[src/trunk]: src/sys/netinet6 in6: reject setting negative values but -1 via ...

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/f78c380b5fcc
branches:  trunk
changeset: 373919:f78c380b5fcc
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Mon Mar 20 09:15:52 2023 +0000

description:
in6: reject setting negative values but -1 via setsockopt(IPV6_CHECKSUM)

Same as OpenBSD.

diffstat:

 sys/netinet6/ip6_output.c |  12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diffs (33 lines):

diff -r 0a1467712cf0 -r f78c380b5fcc sys/netinet6/ip6_output.c
--- a/sys/netinet6/ip6_output.c Sun Mar 19 17:55:57 2023 +0000
+++ b/sys/netinet6/ip6_output.c Mon Mar 20 09:15:52 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ip6_output.c,v 1.232 2023/01/27 09:33:43 ozaki-r Exp $ */
+/*     $NetBSD: ip6_output.c,v 1.233 2023/03/20 09:15:52 ozaki-r Exp $ */
 /*     $KAME: ip6_output.c,v 1.172 2001/03/25 09:55:56 itojun Exp $    */
 
 /*
@@ -62,7 +62,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.232 2023/01/27 09:33:43 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ip6_output.c,v 1.233 2023/03/20 09:15:52 ozaki-r Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_inet.h"
@@ -1984,8 +1984,12 @@
                        error = sockopt_getint(sopt, &optval);
                        if (error)
                                break;
-                       if ((optval % 2) != 0) {
-                               /* the API assumes even offset values */
+                       if (optval < -1 ||
+                           (optval > 0 && (optval % 2) != 0)) {
+                               /*
+                                * The API assumes non-negative even offset
+                                * values or -1 as a special value.
+                                */
                                error = EINVAL;
                        } else if (so->so_proto->pr_protocol ==
                            IPPROTO_ICMPV6) {