xref: /openbmc/linux/ipc/shm.c (revision 8a0a6c9af053fb93c0edf4581518c77fd131803e)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   * linux/ipc/shm.c
4   * Copyright (C) 1992, 1993 Krishna Balasubramanian
5   *	 Many improvements/fixes by Bruno Haible.
6   * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
7   * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
8   *
9   * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
10   * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
11   * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
12   * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
13   * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
14   * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
15   * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
16   *
17   * support for audit of ipc object properties and permission changes
18   * Dustin Kirkland <dustin.kirkland@us.ibm.com>
19   *
20   * namespaces support
21   * OpenVZ, SWsoft Inc.
22   * Pavel Emelianov <xemul@openvz.org>
23   *
24   * Better ipc lock (kern_ipc_perm.lock) handling
25   * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
26   */
27  
28  #include <linux/slab.h>
29  #include <linux/mm.h>
30  #include <linux/hugetlb.h>
31  #include <linux/shm.h>
32  #include <linux/init.h>
33  #include <linux/file.h>
34  #include <linux/mman.h>
35  #include <linux/shmem_fs.h>
36  #include <linux/security.h>
37  #include <linux/syscalls.h>
38  #include <linux/audit.h>
39  #include <linux/capability.h>
40  #include <linux/ptrace.h>
41  #include <linux/seq_file.h>
42  #include <linux/rwsem.h>
43  #include <linux/nsproxy.h>
44  #include <linux/mount.h>
45  #include <linux/ipc_namespace.h>
46  #include <linux/rhashtable.h>
47  
48  #include <linux/uaccess.h>
49  
50  #include "util.h"
51  
52  struct shmid_kernel /* private to the kernel */
53  {
54  	struct kern_ipc_perm	shm_perm;
55  	struct file		*shm_file;
56  	unsigned long		shm_nattch;
57  	unsigned long		shm_segsz;
58  	time64_t		shm_atim;
59  	time64_t		shm_dtim;
60  	time64_t		shm_ctim;
61  	struct pid		*shm_cprid;
62  	struct pid		*shm_lprid;
63  	struct ucounts		*mlock_ucounts;
64  
65  	/*
66  	 * The task created the shm object, for
67  	 * task_lock(shp->shm_creator)
68  	 */
69  	struct task_struct	*shm_creator;
70  
71  	/*
72  	 * List by creator. task_lock(->shm_creator) required for read/write.
73  	 * If list_empty(), then the creator is dead already.
74  	 */
75  	struct list_head	shm_clist;
76  	struct ipc_namespace	*ns;
77  } __randomize_layout;
78  
79  /* shm_mode upper byte flags */
80  #define SHM_DEST	01000	/* segment will be destroyed on last detach */
81  #define SHM_LOCKED	02000   /* segment will not be swapped */
82  
83  struct shm_file_data {
84  	int id;
85  	struct ipc_namespace *ns;
86  	struct file *file;
87  	const struct vm_operations_struct *vm_ops;
88  };
89  
90  #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
91  
92  static const struct file_operations shm_file_operations;
93  static const struct vm_operations_struct shm_vm_ops;
94  
95  #define shm_ids(ns)	((ns)->ids[IPC_SHM_IDS])
96  
97  #define shm_unlock(shp)			\
98  	ipc_unlock(&(shp)->shm_perm)
99  
100  static int newseg(struct ipc_namespace *, struct ipc_params *);
101  static void shm_open(struct vm_area_struct *vma);
102  static void shm_close(struct vm_area_struct *vma);
103  static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
104  #ifdef CONFIG_PROC_FS
105  static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
106  #endif
107  
108  void shm_init_ns(struct ipc_namespace *ns)
109  {
110  	ns->shm_ctlmax = SHMMAX;
111  	ns->shm_ctlall = SHMALL;
112  	ns->shm_ctlmni = SHMMNI;
113  	ns->shm_rmid_forced = 0;
114  	ns->shm_tot = 0;
115  	ipc_init_ids(&shm_ids(ns));
116  }
117  
118  /*
119   * Called with shm_ids.rwsem (writer) and the shp structure locked.
120   * Only shm_ids.rwsem remains locked on exit.
121   */
122  static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
123  {
124  	struct shmid_kernel *shp;
125  
126  	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
127  	WARN_ON(ns != shp->ns);
128  
129  	if (shp->shm_nattch) {
130  		shp->shm_perm.mode |= SHM_DEST;
131  		/* Do not find it any more */
132  		ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
133  		shm_unlock(shp);
134  	} else
135  		shm_destroy(ns, shp);
136  }
137  
138  #ifdef CONFIG_IPC_NS
139  void shm_exit_ns(struct ipc_namespace *ns)
140  {
141  	free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
142  	idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
143  	rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
144  }
145  #endif
146  
147  static int __init ipc_ns_init(void)
148  {
149  	shm_init_ns(&init_ipc_ns);
150  	return 0;
151  }
152  
153  pure_initcall(ipc_ns_init);
154  
155  void __init shm_init(void)
156  {
157  	ipc_init_proc_interface("sysvipc/shm",
158  #if BITS_PER_LONG <= 32
159  				"       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
160  #else
161  				"       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
162  #endif
163  				IPC_SHM_IDS, sysvipc_shm_proc_show);
164  }
165  
166  static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
167  {
168  	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
169  
170  	if (IS_ERR(ipcp))
171  		return ERR_CAST(ipcp);
172  
173  	return container_of(ipcp, struct shmid_kernel, shm_perm);
174  }
175  
176  static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
177  {
178  	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
179  
180  	if (IS_ERR(ipcp))
181  		return ERR_CAST(ipcp);
182  
183  	return container_of(ipcp, struct shmid_kernel, shm_perm);
184  }
185  
186  /*
187   * shm_lock_(check_) routines are called in the paths where the rwsem
188   * is not necessarily held.
189   */
190  static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
191  {
192  	struct kern_ipc_perm *ipcp;
193  
194  	rcu_read_lock();
195  	ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
196  	if (IS_ERR(ipcp))
197  		goto err;
198  
199  	ipc_lock_object(ipcp);
200  	/*
201  	 * ipc_rmid() may have already freed the ID while ipc_lock_object()
202  	 * was spinning: here verify that the structure is still valid.
203  	 * Upon races with RMID, return -EIDRM, thus indicating that
204  	 * the ID points to a removed identifier.
205  	 */
206  	if (ipc_valid_object(ipcp)) {
207  		/* return a locked ipc object upon success */
208  		return container_of(ipcp, struct shmid_kernel, shm_perm);
209  	}
210  
211  	ipc_unlock_object(ipcp);
212  	ipcp = ERR_PTR(-EIDRM);
213  err:
214  	rcu_read_unlock();
215  	/*
216  	 * Callers of shm_lock() must validate the status of the returned ipc
217  	 * object pointer and error out as appropriate.
218  	 */
219  	return ERR_CAST(ipcp);
220  }
221  
222  static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
223  {
224  	rcu_read_lock();
225  	ipc_lock_object(&ipcp->shm_perm);
226  }
227  
228  static void shm_rcu_free(struct rcu_head *head)
229  {
230  	struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
231  							rcu);
232  	struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
233  							shm_perm);
234  	security_shm_free(&shp->shm_perm);
235  	kfree(shp);
236  }
237  
238  /*
239   * It has to be called with shp locked.
240   * It must be called before ipc_rmid()
241   */
242  static inline void shm_clist_rm(struct shmid_kernel *shp)
243  {
244  	struct task_struct *creator;
245  
246  	/* ensure that shm_creator does not disappear */
247  	rcu_read_lock();
248  
249  	/*
250  	 * A concurrent exit_shm may do a list_del_init() as well.
251  	 * Just do nothing if exit_shm already did the work
252  	 */
253  	if (!list_empty(&shp->shm_clist)) {
254  		/*
255  		 * shp->shm_creator is guaranteed to be valid *only*
256  		 * if shp->shm_clist is not empty.
257  		 */
258  		creator = shp->shm_creator;
259  
260  		task_lock(creator);
261  		/*
262  		 * list_del_init() is a nop if the entry was already removed
263  		 * from the list.
264  		 */
265  		list_del_init(&shp->shm_clist);
266  		task_unlock(creator);
267  	}
268  	rcu_read_unlock();
269  }
270  
271  static inline void shm_rmid(struct shmid_kernel *s)
272  {
273  	shm_clist_rm(s);
274  	ipc_rmid(&shm_ids(s->ns), &s->shm_perm);
275  }
276  
277  
278  static int __shm_open(struct shm_file_data *sfd)
279  {
280  	struct shmid_kernel *shp;
281  
282  	shp = shm_lock(sfd->ns, sfd->id);
283  
284  	if (IS_ERR(shp))
285  		return PTR_ERR(shp);
286  
287  	if (shp->shm_file != sfd->file) {
288  		/* ID was reused */
289  		shm_unlock(shp);
290  		return -EINVAL;
291  	}
292  
293  	shp->shm_atim = ktime_get_real_seconds();
294  	ipc_update_pid(&shp->shm_lprid, task_tgid(current));
295  	shp->shm_nattch++;
296  	shm_unlock(shp);
297  	return 0;
298  }
299  
300  /* This is called by fork, once for every shm attach. */
301  static void shm_open(struct vm_area_struct *vma)
302  {
303  	struct file *file = vma->vm_file;
304  	struct shm_file_data *sfd = shm_file_data(file);
305  	int err;
306  
307  	/* Always call underlying open if present */
308  	if (sfd->vm_ops->open)
309  		sfd->vm_ops->open(vma);
310  
311  	err = __shm_open(sfd);
312  	/*
313  	 * We raced in the idr lookup or with shm_destroy().
314  	 * Either way, the ID is busted.
315  	 */
316  	WARN_ON_ONCE(err);
317  }
318  
319  /*
320   * shm_destroy - free the struct shmid_kernel
321   *
322   * @ns: namespace
323   * @shp: struct to free
324   *
325   * It has to be called with shp and shm_ids.rwsem (writer) locked,
326   * but returns with shp unlocked and freed.
327   */
328  static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
329  {
330  	struct file *shm_file;
331  
332  	shm_file = shp->shm_file;
333  	shp->shm_file = NULL;
334  	ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
335  	shm_rmid(shp);
336  	shm_unlock(shp);
337  	if (!is_file_hugepages(shm_file))
338  		shmem_lock(shm_file, 0, shp->mlock_ucounts);
339  	fput(shm_file);
340  	ipc_update_pid(&shp->shm_cprid, NULL);
341  	ipc_update_pid(&shp->shm_lprid, NULL);
342  	ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
343  }
344  
345  /*
346   * shm_may_destroy - identifies whether shm segment should be destroyed now
347   *
348   * Returns true if and only if there are no active users of the segment and
349   * one of the following is true:
350   *
351   * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
352   *
353   * 2) sysctl kernel.shm_rmid_forced is set to 1.
354   */
355  static bool shm_may_destroy(struct shmid_kernel *shp)
356  {
357  	return (shp->shm_nattch == 0) &&
358  	       (shp->ns->shm_rmid_forced ||
359  		(shp->shm_perm.mode & SHM_DEST));
360  }
361  
362  /*
363   * remove the attach descriptor vma.
364   * free memory for segment if it is marked destroyed.
365   * The descriptor has already been removed from the current->mm->mmap list
366   * and will later be kfree()d.
367   */
368  static void __shm_close(struct shm_file_data *sfd)
369  {
370  	struct shmid_kernel *shp;
371  	struct ipc_namespace *ns = sfd->ns;
372  
373  	down_write(&shm_ids(ns).rwsem);
374  	/* remove from the list of attaches of the shm segment */
375  	shp = shm_lock(ns, sfd->id);
376  
377  	/*
378  	 * We raced in the idr lookup or with shm_destroy().
379  	 * Either way, the ID is busted.
380  	 */
381  	if (WARN_ON_ONCE(IS_ERR(shp)))
382  		goto done; /* no-op */
383  
384  	ipc_update_pid(&shp->shm_lprid, task_tgid(current));
385  	shp->shm_dtim = ktime_get_real_seconds();
386  	shp->shm_nattch--;
387  	if (shm_may_destroy(shp))
388  		shm_destroy(ns, shp);
389  	else
390  		shm_unlock(shp);
391  done:
392  	up_write(&shm_ids(ns).rwsem);
393  }
394  
395  static void shm_close(struct vm_area_struct *vma)
396  {
397  	struct file *file = vma->vm_file;
398  	struct shm_file_data *sfd = shm_file_data(file);
399  
400  	/* Always call underlying close if present */
401  	if (sfd->vm_ops->close)
402  		sfd->vm_ops->close(vma);
403  
404  	__shm_close(sfd);
405  }
406  
407  /* Called with ns->shm_ids(ns).rwsem locked */
408  static int shm_try_destroy_orphaned(int id, void *p, void *data)
409  {
410  	struct ipc_namespace *ns = data;
411  	struct kern_ipc_perm *ipcp = p;
412  	struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
413  
414  	/*
415  	 * We want to destroy segments without users and with already
416  	 * exit'ed originating process.
417  	 *
418  	 * As shp->* are changed under rwsem, it's safe to skip shp locking.
419  	 */
420  	if (!list_empty(&shp->shm_clist))
421  		return 0;
422  
423  	if (shm_may_destroy(shp)) {
424  		shm_lock_by_ptr(shp);
425  		shm_destroy(ns, shp);
426  	}
427  	return 0;
428  }
429  
430  void shm_destroy_orphaned(struct ipc_namespace *ns)
431  {
432  	down_write(&shm_ids(ns).rwsem);
433  	if (shm_ids(ns).in_use)
434  		idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
435  	up_write(&shm_ids(ns).rwsem);
436  }
437  
438  /* Locking assumes this will only be called with task == current */
439  void exit_shm(struct task_struct *task)
440  {
441  	for (;;) {
442  		struct shmid_kernel *shp;
443  		struct ipc_namespace *ns;
444  
445  		task_lock(task);
446  
447  		if (list_empty(&task->sysvshm.shm_clist)) {
448  			task_unlock(task);
449  			break;
450  		}
451  
452  		shp = list_first_entry(&task->sysvshm.shm_clist, struct shmid_kernel,
453  				shm_clist);
454  
455  		/*
456  		 * 1) Get pointer to the ipc namespace. It is worth to say
457  		 * that this pointer is guaranteed to be valid because
458  		 * shp lifetime is always shorter than namespace lifetime
459  		 * in which shp lives.
460  		 * We taken task_lock it means that shp won't be freed.
461  		 */
462  		ns = shp->ns;
463  
464  		/*
465  		 * 2) If kernel.shm_rmid_forced is not set then only keep track of
466  		 * which shmids are orphaned, so that a later set of the sysctl
467  		 * can clean them up.
468  		 */
469  		if (!ns->shm_rmid_forced)
470  			goto unlink_continue;
471  
472  		/*
473  		 * 3) get a reference to the namespace.
474  		 *    The refcount could be already 0. If it is 0, then
475  		 *    the shm objects will be free by free_ipc_work().
476  		 */
477  		ns = get_ipc_ns_not_zero(ns);
478  		if (!ns) {
479  unlink_continue:
480  			list_del_init(&shp->shm_clist);
481  			task_unlock(task);
482  			continue;
483  		}
484  
485  		/*
486  		 * 4) get a reference to shp.
487  		 *   This cannot fail: shm_clist_rm() is called before
488  		 *   ipc_rmid(), thus the refcount cannot be 0.
489  		 */
490  		WARN_ON(!ipc_rcu_getref(&shp->shm_perm));
491  
492  		/*
493  		 * 5) unlink the shm segment from the list of segments
494  		 *    created by current.
495  		 *    This must be done last. After unlinking,
496  		 *    only the refcounts obtained above prevent IPC_RMID
497  		 *    from destroying the segment or the namespace.
498  		 */
499  		list_del_init(&shp->shm_clist);
500  
501  		task_unlock(task);
502  
503  		/*
504  		 * 6) we have all references
505  		 *    Thus lock & if needed destroy shp.
506  		 */
507  		down_write(&shm_ids(ns).rwsem);
508  		shm_lock_by_ptr(shp);
509  		/*
510  		 * rcu_read_lock was implicitly taken in shm_lock_by_ptr, it's
511  		 * safe to call ipc_rcu_putref here
512  		 */
513  		ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
514  
515  		if (ipc_valid_object(&shp->shm_perm)) {
516  			if (shm_may_destroy(shp))
517  				shm_destroy(ns, shp);
518  			else
519  				shm_unlock(shp);
520  		} else {
521  			/*
522  			 * Someone else deleted the shp from namespace
523  			 * idr/kht while we have waited.
524  			 * Just unlock and continue.
525  			 */
526  			shm_unlock(shp);
527  		}
528  
529  		up_write(&shm_ids(ns).rwsem);
530  		put_ipc_ns(ns); /* paired with get_ipc_ns_not_zero */
531  	}
532  }
533  
534  static vm_fault_t shm_fault(struct vm_fault *vmf)
535  {
536  	struct file *file = vmf->vma->vm_file;
537  	struct shm_file_data *sfd = shm_file_data(file);
538  
539  	return sfd->vm_ops->fault(vmf);
540  }
541  
542  static int shm_may_split(struct vm_area_struct *vma, unsigned long addr)
543  {
544  	struct file *file = vma->vm_file;
545  	struct shm_file_data *sfd = shm_file_data(file);
546  
547  	if (sfd->vm_ops->may_split)
548  		return sfd->vm_ops->may_split(vma, addr);
549  
550  	return 0;
551  }
552  
553  static unsigned long shm_pagesize(struct vm_area_struct *vma)
554  {
555  	struct file *file = vma->vm_file;
556  	struct shm_file_data *sfd = shm_file_data(file);
557  
558  	if (sfd->vm_ops->pagesize)
559  		return sfd->vm_ops->pagesize(vma);
560  
561  	return PAGE_SIZE;
562  }
563  
564  #ifdef CONFIG_NUMA
565  static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
566  {
567  	struct file *file = vma->vm_file;
568  	struct shm_file_data *sfd = shm_file_data(file);
569  	int err = 0;
570  
571  	if (sfd->vm_ops->set_policy)
572  		err = sfd->vm_ops->set_policy(vma, new);
573  	return err;
574  }
575  
576  static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
577  					unsigned long addr)
578  {
579  	struct file *file = vma->vm_file;
580  	struct shm_file_data *sfd = shm_file_data(file);
581  	struct mempolicy *pol = NULL;
582  
583  	if (sfd->vm_ops->get_policy)
584  		pol = sfd->vm_ops->get_policy(vma, addr);
585  	else if (vma->vm_policy)
586  		pol = vma->vm_policy;
587  
588  	return pol;
589  }
590  #endif
591  
592  static int shm_mmap(struct file *file, struct vm_area_struct *vma)
593  {
594  	struct shm_file_data *sfd = shm_file_data(file);
595  	int ret;
596  
597  	/*
598  	 * In case of remap_file_pages() emulation, the file can represent an
599  	 * IPC ID that was removed, and possibly even reused by another shm
600  	 * segment already.  Propagate this case as an error to caller.
601  	 */
602  	ret = __shm_open(sfd);
603  	if (ret)
604  		return ret;
605  
606  	ret = call_mmap(sfd->file, vma);
607  	if (ret) {
608  		__shm_close(sfd);
609  		return ret;
610  	}
611  	sfd->vm_ops = vma->vm_ops;
612  #ifdef CONFIG_MMU
613  	WARN_ON(!sfd->vm_ops->fault);
614  #endif
615  	vma->vm_ops = &shm_vm_ops;
616  	return 0;
617  }
618  
619  static int shm_release(struct inode *ino, struct file *file)
620  {
621  	struct shm_file_data *sfd = shm_file_data(file);
622  
623  	put_ipc_ns(sfd->ns);
624  	fput(sfd->file);
625  	shm_file_data(file) = NULL;
626  	kfree(sfd);
627  	return 0;
628  }
629  
630  static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
631  {
632  	struct shm_file_data *sfd = shm_file_data(file);
633  
634  	if (!sfd->file->f_op->fsync)
635  		return -EINVAL;
636  	return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
637  }
638  
639  static long shm_fallocate(struct file *file, int mode, loff_t offset,
640  			  loff_t len)
641  {
642  	struct shm_file_data *sfd = shm_file_data(file);
643  
644  	if (!sfd->file->f_op->fallocate)
645  		return -EOPNOTSUPP;
646  	return sfd->file->f_op->fallocate(file, mode, offset, len);
647  }
648  
649  static unsigned long shm_get_unmapped_area(struct file *file,
650  	unsigned long addr, unsigned long len, unsigned long pgoff,
651  	unsigned long flags)
652  {
653  	struct shm_file_data *sfd = shm_file_data(file);
654  
655  	return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
656  						pgoff, flags);
657  }
658  
659  static const struct file_operations shm_file_operations = {
660  	.mmap		= shm_mmap,
661  	.fsync		= shm_fsync,
662  	.release	= shm_release,
663  	.get_unmapped_area	= shm_get_unmapped_area,
664  	.llseek		= noop_llseek,
665  	.fallocate	= shm_fallocate,
666  };
667  
668  /*
669   * shm_file_operations_huge is now identical to shm_file_operations,
670   * but we keep it distinct for the sake of is_file_shm_hugepages().
671   */
672  static const struct file_operations shm_file_operations_huge = {
673  	.mmap		= shm_mmap,
674  	.fsync		= shm_fsync,
675  	.release	= shm_release,
676  	.get_unmapped_area	= shm_get_unmapped_area,
677  	.llseek		= noop_llseek,
678  	.fallocate	= shm_fallocate,
679  };
680  
681  bool is_file_shm_hugepages(struct file *file)
682  {
683  	return file->f_op == &shm_file_operations_huge;
684  }
685  
686  static const struct vm_operations_struct shm_vm_ops = {
687  	.open	= shm_open,	/* callback for a new vm-area open */
688  	.close	= shm_close,	/* callback for when the vm-area is released */
689  	.fault	= shm_fault,
690  	.may_split = shm_may_split,
691  	.pagesize = shm_pagesize,
692  #if defined(CONFIG_NUMA)
693  	.set_policy = shm_set_policy,
694  	.get_policy = shm_get_policy,
695  #endif
696  };
697  
698  /**
699   * newseg - Create a new shared memory segment
700   * @ns: namespace
701   * @params: ptr to the structure that contains key, size and shmflg
702   *
703   * Called with shm_ids.rwsem held as a writer.
704   */
705  static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
706  {
707  	key_t key = params->key;
708  	int shmflg = params->flg;
709  	size_t size = params->u.size;
710  	int error;
711  	struct shmid_kernel *shp;
712  	size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
713  	struct file *file;
714  	char name[13];
715  	vm_flags_t acctflag = 0;
716  
717  	if (size < SHMMIN || size > ns->shm_ctlmax)
718  		return -EINVAL;
719  
720  	if (numpages << PAGE_SHIFT < size)
721  		return -ENOSPC;
722  
723  	if (ns->shm_tot + numpages < ns->shm_tot ||
724  			ns->shm_tot + numpages > ns->shm_ctlall)
725  		return -ENOSPC;
726  
727  	shp = kmalloc(sizeof(*shp), GFP_KERNEL_ACCOUNT);
728  	if (unlikely(!shp))
729  		return -ENOMEM;
730  
731  	shp->shm_perm.key = key;
732  	shp->shm_perm.mode = (shmflg & S_IRWXUGO);
733  	shp->mlock_ucounts = NULL;
734  
735  	shp->shm_perm.security = NULL;
736  	error = security_shm_alloc(&shp->shm_perm);
737  	if (error) {
738  		kfree(shp);
739  		return error;
740  	}
741  
742  	sprintf(name, "SYSV%08x", key);
743  	if (shmflg & SHM_HUGETLB) {
744  		struct hstate *hs;
745  		size_t hugesize;
746  
747  		hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
748  		if (!hs) {
749  			error = -EINVAL;
750  			goto no_file;
751  		}
752  		hugesize = ALIGN(size, huge_page_size(hs));
753  
754  		/* hugetlb_file_setup applies strict accounting */
755  		if (shmflg & SHM_NORESERVE)
756  			acctflag = VM_NORESERVE;
757  		file = hugetlb_file_setup(name, hugesize, acctflag,
758  				HUGETLB_SHMFS_INODE, (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
759  	} else {
760  		/*
761  		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
762  		 * if it's asked for.
763  		 */
764  		if  ((shmflg & SHM_NORESERVE) &&
765  				sysctl_overcommit_memory != OVERCOMMIT_NEVER)
766  			acctflag = VM_NORESERVE;
767  		file = shmem_kernel_file_setup(name, size, acctflag);
768  	}
769  	error = PTR_ERR(file);
770  	if (IS_ERR(file))
771  		goto no_file;
772  
773  	shp->shm_cprid = get_pid(task_tgid(current));
774  	shp->shm_lprid = NULL;
775  	shp->shm_atim = shp->shm_dtim = 0;
776  	shp->shm_ctim = ktime_get_real_seconds();
777  	shp->shm_segsz = size;
778  	shp->shm_nattch = 0;
779  	shp->shm_file = file;
780  	shp->shm_creator = current;
781  
782  	/* ipc_addid() locks shp upon success. */
783  	error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
784  	if (error < 0)
785  		goto no_id;
786  
787  	shp->ns = ns;
788  
789  	task_lock(current);
790  	list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
791  	task_unlock(current);
792  
793  	/*
794  	 * shmid gets reported as "inode#" in /proc/pid/maps.
795  	 * proc-ps tools use this. Changing this will break them.
796  	 */
797  	file_inode(file)->i_ino = shp->shm_perm.id;
798  
799  	ns->shm_tot += numpages;
800  	error = shp->shm_perm.id;
801  
802  	ipc_unlock_object(&shp->shm_perm);
803  	rcu_read_unlock();
804  	return error;
805  
806  no_id:
807  	ipc_update_pid(&shp->shm_cprid, NULL);
808  	ipc_update_pid(&shp->shm_lprid, NULL);
809  	fput(file);
810  	ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
811  	return error;
812  no_file:
813  	call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
814  	return error;
815  }
816  
817  /*
818   * Called with shm_ids.rwsem and ipcp locked.
819   */
820  static int shm_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params)
821  {
822  	struct shmid_kernel *shp;
823  
824  	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
825  	if (shp->shm_segsz < params->u.size)
826  		return -EINVAL;
827  
828  	return 0;
829  }
830  
831  long ksys_shmget(key_t key, size_t size, int shmflg)
832  {
833  	struct ipc_namespace *ns;
834  	static const struct ipc_ops shm_ops = {
835  		.getnew = newseg,
836  		.associate = security_shm_associate,
837  		.more_checks = shm_more_checks,
838  	};
839  	struct ipc_params shm_params;
840  
841  	ns = current->nsproxy->ipc_ns;
842  
843  	shm_params.key = key;
844  	shm_params.flg = shmflg;
845  	shm_params.u.size = size;
846  
847  	return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
848  }
849  
850  SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
851  {
852  	return ksys_shmget(key, size, shmflg);
853  }
854  
855  static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
856  {
857  	switch (version) {
858  	case IPC_64:
859  		return copy_to_user(buf, in, sizeof(*in));
860  	case IPC_OLD:
861  	    {
862  		struct shmid_ds out;
863  
864  		memset(&out, 0, sizeof(out));
865  		ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
866  		out.shm_segsz	= in->shm_segsz;
867  		out.shm_atime	= in->shm_atime;
868  		out.shm_dtime	= in->shm_dtime;
869  		out.shm_ctime	= in->shm_ctime;
870  		out.shm_cpid	= in->shm_cpid;
871  		out.shm_lpid	= in->shm_lpid;
872  		out.shm_nattch	= in->shm_nattch;
873  
874  		return copy_to_user(buf, &out, sizeof(out));
875  	    }
876  	default:
877  		return -EINVAL;
878  	}
879  }
880  
881  static inline unsigned long
882  copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
883  {
884  	switch (version) {
885  	case IPC_64:
886  		if (copy_from_user(out, buf, sizeof(*out)))
887  			return -EFAULT;
888  		return 0;
889  	case IPC_OLD:
890  	    {
891  		struct shmid_ds tbuf_old;
892  
893  		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
894  			return -EFAULT;
895  
896  		out->shm_perm.uid	= tbuf_old.shm_perm.uid;
897  		out->shm_perm.gid	= tbuf_old.shm_perm.gid;
898  		out->shm_perm.mode	= tbuf_old.shm_perm.mode;
899  
900  		return 0;
901  	    }
902  	default:
903  		return -EINVAL;
904  	}
905  }
906  
907  static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
908  {
909  	switch (version) {
910  	case IPC_64:
911  		return copy_to_user(buf, in, sizeof(*in));
912  	case IPC_OLD:
913  	    {
914  		struct shminfo out;
915  
916  		if (in->shmmax > INT_MAX)
917  			out.shmmax = INT_MAX;
918  		else
919  			out.shmmax = (int)in->shmmax;
920  
921  		out.shmmin	= in->shmmin;
922  		out.shmmni	= in->shmmni;
923  		out.shmseg	= in->shmseg;
924  		out.shmall	= in->shmall;
925  
926  		return copy_to_user(buf, &out, sizeof(out));
927  	    }
928  	default:
929  		return -EINVAL;
930  	}
931  }
932  
933  /*
934   * Calculate and add used RSS and swap pages of a shm.
935   * Called with shm_ids.rwsem held as a reader
936   */
937  static void shm_add_rss_swap(struct shmid_kernel *shp,
938  	unsigned long *rss_add, unsigned long *swp_add)
939  {
940  	struct inode *inode;
941  
942  	inode = file_inode(shp->shm_file);
943  
944  	if (is_file_hugepages(shp->shm_file)) {
945  		struct address_space *mapping = inode->i_mapping;
946  		struct hstate *h = hstate_file(shp->shm_file);
947  		*rss_add += pages_per_huge_page(h) * mapping->nrpages;
948  	} else {
949  #ifdef CONFIG_SHMEM
950  		struct shmem_inode_info *info = SHMEM_I(inode);
951  
952  		spin_lock_irq(&info->lock);
953  		*rss_add += inode->i_mapping->nrpages;
954  		*swp_add += info->swapped;
955  		spin_unlock_irq(&info->lock);
956  #else
957  		*rss_add += inode->i_mapping->nrpages;
958  #endif
959  	}
960  }
961  
962  /*
963   * Called with shm_ids.rwsem held as a reader
964   */
965  static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
966  		unsigned long *swp)
967  {
968  	int next_id;
969  	int total, in_use;
970  
971  	*rss = 0;
972  	*swp = 0;
973  
974  	in_use = shm_ids(ns).in_use;
975  
976  	for (total = 0, next_id = 0; total < in_use; next_id++) {
977  		struct kern_ipc_perm *ipc;
978  		struct shmid_kernel *shp;
979  
980  		ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
981  		if (ipc == NULL)
982  			continue;
983  		shp = container_of(ipc, struct shmid_kernel, shm_perm);
984  
985  		shm_add_rss_swap(shp, rss, swp);
986  
987  		total++;
988  	}
989  }
990  
991  /*
992   * This function handles some shmctl commands which require the rwsem
993   * to be held in write mode.
994   * NOTE: no locks must be held, the rwsem is taken inside this function.
995   */
996  static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
997  		       struct shmid64_ds *shmid64)
998  {
999  	struct kern_ipc_perm *ipcp;
1000  	struct shmid_kernel *shp;
1001  	int err;
1002  
1003  	down_write(&shm_ids(ns).rwsem);
1004  	rcu_read_lock();
1005  
1006  	ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
1007  				      &shmid64->shm_perm, 0);
1008  	if (IS_ERR(ipcp)) {
1009  		err = PTR_ERR(ipcp);
1010  		goto out_unlock1;
1011  	}
1012  
1013  	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1014  
1015  	err = security_shm_shmctl(&shp->shm_perm, cmd);
1016  	if (err)
1017  		goto out_unlock1;
1018  
1019  	switch (cmd) {
1020  	case IPC_RMID:
1021  		ipc_lock_object(&shp->shm_perm);
1022  		/* do_shm_rmid unlocks the ipc object and rcu */
1023  		do_shm_rmid(ns, ipcp);
1024  		goto out_up;
1025  	case IPC_SET:
1026  		ipc_lock_object(&shp->shm_perm);
1027  		err = ipc_update_perm(&shmid64->shm_perm, ipcp);
1028  		if (err)
1029  			goto out_unlock0;
1030  		shp->shm_ctim = ktime_get_real_seconds();
1031  		break;
1032  	default:
1033  		err = -EINVAL;
1034  		goto out_unlock1;
1035  	}
1036  
1037  out_unlock0:
1038  	ipc_unlock_object(&shp->shm_perm);
1039  out_unlock1:
1040  	rcu_read_unlock();
1041  out_up:
1042  	up_write(&shm_ids(ns).rwsem);
1043  	return err;
1044  }
1045  
1046  static int shmctl_ipc_info(struct ipc_namespace *ns,
1047  			   struct shminfo64 *shminfo)
1048  {
1049  	int err = security_shm_shmctl(NULL, IPC_INFO);
1050  	if (!err) {
1051  		memset(shminfo, 0, sizeof(*shminfo));
1052  		shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
1053  		shminfo->shmmax = ns->shm_ctlmax;
1054  		shminfo->shmall = ns->shm_ctlall;
1055  		shminfo->shmmin = SHMMIN;
1056  		down_read(&shm_ids(ns).rwsem);
1057  		err = ipc_get_maxidx(&shm_ids(ns));
1058  		up_read(&shm_ids(ns).rwsem);
1059  		if (err < 0)
1060  			err = 0;
1061  	}
1062  	return err;
1063  }
1064  
1065  static int shmctl_shm_info(struct ipc_namespace *ns,
1066  			   struct shm_info *shm_info)
1067  {
1068  	int err = security_shm_shmctl(NULL, SHM_INFO);
1069  	if (!err) {
1070  		memset(shm_info, 0, sizeof(*shm_info));
1071  		down_read(&shm_ids(ns).rwsem);
1072  		shm_info->used_ids = shm_ids(ns).in_use;
1073  		shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
1074  		shm_info->shm_tot = ns->shm_tot;
1075  		shm_info->swap_attempts = 0;
1076  		shm_info->swap_successes = 0;
1077  		err = ipc_get_maxidx(&shm_ids(ns));
1078  		up_read(&shm_ids(ns).rwsem);
1079  		if (err < 0)
1080  			err = 0;
1081  	}
1082  	return err;
1083  }
1084  
1085  static int shmctl_stat(struct ipc_namespace *ns, int shmid,
1086  			int cmd, struct shmid64_ds *tbuf)
1087  {
1088  	struct shmid_kernel *shp;
1089  	int err;
1090  
1091  	memset(tbuf, 0, sizeof(*tbuf));
1092  
1093  	rcu_read_lock();
1094  	if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
1095  		shp = shm_obtain_object(ns, shmid);
1096  		if (IS_ERR(shp)) {
1097  			err = PTR_ERR(shp);
1098  			goto out_unlock;
1099  		}
1100  	} else { /* IPC_STAT */
1101  		shp = shm_obtain_object_check(ns, shmid);
1102  		if (IS_ERR(shp)) {
1103  			err = PTR_ERR(shp);
1104  			goto out_unlock;
1105  		}
1106  	}
1107  
1108  	/*
1109  	 * Semantically SHM_STAT_ANY ought to be identical to
1110  	 * that functionality provided by the /proc/sysvipc/
1111  	 * interface. As such, only audit these calls and
1112  	 * do not do traditional S_IRUGO permission checks on
1113  	 * the ipc object.
1114  	 */
1115  	if (cmd == SHM_STAT_ANY)
1116  		audit_ipc_obj(&shp->shm_perm);
1117  	else {
1118  		err = -EACCES;
1119  		if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1120  			goto out_unlock;
1121  	}
1122  
1123  	err = security_shm_shmctl(&shp->shm_perm, cmd);
1124  	if (err)
1125  		goto out_unlock;
1126  
1127  	ipc_lock_object(&shp->shm_perm);
1128  
1129  	if (!ipc_valid_object(&shp->shm_perm)) {
1130  		ipc_unlock_object(&shp->shm_perm);
1131  		err = -EIDRM;
1132  		goto out_unlock;
1133  	}
1134  
1135  	kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1136  	tbuf->shm_segsz	= shp->shm_segsz;
1137  	tbuf->shm_atime	= shp->shm_atim;
1138  	tbuf->shm_dtime	= shp->shm_dtim;
1139  	tbuf->shm_ctime	= shp->shm_ctim;
1140  #ifndef CONFIG_64BIT
1141  	tbuf->shm_atime_high = shp->shm_atim >> 32;
1142  	tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1143  	tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1144  #endif
1145  	tbuf->shm_cpid	= pid_vnr(shp->shm_cprid);
1146  	tbuf->shm_lpid	= pid_vnr(shp->shm_lprid);
1147  	tbuf->shm_nattch = shp->shm_nattch;
1148  
1149  	if (cmd == IPC_STAT) {
1150  		/*
1151  		 * As defined in SUS:
1152  		 * Return 0 on success
1153  		 */
1154  		err = 0;
1155  	} else {
1156  		/*
1157  		 * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1158  		 * Return the full id, including the sequence number
1159  		 */
1160  		err = shp->shm_perm.id;
1161  	}
1162  
1163  	ipc_unlock_object(&shp->shm_perm);
1164  out_unlock:
1165  	rcu_read_unlock();
1166  	return err;
1167  }
1168  
1169  static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1170  {
1171  	struct shmid_kernel *shp;
1172  	struct file *shm_file;
1173  	int err;
1174  
1175  	rcu_read_lock();
1176  	shp = shm_obtain_object_check(ns, shmid);
1177  	if (IS_ERR(shp)) {
1178  		err = PTR_ERR(shp);
1179  		goto out_unlock1;
1180  	}
1181  
1182  	audit_ipc_obj(&(shp->shm_perm));
1183  	err = security_shm_shmctl(&shp->shm_perm, cmd);
1184  	if (err)
1185  		goto out_unlock1;
1186  
1187  	ipc_lock_object(&shp->shm_perm);
1188  
1189  	/* check if shm_destroy() is tearing down shp */
1190  	if (!ipc_valid_object(&shp->shm_perm)) {
1191  		err = -EIDRM;
1192  		goto out_unlock0;
1193  	}
1194  
1195  	if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1196  		kuid_t euid = current_euid();
1197  
1198  		if (!uid_eq(euid, shp->shm_perm.uid) &&
1199  		    !uid_eq(euid, shp->shm_perm.cuid)) {
1200  			err = -EPERM;
1201  			goto out_unlock0;
1202  		}
1203  		if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1204  			err = -EPERM;
1205  			goto out_unlock0;
1206  		}
1207  	}
1208  
1209  	shm_file = shp->shm_file;
1210  	if (is_file_hugepages(shm_file))
1211  		goto out_unlock0;
1212  
1213  	if (cmd == SHM_LOCK) {
1214  		struct ucounts *ucounts = current_ucounts();
1215  
1216  		err = shmem_lock(shm_file, 1, ucounts);
1217  		if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1218  			shp->shm_perm.mode |= SHM_LOCKED;
1219  			shp->mlock_ucounts = ucounts;
1220  		}
1221  		goto out_unlock0;
1222  	}
1223  
1224  	/* SHM_UNLOCK */
1225  	if (!(shp->shm_perm.mode & SHM_LOCKED))
1226  		goto out_unlock0;
1227  	shmem_lock(shm_file, 0, shp->mlock_ucounts);
1228  	shp->shm_perm.mode &= ~SHM_LOCKED;
1229  	shp->mlock_ucounts = NULL;
1230  	get_file(shm_file);
1231  	ipc_unlock_object(&shp->shm_perm);
1232  	rcu_read_unlock();
1233  	shmem_unlock_mapping(shm_file->f_mapping);
1234  
1235  	fput(shm_file);
1236  	return err;
1237  
1238  out_unlock0:
1239  	ipc_unlock_object(&shp->shm_perm);
1240  out_unlock1:
1241  	rcu_read_unlock();
1242  	return err;
1243  }
1244  
1245  static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
1246  {
1247  	int err;
1248  	struct ipc_namespace *ns;
1249  	struct shmid64_ds sem64;
1250  
1251  	if (cmd < 0 || shmid < 0)
1252  		return -EINVAL;
1253  
1254  	ns = current->nsproxy->ipc_ns;
1255  
1256  	switch (cmd) {
1257  	case IPC_INFO: {
1258  		struct shminfo64 shminfo;
1259  		err = shmctl_ipc_info(ns, &shminfo);
1260  		if (err < 0)
1261  			return err;
1262  		if (copy_shminfo_to_user(buf, &shminfo, version))
1263  			err = -EFAULT;
1264  		return err;
1265  	}
1266  	case SHM_INFO: {
1267  		struct shm_info shm_info;
1268  		err = shmctl_shm_info(ns, &shm_info);
1269  		if (err < 0)
1270  			return err;
1271  		if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1272  			err = -EFAULT;
1273  		return err;
1274  	}
1275  	case SHM_STAT:
1276  	case SHM_STAT_ANY:
1277  	case IPC_STAT: {
1278  		err = shmctl_stat(ns, shmid, cmd, &sem64);
1279  		if (err < 0)
1280  			return err;
1281  		if (copy_shmid_to_user(buf, &sem64, version))
1282  			err = -EFAULT;
1283  		return err;
1284  	}
1285  	case IPC_SET:
1286  		if (copy_shmid_from_user(&sem64, buf, version))
1287  			return -EFAULT;
1288  		fallthrough;
1289  	case IPC_RMID:
1290  		return shmctl_down(ns, shmid, cmd, &sem64);
1291  	case SHM_LOCK:
1292  	case SHM_UNLOCK:
1293  		return shmctl_do_lock(ns, shmid, cmd);
1294  	default:
1295  		return -EINVAL;
1296  	}
1297  }
1298  
1299  SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1300  {
1301  	return ksys_shmctl(shmid, cmd, buf, IPC_64);
1302  }
1303  
1304  #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
1305  long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1306  {
1307  	int version = ipc_parse_version(&cmd);
1308  
1309  	return ksys_shmctl(shmid, cmd, buf, version);
1310  }
1311  
1312  SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1313  {
1314  	return ksys_old_shmctl(shmid, cmd, buf);
1315  }
1316  #endif
1317  
1318  #ifdef CONFIG_COMPAT
1319  
1320  struct compat_shmid_ds {
1321  	struct compat_ipc_perm shm_perm;
1322  	int shm_segsz;
1323  	old_time32_t shm_atime;
1324  	old_time32_t shm_dtime;
1325  	old_time32_t shm_ctime;
1326  	compat_ipc_pid_t shm_cpid;
1327  	compat_ipc_pid_t shm_lpid;
1328  	unsigned short shm_nattch;
1329  	unsigned short shm_unused;
1330  	compat_uptr_t shm_unused2;
1331  	compat_uptr_t shm_unused3;
1332  };
1333  
1334  struct compat_shminfo64 {
1335  	compat_ulong_t shmmax;
1336  	compat_ulong_t shmmin;
1337  	compat_ulong_t shmmni;
1338  	compat_ulong_t shmseg;
1339  	compat_ulong_t shmall;
1340  	compat_ulong_t __unused1;
1341  	compat_ulong_t __unused2;
1342  	compat_ulong_t __unused3;
1343  	compat_ulong_t __unused4;
1344  };
1345  
1346  struct compat_shm_info {
1347  	compat_int_t used_ids;
1348  	compat_ulong_t shm_tot, shm_rss, shm_swp;
1349  	compat_ulong_t swap_attempts, swap_successes;
1350  };
1351  
1352  static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1353  					int version)
1354  {
1355  	if (in->shmmax > INT_MAX)
1356  		in->shmmax = INT_MAX;
1357  	if (version == IPC_64) {
1358  		struct compat_shminfo64 info;
1359  		memset(&info, 0, sizeof(info));
1360  		info.shmmax = in->shmmax;
1361  		info.shmmin = in->shmmin;
1362  		info.shmmni = in->shmmni;
1363  		info.shmseg = in->shmseg;
1364  		info.shmall = in->shmall;
1365  		return copy_to_user(buf, &info, sizeof(info));
1366  	} else {
1367  		struct shminfo info;
1368  		memset(&info, 0, sizeof(info));
1369  		info.shmmax = in->shmmax;
1370  		info.shmmin = in->shmmin;
1371  		info.shmmni = in->shmmni;
1372  		info.shmseg = in->shmseg;
1373  		info.shmall = in->shmall;
1374  		return copy_to_user(buf, &info, sizeof(info));
1375  	}
1376  }
1377  
1378  static int put_compat_shm_info(struct shm_info *ip,
1379  				struct compat_shm_info __user *uip)
1380  {
1381  	struct compat_shm_info info;
1382  
1383  	memset(&info, 0, sizeof(info));
1384  	info.used_ids = ip->used_ids;
1385  	info.shm_tot = ip->shm_tot;
1386  	info.shm_rss = ip->shm_rss;
1387  	info.shm_swp = ip->shm_swp;
1388  	info.swap_attempts = ip->swap_attempts;
1389  	info.swap_successes = ip->swap_successes;
1390  	return copy_to_user(uip, &info, sizeof(info));
1391  }
1392  
1393  static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1394  					int version)
1395  {
1396  	if (version == IPC_64) {
1397  		struct compat_shmid64_ds v;
1398  		memset(&v, 0, sizeof(v));
1399  		to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1400  		v.shm_atime	 = lower_32_bits(in->shm_atime);
1401  		v.shm_atime_high = upper_32_bits(in->shm_atime);
1402  		v.shm_dtime	 = lower_32_bits(in->shm_dtime);
1403  		v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1404  		v.shm_ctime	 = lower_32_bits(in->shm_ctime);
1405  		v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1406  		v.shm_segsz = in->shm_segsz;
1407  		v.shm_nattch = in->shm_nattch;
1408  		v.shm_cpid = in->shm_cpid;
1409  		v.shm_lpid = in->shm_lpid;
1410  		return copy_to_user(buf, &v, sizeof(v));
1411  	} else {
1412  		struct compat_shmid_ds v;
1413  		memset(&v, 0, sizeof(v));
1414  		to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1415  		v.shm_perm.key = in->shm_perm.key;
1416  		v.shm_atime = in->shm_atime;
1417  		v.shm_dtime = in->shm_dtime;
1418  		v.shm_ctime = in->shm_ctime;
1419  		v.shm_segsz = in->shm_segsz;
1420  		v.shm_nattch = in->shm_nattch;
1421  		v.shm_cpid = in->shm_cpid;
1422  		v.shm_lpid = in->shm_lpid;
1423  		return copy_to_user(buf, &v, sizeof(v));
1424  	}
1425  }
1426  
1427  static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1428  					int version)
1429  {
1430  	memset(out, 0, sizeof(*out));
1431  	if (version == IPC_64) {
1432  		struct compat_shmid64_ds __user *p = buf;
1433  		return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1434  	} else {
1435  		struct compat_shmid_ds __user *p = buf;
1436  		return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1437  	}
1438  }
1439  
1440  static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
1441  {
1442  	struct ipc_namespace *ns;
1443  	struct shmid64_ds sem64;
1444  	int err;
1445  
1446  	ns = current->nsproxy->ipc_ns;
1447  
1448  	if (cmd < 0 || shmid < 0)
1449  		return -EINVAL;
1450  
1451  	switch (cmd) {
1452  	case IPC_INFO: {
1453  		struct shminfo64 shminfo;
1454  		err = shmctl_ipc_info(ns, &shminfo);
1455  		if (err < 0)
1456  			return err;
1457  		if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1458  			err = -EFAULT;
1459  		return err;
1460  	}
1461  	case SHM_INFO: {
1462  		struct shm_info shm_info;
1463  		err = shmctl_shm_info(ns, &shm_info);
1464  		if (err < 0)
1465  			return err;
1466  		if (put_compat_shm_info(&shm_info, uptr))
1467  			err = -EFAULT;
1468  		return err;
1469  	}
1470  	case IPC_STAT:
1471  	case SHM_STAT_ANY:
1472  	case SHM_STAT:
1473  		err = shmctl_stat(ns, shmid, cmd, &sem64);
1474  		if (err < 0)
1475  			return err;
1476  		if (copy_compat_shmid_to_user(uptr, &sem64, version))
1477  			err = -EFAULT;
1478  		return err;
1479  
1480  	case IPC_SET:
1481  		if (copy_compat_shmid_from_user(&sem64, uptr, version))
1482  			return -EFAULT;
1483  		fallthrough;
1484  	case IPC_RMID:
1485  		return shmctl_down(ns, shmid, cmd, &sem64);
1486  	case SHM_LOCK:
1487  	case SHM_UNLOCK:
1488  		return shmctl_do_lock(ns, shmid, cmd);
1489  	default:
1490  		return -EINVAL;
1491  	}
1492  	return err;
1493  }
1494  
1495  COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1496  {
1497  	return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
1498  }
1499  
1500  #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
1501  long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
1502  {
1503  	int version = compat_ipc_parse_version(&cmd);
1504  
1505  	return compat_ksys_shmctl(shmid, cmd, uptr, version);
1506  }
1507  
1508  COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
1509  {
1510  	return compat_ksys_old_shmctl(shmid, cmd, uptr);
1511  }
1512  #endif
1513  #endif
1514  
1515  /*
1516   * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1517   *
1518   * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1519   * "raddr" thing points to kernel space, and there has to be a wrapper around
1520   * this.
1521   */
1522  long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1523  	      ulong *raddr, unsigned long shmlba)
1524  {
1525  	struct shmid_kernel *shp;
1526  	unsigned long addr = (unsigned long)shmaddr;
1527  	unsigned long size;
1528  	struct file *file, *base;
1529  	int    err;
1530  	unsigned long flags = MAP_SHARED;
1531  	unsigned long prot;
1532  	int acc_mode;
1533  	struct ipc_namespace *ns;
1534  	struct shm_file_data *sfd;
1535  	int f_flags;
1536  	unsigned long populate = 0;
1537  
1538  	err = -EINVAL;
1539  	if (shmid < 0)
1540  		goto out;
1541  
1542  	if (addr) {
1543  		if (addr & (shmlba - 1)) {
1544  			if (shmflg & SHM_RND) {
1545  				addr &= ~(shmlba - 1);  /* round down */
1546  
1547  				/*
1548  				 * Ensure that the round-down is non-nil
1549  				 * when remapping. This can happen for
1550  				 * cases when addr < shmlba.
1551  				 */
1552  				if (!addr && (shmflg & SHM_REMAP))
1553  					goto out;
1554  			} else
1555  #ifndef __ARCH_FORCE_SHMLBA
1556  				if (addr & ~PAGE_MASK)
1557  #endif
1558  					goto out;
1559  		}
1560  
1561  		flags |= MAP_FIXED;
1562  	} else if ((shmflg & SHM_REMAP))
1563  		goto out;
1564  
1565  	if (shmflg & SHM_RDONLY) {
1566  		prot = PROT_READ;
1567  		acc_mode = S_IRUGO;
1568  		f_flags = O_RDONLY;
1569  	} else {
1570  		prot = PROT_READ | PROT_WRITE;
1571  		acc_mode = S_IRUGO | S_IWUGO;
1572  		f_flags = O_RDWR;
1573  	}
1574  	if (shmflg & SHM_EXEC) {
1575  		prot |= PROT_EXEC;
1576  		acc_mode |= S_IXUGO;
1577  	}
1578  
1579  	/*
1580  	 * We cannot rely on the fs check since SYSV IPC does have an
1581  	 * additional creator id...
1582  	 */
1583  	ns = current->nsproxy->ipc_ns;
1584  	rcu_read_lock();
1585  	shp = shm_obtain_object_check(ns, shmid);
1586  	if (IS_ERR(shp)) {
1587  		err = PTR_ERR(shp);
1588  		goto out_unlock;
1589  	}
1590  
1591  	err = -EACCES;
1592  	if (ipcperms(ns, &shp->shm_perm, acc_mode))
1593  		goto out_unlock;
1594  
1595  	err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1596  	if (err)
1597  		goto out_unlock;
1598  
1599  	ipc_lock_object(&shp->shm_perm);
1600  
1601  	/* check if shm_destroy() is tearing down shp */
1602  	if (!ipc_valid_object(&shp->shm_perm)) {
1603  		ipc_unlock_object(&shp->shm_perm);
1604  		err = -EIDRM;
1605  		goto out_unlock;
1606  	}
1607  
1608  	/*
1609  	 * We need to take a reference to the real shm file to prevent the
1610  	 * pointer from becoming stale in cases where the lifetime of the outer
1611  	 * file extends beyond that of the shm segment.  It's not usually
1612  	 * possible, but it can happen during remap_file_pages() emulation as
1613  	 * that unmaps the memory, then does ->mmap() via file reference only.
1614  	 * We'll deny the ->mmap() if the shm segment was since removed, but to
1615  	 * detect shm ID reuse we need to compare the file pointers.
1616  	 */
1617  	base = get_file(shp->shm_file);
1618  	shp->shm_nattch++;
1619  	size = i_size_read(file_inode(base));
1620  	ipc_unlock_object(&shp->shm_perm);
1621  	rcu_read_unlock();
1622  
1623  	err = -ENOMEM;
1624  	sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1625  	if (!sfd) {
1626  		fput(base);
1627  		goto out_nattch;
1628  	}
1629  
1630  	file = alloc_file_clone(base, f_flags,
1631  			  is_file_hugepages(base) ?
1632  				&shm_file_operations_huge :
1633  				&shm_file_operations);
1634  	err = PTR_ERR(file);
1635  	if (IS_ERR(file)) {
1636  		kfree(sfd);
1637  		fput(base);
1638  		goto out_nattch;
1639  	}
1640  
1641  	sfd->id = shp->shm_perm.id;
1642  	sfd->ns = get_ipc_ns(ns);
1643  	sfd->file = base;
1644  	sfd->vm_ops = NULL;
1645  	file->private_data = sfd;
1646  
1647  	err = security_mmap_file(file, prot, flags);
1648  	if (err)
1649  		goto out_fput;
1650  
1651  	if (mmap_write_lock_killable(current->mm)) {
1652  		err = -EINTR;
1653  		goto out_fput;
1654  	}
1655  
1656  	if (addr && !(shmflg & SHM_REMAP)) {
1657  		err = -EINVAL;
1658  		if (addr + size < addr)
1659  			goto invalid;
1660  
1661  		if (find_vma_intersection(current->mm, addr, addr + size))
1662  			goto invalid;
1663  	}
1664  
1665  	addr = do_mmap(file, addr, size, prot, flags, 0, &populate, NULL);
1666  	*raddr = addr;
1667  	err = 0;
1668  	if (IS_ERR_VALUE(addr))
1669  		err = (long)addr;
1670  invalid:
1671  	mmap_write_unlock(current->mm);
1672  	if (populate)
1673  		mm_populate(addr, populate);
1674  
1675  out_fput:
1676  	fput(file);
1677  
1678  out_nattch:
1679  	down_write(&shm_ids(ns).rwsem);
1680  	shp = shm_lock(ns, shmid);
1681  	shp->shm_nattch--;
1682  
1683  	if (shm_may_destroy(shp))
1684  		shm_destroy(ns, shp);
1685  	else
1686  		shm_unlock(shp);
1687  	up_write(&shm_ids(ns).rwsem);
1688  	return err;
1689  
1690  out_unlock:
1691  	rcu_read_unlock();
1692  out:
1693  	return err;
1694  }
1695  
1696  SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1697  {
1698  	unsigned long ret;
1699  	long err;
1700  
1701  	err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1702  	if (err)
1703  		return err;
1704  	force_successful_syscall_return();
1705  	return (long)ret;
1706  }
1707  
1708  #ifdef CONFIG_COMPAT
1709  
1710  #ifndef COMPAT_SHMLBA
1711  #define COMPAT_SHMLBA	SHMLBA
1712  #endif
1713  
1714  COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1715  {
1716  	unsigned long ret;
1717  	long err;
1718  
1719  	err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1720  	if (err)
1721  		return err;
1722  	force_successful_syscall_return();
1723  	return (long)ret;
1724  }
1725  #endif
1726  
1727  /*
1728   * detach and kill segment if marked destroyed.
1729   * The work is done in shm_close.
1730   */
1731  long ksys_shmdt(char __user *shmaddr)
1732  {
1733  	struct mm_struct *mm = current->mm;
1734  	struct vm_area_struct *vma;
1735  	unsigned long addr = (unsigned long)shmaddr;
1736  	int retval = -EINVAL;
1737  #ifdef CONFIG_MMU
1738  	loff_t size = 0;
1739  	struct file *file;
1740  	VMA_ITERATOR(vmi, mm, addr);
1741  #endif
1742  
1743  	if (addr & ~PAGE_MASK)
1744  		return retval;
1745  
1746  	if (mmap_write_lock_killable(mm))
1747  		return -EINTR;
1748  
1749  	/*
1750  	 * This function tries to be smart and unmap shm segments that
1751  	 * were modified by partial mlock or munmap calls:
1752  	 * - It first determines the size of the shm segment that should be
1753  	 *   unmapped: It searches for a vma that is backed by shm and that
1754  	 *   started at address shmaddr. It records it's size and then unmaps
1755  	 *   it.
1756  	 * - Then it unmaps all shm vmas that started at shmaddr and that
1757  	 *   are within the initially determined size and that are from the
1758  	 *   same shm segment from which we determined the size.
1759  	 * Errors from do_munmap are ignored: the function only fails if
1760  	 * it's called with invalid parameters or if it's called to unmap
1761  	 * a part of a vma. Both calls in this function are for full vmas,
1762  	 * the parameters are directly copied from the vma itself and always
1763  	 * valid - therefore do_munmap cannot fail. (famous last words?)
1764  	 */
1765  	/*
1766  	 * If it had been mremap()'d, the starting address would not
1767  	 * match the usual checks anyway. So assume all vma's are
1768  	 * above the starting address given.
1769  	 */
1770  
1771  #ifdef CONFIG_MMU
1772  	for_each_vma(vmi, vma) {
1773  		/*
1774  		 * Check if the starting address would match, i.e. it's
1775  		 * a fragment created by mprotect() and/or munmap(), or it
1776  		 * otherwise it starts at this address with no hassles.
1777  		 */
1778  		if ((vma->vm_ops == &shm_vm_ops) &&
1779  			(vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1780  
1781  			/*
1782  			 * Record the file of the shm segment being
1783  			 * unmapped.  With mremap(), someone could place
1784  			 * page from another segment but with equal offsets
1785  			 * in the range we are unmapping.
1786  			 */
1787  			file = vma->vm_file;
1788  			size = i_size_read(file_inode(vma->vm_file));
1789  			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
1790  				      NULL, false);
1791  			/*
1792  			 * We discovered the size of the shm segment, so
1793  			 * break out of here and fall through to the next
1794  			 * loop that uses the size information to stop
1795  			 * searching for matching vma's.
1796  			 */
1797  			retval = 0;
1798  			vma = vma_next(&vmi);
1799  			break;
1800  		}
1801  	}
1802  
1803  	/*
1804  	 * We need look no further than the maximum address a fragment
1805  	 * could possibly have landed at. Also cast things to loff_t to
1806  	 * prevent overflows and make comparisons vs. equal-width types.
1807  	 */
1808  	size = PAGE_ALIGN(size);
1809  	while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1810  		/* finding a matching vma now does not alter retval */
1811  		if ((vma->vm_ops == &shm_vm_ops) &&
1812  		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1813  		    (vma->vm_file == file)) {
1814  			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
1815  				      NULL, false);
1816  		}
1817  
1818  		vma = vma_next(&vmi);
1819  	}
1820  
1821  #else	/* CONFIG_MMU */
1822  	vma = vma_lookup(mm, addr);
1823  	/* under NOMMU conditions, the exact address to be destroyed must be
1824  	 * given
1825  	 */
1826  	if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1827  		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1828  		retval = 0;
1829  	}
1830  
1831  #endif
1832  
1833  	mmap_write_unlock(mm);
1834  	return retval;
1835  }
1836  
1837  SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1838  {
1839  	return ksys_shmdt(shmaddr);
1840  }
1841  
1842  #ifdef CONFIG_PROC_FS
1843  static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1844  {
1845  	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1846  	struct user_namespace *user_ns = seq_user_ns(s);
1847  	struct kern_ipc_perm *ipcp = it;
1848  	struct shmid_kernel *shp;
1849  	unsigned long rss = 0, swp = 0;
1850  
1851  	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1852  	shm_add_rss_swap(shp, &rss, &swp);
1853  
1854  #if BITS_PER_LONG <= 32
1855  #define SIZE_SPEC "%10lu"
1856  #else
1857  #define SIZE_SPEC "%21lu"
1858  #endif
1859  
1860  	seq_printf(s,
1861  		   "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1862  		   "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1863  		   SIZE_SPEC " " SIZE_SPEC "\n",
1864  		   shp->shm_perm.key,
1865  		   shp->shm_perm.id,
1866  		   shp->shm_perm.mode,
1867  		   shp->shm_segsz,
1868  		   pid_nr_ns(shp->shm_cprid, pid_ns),
1869  		   pid_nr_ns(shp->shm_lprid, pid_ns),
1870  		   shp->shm_nattch,
1871  		   from_kuid_munged(user_ns, shp->shm_perm.uid),
1872  		   from_kgid_munged(user_ns, shp->shm_perm.gid),
1873  		   from_kuid_munged(user_ns, shp->shm_perm.cuid),
1874  		   from_kgid_munged(user_ns, shp->shm_perm.cgid),
1875  		   shp->shm_atim,
1876  		   shp->shm_dtim,
1877  		   shp->shm_ctim,
1878  		   rss * PAGE_SIZE,
1879  		   swp * PAGE_SIZE);
1880  
1881  	return 0;
1882  }
1883  #endif
1884