Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
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 | |
624dffcb | 11 | * Manfred Spraul <manfred@colorfullife.com> |
1da177e4 LT |
12 | * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary(). |
13 | * Mingming Cao <cmm@us.ibm.com> | |
073115d6 SG |
14 | * Mar 2006 - support for audit of ipc object properties |
15 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> | |
73ea4130 KK |
16 | * Jun 2006 - namespaces ssupport |
17 | * OpenVZ, SWsoft Inc. | |
18 | * Pavel Emelianov <xemul@openvz.org> | |
05603c44 DB |
19 | * |
20 | * General sysv ipc locking scheme: | |
18ccee26 DB |
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). | |
87ad4b0d PM |
26 | * - perform read-only operations, such as INFO command, that |
27 | * do not demand atomicity | |
18ccee26 DB |
28 | * acquire the ipc lock (kern_ipc_perm.lock) through |
29 | * ipc_lock_object() | |
87ad4b0d PM |
30 | * - perform read-only operations that demand atomicity, |
31 | * such as STAT command. | |
18ccee26 DB |
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(). | |
1da177e4 LT |
45 | */ |
46 | ||
1da177e4 LT |
47 | #include <linux/mm.h> |
48 | #include <linux/shm.h> | |
49 | #include <linux/init.h> | |
50 | #include <linux/msg.h> | |
1da177e4 LT |
51 | #include <linux/vmalloc.h> |
52 | #include <linux/slab.h> | |
8f68fa2d | 53 | #include <linux/notifier.h> |
c59ede7b | 54 | #include <linux/capability.h> |
1da177e4 LT |
55 | #include <linux/highuid.h> |
56 | #include <linux/security.h> | |
57 | #include <linux/rcupdate.h> | |
58 | #include <linux/workqueue.h> | |
ae781774 MW |
59 | #include <linux/seq_file.h> |
60 | #include <linux/proc_fs.h> | |
073115d6 | 61 | #include <linux/audit.h> |
73ea4130 | 62 | #include <linux/nsproxy.h> |
3e148c79 | 63 | #include <linux/rwsem.h> |
b6b337ad | 64 | #include <linux/memory.h> |
ae5e1b22 | 65 | #include <linux/ipc_namespace.h> |
0eb71a9d | 66 | #include <linux/rhashtable.h> |
1da177e4 LT |
67 | |
68 | #include <asm/unistd.h> | |
69 | ||
70 | #include "util.h" | |
71 | ||
ae781774 MW |
72 | struct ipc_proc_iface { |
73 | const char *path; | |
74 | const char *header; | |
73ea4130 | 75 | int ids; |
ae781774 MW |
76 | int (*show)(struct seq_file *, void *); |
77 | }; | |
78 | ||
1da177e4 | 79 | /** |
8001c858 | 80 | * ipc_init - initialise ipc subsystem |
1da177e4 | 81 | * |
8001c858 DB |
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. | |
1da177e4 | 88 | */ |
1da177e4 LT |
89 | static int __init ipc_init(void) |
90 | { | |
0cfb6aee GK |
91 | int err_sem, err_msg; |
92 | ||
e74a0eff | 93 | proc_mkdir("sysvipc", NULL); |
0cfb6aee GK |
94 | err_sem = sem_init(); |
95 | WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem); | |
96 | err_msg = msg_init(); | |
97 | WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg); | |
1da177e4 | 98 | shm_init(); |
0cfb6aee GK |
99 | |
100 | return err_msg ? err_msg : err_sem; | |
1da177e4 | 101 | } |
6d08a256 | 102 | device_initcall(ipc_init); |
1da177e4 | 103 | |
0cfb6aee GK |
104 | static const struct rhashtable_params ipc_kht_params = { |
105 | .head_offset = offsetof(struct kern_ipc_perm, khtnode), | |
106 | .key_offset = offsetof(struct kern_ipc_perm, key), | |
107 | .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key), | |
108 | .locks_mul = 1, | |
109 | .automatic_shrinking = true, | |
110 | }; | |
111 | ||
1da177e4 | 112 | /** |
8001c858 DB |
113 | * ipc_init_ids - initialise ipc identifiers |
114 | * @ids: ipc identifier set | |
1da177e4 | 115 | * |
8001c858 | 116 | * Set up the sequence range to use for the ipc identifier range (limited |
0cfb6aee | 117 | * below IPCMNI) then initialise the keys hashtable and ids idr. |
1da177e4 | 118 | */ |
0cfb6aee | 119 | int ipc_init_ids(struct ipc_ids *ids) |
1da177e4 | 120 | { |
0cfb6aee | 121 | int err; |
1da177e4 | 122 | ids->in_use = 0; |
1da177e4 | 123 | ids->seq = 0; |
daf948c7 | 124 | init_rwsem(&ids->rwsem); |
0cfb6aee GK |
125 | err = rhashtable_init(&ids->key_ht, &ipc_kht_params); |
126 | if (err) | |
127 | return err; | |
7ca7e564 | 128 | idr_init(&ids->ipcs_idr); |
0cfb6aee | 129 | ids->tables_initialized = true; |
15df03c8 | 130 | ids->max_id = -1; |
b8fd9983 DB |
131 | #ifdef CONFIG_CHECKPOINT_RESTORE |
132 | ids->next_id = -1; | |
133 | #endif | |
0cfb6aee | 134 | return 0; |
1da177e4 LT |
135 | } |
136 | ||
ae781774 | 137 | #ifdef CONFIG_PROC_FS |
9a32144e | 138 | static const struct file_operations sysvipc_proc_fops; |
ae781774 | 139 | /** |
8001c858 DB |
140 | * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface. |
141 | * @path: Path in procfs | |
142 | * @header: Banner to be printed at the beginning of the file. | |
143 | * @ids: ipc id table to iterate. | |
144 | * @show: show routine. | |
ae781774 MW |
145 | */ |
146 | void __init ipc_init_proc_interface(const char *path, const char *header, | |
73ea4130 | 147 | int ids, int (*show)(struct seq_file *, void *)) |
ae781774 MW |
148 | { |
149 | struct proc_dir_entry *pde; | |
150 | struct ipc_proc_iface *iface; | |
151 | ||
152 | iface = kmalloc(sizeof(*iface), GFP_KERNEL); | |
153 | if (!iface) | |
154 | return; | |
155 | iface->path = path; | |
156 | iface->header = header; | |
157 | iface->ids = ids; | |
158 | iface->show = show; | |
159 | ||
6a6375db DL |
160 | pde = proc_create_data(path, |
161 | S_IRUGO, /* world readable */ | |
162 | NULL, /* parent dir */ | |
163 | &sysvipc_proc_fops, | |
164 | iface); | |
3ab08fe2 | 165 | if (!pde) |
ae781774 | 166 | kfree(iface); |
ae781774 MW |
167 | } |
168 | #endif | |
169 | ||
1da177e4 | 170 | /** |
8001c858 DB |
171 | * ipc_findkey - find a key in an ipc identifier set |
172 | * @ids: ipc identifier set | |
173 | * @key: key to find | |
46c0a8ca | 174 | * |
8001c858 DB |
175 | * Returns the locked pointer to the ipc structure if found or NULL |
176 | * otherwise. If key is found ipc points to the owning ipc structure | |
177 | * | |
0cfb6aee | 178 | * Called with writer ipc_ids.rwsem held. |
1da177e4 | 179 | */ |
7748dbfa | 180 | static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key) |
1da177e4 | 181 | { |
0cfb6aee | 182 | struct kern_ipc_perm *ipcp = NULL; |
7ca7e564 | 183 | |
0cfb6aee GK |
184 | if (likely(ids->tables_initialized)) |
185 | ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, | |
186 | ipc_kht_params); | |
7ca7e564 | 187 | |
0cfb6aee | 188 | if (ipcp) { |
32a27500 | 189 | rcu_read_lock(); |
0cfb6aee GK |
190 | ipc_lock_object(ipcp); |
191 | return ipcp; | |
1da177e4 | 192 | } |
7ca7e564 ND |
193 | |
194 | return NULL; | |
1da177e4 LT |
195 | } |
196 | ||
b8fd9983 | 197 | /* |
e2652ae6 MS |
198 | * Insert new IPC object into idr tree, and set sequence number and id |
199 | * in the correct order. | |
200 | * Especially: | |
201 | * - the sequence number must be set before inserting the object into the idr, | |
202 | * because the sequence number is accessed without a lock. | |
203 | * - the id can/must be set after inserting the object into the idr. | |
204 | * All accesses must be done after getting kern_ipc_perm.lock. | |
205 | * | |
206 | * The caller must own kern_ipc_perm.lock.of the new object. | |
207 | * On error, the function returns a (negative) error code. | |
b8fd9983 | 208 | */ |
e2652ae6 | 209 | static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new) |
b8fd9983 | 210 | { |
e2652ae6 MS |
211 | int idx, next_id = -1; |
212 | ||
213 | #ifdef CONFIG_CHECKPOINT_RESTORE | |
214 | next_id = ids->next_id; | |
215 | ids->next_id = -1; | |
216 | #endif | |
217 | ||
218 | /* | |
219 | * As soon as a new object is inserted into the idr, | |
220 | * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it, | |
221 | * and the lockless preparations for ipc operations can start. | |
222 | * This means especially: permission checks, audit calls, allocation | |
223 | * of undo structures, ... | |
224 | * | |
225 | * Thus the object must be fully initialized, and if something fails, | |
226 | * then the full tear-down sequence must be followed. | |
227 | * (i.e.: set new->deleted, reduce refcount, call_rcu()) | |
228 | */ | |
229 | ||
230 | if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */ | |
b8fd9983 DB |
231 | new->seq = ids->seq++; |
232 | if (ids->seq > IPCID_SEQ_MAX) | |
233 | ids->seq = 0; | |
e2652ae6 | 234 | idx = idr_alloc(&ids->ipcs_idr, new, 0, 0, GFP_NOWAIT); |
b8fd9983 | 235 | } else { |
e2652ae6 MS |
236 | new->seq = ipcid_to_seqx(next_id); |
237 | idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id), | |
238 | 0, GFP_NOWAIT); | |
b8fd9983 | 239 | } |
e2652ae6 MS |
240 | if (idx >= 0) |
241 | new->id = SEQ_MULTIPLIER * new->seq + idx; | |
242 | return idx; | |
b8fd9983 DB |
243 | } |
244 | ||
1da177e4 | 245 | /** |
8001c858 DB |
246 | * ipc_addid - add an ipc identifier |
247 | * @ids: ipc identifier set | |
248 | * @new: new ipc permission set | |
ebf66799 | 249 | * @limit: limit for the number of used ids |
1da177e4 | 250 | * |
8001c858 DB |
251 | * Add an entry 'new' to the ipc ids idr. The permissions object is |
252 | * initialised and the first free entry is set up and the id assigned | |
253 | * is returned. The 'new' entry is returned in a locked state on success. | |
254 | * On failure the entry is not locked and a negative err-code is returned. | |
1da177e4 | 255 | * |
8001c858 | 256 | * Called with writer ipc_ids.rwsem held. |
1da177e4 | 257 | */ |
ebf66799 | 258 | int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) |
1da177e4 | 259 | { |
1efdb69b EB |
260 | kuid_t euid; |
261 | kgid_t egid; | |
e2652ae6 | 262 | int idx, err; |
1da177e4 | 263 | |
ebf66799 DB |
264 | if (limit > IPCMNI) |
265 | limit = IPCMNI; | |
7ca7e564 | 266 | |
ebf66799 | 267 | if (!ids->tables_initialized || ids->in_use >= limit) |
283bb7fa | 268 | return -ENOSPC; |
7ca7e564 | 269 | |
54924ea3 TH |
270 | idr_preload(GFP_KERNEL); |
271 | ||
9405c03e | 272 | refcount_set(&new->refcount, 1); |
e00b4ff7 | 273 | spin_lock_init(&new->lock); |
72a8ff2f | 274 | new->deleted = false; |
e00b4ff7 ND |
275 | rcu_read_lock(); |
276 | spin_lock(&new->lock); | |
277 | ||
b9a53227 LT |
278 | current_euid_egid(&euid, &egid); |
279 | new->cuid = new->uid = euid; | |
280 | new->gid = new->cgid = egid; | |
281 | ||
e2652ae6 | 282 | idx = ipc_idr_alloc(ids, new); |
54924ea3 | 283 | idr_preload_end(); |
0cfb6aee | 284 | |
e2652ae6 | 285 | if (idx >= 0 && new->key != IPC_PRIVATE) { |
0cfb6aee GK |
286 | err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode, |
287 | ipc_kht_params); | |
288 | if (err < 0) { | |
e2652ae6 MS |
289 | idr_remove(&ids->ipcs_idr, idx); |
290 | idx = err; | |
0cfb6aee GK |
291 | } |
292 | } | |
e2652ae6 | 293 | if (idx < 0) { |
e00b4ff7 ND |
294 | spin_unlock(&new->lock); |
295 | rcu_read_unlock(); | |
e2652ae6 | 296 | return idx; |
e00b4ff7 | 297 | } |
7ca7e564 | 298 | |
1da177e4 | 299 | ids->in_use++; |
e2652ae6 MS |
300 | if (idx > ids->max_id) |
301 | ids->max_id = idx; | |
302 | return idx; | |
1da177e4 LT |
303 | } |
304 | ||
7748dbfa | 305 | /** |
8001c858 DB |
306 | * ipcget_new - create a new ipc object |
307 | * @ns: ipc namespace | |
da3dae54 | 308 | * @ids: ipc identifier set |
8001c858 DB |
309 | * @ops: the actual creation routine to call |
310 | * @params: its parameters | |
311 | * | |
312 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
313 | * when the key is IPC_PRIVATE. | |
7748dbfa | 314 | */ |
b2d75cdd | 315 | static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, |
eb66ec44 | 316 | const struct ipc_ops *ops, struct ipc_params *params) |
7748dbfa ND |
317 | { |
318 | int err; | |
7748dbfa | 319 | |
d9a605e4 | 320 | down_write(&ids->rwsem); |
7748dbfa | 321 | err = ops->getnew(ns, params); |
d9a605e4 | 322 | up_write(&ids->rwsem); |
7748dbfa ND |
323 | return err; |
324 | } | |
325 | ||
326 | /** | |
8001c858 DB |
327 | * ipc_check_perms - check security and permissions for an ipc object |
328 | * @ns: ipc namespace | |
329 | * @ipcp: ipc permission set | |
330 | * @ops: the actual security routine to call | |
331 | * @params: its parameters | |
f4566f04 | 332 | * |
8001c858 DB |
333 | * This routine is called by sys_msgget(), sys_semget() and sys_shmget() |
334 | * when the key is not IPC_PRIVATE and that key already exists in the | |
335 | * ds IDR. | |
f4566f04 | 336 | * |
8001c858 | 337 | * On success, the ipc id is returned. |
f4566f04 | 338 | * |
8001c858 | 339 | * It is called with ipc_ids.rwsem and ipcp->lock held. |
7748dbfa | 340 | */ |
b0e77598 SH |
341 | static int ipc_check_perms(struct ipc_namespace *ns, |
342 | struct kern_ipc_perm *ipcp, | |
eb66ec44 | 343 | const struct ipc_ops *ops, |
b0e77598 | 344 | struct ipc_params *params) |
7748dbfa ND |
345 | { |
346 | int err; | |
347 | ||
b0e77598 | 348 | if (ipcperms(ns, ipcp, params->flg)) |
7748dbfa ND |
349 | err = -EACCES; |
350 | else { | |
351 | err = ops->associate(ipcp, params->flg); | |
352 | if (!err) | |
353 | err = ipcp->id; | |
354 | } | |
355 | ||
356 | return err; | |
357 | } | |
358 | ||
359 | /** | |
8001c858 DB |
360 | * ipcget_public - get an ipc object or create a new one |
361 | * @ns: ipc namespace | |
da3dae54 | 362 | * @ids: ipc identifier set |
8001c858 DB |
363 | * @ops: the actual creation routine to call |
364 | * @params: its parameters | |
365 | * | |
366 | * This routine is called by sys_msgget, sys_semget() and sys_shmget() | |
367 | * when the key is not IPC_PRIVATE. | |
368 | * It adds a new entry if the key is not found and does some permission | |
369 | * / security checkings if the key is found. | |
370 | * | |
371 | * On success, the ipc id is returned. | |
7748dbfa | 372 | */ |
b2d75cdd | 373 | static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, |
eb66ec44 | 374 | const struct ipc_ops *ops, struct ipc_params *params) |
7748dbfa ND |
375 | { |
376 | struct kern_ipc_perm *ipcp; | |
377 | int flg = params->flg; | |
378 | int err; | |
7748dbfa | 379 | |
3e148c79 ND |
380 | /* |
381 | * Take the lock as a writer since we are potentially going to add | |
382 | * a new entry + read locks are not "upgradable" | |
383 | */ | |
d9a605e4 | 384 | down_write(&ids->rwsem); |
7748dbfa ND |
385 | ipcp = ipc_findkey(ids, params->key); |
386 | if (ipcp == NULL) { | |
387 | /* key not used */ | |
388 | if (!(flg & IPC_CREAT)) | |
389 | err = -ENOENT; | |
7748dbfa ND |
390 | else |
391 | err = ops->getnew(ns, params); | |
392 | } else { | |
393 | /* ipc object has been locked by ipc_findkey() */ | |
394 | ||
395 | if (flg & IPC_CREAT && flg & IPC_EXCL) | |
396 | err = -EEXIST; | |
397 | else { | |
398 | err = 0; | |
399 | if (ops->more_checks) | |
400 | err = ops->more_checks(ipcp, params); | |
401 | if (!err) | |
f4566f04 ND |
402 | /* |
403 | * ipc_check_perms returns the IPC id on | |
404 | * success | |
405 | */ | |
b0e77598 | 406 | err = ipc_check_perms(ns, ipcp, ops, params); |
7748dbfa ND |
407 | } |
408 | ipc_unlock(ipcp); | |
409 | } | |
d9a605e4 | 410 | up_write(&ids->rwsem); |
7748dbfa ND |
411 | |
412 | return err; | |
413 | } | |
414 | ||
0cfb6aee GK |
415 | /** |
416 | * ipc_kht_remove - remove an ipc from the key hashtable | |
417 | * @ids: ipc identifier set | |
418 | * @ipcp: ipc perm structure containing the key to remove | |
419 | * | |
420 | * ipc_ids.rwsem (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 | static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
424 | { | |
425 | if (ipcp->key != IPC_PRIVATE) | |
426 | rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, | |
427 | ipc_kht_params); | |
428 | } | |
7748dbfa | 429 | |
1da177e4 | 430 | /** |
8001c858 DB |
431 | * ipc_rmid - remove an ipc identifier |
432 | * @ids: ipc identifier set | |
433 | * @ipcp: ipc perm structure containing the identifier to remove | |
1da177e4 | 434 | * |
8001c858 DB |
435 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held |
436 | * before this function is called, and remain locked on the exit. | |
1da177e4 | 437 | */ |
7ca7e564 | 438 | void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) |
1da177e4 | 439 | { |
ce621f5b | 440 | int lid = ipcid_to_idx(ipcp->id); |
7ca7e564 ND |
441 | |
442 | idr_remove(&ids->ipcs_idr, lid); | |
0cfb6aee | 443 | ipc_kht_remove(ids, ipcp); |
1da177e4 | 444 | ids->in_use--; |
72a8ff2f | 445 | ipcp->deleted = true; |
15df03c8 DB |
446 | |
447 | if (unlikely(lid == ids->max_id)) { | |
448 | do { | |
449 | lid--; | |
450 | if (lid == -1) | |
451 | break; | |
452 | } while (!idr_find(&ids->ipcs_idr, lid)); | |
453 | ids->max_id = lid; | |
454 | } | |
1da177e4 LT |
455 | } |
456 | ||
0cfb6aee GK |
457 | /** |
458 | * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE | |
459 | * @ids: ipc identifier set | |
460 | * @ipcp: ipc perm structure containing the key to modify | |
461 | * | |
462 | * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held | |
463 | * before this function is called, and remain locked on the exit. | |
464 | */ | |
465 | void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) | |
466 | { | |
467 | ipc_kht_remove(ids, ipcp); | |
468 | ipcp->key = IPC_PRIVATE; | |
469 | } | |
470 | ||
dba4cdd3 | 471 | int ipc_rcu_getref(struct kern_ipc_perm *ptr) |
1da177e4 | 472 | { |
9405c03e | 473 | return refcount_inc_not_zero(&ptr->refcount); |
65f27f38 DH |
474 | } |
475 | ||
dba4cdd3 MS |
476 | void ipc_rcu_putref(struct kern_ipc_perm *ptr, |
477 | void (*func)(struct rcu_head *head)) | |
1da177e4 | 478 | { |
9405c03e | 479 | if (!refcount_dec_and_test(&ptr->refcount)) |
1da177e4 LT |
480 | return; |
481 | ||
dba4cdd3 | 482 | call_rcu(&ptr->rcu, func); |
53dad6d3 DB |
483 | } |
484 | ||
1da177e4 | 485 | /** |
8001c858 DB |
486 | * ipcperms - check ipc permissions |
487 | * @ns: ipc namespace | |
488 | * @ipcp: ipc permission set | |
489 | * @flag: desired permission set | |
1da177e4 | 490 | * |
8001c858 DB |
491 | * Check user, group, other permissions for access |
492 | * to ipc resources. return 0 if allowed | |
b0e77598 | 493 | * |
0e056eb5 | 494 | * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h> |
1da177e4 | 495 | */ |
b0e77598 SH |
496 | int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) |
497 | { | |
1efdb69b | 498 | kuid_t euid = current_euid(); |
a33e6751 | 499 | int requested_mode, granted_mode; |
1da177e4 | 500 | |
a33e6751 | 501 | audit_ipc_obj(ipcp); |
1da177e4 LT |
502 | requested_mode = (flag >> 6) | (flag >> 3) | flag; |
503 | granted_mode = ipcp->mode; | |
1efdb69b EB |
504 | if (uid_eq(euid, ipcp->cuid) || |
505 | uid_eq(euid, ipcp->uid)) | |
1da177e4 LT |
506 | granted_mode >>= 6; |
507 | else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid)) | |
508 | granted_mode >>= 3; | |
509 | /* is there some bit set in requested_mode but not in granted_mode? */ | |
46c0a8ca | 510 | if ((requested_mode & ~granted_mode & 0007) && |
b0e77598 | 511 | !ns_capable(ns->user_ns, CAP_IPC_OWNER)) |
1da177e4 LT |
512 | return -1; |
513 | ||
514 | return security_ipc_permission(ipcp, flag); | |
515 | } | |
516 | ||
517 | /* | |
518 | * Functions to convert between the kern_ipc_perm structure and the | |
519 | * old/new ipc_perm structures | |
520 | */ | |
521 | ||
522 | /** | |
8001c858 DB |
523 | * kernel_to_ipc64_perm - convert kernel ipc permissions to user |
524 | * @in: kernel permissions | |
525 | * @out: new style ipc permissions | |
1da177e4 | 526 | * |
8001c858 DB |
527 | * Turn the kernel object @in into a set of permissions descriptions |
528 | * for returning to userspace (@out). | |
1da177e4 | 529 | */ |
239521f3 | 530 | void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out) |
1da177e4 LT |
531 | { |
532 | out->key = in->key; | |
1efdb69b EB |
533 | out->uid = from_kuid_munged(current_user_ns(), in->uid); |
534 | out->gid = from_kgid_munged(current_user_ns(), in->gid); | |
535 | out->cuid = from_kuid_munged(current_user_ns(), in->cuid); | |
536 | out->cgid = from_kgid_munged(current_user_ns(), in->cgid); | |
1da177e4 LT |
537 | out->mode = in->mode; |
538 | out->seq = in->seq; | |
539 | } | |
540 | ||
541 | /** | |
8001c858 DB |
542 | * ipc64_perm_to_ipc_perm - convert new ipc permissions to old |
543 | * @in: new style ipc permissions | |
544 | * @out: old style ipc permissions | |
1da177e4 | 545 | * |
8001c858 DB |
546 | * Turn the new style permissions object @in into a compatibility |
547 | * object and store it into the @out pointer. | |
1da177e4 | 548 | */ |
239521f3 | 549 | void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) |
1da177e4 LT |
550 | { |
551 | out->key = in->key; | |
552 | SET_UID(out->uid, in->uid); | |
553 | SET_GID(out->gid, in->gid); | |
554 | SET_UID(out->cuid, in->cuid); | |
555 | SET_GID(out->cgid, in->cgid); | |
556 | out->mode = in->mode; | |
557 | out->seq = in->seq; | |
558 | } | |
559 | ||
4d2bff5e | 560 | /** |
0cfb6aee | 561 | * ipc_obtain_object_idr |
4d2bff5e DB |
562 | * @ids: ipc identifier set |
563 | * @id: ipc id to look for | |
564 | * | |
565 | * Look for an id in the ipc ids idr and return associated ipc object. | |
566 | * | |
567 | * Call inside the RCU critical section. | |
568 | * The ipc object is *not* locked on exit. | |
569 | */ | |
55b7ae50 | 570 | struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) |
4d2bff5e DB |
571 | { |
572 | struct kern_ipc_perm *out; | |
573 | int lid = ipcid_to_idx(id); | |
574 | ||
0cfb6aee GK |
575 | if (unlikely(!ids->tables_initialized)) |
576 | return ERR_PTR(-EINVAL); | |
577 | ||
4d2bff5e DB |
578 | out = idr_find(&ids->ipcs_idr, lid); |
579 | if (!out) | |
580 | return ERR_PTR(-EINVAL); | |
581 | ||
582 | return out; | |
583 | } | |
584 | ||
f4566f04 | 585 | /** |
8001c858 DB |
586 | * ipc_lock - lock an ipc structure without rwsem held |
587 | * @ids: ipc identifier set | |
f4566f04 ND |
588 | * @id: ipc id to look for |
589 | * | |
590 | * Look for an id in the ipc ids idr and lock the associated ipc object. | |
591 | * | |
4d2bff5e | 592 | * The ipc object is locked on successful exit. |
f4566f04 | 593 | */ |
7ca7e564 | 594 | struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) |
1da177e4 | 595 | { |
7ca7e564 | 596 | struct kern_ipc_perm *out; |
1da177e4 LT |
597 | |
598 | rcu_read_lock(); | |
55b7ae50 | 599 | out = ipc_obtain_object_idr(ids, id); |
4d2bff5e | 600 | if (IS_ERR(out)) |
f8b59184 | 601 | goto err; |
7ca7e564 | 602 | |
1da177e4 | 603 | spin_lock(&out->lock); |
4d2bff5e | 604 | |
f8b59184 DB |
605 | /* |
606 | * ipc_rmid() may have already freed the ID while ipc_lock() | |
607 | * was spinning: here verify that the structure is still valid. | |
608 | * Upon races with RMID, return -EIDRM, thus indicating that | |
609 | * the ID points to a removed identifier. | |
1da177e4 | 610 | */ |
72a8ff2f | 611 | if (ipc_valid_object(out)) |
4d2bff5e DB |
612 | return out; |
613 | ||
614 | spin_unlock(&out->lock); | |
f8b59184 DB |
615 | out = ERR_PTR(-EIDRM); |
616 | err: | |
4d2bff5e DB |
617 | rcu_read_unlock(); |
618 | return out; | |
619 | } | |
7ca7e564 | 620 | |
4d2bff5e DB |
621 | /** |
622 | * ipc_obtain_object_check | |
623 | * @ids: ipc identifier set | |
624 | * @id: ipc id to look for | |
625 | * | |
55b7ae50 | 626 | * Similar to ipc_obtain_object_idr() but also checks |
4d2bff5e DB |
627 | * the ipc object reference counter. |
628 | * | |
629 | * Call inside the RCU critical section. | |
630 | * The ipc object is *not* locked on exit. | |
631 | */ | |
632 | struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id) | |
633 | { | |
55b7ae50 | 634 | struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id); |
4d2bff5e DB |
635 | |
636 | if (IS_ERR(out)) | |
637 | goto out; | |
638 | ||
639 | if (ipc_checkid(out, id)) | |
6157dbbf | 640 | return ERR_PTR(-EINVAL); |
4d2bff5e | 641 | out: |
1da177e4 LT |
642 | return out; |
643 | } | |
644 | ||
b2d75cdd PE |
645 | /** |
646 | * ipcget - Common sys_*get() code | |
da3dae54 | 647 | * @ns: namespace |
8001c858 DB |
648 | * @ids: ipc identifier set |
649 | * @ops: operations to be called on ipc object creation, permission checks | |
650 | * and further checks | |
651 | * @params: the parameters needed by the previous operations. | |
b2d75cdd PE |
652 | * |
653 | * Common routine called by sys_msgget(), sys_semget() and sys_shmget(). | |
654 | */ | |
655 | int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, | |
eb66ec44 | 656 | const struct ipc_ops *ops, struct ipc_params *params) |
b2d75cdd PE |
657 | { |
658 | if (params->key == IPC_PRIVATE) | |
659 | return ipcget_new(ns, ids, ops, params); | |
660 | else | |
661 | return ipcget_public(ns, ids, ops, params); | |
662 | } | |
663 | ||
8f4a3809 | 664 | /** |
8001c858 | 665 | * ipc_update_perm - update the permissions of an ipc object |
8f4a3809 PP |
666 | * @in: the permission given as input. |
667 | * @out: the permission of the ipc to set. | |
668 | */ | |
1efdb69b | 669 | int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) |
8f4a3809 | 670 | { |
1efdb69b EB |
671 | kuid_t uid = make_kuid(current_user_ns(), in->uid); |
672 | kgid_t gid = make_kgid(current_user_ns(), in->gid); | |
673 | if (!uid_valid(uid) || !gid_valid(gid)) | |
674 | return -EINVAL; | |
675 | ||
676 | out->uid = uid; | |
677 | out->gid = gid; | |
8f4a3809 PP |
678 | out->mode = (out->mode & ~S_IRWXUGO) |
679 | | (in->mode & S_IRWXUGO); | |
1efdb69b EB |
680 | |
681 | return 0; | |
8f4a3809 PP |
682 | } |
683 | ||
a5f75e7f | 684 | /** |
3b1c4ad3 | 685 | * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd |
8001c858 | 686 | * @ns: ipc namespace |
a5f75e7f PP |
687 | * @ids: the table of ids where to look for the ipc |
688 | * @id: the id of the ipc to retrieve | |
689 | * @cmd: the cmd to check | |
690 | * @perm: the permission to set | |
691 | * @extra_perm: one extra permission parameter used by msq | |
692 | * | |
693 | * This function does some common audit and permissions check for some IPC_XXX | |
694 | * cmd and is called from semctl_down, shmctl_down and msgctl_down. | |
0e056eb5 | 695 | * It must be called without any lock held and: |
696 | * | |
697 | * - retrieves the ipc with the given id in the given table. | |
698 | * - performs some audit and permission check, depending on the given cmd | |
699 | * - returns a pointer to the ipc object or otherwise, the corresponding | |
700 | * error. | |
7b4cc5d8 | 701 | * |
d9a605e4 | 702 | * Call holding the both the rwsem and the rcu read lock. |
a5f75e7f | 703 | */ |
444d0f62 | 704 | struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, |
3b1c4ad3 DB |
705 | struct ipc_ids *ids, int id, int cmd, |
706 | struct ipc64_perm *perm, int extra_perm) | |
444d0f62 | 707 | { |
1efdb69b | 708 | kuid_t euid; |
444d0f62 DB |
709 | int err = -EPERM; |
710 | struct kern_ipc_perm *ipcp; | |
a5f75e7f | 711 | |
444d0f62 | 712 | ipcp = ipc_obtain_object_check(ids, id); |
a5f75e7f PP |
713 | if (IS_ERR(ipcp)) { |
714 | err = PTR_ERR(ipcp); | |
7b4cc5d8 | 715 | goto err; |
a5f75e7f PP |
716 | } |
717 | ||
a33e6751 | 718 | audit_ipc_obj(ipcp); |
e816f370 AV |
719 | if (cmd == IPC_SET) |
720 | audit_ipc_set_perm(extra_perm, perm->uid, | |
444d0f62 | 721 | perm->gid, perm->mode); |
414c0708 DH |
722 | |
723 | euid = current_euid(); | |
1efdb69b | 724 | if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) || |
b0e77598 | 725 | ns_capable(ns->user_ns, CAP_SYS_ADMIN)) |
7b4cc5d8 DB |
726 | return ipcp; /* successful lookup */ |
727 | err: | |
a5f75e7f PP |
728 | return ERR_PTR(err); |
729 | } | |
730 | ||
c1d7e01d | 731 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION |
1da177e4 LT |
732 | |
733 | ||
734 | /** | |
8001c858 DB |
735 | * ipc_parse_version - ipc call version |
736 | * @cmd: pointer to command | |
1da177e4 | 737 | * |
8001c858 DB |
738 | * Return IPC_64 for new style IPC and IPC_OLD for old style IPC. |
739 | * The @cmd value is turned from an encoding command and version into | |
740 | * just the command code. | |
1da177e4 | 741 | */ |
239521f3 | 742 | int ipc_parse_version(int *cmd) |
1da177e4 LT |
743 | { |
744 | if (*cmd & IPC_64) { | |
745 | *cmd ^= IPC_64; | |
746 | return IPC_64; | |
747 | } else { | |
748 | return IPC_OLD; | |
749 | } | |
750 | } | |
751 | ||
c1d7e01d | 752 | #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */ |
ae781774 MW |
753 | |
754 | #ifdef CONFIG_PROC_FS | |
bc1fc6d8 EB |
755 | struct ipc_proc_iter { |
756 | struct ipc_namespace *ns; | |
03f1fc09 | 757 | struct pid_namespace *pid_ns; |
bc1fc6d8 EB |
758 | struct ipc_proc_iface *iface; |
759 | }; | |
760 | ||
03f1fc09 EB |
761 | struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) |
762 | { | |
763 | struct ipc_proc_iter *iter = s->private; | |
764 | return iter->pid_ns; | |
765 | } | |
766 | ||
7ca7e564 ND |
767 | /* |
768 | * This routine locks the ipc structure found at least at position pos. | |
769 | */ | |
b524b9ad AB |
770 | static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, |
771 | loff_t *new_pos) | |
ae781774 | 772 | { |
7ca7e564 ND |
773 | struct kern_ipc_perm *ipc; |
774 | int total, id; | |
73ea4130 | 775 | |
7ca7e564 ND |
776 | total = 0; |
777 | for (id = 0; id < pos && total < ids->in_use; id++) { | |
778 | ipc = idr_find(&ids->ipcs_idr, id); | |
779 | if (ipc != NULL) | |
780 | total++; | |
781 | } | |
ae781774 | 782 | |
7ca7e564 ND |
783 | if (total >= ids->in_use) |
784 | return NULL; | |
ae781774 | 785 | |
239521f3 | 786 | for (; pos < IPCMNI; pos++) { |
7ca7e564 ND |
787 | ipc = idr_find(&ids->ipcs_idr, pos); |
788 | if (ipc != NULL) { | |
789 | *new_pos = pos + 1; | |
32a27500 DB |
790 | rcu_read_lock(); |
791 | ipc_lock_object(ipc); | |
ae781774 MW |
792 | return ipc; |
793 | } | |
794 | } | |
795 | ||
796 | /* Out of range - return NULL to terminate iteration */ | |
797 | return NULL; | |
798 | } | |
799 | ||
7ca7e564 ND |
800 | static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) |
801 | { | |
802 | struct ipc_proc_iter *iter = s->private; | |
803 | struct ipc_proc_iface *iface = iter->iface; | |
804 | struct kern_ipc_perm *ipc = it; | |
805 | ||
806 | /* If we had an ipc id locked before, unlock it */ | |
807 | if (ipc && ipc != SEQ_START_TOKEN) | |
808 | ipc_unlock(ipc); | |
809 | ||
ed2ddbf8 | 810 | return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); |
7ca7e564 ND |
811 | } |
812 | ||
ae781774 | 813 | /* |
f4566f04 ND |
814 | * File positions: pos 0 -> header, pos n -> ipc id = n - 1. |
815 | * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. | |
ae781774 MW |
816 | */ |
817 | static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) | |
818 | { | |
bc1fc6d8 EB |
819 | struct ipc_proc_iter *iter = s->private; |
820 | struct ipc_proc_iface *iface = iter->iface; | |
73ea4130 KK |
821 | struct ipc_ids *ids; |
822 | ||
ed2ddbf8 | 823 | ids = &iter->ns->ids[iface->ids]; |
ae781774 MW |
824 | |
825 | /* | |
826 | * Take the lock - this will be released by the corresponding | |
827 | * call to stop(). | |
828 | */ | |
d9a605e4 | 829 | down_read(&ids->rwsem); |
ae781774 MW |
830 | |
831 | /* pos < 0 is invalid */ | |
832 | if (*pos < 0) | |
833 | return NULL; | |
834 | ||
835 | /* pos == 0 means header */ | |
836 | if (*pos == 0) | |
837 | return SEQ_START_TOKEN; | |
838 | ||
839 | /* Find the (pos-1)th ipc */ | |
7ca7e564 | 840 | return sysvipc_find_ipc(ids, *pos - 1, pos); |
ae781774 MW |
841 | } |
842 | ||
843 | static void sysvipc_proc_stop(struct seq_file *s, void *it) | |
844 | { | |
845 | struct kern_ipc_perm *ipc = it; | |
bc1fc6d8 EB |
846 | struct ipc_proc_iter *iter = s->private; |
847 | struct ipc_proc_iface *iface = iter->iface; | |
73ea4130 | 848 | struct ipc_ids *ids; |
ae781774 | 849 | |
f4566f04 | 850 | /* If we had a locked structure, release it */ |
ae781774 MW |
851 | if (ipc && ipc != SEQ_START_TOKEN) |
852 | ipc_unlock(ipc); | |
853 | ||
ed2ddbf8 | 854 | ids = &iter->ns->ids[iface->ids]; |
ae781774 | 855 | /* Release the lock we took in start() */ |
d9a605e4 | 856 | up_read(&ids->rwsem); |
ae781774 MW |
857 | } |
858 | ||
859 | static int sysvipc_proc_show(struct seq_file *s, void *it) | |
860 | { | |
bc1fc6d8 EB |
861 | struct ipc_proc_iter *iter = s->private; |
862 | struct ipc_proc_iface *iface = iter->iface; | |
ae781774 | 863 | |
7f032d6e JP |
864 | if (it == SEQ_START_TOKEN) { |
865 | seq_puts(s, iface->header); | |
866 | return 0; | |
867 | } | |
ae781774 MW |
868 | |
869 | return iface->show(s, it); | |
870 | } | |
871 | ||
88e9d34c | 872 | static const struct seq_operations sysvipc_proc_seqops = { |
ae781774 MW |
873 | .start = sysvipc_proc_start, |
874 | .stop = sysvipc_proc_stop, | |
875 | .next = sysvipc_proc_next, | |
876 | .show = sysvipc_proc_show, | |
877 | }; | |
878 | ||
bc1fc6d8 EB |
879 | static int sysvipc_proc_open(struct inode *inode, struct file *file) |
880 | { | |
bc1fc6d8 EB |
881 | struct ipc_proc_iter *iter; |
882 | ||
d66a0520 | 883 | iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); |
bc1fc6d8 | 884 | if (!iter) |
d66a0520 | 885 | return -ENOMEM; |
bc1fc6d8 | 886 | |
d9dda78b | 887 | iter->iface = PDE_DATA(inode); |
bc1fc6d8 | 888 | iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); |
03f1fc09 | 889 | iter->pid_ns = get_pid_ns(task_active_pid_ns(current)); |
d66a0520 RJ |
890 | |
891 | return 0; | |
bc1fc6d8 EB |
892 | } |
893 | ||
894 | static int sysvipc_proc_release(struct inode *inode, struct file *file) | |
895 | { | |
896 | struct seq_file *seq = file->private_data; | |
897 | struct ipc_proc_iter *iter = seq->private; | |
898 | put_ipc_ns(iter->ns); | |
03f1fc09 | 899 | put_pid_ns(iter->pid_ns); |
bc1fc6d8 | 900 | return seq_release_private(inode, file); |
ae781774 MW |
901 | } |
902 | ||
9a32144e | 903 | static const struct file_operations sysvipc_proc_fops = { |
ae781774 MW |
904 | .open = sysvipc_proc_open, |
905 | .read = seq_read, | |
906 | .llseek = seq_lseek, | |
bc1fc6d8 | 907 | .release = sysvipc_proc_release, |
ae781774 MW |
908 | }; |
909 | #endif /* CONFIG_PROC_FS */ |