PATCH: fix bug in handling genmask

[Kieran Devlin]

maybe someone could verify & commit this patch

a. fix a bug
b. get rid of junk in ‘mask_rnhead'
c. forbid unprivileged user to insert mask into ‘mask_rnhead'

bug is in this line
        Bcmp((caddr_t *)genmask + 1, (caddr_t *)t->rn_key + 1, ((struct 
sockaddr *)t->rn_key)->sa_len) 
to make this right, at least, it should look like this
        Bcmp((caddr_t)genmask + 1, (caddr_t)t->rn_key + 1, ((struct sockaddr 
*)t->rn_key)->sa_len - 1) 
after doing this, the whole checking seems completely unnecessary, is expected 
result from ‘rn_addmask’.

Index: net/rtsock.c
===================================================================
RCS file: /cvs/src/sys/net/rtsock.c,v
retrieving revision 1.131
diff -p -u -r1.131 rtsock.c
--- net/rtsock.c        1 Nov 2013 20:09:14 -0000       1.131
+++ net/rtsock.c        27 Dec 2013 14:08:44 -0000
@@ -593,18 +593,22 @@ route_output(struct mbuf *m, ...)
                error = EINVAL;
                goto flush;
        }
-       if (genmask) {
-               struct radix_node       *t;
-               t = rn_addmask(genmask, 0, 1);
-               if (t && genmask->sa_len >=
-                   ((struct sockaddr *)t->rn_key)->sa_len &&
-                   Bcmp((caddr_t *)genmask + 1, (caddr_t *)t->rn_key + 1,
-                   ((struct sockaddr *)t->rn_key)->sa_len) - 1)
-                       genmask = (struct sockaddr *)(t->rn_key);
-               else {
+       if (genmask && rtm->rtm_type != RTM_GET) {
+               if (!(rnh = rt_gettable(dst->sa_family, tableid))) {
+                       error = EINVAL;
+                       goto flush;
+               }
+               if (!(rn = rn_addmask(genmask, 0, rnh->rnh_treetop->rn_off))) {
                        error = ENOBUFS;
                        goto flush;
                }
+               if (!((struct sockaddr *)rn->rn_key)->sa_len) {
+                       error = EINVAL;
+                       goto flush;
+               }
+               genmask = (struct sockaddr *)rn->rn_key;
+       } else {
+               genmask = NULL;
        }
 #ifdef MPLS
        info.rti_mpls = rtm->rtm_mpls;