1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * File: af_phonet.c
4 *
5 * Phonet protocols family
6 *
7 * Copyright (C) 2008 Nokia Corporation.
8 *
9 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
10 *          R��mi Denis-Courmont
11 */
12
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <asm/unaligned.h>
17#include <net/sock.h>
18
19#include <linux/if_phonet.h>
20#include <linux/phonet.h>
21#include <net/phonet/phonet.h>
22#include <net/phonet/pn_dev.h>
23
24/* Transport protocol registration */
25static const struct phonet_protocol *proto_tab[PHONET_NPROTO] __read_mostly;
26
27static const struct phonet_protocol *phonet_proto_get(unsigned int protocol)
28{
29	const struct phonet_protocol *pp;
30
31	if (protocol >= PHONET_NPROTO)
32		return NULL;
33
34	rcu_read_lock();
35	pp = rcu_dereference(proto_tab[protocol]);
36	if (pp && !try_module_get(pp->prot->owner))
37		pp = NULL;
38	rcu_read_unlock();
39
40	return pp;
41}
42
43static inline void phonet_proto_put(const struct phonet_protocol *pp)
44{
45	module_put(pp->prot->owner);
46}
47
48/* protocol family functions */
49
50static int pn_socket_create(struct net *net, struct socket *sock, int protocol,
51			    int kern)
52{
53	struct sock *sk;
54	struct pn_sock *pn;
55	const struct phonet_protocol *pnp;
56	int err;
57
58	if (!capable(CAP_SYS_ADMIN))
59		return -EPERM;
60
61	if (protocol == 0) {
62		/* Default protocol selection */
63		switch (sock->type) {
64		case SOCK_DGRAM:
65			protocol = PN_PROTO_PHONET;
66			break;
67		case SOCK_SEQPACKET:
68			protocol = PN_PROTO_PIPE;
69			break;
70		default:
71			return -EPROTONOSUPPORT;
72		}
73	}
74
75	pnp = phonet_proto_get(protocol);
76	if (pnp == NULL &&
77	    request_module("net-pf-%d-proto-%d", PF_PHONET, protocol) == 0)
78		pnp = phonet_proto_get(protocol);
79
80	if (pnp == NULL)
81		return -EPROTONOSUPPORT;
82	if (sock->type != pnp->sock_type) {
83		err = -EPROTONOSUPPORT;
84		goto out;
85	}
86
87	sk = sk_alloc(net, PF_PHONET, GFP_KERNEL, pnp->prot, kern);
88	if (sk == NULL) {
89		err = -ENOMEM;
90		goto out;
91	}
92
93	sock_init_data(sock, sk);
94	sock->state = SS_UNCONNECTED;
95	sock->ops = pnp->ops;
96	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
97	sk->sk_protocol = protocol;
98	pn = pn_sk(sk);
99	pn->sobject = 0;
100	pn->dobject = 0;
101	pn->resource = 0;
102	sk->sk_prot->init(sk);
103	err = 0;
104
105out:
106	phonet_proto_put(pnp);
107	return err;
108}
109
110static const struct net_proto_family phonet_proto_family = {
111	.family = PF_PHONET,
112	.create = pn_socket_create,
113	.owner = THIS_MODULE,
114};
115
116/* Phonet device header operations */
117static int pn_header_create(struct sk_buff *skb, struct net_device *dev,
118				unsigned short type, const void *daddr,
119				const void *saddr, unsigned int len)
120{
121	u8 *media = skb_push(skb, 1);
122
123	if (type != ETH_P_PHONET)
124		return -1;
125
126	if (!saddr)
127		saddr = dev->dev_addr;
128	*media = *(const u8 *)saddr;
129	return 1;
130}
131
132static int pn_header_parse(const struct sk_buff *skb, unsigned char *haddr)
133{
134	const u8 *media = skb_mac_header(skb);
135	*haddr = *media;
136	return 1;
137}
138
139const struct header_ops phonet_header_ops = {
140	.create = pn_header_create,
141	.parse = pn_header_parse,
142};
143EXPORT_SYMBOL(phonet_header_ops);
144
145/*
146 * Prepends an ISI header and sends a datagram.
147 */
148static int pn_send(struct sk_buff *skb, struct net_device *dev,
149			u16 dst, u16 src, u8 res)
150{
151	struct phonethdr *ph;
152	int err;
153
154	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
155	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
156		err = -EMSGSIZE;
157		goto drop;
158	}
159
160	/* Broadcast sending is not implemented */
161	if (pn_addr(dst) == PNADDR_BROADCAST) {
162		err = -EOPNOTSUPP;
163		goto drop;
164	}
165
166	skb_reset_transport_header(skb);
167	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
168	skb_push(skb, sizeof(struct phonethdr));
169	skb_reset_network_header(skb);
170	ph = pn_hdr(skb);
171	ph->pn_rdev = pn_dev(dst);
172	ph->pn_sdev = pn_dev(src);
173	ph->pn_res = res;
174	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
175	ph->pn_robj = pn_obj(dst);
176	ph->pn_sobj = pn_obj(src);
177
178	skb->protocol = htons(ETH_P_PHONET);
179	skb->priority = 0;
180	skb->dev = dev;
181
182	if (skb->pkt_type == PACKET_LOOPBACK) {
183		skb_reset_mac_header(skb);
184		skb_orphan(skb);
185		err = netif_rx(skb) ? -ENOBUFS : 0;
186	} else {
187		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
188					NULL, NULL, skb->len);
189		if (err < 0) {
190			err = -EHOSTUNREACH;
191			goto drop;
192		}
193		err = dev_queue_xmit(skb);
194		if (unlikely(err > 0))
195			err = net_xmit_errno(err);
196	}
197
198	return err;
199drop:
200	kfree_skb(skb);
201	return err;
202}
203
204static int pn_raw_send(const void *data, int len, struct net_device *dev,
205			u16 dst, u16 src, u8 res)
206{
207	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
208	if (skb == NULL)
209		return -ENOMEM;
210
211	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
212		skb->pkt_type = PACKET_LOOPBACK;
213
214	skb_reserve(skb, MAX_PHONET_HEADER);
215	__skb_put(skb, len);
216	skb_copy_to_linear_data(skb, data, len);
217	return pn_send(skb, dev, dst, src, res);
218}
219
220/*
221 * Create a Phonet header for the skb and send it out. Returns
222 * non-zero error code if failed. The skb is freed then.
223 */
224int pn_skb_send(struct sock *sk, struct sk_buff *skb,
225		const struct sockaddr_pn *target)
226{
227	struct net *net = sock_net(sk);
228	struct net_device *dev;
229	struct pn_sock *pn = pn_sk(sk);
230	int err;
231	u16 src, dst;
232	u8 daddr, saddr, res;
233
234	src = pn->sobject;
235	if (target != NULL) {
236		dst = pn_sockaddr_get_object(target);
237		res = pn_sockaddr_get_resource(target);
238	} else {
239		dst = pn->dobject;
240		res = pn->resource;
241	}
242	daddr = pn_addr(dst);
243
244	err = -EHOSTUNREACH;
245	if (sk->sk_bound_dev_if)
246		dev = dev_get_by_index(net, sk->sk_bound_dev_if);
247	else if (phonet_address_lookup(net, daddr) == 0) {
248		dev = phonet_device_get(net);
249		skb->pkt_type = PACKET_LOOPBACK;
250	} else if (dst == 0) {
251		/* Resource routing (small race until phonet_rcv()) */
252		struct sock *sk = pn_find_sock_by_res(net, res);
253		if (sk)	{
254			sock_put(sk);
255			dev = phonet_device_get(net);
256			skb->pkt_type = PACKET_LOOPBACK;
257		} else
258			dev = phonet_route_output(net, daddr);
259	} else
260		dev = phonet_route_output(net, daddr);
261
262	if (!dev || !(dev->flags & IFF_UP))
263		goto drop;
264
265	saddr = phonet_address_get(dev, daddr);
266	if (saddr == PN_NO_ADDR)
267		goto drop;
268
269	if (!pn_addr(src))
270		src = pn_object(saddr, pn_obj(src));
271
272	err = pn_send(skb, dev, dst, src, res);
273	dev_put(dev);
274	return err;
275
276drop:
277	kfree_skb(skb);
278	dev_put(dev);
279	return err;
280}
281EXPORT_SYMBOL(pn_skb_send);
282
283/* Do not send an error message in response to an error message */
284static inline int can_respond(struct sk_buff *skb)
285{
286	const struct phonethdr *ph;
287	const struct phonetmsg *pm;
288	u8 submsg_id;
289
290	if (!pskb_may_pull(skb, 3))
291		return 0;
292
293	ph = pn_hdr(skb);
294	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
295		return 0;
296	if (ph->pn_res == PN_COMMGR) /* indications */
297		return 0;
298
299	ph = pn_hdr(skb); /* re-acquires the pointer */
300	pm = pn_msg(skb);
301	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
302		return 1;
303	submsg_id = (ph->pn_res == PN_PREFIX)
304		? pm->pn_e_submsg_id : pm->pn_submsg_id;
305	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
306		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
307		return 1;
308	return 0;
309}
310
311static int send_obj_unreachable(struct sk_buff *rskb)
312{
313	const struct phonethdr *oph = pn_hdr(rskb);
314	const struct phonetmsg *opm = pn_msg(rskb);
315	struct phonetmsg resp;
316
317	memset(&resp, 0, sizeof(resp));
318	resp.pn_trans_id = opm->pn_trans_id;
319	resp.pn_msg_id = PN_COMMON_MESSAGE;
320	if (oph->pn_res == PN_PREFIX) {
321		resp.pn_e_res_id = opm->pn_e_res_id;
322		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
323		resp.pn_e_orig_msg_id = opm->pn_msg_id;
324		resp.pn_e_status = 0;
325	} else {
326		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
327		resp.pn_orig_msg_id = opm->pn_msg_id;
328		resp.pn_status = 0;
329	}
330	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
331				pn_object(oph->pn_sdev, oph->pn_sobj),
332				pn_object(oph->pn_rdev, oph->pn_robj),
333				oph->pn_res);
334}
335
336static int send_reset_indications(struct sk_buff *rskb)
337{
338	struct phonethdr *oph = pn_hdr(rskb);
339	static const u8 data[4] = {
340		0x00 /* trans ID */, 0x10 /* subscribe msg */,
341		0x00 /* subscription count */, 0x00 /* dummy */
342	};
343
344	return pn_raw_send(data, sizeof(data), rskb->dev,
345				pn_object(oph->pn_sdev, 0x00),
346				pn_object(oph->pn_rdev, oph->pn_robj),
347				PN_COMMGR);
348}
349
350
351/* packet type functions */
352
353/*
354 * Stuff received packets to associated sockets.
355 * On error, returns non-zero and releases the skb.
356 */
357static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
358			struct packet_type *pkttype,
359			struct net_device *orig_dev)
360{
361	struct net *net = dev_net(dev);
362	struct phonethdr *ph;
363	struct sockaddr_pn sa;
364	u16 len;
365
366	skb = skb_share_check(skb, GFP_ATOMIC);
367	if (!skb)
368		return NET_RX_DROP;
369
370	/* check we have at least a full Phonet header */
371	if (!pskb_pull(skb, sizeof(struct phonethdr)))
372		goto out;
373
374	/* check that the advertised length is correct */
375	ph = pn_hdr(skb);
376	len = get_unaligned_be16(&ph->pn_length);
377	if (len < 2)
378		goto out;
379	len -= 2;
380	if ((len > skb->len) || pskb_trim(skb, len))
381		goto out;
382	skb_reset_transport_header(skb);
383
384	pn_skb_get_dst_sockaddr(skb, &sa);
385
386	/* check if this is broadcasted */
387	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
388		pn_deliver_sock_broadcast(net, skb);
389		goto out;
390	}
391
392	/* resource routing */
393	if (pn_sockaddr_get_object(&sa) == 0) {
394		struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
395		if (sk)
396			return sk_receive_skb(sk, skb, 0);
397	}
398
399	/* check if we are the destination */
400	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
401		/* Phonet packet input */
402		struct sock *sk = pn_find_sock_by_sa(net, &sa);
403
404		if (sk)
405			return sk_receive_skb(sk, skb, 0);
406
407		if (can_respond(skb)) {
408			send_obj_unreachable(skb);
409			send_reset_indications(skb);
410		}
411	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
412		goto out; /* Race between address deletion and loopback */
413	else {
414		/* Phonet packet routing */
415		struct net_device *out_dev;
416
417		out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
418		if (!out_dev) {
419			net_dbg_ratelimited("No Phonet route to %02X\n",
420					    pn_sockaddr_get_addr(&sa));
421			goto out;
422		}
423
424		__skb_push(skb, sizeof(struct phonethdr));
425		skb->dev = out_dev;
426		if (out_dev == dev) {
427			net_dbg_ratelimited("Phonet loop to %02X on %s\n",
428					    pn_sockaddr_get_addr(&sa),
429					    dev->name);
430			goto out_dev;
431		}
432		/* Some drivers (e.g. TUN) do not allocate HW header space */
433		if (skb_cow_head(skb, out_dev->hard_header_len))
434			goto out_dev;
435
436		if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
437					skb->len) < 0)
438			goto out_dev;
439		dev_queue_xmit(skb);
440		dev_put(out_dev);
441		return NET_RX_SUCCESS;
442out_dev:
443		dev_put(out_dev);
444	}
445
446out:
447	kfree_skb(skb);
448	return NET_RX_DROP;
449}
450
451static struct packet_type phonet_packet_type __read_mostly = {
452	.type = cpu_to_be16(ETH_P_PHONET),
453	.func = phonet_rcv,
454};
455
456static DEFINE_MUTEX(proto_tab_lock);
457
458int __init_or_module phonet_proto_register(unsigned int protocol,
459				const struct phonet_protocol *pp)
460{
461	int err = 0;
462
463	if (protocol >= PHONET_NPROTO)
464		return -EINVAL;
465
466	err = proto_register(pp->prot, 1);
467	if (err)
468		return err;
469
470	mutex_lock(&proto_tab_lock);
471	if (proto_tab[protocol])
472		err = -EBUSY;
473	else
474		rcu_assign_pointer(proto_tab[protocol], pp);
475	mutex_unlock(&proto_tab_lock);
476
477	return err;
478}
479EXPORT_SYMBOL(phonet_proto_register);
480
481void phonet_proto_unregister(unsigned int protocol,
482			const struct phonet_protocol *pp)
483{
484	mutex_lock(&proto_tab_lock);
485	BUG_ON(proto_tab[protocol] != pp);
486	RCU_INIT_POINTER(proto_tab[protocol], NULL);
487	mutex_unlock(&proto_tab_lock);
488	synchronize_rcu();
489	proto_unregister(pp->prot);
490}
491EXPORT_SYMBOL(phonet_proto_unregister);
492
493/* Module registration */
494static int __init phonet_init(void)
495{
496	int err;
497
498	err = phonet_device_init();
499	if (err)
500		return err;
501
502	pn_sock_init();
503	err = sock_register(&phonet_proto_family);
504	if (err) {
505		printk(KERN_ALERT
506			"phonet protocol family initialization failed\n");
507		goto err_sock;
508	}
509
510	dev_add_pack(&phonet_packet_type);
511	phonet_sysctl_init();
512
513	err = isi_register();
514	if (err)
515		goto err;
516	return 0;
517
518err:
519	phonet_sysctl_exit();
520	sock_unregister(PF_PHONET);
521	dev_remove_pack(&phonet_packet_type);
522err_sock:
523	phonet_device_exit();
524	return err;
525}
526
527static void __exit phonet_exit(void)
528{
529	isi_unregister();
530	phonet_sysctl_exit();
531	sock_unregister(PF_PHONET);
532	dev_remove_pack(&phonet_packet_type);
533	phonet_device_exit();
534}
535
536module_init(phonet_init);
537module_exit(phonet_exit);
538MODULE_DESCRIPTION("Phonet protocol stack for Linux");
539MODULE_LICENSE("GPL");
540MODULE_ALIAS_NETPROTO(PF_PHONET);
541