1 /*
2 * linux/ipc/shm.c
3 * Copyright (C) 1992, 1993 Krishna Balasubramanian
4 * Many improvements/fixes by Bruno Haible.
5 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
7 *
8 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9 * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11 * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
15 *
16 */
17
18 #include <linux/config.h>
19 #include <linux/slab.h>
20 #include <linux/mm.h>
21 #include <linux/hugetlb.h>
22 #include <linux/shm.h>
23 #include <linux/init.h>
24 #include <linux/file.h>
25 #include <linux/mman.h>
26 #include <linux/proc_fs.h>
27 #include <linux/shmem_fs.h>
28 #include <linux/security.h>
29 #include <linux/syscalls.h>
30 #include <asm/uaccess.h>
31
32 #include "util.h"
33
34 #define shm_flags shm_perm.mode
35
36 static struct file_operations shm_file_operations;
37 static struct vm_operations_struct shm_vm_ops;
38
39 static struct ipc_ids shm_ids;
40
41 #define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
42 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
43 #define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id))
44 #define shm_buildid(id, seq) \
45 ipc_buildid(&shm_ids, id, seq)
46
47 static int newseg (key_t key, int shmflg, size_t size);
48 static void shm_open (struct vm_area_struct *shmd);
49 static void shm_close (struct vm_area_struct *shmd);
50 #ifdef CONFIG_PROC_FS
51 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
52 #endif
53
54 size_t shm_ctlmax = SHMMAX;
55 size_t shm_ctlall = SHMALL;
56 int shm_ctlmni = SHMMNI;
57
58 static int shm_tot; /* total number of shared memory pages */
59
60 void __init shm_init (void)
61 {
62 ipc_init_ids(&shm_ids, 1);
63 #ifdef CONFIG_PROC_FS
64 create_proc_read_entry("sysvipc/shm", 0, NULL, sysvipc_shm_read_proc, NULL);
65 #endif
66 }
67
68 static inline int shm_checkid(struct shmid_kernel *s, int id)
69 {
70 if (ipc_checkid(&shm_ids,&s->shm_perm,id))
71 return -EIDRM;
72 return 0;
73 }
74
75 static inline struct shmid_kernel *shm_rmid(int id)
76 {
77 return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
78 }
79
80 static inline int shm_addid(struct shmid_kernel *shp)
81 {
82 return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
83 }
84
85
86
87 static inline void shm_inc (int id) {
88 struct shmid_kernel *shp;
89
90 if(!(shp = shm_lock(id)))
91 BUG();
92 shp->shm_atim = get_seconds();
93 shp->shm_lprid = current->tgid;
94 shp->shm_nattch++;
95 shm_unlock(shp);
96 }
97
98 /* This is called by fork, once for every shm attach. */
99 static void shm_open (struct vm_area_struct *shmd)
100 {
101 shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
102 }
103
104 /*
105 * shm_destroy - free the struct shmid_kernel
106 *
107 * @shp: struct to free
108 *
109 * It has to be called with shp and shm_ids.sem locked,
110 * but returns with shp unlocked and freed.
111 */
112 static void shm_destroy (struct shmid_kernel *shp)
113 {
114 shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
115 shm_rmid (shp->id);
116 shm_unlock(shp);
117 if (!is_file_hugepages(shp->shm_file))
118 shmem_lock(shp->shm_file, 0, shp->mlock_user);
119 else
120 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
121 shp->mlock_user);
122 fput (shp->shm_file);
123 security_shm_free(shp);
124 ipc_rcu_putref(shp);
125 }
126
127 /*
128 * remove the attach descriptor shmd.
129 * free memory for segment if it is marked destroyed.
130 * The descriptor has already been removed from the current->mm->mmap list
131 * and will later be kfree()d.
132 */
133 static void shm_close (struct vm_area_struct *shmd)
134 {
135 struct file * file = shmd->vm_file;
136 int id = file->f_dentry->d_inode->i_ino;
137 struct shmid_kernel *shp;
138
139 down (&shm_ids.sem);
140 /* remove from the list of attaches of the shm segment */
141 if(!(shp = shm_lock(id)))
142 BUG();
143 shp->shm_lprid = current->tgid;
144 shp->shm_dtim = get_seconds();
145 shp->shm_nattch--;
146 if(shp->shm_nattch == 0 &&
147 shp->shm_flags & SHM_DEST)
148 shm_destroy (shp);
149 else
150 shm_unlock(shp);
151 up (&shm_ids.sem);
152 }
153
154 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
155 {
156 file_accessed(file);
157 vma->vm_ops = &shm_vm_ops;
158 shm_inc(file->f_dentry->d_inode->i_ino);
159 return 0;
160 }
161
162 static struct file_operations shm_file_operations = {
163 .mmap = shm_mmap
164 };
165
166 static struct vm_operations_struct shm_vm_ops = {
167 .open = shm_open, /* callback for a new vm-area open */
168 .close = shm_close, /* callback for when the vm-area is released */
169 .nopage = shmem_nopage,
170 #ifdef CONFIG_NUMA
171 .set_policy = shmem_set_policy,
172 .get_policy = shmem_get_policy,
173 #endif
174 };
175
176 static int newseg (key_t key, int shmflg, size_t size)
177 {
178 int error;
179 struct shmid_kernel *shp;
180 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
181 struct file * file;
182 char name[13];
183 int id;
184
185 if (size < SHMMIN || size > shm_ctlmax)
186 return -EINVAL;
187
188 if (shm_tot + numpages >= shm_ctlall)
189 return -ENOSPC;
190
191 shp = ipc_rcu_alloc(sizeof(*shp));
192 if (!shp)
193 return -ENOMEM;
194
195 shp->shm_perm.key = key;
196 shp->shm_flags = (shmflg & S_IRWXUGO);
197 shp->mlock_user = NULL;
198
199 shp->shm_perm.security = NULL;
200 error = security_shm_alloc(shp);
201 if (error) {
202 ipc_rcu_putref(shp);
203 return error;
204 }
205
206 if (shmflg & SHM_HUGETLB) {
207 /* hugetlb_zero_setup takes care of mlock user accounting */
208 file = hugetlb_zero_setup(size);
209 shp->mlock_user = current->user;
210 } else {
211 sprintf (name, "SYSV%08x", key);
212 file = shmem_file_setup(name, size, VM_ACCOUNT);
213 }
214 error = PTR_ERR(file);
215 if (IS_ERR(file))
216 goto no_file;
217
218 error = -ENOSPC;
219 id = shm_addid(shp);
220 if(id == -1)
221 goto no_id;
222
223 shp->shm_cprid = current->tgid;
224 shp->shm_lprid = 0;
225 shp->shm_atim = shp->shm_dtim = 0;
226 shp->shm_ctim = get_seconds();
227 shp->shm_segsz = size;
228 shp->shm_nattch = 0;
229 shp->id = shm_buildid(id,shp->shm_perm.seq);
230 shp->shm_file = file;
231 file->f_dentry->d_inode->i_ino = shp->id;
232 if (shmflg & SHM_HUGETLB)
233 set_file_hugepages(file);
234 else
235 file->f_op = &shm_file_operations;
236 shm_tot += numpages;
237 shm_unlock(shp);
238 return shp->id;
239
240 no_id:
241 fput(file);
242 no_file:
243 security_shm_free(shp);
244 ipc_rcu_putref(shp);
245 return error;
246 }
247
248 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
249 {
250 struct shmid_kernel *shp;
251 int err, id = 0;
252
253 down(&shm_ids.sem);
254 if (key == IPC_PRIVATE) {
255 err = newseg(key, shmflg, size);
256 } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
257 if (!(shmflg & IPC_CREAT))
258 err = -ENOENT;
259 else
260 err = newseg(key, shmflg, size);
261 } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
262 err = -EEXIST;
263 } else {
264 shp = shm_lock(id);
265 if(shp==NULL)
266 BUG();
267 if (shp->shm_segsz < size)
268 err = -EINVAL;
269 else if (ipcperms(&shp->shm_perm, shmflg))
270 err = -EACCES;
271 else {
272 int shmid = shm_buildid(id, shp->shm_perm.seq);
273 err = security_shm_associate(shp, shmflg);
274 if (!err)
275 err = shmid;
276 }
277 shm_unlock(shp);
278 }
279 up(&shm_ids.sem);
280
281 return err;
282 }
283
284 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
285 {
286 switch(version) {
287 case IPC_64:
288 return copy_to_user(buf, in, sizeof(*in));
289 case IPC_OLD:
290 {
291 struct shmid_ds out;
292
293 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
294 out.shm_segsz = in->shm_segsz;
295 out.shm_atime = in->shm_atime;
296 out.shm_dtime = in->shm_dtime;
297 out.shm_ctime = in->shm_ctime;
298 out.shm_cpid = in->shm_cpid;
299 out.shm_lpid = in->shm_lpid;
300 out.shm_nattch = in->shm_nattch;
301
302 return copy_to_user(buf, &out, sizeof(out));
303 }
304 default:
305 return -EINVAL;
306 }
307 }
308
309 struct shm_setbuf {
310 uid_t uid;
311 gid_t gid;
312 mode_t mode;
313 };
314
315 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
316 {
317 switch(version) {
318 case IPC_64:
319 {
320 struct shmid64_ds tbuf;
321
322 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
323 return -EFAULT;
324
325 out->uid = tbuf.shm_perm.uid;
326 out->gid = tbuf.shm_perm.gid;
327 out->mode = tbuf.shm_flags;
328
329 return 0;
330 }
331 case IPC_OLD:
332 {
333 struct shmid_ds tbuf_old;
334
335 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
336 return -EFAULT;
337
338 out->uid = tbuf_old.shm_perm.uid;
339 out->gid = tbuf_old.shm_perm.gid;
340 out->mode = tbuf_old.shm_flags;
341
342 return 0;
343 }
344 default:
345 return -EINVAL;
346 }
347 }
348
349 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
350 {
351 switch(version) {
352 case IPC_64:
353 return copy_to_user(buf, in, sizeof(*in));
354 case IPC_OLD:
355 {
356 struct shminfo out;
357
358 if(in->shmmax > INT_MAX)
359 out.shmmax = INT_MAX;
360 else
361 out.shmmax = (int)in->shmmax;
362
363 out.shmmin = in->shmmin;
364 out.shmmni = in->shmmni;
365 out.shmseg = in->shmseg;
366 out.shmall = in->shmall;
367
368 return copy_to_user(buf, &out, sizeof(out));
369 }
370 default:
371 return -EINVAL;
372 }
373 }
374
375 static void shm_get_stat(unsigned long *rss, unsigned long *swp)
376 {
377 int i;
378
379 *rss = 0;
380 *swp = 0;
381
382 for (i = 0; i <= shm_ids.max_id; i++) {
383 struct shmid_kernel *shp;
384 struct inode *inode;
385
386 shp = shm_get(i);
387 if(!shp)
388 continue;
389
390 inode = shp->shm_file->f_dentry->d_inode;
391
392 if (is_file_hugepages(shp->shm_file)) {
393 struct address_space *mapping = inode->i_mapping;
394 *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
395 } else {
396 struct shmem_inode_info *info = SHMEM_I(inode);
397 spin_lock(&info->lock);
398 *rss += inode->i_mapping->nrpages;
399 *swp += info->swapped;
400 spin_unlock(&info->lock);
401 }
402 }
403 }
404
405 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
406 {
407 struct shm_setbuf setbuf;
408 struct shmid_kernel *shp;
409 int err, version;
410
411 if (cmd < 0 || shmid < 0) {
412 err = -EINVAL;
413 goto out;
414 }
415
416 version = ipc_parse_version(&cmd);
417
418 switch (cmd) { /* replace with proc interface ? */
419 case IPC_INFO:
420 {
421 struct shminfo64 shminfo;
422
423 err = security_shm_shmctl(NULL, cmd);
424 if (err)
425 return err;
426
427 memset(&shminfo,0,sizeof(shminfo));
428 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
429 shminfo.shmmax = shm_ctlmax;
430 shminfo.shmall = shm_ctlall;
431
432 shminfo.shmmin = SHMMIN;
433 if(copy_shminfo_to_user (buf, &shminfo, version))
434 return -EFAULT;
435 /* reading a integer is always atomic */
436 err= shm_ids.max_id;
437 if(err<0)
438 err = 0;
439 goto out;
440 }
441 case SHM_INFO:
442 {
443 struct shm_info shm_info;
444
445 err = security_shm_shmctl(NULL, cmd);
446 if (err)
447 return err;
448
449 memset(&shm_info,0,sizeof(shm_info));
450 down(&shm_ids.sem);
451 shm_info.used_ids = shm_ids.in_use;
452 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
453 shm_info.shm_tot = shm_tot;
454 shm_info.swap_attempts = 0;
455 shm_info.swap_successes = 0;
456 err = shm_ids.max_id;
457 up(&shm_ids.sem);
458 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
459 err = -EFAULT;
460 goto out;
461 }
462
463 err = err < 0 ? 0 : err;
464 goto out;
465 }
466 case SHM_STAT:
467 case IPC_STAT:
468 {
469 struct shmid64_ds tbuf;
470 int result;
471 memset(&tbuf, 0, sizeof(tbuf));
472 shp = shm_lock(shmid);
473 if(shp==NULL) {
474 err = -EINVAL;
475 goto out;
476 } else if(cmd==SHM_STAT) {
477 err = -EINVAL;
478 if (shmid > shm_ids.max_id)
479 goto out_unlock;
480 result = shm_buildid(shmid, shp->shm_perm.seq);
481 } else {
482 err = shm_checkid(shp,shmid);
483 if(err)
484 goto out_unlock;
485 result = 0;
486 }
487 err=-EACCES;
488 if (ipcperms (&shp->shm_perm, S_IRUGO))
489 goto out_unlock;
490 err = security_shm_shmctl(shp, cmd);
491 if (err)
492 goto out_unlock;
493 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
494 tbuf.shm_segsz = shp->shm_segsz;
495 tbuf.shm_atime = shp->shm_atim;
496 tbuf.shm_dtime = shp->shm_dtim;
497 tbuf.shm_ctime = shp->shm_ctim;
498 tbuf.shm_cpid = shp->shm_cprid;
499 tbuf.shm_lpid = shp->shm_lprid;
500 if (!is_file_hugepages(shp->shm_file))
501 tbuf.shm_nattch = shp->shm_nattch;
502 else
503 tbuf.shm_nattch = file_count(shp->shm_file) - 1;
504 shm_unlock(shp);
505 if(copy_shmid_to_user (buf, &tbuf, version))
506 err = -EFAULT;
507 else
508 err = result;
509 goto out;
510 }
511 case SHM_LOCK:
512 case SHM_UNLOCK:
513 {
514 shp = shm_lock(shmid);
515 if(shp==NULL) {
516 err = -EINVAL;
517 goto out;
518 }
519 err = shm_checkid(shp,shmid);
520 if(err)
521 goto out_unlock;
522
523 if (!capable(CAP_IPC_LOCK)) {
524 err = -EPERM;
525 if (current->euid != shp->shm_perm.uid &&
526 current->euid != shp->shm_perm.cuid)
527 goto out_unlock;
528 if (cmd == SHM_LOCK &&
529 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
530 goto out_unlock;
531 }
532
533 err = security_shm_shmctl(shp, cmd);
534 if (err)
535 goto out_unlock;
536
537 if(cmd==SHM_LOCK) {
538 struct user_struct * user = current->user;
539 if (!is_file_hugepages(shp->shm_file)) {
540 err = shmem_lock(shp->shm_file, 1, user);
541 if (!err) {
542 shp->shm_flags |= SHM_LOCKED;
543 shp->mlock_user = user;
544 }
545 }
546 } else if (!is_file_hugepages(shp->shm_file)) {
547 shmem_lock(shp->shm_file, 0, shp->mlock_user);
548 shp->shm_flags &= ~SHM_LOCKED;
549 shp->mlock_user = NULL;
550 }
551 shm_unlock(shp);
552 goto out;
553 }
554 case IPC_RMID:
555 {
556 /*
557 * We cannot simply remove the file. The SVID states
558 * that the block remains until the last person
559 * detaches from it, then is deleted. A shmat() on
560 * an RMID segment is legal in older Linux and if
561 * we change it apps break...
562 *
563 * Instead we set a destroyed flag, and then blow
564 * the name away when the usage hits zero.
565 */
566 down(&shm_ids.sem);
567 shp = shm_lock(shmid);
568 err = -EINVAL;
569 if (shp == NULL)
570 goto out_up;
571 err = shm_checkid(shp, shmid);
572 if(err)
573 goto out_unlock_up;
574
575 if (current->euid != shp->shm_perm.uid &&
576 current->euid != shp->shm_perm.cuid &&
577 !capable(CAP_SYS_ADMIN)) {
578 err=-EPERM;
579 goto out_unlock_up;
580 }
581
582 err = security_shm_shmctl(shp, cmd);
583 if (err)
584 goto out_unlock_up;
585
586 if (shp->shm_nattch){
587 shp->shm_flags |= SHM_DEST;
588 /* Do not find it any more */
589 shp->shm_perm.key = IPC_PRIVATE;
590 shm_unlock(shp);
591 } else
592 shm_destroy (shp);
593 up(&shm_ids.sem);
594 goto out;
595 }
596
597 case IPC_SET:
598 {
599 if (copy_shmid_from_user (&setbuf, buf, version)) {
600 err = -EFAULT;
601 goto out;
602 }
603 down(&shm_ids.sem);
604 shp = shm_lock(shmid);
605 err=-EINVAL;
606 if(shp==NULL)
607 goto out_up;
608 err = shm_checkid(shp,shmid);
609 if(err)
610 goto out_unlock_up;
611 err=-EPERM;
612 if (current->euid != shp->shm_perm.uid &&
613 current->euid != shp->shm_perm.cuid &&
614 !capable(CAP_SYS_ADMIN)) {
615 goto out_unlock_up;
616 }
617
618 err = security_shm_shmctl(shp, cmd);
619 if (err)
620 goto out_unlock_up;
621
622 shp->shm_perm.uid = setbuf.uid;
623 shp->shm_perm.gid = setbuf.gid;
624 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
625 | (setbuf.mode & S_IRWXUGO);
626 shp->shm_ctim = get_seconds();
627 break;
628 }
629
630 default:
631 err = -EINVAL;
632 goto out;
633 }
634
635 err = 0;
636 out_unlock_up:
637 shm_unlock(shp);
638 out_up:
639 up(&shm_ids.sem);
640 goto out;
641 out_unlock:
642 shm_unlock(shp);
643 out:
644 return err;
645 }
646
647 /*
648 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
649 *
650 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
651 * "raddr" thing points to kernel space, and there has to be a wrapper around
652 * this.
653 */
654 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
655 {
656 struct shmid_kernel *shp;
657 unsigned long addr;
658 unsigned long size;
659 struct file * file;
660 int err;
661 unsigned long flags;
662 unsigned long prot;
663 unsigned long o_flags;
664 int acc_mode;
665 void *user_addr;
666
667 if (shmid < 0) {
668 err = -EINVAL;
669 goto out;
670 } else if ((addr = (ulong)shmaddr)) {
671 if (addr & (SHMLBA-1)) {
672 if (shmflg & SHM_RND)
673 addr &= ~(SHMLBA-1); /* round down */
674 else
675 #ifndef __ARCH_FORCE_SHMLBA
676 if (addr & ~PAGE_MASK)
677 #endif
678 return -EINVAL;
679 }
680 flags = MAP_SHARED | MAP_FIXED;
681 } else {
682 if ((shmflg & SHM_REMAP))
683 return -EINVAL;
684
685 flags = MAP_SHARED;
686 }
687
688 if (shmflg & SHM_RDONLY) {
689 prot = PROT_READ;
690 o_flags = O_RDONLY;
691 acc_mode = S_IRUGO;
692 } else {
693 prot = PROT_READ | PROT_WRITE;
694 o_flags = O_RDWR;
695 acc_mode = S_IRUGO | S_IWUGO;
696 }
697 if (shmflg & SHM_EXEC) {
698 prot |= PROT_EXEC;
699 acc_mode |= S_IXUGO;
700 }
701
702 /*
703 * We cannot rely on the fs check since SYSV IPC does have an
704 * additional creator id...
705 */
706 shp = shm_lock(shmid);
707 if(shp == NULL) {
708 err = -EINVAL;
709 goto out;
710 }
711 err = shm_checkid(shp,shmid);
712 if (err) {
713 shm_unlock(shp);
714 goto out;
715 }
716 if (ipcperms(&shp->shm_perm, acc_mode)) {
717 shm_unlock(shp);
718 err = -EACCES;
719 goto out;
720 }
721
722 err = security_shm_shmat(shp, shmaddr, shmflg);
723 if (err) {
724 shm_unlock(shp);
725 return err;
726 }
727
728 file = shp->shm_file;
729 size = i_size_read(file->f_dentry->d_inode);
730 shp->shm_nattch++;
731 shm_unlock(shp);
732
733 down_write(¤t->mm->mmap_sem);
734 if (addr && !(shmflg & SHM_REMAP)) {
735 user_addr = ERR_PTR(-EINVAL);
736 if (find_vma_intersection(current->mm, addr, addr + size))
737 goto invalid;
738 /*
739 * If shm segment goes below stack, make sure there is some
740 * space left for the stack to grow (at least 4 pages).
741 */
742 if (addr < current->mm->start_stack &&
743 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
744 goto invalid;
745 }
746
747 user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
748
749 invalid:
750 up_write(¤t->mm->mmap_sem);
751
752 down (&shm_ids.sem);
753 if(!(shp = shm_lock(shmid)))
754 BUG();
755 shp->shm_nattch--;
756 if(shp->shm_nattch == 0 &&
757 shp->shm_flags & SHM_DEST)
758 shm_destroy (shp);
759 else
760 shm_unlock(shp);
761 up (&shm_ids.sem);
762
763 *raddr = (unsigned long) user_addr;
764 err = 0;
765 if (IS_ERR(user_addr))
766 err = PTR_ERR(user_addr);
767 out:
768 return err;
769 }
770
771 /*
772 * detach and kill segment if marked destroyed.
773 * The work is done in shm_close.
774 */
775 asmlinkage long sys_shmdt(char __user *shmaddr)
776 {
777 struct mm_struct *mm = current->mm;
778 struct vm_area_struct *vma, *next;
779 unsigned long addr = (unsigned long)shmaddr;
780 loff_t size = 0;
781 int retval = -EINVAL;
782
783 down_write(&mm->mmap_sem);
784
785 /*
786 * This function tries to be smart and unmap shm segments that
787 * were modified by partial mlock or munmap calls:
788 * - It first determines the size of the shm segment that should be
789 * unmapped: It searches for a vma that is backed by shm and that
790 * started at address shmaddr. It records it's size and then unmaps
791 * it.
792 * - Then it unmaps all shm vmas that started at shmaddr and that
793 * are within the initially determined size.
794 * Errors from do_munmap are ignored: the function only fails if
795 * it's called with invalid parameters or if it's called to unmap
796 * a part of a vma. Both calls in this function are for full vmas,
797 * the parameters are directly copied from the vma itself and always
798 * valid - therefore do_munmap cannot fail. (famous last words?)
799 */
800 /*
801 * If it had been mremap()'d, the starting address would not
802 * match the usual checks anyway. So assume all vma's are
803 * above the starting address given.
804 */
805 vma = find_vma(mm, addr);
806
807 while (vma) {
808 next = vma->vm_next;
809
810 /*
811 * Check if the starting address would match, i.e. it's
812 * a fragment created by mprotect() and/or munmap(), or it
813 * otherwise it starts at this address with no hassles.
814 */
815 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
816 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
817
818
819 size = vma->vm_file->f_dentry->d_inode->i_size;
820 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
821 /*
822 * We discovered the size of the shm segment, so
823 * break out of here and fall through to the next
824 * loop that uses the size information to stop
825 * searching for matching vma's.
826 */
827 retval = 0;
828 vma = next;
829 break;
830 }
831 vma = next;
832 }
833
834 /*
835 * We need look no further than the maximum address a fragment
836 * could possibly have landed at. Also cast things to loff_t to
837 * prevent overflows and make comparisions vs. equal-width types.
838 */
839 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
840 next = vma->vm_next;
841
842 /* finding a matching vma now does not alter retval */
843 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
844 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
845
846 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
847 vma = next;
848 }
849
850 up_write(&mm->mmap_sem);
851 return retval;
852 }
853
854 #ifdef CONFIG_PROC_FS
855 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
856 {
857 off_t pos = 0;
858 off_t begin = 0;
859 int i, len = 0;
860
861 down(&shm_ids.sem);
862 len += sprintf(buffer, " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n");
863
864 for(i = 0; i <= shm_ids.max_id; i++) {
865 struct shmid_kernel* shp;
866
867 shp = shm_lock(i);
868 if(shp!=NULL) {
869 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
870 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
871 char *format;
872
873 if (sizeof(size_t) <= sizeof(int))
874 format = SMALL_STRING;
875 else
876 format = BIG_STRING;
877 len += sprintf(buffer + len, format,
878 shp->shm_perm.key,
879 shm_buildid(i, shp->shm_perm.seq),
880 shp->shm_flags,
881 shp->shm_segsz,
882 shp->shm_cprid,
883 shp->shm_lprid,
884 is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
885 shp->shm_perm.uid,
886 shp->shm_perm.gid,
887 shp->shm_perm.cuid,
888 shp->shm_perm.cgid,
889 shp->shm_atim,
890 shp->shm_dtim,
891 shp->shm_ctim);
892 shm_unlock(shp);
893
894 pos += len;
895 if(pos < offset) {
896 len = 0;
897 begin = pos;
898 }
899 if(pos > offset + length)
900 goto done;
901 }
902 }
903 *eof = 1;
904 done:
905 up(&shm_ids.sem);
906 *start = buffer + (offset - begin);
907 len -= (offset - begin);
908 if(len > length)
909 len = length;
910 if(len < 0)
911 len = 0;
912 return len;
913 }
914 #endif
915
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