[linux-2.6-block.git] / drivers / connector / connector.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	connector.c
 *
 * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 */

#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <linux/moduleparam.h>
#include <linux/connector.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>

#include <net/sock.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);

static struct cn_dev cdev;

static int cn_already_initialized;

/*
 * Sends mult (multiple) cn_msg at a time.
 *
 * msg->seq and msg->ack are used to determine message genealogy.
 * When someone sends message it puts there locally unique sequence
 * and random acknowledge numbers.  Sequence number may be copied into
 * nlmsghdr->nlmsg_seq too.
 *
 * Sequence number is incremented with each message to be sent.
 *
 * If we expect a reply to our message then the sequence number in
 * received message MUST be the same as in original message, and
 * acknowledge number MUST be the same + 1.
 *
 * If we receive a message and its sequence number is not equal to the
 * one we are expecting then it is a new message.
 *
 * If we receive a message and its sequence number is the same as one
 * we are expecting but it's acknowledgement number is not equal to
 * the acknowledgement number in the original message + 1, then it is
 * a new message.
 *
 * If msg->len != len, then additional cn_msg messages are expected following
 * the first msg.
 *
 * The message is sent to, the portid if given, the group if given, both if
 * both, or if both are zero then the group is looked up and sent there.
 */
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
	gfp_t gfp_mask)
{
	struct cn_callback_entry *__cbq;
	unsigned int size;
	struct sk_buff *skb;
	struct nlmsghdr *nlh;
	struct cn_msg *data;
	struct cn_dev *dev = &cdev;
	u32 group = 0;
	int found = 0;

	if (portid || __group) {
		group = __group;
	} else {
		spin_lock_bh(&dev->cbdev->queue_lock);
		list_for_each_entry(__cbq, &dev->cbdev->queue_list,
				    callback_entry) {
			if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
				found = 1;
				group = __cbq->group;
				break;
			}
		}
		spin_unlock_bh(&dev->cbdev->queue_lock);

		if (!found)
			return -ENODEV;
	}

	if (!portid && !netlink_has_listeners(dev->nls, group))
		return -ESRCH;

	size = sizeof(*msg) + len;

	skb = nlmsg_new(size, gfp_mask);
	if (!skb)
		return -ENOMEM;

	nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
	if (!nlh) {
		kfree_skb(skb);
		return -EMSGSIZE;
	}

	data = nlmsg_data(nlh);

	memcpy(data, msg, size);

	NETLINK_CB(skb).dst_group = group;

	if (group)
		return netlink_broadcast(dev->nls, skb, portid, group,
					 gfp_mask);
	return netlink_unicast(dev->nls, skb, portid,
			!gfpflags_allow_blocking(gfp_mask));
}
EXPORT_SYMBOL_GPL(cn_netlink_send_mult);

/* same as cn_netlink_send_mult except msg->len is used for len */
int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
	gfp_t gfp_mask)
{
	return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
}
EXPORT_SYMBOL_GPL(cn_netlink_send);

/*
 * Callback helper - queues work and setup destructor for given data.
 */
static int cn_call_callback(struct sk_buff *skb)
{
	struct nlmsghdr *nlh;
	struct cn_callback_entry *i, *cbq = NULL;
	struct cn_dev *dev = &cdev;
	struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
	int err = -ENODEV;

	/* verify msg->len is within skb */
	nlh = nlmsg_hdr(skb);
	if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len)
		return -EINVAL;

	spin_lock_bh(&dev->cbdev->queue_lock);
	list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
		if (cn_cb_equal(&i->id.id, &msg->id)) {
			refcount_inc(&i->refcnt);
			cbq = i;
			break;
		}
	}
	spin_unlock_bh(&dev->cbdev->queue_lock);

	if (cbq != NULL) {
		cbq->callback(msg, nsp);
		kfree_skb(skb);
		cn_queue_release_callback(cbq);
		err = 0;
	}

	return err;
}

/*
 * Main netlink receiving function.
 *
 * It checks skb, netlink header and msg sizes, and calls callback helper.
 */
static void cn_rx_skb(struct sk_buff *skb)
{
	struct nlmsghdr *nlh;
	int len, err;

	if (skb->len >= NLMSG_HDRLEN) {
		nlh = nlmsg_hdr(skb);
		len = nlmsg_len(nlh);

		if (len < (int)sizeof(struct cn_msg) ||
		    skb->len < nlh->nlmsg_len ||
		    len > CONNECTOR_MAX_MSG_SIZE)
			return;

		err = cn_call_callback(skb_get(skb));
		if (err < 0)
			kfree_skb(skb);
	}
}

/*
 * Callback add routing - adds callback with given ID and name.
 * If there is registered callback with the same ID it will not be added.
 *
 * May sleep.
 */
int cn_add_callback(struct cb_id *id, const char *name,
		    void (*callback)(struct cn_msg *,
				     struct netlink_skb_parms *))
{
	int err;
	struct cn_dev *dev = &cdev;

	if (!cn_already_initialized)
		return -EAGAIN;

	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
	if (err)
		return err;

	return 0;
}
EXPORT_SYMBOL_GPL(cn_add_callback);

/*
 * Callback remove routing - removes callback
 * with given ID.
 * If there is no registered callback with given
 * ID nothing happens.
 *
 * May sleep while waiting for reference counter to become zero.
 */
void cn_del_callback(struct cb_id *id)
{
	struct cn_dev *dev = &cdev;

	cn_queue_del_callback(dev->cbdev, id);
}
EXPORT_SYMBOL_GPL(cn_del_callback);

static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
{
	struct cn_queue_dev *dev = cdev.cbdev;
	struct cn_callback_entry *cbq;

	seq_printf(m, "Name            ID\n");

	spin_lock_bh(&dev->queue_lock);

	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
		seq_printf(m, "%-15s %u:%u\n",
			   cbq->id.name,
			   cbq->id.id.idx,
			   cbq->id.id.val);
	}

	spin_unlock_bh(&dev->queue_lock);

	return 0;
}

static struct cn_dev cdev = {
	.input   = cn_rx_skb,
};

static int cn_init(void)
{
	struct cn_dev *dev = &cdev;
	struct netlink_kernel_cfg cfg = {
		.groups	= CN_NETLINK_USERS + 0xf,
		.input	= dev->input,
	};

	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
	if (!dev->nls)
		return -EIO;

	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
	if (!dev->cbdev) {
		netlink_kernel_release(dev->nls);
		return -EINVAL;
	}

	cn_already_initialized = 1;

	proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);

	return 0;
}

static void cn_fini(void)
{
	struct cn_dev *dev = &cdev;

	cn_already_initialized = 0;

	remove_proc_entry("connector", init_net.proc_net);

	cn_queue_free_dev(dev->cbdev);
	netlink_kernel_release(dev->nls);
}

subsys_initcall(cn_init);
module_exit(cn_fini);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0-or-later
	2	/*
	3	* connector.c
	4	*
	5	* 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
	6	* All rights reserved.
	7	*/
	8
	9	#include <linux/compiler.h>
	10	#include <linux/kernel.h>
	11	#include <linux/module.h>
	12	#include <linux/list.h>
	13	#include <linux/skbuff.h>
	14	#include <net/netlink.h>
	15	#include <linux/moduleparam.h>
	16	#include <linux/connector.h>
	17	#include <linux/slab.h>
	18	#include <linux/mutex.h>
	19	#include <linux/proc_fs.h>
	20	#include <linux/spinlock.h>
	21
	22	#include <net/sock.h>
	23
	24	MODULE_LICENSE("GPL");
	25	MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
	26	MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
	27	MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
	28
	29	static struct cn_dev cdev;
	30
	31	static int cn_already_initialized;
	32
	33	/*
	34	* Sends mult (multiple) cn_msg at a time.
	35	*
	36	* msg->seq and msg->ack are used to determine message genealogy.
	37	* When someone sends message it puts there locally unique sequence
	38	* and random acknowledge numbers. Sequence number may be copied into
	39	* nlmsghdr->nlmsg_seq too.
	40	*
	41	* Sequence number is incremented with each message to be sent.
	42	*
	43	* If we expect a reply to our message then the sequence number in
	44	* received message MUST be the same as in original message, and
	45	* acknowledge number MUST be the same + 1.
	46	*
	47	* If we receive a message and its sequence number is not equal to the
	48	* one we are expecting then it is a new message.
	49	*
	50	* If we receive a message and its sequence number is the same as one
	51	* we are expecting but it's acknowledgement number is not equal to
	52	* the acknowledgement number in the original message + 1, then it is
	53	* a new message.
	54	*
	55	* If msg->len != len, then additional cn_msg messages are expected following
	56	* the first msg.
	57	*
	58	* The message is sent to, the portid if given, the group if given, both if
	59	* both, or if both are zero then the group is looked up and sent there.
	60	*/
	61	int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group,
	62	gfp_t gfp_mask)
	63	{
	64	struct cn_callback_entry *__cbq;
	65	unsigned int size;
	66	struct sk_buff *skb;
	67	struct nlmsghdr *nlh;
	68	struct cn_msg *data;
	69	struct cn_dev *dev = &cdev;
	70	u32 group = 0;
	71	int found = 0;
	72
	73	if (portid \|\| __group) {
	74	group = __group;
	75	} else {
	76	spin_lock_bh(&dev->cbdev->queue_lock);
	77	list_for_each_entry(__cbq, &dev->cbdev->queue_list,
	78	callback_entry) {
	79	if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
	80	found = 1;
	81	group = __cbq->group;
	82	break;
	83	}
	84	}
	85	spin_unlock_bh(&dev->cbdev->queue_lock);
	86
	87	if (!found)
	88	return -ENODEV;
	89	}
	90
	91	if (!portid && !netlink_has_listeners(dev->nls, group))
	92	return -ESRCH;
	93
	94	size = sizeof(*msg) + len;
	95
	96	skb = nlmsg_new(size, gfp_mask);
	97	if (!skb)
	98	return -ENOMEM;
	99
	100	nlh = nlmsg_put(skb, 0, msg->seq, NLMSG_DONE, size, 0);
	101	if (!nlh) {
	102	kfree_skb(skb);
	103	return -EMSGSIZE;
	104	}
	105
	106	data = nlmsg_data(nlh);
	107
	108	memcpy(data, msg, size);
	109
	110	NETLINK_CB(skb).dst_group = group;
	111
	112	if (group)
	113	return netlink_broadcast(dev->nls, skb, portid, group,
	114	gfp_mask);
	115	return netlink_unicast(dev->nls, skb, portid,
	116	!gfpflags_allow_blocking(gfp_mask));
	117	}
	118	EXPORT_SYMBOL_GPL(cn_netlink_send_mult);
	119
	120	/* same as cn_netlink_send_mult except msg->len is used for len */
	121	int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group,
	122	gfp_t gfp_mask)
	123	{
	124	return cn_netlink_send_mult(msg, msg->len, portid, __group, gfp_mask);
	125	}
	126	EXPORT_SYMBOL_GPL(cn_netlink_send);
	127
	128	/*
	129	* Callback helper - queues work and setup destructor for given data.
	130	*/
	131	static int cn_call_callback(struct sk_buff *skb)
	132	{
	133	struct nlmsghdr *nlh;
	134	struct cn_callback_entry i, cbq = NULL;
	135	struct cn_dev *dev = &cdev;
	136	struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
	137	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
	138	int err = -ENODEV;
	139
	140	/* verify msg->len is within skb */
	141	nlh = nlmsg_hdr(skb);
	142	if (nlh->nlmsg_len < NLMSG_HDRLEN + sizeof(struct cn_msg) + msg->len)
	143	return -EINVAL;
	144
	145	spin_lock_bh(&dev->cbdev->queue_lock);
	146	list_for_each_entry(i, &dev->cbdev->queue_list, callback_entry) {
	147	if (cn_cb_equal(&i->id.id, &msg->id)) {
	148	refcount_inc(&i->refcnt);
	149	cbq = i;
	150	break;
	151	}
	152	}
	153	spin_unlock_bh(&dev->cbdev->queue_lock);
	154
	155	if (cbq != NULL) {
	156	cbq->callback(msg, nsp);
	157	kfree_skb(skb);
	158	cn_queue_release_callback(cbq);
	159	err = 0;
	160	}
	161
	162	return err;
	163	}
	164
	165	/*
	166	* Main netlink receiving function.
	167	*
	168	* It checks skb, netlink header and msg sizes, and calls callback helper.
	169	*/
	170	static void cn_rx_skb(struct sk_buff *skb)
	171	{
	172	struct nlmsghdr *nlh;
	173	int len, err;
	174
	175	if (skb->len >= NLMSG_HDRLEN) {
	176	nlh = nlmsg_hdr(skb);
	177	len = nlmsg_len(nlh);
	178
	179	if (len < (int)sizeof(struct cn_msg) \|\|
	180	skb->len < nlh->nlmsg_len \|\|
	181	len > CONNECTOR_MAX_MSG_SIZE)
	182	return;
	183
	184	err = cn_call_callback(skb_get(skb));
	185	if (err < 0)
	186	kfree_skb(skb);
	187	}
	188	}
	189
	190	/*
	191	* Callback add routing - adds callback with given ID and name.
	192	* If there is registered callback with the same ID it will not be added.
	193	*
	194	* May sleep.
	195	*/
	196	int cn_add_callback(struct cb_id id, const char name,
	197	void (callback)(struct cn_msg ,
	198	struct netlink_skb_parms *))
	199	{
	200	int err;
	201	struct cn_dev *dev = &cdev;
	202
	203	if (!cn_already_initialized)
	204	return -EAGAIN;
	205
	206	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
	207	if (err)
	208	return err;
	209
	210	return 0;
	211	}
	212	EXPORT_SYMBOL_GPL(cn_add_callback);
	213
	214	/*
	215	* Callback remove routing - removes callback
	216	* with given ID.
	217	* If there is no registered callback with given
	218	* ID nothing happens.
	219	*
	220	* May sleep while waiting for reference counter to become zero.
	221	*/
	222	void cn_del_callback(struct cb_id *id)
	223	{
	224	struct cn_dev *dev = &cdev;
	225
	226	cn_queue_del_callback(dev->cbdev, id);
	227	}
	228	EXPORT_SYMBOL_GPL(cn_del_callback);
	229
	230	static int __maybe_unused cn_proc_show(struct seq_file m, void v)
	231	{
	232	struct cn_queue_dev *dev = cdev.cbdev;
	233	struct cn_callback_entry *cbq;
	234
	235	seq_printf(m, "Name ID\n");
	236
	237	spin_lock_bh(&dev->queue_lock);
	238
	239	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
	240	seq_printf(m, "%-15s %u:%u\n",
	241	cbq->id.name,
	242	cbq->id.id.idx,
	243	cbq->id.id.val);
	244	}
	245
	246	spin_unlock_bh(&dev->queue_lock);
	247
	248	return 0;
	249	}
	250
	251	static struct cn_dev cdev = {
	252	.input = cn_rx_skb,
	253	};
	254
	255	static int cn_init(void)
	256	{
	257	struct cn_dev *dev = &cdev;
	258	struct netlink_kernel_cfg cfg = {
	259	.groups = CN_NETLINK_USERS + 0xf,
	260	.input = dev->input,
	261	};
	262
	263	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
	264	if (!dev->nls)
	265	return -EIO;
	266
	267	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
	268	if (!dev->cbdev) {
	269	netlink_kernel_release(dev->nls);
	270	return -EINVAL;
	271	}
	272
	273	cn_already_initialized = 1;
	274
	275	proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);
	276
	277	return 0;
	278	}
	279
	280	static void cn_fini(void)
	281	{
	282	struct cn_dev *dev = &cdev;
	283
	284	cn_already_initialized = 0;
	285
	286	remove_proc_entry("connector", init_net.proc_net);
	287
	288	cn_queue_free_dev(dev->cbdev);
	289	netlink_kernel_release(dev->nls);
	290	}
	291
	292	subsys_initcall(cn_init);
	293	module_exit(cn_fini);