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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * linux/ipc/util.c | |
4 | * Copyright (C) 1992 Krishna Balasubramanian | |
5 | * | |
6 | * Sep 1997 - Call suser() last after "normal" permission checks so we | |
7 | * get BSD style process accounting right. | |
8 | * Occurs in several places in the IPC code. | |
9 | * Chris Evans, <chris@ferret.lmh.ox.ac.uk> | |
10 | * Nov 1999 - ipc helper functions, unified SMP locking | |
11 | * Manfred Spraul <manfred@colorfullife.com> | |
12 | * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary(). | |
13 | * Mingming Cao <cmm@us.ibm.com> | |
14 | * Mar 2006 - support for audit of ipc object properties | |
15 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> | |
16 | * Jun 2006 - namespaces ssupport | |
17 | * OpenVZ, SWsoft Inc. | |
18 | * Pavel Emelianov <xemul@openvz.org> | |
19 | * | |
20 | * General sysv ipc locking scheme: | |
21 | * rcu_read_lock() | |
22 | * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr | |
23 | * tree. | |
24 | * - perform initial checks (capabilities, auditing and permission, | |
25 | * etc). | |
26 | * - perform read-only operations, such as STAT, INFO commands. | |
27 | * acquire the ipc lock (kern_ipc_perm.lock) through | |
28 | * ipc_lock_object() | |
29 | * - perform data updates, such as SET, RMID commands and | |
30 | * mechanism-specific operations (semop/semtimedop, | |
31 | * msgsnd/msgrcv, shmat/shmdt). | |
32 | * drop the ipc lock, through ipc_unlock_object(). | |
33 | * rcu_read_unlock() | |
34 | * | |
35 | * The ids->rwsem must be taken when: | |
36 | * - creating, removing and iterating the existing entries in ipc | |
37 | * identifier sets. | |
38 | * - iterating through files under /proc/sysvipc/ | |
39 | * | |
40 | * Note that sems have a special fast path that avoids kern_ipc_perm.lock - | |
41 | * see sem_lock(). | |
42 | */ | |
43 | ||
44 | #include <linux/mm.h> | |
45 | #include <linux/shm.h> | |
46 | #include <linux/init.h> | |
47 | #include <linux/msg.h> | |
48 | #include <linux/vmalloc.h> | |
49 | #include <linux/slab.h> | |
50 | #include <linux/notifier.h> | |
51 | #include <linux/capability.h> | |
52 | #include <linux/highuid.h> | |
53 | #include <linux/security.h> | |
54 | #include <linux/rcupdate.h> | |
55 | #include <linux/workqueue.h> | |
56 | #include <linux/seq_file.h> | |
57 | #include <linux/proc_fs.h> | |
58 | #include <linux/audit.h> | |
59 | #include <linux/nsproxy.h> | |
60 | #include <linux/rwsem.h> | |
61 | #include <linux/memory.h> | |
62 | #include <linux/ipc_namespace.h> | |
63 | ||
64 | #include <asm/unistd.h> | |
65 | ||
66 | #include "util.h" | |
67 | ||
68 | struct ipc_proc_iface { | |
69 | const char *path; | |
70 | const char *header; | |
71 | int ids; | |
72 | int (*show)(struct seq_file *, void *); | |
73 | }; | |
74 | ||
75 | /** | |
76 | * ipc_init - initialise ipc subsystem | |
77 | * | |
78 | * The various sysv ipc resources (semaphores, messages and shared | |
79 | * memory) are initialised. | |
80 | * | |
81 | * A callback routine is registered into the memory hotplug notifier | |
82 | * chain: since msgmni scales to lowmem this callback routine will be | |
83 | * called upon successful memory add / remove to recompute msmgni. | |
84 | */ | |
85 | static int __init ipc_init(void) | |
86 | { | |
87 | int err_sem, err_msg; | |
88 | ||
89 | err_sem = sem_init(); | |
90 | WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem); | |
91 | err_msg = msg_init(); | |
92 | WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg); | |
93 | shm_init(); | |
94 | ||
95 | return err_msg ? err_msg : err_sem; | |
96 | } | |
97 | device_initcall(ipc_init); | |
98 | ||
99 | static const struct rhashtable_params ipc_kht_params = { | |
100 | .head_offset = offsetof(struct kern_ipc_perm, khtnode), | |
101 | .key_offset = offsetof(struct kern_ipc_perm, key), | |
102 | .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key), | |
103 | .locks_mul = 1, | |
104 | .automatic_shrinking = true, | |
105 | }; | |
106 | ||
107 | /** | |
108 | * ipc_init_ids - initialise ipc identifiers | |
109 | * @ids: ipc identifier set | |
110 | * | |
111 | * Set up the sequence range to use for the ipc identifier range (limited | |
112 | * below IPCMNI) then initialise the keys hashtable and ids idr. | |
113 | */ | |
114 | int ipc_init_ids(struct ipc_ids *ids) | |
115 | { | |
116 | int err; | |
117 | ids->in_use = 0; | |
118 | ids->seq = 0; | |
119 | init_rwsem(&ids->rwsem); | |
120 | err = rhashtable_init(&ids->key_ht, &ipc_kht_params); | |
121 | if (err) | |
122 | return err; | |
123 | idr_init(&ids->ipcs_idr); | |
124 | ids->tables_initialized = true; | |
125 | ids->max_id = -1; | |
126 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
127 | ids->next_id = -1; | |
128 | #endif | |
129 | return 0; | |
130 | } | |
131 | ||
132 | #ifdef CONFIG_PROC_FS | |
133 | static const struct file_operations sysvipc_proc_fops; | |
134 | /** | |
135 | * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface. | |
136 | * @path: Path in procfs | |
137 | * @header: Banner to be printed at the beginning of the file. | |
138 | * @ids: ipc id table to iterate. | |
139 | * @show: show routine. | |
140 | */ | |
141 | void __init ipc_init_proc_interface(const char *path, const char *header, | |
142 | int ids, int (*show)(struct seq_file *, void *)) | |
143 | { | |
144 | struct proc_dir_entry *pde; | |
145 | struct ipc_proc_iface *iface; | |
146 | ||
147 | iface = kmalloc(sizeof(*iface), GFP_KERNEL); | |
148 | if (!iface) | |
149 | return; | |
150 | iface->path = path; | |
151 | iface->header = header; | |
152 | iface->ids = ids; | |
153 | iface->show = show; | |
154 | ||
155 | pde = proc_create_data(path, | |
156 | S_IRUGO, /* world readable */ | |
157 | NULL, /* parent dir */ | |
158 | &sysvipc_proc_fops, | |
159 | iface); | |
160 | if (!pde) | |
161 | kfree(iface); | |
162 | } | |
163 | #endif | |
164 | ||
165 | /** | |
166 | * ipc_findkey - find a key in an ipc identifier set | |
167 | * @ids: ipc identifier set | |
168 | * @key: key to find | |
169 | * | |
170 | * Returns the locked pointer to the ipc structure if found or NULL | |
171 | * otherwise. If key is found ipc points to the owning ipc structure | |
172 | * | |
173 | * Called with writer ipc_ids.rwsem held. | |
174 | */ | |
175 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) | |
176 | { | |
177 | struct kern_ipc_perm *ipcp = NULL; | |
178 | ||
179 | if (likely(ids->tables_initialized)) | |
180 | ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, | |
181 | ipc_kht_params); | |
182 | ||
183 | if (ipcp) { | |
184 | rcu_read_lock(); | |
185 | ipc_lock_object(ipcp); | |
186 | return ipcp; | |
187 | } | |
188 | ||
189 | return NULL; | |
190 | } | |
191 | ||
192 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
193 | /* | |
194 | * Specify desired id for next allocated IPC object. | |
195 | */ | |
196 | #define ipc_idr_alloc(ids, new) \ | |
197 | idr_alloc(&(ids)->ipcs_idr, (new), \ | |
198 | (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\ | |
199 | 0, GFP_NOWAIT) | |
200 | ||
201 | static inline int ipc_buildid(int id, struct ipc_ids *ids, | |
202 | struct kern_ipc_perm *new) | |
203 | { | |
204 | if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */ | |
205 | new->seq = ids->seq++; | |
206 | if (ids->seq > IPCID_SEQ_MAX) | |
207 | ids->seq = 0; | |
208 | } else { | |
209 | new->seq = ipcid_to_seqx(ids->next_id); | |
210 | ids->next_id = -1; | |
211 | } | |
212 | ||
213 | return SEQ_MULTIPLIER * new->seq + id; | |
214 | } | |
215 | ||
216 | #else | |
217 | #define ipc_idr_alloc(ids, new) \ | |
218 | idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT) | |
219 | ||
220 | static inline int ipc_buildid(int id, struct ipc_ids *ids, | |
221 | struct kern_ipc_perm *new) | |
222 | { | |
223 | new->seq = ids->seq++; | |
224 | if (ids->seq > IPCID_SEQ_MAX) | |
225 | ids->seq = 0; | |
226 | ||
227 | return SEQ_MULTIPLIER * new->seq + id; | |
228 | } | |
229 | ||
230 | #endif /* CONFIG_CHECKPOINT_RESTORE */ | |
231 | ||
232 | /** | |
233 | * ipc_addid - add an ipc identifier | |
234 | * @ids: ipc identifier set | |
235 | * @new: new ipc permission set | |
236 | * @limit: limit for the number of used ids | |
237 | * | |
238 | * Add an entry 'new' to the ipc ids idr. The permissions object is | |
239 | * initialised and the first free entry is set up and the id assigned | |
240 | * is returned. The 'new' entry is returned in a locked state on success. | |
241 | * On failure the entry is not locked and a negative err-code is returned. | |
242 | * | |
243 | * Called with writer ipc_ids.rwsem held. | |
244 | */ | |
245 | int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) | |
246 | { | |
247 | kuid_t euid; | |
248 | kgid_t egid; | |
249 | int id, err; | |
250 | ||
251 | if (limit > IPCMNI) | |
252 | limit = IPCMNI; | |
253 | ||
254 | if (!ids->tables_initialized || ids->in_use >= limit) | |
255 | return -ENOSPC; | |
256 | ||
257 | idr_preload(GFP_KERNEL); | |
258 | ||
259 | refcount_set(&new->refcount, 1); | |
260 | spin_lock_init(&new->lock); | |
261 | new->deleted = false; | |
262 | rcu_read_lock(); | |
263 | spin_lock(&new->lock); | |
264 | ||
265 | current_euid_egid(&euid, &egid); | |
266 | new->cuid = new->uid = euid; | |
267 | new->gid = new->cgid = egid; | |
268 | ||
269 | id = ipc_idr_alloc(ids, new); | |
270 | idr_preload_end(); | |
271 | ||
272 | if (id >= 0 && new->key != IPC_PRIVATE) { | |
273 | err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode, | |
274 | ipc_kht_params); | |
275 | if (err < 0) { | |
276 | idr_remove(&ids->ipcs_idr, id); | |
277 | id = err; | |
278 | } | |
279 | } | |
280 | if (id < 0) { | |
281 | spin_unlock(&new->lock); | |
282 | rcu_read_unlock(); | |
283 | return id; | |
284 | } | |
285 | ||
286 | ids->in_use++; | |
287 | if (id > ids->max_id) | |
288 | ids->max_id = id; | |
289 | ||
290 | new->id = ipc_buildid(id, ids, new); | |
291 | ||
292 | return id; | |
293 | } | |
294 | ||
295 | /** | |
296 | * ipcget_new - create a new ipc object | |
297 | * @ns: ipc namespace | |
298 | * @ids: ipc identifier set | |
299 | * @ops: the actual creation routine to call | |
300 | * @params: its parameters | |
301 | * | |
302 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
303 | * when the key is IPC_PRIVATE. | |
304 | */ | |
305 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, | |
306 | const struct ipc_ops *ops, struct ipc_params *params) | |
307 | { | |
308 | int err; | |
309 | ||
310 | down_write(&ids->rwsem); | |
311 | err = ops->getnew(ns, params); | |
312 | up_write(&ids->rwsem); | |
313 | return err; | |
314 | } | |
315 | ||
316 | /** | |
317 | * ipc_check_perms - check security and permissions for an ipc object | |
318 | * @ns: ipc namespace | |
319 | * @ipcp: ipc permission set | |
320 | * @ops: the actual security routine to call | |
321 | * @params: its parameters | |
322 | * | |
323 | * This routine is called by sys_msgget(), sys_semget() and sys_shmget() | |
324 | * when the key is not IPC_PRIVATE and that key already exists in the | |
325 | * ds IDR. | |
326 | * | |
327 | * On success, the ipc id is returned. | |
328 | * | |
329 | * It is called with ipc_ids.rwsem and ipcp->lock held. | |
330 | */ | |
331 | static int ipc_check_perms(struct ipc_namespace *ns, | |
332 | struct kern_ipc_perm *ipcp, | |
333 | const struct ipc_ops *ops, | |
334 | struct ipc_params *params) | |
335 | { | |
336 | int err; | |
337 | ||
338 | if (ipcperms(ns, ipcp, params->flg)) | |
339 | err = -EACCES; | |
340 | else { | |
341 | err = ops->associate(ipcp, params->flg); | |
342 | if (!err) | |
343 | err = ipcp->id; | |
344 | } | |
345 | ||
346 | return err; | |
347 | } | |
348 | ||
349 | /** | |
350 | * ipcget_public - get an ipc object or create a new one | |
351 | * @ns: ipc namespace | |
352 | * @ids: ipc identifier set | |
353 | * @ops: the actual creation routine to call | |
354 | * @params: its parameters | |
355 | * | |
356 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
357 | * when the key is not IPC_PRIVATE. | |
358 | * It adds a new entry if the key is not found and does some permission | |
359 | * / security checkings if the key is found. | |
360 | * | |
361 | * On success, the ipc id is returned. | |
362 | */ | |
363 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, | |
364 | const struct ipc_ops *ops, struct ipc_params *params) | |
365 | { | |
366 | struct kern_ipc_perm *ipcp; | |
367 | int flg = params->flg; | |
368 | int err; | |
369 | ||
370 | /* | |
371 | * Take the lock as a writer since we are potentially going to add | |
372 | * a new entry + read locks are not "upgradable" | |
373 | */ | |
374 | down_write(&ids->rwsem); | |
375 | ipcp = ipc_findkey(ids, params->key); | |
376 | if (ipcp == NULL) { | |
377 | /* key not used */ | |
378 | if (!(flg & IPC_CREAT)) | |
379 | err = -ENOENT; | |
380 | else | |
381 | err = ops->getnew(ns, params); | |
382 | } else { | |
383 | /* ipc object has been locked by ipc_findkey() */ | |
384 | ||
385 | if (flg & IPC_CREAT && flg & IPC_EXCL) | |
386 | err = -EEXIST; | |
387 | else { | |
388 | err = 0; | |
389 | if (ops->more_checks) | |
390 | err = ops->more_checks(ipcp, params); | |
391 | if (!err) | |
392 | /* | |
393 | * ipc_check_perms returns the IPC id on | |
394 | * success | |
395 | */ | |
396 | err = ipc_check_perms(ns, ipcp, ops, params); | |
397 | } | |
398 | ipc_unlock(ipcp); | |
399 | } | |
400 | up_write(&ids->rwsem); | |
401 | ||
402 | return err; | |
403 | } | |
404 | ||
405 | /** | |
406 | * ipc_kht_remove - remove an ipc from the key hashtable | |
407 | * @ids: ipc identifier set | |
408 | * @ipcp: ipc perm structure containing the key to remove | |
409 | * | |
410 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
411 | * before this function is called, and remain locked on the exit. | |
412 | */ | |
413 | static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
414 | { | |
415 | if (ipcp->key != IPC_PRIVATE) | |
416 | rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, | |
417 | ipc_kht_params); | |
418 | } | |
419 | ||
420 | /** | |
421 | * ipc_rmid - remove an ipc identifier | |
422 | * @ids: ipc identifier set | |
423 | * @ipcp: ipc perm structure containing the identifier to remove | |
424 | * | |
425 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
426 | * before this function is called, and remain locked on the exit. | |
427 | */ | |
428 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
429 | { | |
430 | int lid = ipcid_to_idx(ipcp->id); | |
431 | ||
432 | idr_remove(&ids->ipcs_idr, lid); | |
433 | ipc_kht_remove(ids, ipcp); | |
434 | ids->in_use--; | |
435 | ipcp->deleted = true; | |
436 | ||
437 | if (unlikely(lid == ids->max_id)) { | |
438 | do { | |
439 | lid--; | |
440 | if (lid == -1) | |
441 | break; | |
442 | } while (!idr_find(&ids->ipcs_idr, lid)); | |
443 | ids->max_id = lid; | |
444 | } | |
445 | } | |
446 | ||
447 | /** | |
448 | * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE | |
449 | * @ids: ipc identifier set | |
450 | * @ipcp: ipc perm structure containing the key to modify | |
451 | * | |
452 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
453 | * before this function is called, and remain locked on the exit. | |
454 | */ | |
455 | void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
456 | { | |
457 | ipc_kht_remove(ids, ipcp); | |
458 | ipcp->key = IPC_PRIVATE; | |
459 | } | |
460 | ||
461 | int ipc_rcu_getref(struct kern_ipc_perm *ptr) | |
462 | { | |
463 | return refcount_inc_not_zero(&ptr->refcount); | |
464 | } | |
465 | ||
466 | void ipc_rcu_putref(struct kern_ipc_perm *ptr, | |
467 | void (*func)(struct rcu_head *head)) | |
468 | { | |
469 | if (!refcount_dec_and_test(&ptr->refcount)) | |
470 | return; | |
471 | ||
472 | call_rcu(&ptr->rcu, func); | |
473 | } | |
474 | ||
475 | /** | |
476 | * ipcperms - check ipc permissions | |
477 | * @ns: ipc namespace | |
478 | * @ipcp: ipc permission set | |
479 | * @flag: desired permission set | |
480 | * | |
481 | * Check user, group, other permissions for access | |
482 | * to ipc resources. return 0 if allowed | |
483 | * | |
484 | * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h> | |
485 | */ | |
486 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) | |
487 | { | |
488 | kuid_t euid = current_euid(); | |
489 | int requested_mode, granted_mode; | |
490 | ||
491 | audit_ipc_obj(ipcp); | |
492 | requested_mode = (flag >> 6) | (flag >> 3) | flag; | |
493 | granted_mode = ipcp->mode; | |
494 | if (uid_eq(euid, ipcp->cuid) || | |
495 | uid_eq(euid, ipcp->uid)) | |
496 | granted_mode >>= 6; | |
497 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) | |
498 | granted_mode >>= 3; | |
499 | /* is there some bit set in requested_mode but not in granted_mode? */ | |
500 | if ((requested_mode & ~granted_mode & 0007) && | |
501 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) | |
502 | return -1; | |
503 | ||
504 | return security_ipc_permission(ipcp, flag); | |
505 | } | |
506 | ||
507 | /* | |
508 | * Functions to convert between the kern_ipc_perm structure and the | |
509 | * old/new ipc_perm structures | |
510 | */ | |
511 | ||
512 | /** | |
513 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user | |
514 | * @in: kernel permissions | |
515 | * @out: new style ipc permissions | |
516 | * | |
517 | * Turn the kernel object @in into a set of permissions descriptions | |
518 | * for returning to userspace (@out). | |
519 | */ | |
520 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) | |
521 | { | |
522 | out->key = in->key; | |
523 | out->uid = from_kuid_munged(current_user_ns(), in->uid); | |
524 | out->gid = from_kgid_munged(current_user_ns(), in->gid); | |
525 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); | |
526 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); | |
527 | out->mode = in->mode; | |
528 | out->seq = in->seq; | |
529 | } | |
530 | ||
531 | /** | |
532 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old | |
533 | * @in: new style ipc permissions | |
534 | * @out: old style ipc permissions | |
535 | * | |
536 | * Turn the new style permissions object @in into a compatibility | |
537 | * object and store it into the @out pointer. | |
538 | */ | |
539 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) | |
540 | { | |
541 | out->key = in->key; | |
542 | SET_UID(out->uid, in->uid); | |
543 | SET_GID(out->gid, in->gid); | |
544 | SET_UID(out->cuid, in->cuid); | |
545 | SET_GID(out->cgid, in->cgid); | |
546 | out->mode = in->mode; | |
547 | out->seq = in->seq; | |
548 | } | |
549 | ||
550 | /** | |
551 | * ipc_obtain_object_idr | |
552 | * @ids: ipc identifier set | |
553 | * @id: ipc id to look for | |
554 | * | |
555 | * Look for an id in the ipc ids idr and return associated ipc object. | |
556 | * | |
557 | * Call inside the RCU critical section. | |
558 | * The ipc object is *not* locked on exit. | |
559 | */ | |
560 | struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) | |
561 | { | |
562 | struct kern_ipc_perm *out; | |
563 | int lid = ipcid_to_idx(id); | |
564 | ||
565 | if (unlikely(!ids->tables_initialized)) | |
566 | return ERR_PTR(-EINVAL); | |
567 | ||
568 | out = idr_find(&ids->ipcs_idr, lid); | |
569 | if (!out) | |
570 | return ERR_PTR(-EINVAL); | |
571 | ||
572 | return out; | |
573 | } | |
574 | ||
575 | /** | |
576 | * ipc_lock - lock an ipc structure without rwsem held | |
577 | * @ids: ipc identifier set | |
578 | * @id: ipc id to look for | |
579 | * | |
580 | * Look for an id in the ipc ids idr and lock the associated ipc object. | |
581 | * | |
582 | * The ipc object is locked on successful exit. | |
583 | */ | |
584 | struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) | |
585 | { | |
586 | struct kern_ipc_perm *out; | |
587 | ||
588 | rcu_read_lock(); | |
589 | out = ipc_obtain_object_idr(ids, id); | |
590 | if (IS_ERR(out)) | |
591 | goto err; | |
592 | ||
593 | spin_lock(&out->lock); | |
594 | ||
595 | /* | |
596 | * ipc_rmid() may have already freed the ID while ipc_lock() | |
597 | * was spinning: here verify that the structure is still valid. | |
598 | * Upon races with RMID, return -EIDRM, thus indicating that | |
599 | * the ID points to a removed identifier. | |
600 | */ | |
601 | if (ipc_valid_object(out)) | |
602 | return out; | |
603 | ||
604 | spin_unlock(&out->lock); | |
605 | out = ERR_PTR(-EIDRM); | |
606 | err: | |
607 | rcu_read_unlock(); | |
608 | return out; | |
609 | } | |
610 | ||
611 | /** | |
612 | * ipc_obtain_object_check | |
613 | * @ids: ipc identifier set | |
614 | * @id: ipc id to look for | |
615 | * | |
616 | * Similar to ipc_obtain_object_idr() but also checks | |
617 | * the ipc object reference counter. | |
618 | * | |
619 | * Call inside the RCU critical section. | |
620 | * The ipc object is *not* locked on exit. | |
621 | */ | |
622 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) | |
623 | { | |
624 | struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id); | |
625 | ||
626 | if (IS_ERR(out)) | |
627 | goto out; | |
628 | ||
629 | if (ipc_checkid(out, id)) | |
630 | return ERR_PTR(-EINVAL); | |
631 | out: | |
632 | return out; | |
633 | } | |
634 | ||
635 | /** | |
636 | * ipcget - Common sys_*get() code | |
637 | * @ns: namespace | |
638 | * @ids: ipc identifier set | |
639 | * @ops: operations to be called on ipc object creation, permission checks | |
640 | * and further checks | |
641 | * @params: the parameters needed by the previous operations. | |
642 | * | |
643 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). | |
644 | */ | |
645 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, | |
646 | const struct ipc_ops *ops, struct ipc_params *params) | |
647 | { | |
648 | if (params->key == IPC_PRIVATE) | |
649 | return ipcget_new(ns, ids, ops, params); | |
650 | else | |
651 | return ipcget_public(ns, ids, ops, params); | |
652 | } | |
653 | ||
654 | /** | |
655 | * ipc_update_perm - update the permissions of an ipc object | |
656 | * @in: the permission given as input. | |
657 | * @out: the permission of the ipc to set. | |
658 | */ | |
659 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) | |
660 | { | |
661 | kuid_t uid = make_kuid(current_user_ns(), in->uid); | |
662 | kgid_t gid = make_kgid(current_user_ns(), in->gid); | |
663 | if (!uid_valid(uid) || !gid_valid(gid)) | |
664 | return -EINVAL; | |
665 | ||
666 | out->uid = uid; | |
667 | out->gid = gid; | |
668 | out->mode = (out->mode & ~S_IRWXUGO) | |
669 | | (in->mode & S_IRWXUGO); | |
670 | ||
671 | return 0; | |
672 | } | |
673 | ||
674 | /** | |
675 | * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd | |
676 | * @ns: ipc namespace | |
677 | * @ids: the table of ids where to look for the ipc | |
678 | * @id: the id of the ipc to retrieve | |
679 | * @cmd: the cmd to check | |
680 | * @perm: the permission to set | |
681 | * @extra_perm: one extra permission parameter used by msq | |
682 | * | |
683 | * This function does some common audit and permissions check for some IPC_XXX | |
684 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. | |
685 | * It must be called without any lock held and: | |
686 | * | |
687 | * - retrieves the ipc with the given id in the given table. | |
688 | * - performs some audit and permission check, depending on the given cmd | |
689 | * - returns a pointer to the ipc object or otherwise, the corresponding | |
690 | * error. | |
691 | * | |
692 | * Call holding the both the rwsem and the rcu read lock. | |
693 | */ | |
694 | struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, | |
695 | struct ipc_ids *ids, int id, int cmd, | |
696 | struct ipc64_perm *perm, int extra_perm) | |
697 | { | |
698 | kuid_t euid; | |
699 | int err = -EPERM; | |
700 | struct kern_ipc_perm *ipcp; | |
701 | ||
702 | ipcp = ipc_obtain_object_check(ids, id); | |
703 | if (IS_ERR(ipcp)) { | |
704 | err = PTR_ERR(ipcp); | |
705 | goto err; | |
706 | } | |
707 | ||
708 | audit_ipc_obj(ipcp); | |
709 | if (cmd == IPC_SET) | |
710 | audit_ipc_set_perm(extra_perm, perm->uid, | |
711 | perm->gid, perm->mode); | |
712 | ||
713 | euid = current_euid(); | |
714 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || | |
715 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) | |
716 | return ipcp; /* successful lookup */ | |
717 | err: | |
718 | return ERR_PTR(err); | |
719 | } | |
720 | ||
721 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION | |
722 | ||
723 | ||
724 | /** | |
725 | * ipc_parse_version - ipc call version | |
726 | * @cmd: pointer to command | |
727 | * | |
728 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. | |
729 | * The @cmd value is turned from an encoding command and version into | |
730 | * just the command code. | |
731 | */ | |
732 | int ipc_parse_version(int *cmd) | |
733 | { | |
734 | if (*cmd & IPC_64) { | |
735 | *cmd ^= IPC_64; | |
736 | return IPC_64; | |
737 | } else { | |
738 | return IPC_OLD; | |
739 | } | |
740 | } | |
741 | ||
742 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ | |
743 | ||
744 | #ifdef CONFIG_PROC_FS | |
745 | struct ipc_proc_iter { | |
746 | struct ipc_namespace *ns; | |
747 | struct ipc_proc_iface *iface; | |
748 | }; | |
749 | ||
750 | /* | |
751 | * This routine locks the ipc structure found at least at position pos. | |
752 | */ | |
753 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, | |
754 | loff_t *new_pos) | |
755 | { | |
756 | struct kern_ipc_perm *ipc; | |
757 | int total, id; | |
758 | ||
759 | total = 0; | |
760 | for (id = 0; id < pos && total < ids->in_use; id++) { | |
761 | ipc = idr_find(&ids->ipcs_idr, id); | |
762 | if (ipc != NULL) | |
763 | total++; | |
764 | } | |
765 | ||
766 | if (total >= ids->in_use) | |
767 | return NULL; | |
768 | ||
769 | for (; pos < IPCMNI; pos++) { | |
770 | ipc = idr_find(&ids->ipcs_idr, pos); | |
771 | if (ipc != NULL) { | |
772 | *new_pos = pos + 1; | |
773 | rcu_read_lock(); | |
774 | ipc_lock_object(ipc); | |
775 | return ipc; | |
776 | } | |
777 | } | |
778 | ||
779 | /* Out of range - return NULL to terminate iteration */ | |
780 | return NULL; | |
781 | } | |
782 | ||
783 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) | |
784 | { | |
785 | struct ipc_proc_iter *iter = s->private; | |
786 | struct ipc_proc_iface *iface = iter->iface; | |
787 | struct kern_ipc_perm *ipc = it; | |
788 | ||
789 | /* If we had an ipc id locked before, unlock it */ | |
790 | if (ipc && ipc != SEQ_START_TOKEN) | |
791 | ipc_unlock(ipc); | |
792 | ||
793 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); | |
794 | } | |
795 | ||
796 | /* | |
797 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. | |
798 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. | |
799 | */ | |
800 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) | |
801 | { | |
802 | struct ipc_proc_iter *iter = s->private; | |
803 | struct ipc_proc_iface *iface = iter->iface; | |
804 | struct ipc_ids *ids; | |
805 | ||
806 | ids = &iter->ns->ids[iface->ids]; | |
807 | ||
808 | /* | |
809 | * Take the lock - this will be released by the corresponding | |
810 | * call to stop(). | |
811 | */ | |
812 | down_read(&ids->rwsem); | |
813 | ||
814 | /* pos < 0 is invalid */ | |
815 | if (*pos < 0) | |
816 | return NULL; | |
817 | ||
818 | /* pos == 0 means header */ | |
819 | if (*pos == 0) | |
820 | return SEQ_START_TOKEN; | |
821 | ||
822 | /* Find the (pos-1)th ipc */ | |
823 | return sysvipc_find_ipc(ids, *pos - 1, pos); | |
824 | } | |
825 | ||
826 | static void sysvipc_proc_stop(struct seq_file *s, void *it) | |
827 | { | |
828 | struct kern_ipc_perm *ipc = it; | |
829 | struct ipc_proc_iter *iter = s->private; | |
830 | struct ipc_proc_iface *iface = iter->iface; | |
831 | struct ipc_ids *ids; | |
832 | ||
833 | /* If we had a locked structure, release it */ | |
834 | if (ipc && ipc != SEQ_START_TOKEN) | |
835 | ipc_unlock(ipc); | |
836 | ||
837 | ids = &iter->ns->ids[iface->ids]; | |
838 | /* Release the lock we took in start() */ | |
839 | up_read(&ids->rwsem); | |
840 | } | |
841 | ||
842 | static int sysvipc_proc_show(struct seq_file *s, void *it) | |
843 | { | |
844 | struct ipc_proc_iter *iter = s->private; | |
845 | struct ipc_proc_iface *iface = iter->iface; | |
846 | ||
847 | if (it == SEQ_START_TOKEN) { | |
848 | seq_puts(s, iface->header); | |
849 | return 0; | |
850 | } | |
851 | ||
852 | return iface->show(s, it); | |
853 | } | |
854 | ||
855 | static const struct seq_operations sysvipc_proc_seqops = { | |
856 | .start = sysvipc_proc_start, | |
857 | .stop = sysvipc_proc_stop, | |
858 | .next = sysvipc_proc_next, | |
859 | .show = sysvipc_proc_show, | |
860 | }; | |
861 | ||
862 | static int sysvipc_proc_open(struct inode *inode, struct file *file) | |
863 | { | |
864 | struct ipc_proc_iter *iter; | |
865 | ||
866 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); | |
867 | if (!iter) | |
868 | return -ENOMEM; | |
869 | ||
870 | iter->iface = PDE_DATA(inode); | |
871 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); | |
872 | ||
873 | return 0; | |
874 | } | |
875 | ||
876 | static int sysvipc_proc_release(struct inode *inode, struct file *file) | |
877 | { | |
878 | struct seq_file *seq = file->private_data; | |
879 | struct ipc_proc_iter *iter = seq->private; | |
880 | put_ipc_ns(iter->ns); | |
881 | return seq_release_private(inode, file); | |
882 | } | |
883 | ||
884 | static const struct file_operations sysvipc_proc_fops = { | |
885 | .open = sysvipc_proc_open, | |
886 | .read = seq_read, | |
887 | .llseek = seq_lseek, | |
888 | .release = sysvipc_proc_release, | |
889 | }; | |
890 | #endif /* CONFIG_PROC_FS */ |