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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 INFO command, that | |
27 | * do not demand atomicity | |
28 | * acquire the ipc lock (kern_ipc_perm.lock) through | |
29 | * ipc_lock_object() | |
30 | * - perform read-only operations that demand atomicity, | |
31 | * such as STAT command. | |
32 | * - perform data updates, such as SET, RMID commands and | |
33 | * mechanism-specific operations (semop/semtimedop, | |
34 | * msgsnd/msgrcv, shmat/shmdt). | |
35 | * drop the ipc lock, through ipc_unlock_object(). | |
36 | * rcu_read_unlock() | |
37 | * | |
38 | * The ids->rwsem must be taken when: | |
39 | * - creating, removing and iterating the existing entries in ipc | |
40 | * identifier sets. | |
41 | * - iterating through files under /proc/sysvipc/ | |
42 | * | |
43 | * Note that sems have a special fast path that avoids kern_ipc_perm.lock - | |
44 | * see sem_lock(). | |
45 | */ | |
46 | ||
47 | #include <linux/mm.h> | |
48 | #include <linux/shm.h> | |
49 | #include <linux/init.h> | |
50 | #include <linux/msg.h> | |
51 | #include <linux/vmalloc.h> | |
52 | #include <linux/slab.h> | |
53 | #include <linux/notifier.h> | |
54 | #include <linux/capability.h> | |
55 | #include <linux/highuid.h> | |
56 | #include <linux/security.h> | |
57 | #include <linux/rcupdate.h> | |
58 | #include <linux/workqueue.h> | |
59 | #include <linux/seq_file.h> | |
60 | #include <linux/proc_fs.h> | |
61 | #include <linux/audit.h> | |
62 | #include <linux/nsproxy.h> | |
63 | #include <linux/rwsem.h> | |
64 | #include <linux/memory.h> | |
65 | #include <linux/ipc_namespace.h> | |
66 | #include <linux/rhashtable.h> | |
67 | ||
68 | #include <asm/unistd.h> | |
69 | ||
70 | #include "util.h" | |
71 | ||
72 | struct ipc_proc_iface { | |
73 | const char *path; | |
74 | const char *header; | |
75 | int ids; | |
76 | int (*show)(struct seq_file *, void *); | |
77 | }; | |
78 | ||
79 | /** | |
80 | * ipc_init - initialise ipc subsystem | |
81 | * | |
82 | * The various sysv ipc resources (semaphores, messages and shared | |
83 | * memory) are initialised. | |
84 | * | |
85 | * A callback routine is registered into the memory hotplug notifier | |
86 | * chain: since msgmni scales to lowmem this callback routine will be | |
87 | * called upon successful memory add / remove to recompute msmgni. | |
88 | */ | |
89 | static int __init ipc_init(void) | |
90 | { | |
91 | proc_mkdir("sysvipc", NULL); | |
92 | sem_init(); | |
93 | msg_init(); | |
94 | shm_init(); | |
95 | ||
96 | return 0; | |
97 | } | |
98 | device_initcall(ipc_init); | |
99 | ||
100 | static const struct rhashtable_params ipc_kht_params = { | |
101 | .head_offset = offsetof(struct kern_ipc_perm, khtnode), | |
102 | .key_offset = offsetof(struct kern_ipc_perm, key), | |
103 | .key_len = sizeof_field(struct kern_ipc_perm, key), | |
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 ipc_mni) then initialise the keys hashtable and ids idr. | |
113 | */ | |
114 | void ipc_init_ids(struct ipc_ids *ids) | |
115 | { | |
116 | ids->in_use = 0; | |
117 | ids->seq = 0; | |
118 | init_rwsem(&ids->rwsem); | |
119 | rhashtable_init(&ids->key_ht, &ipc_kht_params); | |
120 | idr_init(&ids->ipcs_idr); | |
121 | ids->max_idx = -1; | |
122 | ids->last_idx = -1; | |
123 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
124 | ids->next_id = -1; | |
125 | #endif | |
126 | } | |
127 | ||
128 | #ifdef CONFIG_PROC_FS | |
129 | static const struct proc_ops sysvipc_proc_ops; | |
130 | /** | |
131 | * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface. | |
132 | * @path: Path in procfs | |
133 | * @header: Banner to be printed at the beginning of the file. | |
134 | * @ids: ipc id table to iterate. | |
135 | * @show: show routine. | |
136 | */ | |
137 | void __init ipc_init_proc_interface(const char *path, const char *header, | |
138 | int ids, int (*show)(struct seq_file *, void *)) | |
139 | { | |
140 | struct proc_dir_entry *pde; | |
141 | struct ipc_proc_iface *iface; | |
142 | ||
143 | iface = kmalloc(sizeof(*iface), GFP_KERNEL); | |
144 | if (!iface) | |
145 | return; | |
146 | iface->path = path; | |
147 | iface->header = header; | |
148 | iface->ids = ids; | |
149 | iface->show = show; | |
150 | ||
151 | pde = proc_create_data(path, | |
152 | S_IRUGO, /* world readable */ | |
153 | NULL, /* parent dir */ | |
154 | &sysvipc_proc_ops, | |
155 | iface); | |
156 | if (!pde) | |
157 | kfree(iface); | |
158 | } | |
159 | #endif | |
160 | ||
161 | /** | |
162 | * ipc_findkey - find a key in an ipc identifier set | |
163 | * @ids: ipc identifier set | |
164 | * @key: key to find | |
165 | * | |
166 | * Returns the locked pointer to the ipc structure if found or NULL | |
167 | * otherwise. If key is found ipc points to the owning ipc structure | |
168 | * | |
169 | * Called with writer ipc_ids.rwsem held. | |
170 | */ | |
171 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) | |
172 | { | |
173 | struct kern_ipc_perm *ipcp; | |
174 | ||
175 | ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, | |
176 | ipc_kht_params); | |
177 | if (!ipcp) | |
178 | return NULL; | |
179 | ||
180 | rcu_read_lock(); | |
181 | ipc_lock_object(ipcp); | |
182 | return ipcp; | |
183 | } | |
184 | ||
185 | /* | |
186 | * Insert new IPC object into idr tree, and set sequence number and id | |
187 | * in the correct order. | |
188 | * Especially: | |
189 | * - the sequence number must be set before inserting the object into the idr, | |
190 | * because the sequence number is accessed without a lock. | |
191 | * - the id can/must be set after inserting the object into the idr. | |
192 | * All accesses must be done after getting kern_ipc_perm.lock. | |
193 | * | |
194 | * The caller must own kern_ipc_perm.lock.of the new object. | |
195 | * On error, the function returns a (negative) error code. | |
196 | * | |
197 | * To conserve sequence number space, especially with extended ipc_mni, | |
198 | * the sequence number is incremented only when the returned ID is less than | |
199 | * the last one. | |
200 | */ | |
201 | static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new) | |
202 | { | |
203 | int idx, next_id = -1; | |
204 | ||
205 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
206 | next_id = ids->next_id; | |
207 | ids->next_id = -1; | |
208 | #endif | |
209 | ||
210 | /* | |
211 | * As soon as a new object is inserted into the idr, | |
212 | * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it, | |
213 | * and the lockless preparations for ipc operations can start. | |
214 | * This means especially: permission checks, audit calls, allocation | |
215 | * of undo structures, ... | |
216 | * | |
217 | * Thus the object must be fully initialized, and if something fails, | |
218 | * then the full tear-down sequence must be followed. | |
219 | * (i.e.: set new->deleted, reduce refcount, call_rcu()) | |
220 | */ | |
221 | ||
222 | if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */ | |
223 | int max_idx; | |
224 | ||
225 | max_idx = max(ids->in_use*3/2, ipc_min_cycle); | |
226 | max_idx = min(max_idx, ipc_mni); | |
227 | ||
228 | /* allocate the idx, with a NULL struct kern_ipc_perm */ | |
229 | idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx, | |
230 | GFP_NOWAIT); | |
231 | ||
232 | if (idx >= 0) { | |
233 | /* | |
234 | * idx got allocated successfully. | |
235 | * Now calculate the sequence number and set the | |
236 | * pointer for real. | |
237 | */ | |
238 | if (idx <= ids->last_idx) { | |
239 | ids->seq++; | |
240 | if (ids->seq >= ipcid_seq_max()) | |
241 | ids->seq = 0; | |
242 | } | |
243 | ids->last_idx = idx; | |
244 | ||
245 | new->seq = ids->seq; | |
246 | /* no need for smp_wmb(), this is done | |
247 | * inside idr_replace, as part of | |
248 | * rcu_assign_pointer | |
249 | */ | |
250 | idr_replace(&ids->ipcs_idr, new, idx); | |
251 | } | |
252 | } else { | |
253 | new->seq = ipcid_to_seqx(next_id); | |
254 | idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id), | |
255 | 0, GFP_NOWAIT); | |
256 | } | |
257 | if (idx >= 0) | |
258 | new->id = (new->seq << ipcmni_seq_shift()) + idx; | |
259 | return idx; | |
260 | } | |
261 | ||
262 | /** | |
263 | * ipc_addid - add an ipc identifier | |
264 | * @ids: ipc identifier set | |
265 | * @new: new ipc permission set | |
266 | * @limit: limit for the number of used ids | |
267 | * | |
268 | * Add an entry 'new' to the ipc ids idr. The permissions object is | |
269 | * initialised and the first free entry is set up and the index assigned | |
270 | * is returned. The 'new' entry is returned in a locked state on success. | |
271 | * | |
272 | * On failure the entry is not locked and a negative err-code is returned. | |
273 | * The caller must use ipc_rcu_putref() to free the identifier. | |
274 | * | |
275 | * Called with writer ipc_ids.rwsem held. | |
276 | */ | |
277 | int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) | |
278 | { | |
279 | kuid_t euid; | |
280 | kgid_t egid; | |
281 | int idx, err; | |
282 | ||
283 | /* 1) Initialize the refcount so that ipc_rcu_putref works */ | |
284 | refcount_set(&new->refcount, 1); | |
285 | ||
286 | if (limit > ipc_mni) | |
287 | limit = ipc_mni; | |
288 | ||
289 | if (ids->in_use >= limit) | |
290 | return -ENOSPC; | |
291 | ||
292 | idr_preload(GFP_KERNEL); | |
293 | ||
294 | spin_lock_init(&new->lock); | |
295 | rcu_read_lock(); | |
296 | spin_lock(&new->lock); | |
297 | ||
298 | current_euid_egid(&euid, &egid); | |
299 | new->cuid = new->uid = euid; | |
300 | new->gid = new->cgid = egid; | |
301 | ||
302 | new->deleted = false; | |
303 | ||
304 | idx = ipc_idr_alloc(ids, new); | |
305 | idr_preload_end(); | |
306 | ||
307 | if (idx >= 0 && new->key != IPC_PRIVATE) { | |
308 | err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode, | |
309 | ipc_kht_params); | |
310 | if (err < 0) { | |
311 | idr_remove(&ids->ipcs_idr, idx); | |
312 | idx = err; | |
313 | } | |
314 | } | |
315 | if (idx < 0) { | |
316 | new->deleted = true; | |
317 | spin_unlock(&new->lock); | |
318 | rcu_read_unlock(); | |
319 | return idx; | |
320 | } | |
321 | ||
322 | ids->in_use++; | |
323 | if (idx > ids->max_idx) | |
324 | ids->max_idx = idx; | |
325 | return idx; | |
326 | } | |
327 | ||
328 | /** | |
329 | * ipcget_new - create a new ipc object | |
330 | * @ns: ipc namespace | |
331 | * @ids: ipc identifier set | |
332 | * @ops: the actual creation routine to call | |
333 | * @params: its parameters | |
334 | * | |
335 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
336 | * when the key is IPC_PRIVATE. | |
337 | */ | |
338 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, | |
339 | const struct ipc_ops *ops, struct ipc_params *params) | |
340 | { | |
341 | int err; | |
342 | ||
343 | down_write(&ids->rwsem); | |
344 | err = ops->getnew(ns, params); | |
345 | up_write(&ids->rwsem); | |
346 | return err; | |
347 | } | |
348 | ||
349 | /** | |
350 | * ipc_check_perms - check security and permissions for an ipc object | |
351 | * @ns: ipc namespace | |
352 | * @ipcp: ipc permission set | |
353 | * @ops: the actual security 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 and that key already exists in the | |
358 | * ds IDR. | |
359 | * | |
360 | * On success, the ipc id is returned. | |
361 | * | |
362 | * It is called with ipc_ids.rwsem and ipcp->lock held. | |
363 | */ | |
364 | static int ipc_check_perms(struct ipc_namespace *ns, | |
365 | struct kern_ipc_perm *ipcp, | |
366 | const struct ipc_ops *ops, | |
367 | struct ipc_params *params) | |
368 | { | |
369 | int err; | |
370 | ||
371 | if (ipcperms(ns, ipcp, params->flg)) | |
372 | err = -EACCES; | |
373 | else { | |
374 | err = ops->associate(ipcp, params->flg); | |
375 | if (!err) | |
376 | err = ipcp->id; | |
377 | } | |
378 | ||
379 | return err; | |
380 | } | |
381 | ||
382 | /** | |
383 | * ipcget_public - get an ipc object or create a new one | |
384 | * @ns: ipc namespace | |
385 | * @ids: ipc identifier set | |
386 | * @ops: the actual creation routine to call | |
387 | * @params: its parameters | |
388 | * | |
389 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
390 | * when the key is not IPC_PRIVATE. | |
391 | * It adds a new entry if the key is not found and does some permission | |
392 | * / security checkings if the key is found. | |
393 | * | |
394 | * On success, the ipc id is returned. | |
395 | */ | |
396 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, | |
397 | const struct ipc_ops *ops, struct ipc_params *params) | |
398 | { | |
399 | struct kern_ipc_perm *ipcp; | |
400 | int flg = params->flg; | |
401 | int err; | |
402 | ||
403 | /* | |
404 | * Take the lock as a writer since we are potentially going to add | |
405 | * a new entry + read locks are not "upgradable" | |
406 | */ | |
407 | down_write(&ids->rwsem); | |
408 | ipcp = ipc_findkey(ids, params->key); | |
409 | if (ipcp == NULL) { | |
410 | /* key not used */ | |
411 | if (!(flg & IPC_CREAT)) | |
412 | err = -ENOENT; | |
413 | else | |
414 | err = ops->getnew(ns, params); | |
415 | } else { | |
416 | /* ipc object has been locked by ipc_findkey() */ | |
417 | ||
418 | if (flg & IPC_CREAT && flg & IPC_EXCL) | |
419 | err = -EEXIST; | |
420 | else { | |
421 | err = 0; | |
422 | if (ops->more_checks) | |
423 | err = ops->more_checks(ipcp, params); | |
424 | if (!err) | |
425 | /* | |
426 | * ipc_check_perms returns the IPC id on | |
427 | * success | |
428 | */ | |
429 | err = ipc_check_perms(ns, ipcp, ops, params); | |
430 | } | |
431 | ipc_unlock(ipcp); | |
432 | } | |
433 | up_write(&ids->rwsem); | |
434 | ||
435 | return err; | |
436 | } | |
437 | ||
438 | /** | |
439 | * ipc_kht_remove - remove an ipc from the key hashtable | |
440 | * @ids: ipc identifier set | |
441 | * @ipcp: ipc perm structure containing the key to remove | |
442 | * | |
443 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
444 | * before this function is called, and remain locked on the exit. | |
445 | */ | |
446 | static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
447 | { | |
448 | if (ipcp->key != IPC_PRIVATE) | |
449 | rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, | |
450 | ipc_kht_params); | |
451 | } | |
452 | ||
453 | /** | |
454 | * ipc_rmid - remove an ipc identifier | |
455 | * @ids: ipc identifier set | |
456 | * @ipcp: ipc perm structure containing the identifier to remove | |
457 | * | |
458 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
459 | * before this function is called, and remain locked on the exit. | |
460 | */ | |
461 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
462 | { | |
463 | int idx = ipcid_to_idx(ipcp->id); | |
464 | ||
465 | idr_remove(&ids->ipcs_idr, idx); | |
466 | ipc_kht_remove(ids, ipcp); | |
467 | ids->in_use--; | |
468 | ipcp->deleted = true; | |
469 | ||
470 | if (unlikely(idx == ids->max_idx)) { | |
471 | do { | |
472 | idx--; | |
473 | if (idx == -1) | |
474 | break; | |
475 | } while (!idr_find(&ids->ipcs_idr, idx)); | |
476 | ids->max_idx = idx; | |
477 | } | |
478 | } | |
479 | ||
480 | /** | |
481 | * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE | |
482 | * @ids: ipc identifier set | |
483 | * @ipcp: ipc perm structure containing the key to modify | |
484 | * | |
485 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
486 | * before this function is called, and remain locked on the exit. | |
487 | */ | |
488 | void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
489 | { | |
490 | ipc_kht_remove(ids, ipcp); | |
491 | ipcp->key = IPC_PRIVATE; | |
492 | } | |
493 | ||
494 | bool ipc_rcu_getref(struct kern_ipc_perm *ptr) | |
495 | { | |
496 | return refcount_inc_not_zero(&ptr->refcount); | |
497 | } | |
498 | ||
499 | void ipc_rcu_putref(struct kern_ipc_perm *ptr, | |
500 | void (*func)(struct rcu_head *head)) | |
501 | { | |
502 | if (!refcount_dec_and_test(&ptr->refcount)) | |
503 | return; | |
504 | ||
505 | call_rcu(&ptr->rcu, func); | |
506 | } | |
507 | ||
508 | /** | |
509 | * ipcperms - check ipc permissions | |
510 | * @ns: ipc namespace | |
511 | * @ipcp: ipc permission set | |
512 | * @flag: desired permission set | |
513 | * | |
514 | * Check user, group, other permissions for access | |
515 | * to ipc resources. return 0 if allowed | |
516 | * | |
517 | * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h> | |
518 | */ | |
519 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) | |
520 | { | |
521 | kuid_t euid = current_euid(); | |
522 | int requested_mode, granted_mode; | |
523 | ||
524 | audit_ipc_obj(ipcp); | |
525 | requested_mode = (flag >> 6) | (flag >> 3) | flag; | |
526 | granted_mode = ipcp->mode; | |
527 | if (uid_eq(euid, ipcp->cuid) || | |
528 | uid_eq(euid, ipcp->uid)) | |
529 | granted_mode >>= 6; | |
530 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) | |
531 | granted_mode >>= 3; | |
532 | /* is there some bit set in requested_mode but not in granted_mode? */ | |
533 | if ((requested_mode & ~granted_mode & 0007) && | |
534 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) | |
535 | return -1; | |
536 | ||
537 | return security_ipc_permission(ipcp, flag); | |
538 | } | |
539 | ||
540 | /* | |
541 | * Functions to convert between the kern_ipc_perm structure and the | |
542 | * old/new ipc_perm structures | |
543 | */ | |
544 | ||
545 | /** | |
546 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user | |
547 | * @in: kernel permissions | |
548 | * @out: new style ipc permissions | |
549 | * | |
550 | * Turn the kernel object @in into a set of permissions descriptions | |
551 | * for returning to userspace (@out). | |
552 | */ | |
553 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) | |
554 | { | |
555 | out->key = in->key; | |
556 | out->uid = from_kuid_munged(current_user_ns(), in->uid); | |
557 | out->gid = from_kgid_munged(current_user_ns(), in->gid); | |
558 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); | |
559 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); | |
560 | out->mode = in->mode; | |
561 | out->seq = in->seq; | |
562 | } | |
563 | ||
564 | /** | |
565 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old | |
566 | * @in: new style ipc permissions | |
567 | * @out: old style ipc permissions | |
568 | * | |
569 | * Turn the new style permissions object @in into a compatibility | |
570 | * object and store it into the @out pointer. | |
571 | */ | |
572 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) | |
573 | { | |
574 | out->key = in->key; | |
575 | SET_UID(out->uid, in->uid); | |
576 | SET_GID(out->gid, in->gid); | |
577 | SET_UID(out->cuid, in->cuid); | |
578 | SET_GID(out->cgid, in->cgid); | |
579 | out->mode = in->mode; | |
580 | out->seq = in->seq; | |
581 | } | |
582 | ||
583 | /** | |
584 | * ipc_obtain_object_idr | |
585 | * @ids: ipc identifier set | |
586 | * @id: ipc id to look for | |
587 | * | |
588 | * Look for an id in the ipc ids idr and return associated ipc object. | |
589 | * | |
590 | * Call inside the RCU critical section. | |
591 | * The ipc object is *not* locked on exit. | |
592 | */ | |
593 | struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) | |
594 | { | |
595 | struct kern_ipc_perm *out; | |
596 | int idx = ipcid_to_idx(id); | |
597 | ||
598 | out = idr_find(&ids->ipcs_idr, idx); | |
599 | if (!out) | |
600 | return ERR_PTR(-EINVAL); | |
601 | ||
602 | return out; | |
603 | } | |
604 | ||
605 | /** | |
606 | * ipc_obtain_object_check | |
607 | * @ids: ipc identifier set | |
608 | * @id: ipc id to look for | |
609 | * | |
610 | * Similar to ipc_obtain_object_idr() but also checks the ipc object | |
611 | * sequence number. | |
612 | * | |
613 | * Call inside the RCU critical section. | |
614 | * The ipc object is *not* locked on exit. | |
615 | */ | |
616 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) | |
617 | { | |
618 | struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id); | |
619 | ||
620 | if (IS_ERR(out)) | |
621 | goto out; | |
622 | ||
623 | if (ipc_checkid(out, id)) | |
624 | return ERR_PTR(-EINVAL); | |
625 | out: | |
626 | return out; | |
627 | } | |
628 | ||
629 | /** | |
630 | * ipcget - Common sys_*get() code | |
631 | * @ns: namespace | |
632 | * @ids: ipc identifier set | |
633 | * @ops: operations to be called on ipc object creation, permission checks | |
634 | * and further checks | |
635 | * @params: the parameters needed by the previous operations. | |
636 | * | |
637 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). | |
638 | */ | |
639 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, | |
640 | const struct ipc_ops *ops, struct ipc_params *params) | |
641 | { | |
642 | if (params->key == IPC_PRIVATE) | |
643 | return ipcget_new(ns, ids, ops, params); | |
644 | else | |
645 | return ipcget_public(ns, ids, ops, params); | |
646 | } | |
647 | ||
648 | /** | |
649 | * ipc_update_perm - update the permissions of an ipc object | |
650 | * @in: the permission given as input. | |
651 | * @out: the permission of the ipc to set. | |
652 | */ | |
653 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) | |
654 | { | |
655 | kuid_t uid = make_kuid(current_user_ns(), in->uid); | |
656 | kgid_t gid = make_kgid(current_user_ns(), in->gid); | |
657 | if (!uid_valid(uid) || !gid_valid(gid)) | |
658 | return -EINVAL; | |
659 | ||
660 | out->uid = uid; | |
661 | out->gid = gid; | |
662 | out->mode = (out->mode & ~S_IRWXUGO) | |
663 | | (in->mode & S_IRWXUGO); | |
664 | ||
665 | return 0; | |
666 | } | |
667 | ||
668 | /** | |
669 | * ipcctl_obtain_check - retrieve an ipc object and check permissions | |
670 | * @ns: ipc namespace | |
671 | * @ids: the table of ids where to look for the ipc | |
672 | * @id: the id of the ipc to retrieve | |
673 | * @cmd: the cmd to check | |
674 | * @perm: the permission to set | |
675 | * @extra_perm: one extra permission parameter used by msq | |
676 | * | |
677 | * This function does some common audit and permissions check for some IPC_XXX | |
678 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. | |
679 | * | |
680 | * It: | |
681 | * - retrieves the ipc object 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 | |
684 | * error. | |
685 | * | |
686 | * Call holding the both the rwsem and the rcu read lock. | |
687 | */ | |
688 | struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns, | |
689 | struct ipc_ids *ids, int id, int cmd, | |
690 | struct ipc64_perm *perm, int extra_perm) | |
691 | { | |
692 | kuid_t euid; | |
693 | int err = -EPERM; | |
694 | struct kern_ipc_perm *ipcp; | |
695 | ||
696 | ipcp = ipc_obtain_object_check(ids, id); | |
697 | if (IS_ERR(ipcp)) { | |
698 | err = PTR_ERR(ipcp); | |
699 | goto err; | |
700 | } | |
701 | ||
702 | audit_ipc_obj(ipcp); | |
703 | if (cmd == IPC_SET) | |
704 | audit_ipc_set_perm(extra_perm, perm->uid, | |
705 | perm->gid, perm->mode); | |
706 | ||
707 | euid = current_euid(); | |
708 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || | |
709 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) | |
710 | return ipcp; /* successful lookup */ | |
711 | err: | |
712 | return ERR_PTR(err); | |
713 | } | |
714 | ||
715 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION | |
716 | ||
717 | ||
718 | /** | |
719 | * ipc_parse_version - ipc call version | |
720 | * @cmd: pointer to command | |
721 | * | |
722 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. | |
723 | * The @cmd value is turned from an encoding command and version into | |
724 | * just the command code. | |
725 | */ | |
726 | int ipc_parse_version(int *cmd) | |
727 | { | |
728 | if (*cmd & IPC_64) { | |
729 | *cmd ^= IPC_64; | |
730 | return IPC_64; | |
731 | } else { | |
732 | return IPC_OLD; | |
733 | } | |
734 | } | |
735 | ||
736 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ | |
737 | ||
738 | #ifdef CONFIG_PROC_FS | |
739 | struct ipc_proc_iter { | |
740 | struct ipc_namespace *ns; | |
741 | struct pid_namespace *pid_ns; | |
742 | struct ipc_proc_iface *iface; | |
743 | }; | |
744 | ||
745 | struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) | |
746 | { | |
747 | struct ipc_proc_iter *iter = s->private; | |
748 | return iter->pid_ns; | |
749 | } | |
750 | ||
751 | /* | |
752 | * This routine locks the ipc structure found at least at position pos. | |
753 | */ | |
754 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, | |
755 | loff_t *new_pos) | |
756 | { | |
757 | struct kern_ipc_perm *ipc; | |
758 | int total, id; | |
759 | ||
760 | total = 0; | |
761 | for (id = 0; id < pos && total < ids->in_use; id++) { | |
762 | ipc = idr_find(&ids->ipcs_idr, id); | |
763 | if (ipc != NULL) | |
764 | total++; | |
765 | } | |
766 | ||
767 | if (total >= ids->in_use) | |
768 | return NULL; | |
769 | ||
770 | for (; pos < ipc_mni; pos++) { | |
771 | ipc = idr_find(&ids->ipcs_idr, pos); | |
772 | if (ipc != NULL) { | |
773 | *new_pos = pos + 1; | |
774 | rcu_read_lock(); | |
775 | ipc_lock_object(ipc); | |
776 | return ipc; | |
777 | } | |
778 | } | |
779 | ||
780 | /* Out of range - return NULL to terminate iteration */ | |
781 | return NULL; | |
782 | } | |
783 | ||
784 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) | |
785 | { | |
786 | struct ipc_proc_iter *iter = s->private; | |
787 | struct ipc_proc_iface *iface = iter->iface; | |
788 | struct kern_ipc_perm *ipc = it; | |
789 | ||
790 | /* If we had an ipc id locked before, unlock it */ | |
791 | if (ipc && ipc != SEQ_START_TOKEN) | |
792 | ipc_unlock(ipc); | |
793 | ||
794 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); | |
795 | } | |
796 | ||
797 | /* | |
798 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. | |
799 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. | |
800 | */ | |
801 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) | |
802 | { | |
803 | struct ipc_proc_iter *iter = s->private; | |
804 | struct ipc_proc_iface *iface = iter->iface; | |
805 | struct ipc_ids *ids; | |
806 | ||
807 | ids = &iter->ns->ids[iface->ids]; | |
808 | ||
809 | /* | |
810 | * Take the lock - this will be released by the corresponding | |
811 | * call to stop(). | |
812 | */ | |
813 | down_read(&ids->rwsem); | |
814 | ||
815 | /* pos < 0 is invalid */ | |
816 | if (*pos < 0) | |
817 | return NULL; | |
818 | ||
819 | /* pos == 0 means header */ | |
820 | if (*pos == 0) | |
821 | return SEQ_START_TOKEN; | |
822 | ||
823 | /* Find the (pos-1)th ipc */ | |
824 | return sysvipc_find_ipc(ids, *pos - 1, pos); | |
825 | } | |
826 | ||
827 | static void sysvipc_proc_stop(struct seq_file *s, void *it) | |
828 | { | |
829 | struct kern_ipc_perm *ipc = it; | |
830 | struct ipc_proc_iter *iter = s->private; | |
831 | struct ipc_proc_iface *iface = iter->iface; | |
832 | struct ipc_ids *ids; | |
833 | ||
834 | /* If we had a locked structure, release it */ | |
835 | if (ipc && ipc != SEQ_START_TOKEN) | |
836 | ipc_unlock(ipc); | |
837 | ||
838 | ids = &iter->ns->ids[iface->ids]; | |
839 | /* Release the lock we took in start() */ | |
840 | up_read(&ids->rwsem); | |
841 | } | |
842 | ||
843 | static int sysvipc_proc_show(struct seq_file *s, void *it) | |
844 | { | |
845 | struct ipc_proc_iter *iter = s->private; | |
846 | struct ipc_proc_iface *iface = iter->iface; | |
847 | ||
848 | if (it == SEQ_START_TOKEN) { | |
849 | seq_puts(s, iface->header); | |
850 | return 0; | |
851 | } | |
852 | ||
853 | return iface->show(s, it); | |
854 | } | |
855 | ||
856 | static const struct seq_operations sysvipc_proc_seqops = { | |
857 | .start = sysvipc_proc_start, | |
858 | .stop = sysvipc_proc_stop, | |
859 | .next = sysvipc_proc_next, | |
860 | .show = sysvipc_proc_show, | |
861 | }; | |
862 | ||
863 | static int sysvipc_proc_open(struct inode *inode, struct file *file) | |
864 | { | |
865 | struct ipc_proc_iter *iter; | |
866 | ||
867 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); | |
868 | if (!iter) | |
869 | return -ENOMEM; | |
870 | ||
871 | iter->iface = PDE_DATA(inode); | |
872 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); | |
873 | iter->pid_ns = get_pid_ns(task_active_pid_ns(current)); | |
874 | ||
875 | return 0; | |
876 | } | |
877 | ||
878 | static int sysvipc_proc_release(struct inode *inode, struct file *file) | |
879 | { | |
880 | struct seq_file *seq = file->private_data; | |
881 | struct ipc_proc_iter *iter = seq->private; | |
882 | put_ipc_ns(iter->ns); | |
883 | put_pid_ns(iter->pid_ns); | |
884 | return seq_release_private(inode, file); | |
885 | } | |
886 | ||
887 | static const struct proc_ops sysvipc_proc_ops = { | |
888 | .proc_open = sysvipc_proc_open, | |
889 | .proc_read = seq_read, | |
890 | .proc_lseek = seq_lseek, | |
891 | .proc_release = sysvipc_proc_release, | |
892 | }; | |
893 | #endif /* CONFIG_PROC_FS */ |