Restrict export of device routes to the kernel protocol.

In usual configuration, such export is already restricted
with the aid of the direct protocol but there are some
races that can circumvent it. This makes it harder to
break kernel device routes. Also adds an option to
disable this restriction.

5 files changed, 27 insertions, 17 deletions

diff --git a/sysdep/bsd/krt-sock.c b/sysdep/bsd/krt-sock.c
index 32c269d4..d991ea13 100644
--- a/sysdep/bsd/krt-sock.c
+++ b/sysdep/bsd/krt-sock.c
@@ -40,10 +40,6 @@ krt_capable(rte *e)
 {
   rta *a = e->attrs;
 
-#ifdef CONFIG_AUTO_ROUTES
-  if (a->source == RTS_DEVICE)
-    return 0;
-#endif
   return
     a->cast == RTC_UNICAST &&
     (a->dest == RTD_ROUTER
@@ -163,7 +159,7 @@ krt_sock_send(int cmd, rte *e)
 #endif
 
         if(!i->addr) {
-          log(L_ERR "KIF: interface \"%s\" has no IP addess", i->name);
+          log(L_ERR "KRT: interface %s has no IP addess", i->name);
           return;
         }
 
@@ -185,7 +181,7 @@ krt_sock_send(int cmd, rte *e)
   msg.rtm.rtm_msglen = l;
 
   if ((l = write(rt_sock, (char *)&msg, l)) < 0) {
-    log(L_ERR "KIF: Error sending route %I/%d to kernel", net->n.prefix, net->n.pxlen);
+    log(L_ERR "KRT: Error sending route %I/%d to kernel", net->n.prefix, net->n.pxlen);
   }
 }
 
diff --git a/sysdep/linux/netlink/netlink.c b/sysdep/linux/netlink/netlink.c
index b59b32f3..f31ef9f7 100644
--- a/sysdep/linux/netlink/netlink.c
+++ b/sysdep/linux/netlink/netlink.c
@@ -460,20 +460,14 @@ krt_capable(rte *e)
 {
   rta *a = e->attrs;
 
-  if (a->cast != RTC_UNICAST
-#if 0
-      && a->cast != RTC_ANYCAST
-#endif
-      )
-    return 0;
-  if (a->source == RTS_DEVICE)	/* Kernel takes care of device routes itself */
+  if (a->cast != RTC_UNICAST)
     return 0;
+
   switch (a->dest)
     {
     case RTD_ROUTER:
       if (ipa_has_link_scope(a->gw) && (a->iface == NULL))
 	return 0;
-
     case RTD_DEVICE:
     case RTD_BLACKHOLE:
     case RTD_UNREACHABLE:
diff --git a/sysdep/unix/krt.Y b/sysdep/unix/krt.Y
index 40f1af9f..0375a13b 100644
--- a/sysdep/unix/krt.Y
+++ b/sysdep/unix/krt.Y
@@ -17,7 +17,7 @@ CF_DEFINES
 
 CF_DECLS
 
-CF_KEYWORDS(KERNEL, PERSIST, SCAN, TIME, LEARN, DEVICE)
+CF_KEYWORDS(KERNEL, PERSIST, SCAN, TIME, LEARN, DEVICE, ROUTES)
 
 CF_GRAMMAR
 
@@ -56,6 +56,7 @@ kern_item:
 	cf_error("Learning of kernel routes not supported in this configuration");
 #endif
    }
+ | DEVICE ROUTES bool { THIS_KRT->devroutes = $3; }
  ;
 
 /* Kernel interface protocol */
diff --git a/sysdep/unix/krt.c b/sysdep/unix/krt.c
index c8887b72..419bdd94 100644
--- a/sysdep/unix/krt.c
+++ b/sysdep/unix/krt.c
@@ -734,6 +734,25 @@ krt_scan(timer *t UNUSED)
 /*
  *	Updates
  */
+static int
+krt_import_control(struct proto *P, rte **new, ea_list **attrs, struct linpool *pool)
+{
+  struct krt_proto *p = (struct krt_proto *) P;
+  rte *e = *new;
+
+  if (e->attrs->proto == P)
+    return -1;
+
+  if (!KRT_CF->devroutes && 
+      (e->attrs->dest == RTD_DEVICE) && 
+      (e->attrs->source != RTS_STATIC_DEVICE))
+    return -1;
+
+  if (!krt_capable(e))
+    return -1;
+
+  return 0;
+}
 
 static void
 krt_notify(struct proto *P, struct rtable *table UNUSED, net *net,
@@ -743,8 +762,6 @@ krt_notify(struct proto *P, struct rtable *table UNUSED, net *net,
 
   if (shutting_down)
     return;
-  if (new && (!krt_capable(new) || new->attrs->source == RTS_INHERIT))
-    new = NULL;
   if (!(net->n.flags & KRF_INSTALLED))
     old = NULL;
   if (new)
@@ -871,6 +888,7 @@ krt_init(struct proto_config *c)
   struct krt_proto *p = proto_new(c, sizeof(struct krt_proto));
 
   p->p.accept_ra_types = RA_OPTIMAL;
+  p->p.import_control = krt_import_control;
   p->p.rt_notify = krt_notify;
   return &p->p;
 }
diff --git a/sysdep/unix/krt.h b/sysdep/unix/krt.h
index 1d9e1448..ed61621f 100644
--- a/sysdep/unix/krt.h
+++ b/sysdep/unix/krt.h
@@ -47,6 +47,7 @@ struct krt_config {
   int persist;			/* Keep routes when we exit */
   int scan_time;		/* How often we re-scan routes */
   int learn;			/* Learn routes from other sources */
+  int devroutes;		/* Allow export of device routes */
 };
 
 struct krt_proto {