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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
50 struct 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
59 static const struct file_operations shm_file_operations;
60 static 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
67 static int newseg(struct ipc_namespace *, struct ipc_params *);
68 static void shm_open(struct vm_area_struct *vma);
69 static void shm_close(struct vm_area_struct *vma);
70 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
71 #ifdef CONFIG_PROC_FS
72 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
73 #endif
74
75 void 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  */
89 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
90 {
91         struct shmid_kernel *shp;
92         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
93
94         if (shp->shm_nattch) {
95                 shp->shm_perm.mode |= SHM_DEST;
96                 /* Do not find it any more */
97                 shp->shm_perm.key = IPC_PRIVATE;
98                 shm_unlock(shp);
99         } else
100                 shm_destroy(ns, shp);
101 }
102
103 #ifdef CONFIG_IPC_NS
104 void shm_exit_ns(struct ipc_namespace *ns)
105 {
106         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
107         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
108 }
109 #endif
110
111 static int __init ipc_ns_init(void)
112 {
113         shm_init_ns(&init_ipc_ns);
114         return 0;
115 }
116
117 pure_initcall(ipc_ns_init);
118
119 void __init shm_init(void)
120 {
121         ipc_init_proc_interface("sysvipc/shm",
122 #if BITS_PER_LONG <= 32
123                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
124 #else
125                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
126 #endif
127                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
128 }
129
130 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
131 {
132         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
133
134         if (IS_ERR(ipcp))
135                 return ERR_CAST(ipcp);
136
137         return container_of(ipcp, struct shmid_kernel, shm_perm);
138 }
139
140 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
141 {
142         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
143
144         if (IS_ERR(ipcp))
145                 return ERR_CAST(ipcp);
146
147         return container_of(ipcp, struct shmid_kernel, shm_perm);
148 }
149
150 /*
151  * shm_lock_(check_) routines are called in the paths where the rwsem
152  * is not necessarily held.
153  */
154 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
155 {
156         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
157
158         /*
159          * We raced in the idr lookup or with shm_destroy().  Either way, the
160          * ID is busted.
161          */
162         BUG_ON(IS_ERR(ipcp));
163
164         return container_of(ipcp, struct shmid_kernel, shm_perm);
165 }
166
167 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
168 {
169         rcu_read_lock();
170         ipc_lock_object(&ipcp->shm_perm);
171 }
172
173 static void shm_rcu_free(struct rcu_head *head)
174 {
175         struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
176         struct shmid_kernel *shp = ipc_rcu_to_struct(p);
177
178         security_shm_free(shp);
179         ipc_rcu_free(head);
180 }
181
182 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
183 {
184         list_del(&s->shm_clist);
185         ipc_rmid(&shm_ids(ns), &s->shm_perm);
186 }
187
188
189 /* This is called by fork, once for every shm attach. */
190 static void shm_open(struct vm_area_struct *vma)
191 {
192         struct file *file = vma->vm_file;
193         struct shm_file_data *sfd = shm_file_data(file);
194         struct shmid_kernel *shp;
195
196         shp = shm_lock(sfd->ns, sfd->id);
197         shp->shm_atim = get_seconds();
198         shp->shm_lprid = task_tgid_vnr(current);
199         shp->shm_nattch++;
200         shm_unlock(shp);
201 }
202
203 /*
204  * shm_destroy - free the struct shmid_kernel
205  *
206  * @ns: namespace
207  * @shp: struct to free
208  *
209  * It has to be called with shp and shm_ids.rwsem (writer) locked,
210  * but returns with shp unlocked and freed.
211  */
212 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
213 {
214         struct file *shm_file;
215
216         shm_file = shp->shm_file;
217         shp->shm_file = NULL;
218         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
219         shm_rmid(ns, shp);
220         shm_unlock(shp);
221         if (!is_file_hugepages(shm_file))
222                 shmem_lock(shm_file, 0, shp->mlock_user);
223         else if (shp->mlock_user)
224                 user_shm_unlock(i_size_read(file_inode(shm_file)),
225                                 shp->mlock_user);
226         fput(shm_file);
227         ipc_rcu_putref(shp, shm_rcu_free);
228 }
229
230 /*
231  * shm_may_destroy - identifies whether shm segment should be destroyed now
232  *
233  * Returns true if and only if there are no active users of the segment and
234  * one of the following is true:
235  *
236  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
237  *
238  * 2) sysctl kernel.shm_rmid_forced is set to 1.
239  */
240 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
241 {
242         return (shp->shm_nattch == 0) &&
243                (ns->shm_rmid_forced ||
244                 (shp->shm_perm.mode & SHM_DEST));
245 }
246
247 /*
248  * remove the attach descriptor vma.
249  * free memory for segment if it is marked destroyed.
250  * The descriptor has already been removed from the current->mm->mmap list
251  * and will later be kfree()d.
252  */
253 static void shm_close(struct vm_area_struct *vma)
254 {
255         struct file *file = vma->vm_file;
256         struct shm_file_data *sfd = shm_file_data(file);
257         struct shmid_kernel *shp;
258         struct ipc_namespace *ns = sfd->ns;
259
260         down_write(&shm_ids(ns).rwsem);
261         /* remove from the list of attaches of the shm segment */
262         shp = shm_lock(ns, sfd->id);
263         shp->shm_lprid = task_tgid_vnr(current);
264         shp->shm_dtim = get_seconds();
265         shp->shm_nattch--;
266         if (shm_may_destroy(ns, shp))
267                 shm_destroy(ns, shp);
268         else
269                 shm_unlock(shp);
270         up_write(&shm_ids(ns).rwsem);
271 }
272
273 /* Called with ns->shm_ids(ns).rwsem locked */
274 static int shm_try_destroy_orphaned(int id, void *p, void *data)
275 {
276         struct ipc_namespace *ns = data;
277         struct kern_ipc_perm *ipcp = p;
278         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
279
280         /*
281          * We want to destroy segments without users and with already
282          * exit'ed originating process.
283          *
284          * As shp->* are changed under rwsem, it's safe to skip shp locking.
285          */
286         if (shp->shm_creator != NULL)
287                 return 0;
288
289         if (shm_may_destroy(ns, shp)) {
290                 shm_lock_by_ptr(shp);
291                 shm_destroy(ns, shp);
292         }
293         return 0;
294 }
295
296 void shm_destroy_orphaned(struct ipc_namespace *ns)
297 {
298         down_write(&shm_ids(ns).rwsem);
299         if (shm_ids(ns).in_use)
300                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
301         up_write(&shm_ids(ns).rwsem);
302 }
303
304 /* Locking assumes this will only be called with task == current */
305 void exit_shm(struct task_struct *task)
306 {
307         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
308         struct shmid_kernel *shp, *n;
309
310         if (list_empty(&task->sysvshm.shm_clist))
311                 return;
312
313         /*
314          * If kernel.shm_rmid_forced is not set then only keep track of
315          * which shmids are orphaned, so that a later set of the sysctl
316          * can clean them up.
317          */
318         if (!ns->shm_rmid_forced) {
319                 down_read(&shm_ids(ns).rwsem);
320                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
321                         shp->shm_creator = NULL;
322                 /*
323                  * Only under read lock but we are only called on current
324                  * so no entry on the list will be shared.
325                  */
326                 list_del(&task->sysvshm.shm_clist);
327                 up_read(&shm_ids(ns).rwsem);
328                 return;
329         }
330
331         /*
332          * Destroy all already created segments, that were not yet mapped,
333          * and mark any mapped as orphan to cover the sysctl toggling.
334          * Destroy is skipped if shm_may_destroy() returns false.
335          */
336         down_write(&shm_ids(ns).rwsem);
337         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
338                 shp->shm_creator = NULL;
339
340                 if (shm_may_destroy(ns, shp)) {
341                         shm_lock_by_ptr(shp);
342                         shm_destroy(ns, shp);
343                 }
344         }
345
346         /* Remove the list head from any segments still attached. */
347         list_del(&task->sysvshm.shm_clist);
348         up_write(&shm_ids(ns).rwsem);
349 }
350
351 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
352 {
353         struct file *file = vma->vm_file;
354         struct shm_file_data *sfd = shm_file_data(file);
355
356         return sfd->vm_ops->fault(vma, vmf);
357 }
358
359 #ifdef CONFIG_NUMA
360 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
361 {
362         struct file *file = vma->vm_file;
363         struct shm_file_data *sfd = shm_file_data(file);
364         int err = 0;
365         if (sfd->vm_ops->set_policy)
366                 err = sfd->vm_ops->set_policy(vma, new);
367         return err;
368 }
369
370 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
371                                         unsigned long addr)
372 {
373         struct file *file = vma->vm_file;
374         struct shm_file_data *sfd = shm_file_data(file);
375         struct mempolicy *pol = NULL;
376
377         if (sfd->vm_ops->get_policy)
378                 pol = sfd->vm_ops->get_policy(vma, addr);
379         else if (vma->vm_policy)
380                 pol = vma->vm_policy;
381
382         return pol;
383 }
384 #endif
385
386 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
387 {
388         struct shm_file_data *sfd = shm_file_data(file);
389         int ret;
390
391         ret = sfd->file->f_op->mmap(sfd->file, vma);
392         if (ret != 0)
393                 return ret;
394         sfd->vm_ops = vma->vm_ops;
395 #ifdef CONFIG_MMU
396         BUG_ON(!sfd->vm_ops->fault);
397 #endif
398         vma->vm_ops = &shm_vm_ops;
399         shm_open(vma);
400
401         return ret;
402 }
403
404 static int shm_release(struct inode *ino, struct file *file)
405 {
406         struct shm_file_data *sfd = shm_file_data(file);
407
408         put_ipc_ns(sfd->ns);
409         shm_file_data(file) = NULL;
410         kfree(sfd);
411         return 0;
412 }
413
414 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
415 {
416         struct shm_file_data *sfd = shm_file_data(file);
417
418         if (!sfd->file->f_op->fsync)
419                 return -EINVAL;
420         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
421 }
422
423 static long shm_fallocate(struct file *file, int mode, loff_t offset,
424                           loff_t len)
425 {
426         struct shm_file_data *sfd = shm_file_data(file);
427
428         if (!sfd->file->f_op->fallocate)
429                 return -EOPNOTSUPP;
430         return sfd->file->f_op->fallocate(file, mode, offset, len);
431 }
432
433 static unsigned long shm_get_unmapped_area(struct file *file,
434         unsigned long addr, unsigned long len, unsigned long pgoff,
435         unsigned long flags)
436 {
437         struct shm_file_data *sfd = shm_file_data(file);
438         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
439                                                 pgoff, flags);
440 }
441
442 static const struct file_operations shm_file_operations = {
443         .mmap           = shm_mmap,
444         .fsync          = shm_fsync,
445         .release        = shm_release,
446 #ifndef CONFIG_MMU
447         .get_unmapped_area      = shm_get_unmapped_area,
448 #endif
449         .llseek         = noop_llseek,
450         .fallocate      = shm_fallocate,
451 };
452
453 static const struct file_operations shm_file_operations_huge = {
454         .mmap           = shm_mmap,
455         .fsync          = shm_fsync,
456         .release        = shm_release,
457         .get_unmapped_area      = shm_get_unmapped_area,
458         .llseek         = noop_llseek,
459         .fallocate      = shm_fallocate,
460 };
461
462 int is_file_shm_hugepages(struct file *file)
463 {
464         return file->f_op == &shm_file_operations_huge;
465 }
466
467 static const struct vm_operations_struct shm_vm_ops = {
468         .open   = shm_open,     /* callback for a new vm-area open */
469         .close  = shm_close,    /* callback for when the vm-area is released */
470         .fault  = shm_fault,
471 #if defined(CONFIG_NUMA)
472         .set_policy = shm_set_policy,
473         .get_policy = shm_get_policy,
474 #endif
475 };
476
477 /**
478  * newseg - Create a new shared memory segment
479  * @ns: namespace
480  * @params: ptr to the structure that contains key, size and shmflg
481  *
482  * Called with shm_ids.rwsem held as a writer.
483  */
484 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
485 {
486         key_t key = params->key;
487         int shmflg = params->flg;
488         size_t size = params->u.size;
489         int error;
490         struct shmid_kernel *shp;
491         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
492         struct file *file;
493         char name[13];
494         int id;
495         vm_flags_t acctflag = 0;
496
497         if (size < SHMMIN || size > ns->shm_ctlmax)
498                 return -EINVAL;
499
500         if (numpages << PAGE_SHIFT < size)
501                 return -ENOSPC;
502
503         if (ns->shm_tot + numpages < ns->shm_tot ||
504                         ns->shm_tot + numpages > ns->shm_ctlall)
505                 return -ENOSPC;
506
507         shp = ipc_rcu_alloc(sizeof(*shp));
508         if (!shp)
509                 return -ENOMEM;
510
511         shp->shm_perm.key = key;
512         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
513         shp->mlock_user = NULL;
514
515         shp->shm_perm.security = NULL;
516         error = security_shm_alloc(shp);
517         if (error) {
518                 ipc_rcu_putref(shp, ipc_rcu_free);
519                 return error;
520         }
521
522         sprintf(name, "SYSV%08x", key);
523         if (shmflg & SHM_HUGETLB) {
524                 struct hstate *hs;
525                 size_t hugesize;
526
527                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
528                 if (!hs) {
529                         error = -EINVAL;
530                         goto no_file;
531                 }
532                 hugesize = ALIGN(size, huge_page_size(hs));
533
534                 /* hugetlb_file_setup applies strict accounting */
535                 if (shmflg & SHM_NORESERVE)
536                         acctflag = VM_NORESERVE;
537                 file = hugetlb_file_setup(name, hugesize, acctflag,
538                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
539                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
540         } else {
541                 /*
542                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
543                  * if it's asked for.
544                  */
545                 if  ((shmflg & SHM_NORESERVE) &&
546                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
547                         acctflag = VM_NORESERVE;
548                 file = shmem_file_setup(name, size, acctflag);
549         }
550         error = PTR_ERR(file);
551         if (IS_ERR(file))
552                 goto no_file;
553
554         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
555         if (id < 0) {
556                 error = id;
557                 goto no_id;
558         }
559
560         shp->shm_cprid = task_tgid_vnr(current);
561         shp->shm_lprid = 0;
562         shp->shm_atim = shp->shm_dtim = 0;
563         shp->shm_ctim = get_seconds();
564         shp->shm_segsz = size;
565         shp->shm_nattch = 0;
566         shp->shm_file = file;
567         shp->shm_creator = current;
568         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
569
570         /*
571          * shmid gets reported as "inode#" in /proc/pid/maps.
572          * proc-ps tools use this. Changing this will break them.
573          */
574         file_inode(file)->i_ino = shp->shm_perm.id;
575
576         ns->shm_tot += numpages;
577         error = shp->shm_perm.id;
578
579         ipc_unlock_object(&shp->shm_perm);
580         rcu_read_unlock();
581         return error;
582
583 no_id:
584         if (is_file_hugepages(file) && shp->mlock_user)
585                 user_shm_unlock(size, shp->mlock_user);
586         fput(file);
587 no_file:
588         ipc_rcu_putref(shp, shm_rcu_free);
589         return error;
590 }
591
592 /*
593  * Called with shm_ids.rwsem and ipcp locked.
594  */
595 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
596 {
597         struct shmid_kernel *shp;
598
599         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
600         return security_shm_associate(shp, shmflg);
601 }
602
603 /*
604  * Called with shm_ids.rwsem and ipcp locked.
605  */
606 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
607                                 struct ipc_params *params)
608 {
609         struct shmid_kernel *shp;
610
611         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
612         if (shp->shm_segsz < params->u.size)
613                 return -EINVAL;
614
615         return 0;
616 }
617
618 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
619 {
620         struct ipc_namespace *ns;
621         static const struct ipc_ops shm_ops = {
622                 .getnew = newseg,
623                 .associate = shm_security,
624                 .more_checks = shm_more_checks,
625         };
626         struct ipc_params shm_params;
627
628         ns = current->nsproxy->ipc_ns;
629
630         shm_params.key = key;
631         shm_params.flg = shmflg;
632         shm_params.u.size = size;
633
634         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
635 }
636
637 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
638 {
639         switch (version) {
640         case IPC_64:
641                 return copy_to_user(buf, in, sizeof(*in));
642         case IPC_OLD:
643             {
644                 struct shmid_ds out;
645
646                 memset(&out, 0, sizeof(out));
647                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
648                 out.shm_segsz   = in->shm_segsz;
649                 out.shm_atime   = in->shm_atime;
650                 out.shm_dtime   = in->shm_dtime;
651                 out.shm_ctime   = in->shm_ctime;
652                 out.shm_cpid    = in->shm_cpid;
653                 out.shm_lpid    = in->shm_lpid;
654                 out.shm_nattch  = in->shm_nattch;
655
656                 return copy_to_user(buf, &out, sizeof(out));
657             }
658         default:
659                 return -EINVAL;
660         }
661 }
662
663 static inline unsigned long
664 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
665 {
666         switch (version) {
667         case IPC_64:
668                 if (copy_from_user(out, buf, sizeof(*out)))
669                         return -EFAULT;
670                 return 0;
671         case IPC_OLD:
672             {
673                 struct shmid_ds tbuf_old;
674
675                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
676                         return -EFAULT;
677
678                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
679                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
680                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
681
682                 return 0;
683             }
684         default:
685                 return -EINVAL;
686         }
687 }
688
689 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
690 {
691         switch (version) {
692         case IPC_64:
693                 return copy_to_user(buf, in, sizeof(*in));
694         case IPC_OLD:
695             {
696                 struct shminfo out;
697
698                 if (in->shmmax > INT_MAX)
699                         out.shmmax = INT_MAX;
700                 else
701                         out.shmmax = (int)in->shmmax;
702
703                 out.shmmin      = in->shmmin;
704                 out.shmmni      = in->shmmni;
705                 out.shmseg      = in->shmseg;
706                 out.shmall      = in->shmall;
707
708                 return copy_to_user(buf, &out, sizeof(out));
709             }
710         default:
711                 return -EINVAL;
712         }
713 }
714
715 /*
716  * Calculate and add used RSS and swap pages of a shm.
717  * Called with shm_ids.rwsem held as a reader
718  */
719 static void shm_add_rss_swap(struct shmid_kernel *shp,
720         unsigned long *rss_add, unsigned long *swp_add)
721 {
722         struct inode *inode;
723
724         inode = file_inode(shp->shm_file);
725
726         if (is_file_hugepages(shp->shm_file)) {
727                 struct address_space *mapping = inode->i_mapping;
728                 struct hstate *h = hstate_file(shp->shm_file);
729                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
730         } else {
731 #ifdef CONFIG_SHMEM
732                 struct shmem_inode_info *info = SHMEM_I(inode);
733                 spin_lock(&info->lock);
734                 *rss_add += inode->i_mapping->nrpages;
735                 *swp_add += info->swapped;
736                 spin_unlock(&info->lock);
737 #else
738                 *rss_add += inode->i_mapping->nrpages;
739 #endif
740         }
741 }
742
743 /*
744  * Called with shm_ids.rwsem held as a reader
745  */
746 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
747                 unsigned long *swp)
748 {
749         int next_id;
750         int total, in_use;
751
752         *rss = 0;
753         *swp = 0;
754
755         in_use = shm_ids(ns).in_use;
756
757         for (total = 0, next_id = 0; total < in_use; next_id++) {
758                 struct kern_ipc_perm *ipc;
759                 struct shmid_kernel *shp;
760
761                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
762                 if (ipc == NULL)
763                         continue;
764                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
765
766                 shm_add_rss_swap(shp, rss, swp);
767
768                 total++;
769         }
770 }
771
772 /*
773  * This function handles some shmctl commands which require the rwsem
774  * to be held in write mode.
775  * NOTE: no locks must be held, the rwsem is taken inside this function.
776  */
777 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
778                        struct shmid_ds __user *buf, int version)
779 {
780         struct kern_ipc_perm *ipcp;
781         struct shmid64_ds shmid64;
782         struct shmid_kernel *shp;
783         int err;
784
785         if (cmd == IPC_SET) {
786                 if (copy_shmid_from_user(&shmid64, buf, version))
787                         return -EFAULT;
788         }
789
790         down_write(&shm_ids(ns).rwsem);
791         rcu_read_lock();
792
793         ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
794                                       &shmid64.shm_perm, 0);
795         if (IS_ERR(ipcp)) {
796                 err = PTR_ERR(ipcp);
797                 goto out_unlock1;
798         }
799
800         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
801
802         err = security_shm_shmctl(shp, cmd);
803         if (err)
804                 goto out_unlock1;
805
806         switch (cmd) {
807         case IPC_RMID:
808                 ipc_lock_object(&shp->shm_perm);
809                 /* do_shm_rmid unlocks the ipc object and rcu */
810                 do_shm_rmid(ns, ipcp);
811                 goto out_up;
812         case IPC_SET:
813                 ipc_lock_object(&shp->shm_perm);
814                 err = ipc_update_perm(&shmid64.shm_perm, ipcp);
815                 if (err)
816                         goto out_unlock0;
817                 shp->shm_ctim = get_seconds();
818                 break;
819         default:
820                 err = -EINVAL;
821                 goto out_unlock1;
822         }
823
824 out_unlock0:
825         ipc_unlock_object(&shp->shm_perm);
826 out_unlock1:
827         rcu_read_unlock();
828 out_up:
829         up_write(&shm_ids(ns).rwsem);
830         return err;
831 }
832
833 static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
834                          int cmd, int version, void __user *buf)
835 {
836         int err;
837         struct shmid_kernel *shp;
838
839         /* preliminary security checks for *_INFO */
840         if (cmd == IPC_INFO || cmd == SHM_INFO) {
841                 err = security_shm_shmctl(NULL, cmd);
842                 if (err)
843                         return err;
844         }
845
846         switch (cmd) {
847         case IPC_INFO:
848         {
849                 struct shminfo64 shminfo;
850
851                 memset(&shminfo, 0, sizeof(shminfo));
852                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
853                 shminfo.shmmax = ns->shm_ctlmax;
854                 shminfo.shmall = ns->shm_ctlall;
855
856                 shminfo.shmmin = SHMMIN;
857                 if (copy_shminfo_to_user(buf, &shminfo, version))
858                         return -EFAULT;
859
860                 down_read(&shm_ids(ns).rwsem);
861                 err = ipc_get_maxid(&shm_ids(ns));
862                 up_read(&shm_ids(ns).rwsem);
863
864                 if (err < 0)
865                         err = 0;
866                 goto out;
867         }
868         case SHM_INFO:
869         {
870                 struct shm_info shm_info;
871
872                 memset(&shm_info, 0, sizeof(shm_info));
873                 down_read(&shm_ids(ns).rwsem);
874                 shm_info.used_ids = shm_ids(ns).in_use;
875                 shm_get_stat(ns, &shm_info.shm_rss, &shm_info.shm_swp);
876                 shm_info.shm_tot = ns->shm_tot;
877                 shm_info.swap_attempts = 0;
878                 shm_info.swap_successes = 0;
879                 err = ipc_get_maxid(&shm_ids(ns));
880                 up_read(&shm_ids(ns).rwsem);
881                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
882                         err = -EFAULT;
883                         goto out;
884                 }
885
886                 err = err < 0 ? 0 : err;
887                 goto out;
888         }
889         case SHM_STAT:
890         case IPC_STAT:
891         {
892                 struct shmid64_ds tbuf;
893                 int result;
894
895                 rcu_read_lock();
896                 if (cmd == SHM_STAT) {
897                         shp = shm_obtain_object(ns, shmid);
898                         if (IS_ERR(shp)) {
899                                 err = PTR_ERR(shp);
900                                 goto out_unlock;
901                         }
902                         result = shp->shm_perm.id;
903                 } else {
904                         shp = shm_obtain_object_check(ns, shmid);
905                         if (IS_ERR(shp)) {
906                                 err = PTR_ERR(shp);
907                                 goto out_unlock;
908                         }
909                         result = 0;
910                 }
911
912                 err = -EACCES;
913                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
914                         goto out_unlock;
915
916                 err = security_shm_shmctl(shp, cmd);
917                 if (err)
918                         goto out_unlock;
919
920                 memset(&tbuf, 0, sizeof(tbuf));
921                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
922                 tbuf.shm_segsz  = shp->shm_segsz;
923                 tbuf.shm_atime  = shp->shm_atim;
924                 tbuf.shm_dtime  = shp->shm_dtim;
925                 tbuf.shm_ctime  = shp->shm_ctim;
926                 tbuf.shm_cpid   = shp->shm_cprid;
927                 tbuf.shm_lpid   = shp->shm_lprid;
928                 tbuf.shm_nattch = shp->shm_nattch;
929                 rcu_read_unlock();
930
931                 if (copy_shmid_to_user(buf, &tbuf, version))
932                         err = -EFAULT;
933                 else
934                         err = result;
935                 goto out;
936         }
937         default:
938                 return -EINVAL;
939         }
940
941 out_unlock:
942         rcu_read_unlock();
943 out:
944         return err;
945 }
946
947 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
948 {
949         struct shmid_kernel *shp;
950         int err, version;
951         struct ipc_namespace *ns;
952
953         if (cmd < 0 || shmid < 0)
954                 return -EINVAL;
955
956         version = ipc_parse_version(&cmd);
957         ns = current->nsproxy->ipc_ns;
958
959         switch (cmd) {
960         case IPC_INFO:
961         case SHM_INFO:
962         case SHM_STAT:
963         case IPC_STAT:
964                 return shmctl_nolock(ns, shmid, cmd, version, buf);
965         case IPC_RMID:
966         case IPC_SET:
967                 return shmctl_down(ns, shmid, cmd, buf, version);
968         case SHM_LOCK:
969         case SHM_UNLOCK:
970         {
971                 struct file *shm_file;
972
973                 rcu_read_lock();
974                 shp = shm_obtain_object_check(ns, shmid);
975                 if (IS_ERR(shp)) {
976                         err = PTR_ERR(shp);
977                         goto out_unlock1;
978                 }
979
980                 audit_ipc_obj(&(shp->shm_perm));
981                 err = security_shm_shmctl(shp, cmd);
982                 if (err)
983                         goto out_unlock1;
984
985                 ipc_lock_object(&shp->shm_perm);
986
987                 /* check if shm_destroy() is tearing down shp */
988                 if (!ipc_valid_object(&shp->shm_perm)) {
989                         err = -EIDRM;
990                         goto out_unlock0;
991                 }
992
993                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
994                         kuid_t euid = current_euid();
995                         if (!uid_eq(euid, shp->shm_perm.uid) &&
996                             !uid_eq(euid, shp->shm_perm.cuid)) {
997                                 err = -EPERM;
998                                 goto out_unlock0;
999                         }
1000                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1001                                 err = -EPERM;
1002                                 goto out_unlock0;
1003                         }
1004                 }
1005
1006                 shm_file = shp->shm_file;
1007                 if (is_file_hugepages(shm_file))
1008                         goto out_unlock0;
1009
1010                 if (cmd == SHM_LOCK) {
1011                         struct user_struct *user = current_user();
1012                         err = shmem_lock(shm_file, 1, user);
1013                         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1014                                 shp->shm_perm.mode |= SHM_LOCKED;
1015                                 shp->mlock_user = user;
1016                         }
1017                         goto out_unlock0;
1018                 }
1019
1020                 /* SHM_UNLOCK */
1021                 if (!(shp->shm_perm.mode & SHM_LOCKED))
1022                         goto out_unlock0;
1023                 shmem_lock(shm_file, 0, shp->mlock_user);
1024                 shp->shm_perm.mode &= ~SHM_LOCKED;
1025                 shp->mlock_user = NULL;
1026                 get_file(shm_file);
1027                 ipc_unlock_object(&shp->shm_perm);
1028                 rcu_read_unlock();
1029                 shmem_unlock_mapping(shm_file->f_mapping);
1030
1031                 fput(shm_file);
1032                 return err;
1033         }
1034         default:
1035                 return -EINVAL;
1036         }
1037
1038 out_unlock0:
1039         ipc_unlock_object(&shp->shm_perm);
1040 out_unlock1:
1041         rcu_read_unlock();
1042         return err;
1043 }
1044
1045 /*
1046  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1047  *
1048  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1049  * "raddr" thing points to kernel space, and there has to be a wrapper around
1050  * this.
1051  */
1052 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
1053               unsigned long shmlba)
1054 {
1055         struct shmid_kernel *shp;
1056         unsigned long addr;
1057         unsigned long size;
1058         struct file *file;
1059         int    err;
1060         unsigned long flags;
1061         unsigned long prot;
1062         int acc_mode;
1063         struct ipc_namespace *ns;
1064         struct shm_file_data *sfd;
1065         struct path path;
1066         fmode_t f_mode;
1067         unsigned long populate = 0;
1068
1069         err = -EINVAL;
1070         if (shmid < 0)
1071                 goto out;
1072         else if ((addr = (ulong)shmaddr)) {
1073                 if (addr & (shmlba - 1)) {
1074                         if (shmflg & SHM_RND)
1075                                 addr &= ~(shmlba - 1);     /* round down */
1076                         else
1077 #ifndef __ARCH_FORCE_SHMLBA
1078                                 if (addr & ~PAGE_MASK)
1079 #endif
1080                                         goto out;
1081                 }
1082                 flags = MAP_SHARED | MAP_FIXED;
1083         } else {
1084                 if ((shmflg & SHM_REMAP))
1085                         goto out;
1086
1087                 flags = MAP_SHARED;
1088         }
1089
1090         if (shmflg & SHM_RDONLY) {
1091                 prot = PROT_READ;
1092                 acc_mode = S_IRUGO;
1093                 f_mode = FMODE_READ;
1094         } else {
1095                 prot = PROT_READ | PROT_WRITE;
1096                 acc_mode = S_IRUGO | S_IWUGO;
1097                 f_mode = FMODE_READ | FMODE_WRITE;
1098         }
1099         if (shmflg & SHM_EXEC) {
1100                 prot |= PROT_EXEC;
1101                 acc_mode |= S_IXUGO;
1102         }
1103
1104         /*
1105          * We cannot rely on the fs check since SYSV IPC does have an
1106          * additional creator id...
1107          */
1108         ns = current->nsproxy->ipc_ns;
1109         rcu_read_lock();
1110         shp = shm_obtain_object_check(ns, shmid);
1111         if (IS_ERR(shp)) {
1112                 err = PTR_ERR(shp);
1113                 goto out_unlock;
1114         }
1115
1116         err = -EACCES;
1117         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1118                 goto out_unlock;
1119
1120         err = security_shm_shmat(shp, shmaddr, shmflg);
1121         if (err)
1122                 goto out_unlock;
1123
1124         ipc_lock_object(&shp->shm_perm);
1125
1126         /* check if shm_destroy() is tearing down shp */
1127         if (!ipc_valid_object(&shp->shm_perm)) {
1128                 ipc_unlock_object(&shp->shm_perm);
1129                 err = -EIDRM;
1130                 goto out_unlock;
1131         }
1132
1133         path = shp->shm_file->f_path;
1134         path_get(&path);
1135         shp->shm_nattch++;
1136         size = i_size_read(d_inode(path.dentry));
1137         ipc_unlock_object(&shp->shm_perm);
1138         rcu_read_unlock();
1139
1140         err = -ENOMEM;
1141         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1142         if (!sfd) {
1143                 path_put(&path);
1144                 goto out_nattch;
1145         }
1146
1147         file = alloc_file(&path, f_mode,
1148                           is_file_hugepages(shp->shm_file) ?
1149                                 &shm_file_operations_huge :
1150                                 &shm_file_operations);
1151         err = PTR_ERR(file);
1152         if (IS_ERR(file)) {
1153                 kfree(sfd);
1154                 path_put(&path);
1155                 goto out_nattch;
1156         }
1157
1158         file->private_data = sfd;
1159         file->f_mapping = shp->shm_file->f_mapping;
1160         sfd->id = shp->shm_perm.id;
1161         sfd->ns = get_ipc_ns(ns);
1162         sfd->file = shp->shm_file;
1163         sfd->vm_ops = NULL;
1164
1165         err = security_mmap_file(file, prot, flags);
1166         if (err)
1167                 goto out_fput;
1168
1169         down_write(&current->mm->mmap_sem);
1170         if (addr && !(shmflg & SHM_REMAP)) {
1171                 err = -EINVAL;
1172                 if (addr + size < addr)
1173                         goto invalid;
1174
1175                 if (find_vma_intersection(current->mm, addr, addr + size))
1176                         goto invalid;
1177         }
1178
1179         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
1180         *raddr = addr;
1181         err = 0;
1182         if (IS_ERR_VALUE(addr))
1183                 err = (long)addr;
1184 invalid:
1185         up_write(&current->mm->mmap_sem);
1186         if (populate)
1187                 mm_populate(addr, populate);
1188
1189 out_fput:
1190         fput(file);
1191
1192 out_nattch:
1193         down_write(&shm_ids(ns).rwsem);
1194         shp = shm_lock(ns, shmid);
1195         shp->shm_nattch--;
1196         if (shm_may_destroy(ns, shp))
1197                 shm_destroy(ns, shp);
1198         else
1199                 shm_unlock(shp);
1200         up_write(&shm_ids(ns).rwsem);
1201         return err;
1202
1203 out_unlock:
1204         rcu_read_unlock();
1205 out:
1206         return err;
1207 }
1208
1209 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1210 {
1211         unsigned long ret;
1212         long err;
1213
1214         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1215         if (err)
1216                 return err;
1217         force_successful_syscall_return();
1218         return (long)ret;
1219 }
1220
1221 /*
1222  * detach and kill segment if marked destroyed.
1223  * The work is done in shm_close.
1224  */
1225 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1226 {
1227         struct mm_struct *mm = current->mm;
1228         struct vm_area_struct *vma;
1229         unsigned long addr = (unsigned long)shmaddr;
1230         int retval = -EINVAL;
1231 #ifdef CONFIG_MMU
1232         loff_t size = 0;
1233         struct file *file;
1234         struct vm_area_struct *next;
1235 #endif
1236
1237         if (addr & ~PAGE_MASK)
1238                 return retval;
1239
1240         down_write(&mm->mmap_sem);
1241
1242         /*
1243          * This function tries to be smart and unmap shm segments that
1244          * were modified by partial mlock or munmap calls:
1245          * - It first determines the size of the shm segment that should be
1246          *   unmapped: It searches for a vma that is backed by shm and that
1247          *   started at address shmaddr. It records it's size and then unmaps
1248          *   it.
1249          * - Then it unmaps all shm vmas that started at shmaddr and that
1250          *   are within the initially determined size and that are from the
1251          *   same shm segment from which we determined the size.
1252          * Errors from do_munmap are ignored: the function only fails if
1253          * it's called with invalid parameters or if it's called to unmap
1254          * a part of a vma. Both calls in this function are for full vmas,
1255          * the parameters are directly copied from the vma itself and always
1256          * valid - therefore do_munmap cannot fail. (famous last words?)
1257          */
1258         /*
1259          * If it had been mremap()'d, the starting address would not
1260          * match the usual checks anyway. So assume all vma's are
1261          * above the starting address given.
1262          */
1263         vma = find_vma(mm, addr);
1264
1265 #ifdef CONFIG_MMU
1266         while (vma) {
1267                 next = vma->vm_next;
1268
1269                 /*
1270                  * Check if the starting address would match, i.e. it's
1271                  * a fragment created by mprotect() and/or munmap(), or it
1272                  * otherwise it starts at this address with no hassles.
1273                  */
1274                 if ((vma->vm_ops == &shm_vm_ops) &&
1275                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1276
1277                         /*
1278                          * Record the file of the shm segment being
1279                          * unmapped.  With mremap(), someone could place
1280                          * page from another segment but with equal offsets
1281                          * in the range we are unmapping.
1282                          */
1283                         file = vma->vm_file;
1284                         size = i_size_read(file_inode(vma->vm_file));
1285                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1286                         /*
1287                          * We discovered the size of the shm segment, so
1288                          * break out of here and fall through to the next
1289                          * loop that uses the size information to stop
1290                          * searching for matching vma's.
1291                          */
1292                         retval = 0;
1293                         vma = next;
1294                         break;
1295                 }
1296                 vma = next;
1297         }
1298
1299         /*
1300          * We need look no further than the maximum address a fragment
1301          * could possibly have landed at. Also cast things to loff_t to
1302          * prevent overflows and make comparisons vs. equal-width types.
1303          */
1304         size = PAGE_ALIGN(size);
1305         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1306                 next = vma->vm_next;
1307
1308                 /* finding a matching vma now does not alter retval */
1309                 if ((vma->vm_ops == &shm_vm_ops) &&
1310                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1311                     (vma->vm_file == file))
1312                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1313                 vma = next;
1314         }
1315
1316 #else /* CONFIG_MMU */
1317         /* under NOMMU conditions, the exact address to be destroyed must be
1318          * given */
1319         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1320                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1321                 retval = 0;
1322         }
1323
1324 #endif
1325
1326         up_write(&mm->mmap_sem);
1327         return retval;
1328 }
1329
1330 #ifdef CONFIG_PROC_FS
1331 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1332 {
1333         struct user_namespace *user_ns = seq_user_ns(s);
1334         struct shmid_kernel *shp = it;
1335         unsigned long rss = 0, swp = 0;
1336
1337         shm_add_rss_swap(shp, &rss, &swp);
1338
1339 #if BITS_PER_LONG <= 32
1340 #define SIZE_SPEC "%10lu"
1341 #else
1342 #define SIZE_SPEC "%21lu"
1343 #endif
1344
1345         seq_printf(s,
1346                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1347                    "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1348                    SIZE_SPEC " " SIZE_SPEC "\n",
1349                    shp->shm_perm.key,
1350                    shp->shm_perm.id,
1351                    shp->shm_perm.mode,
1352                    shp->shm_segsz,
1353                    shp->shm_cprid,
1354                    shp->shm_lprid,
1355                    shp->shm_nattch,
1356                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1357                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1358                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1359                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1360                    shp->shm_atim,
1361                    shp->shm_dtim,
1362                    shp->shm_ctim,
1363                    rss * PAGE_SIZE,
1364                    swp * PAGE_SIZE);
1365
1366         return 0;
1367 }
1368 #endif