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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
24 #include <linux/slab.h>
25 #include <linux/mm.h>
26 #include <linux/hugetlb.h>
27 #include <linux/shm.h>
28 #include <linux/init.h>
29 #include <linux/file.h>
30 #include <linux/mman.h>
31 #include <linux/shmem_fs.h>
32 #include <linux/security.h>
33 #include <linux/syscalls.h>
34 #include <linux/audit.h>
35 #include <linux/capability.h>
36 #include <linux/ptrace.h>
37 #include <linux/seq_file.h>
38 #include <linux/rwsem.h>
39 #include <linux/nsproxy.h>
40 #include <linux/mount.h>
41 #include <linux/ipc_namespace.h>
42
43 #include <asm/uaccess.h>
44
45 #include "util.h"
46
47 struct shm_file_data {
48 int id;
49 struct ipc_namespace *ns;
50 struct file *file;
51 const struct vm_operations_struct *vm_ops;
52 };
53
54 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
55
56 static const struct file_operations shm_file_operations;
57 static const struct vm_operations_struct shm_vm_ops;
58
59 #define shm_ids(ns) ((ns)->ids[IPC_SHM_IDS])
60
61 #define shm_unlock(shp) \
62 ipc_unlock(&(shp)->shm_perm)
63
64 static int newseg(struct ipc_namespace *, struct ipc_params *);
65 static void shm_open(struct vm_area_struct *vma);
66 static void shm_close(struct vm_area_struct *vma);
67 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
68 #ifdef CONFIG_PROC_FS
69 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
70 #endif
71
72 void shm_init_ns(struct ipc_namespace *ns)
73 {
74 ns->shm_ctlmax = SHMMAX;
75 ns->shm_ctlall = SHMALL;
76 ns->shm_ctlmni = SHMMNI;
77 ns->shm_rmid_forced = 0;
78 ns->shm_tot = 0;
79 ipc_init_ids(&shm_ids(ns));
80 }
81
82 /*
83 * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
84 * Only shm_ids.rw_mutex remains locked on exit.
85 */
86 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
87 {
88 struct shmid_kernel *shp;
89 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
90
91 if (shp->shm_nattch){
92 shp->shm_perm.mode |= SHM_DEST;
93 /* Do not find it any more */
94 shp->shm_perm.key = IPC_PRIVATE;
95 shm_unlock(shp);
96 } else
97 shm_destroy(ns, shp);
98 }
99
100 #ifdef CONFIG_IPC_NS
101 void shm_exit_ns(struct ipc_namespace *ns)
102 {
103 free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
104 idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
105 }
106 #endif
107
108 static int __init ipc_ns_init(void)
109 {
110 shm_init_ns(&init_ipc_ns);
111 return 0;
112 }
113
114 pure_initcall(ipc_ns_init);
115
116 void __init shm_init (void)
117 {
118 ipc_init_proc_interface("sysvipc/shm",
119 #if BITS_PER_LONG <= 32
120 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n",
121 #else
122 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n",
123 #endif
124 IPC_SHM_IDS, sysvipc_shm_proc_show);
125 }
126
127 /*
128 * shm_lock_(check_) routines are called in the paths where the rw_mutex
129 * is not necessarily held.
130 */
131 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
132 {
133 struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
134
135 if (IS_ERR(ipcp))
136 return (struct shmid_kernel *)ipcp;
137
138 return container_of(ipcp, struct shmid_kernel, shm_perm);
139 }
140
141 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
142 {
143 rcu_read_lock();
144 spin_lock(&ipcp->shm_perm.lock);
145 }
146
147 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
148 int id)
149 {
150 struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
151
152 if (IS_ERR(ipcp))
153 return (struct shmid_kernel *)ipcp;
154
155 return container_of(ipcp, struct shmid_kernel, shm_perm);
156 }
157
158 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
159 {
160 ipc_rmid(&shm_ids(ns), &s->shm_perm);
161 }
162
163
164 /* This is called by fork, once for every shm attach. */
165 static void shm_open(struct vm_area_struct *vma)
166 {
167 struct file *file = vma->vm_file;
168 struct shm_file_data *sfd = shm_file_data(file);
169 struct shmid_kernel *shp;
170
171 shp = shm_lock(sfd->ns, sfd->id);
172 BUG_ON(IS_ERR(shp));
173 shp->shm_atim = get_seconds();
174 shp->shm_lprid = task_tgid_vnr(current);
175 shp->shm_nattch++;
176 shm_unlock(shp);
177 }
178
179 /*
180 * shm_destroy - free the struct shmid_kernel
181 *
182 * @ns: namespace
183 * @shp: struct to free
184 *
185 * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
186 * but returns with shp unlocked and freed.
187 */
188 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
189 {
190 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
191 shm_rmid(ns, shp);
192 shm_unlock(shp);
193 if (!is_file_hugepages(shp->shm_file))
194 shmem_lock(shp->shm_file, 0, shp->mlock_user);
195 else if (shp->mlock_user)
196 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
197 shp->mlock_user);
198 fput (shp->shm_file);
199 security_shm_free(shp);
200 ipc_rcu_putref(shp);
201 }
202
203 /*
204 * shm_may_destroy - identifies whether shm segment should be destroyed now
205 *
206 * Returns true if and only if there are no active users of the segment and
207 * one of the following is true:
208 *
209 * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
210 *
211 * 2) sysctl kernel.shm_rmid_forced is set to 1.
212 */
213 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
214 {
215 return (shp->shm_nattch == 0) &&
216 (ns->shm_rmid_forced ||
217 (shp->shm_perm.mode & SHM_DEST));
218 }
219
220 /*
221 * remove the attach descriptor vma.
222 * free memory for segment if it is marked destroyed.
223 * The descriptor has already been removed from the current->mm->mmap list
224 * and will later be kfree()d.
225 */
226 static void shm_close(struct vm_area_struct *vma)
227 {
228 struct file * file = vma->vm_file;
229 struct shm_file_data *sfd = shm_file_data(file);
230 struct shmid_kernel *shp;
231 struct ipc_namespace *ns = sfd->ns;
232
233 down_write(&shm_ids(ns).rw_mutex);
234 /* remove from the list of attaches of the shm segment */
235 shp = shm_lock(ns, sfd->id);
236 BUG_ON(IS_ERR(shp));
237 shp->shm_lprid = task_tgid_vnr(current);
238 shp->shm_dtim = get_seconds();
239 shp->shm_nattch--;
240 if (shm_may_destroy(ns, shp))
241 shm_destroy(ns, shp);
242 else
243 shm_unlock(shp);
244 up_write(&shm_ids(ns).rw_mutex);
245 }
246
247 /* Called with ns->shm_ids(ns).rw_mutex locked */
248 static int shm_try_destroy_current(int id, void *p, void *data)
249 {
250 struct ipc_namespace *ns = data;
251 struct kern_ipc_perm *ipcp = p;
252 struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
253
254 if (shp->shm_creator != current)
255 return 0;
256
257 /*
258 * Mark it as orphaned to destroy the segment when
259 * kernel.shm_rmid_forced is changed.
260 * It is noop if the following shm_may_destroy() returns true.
261 */
262 shp->shm_creator = NULL;
263
264 /*
265 * Don't even try to destroy it. If shm_rmid_forced=0 and IPC_RMID
266 * is not set, it shouldn't be deleted here.
267 */
268 if (!ns->shm_rmid_forced)
269 return 0;
270
271 if (shm_may_destroy(ns, shp)) {
272 shm_lock_by_ptr(shp);
273 shm_destroy(ns, shp);
274 }
275 return 0;
276 }
277
278 /* Called with ns->shm_ids(ns).rw_mutex locked */
279 static int shm_try_destroy_orphaned(int id, void *p, void *data)
280 {
281 struct ipc_namespace *ns = data;
282 struct kern_ipc_perm *ipcp = p;
283 struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
284
285 /*
286 * We want to destroy segments without users and with already
287 * exit'ed originating process.
288 *
289 * As shp->* are changed under rw_mutex, it's safe to skip shp locking.
290 */
291 if (shp->shm_creator != NULL)
292 return 0;
293
294 if (shm_may_destroy(ns, shp)) {
295 shm_lock_by_ptr(shp);
296 shm_destroy(ns, shp);
297 }
298 return 0;
299 }
300
301 void shm_destroy_orphaned(struct ipc_namespace *ns)
302 {
303 down_write(&shm_ids(ns).rw_mutex);
304 if (shm_ids(ns).in_use)
305 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
306 up_write(&shm_ids(ns).rw_mutex);
307 }
308
309
310 void exit_shm(struct task_struct *task)
311 {
312 struct ipc_namespace *ns = task->nsproxy->ipc_ns;
313
314 if (shm_ids(ns).in_use == 0)
315 return;
316
317 /* Destroy all already created segments, but not mapped yet */
318 down_write(&shm_ids(ns).rw_mutex);
319 if (shm_ids(ns).in_use)
320 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
321 up_write(&shm_ids(ns).rw_mutex);
322 }
323
324 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
325 {
326 struct file *file = vma->vm_file;
327 struct shm_file_data *sfd = shm_file_data(file);
328
329 return sfd->vm_ops->fault(vma, vmf);
330 }
331
332 #ifdef CONFIG_NUMA
333 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
334 {
335 struct file *file = vma->vm_file;
336 struct shm_file_data *sfd = shm_file_data(file);
337 int err = 0;
338 if (sfd->vm_ops->set_policy)
339 err = sfd->vm_ops->set_policy(vma, new);
340 return err;
341 }
342
343 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
344 unsigned long addr)
345 {
346 struct file *file = vma->vm_file;
347 struct shm_file_data *sfd = shm_file_data(file);
348 struct mempolicy *pol = NULL;
349
350 if (sfd->vm_ops->get_policy)
351 pol = sfd->vm_ops->get_policy(vma, addr);
352 else if (vma->vm_policy)
353 pol = vma->vm_policy;
354
355 return pol;
356 }
357 #endif
358
359 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
360 {
361 struct shm_file_data *sfd = shm_file_data(file);
362 int ret;
363
364 ret = sfd->file->f_op->mmap(sfd->file, vma);
365 if (ret != 0)
366 return ret;
367 sfd->vm_ops = vma->vm_ops;
368 #ifdef CONFIG_MMU
369 BUG_ON(!sfd->vm_ops->fault);
370 #endif
371 vma->vm_ops = &shm_vm_ops;
372 shm_open(vma);
373
374 return ret;
375 }
376
377 static int shm_release(struct inode *ino, struct file *file)
378 {
379 struct shm_file_data *sfd = shm_file_data(file);
380
381 put_ipc_ns(sfd->ns);
382 shm_file_data(file) = NULL;
383 kfree(sfd);
384 return 0;
385 }
386
387 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
388 {
389 struct shm_file_data *sfd = shm_file_data(file);
390
391 if (!sfd->file->f_op->fsync)
392 return -EINVAL;
393 return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
394 }
395
396 static long shm_fallocate(struct file *file, int mode, loff_t offset,
397 loff_t len)
398 {
399 struct shm_file_data *sfd = shm_file_data(file);
400
401 if (!sfd->file->f_op->fallocate)
402 return -EOPNOTSUPP;
403 return sfd->file->f_op->fallocate(file, mode, offset, len);
404 }
405
406 static unsigned long shm_get_unmapped_area(struct file *file,
407 unsigned long addr, unsigned long len, unsigned long pgoff,
408 unsigned long flags)
409 {
410 struct shm_file_data *sfd = shm_file_data(file);
411 return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
412 pgoff, flags);
413 }
414
415 static const struct file_operations shm_file_operations = {
416 .mmap = shm_mmap,
417 .fsync = shm_fsync,
418 .release = shm_release,
419 #ifndef CONFIG_MMU
420 .get_unmapped_area = shm_get_unmapped_area,
421 #endif
422 .llseek = noop_llseek,
423 .fallocate = shm_fallocate,
424 };
425
426 static const struct file_operations shm_file_operations_huge = {
427 .mmap = shm_mmap,
428 .fsync = shm_fsync,
429 .release = shm_release,
430 .get_unmapped_area = shm_get_unmapped_area,
431 .llseek = noop_llseek,
432 .fallocate = shm_fallocate,
433 };
434
435 int is_file_shm_hugepages(struct file *file)
436 {
437 return file->f_op == &shm_file_operations_huge;
438 }
439
440 static const struct vm_operations_struct shm_vm_ops = {
441 .open = shm_open, /* callback for a new vm-area open */
442 .close = shm_close, /* callback for when the vm-area is released */
443 .fault = shm_fault,
444 #if defined(CONFIG_NUMA)
445 .set_policy = shm_set_policy,
446 .get_policy = shm_get_policy,
447 #endif
448 };
449
450 /**
451 * newseg - Create a new shared memory segment
452 * @ns: namespace
453 * @params: ptr to the structure that contains key, size and shmflg
454 *
455 * Called with shm_ids.rw_mutex held as a writer.
456 */
457
458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
459 {
460 key_t key = params->key;
461 int shmflg = params->flg;
462 size_t size = params->u.size;
463 int error;
464 struct shmid_kernel *shp;
465 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
466 struct file * file;
467 char name[13];
468 int id;
469 vm_flags_t acctflag = 0;
470
471 if (size < SHMMIN || size > ns->shm_ctlmax)
472 return -EINVAL;
473
474 if (ns->shm_tot + numpages > ns->shm_ctlall)
475 return -ENOSPC;
476
477 shp = ipc_rcu_alloc(sizeof(*shp));
478 if (!shp)
479 return -ENOMEM;
480
481 shp->shm_perm.key = key;
482 shp->shm_perm.mode = (shmflg & S_IRWXUGO);
483 shp->mlock_user = NULL;
484
485 shp->shm_perm.security = NULL;
486 error = security_shm_alloc(shp);
487 if (error) {
488 ipc_rcu_putref(shp);
489 return error;
490 }
491
492 sprintf (name, "SYSV%08x", key);
493 if (shmflg & SHM_HUGETLB) {
494 /* hugetlb_file_setup applies strict accounting */
495 if (shmflg & SHM_NORESERVE)
496 acctflag = VM_NORESERVE;
497 file = hugetlb_file_setup(name, 0, size, acctflag,
498 &shp->mlock_user, HUGETLB_SHMFS_INODE);
499 } else {
500 /*
501 * Do not allow no accounting for OVERCOMMIT_NEVER, even
502 * if it's asked for.
503 */
504 if ((shmflg & SHM_NORESERVE) &&
505 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
506 acctflag = VM_NORESERVE;
507 file = shmem_file_setup(name, size, acctflag);
508 }
509 error = PTR_ERR(file);
510 if (IS_ERR(file))
511 goto no_file;
512
513 id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
514 if (id < 0) {
515 error = id;
516 goto no_id;
517 }
518
519 shp->shm_cprid = task_tgid_vnr(current);
520 shp->shm_lprid = 0;
521 shp->shm_atim = shp->shm_dtim = 0;
522 shp->shm_ctim = get_seconds();
523 shp->shm_segsz = size;
524 shp->shm_nattch = 0;
525 shp->shm_file = file;
526 shp->shm_creator = current;
527 /*
528 * shmid gets reported as "inode#" in /proc/pid/maps.
529 * proc-ps tools use this. Changing this will break them.
530 */
531 file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
532
533 ns->shm_tot += numpages;
534 error = shp->shm_perm.id;
535 shm_unlock(shp);
536 return error;
537
538 no_id:
539 if (is_file_hugepages(file) && shp->mlock_user)
540 user_shm_unlock(size, shp->mlock_user);
541 fput(file);
542 no_file:
543 security_shm_free(shp);
544 ipc_rcu_putref(shp);
545 return error;
546 }
547
548 /*
549 * Called with shm_ids.rw_mutex and ipcp locked.
550 */
551 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
552 {
553 struct shmid_kernel *shp;
554
555 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
556 return security_shm_associate(shp, shmflg);
557 }
558
559 /*
560 * Called with shm_ids.rw_mutex and ipcp locked.
561 */
562 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
563 struct ipc_params *params)
564 {
565 struct shmid_kernel *shp;
566
567 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
568 if (shp->shm_segsz < params->u.size)
569 return -EINVAL;
570
571 return 0;
572 }
573
574 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
575 {
576 struct ipc_namespace *ns;
577 struct ipc_ops shm_ops;
578 struct ipc_params shm_params;
579
580 ns = current->nsproxy->ipc_ns;
581
582 shm_ops.getnew = newseg;
583 shm_ops.associate = shm_security;
584 shm_ops.more_checks = shm_more_checks;
585
586 shm_params.key = key;
587 shm_params.flg = shmflg;
588 shm_params.u.size = size;
589
590 return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
591 }
592
593 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
594 {
595 switch(version) {
596 case IPC_64:
597 return copy_to_user(buf, in, sizeof(*in));
598 case IPC_OLD:
599 {
600 struct shmid_ds out;
601
602 memset(&out, 0, sizeof(out));
603 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
604 out.shm_segsz = in->shm_segsz;
605 out.shm_atime = in->shm_atime;
606 out.shm_dtime = in->shm_dtime;
607 out.shm_ctime = in->shm_ctime;
608 out.shm_cpid = in->shm_cpid;
609 out.shm_lpid = in->shm_lpid;
610 out.shm_nattch = in->shm_nattch;
611
612 return copy_to_user(buf, &out, sizeof(out));
613 }
614 default:
615 return -EINVAL;
616 }
617 }
618
619 static inline unsigned long
620 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
621 {
622 switch(version) {
623 case IPC_64:
624 if (copy_from_user(out, buf, sizeof(*out)))
625 return -EFAULT;
626 return 0;
627 case IPC_OLD:
628 {
629 struct shmid_ds tbuf_old;
630
631 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
632 return -EFAULT;
633
634 out->shm_perm.uid = tbuf_old.shm_perm.uid;
635 out->shm_perm.gid = tbuf_old.shm_perm.gid;
636 out->shm_perm.mode = tbuf_old.shm_perm.mode;
637
638 return 0;
639 }
640 default:
641 return -EINVAL;
642 }
643 }
644
645 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
646 {
647 switch(version) {
648 case IPC_64:
649 return copy_to_user(buf, in, sizeof(*in));
650 case IPC_OLD:
651 {
652 struct shminfo out;
653
654 if(in->shmmax > INT_MAX)
655 out.shmmax = INT_MAX;
656 else
657 out.shmmax = (int)in->shmmax;
658
659 out.shmmin = in->shmmin;
660 out.shmmni = in->shmmni;
661 out.shmseg = in->shmseg;
662 out.shmall = in->shmall;
663
664 return copy_to_user(buf, &out, sizeof(out));
665 }
666 default:
667 return -EINVAL;
668 }
669 }
670
671 /*
672 * Calculate and add used RSS and swap pages of a shm.
673 * Called with shm_ids.rw_mutex held as a reader
674 */
675 static void shm_add_rss_swap(struct shmid_kernel *shp,
676 unsigned long *rss_add, unsigned long *swp_add)
677 {
678 struct inode *inode;
679
680 inode = shp->shm_file->f_path.dentry->d_inode;
681
682 if (is_file_hugepages(shp->shm_file)) {
683 struct address_space *mapping = inode->i_mapping;
684 struct hstate *h = hstate_file(shp->shm_file);
685 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
686 } else {
687 #ifdef CONFIG_SHMEM
688 struct shmem_inode_info *info = SHMEM_I(inode);
689 spin_lock(&info->lock);
690 *rss_add += inode->i_mapping->nrpages;
691 *swp_add += info->swapped;
692 spin_unlock(&info->lock);
693 #else
694 *rss_add += inode->i_mapping->nrpages;
695 #endif
696 }
697 }
698
699 /*
700 * Called with shm_ids.rw_mutex held as a reader
701 */
702 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
703 unsigned long *swp)
704 {
705 int next_id;
706 int total, in_use;
707
708 *rss = 0;
709 *swp = 0;
710
711 in_use = shm_ids(ns).in_use;
712
713 for (total = 0, next_id = 0; total < in_use; next_id++) {
714 struct kern_ipc_perm *ipc;
715 struct shmid_kernel *shp;
716
717 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
718 if (ipc == NULL)
719 continue;
720 shp = container_of(ipc, struct shmid_kernel, shm_perm);
721
722 shm_add_rss_swap(shp, rss, swp);
723
724 total++;
725 }
726 }
727
728 /*
729 * This function handles some shmctl commands which require the rw_mutex
730 * to be held in write mode.
731 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
732 */
733 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
734 struct shmid_ds __user *buf, int version)
735 {
736 struct kern_ipc_perm *ipcp;
737 struct shmid64_ds shmid64;
738 struct shmid_kernel *shp;
739 int err;
740
741 if (cmd == IPC_SET) {
742 if (copy_shmid_from_user(&shmid64, buf, version))
743 return -EFAULT;
744 }
745
746 ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
747 &shmid64.shm_perm, 0);
748 if (IS_ERR(ipcp))
749 return PTR_ERR(ipcp);
750
751 shp = container_of(ipcp, struct shmid_kernel, shm_perm);
752
753 err = security_shm_shmctl(shp, cmd);
754 if (err)
755 goto out_unlock;
756 switch (cmd) {
757 case IPC_RMID:
758 do_shm_rmid(ns, ipcp);
759 goto out_up;
760 case IPC_SET:
761 ipc_update_perm(&shmid64.shm_perm, ipcp);
762 shp->shm_ctim = get_seconds();
763 break;
764 default:
765 err = -EINVAL;
766 }
767 out_unlock:
768 shm_unlock(shp);
769 out_up:
770 up_write(&shm_ids(ns).rw_mutex);
771 return err;
772 }
773
774 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
775 {
776 struct shmid_kernel *shp;
777 int err, version;
778 struct ipc_namespace *ns;
779
780 if (cmd < 0 || shmid < 0) {
781 err = -EINVAL;
782 goto out;
783 }
784
785 version = ipc_parse_version(&cmd);
786 ns = current->nsproxy->ipc_ns;
787
788 switch (cmd) { /* replace with proc interface ? */
789 case IPC_INFO:
790 {
791 struct shminfo64 shminfo;
792
793 err = security_shm_shmctl(NULL, cmd);
794 if (err)
795 return err;
796
797 memset(&shminfo, 0, sizeof(shminfo));
798 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
799 shminfo.shmmax = ns->shm_ctlmax;
800 shminfo.shmall = ns->shm_ctlall;
801
802 shminfo.shmmin = SHMMIN;
803 if(copy_shminfo_to_user (buf, &shminfo, version))
804 return -EFAULT;
805
806 down_read(&shm_ids(ns).rw_mutex);
807 err = ipc_get_maxid(&shm_ids(ns));
808 up_read(&shm_ids(ns).rw_mutex);
809
810 if(err<0)
811 err = 0;
812 goto out;
813 }
814 case SHM_INFO:
815 {
816 struct shm_info shm_info;
817
818 err = security_shm_shmctl(NULL, cmd);
819 if (err)
820 return err;
821
822 memset(&shm_info, 0, sizeof(shm_info));
823 down_read(&shm_ids(ns).rw_mutex);
824 shm_info.used_ids = shm_ids(ns).in_use;
825 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
826 shm_info.shm_tot = ns->shm_tot;
827 shm_info.swap_attempts = 0;
828 shm_info.swap_successes = 0;
829 err = ipc_get_maxid(&shm_ids(ns));
830 up_read(&shm_ids(ns).rw_mutex);
831 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
832 err = -EFAULT;
833 goto out;
834 }
835
836 err = err < 0 ? 0 : err;
837 goto out;
838 }
839 case SHM_STAT:
840 case IPC_STAT:
841 {
842 struct shmid64_ds tbuf;
843 int result;
844
845 if (cmd == SHM_STAT) {
846 shp = shm_lock(ns, shmid);
847 if (IS_ERR(shp)) {
848 err = PTR_ERR(shp);
849 goto out;
850 }
851 result = shp->shm_perm.id;
852 } else {
853 shp = shm_lock_check(ns, shmid);
854 if (IS_ERR(shp)) {
855 err = PTR_ERR(shp);
856 goto out;
857 }
858 result = 0;
859 }
860 err = -EACCES;
861 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
862 goto out_unlock;
863 err = security_shm_shmctl(shp, cmd);
864 if (err)
865 goto out_unlock;
866 memset(&tbuf, 0, sizeof(tbuf));
867 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
868 tbuf.shm_segsz = shp->shm_segsz;
869 tbuf.shm_atime = shp->shm_atim;
870 tbuf.shm_dtime = shp->shm_dtim;
871 tbuf.shm_ctime = shp->shm_ctim;
872 tbuf.shm_cpid = shp->shm_cprid;
873 tbuf.shm_lpid = shp->shm_lprid;
874 tbuf.shm_nattch = shp->shm_nattch;
875 shm_unlock(shp);
876 if(copy_shmid_to_user (buf, &tbuf, version))
877 err = -EFAULT;
878 else
879 err = result;
880 goto out;
881 }
882 case SHM_LOCK:
883 case SHM_UNLOCK:
884 {
885 struct file *shm_file;
886
887 shp = shm_lock_check(ns, shmid);
888 if (IS_ERR(shp)) {
889 err = PTR_ERR(shp);
890 goto out;
891 }
892
893 audit_ipc_obj(&(shp->shm_perm));
894
895 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
896 uid_t euid = current_euid();
897 err = -EPERM;
898 if (euid != shp->shm_perm.uid &&
899 euid != shp->shm_perm.cuid)
900 goto out_unlock;
901 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
902 goto out_unlock;
903 }
904
905 err = security_shm_shmctl(shp, cmd);
906 if (err)
907 goto out_unlock;
908
909 shm_file = shp->shm_file;
910 if (is_file_hugepages(shm_file))
911 goto out_unlock;
912
913 if (cmd == SHM_LOCK) {
914 struct user_struct *user = current_user();
915 err = shmem_lock(shm_file, 1, user);
916 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
917 shp->shm_perm.mode |= SHM_LOCKED;
918 shp->mlock_user = user;
919 }
920 goto out_unlock;
921 }
922
923 /* SHM_UNLOCK */
924 if (!(shp->shm_perm.mode & SHM_LOCKED))
925 goto out_unlock;
926 shmem_lock(shm_file, 0, shp->mlock_user);
927 shp->shm_perm.mode &= ~SHM_LOCKED;
928 shp->mlock_user = NULL;
929 get_file(shm_file);
930 shm_unlock(shp);
931 shmem_unlock_mapping(shm_file->f_mapping);
932 fput(shm_file);
933 goto out;
934 }
935 case IPC_RMID:
936 case IPC_SET:
937 err = shmctl_down(ns, shmid, cmd, buf, version);
938 return err;
939 default:
940 return -EINVAL;
941 }
942
943 out_unlock:
944 shm_unlock(shp);
945 out:
946 return err;
947 }
948
949 /*
950 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
951 *
952 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
953 * "raddr" thing points to kernel space, and there has to be a wrapper around
954 * this.
955 */
956 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
957 {
958 struct shmid_kernel *shp;
959 unsigned long addr;
960 unsigned long size;
961 struct file * file;
962 int err;
963 unsigned long flags;
964 unsigned long prot;
965 int acc_mode;
966 unsigned long user_addr;
967 struct ipc_namespace *ns;
968 struct shm_file_data *sfd;
969 struct path path;
970 fmode_t f_mode;
971
972 err = -EINVAL;
973 if (shmid < 0)
974 goto out;
975 else if ((addr = (ulong)shmaddr)) {
976 if (addr & (SHMLBA-1)) {
977 if (shmflg & SHM_RND)
978 addr &= ~(SHMLBA-1); /* round down */
979 else
980 #ifndef __ARCH_FORCE_SHMLBA
981 if (addr & ~PAGE_MASK)
982 #endif
983 goto out;
984 }
985 flags = MAP_SHARED | MAP_FIXED;
986 } else {
987 if ((shmflg & SHM_REMAP))
988 goto out;
989
990 flags = MAP_SHARED;
991 }
992
993 if (shmflg & SHM_RDONLY) {
994 prot = PROT_READ;
995 acc_mode = S_IRUGO;
996 f_mode = FMODE_READ;
997 } else {
998 prot = PROT_READ | PROT_WRITE;
999 acc_mode = S_IRUGO | S_IWUGO;
1000 f_mode = FMODE_READ | FMODE_WRITE;
1001 }
1002 if (shmflg & SHM_EXEC) {
1003 prot |= PROT_EXEC;
1004 acc_mode |= S_IXUGO;
1005 }
1006
1007 /*
1008 * We cannot rely on the fs check since SYSV IPC does have an
1009 * additional creator id...
1010 */
1011 ns = current->nsproxy->ipc_ns;
1012 shp = shm_lock_check(ns, shmid);
1013 if (IS_ERR(shp)) {
1014 err = PTR_ERR(shp);
1015 goto out;
1016 }
1017
1018 err = -EACCES;
1019 if (ipcperms(ns, &shp->shm_perm, acc_mode))
1020 goto out_unlock;
1021
1022 err = security_shm_shmat(shp, shmaddr, shmflg);
1023 if (err)
1024 goto out_unlock;
1025
1026 path = shp->shm_file->f_path;
1027 path_get(&path);
1028 shp->shm_nattch++;
1029 size = i_size_read(path.dentry->d_inode);
1030 shm_unlock(shp);
1031
1032 err = -ENOMEM;
1033 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1034 if (!sfd)
1035 goto out_put_dentry;
1036
1037 file = alloc_file(&path, f_mode,
1038 is_file_hugepages(shp->shm_file) ?
1039 &shm_file_operations_huge :
1040 &shm_file_operations);
1041 if (!file)
1042 goto out_free;
1043
1044 file->private_data = sfd;
1045 file->f_mapping = shp->shm_file->f_mapping;
1046 sfd->id = shp->shm_perm.id;
1047 sfd->ns = get_ipc_ns(ns);
1048 sfd->file = shp->shm_file;
1049 sfd->vm_ops = NULL;
1050
1051 err = security_mmap_file(file, prot, flags);
1052 if (err)
1053 goto out_fput;
1054
1055 down_write(&current->mm->mmap_sem);
1056 if (addr && !(shmflg & SHM_REMAP)) {
1057 err = -EINVAL;
1058 if (find_vma_intersection(current->mm, addr, addr + size))
1059 goto invalid;
1060 /*
1061 * If shm segment goes below stack, make sure there is some
1062 * space left for the stack to grow (at least 4 pages).
1063 */
1064 if (addr < current->mm->start_stack &&
1065 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1066 goto invalid;
1067 }
1068
1069 user_addr = do_mmap_pgoff(file, addr, size, prot, flags, 0);
1070 *raddr = user_addr;
1071 err = 0;
1072 if (IS_ERR_VALUE(user_addr))
1073 err = (long)user_addr;
1074 invalid:
1075 up_write(&current->mm->mmap_sem);
1076
1077 out_fput:
1078 fput(file);
1079
1080 out_nattch:
1081 down_write(&shm_ids(ns).rw_mutex);
1082 shp = shm_lock(ns, shmid);
1083 BUG_ON(IS_ERR(shp));
1084 shp->shm_nattch--;
1085 if (shm_may_destroy(ns, shp))
1086 shm_destroy(ns, shp);
1087 else
1088 shm_unlock(shp);
1089 up_write(&shm_ids(ns).rw_mutex);
1090
1091 out:
1092 return err;
1093
1094 out_unlock:
1095 shm_unlock(shp);
1096 goto out;
1097
1098 out_free:
1099 kfree(sfd);
1100 out_put_dentry:
1101 path_put(&path);
1102 goto out_nattch;
1103 }
1104
1105 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1106 {
1107 unsigned long ret;
1108 long err;
1109
1110 err = do_shmat(shmid, shmaddr, shmflg, &ret);
1111 if (err)
1112 return err;
1113 force_successful_syscall_return();
1114 return (long)ret;
1115 }
1116
1117 /*
1118 * detach and kill segment if marked destroyed.
1119 * The work is done in shm_close.
1120 */
1121 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1122 {
1123 struct mm_struct *mm = current->mm;
1124 struct vm_area_struct *vma;
1125 unsigned long addr = (unsigned long)shmaddr;
1126 int retval = -EINVAL;
1127 #ifdef CONFIG_MMU
1128 loff_t size = 0;
1129 struct vm_area_struct *next;
1130 #endif
1131
1132 if (addr & ~PAGE_MASK)
1133 return retval;
1134
1135 down_write(&mm->mmap_sem);
1136
1137 /*
1138 * This function tries to be smart and unmap shm segments that
1139 * were modified by partial mlock or munmap calls:
1140 * - It first determines the size of the shm segment that should be
1141 * unmapped: It searches for a vma that is backed by shm and that
1142 * started at address shmaddr. It records it's size and then unmaps
1143 * it.
1144 * - Then it unmaps all shm vmas that started at shmaddr and that
1145 * are within the initially determined size.
1146 * Errors from do_munmap are ignored: the function only fails if
1147 * it's called with invalid parameters or if it's called to unmap
1148 * a part of a vma. Both calls in this function are for full vmas,
1149 * the parameters are directly copied from the vma itself and always
1150 * valid - therefore do_munmap cannot fail. (famous last words?)
1151 */
1152 /*
1153 * If it had been mremap()'d, the starting address would not
1154 * match the usual checks anyway. So assume all vma's are
1155 * above the starting address given.
1156 */
1157 vma = find_vma(mm, addr);
1158
1159 #ifdef CONFIG_MMU
1160 while (vma) {
1161 next = vma->vm_next;
1162
1163 /*
1164 * Check if the starting address would match, i.e. it's
1165 * a fragment created by mprotect() and/or munmap(), or it
1166 * otherwise it starts at this address with no hassles.
1167 */
1168 if ((vma->vm_ops == &shm_vm_ops) &&
1169 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1170
1171
1172 size = vma->vm_file->f_path.dentry->d_inode->i_size;
1173 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1174 /*
1175 * We discovered the size of the shm segment, so
1176 * break out of here and fall through to the next
1177 * loop that uses the size information to stop
1178 * searching for matching vma's.
1179 */
1180 retval = 0;
1181 vma = next;
1182 break;
1183 }
1184 vma = next;
1185 }
1186
1187 /*
1188 * We need look no further than the maximum address a fragment
1189 * could possibly have landed at. Also cast things to loff_t to
1190 * prevent overflows and make comparisons vs. equal-width types.
1191 */
1192 size = PAGE_ALIGN(size);
1193 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1194 next = vma->vm_next;
1195
1196 /* finding a matching vma now does not alter retval */
1197 if ((vma->vm_ops == &shm_vm_ops) &&
1198 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1199
1200 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1201 vma = next;
1202 }
1203
1204 #else /* CONFIG_MMU */
1205 /* under NOMMU conditions, the exact address to be destroyed must be
1206 * given */
1207 retval = -EINVAL;
1208 if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1209 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1210 retval = 0;
1211 }
1212
1213 #endif
1214
1215 up_write(&mm->mmap_sem);
1216 return retval;
1217 }
1218
1219 #ifdef CONFIG_PROC_FS
1220 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1221 {
1222 struct shmid_kernel *shp = it;
1223 unsigned long rss = 0, swp = 0;
1224
1225 shm_add_rss_swap(shp, &rss, &swp);
1226
1227 #if BITS_PER_LONG <= 32
1228 #define SIZE_SPEC "%10lu"
1229 #else
1230 #define SIZE_SPEC "%21lu"
1231 #endif
1232
1233 return seq_printf(s,
1234 "%10d %10d %4o " SIZE_SPEC " %5u %5u "
1235 "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1236 SIZE_SPEC " " SIZE_SPEC "\n",
1237 shp->shm_perm.key,
1238 shp->shm_perm.id,
1239 shp->shm_perm.mode,
1240 shp->shm_segsz,
1241 shp->shm_cprid,
1242 shp->shm_lprid,
1243 shp->shm_nattch,
1244 shp->shm_perm.uid,
1245 shp->shm_perm.gid,
1246 shp->shm_perm.cuid,
1247 shp->shm_perm.cgid,
1248 shp->shm_atim,
1249 shp->shm_dtim,
1250 shp->shm_ctim,
1251 rss * PAGE_SIZE,
1252 swp * PAGE_SIZE);
1253 }
1254 #endif