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Linux/ipc/util.c

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  1 /*
  2  * linux/ipc/util.c
  3  * Copyright (C) 1992 Krishna Balasubramanian
  4  *
  5  * Sep 1997 - Call suser() last after "normal" permission checks so we
  6  *            get BSD style process accounting right.
  7  *            Occurs in several places in the IPC code.
  8  *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
  9  * Nov 1999 - ipc helper functions, unified SMP locking
 10  *            Manfred Spraul <manfred@colorfullife.com>
 11  * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
 12  *            Mingming Cao <cmm@us.ibm.com>
 13  * Mar 2006 - support for audit of ipc object properties
 14  *            Dustin Kirkland <dustin.kirkland@us.ibm.com>
 15  * Jun 2006 - namespaces ssupport
 16  *            OpenVZ, SWsoft Inc.
 17  *            Pavel Emelianov <xemul@openvz.org>
 18  */
 19 
 20 #include <linux/mm.h>
 21 #include <linux/shm.h>
 22 #include <linux/init.h>
 23 #include <linux/msg.h>
 24 #include <linux/vmalloc.h>
 25 #include <linux/slab.h>
 26 #include <linux/capability.h>
 27 #include <linux/highuid.h>
 28 #include <linux/security.h>
 29 #include <linux/rcupdate.h>
 30 #include <linux/workqueue.h>
 31 #include <linux/seq_file.h>
 32 #include <linux/proc_fs.h>
 33 #include <linux/audit.h>
 34 #include <linux/nsproxy.h>
 35 #include <linux/rwsem.h>
 36 #include <linux/memory.h>
 37 #include <linux/ipc_namespace.h>
 38 
 39 #include <asm/unistd.h>
 40 
 41 #include "util.h"
 42 
 43 struct ipc_proc_iface {
 44         const char *path;
 45         const char *header;
 46         int ids;
 47         int (*show)(struct seq_file *, void *);
 48 };
 49 
 50 #ifdef CONFIG_MEMORY_HOTPLUG
 51 
 52 static void ipc_memory_notifier(struct work_struct *work)
 53 {
 54         ipcns_notify(IPCNS_MEMCHANGED);
 55 }
 56 
 57 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
 58 
 59 
 60 static int ipc_memory_callback(struct notifier_block *self,
 61                                 unsigned long action, void *arg)
 62 {
 63         switch (action) {
 64         case MEM_ONLINE:    /* memory successfully brought online */
 65         case MEM_OFFLINE:   /* or offline: it's time to recompute msgmni */
 66                 /*
 67                  * This is done by invoking the ipcns notifier chain with the
 68                  * IPC_MEMCHANGED event.
 69                  * In order not to keep the lock on the hotplug memory chain
 70                  * for too long, queue a work item that will, when waken up,
 71                  * activate the ipcns notification chain.
 72                  * No need to keep several ipc work items on the queue.
 73                  */
 74                 if (!work_pending(&ipc_memory_wq))
 75                         schedule_work(&ipc_memory_wq);
 76                 break;
 77         case MEM_GOING_ONLINE:
 78         case MEM_GOING_OFFLINE:
 79         case MEM_CANCEL_ONLINE:
 80         case MEM_CANCEL_OFFLINE:
 81         default:
 82                 break;
 83         }
 84 
 85         return NOTIFY_OK;
 86 }
 87 
 88 #endif /* CONFIG_MEMORY_HOTPLUG */
 89 
 90 /**
 91  *      ipc_init        -       initialise IPC subsystem
 92  *
 93  *      The various system5 IPC resources (semaphores, messages and shared
 94  *      memory) are initialised
 95  *      A callback routine is registered into the memory hotplug notifier
 96  *      chain: since msgmni scales to lowmem this callback routine will be
 97  *      called upon successful memory add / remove to recompute msmgni.
 98  */
 99  
100 static int __init ipc_init(void)
101 {
102         sem_init();
103         msg_init();
104         shm_init();
105         hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
106         register_ipcns_notifier(&init_ipc_ns);
107         return 0;
108 }
109 __initcall(ipc_init);
110 
111 /**
112  *      ipc_init_ids            -       initialise IPC identifiers
113  *      @ids: Identifier set
114  *
115  *      Set up the sequence range to use for the ipc identifier range (limited
116  *      below IPCMNI) then initialise the ids idr.
117  */
118  
119 void ipc_init_ids(struct ipc_ids *ids)
120 {
121         init_rwsem(&ids->rw_mutex);
122 
123         ids->in_use = 0;
124         ids->seq = 0;
125         {
126                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
127                 if (seq_limit > USHRT_MAX)
128                         ids->seq_max = USHRT_MAX;
129                  else
130                         ids->seq_max = seq_limit;
131         }
132 
133         idr_init(&ids->ipcs_idr);
134 }
135 
136 #ifdef CONFIG_PROC_FS
137 static const struct file_operations sysvipc_proc_fops;
138 /**
139  *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
140  *      @path: Path in procfs
141  *      @header: Banner to be printed at the beginning of the file.
142  *      @ids: ipc id table to iterate.
143  *      @show: show routine.
144  */
145 void __init ipc_init_proc_interface(const char *path, const char *header,
146                 int ids, int (*show)(struct seq_file *, void *))
147 {
148         struct proc_dir_entry *pde;
149         struct ipc_proc_iface *iface;
150 
151         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
152         if (!iface)
153                 return;
154         iface->path     = path;
155         iface->header   = header;
156         iface->ids      = ids;
157         iface->show     = show;
158 
159         pde = proc_create_data(path,
160                                S_IRUGO,        /* world readable */
161                                NULL,           /* parent dir */
162                                &sysvipc_proc_fops,
163                                iface);
164         if (!pde) {
165                 kfree(iface);
166         }
167 }
168 #endif
169 
170 /**
171  *      ipc_findkey     -       find a key in an ipc identifier set     
172  *      @ids: Identifier set
173  *      @key: The key to find
174  *      
175  *      Requires ipc_ids.rw_mutex locked.
176  *      Returns the LOCKED pointer to the ipc structure if found or NULL
177  *      if not.
178  *      If key is found ipc points to the owning ipc structure
179  */
180  
181 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
182 {
183         struct kern_ipc_perm *ipc;
184         int next_id;
185         int total;
186 
187         for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
188                 ipc = idr_find(&ids->ipcs_idr, next_id);
189 
190                 if (ipc == NULL)
191                         continue;
192 
193                 if (ipc->key != key) {
194                         total++;
195                         continue;
196                 }
197 
198                 ipc_lock_by_ptr(ipc);
199                 return ipc;
200         }
201 
202         return NULL;
203 }
204 
205 /**
206  *      ipc_get_maxid   -       get the last assigned id
207  *      @ids: IPC identifier set
208  *
209  *      Called with ipc_ids.rw_mutex held.
210  */
211 
212 int ipc_get_maxid(struct ipc_ids *ids)
213 {
214         struct kern_ipc_perm *ipc;
215         int max_id = -1;
216         int total, id;
217 
218         if (ids->in_use == 0)
219                 return -1;
220 
221         if (ids->in_use == IPCMNI)
222                 return IPCMNI - 1;
223 
224         /* Look for the last assigned id */
225         total = 0;
226         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
227                 ipc = idr_find(&ids->ipcs_idr, id);
228                 if (ipc != NULL) {
229                         max_id = id;
230                         total++;
231                 }
232         }
233         return max_id;
234 }
235 
236 /**
237  *      ipc_addid       -       add an IPC identifier
238  *      @ids: IPC identifier set
239  *      @new: new IPC permission set
240  *      @size: limit for the number of used ids
241  *
242  *      Add an entry 'new' to the IPC ids idr. The permissions object is
243  *      initialised and the first free entry is set up and the id assigned
244  *      is returned. The 'new' entry is returned in a locked state on success.
245  *      On failure the entry is not locked and a negative err-code is returned.
246  *
247  *      Called with ipc_ids.rw_mutex held as a writer.
248  */
249  
250 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
251 {
252         kuid_t euid;
253         kgid_t egid;
254         int id, err;
255 
256         if (size > IPCMNI)
257                 size = IPCMNI;
258 
259         if (ids->in_use >= size)
260                 return -ENOSPC;
261 
262         spin_lock_init(&new->lock);
263         new->deleted = 0;
264         rcu_read_lock();
265         spin_lock(&new->lock);
266 
267         err = idr_get_new(&ids->ipcs_idr, new, &id);
268         if (err) {
269                 spin_unlock(&new->lock);
270                 rcu_read_unlock();
271                 return err;
272         }
273 
274         ids->in_use++;
275 
276         current_euid_egid(&euid, &egid);
277         new->cuid = new->uid = euid;
278         new->gid = new->cgid = egid;
279 
280         new->seq = ids->seq++;
281         if(ids->seq > ids->seq_max)
282                 ids->seq = 0;
283 
284         new->id = ipc_buildid(id, new->seq);
285         return id;
286 }
287 
288 /**
289  *      ipcget_new      -       create a new ipc object
290  *      @ns: namespace
291  *      @ids: IPC identifer set
292  *      @ops: the actual creation routine to call
293  *      @params: its parameters
294  *
295  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
296  *      when the key is IPC_PRIVATE.
297  */
298 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
299                 struct ipc_ops *ops, struct ipc_params *params)
300 {
301         int err;
302 retry:
303         err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
304 
305         if (!err)
306                 return -ENOMEM;
307 
308         down_write(&ids->rw_mutex);
309         err = ops->getnew(ns, params);
310         up_write(&ids->rw_mutex);
311 
312         if (err == -EAGAIN)
313                 goto retry;
314 
315         return err;
316 }
317 
318 /**
319  *      ipc_check_perms -       check security and permissions for an IPC
320  *      @ns: IPC namespace
321  *      @ipcp: ipc permission set
322  *      @ops: the actual security routine to call
323  *      @params: its parameters
324  *
325  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
326  *      when the key is not IPC_PRIVATE and that key already exists in the
327  *      ids IDR.
328  *
329  *      On success, the IPC id is returned.
330  *
331  *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
332  */
333 static int ipc_check_perms(struct ipc_namespace *ns,
334                            struct kern_ipc_perm *ipcp,
335                            struct ipc_ops *ops,
336                            struct ipc_params *params)
337 {
338         int err;
339 
340         if (ipcperms(ns, ipcp, params->flg))
341                 err = -EACCES;
342         else {
343                 err = ops->associate(ipcp, params->flg);
344                 if (!err)
345                         err = ipcp->id;
346         }
347 
348         return err;
349 }
350 
351 /**
352  *      ipcget_public   -       get an ipc object or create a new one
353  *      @ns: namespace
354  *      @ids: IPC identifer set
355  *      @ops: the actual creation routine to call
356  *      @params: its parameters
357  *
358  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
359  *      when the key is not IPC_PRIVATE.
360  *      It adds a new entry if the key is not found and does some permission
361  *      / security checkings if the key is found.
362  *
363  *      On success, the ipc id is returned.
364  */
365 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
366                 struct ipc_ops *ops, struct ipc_params *params)
367 {
368         struct kern_ipc_perm *ipcp;
369         int flg = params->flg;
370         int err;
371 retry:
372         err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
373 
374         /*
375          * Take the lock as a writer since we are potentially going to add
376          * a new entry + read locks are not "upgradable"
377          */
378         down_write(&ids->rw_mutex);
379         ipcp = ipc_findkey(ids, params->key);
380         if (ipcp == NULL) {
381                 /* key not used */
382                 if (!(flg & IPC_CREAT))
383                         err = -ENOENT;
384                 else if (!err)
385                         err = -ENOMEM;
386                 else
387                         err = ops->getnew(ns, params);
388         } else {
389                 /* ipc object has been locked by ipc_findkey() */
390 
391                 if (flg & IPC_CREAT && flg & IPC_EXCL)
392                         err = -EEXIST;
393                 else {
394                         err = 0;
395                         if (ops->more_checks)
396                                 err = ops->more_checks(ipcp, params);
397                         if (!err)
398                                 /*
399                                  * ipc_check_perms returns the IPC id on
400                                  * success
401                                  */
402                                 err = ipc_check_perms(ns, ipcp, ops, params);
403                 }
404                 ipc_unlock(ipcp);
405         }
406         up_write(&ids->rw_mutex);
407 
408         if (err == -EAGAIN)
409                 goto retry;
410 
411         return err;
412 }
413 
414 
415 /**
416  *      ipc_rmid        -       remove an IPC identifier
417  *      @ids: IPC identifier set
418  *      @ipcp: ipc perm structure containing the identifier to remove
419  *
420  *      ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
421  *      before this function is called, and remain locked on the exit.
422  */
423  
424 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
425 {
426         int lid = ipcid_to_idx(ipcp->id);
427 
428         idr_remove(&ids->ipcs_idr, lid);
429 
430         ids->in_use--;
431 
432         ipcp->deleted = 1;
433 
434         return;
435 }
436 
437 /**
438  *      ipc_alloc       -       allocate ipc space
439  *      @size: size desired
440  *
441  *      Allocate memory from the appropriate pools and return a pointer to it.
442  *      NULL is returned if the allocation fails
443  */
444  
445 void* ipc_alloc(int size)
446 {
447         void* out;
448         if(size > PAGE_SIZE)
449                 out = vmalloc(size);
450         else
451                 out = kmalloc(size, GFP_KERNEL);
452         return out;
453 }
454 
455 /**
456  *      ipc_free        -       free ipc space
457  *      @ptr: pointer returned by ipc_alloc
458  *      @size: size of block
459  *
460  *      Free a block created with ipc_alloc(). The caller must know the size
461  *      used in the allocation call.
462  */
463 
464 void ipc_free(void* ptr, int size)
465 {
466         if(size > PAGE_SIZE)
467                 vfree(ptr);
468         else
469                 kfree(ptr);
470 }
471 
472 /*
473  * rcu allocations:
474  * There are three headers that are prepended to the actual allocation:
475  * - during use: ipc_rcu_hdr.
476  * - during the rcu grace period: ipc_rcu_grace.
477  * - [only if vmalloc]: ipc_rcu_sched.
478  * Their lifetime doesn't overlap, thus the headers share the same memory.
479  * Unlike a normal union, they are right-aligned, thus some container_of
480  * forward/backward casting is necessary:
481  */
482 struct ipc_rcu_hdr
483 {
484         int refcount;
485         int is_vmalloc;
486         void *data[0];
487 };
488 
489 
490 struct ipc_rcu_grace
491 {
492         struct rcu_head rcu;
493         /* "void *" makes sure alignment of following data is sane. */
494         void *data[0];
495 };
496 
497 struct ipc_rcu_sched
498 {
499         struct work_struct work;
500         /* "void *" makes sure alignment of following data is sane. */
501         void *data[0];
502 };
503 
504 #define HDRLEN_KMALLOC          (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
505                                         sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
506 #define HDRLEN_VMALLOC          (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
507                                         sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
508 
509 static inline int rcu_use_vmalloc(int size)
510 {
511         /* Too big for a single page? */
512         if (HDRLEN_KMALLOC + size > PAGE_SIZE)
513                 return 1;
514         return 0;
515 }
516 
517 /**
518  *      ipc_rcu_alloc   -       allocate ipc and rcu space 
519  *      @size: size desired
520  *
521  *      Allocate memory for the rcu header structure +  the object.
522  *      Returns the pointer to the object.
523  *      NULL is returned if the allocation fails. 
524  */
525  
526 void* ipc_rcu_alloc(int size)
527 {
528         void* out;
529         /* 
530          * We prepend the allocation with the rcu struct, and
531          * workqueue if necessary (for vmalloc). 
532          */
533         if (rcu_use_vmalloc(size)) {
534                 out = vmalloc(HDRLEN_VMALLOC + size);
535                 if (out) {
536                         out += HDRLEN_VMALLOC;
537                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
538                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
539                 }
540         } else {
541                 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
542                 if (out) {
543                         out += HDRLEN_KMALLOC;
544                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
545                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
546                 }
547         }
548 
549         return out;
550 }
551 
552 void ipc_rcu_getref(void *ptr)
553 {
554         container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
555 }
556 
557 static void ipc_do_vfree(struct work_struct *work)
558 {
559         vfree(container_of(work, struct ipc_rcu_sched, work));
560 }
561 
562 /**
563  * ipc_schedule_free - free ipc + rcu space
564  * @head: RCU callback structure for queued work
565  * 
566  * Since RCU callback function is called in bh,
567  * we need to defer the vfree to schedule_work().
568  */
569 static void ipc_schedule_free(struct rcu_head *head)
570 {
571         struct ipc_rcu_grace *grace;
572         struct ipc_rcu_sched *sched;
573 
574         grace = container_of(head, struct ipc_rcu_grace, rcu);
575         sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
576                                 data[0]);
577 
578         INIT_WORK(&sched->work, ipc_do_vfree);
579         schedule_work(&sched->work);
580 }
581 
582 void ipc_rcu_putref(void *ptr)
583 {
584         if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
585                 return;
586 
587         if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
588                 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
589                                 ipc_schedule_free);
590         } else {
591                 kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu);
592         }
593 }
594 
595 /**
596  *      ipcperms        -       check IPC permissions
597  *      @ns: IPC namespace
598  *      @ipcp: IPC permission set
599  *      @flag: desired permission set.
600  *
601  *      Check user, group, other permissions for access
602  *      to ipc resources. return 0 if allowed
603  *
604  *      @flag will most probably be 0 or S_...UGO from <linux/stat.h>
605  */
606  
607 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
608 {
609         kuid_t euid = current_euid();
610         int requested_mode, granted_mode;
611 
612         audit_ipc_obj(ipcp);
613         requested_mode = (flag >> 6) | (flag >> 3) | flag;
614         granted_mode = ipcp->mode;
615         if (uid_eq(euid, ipcp->cuid) ||
616             uid_eq(euid, ipcp->uid))
617                 granted_mode >>= 6;
618         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
619                 granted_mode >>= 3;
620         /* is there some bit set in requested_mode but not in granted_mode? */
621         if ((requested_mode & ~granted_mode & 0007) && 
622             !ns_capable(ns->user_ns, CAP_IPC_OWNER))
623                 return -1;
624 
625         return security_ipc_permission(ipcp, flag);
626 }
627 
628 /*
629  * Functions to convert between the kern_ipc_perm structure and the
630  * old/new ipc_perm structures
631  */
632 
633 /**
634  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
635  *      @in: kernel permissions
636  *      @out: new style IPC permissions
637  *
638  *      Turn the kernel object @in into a set of permissions descriptions
639  *      for returning to userspace (@out).
640  */
641  
642 
643 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
644 {
645         out->key        = in->key;
646         out->uid        = from_kuid_munged(current_user_ns(), in->uid);
647         out->gid        = from_kgid_munged(current_user_ns(), in->gid);
648         out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
649         out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
650         out->mode       = in->mode;
651         out->seq        = in->seq;
652 }
653 
654 /**
655  *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
656  *      @in: new style IPC permissions
657  *      @out: old style IPC permissions
658  *
659  *      Turn the new style permissions object @in into a compatibility
660  *      object and store it into the @out pointer.
661  */
662  
663 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
664 {
665         out->key        = in->key;
666         SET_UID(out->uid, in->uid);
667         SET_GID(out->gid, in->gid);
668         SET_UID(out->cuid, in->cuid);
669         SET_GID(out->cgid, in->cgid);
670         out->mode       = in->mode;
671         out->seq        = in->seq;
672 }
673 
674 /**
675  * ipc_lock - Lock an ipc structure without rw_mutex held
676  * @ids: IPC identifier set
677  * @id: ipc id to look for
678  *
679  * Look for an id in the ipc ids idr and lock the associated ipc object.
680  *
681  * The ipc object is locked on exit.
682  */
683 
684 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
685 {
686         struct kern_ipc_perm *out;
687         int lid = ipcid_to_idx(id);
688 
689         rcu_read_lock();
690         out = idr_find(&ids->ipcs_idr, lid);
691         if (out == NULL) {
692                 rcu_read_unlock();
693                 return ERR_PTR(-EINVAL);
694         }
695 
696         spin_lock(&out->lock);
697         
698         /* ipc_rmid() may have already freed the ID while ipc_lock
699          * was spinning: here verify that the structure is still valid
700          */
701         if (out->deleted) {
702                 spin_unlock(&out->lock);
703                 rcu_read_unlock();
704                 return ERR_PTR(-EINVAL);
705         }
706 
707         return out;
708 }
709 
710 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
711 {
712         struct kern_ipc_perm *out;
713 
714         out = ipc_lock(ids, id);
715         if (IS_ERR(out))
716                 return out;
717 
718         if (ipc_checkid(out, id)) {
719                 ipc_unlock(out);
720                 return ERR_PTR(-EIDRM);
721         }
722 
723         return out;
724 }
725 
726 /**
727  * ipcget - Common sys_*get() code
728  * @ns : namsepace
729  * @ids : IPC identifier set
730  * @ops : operations to be called on ipc object creation, permission checks
731  *        and further checks
732  * @params : the parameters needed by the previous operations.
733  *
734  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
735  */
736 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
737                         struct ipc_ops *ops, struct ipc_params *params)
738 {
739         if (params->key == IPC_PRIVATE)
740                 return ipcget_new(ns, ids, ops, params);
741         else
742                 return ipcget_public(ns, ids, ops, params);
743 }
744 
745 /**
746  * ipc_update_perm - update the permissions of an IPC.
747  * @in:  the permission given as input.
748  * @out: the permission of the ipc to set.
749  */
750 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
751 {
752         kuid_t uid = make_kuid(current_user_ns(), in->uid);
753         kgid_t gid = make_kgid(current_user_ns(), in->gid);
754         if (!uid_valid(uid) || !gid_valid(gid))
755                 return -EINVAL;
756 
757         out->uid = uid;
758         out->gid = gid;
759         out->mode = (out->mode & ~S_IRWXUGO)
760                 | (in->mode & S_IRWXUGO);
761 
762         return 0;
763 }
764 
765 /**
766  * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
767  * @ns:  the ipc namespace
768  * @ids:  the table of ids where to look for the ipc
769  * @id:   the id of the ipc to retrieve
770  * @cmd:  the cmd to check
771  * @perm: the permission to set
772  * @extra_perm: one extra permission parameter used by msq
773  *
774  * This function does some common audit and permissions check for some IPC_XXX
775  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
776  * It must be called without any lock held and
777  *  - retrieves the ipc with the given id in the given table.
778  *  - performs some audit and permission check, depending on the given cmd
779  *  - returns the ipc with both ipc and rw_mutex locks held in case of success
780  *    or an err-code without any lock held otherwise.
781  */
782 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
783                                       struct ipc_ids *ids, int id, int cmd,
784                                       struct ipc64_perm *perm, int extra_perm)
785 {
786         struct kern_ipc_perm *ipcp;
787         kuid_t euid;
788         int err;
789 
790         down_write(&ids->rw_mutex);
791         ipcp = ipc_lock_check(ids, id);
792         if (IS_ERR(ipcp)) {
793                 err = PTR_ERR(ipcp);
794                 goto out_up;
795         }
796 
797         audit_ipc_obj(ipcp);
798         if (cmd == IPC_SET)
799                 audit_ipc_set_perm(extra_perm, perm->uid,
800                                          perm->gid, perm->mode);
801 
802         euid = current_euid();
803         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
804             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
805                 return ipcp;
806 
807         err = -EPERM;
808         ipc_unlock(ipcp);
809 out_up:
810         up_write(&ids->rw_mutex);
811         return ERR_PTR(err);
812 }
813 
814 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
815 
816 
817 /**
818  *      ipc_parse_version       -       IPC call version
819  *      @cmd: pointer to command
820  *
821  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 
822  *      The @cmd value is turned from an encoding command and version into
823  *      just the command code.
824  */
825  
826 int ipc_parse_version (int *cmd)
827 {
828         if (*cmd & IPC_64) {
829                 *cmd ^= IPC_64;
830                 return IPC_64;
831         } else {
832                 return IPC_OLD;
833         }
834 }
835 
836 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
837 
838 #ifdef CONFIG_PROC_FS
839 struct ipc_proc_iter {
840         struct ipc_namespace *ns;
841         struct ipc_proc_iface *iface;
842 };
843 
844 /*
845  * This routine locks the ipc structure found at least at position pos.
846  */
847 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
848                                               loff_t *new_pos)
849 {
850         struct kern_ipc_perm *ipc;
851         int total, id;
852 
853         total = 0;
854         for (id = 0; id < pos && total < ids->in_use; id++) {
855                 ipc = idr_find(&ids->ipcs_idr, id);
856                 if (ipc != NULL)
857                         total++;
858         }
859 
860         if (total >= ids->in_use)
861                 return NULL;
862 
863         for ( ; pos < IPCMNI; pos++) {
864                 ipc = idr_find(&ids->ipcs_idr, pos);
865                 if (ipc != NULL) {
866                         *new_pos = pos + 1;
867                         ipc_lock_by_ptr(ipc);
868                         return ipc;
869                 }
870         }
871 
872         /* Out of range - return NULL to terminate iteration */
873         return NULL;
874 }
875 
876 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
877 {
878         struct ipc_proc_iter *iter = s->private;
879         struct ipc_proc_iface *iface = iter->iface;
880         struct kern_ipc_perm *ipc = it;
881 
882         /* If we had an ipc id locked before, unlock it */
883         if (ipc && ipc != SEQ_START_TOKEN)
884                 ipc_unlock(ipc);
885 
886         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
887 }
888 
889 /*
890  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
891  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
892  */
893 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
894 {
895         struct ipc_proc_iter *iter = s->private;
896         struct ipc_proc_iface *iface = iter->iface;
897         struct ipc_ids *ids;
898 
899         ids = &iter->ns->ids[iface->ids];
900 
901         /*
902          * Take the lock - this will be released by the corresponding
903          * call to stop().
904          */
905         down_read(&ids->rw_mutex);
906 
907         /* pos < 0 is invalid */
908         if (*pos < 0)
909                 return NULL;
910 
911         /* pos == 0 means header */
912         if (*pos == 0)
913                 return SEQ_START_TOKEN;
914 
915         /* Find the (pos-1)th ipc */
916         return sysvipc_find_ipc(ids, *pos - 1, pos);
917 }
918 
919 static void sysvipc_proc_stop(struct seq_file *s, void *it)
920 {
921         struct kern_ipc_perm *ipc = it;
922         struct ipc_proc_iter *iter = s->private;
923         struct ipc_proc_iface *iface = iter->iface;
924         struct ipc_ids *ids;
925 
926         /* If we had a locked structure, release it */
927         if (ipc && ipc != SEQ_START_TOKEN)
928                 ipc_unlock(ipc);
929 
930         ids = &iter->ns->ids[iface->ids];
931         /* Release the lock we took in start() */
932         up_read(&ids->rw_mutex);
933 }
934 
935 static int sysvipc_proc_show(struct seq_file *s, void *it)
936 {
937         struct ipc_proc_iter *iter = s->private;
938         struct ipc_proc_iface *iface = iter->iface;
939 
940         if (it == SEQ_START_TOKEN)
941                 return seq_puts(s, iface->header);
942 
943         return iface->show(s, it);
944 }
945 
946 static const struct seq_operations sysvipc_proc_seqops = {
947         .start = sysvipc_proc_start,
948         .stop  = sysvipc_proc_stop,
949         .next  = sysvipc_proc_next,
950         .show  = sysvipc_proc_show,
951 };
952 
953 static int sysvipc_proc_open(struct inode *inode, struct file *file)
954 {
955         int ret;
956         struct seq_file *seq;
957         struct ipc_proc_iter *iter;
958 
959         ret = -ENOMEM;
960         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
961         if (!iter)
962                 goto out;
963 
964         ret = seq_open(file, &sysvipc_proc_seqops);
965         if (ret)
966                 goto out_kfree;
967 
968         seq = file->private_data;
969         seq->private = iter;
970 
971         iter->iface = PDE(inode)->data;
972         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
973 out:
974         return ret;
975 out_kfree:
976         kfree(iter);
977         goto out;
978 }
979 
980 static int sysvipc_proc_release(struct inode *inode, struct file *file)
981 {
982         struct seq_file *seq = file->private_data;
983         struct ipc_proc_iter *iter = seq->private;
984         put_ipc_ns(iter->ns);
985         return seq_release_private(inode, file);
986 }
987 
988 static const struct file_operations sysvipc_proc_fops = {
989         .open    = sysvipc_proc_open,
990         .read    = seq_read,
991         .llseek  = seq_lseek,
992         .release = sysvipc_proc_release,
993 };
994 #endif /* CONFIG_PROC_FS */
995 

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