nfsd4: separate session allocation and initialization
[pandora-kernel.git] / drivers / scsi / scsi_netlink.c
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 <linux/slab.h>
26 #include <linux/export.h>
27 #include <net/sock.h>
28 #include <net/netlink.h>
29
30 #include <scsi/scsi_netlink.h>
31 #include "scsi_priv.h"
32
33 struct sock *scsi_nl_sock = NULL;
34 EXPORT_SYMBOL_GPL(scsi_nl_sock);
35
36 static DEFINE_SPINLOCK(scsi_nl_lock);
37 static struct list_head scsi_nl_drivers;
38
39 static u32      scsi_nl_state;
40 #define STATE_EHANDLER_BSY              0x00000001
41
42 struct scsi_nl_transport {
43         int (*msg_handler)(struct sk_buff *);
44         void (*event_handler)(struct notifier_block *, unsigned long, void *);
45         unsigned int refcnt;
46         int flags;
47 };
48
49 /* flags values (bit flags) */
50 #define HANDLER_DELETING                0x1
51
52 static struct scsi_nl_transport transports[SCSI_NL_MAX_TRANSPORTS] =
53         { {NULL, }, };
54
55
56 struct scsi_nl_drvr {
57         struct list_head next;
58         int (*dmsg_handler)(struct Scsi_Host *shost, void *payload,
59                                  u32 len, u32 pid);
60         void (*devt_handler)(struct notifier_block *nb,
61                                  unsigned long event, void *notify_ptr);
62         struct scsi_host_template *hostt;
63         u64 vendor_id;
64         unsigned int refcnt;
65         int flags;
66 };
67
68
69
70 /**
71  * scsi_nl_rcv_msg - Receive message handler.
72  * @skb:                socket receive buffer
73  *
74  * Description: Extracts message from a receive buffer.
75  *    Validates message header and calls appropriate transport message handler
76  *
77  *
78  **/
79 static void
80 scsi_nl_rcv_msg(struct sk_buff *skb)
81 {
82         struct nlmsghdr *nlh;
83         struct scsi_nl_hdr *hdr;
84         unsigned long flags;
85         u32 rlen;
86         int err, tport;
87
88         while (skb->len >= NLMSG_SPACE(0)) {
89                 err = 0;
90
91                 nlh = nlmsg_hdr(skb);
92                 if ((nlh->nlmsg_len < (sizeof(*nlh) + sizeof(*hdr))) ||
93                     (skb->len < nlh->nlmsg_len)) {
94                         printk(KERN_WARNING "%s: discarding partial skb\n",
95                                  __func__);
96                         return;
97                 }
98
99                 rlen = NLMSG_ALIGN(nlh->nlmsg_len);
100                 if (rlen > skb->len)
101                         rlen = skb->len;
102
103                 if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
104                         err = -EBADMSG;
105                         goto next_msg;
106                 }
107
108                 hdr = NLMSG_DATA(nlh);
109                 if ((hdr->version != SCSI_NL_VERSION) ||
110                     (hdr->magic != SCSI_NL_MAGIC)) {
111                         err = -EPROTOTYPE;
112                         goto next_msg;
113                 }
114
115                 if (!capable(CAP_SYS_ADMIN)) {
116                         err = -EPERM;
117                         goto next_msg;
118                 }
119
120                 if (nlh->nlmsg_len < (sizeof(*nlh) + hdr->msglen)) {
121                         printk(KERN_WARNING "%s: discarding partial message\n",
122                                  __func__);
123                         goto next_msg;
124                 }
125
126                 /*
127                  * Deliver message to the appropriate transport
128                  */
129                 spin_lock_irqsave(&scsi_nl_lock, flags);
130
131                 tport = hdr->transport;
132                 if ((tport < SCSI_NL_MAX_TRANSPORTS) &&
133                     !(transports[tport].flags & HANDLER_DELETING) &&
134                     (transports[tport].msg_handler)) {
135                         transports[tport].refcnt++;
136                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
137                         err = transports[tport].msg_handler(skb);
138                         spin_lock_irqsave(&scsi_nl_lock, flags);
139                         transports[tport].refcnt--;
140                 } else
141                         err = -ENOENT;
142
143                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
144
145 next_msg:
146                 if ((err) || (nlh->nlmsg_flags & NLM_F_ACK))
147                         netlink_ack(skb, nlh, err);
148
149                 skb_pull(skb, rlen);
150         }
151 }
152
153
154 /**
155  * scsi_nl_rcv_event - Event handler for a netlink socket.
156  * @this:               event notifier block
157  * @event:              event type
158  * @ptr:                event payload
159  *
160  **/
161 static int
162 scsi_nl_rcv_event(struct notifier_block *this, unsigned long event, void *ptr)
163 {
164         struct netlink_notify *n = ptr;
165         struct scsi_nl_drvr *driver;
166         unsigned long flags;
167         int tport;
168
169         if (n->protocol != NETLINK_SCSITRANSPORT)
170                 return NOTIFY_DONE;
171
172         spin_lock_irqsave(&scsi_nl_lock, flags);
173         scsi_nl_state |= STATE_EHANDLER_BSY;
174
175         /*
176          * Pass event on to any transports that may be listening
177          */
178         for (tport = 0; tport < SCSI_NL_MAX_TRANSPORTS; tport++) {
179                 if (!(transports[tport].flags & HANDLER_DELETING) &&
180                     (transports[tport].event_handler)) {
181                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
182                         transports[tport].event_handler(this, event, ptr);
183                         spin_lock_irqsave(&scsi_nl_lock, flags);
184                 }
185         }
186
187         /*
188          * Pass event on to any drivers that may be listening
189          */
190         list_for_each_entry(driver, &scsi_nl_drivers, next) {
191                 if (!(driver->flags & HANDLER_DELETING) &&
192                     (driver->devt_handler)) {
193                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
194                         driver->devt_handler(this, event, ptr);
195                         spin_lock_irqsave(&scsi_nl_lock, flags);
196                 }
197         }
198
199         scsi_nl_state &= ~STATE_EHANDLER_BSY;
200         spin_unlock_irqrestore(&scsi_nl_lock, flags);
201
202         return NOTIFY_DONE;
203 }
204
205 static struct notifier_block scsi_netlink_notifier = {
206         .notifier_call  = scsi_nl_rcv_event,
207 };
208
209
210 /*
211  * GENERIC SCSI transport receive and event handlers
212  */
213
214 /**
215  * scsi_generic_msg_handler - receive message handler for GENERIC transport messages
216  * @skb:                socket receive buffer
217  **/
218 static int
219 scsi_generic_msg_handler(struct sk_buff *skb)
220 {
221         struct nlmsghdr *nlh = nlmsg_hdr(skb);
222         struct scsi_nl_hdr *snlh = NLMSG_DATA(nlh);
223         struct scsi_nl_drvr *driver;
224         struct Scsi_Host *shost;
225         unsigned long flags;
226         int err = 0, match, pid;
227
228         pid = NETLINK_CREDS(skb)->pid;
229
230         switch (snlh->msgtype) {
231         case SCSI_NL_SHOST_VENDOR:
232                 {
233                 struct scsi_nl_host_vendor_msg *msg = NLMSG_DATA(nlh);
234
235                 /* Locate the driver that corresponds to the message */
236                 spin_lock_irqsave(&scsi_nl_lock, flags);
237                 match = 0;
238                 list_for_each_entry(driver, &scsi_nl_drivers, next) {
239                         if (driver->vendor_id == msg->vendor_id) {
240                                 match = 1;
241                                 break;
242                         }
243                 }
244
245                 if ((!match) || (!driver->dmsg_handler)) {
246                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
247                         err = -ESRCH;
248                         goto rcv_exit;
249                 }
250
251                 if (driver->flags & HANDLER_DELETING) {
252                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
253                         err = -ESHUTDOWN;
254                         goto rcv_exit;
255                 }
256
257                 driver->refcnt++;
258                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
259
260
261                 /* if successful, scsi_host_lookup takes a shost reference */
262                 shost = scsi_host_lookup(msg->host_no);
263                 if (!shost) {
264                         err = -ENODEV;
265                         goto driver_exit;
266                 }
267
268                 /* is this host owned by the vendor ? */
269                 if (shost->hostt != driver->hostt) {
270                         err = -EINVAL;
271                         goto vendormsg_put;
272                 }
273
274                 /* pass message on to the driver */
275                 err = driver->dmsg_handler(shost, (void *)&msg[1],
276                                          msg->vmsg_datalen, pid);
277
278 vendormsg_put:
279                 /* release reference by scsi_host_lookup */
280                 scsi_host_put(shost);
281
282 driver_exit:
283                 /* release our own reference on the registration object */
284                 spin_lock_irqsave(&scsi_nl_lock, flags);
285                 driver->refcnt--;
286                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
287                 break;
288                 }
289
290         default:
291                 err = -EBADR;
292                 break;
293         }
294
295 rcv_exit:
296         if (err)
297                 printk(KERN_WARNING "%s: Msgtype %d failed - err %d\n",
298                          __func__, snlh->msgtype, err);
299         return err;
300 }
301
302
303 /**
304  * scsi_nl_add_transport -
305  *    Registers message and event handlers for a transport. Enables
306  *    receipt of netlink messages and events to a transport.
307  *
308  * @tport:              transport registering handlers
309  * @msg_handler:        receive message handler callback
310  * @event_handler:      receive event handler callback
311  **/
312 int
313 scsi_nl_add_transport(u8 tport,
314         int (*msg_handler)(struct sk_buff *),
315         void (*event_handler)(struct notifier_block *, unsigned long, void *))
316 {
317         unsigned long flags;
318         int err = 0;
319
320         if (tport >= SCSI_NL_MAX_TRANSPORTS)
321                 return -EINVAL;
322
323         spin_lock_irqsave(&scsi_nl_lock, flags);
324
325         if (scsi_nl_state & STATE_EHANDLER_BSY) {
326                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
327                 msleep(1);
328                 spin_lock_irqsave(&scsi_nl_lock, flags);
329         }
330
331         if (transports[tport].msg_handler || transports[tport].event_handler) {
332                 err = -EALREADY;
333                 goto register_out;
334         }
335
336         transports[tport].msg_handler = msg_handler;
337         transports[tport].event_handler = event_handler;
338         transports[tport].flags = 0;
339         transports[tport].refcnt = 0;
340
341 register_out:
342         spin_unlock_irqrestore(&scsi_nl_lock, flags);
343
344         return err;
345 }
346 EXPORT_SYMBOL_GPL(scsi_nl_add_transport);
347
348
349 /**
350  * scsi_nl_remove_transport -
351  *    Disable transport receiption of messages and events
352  *
353  * @tport:              transport deregistering handlers
354  *
355  **/
356 void
357 scsi_nl_remove_transport(u8 tport)
358 {
359         unsigned long flags;
360
361         spin_lock_irqsave(&scsi_nl_lock, flags);
362         if (scsi_nl_state & STATE_EHANDLER_BSY) {
363                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
364                 msleep(1);
365                 spin_lock_irqsave(&scsi_nl_lock, flags);
366         }
367
368         if (tport < SCSI_NL_MAX_TRANSPORTS) {
369                 transports[tport].flags |= HANDLER_DELETING;
370
371                 while (transports[tport].refcnt != 0) {
372                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
373                         schedule_timeout_uninterruptible(HZ/4);
374                         spin_lock_irqsave(&scsi_nl_lock, flags);
375                 }
376                 transports[tport].msg_handler = NULL;
377                 transports[tport].event_handler = NULL;
378                 transports[tport].flags = 0;
379         }
380
381         spin_unlock_irqrestore(&scsi_nl_lock, flags);
382
383         return;
384 }
385 EXPORT_SYMBOL_GPL(scsi_nl_remove_transport);
386
387
388 /**
389  * scsi_nl_add_driver -
390  *    A driver is registering its interfaces for SCSI netlink messages
391  *
392  * @vendor_id:          A unique identification value for the driver.
393  * @hostt:              address of the driver's host template. Used
394  *                      to verify an shost is bound to the driver
395  * @nlmsg_handler:      receive message handler callback
396  * @nlevt_handler:      receive event handler callback
397  *
398  * Returns:
399  *   0 on Success
400  *   error result otherwise
401  **/
402 int
403 scsi_nl_add_driver(u64 vendor_id, struct scsi_host_template *hostt,
404         int (*nlmsg_handler)(struct Scsi_Host *shost, void *payload,
405                                  u32 len, u32 pid),
406         void (*nlevt_handler)(struct notifier_block *nb,
407                                  unsigned long event, void *notify_ptr))
408 {
409         struct scsi_nl_drvr *driver;
410         unsigned long flags;
411
412         driver = kzalloc(sizeof(*driver), GFP_KERNEL);
413         if (unlikely(!driver)) {
414                 printk(KERN_ERR "%s: allocation failure\n", __func__);
415                 return -ENOMEM;
416         }
417
418         driver->dmsg_handler = nlmsg_handler;
419         driver->devt_handler = nlevt_handler;
420         driver->hostt = hostt;
421         driver->vendor_id = vendor_id;
422
423         spin_lock_irqsave(&scsi_nl_lock, flags);
424         if (scsi_nl_state & STATE_EHANDLER_BSY) {
425                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
426                 msleep(1);
427                 spin_lock_irqsave(&scsi_nl_lock, flags);
428         }
429         list_add_tail(&driver->next, &scsi_nl_drivers);
430         spin_unlock_irqrestore(&scsi_nl_lock, flags);
431
432         return 0;
433 }
434 EXPORT_SYMBOL_GPL(scsi_nl_add_driver);
435
436
437 /**
438  * scsi_nl_remove_driver -
439  *    An driver is unregistering with the SCSI netlink messages
440  *
441  * @vendor_id:          The unique identification value for the driver.
442  **/
443 void
444 scsi_nl_remove_driver(u64 vendor_id)
445 {
446         struct scsi_nl_drvr *driver;
447         unsigned long flags;
448
449         spin_lock_irqsave(&scsi_nl_lock, flags);
450         if (scsi_nl_state & STATE_EHANDLER_BSY) {
451                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
452                 msleep(1);
453                 spin_lock_irqsave(&scsi_nl_lock, flags);
454         }
455
456         list_for_each_entry(driver, &scsi_nl_drivers, next) {
457                 if (driver->vendor_id == vendor_id) {
458                         driver->flags |= HANDLER_DELETING;
459                         while (driver->refcnt != 0) {
460                                 spin_unlock_irqrestore(&scsi_nl_lock, flags);
461                                 schedule_timeout_uninterruptible(HZ/4);
462                                 spin_lock_irqsave(&scsi_nl_lock, flags);
463                         }
464                         list_del(&driver->next);
465                         kfree(driver);
466                         spin_unlock_irqrestore(&scsi_nl_lock, flags);
467                         return;
468                 }
469         }
470
471         spin_unlock_irqrestore(&scsi_nl_lock, flags);
472
473         printk(KERN_ERR "%s: removal of driver failed - vendor_id 0x%llx\n",
474                __func__, (unsigned long long)vendor_id);
475         return;
476 }
477 EXPORT_SYMBOL_GPL(scsi_nl_remove_driver);
478
479
480 /**
481  * scsi_netlink_init - Called by SCSI subsystem to initialize
482  *      the SCSI transport netlink interface
483  *
484  **/
485 void
486 scsi_netlink_init(void)
487 {
488         int error;
489         struct netlink_kernel_cfg cfg = {
490                 .input  = scsi_nl_rcv_msg,
491                 .groups = SCSI_NL_GRP_CNT,
492         };
493
494         INIT_LIST_HEAD(&scsi_nl_drivers);
495
496         error = netlink_register_notifier(&scsi_netlink_notifier);
497         if (error) {
498                 printk(KERN_ERR "%s: register of event handler failed - %d\n",
499                                 __func__, error);
500                 return;
501         }
502
503         scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
504                                              THIS_MODULE, &cfg);
505         if (!scsi_nl_sock) {
506                 printk(KERN_ERR "%s: register of receive handler failed\n",
507                                 __func__);
508                 netlink_unregister_notifier(&scsi_netlink_notifier);
509                 return;
510         }
511
512         /* Register the entry points for the generic SCSI transport */
513         error = scsi_nl_add_transport(SCSI_NL_TRANSPORT,
514                                 scsi_generic_msg_handler, NULL);
515         if (error)
516                 printk(KERN_ERR "%s: register of GENERIC transport handler"
517                                 "  failed - %d\n", __func__, error);
518         return;
519 }
520
521
522 /**
523  * scsi_netlink_exit - Called by SCSI subsystem to disable the SCSI transport netlink interface
524  *
525  **/
526 void
527 scsi_netlink_exit(void)
528 {
529         scsi_nl_remove_transport(SCSI_NL_TRANSPORT);
530
531         if (scsi_nl_sock) {
532                 netlink_kernel_release(scsi_nl_sock);
533                 netlink_unregister_notifier(&scsi_netlink_notifier);
534         }
535
536         return;
537 }
538
539
540 /*
541  * Exported Interfaces
542  */
543
544 /**
545  * scsi_nl_send_transport_msg -
546  *    Generic function to send a single message from a SCSI transport to
547  *    a single process
548  *
549  * @pid:                receiving pid
550  * @hdr:                message payload
551  *
552  **/
553 void
554 scsi_nl_send_transport_msg(u32 pid, struct scsi_nl_hdr *hdr)
555 {
556         struct sk_buff *skb;
557         struct nlmsghdr *nlh;
558         const char *fn;
559         char *datab;
560         u32 len, skblen;
561         int err;
562
563         if (!scsi_nl_sock) {
564                 err = -ENOENT;
565                 fn = "netlink socket";
566                 goto msg_fail;
567         }
568
569         len = NLMSG_SPACE(hdr->msglen);
570         skblen = NLMSG_SPACE(len);
571
572         skb = alloc_skb(skblen, GFP_KERNEL);
573         if (!skb) {
574                 err = -ENOBUFS;
575                 fn = "alloc_skb";
576                 goto msg_fail;
577         }
578
579         nlh = nlmsg_put(skb, pid, 0, SCSI_TRANSPORT_MSG, len - sizeof(*nlh), 0);
580         if (!nlh) {
581                 err = -ENOBUFS;
582                 fn = "nlmsg_put";
583                 goto msg_fail_skb;
584         }
585         datab = NLMSG_DATA(nlh);
586         memcpy(datab, hdr, hdr->msglen);
587
588         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
589         if (err < 0) {
590                 fn = "nlmsg_unicast";
591                 /* nlmsg_unicast already kfree_skb'd */
592                 goto msg_fail;
593         }
594
595         return;
596
597 msg_fail_skb:
598         kfree_skb(skb);
599 msg_fail:
600         printk(KERN_WARNING
601                 "%s: Dropped Message : pid %d Transport %d, msgtype x%x, "
602                 "msglen %d: %s : err %d\n",
603                 __func__, pid, hdr->transport, hdr->msgtype, hdr->msglen,
604                 fn, err);
605         return;
606 }
607 EXPORT_SYMBOL_GPL(scsi_nl_send_transport_msg);
608
609
610 /**
611  * scsi_nl_send_vendor_msg - called to send a shost vendor unique message
612  *                      to a specific process id.
613  *
614  * @pid:                process id of the receiver
615  * @host_no:            host # sending the message
616  * @vendor_id:          unique identifier for the driver's vendor
617  * @data_len:           amount, in bytes, of vendor unique payload data
618  * @data_buf:           pointer to vendor unique data buffer
619  *
620  * Returns:
621  *   0 on successful return
622  *   otherwise, failing error code
623  *
624  * Notes:
625  *      This routine assumes no locks are held on entry.
626  */
627 int
628 scsi_nl_send_vendor_msg(u32 pid, unsigned short host_no, u64 vendor_id,
629                          char *data_buf, u32 data_len)
630 {
631         struct sk_buff *skb;
632         struct nlmsghdr *nlh;
633         struct scsi_nl_host_vendor_msg *msg;
634         u32 len, skblen;
635         int err;
636
637         if (!scsi_nl_sock) {
638                 err = -ENOENT;
639                 goto send_vendor_fail;
640         }
641
642         len = SCSI_NL_MSGALIGN(sizeof(*msg) + data_len);
643         skblen = NLMSG_SPACE(len);
644
645         skb = alloc_skb(skblen, GFP_KERNEL);
646         if (!skb) {
647                 err = -ENOBUFS;
648                 goto send_vendor_fail;
649         }
650
651         nlh = nlmsg_put(skb, 0, 0, SCSI_TRANSPORT_MSG,
652                                 skblen - sizeof(*nlh), 0);
653         if (!nlh) {
654                 err = -ENOBUFS;
655                 goto send_vendor_fail_skb;
656         }
657         msg = NLMSG_DATA(nlh);
658
659         INIT_SCSI_NL_HDR(&msg->snlh, SCSI_NL_TRANSPORT,
660                                 SCSI_NL_SHOST_VENDOR, len);
661         msg->vendor_id = vendor_id;
662         msg->host_no = host_no;
663         msg->vmsg_datalen = data_len;   /* bytes */
664         memcpy(&msg[1], data_buf, data_len);
665
666         err = nlmsg_unicast(scsi_nl_sock, skb, pid);
667         if (err)
668                 /* nlmsg_multicast already kfree_skb'd */
669                 goto send_vendor_fail;
670
671         return 0;
672
673 send_vendor_fail_skb:
674         kfree_skb(skb);
675 send_vendor_fail:
676         printk(KERN_WARNING
677                 "%s: Dropped SCSI Msg : host %d vendor_unique - err %d\n",
678                 __func__, host_no, err);
679         return err;
680 }
681 EXPORT_SYMBOL(scsi_nl_send_vendor_msg);
682
683