summaryrefslogtreecommitdiff
path: root/drivers/scsi/scsi_netlink.c
blob: b37e133de80557e3be96e70f0960d5ef910c1fb5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
/*
 *  scsi_netlink.c  - SCSI Transport Netlink Interface
 *
 *  Copyright (C) 2006   James Smart, Emulex Corporation
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <linux/time.h>
#include <linux/jiffies.h>
#include <linux/security.h>
#include <linux/delay.h>
#include <net/sock.h>
#include <net/netlink.h>

#include <scsi/scsi_netlink.h>
#include "scsi_priv.h"

struct sock *scsi_nl_sock = NULL;
EXPORT_SYMBOL_GPL(scsi_nl_sock);

static DEFINE_SPINLOCK(scsi_nl_lock);
static struct list_head scsi_nl_drivers;

static u32	scsi_nl_state;
#define STATE_EHANDLER_BSY		0x00000001

struct scsi_nl_transport {
	int (*msg_handler)(struct sk_buff *);
	void (*event_handler)(struct notifier_block *, unsigned long, void *);
	unsigned int refcnt;
	int flags;
};

/* flags values (bit flags) */
#define HANDLER_DELETING		0x1

static struct scsi_nl_transport transports[SCSI_NL_MAX_TRANSPORTS] =
	{ {NULL, }, };


struct scsi_nl_drvr {
	struct list_head next;
	int (*dmsg_handler)(struct Scsi_Host *shost, void *payload,
				 u32 len, u32 pid);
	void (*devt_handler)(struct notifier_block *nb,
				 unsigned long event, void *notify_ptr);
	struct scsi_host_template *hostt;
	u64 vendor_id;
	unsigned int refcnt;
	int flags;
};



/**
 * scsi_nl_rcv_msg - Receive message handler.
 * @skb:		socket receive buffer
 *
 * Description: Extracts message from a receive buffer.
 *    Validates message header and calls appropriate transport message handler
 *
 *
 **/
static void
scsi_nl_rcv_msg(struct sk_buff *skb)
{
	struct nlmsghdr *nlh;
	struct scsi_nl_hdr *hdr;
	unsigned long flags;
	u32 rlen;
	int err, tport;

	while (skb->len >= NLMSG_SPACE(0)) {
		err = 0;

		nlh = nlmsg_hdr(skb);
		if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
		    (skb->len < nlh->nlmsg_len)) {
			printk(KERN_WARNING "%s: discarding partial skb\n",
				 __func__);
			return;
		}

		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
		if (rlen > skb->len)
			rlen = skb->len;

		if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
			err = -EBADMSG;
			goto next_msg;
		}

		hdr = NLMSG_DATA(nlh);
		if ((hdr->version != SCSI_NL_VERSION) ||
		    (hdr->magic != SCSI_NL_MAGIC)) {
			err = -EPROTOTYPE;
			goto next_msg;
		}

		if (security_netlink_recv(skb, CAP_SYS_ADMIN)) {
			err = -EPERM;
			goto next_msg;
		}

		if (nlh->nlmsg_len < (sizeof(*nlh) + hdr->msglen)) {
			printk(KERN_WARNING "%s: discarding partial message\n",
				 __func__);
			goto next_msg;
		}

		/*
		 * Deliver message to the appropriate transport
		 */
		spin_lock_irqsave(&scsi_nl_lock, flags);

		tport = hdr->transport;
		if ((tport < SCSI_NL_MAX_TRANSPORTS) &&
		    !(transports[tport].flags & HANDLER_DELETING) &&
		    (transports[tport].msg_handler)) {
			transports[tport].refcnt++;
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			err = transports[tport].msg_handler(skb);
			spin_lock_irqsave(&scsi_nl_lock, flags);
			transports[tport].refcnt--;
		} else
			err = -ENOENT;

		spin_unlock_irqrestore(&scsi_nl_lock, flags);

next_msg:
		if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
			netlink_ack(skb, nlh, err);

		skb_pull(skb, rlen);
	}
}


/**
 * scsi_nl_rcv_event - Event handler for a netlink socket.
 * @this:		event notifier block
 * @event:		event type
 * @ptr:		event payload
 *
 **/
static int
scsi_nl_rcv_event(struct notifier_block *this, unsigned long event, void *ptr)
{
	struct netlink_notify *n = ptr;
	struct scsi_nl_drvr *driver;
	unsigned long flags;
	int tport;

	if (n->protocol != NETLINK_SCSITRANSPORT)
		return NOTIFY_DONE;

	spin_lock_irqsave(&scsi_nl_lock, flags);
	scsi_nl_state |= STATE_EHANDLER_BSY;

	/*
	 * Pass event on to any transports that may be listening
	 */
	for (tport = 0; tport < SCSI_NL_MAX_TRANSPORTS; tport++) {
		if (!(transports[tport].flags & HANDLER_DELETING) &&
		    (transports[tport].event_handler)) {
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			transports[tport].event_handler(this, event, ptr);
			spin_lock_irqsave(&scsi_nl_lock, flags);
		}
	}

	/*
	 * Pass event on to any drivers that may be listening
	 */
	list_for_each_entry(driver, &scsi_nl_drivers, next) {
		if (!(driver->flags & HANDLER_DELETING) &&
		    (driver->devt_handler)) {
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			driver->devt_handler(this, event, ptr);
			spin_lock_irqsave(&scsi_nl_lock, flags);
		}
	}

	scsi_nl_state &= ~STATE_EHANDLER_BSY;
	spin_unlock_irqrestore(&scsi_nl_lock, flags);

	return NOTIFY_DONE;
}

static struct notifier_block scsi_netlink_notifier = {
	.notifier_call  = scsi_nl_rcv_event,
};


/**
 * GENERIC SCSI transport receive and event handlers
 **/

/**
 * scsi_generic_msg_handler - receive message handler for GENERIC transport
 * 			 messages
 *
 * @skb:		socket receive buffer
 *
 **/
static int
scsi_generic_msg_handler(struct sk_buff *skb)
{
	struct nlmsghdr *nlh = nlmsg_hdr(skb);
	struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
	struct scsi_nl_drvr *driver;
	struct Scsi_Host *shost;
	unsigned long flags;
	int err = 0, match, pid;

	pid = NETLINK_CREDS(skb)->pid;

	switch (snlh->msgtype) {
	case SCSI_NL_SHOST_VENDOR:
		{
		struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);

		/* Locate the driver that corresponds to the message */
		spin_lock_irqsave(&scsi_nl_lock, flags);
		match = 0;
		list_for_each_entry(driver, &scsi_nl_drivers, next) {
			if (driver->vendor_id == msg->vendor_id) {
				match = 1;
				break;
			}
		}

		if ((!match) || (!driver->dmsg_handler)) {
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			err = -ESRCH;
			goto rcv_exit;
		}

		if (driver->flags & HANDLER_DELETING) {
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			err = -ESHUTDOWN;
			goto rcv_exit;
		}

		driver->refcnt++;
		spin_unlock_irqrestore(&scsi_nl_lock, flags);


		/* if successful, scsi_host_lookup takes a shost reference */
		shost = scsi_host_lookup(msg->host_no);
		if (!shost) {
			err = -ENODEV;
			goto driver_exit;
		}

		/* is this host owned by the vendor ? */
		if (shost->hostt != driver->hostt) {
			err = -EINVAL;
			goto vendormsg_put;
		}

		/* pass message on to the driver */
		err = driver->dmsg_handler(shost, (void *)&msg[1],
					 msg->vmsg_datalen, pid);

vendormsg_put:
		/* release reference by scsi_host_lookup */
		scsi_host_put(shost);

driver_exit:
		/* release our own reference on the registration object */
		spin_lock_irqsave(&scsi_nl_lock, flags);
		driver->refcnt--;
		spin_unlock_irqrestore(&scsi_nl_lock, flags);
		break;
		}

	default:
		err = -EBADR;
		break;
	}

rcv_exit:
	if (err)
		printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
			 __func__, snlh->msgtype, err);
	return err;
}


/**
 * scsi_nl_add_transport -
 *    Registers message and event handlers for a transport. Enables
 *    receipt of netlink messages and events to a transport.
 *
 * @tport:		transport registering handlers
 * @msg_handler:	receive message handler callback
 * @event_handler:	receive event handler callback
 **/
int
scsi_nl_add_transport(u8 tport,
	int (*msg_handler)(struct sk_buff *),
	void (*event_handler)(struct notifier_block *, unsigned long, void *))
{
	unsigned long flags;
	int err = 0;

	if (tport >= SCSI_NL_MAX_TRANSPORTS)
		return -EINVAL;

	spin_lock_irqsave(&scsi_nl_lock, flags);

	if (scsi_nl_state & STATE_EHANDLER_BSY) {
		spin_unlock_irqrestore(&scsi_nl_lock, flags);
		msleep(1);
		spin_lock_irqsave(&scsi_nl_lock, flags);
	}

	if (transports[tport].msg_handler || transports[tport].event_handler) {
		err = -EALREADY;
		goto register_out;
	}

	transports[tport].msg_handler = msg_handler;
	transports[tport].event_handler = event_handler;
	transports[tport].flags = 0;
	transports[tport].refcnt = 0;

register_out:
	spin_unlock_irqrestore(&scsi_nl_lock, flags);

	return err;
}
EXPORT_SYMBOL_GPL(scsi_nl_add_transport);


/**
 * scsi_nl_remove_transport -
 *    Disable transport receiption of messages and events
 *
 * @tport:		transport deregistering handlers
 *
 **/
void
scsi_nl_remove_transport(u8 tport)
{
	unsigned long flags;

	spin_lock_irqsave(&scsi_nl_lock, flags);
	if (scsi_nl_state & STATE_EHANDLER_BSY) {
		spin_unlock_irqrestore(&scsi_nl_lock, flags);
		msleep(1);
		spin_lock_irqsave(&scsi_nl_lock, flags);
	}

	if (tport < SCSI_NL_MAX_TRANSPORTS) {
		transports[tport].flags |= HANDLER_DELETING;

		while (transports[tport].refcnt != 0) {
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			schedule_timeout_uninterruptible(HZ/4);
			spin_lock_irqsave(&scsi_nl_lock, flags);
		}
		transports[tport].msg_handler = NULL;
		transports[tport].event_handler = NULL;
		transports[tport].flags = 0;
	}

	spin_unlock_irqrestore(&scsi_nl_lock, flags);

	return;
}
EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);


/**
 * scsi_nl_add_driver -
 *    A driver is registering its interfaces for SCSI netlink messages
 *
 * @vendor_id:          A unique identification value for the driver.
 * @hostt:		address of the driver's host template. Used
 *			to verify an shost is bound to the driver
 * @nlmsg_handler:	receive message handler callback
 * @nlevt_handler:	receive event handler callback
 *
 * Returns:
 *   0 on Success
 *   error result otherwise
 **/
int
scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
	int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
				 u32 len, u32 pid),
	void (*nlevt_handler)(struct notifier_block *nb,
				 unsigned long event, void *notify_ptr))
{
	struct scsi_nl_drvr *driver;
	unsigned long flags;

	driver = kzalloc(sizeof(*driver), GFP_KERNEL);
	if (unlikely(!driver)) {
		printk(KERN_ERR "%s: allocation failure\n", __func__);
		return -ENOMEM;
	}

	driver->dmsg_handler = nlmsg_handler;
	driver->devt_handler = nlevt_handler;
	driver->hostt = hostt;
	driver->vendor_id = vendor_id;

	spin_lock_irqsave(&scsi_nl_lock, flags);
	if (scsi_nl_state & STATE_EHANDLER_BSY) {
		spin_unlock_irqrestore(&scsi_nl_lock, flags);
		msleep(1);
		spin_lock_irqsave(&scsi_nl_lock, flags);
	}
	list_add_tail(&driver->next, &scsi_nl_drivers);
	spin_unlock_irqrestore(&scsi_nl_lock, flags);

	return 0;
}
EXPORT_SYMBOL_GPL(scsi_nl_add_driver);


/**
 * scsi_nl_remove_driver -
 *    An driver is unregistering with the SCSI netlink messages
 *
 * @vendor_id:          The unique identification value for the driver.
 **/
void
scsi_nl_remove_driver(u64 vendor_id)
{
	struct scsi_nl_drvr *driver;
	unsigned long flags;

	spin_lock_irqsave(&scsi_nl_lock, flags);
	if (scsi_nl_state & STATE_EHANDLER_BSY) {
		spin_unlock_irqrestore(&scsi_nl_lock, flags);
		msleep(1);
		spin_lock_irqsave(&scsi_nl_lock, flags);
	}

	list_for_each_entry(driver, &scsi_nl_drivers, next) {
		if (driver->vendor_id == vendor_id) {
			driver->flags |= HANDLER_DELETING;
			while (driver->refcnt != 0) {
				spin_unlock_irqrestore(&scsi_nl_lock, flags);
				schedule_timeout_uninterruptible(HZ/4);
				spin_lock_irqsave(&scsi_nl_lock, flags);
			}
			list_del(&driver->next);
			kfree(driver);
			spin_unlock_irqrestore(&scsi_nl_lock, flags);
			return;
		}
	}

	spin_unlock_irqrestore(&scsi_nl_lock, flags);

	printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
	       __func__, (unsigned long long)vendor_id);
	return;
}
EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);


/**
 * scsi_netlink_init - Called by SCSI subsystem to intialize
 * 	the SCSI transport netlink interface
 *
 **/
void
scsi_netlink_init(void)
{
	int error;

	INIT_LIST_HEAD(&scsi_nl_drivers);

	error = netlink_register_notifier(&scsi_netlink_notifier);
	if (error) {
		printk(KERN_ERR "%s: register of event handler failed - %d\n",
				__func__, error);
		return;
	}

	scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
				SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
				THIS_MODULE);
	if (!scsi_nl_sock) {
		printk(KERN_ERR "%s: register of recieve handler failed\n",
				__func__);
		netlink_unregister_notifier(&scsi_netlink_notifier);
		return;
	}

	/* Register the entry points for the generic SCSI transport */
	error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
				scsi_generic_msg_handler, NULL);
	if (error)
		printk(KERN_ERR "%s: register of GENERIC transport handler"
				"  failed - %d\n", __func__, error);
	return;
}


/**
 * scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
 *
 **/
void
scsi_netlink_exit(void)
{
	scsi_nl_remove_transport(SCSI_NL_TRANSPORT);

	if (scsi_nl_sock) {
		netlink_kernel_release(scsi_nl_sock);
		netlink_unregister_notifier(&scsi_netlink_notifier);
	}

	return;
}


/*
 * Exported Interfaces
 */

/**
 * scsi_nl_send_transport_msg -
 *    Generic function to send a single message from a SCSI transport to
 *    a single process
 *
 * @pid:		receiving pid
 * @hdr:		message payload
 *
 **/
void
scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
{
	struct sk_buff *skb;
	struct nlmsghdr	*nlh;
	const char *fn;
	char *datab;
	u32 len, skblen;
	int err;

	if (!scsi_nl_sock) {
		err = -ENOENT;
		fn = "netlink socket";
		goto msg_fail;
	}

	len = NLMSG_SPACE(hdr->msglen);
	skblen = NLMSG_SPACE(len);

	skb = alloc_skb(skblen, GFP_KERNEL);
	if (!skb) {
		err = -ENOBUFS;
		fn = "alloc_skb";
		goto msg_fail;
	}

	nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
	if (!nlh) {
		err = -ENOBUFS;
		fn = "nlmsg_put";
		goto msg_fail_skb;
	}
	datab = NLMSG_DATA(nlh);
	memcpy(datab, hdr, hdr->msglen);

	err = nlmsg_unicast(scsi_nl_sock, skb, pid);
	if (err < 0) {
		fn = "nlmsg_unicast";
		/* nlmsg_unicast already kfree_skb'd */
		goto msg_fail;
	}

	return;

msg_fail_skb:
	kfree_skb(skb);
msg_fail:
	printk(KERN_WARNING
		"%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
		"msglen %d: %s : err %d\n",
		__func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
		fn, err);
	return;
}
EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);


/**
 * scsi_nl_send_vendor_msg - called to send a shost vendor unique message
 *                      to a specific process id.
 *
 * @pid:		process id of the receiver
 * @host_no:		host # sending the message
 * @vendor_id:		unique identifier for the driver's vendor
 * @data_len:		amount, in bytes, of vendor unique payload data
 * @data_buf:		pointer to vendor unique data buffer
 *
 * Returns:
 *   0 on succesful return
 *   otherwise, failing error code
 *
 * Notes:
 *	This routine assumes no locks are held on entry.
 */
int
scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
			 char *data_buf, u32 data_len)
{
	struct sk_buff *skb;
	struct nlmsghdr	*nlh;
	struct scsi_nl_host_vendor_msg *msg;
	u32 len, skblen;
	int err;

	if (!scsi_nl_sock) {
		err = -ENOENT;
		goto send_vendor_fail;
	}

	len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
	skblen = NLMSG_SPACE(len);

	skb = alloc_skb(skblen, GFP_KERNEL);
	if (!skb) {
		err = -ENOBUFS;
		goto send_vendor_fail;
	}

	nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
				skblen - sizeof(*nlh), 0);
	if (!nlh) {
		err = -ENOBUFS;
		goto send_vendor_fail_skb;
	}
	msg = NLMSG_DATA(nlh);

	INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
				SCSI_NL_SHOST_VENDOR, len);
	msg->vendor_id = vendor_id;
	msg->host_no = host_no;
	msg->vmsg_datalen = data_len;	/* bytes */
	memcpy(&msg[1], data_buf, data_len);

	err = nlmsg_unicast(scsi_nl_sock, skb, pid);
	if (err)
		/* nlmsg_multicast already kfree_skb'd */
		goto send_vendor_fail;

	return 0;

send_vendor_fail_skb:
	kfree_skb(skb);
send_vendor_fail:
	printk(KERN_WARNING
		"%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
		__func__, host_no, err);
	return err;
}
EXPORT_SYMBOL(scsi_nl_send_vendor_msg);