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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 | * 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 | static void ipc_memory_notifier(struct work_struct *work) |
75 | { |
76 | ipcns_notify(IPCNS_MEMCHANGED); |
77 | } |
78 | |
79 | static int ipc_memory_callback(struct notifier_block *self, |
80 | unsigned long action, void *arg) |
81 | { |
82 | static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier); |
83 | |
84 | switch (action) { |
85 | case MEM_ONLINE: /* memory successfully brought online */ |
86 | case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */ |
87 | /* |
88 | * This is done by invoking the ipcns notifier chain with the |
89 | * IPC_MEMCHANGED event. |
90 | * In order not to keep the lock on the hotplug memory chain |
91 | * for too long, queue a work item that will, when waken up, |
92 | * activate the ipcns notification chain. |
93 | */ |
94 | schedule_work(&ipc_memory_wq); |
95 | break; |
96 | case MEM_GOING_ONLINE: |
97 | case MEM_GOING_OFFLINE: |
98 | case MEM_CANCEL_ONLINE: |
99 | case MEM_CANCEL_OFFLINE: |
100 | default: |
101 | break; |
102 | } |
103 | |
104 | return NOTIFY_OK; |
105 | } |
106 | |
107 | static struct notifier_block ipc_memory_nb = { |
108 | .notifier_call = ipc_memory_callback, |
109 | .priority = IPC_CALLBACK_PRI, |
110 | }; |
111 | |
112 | /** |
113 | * ipc_init - initialise IPC subsystem |
114 | * |
115 | * The various system5 IPC resources (semaphores, messages and shared |
116 | * memory) are initialised |
117 | * A callback routine is registered into the memory hotplug notifier |
118 | * chain: since msgmni scales to lowmem this callback routine will be |
119 | * called upon successful memory add / remove to recompute msmgni. |
120 | */ |
121 | |
122 | static int __init ipc_init(void) |
123 | { |
124 | sem_init(); |
125 | msg_init(); |
126 | shm_init(); |
127 | register_hotmemory_notifier(&ipc_memory_nb); |
128 | register_ipcns_notifier(&init_ipc_ns); |
129 | return 0; |
130 | } |
131 | __initcall(ipc_init); |
132 | |
133 | /** |
134 | * ipc_init_ids - initialise IPC identifiers |
135 | * @ids: Identifier set |
136 | * |
137 | * Set up the sequence range to use for the ipc identifier range (limited |
138 | * below IPCMNI) then initialise the ids idr. |
139 | */ |
140 | |
141 | void ipc_init_ids(struct ipc_ids *ids) |
142 | { |
143 | init_rwsem(&ids->rwsem); |
144 | |
145 | ids->in_use = 0; |
146 | ids->seq = 0; |
147 | ids->next_id = -1; |
148 | { |
149 | int seq_limit = INT_MAX/SEQ_MULTIPLIER; |
150 | if (seq_limit > USHRT_MAX) |
151 | ids->seq_max = USHRT_MAX; |
152 | else |
153 | ids->seq_max = seq_limit; |
154 | } |
155 | |
156 | idr_init(&ids->ipcs_idr); |
157 | } |
158 | |
159 | #ifdef CONFIG_PROC_FS |
160 | static const struct file_operations sysvipc_proc_fops; |
161 | /** |
162 | * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface. |
163 | * @path: Path in procfs |
164 | * @header: Banner to be printed at the beginning of the file. |
165 | * @ids: ipc id table to iterate. |
166 | * @show: show routine. |
167 | */ |
168 | void __init ipc_init_proc_interface(const char *path, const char *header, |
169 | int ids, int (*show)(struct seq_file *, void *)) |
170 | { |
171 | struct proc_dir_entry *pde; |
172 | struct ipc_proc_iface *iface; |
173 | |
174 | iface = kmalloc(sizeof(*iface), GFP_KERNEL); |
175 | if (!iface) |
176 | return; |
177 | iface->path = path; |
178 | iface->header = header; |
179 | iface->ids = ids; |
180 | iface->show = show; |
181 | |
182 | pde = proc_create_data(path, |
183 | S_IRUGO, /* world readable */ |
184 | NULL, /* parent dir */ |
185 | &sysvipc_proc_fops, |
186 | iface); |
187 | if (!pde) { |
188 | kfree(iface); |
189 | } |
190 | } |
191 | #endif |
192 | |
193 | /** |
194 | * ipc_findkey - find a key in an ipc identifier set |
195 | * @ids: Identifier set |
196 | * @key: The key to find |
197 | * |
198 | * Requires ipc_ids.rwsem locked. |
199 | * Returns the LOCKED pointer to the ipc structure if found or NULL |
200 | * if not. |
201 | * If key is found ipc points to the owning ipc structure |
202 | */ |
203 | |
204 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) |
205 | { |
206 | struct kern_ipc_perm *ipc; |
207 | int next_id; |
208 | int total; |
209 | |
210 | for (total = 0, next_id = 0; total < ids->in_use; next_id++) { |
211 | ipc = idr_find(&ids->ipcs_idr, next_id); |
212 | |
213 | if (ipc == NULL) |
214 | continue; |
215 | |
216 | if (ipc->key != key) { |
217 | total++; |
218 | continue; |
219 | } |
220 | |
221 | rcu_read_lock(); |
222 | ipc_lock_object(ipc); |
223 | return ipc; |
224 | } |
225 | |
226 | return NULL; |
227 | } |
228 | |
229 | /** |
230 | * ipc_get_maxid - get the last assigned id |
231 | * @ids: IPC identifier set |
232 | * |
233 | * Called with ipc_ids.rwsem held. |
234 | */ |
235 | |
236 | int ipc_get_maxid(struct ipc_ids *ids) |
237 | { |
238 | struct kern_ipc_perm *ipc; |
239 | int max_id = -1; |
240 | int total, id; |
241 | |
242 | if (ids->in_use == 0) |
243 | return -1; |
244 | |
245 | if (ids->in_use == IPCMNI) |
246 | return IPCMNI - 1; |
247 | |
248 | /* Look for the last assigned id */ |
249 | total = 0; |
250 | for (id = 0; id < IPCMNI && total < ids->in_use; id++) { |
251 | ipc = idr_find(&ids->ipcs_idr, id); |
252 | if (ipc != NULL) { |
253 | max_id = id; |
254 | total++; |
255 | } |
256 | } |
257 | return max_id; |
258 | } |
259 | |
260 | /** |
261 | * ipc_addid - add an IPC identifier |
262 | * @ids: IPC identifier set |
263 | * @new: new IPC permission set |
264 | * @size: limit for the number of used ids |
265 | * |
266 | * Add an entry 'new' to the IPC ids idr. The permissions object is |
267 | * initialised and the first free entry is set up and the id assigned |
268 | * is returned. The 'new' entry is returned in a locked state on success. |
269 | * On failure the entry is not locked and a negative err-code is returned. |
270 | * |
271 | * Called with writer ipc_ids.rwsem held. |
272 | */ |
273 | int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) |
274 | { |
275 | kuid_t euid; |
276 | kgid_t egid; |
277 | int id; |
278 | int next_id = ids->next_id; |
279 | |
280 | if (size > IPCMNI) |
281 | size = IPCMNI; |
282 | |
283 | if (ids->in_use >= size) |
284 | return -ENOSPC; |
285 | |
286 | idr_preload(GFP_KERNEL); |
287 | |
288 | spin_lock_init(&new->lock); |
289 | new->deleted = 0; |
290 | rcu_read_lock(); |
291 | spin_lock(&new->lock); |
292 | |
293 | id = idr_alloc(&ids->ipcs_idr, new, |
294 | (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, |
295 | GFP_NOWAIT); |
296 | idr_preload_end(); |
297 | if (id < 0) { |
298 | spin_unlock(&new->lock); |
299 | rcu_read_unlock(); |
300 | return id; |
301 | } |
302 | |
303 | ids->in_use++; |
304 | |
305 | current_euid_egid(&euid, &egid); |
306 | new->cuid = new->uid = euid; |
307 | new->gid = new->cgid = egid; |
308 | |
309 | if (next_id < 0) { |
310 | new->seq = ids->seq++; |
311 | if (ids->seq > ids->seq_max) |
312 | ids->seq = 0; |
313 | } else { |
314 | new->seq = ipcid_to_seqx(next_id); |
315 | ids->next_id = -1; |
316 | } |
317 | |
318 | new->id = ipc_buildid(id, new->seq); |
319 | return id; |
320 | } |
321 | |
322 | /** |
323 | * ipcget_new - create a new ipc object |
324 | * @ns: namespace |
325 | * @ids: IPC identifer set |
326 | * @ops: the actual creation routine to call |
327 | * @params: its parameters |
328 | * |
329 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() |
330 | * when the key is IPC_PRIVATE. |
331 | */ |
332 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, |
333 | struct ipc_ops *ops, struct ipc_params *params) |
334 | { |
335 | int err; |
336 | |
337 | down_write(&ids->rwsem); |
338 | err = ops->getnew(ns, params); |
339 | up_write(&ids->rwsem); |
340 | return err; |
341 | } |
342 | |
343 | /** |
344 | * ipc_check_perms - check security and permissions for an IPC |
345 | * @ns: IPC namespace |
346 | * @ipcp: ipc permission set |
347 | * @ops: the actual security routine to call |
348 | * @params: its parameters |
349 | * |
350 | * This routine is called by sys_msgget(), sys_semget() and sys_shmget() |
351 | * when the key is not IPC_PRIVATE and that key already exists in the |
352 | * ids IDR. |
353 | * |
354 | * On success, the IPC id is returned. |
355 | * |
356 | * It is called with ipc_ids.rwsem and ipcp->lock held. |
357 | */ |
358 | static int ipc_check_perms(struct ipc_namespace *ns, |
359 | struct kern_ipc_perm *ipcp, |
360 | struct ipc_ops *ops, |
361 | struct ipc_params *params) |
362 | { |
363 | int err; |
364 | |
365 | if (ipcperms(ns, ipcp, params->flg)) |
366 | err = -EACCES; |
367 | else { |
368 | err = ops->associate(ipcp, params->flg); |
369 | if (!err) |
370 | err = ipcp->id; |
371 | } |
372 | |
373 | return err; |
374 | } |
375 | |
376 | /** |
377 | * ipcget_public - get an ipc object or create a new one |
378 | * @ns: namespace |
379 | * @ids: IPC identifer set |
380 | * @ops: the actual creation routine to call |
381 | * @params: its parameters |
382 | * |
383 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() |
384 | * when the key is not IPC_PRIVATE. |
385 | * It adds a new entry if the key is not found and does some permission |
386 | * / security checkings if the key is found. |
387 | * |
388 | * On success, the ipc id is returned. |
389 | */ |
390 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, |
391 | struct ipc_ops *ops, struct ipc_params *params) |
392 | { |
393 | struct kern_ipc_perm *ipcp; |
394 | int flg = params->flg; |
395 | int err; |
396 | |
397 | /* |
398 | * Take the lock as a writer since we are potentially going to add |
399 | * a new entry + read locks are not "upgradable" |
400 | */ |
401 | down_write(&ids->rwsem); |
402 | ipcp = ipc_findkey(ids, params->key); |
403 | if (ipcp == NULL) { |
404 | /* key not used */ |
405 | if (!(flg & IPC_CREAT)) |
406 | err = -ENOENT; |
407 | else |
408 | err = ops->getnew(ns, params); |
409 | } else { |
410 | /* ipc object has been locked by ipc_findkey() */ |
411 | |
412 | if (flg & IPC_CREAT && flg & IPC_EXCL) |
413 | err = -EEXIST; |
414 | else { |
415 | err = 0; |
416 | if (ops->more_checks) |
417 | err = ops->more_checks(ipcp, params); |
418 | if (!err) |
419 | /* |
420 | * ipc_check_perms returns the IPC id on |
421 | * success |
422 | */ |
423 | err = ipc_check_perms(ns, ipcp, ops, params); |
424 | } |
425 | ipc_unlock(ipcp); |
426 | } |
427 | up_write(&ids->rwsem); |
428 | |
429 | return err; |
430 | } |
431 | |
432 | |
433 | /** |
434 | * ipc_rmid - remove an IPC identifier |
435 | * @ids: IPC identifier set |
436 | * @ipcp: ipc perm structure containing the identifier to remove |
437 | * |
438 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held |
439 | * before this function is called, and remain locked on the exit. |
440 | */ |
441 | |
442 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) |
443 | { |
444 | int lid = ipcid_to_idx(ipcp->id); |
445 | |
446 | idr_remove(&ids->ipcs_idr, lid); |
447 | |
448 | ids->in_use--; |
449 | |
450 | ipcp->deleted = 1; |
451 | |
452 | return; |
453 | } |
454 | |
455 | /** |
456 | * ipc_alloc - allocate ipc space |
457 | * @size: size desired |
458 | * |
459 | * Allocate memory from the appropriate pools and return a pointer to it. |
460 | * NULL is returned if the allocation fails |
461 | */ |
462 | |
463 | void *ipc_alloc(int size) |
464 | { |
465 | void *out; |
466 | if(size > PAGE_SIZE) |
467 | out = vmalloc(size); |
468 | else |
469 | out = kmalloc(size, GFP_KERNEL); |
470 | return out; |
471 | } |
472 | |
473 | /** |
474 | * ipc_free - free ipc space |
475 | * @ptr: pointer returned by ipc_alloc |
476 | * @size: size of block |
477 | * |
478 | * Free a block created with ipc_alloc(). The caller must know the size |
479 | * used in the allocation call. |
480 | */ |
481 | |
482 | void ipc_free(void* ptr, int size) |
483 | { |
484 | if(size > PAGE_SIZE) |
485 | vfree(ptr); |
486 | else |
487 | kfree(ptr); |
488 | } |
489 | |
490 | /** |
491 | * ipc_rcu_alloc - allocate ipc and rcu space |
492 | * @size: size desired |
493 | * |
494 | * Allocate memory for the rcu header structure + the object. |
495 | * Returns the pointer to the object or NULL upon failure. |
496 | */ |
497 | void *ipc_rcu_alloc(int size) |
498 | { |
499 | /* |
500 | * We prepend the allocation with the rcu struct |
501 | */ |
502 | struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size); |
503 | if (unlikely(!out)) |
504 | return NULL; |
505 | atomic_set(&out->refcount, 1); |
506 | return out + 1; |
507 | } |
508 | |
509 | int ipc_rcu_getref(void *ptr) |
510 | { |
511 | struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; |
512 | |
513 | return atomic_inc_not_zero(&p->refcount); |
514 | } |
515 | |
516 | void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head)) |
517 | { |
518 | struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; |
519 | |
520 | if (!atomic_dec_and_test(&p->refcount)) |
521 | return; |
522 | |
523 | call_rcu(&p->rcu, func); |
524 | } |
525 | |
526 | void ipc_rcu_free(struct rcu_head *head) |
527 | { |
528 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); |
529 | |
530 | if (is_vmalloc_addr(p)) |
531 | vfree(p); |
532 | else |
533 | kfree(p); |
534 | } |
535 | |
536 | /** |
537 | * ipcperms - check IPC permissions |
538 | * @ns: IPC namespace |
539 | * @ipcp: IPC permission set |
540 | * @flag: desired permission set. |
541 | * |
542 | * Check user, group, other permissions for access |
543 | * to ipc resources. return 0 if allowed |
544 | * |
545 | * @flag will most probably be 0 or S_...UGO from <linux/stat.h> |
546 | */ |
547 | |
548 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) |
549 | { |
550 | kuid_t euid = current_euid(); |
551 | int requested_mode, granted_mode; |
552 | |
553 | audit_ipc_obj(ipcp); |
554 | requested_mode = (flag >> 6) | (flag >> 3) | flag; |
555 | granted_mode = ipcp->mode; |
556 | if (uid_eq(euid, ipcp->cuid) || |
557 | uid_eq(euid, ipcp->uid)) |
558 | granted_mode >>= 6; |
559 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) |
560 | granted_mode >>= 3; |
561 | /* is there some bit set in requested_mode but not in granted_mode? */ |
562 | if ((requested_mode & ~granted_mode & 0007) && |
563 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) |
564 | return -1; |
565 | |
566 | return security_ipc_permission(ipcp, flag); |
567 | } |
568 | |
569 | /* |
570 | * Functions to convert between the kern_ipc_perm structure and the |
571 | * old/new ipc_perm structures |
572 | */ |
573 | |
574 | /** |
575 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user |
576 | * @in: kernel permissions |
577 | * @out: new style IPC permissions |
578 | * |
579 | * Turn the kernel object @in into a set of permissions descriptions |
580 | * for returning to userspace (@out). |
581 | */ |
582 | |
583 | |
584 | void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out) |
585 | { |
586 | out->key = in->key; |
587 | out->uid = from_kuid_munged(current_user_ns(), in->uid); |
588 | out->gid = from_kgid_munged(current_user_ns(), in->gid); |
589 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); |
590 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); |
591 | out->mode = in->mode; |
592 | out->seq = in->seq; |
593 | } |
594 | |
595 | /** |
596 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old |
597 | * @in: new style IPC permissions |
598 | * @out: old style IPC permissions |
599 | * |
600 | * Turn the new style permissions object @in into a compatibility |
601 | * object and store it into the @out pointer. |
602 | */ |
603 | |
604 | void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) |
605 | { |
606 | out->key = in->key; |
607 | SET_UID(out->uid, in->uid); |
608 | SET_GID(out->gid, in->gid); |
609 | SET_UID(out->cuid, in->cuid); |
610 | SET_GID(out->cgid, in->cgid); |
611 | out->mode = in->mode; |
612 | out->seq = in->seq; |
613 | } |
614 | |
615 | /** |
616 | * ipc_obtain_object |
617 | * @ids: ipc identifier set |
618 | * @id: ipc id to look for |
619 | * |
620 | * Look for an id in the ipc ids idr and return associated ipc object. |
621 | * |
622 | * Call inside the RCU critical section. |
623 | * The ipc object is *not* locked on exit. |
624 | */ |
625 | struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id) |
626 | { |
627 | struct kern_ipc_perm *out; |
628 | int lid = ipcid_to_idx(id); |
629 | |
630 | out = idr_find(&ids->ipcs_idr, lid); |
631 | if (!out) |
632 | return ERR_PTR(-EINVAL); |
633 | |
634 | return out; |
635 | } |
636 | |
637 | /** |
638 | * ipc_lock - Lock an ipc structure without rwsem held |
639 | * @ids: IPC identifier set |
640 | * @id: ipc id to look for |
641 | * |
642 | * Look for an id in the ipc ids idr and lock the associated ipc object. |
643 | * |
644 | * The ipc object is locked on successful exit. |
645 | */ |
646 | struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) |
647 | { |
648 | struct kern_ipc_perm *out; |
649 | |
650 | rcu_read_lock(); |
651 | out = ipc_obtain_object(ids, id); |
652 | if (IS_ERR(out)) |
653 | goto err1; |
654 | |
655 | spin_lock(&out->lock); |
656 | |
657 | /* ipc_rmid() may have already freed the ID while ipc_lock |
658 | * was spinning: here verify that the structure is still valid |
659 | */ |
660 | if (!out->deleted) |
661 | return out; |
662 | |
663 | spin_unlock(&out->lock); |
664 | out = ERR_PTR(-EINVAL); |
665 | err1: |
666 | rcu_read_unlock(); |
667 | return out; |
668 | } |
669 | |
670 | /** |
671 | * ipc_obtain_object_check |
672 | * @ids: ipc identifier set |
673 | * @id: ipc id to look for |
674 | * |
675 | * Similar to ipc_obtain_object() but also checks |
676 | * the ipc object reference counter. |
677 | * |
678 | * Call inside the RCU critical section. |
679 | * The ipc object is *not* locked on exit. |
680 | */ |
681 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) |
682 | { |
683 | struct kern_ipc_perm *out = ipc_obtain_object(ids, id); |
684 | |
685 | if (IS_ERR(out)) |
686 | goto out; |
687 | |
688 | if (ipc_checkid(out, id)) |
689 | return ERR_PTR(-EIDRM); |
690 | out: |
691 | return out; |
692 | } |
693 | |
694 | /** |
695 | * ipcget - Common sys_*get() code |
696 | * @ns : namsepace |
697 | * @ids : IPC identifier set |
698 | * @ops : operations to be called on ipc object creation, permission checks |
699 | * and further checks |
700 | * @params : the parameters needed by the previous operations. |
701 | * |
702 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). |
703 | */ |
704 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, |
705 | struct ipc_ops *ops, struct ipc_params *params) |
706 | { |
707 | if (params->key == IPC_PRIVATE) |
708 | return ipcget_new(ns, ids, ops, params); |
709 | else |
710 | return ipcget_public(ns, ids, ops, params); |
711 | } |
712 | |
713 | /** |
714 | * ipc_update_perm - update the permissions of an IPC. |
715 | * @in: the permission given as input. |
716 | * @out: the permission of the ipc to set. |
717 | */ |
718 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) |
719 | { |
720 | kuid_t uid = make_kuid(current_user_ns(), in->uid); |
721 | kgid_t gid = make_kgid(current_user_ns(), in->gid); |
722 | if (!uid_valid(uid) || !gid_valid(gid)) |
723 | return -EINVAL; |
724 | |
725 | out->uid = uid; |
726 | out->gid = gid; |
727 | out->mode = (out->mode & ~S_IRWXUGO) |
728 | | (in->mode & S_IRWXUGO); |
729 | |
730 | return 0; |
731 | } |
732 | |
733 | /** |
734 | * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd |
735 | * @ns: the ipc namespace |
736 | * @ids: the table of ids where to look for the ipc |
737 | * @id: the id of the ipc to retrieve |
738 | * @cmd: the cmd to check |
739 | * @perm: the permission to set |
740 | * @extra_perm: one extra permission parameter used by msq |
741 | * |
742 | * This function does some common audit and permissions check for some IPC_XXX |
743 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. |
744 | * It must be called without any lock held and |
745 | * - retrieves the ipc with the given id in the given table. |
746 | * - performs some audit and permission check, depending on the given cmd |
747 | * - returns a pointer to the ipc object or otherwise, the corresponding error. |
748 | * |
749 | * Call holding the both the rwsem and the rcu read lock. |
750 | */ |
751 | struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, |
752 | struct ipc_ids *ids, int id, int cmd, |
753 | struct ipc64_perm *perm, int extra_perm) |
754 | { |
755 | kuid_t euid; |
756 | int err = -EPERM; |
757 | struct kern_ipc_perm *ipcp; |
758 | |
759 | ipcp = ipc_obtain_object_check(ids, id); |
760 | if (IS_ERR(ipcp)) { |
761 | err = PTR_ERR(ipcp); |
762 | goto err; |
763 | } |
764 | |
765 | audit_ipc_obj(ipcp); |
766 | if (cmd == IPC_SET) |
767 | audit_ipc_set_perm(extra_perm, perm->uid, |
768 | perm->gid, perm->mode); |
769 | |
770 | euid = current_euid(); |
771 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || |
772 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) |
773 | return ipcp; /* successful lookup */ |
774 | err: |
775 | return ERR_PTR(err); |
776 | } |
777 | |
778 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION |
779 | |
780 | |
781 | /** |
782 | * ipc_parse_version - IPC call version |
783 | * @cmd: pointer to command |
784 | * |
785 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. |
786 | * The @cmd value is turned from an encoding command and version into |
787 | * just the command code. |
788 | */ |
789 | |
790 | int ipc_parse_version (int *cmd) |
791 | { |
792 | if (*cmd & IPC_64) { |
793 | *cmd ^= IPC_64; |
794 | return IPC_64; |
795 | } else { |
796 | return IPC_OLD; |
797 | } |
798 | } |
799 | |
800 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ |
801 | |
802 | #ifdef CONFIG_PROC_FS |
803 | struct ipc_proc_iter { |
804 | struct ipc_namespace *ns; |
805 | struct ipc_proc_iface *iface; |
806 | }; |
807 | |
808 | /* |
809 | * This routine locks the ipc structure found at least at position pos. |
810 | */ |
811 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, |
812 | loff_t *new_pos) |
813 | { |
814 | struct kern_ipc_perm *ipc; |
815 | int total, id; |
816 | |
817 | total = 0; |
818 | for (id = 0; id < pos && total < ids->in_use; id++) { |
819 | ipc = idr_find(&ids->ipcs_idr, id); |
820 | if (ipc != NULL) |
821 | total++; |
822 | } |
823 | |
824 | if (total >= ids->in_use) |
825 | return NULL; |
826 | |
827 | for ( ; pos < IPCMNI; pos++) { |
828 | ipc = idr_find(&ids->ipcs_idr, pos); |
829 | if (ipc != NULL) { |
830 | *new_pos = pos + 1; |
831 | rcu_read_lock(); |
832 | ipc_lock_object(ipc); |
833 | return ipc; |
834 | } |
835 | } |
836 | |
837 | /* Out of range - return NULL to terminate iteration */ |
838 | return NULL; |
839 | } |
840 | |
841 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) |
842 | { |
843 | struct ipc_proc_iter *iter = s->private; |
844 | struct ipc_proc_iface *iface = iter->iface; |
845 | struct kern_ipc_perm *ipc = it; |
846 | |
847 | /* If we had an ipc id locked before, unlock it */ |
848 | if (ipc && ipc != SEQ_START_TOKEN) |
849 | ipc_unlock(ipc); |
850 | |
851 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); |
852 | } |
853 | |
854 | /* |
855 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. |
856 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. |
857 | */ |
858 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) |
859 | { |
860 | struct ipc_proc_iter *iter = s->private; |
861 | struct ipc_proc_iface *iface = iter->iface; |
862 | struct ipc_ids *ids; |
863 | |
864 | ids = &iter->ns->ids[iface->ids]; |
865 | |
866 | /* |
867 | * Take the lock - this will be released by the corresponding |
868 | * call to stop(). |
869 | */ |
870 | down_read(&ids->rwsem); |
871 | |
872 | /* pos < 0 is invalid */ |
873 | if (*pos < 0) |
874 | return NULL; |
875 | |
876 | /* pos == 0 means header */ |
877 | if (*pos == 0) |
878 | return SEQ_START_TOKEN; |
879 | |
880 | /* Find the (pos-1)th ipc */ |
881 | return sysvipc_find_ipc(ids, *pos - 1, pos); |
882 | } |
883 | |
884 | static void sysvipc_proc_stop(struct seq_file *s, void *it) |
885 | { |
886 | struct kern_ipc_perm *ipc = it; |
887 | struct ipc_proc_iter *iter = s->private; |
888 | struct ipc_proc_iface *iface = iter->iface; |
889 | struct ipc_ids *ids; |
890 | |
891 | /* If we had a locked structure, release it */ |
892 | if (ipc && ipc != SEQ_START_TOKEN) |
893 | ipc_unlock(ipc); |
894 | |
895 | ids = &iter->ns->ids[iface->ids]; |
896 | /* Release the lock we took in start() */ |
897 | up_read(&ids->rwsem); |
898 | } |
899 | |
900 | static int sysvipc_proc_show(struct seq_file *s, void *it) |
901 | { |
902 | struct ipc_proc_iter *iter = s->private; |
903 | struct ipc_proc_iface *iface = iter->iface; |
904 | |
905 | if (it == SEQ_START_TOKEN) |
906 | return seq_puts(s, iface->header); |
907 | |
908 | return iface->show(s, it); |
909 | } |
910 | |
911 | static const struct seq_operations sysvipc_proc_seqops = { |
912 | .start = sysvipc_proc_start, |
913 | .stop = sysvipc_proc_stop, |
914 | .next = sysvipc_proc_next, |
915 | .show = sysvipc_proc_show, |
916 | }; |
917 | |
918 | static int sysvipc_proc_open(struct inode *inode, struct file *file) |
919 | { |
920 | int ret; |
921 | struct seq_file *seq; |
922 | struct ipc_proc_iter *iter; |
923 | |
924 | ret = -ENOMEM; |
925 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
926 | if (!iter) |
927 | goto out; |
928 | |
929 | ret = seq_open(file, &sysvipc_proc_seqops); |
930 | if (ret) |
931 | goto out_kfree; |
932 | |
933 | seq = file->private_data; |
934 | seq->private = iter; |
935 | |
936 | iter->iface = PDE_DATA(inode); |
937 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); |
938 | out: |
939 | return ret; |
940 | out_kfree: |
941 | kfree(iter); |
942 | goto out; |
943 | } |
944 | |
945 | static int sysvipc_proc_release(struct inode *inode, struct file *file) |
946 | { |
947 | struct seq_file *seq = file->private_data; |
948 | struct ipc_proc_iter *iter = seq->private; |
949 | put_ipc_ns(iter->ns); |
950 | return seq_release_private(inode, file); |
951 | } |
952 | |
953 | static const struct file_operations sysvipc_proc_fops = { |
954 | .open = sysvipc_proc_open, |
955 | .read = seq_read, |
956 | .llseek = seq_lseek, |
957 | .release = sysvipc_proc_release, |
958 | }; |
959 | #endif /* CONFIG_PROC_FS */ |
960 |
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