Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/ipc/sem.c | |
3 | * Copyright (C) 1992 Krishna Balasubramanian | |
4 | * Copyright (C) 1995 Eric Schenk, Bruno Haible | |
5 | * | |
1da177e4 LT |
6 | * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
7 | * | |
8 | * SMP-threaded, sysctl's added | |
624dffcb | 9 | * (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
1da177e4 | 10 | * Enforced range limit on SEM_UNDO |
046c6884 | 11 | * (c) 2001 Red Hat Inc |
1da177e4 LT |
12 | * Lockless wakeup |
13 | * (c) 2003 Manfred Spraul <manfred@colorfullife.com> | |
9ae949fa | 14 | * (c) 2016 Davidlohr Bueso <dave@stgolabs.net> |
c5cf6359 MS |
15 | * Further wakeup optimizations, documentation |
16 | * (c) 2010 Manfred Spraul <manfred@colorfullife.com> | |
073115d6 SG |
17 | * |
18 | * support for audit of ipc object properties and permission changes | |
19 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> | |
e3893534 KK |
20 | * |
21 | * namespaces support | |
22 | * OpenVZ, SWsoft Inc. | |
23 | * Pavel Emelianov <xemul@openvz.org> | |
c5cf6359 MS |
24 | * |
25 | * Implementation notes: (May 2010) | |
26 | * This file implements System V semaphores. | |
27 | * | |
28 | * User space visible behavior: | |
29 | * - FIFO ordering for semop() operations (just FIFO, not starvation | |
30 | * protection) | |
31 | * - multiple semaphore operations that alter the same semaphore in | |
32 | * one semop() are handled. | |
33 | * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and | |
34 | * SETALL calls. | |
35 | * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO. | |
36 | * - undo adjustments at process exit are limited to 0..SEMVMX. | |
37 | * - namespace are supported. | |
38 | * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing | |
39 | * to /proc/sys/kernel/sem. | |
40 | * - statistics about the usage are reported in /proc/sysvipc/sem. | |
41 | * | |
42 | * Internals: | |
43 | * - scalability: | |
44 | * - all global variables are read-mostly. | |
45 | * - semop() calls and semctl(RMID) are synchronized by RCU. | |
46 | * - most operations do write operations (actually: spin_lock calls) to | |
47 | * the per-semaphore array structure. | |
48 | * Thus: Perfect SMP scaling between independent semaphore arrays. | |
49 | * If multiple semaphores in one array are used, then cache line | |
50 | * trashing on the semaphore array spinlock will limit the scaling. | |
2f2ed41d | 51 | * - semncnt and semzcnt are calculated on demand in count_semcnt() |
c5cf6359 MS |
52 | * - the task that performs a successful semop() scans the list of all |
53 | * sleeping tasks and completes any pending operations that can be fulfilled. | |
54 | * Semaphores are actively given to waiting tasks (necessary for FIFO). | |
55 | * (see update_queue()) | |
56 | * - To improve the scalability, the actual wake-up calls are performed after | |
9ae949fa | 57 | * dropping all locks. (see wake_up_sem_queue_prepare()) |
c5cf6359 MS |
58 | * - All work is done by the waker, the woken up task does not have to do |
59 | * anything - not even acquiring a lock or dropping a refcount. | |
60 | * - A woken up task may not even touch the semaphore array anymore, it may | |
61 | * have been destroyed already by a semctl(RMID). | |
c5cf6359 MS |
62 | * - UNDO values are stored in an array (one per process and per |
63 | * semaphore array, lazily allocated). For backwards compatibility, multiple | |
64 | * modes for the UNDO variables are supported (per process, per thread) | |
65 | * (see copy_semundo, CLONE_SYSVSEM) | |
66 | * - There are two lists of the pending operations: a per-array list | |
67 | * and per-semaphore list (stored in the array). This allows to achieve FIFO | |
68 | * ordering without always scanning all pending operations. | |
69 | * The worst-case behavior is nevertheless O(N^2) for N wakeups. | |
1da177e4 LT |
70 | */ |
71 | ||
1da177e4 LT |
72 | #include <linux/slab.h> |
73 | #include <linux/spinlock.h> | |
74 | #include <linux/init.h> | |
75 | #include <linux/proc_fs.h> | |
76 | #include <linux/time.h> | |
1da177e4 LT |
77 | #include <linux/security.h> |
78 | #include <linux/syscalls.h> | |
79 | #include <linux/audit.h> | |
c59ede7b | 80 | #include <linux/capability.h> |
19b4946c | 81 | #include <linux/seq_file.h> |
3e148c79 | 82 | #include <linux/rwsem.h> |
e3893534 | 83 | #include <linux/nsproxy.h> |
ae5e1b22 | 84 | #include <linux/ipc_namespace.h> |
5f921ae9 | 85 | |
7153e402 | 86 | #include <linux/uaccess.h> |
1da177e4 LT |
87 | #include "util.h" |
88 | ||
e57940d7 MS |
89 | /* One semaphore structure for each semaphore in the system. */ |
90 | struct sem { | |
91 | int semval; /* current value */ | |
a5f4db87 DB |
92 | /* |
93 | * PID of the process that last modified the semaphore. For | |
94 | * Linux, specifically these are: | |
95 | * - semop | |
96 | * - semctl, via SETVAL and SETALL. | |
97 | * - at task exit when performing undo adjustments (see exit_sem). | |
98 | */ | |
99 | int sempid; | |
6062a8dc | 100 | spinlock_t lock; /* spinlock for fine-grained semtimedop */ |
1a82e9e1 MS |
101 | struct list_head pending_alter; /* pending single-sop operations */ |
102 | /* that alter the semaphore */ | |
103 | struct list_head pending_const; /* pending single-sop operations */ | |
104 | /* that do not alter the semaphore*/ | |
d12e1e50 | 105 | time_t sem_otime; /* candidate for sem_otime */ |
f5c936c0 | 106 | } ____cacheline_aligned_in_smp; |
e57940d7 MS |
107 | |
108 | /* One queue for each sleeping process in the system. */ | |
109 | struct sem_queue { | |
e57940d7 MS |
110 | struct list_head list; /* queue of pending operations */ |
111 | struct task_struct *sleeper; /* this process */ | |
112 | struct sem_undo *undo; /* undo structure */ | |
113 | int pid; /* process id of requesting process */ | |
114 | int status; /* completion status of operation */ | |
115 | struct sembuf *sops; /* array of pending operations */ | |
ed247b7c | 116 | struct sembuf *blocking; /* the operation that blocked */ |
e57940d7 MS |
117 | int nsops; /* number of operations */ |
118 | int alter; /* does *sops alter the array? */ | |
119 | }; | |
120 | ||
121 | /* Each task has a list of undo requests. They are executed automatically | |
122 | * when the process exits. | |
123 | */ | |
124 | struct sem_undo { | |
125 | struct list_head list_proc; /* per-process list: * | |
126 | * all undos from one process | |
127 | * rcu protected */ | |
128 | struct rcu_head rcu; /* rcu struct for sem_undo */ | |
129 | struct sem_undo_list *ulp; /* back ptr to sem_undo_list */ | |
130 | struct list_head list_id; /* per semaphore array list: | |
131 | * all undos for one array */ | |
132 | int semid; /* semaphore set identifier */ | |
133 | short *semadj; /* array of adjustments */ | |
134 | /* one per semaphore */ | |
135 | }; | |
136 | ||
137 | /* sem_undo_list controls shared access to the list of sem_undo structures | |
138 | * that may be shared among all a CLONE_SYSVSEM task group. | |
139 | */ | |
140 | struct sem_undo_list { | |
141 | atomic_t refcnt; | |
142 | spinlock_t lock; | |
143 | struct list_head list_proc; | |
144 | }; | |
145 | ||
146 | ||
ed2ddbf8 | 147 | #define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS]) |
e3893534 | 148 | |
1b531f21 | 149 | #define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid) |
1da177e4 | 150 | |
7748dbfa | 151 | static int newary(struct ipc_namespace *, struct ipc_params *); |
01b8b07a | 152 | static void freeary(struct ipc_namespace *, struct kern_ipc_perm *); |
1da177e4 | 153 | #ifdef CONFIG_PROC_FS |
19b4946c | 154 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it); |
1da177e4 LT |
155 | #endif |
156 | ||
157 | #define SEMMSL_FAST 256 /* 512 bytes on stack */ | |
158 | #define SEMOPM_FAST 64 /* ~ 372 bytes on stack */ | |
159 | ||
160 | /* | |
758a6ba3 | 161 | * Locking: |
5864a2fd | 162 | * a) global sem_lock() for read/write |
1da177e4 | 163 | * sem_undo.id_next, |
758a6ba3 | 164 | * sem_array.complex_count, |
5864a2fd MS |
165 | * sem_array.complex_mode |
166 | * sem_array.pending{_alter,_const}, | |
167 | * sem_array.sem_undo | |
46c0a8ca | 168 | * |
5864a2fd | 169 | * b) global or semaphore sem_lock() for read/write: |
758a6ba3 | 170 | * sem_array.sem_base[i].pending_{const,alter}: |
5864a2fd MS |
171 | * sem_array.complex_mode (for read) |
172 | * | |
173 | * c) special: | |
174 | * sem_undo_list.list_proc: | |
175 | * * undo_list->lock for write | |
176 | * * rcu for read | |
1da177e4 LT |
177 | */ |
178 | ||
e3893534 KK |
179 | #define sc_semmsl sem_ctls[0] |
180 | #define sc_semmns sem_ctls[1] | |
181 | #define sc_semopm sem_ctls[2] | |
182 | #define sc_semmni sem_ctls[3] | |
183 | ||
ed2ddbf8 | 184 | void sem_init_ns(struct ipc_namespace *ns) |
e3893534 | 185 | { |
e3893534 KK |
186 | ns->sc_semmsl = SEMMSL; |
187 | ns->sc_semmns = SEMMNS; | |
188 | ns->sc_semopm = SEMOPM; | |
189 | ns->sc_semmni = SEMMNI; | |
190 | ns->used_sems = 0; | |
ed2ddbf8 | 191 | ipc_init_ids(&ns->ids[IPC_SEM_IDS]); |
e3893534 KK |
192 | } |
193 | ||
ae5e1b22 | 194 | #ifdef CONFIG_IPC_NS |
e3893534 KK |
195 | void sem_exit_ns(struct ipc_namespace *ns) |
196 | { | |
01b8b07a | 197 | free_ipcs(ns, &sem_ids(ns), freeary); |
7d6feeb2 | 198 | idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr); |
e3893534 | 199 | } |
ae5e1b22 | 200 | #endif |
1da177e4 | 201 | |
239521f3 | 202 | void __init sem_init(void) |
1da177e4 | 203 | { |
ed2ddbf8 | 204 | sem_init_ns(&init_ipc_ns); |
19b4946c MW |
205 | ipc_init_proc_interface("sysvipc/sem", |
206 | " key semid perms nsems uid gid cuid cgid otime ctime\n", | |
e3893534 | 207 | IPC_SEM_IDS, sysvipc_sem_proc_show); |
1da177e4 LT |
208 | } |
209 | ||
f269f40a MS |
210 | /** |
211 | * unmerge_queues - unmerge queues, if possible. | |
212 | * @sma: semaphore array | |
213 | * | |
214 | * The function unmerges the wait queues if complex_count is 0. | |
215 | * It must be called prior to dropping the global semaphore array lock. | |
216 | */ | |
217 | static void unmerge_queues(struct sem_array *sma) | |
218 | { | |
219 | struct sem_queue *q, *tq; | |
220 | ||
221 | /* complex operations still around? */ | |
222 | if (sma->complex_count) | |
223 | return; | |
224 | /* | |
225 | * We will switch back to simple mode. | |
226 | * Move all pending operation back into the per-semaphore | |
227 | * queues. | |
228 | */ | |
229 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { | |
230 | struct sem *curr; | |
231 | curr = &sma->sem_base[q->sops[0].sem_num]; | |
232 | ||
233 | list_add_tail(&q->list, &curr->pending_alter); | |
234 | } | |
235 | INIT_LIST_HEAD(&sma->pending_alter); | |
236 | } | |
237 | ||
238 | /** | |
8001c858 | 239 | * merge_queues - merge single semop queues into global queue |
f269f40a MS |
240 | * @sma: semaphore array |
241 | * | |
242 | * This function merges all per-semaphore queues into the global queue. | |
243 | * It is necessary to achieve FIFO ordering for the pending single-sop | |
244 | * operations when a multi-semop operation must sleep. | |
245 | * Only the alter operations must be moved, the const operations can stay. | |
246 | */ | |
247 | static void merge_queues(struct sem_array *sma) | |
248 | { | |
249 | int i; | |
250 | for (i = 0; i < sma->sem_nsems; i++) { | |
251 | struct sem *sem = sma->sem_base + i; | |
252 | ||
253 | list_splice_init(&sem->pending_alter, &sma->pending_alter); | |
254 | } | |
255 | } | |
256 | ||
53dad6d3 DB |
257 | static void sem_rcu_free(struct rcu_head *head) |
258 | { | |
259 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); | |
260 | struct sem_array *sma = ipc_rcu_to_struct(p); | |
261 | ||
262 | security_sem_free(sma); | |
263 | ipc_rcu_free(head); | |
264 | } | |
265 | ||
5e9d5275 | 266 | /* |
5864a2fd | 267 | * Enter the mode suitable for non-simple operations: |
5e9d5275 | 268 | * Caller must own sem_perm.lock. |
5e9d5275 | 269 | */ |
5864a2fd | 270 | static void complexmode_enter(struct sem_array *sma) |
5e9d5275 MS |
271 | { |
272 | int i; | |
273 | struct sem *sem; | |
274 | ||
5864a2fd MS |
275 | if (sma->complex_mode) { |
276 | /* We are already in complex_mode. Nothing to do */ | |
6d07b68c MS |
277 | return; |
278 | } | |
279 | ||
5864a2fd MS |
280 | /* We need a full barrier after seting complex_mode: |
281 | * The write to complex_mode must be visible | |
282 | * before we read the first sem->lock spinlock state. | |
283 | */ | |
284 | smp_store_mb(sma->complex_mode, true); | |
285 | ||
5e9d5275 MS |
286 | for (i = 0; i < sma->sem_nsems; i++) { |
287 | sem = sma->sem_base + i; | |
288 | spin_unlock_wait(&sem->lock); | |
289 | } | |
5864a2fd MS |
290 | /* |
291 | * spin_unlock_wait() is not a memory barriers, it is only a | |
292 | * control barrier. The code must pair with spin_unlock(&sem->lock), | |
293 | * thus just the control barrier is insufficient. | |
294 | * | |
295 | * smp_rmb() is sufficient, as writes cannot pass the control barrier. | |
296 | */ | |
297 | smp_rmb(); | |
298 | } | |
299 | ||
300 | /* | |
301 | * Try to leave the mode that disallows simple operations: | |
302 | * Caller must own sem_perm.lock. | |
303 | */ | |
304 | static void complexmode_tryleave(struct sem_array *sma) | |
305 | { | |
306 | if (sma->complex_count) { | |
307 | /* Complex ops are sleeping. | |
308 | * We must stay in complex mode | |
309 | */ | |
310 | return; | |
311 | } | |
312 | /* | |
313 | * Immediately after setting complex_mode to false, | |
314 | * a simple op can start. Thus: all memory writes | |
315 | * performed by the current operation must be visible | |
316 | * before we set complex_mode to false. | |
317 | */ | |
318 | smp_store_release(&sma->complex_mode, false); | |
5e9d5275 MS |
319 | } |
320 | ||
5864a2fd | 321 | #define SEM_GLOBAL_LOCK (-1) |
6062a8dc RR |
322 | /* |
323 | * If the request contains only one semaphore operation, and there are | |
324 | * no complex transactions pending, lock only the semaphore involved. | |
325 | * Otherwise, lock the entire semaphore array, since we either have | |
326 | * multiple semaphores in our own semops, or we need to look at | |
327 | * semaphores from other pending complex operations. | |
6062a8dc RR |
328 | */ |
329 | static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, | |
330 | int nsops) | |
331 | { | |
5e9d5275 | 332 | struct sem *sem; |
6062a8dc | 333 | |
5e9d5275 MS |
334 | if (nsops != 1) { |
335 | /* Complex operation - acquire a full lock */ | |
336 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 337 | |
5864a2fd MS |
338 | /* Prevent parallel simple ops */ |
339 | complexmode_enter(sma); | |
340 | return SEM_GLOBAL_LOCK; | |
5e9d5275 MS |
341 | } |
342 | ||
343 | /* | |
344 | * Only one semaphore affected - try to optimize locking. | |
5864a2fd MS |
345 | * Optimized locking is possible if no complex operation |
346 | * is either enqueued or processed right now. | |
347 | * | |
348 | * Both facts are tracked by complex_mode. | |
5e9d5275 MS |
349 | */ |
350 | sem = sma->sem_base + sops->sem_num; | |
6062a8dc | 351 | |
5864a2fd MS |
352 | /* |
353 | * Initial check for complex_mode. Just an optimization, | |
354 | * no locking, no memory barrier. | |
355 | */ | |
356 | if (!sma->complex_mode) { | |
6062a8dc | 357 | /* |
5e9d5275 MS |
358 | * It appears that no complex operation is around. |
359 | * Acquire the per-semaphore lock. | |
6062a8dc | 360 | */ |
5e9d5275 MS |
361 | spin_lock(&sem->lock); |
362 | ||
5864a2fd MS |
363 | /* |
364 | * See 51d7d5205d33 | |
365 | * ("powerpc: Add smp_mb() to arch_spin_is_locked()"): | |
366 | * A full barrier is required: the write of sem->lock | |
367 | * must be visible before the read is executed | |
368 | */ | |
369 | smp_mb(); | |
5e9d5275 | 370 | |
5864a2fd MS |
371 | if (!smp_load_acquire(&sma->complex_mode)) { |
372 | /* fast path successful! */ | |
373 | return sops->sem_num; | |
6062a8dc | 374 | } |
5e9d5275 MS |
375 | spin_unlock(&sem->lock); |
376 | } | |
377 | ||
378 | /* slow path: acquire the full lock */ | |
379 | ipc_lock_object(&sma->sem_perm); | |
6062a8dc | 380 | |
5e9d5275 MS |
381 | if (sma->complex_count == 0) { |
382 | /* False alarm: | |
383 | * There is no complex operation, thus we can switch | |
384 | * back to the fast path. | |
385 | */ | |
386 | spin_lock(&sem->lock); | |
387 | ipc_unlock_object(&sma->sem_perm); | |
388 | return sops->sem_num; | |
6062a8dc | 389 | } else { |
5e9d5275 MS |
390 | /* Not a false alarm, thus complete the sequence for a |
391 | * full lock. | |
6062a8dc | 392 | */ |
5864a2fd MS |
393 | complexmode_enter(sma); |
394 | return SEM_GLOBAL_LOCK; | |
6062a8dc | 395 | } |
6062a8dc RR |
396 | } |
397 | ||
398 | static inline void sem_unlock(struct sem_array *sma, int locknum) | |
399 | { | |
5864a2fd | 400 | if (locknum == SEM_GLOBAL_LOCK) { |
f269f40a | 401 | unmerge_queues(sma); |
5864a2fd | 402 | complexmode_tryleave(sma); |
cf9d5d78 | 403 | ipc_unlock_object(&sma->sem_perm); |
6062a8dc RR |
404 | } else { |
405 | struct sem *sem = sma->sem_base + locknum; | |
406 | spin_unlock(&sem->lock); | |
407 | } | |
6062a8dc RR |
408 | } |
409 | ||
3e148c79 | 410 | /* |
d9a605e4 | 411 | * sem_lock_(check_) routines are called in the paths where the rwsem |
3e148c79 | 412 | * is not held. |
321310ce LT |
413 | * |
414 | * The caller holds the RCU read lock. | |
3e148c79 | 415 | */ |
6062a8dc RR |
416 | static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, |
417 | int id, struct sembuf *sops, int nsops, int *locknum) | |
023a5355 | 418 | { |
c460b662 RR |
419 | struct kern_ipc_perm *ipcp; |
420 | struct sem_array *sma; | |
03f02c76 | 421 | |
55b7ae50 | 422 | ipcp = ipc_obtain_object_idr(&sem_ids(ns), id); |
321310ce LT |
423 | if (IS_ERR(ipcp)) |
424 | return ERR_CAST(ipcp); | |
b1ed88b4 | 425 | |
6062a8dc RR |
426 | sma = container_of(ipcp, struct sem_array, sem_perm); |
427 | *locknum = sem_lock(sma, sops, nsops); | |
c460b662 RR |
428 | |
429 | /* ipc_rmid() may have already freed the ID while sem_lock | |
430 | * was spinning: verify that the structure is still valid | |
431 | */ | |
72a8ff2f | 432 | if (ipc_valid_object(ipcp)) |
c460b662 RR |
433 | return container_of(ipcp, struct sem_array, sem_perm); |
434 | ||
6062a8dc | 435 | sem_unlock(sma, *locknum); |
321310ce | 436 | return ERR_PTR(-EINVAL); |
023a5355 ND |
437 | } |
438 | ||
16df3674 DB |
439 | static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id) |
440 | { | |
55b7ae50 | 441 | struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&sem_ids(ns), id); |
16df3674 DB |
442 | |
443 | if (IS_ERR(ipcp)) | |
444 | return ERR_CAST(ipcp); | |
445 | ||
446 | return container_of(ipcp, struct sem_array, sem_perm); | |
447 | } | |
448 | ||
16df3674 DB |
449 | static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns, |
450 | int id) | |
451 | { | |
452 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&sem_ids(ns), id); | |
453 | ||
454 | if (IS_ERR(ipcp)) | |
455 | return ERR_CAST(ipcp); | |
b1ed88b4 | 456 | |
03f02c76 | 457 | return container_of(ipcp, struct sem_array, sem_perm); |
023a5355 ND |
458 | } |
459 | ||
6ff37972 PP |
460 | static inline void sem_lock_and_putref(struct sem_array *sma) |
461 | { | |
6062a8dc | 462 | sem_lock(sma, NULL, -1); |
9b24fef9 | 463 | ipc_rcu_putref(sma, sem_rcu_free); |
6ff37972 PP |
464 | } |
465 | ||
7ca7e564 ND |
466 | static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) |
467 | { | |
468 | ipc_rmid(&sem_ids(ns), &s->sem_perm); | |
469 | } | |
470 | ||
f4566f04 ND |
471 | /** |
472 | * newary - Create a new semaphore set | |
473 | * @ns: namespace | |
474 | * @params: ptr to the structure that contains key, semflg and nsems | |
475 | * | |
d9a605e4 | 476 | * Called with sem_ids.rwsem held (as a writer) |
f4566f04 | 477 | */ |
7748dbfa | 478 | static int newary(struct ipc_namespace *ns, struct ipc_params *params) |
1da177e4 LT |
479 | { |
480 | int id; | |
481 | int retval; | |
482 | struct sem_array *sma; | |
483 | int size; | |
7748dbfa ND |
484 | key_t key = params->key; |
485 | int nsems = params->u.nsems; | |
486 | int semflg = params->flg; | |
b97e820f | 487 | int i; |
1da177e4 LT |
488 | |
489 | if (!nsems) | |
490 | return -EINVAL; | |
e3893534 | 491 | if (ns->used_sems + nsems > ns->sc_semmns) |
1da177e4 LT |
492 | return -ENOSPC; |
493 | ||
239521f3 | 494 | size = sizeof(*sma) + nsems * sizeof(struct sem); |
1da177e4 | 495 | sma = ipc_rcu_alloc(size); |
3ab08fe2 | 496 | if (!sma) |
1da177e4 | 497 | return -ENOMEM; |
3ab08fe2 | 498 | |
239521f3 | 499 | memset(sma, 0, size); |
1da177e4 LT |
500 | |
501 | sma->sem_perm.mode = (semflg & S_IRWXUGO); | |
502 | sma->sem_perm.key = key; | |
503 | ||
504 | sma->sem_perm.security = NULL; | |
505 | retval = security_sem_alloc(sma); | |
506 | if (retval) { | |
53dad6d3 | 507 | ipc_rcu_putref(sma, ipc_rcu_free); |
1da177e4 LT |
508 | return retval; |
509 | } | |
510 | ||
1da177e4 | 511 | sma->sem_base = (struct sem *) &sma[1]; |
b97e820f | 512 | |
6062a8dc | 513 | for (i = 0; i < nsems; i++) { |
1a82e9e1 MS |
514 | INIT_LIST_HEAD(&sma->sem_base[i].pending_alter); |
515 | INIT_LIST_HEAD(&sma->sem_base[i].pending_const); | |
6062a8dc RR |
516 | spin_lock_init(&sma->sem_base[i].lock); |
517 | } | |
b97e820f MS |
518 | |
519 | sma->complex_count = 0; | |
5864a2fd | 520 | sma->complex_mode = true; /* dropped by sem_unlock below */ |
1a82e9e1 MS |
521 | INIT_LIST_HEAD(&sma->pending_alter); |
522 | INIT_LIST_HEAD(&sma->pending_const); | |
4daa28f6 | 523 | INIT_LIST_HEAD(&sma->list_id); |
1da177e4 LT |
524 | sma->sem_nsems = nsems; |
525 | sma->sem_ctime = get_seconds(); | |
e8577d1f MS |
526 | |
527 | id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); | |
528 | if (id < 0) { | |
529 | ipc_rcu_putref(sma, sem_rcu_free); | |
530 | return id; | |
531 | } | |
532 | ns->used_sems += nsems; | |
533 | ||
6062a8dc | 534 | sem_unlock(sma, -1); |
6d49dab8 | 535 | rcu_read_unlock(); |
1da177e4 | 536 | |
7ca7e564 | 537 | return sma->sem_perm.id; |
1da177e4 LT |
538 | } |
539 | ||
7748dbfa | 540 | |
f4566f04 | 541 | /* |
d9a605e4 | 542 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 543 | */ |
03f02c76 | 544 | static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) |
7748dbfa | 545 | { |
03f02c76 ND |
546 | struct sem_array *sma; |
547 | ||
548 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
549 | return security_sem_associate(sma, semflg); | |
7748dbfa ND |
550 | } |
551 | ||
f4566f04 | 552 | /* |
d9a605e4 | 553 | * Called with sem_ids.rwsem and ipcp locked. |
f4566f04 | 554 | */ |
03f02c76 ND |
555 | static inline int sem_more_checks(struct kern_ipc_perm *ipcp, |
556 | struct ipc_params *params) | |
7748dbfa | 557 | { |
03f02c76 ND |
558 | struct sem_array *sma; |
559 | ||
560 | sma = container_of(ipcp, struct sem_array, sem_perm); | |
561 | if (params->u.nsems > sma->sem_nsems) | |
7748dbfa ND |
562 | return -EINVAL; |
563 | ||
564 | return 0; | |
565 | } | |
566 | ||
d5460c99 | 567 | SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) |
1da177e4 | 568 | { |
e3893534 | 569 | struct ipc_namespace *ns; |
eb66ec44 MK |
570 | static const struct ipc_ops sem_ops = { |
571 | .getnew = newary, | |
572 | .associate = sem_security, | |
573 | .more_checks = sem_more_checks, | |
574 | }; | |
7748dbfa | 575 | struct ipc_params sem_params; |
e3893534 KK |
576 | |
577 | ns = current->nsproxy->ipc_ns; | |
1da177e4 | 578 | |
e3893534 | 579 | if (nsems < 0 || nsems > ns->sc_semmsl) |
1da177e4 | 580 | return -EINVAL; |
7ca7e564 | 581 | |
7748dbfa ND |
582 | sem_params.key = key; |
583 | sem_params.flg = semflg; | |
584 | sem_params.u.nsems = nsems; | |
1da177e4 | 585 | |
7748dbfa | 586 | return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); |
1da177e4 LT |
587 | } |
588 | ||
78f5009c PM |
589 | /** |
590 | * perform_atomic_semop - Perform (if possible) a semaphore operation | |
758a6ba3 | 591 | * @sma: semaphore array |
d198cd6d | 592 | * @q: struct sem_queue that describes the operation |
758a6ba3 MS |
593 | * |
594 | * Returns 0 if the operation was possible. | |
595 | * Returns 1 if the operation is impossible, the caller must sleep. | |
596 | * Negative values are error codes. | |
1da177e4 | 597 | */ |
d198cd6d | 598 | static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q) |
1da177e4 | 599 | { |
d198cd6d | 600 | int result, sem_op, nsops, pid; |
1da177e4 | 601 | struct sembuf *sop; |
239521f3 | 602 | struct sem *curr; |
d198cd6d MS |
603 | struct sembuf *sops; |
604 | struct sem_undo *un; | |
605 | ||
606 | sops = q->sops; | |
607 | nsops = q->nsops; | |
608 | un = q->undo; | |
1da177e4 LT |
609 | |
610 | for (sop = sops; sop < sops + nsops; sop++) { | |
611 | curr = sma->sem_base + sop->sem_num; | |
612 | sem_op = sop->sem_op; | |
613 | result = curr->semval; | |
78f5009c | 614 | |
1da177e4 LT |
615 | if (!sem_op && result) |
616 | goto would_block; | |
617 | ||
618 | result += sem_op; | |
619 | if (result < 0) | |
620 | goto would_block; | |
621 | if (result > SEMVMX) | |
622 | goto out_of_range; | |
78f5009c | 623 | |
1da177e4 LT |
624 | if (sop->sem_flg & SEM_UNDO) { |
625 | int undo = un->semadj[sop->sem_num] - sem_op; | |
78f5009c | 626 | /* Exceeding the undo range is an error. */ |
1da177e4 LT |
627 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) |
628 | goto out_of_range; | |
78f5009c | 629 | un->semadj[sop->sem_num] = undo; |
1da177e4 | 630 | } |
78f5009c | 631 | |
1da177e4 LT |
632 | curr->semval = result; |
633 | } | |
634 | ||
635 | sop--; | |
d198cd6d | 636 | pid = q->pid; |
1da177e4 LT |
637 | while (sop >= sops) { |
638 | sma->sem_base[sop->sem_num].sempid = pid; | |
1da177e4 LT |
639 | sop--; |
640 | } | |
78f5009c | 641 | |
1da177e4 LT |
642 | return 0; |
643 | ||
644 | out_of_range: | |
645 | result = -ERANGE; | |
646 | goto undo; | |
647 | ||
648 | would_block: | |
ed247b7c MS |
649 | q->blocking = sop; |
650 | ||
1da177e4 LT |
651 | if (sop->sem_flg & IPC_NOWAIT) |
652 | result = -EAGAIN; | |
653 | else | |
654 | result = 1; | |
655 | ||
656 | undo: | |
657 | sop--; | |
658 | while (sop >= sops) { | |
78f5009c PM |
659 | sem_op = sop->sem_op; |
660 | sma->sem_base[sop->sem_num].semval -= sem_op; | |
661 | if (sop->sem_flg & SEM_UNDO) | |
662 | un->semadj[sop->sem_num] += sem_op; | |
1da177e4 LT |
663 | sop--; |
664 | } | |
665 | ||
666 | return result; | |
667 | } | |
668 | ||
9ae949fa DB |
669 | static inline void wake_up_sem_queue_prepare(struct sem_queue *q, int error, |
670 | struct wake_q_head *wake_q) | |
0a2b9d4c | 671 | { |
9ae949fa DB |
672 | wake_q_add(wake_q, q->sleeper); |
673 | /* | |
674 | * Rely on the above implicit barrier, such that we can | |
675 | * ensure that we hold reference to the task before setting | |
676 | * q->status. Otherwise we could race with do_exit if the | |
677 | * task is awoken by an external event before calling | |
678 | * wake_up_process(). | |
679 | */ | |
680 | WRITE_ONCE(q->status, error); | |
d4212093 NP |
681 | } |
682 | ||
b97e820f MS |
683 | static void unlink_queue(struct sem_array *sma, struct sem_queue *q) |
684 | { | |
685 | list_del(&q->list); | |
9f1bc2c9 | 686 | if (q->nsops > 1) |
b97e820f MS |
687 | sma->complex_count--; |
688 | } | |
689 | ||
fd5db422 MS |
690 | /** check_restart(sma, q) |
691 | * @sma: semaphore array | |
692 | * @q: the operation that just completed | |
693 | * | |
694 | * update_queue is O(N^2) when it restarts scanning the whole queue of | |
695 | * waiting operations. Therefore this function checks if the restart is | |
696 | * really necessary. It is called after a previously waiting operation | |
1a82e9e1 MS |
697 | * modified the array. |
698 | * Note that wait-for-zero operations are handled without restart. | |
fd5db422 MS |
699 | */ |
700 | static int check_restart(struct sem_array *sma, struct sem_queue *q) | |
701 | { | |
1a82e9e1 MS |
702 | /* pending complex alter operations are too difficult to analyse */ |
703 | if (!list_empty(&sma->pending_alter)) | |
fd5db422 MS |
704 | return 1; |
705 | ||
706 | /* we were a sleeping complex operation. Too difficult */ | |
707 | if (q->nsops > 1) | |
708 | return 1; | |
709 | ||
1a82e9e1 MS |
710 | /* It is impossible that someone waits for the new value: |
711 | * - complex operations always restart. | |
712 | * - wait-for-zero are handled seperately. | |
713 | * - q is a previously sleeping simple operation that | |
714 | * altered the array. It must be a decrement, because | |
715 | * simple increments never sleep. | |
716 | * - If there are older (higher priority) decrements | |
717 | * in the queue, then they have observed the original | |
718 | * semval value and couldn't proceed. The operation | |
719 | * decremented to value - thus they won't proceed either. | |
720 | */ | |
721 | return 0; | |
722 | } | |
fd5db422 | 723 | |
1a82e9e1 | 724 | /** |
8001c858 | 725 | * wake_const_ops - wake up non-alter tasks |
1a82e9e1 MS |
726 | * @sma: semaphore array. |
727 | * @semnum: semaphore that was modified. | |
9ae949fa | 728 | * @wake_q: lockless wake-queue head. |
1a82e9e1 MS |
729 | * |
730 | * wake_const_ops must be called after a semaphore in a semaphore array | |
731 | * was set to 0. If complex const operations are pending, wake_const_ops must | |
732 | * be called with semnum = -1, as well as with the number of each modified | |
733 | * semaphore. | |
9ae949fa | 734 | * The tasks that must be woken up are added to @wake_q. The return code |
1a82e9e1 MS |
735 | * is stored in q->pid. |
736 | * The function returns 1 if at least one operation was completed successfully. | |
737 | */ | |
738 | static int wake_const_ops(struct sem_array *sma, int semnum, | |
9ae949fa | 739 | struct wake_q_head *wake_q) |
1a82e9e1 MS |
740 | { |
741 | struct sem_queue *q; | |
742 | struct list_head *walk; | |
743 | struct list_head *pending_list; | |
744 | int semop_completed = 0; | |
745 | ||
746 | if (semnum == -1) | |
747 | pending_list = &sma->pending_const; | |
748 | else | |
749 | pending_list = &sma->sem_base[semnum].pending_const; | |
fd5db422 | 750 | |
1a82e9e1 MS |
751 | walk = pending_list->next; |
752 | while (walk != pending_list) { | |
753 | int error; | |
754 | ||
755 | q = container_of(walk, struct sem_queue, list); | |
756 | walk = walk->next; | |
757 | ||
d198cd6d | 758 | error = perform_atomic_semop(sma, q); |
1a82e9e1 MS |
759 | |
760 | if (error <= 0) { | |
761 | /* operation completed, remove from queue & wakeup */ | |
762 | ||
763 | unlink_queue(sma, q); | |
764 | ||
9ae949fa | 765 | wake_up_sem_queue_prepare(q, error, wake_q); |
1a82e9e1 MS |
766 | if (error == 0) |
767 | semop_completed = 1; | |
768 | } | |
769 | } | |
770 | return semop_completed; | |
771 | } | |
772 | ||
773 | /** | |
8001c858 | 774 | * do_smart_wakeup_zero - wakeup all wait for zero tasks |
1a82e9e1 MS |
775 | * @sma: semaphore array |
776 | * @sops: operations that were performed | |
777 | * @nsops: number of operations | |
9ae949fa | 778 | * @wake_q: lockless wake-queue head |
1a82e9e1 | 779 | * |
8001c858 DB |
780 | * Checks all required queue for wait-for-zero operations, based |
781 | * on the actual changes that were performed on the semaphore array. | |
1a82e9e1 MS |
782 | * The function returns 1 if at least one operation was completed successfully. |
783 | */ | |
784 | static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, | |
9ae949fa | 785 | int nsops, struct wake_q_head *wake_q) |
1a82e9e1 MS |
786 | { |
787 | int i; | |
788 | int semop_completed = 0; | |
789 | int got_zero = 0; | |
790 | ||
791 | /* first: the per-semaphore queues, if known */ | |
792 | if (sops) { | |
793 | for (i = 0; i < nsops; i++) { | |
794 | int num = sops[i].sem_num; | |
795 | ||
796 | if (sma->sem_base[num].semval == 0) { | |
797 | got_zero = 1; | |
9ae949fa | 798 | semop_completed |= wake_const_ops(sma, num, wake_q); |
1a82e9e1 MS |
799 | } |
800 | } | |
801 | } else { | |
802 | /* | |
803 | * No sops means modified semaphores not known. | |
804 | * Assume all were changed. | |
fd5db422 | 805 | */ |
1a82e9e1 MS |
806 | for (i = 0; i < sma->sem_nsems; i++) { |
807 | if (sma->sem_base[i].semval == 0) { | |
808 | got_zero = 1; | |
9ae949fa | 809 | semop_completed |= wake_const_ops(sma, i, wake_q); |
1a82e9e1 MS |
810 | } |
811 | } | |
fd5db422 MS |
812 | } |
813 | /* | |
1a82e9e1 MS |
814 | * If one of the modified semaphores got 0, |
815 | * then check the global queue, too. | |
fd5db422 | 816 | */ |
1a82e9e1 | 817 | if (got_zero) |
9ae949fa | 818 | semop_completed |= wake_const_ops(sma, -1, wake_q); |
fd5db422 | 819 | |
1a82e9e1 | 820 | return semop_completed; |
fd5db422 MS |
821 | } |
822 | ||
636c6be8 MS |
823 | |
824 | /** | |
8001c858 | 825 | * update_queue - look for tasks that can be completed. |
636c6be8 MS |
826 | * @sma: semaphore array. |
827 | * @semnum: semaphore that was modified. | |
9ae949fa | 828 | * @wake_q: lockless wake-queue head. |
636c6be8 MS |
829 | * |
830 | * update_queue must be called after a semaphore in a semaphore array | |
9f1bc2c9 RR |
831 | * was modified. If multiple semaphores were modified, update_queue must |
832 | * be called with semnum = -1, as well as with the number of each modified | |
833 | * semaphore. | |
9ae949fa | 834 | * The tasks that must be woken up are added to @wake_q. The return code |
0a2b9d4c | 835 | * is stored in q->pid. |
1a82e9e1 MS |
836 | * The function internally checks if const operations can now succeed. |
837 | * | |
0a2b9d4c | 838 | * The function return 1 if at least one semop was completed successfully. |
1da177e4 | 839 | */ |
9ae949fa | 840 | static int update_queue(struct sem_array *sma, int semnum, struct wake_q_head *wake_q) |
1da177e4 | 841 | { |
636c6be8 MS |
842 | struct sem_queue *q; |
843 | struct list_head *walk; | |
844 | struct list_head *pending_list; | |
0a2b9d4c | 845 | int semop_completed = 0; |
636c6be8 | 846 | |
9f1bc2c9 | 847 | if (semnum == -1) |
1a82e9e1 | 848 | pending_list = &sma->pending_alter; |
9f1bc2c9 | 849 | else |
1a82e9e1 | 850 | pending_list = &sma->sem_base[semnum].pending_alter; |
9cad200c NP |
851 | |
852 | again: | |
636c6be8 MS |
853 | walk = pending_list->next; |
854 | while (walk != pending_list) { | |
fd5db422 | 855 | int error, restart; |
636c6be8 | 856 | |
9f1bc2c9 | 857 | q = container_of(walk, struct sem_queue, list); |
636c6be8 | 858 | walk = walk->next; |
1da177e4 | 859 | |
d987f8b2 MS |
860 | /* If we are scanning the single sop, per-semaphore list of |
861 | * one semaphore and that semaphore is 0, then it is not | |
1a82e9e1 | 862 | * necessary to scan further: simple increments |
d987f8b2 MS |
863 | * that affect only one entry succeed immediately and cannot |
864 | * be in the per semaphore pending queue, and decrements | |
865 | * cannot be successful if the value is already 0. | |
866 | */ | |
1a82e9e1 | 867 | if (semnum != -1 && sma->sem_base[semnum].semval == 0) |
d987f8b2 MS |
868 | break; |
869 | ||
d198cd6d | 870 | error = perform_atomic_semop(sma, q); |
1da177e4 LT |
871 | |
872 | /* Does q->sleeper still need to sleep? */ | |
9cad200c NP |
873 | if (error > 0) |
874 | continue; | |
875 | ||
b97e820f | 876 | unlink_queue(sma, q); |
9cad200c | 877 | |
0a2b9d4c | 878 | if (error) { |
fd5db422 | 879 | restart = 0; |
0a2b9d4c MS |
880 | } else { |
881 | semop_completed = 1; | |
9ae949fa | 882 | do_smart_wakeup_zero(sma, q->sops, q->nsops, wake_q); |
fd5db422 | 883 | restart = check_restart(sma, q); |
0a2b9d4c | 884 | } |
fd5db422 | 885 | |
9ae949fa | 886 | wake_up_sem_queue_prepare(q, error, wake_q); |
fd5db422 | 887 | if (restart) |
9cad200c | 888 | goto again; |
1da177e4 | 889 | } |
0a2b9d4c | 890 | return semop_completed; |
1da177e4 LT |
891 | } |
892 | ||
0e8c6656 | 893 | /** |
8001c858 | 894 | * set_semotime - set sem_otime |
0e8c6656 MS |
895 | * @sma: semaphore array |
896 | * @sops: operations that modified the array, may be NULL | |
897 | * | |
898 | * sem_otime is replicated to avoid cache line trashing. | |
899 | * This function sets one instance to the current time. | |
900 | */ | |
901 | static void set_semotime(struct sem_array *sma, struct sembuf *sops) | |
902 | { | |
903 | if (sops == NULL) { | |
904 | sma->sem_base[0].sem_otime = get_seconds(); | |
905 | } else { | |
906 | sma->sem_base[sops[0].sem_num].sem_otime = | |
907 | get_seconds(); | |
908 | } | |
909 | } | |
910 | ||
0a2b9d4c | 911 | /** |
8001c858 | 912 | * do_smart_update - optimized update_queue |
fd5db422 MS |
913 | * @sma: semaphore array |
914 | * @sops: operations that were performed | |
915 | * @nsops: number of operations | |
0a2b9d4c | 916 | * @otime: force setting otime |
9ae949fa | 917 | * @wake_q: lockless wake-queue head |
fd5db422 | 918 | * |
1a82e9e1 MS |
919 | * do_smart_update() does the required calls to update_queue and wakeup_zero, |
920 | * based on the actual changes that were performed on the semaphore array. | |
0a2b9d4c | 921 | * Note that the function does not do the actual wake-up: the caller is |
9ae949fa | 922 | * responsible for calling wake_up_q(). |
0a2b9d4c | 923 | * It is safe to perform this call after dropping all locks. |
fd5db422 | 924 | */ |
0a2b9d4c | 925 | static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops, |
9ae949fa | 926 | int otime, struct wake_q_head *wake_q) |
fd5db422 MS |
927 | { |
928 | int i; | |
929 | ||
9ae949fa | 930 | otime |= do_smart_wakeup_zero(sma, sops, nsops, wake_q); |
1a82e9e1 | 931 | |
f269f40a MS |
932 | if (!list_empty(&sma->pending_alter)) { |
933 | /* semaphore array uses the global queue - just process it. */ | |
9ae949fa | 934 | otime |= update_queue(sma, -1, wake_q); |
f269f40a MS |
935 | } else { |
936 | if (!sops) { | |
937 | /* | |
938 | * No sops, thus the modified semaphores are not | |
939 | * known. Check all. | |
940 | */ | |
941 | for (i = 0; i < sma->sem_nsems; i++) | |
9ae949fa | 942 | otime |= update_queue(sma, i, wake_q); |
f269f40a MS |
943 | } else { |
944 | /* | |
945 | * Check the semaphores that were increased: | |
946 | * - No complex ops, thus all sleeping ops are | |
947 | * decrease. | |
948 | * - if we decreased the value, then any sleeping | |
949 | * semaphore ops wont be able to run: If the | |
950 | * previous value was too small, then the new | |
951 | * value will be too small, too. | |
952 | */ | |
953 | for (i = 0; i < nsops; i++) { | |
954 | if (sops[i].sem_op > 0) { | |
955 | otime |= update_queue(sma, | |
9ae949fa | 956 | sops[i].sem_num, wake_q); |
f269f40a | 957 | } |
ab465df9 | 958 | } |
9f1bc2c9 | 959 | } |
fd5db422 | 960 | } |
0e8c6656 MS |
961 | if (otime) |
962 | set_semotime(sma, sops); | |
fd5db422 MS |
963 | } |
964 | ||
2f2ed41d | 965 | /* |
b220c57a | 966 | * check_qop: Test if a queued operation sleeps on the semaphore semnum |
2f2ed41d MS |
967 | */ |
968 | static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q, | |
969 | bool count_zero) | |
970 | { | |
b220c57a | 971 | struct sembuf *sop = q->blocking; |
2f2ed41d | 972 | |
9b44ee2e MS |
973 | /* |
974 | * Linux always (since 0.99.10) reported a task as sleeping on all | |
975 | * semaphores. This violates SUS, therefore it was changed to the | |
976 | * standard compliant behavior. | |
977 | * Give the administrators a chance to notice that an application | |
978 | * might misbehave because it relies on the Linux behavior. | |
979 | */ | |
980 | pr_info_once("semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant.\n" | |
981 | "The task %s (%d) triggered the difference, watch for misbehavior.\n", | |
982 | current->comm, task_pid_nr(current)); | |
983 | ||
b220c57a MS |
984 | if (sop->sem_num != semnum) |
985 | return 0; | |
2f2ed41d | 986 | |
b220c57a MS |
987 | if (count_zero && sop->sem_op == 0) |
988 | return 1; | |
989 | if (!count_zero && sop->sem_op < 0) | |
990 | return 1; | |
991 | ||
992 | return 0; | |
2f2ed41d MS |
993 | } |
994 | ||
1da177e4 LT |
995 | /* The following counts are associated to each semaphore: |
996 | * semncnt number of tasks waiting on semval being nonzero | |
997 | * semzcnt number of tasks waiting on semval being zero | |
b220c57a MS |
998 | * |
999 | * Per definition, a task waits only on the semaphore of the first semop | |
1000 | * that cannot proceed, even if additional operation would block, too. | |
1da177e4 | 1001 | */ |
2f2ed41d MS |
1002 | static int count_semcnt(struct sem_array *sma, ushort semnum, |
1003 | bool count_zero) | |
1da177e4 | 1004 | { |
2f2ed41d | 1005 | struct list_head *l; |
239521f3 | 1006 | struct sem_queue *q; |
2f2ed41d | 1007 | int semcnt; |
1da177e4 | 1008 | |
2f2ed41d MS |
1009 | semcnt = 0; |
1010 | /* First: check the simple operations. They are easy to evaluate */ | |
1011 | if (count_zero) | |
1012 | l = &sma->sem_base[semnum].pending_const; | |
1013 | else | |
1014 | l = &sma->sem_base[semnum].pending_alter; | |
1da177e4 | 1015 | |
2f2ed41d MS |
1016 | list_for_each_entry(q, l, list) { |
1017 | /* all task on a per-semaphore list sleep on exactly | |
1018 | * that semaphore | |
1019 | */ | |
1020 | semcnt++; | |
ebc2e5e6 RR |
1021 | } |
1022 | ||
2f2ed41d | 1023 | /* Then: check the complex operations. */ |
1994862d | 1024 | list_for_each_entry(q, &sma->pending_alter, list) { |
2f2ed41d MS |
1025 | semcnt += check_qop(sma, semnum, q, count_zero); |
1026 | } | |
1027 | if (count_zero) { | |
1028 | list_for_each_entry(q, &sma->pending_const, list) { | |
1029 | semcnt += check_qop(sma, semnum, q, count_zero); | |
1030 | } | |
1994862d | 1031 | } |
2f2ed41d | 1032 | return semcnt; |
1da177e4 LT |
1033 | } |
1034 | ||
d9a605e4 DB |
1035 | /* Free a semaphore set. freeary() is called with sem_ids.rwsem locked |
1036 | * as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem | |
3e148c79 | 1037 | * remains locked on exit. |
1da177e4 | 1038 | */ |
01b8b07a | 1039 | static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
1da177e4 | 1040 | { |
380af1b3 MS |
1041 | struct sem_undo *un, *tu; |
1042 | struct sem_queue *q, *tq; | |
01b8b07a | 1043 | struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
9f1bc2c9 | 1044 | int i; |
9ae949fa | 1045 | DEFINE_WAKE_Q(wake_q); |
1da177e4 | 1046 | |
380af1b3 | 1047 | /* Free the existing undo structures for this semaphore set. */ |
cf9d5d78 | 1048 | ipc_assert_locked_object(&sma->sem_perm); |
380af1b3 MS |
1049 | list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { |
1050 | list_del(&un->list_id); | |
1051 | spin_lock(&un->ulp->lock); | |
1da177e4 | 1052 | un->semid = -1; |
380af1b3 MS |
1053 | list_del_rcu(&un->list_proc); |
1054 | spin_unlock(&un->ulp->lock); | |
693a8b6e | 1055 | kfree_rcu(un, rcu); |
380af1b3 | 1056 | } |
1da177e4 LT |
1057 | |
1058 | /* Wake up all pending processes and let them fail with EIDRM. */ | |
1a82e9e1 MS |
1059 | list_for_each_entry_safe(q, tq, &sma->pending_const, list) { |
1060 | unlink_queue(sma, q); | |
9ae949fa | 1061 | wake_up_sem_queue_prepare(q, -EIDRM, &wake_q); |
1a82e9e1 MS |
1062 | } |
1063 | ||
1064 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { | |
b97e820f | 1065 | unlink_queue(sma, q); |
9ae949fa | 1066 | wake_up_sem_queue_prepare(q, -EIDRM, &wake_q); |
1da177e4 | 1067 | } |
9f1bc2c9 RR |
1068 | for (i = 0; i < sma->sem_nsems; i++) { |
1069 | struct sem *sem = sma->sem_base + i; | |
1a82e9e1 MS |
1070 | list_for_each_entry_safe(q, tq, &sem->pending_const, list) { |
1071 | unlink_queue(sma, q); | |
9ae949fa | 1072 | wake_up_sem_queue_prepare(q, -EIDRM, &wake_q); |
1a82e9e1 MS |
1073 | } |
1074 | list_for_each_entry_safe(q, tq, &sem->pending_alter, list) { | |
9f1bc2c9 | 1075 | unlink_queue(sma, q); |
9ae949fa | 1076 | wake_up_sem_queue_prepare(q, -EIDRM, &wake_q); |
9f1bc2c9 RR |
1077 | } |
1078 | } | |
1da177e4 | 1079 | |
7ca7e564 ND |
1080 | /* Remove the semaphore set from the IDR */ |
1081 | sem_rmid(ns, sma); | |
6062a8dc | 1082 | sem_unlock(sma, -1); |
6d49dab8 | 1083 | rcu_read_unlock(); |
1da177e4 | 1084 | |
9ae949fa | 1085 | wake_up_q(&wake_q); |
e3893534 | 1086 | ns->used_sems -= sma->sem_nsems; |
53dad6d3 | 1087 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1088 | } |
1089 | ||
1090 | static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) | |
1091 | { | |
239521f3 | 1092 | switch (version) { |
1da177e4 LT |
1093 | case IPC_64: |
1094 | return copy_to_user(buf, in, sizeof(*in)); | |
1095 | case IPC_OLD: | |
1096 | { | |
1097 | struct semid_ds out; | |
1098 | ||
982f7c2b DR |
1099 | memset(&out, 0, sizeof(out)); |
1100 | ||
1da177e4 LT |
1101 | ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm); |
1102 | ||
1103 | out.sem_otime = in->sem_otime; | |
1104 | out.sem_ctime = in->sem_ctime; | |
1105 | out.sem_nsems = in->sem_nsems; | |
1106 | ||
1107 | return copy_to_user(buf, &out, sizeof(out)); | |
1108 | } | |
1109 | default: | |
1110 | return -EINVAL; | |
1111 | } | |
1112 | } | |
1113 | ||
d12e1e50 MS |
1114 | static time_t get_semotime(struct sem_array *sma) |
1115 | { | |
1116 | int i; | |
1117 | time_t res; | |
1118 | ||
1119 | res = sma->sem_base[0].sem_otime; | |
1120 | for (i = 1; i < sma->sem_nsems; i++) { | |
1121 | time_t to = sma->sem_base[i].sem_otime; | |
1122 | ||
1123 | if (to > res) | |
1124 | res = to; | |
1125 | } | |
1126 | return res; | |
1127 | } | |
1128 | ||
4b9fcb0e | 1129 | static int semctl_nolock(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1130 | int cmd, int version, void __user *p) |
1da177e4 | 1131 | { |
e5cc9c7b | 1132 | int err; |
1da177e4 LT |
1133 | struct sem_array *sma; |
1134 | ||
239521f3 | 1135 | switch (cmd) { |
1da177e4 LT |
1136 | case IPC_INFO: |
1137 | case SEM_INFO: | |
1138 | { | |
1139 | struct seminfo seminfo; | |
1140 | int max_id; | |
1141 | ||
1142 | err = security_sem_semctl(NULL, cmd); | |
1143 | if (err) | |
1144 | return err; | |
46c0a8ca | 1145 | |
239521f3 | 1146 | memset(&seminfo, 0, sizeof(seminfo)); |
e3893534 KK |
1147 | seminfo.semmni = ns->sc_semmni; |
1148 | seminfo.semmns = ns->sc_semmns; | |
1149 | seminfo.semmsl = ns->sc_semmsl; | |
1150 | seminfo.semopm = ns->sc_semopm; | |
1da177e4 LT |
1151 | seminfo.semvmx = SEMVMX; |
1152 | seminfo.semmnu = SEMMNU; | |
1153 | seminfo.semmap = SEMMAP; | |
1154 | seminfo.semume = SEMUME; | |
d9a605e4 | 1155 | down_read(&sem_ids(ns).rwsem); |
1da177e4 | 1156 | if (cmd == SEM_INFO) { |
e3893534 KK |
1157 | seminfo.semusz = sem_ids(ns).in_use; |
1158 | seminfo.semaem = ns->used_sems; | |
1da177e4 LT |
1159 | } else { |
1160 | seminfo.semusz = SEMUSZ; | |
1161 | seminfo.semaem = SEMAEM; | |
1162 | } | |
7ca7e564 | 1163 | max_id = ipc_get_maxid(&sem_ids(ns)); |
d9a605e4 | 1164 | up_read(&sem_ids(ns).rwsem); |
46c0a8ca | 1165 | if (copy_to_user(p, &seminfo, sizeof(struct seminfo))) |
1da177e4 | 1166 | return -EFAULT; |
239521f3 | 1167 | return (max_id < 0) ? 0 : max_id; |
1da177e4 | 1168 | } |
4b9fcb0e | 1169 | case IPC_STAT: |
1da177e4 LT |
1170 | case SEM_STAT: |
1171 | { | |
1172 | struct semid64_ds tbuf; | |
16df3674 DB |
1173 | int id = 0; |
1174 | ||
1175 | memset(&tbuf, 0, sizeof(tbuf)); | |
1da177e4 | 1176 | |
941b0304 | 1177 | rcu_read_lock(); |
4b9fcb0e | 1178 | if (cmd == SEM_STAT) { |
16df3674 DB |
1179 | sma = sem_obtain_object(ns, semid); |
1180 | if (IS_ERR(sma)) { | |
1181 | err = PTR_ERR(sma); | |
1182 | goto out_unlock; | |
1183 | } | |
4b9fcb0e PP |
1184 | id = sma->sem_perm.id; |
1185 | } else { | |
16df3674 DB |
1186 | sma = sem_obtain_object_check(ns, semid); |
1187 | if (IS_ERR(sma)) { | |
1188 | err = PTR_ERR(sma); | |
1189 | goto out_unlock; | |
1190 | } | |
4b9fcb0e | 1191 | } |
1da177e4 LT |
1192 | |
1193 | err = -EACCES; | |
b0e77598 | 1194 | if (ipcperms(ns, &sma->sem_perm, S_IRUGO)) |
1da177e4 LT |
1195 | goto out_unlock; |
1196 | ||
1197 | err = security_sem_semctl(sma, cmd); | |
1198 | if (err) | |
1199 | goto out_unlock; | |
1200 | ||
1da177e4 | 1201 | kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); |
d12e1e50 MS |
1202 | tbuf.sem_otime = get_semotime(sma); |
1203 | tbuf.sem_ctime = sma->sem_ctime; | |
1204 | tbuf.sem_nsems = sma->sem_nsems; | |
16df3674 | 1205 | rcu_read_unlock(); |
e1fd1f49 | 1206 | if (copy_semid_to_user(p, &tbuf, version)) |
1da177e4 LT |
1207 | return -EFAULT; |
1208 | return id; | |
1209 | } | |
1210 | default: | |
1211 | return -EINVAL; | |
1212 | } | |
1da177e4 | 1213 | out_unlock: |
16df3674 | 1214 | rcu_read_unlock(); |
1da177e4 LT |
1215 | return err; |
1216 | } | |
1217 | ||
e1fd1f49 AV |
1218 | static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, |
1219 | unsigned long arg) | |
1220 | { | |
1221 | struct sem_undo *un; | |
1222 | struct sem_array *sma; | |
239521f3 | 1223 | struct sem *curr; |
9ae949fa DB |
1224 | int err, val; |
1225 | DEFINE_WAKE_Q(wake_q); | |
1226 | ||
e1fd1f49 AV |
1227 | #if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN) |
1228 | /* big-endian 64bit */ | |
1229 | val = arg >> 32; | |
1230 | #else | |
1231 | /* 32bit or little-endian 64bit */ | |
1232 | val = arg; | |
1233 | #endif | |
1234 | ||
6062a8dc RR |
1235 | if (val > SEMVMX || val < 0) |
1236 | return -ERANGE; | |
e1fd1f49 | 1237 | |
6062a8dc RR |
1238 | rcu_read_lock(); |
1239 | sma = sem_obtain_object_check(ns, semid); | |
1240 | if (IS_ERR(sma)) { | |
1241 | rcu_read_unlock(); | |
1242 | return PTR_ERR(sma); | |
1243 | } | |
1244 | ||
1245 | if (semnum < 0 || semnum >= sma->sem_nsems) { | |
1246 | rcu_read_unlock(); | |
1247 | return -EINVAL; | |
1248 | } | |
1249 | ||
1250 | ||
1251 | if (ipcperms(ns, &sma->sem_perm, S_IWUGO)) { | |
1252 | rcu_read_unlock(); | |
1253 | return -EACCES; | |
1254 | } | |
e1fd1f49 AV |
1255 | |
1256 | err = security_sem_semctl(sma, SETVAL); | |
6062a8dc RR |
1257 | if (err) { |
1258 | rcu_read_unlock(); | |
1259 | return -EACCES; | |
1260 | } | |
e1fd1f49 | 1261 | |
6062a8dc | 1262 | sem_lock(sma, NULL, -1); |
e1fd1f49 | 1263 | |
0f3d2b01 | 1264 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1265 | sem_unlock(sma, -1); |
1266 | rcu_read_unlock(); | |
1267 | return -EIDRM; | |
1268 | } | |
1269 | ||
e1fd1f49 AV |
1270 | curr = &sma->sem_base[semnum]; |
1271 | ||
cf9d5d78 | 1272 | ipc_assert_locked_object(&sma->sem_perm); |
e1fd1f49 AV |
1273 | list_for_each_entry(un, &sma->list_id, list_id) |
1274 | un->semadj[semnum] = 0; | |
1275 | ||
1276 | curr->semval = val; | |
1277 | curr->sempid = task_tgid_vnr(current); | |
1278 | sma->sem_ctime = get_seconds(); | |
1279 | /* maybe some queued-up processes were waiting for this */ | |
9ae949fa | 1280 | do_smart_update(sma, NULL, 0, 0, &wake_q); |
6062a8dc | 1281 | sem_unlock(sma, -1); |
6d49dab8 | 1282 | rcu_read_unlock(); |
9ae949fa | 1283 | wake_up_q(&wake_q); |
6062a8dc | 1284 | return 0; |
e1fd1f49 AV |
1285 | } |
1286 | ||
e3893534 | 1287 | static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, |
e1fd1f49 | 1288 | int cmd, void __user *p) |
1da177e4 LT |
1289 | { |
1290 | struct sem_array *sma; | |
239521f3 | 1291 | struct sem *curr; |
16df3674 | 1292 | int err, nsems; |
1da177e4 | 1293 | ushort fast_sem_io[SEMMSL_FAST]; |
239521f3 | 1294 | ushort *sem_io = fast_sem_io; |
9ae949fa | 1295 | DEFINE_WAKE_Q(wake_q); |
16df3674 DB |
1296 | |
1297 | rcu_read_lock(); | |
1298 | sma = sem_obtain_object_check(ns, semid); | |
1299 | if (IS_ERR(sma)) { | |
1300 | rcu_read_unlock(); | |
023a5355 | 1301 | return PTR_ERR(sma); |
16df3674 | 1302 | } |
1da177e4 LT |
1303 | |
1304 | nsems = sma->sem_nsems; | |
1305 | ||
1da177e4 | 1306 | err = -EACCES; |
c728b9c8 LT |
1307 | if (ipcperms(ns, &sma->sem_perm, cmd == SETALL ? S_IWUGO : S_IRUGO)) |
1308 | goto out_rcu_wakeup; | |
1da177e4 LT |
1309 | |
1310 | err = security_sem_semctl(sma, cmd); | |
c728b9c8 LT |
1311 | if (err) |
1312 | goto out_rcu_wakeup; | |
1da177e4 LT |
1313 | |
1314 | err = -EACCES; | |
1315 | switch (cmd) { | |
1316 | case GETALL: | |
1317 | { | |
e1fd1f49 | 1318 | ushort __user *array = p; |
1da177e4 LT |
1319 | int i; |
1320 | ||
ce857229 | 1321 | sem_lock(sma, NULL, -1); |
0f3d2b01 | 1322 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1323 | err = -EIDRM; |
1324 | goto out_unlock; | |
1325 | } | |
239521f3 | 1326 | if (nsems > SEMMSL_FAST) { |
ce857229 | 1327 | if (!ipc_rcu_getref(sma)) { |
ce857229 | 1328 | err = -EIDRM; |
6e224f94 | 1329 | goto out_unlock; |
ce857229 AV |
1330 | } |
1331 | sem_unlock(sma, -1); | |
6d49dab8 | 1332 | rcu_read_unlock(); |
1da177e4 | 1333 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
239521f3 | 1334 | if (sem_io == NULL) { |
9b24fef9 | 1335 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1336 | return -ENOMEM; |
1337 | } | |
1338 | ||
4091fd94 | 1339 | rcu_read_lock(); |
6ff37972 | 1340 | sem_lock_and_putref(sma); |
0f3d2b01 | 1341 | if (!ipc_valid_object(&sma->sem_perm)) { |
1da177e4 | 1342 | err = -EIDRM; |
6e224f94 | 1343 | goto out_unlock; |
1da177e4 | 1344 | } |
ce857229 | 1345 | } |
1da177e4 LT |
1346 | for (i = 0; i < sma->sem_nsems; i++) |
1347 | sem_io[i] = sma->sem_base[i].semval; | |
6062a8dc | 1348 | sem_unlock(sma, -1); |
6d49dab8 | 1349 | rcu_read_unlock(); |
1da177e4 | 1350 | err = 0; |
239521f3 | 1351 | if (copy_to_user(array, sem_io, nsems*sizeof(ushort))) |
1da177e4 LT |
1352 | err = -EFAULT; |
1353 | goto out_free; | |
1354 | } | |
1355 | case SETALL: | |
1356 | { | |
1357 | int i; | |
1358 | struct sem_undo *un; | |
1359 | ||
6062a8dc | 1360 | if (!ipc_rcu_getref(sma)) { |
6e224f94 MS |
1361 | err = -EIDRM; |
1362 | goto out_rcu_wakeup; | |
6062a8dc | 1363 | } |
16df3674 | 1364 | rcu_read_unlock(); |
1da177e4 | 1365 | |
239521f3 | 1366 | if (nsems > SEMMSL_FAST) { |
1da177e4 | 1367 | sem_io = ipc_alloc(sizeof(ushort)*nsems); |
239521f3 | 1368 | if (sem_io == NULL) { |
9b24fef9 | 1369 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1370 | return -ENOMEM; |
1371 | } | |
1372 | } | |
1373 | ||
239521f3 | 1374 | if (copy_from_user(sem_io, p, nsems*sizeof(ushort))) { |
9b24fef9 | 1375 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1376 | err = -EFAULT; |
1377 | goto out_free; | |
1378 | } | |
1379 | ||
1380 | for (i = 0; i < nsems; i++) { | |
1381 | if (sem_io[i] > SEMVMX) { | |
9b24fef9 | 1382 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1383 | err = -ERANGE; |
1384 | goto out_free; | |
1385 | } | |
1386 | } | |
4091fd94 | 1387 | rcu_read_lock(); |
6ff37972 | 1388 | sem_lock_and_putref(sma); |
0f3d2b01 | 1389 | if (!ipc_valid_object(&sma->sem_perm)) { |
1da177e4 | 1390 | err = -EIDRM; |
6e224f94 | 1391 | goto out_unlock; |
1da177e4 LT |
1392 | } |
1393 | ||
a5f4db87 | 1394 | for (i = 0; i < nsems; i++) { |
1da177e4 | 1395 | sma->sem_base[i].semval = sem_io[i]; |
a5f4db87 DB |
1396 | sma->sem_base[i].sempid = task_tgid_vnr(current); |
1397 | } | |
4daa28f6 | 1398 | |
cf9d5d78 | 1399 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1400 | list_for_each_entry(un, &sma->list_id, list_id) { |
1da177e4 LT |
1401 | for (i = 0; i < nsems; i++) |
1402 | un->semadj[i] = 0; | |
4daa28f6 | 1403 | } |
1da177e4 LT |
1404 | sma->sem_ctime = get_seconds(); |
1405 | /* maybe some queued-up processes were waiting for this */ | |
9ae949fa | 1406 | do_smart_update(sma, NULL, 0, 0, &wake_q); |
1da177e4 LT |
1407 | err = 0; |
1408 | goto out_unlock; | |
1409 | } | |
e1fd1f49 | 1410 | /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */ |
1da177e4 LT |
1411 | } |
1412 | err = -EINVAL; | |
c728b9c8 LT |
1413 | if (semnum < 0 || semnum >= nsems) |
1414 | goto out_rcu_wakeup; | |
1da177e4 | 1415 | |
6062a8dc | 1416 | sem_lock(sma, NULL, -1); |
0f3d2b01 | 1417 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
1418 | err = -EIDRM; |
1419 | goto out_unlock; | |
1420 | } | |
1da177e4 LT |
1421 | curr = &sma->sem_base[semnum]; |
1422 | ||
1423 | switch (cmd) { | |
1424 | case GETVAL: | |
1425 | err = curr->semval; | |
1426 | goto out_unlock; | |
1427 | case GETPID: | |
1428 | err = curr->sempid; | |
1429 | goto out_unlock; | |
1430 | case GETNCNT: | |
2f2ed41d | 1431 | err = count_semcnt(sma, semnum, 0); |
1da177e4 LT |
1432 | goto out_unlock; |
1433 | case GETZCNT: | |
2f2ed41d | 1434 | err = count_semcnt(sma, semnum, 1); |
1da177e4 | 1435 | goto out_unlock; |
1da177e4 | 1436 | } |
16df3674 | 1437 | |
1da177e4 | 1438 | out_unlock: |
6062a8dc | 1439 | sem_unlock(sma, -1); |
c728b9c8 | 1440 | out_rcu_wakeup: |
6d49dab8 | 1441 | rcu_read_unlock(); |
9ae949fa | 1442 | wake_up_q(&wake_q); |
1da177e4 | 1443 | out_free: |
239521f3 | 1444 | if (sem_io != fast_sem_io) |
1d5cfdb0 | 1445 | ipc_free(sem_io); |
1da177e4 LT |
1446 | return err; |
1447 | } | |
1448 | ||
016d7132 PP |
1449 | static inline unsigned long |
1450 | copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) | |
1da177e4 | 1451 | { |
239521f3 | 1452 | switch (version) { |
1da177e4 | 1453 | case IPC_64: |
016d7132 | 1454 | if (copy_from_user(out, buf, sizeof(*out))) |
1da177e4 | 1455 | return -EFAULT; |
1da177e4 | 1456 | return 0; |
1da177e4 LT |
1457 | case IPC_OLD: |
1458 | { | |
1459 | struct semid_ds tbuf_old; | |
1460 | ||
239521f3 | 1461 | if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
1da177e4 LT |
1462 | return -EFAULT; |
1463 | ||
016d7132 PP |
1464 | out->sem_perm.uid = tbuf_old.sem_perm.uid; |
1465 | out->sem_perm.gid = tbuf_old.sem_perm.gid; | |
1466 | out->sem_perm.mode = tbuf_old.sem_perm.mode; | |
1da177e4 LT |
1467 | |
1468 | return 0; | |
1469 | } | |
1470 | default: | |
1471 | return -EINVAL; | |
1472 | } | |
1473 | } | |
1474 | ||
522bb2a2 | 1475 | /* |
d9a605e4 | 1476 | * This function handles some semctl commands which require the rwsem |
522bb2a2 | 1477 | * to be held in write mode. |
d9a605e4 | 1478 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
522bb2a2 | 1479 | */ |
21a4826a | 1480 | static int semctl_down(struct ipc_namespace *ns, int semid, |
e1fd1f49 | 1481 | int cmd, int version, void __user *p) |
1da177e4 LT |
1482 | { |
1483 | struct sem_array *sma; | |
1484 | int err; | |
016d7132 | 1485 | struct semid64_ds semid64; |
1da177e4 LT |
1486 | struct kern_ipc_perm *ipcp; |
1487 | ||
239521f3 | 1488 | if (cmd == IPC_SET) { |
e1fd1f49 | 1489 | if (copy_semid_from_user(&semid64, p, version)) |
1da177e4 | 1490 | return -EFAULT; |
1da177e4 | 1491 | } |
073115d6 | 1492 | |
d9a605e4 | 1493 | down_write(&sem_ids(ns).rwsem); |
7b4cc5d8 DB |
1494 | rcu_read_lock(); |
1495 | ||
16df3674 DB |
1496 | ipcp = ipcctl_pre_down_nolock(ns, &sem_ids(ns), semid, cmd, |
1497 | &semid64.sem_perm, 0); | |
7b4cc5d8 DB |
1498 | if (IS_ERR(ipcp)) { |
1499 | err = PTR_ERR(ipcp); | |
7b4cc5d8 DB |
1500 | goto out_unlock1; |
1501 | } | |
073115d6 | 1502 | |
a5f75e7f | 1503 | sma = container_of(ipcp, struct sem_array, sem_perm); |
1da177e4 LT |
1504 | |
1505 | err = security_sem_semctl(sma, cmd); | |
7b4cc5d8 DB |
1506 | if (err) |
1507 | goto out_unlock1; | |
1da177e4 | 1508 | |
7b4cc5d8 | 1509 | switch (cmd) { |
1da177e4 | 1510 | case IPC_RMID: |
6062a8dc | 1511 | sem_lock(sma, NULL, -1); |
7b4cc5d8 | 1512 | /* freeary unlocks the ipc object and rcu */ |
01b8b07a | 1513 | freeary(ns, ipcp); |
522bb2a2 | 1514 | goto out_up; |
1da177e4 | 1515 | case IPC_SET: |
6062a8dc | 1516 | sem_lock(sma, NULL, -1); |
1efdb69b EB |
1517 | err = ipc_update_perm(&semid64.sem_perm, ipcp); |
1518 | if (err) | |
7b4cc5d8 | 1519 | goto out_unlock0; |
1da177e4 | 1520 | sma->sem_ctime = get_seconds(); |
1da177e4 LT |
1521 | break; |
1522 | default: | |
1da177e4 | 1523 | err = -EINVAL; |
7b4cc5d8 | 1524 | goto out_unlock1; |
1da177e4 | 1525 | } |
1da177e4 | 1526 | |
7b4cc5d8 | 1527 | out_unlock0: |
6062a8dc | 1528 | sem_unlock(sma, -1); |
7b4cc5d8 | 1529 | out_unlock1: |
6d49dab8 | 1530 | rcu_read_unlock(); |
522bb2a2 | 1531 | out_up: |
d9a605e4 | 1532 | up_write(&sem_ids(ns).rwsem); |
1da177e4 LT |
1533 | return err; |
1534 | } | |
1535 | ||
e1fd1f49 | 1536 | SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) |
1da177e4 | 1537 | { |
1da177e4 | 1538 | int version; |
e3893534 | 1539 | struct ipc_namespace *ns; |
e1fd1f49 | 1540 | void __user *p = (void __user *)arg; |
1da177e4 LT |
1541 | |
1542 | if (semid < 0) | |
1543 | return -EINVAL; | |
1544 | ||
1545 | version = ipc_parse_version(&cmd); | |
e3893534 | 1546 | ns = current->nsproxy->ipc_ns; |
1da177e4 | 1547 | |
239521f3 | 1548 | switch (cmd) { |
1da177e4 LT |
1549 | case IPC_INFO: |
1550 | case SEM_INFO: | |
4b9fcb0e | 1551 | case IPC_STAT: |
1da177e4 | 1552 | case SEM_STAT: |
e1fd1f49 | 1553 | return semctl_nolock(ns, semid, cmd, version, p); |
1da177e4 LT |
1554 | case GETALL: |
1555 | case GETVAL: | |
1556 | case GETPID: | |
1557 | case GETNCNT: | |
1558 | case GETZCNT: | |
1da177e4 | 1559 | case SETALL: |
e1fd1f49 AV |
1560 | return semctl_main(ns, semid, semnum, cmd, p); |
1561 | case SETVAL: | |
1562 | return semctl_setval(ns, semid, semnum, arg); | |
1da177e4 LT |
1563 | case IPC_RMID: |
1564 | case IPC_SET: | |
e1fd1f49 | 1565 | return semctl_down(ns, semid, cmd, version, p); |
1da177e4 LT |
1566 | default: |
1567 | return -EINVAL; | |
1568 | } | |
1569 | } | |
1570 | ||
1da177e4 LT |
1571 | /* If the task doesn't already have a undo_list, then allocate one |
1572 | * here. We guarantee there is only one thread using this undo list, | |
1573 | * and current is THE ONE | |
1574 | * | |
1575 | * If this allocation and assignment succeeds, but later | |
1576 | * portions of this code fail, there is no need to free the sem_undo_list. | |
1577 | * Just let it stay associated with the task, and it'll be freed later | |
1578 | * at exit time. | |
1579 | * | |
1580 | * This can block, so callers must hold no locks. | |
1581 | */ | |
1582 | static inline int get_undo_list(struct sem_undo_list **undo_listp) | |
1583 | { | |
1584 | struct sem_undo_list *undo_list; | |
1da177e4 LT |
1585 | |
1586 | undo_list = current->sysvsem.undo_list; | |
1587 | if (!undo_list) { | |
2453a306 | 1588 | undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL); |
1da177e4 LT |
1589 | if (undo_list == NULL) |
1590 | return -ENOMEM; | |
00a5dfdb | 1591 | spin_lock_init(&undo_list->lock); |
1da177e4 | 1592 | atomic_set(&undo_list->refcnt, 1); |
4daa28f6 MS |
1593 | INIT_LIST_HEAD(&undo_list->list_proc); |
1594 | ||
1da177e4 LT |
1595 | current->sysvsem.undo_list = undo_list; |
1596 | } | |
1597 | *undo_listp = undo_list; | |
1598 | return 0; | |
1599 | } | |
1600 | ||
bf17bb71 | 1601 | static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid) |
1da177e4 | 1602 | { |
bf17bb71 | 1603 | struct sem_undo *un; |
4daa28f6 | 1604 | |
bf17bb71 NP |
1605 | list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) { |
1606 | if (un->semid == semid) | |
1607 | return un; | |
1da177e4 | 1608 | } |
4daa28f6 | 1609 | return NULL; |
1da177e4 LT |
1610 | } |
1611 | ||
bf17bb71 NP |
1612 | static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) |
1613 | { | |
1614 | struct sem_undo *un; | |
1615 | ||
239521f3 | 1616 | assert_spin_locked(&ulp->lock); |
bf17bb71 NP |
1617 | |
1618 | un = __lookup_undo(ulp, semid); | |
1619 | if (un) { | |
1620 | list_del_rcu(&un->list_proc); | |
1621 | list_add_rcu(&un->list_proc, &ulp->list_proc); | |
1622 | } | |
1623 | return un; | |
1624 | } | |
1625 | ||
4daa28f6 | 1626 | /** |
8001c858 | 1627 | * find_alloc_undo - lookup (and if not present create) undo array |
4daa28f6 MS |
1628 | * @ns: namespace |
1629 | * @semid: semaphore array id | |
1630 | * | |
1631 | * The function looks up (and if not present creates) the undo structure. | |
1632 | * The size of the undo structure depends on the size of the semaphore | |
1633 | * array, thus the alloc path is not that straightforward. | |
380af1b3 MS |
1634 | * Lifetime-rules: sem_undo is rcu-protected, on success, the function |
1635 | * performs a rcu_read_lock(). | |
4daa28f6 MS |
1636 | */ |
1637 | static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) | |
1da177e4 LT |
1638 | { |
1639 | struct sem_array *sma; | |
1640 | struct sem_undo_list *ulp; | |
1641 | struct sem_undo *un, *new; | |
6062a8dc | 1642 | int nsems, error; |
1da177e4 LT |
1643 | |
1644 | error = get_undo_list(&ulp); | |
1645 | if (error) | |
1646 | return ERR_PTR(error); | |
1647 | ||
380af1b3 | 1648 | rcu_read_lock(); |
c530c6ac | 1649 | spin_lock(&ulp->lock); |
1da177e4 | 1650 | un = lookup_undo(ulp, semid); |
c530c6ac | 1651 | spin_unlock(&ulp->lock); |
239521f3 | 1652 | if (likely(un != NULL)) |
1da177e4 LT |
1653 | goto out; |
1654 | ||
1655 | /* no undo structure around - allocate one. */ | |
4daa28f6 | 1656 | /* step 1: figure out the size of the semaphore array */ |
16df3674 DB |
1657 | sma = sem_obtain_object_check(ns, semid); |
1658 | if (IS_ERR(sma)) { | |
1659 | rcu_read_unlock(); | |
4de85cd6 | 1660 | return ERR_CAST(sma); |
16df3674 | 1661 | } |
023a5355 | 1662 | |
1da177e4 | 1663 | nsems = sma->sem_nsems; |
6062a8dc RR |
1664 | if (!ipc_rcu_getref(sma)) { |
1665 | rcu_read_unlock(); | |
1666 | un = ERR_PTR(-EIDRM); | |
1667 | goto out; | |
1668 | } | |
16df3674 | 1669 | rcu_read_unlock(); |
1da177e4 | 1670 | |
4daa28f6 | 1671 | /* step 2: allocate new undo structure */ |
4668edc3 | 1672 | new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); |
1da177e4 | 1673 | if (!new) { |
9b24fef9 | 1674 | ipc_rcu_putref(sma, sem_rcu_free); |
1da177e4 LT |
1675 | return ERR_PTR(-ENOMEM); |
1676 | } | |
1da177e4 | 1677 | |
380af1b3 | 1678 | /* step 3: Acquire the lock on semaphore array */ |
4091fd94 | 1679 | rcu_read_lock(); |
6ff37972 | 1680 | sem_lock_and_putref(sma); |
0f3d2b01 | 1681 | if (!ipc_valid_object(&sma->sem_perm)) { |
6062a8dc | 1682 | sem_unlock(sma, -1); |
6d49dab8 | 1683 | rcu_read_unlock(); |
1da177e4 LT |
1684 | kfree(new); |
1685 | un = ERR_PTR(-EIDRM); | |
1686 | goto out; | |
1687 | } | |
380af1b3 MS |
1688 | spin_lock(&ulp->lock); |
1689 | ||
1690 | /* | |
1691 | * step 4: check for races: did someone else allocate the undo struct? | |
1692 | */ | |
1693 | un = lookup_undo(ulp, semid); | |
1694 | if (un) { | |
1695 | kfree(new); | |
1696 | goto success; | |
1697 | } | |
4daa28f6 MS |
1698 | /* step 5: initialize & link new undo structure */ |
1699 | new->semadj = (short *) &new[1]; | |
380af1b3 | 1700 | new->ulp = ulp; |
4daa28f6 MS |
1701 | new->semid = semid; |
1702 | assert_spin_locked(&ulp->lock); | |
380af1b3 | 1703 | list_add_rcu(&new->list_proc, &ulp->list_proc); |
cf9d5d78 | 1704 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 | 1705 | list_add(&new->list_id, &sma->list_id); |
380af1b3 | 1706 | un = new; |
4daa28f6 | 1707 | |
380af1b3 | 1708 | success: |
c530c6ac | 1709 | spin_unlock(&ulp->lock); |
6062a8dc | 1710 | sem_unlock(sma, -1); |
1da177e4 LT |
1711 | out: |
1712 | return un; | |
1713 | } | |
1714 | ||
d5460c99 HC |
1715 | SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, |
1716 | unsigned, nsops, const struct timespec __user *, timeout) | |
1da177e4 LT |
1717 | { |
1718 | int error = -EINVAL; | |
1719 | struct sem_array *sma; | |
1720 | struct sembuf fast_sops[SEMOPM_FAST]; | |
239521f3 | 1721 | struct sembuf *sops = fast_sops, *sop; |
1da177e4 | 1722 | struct sem_undo *un; |
6062a8dc | 1723 | int undos = 0, alter = 0, max, locknum; |
1da177e4 LT |
1724 | struct sem_queue queue; |
1725 | unsigned long jiffies_left = 0; | |
e3893534 KK |
1726 | struct ipc_namespace *ns; |
1727 | ||
1728 | ns = current->nsproxy->ipc_ns; | |
1da177e4 LT |
1729 | |
1730 | if (nsops < 1 || semid < 0) | |
1731 | return -EINVAL; | |
e3893534 | 1732 | if (nsops > ns->sc_semopm) |
1da177e4 | 1733 | return -E2BIG; |
239521f3 MS |
1734 | if (nsops > SEMOPM_FAST) { |
1735 | sops = kmalloc(sizeof(*sops)*nsops, GFP_KERNEL); | |
1736 | if (sops == NULL) | |
1da177e4 LT |
1737 | return -ENOMEM; |
1738 | } | |
239521f3 MS |
1739 | if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) { |
1740 | error = -EFAULT; | |
1da177e4 LT |
1741 | goto out_free; |
1742 | } | |
1743 | if (timeout) { | |
1744 | struct timespec _timeout; | |
1745 | if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { | |
1746 | error = -EFAULT; | |
1747 | goto out_free; | |
1748 | } | |
1749 | if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || | |
1750 | _timeout.tv_nsec >= 1000000000L) { | |
1751 | error = -EINVAL; | |
1752 | goto out_free; | |
1753 | } | |
1754 | jiffies_left = timespec_to_jiffies(&_timeout); | |
1755 | } | |
1756 | max = 0; | |
1757 | for (sop = sops; sop < sops + nsops; sop++) { | |
1758 | if (sop->sem_num >= max) | |
1759 | max = sop->sem_num; | |
1760 | if (sop->sem_flg & SEM_UNDO) | |
b78755ab MS |
1761 | undos = 1; |
1762 | if (sop->sem_op != 0) | |
1da177e4 LT |
1763 | alter = 1; |
1764 | } | |
1da177e4 | 1765 | |
6062a8dc | 1766 | |
1da177e4 | 1767 | if (undos) { |
6062a8dc | 1768 | /* On success, find_alloc_undo takes the rcu_read_lock */ |
4daa28f6 | 1769 | un = find_alloc_undo(ns, semid); |
1da177e4 LT |
1770 | if (IS_ERR(un)) { |
1771 | error = PTR_ERR(un); | |
1772 | goto out_free; | |
1773 | } | |
6062a8dc | 1774 | } else { |
1da177e4 | 1775 | un = NULL; |
6062a8dc RR |
1776 | rcu_read_lock(); |
1777 | } | |
1da177e4 | 1778 | |
16df3674 | 1779 | sma = sem_obtain_object_check(ns, semid); |
023a5355 | 1780 | if (IS_ERR(sma)) { |
6062a8dc | 1781 | rcu_read_unlock(); |
023a5355 | 1782 | error = PTR_ERR(sma); |
1da177e4 | 1783 | goto out_free; |
023a5355 ND |
1784 | } |
1785 | ||
16df3674 | 1786 | error = -EFBIG; |
248e7357 DB |
1787 | if (max >= sma->sem_nsems) { |
1788 | rcu_read_unlock(); | |
1789 | goto out_free; | |
1790 | } | |
16df3674 DB |
1791 | |
1792 | error = -EACCES; | |
248e7357 DB |
1793 | if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) { |
1794 | rcu_read_unlock(); | |
1795 | goto out_free; | |
1796 | } | |
16df3674 DB |
1797 | |
1798 | error = security_sem_semop(sma, sops, nsops, alter); | |
248e7357 DB |
1799 | if (error) { |
1800 | rcu_read_unlock(); | |
1801 | goto out_free; | |
1802 | } | |
16df3674 | 1803 | |
6e224f94 MS |
1804 | error = -EIDRM; |
1805 | locknum = sem_lock(sma, sops, nsops); | |
0f3d2b01 RA |
1806 | /* |
1807 | * We eventually might perform the following check in a lockless | |
1808 | * fashion, considering ipc_valid_object() locking constraints. | |
1809 | * If nsops == 1 and there is no contention for sem_perm.lock, then | |
1810 | * only a per-semaphore lock is held and it's OK to proceed with the | |
1811 | * check below. More details on the fine grained locking scheme | |
1812 | * entangled here and why it's RMID race safe on comments at sem_lock() | |
1813 | */ | |
1814 | if (!ipc_valid_object(&sma->sem_perm)) | |
6e224f94 | 1815 | goto out_unlock_free; |
1da177e4 | 1816 | /* |
4daa28f6 | 1817 | * semid identifiers are not unique - find_alloc_undo may have |
1da177e4 | 1818 | * allocated an undo structure, it was invalidated by an RMID |
4daa28f6 | 1819 | * and now a new array with received the same id. Check and fail. |
25985edc | 1820 | * This case can be detected checking un->semid. The existence of |
380af1b3 | 1821 | * "un" itself is guaranteed by rcu. |
1da177e4 | 1822 | */ |
6062a8dc RR |
1823 | if (un && un->semid == -1) |
1824 | goto out_unlock_free; | |
4daa28f6 | 1825 | |
d198cd6d MS |
1826 | queue.sops = sops; |
1827 | queue.nsops = nsops; | |
1828 | queue.undo = un; | |
1829 | queue.pid = task_tgid_vnr(current); | |
1830 | queue.alter = alter; | |
1831 | ||
1832 | error = perform_atomic_semop(sma, &queue); | |
9ae949fa DB |
1833 | if (error == 0) { /* non-blocking succesfull path */ |
1834 | DEFINE_WAKE_Q(wake_q); | |
1835 | ||
1836 | /* | |
1837 | * If the operation was successful, then do | |
0e8c6656 MS |
1838 | * the required updates. |
1839 | */ | |
1840 | if (alter) | |
9ae949fa | 1841 | do_smart_update(sma, sops, nsops, 1, &wake_q); |
0e8c6656 MS |
1842 | else |
1843 | set_semotime(sma, sops); | |
9ae949fa DB |
1844 | |
1845 | sem_unlock(sma, locknum); | |
1846 | rcu_read_unlock(); | |
1847 | wake_up_q(&wake_q); | |
1848 | ||
1849 | goto out_free; | |
1da177e4 | 1850 | } |
9ae949fa | 1851 | if (error < 0) /* non-blocking error path */ |
0e8c6656 | 1852 | goto out_unlock_free; |
1da177e4 | 1853 | |
9ae949fa DB |
1854 | /* |
1855 | * We need to sleep on this operation, so we put the current | |
1da177e4 LT |
1856 | * task into the pending queue and go to sleep. |
1857 | */ | |
b97e820f MS |
1858 | if (nsops == 1) { |
1859 | struct sem *curr; | |
1860 | curr = &sma->sem_base[sops->sem_num]; | |
1861 | ||
f269f40a MS |
1862 | if (alter) { |
1863 | if (sma->complex_count) { | |
1864 | list_add_tail(&queue.list, | |
1865 | &sma->pending_alter); | |
1866 | } else { | |
1867 | ||
1868 | list_add_tail(&queue.list, | |
1869 | &curr->pending_alter); | |
1870 | } | |
1871 | } else { | |
1a82e9e1 | 1872 | list_add_tail(&queue.list, &curr->pending_const); |
f269f40a | 1873 | } |
b97e820f | 1874 | } else { |
f269f40a MS |
1875 | if (!sma->complex_count) |
1876 | merge_queues(sma); | |
1877 | ||
9f1bc2c9 | 1878 | if (alter) |
1a82e9e1 | 1879 | list_add_tail(&queue.list, &sma->pending_alter); |
9f1bc2c9 | 1880 | else |
1a82e9e1 MS |
1881 | list_add_tail(&queue.list, &sma->pending_const); |
1882 | ||
b97e820f MS |
1883 | sma->complex_count++; |
1884 | } | |
1885 | ||
9ae949fa | 1886 | sleep_again: |
1da177e4 LT |
1887 | queue.status = -EINTR; |
1888 | queue.sleeper = current; | |
0b0577f6 | 1889 | |
52644c9a | 1890 | __set_current_state(TASK_INTERRUPTIBLE); |
6062a8dc | 1891 | sem_unlock(sma, locknum); |
6d49dab8 | 1892 | rcu_read_unlock(); |
1da177e4 LT |
1893 | |
1894 | if (timeout) | |
1895 | jiffies_left = schedule_timeout(jiffies_left); | |
1896 | else | |
1897 | schedule(); | |
1898 | ||
9ae949fa DB |
1899 | /* |
1900 | * fastpath: the semop has completed, either successfully or not, from | |
1901 | * the syscall pov, is quite irrelevant to us at this point; we're done. | |
1902 | * | |
1903 | * We _do_ care, nonetheless, about being awoken by a signal or | |
1904 | * spuriously. The queue.status is checked again in the slowpath (aka | |
1905 | * after taking sem_lock), such that we can detect scenarios where we | |
1906 | * were awakened externally, during the window between wake_q_add() and | |
1907 | * wake_up_q(). | |
1908 | */ | |
1909 | error = READ_ONCE(queue.status); | |
1da177e4 | 1910 | if (error != -EINTR) { |
9ae949fa DB |
1911 | /* |
1912 | * User space could assume that semop() is a memory barrier: | |
1913 | * Without the mb(), the cpu could speculatively read in user | |
1914 | * space stale data that was overwritten by the previous owner | |
1915 | * of the semaphore. | |
c61284e9 MS |
1916 | */ |
1917 | smp_mb(); | |
1da177e4 LT |
1918 | goto out_free; |
1919 | } | |
1920 | ||
321310ce | 1921 | rcu_read_lock(); |
6062a8dc | 1922 | sma = sem_obtain_lock(ns, semid, sops, nsops, &locknum); |
9ae949fa | 1923 | error = READ_ONCE(queue.status); |
d694ad62 MS |
1924 | |
1925 | /* | |
1926 | * Array removed? If yes, leave without sem_unlock(). | |
1927 | */ | |
023a5355 | 1928 | if (IS_ERR(sma)) { |
321310ce | 1929 | rcu_read_unlock(); |
1da177e4 LT |
1930 | goto out_free; |
1931 | } | |
1932 | ||
1933 | /* | |
d694ad62 MS |
1934 | * If queue.status != -EINTR we are woken up by another process. |
1935 | * Leave without unlink_queue(), but with sem_unlock(). | |
1da177e4 | 1936 | */ |
3ab08fe2 | 1937 | if (error != -EINTR) |
1da177e4 | 1938 | goto out_unlock_free; |
1da177e4 LT |
1939 | |
1940 | /* | |
9ae949fa | 1941 | * If an interrupt occurred we have to clean up the queue. |
1da177e4 LT |
1942 | */ |
1943 | if (timeout && jiffies_left == 0) | |
1944 | error = -EAGAIN; | |
0b0577f6 MS |
1945 | |
1946 | /* | |
9ae949fa | 1947 | * If the wakeup was spurious, just retry. |
0b0577f6 MS |
1948 | */ |
1949 | if (error == -EINTR && !signal_pending(current)) | |
1950 | goto sleep_again; | |
1951 | ||
b97e820f | 1952 | unlink_queue(sma, &queue); |
1da177e4 LT |
1953 | |
1954 | out_unlock_free: | |
6062a8dc | 1955 | sem_unlock(sma, locknum); |
6d49dab8 | 1956 | rcu_read_unlock(); |
1da177e4 | 1957 | out_free: |
239521f3 | 1958 | if (sops != fast_sops) |
1da177e4 LT |
1959 | kfree(sops); |
1960 | return error; | |
1961 | } | |
1962 | ||
d5460c99 HC |
1963 | SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops, |
1964 | unsigned, nsops) | |
1da177e4 LT |
1965 | { |
1966 | return sys_semtimedop(semid, tsops, nsops, NULL); | |
1967 | } | |
1968 | ||
1969 | /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between | |
1970 | * parent and child tasks. | |
1da177e4 LT |
1971 | */ |
1972 | ||
1973 | int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) | |
1974 | { | |
1975 | struct sem_undo_list *undo_list; | |
1976 | int error; | |
1977 | ||
1978 | if (clone_flags & CLONE_SYSVSEM) { | |
1979 | error = get_undo_list(&undo_list); | |
1980 | if (error) | |
1981 | return error; | |
1da177e4 LT |
1982 | atomic_inc(&undo_list->refcnt); |
1983 | tsk->sysvsem.undo_list = undo_list; | |
46c0a8ca | 1984 | } else |
1da177e4 LT |
1985 | tsk->sysvsem.undo_list = NULL; |
1986 | ||
1987 | return 0; | |
1988 | } | |
1989 | ||
1990 | /* | |
1991 | * add semadj values to semaphores, free undo structures. | |
1992 | * undo structures are not freed when semaphore arrays are destroyed | |
1993 | * so some of them may be out of date. | |
1994 | * IMPLEMENTATION NOTE: There is some confusion over whether the | |
1995 | * set of adjustments that needs to be done should be done in an atomic | |
1996 | * manner or not. That is, if we are attempting to decrement the semval | |
1997 | * should we queue up and wait until we can do so legally? | |
1998 | * The original implementation attempted to do this (queue and wait). | |
1999 | * The current implementation does not do so. The POSIX standard | |
2000 | * and SVID should be consulted to determine what behavior is mandated. | |
2001 | */ | |
2002 | void exit_sem(struct task_struct *tsk) | |
2003 | { | |
4daa28f6 | 2004 | struct sem_undo_list *ulp; |
1da177e4 | 2005 | |
4daa28f6 MS |
2006 | ulp = tsk->sysvsem.undo_list; |
2007 | if (!ulp) | |
1da177e4 | 2008 | return; |
9edff4ab | 2009 | tsk->sysvsem.undo_list = NULL; |
1da177e4 | 2010 | |
4daa28f6 | 2011 | if (!atomic_dec_and_test(&ulp->refcnt)) |
1da177e4 LT |
2012 | return; |
2013 | ||
380af1b3 | 2014 | for (;;) { |
1da177e4 | 2015 | struct sem_array *sma; |
380af1b3 | 2016 | struct sem_undo *un; |
6062a8dc | 2017 | int semid, i; |
9ae949fa | 2018 | DEFINE_WAKE_Q(wake_q); |
4daa28f6 | 2019 | |
2a1613a5 NB |
2020 | cond_resched(); |
2021 | ||
380af1b3 | 2022 | rcu_read_lock(); |
05725f7e JP |
2023 | un = list_entry_rcu(ulp->list_proc.next, |
2024 | struct sem_undo, list_proc); | |
602b8593 HK |
2025 | if (&un->list_proc == &ulp->list_proc) { |
2026 | /* | |
2027 | * We must wait for freeary() before freeing this ulp, | |
2028 | * in case we raced with last sem_undo. There is a small | |
2029 | * possibility where we exit while freeary() didn't | |
2030 | * finish unlocking sem_undo_list. | |
2031 | */ | |
2032 | spin_unlock_wait(&ulp->lock); | |
2033 | rcu_read_unlock(); | |
2034 | break; | |
2035 | } | |
2036 | spin_lock(&ulp->lock); | |
2037 | semid = un->semid; | |
2038 | spin_unlock(&ulp->lock); | |
4daa28f6 | 2039 | |
602b8593 | 2040 | /* exit_sem raced with IPC_RMID, nothing to do */ |
6062a8dc RR |
2041 | if (semid == -1) { |
2042 | rcu_read_unlock(); | |
602b8593 | 2043 | continue; |
6062a8dc | 2044 | } |
1da177e4 | 2045 | |
602b8593 | 2046 | sma = sem_obtain_object_check(tsk->nsproxy->ipc_ns, semid); |
380af1b3 | 2047 | /* exit_sem raced with IPC_RMID, nothing to do */ |
6062a8dc RR |
2048 | if (IS_ERR(sma)) { |
2049 | rcu_read_unlock(); | |
380af1b3 | 2050 | continue; |
6062a8dc | 2051 | } |
1da177e4 | 2052 | |
6062a8dc | 2053 | sem_lock(sma, NULL, -1); |
6e224f94 | 2054 | /* exit_sem raced with IPC_RMID, nothing to do */ |
0f3d2b01 | 2055 | if (!ipc_valid_object(&sma->sem_perm)) { |
6e224f94 MS |
2056 | sem_unlock(sma, -1); |
2057 | rcu_read_unlock(); | |
2058 | continue; | |
2059 | } | |
bf17bb71 | 2060 | un = __lookup_undo(ulp, semid); |
380af1b3 MS |
2061 | if (un == NULL) { |
2062 | /* exit_sem raced with IPC_RMID+semget() that created | |
2063 | * exactly the same semid. Nothing to do. | |
2064 | */ | |
6062a8dc | 2065 | sem_unlock(sma, -1); |
6d49dab8 | 2066 | rcu_read_unlock(); |
380af1b3 MS |
2067 | continue; |
2068 | } | |
2069 | ||
2070 | /* remove un from the linked lists */ | |
cf9d5d78 | 2071 | ipc_assert_locked_object(&sma->sem_perm); |
4daa28f6 MS |
2072 | list_del(&un->list_id); |
2073 | ||
a9795584 HK |
2074 | /* we are the last process using this ulp, acquiring ulp->lock |
2075 | * isn't required. Besides that, we are also protected against | |
2076 | * IPC_RMID as we hold sma->sem_perm lock now | |
2077 | */ | |
380af1b3 | 2078 | list_del_rcu(&un->list_proc); |
380af1b3 | 2079 | |
4daa28f6 MS |
2080 | /* perform adjustments registered in un */ |
2081 | for (i = 0; i < sma->sem_nsems; i++) { | |
239521f3 | 2082 | struct sem *semaphore = &sma->sem_base[i]; |
4daa28f6 MS |
2083 | if (un->semadj[i]) { |
2084 | semaphore->semval += un->semadj[i]; | |
1da177e4 LT |
2085 | /* |
2086 | * Range checks of the new semaphore value, | |
2087 | * not defined by sus: | |
2088 | * - Some unices ignore the undo entirely | |
2089 | * (e.g. HP UX 11i 11.22, Tru64 V5.1) | |
2090 | * - some cap the value (e.g. FreeBSD caps | |
2091 | * at 0, but doesn't enforce SEMVMX) | |
2092 | * | |
2093 | * Linux caps the semaphore value, both at 0 | |
2094 | * and at SEMVMX. | |
2095 | * | |
239521f3 | 2096 | * Manfred <manfred@colorfullife.com> |
1da177e4 | 2097 | */ |
5f921ae9 IM |
2098 | if (semaphore->semval < 0) |
2099 | semaphore->semval = 0; | |
2100 | if (semaphore->semval > SEMVMX) | |
2101 | semaphore->semval = SEMVMX; | |
b488893a | 2102 | semaphore->sempid = task_tgid_vnr(current); |
1da177e4 LT |
2103 | } |
2104 | } | |
1da177e4 | 2105 | /* maybe some queued-up processes were waiting for this */ |
9ae949fa | 2106 | do_smart_update(sma, NULL, 0, 1, &wake_q); |
6062a8dc | 2107 | sem_unlock(sma, -1); |
6d49dab8 | 2108 | rcu_read_unlock(); |
9ae949fa | 2109 | wake_up_q(&wake_q); |
380af1b3 | 2110 | |
693a8b6e | 2111 | kfree_rcu(un, rcu); |
1da177e4 | 2112 | } |
4daa28f6 | 2113 | kfree(ulp); |
1da177e4 LT |
2114 | } |
2115 | ||
2116 | #ifdef CONFIG_PROC_FS | |
19b4946c | 2117 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it) |
1da177e4 | 2118 | { |
1efdb69b | 2119 | struct user_namespace *user_ns = seq_user_ns(s); |
19b4946c | 2120 | struct sem_array *sma = it; |
d12e1e50 MS |
2121 | time_t sem_otime; |
2122 | ||
d8c63376 MS |
2123 | /* |
2124 | * The proc interface isn't aware of sem_lock(), it calls | |
2125 | * ipc_lock_object() directly (in sysvipc_find_ipc). | |
5864a2fd MS |
2126 | * In order to stay compatible with sem_lock(), we must |
2127 | * enter / leave complex_mode. | |
d8c63376 | 2128 | */ |
5864a2fd | 2129 | complexmode_enter(sma); |
d8c63376 | 2130 | |
d12e1e50 | 2131 | sem_otime = get_semotime(sma); |
19b4946c | 2132 | |
7f032d6e JP |
2133 | seq_printf(s, |
2134 | "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n", | |
2135 | sma->sem_perm.key, | |
2136 | sma->sem_perm.id, | |
2137 | sma->sem_perm.mode, | |
2138 | sma->sem_nsems, | |
2139 | from_kuid_munged(user_ns, sma->sem_perm.uid), | |
2140 | from_kgid_munged(user_ns, sma->sem_perm.gid), | |
2141 | from_kuid_munged(user_ns, sma->sem_perm.cuid), | |
2142 | from_kgid_munged(user_ns, sma->sem_perm.cgid), | |
2143 | sem_otime, | |
2144 | sma->sem_ctime); | |
2145 | ||
5864a2fd MS |
2146 | complexmode_tryleave(sma); |
2147 | ||
7f032d6e | 2148 | return 0; |
1da177e4 LT |
2149 | } |
2150 | #endif |