X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=secnet.git;a=blobdiff_plain;f=netlink.c;h=022ddf1c00ae7a7c440c6245aca9494cf096fa46;hp=0b1ebe411291b7f4b8f9bb59490693b5e94084ea;hb=b2a56f7c93d221607864761c590952b9a614dc9f;hpb=4efd681a66c15bc6f81eefc69396669e165e5e0f

diff --git a/netlink.c b/netlink.c
index 0b1ebe4..022ddf1 100644
--- a/netlink.c
+++ b/netlink.c
@@ -1,79 +1,16 @@
 /* User-kernel network link */
 
-/* We will eventually support a variety of methods for extracting
-   packets from the kernel: userv-ipif, ipif on its own (when we run
-   as root), the kernel TUN driver, SLIP to a pty, an external netlink
-   daemon. There is a performance/security tradeoff. */
-
-/* When dealing with SLIP (to a pty, or ipif) we have separate rx, tx
-   and client buffers. When receiving we may read() any amount, not
-   just whole packets. When transmitting we need to bytestuff anyway,
-   and may be part-way through receiving. */
-
-/* Each netlink device is actually a router, with its own IP
-   address. We do things like decreasing the TTL and recalculating the
-   header checksum, generating ICMP, responding to pings, etc. */
+/* Each netlink device is actually a router, with its own IP address.
+   We do things like decreasing the TTL and recalculating the header
+   checksum, generating ICMP, responding to pings, etc. */
 
 /* This is where we have the anti-spoofing paranoia - before sending a
    packet to the kernel we check that the tunnel it came over could
    reasonably have produced it. */
 
-/* XXX now implement TUN. Kernel needs recompiling. */
-
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sys/ioctl.h>
-
-#include "config.h"
 #include "secnet.h"
 #include "util.h"
-
-#ifdef HAVE_LINUX_IF_H
-#include <linux/if.h>
-#include <linux/if_tun.h>
-#endif
-
-/* XXX where do we find if_tun on other architectures? */
-
-#define DEFAULT_BUFSIZE 2048
-#define DEFAULT_MTU 1000
-#define ICMP_BUFSIZE 1024
-
-#define SLIP_END    192
-#define SLIP_ESC    219
-#define SLIP_ESCEND 220
-#define SLIP_ESCESC 221
-
-struct netlink_client {
-    struct subnet_list *networks;
-    netlink_deliver_fn *deliver;
-    void *dst;
-    string_t name;
-    bool_t can_deliver;
-    struct netlink_client *next;
-};
-
-/* Netlink provides one function to the device driver, to call to deliver
-   a packet from the device. The device driver provides one function to
-   netlink, for it to call to deliver a packet to the device. */
-
-struct netlink {
-    closure_t cl;
-    struct netlink_if ops;
-    void *dst; /* Pointer to host interface state */
-    string_t name;
-    uint32_t max_start_pad;
-    uint32_t max_end_pad;
-    struct subnet_list networks;
-    uint32_t local_address; /* host interface address */
-    uint32_t secnet_address; /* our own address */
-    uint32_t mtu;
-    struct netlink_client *clients;
-    netlink_deliver_fn *deliver_to_host; /* Provided by driver */
-    struct buffer_if icmp; /* Buffer for assembly of outgoing ICMP */
-};
+#include "netlink.h"
 
 /* Generic IP checksum routine */
 static inline uint16_t ip_csum(uint8_t *iph,uint32_t count)
@@ -176,7 +113,9 @@ struct icmphdr {
     } d;
 };
     
-static void netlink_packet_deliver(struct netlink *st, struct buffer_if *buf);
+static void netlink_packet_deliver(struct netlink *st,
+				   struct netlink_client *client,
+				   struct buffer_if *buf);
 
 static struct icmphdr *netlink_icmp_tmpl(struct netlink *st,
 					 uint32_t dest,uint16_t len)
@@ -266,7 +205,10 @@ static uint16_t netlink_icmp_reply_len(struct buffer_if *buf)
     return (hlen>plen?plen:hlen);
 }
 
+/* client indicates where the packet we're constructing a response to
+   comes from. NULL indicates the host. */
 static void netlink_icmp_simple(struct netlink *st, struct buffer_if *buf,
+				struct netlink_client *client,
 				uint8_t type, uint8_t code)
 {
     struct iphdr *iph=(struct iphdr *)buf->start;
@@ -279,7 +221,7 @@ static void netlink_icmp_simple(struct netlink *st, struct buffer_if *buf,
 	h->type=type; h->code=code;
 	memcpy(buf_append(&st->icmp,len),buf->start,len);
 	netlink_icmp_csum(h);
-	netlink_packet_deliver(st,&st->icmp);
+	netlink_packet_deliver(st,NULL,&st->icmp);
 	BUF_ASSERT_FREE(&st->icmp);
     }
 }
@@ -300,34 +242,29 @@ static bool_t netlink_check(struct netlink *st, struct buffer_if *buf)
     struct iphdr *iph=(struct iphdr *)buf->start;
     uint32_t len;
 
-    if (iph->ihl < 5 || iph->version != 4) {
-	printf("ihl/version check failed\n");
-	return False;
-    }
-    if (buf->size < iph->ihl*4) {
-	printf("buffer size check failed\n");
-	return False;
-    }
-    if (ip_fast_csum((uint8_t *)iph, iph->ihl)!=0) {
-	printf("checksum failed\n");
-	return False;
-    }
+    if (iph->ihl < 5 || iph->version != 4) return False;
+    if (buf->size < iph->ihl*4) return False;
+    if (ip_fast_csum((uint8_t *)iph, iph->ihl)!=0) return False;
     len=ntohs(iph->tot_len);
     /* There should be no padding */
-    if (buf->size!=len || len<(iph->ihl<<2)) {
-	printf("length check failed buf->size=%d len=%d\n",buf->size,len);
-	return False;
-    }
-
+    if (buf->size!=len || len<(iph->ihl<<2)) return False;
     /* XXX check that there's no source route specified */
     return True;
 }
 
-static void netlink_packet_deliver(struct netlink *st, struct buffer_if *buf)
+/* Deliver a packet. "client" points to the _origin_ of the packet, not
+   its destination. (May be used when sending ICMP response - avoid
+   asymmetric routing.) */
+static void netlink_packet_deliver(struct netlink *st,
+				   struct netlink_client *client,
+				   struct buffer_if *buf)
 {
     struct iphdr *iph=(struct iphdr *)buf->start;
     uint32_t dest=ntohl(iph->daddr);
-    struct netlink_client *c;
+    uint32_t source=ntohl(iph->saddr);
+    uint32_t best_quality;
+    int best_match;
+    int i;
 
     BUF_ASSERT_USED(buf);
 
@@ -337,30 +274,80 @@ static void netlink_packet_deliver(struct netlink *st, struct buffer_if *buf)
 	return;
     }
     
-    for (c=st->clients; c; c=c->next) {
-	if (subnet_match(c->networks,dest)) {
-	    if (c->can_deliver) {
-		c->deliver(c->dst,c,buf);
+    /* XXX we're going to need an extra value 'allow_route' for the
+       source of the packet. It's always True for packets from the
+       host. For packets from tunnels, we consult the client
+       options. If !allow_route and the destination is a tunnel that
+       also doesn't allow routing, we must reject the packet with an
+       'administratively prohibited' or something similar ICMP. */
+    if (!client) {
+	/* Origin of packet is host or secnet. Might be for a tunnel. */
+	best_quality=0;
+	best_match=-1;
+	for (i=0; i<st->n_routes; i++) {
+	    if (st->routes[i].up && subnet_match(&st->routes[i].net,dest)) {
+		if (st->routes[i].c->link_quality>best_quality
+		    || best_quality==0) {
+		    best_quality=st->routes[i].c->link_quality;
+		    best_match=i;
+		    /* If quality isn't perfect we may wish to
+		       consider kicking the tunnel with a 0-length
+		       packet to prompt it to perform a key setup.
+		       Then it'll eventually decide it's up or
+		       down. */
+		    /* If quality is perfect we don't need to search
+                       any more. */
+		    if (best_quality>=MAXIMUM_LINK_QUALITY) break;
+		}
+	    }
+	}
+	if (best_match==-1) {
+	    /* Not going down a tunnel. Might be for the host. 
+	       XXX think about this - only situation should be if we're
+	       sending ICMP. */
+	    if (source!=st->secnet_address) {
+		Message(M_ERROR,"netlink_packet_deliver: outgoing packet "
+			"from host that won't fit down any of our tunnels!\n");
+		/* XXX I think this could also occur if a soft tunnel just
+		   went down, but still had packets queued in the kernel. */
+		BUF_FREE(buf);
+	    } else {
+		st->deliver_to_host(st->dst,NULL,buf);
+		BUF_ASSERT_FREE(buf);
+	    }
+	} else {
+	    if (best_quality>0) {
+		st->routes[best_match].c->deliver(
+		    st->routes[best_match].c->dst,
+		    st->routes[best_match].c, buf);
 		BUF_ASSERT_FREE(buf);
 	    } else {
 		/* Generate ICMP destination unreachable */
-		netlink_icmp_simple(st,buf,3,0);
+		netlink_icmp_simple(st,buf,client,3,0); /* client==NULL */
 		BUF_FREE(buf);
 	    }
-	    return;
+	}
+    } else { /* client is set */
+	/* We know the origin is a tunnel - packet must be for the host */
+	/* XXX THIS IS NOT NECESSARILY TRUE, AND NEEDS FIXING */
+	/* THIS FUNCTION MUST JUST DELIVER THE PACKET: IT MUST ASSUME
+	   THE PACKET HAS ALREADY BEEN CHECKED */
+	if (subnet_matches_list(&st->networks,dest)) {
+	    st->deliver_to_host(st->dst,NULL,buf);
+	    BUF_ASSERT_FREE(buf);
+	} else {
+	    Message(M_ERROR,"%s: packet from tunnel %s can't be delivered "
+		    "to the host\n",st->name,client->name);
+	    netlink_icmp_simple(st,buf,client,3,0);
+	    BUF_FREE(buf);
 	}
     }
-    if (subnet_match(&st->networks,dest)) {
-	st->deliver_to_host(st->dst,NULL,buf);
-	BUF_ASSERT_FREE(buf);
-	return;
-    }
-    Message(M_ERROR,"%s: failed to deliver a packet (bad destination address)"
-	    "\nXXX make this message clearer\n");
-    BUF_FREE(buf);
+    BUF_ASSERT_FREE(buf);
 }
 
-static void netlink_packet_forward(struct netlink *st, struct buffer_if *buf)
+static void netlink_packet_forward(struct netlink *st, 
+				   struct netlink_client *client,
+				   struct buffer_if *buf)
 {
     struct iphdr *iph=(struct iphdr *)buf->start;
     
@@ -369,7 +356,7 @@ static void netlink_packet_forward(struct netlink *st, struct buffer_if *buf)
     /* Packet has already been checked */
     if (iph->ttl<=1) {
 	/* Generate ICMP time exceeded */
-	netlink_icmp_simple(st,buf,11,0);
+	netlink_icmp_simple(st,buf,client,11,0);
 	BUF_FREE(buf);
 	return;
     }
@@ -377,20 +364,22 @@ static void netlink_packet_forward(struct netlink *st, struct buffer_if *buf)
     iph->check=0;
     iph->check=ip_fast_csum((uint8_t *)iph,iph->ihl);
 
-    netlink_packet_deliver(st,buf);
+    netlink_packet_deliver(st,client,buf);
     BUF_ASSERT_FREE(buf);
 }
 
-/* Someone has been foolish enough to address a packet to us. I
-   suppose we should reply to it, just to be polite. */
-static void netlink_packet_local(struct netlink *st, struct buffer_if *buf)
+/* Deal with packets addressed explicitly to us */
+static void netlink_packet_local(struct netlink *st,
+				 struct netlink_client *client,
+				 struct buffer_if *buf)
 {
     struct icmphdr *h;
 
     h=(struct icmphdr *)buf->start;
 
     if ((ntohs(h->iph.frag_off)&0xbfff)!=0) {
-	Message(M_WARNING,"%s: fragmented packet addressed to us\n",st->name);
+	Message(M_WARNING,"%s: fragmented packet addressed to secnet; "
+		"ignoring it\n",st->name);
 	BUF_FREE(buf);
 	return;
     }
@@ -407,13 +396,13 @@ static void netlink_packet_local(struct netlink *st, struct buffer_if *buf)
 	    h->iph.check=0;
 	    h->iph.check=ip_fast_csum((uint8_t *)h,h->iph.ihl);
 	    netlink_icmp_csum(h);
-	    netlink_packet_deliver(st,buf);
+	    netlink_packet_deliver(st,NULL,buf);
 	    return;
 	}
 	Message(M_WARNING,"%s: unknown incoming ICMP\n",st->name);
     } else {
 	/* Send ICMP protocol unreachable */
-	netlink_icmp_simple(st,buf,3,2);
+	netlink_icmp_simple(st,buf,client,3,2);
 	BUF_FREE(buf);
 	return;
     }
@@ -421,19 +410,19 @@ static void netlink_packet_local(struct netlink *st, struct buffer_if *buf)
     BUF_FREE(buf);
 }
 
-/* Called by site code when remote packet is available */
-/* buf is allocated on entry and free on return */
-static void netlink_from_tunnel(void *sst, void *cst, struct buffer_if *buf)
+/* If cid==NULL packet is from host, otherwise cid specifies which tunnel 
+   it came from. */
+static void netlink_incoming(void *sst, void *cid, struct buffer_if *buf)
 {
     struct netlink *st=sst;
-    struct netlink_client *client=cst;
+    struct netlink_client *client=cid;
     uint32_t source,dest;
     struct iphdr *iph;
 
     BUF_ASSERT_USED(buf);
     if (!netlink_check(st,buf)) {
-	Message(M_WARNING,"%s: bad IP packet from tunnel %s\n",
-		st->name,client->name);
+	Message(M_WARNING,"%s: bad IP packet from %s\n",
+		st->name,client?client->name:"host");
 	BUF_FREE(buf);
 	return;
     }
@@ -442,94 +431,88 @@ static void netlink_from_tunnel(void *sst, void *cst, struct buffer_if *buf)
     source=ntohl(iph->saddr);
     dest=ntohl(iph->daddr);
 
-    /* Check that the packet source is in 'nets' and its destination is
-       in client->networks */
-    if (!subnet_match(client->networks,source)) {
-	string_t s,d;
-	s=ipaddr_to_string(source);
-	d=ipaddr_to_string(dest);
-	Message(M_WARNING,"%s: packet from tunnel %s with bad source address "
-		"(s=%s,d=%s)\n",st->name,client->name,s,d);
-	free(s); free(d);
-	BUF_FREE(buf);
-	return;
+    /* Check source */
+    if (client) {
+	/* Check that the packet source is in 'nets' and its destination is
+	   in st->networks */
+	if (!subnet_matches_list(client->networks,source)) {
+	    string_t s,d;
+	    s=ipaddr_to_string(source);
+	    d=ipaddr_to_string(dest);
+	    Message(M_WARNING,"%s: packet from tunnel %s with bad "
+		    "source address (s=%s,d=%s)\n",st->name,client->name,s,d);
+	    free(s); free(d);
+	    BUF_FREE(buf);
+	    return;
+	}
+    } else {
+	if (!subnet_matches_list(&st->networks,source)) {
+	    string_t s,d;
+	    s=ipaddr_to_string(source);
+	    d=ipaddr_to_string(dest);
+	    Message(M_WARNING,"%s: outgoing packet with bad source address "
+		    "(s=%s,d=%s)\n",st->name,s,d);
+	    free(s); free(d);
+	    BUF_FREE(buf);
+	    return;
+	}
     }
-    /* (st->secnet_address needs checking before matching against
-       st->networks because secnet's IP address may not be in the
-       range the host is willing to deal with) */
+    /* (st->secnet_address needs checking before matching destination
+       addresses) */
     if (dest==st->secnet_address) {
-        netlink_packet_local(st,buf);
+	netlink_packet_local(st,client,buf);
 	BUF_ASSERT_FREE(buf);
 	return;
     }
-    if (!subnet_match(&st->networks,dest)) {
-	string_t s,d;
-	s=ipaddr_to_string(source);
-	d=ipaddr_to_string(dest);
-	Message(M_WARNING,"%s: incoming packet from tunnel %s "
-		"with bad destination address "
-		"(s=%s,d=%s)\n",st->name,client->name,s,d);
-	free(s); free(d);
-	BUF_FREE(buf);
-	return;
+    if (client) {
+	/* Check for free routing */
+	if (!subnet_matches_list(&st->networks,dest)) {
+	    string_t s,d;
+	    s=ipaddr_to_string(source);
+	    d=ipaddr_to_string(dest);
+	    Message(M_WARNING,"%s: incoming packet from tunnel %s "
+		    "with bad destination address "
+		    "(s=%s,d=%s)\n",st->name,client->name,s,d);
+	    free(s); free(d);
+	    BUF_FREE(buf);
+	    return;
+	}
     }
-
-    netlink_packet_forward(st,buf);
-
+    netlink_packet_forward(st,client,buf);
     BUF_ASSERT_FREE(buf);
 }
 
-/* Called by driver code when packet is received from kernel */
-/* cid should be NULL */
-/* buf should be allocated on entry, and is free on return */
-static void netlink_from_host(void *sst, void *cid, struct buffer_if *buf)
+static void netlink_set_softlinks(struct netlink *st, struct netlink_client *c,
+				  bool_t up)
 {
-    struct netlink *st=sst;
-    uint32_t source,dest;
-    struct iphdr *iph;
-
-    BUF_ASSERT_USED(buf);
-    if (!netlink_check(st,buf)) {
-	Message(M_WARNING,"%s: bad IP packet from host\n",
-		st->name);
-	BUF_FREE(buf);
-	return;
-    }
-    iph=(struct iphdr *)buf->start;
-
-    source=ntohl(iph->saddr);
-    dest=ntohl(iph->daddr);
+    uint32_t i;
 
-    if (!subnet_match(&st->networks,source)) {
-	string_t s,d;
-	s=ipaddr_to_string(source);
-	d=ipaddr_to_string(dest);
-	Message(M_WARNING,"%s: outgoing packet with bad source address "
-		"(s=%s,d=%s)\n",st->name,s,d);
-	free(s); free(d);
-	BUF_FREE(buf);
-	return;
-    }
-    if (dest==st->secnet_address) {
-	netlink_packet_local(st,buf);
-	BUF_ASSERT_FREE(buf);
-	return;
+    if (!st->routes) return; /* Table has not yet been created */
+    for (i=0; i<st->n_routes; i++) {
+	if (!st->routes[i].hard && st->routes[i].c==c) {
+	    st->routes[i].up=up;
+	    st->set_route(st->dst,&st->routes[i]);
+	}
     }
-    netlink_packet_forward(st,buf);
-    BUF_ASSERT_FREE(buf);
 }
 
-static void netlink_set_delivery(void *sst, void *cid, bool_t can_deliver)
+static void netlink_set_quality(void *sst, void *cid, uint32_t quality)
 {
+    struct netlink *st=sst;
     struct netlink_client *c=cid;
 
-    c->can_deliver=can_deliver;
+    c->link_quality=quality;
+    if (c->link_quality==LINK_QUALITY_DOWN) {
+	netlink_set_softlinks(st,c,False);
+    } else {
+	netlink_set_softlinks(st,c,True);
+    }
 }
 
 static void *netlink_regnets(void *sst, struct subnet_list *nets,
 			     netlink_deliver_fn *deliver, void *dst,
 			     uint32_t max_start_pad, uint32_t max_end_pad,
-			     string_t client_name)
+			     uint32_t options, string_t client_name)
 {
     struct netlink *st=sst;
     struct netlink_client *c;
@@ -538,24 +521,122 @@ static void *netlink_regnets(void *sst, struct subnet_list *nets,
 	    "max_start_pad=%d, max_end_pad=%d\n",
 	    nets->entries,max_start_pad,max_end_pad);
 
+    if ((options&NETLINK_OPTION_SOFTROUTE) && !st->set_route) {
+	Message(M_ERROR,"%s: this netlink device does not support "
+		"soft routes.\n");
+	return NULL;
+    }
+
+    if (options&NETLINK_OPTION_SOFTROUTE) {
+	/* XXX for now we assume that soft routes require root privilege;
+	   this may not always be true. The device driver can tell us. */
+	require_root_privileges=True;
+	require_root_privileges_explanation="netlink: soft routes";
+    }
+
+    /* Check that nets do not intersect st->exclude_remote_networks;
+       refuse to register if they do. */
+    if (subnet_lists_intersect(&st->exclude_remote_networks,nets)) {
+	Message(M_ERROR,"%s: site %s specifies networks that "
+		"intersect with the explicitly excluded remote networks\n",
+		st->name,client_name);
+	return False;
+    }
+
     c=safe_malloc(sizeof(*c),"netlink_regnets");
     c->networks=nets;
     c->deliver=deliver;
     c->dst=dst;
     c->name=client_name; /* XXX copy it? */
-    c->can_deliver=False;
+    c->options=options;
+    c->link_quality=LINK_QUALITY_DOWN;
     c->next=st->clients;
     st->clients=c;
     if (max_start_pad > st->max_start_pad) st->max_start_pad=max_start_pad;
     if (max_end_pad > st->max_end_pad) st->max_end_pad=max_end_pad;
+    st->n_routes+=nets->entries;
 
     return c;
 }
 
-static netlink_deliver_fn *netlink_init(struct netlink *st,
-					void *dst, struct cloc loc,
-					dict_t *dict, string_t description,
-					netlink_deliver_fn *to_host)
+static void netlink_dump_routes(struct netlink *st)
+{
+    int i;
+    string_t net;
+
+    Message(M_INFO,"%s: routing table:\n",st->name);
+    for (i=0; i<st->n_routes; i++) {
+	net=subnet_to_string(&st->routes[i].net);
+	Message(M_INFO,"%s -> tunnel %s (%s,%s route,%s)\n",net,
+		st->routes[i].c->name,
+		st->routes[i].hard?"hard":"soft",
+		st->routes[i].allow_route?"free":"restricted",
+		st->routes[i].up?"up":"down");
+	free(net);
+    }
+    Message(M_INFO,"%s/32 -> netlink \"%s\"\n",
+	    ipaddr_to_string(st->secnet_address),st->name);
+    for (i=0; i<st->networks.entries; i++) {
+	net=subnet_to_string(&st->networks.list[i]);
+	Message(M_INFO,"%s -> host\n",net);
+	free(net);
+    }
+}
+
+static int netlink_compare_route_specificity(const void *ap, const void *bp)
+{
+    const struct netlink_route *a=ap;
+    const struct netlink_route *b=bp;
+
+    if (a->net.len==b->net.len) return 0;
+    if (a->net.len<b->net.len) return 1;
+    return -1;
+}
+
+static void netlink_phase_hook(void *sst, uint32_t new_phase)
+{
+    struct netlink *st=sst;
+    struct netlink_client *c;
+    uint32_t i,j;
+
+    /* All the networks serviced by the various tunnels should now
+     * have been registered.  We build a routing table by sorting the
+     * routes into most-specific-first order.  */
+    st->routes=safe_malloc(st->n_routes*sizeof(*st->routes),
+			   "netlink_phase_hook");
+    /* Fill the table */
+    i=0;
+    for (c=st->clients; c; c=c->next) {
+	for (j=0; j<c->networks->entries; j++) {
+	    st->routes[i].net=c->networks->list[j];
+	    st->routes[i].c=c;
+	    /* Hard routes are always up;
+	       soft routes default to down */
+	    st->routes[i].up=c->options&NETLINK_OPTION_SOFTROUTE?False:True;
+	    st->routes[i].kup=False;
+	    st->routes[i].hard=c->options&NETLINK_OPTION_SOFTROUTE?False:True;
+	    st->routes[i].allow_route=c->options&NETLINK_OPTION_ALLOW_ROUTE?
+		True:False;
+	    i++;
+	}
+    }
+    /* ASSERT i==st->n_routes */
+    if (i!=st->n_routes) {
+	fatal("netlink: route count error: expected %d got %d\n",
+	      st->n_routes,i);
+    }
+    /* Sort the table in descending order of specificity */
+    qsort(st->routes,st->n_routes,sizeof(*st->routes),
+	  netlink_compare_route_specificity);
+
+    netlink_dump_routes(st);
+}
+
+netlink_deliver_fn *netlink_init(struct netlink *st,
+				 void *dst, struct cloc loc,
+				 dict_t *dict, string_t description,
+				 netlink_route_fn *set_route,
+				 netlink_deliver_fn *to_host)
 {
     st->dst=dst;
     st->cl.description=description;
@@ -564,520 +645,33 @@ static netlink_deliver_fn *netlink_init(struct netlink *st,
     st->cl.interface=&st->ops;
     st->ops.st=st;
     st->ops.regnets=netlink_regnets;
-    st->ops.deliver=netlink_from_tunnel;
-    st->ops.set_delivery=netlink_set_delivery;
+    st->ops.deliver=netlink_incoming;
+    st->ops.set_quality=netlink_set_quality;
     st->max_start_pad=0;
     st->max_end_pad=0;
     st->clients=NULL;
+    st->set_route=set_route;
     st->deliver_to_host=to_host;
 
     st->name=dict_read_string(dict,"name",False,"netlink",loc);
     if (!st->name) st->name=description;
     dict_read_subnet_list(dict, "networks", True, "netlink", loc,
 			  &st->networks);
-    st->local_address=string_to_ipaddr(
-	dict_find_item(dict,"local-address", True, "netlink", loc),"netlink");
+    dict_read_subnet_list(dict, "exclude-remote-networks", False, "netlink",
+			  loc, &st->exclude_remote_networks);
+    /* secnet-address does not have to be in local-networks;
+       however, it should be advertised in the 'sites' file for the
+       local site. */
     st->secnet_address=string_to_ipaddr(
 	dict_find_item(dict,"secnet-address", True, "netlink", loc),"netlink");
-    if (!subnet_match(&st->networks,st->local_address)) {
-	cfgfatal(loc,"netlink","local-address must be in local networks\n");
-    }
     st->mtu=dict_read_number(dict, "mtu", False, "netlink", loc, DEFAULT_MTU);
     buffer_new(&st->icmp,ICMP_BUFSIZE);
+    st->n_routes=0;
+    st->routes=NULL;
 
-    return netlink_from_host;
-}
-
-/* Connection to the kernel through userv-ipif */
-
-struct userv {
-    struct netlink nl;
-    int txfd; /* We transmit to userv */
-    int rxfd; /* We receive from userv */
-    string_t userv_path;
-    string_t service_user;
-    string_t service_name;
-    uint32_t txbuflen;
-    struct buffer_if *buff; /* We unstuff received packets into here
-			       and send them to the site code. */
-    bool_t pending_esc;
-    netlink_deliver_fn *netlink_to_tunnel;
-};
-
-static int userv_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
-			    int *timeout_io, const struct timeval *tv_now,
-			    uint64_t *now)
-{
-    struct userv *st=sst;
-    *nfds_io=2;
-    fds[0].fd=st->txfd;
-    fds[0].events=POLLERR; /* Might want to pick up POLLOUT sometime */
-    fds[1].fd=st->rxfd;
-    fds[1].events=POLLIN|POLLERR|POLLHUP;
-    return 0;
-}
-
-static void userv_afterpoll(void *sst, struct pollfd *fds, int nfds,
-			    const struct timeval *tv_now, uint64_t *now)
-{
-    struct userv *st=sst;
-    uint8_t rxbuf[DEFAULT_BUFSIZE];
-    int l,i;
-
-    if (fds[1].revents&POLLERR) {
-	printf("userv_afterpoll: hup!\n");
-    }
-    if (fds[1].revents&POLLIN) {
-	l=read(st->rxfd,rxbuf,DEFAULT_BUFSIZE);
-	if (l<0) {
-	    fatal_perror("userv_afterpoll: read(rxfd)");
-	}
-	if (l==0) {
-	    fatal("userv_afterpoll: read(rxfd)=0; userv gone away?\n");
-	}
-	/* XXX really crude unstuff code */
-	/* XXX check for buffer overflow */
-	BUF_ASSERT_USED(st->buff);
-	for (i=0; i<l; i++) {
-	    if (st->pending_esc) {
-		st->pending_esc=False;
-		switch(rxbuf[i]) {
-		case SLIP_ESCEND:
-		    *(uint8_t *)buf_append(st->buff,1)=SLIP_END;
-		    break;
-		case SLIP_ESCESC:
-		    *(uint8_t *)buf_append(st->buff,1)=SLIP_ESC;
-		    break;
-		default:
-		    fatal("userv_afterpoll: bad SLIP escape character\n");
-		}
-	    } else {
-		switch (rxbuf[i]) {
-		case SLIP_END:
-		    if (st->buff->size>0) {
-			st->netlink_to_tunnel(&st->nl,NULL,
-					      st->buff);
-			BUF_ALLOC(st->buff,"userv_afterpoll");
-		    }
-		    buffer_init(st->buff,st->nl.max_start_pad);
-		    break;
-		case SLIP_ESC:
-		    st->pending_esc=True;
-		    break;
-		default:
-		    *(uint8_t *)buf_append(st->buff,1)=rxbuf[i];
-		    break;
-		}
-	    }
-	}
-    }
-}
-
-/* Send buf to the kernel. Free buf before returning. */
-static void userv_deliver_to_kernel(void *sst, void *cid,
-				    struct buffer_if *buf)
-{
-    struct userv *st=sst;
-    uint8_t txbuf[DEFAULT_BUFSIZE];
-    uint8_t *i;
-    uint32_t j;
-
-    BUF_ASSERT_USED(buf);
-
-    /* Spit the packet at userv-ipif: SLIP start marker, then
-       bytestuff the packet, then SLIP end marker */
-    /* XXX crunchy bytestuff code */
-    j=0;
-    txbuf[j++]=SLIP_END;
-    for (i=buf->start; i<(buf->start+buf->size); i++) {
-	switch (*i) {
-	case SLIP_END:
-	    txbuf[j++]=SLIP_ESC;
-	    txbuf[j++]=SLIP_ESCEND;
-	    break;
-	case SLIP_ESC:
-	    txbuf[j++]=SLIP_ESC;
-	    txbuf[j++]=SLIP_ESCESC;
-	    break;
-	default:
-	    txbuf[j++]=*i;
-	    break;
-	}
-    }
-    txbuf[j++]=SLIP_END;
-    if (write(st->txfd,txbuf,j)<0) {
-	fatal_perror("userv_deliver_to_kernel: write()");
-    }
-    BUF_FREE(buf);
-}
-
-static void userv_phase_hook(void *sst, uint32_t newphase)
-{
-    struct userv *st=sst;
-    pid_t child;
-    int c_stdin[2];
-    int c_stdout[2];
-    string_t addrs;
-    string_t nets;
-    string_t s;
-    struct netlink_client *c;
-    int i;
-
-    /* This is where we actually invoke userv - all the networks we'll
-       be using should already have been registered. */
-
-    addrs=safe_malloc(512,"userv_phase_hook:addrs");
-    snprintf(addrs,512,"%s,%s,%d,slip",ipaddr_to_string(st->nl.local_address),
-	     ipaddr_to_string(st->nl.secnet_address),st->nl.mtu);
-
-    nets=safe_malloc(1024,"userv_phase_hook:nets");
-    *nets=0;
-    for (c=st->nl.clients; c; c=c->next) {
-	for (i=0; i<c->networks->entries; i++) {
-	    s=subnet_to_string(&c->networks->list[i]);
-	    strcat(nets,s);
-	    strcat(nets,",");
-	    free(s);
-	}
-    }
-    nets[strlen(nets)-1]=0;
-
-    Message(M_INFO,"\nuserv_phase_hook: %s %s %s %s %s\n",st->userv_path,
-	   st->service_user,st->service_name,addrs,nets);
-
-    /* Allocate buffer, plus space for padding. Make sure we end up
-       with the start of the packet well-aligned. */
-    /* ALIGN(st->max_start_pad,16); */
-    /* ALIGN(st->max_end_pad,16); */
-
-    st->pending_esc=False;
-
-    /* Invoke userv */
-    if (pipe(c_stdin)!=0) {
-	fatal_perror("userv_phase_hook: pipe(c_stdin)");
-    }
-    if (pipe(c_stdout)!=0) {
-	fatal_perror("userv_phase_hook: pipe(c_stdout)");
-    }
-    st->txfd=c_stdin[1];
-    st->rxfd=c_stdout[0];
-
-    child=fork();
-    if (child==-1) {
-	fatal_perror("userv_phase_hook: fork()");
-    }
-    if (child==0) {
-	char **argv;
-
-	/* We are the child. Modify our stdin and stdout, then exec userv */
-	dup2(c_stdin[0],0);
-	dup2(c_stdout[1],1);
-	close(c_stdin[1]);
-	close(c_stdout[0]);
-
-	/* The arguments are:
-	   userv
-	   service-user
-	   service-name
-	   local-addr,secnet-addr,mtu,protocol
-	   route1,route2,... */
-	argv=malloc(sizeof(*argv)*6);
-	argv[0]=st->userv_path;
-	argv[1]=st->service_user;
-	argv[2]=st->service_name;
-	argv[3]=addrs;
-	argv[4]=nets;
-	argv[5]=NULL;
-	execvp(st->userv_path,argv);
-	perror("netlink-userv-ipif: execvp");
-
-	exit(1);
-    }
-    /* We are the parent... */
-	   
-    /* Register for poll() */
-    register_for_poll(st, userv_beforepoll, userv_afterpoll, 2, st->nl.name);
-}
-
-static list_t *userv_apply(closure_t *self, struct cloc loc, dict_t *context,
-			   list_t *args)
-{
-    struct userv *st;
-    item_t *item;
-    dict_t *dict;
-
-    st=safe_malloc(sizeof(*st),"userv_apply");
-
-    /* First parameter must be a dict */
-    item=list_elem(args,0);
-    if (!item || item->type!=t_dict)
-	cfgfatal(loc,"userv-ipif","parameter must be a dictionary\n");
-    
-    dict=item->data.dict;
-
-    st->netlink_to_tunnel=
-	netlink_init(&st->nl,st,loc,dict,
-		     "netlink-userv-ipif",userv_deliver_to_kernel);
-
-    st->userv_path=dict_read_string(dict,"userv-path",False,"userv-netlink",
-				    loc);
-    st->service_user=dict_read_string(dict,"service-user",False,
-				      "userv-netlink",loc);
-    st->service_name=dict_read_string(dict,"service-name",False,
-				      "userv-netlink",loc);
-    if (!st->userv_path) st->userv_path="userv";
-    if (!st->service_user) st->service_user="root";
-    if (!st->service_name) st->service_name="ipif";
-    st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"userv-netlink",loc);
-    BUF_ALLOC(st->buff,"netlink:userv_apply");
-
-    st->rxfd=-1; st->txfd=-1;
-    add_hook(PHASE_DROPPRIV,userv_phase_hook,st);
-
-    return new_closure(&st->nl.cl);
-}
-
-/* Connection to the kernel through the universal TUN/TAP driver */
-
-struct tun {
-    struct netlink nl;
-    int fd;
-    string_t device_path;
-    string_t interface_name;
-    string_t ifconfig_path;
-    string_t route_path;
-    struct buffer_if *buff; /* We receive packets into here
-			       and send them to the netlink code. */
-    netlink_deliver_fn *netlink_to_tunnel;
-};
-
-static int tun_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
-			  int *timeout_io, const struct timeval *tv_now,
-			  uint64_t *now)
-{
-    struct tun *st=sst;
-    *nfds_io=1;
-    fds[0].fd=st->fd;
-    fds[0].events=POLLIN|POLLERR|POLLHUP;
-    return 0;
-}
-
-static void tun_afterpoll(void *sst, struct pollfd *fds, int nfds,
-			    const struct timeval *tv_now, uint64_t *now)
-{
-    struct tun *st=sst;
-    int l;
-
-    if (fds[0].revents&POLLERR) {
-	printf("tun_afterpoll: hup!\n");
-    }
-    if (fds[0].revents&POLLIN) {
-	BUF_ALLOC(st->buff,"tun_afterpoll");
-	buffer_init(st->buff,st->nl.max_start_pad);
-	l=read(st->fd,st->buff->start,st->buff->len-st->nl.max_start_pad);
-	if (l<0) {
-	    fatal_perror("tun_afterpoll: read()");
-	}
-	if (l==0) {
-	    fatal("tun_afterpoll: read()=0; device gone away?\n");
-	}
-	if (l>0) {
-	    st->buff->size=l;
-	    st->netlink_to_tunnel(&st->nl,NULL,st->buff);
-	    BUF_ASSERT_FREE(st->buff);
-	}
-    }
-}
-
-static void tun_deliver_to_kernel(void *sst, void *cid,
-				  struct buffer_if *buf)
-{
-    struct tun *st=sst;
-
-    BUF_ASSERT_USED(buf);
-
-    /* No error checking, because we'd just throw the packet away anyway */
-    write(st->fd,buf->start,buf->size);
-    BUF_FREE(buf);
-}
-
-static void tun_phase_hook(void *sst, uint32_t newphase)
-{
-    struct tun *st=sst;
-    string_t hostaddr,secnetaddr;
-    uint8_t mtu[6];
-    string_t network,mask;
-    struct netlink_client *c;
-    int i;
-
-    /* All the networks we'll be using have been registered. Invoke ifconfig
-       to set the TUN device's address, and route to add routes to all
-       our networks. */
-
-    hostaddr=ipaddr_to_string(st->nl.local_address);
-    secnetaddr=ipaddr_to_string(st->nl.secnet_address);
-    snprintf(mtu,6,"%d",st->nl.mtu);
-    mtu[5]=0;
-
-    sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
-	    hostaddr,"netmask","255.255.255.255","-broadcast",
-	    "pointopoint",secnetaddr,"mtu",mtu,"up",(char *)0);
-
-    for (c=st->nl.clients; c; c=c->next) {
-	for (i=0; i<c->networks->entries; i++) {
-	    network=ipaddr_to_string(c->networks->list[i].prefix);
-	    mask=ipaddr_to_string(c->networks->list[i].mask);
-	    sys_cmd(st->route_path,"route","add","-net",network,
-		    "netmask",mask,"gw",secnetaddr,(char *)0);
-	}
-    }
-
-    /* Register for poll() */
-    register_for_poll(st, tun_beforepoll, tun_afterpoll, 1, st->nl.name);
-}
-
-#ifdef HAVE_LINUX_IF_H
-static list_t *tun_apply(closure_t *self, struct cloc loc, dict_t *context,
-			 list_t *args)
-{
-    struct tun *st;
-    item_t *item;
-    dict_t *dict;
-    struct ifreq ifr;
-
-    st=safe_malloc(sizeof(*st),"tun_apply");
-
-    /* First parameter must be a dict */
-    item=list_elem(args,0);
-    if (!item || item->type!=t_dict)
-	cfgfatal(loc,"tun","parameter must be a dictionary\n");
-    
-    dict=item->data.dict;
-
-    st->netlink_to_tunnel=
-	netlink_init(&st->nl,st,loc,dict,
-		     "netlink-tun",tun_deliver_to_kernel);
-
-    st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-    st->interface_name=dict_read_string(dict,"interface",False,
-					"tun-netlink",loc);
-    st->ifconfig_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-    st->route_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-
-    if (!st->device_path) st->device_path="/dev/net/tun";
-    if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
-    if (!st->route_path) st->route_path="route";
-    st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
-
-    /* New TUN interface: open the device, then do ioctl TUNSETIFF
-       to set or find out the network interface name. */
-    st->fd=open(st->device_path,O_RDWR);
-    if (st->fd==-1) {
-	fatal_perror("%s: can't open device file %s",st->nl.name,
-		     st->device_path);
-    }
-    memset(&ifr,0,sizeof(ifr));
-    ifr.ifr_flags = IFF_TUN | IFF_NO_PI; /* Just send/receive IP packets,
-					    no extra headers */
-    if (st->interface_name)
-	strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
-    if (ioctl(st->fd,TUNSETIFF,&ifr)<0) {
-	fatal_perror("%s: ioctl(TUNSETIFF)",st->nl.name);
-    }
-    if (!st->interface_name) {
-	st->interface_name=safe_malloc(strlen(ifr.ifr_name)+1,"tun_apply");
-	strcpy(st->interface_name,ifr.ifr_name);
-	Message(M_INFO,"%s: allocated network interface %s\n",st->nl.name,
-		st->interface_name);
-    }
-
-    add_hook(PHASE_DROPPRIV,tun_phase_hook,st);
-
-    return new_closure(&st->nl.cl);
-}
-#endif /* HAVE_LINUX_IF_H */
-
-static list_t *tun_old_apply(closure_t *self, struct cloc loc, dict_t *context,
-			     list_t *args)
-{
-    struct tun *st;
-    item_t *item;
-    dict_t *dict;
-    bool_t search_for_if;
-
-    st=safe_malloc(sizeof(*st),"tun_old_apply");
-
-    Message(M_WARNING,"the tun-old code has never been tested. Please report "
-	    "success or failure to steve@greenend.org.uk\n");
-
-    /* First parameter must be a dict */
-    item=list_elem(args,0);
-    if (!item || item->type!=t_dict)
-	cfgfatal(loc,"tun","parameter must be a dictionary\n");
-    
-    dict=item->data.dict;
-
-    st->netlink_to_tunnel=
-	netlink_init(&st->nl,st,loc,dict,
-		     "netlink-tun",tun_deliver_to_kernel);
-
-    st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-    st->interface_name=dict_read_string(dict,"interface",False,
-					"tun-netlink",loc);
-    search_for_if=dict_read_bool(dict,"interface-search",False,"tun-netlink",
-				 loc,st->device_path==NULL);
-    st->ifconfig_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-    st->route_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
-
-    if (!st->device_path) st->device_path="/dev/tun";
-    if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
-    if (!st->route_path) st->route_path="route";
-    st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
-
-    /* Old TUN interface: the network interface name depends on which
-       /dev/tunX file we open. If 'interface-search' is set to true, treat
-       'device' as the prefix and try numbers from 0--255. If it's set
-       to false, treat 'device' as the whole name, and require than an
-       appropriate interface name be specified. */
-    if (search_for_if) {
-	string_t dname;
-	int i;
-
-	if (st->interface_name) {
-	    cfgfatal(loc,"tun-old","you may not specify an interface name "
-		     "in interface-search mode\n");
-	}
-	dname=safe_malloc(strlen(st->device_path)+4,"tun_old_apply");
-	st->interface_name=safe_malloc(8,"tun_old_apply");
-	
-	for (i=0; i<255; i++) {
-	    sprintf(dname,"%s%d",st->device_path,i);
-	    if ((st->fd=open(dname,O_RDWR))>0) {
-		sprintf(st->interface_name,"tun%d",i);
-		Message(M_INFO,"%s: allocated network interface %s "
-			"through %s\n",st->nl.name,st->interface_name,dname);
-		continue;
-	    }
-	}
-	if (st->fd==-1) {
-	    fatal("%s: unable to open any TUN device (%s...)\n",
-		  st->nl.name,st->device_path);
-	}
-    } else {
-	if (!st->interface_name) {
-	    cfgfatal(loc,"tun-old","you must specify an interface name "
-		     "when you explicitly specify a TUN device file\n");
-	}
-	st->fd=open(st->device_path,O_RDWR);
-	if (st->fd==-1) {
-	    fatal_perror("%s: unable to open TUN device file %s",
-			 st->nl.name,st->device_path);
-	}
-    }
+    add_hook(PHASE_SETUP,netlink_phase_hook,st);
 
-    add_hook(PHASE_DROPPRIV,tun_phase_hook,st);
-
-    return new_closure(&st->nl.cl);
+    return netlink_incoming;
 }
 
 /* No connection to the kernel at all... */
@@ -1086,6 +680,22 @@ struct null {
     struct netlink nl;
 };
 
+static bool_t null_set_route(void *sst, struct netlink_route *route)
+{
+    struct null *st=sst;
+    string_t t;
+
+    if (route->up!=route->kup) {
+	t=subnet_to_string(&route->net);
+	Message(M_INFO,"%s: setting route %s to state %s\n",st->nl.name,
+		t, route->up?"up":"down");
+	free(t);
+	route->kup=route->up;
+	return True;
+    }
+    return False;
+}
+	    
 static void null_deliver(void *sst, void *cid, struct buffer_if *buf)
 {
     return;
@@ -1106,7 +716,8 @@ static list_t *null_apply(closure_t *self, struct cloc loc, dict_t *context,
     
     dict=item->data.dict;
 
-    netlink_init(&st->nl,st,loc,dict,"null-netlink",null_deliver);
+    netlink_init(&st->nl,st,loc,dict,"null-netlink",null_set_route,
+		 null_deliver);
 
     return new_closure(&st->nl.cl);
 }
@@ -1114,15 +725,5 @@ static list_t *null_apply(closure_t *self, struct cloc loc, dict_t *context,
 init_module netlink_module;
 void netlink_module(dict_t *dict)
 {
-    add_closure(dict,"userv-ipif",userv_apply);
-#ifdef HAVE_LINUX_IF_H
-    add_closure(dict,"tun",tun_apply);
-#endif
-    add_closure(dict,"tun-old",tun_old_apply);
     add_closure(dict,"null-netlink",null_apply);
-#if 0
-    /* TODO */
-    add_closure(dict,"pty-slip",ptyslip_apply);
-    add_closure(dict,"slipd",slipd_apply);
-#endif /* 0 */
 }