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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 | /** | |
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 | id = idr_alloc(&ids->ipcs_idr, new, | |
241 | (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, | |
242 | GFP_NOWAIT); | |
243 | idr_preload_end(); | |
244 | if (id < 0) { | |
245 | spin_unlock(&new->lock); | |
246 | rcu_read_unlock(); | |
247 | return id; | |
248 | } | |
249 | ||
250 | ids->in_use++; | |
251 | ||
252 | current_euid_egid(&euid, &egid); | |
253 | new->cuid = new->uid = euid; | |
254 | new->gid = new->cgid = egid; | |
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 | * @size: size of block | |
418 | * | |
419 | * Free a block created with ipc_alloc(). The caller must know the size | |
420 | * used in the allocation call. | |
421 | */ | |
422 | void ipc_free(void *ptr, int size) | |
423 | { | |
424 | if (size > PAGE_SIZE) | |
425 | vfree(ptr); | |
426 | else | |
427 | kfree(ptr); | |
428 | } | |
429 | ||
430 | /** | |
431 | * ipc_rcu_alloc - allocate ipc and rcu space | |
432 | * @size: size desired | |
433 | * | |
434 | * Allocate memory for the rcu header structure + the object. | |
435 | * Returns the pointer to the object or NULL upon failure. | |
436 | */ | |
437 | void *ipc_rcu_alloc(int size) | |
438 | { | |
439 | /* | |
440 | * We prepend the allocation with the rcu struct | |
441 | */ | |
442 | struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size); | |
443 | if (unlikely(!out)) | |
444 | return NULL; | |
445 | atomic_set(&out->refcount, 1); | |
446 | return out + 1; | |
447 | } | |
448 | ||
449 | int ipc_rcu_getref(void *ptr) | |
450 | { | |
451 | struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; | |
452 | ||
453 | return atomic_inc_not_zero(&p->refcount); | |
454 | } | |
455 | ||
456 | void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head)) | |
457 | { | |
458 | struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; | |
459 | ||
460 | if (!atomic_dec_and_test(&p->refcount)) | |
461 | return; | |
462 | ||
463 | call_rcu(&p->rcu, func); | |
464 | } | |
465 | ||
466 | void ipc_rcu_free(struct rcu_head *head) | |
467 | { | |
468 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); | |
469 | ||
470 | if (is_vmalloc_addr(p)) | |
471 | vfree(p); | |
472 | else | |
473 | kfree(p); | |
474 | } | |
475 | ||
476 | /** | |
477 | * ipcperms - check ipc permissions | |
478 | * @ns: ipc namespace | |
479 | * @ipcp: ipc permission set | |
480 | * @flag: desired permission set | |
481 | * | |
482 | * Check user, group, other permissions for access | |
483 | * to ipc resources. return 0 if allowed | |
484 | * | |
485 | * @flag will most probably be 0 or S_...UGO from <linux/stat.h> | |
486 | */ | |
487 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) | |
488 | { | |
489 | kuid_t euid = current_euid(); | |
490 | int requested_mode, granted_mode; | |
491 | ||
492 | audit_ipc_obj(ipcp); | |
493 | requested_mode = (flag >> 6) | (flag >> 3) | flag; | |
494 | granted_mode = ipcp->mode; | |
495 | if (uid_eq(euid, ipcp->cuid) || | |
496 | uid_eq(euid, ipcp->uid)) | |
497 | granted_mode >>= 6; | |
498 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) | |
499 | granted_mode >>= 3; | |
500 | /* is there some bit set in requested_mode but not in granted_mode? */ | |
501 | if ((requested_mode & ~granted_mode & 0007) && | |
502 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) | |
503 | return -1; | |
504 | ||
505 | return security_ipc_permission(ipcp, flag); | |
506 | } | |
507 | ||
508 | /* | |
509 | * Functions to convert between the kern_ipc_perm structure and the | |
510 | * old/new ipc_perm structures | |
511 | */ | |
512 | ||
513 | /** | |
514 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user | |
515 | * @in: kernel permissions | |
516 | * @out: new style ipc permissions | |
517 | * | |
518 | * Turn the kernel object @in into a set of permissions descriptions | |
519 | * for returning to userspace (@out). | |
520 | */ | |
521 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) | |
522 | { | |
523 | out->key = in->key; | |
524 | out->uid = from_kuid_munged(current_user_ns(), in->uid); | |
525 | out->gid = from_kgid_munged(current_user_ns(), in->gid); | |
526 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); | |
527 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); | |
528 | out->mode = in->mode; | |
529 | out->seq = in->seq; | |
530 | } | |
531 | ||
532 | /** | |
533 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old | |
534 | * @in: new style ipc permissions | |
535 | * @out: old style ipc permissions | |
536 | * | |
537 | * Turn the new style permissions object @in into a compatibility | |
538 | * object and store it into the @out pointer. | |
539 | */ | |
540 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) | |
541 | { | |
542 | out->key = in->key; | |
543 | SET_UID(out->uid, in->uid); | |
544 | SET_GID(out->gid, in->gid); | |
545 | SET_UID(out->cuid, in->cuid); | |
546 | SET_GID(out->cgid, in->cgid); | |
547 | out->mode = in->mode; | |
548 | out->seq = in->seq; | |
549 | } | |
550 | ||
551 | /** | |
552 | * ipc_obtain_object | |
553 | * @ids: ipc identifier set | |
554 | * @id: ipc id to look for | |
555 | * | |
556 | * Look for an id in the ipc ids idr and return associated ipc object. | |
557 | * | |
558 | * Call inside the RCU critical section. | |
559 | * The ipc object is *not* locked on exit. | |
560 | */ | |
561 | struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id) | |
562 | { | |
563 | struct kern_ipc_perm *out; | |
564 | int lid = ipcid_to_idx(id); | |
565 | ||
566 | out = idr_find(&ids->ipcs_idr, lid); | |
567 | if (!out) | |
568 | return ERR_PTR(-EINVAL); | |
569 | ||
570 | return out; | |
571 | } | |
572 | ||
573 | /** | |
574 | * ipc_lock - lock an ipc structure without rwsem held | |
575 | * @ids: ipc identifier set | |
576 | * @id: ipc id to look for | |
577 | * | |
578 | * Look for an id in the ipc ids idr and lock the associated ipc object. | |
579 | * | |
580 | * The ipc object is locked on successful exit. | |
581 | */ | |
582 | struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) | |
583 | { | |
584 | struct kern_ipc_perm *out; | |
585 | ||
586 | rcu_read_lock(); | |
587 | out = ipc_obtain_object(ids, id); | |
588 | if (IS_ERR(out)) | |
589 | goto err1; | |
590 | ||
591 | spin_lock(&out->lock); | |
592 | ||
593 | /* ipc_rmid() may have already freed the ID while ipc_lock | |
594 | * was spinning: here verify that the structure is still valid | |
595 | */ | |
596 | if (ipc_valid_object(out)) | |
597 | return out; | |
598 | ||
599 | spin_unlock(&out->lock); | |
600 | out = ERR_PTR(-EINVAL); | |
601 | err1: | |
602 | rcu_read_unlock(); | |
603 | return out; | |
604 | } | |
605 | ||
606 | /** | |
607 | * ipc_obtain_object_check | |
608 | * @ids: ipc identifier set | |
609 | * @id: ipc id to look for | |
610 | * | |
611 | * Similar to ipc_obtain_object() but also checks | |
612 | * the ipc object reference counter. | |
613 | * | |
614 | * Call inside the RCU critical section. | |
615 | * The ipc object is *not* locked on exit. | |
616 | */ | |
617 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) | |
618 | { | |
619 | struct kern_ipc_perm *out = ipc_obtain_object(ids, id); | |
620 | ||
621 | if (IS_ERR(out)) | |
622 | goto out; | |
623 | ||
624 | if (ipc_checkid(out, id)) | |
625 | return ERR_PTR(-EIDRM); | |
626 | out: | |
627 | return out; | |
628 | } | |
629 | ||
630 | /** | |
631 | * ipcget - Common sys_*get() code | |
632 | * @ns: namespace | |
633 | * @ids: ipc identifier set | |
634 | * @ops: operations to be called on ipc object creation, permission checks | |
635 | * and further checks | |
636 | * @params: the parameters needed by the previous operations. | |
637 | * | |
638 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). | |
639 | */ | |
640 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, | |
641 | const struct ipc_ops *ops, struct ipc_params *params) | |
642 | { | |
643 | if (params->key == IPC_PRIVATE) | |
644 | return ipcget_new(ns, ids, ops, params); | |
645 | else | |
646 | return ipcget_public(ns, ids, ops, params); | |
647 | } | |
648 | ||
649 | /** | |
650 | * ipc_update_perm - update the permissions of an ipc object | |
651 | * @in: the permission given as input. | |
652 | * @out: the permission of the ipc to set. | |
653 | */ | |
654 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) | |
655 | { | |
656 | kuid_t uid = make_kuid(current_user_ns(), in->uid); | |
657 | kgid_t gid = make_kgid(current_user_ns(), in->gid); | |
658 | if (!uid_valid(uid) || !gid_valid(gid)) | |
659 | return -EINVAL; | |
660 | ||
661 | out->uid = uid; | |
662 | out->gid = gid; | |
663 | out->mode = (out->mode & ~S_IRWXUGO) | |
664 | | (in->mode & S_IRWXUGO); | |
665 | ||
666 | return 0; | |
667 | } | |
668 | ||
669 | /** | |
670 | * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd | |
671 | * @ns: ipc namespace | |
672 | * @ids: the table of ids where to look for the ipc | |
673 | * @id: the id of the ipc to retrieve | |
674 | * @cmd: the cmd to check | |
675 | * @perm: the permission to set | |
676 | * @extra_perm: one extra permission parameter used by msq | |
677 | * | |
678 | * This function does some common audit and permissions check for some IPC_XXX | |
679 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. | |
680 | * It must be called without any lock held and | |
681 | * - retrieves the ipc with the given id in the given table. | |
682 | * - performs some audit and permission check, depending on the given cmd | |
683 | * - returns a pointer to the ipc object or otherwise, the corresponding error. | |
684 | * | |
685 | * Call holding the both the rwsem and the rcu read lock. | |
686 | */ | |
687 | struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, | |
688 | struct ipc_ids *ids, int id, int cmd, | |
689 | struct ipc64_perm *perm, int extra_perm) | |
690 | { | |
691 | kuid_t euid; | |
692 | int err = -EPERM; | |
693 | struct kern_ipc_perm *ipcp; | |
694 | ||
695 | ipcp = ipc_obtain_object_check(ids, id); | |
696 | if (IS_ERR(ipcp)) { | |
697 | err = PTR_ERR(ipcp); | |
698 | goto err; | |
699 | } | |
700 | ||
701 | audit_ipc_obj(ipcp); | |
702 | if (cmd == IPC_SET) | |
703 | audit_ipc_set_perm(extra_perm, perm->uid, | |
704 | perm->gid, perm->mode); | |
705 | ||
706 | euid = current_euid(); | |
707 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || | |
708 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) | |
709 | return ipcp; /* successful lookup */ | |
710 | err: | |
711 | return ERR_PTR(err); | |
712 | } | |
713 | ||
714 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION | |
715 | ||
716 | ||
717 | /** | |
718 | * ipc_parse_version - ipc call version | |
719 | * @cmd: pointer to command | |
720 | * | |
721 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. | |
722 | * The @cmd value is turned from an encoding command and version into | |
723 | * just the command code. | |
724 | */ | |
725 | int ipc_parse_version(int *cmd) | |
726 | { | |
727 | if (*cmd & IPC_64) { | |
728 | *cmd ^= IPC_64; | |
729 | return IPC_64; | |
730 | } else { | |
731 | return IPC_OLD; | |
732 | } | |
733 | } | |
734 | ||
735 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ | |
736 | ||
737 | #ifdef CONFIG_PROC_FS | |
738 | struct ipc_proc_iter { | |
739 | struct ipc_namespace *ns; | |
740 | struct ipc_proc_iface *iface; | |
741 | }; | |
742 | ||
743 | /* | |
744 | * This routine locks the ipc structure found at least at position pos. | |
745 | */ | |
746 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, | |
747 | loff_t *new_pos) | |
748 | { | |
749 | struct kern_ipc_perm *ipc; | |
750 | int total, id; | |
751 | ||
752 | total = 0; | |
753 | for (id = 0; id < pos && total < ids->in_use; id++) { | |
754 | ipc = idr_find(&ids->ipcs_idr, id); | |
755 | if (ipc != NULL) | |
756 | total++; | |
757 | } | |
758 | ||
759 | if (total >= ids->in_use) | |
760 | return NULL; | |
761 | ||
762 | for (; pos < IPCMNI; pos++) { | |
763 | ipc = idr_find(&ids->ipcs_idr, pos); | |
764 | if (ipc != NULL) { | |
765 | *new_pos = pos + 1; | |
766 | rcu_read_lock(); | |
767 | ipc_lock_object(ipc); | |
768 | return ipc; | |
769 | } | |
770 | } | |
771 | ||
772 | /* Out of range - return NULL to terminate iteration */ | |
773 | return NULL; | |
774 | } | |
775 | ||
776 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) | |
777 | { | |
778 | struct ipc_proc_iter *iter = s->private; | |
779 | struct ipc_proc_iface *iface = iter->iface; | |
780 | struct kern_ipc_perm *ipc = it; | |
781 | ||
782 | /* If we had an ipc id locked before, unlock it */ | |
783 | if (ipc && ipc != SEQ_START_TOKEN) | |
784 | ipc_unlock(ipc); | |
785 | ||
786 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); | |
787 | } | |
788 | ||
789 | /* | |
790 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. | |
791 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. | |
792 | */ | |
793 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) | |
794 | { | |
795 | struct ipc_proc_iter *iter = s->private; | |
796 | struct ipc_proc_iface *iface = iter->iface; | |
797 | struct ipc_ids *ids; | |
798 | ||
799 | ids = &iter->ns->ids[iface->ids]; | |
800 | ||
801 | /* | |
802 | * Take the lock - this will be released by the corresponding | |
803 | * call to stop(). | |
804 | */ | |
805 | down_read(&ids->rwsem); | |
806 | ||
807 | /* pos < 0 is invalid */ | |
808 | if (*pos < 0) | |
809 | return NULL; | |
810 | ||
811 | /* pos == 0 means header */ | |
812 | if (*pos == 0) | |
813 | return SEQ_START_TOKEN; | |
814 | ||
815 | /* Find the (pos-1)th ipc */ | |
816 | return sysvipc_find_ipc(ids, *pos - 1, pos); | |
817 | } | |
818 | ||
819 | static void sysvipc_proc_stop(struct seq_file *s, void *it) | |
820 | { | |
821 | struct kern_ipc_perm *ipc = it; | |
822 | struct ipc_proc_iter *iter = s->private; | |
823 | struct ipc_proc_iface *iface = iter->iface; | |
824 | struct ipc_ids *ids; | |
825 | ||
826 | /* If we had a locked structure, release it */ | |
827 | if (ipc && ipc != SEQ_START_TOKEN) | |
828 | ipc_unlock(ipc); | |
829 | ||
830 | ids = &iter->ns->ids[iface->ids]; | |
831 | /* Release the lock we took in start() */ | |
832 | up_read(&ids->rwsem); | |
833 | } | |
834 | ||
835 | static int sysvipc_proc_show(struct seq_file *s, void *it) | |
836 | { | |
837 | struct ipc_proc_iter *iter = s->private; | |
838 | struct ipc_proc_iface *iface = iter->iface; | |
839 | ||
840 | if (it == SEQ_START_TOKEN) | |
841 | return seq_puts(s, iface->header); | |
842 | ||
843 | return iface->show(s, it); | |
844 | } | |
845 | ||
846 | static const struct seq_operations sysvipc_proc_seqops = { | |
847 | .start = sysvipc_proc_start, | |
848 | .stop = sysvipc_proc_stop, | |
849 | .next = sysvipc_proc_next, | |
850 | .show = sysvipc_proc_show, | |
851 | }; | |
852 | ||
853 | static int sysvipc_proc_open(struct inode *inode, struct file *file) | |
854 | { | |
855 | struct ipc_proc_iter *iter; | |
856 | ||
857 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); | |
858 | if (!iter) | |
859 | return -ENOMEM; | |
860 | ||
861 | iter->iface = PDE_DATA(inode); | |
862 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); | |
863 | ||
864 | return 0; | |
865 | } | |
866 | ||
867 | static int sysvipc_proc_release(struct inode *inode, struct file *file) | |
868 | { | |
869 | struct seq_file *seq = file->private_data; | |
870 | struct ipc_proc_iter *iter = seq->private; | |
871 | put_ipc_ns(iter->ns); | |
872 | return seq_release_private(inode, file); | |
873 | } | |
874 | ||
875 | static const struct file_operations sysvipc_proc_fops = { | |
876 | .open = sysvipc_proc_open, | |
877 | .read = seq_read, | |
878 | .llseek = seq_lseek, | |
879 | .release = sysvipc_proc_release, | |
880 | }; | |
881 | #endif /* CONFIG_PROC_FS */ |