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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/ipc/sem.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 * Copyright (C) 1995 Eric Schenk, Bruno Haible
5 *
6 * IMPLEMENTATION NOTES ON CODE REWRITE (Eric Schenk, January 1995):
7 * This code underwent a massive rewrite in order to solve some problems
8 * with the original code. In particular the original code failed to
9 * wake up processes that were waiting for semval to go to 0 if the
10 * value went to 0 and was then incremented rapidly enough. In solving
11 * this problem I have also modified the implementation so that it
12 * processes pending operations in a FIFO manner, thus give a guarantee
13 * that processes waiting for a lock on the semaphore won't starve
14 * unless another locking process fails to unlock.
15 * In addition the following two changes in behavior have been introduced:
16 * - The original implementation of semop returned the value
17 * last semaphore element examined on success. This does not
18 * match the manual page specifications, and effectively
19 * allows the user to read the semaphore even if they do not
20 * have read permissions. The implementation now returns 0
21 * on success as stated in the manual page.
22 * - There is some confusion over whether the set of undo adjustments
23 * to be performed at exit should be done in an atomic manner.
24 * That is, if we are attempting to decrement the semval should we queue
25 * up and wait until we can do so legally?
26 * The original implementation attempted to do this.
27 * The current implementation does not do so. This is because I don't
28 * think it is the right thing (TM) to do, and because I couldn't
29 * see a clean way to get the old behavior with the new design.
30 * The POSIX standard and SVID should be consulted to determine
31 * what behavior is mandated.
32 *
33 * Further notes on refinement (Christoph Rohland, December 1998):
34 * - The POSIX standard says, that the undo adjustments simply should
35 * redo. So the current implementation is o.K.
36 * - The previous code had two flaws:
37 * 1) It actively gave the semaphore to the next waiting process
38 * sleeping on the semaphore. Since this process did not have the
39 * cpu this led to many unnecessary context switches and bad
40 * performance. Now we only check which process should be able to
41 * get the semaphore and if this process wants to reduce some
42 * semaphore value we simply wake it up without doing the
43 * operation. So it has to try to get it later. Thus e.g. the
44 * running process may reacquire the semaphore during the current
45 * time slice. If it only waits for zero or increases the semaphore,
46 * we do the operation in advance and wake it up.
47 * 2) It did not wake up all zero waiting processes. We try to do
48 * better but only get the semops right which only wait for zero or
49 * increase. If there are decrement operations in the operations
50 * array we do the same as before.
51 *
52 * With the incarnation of O(1) scheduler, it becomes unnecessary to perform
53 * check/retry algorithm for waking up blocked processes as the new scheduler
54 * is better at handling thread switch than the old one.
55 *
56 * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
57 *
58 * SMP-threaded, sysctl's added
Christian Kujau624dffc2006-01-15 02:43:54 +010059 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 * Enforced range limit on SEM_UNDO
61 * (c) 2001 Red Hat Inc <alan@redhat.com>
62 * Lockless wakeup
63 * (c) 2003 Manfred Spraul <manfred@colorfullife.com>
Steve Grubb073115d2006-04-02 17:07:33 -040064 *
65 * support for audit of ipc object properties and permission changes
66 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
Kirill Korotaeve3893532006-10-02 02:18:22 -070067 *
68 * namespaces support
69 * OpenVZ, SWsoft Inc.
70 * Pavel Emelianov <xemul@openvz.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 */
72
Linus Torvalds1da177e2005-04-16 15:20:36 -070073#include <linux/slab.h>
74#include <linux/spinlock.h>
75#include <linux/init.h>
76#include <linux/proc_fs.h>
77#include <linux/time.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070078#include <linux/security.h>
79#include <linux/syscalls.h>
80#include <linux/audit.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080081#include <linux/capability.h>
Mike Waychison19b49462005-09-06 15:17:10 -070082#include <linux/seq_file.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080083#include <linux/mutex.h>
Kirill Korotaeve3893532006-10-02 02:18:22 -070084#include <linux/nsproxy.h>
Ingo Molnar5f921ae2006-03-26 01:37:17 -080085
Linus Torvalds1da177e2005-04-16 15:20:36 -070086#include <asm/uaccess.h>
87#include "util.h"
88
Kirill Korotaeve3893532006-10-02 02:18:22 -070089#define sem_ids(ns) (*((ns)->ids[IPC_SEM_IDS]))
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Kirill Korotaeve3893532006-10-02 02:18:22 -070091#define sem_lock(ns, id) ((struct sem_array*)ipc_lock(&sem_ids(ns), id))
92#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm)
93#define sem_rmid(ns, id) ((struct sem_array*)ipc_rmid(&sem_ids(ns), id))
94#define sem_checkid(ns, sma, semid) \
95 ipc_checkid(&sem_ids(ns),&sma->sem_perm,semid)
96#define sem_buildid(ns, id, seq) \
97 ipc_buildid(&sem_ids(ns), id, seq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
Kirill Korotaeve3893532006-10-02 02:18:22 -070099static struct ipc_ids init_sem_ids;
100
101static int newary(struct ipc_namespace *, key_t, int, int);
102static void freeary(struct ipc_namespace *ns, struct sem_array *sma, int id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -0700104static int sysvipc_sem_proc_show(struct seq_file *s, void *it);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105#endif
106
107#define SEMMSL_FAST 256 /* 512 bytes on stack */
108#define SEMOPM_FAST 64 /* ~ 372 bytes on stack */
109
110/*
111 * linked list protection:
112 * sem_undo.id_next,
113 * sem_array.sem_pending{,last},
114 * sem_array.sem_undo: sem_lock() for read/write
115 * sem_undo.proc_next: only "current" is allowed to read/write that field.
116 *
117 */
118
Kirill Korotaeve3893532006-10-02 02:18:22 -0700119#define sc_semmsl sem_ctls[0]
120#define sc_semmns sem_ctls[1]
121#define sc_semopm sem_ctls[2]
122#define sc_semmni sem_ctls[3]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123
Kirill Korotaeve3893532006-10-02 02:18:22 -0700124static void __ipc_init __sem_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
125{
126 ns->ids[IPC_SEM_IDS] = ids;
127 ns->sc_semmsl = SEMMSL;
128 ns->sc_semmns = SEMMNS;
129 ns->sc_semopm = SEMOPM;
130 ns->sc_semmni = SEMMNI;
131 ns->used_sems = 0;
132 ipc_init_ids(ids, ns->sc_semmni);
133}
134
135#ifdef CONFIG_IPC_NS
136int sem_init_ns(struct ipc_namespace *ns)
137{
138 struct ipc_ids *ids;
139
140 ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
141 if (ids == NULL)
142 return -ENOMEM;
143
144 __sem_init_ns(ns, ids);
145 return 0;
146}
147
148void sem_exit_ns(struct ipc_namespace *ns)
149{
150 int i;
151 struct sem_array *sma;
152
153 mutex_lock(&sem_ids(ns).mutex);
154 for (i = 0; i <= sem_ids(ns).max_id; i++) {
155 sma = sem_lock(ns, i);
156 if (sma == NULL)
157 continue;
158
159 freeary(ns, sma, i);
160 }
161 mutex_unlock(&sem_ids(ns).mutex);
162
Pavel Emelianovc7e12b82006-11-02 22:07:03 -0800163 ipc_fini_ids(ns->ids[IPC_SEM_IDS]);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700164 kfree(ns->ids[IPC_SEM_IDS]);
165 ns->ids[IPC_SEM_IDS] = NULL;
166}
167#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168
169void __init sem_init (void)
170{
Kirill Korotaeve3893532006-10-02 02:18:22 -0700171 __sem_init_ns(&init_ipc_ns, &init_sem_ids);
Mike Waychison19b49462005-09-06 15:17:10 -0700172 ipc_init_proc_interface("sysvipc/sem",
173 " key semid perms nsems uid gid cuid cgid otime ctime\n",
Kirill Korotaeve3893532006-10-02 02:18:22 -0700174 IPC_SEM_IDS, sysvipc_sem_proc_show);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175}
176
177/*
178 * Lockless wakeup algorithm:
179 * Without the check/retry algorithm a lockless wakeup is possible:
180 * - queue.status is initialized to -EINTR before blocking.
181 * - wakeup is performed by
182 * * unlinking the queue entry from sma->sem_pending
183 * * setting queue.status to IN_WAKEUP
184 * This is the notification for the blocked thread that a
185 * result value is imminent.
186 * * call wake_up_process
187 * * set queue.status to the final value.
188 * - the previously blocked thread checks queue.status:
189 * * if it's IN_WAKEUP, then it must wait until the value changes
190 * * if it's not -EINTR, then the operation was completed by
191 * update_queue. semtimedop can return queue.status without
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800192 * performing any operation on the sem array.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 * * otherwise it must acquire the spinlock and check what's up.
194 *
195 * The two-stage algorithm is necessary to protect against the following
196 * races:
197 * - if queue.status is set after wake_up_process, then the woken up idle
198 * thread could race forward and try (and fail) to acquire sma->lock
199 * before update_queue had a chance to set queue.status
200 * - if queue.status is written before wake_up_process and if the
201 * blocked process is woken up by a signal between writing
202 * queue.status and the wake_up_process, then the woken up
203 * process could return from semtimedop and die by calling
204 * sys_exit before wake_up_process is called. Then wake_up_process
205 * will oops, because the task structure is already invalid.
206 * (yes, this happened on s390 with sysv msg).
207 *
208 */
209#define IN_WAKEUP 1
210
Kirill Korotaeve3893532006-10-02 02:18:22 -0700211static int newary (struct ipc_namespace *ns, key_t key, int nsems, int semflg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212{
213 int id;
214 int retval;
215 struct sem_array *sma;
216 int size;
217
218 if (!nsems)
219 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700220 if (ns->used_sems + nsems > ns->sc_semmns)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 return -ENOSPC;
222
223 size = sizeof (*sma) + nsems * sizeof (struct sem);
224 sma = ipc_rcu_alloc(size);
225 if (!sma) {
226 return -ENOMEM;
227 }
228 memset (sma, 0, size);
229
230 sma->sem_perm.mode = (semflg & S_IRWXUGO);
231 sma->sem_perm.key = key;
232
233 sma->sem_perm.security = NULL;
234 retval = security_sem_alloc(sma);
235 if (retval) {
236 ipc_rcu_putref(sma);
237 return retval;
238 }
239
Kirill Korotaeve3893532006-10-02 02:18:22 -0700240 id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 if(id == -1) {
242 security_sem_free(sma);
243 ipc_rcu_putref(sma);
244 return -ENOSPC;
245 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700246 ns->used_sems += nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
Kirill Korotaeve3893532006-10-02 02:18:22 -0700248 sma->sem_id = sem_buildid(ns, id, sma->sem_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 sma->sem_base = (struct sem *) &sma[1];
250 /* sma->sem_pending = NULL; */
251 sma->sem_pending_last = &sma->sem_pending;
252 /* sma->undo = NULL; */
253 sma->sem_nsems = nsems;
254 sma->sem_ctime = get_seconds();
255 sem_unlock(sma);
256
Mike Waychison19b49462005-09-06 15:17:10 -0700257 return sma->sem_id;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258}
259
260asmlinkage long sys_semget (key_t key, int nsems, int semflg)
261{
262 int id, err = -EINVAL;
263 struct sem_array *sma;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700264 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
Kirill Korotaeve3893532006-10-02 02:18:22 -0700266 ns = current->nsproxy->ipc_ns;
267
268 if (nsems < 0 || nsems > ns->sc_semmsl)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700270 mutex_lock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
272 if (key == IPC_PRIVATE) {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700273 err = newary(ns, key, nsems, semflg);
274 } else if ((id = ipc_findkey(&sem_ids(ns), key)) == -1) { /* key not used */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 if (!(semflg & IPC_CREAT))
276 err = -ENOENT;
277 else
Kirill Korotaeve3893532006-10-02 02:18:22 -0700278 err = newary(ns, key, nsems, semflg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 } else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
280 err = -EEXIST;
281 } else {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700282 sma = sem_lock(ns, id);
Eric Sesterhenn27315c92006-03-26 18:28:38 +0200283 BUG_ON(sma==NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 if (nsems > sma->sem_nsems)
285 err = -EINVAL;
286 else if (ipcperms(&sma->sem_perm, semflg))
287 err = -EACCES;
288 else {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700289 int semid = sem_buildid(ns, id, sma->sem_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 err = security_sem_associate(sma, semflg);
291 if (!err)
292 err = semid;
293 }
294 sem_unlock(sma);
295 }
296
Kirill Korotaeve3893532006-10-02 02:18:22 -0700297 mutex_unlock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 return err;
299}
300
301/* Manage the doubly linked list sma->sem_pending as a FIFO:
302 * insert new queue elements at the tail sma->sem_pending_last.
303 */
304static inline void append_to_queue (struct sem_array * sma,
305 struct sem_queue * q)
306{
307 *(q->prev = sma->sem_pending_last) = q;
308 *(sma->sem_pending_last = &q->next) = NULL;
309}
310
311static inline void prepend_to_queue (struct sem_array * sma,
312 struct sem_queue * q)
313{
314 q->next = sma->sem_pending;
315 *(q->prev = &sma->sem_pending) = q;
316 if (q->next)
317 q->next->prev = &q->next;
318 else /* sma->sem_pending_last == &sma->sem_pending */
319 sma->sem_pending_last = &q->next;
320}
321
322static inline void remove_from_queue (struct sem_array * sma,
323 struct sem_queue * q)
324{
325 *(q->prev) = q->next;
326 if (q->next)
327 q->next->prev = q->prev;
328 else /* sma->sem_pending_last == &q->next */
329 sma->sem_pending_last = q->prev;
330 q->prev = NULL; /* mark as removed */
331}
332
333/*
334 * Determine whether a sequence of semaphore operations would succeed
335 * all at once. Return 0 if yes, 1 if need to sleep, else return error code.
336 */
337
338static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops,
339 int nsops, struct sem_undo *un, int pid)
340{
341 int result, sem_op;
342 struct sembuf *sop;
343 struct sem * curr;
344
345 for (sop = sops; sop < sops + nsops; sop++) {
346 curr = sma->sem_base + sop->sem_num;
347 sem_op = sop->sem_op;
348 result = curr->semval;
349
350 if (!sem_op && result)
351 goto would_block;
352
353 result += sem_op;
354 if (result < 0)
355 goto would_block;
356 if (result > SEMVMX)
357 goto out_of_range;
358 if (sop->sem_flg & SEM_UNDO) {
359 int undo = un->semadj[sop->sem_num] - sem_op;
360 /*
361 * Exceeding the undo range is an error.
362 */
363 if (undo < (-SEMAEM - 1) || undo > SEMAEM)
364 goto out_of_range;
365 }
366 curr->semval = result;
367 }
368
369 sop--;
370 while (sop >= sops) {
371 sma->sem_base[sop->sem_num].sempid = pid;
372 if (sop->sem_flg & SEM_UNDO)
373 un->semadj[sop->sem_num] -= sop->sem_op;
374 sop--;
375 }
376
377 sma->sem_otime = get_seconds();
378 return 0;
379
380out_of_range:
381 result = -ERANGE;
382 goto undo;
383
384would_block:
385 if (sop->sem_flg & IPC_NOWAIT)
386 result = -EAGAIN;
387 else
388 result = 1;
389
390undo:
391 sop--;
392 while (sop >= sops) {
393 sma->sem_base[sop->sem_num].semval -= sop->sem_op;
394 sop--;
395 }
396
397 return result;
398}
399
400/* Go through the pending queue for the indicated semaphore
401 * looking for tasks that can be completed.
402 */
403static void update_queue (struct sem_array * sma)
404{
405 int error;
406 struct sem_queue * q;
407
408 q = sma->sem_pending;
409 while(q) {
410 error = try_atomic_semop(sma, q->sops, q->nsops,
411 q->undo, q->pid);
412
413 /* Does q->sleeper still need to sleep? */
414 if (error <= 0) {
415 struct sem_queue *n;
416 remove_from_queue(sma,q);
417 q->status = IN_WAKEUP;
418 /*
419 * Continue scanning. The next operation
420 * that must be checked depends on the type of the
421 * completed operation:
422 * - if the operation modified the array, then
423 * restart from the head of the queue and
424 * check for threads that might be waiting
425 * for semaphore values to become 0.
426 * - if the operation didn't modify the array,
427 * then just continue.
428 */
429 if (q->alter)
430 n = sma->sem_pending;
431 else
432 n = q->next;
433 wake_up_process(q->sleeper);
434 /* hands-off: q will disappear immediately after
435 * writing q->status.
436 */
Linus Torvalds1224b372005-12-24 12:19:38 -0800437 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 q->status = error;
439 q = n;
440 } else {
441 q = q->next;
442 }
443 }
444}
445
446/* The following counts are associated to each semaphore:
447 * semncnt number of tasks waiting on semval being nonzero
448 * semzcnt number of tasks waiting on semval being zero
449 * This model assumes that a task waits on exactly one semaphore.
450 * Since semaphore operations are to be performed atomically, tasks actually
451 * wait on a whole sequence of semaphores simultaneously.
452 * The counts we return here are a rough approximation, but still
453 * warrant that semncnt+semzcnt>0 if the task is on the pending queue.
454 */
455static int count_semncnt (struct sem_array * sma, ushort semnum)
456{
457 int semncnt;
458 struct sem_queue * q;
459
460 semncnt = 0;
461 for (q = sma->sem_pending; q; q = q->next) {
462 struct sembuf * sops = q->sops;
463 int nsops = q->nsops;
464 int i;
465 for (i = 0; i < nsops; i++)
466 if (sops[i].sem_num == semnum
467 && (sops[i].sem_op < 0)
468 && !(sops[i].sem_flg & IPC_NOWAIT))
469 semncnt++;
470 }
471 return semncnt;
472}
473static int count_semzcnt (struct sem_array * sma, ushort semnum)
474{
475 int semzcnt;
476 struct sem_queue * q;
477
478 semzcnt = 0;
479 for (q = sma->sem_pending; q; q = q->next) {
480 struct sembuf * sops = q->sops;
481 int nsops = q->nsops;
482 int i;
483 for (i = 0; i < nsops; i++)
484 if (sops[i].sem_num == semnum
485 && (sops[i].sem_op == 0)
486 && !(sops[i].sem_flg & IPC_NOWAIT))
487 semzcnt++;
488 }
489 return semzcnt;
490}
491
Ingo Molnar5f921ae2006-03-26 01:37:17 -0800492/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
493 * the spinlock for this semaphore set hold. sem_ids.mutex remains locked
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494 * on exit.
495 */
Kirill Korotaeve3893532006-10-02 02:18:22 -0700496static void freeary (struct ipc_namespace *ns, struct sem_array *sma, int id)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497{
498 struct sem_undo *un;
499 struct sem_queue *q;
500 int size;
501
502 /* Invalidate the existing undo structures for this semaphore set.
503 * (They will be freed without any further action in exit_sem()
504 * or during the next semop.)
505 */
506 for (un = sma->undo; un; un = un->id_next)
507 un->semid = -1;
508
509 /* Wake up all pending processes and let them fail with EIDRM. */
510 q = sma->sem_pending;
511 while(q) {
512 struct sem_queue *n;
513 /* lazy remove_from_queue: we are killing the whole queue */
514 q->prev = NULL;
515 n = q->next;
516 q->status = IN_WAKEUP;
517 wake_up_process(q->sleeper); /* doesn't sleep */
Manfred Spraul6003a932005-12-23 23:57:41 +0100518 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 q->status = -EIDRM; /* hands-off q */
520 q = n;
521 }
522
523 /* Remove the semaphore set from the ID array*/
Kirill Korotaeve3893532006-10-02 02:18:22 -0700524 sma = sem_rmid(ns, id);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 sem_unlock(sma);
526
Kirill Korotaeve3893532006-10-02 02:18:22 -0700527 ns->used_sems -= sma->sem_nsems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528 size = sizeof (*sma) + sma->sem_nsems * sizeof (struct sem);
529 security_sem_free(sma);
530 ipc_rcu_putref(sma);
531}
532
533static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version)
534{
535 switch(version) {
536 case IPC_64:
537 return copy_to_user(buf, in, sizeof(*in));
538 case IPC_OLD:
539 {
540 struct semid_ds out;
541
542 ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm);
543
544 out.sem_otime = in->sem_otime;
545 out.sem_ctime = in->sem_ctime;
546 out.sem_nsems = in->sem_nsems;
547
548 return copy_to_user(buf, &out, sizeof(out));
549 }
550 default:
551 return -EINVAL;
552 }
553}
554
Kirill Korotaeve3893532006-10-02 02:18:22 -0700555static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
556 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557{
558 int err = -EINVAL;
559 struct sem_array *sma;
560
561 switch(cmd) {
562 case IPC_INFO:
563 case SEM_INFO:
564 {
565 struct seminfo seminfo;
566 int max_id;
567
568 err = security_sem_semctl(NULL, cmd);
569 if (err)
570 return err;
571
572 memset(&seminfo,0,sizeof(seminfo));
Kirill Korotaeve3893532006-10-02 02:18:22 -0700573 seminfo.semmni = ns->sc_semmni;
574 seminfo.semmns = ns->sc_semmns;
575 seminfo.semmsl = ns->sc_semmsl;
576 seminfo.semopm = ns->sc_semopm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 seminfo.semvmx = SEMVMX;
578 seminfo.semmnu = SEMMNU;
579 seminfo.semmap = SEMMAP;
580 seminfo.semume = SEMUME;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700581 mutex_lock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 if (cmd == SEM_INFO) {
Kirill Korotaeve3893532006-10-02 02:18:22 -0700583 seminfo.semusz = sem_ids(ns).in_use;
584 seminfo.semaem = ns->used_sems;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 } else {
586 seminfo.semusz = SEMUSZ;
587 seminfo.semaem = SEMAEM;
588 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700589 max_id = sem_ids(ns).max_id;
590 mutex_unlock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
592 return -EFAULT;
593 return (max_id < 0) ? 0: max_id;
594 }
595 case SEM_STAT:
596 {
597 struct semid64_ds tbuf;
598 int id;
599
Kirill Korotaeve3893532006-10-02 02:18:22 -0700600 if(semid >= sem_ids(ns).entries->size)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 return -EINVAL;
602
603 memset(&tbuf,0,sizeof(tbuf));
604
Kirill Korotaeve3893532006-10-02 02:18:22 -0700605 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 if(sma == NULL)
607 return -EINVAL;
608
609 err = -EACCES;
610 if (ipcperms (&sma->sem_perm, S_IRUGO))
611 goto out_unlock;
612
613 err = security_sem_semctl(sma, cmd);
614 if (err)
615 goto out_unlock;
616
Kirill Korotaeve3893532006-10-02 02:18:22 -0700617 id = sem_buildid(ns, semid, sma->sem_perm.seq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618
619 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
620 tbuf.sem_otime = sma->sem_otime;
621 tbuf.sem_ctime = sma->sem_ctime;
622 tbuf.sem_nsems = sma->sem_nsems;
623 sem_unlock(sma);
624 if (copy_semid_to_user (arg.buf, &tbuf, version))
625 return -EFAULT;
626 return id;
627 }
628 default:
629 return -EINVAL;
630 }
631 return err;
632out_unlock:
633 sem_unlock(sma);
634 return err;
635}
636
Kirill Korotaeve3893532006-10-02 02:18:22 -0700637static int semctl_main(struct ipc_namespace *ns, int semid, int semnum,
638 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639{
640 struct sem_array *sma;
641 struct sem* curr;
642 int err;
643 ushort fast_sem_io[SEMMSL_FAST];
644 ushort* sem_io = fast_sem_io;
645 int nsems;
646
Kirill Korotaeve3893532006-10-02 02:18:22 -0700647 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 if(sma==NULL)
649 return -EINVAL;
650
651 nsems = sma->sem_nsems;
652
653 err=-EIDRM;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700654 if (sem_checkid(ns,sma,semid))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 goto out_unlock;
656
657 err = -EACCES;
658 if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
659 goto out_unlock;
660
661 err = security_sem_semctl(sma, cmd);
662 if (err)
663 goto out_unlock;
664
665 err = -EACCES;
666 switch (cmd) {
667 case GETALL:
668 {
669 ushort __user *array = arg.array;
670 int i;
671
672 if(nsems > SEMMSL_FAST) {
673 ipc_rcu_getref(sma);
674 sem_unlock(sma);
675
676 sem_io = ipc_alloc(sizeof(ushort)*nsems);
677 if(sem_io == NULL) {
678 ipc_lock_by_ptr(&sma->sem_perm);
679 ipc_rcu_putref(sma);
680 sem_unlock(sma);
681 return -ENOMEM;
682 }
683
684 ipc_lock_by_ptr(&sma->sem_perm);
685 ipc_rcu_putref(sma);
686 if (sma->sem_perm.deleted) {
687 sem_unlock(sma);
688 err = -EIDRM;
689 goto out_free;
690 }
691 }
692
693 for (i = 0; i < sma->sem_nsems; i++)
694 sem_io[i] = sma->sem_base[i].semval;
695 sem_unlock(sma);
696 err = 0;
697 if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
698 err = -EFAULT;
699 goto out_free;
700 }
701 case SETALL:
702 {
703 int i;
704 struct sem_undo *un;
705
706 ipc_rcu_getref(sma);
707 sem_unlock(sma);
708
709 if(nsems > SEMMSL_FAST) {
710 sem_io = ipc_alloc(sizeof(ushort)*nsems);
711 if(sem_io == NULL) {
712 ipc_lock_by_ptr(&sma->sem_perm);
713 ipc_rcu_putref(sma);
714 sem_unlock(sma);
715 return -ENOMEM;
716 }
717 }
718
719 if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) {
720 ipc_lock_by_ptr(&sma->sem_perm);
721 ipc_rcu_putref(sma);
722 sem_unlock(sma);
723 err = -EFAULT;
724 goto out_free;
725 }
726
727 for (i = 0; i < nsems; i++) {
728 if (sem_io[i] > SEMVMX) {
729 ipc_lock_by_ptr(&sma->sem_perm);
730 ipc_rcu_putref(sma);
731 sem_unlock(sma);
732 err = -ERANGE;
733 goto out_free;
734 }
735 }
736 ipc_lock_by_ptr(&sma->sem_perm);
737 ipc_rcu_putref(sma);
738 if (sma->sem_perm.deleted) {
739 sem_unlock(sma);
740 err = -EIDRM;
741 goto out_free;
742 }
743
744 for (i = 0; i < nsems; i++)
745 sma->sem_base[i].semval = sem_io[i];
746 for (un = sma->undo; un; un = un->id_next)
747 for (i = 0; i < nsems; i++)
748 un->semadj[i] = 0;
749 sma->sem_ctime = get_seconds();
750 /* maybe some queued-up processes were waiting for this */
751 update_queue(sma);
752 err = 0;
753 goto out_unlock;
754 }
755 case IPC_STAT:
756 {
757 struct semid64_ds tbuf;
758 memset(&tbuf,0,sizeof(tbuf));
759 kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm);
760 tbuf.sem_otime = sma->sem_otime;
761 tbuf.sem_ctime = sma->sem_ctime;
762 tbuf.sem_nsems = sma->sem_nsems;
763 sem_unlock(sma);
764 if (copy_semid_to_user (arg.buf, &tbuf, version))
765 return -EFAULT;
766 return 0;
767 }
768 /* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */
769 }
770 err = -EINVAL;
771 if(semnum < 0 || semnum >= nsems)
772 goto out_unlock;
773
774 curr = &sma->sem_base[semnum];
775
776 switch (cmd) {
777 case GETVAL:
778 err = curr->semval;
779 goto out_unlock;
780 case GETPID:
781 err = curr->sempid;
782 goto out_unlock;
783 case GETNCNT:
784 err = count_semncnt(sma,semnum);
785 goto out_unlock;
786 case GETZCNT:
787 err = count_semzcnt(sma,semnum);
788 goto out_unlock;
789 case SETVAL:
790 {
791 int val = arg.val;
792 struct sem_undo *un;
793 err = -ERANGE;
794 if (val > SEMVMX || val < 0)
795 goto out_unlock;
796
797 for (un = sma->undo; un; un = un->id_next)
798 un->semadj[semnum] = 0;
799 curr->semval = val;
800 curr->sempid = current->tgid;
801 sma->sem_ctime = get_seconds();
802 /* maybe some queued-up processes were waiting for this */
803 update_queue(sma);
804 err = 0;
805 goto out_unlock;
806 }
807 }
808out_unlock:
809 sem_unlock(sma);
810out_free:
811 if(sem_io != fast_sem_io)
812 ipc_free(sem_io, sizeof(ushort)*nsems);
813 return err;
814}
815
816struct sem_setbuf {
817 uid_t uid;
818 gid_t gid;
819 mode_t mode;
820};
821
822static inline unsigned long copy_semid_from_user(struct sem_setbuf *out, void __user *buf, int version)
823{
824 switch(version) {
825 case IPC_64:
826 {
827 struct semid64_ds tbuf;
828
829 if(copy_from_user(&tbuf, buf, sizeof(tbuf)))
830 return -EFAULT;
831
832 out->uid = tbuf.sem_perm.uid;
833 out->gid = tbuf.sem_perm.gid;
834 out->mode = tbuf.sem_perm.mode;
835
836 return 0;
837 }
838 case IPC_OLD:
839 {
840 struct semid_ds tbuf_old;
841
842 if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
843 return -EFAULT;
844
845 out->uid = tbuf_old.sem_perm.uid;
846 out->gid = tbuf_old.sem_perm.gid;
847 out->mode = tbuf_old.sem_perm.mode;
848
849 return 0;
850 }
851 default:
852 return -EINVAL;
853 }
854}
855
Kirill Korotaeve3893532006-10-02 02:18:22 -0700856static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
857 int cmd, int version, union semun arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858{
859 struct sem_array *sma;
860 int err;
861 struct sem_setbuf setbuf;
862 struct kern_ipc_perm *ipcp;
863
864 if(cmd == IPC_SET) {
865 if(copy_semid_from_user (&setbuf, arg.buf, version))
866 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 }
Kirill Korotaeve3893532006-10-02 02:18:22 -0700868 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 if(sma==NULL)
870 return -EINVAL;
871
Kirill Korotaeve3893532006-10-02 02:18:22 -0700872 if (sem_checkid(ns,sma,semid)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 err=-EIDRM;
874 goto out_unlock;
875 }
876 ipcp = &sma->sem_perm;
Steve Grubb073115d2006-04-02 17:07:33 -0400877
878 err = audit_ipc_obj(ipcp);
879 if (err)
880 goto out_unlock;
881
Linda Knippersac032212006-05-16 22:03:48 -0400882 if (cmd == IPC_SET) {
883 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
884 if (err)
885 goto out_unlock;
886 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887 if (current->euid != ipcp->cuid &&
888 current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) {
889 err=-EPERM;
890 goto out_unlock;
891 }
892
893 err = security_sem_semctl(sma, cmd);
894 if (err)
895 goto out_unlock;
896
897 switch(cmd){
898 case IPC_RMID:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700899 freeary(ns, sma, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 err = 0;
901 break;
902 case IPC_SET:
903 ipcp->uid = setbuf.uid;
904 ipcp->gid = setbuf.gid;
905 ipcp->mode = (ipcp->mode & ~S_IRWXUGO)
906 | (setbuf.mode & S_IRWXUGO);
907 sma->sem_ctime = get_seconds();
908 sem_unlock(sma);
909 err = 0;
910 break;
911 default:
912 sem_unlock(sma);
913 err = -EINVAL;
914 break;
915 }
916 return err;
917
918out_unlock:
919 sem_unlock(sma);
920 return err;
921}
922
923asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
924{
925 int err = -EINVAL;
926 int version;
Kirill Korotaeve3893532006-10-02 02:18:22 -0700927 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928
929 if (semid < 0)
930 return -EINVAL;
931
932 version = ipc_parse_version(&cmd);
Kirill Korotaeve3893532006-10-02 02:18:22 -0700933 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934
935 switch(cmd) {
936 case IPC_INFO:
937 case SEM_INFO:
938 case SEM_STAT:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700939 err = semctl_nolock(ns,semid,semnum,cmd,version,arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940 return err;
941 case GETALL:
942 case GETVAL:
943 case GETPID:
944 case GETNCNT:
945 case GETZCNT:
946 case IPC_STAT:
947 case SETVAL:
948 case SETALL:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700949 err = semctl_main(ns,semid,semnum,cmd,version,arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700950 return err;
951 case IPC_RMID:
952 case IPC_SET:
Kirill Korotaeve3893532006-10-02 02:18:22 -0700953 mutex_lock(&sem_ids(ns).mutex);
954 err = semctl_down(ns,semid,semnum,cmd,version,arg);
955 mutex_unlock(&sem_ids(ns).mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700956 return err;
957 default:
958 return -EINVAL;
959 }
960}
961
962static inline void lock_semundo(void)
963{
964 struct sem_undo_list *undo_list;
965
966 undo_list = current->sysvsem.undo_list;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +0200967 if (undo_list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 spin_lock(&undo_list->lock);
969}
970
971/* This code has an interaction with copy_semundo().
972 * Consider; two tasks are sharing the undo_list. task1
973 * acquires the undo_list lock in lock_semundo(). If task2 now
974 * exits before task1 releases the lock (by calling
975 * unlock_semundo()), then task1 will never call spin_unlock().
976 * This leave the sem_undo_list in a locked state. If task1 now creats task3
977 * and once again shares the sem_undo_list, the sem_undo_list will still be
978 * locked, and future SEM_UNDO operations will deadlock. This case is
979 * dealt with in copy_semundo() by having it reinitialize the spin lock when
980 * the refcnt goes from 1 to 2.
981 */
982static inline void unlock_semundo(void)
983{
984 struct sem_undo_list *undo_list;
985
986 undo_list = current->sysvsem.undo_list;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +0200987 if (undo_list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 spin_unlock(&undo_list->lock);
989}
990
991
992/* If the task doesn't already have a undo_list, then allocate one
993 * here. We guarantee there is only one thread using this undo list,
994 * and current is THE ONE
995 *
996 * If this allocation and assignment succeeds, but later
997 * portions of this code fail, there is no need to free the sem_undo_list.
998 * Just let it stay associated with the task, and it'll be freed later
999 * at exit time.
1000 *
1001 * This can block, so callers must hold no locks.
1002 */
1003static inline int get_undo_list(struct sem_undo_list **undo_listp)
1004{
1005 struct sem_undo_list *undo_list;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
1007 undo_list = current->sysvsem.undo_list;
1008 if (!undo_list) {
Matt Helsley2453a302006-10-02 02:18:25 -07001009 undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 if (undo_list == NULL)
1011 return -ENOMEM;
Ingo Molnar00a5dfd2005-08-05 23:05:27 +02001012 spin_lock_init(&undo_list->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 atomic_set(&undo_list->refcnt, 1);
1014 current->sysvsem.undo_list = undo_list;
1015 }
1016 *undo_listp = undo_list;
1017 return 0;
1018}
1019
1020static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
1021{
1022 struct sem_undo **last, *un;
1023
1024 last = &ulp->proc_list;
1025 un = *last;
1026 while(un != NULL) {
1027 if(un->semid==semid)
1028 break;
1029 if(un->semid==-1) {
1030 *last=un->proc_next;
1031 kfree(un);
1032 } else {
1033 last=&un->proc_next;
1034 }
1035 un=*last;
1036 }
1037 return un;
1038}
1039
Kirill Korotaeve3893532006-10-02 02:18:22 -07001040static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041{
1042 struct sem_array *sma;
1043 struct sem_undo_list *ulp;
1044 struct sem_undo *un, *new;
1045 int nsems;
1046 int error;
1047
1048 error = get_undo_list(&ulp);
1049 if (error)
1050 return ERR_PTR(error);
1051
1052 lock_semundo();
1053 un = lookup_undo(ulp, semid);
1054 unlock_semundo();
1055 if (likely(un!=NULL))
1056 goto out;
1057
1058 /* no undo structure around - allocate one. */
Kirill Korotaeve3893532006-10-02 02:18:22 -07001059 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 un = ERR_PTR(-EINVAL);
1061 if(sma==NULL)
1062 goto out;
1063 un = ERR_PTR(-EIDRM);
Kirill Korotaeve3893532006-10-02 02:18:22 -07001064 if (sem_checkid(ns,sma,semid)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 sem_unlock(sma);
1066 goto out;
1067 }
1068 nsems = sma->sem_nsems;
1069 ipc_rcu_getref(sma);
1070 sem_unlock(sma);
1071
Burman Yan4668edc2006-12-06 20:38:51 -08001072 new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073 if (!new) {
1074 ipc_lock_by_ptr(&sma->sem_perm);
1075 ipc_rcu_putref(sma);
1076 sem_unlock(sma);
1077 return ERR_PTR(-ENOMEM);
1078 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 new->semadj = (short *) &new[1];
1080 new->semid = semid;
1081
1082 lock_semundo();
1083 un = lookup_undo(ulp, semid);
1084 if (un) {
1085 unlock_semundo();
1086 kfree(new);
1087 ipc_lock_by_ptr(&sma->sem_perm);
1088 ipc_rcu_putref(sma);
1089 sem_unlock(sma);
1090 goto out;
1091 }
1092 ipc_lock_by_ptr(&sma->sem_perm);
1093 ipc_rcu_putref(sma);
1094 if (sma->sem_perm.deleted) {
1095 sem_unlock(sma);
1096 unlock_semundo();
1097 kfree(new);
1098 un = ERR_PTR(-EIDRM);
1099 goto out;
1100 }
1101 new->proc_next = ulp->proc_list;
1102 ulp->proc_list = new;
1103 new->id_next = sma->undo;
1104 sma->undo = new;
1105 sem_unlock(sma);
1106 un = new;
1107 unlock_semundo();
1108out:
1109 return un;
1110}
1111
1112asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops,
1113 unsigned nsops, const struct timespec __user *timeout)
1114{
1115 int error = -EINVAL;
1116 struct sem_array *sma;
1117 struct sembuf fast_sops[SEMOPM_FAST];
1118 struct sembuf* sops = fast_sops, *sop;
1119 struct sem_undo *un;
Manfred Spraulb78755a2005-06-23 00:10:06 -07001120 int undos = 0, alter = 0, max;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 struct sem_queue queue;
1122 unsigned long jiffies_left = 0;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001123 struct ipc_namespace *ns;
1124
1125 ns = current->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126
1127 if (nsops < 1 || semid < 0)
1128 return -EINVAL;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001129 if (nsops > ns->sc_semopm)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 return -E2BIG;
1131 if(nsops > SEMOPM_FAST) {
1132 sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL);
1133 if(sops==NULL)
1134 return -ENOMEM;
1135 }
1136 if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) {
1137 error=-EFAULT;
1138 goto out_free;
1139 }
1140 if (timeout) {
1141 struct timespec _timeout;
1142 if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) {
1143 error = -EFAULT;
1144 goto out_free;
1145 }
1146 if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||
1147 _timeout.tv_nsec >= 1000000000L) {
1148 error = -EINVAL;
1149 goto out_free;
1150 }
1151 jiffies_left = timespec_to_jiffies(&_timeout);
1152 }
1153 max = 0;
1154 for (sop = sops; sop < sops + nsops; sop++) {
1155 if (sop->sem_num >= max)
1156 max = sop->sem_num;
1157 if (sop->sem_flg & SEM_UNDO)
Manfred Spraulb78755a2005-06-23 00:10:06 -07001158 undos = 1;
1159 if (sop->sem_op != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160 alter = 1;
1161 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162
1163retry_undos:
1164 if (undos) {
Kirill Korotaeve3893532006-10-02 02:18:22 -07001165 un = find_undo(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 if (IS_ERR(un)) {
1167 error = PTR_ERR(un);
1168 goto out_free;
1169 }
1170 } else
1171 un = NULL;
1172
Kirill Korotaeve3893532006-10-02 02:18:22 -07001173 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 error=-EINVAL;
1175 if(sma==NULL)
1176 goto out_free;
1177 error = -EIDRM;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001178 if (sem_checkid(ns,sma,semid))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 goto out_unlock_free;
1180 /*
1181 * semid identifies are not unique - find_undo may have
1182 * allocated an undo structure, it was invalidated by an RMID
1183 * and now a new array with received the same id. Check and retry.
1184 */
1185 if (un && un->semid == -1) {
1186 sem_unlock(sma);
1187 goto retry_undos;
1188 }
1189 error = -EFBIG;
1190 if (max >= sma->sem_nsems)
1191 goto out_unlock_free;
1192
1193 error = -EACCES;
1194 if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
1195 goto out_unlock_free;
1196
1197 error = security_sem_semop(sma, sops, nsops, alter);
1198 if (error)
1199 goto out_unlock_free;
1200
1201 error = try_atomic_semop (sma, sops, nsops, un, current->tgid);
1202 if (error <= 0) {
1203 if (alter && error == 0)
1204 update_queue (sma);
1205 goto out_unlock_free;
1206 }
1207
1208 /* We need to sleep on this operation, so we put the current
1209 * task into the pending queue and go to sleep.
1210 */
1211
1212 queue.sma = sma;
1213 queue.sops = sops;
1214 queue.nsops = nsops;
1215 queue.undo = un;
1216 queue.pid = current->tgid;
1217 queue.id = semid;
1218 queue.alter = alter;
1219 if (alter)
1220 append_to_queue(sma ,&queue);
1221 else
1222 prepend_to_queue(sma ,&queue);
1223
1224 queue.status = -EINTR;
1225 queue.sleeper = current;
1226 current->state = TASK_INTERRUPTIBLE;
1227 sem_unlock(sma);
1228
1229 if (timeout)
1230 jiffies_left = schedule_timeout(jiffies_left);
1231 else
1232 schedule();
1233
1234 error = queue.status;
1235 while(unlikely(error == IN_WAKEUP)) {
1236 cpu_relax();
1237 error = queue.status;
1238 }
1239
1240 if (error != -EINTR) {
1241 /* fast path: update_queue already obtained all requested
1242 * resources */
1243 goto out_free;
1244 }
1245
Kirill Korotaeve3893532006-10-02 02:18:22 -07001246 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 if(sma==NULL) {
Eric Sesterhenn27315c92006-03-26 18:28:38 +02001248 BUG_ON(queue.prev != NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249 error = -EIDRM;
1250 goto out_free;
1251 }
1252
1253 /*
1254 * If queue.status != -EINTR we are woken up by another process
1255 */
1256 error = queue.status;
1257 if (error != -EINTR) {
1258 goto out_unlock_free;
1259 }
1260
1261 /*
1262 * If an interrupt occurred we have to clean up the queue
1263 */
1264 if (timeout && jiffies_left == 0)
1265 error = -EAGAIN;
1266 remove_from_queue(sma,&queue);
1267 goto out_unlock_free;
1268
1269out_unlock_free:
1270 sem_unlock(sma);
1271out_free:
1272 if(sops != fast_sops)
1273 kfree(sops);
1274 return error;
1275}
1276
1277asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsops)
1278{
1279 return sys_semtimedop(semid, tsops, nsops, NULL);
1280}
1281
1282/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between
1283 * parent and child tasks.
1284 *
1285 * See the notes above unlock_semundo() regarding the spin_lock_init()
1286 * in this code. Initialize the undo_list->lock here instead of get_undo_list()
1287 * because of the reasoning in the comment above unlock_semundo.
1288 */
1289
1290int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
1291{
1292 struct sem_undo_list *undo_list;
1293 int error;
1294
1295 if (clone_flags & CLONE_SYSVSEM) {
1296 error = get_undo_list(&undo_list);
1297 if (error)
1298 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 atomic_inc(&undo_list->refcnt);
1300 tsk->sysvsem.undo_list = undo_list;
1301 } else
1302 tsk->sysvsem.undo_list = NULL;
1303
1304 return 0;
1305}
1306
1307/*
1308 * add semadj values to semaphores, free undo structures.
1309 * undo structures are not freed when semaphore arrays are destroyed
1310 * so some of them may be out of date.
1311 * IMPLEMENTATION NOTE: There is some confusion over whether the
1312 * set of adjustments that needs to be done should be done in an atomic
1313 * manner or not. That is, if we are attempting to decrement the semval
1314 * should we queue up and wait until we can do so legally?
1315 * The original implementation attempted to do this (queue and wait).
1316 * The current implementation does not do so. The POSIX standard
1317 * and SVID should be consulted to determine what behavior is mandated.
1318 */
1319void exit_sem(struct task_struct *tsk)
1320{
1321 struct sem_undo_list *undo_list;
1322 struct sem_undo *u, **up;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001323 struct ipc_namespace *ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324
1325 undo_list = tsk->sysvsem.undo_list;
1326 if (!undo_list)
1327 return;
1328
1329 if (!atomic_dec_and_test(&undo_list->refcnt))
1330 return;
1331
Kirill Korotaeve3893532006-10-02 02:18:22 -07001332 ns = tsk->nsproxy->ipc_ns;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 /* There's no need to hold the semundo list lock, as current
1334 * is the last task exiting for this undo list.
1335 */
1336 for (up = &undo_list->proc_list; (u = *up); *up = u->proc_next, kfree(u)) {
1337 struct sem_array *sma;
1338 int nsems, i;
1339 struct sem_undo *un, **unp;
1340 int semid;
1341
1342 semid = u->semid;
1343
1344 if(semid == -1)
1345 continue;
Kirill Korotaeve3893532006-10-02 02:18:22 -07001346 sma = sem_lock(ns, semid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 if (sma == NULL)
1348 continue;
1349
1350 if (u->semid == -1)
1351 goto next_entry;
1352
Kirill Korotaeve3893532006-10-02 02:18:22 -07001353 BUG_ON(sem_checkid(ns,sma,u->semid));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354
1355 /* remove u from the sma->undo list */
1356 for (unp = &sma->undo; (un = *unp); unp = &un->id_next) {
1357 if (u == un)
1358 goto found;
1359 }
1360 printk ("exit_sem undo list error id=%d\n", u->semid);
1361 goto next_entry;
1362found:
1363 *unp = un->id_next;
1364 /* perform adjustments registered in u */
1365 nsems = sma->sem_nsems;
1366 for (i = 0; i < nsems; i++) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001367 struct sem * semaphore = &sma->sem_base[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 if (u->semadj[i]) {
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001369 semaphore->semval += u->semadj[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 /*
1371 * Range checks of the new semaphore value,
1372 * not defined by sus:
1373 * - Some unices ignore the undo entirely
1374 * (e.g. HP UX 11i 11.22, Tru64 V5.1)
1375 * - some cap the value (e.g. FreeBSD caps
1376 * at 0, but doesn't enforce SEMVMX)
1377 *
1378 * Linux caps the semaphore value, both at 0
1379 * and at SEMVMX.
1380 *
1381 * Manfred <manfred@colorfullife.com>
1382 */
Ingo Molnar5f921ae2006-03-26 01:37:17 -08001383 if (semaphore->semval < 0)
1384 semaphore->semval = 0;
1385 if (semaphore->semval > SEMVMX)
1386 semaphore->semval = SEMVMX;
1387 semaphore->sempid = current->tgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 }
1389 }
1390 sma->sem_otime = get_seconds();
1391 /* maybe some queued-up processes were waiting for this */
1392 update_queue(sma);
1393next_entry:
1394 sem_unlock(sma);
1395 }
1396 kfree(undo_list);
1397}
1398
1399#ifdef CONFIG_PROC_FS
Mike Waychison19b49462005-09-06 15:17:10 -07001400static int sysvipc_sem_proc_show(struct seq_file *s, void *it)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401{
Mike Waychison19b49462005-09-06 15:17:10 -07001402 struct sem_array *sma = it;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
Mike Waychison19b49462005-09-06 15:17:10 -07001404 return seq_printf(s,
1405 "%10d %10d %4o %10lu %5u %5u %5u %5u %10lu %10lu\n",
1406 sma->sem_perm.key,
1407 sma->sem_id,
1408 sma->sem_perm.mode,
1409 sma->sem_nsems,
1410 sma->sem_perm.uid,
1411 sma->sem_perm.gid,
1412 sma->sem_perm.cuid,
1413 sma->sem_perm.cgid,
1414 sma->sem_otime,
1415 sma->sem_ctime);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416}
1417#endif