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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
214  *                       messages
215  *
216  * @skb:                socket receive buffer
217  *
218  **/
219 static int
220 scsi_generic_msg_handler(struct sk_buff *skb)
221 {
222         struct nlmsghdr *nlh = nlmsg_hdr(skb);
223         struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
224         struct scsi_nl_drvr *driver;
225         struct Scsi_Host *shost;
226         unsigned long flags;
227         int err = 0, match, pid;
228
229         pid = NETLINK_CREDS(skb)->pid;
230
231         switch (snlh->msgtype) {
232         case SCSI_NL_SHOST_VENDOR:
233                 {
234                 struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);
235
236                 /* Locate the driver that corresponds to the message */
237                 spin_lock_irqsave(&scsi_nl_lock, flags);
238                 match = 0;
239                 list_for_each_entry(driver, &scsi_nl_drivers, next) {
240                         if (driver->vendor_id == msg->vendor_id) {
241                                 match = 1;
242                                 break;
243                         }
244                 }
245
246                 if ((!match) || (!driver->dmsg_handler)) {
247                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
248                         err = -ESRCH;
249                         goto rcv_exit;
250                 }
251
252                 if (driver->flags & HANDLER_DELETING) {
253                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
254                         err = -ESHUTDOWN;
255                         goto rcv_exit;
256                 }
257
258                 driver->refcnt++;
259                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
260
261
262                 /* if successful, scsi_host_lookup takes a shost reference */
263                 shost = scsi_host_lookup(msg->host_no);
264                 if (!shost) {
265                         err = -ENODEV;
266                         goto driver_exit;
267                 }
268
269                 /* is this host owned by the vendor ? */
270                 if (shost->hostt != driver->hostt) {
271                         err = -EINVAL;
272                         goto vendormsg_put;
273                 }
274
275                 /* pass message on to the driver */
276                 err = driver->dmsg_handler(shost, (void *)&msg[1],
277                                          msg->vmsg_datalen, pid);
278
279 vendormsg_put:
280                 /* release reference by scsi_host_lookup */
281                 scsi_host_put(shost);
282
283 driver_exit:
284                 /* release our own reference on the registration object */
285                 spin_lock_irqsave(&scsi_nl_lock, flags);
286                 driver->refcnt--;
287                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
288                 break;
289                 }
290
291         default:
292                 err = -EBADR;
293                 break;
294         }
295
296 rcv_exit:
297         if (err)
298                 printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
299                          __func__, snlh->msgtype, err);
300         return err;
301 }
302
303
304 /**
305  * scsi_nl_add_transport -
306  *    Registers message and event handlers for a transport. Enables
307  *    receipt of netlink messages and events to a transport.
308  *
309  * @tport:              transport registering handlers
310  * @msg_handler:        receive message handler callback
311  * @event_handler:      receive event handler callback
312  **/
313 int
314 scsi_nl_add_transport(u8 tport,
315         int (*msg_handler)(struct sk_buff *),
316         void (*event_handler)(struct notifier_block *, unsigned long, void *))
317 {
318         unsigned long flags;
319         int err = 0;
320
321         if (tport >= SCSI_NL_MAX_TRANSPORTS)
322                 return -EINVAL;
323
324         spin_lock_irqsave(&scsi_nl_lock, flags);
325
326         if (scsi_nl_state & STATE_EHANDLER_BSY) {
327                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
328                 msleep(1);
329                 spin_lock_irqsave(&scsi_nl_lock, flags);
330         }
331
332         if (transports[tport].msg_handler || transports[tport].event_handler) {
333                 err = -EALREADY;
334                 goto register_out;
335         }
336
337         transports[tport].msg_handler = msg_handler;
338         transports[tport].event_handler = event_handler;
339         transports[tport].flags = 0;
340         transports[tport].refcnt = 0;
341
342 register_out:
343         spin_unlock_irqrestore(&scsi_nl_lock, flags);
344
345         return err;
346 }
347 EXPORT_SYMBOL_GPL(scsi_nl_add_transport);
348
349
350 /**
351  * scsi_nl_remove_transport -
352  *    Disable transport receiption of messages and events
353  *
354  * @tport:              transport deregistering handlers
355  *
356  **/
357 void
358 scsi_nl_remove_transport(u8 tport)
359 {
360         unsigned long flags;
361
362         spin_lock_irqsave(&scsi_nl_lock, flags);
363         if (scsi_nl_state & STATE_EHANDLER_BSY) {
364                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
365                 msleep(1);
366                 spin_lock_irqsave(&scsi_nl_lock, flags);
367         }
368
369         if (tport < SCSI_NL_MAX_TRANSPORTS) {
370                 transports[tport].flags |= HANDLER_DELETING;
371
372                 while (transports[tport].refcnt != 0) {
373                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
374                         schedule_timeout_uninterruptible(HZ/4);
375                         spin_lock_irqsave(&scsi_nl_lock, flags);
376                 }
377                 transports[tport].msg_handler = NULL;
378                 transports[tport].event_handler = NULL;
379                 transports[tport].flags = 0;
380         }
381
382         spin_unlock_irqrestore(&scsi_nl_lock, flags);
383
384         return;
385 }
386 EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);
387
388
389 /**
390  * scsi_nl_add_driver -
391  *    A driver is registering its interfaces for SCSI netlink messages
392  *
393  * @vendor_id:          A unique identification value for the driver.
394  * @hostt:              address of the driver's host template. Used
395  *                      to verify an shost is bound to the driver
396  * @nlmsg_handler:      receive message handler callback
397  * @nlevt_handler:      receive event handler callback
398  *
399  * Returns:
400  *   0 on Success
401  *   error result otherwise
402  **/
403 int
404 scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
405         int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
406                                  u32 len, u32 pid),
407         void (*nlevt_handler)(struct notifier_block *nb,
408                                  unsigned long event, void *notify_ptr))
409 {
410         struct scsi_nl_drvr *driver;
411         unsigned long flags;
412
413         driver = kzalloc(sizeof(*driver), GFP_KERNEL);
414         if (unlikely(!driver)) {
415                 printk(KERN_ERR "%s: allocation failure\n", __func__);
416                 return -ENOMEM;
417         }
418
419         driver->dmsg_handler = nlmsg_handler;
420         driver->devt_handler = nlevt_handler;
421         driver->hostt = hostt;
422         driver->vendor_id = vendor_id;
423
424         spin_lock_irqsave(&scsi_nl_lock, flags);
425         if (scsi_nl_state & STATE_EHANDLER_BSY) {
426                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
427                 msleep(1);
428                 spin_lock_irqsave(&scsi_nl_lock, flags);
429         }
430         list_add_tail(&driver->next, &scsi_nl_drivers);
431         spin_unlock_irqrestore(&scsi_nl_lock, flags);
432
433         return 0;
434 }
435 EXPORT_SYMBOL_GPL(scsi_nl_add_driver);
436
437
438 /**
439  * scsi_nl_remove_driver -
440  *    An driver is unregistering with the SCSI netlink messages
441  *
442  * @vendor_id:          The unique identification value for the driver.
443  **/
444 void
445 scsi_nl_remove_driver(u64 vendor_id)
446 {
447         struct scsi_nl_drvr *driver;
448         unsigned long flags;
449
450         spin_lock_irqsave(&scsi_nl_lock, flags);
451         if (scsi_nl_state & STATE_EHANDLER_BSY) {
452                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
453                 msleep(1);
454                 spin_lock_irqsave(&scsi_nl_lock, flags);
455         }
456
457         list_for_each_entry(driver, &scsi_nl_drivers, next) {
458                 if (driver->vendor_id == vendor_id) {
459                         driver->flags |= HANDLER_DELETING;
460                         while (driver->refcnt != 0) {
461                                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
462                                 schedule_timeout_uninterruptible(HZ/4);
463                                 spin_lock_irqsave(&scsi_nl_lock, flags);
464                         }
465                         list_del(&driver->next);
466                         kfree(driver);
467                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
468                         return;
469                 }
470         }
471
472         spin_unlock_irqrestore(&scsi_nl_lock, flags);
473
474         printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
475                __func__, (unsigned long long)vendor_id);
476         return;
477 }
478 EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
479
480
481 /**
482  * scsi_netlink_init - Called by SCSI subsystem to intialize
483  *      the SCSI transport netlink interface
484  *
485  **/
486 void
487 scsi_netlink_init(void)
488 {
489         int error;
490
491         INIT_LIST_HEAD(&scsi_nl_drivers);
492
493         error = netlink_register_notifier(&scsi_netlink_notifier);
494         if (error) {
495                 printk(KERN_ERR "%s: register of event handler failed - %d\n",
496                                 __func__, error);
497                 return;
498         }
499
500         scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
501                                 SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
502                                 THIS_MODULE);
503         if (!scsi_nl_sock) {
504                 printk(KERN_ERR "%s: register of recieve handler failed\n",
505                                 __func__);
506                 netlink_unregister_notifier(&scsi_netlink_notifier);
507                 return;
508         }
509
510         /* Register the entry points for the generic SCSI transport */
511         error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
512                                 scsi_generic_msg_handler, NULL);
513         if (error)
514                 printk(KERN_ERR "%s: register of GENERIC transport handler"
515                                 "  failed - %d\n", __func__, error);
516         return;
517 }
518
519
520 /**
521  * scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
522  *
523  **/
524 void
525 scsi_netlink_exit(void)
526 {
527         scsi_nl_remove_transport(SCSI_NL_TRANSPORT);
528
529         if (scsi_nl_sock) {
530                 netlink_kernel_release(scsi_nl_sock);
531                 netlink_unregister_notifier(&scsi_netlink_notifier);
532         }
533
534         return;
535 }
536
537
538 /*
539  * Exported Interfaces
540  */
541
542 /**
543  * scsi_nl_send_transport_msg -
544  *    Generic function to send a single message from a SCSI transport to
545  *    a single process
546  *
547  * @pid:                receiving pid
548  * @hdr:                message payload
549  *
550  **/
551 void
552 scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
553 {
554         struct sk_buff *skb;
555         struct nlmsghdr *nlh;
556         const char *fn;
557         char *datab;
558         u32 len, skblen;
559         int err;
560
561         if (!scsi_nl_sock) {
562                 err = -ENOENT;
563                 fn = "netlink socket";
564                 goto msg_fail;
565         }
566
567         len = NLMSG_SPACE(hdr->msglen);
568         skblen = NLMSG_SPACE(len);
569
570         skb = alloc_skb(skblen, GFP_KERNEL);
571         if (!skb) {
572                 err = -ENOBUFS;
573                 fn = "alloc_skb";
574                 goto msg_fail;
575         }
576
577         nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
578         if (!nlh) {
579                 err = -ENOBUFS;
580                 fn = "nlmsg_put";
581                 goto msg_fail_skb;
582         }
583         datab = NLMSG_DATA(nlh);
584         memcpy(datab, hdr, hdr->msglen);
585
586         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
587         if (err < 0) {
588                 fn = "nlmsg_unicast";
589                 /* nlmsg_unicast already kfree_skb'd */
590                 goto msg_fail;
591         }
592
593         return;
594
595 msg_fail_skb:
596         kfree_skb(skb);
597 msg_fail:
598         printk(KERN_WARNING
599                 "%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
600                 "msglen %d: %s : err %d\n",
601                 __func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
602                 fn, err);
603         return;
604 }
605 EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);
606
607
608 /**
609  * scsi_nl_send_vendor_msg - called to send a shost vendor unique message
610  *                      to a specific process id.
611  *
612  * @pid:                process id of the receiver
613  * @host_no:            host # sending the message
614  * @vendor_id:          unique identifier for the driver's vendor
615  * @data_len:           amount, in bytes, of vendor unique payload data
616  * @data_buf:           pointer to vendor unique data buffer
617  *
618  * Returns:
619  *   0 on succesful return
620  *   otherwise, failing error code
621  *
622  * Notes:
623  *      This routine assumes no locks are held on entry.
624  */
625 int
626 scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
627                          char *data_buf, u32 data_len)
628 {
629         struct sk_buff *skb;
630         struct nlmsghdr *nlh;
631         struct scsi_nl_host_vendor_msg *msg;
632         u32 len, skblen;
633         int err;
634
635         if (!scsi_nl_sock) {
636                 err = -ENOENT;
637                 goto send_vendor_fail;
638         }
639
640         len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
641         skblen = NLMSG_SPACE(len);
642
643         skb = alloc_skb(skblen, GFP_KERNEL);
644         if (!skb) {
645                 err = -ENOBUFS;
646                 goto send_vendor_fail;
647         }
648
649         nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
650                                 skblen - sizeof(*nlh), 0);
651         if (!nlh) {
652                 err = -ENOBUFS;
653                 goto send_vendor_fail_skb;
654         }
655         msg = NLMSG_DATA(nlh);
656
657         INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
658                                 SCSI_NL_SHOST_VENDOR, len);
659         msg->vendor_id = vendor_id;
660         msg->host_no = host_no;
661         msg->vmsg_datalen = data_len;   /* bytes */
662         memcpy(&msg[1], data_buf, data_len);
663
664         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
665         if (err)
666                 /* nlmsg_multicast already kfree_skb'd */
667                 goto send_vendor_fail;
668
669         return 0;
670
671 send_vendor_fail_skb:
672         kfree_skb(skb);
673 send_vendor_fail:
674         printk(KERN_WARNING
675                 "%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
676                 __func__, host_no, err);
677         return err;
678 }
679 EXPORT_SYMBOL(scsi_nl_send_vendor_msg);
680
681