1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/ipc/sem.c |
4 | * Copyright (C) 1992 Krishna Balasubramanian |
5 | * Copyright (C) 1995 Eric Schenk, Bruno Haible |
6 | * |
7 | * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
8 | * |
9 | * SMP-threaded, sysctl's added |
10 | * (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
11 | * Enforced range limit on SEM_UNDO |
12 | * (c) 2001 Red Hat Inc |
13 | * Lockless wakeup |
14 | * (c) 2003 Manfred Spraul <manfred@colorfullife.com> |
15 | * (c) 2016 Davidlohr Bueso <dave@stgolabs.net> |
16 | * Further wakeup optimizations, documentation |
17 | * (c) 2010 Manfred Spraul <manfred@colorfullife.com> |
18 | * |
19 | * support for audit of ipc object properties and permission changes |
20 | * Dustin Kirkland <dustin.kirkland@us.ibm.com> |
21 | * |
22 | * namespaces support |
23 | * OpenVZ, SWsoft Inc. |
24 | * Pavel Emelianov <xemul@openvz.org> |
25 | * |
26 | * Implementation notes: (May 2010) |
27 | * This file implements System V semaphores. |
28 | * |
29 | * User space visible behavior: |
30 | * - FIFO ordering for semop() operations (just FIFO, not starvation |
31 | * protection) |
32 | * - multiple semaphore operations that alter the same semaphore in |
33 | * one semop() are handled. |
34 | * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and |
35 | * SETALL calls. |
36 | * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO. |
37 | * - undo adjustments at process exit are limited to 0..SEMVMX. |
38 | * - namespace are supported. |
39 | * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtime by writing |
40 | * to /proc/sys/kernel/sem. |
41 | * - statistics about the usage are reported in /proc/sysvipc/sem. |
42 | * |
43 | * Internals: |
44 | * - scalability: |
45 | * - all global variables are read-mostly. |
46 | * - semop() calls and semctl(RMID) are synchronized by RCU. |
47 | * - most operations do write operations (actually: spin_lock calls) to |
48 | * the per-semaphore array structure. |
49 | * Thus: Perfect SMP scaling between independent semaphore arrays. |
50 | * If multiple semaphores in one array are used, then cache line |
51 | * trashing on the semaphore array spinlock will limit the scaling. |
52 | * - semncnt and semzcnt are calculated on demand in count_semcnt() |
53 | * - the task that performs a successful semop() scans the list of all |
54 | * sleeping tasks and completes any pending operations that can be fulfilled. |
55 | * Semaphores are actively given to waiting tasks (necessary for FIFO). |
56 | * (see update_queue()) |
57 | * - To improve the scalability, the actual wake-up calls are performed after |
58 | * dropping all locks. (see wake_up_sem_queue_prepare()) |
59 | * - All work is done by the waker, the woken up task does not have to do |
60 | * anything - not even acquiring a lock or dropping a refcount. |
61 | * - A woken up task may not even touch the semaphore array anymore, it may |
62 | * have been destroyed already by a semctl(RMID). |
63 | * - UNDO values are stored in an array (one per process and per |
64 | * semaphore array, lazily allocated). For backwards compatibility, multiple |
65 | * modes for the UNDO variables are supported (per process, per thread) |
66 | * (see copy_semundo, CLONE_SYSVSEM) |
67 | * - There are two lists of the pending operations: a per-array list |
68 | * and per-semaphore list (stored in the array). This allows to achieve FIFO |
69 | * ordering without always scanning all pending operations. |
70 | * The worst-case behavior is nevertheless O(N^2) for N wakeups. |
71 | */ |
72 | |
73 | #include <linux/compat.h> |
74 | #include <linux/slab.h> |
75 | #include <linux/spinlock.h> |
76 | #include <linux/init.h> |
77 | #include <linux/proc_fs.h> |
78 | #include <linux/time.h> |
79 | #include <linux/security.h> |
80 | #include <linux/syscalls.h> |
81 | #include <linux/audit.h> |
82 | #include <linux/capability.h> |
83 | #include <linux/seq_file.h> |
84 | #include <linux/rwsem.h> |
85 | #include <linux/nsproxy.h> |
86 | #include <linux/ipc_namespace.h> |
87 | #include <linux/sched/wake_q.h> |
88 | #include <linux/nospec.h> |
89 | #include <linux/rhashtable.h> |
90 | |
91 | #include <linux/uaccess.h> |
92 | #include "util.h" |
93 | |
94 | /* One semaphore structure for each semaphore in the system. */ |
95 | struct sem { |
96 | int semval; /* current value */ |
97 | /* |
98 | * PID of the process that last modified the semaphore. For |
99 | * Linux, specifically these are: |
100 | * - semop |
101 | * - semctl, via SETVAL and SETALL. |
102 | * - at task exit when performing undo adjustments (see exit_sem). |
103 | */ |
104 | struct pid *sempid; |
105 | spinlock_t lock; /* spinlock for fine-grained semtimedop */ |
106 | struct list_head pending_alter; /* pending single-sop operations */ |
107 | /* that alter the semaphore */ |
108 | struct list_head pending_const; /* pending single-sop operations */ |
109 | /* that do not alter the semaphore*/ |
110 | time64_t sem_otime; /* candidate for sem_otime */ |
111 | } ____cacheline_aligned_in_smp; |
112 | |
113 | /* One sem_array data structure for each set of semaphores in the system. */ |
114 | struct sem_array { |
115 | struct kern_ipc_perm sem_perm; /* permissions .. see ipc.h */ |
116 | time64_t sem_ctime; /* create/last semctl() time */ |
117 | struct list_head pending_alter; /* pending operations */ |
118 | /* that alter the array */ |
119 | struct list_head pending_const; /* pending complex operations */ |
120 | /* that do not alter semvals */ |
121 | struct list_head list_id; /* undo requests on this array */ |
122 | int sem_nsems; /* no. of semaphores in array */ |
123 | int complex_count; /* pending complex operations */ |
124 | unsigned int use_global_lock;/* >0: global lock required */ |
125 | |
126 | struct sem sems[]; |
127 | } __randomize_layout; |
128 | |
129 | /* One queue for each sleeping process in the system. */ |
130 | struct sem_queue { |
131 | struct list_head list; /* queue of pending operations */ |
132 | struct task_struct *sleeper; /* this process */ |
133 | struct sem_undo *undo; /* undo structure */ |
134 | struct pid *pid; /* process id of requesting process */ |
135 | int status; /* completion status of operation */ |
136 | struct sembuf *sops; /* array of pending operations */ |
137 | struct sembuf *blocking; /* the operation that blocked */ |
138 | int nsops; /* number of operations */ |
139 | bool alter; /* does *sops alter the array? */ |
140 | bool dupsop; /* sops on more than one sem_num */ |
141 | }; |
142 | |
143 | /* Each task has a list of undo requests. They are executed automatically |
144 | * when the process exits. |
145 | */ |
146 | struct sem_undo { |
147 | struct list_head list_proc; /* per-process list: * |
148 | * all undos from one process |
149 | * rcu protected */ |
150 | struct rcu_head rcu; /* rcu struct for sem_undo */ |
151 | struct sem_undo_list *ulp; /* back ptr to sem_undo_list */ |
152 | struct list_head list_id; /* per semaphore array list: |
153 | * all undos for one array */ |
154 | int semid; /* semaphore set identifier */ |
155 | short semadj[]; /* array of adjustments */ |
156 | /* one per semaphore */ |
157 | }; |
158 | |
159 | /* sem_undo_list controls shared access to the list of sem_undo structures |
160 | * that may be shared among all a CLONE_SYSVSEM task group. |
161 | */ |
162 | struct sem_undo_list { |
163 | refcount_t refcnt; |
164 | spinlock_t lock; |
165 | struct list_head list_proc; |
166 | }; |
167 | |
168 | |
169 | #define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS]) |
170 | |
171 | static int newary(struct ipc_namespace *, struct ipc_params *); |
172 | static void freeary(struct ipc_namespace *, struct kern_ipc_perm *); |
173 | #ifdef CONFIG_PROC_FS |
174 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it); |
175 | #endif |
176 | |
177 | #define SEMMSL_FAST 256 /* 512 bytes on stack */ |
178 | #define SEMOPM_FAST 64 /* ~ 372 bytes on stack */ |
179 | |
180 | /* |
181 | * Switching from the mode suitable for simple ops |
182 | * to the mode for complex ops is costly. Therefore: |
183 | * use some hysteresis |
184 | */ |
185 | #define USE_GLOBAL_LOCK_HYSTERESIS 10 |
186 | |
187 | /* |
188 | * Locking: |
189 | * a) global sem_lock() for read/write |
190 | * sem_undo.id_next, |
191 | * sem_array.complex_count, |
192 | * sem_array.pending{_alter,_const}, |
193 | * sem_array.sem_undo |
194 | * |
195 | * b) global or semaphore sem_lock() for read/write: |
196 | * sem_array.sems[i].pending_{const,alter}: |
197 | * |
198 | * c) special: |
199 | * sem_undo_list.list_proc: |
200 | * * undo_list->lock for write |
201 | * * rcu for read |
202 | * use_global_lock: |
203 | * * global sem_lock() for write |
204 | * * either local or global sem_lock() for read. |
205 | * |
206 | * Memory ordering: |
207 | * Most ordering is enforced by using spin_lock() and spin_unlock(). |
208 | * |
209 | * Exceptions: |
210 | * 1) use_global_lock: (SEM_BARRIER_1) |
211 | * Setting it from non-zero to 0 is a RELEASE, this is ensured by |
212 | * using smp_store_release(): Immediately after setting it to 0, |
213 | * a simple op can start. |
214 | * Testing if it is non-zero is an ACQUIRE, this is ensured by using |
215 | * smp_load_acquire(). |
216 | * Setting it from 0 to non-zero must be ordered with regards to |
217 | * this smp_load_acquire(), this is guaranteed because the smp_load_acquire() |
218 | * is inside a spin_lock() and after a write from 0 to non-zero a |
219 | * spin_lock()+spin_unlock() is done. |
220 | * To prevent the compiler/cpu temporarily writing 0 to use_global_lock, |
221 | * READ_ONCE()/WRITE_ONCE() is used. |
222 | * |
223 | * 2) queue.status: (SEM_BARRIER_2) |
224 | * Initialization is done while holding sem_lock(), so no further barrier is |
225 | * required. |
226 | * Setting it to a result code is a RELEASE, this is ensured by both a |
227 | * smp_store_release() (for case a) and while holding sem_lock() |
228 | * (for case b). |
229 | * The ACQUIRE when reading the result code without holding sem_lock() is |
230 | * achieved by using READ_ONCE() + smp_acquire__after_ctrl_dep(). |
231 | * (case a above). |
232 | * Reading the result code while holding sem_lock() needs no further barriers, |
233 | * the locks inside sem_lock() enforce ordering (case b above) |
234 | * |
235 | * 3) current->state: |
236 | * current->state is set to TASK_INTERRUPTIBLE while holding sem_lock(). |
237 | * The wakeup is handled using the wake_q infrastructure. wake_q wakeups may |
238 | * happen immediately after calling wake_q_add. As wake_q_add_safe() is called |
239 | * when holding sem_lock(), no further barriers are required. |
240 | * |
241 | * See also ipc/mqueue.c for more details on the covered races. |
242 | */ |
243 | |
244 | #define sc_semmsl sem_ctls[0] |
245 | #define sc_semmns sem_ctls[1] |
246 | #define sc_semopm sem_ctls[2] |
247 | #define sc_semmni sem_ctls[3] |
248 | |
249 | void sem_init_ns(struct ipc_namespace *ns) |
250 | { |
251 | ns->sc_semmsl = SEMMSL; |
252 | ns->sc_semmns = SEMMNS; |
253 | ns->sc_semopm = SEMOPM; |
254 | ns->sc_semmni = SEMMNI; |
255 | ns->used_sems = 0; |
256 | ipc_init_ids(ids: &ns->ids[IPC_SEM_IDS]); |
257 | } |
258 | |
259 | #ifdef CONFIG_IPC_NS |
260 | void sem_exit_ns(struct ipc_namespace *ns) |
261 | { |
262 | free_ipcs(ns, ids: &sem_ids(ns), free: freeary); |
263 | idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr); |
264 | rhashtable_destroy(ht: &ns->ids[IPC_SEM_IDS].key_ht); |
265 | } |
266 | #endif |
267 | |
268 | void __init sem_init(void) |
269 | { |
270 | sem_init_ns(ns: &init_ipc_ns); |
271 | ipc_init_proc_interface(path: "sysvipc/sem" , |
272 | header: " key semid perms nsems uid gid cuid cgid otime ctime\n" , |
273 | IPC_SEM_IDS, show: sysvipc_sem_proc_show); |
274 | } |
275 | |
276 | /** |
277 | * unmerge_queues - unmerge queues, if possible. |
278 | * @sma: semaphore array |
279 | * |
280 | * The function unmerges the wait queues if complex_count is 0. |
281 | * It must be called prior to dropping the global semaphore array lock. |
282 | */ |
283 | static void unmerge_queues(struct sem_array *sma) |
284 | { |
285 | struct sem_queue *q, *tq; |
286 | |
287 | /* complex operations still around? */ |
288 | if (sma->complex_count) |
289 | return; |
290 | /* |
291 | * We will switch back to simple mode. |
292 | * Move all pending operation back into the per-semaphore |
293 | * queues. |
294 | */ |
295 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { |
296 | struct sem *curr; |
297 | curr = &sma->sems[q->sops[0].sem_num]; |
298 | |
299 | list_add_tail(new: &q->list, head: &curr->pending_alter); |
300 | } |
301 | INIT_LIST_HEAD(list: &sma->pending_alter); |
302 | } |
303 | |
304 | /** |
305 | * merge_queues - merge single semop queues into global queue |
306 | * @sma: semaphore array |
307 | * |
308 | * This function merges all per-semaphore queues into the global queue. |
309 | * It is necessary to achieve FIFO ordering for the pending single-sop |
310 | * operations when a multi-semop operation must sleep. |
311 | * Only the alter operations must be moved, the const operations can stay. |
312 | */ |
313 | static void merge_queues(struct sem_array *sma) |
314 | { |
315 | int i; |
316 | for (i = 0; i < sma->sem_nsems; i++) { |
317 | struct sem *sem = &sma->sems[i]; |
318 | |
319 | list_splice_init(list: &sem->pending_alter, head: &sma->pending_alter); |
320 | } |
321 | } |
322 | |
323 | static void sem_rcu_free(struct rcu_head *head) |
324 | { |
325 | struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu); |
326 | struct sem_array *sma = container_of(p, struct sem_array, sem_perm); |
327 | |
328 | security_sem_free(sma: &sma->sem_perm); |
329 | kvfree(addr: sma); |
330 | } |
331 | |
332 | /* |
333 | * Enter the mode suitable for non-simple operations: |
334 | * Caller must own sem_perm.lock. |
335 | */ |
336 | static void complexmode_enter(struct sem_array *sma) |
337 | { |
338 | int i; |
339 | struct sem *sem; |
340 | |
341 | if (sma->use_global_lock > 0) { |
342 | /* |
343 | * We are already in global lock mode. |
344 | * Nothing to do, just reset the |
345 | * counter until we return to simple mode. |
346 | */ |
347 | WRITE_ONCE(sma->use_global_lock, USE_GLOBAL_LOCK_HYSTERESIS); |
348 | return; |
349 | } |
350 | WRITE_ONCE(sma->use_global_lock, USE_GLOBAL_LOCK_HYSTERESIS); |
351 | |
352 | for (i = 0; i < sma->sem_nsems; i++) { |
353 | sem = &sma->sems[i]; |
354 | spin_lock(lock: &sem->lock); |
355 | spin_unlock(lock: &sem->lock); |
356 | } |
357 | } |
358 | |
359 | /* |
360 | * Try to leave the mode that disallows simple operations: |
361 | * Caller must own sem_perm.lock. |
362 | */ |
363 | static void complexmode_tryleave(struct sem_array *sma) |
364 | { |
365 | if (sma->complex_count) { |
366 | /* Complex ops are sleeping. |
367 | * We must stay in complex mode |
368 | */ |
369 | return; |
370 | } |
371 | if (sma->use_global_lock == 1) { |
372 | |
373 | /* See SEM_BARRIER_1 for purpose/pairing */ |
374 | smp_store_release(&sma->use_global_lock, 0); |
375 | } else { |
376 | WRITE_ONCE(sma->use_global_lock, |
377 | sma->use_global_lock-1); |
378 | } |
379 | } |
380 | |
381 | #define SEM_GLOBAL_LOCK (-1) |
382 | /* |
383 | * If the request contains only one semaphore operation, and there are |
384 | * no complex transactions pending, lock only the semaphore involved. |
385 | * Otherwise, lock the entire semaphore array, since we either have |
386 | * multiple semaphores in our own semops, or we need to look at |
387 | * semaphores from other pending complex operations. |
388 | */ |
389 | static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, |
390 | int nsops) |
391 | { |
392 | struct sem *sem; |
393 | int idx; |
394 | |
395 | if (nsops != 1) { |
396 | /* Complex operation - acquire a full lock */ |
397 | ipc_lock_object(perm: &sma->sem_perm); |
398 | |
399 | /* Prevent parallel simple ops */ |
400 | complexmode_enter(sma); |
401 | return SEM_GLOBAL_LOCK; |
402 | } |
403 | |
404 | /* |
405 | * Only one semaphore affected - try to optimize locking. |
406 | * Optimized locking is possible if no complex operation |
407 | * is either enqueued or processed right now. |
408 | * |
409 | * Both facts are tracked by use_global_mode. |
410 | */ |
411 | idx = array_index_nospec(sops->sem_num, sma->sem_nsems); |
412 | sem = &sma->sems[idx]; |
413 | |
414 | /* |
415 | * Initial check for use_global_lock. Just an optimization, |
416 | * no locking, no memory barrier. |
417 | */ |
418 | if (!READ_ONCE(sma->use_global_lock)) { |
419 | /* |
420 | * It appears that no complex operation is around. |
421 | * Acquire the per-semaphore lock. |
422 | */ |
423 | spin_lock(lock: &sem->lock); |
424 | |
425 | /* see SEM_BARRIER_1 for purpose/pairing */ |
426 | if (!smp_load_acquire(&sma->use_global_lock)) { |
427 | /* fast path successful! */ |
428 | return sops->sem_num; |
429 | } |
430 | spin_unlock(lock: &sem->lock); |
431 | } |
432 | |
433 | /* slow path: acquire the full lock */ |
434 | ipc_lock_object(perm: &sma->sem_perm); |
435 | |
436 | if (sma->use_global_lock == 0) { |
437 | /* |
438 | * The use_global_lock mode ended while we waited for |
439 | * sma->sem_perm.lock. Thus we must switch to locking |
440 | * with sem->lock. |
441 | * Unlike in the fast path, there is no need to recheck |
442 | * sma->use_global_lock after we have acquired sem->lock: |
443 | * We own sma->sem_perm.lock, thus use_global_lock cannot |
444 | * change. |
445 | */ |
446 | spin_lock(lock: &sem->lock); |
447 | |
448 | ipc_unlock_object(perm: &sma->sem_perm); |
449 | return sops->sem_num; |
450 | } else { |
451 | /* |
452 | * Not a false alarm, thus continue to use the global lock |
453 | * mode. No need for complexmode_enter(), this was done by |
454 | * the caller that has set use_global_mode to non-zero. |
455 | */ |
456 | return SEM_GLOBAL_LOCK; |
457 | } |
458 | } |
459 | |
460 | static inline void sem_unlock(struct sem_array *sma, int locknum) |
461 | { |
462 | if (locknum == SEM_GLOBAL_LOCK) { |
463 | unmerge_queues(sma); |
464 | complexmode_tryleave(sma); |
465 | ipc_unlock_object(perm: &sma->sem_perm); |
466 | } else { |
467 | struct sem *sem = &sma->sems[locknum]; |
468 | spin_unlock(lock: &sem->lock); |
469 | } |
470 | } |
471 | |
472 | /* |
473 | * sem_lock_(check_) routines are called in the paths where the rwsem |
474 | * is not held. |
475 | * |
476 | * The caller holds the RCU read lock. |
477 | */ |
478 | static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id) |
479 | { |
480 | struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(ids: &sem_ids(ns), id); |
481 | |
482 | if (IS_ERR(ptr: ipcp)) |
483 | return ERR_CAST(ptr: ipcp); |
484 | |
485 | return container_of(ipcp, struct sem_array, sem_perm); |
486 | } |
487 | |
488 | static inline struct sem_array *sem_obtain_object_check(struct ipc_namespace *ns, |
489 | int id) |
490 | { |
491 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(ids: &sem_ids(ns), id); |
492 | |
493 | if (IS_ERR(ptr: ipcp)) |
494 | return ERR_CAST(ptr: ipcp); |
495 | |
496 | return container_of(ipcp, struct sem_array, sem_perm); |
497 | } |
498 | |
499 | static inline void sem_lock_and_putref(struct sem_array *sma) |
500 | { |
501 | sem_lock(sma, NULL, nsops: -1); |
502 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
503 | } |
504 | |
505 | static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) |
506 | { |
507 | ipc_rmid(&sem_ids(ns), &s->sem_perm); |
508 | } |
509 | |
510 | static struct sem_array *sem_alloc(size_t nsems) |
511 | { |
512 | struct sem_array *sma; |
513 | |
514 | if (nsems > (INT_MAX - sizeof(*sma)) / sizeof(sma->sems[0])) |
515 | return NULL; |
516 | |
517 | sma = kvzalloc(struct_size(sma, sems, nsems), GFP_KERNEL_ACCOUNT); |
518 | if (unlikely(!sma)) |
519 | return NULL; |
520 | |
521 | return sma; |
522 | } |
523 | |
524 | /** |
525 | * newary - Create a new semaphore set |
526 | * @ns: namespace |
527 | * @params: ptr to the structure that contains key, semflg and nsems |
528 | * |
529 | * Called with sem_ids.rwsem held (as a writer) |
530 | */ |
531 | static int newary(struct ipc_namespace *ns, struct ipc_params *params) |
532 | { |
533 | int retval; |
534 | struct sem_array *sma; |
535 | key_t key = params->key; |
536 | int nsems = params->u.nsems; |
537 | int semflg = params->flg; |
538 | int i; |
539 | |
540 | if (!nsems) |
541 | return -EINVAL; |
542 | if (ns->used_sems + nsems > ns->sc_semmns) |
543 | return -ENOSPC; |
544 | |
545 | sma = sem_alloc(nsems); |
546 | if (!sma) |
547 | return -ENOMEM; |
548 | |
549 | sma->sem_perm.mode = (semflg & S_IRWXUGO); |
550 | sma->sem_perm.key = key; |
551 | |
552 | sma->sem_perm.security = NULL; |
553 | retval = security_sem_alloc(sma: &sma->sem_perm); |
554 | if (retval) { |
555 | kvfree(addr: sma); |
556 | return retval; |
557 | } |
558 | |
559 | for (i = 0; i < nsems; i++) { |
560 | INIT_LIST_HEAD(list: &sma->sems[i].pending_alter); |
561 | INIT_LIST_HEAD(list: &sma->sems[i].pending_const); |
562 | spin_lock_init(&sma->sems[i].lock); |
563 | } |
564 | |
565 | sma->complex_count = 0; |
566 | sma->use_global_lock = USE_GLOBAL_LOCK_HYSTERESIS; |
567 | INIT_LIST_HEAD(list: &sma->pending_alter); |
568 | INIT_LIST_HEAD(list: &sma->pending_const); |
569 | INIT_LIST_HEAD(list: &sma->list_id); |
570 | sma->sem_nsems = nsems; |
571 | sma->sem_ctime = ktime_get_real_seconds(); |
572 | |
573 | /* ipc_addid() locks sma upon success. */ |
574 | retval = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); |
575 | if (retval < 0) { |
576 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
577 | return retval; |
578 | } |
579 | ns->used_sems += nsems; |
580 | |
581 | sem_unlock(sma, locknum: -1); |
582 | rcu_read_unlock(); |
583 | |
584 | return sma->sem_perm.id; |
585 | } |
586 | |
587 | |
588 | /* |
589 | * Called with sem_ids.rwsem and ipcp locked. |
590 | */ |
591 | static int sem_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params) |
592 | { |
593 | struct sem_array *sma; |
594 | |
595 | sma = container_of(ipcp, struct sem_array, sem_perm); |
596 | if (params->u.nsems > sma->sem_nsems) |
597 | return -EINVAL; |
598 | |
599 | return 0; |
600 | } |
601 | |
602 | long ksys_semget(key_t key, int nsems, int semflg) |
603 | { |
604 | struct ipc_namespace *ns; |
605 | static const struct ipc_ops sem_ops = { |
606 | .getnew = newary, |
607 | .associate = security_sem_associate, |
608 | .more_checks = sem_more_checks, |
609 | }; |
610 | struct ipc_params sem_params; |
611 | |
612 | ns = current->nsproxy->ipc_ns; |
613 | |
614 | if (nsems < 0 || nsems > ns->sc_semmsl) |
615 | return -EINVAL; |
616 | |
617 | sem_params.key = key; |
618 | sem_params.flg = semflg; |
619 | sem_params.u.nsems = nsems; |
620 | |
621 | return ipcget(ns, ids: &sem_ids(ns), ops: &sem_ops, params: &sem_params); |
622 | } |
623 | |
624 | SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) |
625 | { |
626 | return ksys_semget(key, nsems, semflg); |
627 | } |
628 | |
629 | /** |
630 | * perform_atomic_semop[_slow] - Attempt to perform semaphore |
631 | * operations on a given array. |
632 | * @sma: semaphore array |
633 | * @q: struct sem_queue that describes the operation |
634 | * |
635 | * Caller blocking are as follows, based the value |
636 | * indicated by the semaphore operation (sem_op): |
637 | * |
638 | * (1) >0 never blocks. |
639 | * (2) 0 (wait-for-zero operation): semval is non-zero. |
640 | * (3) <0 attempting to decrement semval to a value smaller than zero. |
641 | * |
642 | * Returns 0 if the operation was possible. |
643 | * Returns 1 if the operation is impossible, the caller must sleep. |
644 | * Returns <0 for error codes. |
645 | */ |
646 | static int perform_atomic_semop_slow(struct sem_array *sma, struct sem_queue *q) |
647 | { |
648 | int result, sem_op, nsops; |
649 | struct pid *pid; |
650 | struct sembuf *sop; |
651 | struct sem *curr; |
652 | struct sembuf *sops; |
653 | struct sem_undo *un; |
654 | |
655 | sops = q->sops; |
656 | nsops = q->nsops; |
657 | un = q->undo; |
658 | |
659 | for (sop = sops; sop < sops + nsops; sop++) { |
660 | int idx = array_index_nospec(sop->sem_num, sma->sem_nsems); |
661 | curr = &sma->sems[idx]; |
662 | sem_op = sop->sem_op; |
663 | result = curr->semval; |
664 | |
665 | if (!sem_op && result) |
666 | goto would_block; |
667 | |
668 | result += sem_op; |
669 | if (result < 0) |
670 | goto would_block; |
671 | if (result > SEMVMX) |
672 | goto out_of_range; |
673 | |
674 | if (sop->sem_flg & SEM_UNDO) { |
675 | int undo = un->semadj[sop->sem_num] - sem_op; |
676 | /* Exceeding the undo range is an error. */ |
677 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) |
678 | goto out_of_range; |
679 | un->semadj[sop->sem_num] = undo; |
680 | } |
681 | |
682 | curr->semval = result; |
683 | } |
684 | |
685 | sop--; |
686 | pid = q->pid; |
687 | while (sop >= sops) { |
688 | ipc_update_pid(pos: &sma->sems[sop->sem_num].sempid, pid); |
689 | sop--; |
690 | } |
691 | |
692 | return 0; |
693 | |
694 | out_of_range: |
695 | result = -ERANGE; |
696 | goto undo; |
697 | |
698 | would_block: |
699 | q->blocking = sop; |
700 | |
701 | if (sop->sem_flg & IPC_NOWAIT) |
702 | result = -EAGAIN; |
703 | else |
704 | result = 1; |
705 | |
706 | undo: |
707 | sop--; |
708 | while (sop >= sops) { |
709 | sem_op = sop->sem_op; |
710 | sma->sems[sop->sem_num].semval -= sem_op; |
711 | if (sop->sem_flg & SEM_UNDO) |
712 | un->semadj[sop->sem_num] += sem_op; |
713 | sop--; |
714 | } |
715 | |
716 | return result; |
717 | } |
718 | |
719 | static int perform_atomic_semop(struct sem_array *sma, struct sem_queue *q) |
720 | { |
721 | int result, sem_op, nsops; |
722 | struct sembuf *sop; |
723 | struct sem *curr; |
724 | struct sembuf *sops; |
725 | struct sem_undo *un; |
726 | |
727 | sops = q->sops; |
728 | nsops = q->nsops; |
729 | un = q->undo; |
730 | |
731 | if (unlikely(q->dupsop)) |
732 | return perform_atomic_semop_slow(sma, q); |
733 | |
734 | /* |
735 | * We scan the semaphore set twice, first to ensure that the entire |
736 | * operation can succeed, therefore avoiding any pointless writes |
737 | * to shared memory and having to undo such changes in order to block |
738 | * until the operations can go through. |
739 | */ |
740 | for (sop = sops; sop < sops + nsops; sop++) { |
741 | int idx = array_index_nospec(sop->sem_num, sma->sem_nsems); |
742 | |
743 | curr = &sma->sems[idx]; |
744 | sem_op = sop->sem_op; |
745 | result = curr->semval; |
746 | |
747 | if (!sem_op && result) |
748 | goto would_block; /* wait-for-zero */ |
749 | |
750 | result += sem_op; |
751 | if (result < 0) |
752 | goto would_block; |
753 | |
754 | if (result > SEMVMX) |
755 | return -ERANGE; |
756 | |
757 | if (sop->sem_flg & SEM_UNDO) { |
758 | int undo = un->semadj[sop->sem_num] - sem_op; |
759 | |
760 | /* Exceeding the undo range is an error. */ |
761 | if (undo < (-SEMAEM - 1) || undo > SEMAEM) |
762 | return -ERANGE; |
763 | } |
764 | } |
765 | |
766 | for (sop = sops; sop < sops + nsops; sop++) { |
767 | curr = &sma->sems[sop->sem_num]; |
768 | sem_op = sop->sem_op; |
769 | |
770 | if (sop->sem_flg & SEM_UNDO) { |
771 | int undo = un->semadj[sop->sem_num] - sem_op; |
772 | |
773 | un->semadj[sop->sem_num] = undo; |
774 | } |
775 | curr->semval += sem_op; |
776 | ipc_update_pid(pos: &curr->sempid, pid: q->pid); |
777 | } |
778 | |
779 | return 0; |
780 | |
781 | would_block: |
782 | q->blocking = sop; |
783 | return sop->sem_flg & IPC_NOWAIT ? -EAGAIN : 1; |
784 | } |
785 | |
786 | static inline void wake_up_sem_queue_prepare(struct sem_queue *q, int error, |
787 | struct wake_q_head *wake_q) |
788 | { |
789 | struct task_struct *sleeper; |
790 | |
791 | sleeper = get_task_struct(t: q->sleeper); |
792 | |
793 | /* see SEM_BARRIER_2 for purpose/pairing */ |
794 | smp_store_release(&q->status, error); |
795 | |
796 | wake_q_add_safe(head: wake_q, task: sleeper); |
797 | } |
798 | |
799 | static void unlink_queue(struct sem_array *sma, struct sem_queue *q) |
800 | { |
801 | list_del(entry: &q->list); |
802 | if (q->nsops > 1) |
803 | sma->complex_count--; |
804 | } |
805 | |
806 | /** check_restart(sma, q) |
807 | * @sma: semaphore array |
808 | * @q: the operation that just completed |
809 | * |
810 | * update_queue is O(N^2) when it restarts scanning the whole queue of |
811 | * waiting operations. Therefore this function checks if the restart is |
812 | * really necessary. It is called after a previously waiting operation |
813 | * modified the array. |
814 | * Note that wait-for-zero operations are handled without restart. |
815 | */ |
816 | static inline int check_restart(struct sem_array *sma, struct sem_queue *q) |
817 | { |
818 | /* pending complex alter operations are too difficult to analyse */ |
819 | if (!list_empty(head: &sma->pending_alter)) |
820 | return 1; |
821 | |
822 | /* we were a sleeping complex operation. Too difficult */ |
823 | if (q->nsops > 1) |
824 | return 1; |
825 | |
826 | /* It is impossible that someone waits for the new value: |
827 | * - complex operations always restart. |
828 | * - wait-for-zero are handled separately. |
829 | * - q is a previously sleeping simple operation that |
830 | * altered the array. It must be a decrement, because |
831 | * simple increments never sleep. |
832 | * - If there are older (higher priority) decrements |
833 | * in the queue, then they have observed the original |
834 | * semval value and couldn't proceed. The operation |
835 | * decremented to value - thus they won't proceed either. |
836 | */ |
837 | return 0; |
838 | } |
839 | |
840 | /** |
841 | * wake_const_ops - wake up non-alter tasks |
842 | * @sma: semaphore array. |
843 | * @semnum: semaphore that was modified. |
844 | * @wake_q: lockless wake-queue head. |
845 | * |
846 | * wake_const_ops must be called after a semaphore in a semaphore array |
847 | * was set to 0. If complex const operations are pending, wake_const_ops must |
848 | * be called with semnum = -1, as well as with the number of each modified |
849 | * semaphore. |
850 | * The tasks that must be woken up are added to @wake_q. The return code |
851 | * is stored in q->pid. |
852 | * The function returns 1 if at least one operation was completed successfully. |
853 | */ |
854 | static int wake_const_ops(struct sem_array *sma, int semnum, |
855 | struct wake_q_head *wake_q) |
856 | { |
857 | struct sem_queue *q, *tmp; |
858 | struct list_head *pending_list; |
859 | int semop_completed = 0; |
860 | |
861 | if (semnum == -1) |
862 | pending_list = &sma->pending_const; |
863 | else |
864 | pending_list = &sma->sems[semnum].pending_const; |
865 | |
866 | list_for_each_entry_safe(q, tmp, pending_list, list) { |
867 | int error = perform_atomic_semop(sma, q); |
868 | |
869 | if (error > 0) |
870 | continue; |
871 | /* operation completed, remove from queue & wakeup */ |
872 | unlink_queue(sma, q); |
873 | |
874 | wake_up_sem_queue_prepare(q, error, wake_q); |
875 | if (error == 0) |
876 | semop_completed = 1; |
877 | } |
878 | |
879 | return semop_completed; |
880 | } |
881 | |
882 | /** |
883 | * do_smart_wakeup_zero - wakeup all wait for zero tasks |
884 | * @sma: semaphore array |
885 | * @sops: operations that were performed |
886 | * @nsops: number of operations |
887 | * @wake_q: lockless wake-queue head |
888 | * |
889 | * Checks all required queue for wait-for-zero operations, based |
890 | * on the actual changes that were performed on the semaphore array. |
891 | * The function returns 1 if at least one operation was completed successfully. |
892 | */ |
893 | static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, |
894 | int nsops, struct wake_q_head *wake_q) |
895 | { |
896 | int i; |
897 | int semop_completed = 0; |
898 | int got_zero = 0; |
899 | |
900 | /* first: the per-semaphore queues, if known */ |
901 | if (sops) { |
902 | for (i = 0; i < nsops; i++) { |
903 | int num = sops[i].sem_num; |
904 | |
905 | if (sma->sems[num].semval == 0) { |
906 | got_zero = 1; |
907 | semop_completed |= wake_const_ops(sma, semnum: num, wake_q); |
908 | } |
909 | } |
910 | } else { |
911 | /* |
912 | * No sops means modified semaphores not known. |
913 | * Assume all were changed. |
914 | */ |
915 | for (i = 0; i < sma->sem_nsems; i++) { |
916 | if (sma->sems[i].semval == 0) { |
917 | got_zero = 1; |
918 | semop_completed |= wake_const_ops(sma, semnum: i, wake_q); |
919 | } |
920 | } |
921 | } |
922 | /* |
923 | * If one of the modified semaphores got 0, |
924 | * then check the global queue, too. |
925 | */ |
926 | if (got_zero) |
927 | semop_completed |= wake_const_ops(sma, semnum: -1, wake_q); |
928 | |
929 | return semop_completed; |
930 | } |
931 | |
932 | |
933 | /** |
934 | * update_queue - look for tasks that can be completed. |
935 | * @sma: semaphore array. |
936 | * @semnum: semaphore that was modified. |
937 | * @wake_q: lockless wake-queue head. |
938 | * |
939 | * update_queue must be called after a semaphore in a semaphore array |
940 | * was modified. If multiple semaphores were modified, update_queue must |
941 | * be called with semnum = -1, as well as with the number of each modified |
942 | * semaphore. |
943 | * The tasks that must be woken up are added to @wake_q. The return code |
944 | * is stored in q->pid. |
945 | * The function internally checks if const operations can now succeed. |
946 | * |
947 | * The function return 1 if at least one semop was completed successfully. |
948 | */ |
949 | static int update_queue(struct sem_array *sma, int semnum, struct wake_q_head *wake_q) |
950 | { |
951 | struct sem_queue *q, *tmp; |
952 | struct list_head *pending_list; |
953 | int semop_completed = 0; |
954 | |
955 | if (semnum == -1) |
956 | pending_list = &sma->pending_alter; |
957 | else |
958 | pending_list = &sma->sems[semnum].pending_alter; |
959 | |
960 | again: |
961 | list_for_each_entry_safe(q, tmp, pending_list, list) { |
962 | int error, restart; |
963 | |
964 | /* If we are scanning the single sop, per-semaphore list of |
965 | * one semaphore and that semaphore is 0, then it is not |
966 | * necessary to scan further: simple increments |
967 | * that affect only one entry succeed immediately and cannot |
968 | * be in the per semaphore pending queue, and decrements |
969 | * cannot be successful if the value is already 0. |
970 | */ |
971 | if (semnum != -1 && sma->sems[semnum].semval == 0) |
972 | break; |
973 | |
974 | error = perform_atomic_semop(sma, q); |
975 | |
976 | /* Does q->sleeper still need to sleep? */ |
977 | if (error > 0) |
978 | continue; |
979 | |
980 | unlink_queue(sma, q); |
981 | |
982 | if (error) { |
983 | restart = 0; |
984 | } else { |
985 | semop_completed = 1; |
986 | do_smart_wakeup_zero(sma, sops: q->sops, nsops: q->nsops, wake_q); |
987 | restart = check_restart(sma, q); |
988 | } |
989 | |
990 | wake_up_sem_queue_prepare(q, error, wake_q); |
991 | if (restart) |
992 | goto again; |
993 | } |
994 | return semop_completed; |
995 | } |
996 | |
997 | /** |
998 | * set_semotime - set sem_otime |
999 | * @sma: semaphore array |
1000 | * @sops: operations that modified the array, may be NULL |
1001 | * |
1002 | * sem_otime is replicated to avoid cache line trashing. |
1003 | * This function sets one instance to the current time. |
1004 | */ |
1005 | static void set_semotime(struct sem_array *sma, struct sembuf *sops) |
1006 | { |
1007 | if (sops == NULL) { |
1008 | sma->sems[0].sem_otime = ktime_get_real_seconds(); |
1009 | } else { |
1010 | sma->sems[sops[0].sem_num].sem_otime = |
1011 | ktime_get_real_seconds(); |
1012 | } |
1013 | } |
1014 | |
1015 | /** |
1016 | * do_smart_update - optimized update_queue |
1017 | * @sma: semaphore array |
1018 | * @sops: operations that were performed |
1019 | * @nsops: number of operations |
1020 | * @otime: force setting otime |
1021 | * @wake_q: lockless wake-queue head |
1022 | * |
1023 | * do_smart_update() does the required calls to update_queue and wakeup_zero, |
1024 | * based on the actual changes that were performed on the semaphore array. |
1025 | * Note that the function does not do the actual wake-up: the caller is |
1026 | * responsible for calling wake_up_q(). |
1027 | * It is safe to perform this call after dropping all locks. |
1028 | */ |
1029 | static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops, |
1030 | int otime, struct wake_q_head *wake_q) |
1031 | { |
1032 | int i; |
1033 | |
1034 | otime |= do_smart_wakeup_zero(sma, sops, nsops, wake_q); |
1035 | |
1036 | if (!list_empty(head: &sma->pending_alter)) { |
1037 | /* semaphore array uses the global queue - just process it. */ |
1038 | otime |= update_queue(sma, semnum: -1, wake_q); |
1039 | } else { |
1040 | if (!sops) { |
1041 | /* |
1042 | * No sops, thus the modified semaphores are not |
1043 | * known. Check all. |
1044 | */ |
1045 | for (i = 0; i < sma->sem_nsems; i++) |
1046 | otime |= update_queue(sma, semnum: i, wake_q); |
1047 | } else { |
1048 | /* |
1049 | * Check the semaphores that were increased: |
1050 | * - No complex ops, thus all sleeping ops are |
1051 | * decrease. |
1052 | * - if we decreased the value, then any sleeping |
1053 | * semaphore ops won't be able to run: If the |
1054 | * previous value was too small, then the new |
1055 | * value will be too small, too. |
1056 | */ |
1057 | for (i = 0; i < nsops; i++) { |
1058 | if (sops[i].sem_op > 0) { |
1059 | otime |= update_queue(sma, |
1060 | semnum: sops[i].sem_num, wake_q); |
1061 | } |
1062 | } |
1063 | } |
1064 | } |
1065 | if (otime) |
1066 | set_semotime(sma, sops); |
1067 | } |
1068 | |
1069 | /* |
1070 | * check_qop: Test if a queued operation sleeps on the semaphore semnum |
1071 | */ |
1072 | static int check_qop(struct sem_array *sma, int semnum, struct sem_queue *q, |
1073 | bool count_zero) |
1074 | { |
1075 | struct sembuf *sop = q->blocking; |
1076 | |
1077 | /* |
1078 | * Linux always (since 0.99.10) reported a task as sleeping on all |
1079 | * semaphores. This violates SUS, therefore it was changed to the |
1080 | * standard compliant behavior. |
1081 | * Give the administrators a chance to notice that an application |
1082 | * might misbehave because it relies on the Linux behavior. |
1083 | */ |
1084 | pr_info_once("semctl(GETNCNT/GETZCNT) is since 3.16 Single Unix Specification compliant.\n" |
1085 | "The task %s (%d) triggered the difference, watch for misbehavior.\n" , |
1086 | current->comm, task_pid_nr(current)); |
1087 | |
1088 | if (sop->sem_num != semnum) |
1089 | return 0; |
1090 | |
1091 | if (count_zero && sop->sem_op == 0) |
1092 | return 1; |
1093 | if (!count_zero && sop->sem_op < 0) |
1094 | return 1; |
1095 | |
1096 | return 0; |
1097 | } |
1098 | |
1099 | /* The following counts are associated to each semaphore: |
1100 | * semncnt number of tasks waiting on semval being nonzero |
1101 | * semzcnt number of tasks waiting on semval being zero |
1102 | * |
1103 | * Per definition, a task waits only on the semaphore of the first semop |
1104 | * that cannot proceed, even if additional operation would block, too. |
1105 | */ |
1106 | static int count_semcnt(struct sem_array *sma, ushort semnum, |
1107 | bool count_zero) |
1108 | { |
1109 | struct list_head *l; |
1110 | struct sem_queue *q; |
1111 | int semcnt; |
1112 | |
1113 | semcnt = 0; |
1114 | /* First: check the simple operations. They are easy to evaluate */ |
1115 | if (count_zero) |
1116 | l = &sma->sems[semnum].pending_const; |
1117 | else |
1118 | l = &sma->sems[semnum].pending_alter; |
1119 | |
1120 | list_for_each_entry(q, l, list) { |
1121 | /* all task on a per-semaphore list sleep on exactly |
1122 | * that semaphore |
1123 | */ |
1124 | semcnt++; |
1125 | } |
1126 | |
1127 | /* Then: check the complex operations. */ |
1128 | list_for_each_entry(q, &sma->pending_alter, list) { |
1129 | semcnt += check_qop(sma, semnum, q, count_zero); |
1130 | } |
1131 | if (count_zero) { |
1132 | list_for_each_entry(q, &sma->pending_const, list) { |
1133 | semcnt += check_qop(sma, semnum, q, count_zero); |
1134 | } |
1135 | } |
1136 | return semcnt; |
1137 | } |
1138 | |
1139 | /* Free a semaphore set. freeary() is called with sem_ids.rwsem locked |
1140 | * as a writer and the spinlock for this semaphore set hold. sem_ids.rwsem |
1141 | * remains locked on exit. |
1142 | */ |
1143 | static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
1144 | { |
1145 | struct sem_undo *un, *tu; |
1146 | struct sem_queue *q, *tq; |
1147 | struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
1148 | int i; |
1149 | DEFINE_WAKE_Q(wake_q); |
1150 | |
1151 | /* Free the existing undo structures for this semaphore set. */ |
1152 | ipc_assert_locked_object(perm: &sma->sem_perm); |
1153 | list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { |
1154 | list_del(entry: &un->list_id); |
1155 | spin_lock(lock: &un->ulp->lock); |
1156 | un->semid = -1; |
1157 | list_del_rcu(entry: &un->list_proc); |
1158 | spin_unlock(lock: &un->ulp->lock); |
1159 | kvfree_rcu(un, rcu); |
1160 | } |
1161 | |
1162 | /* Wake up all pending processes and let them fail with EIDRM. */ |
1163 | list_for_each_entry_safe(q, tq, &sma->pending_const, list) { |
1164 | unlink_queue(sma, q); |
1165 | wake_up_sem_queue_prepare(q, error: -EIDRM, wake_q: &wake_q); |
1166 | } |
1167 | |
1168 | list_for_each_entry_safe(q, tq, &sma->pending_alter, list) { |
1169 | unlink_queue(sma, q); |
1170 | wake_up_sem_queue_prepare(q, error: -EIDRM, wake_q: &wake_q); |
1171 | } |
1172 | for (i = 0; i < sma->sem_nsems; i++) { |
1173 | struct sem *sem = &sma->sems[i]; |
1174 | list_for_each_entry_safe(q, tq, &sem->pending_const, list) { |
1175 | unlink_queue(sma, q); |
1176 | wake_up_sem_queue_prepare(q, error: -EIDRM, wake_q: &wake_q); |
1177 | } |
1178 | list_for_each_entry_safe(q, tq, &sem->pending_alter, list) { |
1179 | unlink_queue(sma, q); |
1180 | wake_up_sem_queue_prepare(q, error: -EIDRM, wake_q: &wake_q); |
1181 | } |
1182 | ipc_update_pid(pos: &sem->sempid, NULL); |
1183 | } |
1184 | |
1185 | /* Remove the semaphore set from the IDR */ |
1186 | sem_rmid(ns, s: sma); |
1187 | sem_unlock(sma, locknum: -1); |
1188 | rcu_read_unlock(); |
1189 | |
1190 | wake_up_q(head: &wake_q); |
1191 | ns->used_sems -= sma->sem_nsems; |
1192 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1193 | } |
1194 | |
1195 | static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) |
1196 | { |
1197 | switch (version) { |
1198 | case IPC_64: |
1199 | return copy_to_user(to: buf, from: in, n: sizeof(*in)); |
1200 | case IPC_OLD: |
1201 | { |
1202 | struct semid_ds out; |
1203 | |
1204 | memset(&out, 0, sizeof(out)); |
1205 | |
1206 | ipc64_perm_to_ipc_perm(in: &in->sem_perm, out: &out.sem_perm); |
1207 | |
1208 | out.sem_otime = in->sem_otime; |
1209 | out.sem_ctime = in->sem_ctime; |
1210 | out.sem_nsems = in->sem_nsems; |
1211 | |
1212 | return copy_to_user(to: buf, from: &out, n: sizeof(out)); |
1213 | } |
1214 | default: |
1215 | return -EINVAL; |
1216 | } |
1217 | } |
1218 | |
1219 | static time64_t get_semotime(struct sem_array *sma) |
1220 | { |
1221 | int i; |
1222 | time64_t res; |
1223 | |
1224 | res = sma->sems[0].sem_otime; |
1225 | for (i = 1; i < sma->sem_nsems; i++) { |
1226 | time64_t to = sma->sems[i].sem_otime; |
1227 | |
1228 | if (to > res) |
1229 | res = to; |
1230 | } |
1231 | return res; |
1232 | } |
1233 | |
1234 | static int semctl_stat(struct ipc_namespace *ns, int semid, |
1235 | int cmd, struct semid64_ds *semid64) |
1236 | { |
1237 | struct sem_array *sma; |
1238 | time64_t semotime; |
1239 | int err; |
1240 | |
1241 | memset(semid64, 0, sizeof(*semid64)); |
1242 | |
1243 | rcu_read_lock(); |
1244 | if (cmd == SEM_STAT || cmd == SEM_STAT_ANY) { |
1245 | sma = sem_obtain_object(ns, id: semid); |
1246 | if (IS_ERR(ptr: sma)) { |
1247 | err = PTR_ERR(ptr: sma); |
1248 | goto out_unlock; |
1249 | } |
1250 | } else { /* IPC_STAT */ |
1251 | sma = sem_obtain_object_check(ns, id: semid); |
1252 | if (IS_ERR(ptr: sma)) { |
1253 | err = PTR_ERR(ptr: sma); |
1254 | goto out_unlock; |
1255 | } |
1256 | } |
1257 | |
1258 | /* see comment for SHM_STAT_ANY */ |
1259 | if (cmd == SEM_STAT_ANY) |
1260 | audit_ipc_obj(ipcp: &sma->sem_perm); |
1261 | else { |
1262 | err = -EACCES; |
1263 | if (ipcperms(ns, ipcp: &sma->sem_perm, S_IRUGO)) |
1264 | goto out_unlock; |
1265 | } |
1266 | |
1267 | err = security_sem_semctl(sma: &sma->sem_perm, cmd); |
1268 | if (err) |
1269 | goto out_unlock; |
1270 | |
1271 | ipc_lock_object(perm: &sma->sem_perm); |
1272 | |
1273 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1274 | ipc_unlock_object(perm: &sma->sem_perm); |
1275 | err = -EIDRM; |
1276 | goto out_unlock; |
1277 | } |
1278 | |
1279 | kernel_to_ipc64_perm(in: &sma->sem_perm, out: &semid64->sem_perm); |
1280 | semotime = get_semotime(sma); |
1281 | semid64->sem_otime = semotime; |
1282 | semid64->sem_ctime = sma->sem_ctime; |
1283 | #ifndef CONFIG_64BIT |
1284 | semid64->sem_otime_high = semotime >> 32; |
1285 | semid64->sem_ctime_high = sma->sem_ctime >> 32; |
1286 | #endif |
1287 | semid64->sem_nsems = sma->sem_nsems; |
1288 | |
1289 | if (cmd == IPC_STAT) { |
1290 | /* |
1291 | * As defined in SUS: |
1292 | * Return 0 on success |
1293 | */ |
1294 | err = 0; |
1295 | } else { |
1296 | /* |
1297 | * SEM_STAT and SEM_STAT_ANY (both Linux specific) |
1298 | * Return the full id, including the sequence number |
1299 | */ |
1300 | err = sma->sem_perm.id; |
1301 | } |
1302 | ipc_unlock_object(perm: &sma->sem_perm); |
1303 | out_unlock: |
1304 | rcu_read_unlock(); |
1305 | return err; |
1306 | } |
1307 | |
1308 | static int semctl_info(struct ipc_namespace *ns, int semid, |
1309 | int cmd, void __user *p) |
1310 | { |
1311 | struct seminfo seminfo; |
1312 | int max_idx; |
1313 | int err; |
1314 | |
1315 | err = security_sem_semctl(NULL, cmd); |
1316 | if (err) |
1317 | return err; |
1318 | |
1319 | memset(&seminfo, 0, sizeof(seminfo)); |
1320 | seminfo.semmni = ns->sc_semmni; |
1321 | seminfo.semmns = ns->sc_semmns; |
1322 | seminfo.semmsl = ns->sc_semmsl; |
1323 | seminfo.semopm = ns->sc_semopm; |
1324 | seminfo.semvmx = SEMVMX; |
1325 | seminfo.semmnu = SEMMNU; |
1326 | seminfo.semmap = SEMMAP; |
1327 | seminfo.semume = SEMUME; |
1328 | down_read(sem: &sem_ids(ns).rwsem); |
1329 | if (cmd == SEM_INFO) { |
1330 | seminfo.semusz = sem_ids(ns).in_use; |
1331 | seminfo.semaem = ns->used_sems; |
1332 | } else { |
1333 | seminfo.semusz = SEMUSZ; |
1334 | seminfo.semaem = SEMAEM; |
1335 | } |
1336 | max_idx = ipc_get_maxidx(ids: &sem_ids(ns)); |
1337 | up_read(sem: &sem_ids(ns).rwsem); |
1338 | if (copy_to_user(to: p, from: &seminfo, n: sizeof(struct seminfo))) |
1339 | return -EFAULT; |
1340 | return (max_idx < 0) ? 0 : max_idx; |
1341 | } |
1342 | |
1343 | static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, |
1344 | int val) |
1345 | { |
1346 | struct sem_undo *un; |
1347 | struct sem_array *sma; |
1348 | struct sem *curr; |
1349 | int err; |
1350 | DEFINE_WAKE_Q(wake_q); |
1351 | |
1352 | if (val > SEMVMX || val < 0) |
1353 | return -ERANGE; |
1354 | |
1355 | rcu_read_lock(); |
1356 | sma = sem_obtain_object_check(ns, id: semid); |
1357 | if (IS_ERR(ptr: sma)) { |
1358 | rcu_read_unlock(); |
1359 | return PTR_ERR(ptr: sma); |
1360 | } |
1361 | |
1362 | if (semnum < 0 || semnum >= sma->sem_nsems) { |
1363 | rcu_read_unlock(); |
1364 | return -EINVAL; |
1365 | } |
1366 | |
1367 | |
1368 | if (ipcperms(ns, ipcp: &sma->sem_perm, S_IWUGO)) { |
1369 | rcu_read_unlock(); |
1370 | return -EACCES; |
1371 | } |
1372 | |
1373 | err = security_sem_semctl(sma: &sma->sem_perm, SETVAL); |
1374 | if (err) { |
1375 | rcu_read_unlock(); |
1376 | return -EACCES; |
1377 | } |
1378 | |
1379 | sem_lock(sma, NULL, nsops: -1); |
1380 | |
1381 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1382 | sem_unlock(sma, locknum: -1); |
1383 | rcu_read_unlock(); |
1384 | return -EIDRM; |
1385 | } |
1386 | |
1387 | semnum = array_index_nospec(semnum, sma->sem_nsems); |
1388 | curr = &sma->sems[semnum]; |
1389 | |
1390 | ipc_assert_locked_object(perm: &sma->sem_perm); |
1391 | list_for_each_entry(un, &sma->list_id, list_id) |
1392 | un->semadj[semnum] = 0; |
1393 | |
1394 | curr->semval = val; |
1395 | ipc_update_pid(pos: &curr->sempid, pid: task_tgid(current)); |
1396 | sma->sem_ctime = ktime_get_real_seconds(); |
1397 | /* maybe some queued-up processes were waiting for this */ |
1398 | do_smart_update(sma, NULL, nsops: 0, otime: 0, wake_q: &wake_q); |
1399 | sem_unlock(sma, locknum: -1); |
1400 | rcu_read_unlock(); |
1401 | wake_up_q(head: &wake_q); |
1402 | return 0; |
1403 | } |
1404 | |
1405 | static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, |
1406 | int cmd, void __user *p) |
1407 | { |
1408 | struct sem_array *sma; |
1409 | struct sem *curr; |
1410 | int err, nsems; |
1411 | ushort fast_sem_io[SEMMSL_FAST]; |
1412 | ushort *sem_io = fast_sem_io; |
1413 | DEFINE_WAKE_Q(wake_q); |
1414 | |
1415 | rcu_read_lock(); |
1416 | sma = sem_obtain_object_check(ns, id: semid); |
1417 | if (IS_ERR(ptr: sma)) { |
1418 | rcu_read_unlock(); |
1419 | return PTR_ERR(ptr: sma); |
1420 | } |
1421 | |
1422 | nsems = sma->sem_nsems; |
1423 | |
1424 | err = -EACCES; |
1425 | if (ipcperms(ns, ipcp: &sma->sem_perm, flg: cmd == SETALL ? S_IWUGO : S_IRUGO)) |
1426 | goto out_rcu_wakeup; |
1427 | |
1428 | err = security_sem_semctl(sma: &sma->sem_perm, cmd); |
1429 | if (err) |
1430 | goto out_rcu_wakeup; |
1431 | |
1432 | switch (cmd) { |
1433 | case GETALL: |
1434 | { |
1435 | ushort __user *array = p; |
1436 | int i; |
1437 | |
1438 | sem_lock(sma, NULL, nsops: -1); |
1439 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1440 | err = -EIDRM; |
1441 | goto out_unlock; |
1442 | } |
1443 | if (nsems > SEMMSL_FAST) { |
1444 | if (!ipc_rcu_getref(ptr: &sma->sem_perm)) { |
1445 | err = -EIDRM; |
1446 | goto out_unlock; |
1447 | } |
1448 | sem_unlock(sma, locknum: -1); |
1449 | rcu_read_unlock(); |
1450 | sem_io = kvmalloc_array(n: nsems, size: sizeof(ushort), |
1451 | GFP_KERNEL); |
1452 | if (sem_io == NULL) { |
1453 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1454 | return -ENOMEM; |
1455 | } |
1456 | |
1457 | rcu_read_lock(); |
1458 | sem_lock_and_putref(sma); |
1459 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1460 | err = -EIDRM; |
1461 | goto out_unlock; |
1462 | } |
1463 | } |
1464 | for (i = 0; i < sma->sem_nsems; i++) |
1465 | sem_io[i] = sma->sems[i].semval; |
1466 | sem_unlock(sma, locknum: -1); |
1467 | rcu_read_unlock(); |
1468 | err = 0; |
1469 | if (copy_to_user(to: array, from: sem_io, n: nsems*sizeof(ushort))) |
1470 | err = -EFAULT; |
1471 | goto out_free; |
1472 | } |
1473 | case SETALL: |
1474 | { |
1475 | int i; |
1476 | struct sem_undo *un; |
1477 | |
1478 | if (!ipc_rcu_getref(ptr: &sma->sem_perm)) { |
1479 | err = -EIDRM; |
1480 | goto out_rcu_wakeup; |
1481 | } |
1482 | rcu_read_unlock(); |
1483 | |
1484 | if (nsems > SEMMSL_FAST) { |
1485 | sem_io = kvmalloc_array(n: nsems, size: sizeof(ushort), |
1486 | GFP_KERNEL); |
1487 | if (sem_io == NULL) { |
1488 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1489 | return -ENOMEM; |
1490 | } |
1491 | } |
1492 | |
1493 | if (copy_from_user(to: sem_io, from: p, n: nsems*sizeof(ushort))) { |
1494 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1495 | err = -EFAULT; |
1496 | goto out_free; |
1497 | } |
1498 | |
1499 | for (i = 0; i < nsems; i++) { |
1500 | if (sem_io[i] > SEMVMX) { |
1501 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1502 | err = -ERANGE; |
1503 | goto out_free; |
1504 | } |
1505 | } |
1506 | rcu_read_lock(); |
1507 | sem_lock_and_putref(sma); |
1508 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1509 | err = -EIDRM; |
1510 | goto out_unlock; |
1511 | } |
1512 | |
1513 | for (i = 0; i < nsems; i++) { |
1514 | sma->sems[i].semval = sem_io[i]; |
1515 | ipc_update_pid(pos: &sma->sems[i].sempid, pid: task_tgid(current)); |
1516 | } |
1517 | |
1518 | ipc_assert_locked_object(perm: &sma->sem_perm); |
1519 | list_for_each_entry(un, &sma->list_id, list_id) { |
1520 | for (i = 0; i < nsems; i++) |
1521 | un->semadj[i] = 0; |
1522 | } |
1523 | sma->sem_ctime = ktime_get_real_seconds(); |
1524 | /* maybe some queued-up processes were waiting for this */ |
1525 | do_smart_update(sma, NULL, nsops: 0, otime: 0, wake_q: &wake_q); |
1526 | err = 0; |
1527 | goto out_unlock; |
1528 | } |
1529 | /* GETVAL, GETPID, GETNCTN, GETZCNT: fall-through */ |
1530 | } |
1531 | err = -EINVAL; |
1532 | if (semnum < 0 || semnum >= nsems) |
1533 | goto out_rcu_wakeup; |
1534 | |
1535 | sem_lock(sma, NULL, nsops: -1); |
1536 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1537 | err = -EIDRM; |
1538 | goto out_unlock; |
1539 | } |
1540 | |
1541 | semnum = array_index_nospec(semnum, nsems); |
1542 | curr = &sma->sems[semnum]; |
1543 | |
1544 | switch (cmd) { |
1545 | case GETVAL: |
1546 | err = curr->semval; |
1547 | goto out_unlock; |
1548 | case GETPID: |
1549 | err = pid_vnr(pid: curr->sempid); |
1550 | goto out_unlock; |
1551 | case GETNCNT: |
1552 | err = count_semcnt(sma, semnum, count_zero: 0); |
1553 | goto out_unlock; |
1554 | case GETZCNT: |
1555 | err = count_semcnt(sma, semnum, count_zero: 1); |
1556 | goto out_unlock; |
1557 | } |
1558 | |
1559 | out_unlock: |
1560 | sem_unlock(sma, locknum: -1); |
1561 | out_rcu_wakeup: |
1562 | rcu_read_unlock(); |
1563 | wake_up_q(head: &wake_q); |
1564 | out_free: |
1565 | if (sem_io != fast_sem_io) |
1566 | kvfree(addr: sem_io); |
1567 | return err; |
1568 | } |
1569 | |
1570 | static inline unsigned long |
1571 | copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) |
1572 | { |
1573 | switch (version) { |
1574 | case IPC_64: |
1575 | if (copy_from_user(to: out, from: buf, n: sizeof(*out))) |
1576 | return -EFAULT; |
1577 | return 0; |
1578 | case IPC_OLD: |
1579 | { |
1580 | struct semid_ds tbuf_old; |
1581 | |
1582 | if (copy_from_user(to: &tbuf_old, from: buf, n: sizeof(tbuf_old))) |
1583 | return -EFAULT; |
1584 | |
1585 | out->sem_perm.uid = tbuf_old.sem_perm.uid; |
1586 | out->sem_perm.gid = tbuf_old.sem_perm.gid; |
1587 | out->sem_perm.mode = tbuf_old.sem_perm.mode; |
1588 | |
1589 | return 0; |
1590 | } |
1591 | default: |
1592 | return -EINVAL; |
1593 | } |
1594 | } |
1595 | |
1596 | /* |
1597 | * This function handles some semctl commands which require the rwsem |
1598 | * to be held in write mode. |
1599 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
1600 | */ |
1601 | static int semctl_down(struct ipc_namespace *ns, int semid, |
1602 | int cmd, struct semid64_ds *semid64) |
1603 | { |
1604 | struct sem_array *sma; |
1605 | int err; |
1606 | struct kern_ipc_perm *ipcp; |
1607 | |
1608 | down_write(sem: &sem_ids(ns).rwsem); |
1609 | rcu_read_lock(); |
1610 | |
1611 | ipcp = ipcctl_obtain_check(ns, ids: &sem_ids(ns), id: semid, cmd, |
1612 | perm: &semid64->sem_perm, extra_perm: 0); |
1613 | if (IS_ERR(ptr: ipcp)) { |
1614 | err = PTR_ERR(ptr: ipcp); |
1615 | goto out_unlock1; |
1616 | } |
1617 | |
1618 | sma = container_of(ipcp, struct sem_array, sem_perm); |
1619 | |
1620 | err = security_sem_semctl(sma: &sma->sem_perm, cmd); |
1621 | if (err) |
1622 | goto out_unlock1; |
1623 | |
1624 | switch (cmd) { |
1625 | case IPC_RMID: |
1626 | sem_lock(sma, NULL, nsops: -1); |
1627 | /* freeary unlocks the ipc object and rcu */ |
1628 | freeary(ns, ipcp); |
1629 | goto out_up; |
1630 | case IPC_SET: |
1631 | sem_lock(sma, NULL, nsops: -1); |
1632 | err = ipc_update_perm(in: &semid64->sem_perm, out: ipcp); |
1633 | if (err) |
1634 | goto out_unlock0; |
1635 | sma->sem_ctime = ktime_get_real_seconds(); |
1636 | break; |
1637 | default: |
1638 | err = -EINVAL; |
1639 | goto out_unlock1; |
1640 | } |
1641 | |
1642 | out_unlock0: |
1643 | sem_unlock(sma, locknum: -1); |
1644 | out_unlock1: |
1645 | rcu_read_unlock(); |
1646 | out_up: |
1647 | up_write(sem: &sem_ids(ns).rwsem); |
1648 | return err; |
1649 | } |
1650 | |
1651 | static long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg, int version) |
1652 | { |
1653 | struct ipc_namespace *ns; |
1654 | void __user *p = (void __user *)arg; |
1655 | struct semid64_ds semid64; |
1656 | int err; |
1657 | |
1658 | if (semid < 0) |
1659 | return -EINVAL; |
1660 | |
1661 | ns = current->nsproxy->ipc_ns; |
1662 | |
1663 | switch (cmd) { |
1664 | case IPC_INFO: |
1665 | case SEM_INFO: |
1666 | return semctl_info(ns, semid, cmd, p); |
1667 | case IPC_STAT: |
1668 | case SEM_STAT: |
1669 | case SEM_STAT_ANY: |
1670 | err = semctl_stat(ns, semid, cmd, semid64: &semid64); |
1671 | if (err < 0) |
1672 | return err; |
1673 | if (copy_semid_to_user(buf: p, in: &semid64, version)) |
1674 | err = -EFAULT; |
1675 | return err; |
1676 | case GETALL: |
1677 | case GETVAL: |
1678 | case GETPID: |
1679 | case GETNCNT: |
1680 | case GETZCNT: |
1681 | case SETALL: |
1682 | return semctl_main(ns, semid, semnum, cmd, p); |
1683 | case SETVAL: { |
1684 | int val; |
1685 | #if defined(CONFIG_64BIT) && defined(__BIG_ENDIAN) |
1686 | /* big-endian 64bit */ |
1687 | val = arg >> 32; |
1688 | #else |
1689 | /* 32bit or little-endian 64bit */ |
1690 | val = arg; |
1691 | #endif |
1692 | return semctl_setval(ns, semid, semnum, val); |
1693 | } |
1694 | case IPC_SET: |
1695 | if (copy_semid_from_user(out: &semid64, buf: p, version)) |
1696 | return -EFAULT; |
1697 | fallthrough; |
1698 | case IPC_RMID: |
1699 | return semctl_down(ns, semid, cmd, semid64: &semid64); |
1700 | default: |
1701 | return -EINVAL; |
1702 | } |
1703 | } |
1704 | |
1705 | SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) |
1706 | { |
1707 | return ksys_semctl(semid, semnum, cmd, arg, IPC_64); |
1708 | } |
1709 | |
1710 | #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION |
1711 | long ksys_old_semctl(int semid, int semnum, int cmd, unsigned long arg) |
1712 | { |
1713 | int version = ipc_parse_version(&cmd); |
1714 | |
1715 | return ksys_semctl(semid, semnum, cmd, arg, version); |
1716 | } |
1717 | |
1718 | SYSCALL_DEFINE4(old_semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) |
1719 | { |
1720 | return ksys_old_semctl(semid, semnum, cmd, arg); |
1721 | } |
1722 | #endif |
1723 | |
1724 | #ifdef CONFIG_COMPAT |
1725 | |
1726 | struct compat_semid_ds { |
1727 | struct compat_ipc_perm sem_perm; |
1728 | old_time32_t sem_otime; |
1729 | old_time32_t sem_ctime; |
1730 | compat_uptr_t sem_base; |
1731 | compat_uptr_t sem_pending; |
1732 | compat_uptr_t sem_pending_last; |
1733 | compat_uptr_t undo; |
1734 | unsigned short sem_nsems; |
1735 | }; |
1736 | |
1737 | static int copy_compat_semid_from_user(struct semid64_ds *out, void __user *buf, |
1738 | int version) |
1739 | { |
1740 | memset(out, 0, sizeof(*out)); |
1741 | if (version == IPC_64) { |
1742 | struct compat_semid64_ds __user *p = buf; |
1743 | return get_compat_ipc64_perm(&out->sem_perm, &p->sem_perm); |
1744 | } else { |
1745 | struct compat_semid_ds __user *p = buf; |
1746 | return get_compat_ipc_perm(&out->sem_perm, &p->sem_perm); |
1747 | } |
1748 | } |
1749 | |
1750 | static int copy_compat_semid_to_user(void __user *buf, struct semid64_ds *in, |
1751 | int version) |
1752 | { |
1753 | if (version == IPC_64) { |
1754 | struct compat_semid64_ds v; |
1755 | memset(&v, 0, sizeof(v)); |
1756 | to_compat_ipc64_perm(&v.sem_perm, &in->sem_perm); |
1757 | v.sem_otime = lower_32_bits(in->sem_otime); |
1758 | v.sem_otime_high = upper_32_bits(in->sem_otime); |
1759 | v.sem_ctime = lower_32_bits(in->sem_ctime); |
1760 | v.sem_ctime_high = upper_32_bits(in->sem_ctime); |
1761 | v.sem_nsems = in->sem_nsems; |
1762 | return copy_to_user(to: buf, from: &v, n: sizeof(v)); |
1763 | } else { |
1764 | struct compat_semid_ds v; |
1765 | memset(&v, 0, sizeof(v)); |
1766 | to_compat_ipc_perm(&v.sem_perm, &in->sem_perm); |
1767 | v.sem_otime = in->sem_otime; |
1768 | v.sem_ctime = in->sem_ctime; |
1769 | v.sem_nsems = in->sem_nsems; |
1770 | return copy_to_user(to: buf, from: &v, n: sizeof(v)); |
1771 | } |
1772 | } |
1773 | |
1774 | static long compat_ksys_semctl(int semid, int semnum, int cmd, int arg, int version) |
1775 | { |
1776 | void __user *p = compat_ptr(uptr: arg); |
1777 | struct ipc_namespace *ns; |
1778 | struct semid64_ds semid64; |
1779 | int err; |
1780 | |
1781 | ns = current->nsproxy->ipc_ns; |
1782 | |
1783 | if (semid < 0) |
1784 | return -EINVAL; |
1785 | |
1786 | switch (cmd & (~IPC_64)) { |
1787 | case IPC_INFO: |
1788 | case SEM_INFO: |
1789 | return semctl_info(ns, semid, cmd, p); |
1790 | case IPC_STAT: |
1791 | case SEM_STAT: |
1792 | case SEM_STAT_ANY: |
1793 | err = semctl_stat(ns, semid, cmd, semid64: &semid64); |
1794 | if (err < 0) |
1795 | return err; |
1796 | if (copy_compat_semid_to_user(buf: p, in: &semid64, version)) |
1797 | err = -EFAULT; |
1798 | return err; |
1799 | case GETVAL: |
1800 | case GETPID: |
1801 | case GETNCNT: |
1802 | case GETZCNT: |
1803 | case GETALL: |
1804 | case SETALL: |
1805 | return semctl_main(ns, semid, semnum, cmd, p); |
1806 | case SETVAL: |
1807 | return semctl_setval(ns, semid, semnum, val: arg); |
1808 | case IPC_SET: |
1809 | if (copy_compat_semid_from_user(out: &semid64, buf: p, version)) |
1810 | return -EFAULT; |
1811 | fallthrough; |
1812 | case IPC_RMID: |
1813 | return semctl_down(ns, semid, cmd, semid64: &semid64); |
1814 | default: |
1815 | return -EINVAL; |
1816 | } |
1817 | } |
1818 | |
1819 | COMPAT_SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, int, arg) |
1820 | { |
1821 | return compat_ksys_semctl(semid, semnum, cmd, arg, IPC_64); |
1822 | } |
1823 | |
1824 | #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION |
1825 | long compat_ksys_old_semctl(int semid, int semnum, int cmd, int arg) |
1826 | { |
1827 | int version = compat_ipc_parse_version(cmd: &cmd); |
1828 | |
1829 | return compat_ksys_semctl(semid, semnum, cmd, arg, version); |
1830 | } |
1831 | |
1832 | COMPAT_SYSCALL_DEFINE4(old_semctl, int, semid, int, semnum, int, cmd, int, arg) |
1833 | { |
1834 | return compat_ksys_old_semctl(semid, semnum, cmd, arg); |
1835 | } |
1836 | #endif |
1837 | #endif |
1838 | |
1839 | /* If the task doesn't already have a undo_list, then allocate one |
1840 | * here. We guarantee there is only one thread using this undo list, |
1841 | * and current is THE ONE |
1842 | * |
1843 | * If this allocation and assignment succeeds, but later |
1844 | * portions of this code fail, there is no need to free the sem_undo_list. |
1845 | * Just let it stay associated with the task, and it'll be freed later |
1846 | * at exit time. |
1847 | * |
1848 | * This can block, so callers must hold no locks. |
1849 | */ |
1850 | static inline int get_undo_list(struct sem_undo_list **undo_listp) |
1851 | { |
1852 | struct sem_undo_list *undo_list; |
1853 | |
1854 | undo_list = current->sysvsem.undo_list; |
1855 | if (!undo_list) { |
1856 | undo_list = kzalloc(size: sizeof(*undo_list), GFP_KERNEL_ACCOUNT); |
1857 | if (undo_list == NULL) |
1858 | return -ENOMEM; |
1859 | spin_lock_init(&undo_list->lock); |
1860 | refcount_set(r: &undo_list->refcnt, n: 1); |
1861 | INIT_LIST_HEAD(list: &undo_list->list_proc); |
1862 | |
1863 | current->sysvsem.undo_list = undo_list; |
1864 | } |
1865 | *undo_listp = undo_list; |
1866 | return 0; |
1867 | } |
1868 | |
1869 | static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid) |
1870 | { |
1871 | struct sem_undo *un; |
1872 | |
1873 | list_for_each_entry_rcu(un, &ulp->list_proc, list_proc, |
1874 | spin_is_locked(&ulp->lock)) { |
1875 | if (un->semid == semid) |
1876 | return un; |
1877 | } |
1878 | return NULL; |
1879 | } |
1880 | |
1881 | static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) |
1882 | { |
1883 | struct sem_undo *un; |
1884 | |
1885 | assert_spin_locked(&ulp->lock); |
1886 | |
1887 | un = __lookup_undo(ulp, semid); |
1888 | if (un) { |
1889 | list_del_rcu(entry: &un->list_proc); |
1890 | list_add_rcu(new: &un->list_proc, head: &ulp->list_proc); |
1891 | } |
1892 | return un; |
1893 | } |
1894 | |
1895 | /** |
1896 | * find_alloc_undo - lookup (and if not present create) undo array |
1897 | * @ns: namespace |
1898 | * @semid: semaphore array id |
1899 | * |
1900 | * The function looks up (and if not present creates) the undo structure. |
1901 | * The size of the undo structure depends on the size of the semaphore |
1902 | * array, thus the alloc path is not that straightforward. |
1903 | * Lifetime-rules: sem_undo is rcu-protected, on success, the function |
1904 | * performs a rcu_read_lock(). |
1905 | */ |
1906 | static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) |
1907 | { |
1908 | struct sem_array *sma; |
1909 | struct sem_undo_list *ulp; |
1910 | struct sem_undo *un, *new; |
1911 | int nsems, error; |
1912 | |
1913 | error = get_undo_list(undo_listp: &ulp); |
1914 | if (error) |
1915 | return ERR_PTR(error); |
1916 | |
1917 | rcu_read_lock(); |
1918 | spin_lock(lock: &ulp->lock); |
1919 | un = lookup_undo(ulp, semid); |
1920 | spin_unlock(lock: &ulp->lock); |
1921 | if (likely(un != NULL)) |
1922 | goto out; |
1923 | |
1924 | /* no undo structure around - allocate one. */ |
1925 | /* step 1: figure out the size of the semaphore array */ |
1926 | sma = sem_obtain_object_check(ns, id: semid); |
1927 | if (IS_ERR(ptr: sma)) { |
1928 | rcu_read_unlock(); |
1929 | return ERR_CAST(ptr: sma); |
1930 | } |
1931 | |
1932 | nsems = sma->sem_nsems; |
1933 | if (!ipc_rcu_getref(ptr: &sma->sem_perm)) { |
1934 | rcu_read_unlock(); |
1935 | un = ERR_PTR(error: -EIDRM); |
1936 | goto out; |
1937 | } |
1938 | rcu_read_unlock(); |
1939 | |
1940 | /* step 2: allocate new undo structure */ |
1941 | new = kvzalloc(struct_size(new, semadj, nsems), GFP_KERNEL_ACCOUNT); |
1942 | if (!new) { |
1943 | ipc_rcu_putref(ptr: &sma->sem_perm, func: sem_rcu_free); |
1944 | return ERR_PTR(error: -ENOMEM); |
1945 | } |
1946 | |
1947 | /* step 3: Acquire the lock on semaphore array */ |
1948 | rcu_read_lock(); |
1949 | sem_lock_and_putref(sma); |
1950 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
1951 | sem_unlock(sma, locknum: -1); |
1952 | rcu_read_unlock(); |
1953 | kvfree(addr: new); |
1954 | un = ERR_PTR(error: -EIDRM); |
1955 | goto out; |
1956 | } |
1957 | spin_lock(lock: &ulp->lock); |
1958 | |
1959 | /* |
1960 | * step 4: check for races: did someone else allocate the undo struct? |
1961 | */ |
1962 | un = lookup_undo(ulp, semid); |
1963 | if (un) { |
1964 | spin_unlock(lock: &ulp->lock); |
1965 | kvfree(addr: new); |
1966 | goto success; |
1967 | } |
1968 | /* step 5: initialize & link new undo structure */ |
1969 | new->ulp = ulp; |
1970 | new->semid = semid; |
1971 | assert_spin_locked(&ulp->lock); |
1972 | list_add_rcu(new: &new->list_proc, head: &ulp->list_proc); |
1973 | ipc_assert_locked_object(perm: &sma->sem_perm); |
1974 | list_add(new: &new->list_id, head: &sma->list_id); |
1975 | un = new; |
1976 | spin_unlock(lock: &ulp->lock); |
1977 | success: |
1978 | sem_unlock(sma, locknum: -1); |
1979 | out: |
1980 | return un; |
1981 | } |
1982 | |
1983 | long __do_semtimedop(int semid, struct sembuf *sops, |
1984 | unsigned nsops, const struct timespec64 *timeout, |
1985 | struct ipc_namespace *ns) |
1986 | { |
1987 | int error = -EINVAL; |
1988 | struct sem_array *sma; |
1989 | struct sembuf *sop; |
1990 | struct sem_undo *un; |
1991 | int max, locknum; |
1992 | bool undos = false, alter = false, dupsop = false; |
1993 | struct sem_queue queue; |
1994 | unsigned long dup = 0; |
1995 | ktime_t expires, *exp = NULL; |
1996 | bool timed_out = false; |
1997 | |
1998 | if (nsops < 1 || semid < 0) |
1999 | return -EINVAL; |
2000 | if (nsops > ns->sc_semopm) |
2001 | return -E2BIG; |
2002 | |
2003 | if (timeout) { |
2004 | if (!timespec64_valid(ts: timeout)) |
2005 | return -EINVAL; |
2006 | expires = ktime_add_safe(lhs: ktime_get(), |
2007 | rhs: timespec64_to_ktime(ts: *timeout)); |
2008 | exp = &expires; |
2009 | } |
2010 | |
2011 | |
2012 | max = 0; |
2013 | for (sop = sops; sop < sops + nsops; sop++) { |
2014 | unsigned long mask = 1ULL << ((sop->sem_num) % BITS_PER_LONG); |
2015 | |
2016 | if (sop->sem_num >= max) |
2017 | max = sop->sem_num; |
2018 | if (sop->sem_flg & SEM_UNDO) |
2019 | undos = true; |
2020 | if (dup & mask) { |
2021 | /* |
2022 | * There was a previous alter access that appears |
2023 | * to have accessed the same semaphore, thus use |
2024 | * the dupsop logic. "appears", because the detection |
2025 | * can only check % BITS_PER_LONG. |
2026 | */ |
2027 | dupsop = true; |
2028 | } |
2029 | if (sop->sem_op != 0) { |
2030 | alter = true; |
2031 | dup |= mask; |
2032 | } |
2033 | } |
2034 | |
2035 | if (undos) { |
2036 | /* On success, find_alloc_undo takes the rcu_read_lock */ |
2037 | un = find_alloc_undo(ns, semid); |
2038 | if (IS_ERR(ptr: un)) { |
2039 | error = PTR_ERR(ptr: un); |
2040 | goto out; |
2041 | } |
2042 | } else { |
2043 | un = NULL; |
2044 | rcu_read_lock(); |
2045 | } |
2046 | |
2047 | sma = sem_obtain_object_check(ns, id: semid); |
2048 | if (IS_ERR(ptr: sma)) { |
2049 | rcu_read_unlock(); |
2050 | error = PTR_ERR(ptr: sma); |
2051 | goto out; |
2052 | } |
2053 | |
2054 | error = -EFBIG; |
2055 | if (max >= sma->sem_nsems) { |
2056 | rcu_read_unlock(); |
2057 | goto out; |
2058 | } |
2059 | |
2060 | error = -EACCES; |
2061 | if (ipcperms(ns, ipcp: &sma->sem_perm, flg: alter ? S_IWUGO : S_IRUGO)) { |
2062 | rcu_read_unlock(); |
2063 | goto out; |
2064 | } |
2065 | |
2066 | error = security_sem_semop(sma: &sma->sem_perm, sops, nsops, alter); |
2067 | if (error) { |
2068 | rcu_read_unlock(); |
2069 | goto out; |
2070 | } |
2071 | |
2072 | error = -EIDRM; |
2073 | locknum = sem_lock(sma, sops, nsops); |
2074 | /* |
2075 | * We eventually might perform the following check in a lockless |
2076 | * fashion, considering ipc_valid_object() locking constraints. |
2077 | * If nsops == 1 and there is no contention for sem_perm.lock, then |
2078 | * only a per-semaphore lock is held and it's OK to proceed with the |
2079 | * check below. More details on the fine grained locking scheme |
2080 | * entangled here and why it's RMID race safe on comments at sem_lock() |
2081 | */ |
2082 | if (!ipc_valid_object(perm: &sma->sem_perm)) |
2083 | goto out_unlock; |
2084 | /* |
2085 | * semid identifiers are not unique - find_alloc_undo may have |
2086 | * allocated an undo structure, it was invalidated by an RMID |
2087 | * and now a new array with received the same id. Check and fail. |
2088 | * This case can be detected checking un->semid. The existence of |
2089 | * "un" itself is guaranteed by rcu. |
2090 | */ |
2091 | if (un && un->semid == -1) |
2092 | goto out_unlock; |
2093 | |
2094 | queue.sops = sops; |
2095 | queue.nsops = nsops; |
2096 | queue.undo = un; |
2097 | queue.pid = task_tgid(current); |
2098 | queue.alter = alter; |
2099 | queue.dupsop = dupsop; |
2100 | |
2101 | error = perform_atomic_semop(sma, q: &queue); |
2102 | if (error == 0) { /* non-blocking successful path */ |
2103 | DEFINE_WAKE_Q(wake_q); |
2104 | |
2105 | /* |
2106 | * If the operation was successful, then do |
2107 | * the required updates. |
2108 | */ |
2109 | if (alter) |
2110 | do_smart_update(sma, sops, nsops, otime: 1, wake_q: &wake_q); |
2111 | else |
2112 | set_semotime(sma, sops); |
2113 | |
2114 | sem_unlock(sma, locknum); |
2115 | rcu_read_unlock(); |
2116 | wake_up_q(head: &wake_q); |
2117 | |
2118 | goto out; |
2119 | } |
2120 | if (error < 0) /* non-blocking error path */ |
2121 | goto out_unlock; |
2122 | |
2123 | /* |
2124 | * We need to sleep on this operation, so we put the current |
2125 | * task into the pending queue and go to sleep. |
2126 | */ |
2127 | if (nsops == 1) { |
2128 | struct sem *curr; |
2129 | int idx = array_index_nospec(sops->sem_num, sma->sem_nsems); |
2130 | curr = &sma->sems[idx]; |
2131 | |
2132 | if (alter) { |
2133 | if (sma->complex_count) { |
2134 | list_add_tail(new: &queue.list, |
2135 | head: &sma->pending_alter); |
2136 | } else { |
2137 | |
2138 | list_add_tail(new: &queue.list, |
2139 | head: &curr->pending_alter); |
2140 | } |
2141 | } else { |
2142 | list_add_tail(new: &queue.list, head: &curr->pending_const); |
2143 | } |
2144 | } else { |
2145 | if (!sma->complex_count) |
2146 | merge_queues(sma); |
2147 | |
2148 | if (alter) |
2149 | list_add_tail(new: &queue.list, head: &sma->pending_alter); |
2150 | else |
2151 | list_add_tail(new: &queue.list, head: &sma->pending_const); |
2152 | |
2153 | sma->complex_count++; |
2154 | } |
2155 | |
2156 | do { |
2157 | /* memory ordering ensured by the lock in sem_lock() */ |
2158 | WRITE_ONCE(queue.status, -EINTR); |
2159 | queue.sleeper = current; |
2160 | |
2161 | /* memory ordering is ensured by the lock in sem_lock() */ |
2162 | __set_current_state(TASK_INTERRUPTIBLE); |
2163 | sem_unlock(sma, locknum); |
2164 | rcu_read_unlock(); |
2165 | |
2166 | timed_out = !schedule_hrtimeout_range(expires: exp, |
2167 | current->timer_slack_ns, mode: HRTIMER_MODE_ABS); |
2168 | |
2169 | /* |
2170 | * fastpath: the semop has completed, either successfully or |
2171 | * not, from the syscall pov, is quite irrelevant to us at this |
2172 | * point; we're done. |
2173 | * |
2174 | * We _do_ care, nonetheless, about being awoken by a signal or |
2175 | * spuriously. The queue.status is checked again in the |
2176 | * slowpath (aka after taking sem_lock), such that we can detect |
2177 | * scenarios where we were awakened externally, during the |
2178 | * window between wake_q_add() and wake_up_q(). |
2179 | */ |
2180 | rcu_read_lock(); |
2181 | error = READ_ONCE(queue.status); |
2182 | if (error != -EINTR) { |
2183 | /* see SEM_BARRIER_2 for purpose/pairing */ |
2184 | smp_acquire__after_ctrl_dep(); |
2185 | rcu_read_unlock(); |
2186 | goto out; |
2187 | } |
2188 | |
2189 | locknum = sem_lock(sma, sops, nsops); |
2190 | |
2191 | if (!ipc_valid_object(perm: &sma->sem_perm)) |
2192 | goto out_unlock; |
2193 | |
2194 | /* |
2195 | * No necessity for any barrier: We are protect by sem_lock() |
2196 | */ |
2197 | error = READ_ONCE(queue.status); |
2198 | |
2199 | /* |
2200 | * If queue.status != -EINTR we are woken up by another process. |
2201 | * Leave without unlink_queue(), but with sem_unlock(). |
2202 | */ |
2203 | if (error != -EINTR) |
2204 | goto out_unlock; |
2205 | |
2206 | /* |
2207 | * If an interrupt occurred we have to clean up the queue. |
2208 | */ |
2209 | if (timed_out) |
2210 | error = -EAGAIN; |
2211 | } while (error == -EINTR && !signal_pending(current)); /* spurious */ |
2212 | |
2213 | unlink_queue(sma, q: &queue); |
2214 | |
2215 | out_unlock: |
2216 | sem_unlock(sma, locknum); |
2217 | rcu_read_unlock(); |
2218 | out: |
2219 | return error; |
2220 | } |
2221 | |
2222 | static long do_semtimedop(int semid, struct sembuf __user *tsops, |
2223 | unsigned nsops, const struct timespec64 *timeout) |
2224 | { |
2225 | struct sembuf fast_sops[SEMOPM_FAST]; |
2226 | struct sembuf *sops = fast_sops; |
2227 | struct ipc_namespace *ns; |
2228 | int ret; |
2229 | |
2230 | ns = current->nsproxy->ipc_ns; |
2231 | if (nsops > ns->sc_semopm) |
2232 | return -E2BIG; |
2233 | if (nsops < 1) |
2234 | return -EINVAL; |
2235 | |
2236 | if (nsops > SEMOPM_FAST) { |
2237 | sops = kvmalloc_array(n: nsops, size: sizeof(*sops), GFP_KERNEL); |
2238 | if (sops == NULL) |
2239 | return -ENOMEM; |
2240 | } |
2241 | |
2242 | if (copy_from_user(to: sops, from: tsops, n: nsops * sizeof(*tsops))) { |
2243 | ret = -EFAULT; |
2244 | goto out_free; |
2245 | } |
2246 | |
2247 | ret = __do_semtimedop(semid, sops, nsops, timeout, ns); |
2248 | |
2249 | out_free: |
2250 | if (sops != fast_sops) |
2251 | kvfree(addr: sops); |
2252 | |
2253 | return ret; |
2254 | } |
2255 | |
2256 | long ksys_semtimedop(int semid, struct sembuf __user *tsops, |
2257 | unsigned int nsops, const struct __kernel_timespec __user *timeout) |
2258 | { |
2259 | if (timeout) { |
2260 | struct timespec64 ts; |
2261 | if (get_timespec64(ts: &ts, uts: timeout)) |
2262 | return -EFAULT; |
2263 | return do_semtimedop(semid, tsops, nsops, timeout: &ts); |
2264 | } |
2265 | return do_semtimedop(semid, tsops, nsops, NULL); |
2266 | } |
2267 | |
2268 | SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, |
2269 | unsigned int, nsops, const struct __kernel_timespec __user *, timeout) |
2270 | { |
2271 | return ksys_semtimedop(semid, tsops, nsops, timeout); |
2272 | } |
2273 | |
2274 | #ifdef CONFIG_COMPAT_32BIT_TIME |
2275 | long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems, |
2276 | unsigned int nsops, |
2277 | const struct old_timespec32 __user *timeout) |
2278 | { |
2279 | if (timeout) { |
2280 | struct timespec64 ts; |
2281 | if (get_old_timespec32(&ts, timeout)) |
2282 | return -EFAULT; |
2283 | return do_semtimedop(semid, tsops: tsems, nsops, timeout: &ts); |
2284 | } |
2285 | return do_semtimedop(semid, tsops: tsems, nsops, NULL); |
2286 | } |
2287 | |
2288 | SYSCALL_DEFINE4(semtimedop_time32, int, semid, struct sembuf __user *, tsems, |
2289 | unsigned int, nsops, |
2290 | const struct old_timespec32 __user *, timeout) |
2291 | { |
2292 | return compat_ksys_semtimedop(semid, tsems, nsops, timeout); |
2293 | } |
2294 | #endif |
2295 | |
2296 | SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops, |
2297 | unsigned, nsops) |
2298 | { |
2299 | return do_semtimedop(semid, tsops, nsops, NULL); |
2300 | } |
2301 | |
2302 | /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between |
2303 | * parent and child tasks. |
2304 | */ |
2305 | |
2306 | int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) |
2307 | { |
2308 | struct sem_undo_list *undo_list; |
2309 | int error; |
2310 | |
2311 | if (clone_flags & CLONE_SYSVSEM) { |
2312 | error = get_undo_list(undo_listp: &undo_list); |
2313 | if (error) |
2314 | return error; |
2315 | refcount_inc(r: &undo_list->refcnt); |
2316 | tsk->sysvsem.undo_list = undo_list; |
2317 | } else |
2318 | tsk->sysvsem.undo_list = NULL; |
2319 | |
2320 | return 0; |
2321 | } |
2322 | |
2323 | /* |
2324 | * add semadj values to semaphores, free undo structures. |
2325 | * undo structures are not freed when semaphore arrays are destroyed |
2326 | * so some of them may be out of date. |
2327 | * IMPLEMENTATION NOTE: There is some confusion over whether the |
2328 | * set of adjustments that needs to be done should be done in an atomic |
2329 | * manner or not. That is, if we are attempting to decrement the semval |
2330 | * should we queue up and wait until we can do so legally? |
2331 | * The original implementation attempted to do this (queue and wait). |
2332 | * The current implementation does not do so. The POSIX standard |
2333 | * and SVID should be consulted to determine what behavior is mandated. |
2334 | */ |
2335 | void exit_sem(struct task_struct *tsk) |
2336 | { |
2337 | struct sem_undo_list *ulp; |
2338 | |
2339 | ulp = tsk->sysvsem.undo_list; |
2340 | if (!ulp) |
2341 | return; |
2342 | tsk->sysvsem.undo_list = NULL; |
2343 | |
2344 | if (!refcount_dec_and_test(r: &ulp->refcnt)) |
2345 | return; |
2346 | |
2347 | for (;;) { |
2348 | struct sem_array *sma; |
2349 | struct sem_undo *un; |
2350 | int semid, i; |
2351 | DEFINE_WAKE_Q(wake_q); |
2352 | |
2353 | cond_resched(); |
2354 | |
2355 | rcu_read_lock(); |
2356 | un = list_entry_rcu(ulp->list_proc.next, |
2357 | struct sem_undo, list_proc); |
2358 | if (&un->list_proc == &ulp->list_proc) { |
2359 | /* |
2360 | * We must wait for freeary() before freeing this ulp, |
2361 | * in case we raced with last sem_undo. There is a small |
2362 | * possibility where we exit while freeary() didn't |
2363 | * finish unlocking sem_undo_list. |
2364 | */ |
2365 | spin_lock(lock: &ulp->lock); |
2366 | spin_unlock(lock: &ulp->lock); |
2367 | rcu_read_unlock(); |
2368 | break; |
2369 | } |
2370 | spin_lock(lock: &ulp->lock); |
2371 | semid = un->semid; |
2372 | spin_unlock(lock: &ulp->lock); |
2373 | |
2374 | /* exit_sem raced with IPC_RMID, nothing to do */ |
2375 | if (semid == -1) { |
2376 | rcu_read_unlock(); |
2377 | continue; |
2378 | } |
2379 | |
2380 | sma = sem_obtain_object_check(ns: tsk->nsproxy->ipc_ns, id: semid); |
2381 | /* exit_sem raced with IPC_RMID, nothing to do */ |
2382 | if (IS_ERR(ptr: sma)) { |
2383 | rcu_read_unlock(); |
2384 | continue; |
2385 | } |
2386 | |
2387 | sem_lock(sma, NULL, nsops: -1); |
2388 | /* exit_sem raced with IPC_RMID, nothing to do */ |
2389 | if (!ipc_valid_object(perm: &sma->sem_perm)) { |
2390 | sem_unlock(sma, locknum: -1); |
2391 | rcu_read_unlock(); |
2392 | continue; |
2393 | } |
2394 | un = __lookup_undo(ulp, semid); |
2395 | if (un == NULL) { |
2396 | /* exit_sem raced with IPC_RMID+semget() that created |
2397 | * exactly the same semid. Nothing to do. |
2398 | */ |
2399 | sem_unlock(sma, locknum: -1); |
2400 | rcu_read_unlock(); |
2401 | continue; |
2402 | } |
2403 | |
2404 | /* remove un from the linked lists */ |
2405 | ipc_assert_locked_object(perm: &sma->sem_perm); |
2406 | list_del(entry: &un->list_id); |
2407 | |
2408 | spin_lock(lock: &ulp->lock); |
2409 | list_del_rcu(entry: &un->list_proc); |
2410 | spin_unlock(lock: &ulp->lock); |
2411 | |
2412 | /* perform adjustments registered in un */ |
2413 | for (i = 0; i < sma->sem_nsems; i++) { |
2414 | struct sem *semaphore = &sma->sems[i]; |
2415 | if (un->semadj[i]) { |
2416 | semaphore->semval += un->semadj[i]; |
2417 | /* |
2418 | * Range checks of the new semaphore value, |
2419 | * not defined by sus: |
2420 | * - Some unices ignore the undo entirely |
2421 | * (e.g. HP UX 11i 11.22, Tru64 V5.1) |
2422 | * - some cap the value (e.g. FreeBSD caps |
2423 | * at 0, but doesn't enforce SEMVMX) |
2424 | * |
2425 | * Linux caps the semaphore value, both at 0 |
2426 | * and at SEMVMX. |
2427 | * |
2428 | * Manfred <manfred@colorfullife.com> |
2429 | */ |
2430 | if (semaphore->semval < 0) |
2431 | semaphore->semval = 0; |
2432 | if (semaphore->semval > SEMVMX) |
2433 | semaphore->semval = SEMVMX; |
2434 | ipc_update_pid(pos: &semaphore->sempid, pid: task_tgid(current)); |
2435 | } |
2436 | } |
2437 | /* maybe some queued-up processes were waiting for this */ |
2438 | do_smart_update(sma, NULL, nsops: 0, otime: 1, wake_q: &wake_q); |
2439 | sem_unlock(sma, locknum: -1); |
2440 | rcu_read_unlock(); |
2441 | wake_up_q(head: &wake_q); |
2442 | |
2443 | kvfree_rcu(un, rcu); |
2444 | } |
2445 | kfree(objp: ulp); |
2446 | } |
2447 | |
2448 | #ifdef CONFIG_PROC_FS |
2449 | static int sysvipc_sem_proc_show(struct seq_file *s, void *it) |
2450 | { |
2451 | struct user_namespace *user_ns = seq_user_ns(seq: s); |
2452 | struct kern_ipc_perm *ipcp = it; |
2453 | struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
2454 | time64_t sem_otime; |
2455 | |
2456 | /* |
2457 | * The proc interface isn't aware of sem_lock(), it calls |
2458 | * ipc_lock_object(), i.e. spin_lock(&sma->sem_perm.lock). |
2459 | * (in sysvipc_find_ipc) |
2460 | * In order to stay compatible with sem_lock(), we must |
2461 | * enter / leave complex_mode. |
2462 | */ |
2463 | complexmode_enter(sma); |
2464 | |
2465 | sem_otime = get_semotime(sma); |
2466 | |
2467 | seq_printf(m: s, |
2468 | fmt: "%10d %10d %4o %10u %5u %5u %5u %5u %10llu %10llu\n" , |
2469 | sma->sem_perm.key, |
2470 | sma->sem_perm.id, |
2471 | sma->sem_perm.mode, |
2472 | sma->sem_nsems, |
2473 | from_kuid_munged(to: user_ns, uid: sma->sem_perm.uid), |
2474 | from_kgid_munged(to: user_ns, gid: sma->sem_perm.gid), |
2475 | from_kuid_munged(to: user_ns, uid: sma->sem_perm.cuid), |
2476 | from_kgid_munged(to: user_ns, gid: sma->sem_perm.cgid), |
2477 | sem_otime, |
2478 | sma->sem_ctime); |
2479 | |
2480 | complexmode_tryleave(sma); |
2481 | |
2482 | return 0; |
2483 | } |
2484 | #endif |
2485 | |