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