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