xref: /linux/ipc/shm.c (revision ce14489c)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/ipc/shm.c
4  * Copyright (C) 1992, 1993 Krishna Balasubramanian
5  *	 Many improvements/fixes by Bruno Haible.
6  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
7  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
8  *
9  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
10  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
11  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
12  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
13  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
14  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
15  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
16  *
17  * support for audit of ipc object properties and permission changes
18  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
19  *
20  * namespaces support
21  * OpenVZ, SWsoft Inc.
22  * Pavel Emelianov <xemul@openvz.org>
23  *
24  * Better ipc lock (kern_ipc_perm.lock) handling
25  * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
26  */
27 
28 #include <linux/slab.h>
29 #include <linux/mm.h>
30 #include <linux/hugetlb.h>
31 #include <linux/shm.h>
32 #include <linux/init.h>
33 #include <linux/file.h>
34 #include <linux/mman.h>
35 #include <linux/shmem_fs.h>
36 #include <linux/security.h>
37 #include <linux/syscalls.h>
38 #include <linux/audit.h>
39 #include <linux/capability.h>
40 #include <linux/ptrace.h>
41 #include <linux/seq_file.h>
42 #include <linux/rwsem.h>
43 #include <linux/nsproxy.h>
44 #include <linux/mount.h>
45 #include <linux/ipc_namespace.h>
46 #include <linux/rhashtable.h>
47 
48 #include <linux/uaccess.h>
49 
50 #include "util.h"
51 
52 struct shmid_kernel /* private to the kernel */
53 {
54 	struct kern_ipc_perm	shm_perm;
55 	struct file		*shm_file;
56 	unsigned long		shm_nattch;
57 	unsigned long		shm_segsz;
58 	time64_t		shm_atim;
59 	time64_t		shm_dtim;
60 	time64_t		shm_ctim;
61 	struct pid		*shm_cprid;
62 	struct pid		*shm_lprid;
63 	struct user_struct	*mlock_user;
64 
65 	/* The task created the shm object.  NULL if the task is dead. */
66 	struct task_struct	*shm_creator;
67 	struct list_head	shm_clist;	/* list by creator */
68 } __randomize_layout;
69 
70 /* shm_mode upper byte flags */
71 #define SHM_DEST	01000	/* segment will be destroyed on last detach */
72 #define SHM_LOCKED	02000   /* segment will not be swapped */
73 
74 struct shm_file_data {
75 	int id;
76 	struct ipc_namespace *ns;
77 	struct file *file;
78 	const struct vm_operations_struct *vm_ops;
79 };
80 
81 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
82 
83 static const struct file_operations shm_file_operations;
84 static const struct vm_operations_struct shm_vm_ops;
85 
86 #define shm_ids(ns)	((ns)->ids[IPC_SHM_IDS])
87 
88 #define shm_unlock(shp)			\
89 	ipc_unlock(&(shp)->shm_perm)
90 
91 static int newseg(struct ipc_namespace *, struct ipc_params *);
92 static void shm_open(struct vm_area_struct *vma);
93 static void shm_close(struct vm_area_struct *vma);
94 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
95 #ifdef CONFIG_PROC_FS
96 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
97 #endif
98 
99 void shm_init_ns(struct ipc_namespace *ns)
100 {
101 	ns->shm_ctlmax = SHMMAX;
102 	ns->shm_ctlall = SHMALL;
103 	ns->shm_ctlmni = SHMMNI;
104 	ns->shm_rmid_forced = 0;
105 	ns->shm_tot = 0;
106 	ipc_init_ids(&shm_ids(ns));
107 }
108 
109 /*
110  * Called with shm_ids.rwsem (writer) and the shp structure locked.
111  * Only shm_ids.rwsem remains locked on exit.
112  */
113 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
114 {
115 	struct shmid_kernel *shp;
116 
117 	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
118 
119 	if (shp->shm_nattch) {
120 		shp->shm_perm.mode |= SHM_DEST;
121 		/* Do not find it any more */
122 		ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
123 		shm_unlock(shp);
124 	} else
125 		shm_destroy(ns, shp);
126 }
127 
128 #ifdef CONFIG_IPC_NS
129 void shm_exit_ns(struct ipc_namespace *ns)
130 {
131 	free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
132 	idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
133 	rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
134 }
135 #endif
136 
137 static int __init ipc_ns_init(void)
138 {
139 	shm_init_ns(&init_ipc_ns);
140 	return 0;
141 }
142 
143 pure_initcall(ipc_ns_init);
144 
145 void __init shm_init(void)
146 {
147 	ipc_init_proc_interface("sysvipc/shm",
148 #if BITS_PER_LONG <= 32
149 				"       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
150 #else
151 				"       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
152 #endif
153 				IPC_SHM_IDS, sysvipc_shm_proc_show);
154 }
155 
156 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
157 {
158 	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
159 
160 	if (IS_ERR(ipcp))
161 		return ERR_CAST(ipcp);
162 
163 	return container_of(ipcp, struct shmid_kernel, shm_perm);
164 }
165 
166 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
167 {
168 	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
169 
170 	if (IS_ERR(ipcp))
171 		return ERR_CAST(ipcp);
172 
173 	return container_of(ipcp, struct shmid_kernel, shm_perm);
174 }
175 
176 /*
177  * shm_lock_(check_) routines are called in the paths where the rwsem
178  * is not necessarily held.
179  */
180 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
181 {
182 	struct kern_ipc_perm *ipcp;
183 
184 	rcu_read_lock();
185 	ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
186 	if (IS_ERR(ipcp))
187 		goto err;
188 
189 	ipc_lock_object(ipcp);
190 	/*
191 	 * ipc_rmid() may have already freed the ID while ipc_lock_object()
192 	 * was spinning: here verify that the structure is still valid.
193 	 * Upon races with RMID, return -EIDRM, thus indicating that
194 	 * the ID points to a removed identifier.
195 	 */
196 	if (ipc_valid_object(ipcp)) {
197 		/* return a locked ipc object upon success */
198 		return container_of(ipcp, struct shmid_kernel, shm_perm);
199 	}
200 
201 	ipc_unlock_object(ipcp);
202 	ipcp = ERR_PTR(-EIDRM);
203 err:
204 	rcu_read_unlock();
205 	/*
206 	 * Callers of shm_lock() must validate the status of the returned ipc
207 	 * object pointer and error out as appropriate.
208 	 */
209 	return ERR_CAST(ipcp);
210 }
211 
212 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
213 {
214 	rcu_read_lock();
215 	ipc_lock_object(&ipcp->shm_perm);
216 }
217 
218 static void shm_rcu_free(struct rcu_head *head)
219 {
220 	struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
221 							rcu);
222 	struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
223 							shm_perm);
224 	security_shm_free(&shp->shm_perm);
225 	kvfree(shp);
226 }
227 
228 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
229 {
230 	list_del(&s->shm_clist);
231 	ipc_rmid(&shm_ids(ns), &s->shm_perm);
232 }
233 
234 
235 static int __shm_open(struct vm_area_struct *vma)
236 {
237 	struct file *file = vma->vm_file;
238 	struct shm_file_data *sfd = shm_file_data(file);
239 	struct shmid_kernel *shp;
240 
241 	shp = shm_lock(sfd->ns, sfd->id);
242 
243 	if (IS_ERR(shp))
244 		return PTR_ERR(shp);
245 
246 	if (shp->shm_file != sfd->file) {
247 		/* ID was reused */
248 		shm_unlock(shp);
249 		return -EINVAL;
250 	}
251 
252 	shp->shm_atim = ktime_get_real_seconds();
253 	ipc_update_pid(&shp->shm_lprid, task_tgid(current));
254 	shp->shm_nattch++;
255 	shm_unlock(shp);
256 	return 0;
257 }
258 
259 /* This is called by fork, once for every shm attach. */
260 static void shm_open(struct vm_area_struct *vma)
261 {
262 	int err = __shm_open(vma);
263 	/*
264 	 * We raced in the idr lookup or with shm_destroy().
265 	 * Either way, the ID is busted.
266 	 */
267 	WARN_ON_ONCE(err);
268 }
269 
270 /*
271  * shm_destroy - free the struct shmid_kernel
272  *
273  * @ns: namespace
274  * @shp: struct to free
275  *
276  * It has to be called with shp and shm_ids.rwsem (writer) locked,
277  * but returns with shp unlocked and freed.
278  */
279 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
280 {
281 	struct file *shm_file;
282 
283 	shm_file = shp->shm_file;
284 	shp->shm_file = NULL;
285 	ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
286 	shm_rmid(ns, shp);
287 	shm_unlock(shp);
288 	if (!is_file_hugepages(shm_file))
289 		shmem_lock(shm_file, 0, shp->mlock_user);
290 	else if (shp->mlock_user)
291 		user_shm_unlock(i_size_read(file_inode(shm_file)),
292 				shp->mlock_user);
293 	fput(shm_file);
294 	ipc_update_pid(&shp->shm_cprid, NULL);
295 	ipc_update_pid(&shp->shm_lprid, NULL);
296 	ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
297 }
298 
299 /*
300  * shm_may_destroy - identifies whether shm segment should be destroyed now
301  *
302  * Returns true if and only if there are no active users of the segment and
303  * one of the following is true:
304  *
305  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
306  *
307  * 2) sysctl kernel.shm_rmid_forced is set to 1.
308  */
309 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
310 {
311 	return (shp->shm_nattch == 0) &&
312 	       (ns->shm_rmid_forced ||
313 		(shp->shm_perm.mode & SHM_DEST));
314 }
315 
316 /*
317  * remove the attach descriptor vma.
318  * free memory for segment if it is marked destroyed.
319  * The descriptor has already been removed from the current->mm->mmap list
320  * and will later be kfree()d.
321  */
322 static void shm_close(struct vm_area_struct *vma)
323 {
324 	struct file *file = vma->vm_file;
325 	struct shm_file_data *sfd = shm_file_data(file);
326 	struct shmid_kernel *shp;
327 	struct ipc_namespace *ns = sfd->ns;
328 
329 	down_write(&shm_ids(ns).rwsem);
330 	/* remove from the list of attaches of the shm segment */
331 	shp = shm_lock(ns, sfd->id);
332 
333 	/*
334 	 * We raced in the idr lookup or with shm_destroy().
335 	 * Either way, the ID is busted.
336 	 */
337 	if (WARN_ON_ONCE(IS_ERR(shp)))
338 		goto done; /* no-op */
339 
340 	ipc_update_pid(&shp->shm_lprid, task_tgid(current));
341 	shp->shm_dtim = ktime_get_real_seconds();
342 	shp->shm_nattch--;
343 	if (shm_may_destroy(ns, shp))
344 		shm_destroy(ns, shp);
345 	else
346 		shm_unlock(shp);
347 done:
348 	up_write(&shm_ids(ns).rwsem);
349 }
350 
351 /* Called with ns->shm_ids(ns).rwsem locked */
352 static int shm_try_destroy_orphaned(int id, void *p, void *data)
353 {
354 	struct ipc_namespace *ns = data;
355 	struct kern_ipc_perm *ipcp = p;
356 	struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
357 
358 	/*
359 	 * We want to destroy segments without users and with already
360 	 * exit'ed originating process.
361 	 *
362 	 * As shp->* are changed under rwsem, it's safe to skip shp locking.
363 	 */
364 	if (shp->shm_creator != NULL)
365 		return 0;
366 
367 	if (shm_may_destroy(ns, shp)) {
368 		shm_lock_by_ptr(shp);
369 		shm_destroy(ns, shp);
370 	}
371 	return 0;
372 }
373 
374 void shm_destroy_orphaned(struct ipc_namespace *ns)
375 {
376 	down_write(&shm_ids(ns).rwsem);
377 	if (shm_ids(ns).in_use)
378 		idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
379 	up_write(&shm_ids(ns).rwsem);
380 }
381 
382 /* Locking assumes this will only be called with task == current */
383 void exit_shm(struct task_struct *task)
384 {
385 	struct ipc_namespace *ns = task->nsproxy->ipc_ns;
386 	struct shmid_kernel *shp, *n;
387 
388 	if (list_empty(&task->sysvshm.shm_clist))
389 		return;
390 
391 	/*
392 	 * If kernel.shm_rmid_forced is not set then only keep track of
393 	 * which shmids are orphaned, so that a later set of the sysctl
394 	 * can clean them up.
395 	 */
396 	if (!ns->shm_rmid_forced) {
397 		down_read(&shm_ids(ns).rwsem);
398 		list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
399 			shp->shm_creator = NULL;
400 		/*
401 		 * Only under read lock but we are only called on current
402 		 * so no entry on the list will be shared.
403 		 */
404 		list_del(&task->sysvshm.shm_clist);
405 		up_read(&shm_ids(ns).rwsem);
406 		return;
407 	}
408 
409 	/*
410 	 * Destroy all already created segments, that were not yet mapped,
411 	 * and mark any mapped as orphan to cover the sysctl toggling.
412 	 * Destroy is skipped if shm_may_destroy() returns false.
413 	 */
414 	down_write(&shm_ids(ns).rwsem);
415 	list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
416 		shp->shm_creator = NULL;
417 
418 		if (shm_may_destroy(ns, shp)) {
419 			shm_lock_by_ptr(shp);
420 			shm_destroy(ns, shp);
421 		}
422 	}
423 
424 	/* Remove the list head from any segments still attached. */
425 	list_del(&task->sysvshm.shm_clist);
426 	up_write(&shm_ids(ns).rwsem);
427 }
428 
429 static vm_fault_t shm_fault(struct vm_fault *vmf)
430 {
431 	struct file *file = vmf->vma->vm_file;
432 	struct shm_file_data *sfd = shm_file_data(file);
433 
434 	return sfd->vm_ops->fault(vmf);
435 }
436 
437 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
438 {
439 	struct file *file = vma->vm_file;
440 	struct shm_file_data *sfd = shm_file_data(file);
441 
442 	if (sfd->vm_ops->split)
443 		return sfd->vm_ops->split(vma, addr);
444 
445 	return 0;
446 }
447 
448 static unsigned long shm_pagesize(struct vm_area_struct *vma)
449 {
450 	struct file *file = vma->vm_file;
451 	struct shm_file_data *sfd = shm_file_data(file);
452 
453 	if (sfd->vm_ops->pagesize)
454 		return sfd->vm_ops->pagesize(vma);
455 
456 	return PAGE_SIZE;
457 }
458 
459 #ifdef CONFIG_NUMA
460 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
461 {
462 	struct file *file = vma->vm_file;
463 	struct shm_file_data *sfd = shm_file_data(file);
464 	int err = 0;
465 
466 	if (sfd->vm_ops->set_policy)
467 		err = sfd->vm_ops->set_policy(vma, new);
468 	return err;
469 }
470 
471 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
472 					unsigned long addr)
473 {
474 	struct file *file = vma->vm_file;
475 	struct shm_file_data *sfd = shm_file_data(file);
476 	struct mempolicy *pol = NULL;
477 
478 	if (sfd->vm_ops->get_policy)
479 		pol = sfd->vm_ops->get_policy(vma, addr);
480 	else if (vma->vm_policy)
481 		pol = vma->vm_policy;
482 
483 	return pol;
484 }
485 #endif
486 
487 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
488 {
489 	struct shm_file_data *sfd = shm_file_data(file);
490 	int ret;
491 
492 	/*
493 	 * In case of remap_file_pages() emulation, the file can represent an
494 	 * IPC ID that was removed, and possibly even reused by another shm
495 	 * segment already.  Propagate this case as an error to caller.
496 	 */
497 	ret = __shm_open(vma);
498 	if (ret)
499 		return ret;
500 
501 	ret = call_mmap(sfd->file, vma);
502 	if (ret) {
503 		shm_close(vma);
504 		return ret;
505 	}
506 	sfd->vm_ops = vma->vm_ops;
507 #ifdef CONFIG_MMU
508 	WARN_ON(!sfd->vm_ops->fault);
509 #endif
510 	vma->vm_ops = &shm_vm_ops;
511 	return 0;
512 }
513 
514 static int shm_release(struct inode *ino, struct file *file)
515 {
516 	struct shm_file_data *sfd = shm_file_data(file);
517 
518 	put_ipc_ns(sfd->ns);
519 	fput(sfd->file);
520 	shm_file_data(file) = NULL;
521 	kfree(sfd);
522 	return 0;
523 }
524 
525 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
526 {
527 	struct shm_file_data *sfd = shm_file_data(file);
528 
529 	if (!sfd->file->f_op->fsync)
530 		return -EINVAL;
531 	return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
532 }
533 
534 static long shm_fallocate(struct file *file, int mode, loff_t offset,
535 			  loff_t len)
536 {
537 	struct shm_file_data *sfd = shm_file_data(file);
538 
539 	if (!sfd->file->f_op->fallocate)
540 		return -EOPNOTSUPP;
541 	return sfd->file->f_op->fallocate(file, mode, offset, len);
542 }
543 
544 static unsigned long shm_get_unmapped_area(struct file *file,
545 	unsigned long addr, unsigned long len, unsigned long pgoff,
546 	unsigned long flags)
547 {
548 	struct shm_file_data *sfd = shm_file_data(file);
549 
550 	return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
551 						pgoff, flags);
552 }
553 
554 static const struct file_operations shm_file_operations = {
555 	.mmap		= shm_mmap,
556 	.fsync		= shm_fsync,
557 	.release	= shm_release,
558 	.get_unmapped_area	= shm_get_unmapped_area,
559 	.llseek		= noop_llseek,
560 	.fallocate	= shm_fallocate,
561 };
562 
563 /*
564  * shm_file_operations_huge is now identical to shm_file_operations,
565  * but we keep it distinct for the sake of is_file_shm_hugepages().
566  */
567 static const struct file_operations shm_file_operations_huge = {
568 	.mmap		= shm_mmap,
569 	.fsync		= shm_fsync,
570 	.release	= shm_release,
571 	.get_unmapped_area	= shm_get_unmapped_area,
572 	.llseek		= noop_llseek,
573 	.fallocate	= shm_fallocate,
574 };
575 
576 bool is_file_shm_hugepages(struct file *file)
577 {
578 	return file->f_op == &shm_file_operations_huge;
579 }
580 
581 static const struct vm_operations_struct shm_vm_ops = {
582 	.open	= shm_open,	/* callback for a new vm-area open */
583 	.close	= shm_close,	/* callback for when the vm-area is released */
584 	.fault	= shm_fault,
585 	.split	= shm_split,
586 	.pagesize = shm_pagesize,
587 #if defined(CONFIG_NUMA)
588 	.set_policy = shm_set_policy,
589 	.get_policy = shm_get_policy,
590 #endif
591 };
592 
593 /**
594  * newseg - Create a new shared memory segment
595  * @ns: namespace
596  * @params: ptr to the structure that contains key, size and shmflg
597  *
598  * Called with shm_ids.rwsem held as a writer.
599  */
600 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
601 {
602 	key_t key = params->key;
603 	int shmflg = params->flg;
604 	size_t size = params->u.size;
605 	int error;
606 	struct shmid_kernel *shp;
607 	size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
608 	struct file *file;
609 	char name[13];
610 	vm_flags_t acctflag = 0;
611 
612 	if (size < SHMMIN || size > ns->shm_ctlmax)
613 		return -EINVAL;
614 
615 	if (numpages << PAGE_SHIFT < size)
616 		return -ENOSPC;
617 
618 	if (ns->shm_tot + numpages < ns->shm_tot ||
619 			ns->shm_tot + numpages > ns->shm_ctlall)
620 		return -ENOSPC;
621 
622 	shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
623 	if (unlikely(!shp))
624 		return -ENOMEM;
625 
626 	shp->shm_perm.key = key;
627 	shp->shm_perm.mode = (shmflg & S_IRWXUGO);
628 	shp->mlock_user = NULL;
629 
630 	shp->shm_perm.security = NULL;
631 	error = security_shm_alloc(&shp->shm_perm);
632 	if (error) {
633 		kvfree(shp);
634 		return error;
635 	}
636 
637 	sprintf(name, "SYSV%08x", key);
638 	if (shmflg & SHM_HUGETLB) {
639 		struct hstate *hs;
640 		size_t hugesize;
641 
642 		hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
643 		if (!hs) {
644 			error = -EINVAL;
645 			goto no_file;
646 		}
647 		hugesize = ALIGN(size, huge_page_size(hs));
648 
649 		/* hugetlb_file_setup applies strict accounting */
650 		if (shmflg & SHM_NORESERVE)
651 			acctflag = VM_NORESERVE;
652 		file = hugetlb_file_setup(name, hugesize, acctflag,
653 				  &shp->mlock_user, HUGETLB_SHMFS_INODE,
654 				(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
655 	} else {
656 		/*
657 		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
658 		 * if it's asked for.
659 		 */
660 		if  ((shmflg & SHM_NORESERVE) &&
661 				sysctl_overcommit_memory != OVERCOMMIT_NEVER)
662 			acctflag = VM_NORESERVE;
663 		file = shmem_kernel_file_setup(name, size, acctflag);
664 	}
665 	error = PTR_ERR(file);
666 	if (IS_ERR(file))
667 		goto no_file;
668 
669 	shp->shm_cprid = get_pid(task_tgid(current));
670 	shp->shm_lprid = NULL;
671 	shp->shm_atim = shp->shm_dtim = 0;
672 	shp->shm_ctim = ktime_get_real_seconds();
673 	shp->shm_segsz = size;
674 	shp->shm_nattch = 0;
675 	shp->shm_file = file;
676 	shp->shm_creator = current;
677 
678 	/* ipc_addid() locks shp upon success. */
679 	error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
680 	if (error < 0)
681 		goto no_id;
682 
683 	list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
684 
685 	/*
686 	 * shmid gets reported as "inode#" in /proc/pid/maps.
687 	 * proc-ps tools use this. Changing this will break them.
688 	 */
689 	file_inode(file)->i_ino = shp->shm_perm.id;
690 
691 	ns->shm_tot += numpages;
692 	error = shp->shm_perm.id;
693 
694 	ipc_unlock_object(&shp->shm_perm);
695 	rcu_read_unlock();
696 	return error;
697 
698 no_id:
699 	ipc_update_pid(&shp->shm_cprid, NULL);
700 	ipc_update_pid(&shp->shm_lprid, NULL);
701 	if (is_file_hugepages(file) && shp->mlock_user)
702 		user_shm_unlock(size, shp->mlock_user);
703 	fput(file);
704 	ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
705 	return error;
706 no_file:
707 	call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
708 	return error;
709 }
710 
711 /*
712  * Called with shm_ids.rwsem and ipcp locked.
713  */
714 static int shm_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params)
715 {
716 	struct shmid_kernel *shp;
717 
718 	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
719 	if (shp->shm_segsz < params->u.size)
720 		return -EINVAL;
721 
722 	return 0;
723 }
724 
725 long ksys_shmget(key_t key, size_t size, int shmflg)
726 {
727 	struct ipc_namespace *ns;
728 	static const struct ipc_ops shm_ops = {
729 		.getnew = newseg,
730 		.associate = security_shm_associate,
731 		.more_checks = shm_more_checks,
732 	};
733 	struct ipc_params shm_params;
734 
735 	ns = current->nsproxy->ipc_ns;
736 
737 	shm_params.key = key;
738 	shm_params.flg = shmflg;
739 	shm_params.u.size = size;
740 
741 	return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
742 }
743 
744 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
745 {
746 	return ksys_shmget(key, size, shmflg);
747 }
748 
749 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
750 {
751 	switch (version) {
752 	case IPC_64:
753 		return copy_to_user(buf, in, sizeof(*in));
754 	case IPC_OLD:
755 	    {
756 		struct shmid_ds out;
757 
758 		memset(&out, 0, sizeof(out));
759 		ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
760 		out.shm_segsz	= in->shm_segsz;
761 		out.shm_atime	= in->shm_atime;
762 		out.shm_dtime	= in->shm_dtime;
763 		out.shm_ctime	= in->shm_ctime;
764 		out.shm_cpid	= in->shm_cpid;
765 		out.shm_lpid	= in->shm_lpid;
766 		out.shm_nattch	= in->shm_nattch;
767 
768 		return copy_to_user(buf, &out, sizeof(out));
769 	    }
770 	default:
771 		return -EINVAL;
772 	}
773 }
774 
775 static inline unsigned long
776 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
777 {
778 	switch (version) {
779 	case IPC_64:
780 		if (copy_from_user(out, buf, sizeof(*out)))
781 			return -EFAULT;
782 		return 0;
783 	case IPC_OLD:
784 	    {
785 		struct shmid_ds tbuf_old;
786 
787 		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
788 			return -EFAULT;
789 
790 		out->shm_perm.uid	= tbuf_old.shm_perm.uid;
791 		out->shm_perm.gid	= tbuf_old.shm_perm.gid;
792 		out->shm_perm.mode	= tbuf_old.shm_perm.mode;
793 
794 		return 0;
795 	    }
796 	default:
797 		return -EINVAL;
798 	}
799 }
800 
801 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
802 {
803 	switch (version) {
804 	case IPC_64:
805 		return copy_to_user(buf, in, sizeof(*in));
806 	case IPC_OLD:
807 	    {
808 		struct shminfo out;
809 
810 		if (in->shmmax > INT_MAX)
811 			out.shmmax = INT_MAX;
812 		else
813 			out.shmmax = (int)in->shmmax;
814 
815 		out.shmmin	= in->shmmin;
816 		out.shmmni	= in->shmmni;
817 		out.shmseg	= in->shmseg;
818 		out.shmall	= in->shmall;
819 
820 		return copy_to_user(buf, &out, sizeof(out));
821 	    }
822 	default:
823 		return -EINVAL;
824 	}
825 }
826 
827 /*
828  * Calculate and add used RSS and swap pages of a shm.
829  * Called with shm_ids.rwsem held as a reader
830  */
831 static void shm_add_rss_swap(struct shmid_kernel *shp,
832 	unsigned long *rss_add, unsigned long *swp_add)
833 {
834 	struct inode *inode;
835 
836 	inode = file_inode(shp->shm_file);
837 
838 	if (is_file_hugepages(shp->shm_file)) {
839 		struct address_space *mapping = inode->i_mapping;
840 		struct hstate *h = hstate_file(shp->shm_file);
841 		*rss_add += pages_per_huge_page(h) * mapping->nrpages;
842 	} else {
843 #ifdef CONFIG_SHMEM
844 		struct shmem_inode_info *info = SHMEM_I(inode);
845 
846 		spin_lock_irq(&info->lock);
847 		*rss_add += inode->i_mapping->nrpages;
848 		*swp_add += info->swapped;
849 		spin_unlock_irq(&info->lock);
850 #else
851 		*rss_add += inode->i_mapping->nrpages;
852 #endif
853 	}
854 }
855 
856 /*
857  * Called with shm_ids.rwsem held as a reader
858  */
859 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
860 		unsigned long *swp)
861 {
862 	int next_id;
863 	int total, in_use;
864 
865 	*rss = 0;
866 	*swp = 0;
867 
868 	in_use = shm_ids(ns).in_use;
869 
870 	for (total = 0, next_id = 0; total < in_use; next_id++) {
871 		struct kern_ipc_perm *ipc;
872 		struct shmid_kernel *shp;
873 
874 		ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
875 		if (ipc == NULL)
876 			continue;
877 		shp = container_of(ipc, struct shmid_kernel, shm_perm);
878 
879 		shm_add_rss_swap(shp, rss, swp);
880 
881 		total++;
882 	}
883 }
884 
885 /*
886  * This function handles some shmctl commands which require the rwsem
887  * to be held in write mode.
888  * NOTE: no locks must be held, the rwsem is taken inside this function.
889  */
890 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
891 		       struct shmid64_ds *shmid64)
892 {
893 	struct kern_ipc_perm *ipcp;
894 	struct shmid_kernel *shp;
895 	int err;
896 
897 	down_write(&shm_ids(ns).rwsem);
898 	rcu_read_lock();
899 
900 	ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
901 				      &shmid64->shm_perm, 0);
902 	if (IS_ERR(ipcp)) {
903 		err = PTR_ERR(ipcp);
904 		goto out_unlock1;
905 	}
906 
907 	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
908 
909 	err = security_shm_shmctl(&shp->shm_perm, cmd);
910 	if (err)
911 		goto out_unlock1;
912 
913 	switch (cmd) {
914 	case IPC_RMID:
915 		ipc_lock_object(&shp->shm_perm);
916 		/* do_shm_rmid unlocks the ipc object and rcu */
917 		do_shm_rmid(ns, ipcp);
918 		goto out_up;
919 	case IPC_SET:
920 		ipc_lock_object(&shp->shm_perm);
921 		err = ipc_update_perm(&shmid64->shm_perm, ipcp);
922 		if (err)
923 			goto out_unlock0;
924 		shp->shm_ctim = ktime_get_real_seconds();
925 		break;
926 	default:
927 		err = -EINVAL;
928 		goto out_unlock1;
929 	}
930 
931 out_unlock0:
932 	ipc_unlock_object(&shp->shm_perm);
933 out_unlock1:
934 	rcu_read_unlock();
935 out_up:
936 	up_write(&shm_ids(ns).rwsem);
937 	return err;
938 }
939 
940 static int shmctl_ipc_info(struct ipc_namespace *ns,
941 			   struct shminfo64 *shminfo)
942 {
943 	int err = security_shm_shmctl(NULL, IPC_INFO);
944 	if (!err) {
945 		memset(shminfo, 0, sizeof(*shminfo));
946 		shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
947 		shminfo->shmmax = ns->shm_ctlmax;
948 		shminfo->shmall = ns->shm_ctlall;
949 		shminfo->shmmin = SHMMIN;
950 		down_read(&shm_ids(ns).rwsem);
951 		err = ipc_get_maxidx(&shm_ids(ns));
952 		up_read(&shm_ids(ns).rwsem);
953 		if (err < 0)
954 			err = 0;
955 	}
956 	return err;
957 }
958 
959 static int shmctl_shm_info(struct ipc_namespace *ns,
960 			   struct shm_info *shm_info)
961 {
962 	int err = security_shm_shmctl(NULL, SHM_INFO);
963 	if (!err) {
964 		memset(shm_info, 0, sizeof(*shm_info));
965 		down_read(&shm_ids(ns).rwsem);
966 		shm_info->used_ids = shm_ids(ns).in_use;
967 		shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
968 		shm_info->shm_tot = ns->shm_tot;
969 		shm_info->swap_attempts = 0;
970 		shm_info->swap_successes = 0;
971 		err = ipc_get_maxidx(&shm_ids(ns));
972 		up_read(&shm_ids(ns).rwsem);
973 		if (err < 0)
974 			err = 0;
975 	}
976 	return err;
977 }
978 
979 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
980 			int cmd, struct shmid64_ds *tbuf)
981 {
982 	struct shmid_kernel *shp;
983 	int err;
984 
985 	memset(tbuf, 0, sizeof(*tbuf));
986 
987 	rcu_read_lock();
988 	if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
989 		shp = shm_obtain_object(ns, shmid);
990 		if (IS_ERR(shp)) {
991 			err = PTR_ERR(shp);
992 			goto out_unlock;
993 		}
994 	} else { /* IPC_STAT */
995 		shp = shm_obtain_object_check(ns, shmid);
996 		if (IS_ERR(shp)) {
997 			err = PTR_ERR(shp);
998 			goto out_unlock;
999 		}
1000 	}
1001 
1002 	/*
1003 	 * Semantically SHM_STAT_ANY ought to be identical to
1004 	 * that functionality provided by the /proc/sysvipc/
1005 	 * interface. As such, only audit these calls and
1006 	 * do not do traditional S_IRUGO permission checks on
1007 	 * the ipc object.
1008 	 */
1009 	if (cmd == SHM_STAT_ANY)
1010 		audit_ipc_obj(&shp->shm_perm);
1011 	else {
1012 		err = -EACCES;
1013 		if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1014 			goto out_unlock;
1015 	}
1016 
1017 	err = security_shm_shmctl(&shp->shm_perm, cmd);
1018 	if (err)
1019 		goto out_unlock;
1020 
1021 	ipc_lock_object(&shp->shm_perm);
1022 
1023 	if (!ipc_valid_object(&shp->shm_perm)) {
1024 		ipc_unlock_object(&shp->shm_perm);
1025 		err = -EIDRM;
1026 		goto out_unlock;
1027 	}
1028 
1029 	kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1030 	tbuf->shm_segsz	= shp->shm_segsz;
1031 	tbuf->shm_atime	= shp->shm_atim;
1032 	tbuf->shm_dtime	= shp->shm_dtim;
1033 	tbuf->shm_ctime	= shp->shm_ctim;
1034 #ifndef CONFIG_64BIT
1035 	tbuf->shm_atime_high = shp->shm_atim >> 32;
1036 	tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1037 	tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1038 #endif
1039 	tbuf->shm_cpid	= pid_vnr(shp->shm_cprid);
1040 	tbuf->shm_lpid	= pid_vnr(shp->shm_lprid);
1041 	tbuf->shm_nattch = shp->shm_nattch;
1042 
1043 	if (cmd == IPC_STAT) {
1044 		/*
1045 		 * As defined in SUS:
1046 		 * Return 0 on success
1047 		 */
1048 		err = 0;
1049 	} else {
1050 		/*
1051 		 * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1052 		 * Return the full id, including the sequence number
1053 		 */
1054 		err = shp->shm_perm.id;
1055 	}
1056 
1057 	ipc_unlock_object(&shp->shm_perm);
1058 out_unlock:
1059 	rcu_read_unlock();
1060 	return err;
1061 }
1062 
1063 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1064 {
1065 	struct shmid_kernel *shp;
1066 	struct file *shm_file;
1067 	int err;
1068 
1069 	rcu_read_lock();
1070 	shp = shm_obtain_object_check(ns, shmid);
1071 	if (IS_ERR(shp)) {
1072 		err = PTR_ERR(shp);
1073 		goto out_unlock1;
1074 	}
1075 
1076 	audit_ipc_obj(&(shp->shm_perm));
1077 	err = security_shm_shmctl(&shp->shm_perm, cmd);
1078 	if (err)
1079 		goto out_unlock1;
1080 
1081 	ipc_lock_object(&shp->shm_perm);
1082 
1083 	/* check if shm_destroy() is tearing down shp */
1084 	if (!ipc_valid_object(&shp->shm_perm)) {
1085 		err = -EIDRM;
1086 		goto out_unlock0;
1087 	}
1088 
1089 	if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1090 		kuid_t euid = current_euid();
1091 
1092 		if (!uid_eq(euid, shp->shm_perm.uid) &&
1093 		    !uid_eq(euid, shp->shm_perm.cuid)) {
1094 			err = -EPERM;
1095 			goto out_unlock0;
1096 		}
1097 		if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1098 			err = -EPERM;
1099 			goto out_unlock0;
1100 		}
1101 	}
1102 
1103 	shm_file = shp->shm_file;
1104 	if (is_file_hugepages(shm_file))
1105 		goto out_unlock0;
1106 
1107 	if (cmd == SHM_LOCK) {
1108 		struct user_struct *user = current_user();
1109 
1110 		err = shmem_lock(shm_file, 1, user);
1111 		if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1112 			shp->shm_perm.mode |= SHM_LOCKED;
1113 			shp->mlock_user = user;
1114 		}
1115 		goto out_unlock0;
1116 	}
1117 
1118 	/* SHM_UNLOCK */
1119 	if (!(shp->shm_perm.mode & SHM_LOCKED))
1120 		goto out_unlock0;
1121 	shmem_lock(shm_file, 0, shp->mlock_user);
1122 	shp->shm_perm.mode &= ~SHM_LOCKED;
1123 	shp->mlock_user = NULL;
1124 	get_file(shm_file);
1125 	ipc_unlock_object(&shp->shm_perm);
1126 	rcu_read_unlock();
1127 	shmem_unlock_mapping(shm_file->f_mapping);
1128 
1129 	fput(shm_file);
1130 	return err;
1131 
1132 out_unlock0:
1133 	ipc_unlock_object(&shp->shm_perm);
1134 out_unlock1:
1135 	rcu_read_unlock();
1136 	return err;
1137 }
1138 
1139 static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
1140 {
1141 	int err;
1142 	struct ipc_namespace *ns;
1143 	struct shmid64_ds sem64;
1144 
1145 	if (cmd < 0 || shmid < 0)
1146 		return -EINVAL;
1147 
1148 	ns = current->nsproxy->ipc_ns;
1149 
1150 	switch (cmd) {
1151 	case IPC_INFO: {
1152 		struct shminfo64 shminfo;
1153 		err = shmctl_ipc_info(ns, &shminfo);
1154 		if (err < 0)
1155 			return err;
1156 		if (copy_shminfo_to_user(buf, &shminfo, version))
1157 			err = -EFAULT;
1158 		return err;
1159 	}
1160 	case SHM_INFO: {
1161 		struct shm_info shm_info;
1162 		err = shmctl_shm_info(ns, &shm_info);
1163 		if (err < 0)
1164 			return err;
1165 		if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1166 			err = -EFAULT;
1167 		return err;
1168 	}
1169 	case SHM_STAT:
1170 	case SHM_STAT_ANY:
1171 	case IPC_STAT: {
1172 		err = shmctl_stat(ns, shmid, cmd, &sem64);
1173 		if (err < 0)
1174 			return err;
1175 		if (copy_shmid_to_user(buf, &sem64, version))
1176 			err = -EFAULT;
1177 		return err;
1178 	}
1179 	case IPC_SET:
1180 		if (copy_shmid_from_user(&sem64, buf, version))
1181 			return -EFAULT;
1182 		/* fallthru */
1183 	case IPC_RMID:
1184 		return shmctl_down(ns, shmid, cmd, &sem64);
1185 	case SHM_LOCK:
1186 	case SHM_UNLOCK:
1187 		return shmctl_do_lock(ns, shmid, cmd);
1188 	default:
1189 		return -EINVAL;
1190 	}
1191 }
1192 
1193 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1194 {
1195 	return ksys_shmctl(shmid, cmd, buf, IPC_64);
1196 }
1197 
1198 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
1199 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1200 {
1201 	int version = ipc_parse_version(&cmd);
1202 
1203 	return ksys_shmctl(shmid, cmd, buf, version);
1204 }
1205 
1206 SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1207 {
1208 	return ksys_old_shmctl(shmid, cmd, buf);
1209 }
1210 #endif
1211 
1212 #ifdef CONFIG_COMPAT
1213 
1214 struct compat_shmid_ds {
1215 	struct compat_ipc_perm shm_perm;
1216 	int shm_segsz;
1217 	old_time32_t shm_atime;
1218 	old_time32_t shm_dtime;
1219 	old_time32_t shm_ctime;
1220 	compat_ipc_pid_t shm_cpid;
1221 	compat_ipc_pid_t shm_lpid;
1222 	unsigned short shm_nattch;
1223 	unsigned short shm_unused;
1224 	compat_uptr_t shm_unused2;
1225 	compat_uptr_t shm_unused3;
1226 };
1227 
1228 struct compat_shminfo64 {
1229 	compat_ulong_t shmmax;
1230 	compat_ulong_t shmmin;
1231 	compat_ulong_t shmmni;
1232 	compat_ulong_t shmseg;
1233 	compat_ulong_t shmall;
1234 	compat_ulong_t __unused1;
1235 	compat_ulong_t __unused2;
1236 	compat_ulong_t __unused3;
1237 	compat_ulong_t __unused4;
1238 };
1239 
1240 struct compat_shm_info {
1241 	compat_int_t used_ids;
1242 	compat_ulong_t shm_tot, shm_rss, shm_swp;
1243 	compat_ulong_t swap_attempts, swap_successes;
1244 };
1245 
1246 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1247 					int version)
1248 {
1249 	if (in->shmmax > INT_MAX)
1250 		in->shmmax = INT_MAX;
1251 	if (version == IPC_64) {
1252 		struct compat_shminfo64 info;
1253 		memset(&info, 0, sizeof(info));
1254 		info.shmmax = in->shmmax;
1255 		info.shmmin = in->shmmin;
1256 		info.shmmni = in->shmmni;
1257 		info.shmseg = in->shmseg;
1258 		info.shmall = in->shmall;
1259 		return copy_to_user(buf, &info, sizeof(info));
1260 	} else {
1261 		struct shminfo info;
1262 		memset(&info, 0, sizeof(info));
1263 		info.shmmax = in->shmmax;
1264 		info.shmmin = in->shmmin;
1265 		info.shmmni = in->shmmni;
1266 		info.shmseg = in->shmseg;
1267 		info.shmall = in->shmall;
1268 		return copy_to_user(buf, &info, sizeof(info));
1269 	}
1270 }
1271 
1272 static int put_compat_shm_info(struct shm_info *ip,
1273 				struct compat_shm_info __user *uip)
1274 {
1275 	struct compat_shm_info info;
1276 
1277 	memset(&info, 0, sizeof(info));
1278 	info.used_ids = ip->used_ids;
1279 	info.shm_tot = ip->shm_tot;
1280 	info.shm_rss = ip->shm_rss;
1281 	info.shm_swp = ip->shm_swp;
1282 	info.swap_attempts = ip->swap_attempts;
1283 	info.swap_successes = ip->swap_successes;
1284 	return copy_to_user(uip, &info, sizeof(info));
1285 }
1286 
1287 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1288 					int version)
1289 {
1290 	if (version == IPC_64) {
1291 		struct compat_shmid64_ds v;
1292 		memset(&v, 0, sizeof(v));
1293 		to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1294 		v.shm_atime	 = lower_32_bits(in->shm_atime);
1295 		v.shm_atime_high = upper_32_bits(in->shm_atime);
1296 		v.shm_dtime	 = lower_32_bits(in->shm_dtime);
1297 		v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1298 		v.shm_ctime	 = lower_32_bits(in->shm_ctime);
1299 		v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1300 		v.shm_segsz = in->shm_segsz;
1301 		v.shm_nattch = in->shm_nattch;
1302 		v.shm_cpid = in->shm_cpid;
1303 		v.shm_lpid = in->shm_lpid;
1304 		return copy_to_user(buf, &v, sizeof(v));
1305 	} else {
1306 		struct compat_shmid_ds v;
1307 		memset(&v, 0, sizeof(v));
1308 		to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1309 		v.shm_perm.key = in->shm_perm.key;
1310 		v.shm_atime = in->shm_atime;
1311 		v.shm_dtime = in->shm_dtime;
1312 		v.shm_ctime = in->shm_ctime;
1313 		v.shm_segsz = in->shm_segsz;
1314 		v.shm_nattch = in->shm_nattch;
1315 		v.shm_cpid = in->shm_cpid;
1316 		v.shm_lpid = in->shm_lpid;
1317 		return copy_to_user(buf, &v, sizeof(v));
1318 	}
1319 }
1320 
1321 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1322 					int version)
1323 {
1324 	memset(out, 0, sizeof(*out));
1325 	if (version == IPC_64) {
1326 		struct compat_shmid64_ds __user *p = buf;
1327 		return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1328 	} else {
1329 		struct compat_shmid_ds __user *p = buf;
1330 		return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1331 	}
1332 }
1333 
1334 static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
1335 {
1336 	struct ipc_namespace *ns;
1337 	struct shmid64_ds sem64;
1338 	int err;
1339 
1340 	ns = current->nsproxy->ipc_ns;
1341 
1342 	if (cmd < 0 || shmid < 0)
1343 		return -EINVAL;
1344 
1345 	switch (cmd) {
1346 	case IPC_INFO: {
1347 		struct shminfo64 shminfo;
1348 		err = shmctl_ipc_info(ns, &shminfo);
1349 		if (err < 0)
1350 			return err;
1351 		if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1352 			err = -EFAULT;
1353 		return err;
1354 	}
1355 	case SHM_INFO: {
1356 		struct shm_info shm_info;
1357 		err = shmctl_shm_info(ns, &shm_info);
1358 		if (err < 0)
1359 			return err;
1360 		if (put_compat_shm_info(&shm_info, uptr))
1361 			err = -EFAULT;
1362 		return err;
1363 	}
1364 	case IPC_STAT:
1365 	case SHM_STAT_ANY:
1366 	case SHM_STAT:
1367 		err = shmctl_stat(ns, shmid, cmd, &sem64);
1368 		if (err < 0)
1369 			return err;
1370 		if (copy_compat_shmid_to_user(uptr, &sem64, version))
1371 			err = -EFAULT;
1372 		return err;
1373 
1374 	case IPC_SET:
1375 		if (copy_compat_shmid_from_user(&sem64, uptr, version))
1376 			return -EFAULT;
1377 		/* fallthru */
1378 	case IPC_RMID:
1379 		return shmctl_down(ns, shmid, cmd, &sem64);
1380 	case SHM_LOCK:
1381 	case SHM_UNLOCK:
1382 		return shmctl_do_lock(ns, shmid, cmd);
1383 	default:
1384 		return -EINVAL;
1385 	}
1386 	return err;
1387 }
1388 
1389 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1390 {
1391 	return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
1392 }
1393 
1394 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
1395 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
1396 {
1397 	int version = compat_ipc_parse_version(&cmd);
1398 
1399 	return compat_ksys_shmctl(shmid, cmd, uptr, version);
1400 }
1401 
1402 COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
1403 {
1404 	return compat_ksys_old_shmctl(shmid, cmd, uptr);
1405 }
1406 #endif
1407 #endif
1408 
1409 /*
1410  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1411  *
1412  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1413  * "raddr" thing points to kernel space, and there has to be a wrapper around
1414  * this.
1415  */
1416 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1417 	      ulong *raddr, unsigned long shmlba)
1418 {
1419 	struct shmid_kernel *shp;
1420 	unsigned long addr = (unsigned long)shmaddr;
1421 	unsigned long size;
1422 	struct file *file, *base;
1423 	int    err;
1424 	unsigned long flags = MAP_SHARED;
1425 	unsigned long prot;
1426 	int acc_mode;
1427 	struct ipc_namespace *ns;
1428 	struct shm_file_data *sfd;
1429 	int f_flags;
1430 	unsigned long populate = 0;
1431 
1432 	err = -EINVAL;
1433 	if (shmid < 0)
1434 		goto out;
1435 
1436 	if (addr) {
1437 		if (addr & (shmlba - 1)) {
1438 			if (shmflg & SHM_RND) {
1439 				addr &= ~(shmlba - 1);  /* round down */
1440 
1441 				/*
1442 				 * Ensure that the round-down is non-nil
1443 				 * when remapping. This can happen for
1444 				 * cases when addr < shmlba.
1445 				 */
1446 				if (!addr && (shmflg & SHM_REMAP))
1447 					goto out;
1448 			} else
1449 #ifndef __ARCH_FORCE_SHMLBA
1450 				if (addr & ~PAGE_MASK)
1451 #endif
1452 					goto out;
1453 		}
1454 
1455 		flags |= MAP_FIXED;
1456 	} else if ((shmflg & SHM_REMAP))
1457 		goto out;
1458 
1459 	if (shmflg & SHM_RDONLY) {
1460 		prot = PROT_READ;
1461 		acc_mode = S_IRUGO;
1462 		f_flags = O_RDONLY;
1463 	} else {
1464 		prot = PROT_READ | PROT_WRITE;
1465 		acc_mode = S_IRUGO | S_IWUGO;
1466 		f_flags = O_RDWR;
1467 	}
1468 	if (shmflg & SHM_EXEC) {
1469 		prot |= PROT_EXEC;
1470 		acc_mode |= S_IXUGO;
1471 	}
1472 
1473 	/*
1474 	 * We cannot rely on the fs check since SYSV IPC does have an
1475 	 * additional creator id...
1476 	 */
1477 	ns = current->nsproxy->ipc_ns;
1478 	rcu_read_lock();
1479 	shp = shm_obtain_object_check(ns, shmid);
1480 	if (IS_ERR(shp)) {
1481 		err = PTR_ERR(shp);
1482 		goto out_unlock;
1483 	}
1484 
1485 	err = -EACCES;
1486 	if (ipcperms(ns, &shp->shm_perm, acc_mode))
1487 		goto out_unlock;
1488 
1489 	err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1490 	if (err)
1491 		goto out_unlock;
1492 
1493 	ipc_lock_object(&shp->shm_perm);
1494 
1495 	/* check if shm_destroy() is tearing down shp */
1496 	if (!ipc_valid_object(&shp->shm_perm)) {
1497 		ipc_unlock_object(&shp->shm_perm);
1498 		err = -EIDRM;
1499 		goto out_unlock;
1500 	}
1501 
1502 	/*
1503 	 * We need to take a reference to the real shm file to prevent the
1504 	 * pointer from becoming stale in cases where the lifetime of the outer
1505 	 * file extends beyond that of the shm segment.  It's not usually
1506 	 * possible, but it can happen during remap_file_pages() emulation as
1507 	 * that unmaps the memory, then does ->mmap() via file reference only.
1508 	 * We'll deny the ->mmap() if the shm segment was since removed, but to
1509 	 * detect shm ID reuse we need to compare the file pointers.
1510 	 */
1511 	base = get_file(shp->shm_file);
1512 	shp->shm_nattch++;
1513 	size = i_size_read(file_inode(base));
1514 	ipc_unlock_object(&shp->shm_perm);
1515 	rcu_read_unlock();
1516 
1517 	err = -ENOMEM;
1518 	sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1519 	if (!sfd) {
1520 		fput(base);
1521 		goto out_nattch;
1522 	}
1523 
1524 	file = alloc_file_clone(base, f_flags,
1525 			  is_file_hugepages(base) ?
1526 				&shm_file_operations_huge :
1527 				&shm_file_operations);
1528 	err = PTR_ERR(file);
1529 	if (IS_ERR(file)) {
1530 		kfree(sfd);
1531 		fput(base);
1532 		goto out_nattch;
1533 	}
1534 
1535 	sfd->id = shp->shm_perm.id;
1536 	sfd->ns = get_ipc_ns(ns);
1537 	sfd->file = base;
1538 	sfd->vm_ops = NULL;
1539 	file->private_data = sfd;
1540 
1541 	err = security_mmap_file(file, prot, flags);
1542 	if (err)
1543 		goto out_fput;
1544 
1545 	if (mmap_write_lock_killable(current->mm)) {
1546 		err = -EINTR;
1547 		goto out_fput;
1548 	}
1549 
1550 	if (addr && !(shmflg & SHM_REMAP)) {
1551 		err = -EINVAL;
1552 		if (addr + size < addr)
1553 			goto invalid;
1554 
1555 		if (find_vma_intersection(current->mm, addr, addr + size))
1556 			goto invalid;
1557 	}
1558 
1559 	addr = do_mmap(file, addr, size, prot, flags, 0, &populate, NULL);
1560 	*raddr = addr;
1561 	err = 0;
1562 	if (IS_ERR_VALUE(addr))
1563 		err = (long)addr;
1564 invalid:
1565 	mmap_write_unlock(current->mm);
1566 	if (populate)
1567 		mm_populate(addr, populate);
1568 
1569 out_fput:
1570 	fput(file);
1571 
1572 out_nattch:
1573 	down_write(&shm_ids(ns).rwsem);
1574 	shp = shm_lock(ns, shmid);
1575 	shp->shm_nattch--;
1576 	if (shm_may_destroy(ns, shp))
1577 		shm_destroy(ns, shp);
1578 	else
1579 		shm_unlock(shp);
1580 	up_write(&shm_ids(ns).rwsem);
1581 	return err;
1582 
1583 out_unlock:
1584 	rcu_read_unlock();
1585 out:
1586 	return err;
1587 }
1588 
1589 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1590 {
1591 	unsigned long ret;
1592 	long err;
1593 
1594 	err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1595 	if (err)
1596 		return err;
1597 	force_successful_syscall_return();
1598 	return (long)ret;
1599 }
1600 
1601 #ifdef CONFIG_COMPAT
1602 
1603 #ifndef COMPAT_SHMLBA
1604 #define COMPAT_SHMLBA	SHMLBA
1605 #endif
1606 
1607 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1608 {
1609 	unsigned long ret;
1610 	long err;
1611 
1612 	err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1613 	if (err)
1614 		return err;
1615 	force_successful_syscall_return();
1616 	return (long)ret;
1617 }
1618 #endif
1619 
1620 /*
1621  * detach and kill segment if marked destroyed.
1622  * The work is done in shm_close.
1623  */
1624 long ksys_shmdt(char __user *shmaddr)
1625 {
1626 	struct mm_struct *mm = current->mm;
1627 	struct vm_area_struct *vma;
1628 	unsigned long addr = (unsigned long)shmaddr;
1629 	int retval = -EINVAL;
1630 #ifdef CONFIG_MMU
1631 	loff_t size = 0;
1632 	struct file *file;
1633 	struct vm_area_struct *next;
1634 #endif
1635 
1636 	if (addr & ~PAGE_MASK)
1637 		return retval;
1638 
1639 	if (mmap_write_lock_killable(mm))
1640 		return -EINTR;
1641 
1642 	/*
1643 	 * This function tries to be smart and unmap shm segments that
1644 	 * were modified by partial mlock or munmap calls:
1645 	 * - It first determines the size of the shm segment that should be
1646 	 *   unmapped: It searches for a vma that is backed by shm and that
1647 	 *   started at address shmaddr. It records it's size and then unmaps
1648 	 *   it.
1649 	 * - Then it unmaps all shm vmas that started at shmaddr and that
1650 	 *   are within the initially determined size and that are from the
1651 	 *   same shm segment from which we determined the size.
1652 	 * Errors from do_munmap are ignored: the function only fails if
1653 	 * it's called with invalid parameters or if it's called to unmap
1654 	 * a part of a vma. Both calls in this function are for full vmas,
1655 	 * the parameters are directly copied from the vma itself and always
1656 	 * valid - therefore do_munmap cannot fail. (famous last words?)
1657 	 */
1658 	/*
1659 	 * If it had been mremap()'d, the starting address would not
1660 	 * match the usual checks anyway. So assume all vma's are
1661 	 * above the starting address given.
1662 	 */
1663 	vma = find_vma(mm, addr);
1664 
1665 #ifdef CONFIG_MMU
1666 	while (vma) {
1667 		next = vma->vm_next;
1668 
1669 		/*
1670 		 * Check if the starting address would match, i.e. it's
1671 		 * a fragment created by mprotect() and/or munmap(), or it
1672 		 * otherwise it starts at this address with no hassles.
1673 		 */
1674 		if ((vma->vm_ops == &shm_vm_ops) &&
1675 			(vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1676 
1677 			/*
1678 			 * Record the file of the shm segment being
1679 			 * unmapped.  With mremap(), someone could place
1680 			 * page from another segment but with equal offsets
1681 			 * in the range we are unmapping.
1682 			 */
1683 			file = vma->vm_file;
1684 			size = i_size_read(file_inode(vma->vm_file));
1685 			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1686 			/*
1687 			 * We discovered the size of the shm segment, so
1688 			 * break out of here and fall through to the next
1689 			 * loop that uses the size information to stop
1690 			 * searching for matching vma's.
1691 			 */
1692 			retval = 0;
1693 			vma = next;
1694 			break;
1695 		}
1696 		vma = next;
1697 	}
1698 
1699 	/*
1700 	 * We need look no further than the maximum address a fragment
1701 	 * could possibly have landed at. Also cast things to loff_t to
1702 	 * prevent overflows and make comparisons vs. equal-width types.
1703 	 */
1704 	size = PAGE_ALIGN(size);
1705 	while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1706 		next = vma->vm_next;
1707 
1708 		/* finding a matching vma now does not alter retval */
1709 		if ((vma->vm_ops == &shm_vm_ops) &&
1710 		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1711 		    (vma->vm_file == file))
1712 			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1713 		vma = next;
1714 	}
1715 
1716 #else	/* CONFIG_MMU */
1717 	/* under NOMMU conditions, the exact address to be destroyed must be
1718 	 * given
1719 	 */
1720 	if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1721 		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1722 		retval = 0;
1723 	}
1724 
1725 #endif
1726 
1727 	mmap_write_unlock(mm);
1728 	return retval;
1729 }
1730 
1731 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1732 {
1733 	return ksys_shmdt(shmaddr);
1734 }
1735 
1736 #ifdef CONFIG_PROC_FS
1737 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1738 {
1739 	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1740 	struct user_namespace *user_ns = seq_user_ns(s);
1741 	struct kern_ipc_perm *ipcp = it;
1742 	struct shmid_kernel *shp;
1743 	unsigned long rss = 0, swp = 0;
1744 
1745 	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1746 	shm_add_rss_swap(shp, &rss, &swp);
1747 
1748 #if BITS_PER_LONG <= 32
1749 #define SIZE_SPEC "%10lu"
1750 #else
1751 #define SIZE_SPEC "%21lu"
1752 #endif
1753 
1754 	seq_printf(s,
1755 		   "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1756 		   "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1757 		   SIZE_SPEC " " SIZE_SPEC "\n",
1758 		   shp->shm_perm.key,
1759 		   shp->shm_perm.id,
1760 		   shp->shm_perm.mode,
1761 		   shp->shm_segsz,
1762 		   pid_nr_ns(shp->shm_cprid, pid_ns),
1763 		   pid_nr_ns(shp->shm_lprid, pid_ns),
1764 		   shp->shm_nattch,
1765 		   from_kuid_munged(user_ns, shp->shm_perm.uid),
1766 		   from_kgid_munged(user_ns, shp->shm_perm.gid),
1767 		   from_kuid_munged(user_ns, shp->shm_perm.cuid),
1768 		   from_kgid_munged(user_ns, shp->shm_perm.cgid),
1769 		   shp->shm_atim,
1770 		   shp->shm_dtim,
1771 		   shp->shm_ctim,
1772 		   rss * PAGE_SIZE,
1773 		   swp * PAGE_SIZE);
1774 
1775 	return 0;
1776 }
1777 #endif
1778