xref: /openbmc/linux/drivers/scsi/scsi_netlink.c (revision 9ac8d3fb)
1 /*
2  *  scsi_netlink.c  - SCSI Transport Netlink Interface
3  *
4  *  Copyright (C) 2006   James Smart, Emulex Corporation
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, write to the Free Software
18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  *
20  */
21 #include <linux/time.h>
22 #include <linux/jiffies.h>
23 #include <linux/security.h>
24 #include <linux/delay.h>
25 #include <net/sock.h>
26 #include <net/netlink.h>
27 
28 #include <scsi/scsi_netlink.h>
29 #include "scsi_priv.h"
30 
31 struct sock *scsi_nl_sock = NULL;
32 EXPORT_SYMBOL_GPL(scsi_nl_sock);
33 
34 static DEFINE_SPINLOCK(scsi_nl_lock);
35 static struct list_head scsi_nl_drivers;
36 
37 static u32	scsi_nl_state;
38 #define STATE_EHANDLER_BSY		0x00000001
39 
40 struct scsi_nl_transport {
41 	int (*msg_handler)(struct sk_buff *);
42 	void (*event_handler)(struct notifier_block *, unsigned long, void *);
43 	unsigned int refcnt;
44 	int flags;
45 };
46 
47 /* flags values (bit flags) */
48 #define HANDLER_DELETING		0x1
49 
50 static struct scsi_nl_transport transports[SCSI_NL_MAX_TRANSPORTS] =
51 	{ {NULL, }, };
52 
53 
54 struct scsi_nl_drvr {
55 	struct list_head next;
56 	int (*dmsg_handler)(struct Scsi_Host *shost, void *payload,
57 				 u32 len, u32 pid);
58 	void (*devt_handler)(struct notifier_block *nb,
59 				 unsigned long event, void *notify_ptr);
60 	struct scsi_host_template *hostt;
61 	u64 vendor_id;
62 	unsigned int refcnt;
63 	int flags;
64 };
65 
66 
67 
68 /**
69  * scsi_nl_rcv_msg - Receive message handler.
70  * @skb:		socket receive buffer
71  *
72  * Description: Extracts message from a receive buffer.
73  *    Validates message header and calls appropriate transport message handler
74  *
75  *
76  **/
77 static void
78 scsi_nl_rcv_msg(struct sk_buff *skb)
79 {
80 	struct nlmsghdr *nlh;
81 	struct scsi_nl_hdr *hdr;
82 	unsigned long flags;
83 	u32 rlen;
84 	int err, tport;
85 
86 	while (skb->len >= NLMSG_SPACE(0)) {
87 		err = 0;
88 
89 		nlh = nlmsg_hdr(skb);
90 		if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
91 		    (skb->len < nlh->nlmsg_len)) {
92 			printk(KERN_WARNING "%s: discarding partial skb\n",
93 				 __func__);
94 			return;
95 		}
96 
97 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
98 		if (rlen > skb->len)
99 			rlen = skb->len;
100 
101 		if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
102 			err = -EBADMSG;
103 			goto next_msg;
104 		}
105 
106 		hdr = NLMSG_DATA(nlh);
107 		if ((hdr->version != SCSI_NL_VERSION) ||
108 		    (hdr->magic != SCSI_NL_MAGIC)) {
109 			err = -EPROTOTYPE;
110 			goto next_msg;
111 		}
112 
113 		if (security_netlink_recv(skb, CAP_SYS_ADMIN)) {
114 			err = -EPERM;
115 			goto next_msg;
116 		}
117 
118 		if (nlh->nlmsg_len < (sizeof(*nlh) + hdr->msglen)) {
119 			printk(KERN_WARNING "%s: discarding partial message\n",
120 				 __func__);
121 			goto next_msg;
122 		}
123 
124 		/*
125 		 * Deliver message to the appropriate transport
126 		 */
127 		spin_lock_irqsave(&scsi_nl_lock, flags);
128 
129 		tport = hdr->transport;
130 		if ((tport < SCSI_NL_MAX_TRANSPORTS) &&
131 		    !(transports[tport].flags & HANDLER_DELETING) &&
132 		    (transports[tport].msg_handler)) {
133 			transports[tport].refcnt++;
134 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
135 			err = transports[tport].msg_handler(skb);
136 			spin_lock_irqsave(&scsi_nl_lock, flags);
137 			transports[tport].refcnt--;
138 		} else
139 			err = -ENOENT;
140 
141 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
142 
143 next_msg:
144 		if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
145 			netlink_ack(skb, nlh, err);
146 
147 		skb_pull(skb, rlen);
148 	}
149 }
150 
151 
152 /**
153  * scsi_nl_rcv_event - Event handler for a netlink socket.
154  * @this:		event notifier block
155  * @event:		event type
156  * @ptr:		event payload
157  *
158  **/
159 static int
160 scsi_nl_rcv_event(struct notifier_block *this, unsigned long event, void *ptr)
161 {
162 	struct netlink_notify *n = ptr;
163 	struct scsi_nl_drvr *driver;
164 	unsigned long flags;
165 	int tport;
166 
167 	if (n->protocol != NETLINK_SCSITRANSPORT)
168 		return NOTIFY_DONE;
169 
170 	spin_lock_irqsave(&scsi_nl_lock, flags);
171 	scsi_nl_state |= STATE_EHANDLER_BSY;
172 
173 	/*
174 	 * Pass event on to any transports that may be listening
175 	 */
176 	for (tport = 0; tport < SCSI_NL_MAX_TRANSPORTS; tport++) {
177 		if (!(transports[tport].flags & HANDLER_DELETING) &&
178 		    (transports[tport].event_handler)) {
179 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
180 			transports[tport].event_handler(this, event, ptr);
181 			spin_lock_irqsave(&scsi_nl_lock, flags);
182 		}
183 	}
184 
185 	/*
186 	 * Pass event on to any drivers that may be listening
187 	 */
188 	list_for_each_entry(driver, &scsi_nl_drivers, next) {
189 		if (!(driver->flags & HANDLER_DELETING) &&
190 		    (driver->devt_handler)) {
191 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
192 			driver->devt_handler(this, event, ptr);
193 			spin_lock_irqsave(&scsi_nl_lock, flags);
194 		}
195 	}
196 
197 	scsi_nl_state &= ~STATE_EHANDLER_BSY;
198 	spin_unlock_irqrestore(&scsi_nl_lock, flags);
199 
200 	return NOTIFY_DONE;
201 }
202 
203 static struct notifier_block scsi_netlink_notifier = {
204 	.notifier_call  = scsi_nl_rcv_event,
205 };
206 
207 
208 /*
209  * GENERIC SCSI transport receive and event handlers
210  */
211 
212 /**
213  * scsi_generic_msg_handler - receive message handler for GENERIC transport messages
214  * @skb:		socket receive buffer
215  **/
216 static int
217 scsi_generic_msg_handler(struct sk_buff *skb)
218 {
219 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
220 	struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
221 	struct scsi_nl_drvr *driver;
222 	struct Scsi_Host *shost;
223 	unsigned long flags;
224 	int err = 0, match, pid;
225 
226 	pid = NETLINK_CREDS(skb)->pid;
227 
228 	switch (snlh->msgtype) {
229 	case SCSI_NL_SHOST_VENDOR:
230 		{
231 		struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);
232 
233 		/* Locate the driver that corresponds to the message */
234 		spin_lock_irqsave(&scsi_nl_lock, flags);
235 		match = 0;
236 		list_for_each_entry(driver, &scsi_nl_drivers, next) {
237 			if (driver->vendor_id == msg->vendor_id) {
238 				match = 1;
239 				break;
240 			}
241 		}
242 
243 		if ((!match) || (!driver->dmsg_handler)) {
244 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
245 			err = -ESRCH;
246 			goto rcv_exit;
247 		}
248 
249 		if (driver->flags & HANDLER_DELETING) {
250 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
251 			err = -ESHUTDOWN;
252 			goto rcv_exit;
253 		}
254 
255 		driver->refcnt++;
256 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
257 
258 
259 		/* if successful, scsi_host_lookup takes a shost reference */
260 		shost = scsi_host_lookup(msg->host_no);
261 		if (!shost) {
262 			err = -ENODEV;
263 			goto driver_exit;
264 		}
265 
266 		/* is this host owned by the vendor ? */
267 		if (shost->hostt != driver->hostt) {
268 			err = -EINVAL;
269 			goto vendormsg_put;
270 		}
271 
272 		/* pass message on to the driver */
273 		err = driver->dmsg_handler(shost, (void *)&msg[1],
274 					 msg->vmsg_datalen, pid);
275 
276 vendormsg_put:
277 		/* release reference by scsi_host_lookup */
278 		scsi_host_put(shost);
279 
280 driver_exit:
281 		/* release our own reference on the registration object */
282 		spin_lock_irqsave(&scsi_nl_lock, flags);
283 		driver->refcnt--;
284 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
285 		break;
286 		}
287 
288 	default:
289 		err = -EBADR;
290 		break;
291 	}
292 
293 rcv_exit:
294 	if (err)
295 		printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
296 			 __func__, snlh->msgtype, err);
297 	return err;
298 }
299 
300 
301 /**
302  * scsi_nl_add_transport -
303  *    Registers message and event handlers for a transport. Enables
304  *    receipt of netlink messages and events to a transport.
305  *
306  * @tport:		transport registering handlers
307  * @msg_handler:	receive message handler callback
308  * @event_handler:	receive event handler callback
309  **/
310 int
311 scsi_nl_add_transport(u8 tport,
312 	int (*msg_handler)(struct sk_buff *),
313 	void (*event_handler)(struct notifier_block *, unsigned long, void *))
314 {
315 	unsigned long flags;
316 	int err = 0;
317 
318 	if (tport >= SCSI_NL_MAX_TRANSPORTS)
319 		return -EINVAL;
320 
321 	spin_lock_irqsave(&scsi_nl_lock, flags);
322 
323 	if (scsi_nl_state & STATE_EHANDLER_BSY) {
324 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
325 		msleep(1);
326 		spin_lock_irqsave(&scsi_nl_lock, flags);
327 	}
328 
329 	if (transports[tport].msg_handler || transports[tport].event_handler) {
330 		err = -EALREADY;
331 		goto register_out;
332 	}
333 
334 	transports[tport].msg_handler = msg_handler;
335 	transports[tport].event_handler = event_handler;
336 	transports[tport].flags = 0;
337 	transports[tport].refcnt = 0;
338 
339 register_out:
340 	spin_unlock_irqrestore(&scsi_nl_lock, flags);
341 
342 	return err;
343 }
344 EXPORT_SYMBOL_GPL(scsi_nl_add_transport);
345 
346 
347 /**
348  * scsi_nl_remove_transport -
349  *    Disable transport receiption of messages and events
350  *
351  * @tport:		transport deregistering handlers
352  *
353  **/
354 void
355 scsi_nl_remove_transport(u8 tport)
356 {
357 	unsigned long flags;
358 
359 	spin_lock_irqsave(&scsi_nl_lock, flags);
360 	if (scsi_nl_state & STATE_EHANDLER_BSY) {
361 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
362 		msleep(1);
363 		spin_lock_irqsave(&scsi_nl_lock, flags);
364 	}
365 
366 	if (tport < SCSI_NL_MAX_TRANSPORTS) {
367 		transports[tport].flags |= HANDLER_DELETING;
368 
369 		while (transports[tport].refcnt != 0) {
370 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
371 			schedule_timeout_uninterruptible(HZ/4);
372 			spin_lock_irqsave(&scsi_nl_lock, flags);
373 		}
374 		transports[tport].msg_handler = NULL;
375 		transports[tport].event_handler = NULL;
376 		transports[tport].flags = 0;
377 	}
378 
379 	spin_unlock_irqrestore(&scsi_nl_lock, flags);
380 
381 	return;
382 }
383 EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);
384 
385 
386 /**
387  * scsi_nl_add_driver -
388  *    A driver is registering its interfaces for SCSI netlink messages
389  *
390  * @vendor_id:          A unique identification value for the driver.
391  * @hostt:		address of the driver's host template. Used
392  *			to verify an shost is bound to the driver
393  * @nlmsg_handler:	receive message handler callback
394  * @nlevt_handler:	receive event handler callback
395  *
396  * Returns:
397  *   0 on Success
398  *   error result otherwise
399  **/
400 int
401 scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
402 	int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
403 				 u32 len, u32 pid),
404 	void (*nlevt_handler)(struct notifier_block *nb,
405 				 unsigned long event, void *notify_ptr))
406 {
407 	struct scsi_nl_drvr *driver;
408 	unsigned long flags;
409 
410 	driver = kzalloc(sizeof(*driver), GFP_KERNEL);
411 	if (unlikely(!driver)) {
412 		printk(KERN_ERR "%s: allocation failure\n", __func__);
413 		return -ENOMEM;
414 	}
415 
416 	driver->dmsg_handler = nlmsg_handler;
417 	driver->devt_handler = nlevt_handler;
418 	driver->hostt = hostt;
419 	driver->vendor_id = vendor_id;
420 
421 	spin_lock_irqsave(&scsi_nl_lock, flags);
422 	if (scsi_nl_state & STATE_EHANDLER_BSY) {
423 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
424 		msleep(1);
425 		spin_lock_irqsave(&scsi_nl_lock, flags);
426 	}
427 	list_add_tail(&driver->next, &scsi_nl_drivers);
428 	spin_unlock_irqrestore(&scsi_nl_lock, flags);
429 
430 	return 0;
431 }
432 EXPORT_SYMBOL_GPL(scsi_nl_add_driver);
433 
434 
435 /**
436  * scsi_nl_remove_driver -
437  *    An driver is unregistering with the SCSI netlink messages
438  *
439  * @vendor_id:          The unique identification value for the driver.
440  **/
441 void
442 scsi_nl_remove_driver(u64 vendor_id)
443 {
444 	struct scsi_nl_drvr *driver;
445 	unsigned long flags;
446 
447 	spin_lock_irqsave(&scsi_nl_lock, flags);
448 	if (scsi_nl_state & STATE_EHANDLER_BSY) {
449 		spin_unlock_irqrestore(&scsi_nl_lock, flags);
450 		msleep(1);
451 		spin_lock_irqsave(&scsi_nl_lock, flags);
452 	}
453 
454 	list_for_each_entry(driver, &scsi_nl_drivers, next) {
455 		if (driver->vendor_id == vendor_id) {
456 			driver->flags |= HANDLER_DELETING;
457 			while (driver->refcnt != 0) {
458 				spin_unlock_irqrestore(&scsi_nl_lock, flags);
459 				schedule_timeout_uninterruptible(HZ/4);
460 				spin_lock_irqsave(&scsi_nl_lock, flags);
461 			}
462 			list_del(&driver->next);
463 			kfree(driver);
464 			spin_unlock_irqrestore(&scsi_nl_lock, flags);
465 			return;
466 		}
467 	}
468 
469 	spin_unlock_irqrestore(&scsi_nl_lock, flags);
470 
471 	printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
472 	       __func__, (unsigned long long)vendor_id);
473 	return;
474 }
475 EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
476 
477 
478 /**
479  * scsi_netlink_init - Called by SCSI subsystem to intialize
480  * 	the SCSI transport netlink interface
481  *
482  **/
483 void
484 scsi_netlink_init(void)
485 {
486 	int error;
487 
488 	INIT_LIST_HEAD(&scsi_nl_drivers);
489 
490 	error = netlink_register_notifier(&scsi_netlink_notifier);
491 	if (error) {
492 		printk(KERN_ERR "%s: register of event handler failed - %d\n",
493 				__func__, error);
494 		return;
495 	}
496 
497 	scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
498 				SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
499 				THIS_MODULE);
500 	if (!scsi_nl_sock) {
501 		printk(KERN_ERR "%s: register of recieve handler failed\n",
502 				__func__);
503 		netlink_unregister_notifier(&scsi_netlink_notifier);
504 		return;
505 	}
506 
507 	/* Register the entry points for the generic SCSI transport */
508 	error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
509 				scsi_generic_msg_handler, NULL);
510 	if (error)
511 		printk(KERN_ERR "%s: register of GENERIC transport handler"
512 				"  failed - %d\n", __func__, error);
513 	return;
514 }
515 
516 
517 /**
518  * scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
519  *
520  **/
521 void
522 scsi_netlink_exit(void)
523 {
524 	scsi_nl_remove_transport(SCSI_NL_TRANSPORT);
525 
526 	if (scsi_nl_sock) {
527 		netlink_kernel_release(scsi_nl_sock);
528 		netlink_unregister_notifier(&scsi_netlink_notifier);
529 	}
530 
531 	return;
532 }
533 
534 
535 /*
536  * Exported Interfaces
537  */
538 
539 /**
540  * scsi_nl_send_transport_msg -
541  *    Generic function to send a single message from a SCSI transport to
542  *    a single process
543  *
544  * @pid:		receiving pid
545  * @hdr:		message payload
546  *
547  **/
548 void
549 scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
550 {
551 	struct sk_buff *skb;
552 	struct nlmsghdr	*nlh;
553 	const char *fn;
554 	char *datab;
555 	u32 len, skblen;
556 	int err;
557 
558 	if (!scsi_nl_sock) {
559 		err = -ENOENT;
560 		fn = "netlink socket";
561 		goto msg_fail;
562 	}
563 
564 	len = NLMSG_SPACE(hdr->msglen);
565 	skblen = NLMSG_SPACE(len);
566 
567 	skb = alloc_skb(skblen, GFP_KERNEL);
568 	if (!skb) {
569 		err = -ENOBUFS;
570 		fn = "alloc_skb";
571 		goto msg_fail;
572 	}
573 
574 	nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
575 	if (!nlh) {
576 		err = -ENOBUFS;
577 		fn = "nlmsg_put";
578 		goto msg_fail_skb;
579 	}
580 	datab = NLMSG_DATA(nlh);
581 	memcpy(datab, hdr, hdr->msglen);
582 
583 	err = nlmsg_unicast(scsi_nl_sock, skb, pid);
584 	if (err < 0) {
585 		fn = "nlmsg_unicast";
586 		/* nlmsg_unicast already kfree_skb'd */
587 		goto msg_fail;
588 	}
589 
590 	return;
591 
592 msg_fail_skb:
593 	kfree_skb(skb);
594 msg_fail:
595 	printk(KERN_WARNING
596 		"%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
597 		"msglen %d: %s : err %d\n",
598 		__func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
599 		fn, err);
600 	return;
601 }
602 EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);
603 
604 
605 /**
606  * scsi_nl_send_vendor_msg - called to send a shost vendor unique message
607  *                      to a specific process id.
608  *
609  * @pid:		process id of the receiver
610  * @host_no:		host # sending the message
611  * @vendor_id:		unique identifier for the driver's vendor
612  * @data_len:		amount, in bytes, of vendor unique payload data
613  * @data_buf:		pointer to vendor unique data buffer
614  *
615  * Returns:
616  *   0 on succesful return
617  *   otherwise, failing error code
618  *
619  * Notes:
620  *	This routine assumes no locks are held on entry.
621  */
622 int
623 scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
624 			 char *data_buf, u32 data_len)
625 {
626 	struct sk_buff *skb;
627 	struct nlmsghdr	*nlh;
628 	struct scsi_nl_host_vendor_msg *msg;
629 	u32 len, skblen;
630 	int err;
631 
632 	if (!scsi_nl_sock) {
633 		err = -ENOENT;
634 		goto send_vendor_fail;
635 	}
636 
637 	len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
638 	skblen = NLMSG_SPACE(len);
639 
640 	skb = alloc_skb(skblen, GFP_KERNEL);
641 	if (!skb) {
642 		err = -ENOBUFS;
643 		goto send_vendor_fail;
644 	}
645 
646 	nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
647 				skblen - sizeof(*nlh), 0);
648 	if (!nlh) {
649 		err = -ENOBUFS;
650 		goto send_vendor_fail_skb;
651 	}
652 	msg = NLMSG_DATA(nlh);
653 
654 	INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
655 				SCSI_NL_SHOST_VENDOR, len);
656 	msg->vendor_id = vendor_id;
657 	msg->host_no = host_no;
658 	msg->vmsg_datalen = data_len;	/* bytes */
659 	memcpy(&msg[1], data_buf, data_len);
660 
661 	err = nlmsg_unicast(scsi_nl_sock, skb, pid);
662 	if (err)
663 		/* nlmsg_multicast already kfree_skb'd */
664 		goto send_vendor_fail;
665 
666 	return 0;
667 
668 send_vendor_fail_skb:
669 	kfree_skb(skb);
670 send_vendor_fail:
671 	printk(KERN_WARNING
672 		"%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
673 		__func__, host_no, err);
674 	return err;
675 }
676 EXPORT_SYMBOL(scsi_nl_send_vendor_msg);
677 
678 
679