af_phonet.c

  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 *          Rémi Denis-Courmont
 11 */
 12
 13#include <linux/kernel.h>
 14#include <linux/module.h>
 15#include <linux/slab.h>
 16#include <linux/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 __rcu *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,
133			   const struct net_device *dev,
134			   unsigned char *haddr)
135{
136	const u8 *media = skb_mac_header(skb);
137
138	*haddr = *media;
139	return 1;
140}
141
142const struct header_ops phonet_header_ops = {
143	.create = pn_header_create,
144	.parse = pn_header_parse,
145};
146EXPORT_SYMBOL(phonet_header_ops);
147
148/*
149 * Prepends an ISI header and sends a datagram.
150 */
151static int pn_send(struct sk_buff *skb, struct net_device *dev,
152			u16 dst, u16 src, u8 res)
153{
154	struct phonethdr *ph;
155	int err;
156
157	if (skb->len + 2 > 0xffff /* Phonet length field limit */ ||
158	    skb->len + sizeof(struct phonethdr) > dev->mtu) {
159		err = -EMSGSIZE;
160		goto drop;
161	}
162
163	/* Broadcast sending is not implemented */
164	if (pn_addr(dst) == PNADDR_BROADCAST) {
165		err = -EOPNOTSUPP;
166		goto drop;
167	}
168
169	skb_reset_transport_header(skb);
170	WARN_ON(skb_headroom(skb) & 1); /* HW assumes word alignment */
171	skb_push(skb, sizeof(struct phonethdr));
172	skb_reset_network_header(skb);
173	ph = pn_hdr(skb);
174	ph->pn_rdev = pn_dev(dst);
175	ph->pn_sdev = pn_dev(src);
176	ph->pn_res = res;
177	ph->pn_length = __cpu_to_be16(skb->len + 2 - sizeof(*ph));
178	ph->pn_robj = pn_obj(dst);
179	ph->pn_sobj = pn_obj(src);
180
181	skb->protocol = htons(ETH_P_PHONET);
182	skb->priority = 0;
183	skb->dev = dev;
184
185	if (skb->pkt_type == PACKET_LOOPBACK) {
186		skb_reset_mac_header(skb);
187		skb_orphan(skb);
188		err = netif_rx(skb) ? -ENOBUFS : 0;
189	} else {
190		err = dev_hard_header(skb, dev, ntohs(skb->protocol),
191					NULL, NULL, skb->len);
192		if (err < 0) {
193			err = -EHOSTUNREACH;
194			goto drop;
195		}
196		err = dev_queue_xmit(skb);
197		if (unlikely(err > 0))
198			err = net_xmit_errno(err);
199	}
200
201	return err;
202drop:
203	kfree_skb(skb);
204	return err;
205}
206
207static int pn_raw_send(const void *data, int len, struct net_device *dev,
208			u16 dst, u16 src, u8 res)
209{
210	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);
211	if (skb == NULL)
212		return -ENOMEM;
213
214	if (phonet_address_lookup(dev_net(dev), pn_addr(dst)) == 0)
215		skb->pkt_type = PACKET_LOOPBACK;
216
217	skb_reserve(skb, MAX_PHONET_HEADER);
218	__skb_put(skb, len);
219	skb_copy_to_linear_data(skb, data, len);
220	return pn_send(skb, dev, dst, src, res);
221}
222
223/*
224 * Create a Phonet header for the skb and send it out. Returns
225 * non-zero error code if failed. The skb is freed then.
226 */
227int pn_skb_send(struct sock *sk, struct sk_buff *skb,
228		const struct sockaddr_pn *target)
229{
230	struct net *net = sock_net(sk);
231	struct net_device *dev;
232	struct pn_sock *pn = pn_sk(sk);
233	int err;
234	u16 src, dst;
235	u8 daddr, saddr, res;
236
237	src = pn->sobject;
238	if (target != NULL) {
239		dst = pn_sockaddr_get_object(target);
240		res = pn_sockaddr_get_resource(target);
241	} else {
242		dst = pn->dobject;
243		res = pn->resource;
244	}
245	daddr = pn_addr(dst);
246
247	err = -EHOSTUNREACH;
248	if (sk->sk_bound_dev_if)
249		dev = dev_get_by_index(net, sk->sk_bound_dev_if);
250	else if (phonet_address_lookup(net, daddr) == 0) {
251		dev = phonet_device_get(net);
252		skb->pkt_type = PACKET_LOOPBACK;
253	} else if (dst == 0) {
254		/* Resource routing (small race until phonet_rcv()) */
255		struct sock *sk = pn_find_sock_by_res(net, res);
256		if (sk)	{
257			sock_put(sk);
258			dev = phonet_device_get(net);
259			skb->pkt_type = PACKET_LOOPBACK;
260		} else
261			dev = phonet_route_output(net, daddr);
262	} else
263		dev = phonet_route_output(net, daddr);
264
265	if (!dev || !(dev->flags & IFF_UP))
266		goto drop;
267
268	saddr = phonet_address_get(dev, daddr);
269	if (saddr == PN_NO_ADDR)
270		goto drop;
271
272	if (!pn_addr(src))
273		src = pn_object(saddr, pn_obj(src));
274
275	err = pn_send(skb, dev, dst, src, res);
276	dev_put(dev);
277	return err;
278
279drop:
280	kfree_skb(skb);
281	dev_put(dev);
282	return err;
283}
284EXPORT_SYMBOL(pn_skb_send);
285
286/* Do not send an error message in response to an error message */
287static inline int can_respond(struct sk_buff *skb)
288{
289	const struct phonethdr *ph;
290	const struct phonetmsg *pm;
291	u8 submsg_id;
292
293	if (!pskb_may_pull(skb, 3))
294		return 0;
295
296	ph = pn_hdr(skb);
297	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))
298		return 0;
299	if (ph->pn_res == PN_COMMGR) /* indications */
300		return 0;
301
302	ph = pn_hdr(skb); /* re-acquires the pointer */
303	pm = pn_msg(skb);
304	if (pm->pn_msg_id != PN_COMMON_MESSAGE)
305		return 1;
306	submsg_id = (ph->pn_res == PN_PREFIX)
307		? pm->pn_e_submsg_id : pm->pn_submsg_id;
308	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&
309		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)
310		return 1;
311	return 0;
312}
313
314static int send_obj_unreachable(struct sk_buff *rskb)
315{
316	const struct phonethdr *oph = pn_hdr(rskb);
317	const struct phonetmsg *opm = pn_msg(rskb);
318	struct phonetmsg resp;
319
320	memset(&resp, 0, sizeof(resp));
321	resp.pn_trans_id = opm->pn_trans_id;
322	resp.pn_msg_id = PN_COMMON_MESSAGE;
323	if (oph->pn_res == PN_PREFIX) {
324		resp.pn_e_res_id = opm->pn_e_res_id;
325		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
326		resp.pn_e_orig_msg_id = opm->pn_msg_id;
327		resp.pn_e_status = 0;
328	} else {
329		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;
330		resp.pn_orig_msg_id = opm->pn_msg_id;
331		resp.pn_status = 0;
332	}
333	return pn_raw_send(&resp, sizeof(resp), rskb->dev,
334				pn_object(oph->pn_sdev, oph->pn_sobj),
335				pn_object(oph->pn_rdev, oph->pn_robj),
336				oph->pn_res);
337}
338
339static int send_reset_indications(struct sk_buff *rskb)
340{
341	struct phonethdr *oph = pn_hdr(rskb);
342	static const u8 data[4] = {
343		0x00 /* trans ID */, 0x10 /* subscribe msg */,
344		0x00 /* subscription count */, 0x00 /* dummy */
345	};
346
347	return pn_raw_send(data, sizeof(data), rskb->dev,
348				pn_object(oph->pn_sdev, 0x00),
349				pn_object(oph->pn_rdev, oph->pn_robj),
350				PN_COMMGR);
351}
352
353
354/* packet type functions */
355
356/*
357 * Stuff received packets to associated sockets.
358 * On error, returns non-zero and releases the skb.
359 */
360static int phonet_rcv(struct sk_buff *skb, struct net_device *dev,
361			struct packet_type *pkttype,
362			struct net_device *orig_dev)
363{
364	struct net *net = dev_net(dev);
365	struct phonethdr *ph;
366	struct sockaddr_pn sa;
367	u16 len;
368
369	skb = skb_share_check(skb, GFP_ATOMIC);
370	if (!skb)
371		return NET_RX_DROP;
372
373	/* check we have at least a full Phonet header */
374	if (!pskb_pull(skb, sizeof(struct phonethdr)))
375		goto out;
376
377	/* check that the advertised length is correct */
378	ph = pn_hdr(skb);
379	len = get_unaligned_be16(&ph->pn_length);
380	if (len < 2)
381		goto out;
382	len -= 2;
383	if ((len > skb->len) || pskb_trim(skb, len))
384		goto out;
385	skb_reset_transport_header(skb);
386
387	pn_skb_get_dst_sockaddr(skb, &sa);
388
389	/* check if this is broadcasted */
390	if (pn_sockaddr_get_addr(&sa) == PNADDR_BROADCAST) {
391		pn_deliver_sock_broadcast(net, skb);
392		goto out;
393	}
394
395	/* resource routing */
396	if (pn_sockaddr_get_object(&sa) == 0) {
397		struct sock *sk = pn_find_sock_by_res(net, sa.spn_resource);
398		if (sk)
399			return sk_receive_skb(sk, skb, 0);
400	}
401
402	/* check if we are the destination */
403	if (phonet_address_lookup(net, pn_sockaddr_get_addr(&sa)) == 0) {
404		/* Phonet packet input */
405		struct sock *sk = pn_find_sock_by_sa(net, &sa);
406
407		if (sk)
408			return sk_receive_skb(sk, skb, 0);
409
410		if (can_respond(skb)) {
411			send_obj_unreachable(skb);
412			send_reset_indications(skb);
413		}
414	} else if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
415		goto out; /* Race between address deletion and loopback */
416	else {
417		/* Phonet packet routing */
418		struct net_device *out_dev;
419
420		out_dev = phonet_route_output(net, pn_sockaddr_get_addr(&sa));
421		if (!out_dev) {
422			net_dbg_ratelimited("No Phonet route to %02X\n",
423					    pn_sockaddr_get_addr(&sa));
424			goto out;
425		}
426
427		__skb_push(skb, sizeof(struct phonethdr));
428		skb->dev = out_dev;
429		if (out_dev == dev) {
430			net_dbg_ratelimited("Phonet loop to %02X on %s\n",
431					    pn_sockaddr_get_addr(&sa),
432					    dev->name);
433			goto out_dev;
434		}
435		/* Some drivers (e.g. TUN) do not allocate HW header space */
436		if (skb_cow_head(skb, out_dev->hard_header_len))
437			goto out_dev;
438
439		if (dev_hard_header(skb, out_dev, ETH_P_PHONET, NULL, NULL,
440					skb->len) < 0)
441			goto out_dev;
442		dev_queue_xmit(skb);
443		dev_put(out_dev);
444		return NET_RX_SUCCESS;
445out_dev:
446		dev_put(out_dev);
447	}
448
449out:
450	kfree_skb(skb);
451	return NET_RX_DROP;
452}
453
454static struct packet_type phonet_packet_type __read_mostly = {
455	.type = cpu_to_be16(ETH_P_PHONET),
456	.func = phonet_rcv,
457};
458
459static DEFINE_MUTEX(proto_tab_lock);
460
461int __init_or_module phonet_proto_register(unsigned int protocol,
462				const struct phonet_protocol *pp)
463{
464	int err = 0;
465
466	if (protocol >= PHONET_NPROTO)
467		return -EINVAL;
468
469	err = proto_register(pp->prot, 1);
470	if (err)
471		return err;
472
473	mutex_lock(&proto_tab_lock);
474	if (proto_tab[protocol])
475		err = -EBUSY;
476	else
477		rcu_assign_pointer(proto_tab[protocol], pp);
478	mutex_unlock(&proto_tab_lock);
479
480	return err;
481}
482EXPORT_SYMBOL(phonet_proto_register);
483
484void phonet_proto_unregister(unsigned int protocol,
485			const struct phonet_protocol *pp)
486{
487	mutex_lock(&proto_tab_lock);
488	BUG_ON(rcu_access_pointer(proto_tab[protocol]) != pp);
489	RCU_INIT_POINTER(proto_tab[protocol], NULL);
490	mutex_unlock(&proto_tab_lock);
491	synchronize_rcu();
492	proto_unregister(pp->prot);
493}
494EXPORT_SYMBOL(phonet_proto_unregister);
495
496/* Module registration */
497static int __init phonet_init(void)
498{
499	int err;
500
501	err = phonet_device_init();
502	if (err)
503		return err;
504
505	pn_sock_init();
506	err = sock_register(&phonet_proto_family);
507	if (err) {
508		printk(KERN_ALERT
509			"phonet protocol family initialization failed\n");
510		goto err_sock;
511	}
512
513	dev_add_pack(&phonet_packet_type);
514	phonet_sysctl_init();
515
516	err = isi_register();
517	if (err)
518		goto err;
519	return 0;
520
521err:
522	phonet_sysctl_exit();
523	sock_unregister(PF_PHONET);
524	dev_remove_pack(&phonet_packet_type);
525err_sock:
526	phonet_device_exit();
527	return err;
528}
529
530static void __exit phonet_exit(void)
531{
532	isi_unregister();
533	phonet_sysctl_exit();
534	sock_unregister(PF_PHONET);
535	dev_remove_pack(&phonet_packet_type);
536	phonet_device_exit();
537}
538
539module_init(phonet_init);
540module_exit(phonet_exit);
541MODULE_DESCRIPTION("Phonet protocol stack for Linux");
542MODULE_LICENSE("GPL");
543MODULE_ALIAS_NETPROTO(PF_PHONET);