Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/ipc/util.c

  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  * General sysv ipc locking scheme:
 20  *      rcu_read_lock()
 21  *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
 22  *          tree.
 23  *          - perform initial checks (capabilities, auditing and permission,
 24  *            etc).
 25  *          - perform read-only operations, such as STAT, INFO commands.
 26  *            acquire the ipc lock (kern_ipc_perm.lock) through
 27  *            ipc_lock_object()
 28  *              - perform data updates, such as SET, RMID commands and
 29  *                mechanism-specific operations (semop/semtimedop,
 30  *                msgsnd/msgrcv, shmat/shmdt).
 31  *          drop the ipc lock, through ipc_unlock_object().
 32  *      rcu_read_unlock()
 33  *
 34  *  The ids->rwsem must be taken when:
 35  *      - creating, removing and iterating the existing entries in ipc
 36  *        identifier sets.
 37  *      - iterating through files under /proc/sysvipc/
 38  *
 39  *  Note that sems have a special fast path that avoids kern_ipc_perm.lock -
 40  *  see sem_lock().
 41  */
 42 
 43 #include <linux/mm.h>
 44 #include <linux/shm.h>
 45 #include <linux/init.h>
 46 #include <linux/msg.h>
 47 #include <linux/vmalloc.h>
 48 #include <linux/slab.h>
 49 #include <linux/notifier.h>
 50 #include <linux/capability.h>
 51 #include <linux/highuid.h>
 52 #include <linux/security.h>
 53 #include <linux/rcupdate.h>
 54 #include <linux/workqueue.h>
 55 #include <linux/seq_file.h>
 56 #include <linux/proc_fs.h>
 57 #include <linux/audit.h>
 58 #include <linux/nsproxy.h>
 59 #include <linux/rwsem.h>
 60 #include <linux/memory.h>
 61 #include <linux/ipc_namespace.h>
 62 
 63 #include <asm/unistd.h>
 64 
 65 #include "util.h"
 66 
 67 struct ipc_proc_iface {
 68         const char *path;
 69         const char *header;
 70         int ids;
 71         int (*show)(struct seq_file *, void *);
 72 };
 73 
 74 /**
 75  * ipc_init - initialise ipc subsystem
 76  *
 77  * The various sysv ipc resources (semaphores, messages and shared
 78  * memory) are initialised.
 79  *
 80  * A callback routine is registered into the memory hotplug notifier
 81  * chain: since msgmni scales to lowmem this callback routine will be
 82  * called upon successful memory add / remove to recompute msmgni.
 83  */
 84 static int __init ipc_init(void)
 85 {
 86         sem_init();
 87         msg_init();
 88         shm_init();
 89         return 0;
 90 }
 91 device_initcall(ipc_init);
 92 
 93 /**
 94  * ipc_init_ids - initialise ipc identifiers
 95  * @ids: ipc identifier set
 96  *
 97  * Set up the sequence range to use for the ipc identifier range (limited
 98  * below IPCMNI) then initialise the ids idr.
 99  */
100 void ipc_init_ids(struct ipc_ids *ids)
101 {
102         ids->in_use = 0;
103         ids->seq = 0;
104         ids->next_id = -1;
105         init_rwsem(&ids->rwsem);
106         idr_init(&ids->ipcs_idr);
107 }
108 
109 #ifdef CONFIG_PROC_FS
110 static const struct file_operations sysvipc_proc_fops;
111 /**
112  * ipc_init_proc_interface -  create a proc interface for sysipc types using a seq_file interface.
113  * @path: Path in procfs
114  * @header: Banner to be printed at the beginning of the file.
115  * @ids: ipc id table to iterate.
116  * @show: show routine.
117  */
118 void __init ipc_init_proc_interface(const char *path, const char *header,
119                 int ids, int (*show)(struct seq_file *, void *))
120 {
121         struct proc_dir_entry *pde;
122         struct ipc_proc_iface *iface;
123 
124         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
125         if (!iface)
126                 return;
127         iface->path     = path;
128         iface->header   = header;
129         iface->ids      = ids;
130         iface->show     = show;
131 
132         pde = proc_create_data(path,
133                                S_IRUGO,        /* world readable */
134                                NULL,           /* parent dir */
135                                &sysvipc_proc_fops,
136                                iface);
137         if (!pde)
138                 kfree(iface);
139 }
140 #endif
141 
142 /**
143  * ipc_findkey  - find a key in an ipc identifier set
144  * @ids: ipc identifier set
145  * @key: key to find
146  *
147  * Returns the locked pointer to the ipc structure if found or NULL
148  * otherwise. If key is found ipc points to the owning ipc structure
149  *
150  * Called with ipc_ids.rwsem held.
151  */
152 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
153 {
154         struct kern_ipc_perm *ipc;
155         int next_id;
156         int total;
157 
158         for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
159                 ipc = idr_find(&ids->ipcs_idr, next_id);
160 
161                 if (ipc == NULL)
162                         continue;
163 
164                 if (ipc->key != key) {
165                         total++;
166                         continue;
167                 }
168 
169                 rcu_read_lock();
170                 ipc_lock_object(ipc);
171                 return ipc;
172         }
173 
174         return NULL;
175 }
176 
177 /**
178  * ipc_get_maxid - get the last assigned id
179  * @ids: ipc identifier set
180  *
181  * Called with ipc_ids.rwsem held.
182  */
183 int ipc_get_maxid(struct ipc_ids *ids)
184 {
185         struct kern_ipc_perm *ipc;
186         int max_id = -1;
187         int total, id;
188 
189         if (ids->in_use == 0)
190                 return -1;
191 
192         if (ids->in_use == IPCMNI)
193                 return IPCMNI - 1;
194 
195         /* Look for the last assigned id */
196         total = 0;
197         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
198                 ipc = idr_find(&ids->ipcs_idr, id);
199                 if (ipc != NULL) {
200                         max_id = id;
201                         total++;
202                 }
203         }
204         return max_id;
205 }
206 
207 /**
208  * ipc_addid - add an ipc identifier
209  * @ids: ipc identifier set
210  * @new: new ipc permission set
211  * @size: limit for the number of used ids
212  *
213  * Add an entry 'new' to the ipc ids idr. The permissions object is
214  * initialised and the first free entry is set up and the id assigned
215  * is returned. The 'new' entry is returned in a locked state on success.
216  * On failure the entry is not locked and a negative err-code is returned.
217  *
218  * Called with writer ipc_ids.rwsem held.
219  */
220 int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
221 {
222         kuid_t euid;
223         kgid_t egid;
224         int id;
225         int next_id = ids->next_id;
226 
227         if (size > IPCMNI)
228                 size = IPCMNI;
229 
230         if (ids->in_use >= size)
231                 return -ENOSPC;
232 
233         idr_preload(GFP_KERNEL);
234 
235         spin_lock_init(&new->lock);
236         new->deleted = false;
237         rcu_read_lock();
238         spin_lock(&new->lock);
239 
240         current_euid_egid(&euid, &egid);
241         new->cuid = new->uid = euid;
242         new->gid = new->cgid = egid;
243 
244         id = idr_alloc(&ids->ipcs_idr, new,
245                        (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
246                        GFP_NOWAIT);
247         idr_preload_end();
248         if (id < 0) {
249                 spin_unlock(&new->lock);
250                 rcu_read_unlock();
251                 return id;
252         }
253 
254         ids->in_use++;
255 
256         if (next_id < 0) {
257                 new->seq = ids->seq++;
258                 if (ids->seq > IPCID_SEQ_MAX)
259                         ids->seq = 0;
260         } else {
261                 new->seq = ipcid_to_seqx(next_id);
262                 ids->next_id = -1;
263         }
264 
265         new->id = ipc_buildid(id, new->seq);
266         return id;
267 }
268 
269 /**
270  * ipcget_new - create a new ipc object
271  * @ns: ipc namespace
272  * @ids: ipc identifier set
273  * @ops: the actual creation routine to call
274  * @params: its parameters
275  *
276  * This routine is called by sys_msgget, sys_semget() and sys_shmget()
277  * when the key is IPC_PRIVATE.
278  */
279 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
280                 const struct ipc_ops *ops, struct ipc_params *params)
281 {
282         int err;
283 
284         down_write(&ids->rwsem);
285         err = ops->getnew(ns, params);
286         up_write(&ids->rwsem);
287         return err;
288 }
289 
290 /**
291  * ipc_check_perms - check security and permissions for an ipc object
292  * @ns: ipc namespace
293  * @ipcp: ipc permission set
294  * @ops: the actual security routine to call
295  * @params: its parameters
296  *
297  * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
298  * when the key is not IPC_PRIVATE and that key already exists in the
299  * ds IDR.
300  *
301  * On success, the ipc id is returned.
302  *
303  * It is called with ipc_ids.rwsem and ipcp->lock held.
304  */
305 static int ipc_check_perms(struct ipc_namespace *ns,
306                            struct kern_ipc_perm *ipcp,
307                            const struct ipc_ops *ops,
308                            struct ipc_params *params)
309 {
310         int err;
311 
312         if (ipcperms(ns, ipcp, params->flg))
313                 err = -EACCES;
314         else {
315                 err = ops->associate(ipcp, params->flg);
316                 if (!err)
317                         err = ipcp->id;
318         }
319 
320         return err;
321 }
322 
323 /**
324  * ipcget_public - get an ipc object or create a new one
325  * @ns: ipc namespace
326  * @ids: ipc identifier set
327  * @ops: the actual creation routine to call
328  * @params: its parameters
329  *
330  * This routine is called by sys_msgget, sys_semget() and sys_shmget()
331  * when the key is not IPC_PRIVATE.
332  * It adds a new entry if the key is not found and does some permission
333  * / security checkings if the key is found.
334  *
335  * On success, the ipc id is returned.
336  */
337 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
338                 const struct ipc_ops *ops, struct ipc_params *params)
339 {
340         struct kern_ipc_perm *ipcp;
341         int flg = params->flg;
342         int err;
343 
344         /*
345          * Take the lock as a writer since we are potentially going to add
346          * a new entry + read locks are not "upgradable"
347          */
348         down_write(&ids->rwsem);
349         ipcp = ipc_findkey(ids, params->key);
350         if (ipcp == NULL) {
351                 /* key not used */
352                 if (!(flg & IPC_CREAT))
353                         err = -ENOENT;
354                 else
355                         err = ops->getnew(ns, params);
356         } else {
357                 /* ipc object has been locked by ipc_findkey() */
358 
359                 if (flg & IPC_CREAT && flg & IPC_EXCL)
360                         err = -EEXIST;
361                 else {
362                         err = 0;
363                         if (ops->more_checks)
364                                 err = ops->more_checks(ipcp, params);
365                         if (!err)
366                                 /*
367                                  * ipc_check_perms returns the IPC id on
368                                  * success
369                                  */
370                                 err = ipc_check_perms(ns, ipcp, ops, params);
371                 }
372                 ipc_unlock(ipcp);
373         }
374         up_write(&ids->rwsem);
375 
376         return err;
377 }
378 
379 
380 /**
381  * ipc_rmid - remove an ipc identifier
382  * @ids: ipc identifier set
383  * @ipcp: ipc perm structure containing the identifier to remove
384  *
385  * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
386  * before this function is called, and remain locked on the exit.
387  */
388 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
389 {
390         int lid = ipcid_to_idx(ipcp->id);
391 
392         idr_remove(&ids->ipcs_idr, lid);
393         ids->in_use--;
394         ipcp->deleted = true;
395 }
396 
397 /**
398  * ipc_alloc -  allocate ipc space
399  * @size: size desired
400  *
401  * Allocate memory from the appropriate pools and return a pointer to it.
402  * NULL is returned if the allocation fails
403  */
404 void *ipc_alloc(int size)
405 {
406         void *out;
407         if (size > PAGE_SIZE)
408                 out = vmalloc(size);
409         else
410                 out = kmalloc(size, GFP_KERNEL);
411         return out;
412 }
413 
414 /**
415  * ipc_free - free ipc space
416  * @ptr: pointer returned by ipc_alloc
417  *
418  * Free a block created with ipc_alloc().
419  */
420 void ipc_free(void *ptr)
421 {
422         kvfree(ptr);
423 }
424 
425 /**
426  * ipc_rcu_alloc - allocate ipc and rcu space
427  * @size: size desired
428  *
429  * Allocate memory for the rcu header structure +  the object.
430  * Returns the pointer to the object or NULL upon failure.
431  */
432 void *ipc_rcu_alloc(int size)
433 {
434         /*
435          * We prepend the allocation with the rcu struct
436          */
437         struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
438         if (unlikely(!out))
439                 return NULL;
440         atomic_set(&out->refcount, 1);
441         return out + 1;
442 }
443 
444 int ipc_rcu_getref(void *ptr)
445 {
446         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
447 
448         return atomic_inc_not_zero(&p->refcount);
449 }
450 
451 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
452 {
453         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
454 
455         if (!atomic_dec_and_test(&p->refcount))
456                 return;
457 
458         call_rcu(&p->rcu, func);
459 }
460 
461 void ipc_rcu_free(struct rcu_head *head)
462 {
463         struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
464 
465         kvfree(p);
466 }
467 
468 /**
469  * ipcperms - check ipc permissions
470  * @ns: ipc namespace
471  * @ipcp: ipc permission set
472  * @flag: desired permission set
473  *
474  * Check user, group, other permissions for access
475  * to ipc resources. return 0 if allowed
476  *
477  * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
478  */
479 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
480 {
481         kuid_t euid = current_euid();
482         int requested_mode, granted_mode;
483 
484         audit_ipc_obj(ipcp);
485         requested_mode = (flag >> 6) | (flag >> 3) | flag;
486         granted_mode = ipcp->mode;
487         if (uid_eq(euid, ipcp->cuid) ||
488             uid_eq(euid, ipcp->uid))
489                 granted_mode >>= 6;
490         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
491                 granted_mode >>= 3;
492         /* is there some bit set in requested_mode but not in granted_mode? */
493         if ((requested_mode & ~granted_mode & 0007) &&
494             !ns_capable(ns->user_ns, CAP_IPC_OWNER))
495                 return -1;
496 
497         return security_ipc_permission(ipcp, flag);
498 }
499 
500 /*
501  * Functions to convert between the kern_ipc_perm structure and the
502  * old/new ipc_perm structures
503  */
504 
505 /**
506  * kernel_to_ipc64_perm - convert kernel ipc permissions to user
507  * @in: kernel permissions
508  * @out: new style ipc permissions
509  *
510  * Turn the kernel object @in into a set of permissions descriptions
511  * for returning to userspace (@out).
512  */
513 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
514 {
515         out->key        = in->key;
516         out->uid        = from_kuid_munged(current_user_ns(), in->uid);
517         out->gid        = from_kgid_munged(current_user_ns(), in->gid);
518         out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
519         out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
520         out->mode       = in->mode;
521         out->seq        = in->seq;
522 }
523 
524 /**
525  * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
526  * @in: new style ipc permissions
527  * @out: old style ipc permissions
528  *
529  * Turn the new style permissions object @in into a compatibility
530  * object and store it into the @out pointer.
531  */
532 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
533 {
534         out->key        = in->key;
535         SET_UID(out->uid, in->uid);
536         SET_GID(out->gid, in->gid);
537         SET_UID(out->cuid, in->cuid);
538         SET_GID(out->cgid, in->cgid);
539         out->mode       = in->mode;
540         out->seq        = in->seq;
541 }
542 
543 /**
544  * ipc_obtain_object
545  * @ids: ipc identifier set
546  * @id: ipc id to look for
547  *
548  * Look for an id in the ipc ids idr and return associated ipc object.
549  *
550  * Call inside the RCU critical section.
551  * The ipc object is *not* locked on exit.
552  */
553 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
554 {
555         struct kern_ipc_perm *out;
556         int lid = ipcid_to_idx(id);
557 
558         out = idr_find(&ids->ipcs_idr, lid);
559         if (!out)
560                 return ERR_PTR(-EINVAL);
561 
562         return out;
563 }
564 
565 /**
566  * ipc_lock - lock an ipc structure without rwsem held
567  * @ids: ipc identifier set
568  * @id: ipc id to look for
569  *
570  * Look for an id in the ipc ids idr and lock the associated ipc object.
571  *
572  * The ipc object is locked on successful exit.
573  */
574 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
575 {
576         struct kern_ipc_perm *out;
577 
578         rcu_read_lock();
579         out = ipc_obtain_object_idr(ids, id);
580         if (IS_ERR(out))
581                 goto err;
582 
583         spin_lock(&out->lock);
584 
585         /*
586          * ipc_rmid() may have already freed the ID while ipc_lock()
587          * was spinning: here verify that the structure is still valid.
588          * Upon races with RMID, return -EIDRM, thus indicating that
589          * the ID points to a removed identifier.
590          */
591         if (ipc_valid_object(out))
592                 return out;
593 
594         spin_unlock(&out->lock);
595         out = ERR_PTR(-EIDRM);
596 err:
597         rcu_read_unlock();
598         return out;
599 }
600 
601 /**
602  * ipc_obtain_object_check
603  * @ids: ipc identifier set
604  * @id: ipc id to look for
605  *
606  * Similar to ipc_obtain_object_idr() but also checks
607  * the ipc object reference counter.
608  *
609  * Call inside the RCU critical section.
610  * The ipc object is *not* locked on exit.
611  */
612 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
613 {
614         struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
615 
616         if (IS_ERR(out))
617                 goto out;
618 
619         if (ipc_checkid(out, id))
620                 return ERR_PTR(-EINVAL);
621 out:
622         return out;
623 }
624 
625 /**
626  * ipcget - Common sys_*get() code
627  * @ns: namespace
628  * @ids: ipc identifier set
629  * @ops: operations to be called on ipc object creation, permission checks
630  *       and further checks
631  * @params: the parameters needed by the previous operations.
632  *
633  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
634  */
635 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
636                         const struct ipc_ops *ops, struct ipc_params *params)
637 {
638         if (params->key == IPC_PRIVATE)
639                 return ipcget_new(ns, ids, ops, params);
640         else
641                 return ipcget_public(ns, ids, ops, params);
642 }
643 
644 /**
645  * ipc_update_perm - update the permissions of an ipc object
646  * @in:  the permission given as input.
647  * @out: the permission of the ipc to set.
648  */
649 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
650 {
651         kuid_t uid = make_kuid(current_user_ns(), in->uid);
652         kgid_t gid = make_kgid(current_user_ns(), in->gid);
653         if (!uid_valid(uid) || !gid_valid(gid))
654                 return -EINVAL;
655 
656         out->uid = uid;
657         out->gid = gid;
658         out->mode = (out->mode & ~S_IRWXUGO)
659                 | (in->mode & S_IRWXUGO);
660 
661         return 0;
662 }
663 
664 /**
665  * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
666  * @ns:  ipc namespace
667  * @ids:  the table of ids where to look for the ipc
668  * @id:   the id of the ipc to retrieve
669  * @cmd:  the cmd to check
670  * @perm: the permission to set
671  * @extra_perm: one extra permission parameter used by msq
672  *
673  * This function does some common audit and permissions check for some IPC_XXX
674  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
675  * It must be called without any lock held and
676  *  - retrieves the ipc with the given id in the given table.
677  *  - performs some audit and permission check, depending on the given cmd
678  *  - returns a pointer to the ipc object or otherwise, the corresponding error.
679  *
680  * Call holding the both the rwsem and the rcu read lock.
681  */
682 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
683                                         struct ipc_ids *ids, int id, int cmd,
684                                         struct ipc64_perm *perm, int extra_perm)
685 {
686         kuid_t euid;
687         int err = -EPERM;
688         struct kern_ipc_perm *ipcp;
689 
690         ipcp = ipc_obtain_object_check(ids, id);
691         if (IS_ERR(ipcp)) {
692                 err = PTR_ERR(ipcp);
693                 goto err;
694         }
695 
696         audit_ipc_obj(ipcp);
697         if (cmd == IPC_SET)
698                 audit_ipc_set_perm(extra_perm, perm->uid,
699                                    perm->gid, perm->mode);
700 
701         euid = current_euid();
702         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
703             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
704                 return ipcp; /* successful lookup */
705 err:
706         return ERR_PTR(err);
707 }
708 
709 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
710 
711 
712 /**
713  * ipc_parse_version - ipc call version
714  * @cmd: pointer to command
715  *
716  * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
717  * The @cmd value is turned from an encoding command and version into
718  * just the command code.
719  */
720 int ipc_parse_version(int *cmd)
721 {
722         if (*cmd & IPC_64) {
723                 *cmd ^= IPC_64;
724                 return IPC_64;
725         } else {
726                 return IPC_OLD;
727         }
728 }
729 
730 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
731 
732 #ifdef CONFIG_PROC_FS
733 struct ipc_proc_iter {
734         struct ipc_namespace *ns;
735         struct ipc_proc_iface *iface;
736 };
737 
738 /*
739  * This routine locks the ipc structure found at least at position pos.
740  */
741 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
742                                               loff_t *new_pos)
743 {
744         struct kern_ipc_perm *ipc;
745         int total, id;
746 
747         total = 0;
748         for (id = 0; id < pos && total < ids->in_use; id++) {
749                 ipc = idr_find(&ids->ipcs_idr, id);
750                 if (ipc != NULL)
751                         total++;
752         }
753 
754         if (total >= ids->in_use)
755                 return NULL;
756 
757         for (; pos < IPCMNI; pos++) {
758                 ipc = idr_find(&ids->ipcs_idr, pos);
759                 if (ipc != NULL) {
760                         *new_pos = pos + 1;
761                         rcu_read_lock();
762                         ipc_lock_object(ipc);
763                         return ipc;
764                 }
765         }
766 
767         /* Out of range - return NULL to terminate iteration */
768         return NULL;
769 }
770 
771 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
772 {
773         struct ipc_proc_iter *iter = s->private;
774         struct ipc_proc_iface *iface = iter->iface;
775         struct kern_ipc_perm *ipc = it;
776 
777         /* If we had an ipc id locked before, unlock it */
778         if (ipc && ipc != SEQ_START_TOKEN)
779                 ipc_unlock(ipc);
780 
781         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
782 }
783 
784 /*
785  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
786  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
787  */
788 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
789 {
790         struct ipc_proc_iter *iter = s->private;
791         struct ipc_proc_iface *iface = iter->iface;
792         struct ipc_ids *ids;
793 
794         ids = &iter->ns->ids[iface->ids];
795 
796         /*
797          * Take the lock - this will be released by the corresponding
798          * call to stop().
799          */
800         down_read(&ids->rwsem);
801 
802         /* pos < 0 is invalid */
803         if (*pos < 0)
804                 return NULL;
805 
806         /* pos == 0 means header */
807         if (*pos == 0)
808                 return SEQ_START_TOKEN;
809 
810         /* Find the (pos-1)th ipc */
811         return sysvipc_find_ipc(ids, *pos - 1, pos);
812 }
813 
814 static void sysvipc_proc_stop(struct seq_file *s, void *it)
815 {
816         struct kern_ipc_perm *ipc = it;
817         struct ipc_proc_iter *iter = s->private;
818         struct ipc_proc_iface *iface = iter->iface;
819         struct ipc_ids *ids;
820 
821         /* If we had a locked structure, release it */
822         if (ipc && ipc != SEQ_START_TOKEN)
823                 ipc_unlock(ipc);
824 
825         ids = &iter->ns->ids[iface->ids];
826         /* Release the lock we took in start() */
827         up_read(&ids->rwsem);
828 }
829 
830 static int sysvipc_proc_show(struct seq_file *s, void *it)
831 {
832         struct ipc_proc_iter *iter = s->private;
833         struct ipc_proc_iface *iface = iter->iface;
834 
835         if (it == SEQ_START_TOKEN) {
836                 seq_puts(s, iface->header);
837                 return 0;
838         }
839 
840         return iface->show(s, it);
841 }
842 
843 static const struct seq_operations sysvipc_proc_seqops = {
844         .start = sysvipc_proc_start,
845         .stop  = sysvipc_proc_stop,
846         .next  = sysvipc_proc_next,
847         .show  = sysvipc_proc_show,
848 };
849 
850 static int sysvipc_proc_open(struct inode *inode, struct file *file)
851 {
852         struct ipc_proc_iter *iter;
853 
854         iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
855         if (!iter)
856                 return -ENOMEM;
857 
858         iter->iface = PDE_DATA(inode);
859         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
860 
861         return 0;
862 }
863 
864 static int sysvipc_proc_release(struct inode *inode, struct file *file)
865 {
866         struct seq_file *seq = file->private_data;
867         struct ipc_proc_iter *iter = seq->private;
868         put_ipc_ns(iter->ns);
869         return seq_release_private(inode, file);
870 }
871 
872 static const struct file_operations sysvipc_proc_fops = {
873         .open    = sysvipc_proc_open,
874         .read    = seq_read,
875         .llseek  = seq_lseek,
876         .release = sysvipc_proc_release,
877 };
878 #endif /* CONFIG_PROC_FS */
879 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us