[src/trunk]: src/sys/net Fix the wrong CHAP option length in conf-nak

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

details:   https://anonhg.NetBSD.org/src/rev/b7734c2fc5fb
branches:  trunk
changeset: 961974:b7734c2fc5fb
user:      yamaguchi <yamaguchi%NetBSD.org@localhost>
date:      Mon Apr 26 08:45:57 2021 +0000

description:
Fix the wrong CHAP option length in conf-nak

RFC 1994 defines that the CHAP option length in conf-nak is 5.
However, 4 was used when CHAP is cofigured and PPP is proposed
by a peer.

diffstat:

 sys/net/if_spppsubr.c |  39 ++++++++++++++++++++++++++++-----------
 1 files changed, 28 insertions(+), 11 deletions(-)

diffs (67 lines):

diff -r e55200768e37 -r b7734c2fc5fb sys/net/if_spppsubr.c
--- a/sys/net/if_spppsubr.c     Mon Apr 26 08:42:19 2021 +0000
+++ b/sys/net/if_spppsubr.c     Mon Apr 26 08:45:57 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_spppsubr.c,v 1.225 2021/04/26 08:42:19 yamaguchi Exp $       */
+/*     $NetBSD: if_spppsubr.c,v 1.226 2021/04/26 08:45:57 yamaguchi Exp $       */
 
 /*
  * Synchronous PPP/Cisco link level subroutines.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_spppsubr.c,v 1.225 2021/04/26 08:42:19 yamaguchi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_spppsubr.c,v 1.226 2021/04/26 08:45:57 yamaguchi Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_inet.h"
@@ -2876,22 +2876,39 @@
                                if (authproto == PPP_PAP || authproto == PPP_CHAP)
                                        sp->myauth.proto = authproto;
                        }
-                       if (sp->myauth.proto != authproto) {
-                               /* not agreed, nak */
+                       if (sp->myauth.proto == authproto) {
+                               if (authproto != PPP_CHAP || p[4] == CHAP_MD5) {
+                                       continue;
+                               }
+                               if (debug)
+                                       addlog(" [chap without MD5]");
+                       } else {
                                if (debug)
                                        addlog(" [mine %s != his %s]",
                                               sppp_proto_name(sp->myauth.proto),
                                               sppp_proto_name(authproto));
-                               p[2] = sp->myauth.proto >> 8;
-                               p[3] = sp->myauth.proto;
-                               break;
+                       }
+                       /* not agreed, nak */
+                       if (sp->myauth.proto == PPP_CHAP) {
+                               l = 5;
+                       } else {
+                               l = 4;
                        }
-                       if (authproto == PPP_CHAP && p[4] != CHAP_MD5) {
+
+                       if (rlen + l > blen) {
                                if (debug)
-                                       addlog(" [chap not MD5]");
-                               p[4] = CHAP_MD5;
-                               break;
+                                       addlog(" [overflow]");
+                               continue;
                        }
+
+                       r[0] = LCP_OPT_AUTH_PROTO;
+                       r[1] = l;
+                       r[2] = sp->myauth.proto >> 8;
+                       r[3] = sp->myauth.proto & 0xff;
+                       if (sp->myauth.proto == PPP_CHAP)
+                               r[4] = CHAP_MD5;
+                       rlen += l;
+                       r += l;
                        continue;
                case LCP_OPT_MP_EID:
                        /*