHA1Init(&s);
        SHA1Update(&s, (const uint8_t *)&rs.entropy, sizeof(rs.entropy));
@@ -309,6 +309,17 @@
                rs.entropy = 0;
        }
 
+       /*
+        * If the entropy is insensibly large, try byte-swapping.
+        * Otherwise assume the file is corrupted and act as though it
+        * has zero entropy.
+        */
+       if (howmany(rs.entropy, NBBY) > sizeof(rs.data)) {
+               rs.entropy = bswap32(rs.entropy);
+               if (howmany(rs.entropy, NBBY) > sizeof(rs.data))
+                       rs.entropy = 0;
+       }
+
        /* Format the ioctl request.  */
        rd.len = MIN(sizeof(rd.data), sizeof(rs.data));
        rd.entropy = rs.entropy;