c38c8425a89eef2afcfabadaade095e8f19ffbf1
[muen/linux.git] / ipc / shm.c
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
51 struct shm_file_data {
52         int id;
53         struct ipc_namespace *ns;
54         struct file *file;
55         const struct vm_operations_struct *vm_ops;
56 };
57
58 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
59
60 static const struct file_operations shm_file_operations;
61 static const struct vm_operations_struct shm_vm_ops;
62
63 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
64
65 #define shm_unlock(shp)                 \
66         ipc_unlock(&(shp)->shm_perm)
67
68 static int newseg(struct ipc_namespace *, struct ipc_params *);
69 static void shm_open(struct vm_area_struct *vma);
70 static void shm_close(struct vm_area_struct *vma);
71 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
72 #ifdef CONFIG_PROC_FS
73 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
74 #endif
75
76 int shm_init_ns(struct ipc_namespace *ns)
77 {
78         ns->shm_ctlmax = SHMMAX;
79         ns->shm_ctlall = SHMALL;
80         ns->shm_ctlmni = SHMMNI;
81         ns->shm_rmid_forced = 0;
82         ns->shm_tot = 0;
83         return ipc_init_ids(&shm_ids(ns));
84 }
85
86 /*
87  * Called with shm_ids.rwsem (writer) and the shp structure locked.
88  * Only shm_ids.rwsem remains locked on exit.
89  */
90 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
91 {
92         struct shmid_kernel *shp;
93
94         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
95
96         if (shp->shm_nattch) {
97                 shp->shm_perm.mode |= SHM_DEST;
98                 /* Do not find it any more */
99                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
100                 shm_unlock(shp);
101         } else
102                 shm_destroy(ns, shp);
103 }
104
105 #ifdef CONFIG_IPC_NS
106 void shm_exit_ns(struct ipc_namespace *ns)
107 {
108         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
109         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
110         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
111 }
112 #endif
113
114 static int __init ipc_ns_init(void)
115 {
116         const int err = shm_init_ns(&init_ipc_ns);
117         WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err);
118         return err;
119 }
120
121 pure_initcall(ipc_ns_init);
122
123 void __init shm_init(void)
124 {
125         ipc_init_proc_interface("sysvipc/shm",
126 #if BITS_PER_LONG <= 32
127                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
128 #else
129                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
130 #endif
131                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
132 }
133
134 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
135 {
136         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
137
138         if (IS_ERR(ipcp))
139                 return ERR_CAST(ipcp);
140
141         return container_of(ipcp, struct shmid_kernel, shm_perm);
142 }
143
144 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
145 {
146         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
147
148         if (IS_ERR(ipcp))
149                 return ERR_CAST(ipcp);
150
151         return container_of(ipcp, struct shmid_kernel, shm_perm);
152 }
153
154 /*
155  * shm_lock_(check_) routines are called in the paths where the rwsem
156  * is not necessarily held.
157  */
158 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
159 {
160         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
161
162         /*
163          * Callers of shm_lock() must validate the status of the returned ipc
164          * object pointer (as returned by ipc_lock()), and error out as
165          * appropriate.
166          */
167         if (IS_ERR(ipcp))
168                 return (void *)ipcp;
169         return container_of(ipcp, struct shmid_kernel, shm_perm);
170 }
171
172 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
173 {
174         rcu_read_lock();
175         ipc_lock_object(&ipcp->shm_perm);
176 }
177
178 static void shm_rcu_free(struct rcu_head *head)
179 {
180         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
181                                                         rcu);
182         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
183                                                         shm_perm);
184         security_shm_free(shp);
185         kvfree(shp);
186 }
187
188 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
189 {
190         list_del(&s->shm_clist);
191         ipc_rmid(&shm_ids(ns), &s->shm_perm);
192 }
193
194
195 static int __shm_open(struct vm_area_struct *vma)
196 {
197         struct file *file = vma->vm_file;
198         struct shm_file_data *sfd = shm_file_data(file);
199         struct shmid_kernel *shp;
200
201         shp = shm_lock(sfd->ns, sfd->id);
202
203         if (IS_ERR(shp))
204                 return PTR_ERR(shp);
205
206         shp->shm_atim = ktime_get_real_seconds();
207         shp->shm_lprid = task_tgid_vnr(current);
208         shp->shm_nattch++;
209         shm_unlock(shp);
210         return 0;
211 }
212
213 /* This is called by fork, once for every shm attach. */
214 static void shm_open(struct vm_area_struct *vma)
215 {
216         int err = __shm_open(vma);
217         /*
218          * We raced in the idr lookup or with shm_destroy().
219          * Either way, the ID is busted.
220          */
221         WARN_ON_ONCE(err);
222 }
223
224 /*
225  * shm_destroy - free the struct shmid_kernel
226  *
227  * @ns: namespace
228  * @shp: struct to free
229  *
230  * It has to be called with shp and shm_ids.rwsem (writer) locked,
231  * but returns with shp unlocked and freed.
232  */
233 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
234 {
235         struct file *shm_file;
236
237         shm_file = shp->shm_file;
238         shp->shm_file = NULL;
239         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
240         shm_rmid(ns, shp);
241         shm_unlock(shp);
242         if (!is_file_hugepages(shm_file))
243                 shmem_lock(shm_file, 0, shp->mlock_user);
244         else if (shp->mlock_user)
245                 user_shm_unlock(i_size_read(file_inode(shm_file)),
246                                 shp->mlock_user);
247         fput(shm_file);
248         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
249 }
250
251 /*
252  * shm_may_destroy - identifies whether shm segment should be destroyed now
253  *
254  * Returns true if and only if there are no active users of the segment and
255  * one of the following is true:
256  *
257  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
258  *
259  * 2) sysctl kernel.shm_rmid_forced is set to 1.
260  */
261 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
262 {
263         return (shp->shm_nattch == 0) &&
264                (ns->shm_rmid_forced ||
265                 (shp->shm_perm.mode & SHM_DEST));
266 }
267
268 /*
269  * remove the attach descriptor vma.
270  * free memory for segment if it is marked destroyed.
271  * The descriptor has already been removed from the current->mm->mmap list
272  * and will later be kfree()d.
273  */
274 static void shm_close(struct vm_area_struct *vma)
275 {
276         struct file *file = vma->vm_file;
277         struct shm_file_data *sfd = shm_file_data(file);
278         struct shmid_kernel *shp;
279         struct ipc_namespace *ns = sfd->ns;
280
281         down_write(&shm_ids(ns).rwsem);
282         /* remove from the list of attaches of the shm segment */
283         shp = shm_lock(ns, sfd->id);
284
285         /*
286          * We raced in the idr lookup or with shm_destroy().
287          * Either way, the ID is busted.
288          */
289         if (WARN_ON_ONCE(IS_ERR(shp)))
290                 goto done; /* no-op */
291
292         shp->shm_lprid = task_tgid_vnr(current);
293         shp->shm_dtim = ktime_get_real_seconds();
294         shp->shm_nattch--;
295         if (shm_may_destroy(ns, shp))
296                 shm_destroy(ns, shp);
297         else
298                 shm_unlock(shp);
299 done:
300         up_write(&shm_ids(ns).rwsem);
301 }
302
303 /* Called with ns->shm_ids(ns).rwsem locked */
304 static int shm_try_destroy_orphaned(int id, void *p, void *data)
305 {
306         struct ipc_namespace *ns = data;
307         struct kern_ipc_perm *ipcp = p;
308         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
309
310         /*
311          * We want to destroy segments without users and with already
312          * exit'ed originating process.
313          *
314          * As shp->* are changed under rwsem, it's safe to skip shp locking.
315          */
316         if (shp->shm_creator != NULL)
317                 return 0;
318
319         if (shm_may_destroy(ns, shp)) {
320                 shm_lock_by_ptr(shp);
321                 shm_destroy(ns, shp);
322         }
323         return 0;
324 }
325
326 void shm_destroy_orphaned(struct ipc_namespace *ns)
327 {
328         down_write(&shm_ids(ns).rwsem);
329         if (shm_ids(ns).in_use)
330                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
331         up_write(&shm_ids(ns).rwsem);
332 }
333
334 /* Locking assumes this will only be called with task == current */
335 void exit_shm(struct task_struct *task)
336 {
337         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
338         struct shmid_kernel *shp, *n;
339
340         if (list_empty(&task->sysvshm.shm_clist))
341                 return;
342
343         /*
344          * If kernel.shm_rmid_forced is not set then only keep track of
345          * which shmids are orphaned, so that a later set of the sysctl
346          * can clean them up.
347          */
348         if (!ns->shm_rmid_forced) {
349                 down_read(&shm_ids(ns).rwsem);
350                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
351                         shp->shm_creator = NULL;
352                 /*
353                  * Only under read lock but we are only called on current
354                  * so no entry on the list will be shared.
355                  */
356                 list_del(&task->sysvshm.shm_clist);
357                 up_read(&shm_ids(ns).rwsem);
358                 return;
359         }
360
361         /*
362          * Destroy all already created segments, that were not yet mapped,
363          * and mark any mapped as orphan to cover the sysctl toggling.
364          * Destroy is skipped if shm_may_destroy() returns false.
365          */
366         down_write(&shm_ids(ns).rwsem);
367         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
368                 shp->shm_creator = NULL;
369
370                 if (shm_may_destroy(ns, shp)) {
371                         shm_lock_by_ptr(shp);
372                         shm_destroy(ns, shp);
373                 }
374         }
375
376         /* Remove the list head from any segments still attached. */
377         list_del(&task->sysvshm.shm_clist);
378         up_write(&shm_ids(ns).rwsem);
379 }
380
381 static int shm_fault(struct vm_fault *vmf)
382 {
383         struct file *file = vmf->vma->vm_file;
384         struct shm_file_data *sfd = shm_file_data(file);
385
386         return sfd->vm_ops->fault(vmf);
387 }
388
389 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
390 {
391         struct file *file = vma->vm_file;
392         struct shm_file_data *sfd = shm_file_data(file);
393
394         if (sfd->vm_ops && sfd->vm_ops->split)
395                 return sfd->vm_ops->split(vma, addr);
396
397         return 0;
398 }
399
400 #ifdef CONFIG_NUMA
401 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
402 {
403         struct file *file = vma->vm_file;
404         struct shm_file_data *sfd = shm_file_data(file);
405         int err = 0;
406
407         if (sfd->vm_ops->set_policy)
408                 err = sfd->vm_ops->set_policy(vma, new);
409         return err;
410 }
411
412 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
413                                         unsigned long addr)
414 {
415         struct file *file = vma->vm_file;
416         struct shm_file_data *sfd = shm_file_data(file);
417         struct mempolicy *pol = NULL;
418
419         if (sfd->vm_ops->get_policy)
420                 pol = sfd->vm_ops->get_policy(vma, addr);
421         else if (vma->vm_policy)
422                 pol = vma->vm_policy;
423
424         return pol;
425 }
426 #endif
427
428 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
429 {
430         struct shm_file_data *sfd = shm_file_data(file);
431         int ret;
432
433         /*
434          * In case of remap_file_pages() emulation, the file can represent
435          * removed IPC ID: propogate shm_lock() error to caller.
436          */
437         ret = __shm_open(vma);
438         if (ret)
439                 return ret;
440
441         ret = call_mmap(sfd->file, vma);
442         if (ret) {
443                 shm_close(vma);
444                 return ret;
445         }
446         sfd->vm_ops = vma->vm_ops;
447 #ifdef CONFIG_MMU
448         WARN_ON(!sfd->vm_ops->fault);
449 #endif
450         vma->vm_ops = &shm_vm_ops;
451         return 0;
452 }
453
454 static int shm_release(struct inode *ino, struct file *file)
455 {
456         struct shm_file_data *sfd = shm_file_data(file);
457
458         put_ipc_ns(sfd->ns);
459         shm_file_data(file) = NULL;
460         kfree(sfd);
461         return 0;
462 }
463
464 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
465 {
466         struct shm_file_data *sfd = shm_file_data(file);
467
468         if (!sfd->file->f_op->fsync)
469                 return -EINVAL;
470         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
471 }
472
473 static long shm_fallocate(struct file *file, int mode, loff_t offset,
474                           loff_t len)
475 {
476         struct shm_file_data *sfd = shm_file_data(file);
477
478         if (!sfd->file->f_op->fallocate)
479                 return -EOPNOTSUPP;
480         return sfd->file->f_op->fallocate(file, mode, offset, len);
481 }
482
483 static unsigned long shm_get_unmapped_area(struct file *file,
484         unsigned long addr, unsigned long len, unsigned long pgoff,
485         unsigned long flags)
486 {
487         struct shm_file_data *sfd = shm_file_data(file);
488
489         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
490                                                 pgoff, flags);
491 }
492
493 static const struct file_operations shm_file_operations = {
494         .mmap           = shm_mmap,
495         .fsync          = shm_fsync,
496         .release        = shm_release,
497         .get_unmapped_area      = shm_get_unmapped_area,
498         .llseek         = noop_llseek,
499         .fallocate      = shm_fallocate,
500 };
501
502 /*
503  * shm_file_operations_huge is now identical to shm_file_operations,
504  * but we keep it distinct for the sake of is_file_shm_hugepages().
505  */
506 static const struct file_operations shm_file_operations_huge = {
507         .mmap           = shm_mmap,
508         .fsync          = shm_fsync,
509         .release        = shm_release,
510         .get_unmapped_area      = shm_get_unmapped_area,
511         .llseek         = noop_llseek,
512         .fallocate      = shm_fallocate,
513 };
514
515 bool is_file_shm_hugepages(struct file *file)
516 {
517         return file->f_op == &shm_file_operations_huge;
518 }
519
520 static const struct vm_operations_struct shm_vm_ops = {
521         .open   = shm_open,     /* callback for a new vm-area open */
522         .close  = shm_close,    /* callback for when the vm-area is released */
523         .fault  = shm_fault,
524         .split  = shm_split,
525 #if defined(CONFIG_NUMA)
526         .set_policy = shm_set_policy,
527         .get_policy = shm_get_policy,
528 #endif
529 };
530
531 /**
532  * newseg - Create a new shared memory segment
533  * @ns: namespace
534  * @params: ptr to the structure that contains key, size and shmflg
535  *
536  * Called with shm_ids.rwsem held as a writer.
537  */
538 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
539 {
540         key_t key = params->key;
541         int shmflg = params->flg;
542         size_t size = params->u.size;
543         int error;
544         struct shmid_kernel *shp;
545         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
546         struct file *file;
547         char name[13];
548         vm_flags_t acctflag = 0;
549
550         if (size < SHMMIN || size > ns->shm_ctlmax)
551                 return -EINVAL;
552
553         if (numpages << PAGE_SHIFT < size)
554                 return -ENOSPC;
555
556         if (ns->shm_tot + numpages < ns->shm_tot ||
557                         ns->shm_tot + numpages > ns->shm_ctlall)
558                 return -ENOSPC;
559
560         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
561         if (unlikely(!shp))
562                 return -ENOMEM;
563
564         shp->shm_perm.key = key;
565         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
566         shp->mlock_user = NULL;
567
568         shp->shm_perm.security = NULL;
569         error = security_shm_alloc(shp);
570         if (error) {
571                 kvfree(shp);
572                 return error;
573         }
574
575         sprintf(name, "SYSV%08x", key);
576         if (shmflg & SHM_HUGETLB) {
577                 struct hstate *hs;
578                 size_t hugesize;
579
580                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
581                 if (!hs) {
582                         error = -EINVAL;
583                         goto no_file;
584                 }
585                 hugesize = ALIGN(size, huge_page_size(hs));
586
587                 /* hugetlb_file_setup applies strict accounting */
588                 if (shmflg & SHM_NORESERVE)
589                         acctflag = VM_NORESERVE;
590                 file = hugetlb_file_setup(name, hugesize, acctflag,
591                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
592                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
593         } else {
594                 /*
595                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
596                  * if it's asked for.
597                  */
598                 if  ((shmflg & SHM_NORESERVE) &&
599                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
600                         acctflag = VM_NORESERVE;
601                 file = shmem_kernel_file_setup(name, size, acctflag);
602         }
603         error = PTR_ERR(file);
604         if (IS_ERR(file))
605                 goto no_file;
606
607         shp->shm_cprid = task_tgid_vnr(current);
608         shp->shm_lprid = 0;
609         shp->shm_atim = shp->shm_dtim = 0;
610         shp->shm_ctim = ktime_get_real_seconds();
611         shp->shm_segsz = size;
612         shp->shm_nattch = 0;
613         shp->shm_file = file;
614         shp->shm_creator = current;
615
616         /* ipc_addid() locks shp upon success. */
617         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
618         if (error < 0)
619                 goto no_id;
620
621         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
622
623         /*
624          * shmid gets reported as "inode#" in /proc/pid/maps.
625          * proc-ps tools use this. Changing this will break them.
626          */
627         file_inode(file)->i_ino = shp->shm_perm.id;
628
629         ns->shm_tot += numpages;
630         error = shp->shm_perm.id;
631
632         ipc_unlock_object(&shp->shm_perm);
633         rcu_read_unlock();
634         return error;
635
636 no_id:
637         if (is_file_hugepages(file) && shp->mlock_user)
638                 user_shm_unlock(size, shp->mlock_user);
639         fput(file);
640 no_file:
641         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
642         return error;
643 }
644
645 /*
646  * Called with shm_ids.rwsem and ipcp locked.
647  */
648 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
649 {
650         struct shmid_kernel *shp;
651
652         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
653         return security_shm_associate(shp, shmflg);
654 }
655
656 /*
657  * Called with shm_ids.rwsem and ipcp locked.
658  */
659 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
660                                 struct ipc_params *params)
661 {
662         struct shmid_kernel *shp;
663
664         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
665         if (shp->shm_segsz < params->u.size)
666                 return -EINVAL;
667
668         return 0;
669 }
670
671 long ksys_shmget(key_t key, size_t size, int shmflg)
672 {
673         struct ipc_namespace *ns;
674         static const struct ipc_ops shm_ops = {
675                 .getnew = newseg,
676                 .associate = shm_security,
677                 .more_checks = shm_more_checks,
678         };
679         struct ipc_params shm_params;
680
681         ns = current->nsproxy->ipc_ns;
682
683         shm_params.key = key;
684         shm_params.flg = shmflg;
685         shm_params.u.size = size;
686
687         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
688 }
689
690 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
691 {
692         return ksys_shmget(key, size, shmflg);
693 }
694
695 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
696 {
697         switch (version) {
698         case IPC_64:
699                 return copy_to_user(buf, in, sizeof(*in));
700         case IPC_OLD:
701             {
702                 struct shmid_ds out;
703
704                 memset(&out, 0, sizeof(out));
705                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
706                 out.shm_segsz   = in->shm_segsz;
707                 out.shm_atime   = in->shm_atime;
708                 out.shm_dtime   = in->shm_dtime;
709                 out.shm_ctime   = in->shm_ctime;
710                 out.shm_cpid    = in->shm_cpid;
711                 out.shm_lpid    = in->shm_lpid;
712                 out.shm_nattch  = in->shm_nattch;
713
714                 return copy_to_user(buf, &out, sizeof(out));
715             }
716         default:
717                 return -EINVAL;
718         }
719 }
720
721 static inline unsigned long
722 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
723 {
724         switch (version) {
725         case IPC_64:
726                 if (copy_from_user(out, buf, sizeof(*out)))
727                         return -EFAULT;
728                 return 0;
729         case IPC_OLD:
730             {
731                 struct shmid_ds tbuf_old;
732
733                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
734                         return -EFAULT;
735
736                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
737                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
738                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
739
740                 return 0;
741             }
742         default:
743                 return -EINVAL;
744         }
745 }
746
747 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
748 {
749         switch (version) {
750         case IPC_64:
751                 return copy_to_user(buf, in, sizeof(*in));
752         case IPC_OLD:
753             {
754                 struct shminfo out;
755
756                 if (in->shmmax > INT_MAX)
757                         out.shmmax = INT_MAX;
758                 else
759                         out.shmmax = (int)in->shmmax;
760
761                 out.shmmin      = in->shmmin;
762                 out.shmmni      = in->shmmni;
763                 out.shmseg      = in->shmseg;
764                 out.shmall      = in->shmall;
765
766                 return copy_to_user(buf, &out, sizeof(out));
767             }
768         default:
769                 return -EINVAL;
770         }
771 }
772
773 /*
774  * Calculate and add used RSS and swap pages of a shm.
775  * Called with shm_ids.rwsem held as a reader
776  */
777 static void shm_add_rss_swap(struct shmid_kernel *shp,
778         unsigned long *rss_add, unsigned long *swp_add)
779 {
780         struct inode *inode;
781
782         inode = file_inode(shp->shm_file);
783
784         if (is_file_hugepages(shp->shm_file)) {
785                 struct address_space *mapping = inode->i_mapping;
786                 struct hstate *h = hstate_file(shp->shm_file);
787                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
788         } else {
789 #ifdef CONFIG_SHMEM
790                 struct shmem_inode_info *info = SHMEM_I(inode);
791
792                 spin_lock_irq(&info->lock);
793                 *rss_add += inode->i_mapping->nrpages;
794                 *swp_add += info->swapped;
795                 spin_unlock_irq(&info->lock);
796 #else
797                 *rss_add += inode->i_mapping->nrpages;
798 #endif
799         }
800 }
801
802 /*
803  * Called with shm_ids.rwsem held as a reader
804  */
805 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
806                 unsigned long *swp)
807 {
808         int next_id;
809         int total, in_use;
810
811         *rss = 0;
812         *swp = 0;
813
814         in_use = shm_ids(ns).in_use;
815
816         for (total = 0, next_id = 0; total < in_use; next_id++) {
817                 struct kern_ipc_perm *ipc;
818                 struct shmid_kernel *shp;
819
820                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
821                 if (ipc == NULL)
822                         continue;
823                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
824
825                 shm_add_rss_swap(shp, rss, swp);
826
827                 total++;
828         }
829 }
830
831 /*
832  * This function handles some shmctl commands which require the rwsem
833  * to be held in write mode.
834  * NOTE: no locks must be held, the rwsem is taken inside this function.
835  */
836 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
837                        struct shmid64_ds *shmid64)
838 {
839         struct kern_ipc_perm *ipcp;
840         struct shmid_kernel *shp;
841         int err;
842
843         down_write(&shm_ids(ns).rwsem);
844         rcu_read_lock();
845
846         ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
847                                       &shmid64->shm_perm, 0);
848         if (IS_ERR(ipcp)) {
849                 err = PTR_ERR(ipcp);
850                 goto out_unlock1;
851         }
852
853         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
854
855         err = security_shm_shmctl(shp, cmd);
856         if (err)
857                 goto out_unlock1;
858
859         switch (cmd) {
860         case IPC_RMID:
861                 ipc_lock_object(&shp->shm_perm);
862                 /* do_shm_rmid unlocks the ipc object and rcu */
863                 do_shm_rmid(ns, ipcp);
864                 goto out_up;
865         case IPC_SET:
866                 ipc_lock_object(&shp->shm_perm);
867                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
868                 if (err)
869                         goto out_unlock0;
870                 shp->shm_ctim = ktime_get_real_seconds();
871                 break;
872         default:
873                 err = -EINVAL;
874                 goto out_unlock1;
875         }
876
877 out_unlock0:
878         ipc_unlock_object(&shp->shm_perm);
879 out_unlock1:
880         rcu_read_unlock();
881 out_up:
882         up_write(&shm_ids(ns).rwsem);
883         return err;
884 }
885
886 static int shmctl_ipc_info(struct ipc_namespace *ns,
887                            struct shminfo64 *shminfo)
888 {
889         int err = security_shm_shmctl(NULL, IPC_INFO);
890         if (!err) {
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                 shminfo->shmmin = SHMMIN;
896                 down_read(&shm_ids(ns).rwsem);
897                 err = ipc_get_maxid(&shm_ids(ns));
898                 up_read(&shm_ids(ns).rwsem);
899                 if (err < 0)
900                         err = 0;
901         }
902         return err;
903 }
904
905 static int shmctl_shm_info(struct ipc_namespace *ns,
906                            struct shm_info *shm_info)
907 {
908         int err = security_shm_shmctl(NULL, SHM_INFO);
909         if (!err) {
910                 memset(shm_info, 0, sizeof(*shm_info));
911                 down_read(&shm_ids(ns).rwsem);
912                 shm_info->used_ids = shm_ids(ns).in_use;
913                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
914                 shm_info->shm_tot = ns->shm_tot;
915                 shm_info->swap_attempts = 0;
916                 shm_info->swap_successes = 0;
917                 err = ipc_get_maxid(&shm_ids(ns));
918                 up_read(&shm_ids(ns).rwsem);
919                 if (err < 0)
920                         err = 0;
921         }
922         return err;
923 }
924
925 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
926                         int cmd, struct shmid64_ds *tbuf)
927 {
928         struct shmid_kernel *shp;
929         int id = 0;
930         int err;
931
932         memset(tbuf, 0, sizeof(*tbuf));
933
934         rcu_read_lock();
935         if (cmd == SHM_STAT) {
936                 shp = shm_obtain_object(ns, shmid);
937                 if (IS_ERR(shp)) {
938                         err = PTR_ERR(shp);
939                         goto out_unlock;
940                 }
941                 id = shp->shm_perm.id;
942         } else {
943                 shp = shm_obtain_object_check(ns, shmid);
944                 if (IS_ERR(shp)) {
945                         err = PTR_ERR(shp);
946                         goto out_unlock;
947                 }
948         }
949
950         err = -EACCES;
951         if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
952                 goto out_unlock;
953
954         err = security_shm_shmctl(shp, cmd);
955         if (err)
956                 goto out_unlock;
957
958         ipc_lock_object(&shp->shm_perm);
959
960         if (!ipc_valid_object(&shp->shm_perm)) {
961                 ipc_unlock_object(&shp->shm_perm);
962                 err = -EIDRM;
963                 goto out_unlock;
964         }
965
966         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
967         tbuf->shm_segsz = shp->shm_segsz;
968         tbuf->shm_atime = shp->shm_atim;
969         tbuf->shm_dtime = shp->shm_dtim;
970         tbuf->shm_ctime = shp->shm_ctim;
971         tbuf->shm_cpid  = shp->shm_cprid;
972         tbuf->shm_lpid  = shp->shm_lprid;
973         tbuf->shm_nattch = shp->shm_nattch;
974
975         ipc_unlock_object(&shp->shm_perm);
976         rcu_read_unlock();
977         return id;
978
979 out_unlock:
980         rcu_read_unlock();
981         return err;
982 }
983
984 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
985 {
986         struct shmid_kernel *shp;
987         struct file *shm_file;
988         int err;
989
990         rcu_read_lock();
991         shp = shm_obtain_object_check(ns, shmid);
992         if (IS_ERR(shp)) {
993                 err = PTR_ERR(shp);
994                 goto out_unlock1;
995         }
996
997         audit_ipc_obj(&(shp->shm_perm));
998         err = security_shm_shmctl(shp, cmd);
999         if (err)
1000                 goto out_unlock1;
1001
1002         ipc_lock_object(&shp->shm_perm);
1003
1004         /* check if shm_destroy() is tearing down shp */
1005         if (!ipc_valid_object(&shp->shm_perm)) {
1006                 err = -EIDRM;
1007                 goto out_unlock0;
1008         }
1009
1010         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1011                 kuid_t euid = current_euid();
1012
1013                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1014                     !uid_eq(euid, shp->shm_perm.cuid)) {
1015                         err = -EPERM;
1016                         goto out_unlock0;
1017                 }
1018                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1019                         err = -EPERM;
1020                         goto out_unlock0;
1021                 }
1022         }
1023
1024         shm_file = shp->shm_file;
1025         if (is_file_hugepages(shm_file))
1026                 goto out_unlock0;
1027
1028         if (cmd == SHM_LOCK) {
1029                 struct user_struct *user = current_user();
1030
1031                 err = shmem_lock(shm_file, 1, user);
1032                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1033                         shp->shm_perm.mode |= SHM_LOCKED;
1034                         shp->mlock_user = user;
1035                 }
1036                 goto out_unlock0;
1037         }
1038
1039         /* SHM_UNLOCK */
1040         if (!(shp->shm_perm.mode & SHM_LOCKED))
1041                 goto out_unlock0;
1042         shmem_lock(shm_file, 0, shp->mlock_user);
1043         shp->shm_perm.mode &= ~SHM_LOCKED;
1044         shp->mlock_user = NULL;
1045         get_file(shm_file);
1046         ipc_unlock_object(&shp->shm_perm);
1047         rcu_read_unlock();
1048         shmem_unlock_mapping(shm_file->f_mapping);
1049
1050         fput(shm_file);
1051         return err;
1052
1053 out_unlock0:
1054         ipc_unlock_object(&shp->shm_perm);
1055 out_unlock1:
1056         rcu_read_unlock();
1057         return err;
1058 }
1059
1060 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1061 {
1062         int err, version;
1063         struct ipc_namespace *ns;
1064         struct shmid64_ds sem64;
1065
1066         if (cmd < 0 || shmid < 0)
1067                 return -EINVAL;
1068
1069         version = ipc_parse_version(&cmd);
1070         ns = current->nsproxy->ipc_ns;
1071
1072         switch (cmd) {
1073         case IPC_INFO: {
1074                 struct shminfo64 shminfo;
1075                 err = shmctl_ipc_info(ns, &shminfo);
1076                 if (err < 0)
1077                         return err;
1078                 if (copy_shminfo_to_user(buf, &shminfo, version))
1079                         err = -EFAULT;
1080                 return err;
1081         }
1082         case SHM_INFO: {
1083                 struct shm_info shm_info;
1084                 err = shmctl_shm_info(ns, &shm_info);
1085                 if (err < 0)
1086                         return err;
1087                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1088                         err = -EFAULT;
1089                 return err;
1090         }
1091         case SHM_STAT:
1092         case IPC_STAT: {
1093                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1094                 if (err < 0)
1095                         return err;
1096                 if (copy_shmid_to_user(buf, &sem64, version))
1097                         err = -EFAULT;
1098                 return err;
1099         }
1100         case IPC_SET:
1101                 if (copy_shmid_from_user(&sem64, buf, version))
1102                         return -EFAULT;
1103                 /* fallthru */
1104         case IPC_RMID:
1105                 return shmctl_down(ns, shmid, cmd, &sem64);
1106         case SHM_LOCK:
1107         case SHM_UNLOCK:
1108                 return shmctl_do_lock(ns, shmid, cmd);
1109         default:
1110                 return -EINVAL;
1111         }
1112 }
1113
1114 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1115 {
1116         return ksys_shmctl(shmid, cmd, buf);
1117 }
1118
1119 #ifdef CONFIG_COMPAT
1120
1121 struct compat_shmid_ds {
1122         struct compat_ipc_perm shm_perm;
1123         int shm_segsz;
1124         compat_time_t shm_atime;
1125         compat_time_t shm_dtime;
1126         compat_time_t shm_ctime;
1127         compat_ipc_pid_t shm_cpid;
1128         compat_ipc_pid_t shm_lpid;
1129         unsigned short shm_nattch;
1130         unsigned short shm_unused;
1131         compat_uptr_t shm_unused2;
1132         compat_uptr_t shm_unused3;
1133 };
1134
1135 struct compat_shminfo64 {
1136         compat_ulong_t shmmax;
1137         compat_ulong_t shmmin;
1138         compat_ulong_t shmmni;
1139         compat_ulong_t shmseg;
1140         compat_ulong_t shmall;
1141         compat_ulong_t __unused1;
1142         compat_ulong_t __unused2;
1143         compat_ulong_t __unused3;
1144         compat_ulong_t __unused4;
1145 };
1146
1147 struct compat_shm_info {
1148         compat_int_t used_ids;
1149         compat_ulong_t shm_tot, shm_rss, shm_swp;
1150         compat_ulong_t swap_attempts, swap_successes;
1151 };
1152
1153 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1154                                         int version)
1155 {
1156         if (in->shmmax > INT_MAX)
1157                 in->shmmax = INT_MAX;
1158         if (version == IPC_64) {
1159                 struct compat_shminfo64 info;
1160                 memset(&info, 0, sizeof(info));
1161                 info.shmmax = in->shmmax;
1162                 info.shmmin = in->shmmin;
1163                 info.shmmni = in->shmmni;
1164                 info.shmseg = in->shmseg;
1165                 info.shmall = in->shmall;
1166                 return copy_to_user(buf, &info, sizeof(info));
1167         } else {
1168                 struct shminfo info;
1169                 memset(&info, 0, sizeof(info));
1170                 info.shmmax = in->shmmax;
1171                 info.shmmin = in->shmmin;
1172                 info.shmmni = in->shmmni;
1173                 info.shmseg = in->shmseg;
1174                 info.shmall = in->shmall;
1175                 return copy_to_user(buf, &info, sizeof(info));
1176         }
1177 }
1178
1179 static int put_compat_shm_info(struct shm_info *ip,
1180                                 struct compat_shm_info __user *uip)
1181 {
1182         struct compat_shm_info info;
1183
1184         memset(&info, 0, sizeof(info));
1185         info.used_ids = ip->used_ids;
1186         info.shm_tot = ip->shm_tot;
1187         info.shm_rss = ip->shm_rss;
1188         info.shm_swp = ip->shm_swp;
1189         info.swap_attempts = ip->swap_attempts;
1190         info.swap_successes = ip->swap_successes;
1191         return copy_to_user(uip, &info, sizeof(info));
1192 }
1193
1194 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1195                                         int version)
1196 {
1197         if (version == IPC_64) {
1198                 struct compat_shmid64_ds v;
1199                 memset(&v, 0, sizeof(v));
1200                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1201                 v.shm_atime = in->shm_atime;
1202                 v.shm_dtime = in->shm_dtime;
1203                 v.shm_ctime = in->shm_ctime;
1204                 v.shm_segsz = in->shm_segsz;
1205                 v.shm_nattch = in->shm_nattch;
1206                 v.shm_cpid = in->shm_cpid;
1207                 v.shm_lpid = in->shm_lpid;
1208                 return copy_to_user(buf, &v, sizeof(v));
1209         } else {
1210                 struct compat_shmid_ds v;
1211                 memset(&v, 0, sizeof(v));
1212                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1213                 v.shm_perm.key = in->shm_perm.key;
1214                 v.shm_atime = in->shm_atime;
1215                 v.shm_dtime = in->shm_dtime;
1216                 v.shm_ctime = in->shm_ctime;
1217                 v.shm_segsz = in->shm_segsz;
1218                 v.shm_nattch = in->shm_nattch;
1219                 v.shm_cpid = in->shm_cpid;
1220                 v.shm_lpid = in->shm_lpid;
1221                 return copy_to_user(buf, &v, sizeof(v));
1222         }
1223 }
1224
1225 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1226                                         int version)
1227 {
1228         memset(out, 0, sizeof(*out));
1229         if (version == IPC_64) {
1230                 struct compat_shmid64_ds __user *p = buf;
1231                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1232         } else {
1233                 struct compat_shmid_ds __user *p = buf;
1234                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1235         }
1236 }
1237
1238 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr)
1239 {
1240         struct ipc_namespace *ns;
1241         struct shmid64_ds sem64;
1242         int version = compat_ipc_parse_version(&cmd);
1243         int err;
1244
1245         ns = current->nsproxy->ipc_ns;
1246
1247         if (cmd < 0 || shmid < 0)
1248                 return -EINVAL;
1249
1250         switch (cmd) {
1251         case IPC_INFO: {
1252                 struct shminfo64 shminfo;
1253                 err = shmctl_ipc_info(ns, &shminfo);
1254                 if (err < 0)
1255                         return err;
1256                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1257                         err = -EFAULT;
1258                 return err;
1259         }
1260         case SHM_INFO: {
1261                 struct shm_info shm_info;
1262                 err = shmctl_shm_info(ns, &shm_info);
1263                 if (err < 0)
1264                         return err;
1265                 if (put_compat_shm_info(&shm_info, uptr))
1266                         err = -EFAULT;
1267                 return err;
1268         }
1269         case IPC_STAT:
1270         case SHM_STAT:
1271                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1272                 if (err < 0)
1273                         return err;
1274                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1275                         err = -EFAULT;
1276                 return err;
1277
1278         case IPC_SET:
1279                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1280                         return -EFAULT;
1281                 /* fallthru */
1282         case IPC_RMID:
1283                 return shmctl_down(ns, shmid, cmd, &sem64);
1284         case SHM_LOCK:
1285         case SHM_UNLOCK:
1286                 return shmctl_do_lock(ns, shmid, cmd);
1287                 break;
1288         default:
1289                 return -EINVAL;
1290         }
1291         return err;
1292 }
1293
1294 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1295 {
1296         return compat_ksys_shmctl(shmid, cmd, uptr);
1297 }
1298 #endif
1299
1300 /*
1301  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1302  *
1303  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1304  * "raddr" thing points to kernel space, and there has to be a wrapper around
1305  * this.
1306  */
1307 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1308               ulong *raddr, unsigned long shmlba)
1309 {
1310         struct shmid_kernel *shp;
1311         unsigned long addr = (unsigned long)shmaddr;
1312         unsigned long size;
1313         struct file *file;
1314         int    err;
1315         unsigned long flags = MAP_SHARED;
1316         unsigned long prot;
1317         int acc_mode;
1318         struct ipc_namespace *ns;
1319         struct shm_file_data *sfd;
1320         struct path path;
1321         fmode_t f_mode;
1322         unsigned long populate = 0;
1323
1324         err = -EINVAL;
1325         if (shmid < 0)
1326                 goto out;
1327
1328         if (addr) {
1329                 if (addr & (shmlba - 1)) {
1330                         /*
1331                          * Round down to the nearest multiple of shmlba.
1332                          * For sane do_mmap_pgoff() parameters, avoid
1333                          * round downs that trigger nil-page and MAP_FIXED.
1334                          */
1335                         if ((shmflg & SHM_RND) && addr >= shmlba)
1336                                 addr &= ~(shmlba - 1);
1337                         else
1338 #ifndef __ARCH_FORCE_SHMLBA
1339                                 if (addr & ~PAGE_MASK)
1340 #endif
1341                                         goto out;
1342                 }
1343
1344                 flags |= MAP_FIXED;
1345         } else if ((shmflg & SHM_REMAP))
1346                 goto out;
1347
1348         if (shmflg & SHM_RDONLY) {
1349                 prot = PROT_READ;
1350                 acc_mode = S_IRUGO;
1351                 f_mode = FMODE_READ;
1352         } else {
1353                 prot = PROT_READ | PROT_WRITE;
1354                 acc_mode = S_IRUGO | S_IWUGO;
1355                 f_mode = FMODE_READ | FMODE_WRITE;
1356         }
1357         if (shmflg & SHM_EXEC) {
1358                 prot |= PROT_EXEC;
1359                 acc_mode |= S_IXUGO;
1360         }
1361
1362         /*
1363          * We cannot rely on the fs check since SYSV IPC does have an
1364          * additional creator id...
1365          */
1366         ns = current->nsproxy->ipc_ns;
1367         rcu_read_lock();
1368         shp = shm_obtain_object_check(ns, shmid);
1369         if (IS_ERR(shp)) {
1370                 err = PTR_ERR(shp);
1371                 goto out_unlock;
1372         }
1373
1374         err = -EACCES;
1375         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1376                 goto out_unlock;
1377
1378         err = security_shm_shmat(shp, shmaddr, shmflg);
1379         if (err)
1380                 goto out_unlock;
1381
1382         ipc_lock_object(&shp->shm_perm);
1383
1384         /* check if shm_destroy() is tearing down shp */
1385         if (!ipc_valid_object(&shp->shm_perm)) {
1386                 ipc_unlock_object(&shp->shm_perm);
1387                 err = -EIDRM;
1388                 goto out_unlock;
1389         }
1390
1391         path = shp->shm_file->f_path;
1392         path_get(&path);
1393         shp->shm_nattch++;
1394         size = i_size_read(d_inode(path.dentry));
1395         ipc_unlock_object(&shp->shm_perm);
1396         rcu_read_unlock();
1397
1398         err = -ENOMEM;
1399         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1400         if (!sfd) {
1401                 path_put(&path);
1402                 goto out_nattch;
1403         }
1404
1405         file = alloc_file(&path, f_mode,
1406                           is_file_hugepages(shp->shm_file) ?
1407                                 &shm_file_operations_huge :
1408                                 &shm_file_operations);
1409         err = PTR_ERR(file);
1410         if (IS_ERR(file)) {
1411                 kfree(sfd);
1412                 path_put(&path);
1413                 goto out_nattch;
1414         }
1415
1416         file->private_data = sfd;
1417         file->f_mapping = shp->shm_file->f_mapping;
1418         sfd->id = shp->shm_perm.id;
1419         sfd->ns = get_ipc_ns(ns);
1420         sfd->file = shp->shm_file;
1421         sfd->vm_ops = NULL;
1422
1423         err = security_mmap_file(file, prot, flags);
1424         if (err)
1425                 goto out_fput;
1426
1427         if (down_write_killable(&current->mm->mmap_sem)) {
1428                 err = -EINTR;
1429                 goto out_fput;
1430         }
1431
1432         if (addr && !(shmflg & SHM_REMAP)) {
1433                 err = -EINVAL;
1434                 if (addr + size < addr)
1435                         goto invalid;
1436
1437                 if (find_vma_intersection(current->mm, addr, addr + size))
1438                         goto invalid;
1439         }
1440
1441         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
1442         *raddr = addr;
1443         err = 0;
1444         if (IS_ERR_VALUE(addr))
1445                 err = (long)addr;
1446 invalid:
1447         up_write(&current->mm->mmap_sem);
1448         if (populate)
1449                 mm_populate(addr, populate);
1450
1451 out_fput:
1452         fput(file);
1453
1454 out_nattch:
1455         down_write(&shm_ids(ns).rwsem);
1456         shp = shm_lock(ns, shmid);
1457         shp->shm_nattch--;
1458         if (shm_may_destroy(ns, shp))
1459                 shm_destroy(ns, shp);
1460         else
1461                 shm_unlock(shp);
1462         up_write(&shm_ids(ns).rwsem);
1463         return err;
1464
1465 out_unlock:
1466         rcu_read_unlock();
1467 out:
1468         return err;
1469 }
1470
1471 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1472 {
1473         unsigned long ret;
1474         long err;
1475
1476         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1477         if (err)
1478                 return err;
1479         force_successful_syscall_return();
1480         return (long)ret;
1481 }
1482
1483 #ifdef CONFIG_COMPAT
1484
1485 #ifndef COMPAT_SHMLBA
1486 #define COMPAT_SHMLBA   SHMLBA
1487 #endif
1488
1489 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1490 {
1491         unsigned long ret;
1492         long err;
1493
1494         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1495         if (err)
1496                 return err;
1497         force_successful_syscall_return();
1498         return (long)ret;
1499 }
1500 #endif
1501
1502 /*
1503  * detach and kill segment if marked destroyed.
1504  * The work is done in shm_close.
1505  */
1506 long ksys_shmdt(char __user *shmaddr)
1507 {
1508         struct mm_struct *mm = current->mm;
1509         struct vm_area_struct *vma;
1510         unsigned long addr = (unsigned long)shmaddr;
1511         int retval = -EINVAL;
1512 #ifdef CONFIG_MMU
1513         loff_t size = 0;
1514         struct file *file;
1515         struct vm_area_struct *next;
1516 #endif
1517
1518         if (addr & ~PAGE_MASK)
1519                 return retval;
1520
1521         if (down_write_killable(&mm->mmap_sem))
1522                 return -EINTR;
1523
1524         /*
1525          * This function tries to be smart and unmap shm segments that
1526          * were modified by partial mlock or munmap calls:
1527          * - It first determines the size of the shm segment that should be
1528          *   unmapped: It searches for a vma that is backed by shm and that
1529          *   started at address shmaddr. It records it's size and then unmaps
1530          *   it.
1531          * - Then it unmaps all shm vmas that started at shmaddr and that
1532          *   are within the initially determined size and that are from the
1533          *   same shm segment from which we determined the size.
1534          * Errors from do_munmap are ignored: the function only fails if
1535          * it's called with invalid parameters or if it's called to unmap
1536          * a part of a vma. Both calls in this function are for full vmas,
1537          * the parameters are directly copied from the vma itself and always
1538          * valid - therefore do_munmap cannot fail. (famous last words?)
1539          */
1540         /*
1541          * If it had been mremap()'d, the starting address would not
1542          * match the usual checks anyway. So assume all vma's are
1543          * above the starting address given.
1544          */
1545         vma = find_vma(mm, addr);
1546
1547 #ifdef CONFIG_MMU
1548         while (vma) {
1549                 next = vma->vm_next;
1550
1551                 /*
1552                  * Check if the starting address would match, i.e. it's
1553                  * a fragment created by mprotect() and/or munmap(), or it
1554                  * otherwise it starts at this address with no hassles.
1555                  */
1556                 if ((vma->vm_ops == &shm_vm_ops) &&
1557                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1558
1559                         /*
1560                          * Record the file of the shm segment being
1561                          * unmapped.  With mremap(), someone could place
1562                          * page from another segment but with equal offsets
1563                          * in the range we are unmapping.
1564                          */
1565                         file = vma->vm_file;
1566                         size = i_size_read(file_inode(vma->vm_file));
1567                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1568                         /*
1569                          * We discovered the size of the shm segment, so
1570                          * break out of here and fall through to the next
1571                          * loop that uses the size information to stop
1572                          * searching for matching vma's.
1573                          */
1574                         retval = 0;
1575                         vma = next;
1576                         break;
1577                 }
1578                 vma = next;
1579         }
1580
1581         /*
1582          * We need look no further than the maximum address a fragment
1583          * could possibly have landed at. Also cast things to loff_t to
1584          * prevent overflows and make comparisons vs. equal-width types.
1585          */
1586         size = PAGE_ALIGN(size);
1587         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1588                 next = vma->vm_next;
1589
1590                 /* finding a matching vma now does not alter retval */
1591                 if ((vma->vm_ops == &shm_vm_ops) &&
1592                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1593                     (vma->vm_file == file))
1594                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1595                 vma = next;
1596         }
1597
1598 #else   /* CONFIG_MMU */
1599         /* under NOMMU conditions, the exact address to be destroyed must be
1600          * given
1601          */
1602         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1603                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1604                 retval = 0;
1605         }
1606
1607 #endif
1608
1609         up_write(&mm->mmap_sem);
1610         return retval;
1611 }
1612
1613 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1614 {
1615         return ksys_shmdt(shmaddr);
1616 }
1617
1618 #ifdef CONFIG_PROC_FS
1619 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1620 {
1621         struct user_namespace *user_ns = seq_user_ns(s);
1622         struct kern_ipc_perm *ipcp = it;
1623         struct shmid_kernel *shp;
1624         unsigned long rss = 0, swp = 0;
1625
1626         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1627         shm_add_rss_swap(shp, &rss, &swp);
1628
1629 #if BITS_PER_LONG <= 32
1630 #define SIZE_SPEC "%10lu"
1631 #else
1632 #define SIZE_SPEC "%21lu"
1633 #endif
1634
1635         seq_printf(s,
1636                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1637                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1638                    SIZE_SPEC " " SIZE_SPEC "\n",
1639                    shp->shm_perm.key,
1640                    shp->shm_perm.id,
1641                    shp->shm_perm.mode,
1642                    shp->shm_segsz,
1643                    shp->shm_cprid,
1644                    shp->shm_lprid,
1645                    shp->shm_nattch,
1646                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1647                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1648                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1649                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1650                    shp->shm_atim,
1651                    shp->shm_dtim,
1652                    shp->shm_ctim,
1653                    rss * PAGE_SIZE,
1654                    swp * PAGE_SIZE);
1655
1656         return 0;
1657 }
1658 #endif