From 421838ffef49338218dd85ff5efd1d5396ab7ccf Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Wed, 17 Mar 1999 15:01:07 +0000
Subject: [PATCH] rte_update: Check sanity of incoming entries. Throw out (and
 log) all routes to bogus prefixes and non-local routes to host scope
 addresses.

---
 nest/rt-table.c | 46 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/nest/rt-table.c b/nest/rt-table.c
index 756141ce..584c434f 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -165,6 +165,38 @@ rt_feed_baby(struct proto *p)
     }
 }
 
+static inline int
+rte_validate(rte *e)
+{
+  int c;
+  net *n = e->net;
+
+  ASSERT(!ipa_nonzero(ipa_and(n->n.prefix, ipa_not(ipa_mkmask(n->n.pxlen)))));
+  if (n->n.pxlen)
+    {
+      c = ipa_classify(n->n.prefix);
+      if (c < 0 || !(c & IADDR_HOST))
+	{
+	  if (!ipa_nonzero(n->n.prefix) && n->n.pxlen <= 1)
+	    return 1;		/* Default route and half-default route is OK */
+	  log(L_WARN "Ignoring bogus route %I/%d received from %I via %s",
+	      n->n.prefix, n->n.pxlen, e->attrs->from, e->attrs->proto->name);
+	  return 0;
+	}
+      if ((c & IADDR_SCOPE_MASK) == SCOPE_HOST)
+	{
+	  int s = e->attrs->source;
+	  if (s != RTS_STATIC && s != RTS_DEVICE && s != RTS_STATIC_DEVICE)
+	    {
+	      log(L_WARN "Ignoring host scope route %I/%d received from %I via %s",
+		  n->n.prefix, n->n.pxlen, e->attrs->from, e->attrs->proto->name);
+	      return 0;
+	    }
+	}
+    }
+  return 1;
+}
+
 void
 rte_free(rte *e)
 {
@@ -187,15 +219,17 @@ rte_update(net *net, struct proto *p, rte *new)
   rte *old = NULL;
   rte **k, *r, *s;
 
-  if (new && p->in_filter && f_run(p->in_filter, new, NULL) != F_ACCEPT)
+  if (new)
     {
-      rte_free(new);
-      return;
+      if (!rte_validate(new) || p->in_filter && f_run(p->in_filter, new, NULL) != F_ACCEPT)
+	{
+	  rte_free(new);
+	  return;
+	}
+      if (!(new->attrs->aflags & RTAF_CACHED)) /* Need to copy attributes */
+	new->attrs = rta_lookup(new->attrs);
     }
 
-  if (new && !(new->attrs->aflags & RTAF_CACHED)) /* Need to copy attributes */
-    new->attrs = rta_lookup(new->attrs);
-
   k = &net->routes;			/* Find and remove original route from the same protocol */
   while (old = *k)
     {