blob: 798cad18dd878f2ee81f03e34431dbc001e2c2a9
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 |