netlink: Set "unused" in ICMP header (SECURITY)

[secnet] / netlink.c

diff --git a/netlink.c b/netlink.c
index 6384c02..87b6671 100644 (file)
--- a/netlink.c
+++ b/netlink.c
@@ -193,6 +193,10 @@ struct iphdr {
     uint16_t   tot_len;
     uint16_t   id;
     uint16_t   frag_off;
+#define IPHDR_FRAG_OFF  ((uint16_t)0x1fff)
+#define IPHDR_FRAG_MORE ((uint16_t)0x2000)
+#define IPHDR_FRAG_DONT ((uint16_t)0x4000)
+/*                 reserved        0x8000 */
     uint8_t    ttl;
     uint8_t    protocol;
     uint16_t   check;
@@ -206,7 +210,7 @@ struct icmphdr {
     uint8_t type;
     uint8_t code;
     uint16_t check;
-    union {
+    union icmpinfofield {
        uint32_t unused;
        struct {
            uint8_t pointer;
@@ -220,6 +224,8 @@ struct icmphdr {
        } echo;
     } d;
 };
+
+static const union icmpinfofield icmp_noinfo;
     
 static void netlink_packet_deliver(struct netlink *st,
                                   struct netlink_client *client,
@@ -305,7 +311,7 @@ static bool_t netlink_icmp_may_reply(struct buffer_if *buf)
        }
     }
     /* How do we spot broadcast destination addresses? */
-    if (ntohs(iph->frag_off)&0x1fff) return False; /* Non-initial fragment */
+    if (ntohs(iph->frag_off)&IPHDR_FRAG_OFF) return False;
     source=ntohl(iph->saddr);
     if (source==0) return False;
     if ((source&0xff000000)==0x7f000000) return False;
@@ -354,7 +360,8 @@ static uint16_t netlink_icmp_reply_len(struct buffer_if *buf)
    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)
+                               uint8_t type, uint8_t code,
+                               union icmpinfofield info)
 {
     struct icmphdr *h;
     uint16_t len;
@@ -363,7 +370,7 @@ static void netlink_icmp_simple(struct netlink *st, struct buffer_if *buf,
        struct iphdr *iph=(struct iphdr *)buf->start;
        len=netlink_icmp_reply_len(buf);
        h=netlink_icmp_tmpl(st,ntohl(iph->saddr),len);
-       h->type=type; h->code=code;
+       h->type=type; h->code=code; h->d=info;
        memcpy(buf_append(&st->icmp,len),buf->start,len);
        netlink_icmp_csum(h);
        netlink_packet_deliver(st,NULL,&st->icmp);
@@ -521,7 +528,7 @@ static void netlink_packet_deliver(struct netlink *st,
                    "(s=%s, d=%s)\n", st->name, s, d);
            free(s); free(d);
            netlink_icmp_simple(st,buf,client,ICMP_TYPE_UNREACHABLE,
-                               ICMP_CODE_NET_UNREACHABLE);
+                               ICMP_CODE_NET_UNREACHABLE, icmp_noinfo);
            BUF_FREE(buf);
        }
     } else {
@@ -538,7 +545,7 @@ static void netlink_packet_deliver(struct netlink *st,
            free(s); free(d);
                    
            netlink_icmp_simple(st,buf,client,ICMP_TYPE_UNREACHABLE,
-                               ICMP_CODE_NET_PROHIBITED);
+                               ICMP_CODE_NET_PROHIBITED, icmp_noinfo);
            BUF_FREE(buf);
        } else {
            if (best_quality>0) {
@@ -548,8 +555,10 @@ static void netlink_packet_deliver(struct netlink *st,
                BUF_ASSERT_FREE(buf);
            } else {
                /* Generate ICMP destination unreachable */
-               netlink_icmp_simple(st,buf,client,ICMP_TYPE_UNREACHABLE,
-                                   ICMP_CODE_NET_UNREACHABLE); /* client==NULL */
+               netlink_icmp_simple(st,buf,client,/* client==NULL */
+                                   ICMP_TYPE_UNREACHABLE,
+                                   ICMP_CODE_NET_UNREACHABLE,
+                                   icmp_noinfo);
                BUF_FREE(buf);
            }
        }
@@ -570,7 +579,7 @@ static void netlink_packet_forward(struct netlink *st,
     if (iph->ttl<=1) {
        /* Generate ICMP time exceeded */
        netlink_icmp_simple(st,buf,client,ICMP_TYPE_TIME_EXCEEDED,
-                           ICMP_CODE_TTL_EXCEEDED);
+                           ICMP_CODE_TTL_EXCEEDED,icmp_noinfo);
        BUF_FREE(buf);
        return;
     }
@@ -599,7 +608,7 @@ static void netlink_packet_local(struct netlink *st,
     }
     h=(struct icmphdr *)buf->start;
 
-    if ((ntohs(h->iph.frag_off)&0xbfff)!=0) {
+    if ((ntohs(h->iph.frag_off)&(IPHDR_FRAG_OFF|IPHDR_FRAG_MORE))!=0) {
        Message(M_WARNING,"%s: fragmented packet addressed to secnet; "
                "ignoring it\n",st->name);
        BUF_FREE(buf);
@@ -625,7 +634,7 @@ static void netlink_packet_local(struct netlink *st,
     } else {
        /* Send ICMP protocol unreachable */
        netlink_icmp_simple(st,buf,client,ICMP_TYPE_UNREACHABLE,
-                           ICMP_CODE_PROTOCOL_UNREACHABLE);
+                           ICMP_CODE_PROTOCOL_UNREACHABLE,icmp_noinfo);
        BUF_FREE(buf);
        return;
     }
@@ -765,7 +774,7 @@ static void netlink_dump_routes(struct netlink *st, bool_t requested)
     if (requested) c=M_WARNING;
     if (st->ptp) {
        net=ipaddr_to_string(st->secnet_address);
-       Message(c,"%s: point-to-point (remote end is %s); routes:\n",
+       Message(c,"%s: point-to-point (remote end is %s); routes: ",
                st->name, net);
        free(net);
        netlink_output_subnets(st,c,st->clients->subnets);