net/x25/x25_forward.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      History
   4  *      03-01-2007      Added forwarding for x.25       Andrew Hendry
   5  */
   6
   7 #define pr_fmt(fmt) "X25: " fmt
   8
   9 #include <linux/if_arp.h>
  10 #include <linux/init.h>
  11 #include <linux/slab.h>
  12 #include <net/x25.h>
  13
  14 LIST_HEAD(x25_forward_list);
  15 DEFINE_RWLOCK(x25_forward_list_lock);
  16
  17 int x25_forward_call(struct x25_address *dest_addr, struct x25_neigh *from,
  18                         struct sk_buff *skb, int lci)
  19 {
  20         struct x25_route *rt;
  21         struct x25_neigh *neigh_new = NULL;
  22         struct list_head *entry;
  23         struct x25_forward *x25_frwd, *new_frwd;
  24         struct sk_buff *skbn;
  25         short same_lci = 0;
  26         int rc = 0;
  27
  28         if ((rt = x25_get_route(dest_addr)) == NULL)
  29                 goto out_no_route;
  30
  31         if ((neigh_new = x25_get_neigh(rt->dev)) == NULL) {
  32                 /* This shouldn't happen, if it occurs somehow
  33                  * do something sensible
  34                  */
  35                 goto out_put_route;
  36         }
  37
  38         /* Avoid a loop. This is the normal exit path for a
  39          * system with only one x.25 iface and default route
  40          */
  41         if (rt->dev == from->dev) {
  42                 goto out_put_nb;
  43         }
  44
  45         /* Remote end sending a call request on an already
  46          * established LCI? It shouldn't happen, just in case..
  47          */
  48         read_lock_bh(&x25_forward_list_lock);
  49         list_for_each(entry, &x25_forward_list) {
  50                 x25_frwd = list_entry(entry, struct x25_forward, node);
  51                 if (x25_frwd->lci == lci) {
  52                         pr_warn("call request for lci which is already registered!, transmitting but not registering new pair\n");
  53                         same_lci = 1;
  54                 }
  55         }
  56         read_unlock_bh(&x25_forward_list_lock);
  57
  58         /* Save the forwarding details for future traffic */
  59         if (!same_lci){
  60                 if ((new_frwd = kmalloc(sizeof(struct x25_forward),
  61                                                 GFP_ATOMIC)) == NULL){
  62                         rc = -ENOMEM;
  63                         goto out_put_nb;
  64                 }
  65                 new_frwd->lci = lci;
  66                 new_frwd->dev1 = rt->dev;
  67                 new_frwd->dev2 = from->dev;
  68                 write_lock_bh(&x25_forward_list_lock);
  69                 list_add(&new_frwd->node, &x25_forward_list);
  70                 write_unlock_bh(&x25_forward_list_lock);
  71         }
  72
  73         /* Forward the call request */
  74         if ( (skbn = skb_clone(skb, GFP_ATOMIC)) == NULL){
  75                 goto out_put_nb;
  76         }
  77         x25_transmit_link(skbn, neigh_new);
  78         rc = 1;
  79
  80
  81 out_put_nb:
  82         x25_neigh_put(neigh_new);
  83
  84 out_put_route:
  85         x25_route_put(rt);
  86
  87 out_no_route:
  88         return rc;
  89 }
  90
  91
  92 int x25_forward_data(int lci, struct x25_neigh *from, struct sk_buff *skb) {
  93
  94         struct x25_forward *frwd;
  95         struct list_head *entry;
  96         struct net_device *peer = NULL;
  97         struct x25_neigh *nb;
  98         struct sk_buff *skbn;
  99         int rc = 0;
 100
 101         read_lock_bh(&x25_forward_list_lock);
 102         list_for_each(entry, &x25_forward_list) {
 103                 frwd = list_entry(entry, struct x25_forward, node);
 104                 if (frwd->lci == lci) {
 105                         /* The call is established, either side can send */
 106                         if (from->dev == frwd->dev1) {
 107                                 peer = frwd->dev2;
 108                         } else {
 109                                 peer = frwd->dev1;
 110                         }
 111                         break;
 112                 }
 113         }
 114         read_unlock_bh(&x25_forward_list_lock);
 115
 116         if ( (nb = x25_get_neigh(peer)) == NULL)
 117                 goto out;
 118
 119         if ( (skbn = pskb_copy(skb, GFP_ATOMIC)) == NULL){
 120                 goto output;
 121
 122         }
 123         x25_transmit_link(skbn, nb);
 124
 125         rc = 1;
 126 output:
 127         x25_neigh_put(nb);
 128 out:
 129         return rc;
 130 }
 131
 132 void x25_clear_forward_by_lci(unsigned int lci)
 133 {
 134         struct x25_forward *fwd, *tmp;
 135
 136         write_lock_bh(&x25_forward_list_lock);
 137
 138         list_for_each_entry_safe(fwd, tmp, &x25_forward_list, node) {
 139                 if (fwd->lci == lci) {
 140                         list_del(&fwd->node);
 141                         kfree(fwd);
 142                 }
 143         }
 144         write_unlock_bh(&x25_forward_list_lock);
 145 }
 146
 147
 148 void x25_clear_forward_by_dev(struct net_device *dev)
 149 {
 150         struct x25_forward *fwd, *tmp;
 151
 152         write_lock_bh(&x25_forward_list_lock);
 153
 154         list_for_each_entry_safe(fwd, tmp, &x25_forward_list, node) {
 155                 if ((fwd->dev1 == dev) || (fwd->dev2 == dev)){
 156                         list_del(&fwd->node);
 157                         kfree(fwd);
 158                 }
 159         }
 160         write_unlock_bh(&x25_forward_list_lock);
 161 }