net/x25/x25_forward.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  History
0004  *  03-01-2007  Added forwarding for x.25   Andrew Hendry
0005  */
0006
0007 #define pr_fmt(fmt) "X25: " fmt
0008
0009 #include <linux/if_arp.h>
0010 #include <linux/init.h>
0011 #include <linux/slab.h>
0012 #include <net/x25.h>
0013
0014 LIST_HEAD(x25_forward_list);
0015 DEFINE_RWLOCK(x25_forward_list_lock);
0016
0017 int x25_forward_call(struct x25_address *dest_addr, struct x25_neigh *from,
0018             struct sk_buff *skb, int lci)
0019 {
0020     struct x25_route *rt;
0021     struct x25_neigh *neigh_new = NULL;
0022     struct x25_forward *x25_frwd, *new_frwd;
0023     struct sk_buff *skbn;
0024     short same_lci = 0;
0025     int rc = 0;
0026
0027     if ((rt = x25_get_route(dest_addr)) == NULL)
0028         goto out_no_route;
0029
0030     if ((neigh_new = x25_get_neigh(rt->dev)) == NULL) {
0031         /* This shouldn't happen, if it occurs somehow
0032          * do something sensible
0033          */
0034         goto out_put_route;
0035     }
0036
0037     /* Avoid a loop. This is the normal exit path for a
0038      * system with only one x.25 iface and default route
0039      */
0040     if (rt->dev == from->dev) {
0041         goto out_put_nb;
0042     }
0043
0044     /* Remote end sending a call request on an already
0045      * established LCI? It shouldn't happen, just in case..
0046      */
0047     read_lock_bh(&x25_forward_list_lock);
0048     list_for_each_entry(x25_frwd, &x25_forward_list, node) {
0049         if (x25_frwd->lci == lci) {
0050             pr_warn("call request for lci which is already registered!, transmitting but not registering new pair\n");
0051             same_lci = 1;
0052         }
0053     }
0054     read_unlock_bh(&x25_forward_list_lock);
0055
0056     /* Save the forwarding details for future traffic */
0057     if (!same_lci){
0058         if ((new_frwd = kmalloc(sizeof(struct x25_forward),
0059                         GFP_ATOMIC)) == NULL){
0060             rc = -ENOMEM;
0061             goto out_put_nb;
0062         }
0063         new_frwd->lci = lci;
0064         new_frwd->dev1 = rt->dev;
0065         new_frwd->dev2 = from->dev;
0066         write_lock_bh(&x25_forward_list_lock);
0067         list_add(&new_frwd->node, &x25_forward_list);
0068         write_unlock_bh(&x25_forward_list_lock);
0069     }
0070
0071     /* Forward the call request */
0072     if ( (skbn = skb_clone(skb, GFP_ATOMIC)) == NULL){
0073         goto out_put_nb;
0074     }
0075     x25_transmit_link(skbn, neigh_new);
0076     rc = 1;
0077
0078
0079 out_put_nb:
0080     x25_neigh_put(neigh_new);
0081
0082 out_put_route:
0083     x25_route_put(rt);
0084
0085 out_no_route:
0086     return rc;
0087 }
0088
0089
0090 int x25_forward_data(int lci, struct x25_neigh *from, struct sk_buff *skb) {
0091
0092     struct x25_forward *frwd;
0093     struct net_device *peer = NULL;
0094     struct x25_neigh *nb;
0095     struct sk_buff *skbn;
0096     int rc = 0;
0097
0098     read_lock_bh(&x25_forward_list_lock);
0099     list_for_each_entry(frwd, &x25_forward_list, node) {
0100         if (frwd->lci == lci) {
0101             /* The call is established, either side can send */
0102             if (from->dev == frwd->dev1) {
0103                 peer = frwd->dev2;
0104             } else {
0105                 peer = frwd->dev1;
0106             }
0107             break;
0108         }
0109     }
0110     read_unlock_bh(&x25_forward_list_lock);
0111
0112     if ( (nb = x25_get_neigh(peer)) == NULL)
0113         goto out;
0114
0115     if ( (skbn = pskb_copy(skb, GFP_ATOMIC)) == NULL){
0116         goto output;
0117
0118     }
0119     x25_transmit_link(skbn, nb);
0120
0121     rc = 1;
0122 output:
0123     x25_neigh_put(nb);
0124 out:
0125     return rc;
0126 }
0127
0128 void x25_clear_forward_by_lci(unsigned int lci)
0129 {
0130     struct x25_forward *fwd, *tmp;
0131
0132     write_lock_bh(&x25_forward_list_lock);
0133
0134     list_for_each_entry_safe(fwd, tmp, &x25_forward_list, node) {
0135         if (fwd->lci == lci) {
0136             list_del(&fwd->node);
0137             kfree(fwd);
0138         }
0139     }
0140     write_unlock_bh(&x25_forward_list_lock);
0141 }
0142
0143
0144 void x25_clear_forward_by_dev(struct net_device *dev)
0145 {
0146     struct x25_forward *fwd, *tmp;
0147
0148     write_lock_bh(&x25_forward_list_lock);
0149
0150     list_for_each_entry_safe(fwd, tmp, &x25_forward_list, node) {
0151         if ((fwd->dev1 == dev) || (fwd->dev2 == dev)){
0152             list_del(&fwd->node);
0153             kfree(fwd);
0154         }
0155     }
0156     write_unlock_bh(&x25_forward_list_lock);
0157 }