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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 | uid_t euid; |
253 | gid_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 | uid_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 (euid == ipcp->cuid || |
616 | 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 = in->uid; |
647 | out->gid = in->gid; |
648 | out->cuid = in->cuid; |
649 | out->cgid = 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 | void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) |
751 | { |
752 | out->uid = in->uid; |
753 | out->gid = in->gid; |
754 | out->mode = (out->mode & ~S_IRWXUGO) |
755 | | (in->mode & S_IRWXUGO); |
756 | } |
757 | |
758 | /** |
759 | * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd |
760 | * @ns: the ipc namespace |
761 | * @ids: the table of ids where to look for the ipc |
762 | * @id: the id of the ipc to retrieve |
763 | * @cmd: the cmd to check |
764 | * @perm: the permission to set |
765 | * @extra_perm: one extra permission parameter used by msq |
766 | * |
767 | * This function does some common audit and permissions check for some IPC_XXX |
768 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. |
769 | * It must be called without any lock held and |
770 | * - retrieves the ipc with the given id in the given table. |
771 | * - performs some audit and permission check, depending on the given cmd |
772 | * - returns the ipc with both ipc and rw_mutex locks held in case of success |
773 | * or an err-code without any lock held otherwise. |
774 | */ |
775 | struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns, |
776 | struct ipc_ids *ids, int id, int cmd, |
777 | struct ipc64_perm *perm, int extra_perm) |
778 | { |
779 | struct kern_ipc_perm *ipcp; |
780 | uid_t euid; |
781 | int err; |
782 | |
783 | down_write(&ids->rw_mutex); |
784 | ipcp = ipc_lock_check(ids, id); |
785 | if (IS_ERR(ipcp)) { |
786 | err = PTR_ERR(ipcp); |
787 | goto out_up; |
788 | } |
789 | |
790 | audit_ipc_obj(ipcp); |
791 | if (cmd == IPC_SET) |
792 | audit_ipc_set_perm(extra_perm, perm->uid, |
793 | perm->gid, perm->mode); |
794 | |
795 | euid = current_euid(); |
796 | if (euid == ipcp->cuid || euid == ipcp->uid || |
797 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) |
798 | return ipcp; |
799 | |
800 | err = -EPERM; |
801 | ipc_unlock(ipcp); |
802 | out_up: |
803 | up_write(&ids->rw_mutex); |
804 | return ERR_PTR(err); |
805 | } |
806 | |
807 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION |
808 | |
809 | |
810 | /** |
811 | * ipc_parse_version - IPC call version |
812 | * @cmd: pointer to command |
813 | * |
814 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. |
815 | * The @cmd value is turned from an encoding command and version into |
816 | * just the command code. |
817 | */ |
818 | |
819 | int ipc_parse_version (int *cmd) |
820 | { |
821 | if (*cmd & IPC_64) { |
822 | *cmd ^= IPC_64; |
823 | return IPC_64; |
824 | } else { |
825 | return IPC_OLD; |
826 | } |
827 | } |
828 | |
829 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ |
830 | |
831 | #ifdef CONFIG_PROC_FS |
832 | struct ipc_proc_iter { |
833 | struct ipc_namespace *ns; |
834 | struct ipc_proc_iface *iface; |
835 | }; |
836 | |
837 | /* |
838 | * This routine locks the ipc structure found at least at position pos. |
839 | */ |
840 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, |
841 | loff_t *new_pos) |
842 | { |
843 | struct kern_ipc_perm *ipc; |
844 | int total, id; |
845 | |
846 | total = 0; |
847 | for (id = 0; id < pos && total < ids->in_use; id++) { |
848 | ipc = idr_find(&ids->ipcs_idr, id); |
849 | if (ipc != NULL) |
850 | total++; |
851 | } |
852 | |
853 | if (total >= ids->in_use) |
854 | return NULL; |
855 | |
856 | for ( ; pos < IPCMNI; pos++) { |
857 | ipc = idr_find(&ids->ipcs_idr, pos); |
858 | if (ipc != NULL) { |
859 | *new_pos = pos + 1; |
860 | ipc_lock_by_ptr(ipc); |
861 | return ipc; |
862 | } |
863 | } |
864 | |
865 | /* Out of range - return NULL to terminate iteration */ |
866 | return NULL; |
867 | } |
868 | |
869 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) |
870 | { |
871 | struct ipc_proc_iter *iter = s->private; |
872 | struct ipc_proc_iface *iface = iter->iface; |
873 | struct kern_ipc_perm *ipc = it; |
874 | |
875 | /* If we had an ipc id locked before, unlock it */ |
876 | if (ipc && ipc != SEQ_START_TOKEN) |
877 | ipc_unlock(ipc); |
878 | |
879 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); |
880 | } |
881 | |
882 | /* |
883 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. |
884 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. |
885 | */ |
886 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) |
887 | { |
888 | struct ipc_proc_iter *iter = s->private; |
889 | struct ipc_proc_iface *iface = iter->iface; |
890 | struct ipc_ids *ids; |
891 | |
892 | ids = &iter->ns->ids[iface->ids]; |
893 | |
894 | /* |
895 | * Take the lock - this will be released by the corresponding |
896 | * call to stop(). |
897 | */ |
898 | down_read(&ids->rw_mutex); |
899 | |
900 | /* pos < 0 is invalid */ |
901 | if (*pos < 0) |
902 | return NULL; |
903 | |
904 | /* pos == 0 means header */ |
905 | if (*pos == 0) |
906 | return SEQ_START_TOKEN; |
907 | |
908 | /* Find the (pos-1)th ipc */ |
909 | return sysvipc_find_ipc(ids, *pos - 1, pos); |
910 | } |
911 | |
912 | static void sysvipc_proc_stop(struct seq_file *s, void *it) |
913 | { |
914 | struct kern_ipc_perm *ipc = it; |
915 | struct ipc_proc_iter *iter = s->private; |
916 | struct ipc_proc_iface *iface = iter->iface; |
917 | struct ipc_ids *ids; |
918 | |
919 | /* If we had a locked structure, release it */ |
920 | if (ipc && ipc != SEQ_START_TOKEN) |
921 | ipc_unlock(ipc); |
922 | |
923 | ids = &iter->ns->ids[iface->ids]; |
924 | /* Release the lock we took in start() */ |
925 | up_read(&ids->rw_mutex); |
926 | } |
927 | |
928 | static int sysvipc_proc_show(struct seq_file *s, void *it) |
929 | { |
930 | struct ipc_proc_iter *iter = s->private; |
931 | struct ipc_proc_iface *iface = iter->iface; |
932 | |
933 | if (it == SEQ_START_TOKEN) |
934 | return seq_puts(s, iface->header); |
935 | |
936 | return iface->show(s, it); |
937 | } |
938 | |
939 | static const struct seq_operations sysvipc_proc_seqops = { |
940 | .start = sysvipc_proc_start, |
941 | .stop = sysvipc_proc_stop, |
942 | .next = sysvipc_proc_next, |
943 | .show = sysvipc_proc_show, |
944 | }; |
945 | |
946 | static int sysvipc_proc_open(struct inode *inode, struct file *file) |
947 | { |
948 | int ret; |
949 | struct seq_file *seq; |
950 | struct ipc_proc_iter *iter; |
951 | |
952 | ret = -ENOMEM; |
953 | iter = kmalloc(sizeof(*iter), GFP_KERNEL); |
954 | if (!iter) |
955 | goto out; |
956 | |
957 | ret = seq_open(file, &sysvipc_proc_seqops); |
958 | if (ret) |
959 | goto out_kfree; |
960 | |
961 | seq = file->private_data; |
962 | seq->private = iter; |
963 | |
964 | iter->iface = PDE(inode)->data; |
965 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); |
966 | out: |
967 | return ret; |
968 | out_kfree: |
969 | kfree(iter); |
970 | goto out; |
971 | } |
972 | |
973 | static int sysvipc_proc_release(struct inode *inode, struct file *file) |
974 | { |
975 | struct seq_file *seq = file->private_data; |
976 | struct ipc_proc_iter *iter = seq->private; |
977 | put_ipc_ns(iter->ns); |
978 | return seq_release_private(inode, file); |
979 | } |
980 | |
981 | static const struct file_operations sysvipc_proc_fops = { |
982 | .open = sysvipc_proc_open, |
983 | .read = seq_read, |
984 | .llseek = seq_lseek, |
985 | .release = sysvipc_proc_release, |
986 | }; |
987 | #endif /* CONFIG_PROC_FS */ |
988 |
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