add filtering
[l2tpns.git] / l2tpns.c
index de3929d..a1f30a2 100644 (file)
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -4,7 +4,7 @@
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 
-char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.56 2004/11/25 02:49:18 bodea Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.59 2004/11/28 20:10:04 bodea Exp $";
 
 #include <arpa/inet.h>
 #include <assert.h>
@@ -54,7 +54,7 @@ char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.56 2004/11/25 02:49:18 bodea Exp
 #endif /* BGP */
 
 // Globals
-struct configt *config = NULL; // all configuration
+configt *config = NULL;                // all configuration
 int tunfd = -1;                        // tun interface file handle. (network device)
 int udpfd = -1;                        // UDP file handle
 int controlfd = -1;            // Control signal handle
@@ -88,9 +88,9 @@ linked_list *loaded_plugins;
 linked_list *plugins[MAX_PLUGIN_TYPES];
 
 #define membersize(STRUCT, MEMBER) sizeof(((STRUCT *)0)->MEMBER)
-#define CONFIG(NAME, MEMBER, TYPE) { NAME, offsetof(struct configt, MEMBER), membersize(struct configt, MEMBER), TYPE }
+#define CONFIG(NAME, MEMBER, TYPE) { NAME, offsetof(configt, MEMBER), membersize(configt, MEMBER), TYPE }
 
-struct config_descriptt config_values[] = {
+config_descriptt config_values[] = {
        CONFIG("debug", debug, INT),
        CONFIG("log_file", log_filename, STRING),
        CONFIG("pid_file", pid_file, STRING),
@@ -146,6 +146,7 @@ sessiont *session = NULL;           // Array of session structures.
 sessioncountt *sess_count = NULL;      // Array of partial per-session traffic counters.
 radiust *radius = NULL;                        // Array of radius structures.
 ippoolt *ip_address_pool = NULL;       // Array of dynamic IP addresses.
+ip_filtert *ip_filters = NULL; // Array of named filters.
 static controlt *controlfree = 0;
 struct Tstats *_statistics = NULL;
 #ifdef RINGBUFFER
@@ -763,6 +764,10 @@ static void processipout(u8 * buf, int len)
        t = session[s].tunnel;
        sp = &session[s];
 
+       // run access-list if any
+       if (session[s].filter_out && !ip_filter(buf, len, session[s].filter_out - 1))
+               return;
+
        if (sp->tbf_out)
        {
                // Are we throttling this session?
@@ -942,8 +947,10 @@ static void controladd(controlt * c, tunnelidt t, sessionidt s)
                tunnel[t].controle->next = c;
        else
                tunnel[t].controls = c;
+
        tunnel[t].controle = c;
        tunnel[t].controlc++;
+
        // send now if space in window
        if (tunnel[t].controlc <= tunnel[t].window)
        {
@@ -999,6 +1006,44 @@ void throttle_session(sessionidt s, int rate_in, int rate_out)
        }
 }
 
+// add/remove filters from session (-1 = no change)
+void filter_session(sessionidt s, int filter_in, int filter_out)
+{
+       if (!session[s].tunnel)
+               return; // No-one home.
+
+       if (!*session[s].user)
+               return; // User not logged in
+
+       // paranoia
+       if (filter_in > MAXFILTER) filter_in = -1;
+       if (filter_out > MAXFILTER) filter_out = -1;
+       if (session[s].filter_in > MAXFILTER) session[s].filter_in = 0;
+       if (session[s].filter_out > MAXFILTER) session[s].filter_out = 0;
+
+       if (filter_in >= 0)
+       {
+               if (session[s].filter_in)
+                       ip_filters[session[s].filter_in - 1].used--;
+
+               if (filter_in > 0)
+                       ip_filters[filter_in - 1].used++;
+
+               session[s].filter_in = filter_in;
+       }
+
+       if (filter_out >= 0)
+       {
+               if (session[s].filter_out)
+                       ip_filters[session[s].filter_out - 1].used--;
+
+               if (filter_out > 0)
+                       ip_filters[filter_out - 1].used++;
+
+               session[s].filter_out = filter_out;
+       }
+}
+
 // start tidy shutdown of session
 void sessionshutdown(sessionidt s, char *reason)
 {
@@ -1078,6 +1123,10 @@ void sessionshutdown(sessionidt s, char *reason)
        if (!session[s].die)
                session[s].die = now() + 150; // Clean up in 15 seconds
 
+       // update filter refcounts
+       if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
+       if (session[s].filter_out) ip_filters[session[s].filter_out - 1].used--;
+
        cluster_send_session(s);
 }
 
@@ -1306,10 +1355,9 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
                        STAT(tunnel_rx_errors);
                        return;
                }
-               LOG(3, ntohl(addr->sin_addr.s_addr), s, t, "Control message (%d bytes): (unacked %d) l-ns %d l-nr %d r-ns %d r-nr %d\n",
-                               l, tunnel[t].controlc, tunnel[t].ns, tunnel[t].nr, ns, nr);
-               // if no tunnel specified, assign one
-               if (!t)
+
+               // check for duplicate tunnel open message
+               if (!t && ns == 0)
                {
                        int i;
 
@@ -1323,10 +1371,15 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
                                        tunnel[i].port != ntohs(addr->sin_port) )
                                        continue;
                                t = i;
+                               LOG(3, ntohl(addr->sin_addr.s_addr), s, t, "Duplicate SCCRQ?\n");
                                break;
                        }
                }
 
+               LOG(3, ntohl(addr->sin_addr.s_addr), s, t, "Control message (%d bytes): (unacked %d) l-ns %d l-nr %d r-ns %d r-nr %d\n",
+                               l, tunnel[t].controlc, tunnel[t].ns, tunnel[t].nr, ns, nr);
+
+               // if no tunnel specified, assign one
                if (!t)
                {
                        if (!(t = new_tunnel()))
@@ -1339,8 +1392,28 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
                        tunnel[t].ip = ntohl(*(ipt *) & addr->sin_addr);
                        tunnel[t].port = ntohs(addr->sin_port);
                        tunnel[t].window = 4; // default window
-                       LOG(1, ntohl(addr->sin_addr.s_addr), 0, t, "   New tunnel from %u.%u.%u.%u/%u ID %d\n", tunnel[t].ip >> 24, tunnel[t].ip >> 16 & 255, tunnel[t].ip >> 8 & 255, tunnel[t].ip & 255, tunnel[t].port, t);
                        STAT(tunnel_created);
+                       LOG(1, ntohl(addr->sin_addr.s_addr), 0, t, "   New tunnel from %u.%u.%u.%u/%u ID %d\n",
+                               tunnel[t].ip >> 24, tunnel[t].ip >> 16 & 255,
+                               tunnel[t].ip >> 8 & 255, tunnel[t].ip & 255, tunnel[t].port, t);
+               }
+
+                       // If the 'ns' just received is not the 'nr' we're
+                       // expecting, just send an ack and drop it.
+                       //
+                       // if 'ns' is less, then we got a retransmitted packet.
+                       // if 'ns' is greater than missed a packet. Either way
+                       // we should ignore it.
+               if (ns != tunnel[t].nr)
+               {
+                       // is this the sequence we were expecting?
+                       STAT(tunnel_rx_errors);
+                       LOG(1, ntohl(addr->sin_addr.s_addr), 0, t, "   Out of sequence tunnel %d, (%d is not the expected %d)\n",
+                               t, ns, tunnel[t].nr);
+
+                       if (l)  // Is this not a ZLB?
+                               controlnull(t);
+                       return;
                }
 
                // This is used to time out old tunnels
@@ -1350,7 +1423,7 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
                {
                        int skip = tunnel[t].window; // track how many in-window packets are still in queue
                                // some to clear maybe?
-                       while (tunnel[t].controlc && (((tunnel[t].ns - tunnel[t].controlc) - nr) & 0x8000))
+                       while (tunnel[t].controlc > 0 && (((tunnel[t].ns - tunnel[t].controlc) - nr) & 0x8000))
                        {
                                controlt *c = tunnel[t].controls;
                                tunnel[t].controls = c->next;
@@ -1361,22 +1434,6 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
                                tunnel[t].try = 0; // we have progress
                        }
 
-                               // If the 'ns' just received is not the 'nr' we're
-                               // expecting, just send an ack and drop it.
-                               //
-                               // if 'ns' is less, then we got a retransmitted packet.
-                               // if 'ns' is greater than missed a packet. Either way
-                               // we should ignore it.
-                       if (ns != tunnel[t].nr)
-                       {
-                               // is this the sequence we were expecting?
-                               LOG(1, ntohl(addr->sin_addr.s_addr), 0, t, "   Out of sequence tunnel %d, (%d is not the expected %d)\n", t, ns, tunnel[t].nr);
-                               STAT(tunnel_rx_errors);
-
-                               if (l)  // Is this not a ZLB?
-                                       controlnull(t);
-                               return;
-                       }
                        // receiver advance (do here so quoted correctly in any sends below)
                        if (l) tunnel[t].nr = (ns + 1);
                        if (skip < 0) skip = 0;
@@ -2120,6 +2177,22 @@ static int regular_cleanups(void)
                                send++;
                        }
 
+                       if (a & CLI_SESS_NOFILTER)
+                       {
+                               LOG(2, 0, s, session[s].tunnel, "Un-filtering session by CLI\n");
+                               filter_session(s, 0, 0);
+                               send++;
+                       }
+                       else if (a & CLI_SESS_FILTER)
+                       {
+                               LOG(2, 0, s, session[s].tunnel, "Filtering session by CLI (in=%d, out=%d)\n",
+                                   cli_session_actions[s].filter_in,
+                                   cli_session_actions[s].filter_out);
+
+                               filter_session(s, cli_session_actions[s].filter_in, cli_session_actions[s].filter_out);
+                               send++;
+                       }
+
                        if (send)
                                cluster_send_session(s);
 
@@ -2480,12 +2553,12 @@ static void initdata(int optdebug, char *optconfig)
                LOG(0, 0, 0, 0, "Error doing malloc for _statistics: %s\n", strerror(errno));
                exit(1);
        }
-       if (!(config = shared_malloc(sizeof(struct configt))))
+       if (!(config = shared_malloc(sizeof(configt))))
        {
                LOG(0, 0, 0, 0, "Error doing malloc for configuration: %s\n", strerror(errno));
                exit(1);
        }
-       memset(config, 0, sizeof(struct configt));
+       memset(config, 0, sizeof(configt));
        time(&config->start_time);
        strncpy(config->config_file, optconfig, strlen(optconfig));
        config->debug = optdebug;
@@ -2521,6 +2594,13 @@ static void initdata(int optdebug, char *optconfig)
                exit(1);
        }
 
+if (!(ip_filters = shared_malloc(sizeof(ip_filtert) * MAXFILTER)))
+{
+       LOG(0, 0, 0, 0, "Error doing malloc for ip_filters: %s\n", strerror(errno));
+       exit(1);
+}
+memset(ip_filters, 0, sizeof(ip_filtert) * MAXFILTER);
+
 #ifdef RINGBUFFER
        if (!(ringbuffer = shared_malloc(sizeof(struct Tringbuffer))))
        {
@@ -2572,11 +2652,11 @@ static void initdata(int optdebug, char *optconfig)
        _statistics->start_time = _statistics->last_reset = time(NULL);
 
 #ifdef BGP
-       if (!(bgp_peers = shared_malloc(sizeof(struct bgp_peer) * BGP_NUM_PEERS)))
-       {
-               LOG(0, 0, 0, 0, "Error doing malloc for bgp: %s\n", strerror(errno));
-               exit(1);
-       }
+       if (!(bgp_peers = shared_malloc(sizeof(struct bgp_peer) * BGP_NUM_PEERS)))
+       {
+               LOG(0, 0, 0, 0, "Error doing malloc for bgp: %s\n", strerror(errno));
+               exit(1);
+       }
 #endif /* BGP */
 }
 
@@ -3711,6 +3791,31 @@ int load_session(sessionidt s, sessiont *new)
                }
        }
 
+       // check filters
+       if (new->filter_in && (new->filter_in > MAXFILTER || !ip_filters[new->filter_in - 1].name[0]))
+       {
+               LOG(2, session[s].ip, s, session[s].tunnel, "Dropping invalid input filter %d\n", (int) new->filter_in);
+               new->filter_in = 0;
+       }
+
+       if (new->filter_out && (new->filter_out > MAXFILTER || !ip_filters[new->filter_out - 1].name[0]))
+       {
+               LOG(2, session[s].ip, s, session[s].tunnel, "Dropping invalid output filter %d\n", (int) new->filter_out);
+               new->filter_out = 0;
+       }
+
+       if (new->filter_in != session[s].filter_in)
+       {
+               if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
+               if (new->filter_in)       ip_filters[new->filter_in - 1].used++;
+       }
+
+       if (new->filter_out != session[s].filter_out)
+       {
+               if (session[s].filter_out) ip_filters[session[s].filter_out - 1].used--;
+               if (new->filter_out)       ip_filters[new->filter_out - 1].used++;
+       }
+
        if (new->tunnel && s > config->cluster_highest_sessionid)       // Maintain this in the slave. It's used
                                        // for walking the sessions to forward byte counts to the master.
                config->cluster_highest_sessionid = s;
@@ -4279,3 +4384,107 @@ static int unhide_avp(u8 *avp, tunnelidt t, sessionidt s, u16 length)
        return hidden_length + 6;
 }
 
+static int ip_filter_port(ip_filter_portt *p, portt port)
+{
+       switch (p->op)
+       {
+       case FILTER_PORT_OP_EQ:    return port == p->port;
+       case FILTER_PORT_OP_NEQ:   return port != p->port;
+       case FILTER_PORT_OP_GT:    return port > p->port;
+       case FILTER_PORT_OP_LT:    return port < p->port;
+       case FILTER_PORT_OP_RANGE: return port >= p->port && port <= p->port2;
+       }
+
+       return 0;
+}
+
+static int ip_filter_flag(u8 op, u8 sflags, u8 cflags, u8 flags)
+{
+       switch (op)
+       {
+       /*
+        * NOTE: "match-any +A +B -C -D" is interpreted as "match if
+        * either A or B is set *and* C or D is clear".  While "or" is
+        * possibly more correct, the way "established" is currently
+        * implemented depends on this behaviour.
+        */
+       case FILTER_FLAG_OP_ANY:
+               return (flags & sflags) && !(flags & cflags);
+
+       case FILTER_FLAG_OP_ALL:
+               return (flags & sflags) == sflags && (~flags & cflags) == cflags;
+       }
+
+       return 0;
+}
+
+int ip_filter(u8 *buf, int len, u8 filter)
+{
+       u8 proto;
+       ipt src_ip;
+       ipt dst_ip;
+       portt src_port = 0;
+       portt dst_port = 0;
+       u8 flags = 0;
+       ip_filter_rulet *rule;
+
+       if (len < 20) // up to end of destination address
+               return 0;
+
+       if (*buf >> 4) // IPv4
+               return 0;
+
+       proto = buf[9];
+       src_ip = *(u32 *) (buf + 12);
+       dst_ip = *(u32 *) (buf + 16);
+
+       if (proto == IPPROTO_TCP || proto == IPPROTO_UDP)
+       {
+               int l = buf[0] & 0xf;
+               if (len < l + 4) // ports
+                       return 0;
+
+               src_port = ntohs(*(u16 *) (buf + l));
+               dst_port = ntohs(*(u16 *) (buf + l + 2));
+               if (proto == IPPROTO_TCP)
+               {
+                       if (len < l + 15) // flags
+                               return 0;
+
+                       flags = buf[l + 14] & 0x3f;
+               }
+       }
+
+       for (rule = ip_filters[filter].rules; rule->action; rule++)
+       {
+               if (proto && proto != rule->proto)
+                       continue;
+
+               if (rule->src_wild != INADDR_BROADCAST &&
+                   (src_ip & ~rule->src_wild) != (rule->src_ip & ~rule->src_wild))
+                       continue;
+
+               if (rule->dst_wild != INADDR_BROADCAST &&
+                   (dst_ip & ~rule->dst_wild) != (rule->dst_ip & ~rule->dst_wild))
+                       continue;
+
+               if (proto == IPPROTO_TCP || proto == IPPROTO_UDP)
+               {
+                       if (rule->src_ports.op && !ip_filter_port(&rule->src_ports, src_port))
+                               continue;
+
+                       if (rule->dst_ports.op && !ip_filter_port(&rule->dst_ports, dst_port))
+                               continue;
+
+                       if (proto == IPPROTO_TCP && rule->tcp_flag_op &&
+                           !ip_filter_flag(rule->tcp_flag_op, rule->tcp_sflags, rule->tcp_cflags, flags))
+                               continue;
+               }
+
+               // matched
+               return rule->action == FILTER_ACTION_PERMIT;
+       }
+
+       // default deny
+       return 0;
+}