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