signaling.c

  1// SPDX-License-Identifier: GPL-2.0
  2/* net/atm/signaling.c - ATM signaling */
  3
  4/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
  5
  6#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
  7
  8#include <linux/errno.h>	/* error codes */
  9#include <linux/kernel.h>	/* printk */
 10#include <linux/skbuff.h>
 11#include <linux/wait.h>
 12#include <linux/sched.h>	/* jiffies and HZ */
 13#include <linux/atm.h>		/* ATM stuff */
 14#include <linux/atmsap.h>
 15#include <linux/atmsvc.h>
 16#include <linux/atmdev.h>
 17#include <linux/bitops.h>
 18#include <linux/slab.h>
 19
 20#include "resources.h"
 21#include "signaling.h"
 22
 23struct atm_vcc *sigd = NULL;
 24
 25/*
 26 * find_get_vcc - validate and get a reference to a vcc pointer
 27 * @vcc: the vcc pointer to validate
 28 *
 29 * This function validates that @vcc points to a registered VCC in vcc_hash.
 30 * If found, it increments the socket reference count and returns the vcc.
 31 * The caller must call sock_put(sk_atm(vcc)) when done.
 32 *
 33 * Returns the vcc pointer if valid, NULL otherwise.
 34 */
 35static struct atm_vcc *find_get_vcc(struct atm_vcc *vcc)
 36{
 37	int i;
 38
 39	read_lock(&vcc_sklist_lock);
 40	for (i = 0; i < VCC_HTABLE_SIZE; i++) {
 41		struct sock *s;
 42
 43		sk_for_each(s, &vcc_hash[i]) {
 44			if (atm_sk(s) == vcc) {
 45				sock_hold(s);
 46				read_unlock(&vcc_sklist_lock);
 47				return vcc;
 48			}
 49		}
 50	}
 51	read_unlock(&vcc_sklist_lock);
 52	return NULL;
 53}
 54
 55static void sigd_put_skb(struct sk_buff *skb)
 56{
 57	if (!sigd) {
 58		pr_debug("atmsvc: no signaling daemon\n");
 59		kfree_skb(skb);
 60		return;
 61	}
 62	atm_force_charge(sigd, skb->truesize);
 63	skb_queue_tail(&sk_atm(sigd)->sk_receive_queue, skb);
 64	sk_atm(sigd)->sk_data_ready(sk_atm(sigd));
 65}
 66
 67static void modify_qos(struct atm_vcc *vcc, struct atmsvc_msg *msg)
 68{
 69	struct sk_buff *skb;
 70
 71	if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
 72	    !test_bit(ATM_VF_READY, &vcc->flags))
 73		return;
 74	msg->type = as_error;
 75	if (!vcc->dev->ops->change_qos)
 76		msg->reply = -EOPNOTSUPP;
 77	else {
 78		/* should lock VCC */
 79		msg->reply = vcc->dev->ops->change_qos(vcc, &msg->qos,
 80						       msg->reply);
 81		if (!msg->reply)
 82			msg->type = as_okay;
 83	}
 84	/*
 85	 * Should probably just turn around the old skb. But then, the buffer
 86	 * space accounting needs to follow the change too. Maybe later.
 87	 */
 88	while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
 89		schedule();
 90	*(struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg)) = *msg;
 91	sigd_put_skb(skb);
 92}
 93
 94static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
 95{
 96	struct atmsvc_msg *msg;
 97	struct atm_vcc *session_vcc;
 98	struct sock *sk;
 99
100	msg = (struct atmsvc_msg *) skb->data;
101	WARN_ON(refcount_sub_and_test(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc));
102
103	vcc = find_get_vcc(*(struct atm_vcc **)&msg->vcc);
104	if (!vcc) {
105		pr_debug("invalid vcc pointer in msg\n");
106		dev_kfree_skb(skb);
107		return -EINVAL;
108	}
109
110	pr_debug("%d (0x%lx)\n", (int)msg->type, (unsigned long)vcc);
111	sk = sk_atm(vcc);
112
113	switch (msg->type) {
114	case as_okay:
115		sk->sk_err = -msg->reply;
116		clear_bit(ATM_VF_WAITING, &vcc->flags);
117		if (!*vcc->local.sas_addr.prv && !*vcc->local.sas_addr.pub) {
118			vcc->local.sas_family = AF_ATMSVC;
119			memcpy(vcc->local.sas_addr.prv,
120			       msg->local.sas_addr.prv, ATM_ESA_LEN);
121			memcpy(vcc->local.sas_addr.pub,
122			       msg->local.sas_addr.pub, ATM_E164_LEN + 1);
123		}
124		session_vcc = vcc->session ? vcc->session : vcc;
125		if (session_vcc->vpi || session_vcc->vci)
126			break;
127		session_vcc->itf = msg->pvc.sap_addr.itf;
128		session_vcc->vpi = msg->pvc.sap_addr.vpi;
129		session_vcc->vci = msg->pvc.sap_addr.vci;
130		if (session_vcc->vpi || session_vcc->vci)
131			session_vcc->qos = msg->qos;
132		break;
133	case as_error:
134		clear_bit(ATM_VF_REGIS, &vcc->flags);
135		clear_bit(ATM_VF_READY, &vcc->flags);
136		sk->sk_err = -msg->reply;
137		clear_bit(ATM_VF_WAITING, &vcc->flags);
138		break;
139	case as_indicate:
140		/* Release the reference from msg->vcc, we'll use msg->listen_vcc instead */
141		sock_put(sk);
142
143		vcc = find_get_vcc(*(struct atm_vcc **)&msg->listen_vcc);
144		if (!vcc) {
145			pr_debug("invalid listen_vcc pointer in msg\n");
146			dev_kfree_skb(skb);
147			return -EINVAL;
148		}
149
150		sk = sk_atm(vcc);
151		pr_debug("as_indicate!!!\n");
152		lock_sock(sk);
153		if (sk_acceptq_is_full(sk)) {
154			sigd_enq(NULL, as_reject, vcc, NULL, NULL);
155			dev_kfree_skb(skb);
156			goto as_indicate_complete;
157		}
158		sk_acceptq_added(sk);
159		skb_queue_tail(&sk->sk_receive_queue, skb);
160		pr_debug("waking sk_sleep(sk) 0x%p\n", sk_sleep(sk));
161		sk->sk_state_change(sk);
162as_indicate_complete:
163		release_sock(sk);
164		/* Paired with find_get_vcc(msg->listen_vcc) above */
165		sock_put(sk);
166		return 0;
167	case as_close:
168		set_bit(ATM_VF_RELEASED, &vcc->flags);
169		vcc_release_async(vcc, msg->reply);
170		goto out;
171	case as_modify:
172		modify_qos(vcc, msg);
173		break;
174	case as_addparty:
175	case as_dropparty:
176		WRITE_ONCE(sk->sk_err_soft, -msg->reply);
177					/* < 0 failure, otherwise ep_ref */
178		clear_bit(ATM_VF_WAITING, &vcc->flags);
179		break;
180	default:
181		pr_alert("bad message type %d\n", (int)msg->type);
182		/* Paired with find_get_vcc(msg->vcc) above */
183		sock_put(sk);
184		return -EINVAL;
185	}
186	sk->sk_state_change(sk);
187out:
188	dev_kfree_skb(skb);
189	/* Paired with find_get_vcc(msg->vcc) above */
190	sock_put(sk);
191	return 0;
192}
193
194void sigd_enq2(struct atm_vcc *vcc, enum atmsvc_msg_type type,
195	       struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
196	       const struct sockaddr_atmsvc *svc, const struct atm_qos *qos,
197	       int reply)
198{
199	struct sk_buff *skb;
200	struct atmsvc_msg *msg;
201	static unsigned int session = 0;
202
203	pr_debug("%d (0x%p)\n", (int)type, vcc);
204	while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
205		schedule();
206	msg = skb_put_zero(skb, sizeof(struct atmsvc_msg));
207	msg->type = type;
208	*(struct atm_vcc **) &msg->vcc = vcc;
209	*(struct atm_vcc **) &msg->listen_vcc = listen_vcc;
210	msg->reply = reply;
211	if (qos)
212		msg->qos = *qos;
213	if (vcc)
214		msg->sap = vcc->sap;
215	if (svc)
216		msg->svc = *svc;
217	if (vcc)
218		msg->local = vcc->local;
219	if (pvc)
220		msg->pvc = *pvc;
221	if (vcc) {
222		if (type == as_connect && test_bit(ATM_VF_SESSION, &vcc->flags))
223			msg->session = ++session;
224			/* every new pmp connect gets the next session number */
225	}
226	sigd_put_skb(skb);
227	if (vcc)
228		set_bit(ATM_VF_REGIS, &vcc->flags);
229}
230
231void sigd_enq(struct atm_vcc *vcc, enum atmsvc_msg_type type,
232	      struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
233	      const struct sockaddr_atmsvc *svc)
234{
235	sigd_enq2(vcc, type, listen_vcc, pvc, svc, vcc ? &vcc->qos : NULL, 0);
236	/* other ISP applications may use "reply" */
237}
238
239static void purge_vcc(struct atm_vcc *vcc)
240{
241	if (sk_atm(vcc)->sk_family == PF_ATMSVC &&
242	    !test_bit(ATM_VF_META, &vcc->flags)) {
243		set_bit(ATM_VF_RELEASED, &vcc->flags);
244		clear_bit(ATM_VF_REGIS, &vcc->flags);
245		vcc_release_async(vcc, -EUNATCH);
246	}
247}
248
249static void sigd_close(struct atm_vcc *vcc)
250{
251	struct sock *s;
252	int i;
253
254	pr_debug("\n");
255	sigd = NULL;
256	if (skb_peek(&sk_atm(vcc)->sk_receive_queue))
257		pr_err("closing with requests pending\n");
258	skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);
259
260	read_lock(&vcc_sklist_lock);
261	for (i = 0; i < VCC_HTABLE_SIZE; ++i) {
262		struct hlist_head *head = &vcc_hash[i];
263
264		sk_for_each(s, head) {
265			vcc = atm_sk(s);
266
267			purge_vcc(vcc);
268		}
269	}
270	read_unlock(&vcc_sklist_lock);
271}
272
273static const struct atmdev_ops sigd_dev_ops = {
274	.close = sigd_close,
275	.send =	sigd_send
276};
277
278static struct atm_dev sigd_dev = {
279	.ops =		&sigd_dev_ops,
280	.type =		"sig",
281	.number =	999,
282	.lock =		__SPIN_LOCK_UNLOCKED(sigd_dev.lock)
283};
284
285int sigd_attach(struct atm_vcc *vcc)
286{
287	if (sigd)
288		return -EADDRINUSE;
289	pr_debug("\n");
290	sigd = vcc;
291	vcc->dev = &sigd_dev;
292	vcc_insert_socket(sk_atm(vcc));
293	set_bit(ATM_VF_META, &vcc->flags);
294	set_bit(ATM_VF_READY, &vcc->flags);
295	return 0;
296}