1 /*
2 * An async IO implementation for Linux
3 * Written by Benjamin LaHaise <bcrl@kvack.org>
4 *
5 * Implements an efficient asynchronous io interface.
6 *
7 * Copyright 2000, 2001, 2002 Red Hat, Inc. All Rights Reserved.
8 * Copyright 2018 Christoph Hellwig.
9 *
10 * See ../COPYING for licensing terms.
11 */
12 #define pr_fmt(fmt) "%s: " fmt, __func__
13
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/errno.h>
17 #include <linux/time.h>
18 #include <linux/aio_abi.h>
19 #include <linux/export.h>
20 #include <linux/syscalls.h>
21 #include <linux/backing-dev.h>
22 #include <linux/refcount.h>
23 #include <linux/uio.h>
24
25 #include <linux/sched/signal.h>
26 #include <linux/fs.h>
27 #include <linux/file.h>
28 #include <linux/mm.h>
29 #include <linux/mman.h>
30 #include <linux/percpu.h>
31 #include <linux/slab.h>
32 #include <linux/timer.h>
33 #include <linux/aio.h>
34 #include <linux/highmem.h>
35 #include <linux/workqueue.h>
36 #include <linux/security.h>
37 #include <linux/eventfd.h>
38 #include <linux/blkdev.h>
39 #include <linux/compat.h>
40 #include <linux/migrate.h>
41 #include <linux/ramfs.h>
42 #include <linux/percpu-refcount.h>
43 #include <linux/mount.h>
44 #include <linux/pseudo_fs.h>
45
46 #include <linux/uaccess.h>
47 #include <linux/nospec.h>
48
49 #include "internal.h"
50
51 #define KIOCB_KEY 0
52
53 #define AIO_RING_MAGIC 0xa10a10a1
54 #define AIO_RING_COMPAT_FEATURES 1
55 #define AIO_RING_INCOMPAT_FEATURES 0
56 struct aio_ring {
57 unsigned id; /* kernel internal index number */
58 unsigned nr; /* number of io_events */
59 unsigned head; /* Written to by userland or under ring_lock
60 * mutex by aio_read_events_ring(). */
61 unsigned tail;
62
63 unsigned magic;
64 unsigned compat_features;
65 unsigned incompat_features;
66 unsigned header_length; /* size of aio_ring */
67
68
69 struct io_event io_events[];
70 }; /* 128 bytes + ring size */
71
72 /*
73 * Plugging is meant to work with larger batches of IOs. If we don't
74 * have more than the below, then don't bother setting up a plug.
75 */
76 #define AIO_PLUG_THRESHOLD 2
77
78 #define AIO_RING_PAGES 8
79
80 struct kioctx_table {
81 struct rcu_head rcu;
82 unsigned nr;
83 struct kioctx __rcu *table[] __counted_by(nr);
84 };
85
86 struct kioctx_cpu {
87 unsigned reqs_available;
88 };
89
90 struct ctx_rq_wait {
91 struct completion comp;
92 atomic_t count;
93 };
94
95 struct kioctx {
96 struct percpu_ref users;
97 atomic_t dead;
98
99 struct percpu_ref reqs;
100
101 unsigned long user_id;
102
103 struct __percpu kioctx_cpu *cpu;
104
105 /*
106 * For percpu reqs_available, number of slots we move to/from global
107 * counter at a time:
108 */
109 unsigned req_batch;
110 /*
111 * This is what userspace passed to io_setup(), it's not used for
112 * anything but counting against the global max_reqs quota.
113 *
114 * The real limit is nr_events - 1, which will be larger (see
115 * aio_setup_ring())
116 */
117 unsigned max_reqs;
118
119 /* Size of ringbuffer, in units of struct io_event */
120 unsigned nr_events;
121
122 unsigned long mmap_base;
123 unsigned long mmap_size;
124
125 struct page **ring_pages;
126 long nr_pages;
127
128 struct rcu_work free_rwork; /* see free_ioctx() */
129
130 /*
131 * signals when all in-flight requests are done
132 */
133 struct ctx_rq_wait *rq_wait;
134
135 struct {
136 /*
137 * This counts the number of available slots in the ringbuffer,
138 * so we avoid overflowing it: it's decremented (if positive)
139 * when allocating a kiocb and incremented when the resulting
140 * io_event is pulled off the ringbuffer.
141 *
142 * We batch accesses to it with a percpu version.
143 */
144 atomic_t reqs_available;
145 } ____cacheline_aligned_in_smp;
146
147 struct {
148 spinlock_t ctx_lock;
149 struct list_head active_reqs; /* used for cancellation */
150 } ____cacheline_aligned_in_smp;
151
152 struct {
153 struct mutex ring_lock;
154 wait_queue_head_t wait;
155 } ____cacheline_aligned_in_smp;
156
157 struct {
158 unsigned tail;
159 unsigned completed_events;
160 spinlock_t completion_lock;
161 } ____cacheline_aligned_in_smp;
162
163 struct page *internal_pages[AIO_RING_PAGES];
164 struct file *aio_ring_file;
165
166 unsigned id;
167 };
168
169 /*
170 * First field must be the file pointer in all the
171 * iocb unions! See also 'struct kiocb' in <linux/fs.h>
172 */
173 struct fsync_iocb {
174 struct file *file;
175 struct work_struct work;
176 bool datasync;
177 struct cred *creds;
178 };
179
180 struct poll_iocb {
181 struct file *file;
182 struct wait_queue_head *head;
183 __poll_t events;
184 bool cancelled;
185 bool work_scheduled;
186 bool work_need_resched;
187 struct wait_queue_entry wait;
188 struct work_struct work;
189 };
190
191 /*
192 * NOTE! Each of the iocb union members has the file pointer
193 * as the first entry in their struct definition. So you can
194 * access the file pointer through any of the sub-structs,
195 * or directly as just 'ki_filp' in this struct.
196 */
197 struct aio_kiocb {
198 union {
199 struct file *ki_filp;
200 struct kiocb rw;
201 struct fsync_iocb fsync;
202 struct poll_iocb poll;
203 };
204
205 struct kioctx *ki_ctx;
206 kiocb_cancel_fn *ki_cancel;
207
208 struct io_event ki_res;
209
210 struct list_head ki_list; /* the aio core uses this
211 * for cancellation */
212 refcount_t ki_refcnt;
213
214 /*
215 * If the aio_resfd field of the userspace iocb is not zero,
216 * this is the underlying eventfd context to deliver events to.
217 */
218 struct eventfd_ctx *ki_eventfd;
219 };
220
221 /*------ sysctl variables----*/
222 static DEFINE_SPINLOCK(aio_nr_lock);
223 static unsigned long aio_nr; /* current system wide number of aio requests */
224 static unsigned long aio_max_nr = 0x10000; /* system wide maximum number of aio requests */
225 /*----end sysctl variables---*/
226 #ifdef CONFIG_SYSCTL
227 static struct ctl_table aio_sysctls[] = {
228 {
229 .procname = "aio-nr",
230 .data = &aio_nr,
231 .maxlen = sizeof(aio_nr),
232 .mode = 0444,
233 .proc_handler = proc_doulongvec_minmax,
234 },
235 {
236 .procname = "aio-max-nr",
237 .data = &aio_max_nr,
238 .maxlen = sizeof(aio_max_nr),
239 .mode = 0644,
240 .proc_handler = proc_doulongvec_minmax,
241 },
242 {}
243 };
244
aio_sysctl_init(void)245 static void __init aio_sysctl_init(void)
246 {
247 register_sysctl_init("fs", aio_sysctls);
248 }
249 #else
250 #define aio_sysctl_init() do { } while (0)
251 #endif
252
253 static struct kmem_cache *kiocb_cachep;
254 static struct kmem_cache *kioctx_cachep;
255
256 static struct vfsmount *aio_mnt;
257
258 static const struct file_operations aio_ring_fops;
259 static const struct address_space_operations aio_ctx_aops;
260
aio_private_file(struct kioctx * ctx,loff_t nr_pages)261 static struct file *aio_private_file(struct kioctx *ctx, loff_t nr_pages)
262 {
263 struct file *file;
264 struct inode *inode = alloc_anon_inode(aio_mnt->mnt_sb);
265 if (IS_ERR(inode))
266 return ERR_CAST(inode);
267
268 inode->i_mapping->a_ops = &aio_ctx_aops;
269 inode->i_mapping->private_data = ctx;
270 inode->i_size = PAGE_SIZE * nr_pages;
271
272 file = alloc_file_pseudo(inode, aio_mnt, "[aio]",
273 O_RDWR, &aio_ring_fops);
274 if (IS_ERR(file))
275 iput(inode);
276 return file;
277 }
278
aio_init_fs_context(struct fs_context * fc)279 static int aio_init_fs_context(struct fs_context *fc)
280 {
281 if (!init_pseudo(fc, AIO_RING_MAGIC))
282 return -ENOMEM;
283 fc->s_iflags |= SB_I_NOEXEC;
284 return 0;
285 }
286
287 /* aio_setup
288 * Creates the slab caches used by the aio routines, panic on
289 * failure as this is done early during the boot sequence.
290 */
aio_setup(void)291 static int __init aio_setup(void)
292 {
293 static struct file_system_type aio_fs = {
294 .name = "aio",
295 .init_fs_context = aio_init_fs_context,
296 .kill_sb = kill_anon_super,
297 };
298 aio_mnt = kern_mount(&aio_fs);
299 if (IS_ERR(aio_mnt))
300 panic("Failed to create aio fs mount.");
301
302 kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
303 kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
304 aio_sysctl_init();
305 return 0;
306 }
307 __initcall(aio_setup);
308
put_aio_ring_file(struct kioctx * ctx)309 static void put_aio_ring_file(struct kioctx *ctx)
310 {
311 struct file *aio_ring_file = ctx->aio_ring_file;
312 struct address_space *i_mapping;
313
314 if (aio_ring_file) {
315 truncate_setsize(file_inode(aio_ring_file), 0);
316
317 /* Prevent further access to the kioctx from migratepages */
318 i_mapping = aio_ring_file->f_mapping;
319 spin_lock(&i_mapping->private_lock);
320 i_mapping->private_data = NULL;
321 ctx->aio_ring_file = NULL;
322 spin_unlock(&i_mapping->private_lock);
323
324 fput(aio_ring_file);
325 }
326 }
327
aio_free_ring(struct kioctx * ctx)328 static void aio_free_ring(struct kioctx *ctx)
329 {
330 int i;
331
332 /* Disconnect the kiotx from the ring file. This prevents future
333 * accesses to the kioctx from page migration.
334 */
335 put_aio_ring_file(ctx);
336
337 for (i = 0; i < ctx->nr_pages; i++) {
338 struct page *page;
339 pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
340 page_count(ctx->ring_pages[i]));
341 page = ctx->ring_pages[i];
342 if (!page)
343 continue;
344 ctx->ring_pages[i] = NULL;
345 put_page(page);
346 }
347
348 if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
349 kfree(ctx->ring_pages);
350 ctx->ring_pages = NULL;
351 }
352 }
353
aio_ring_mremap(struct vm_area_struct * vma)354 static int aio_ring_mremap(struct vm_area_struct *vma)
355 {
356 struct file *file = vma->vm_file;
357 struct mm_struct *mm = vma->vm_mm;
358 struct kioctx_table *table;
359 int i, res = -EINVAL;
360
361 spin_lock(&mm->ioctx_lock);
362 rcu_read_lock();
363 table = rcu_dereference(mm->ioctx_table);
364 if (!table)
365 goto out_unlock;
366
367 for (i = 0; i < table->nr; i++) {
368 struct kioctx *ctx;
369
370 ctx = rcu_dereference(table->table[i]);
371 if (ctx && ctx->aio_ring_file == file) {
372 if (!atomic_read(&ctx->dead)) {
373 ctx->user_id = ctx->mmap_base = vma->vm_start;
374 res = 0;
375 }
376 break;
377 }
378 }
379
380 out_unlock:
381 rcu_read_unlock();
382 spin_unlock(&mm->ioctx_lock);
383 return res;
384 }
385
386 static const struct vm_operations_struct aio_ring_vm_ops = {
387 .mremap = aio_ring_mremap,
388 #if IS_ENABLED(CONFIG_MMU)
389 .fault = filemap_fault,
390 .map_pages = filemap_map_pages,
391 .page_mkwrite = filemap_page_mkwrite,
392 #endif
393 };
394
aio_ring_mmap(struct file * file,struct vm_area_struct * vma)395 static int aio_ring_mmap(struct file *file, struct vm_area_struct *vma)
396 {
397 vm_flags_set(vma, VM_DONTEXPAND);
398 vma->vm_ops = &aio_ring_vm_ops;
399 return 0;
400 }
401
402 static const struct file_operations aio_ring_fops = {
403 .mmap = aio_ring_mmap,
404 };
405
406 #if IS_ENABLED(CONFIG_MIGRATION)
aio_migrate_folio(struct address_space * mapping,struct folio * dst,struct folio * src,enum migrate_mode mode)407 static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
408 struct folio *src, enum migrate_mode mode)
409 {
410 struct kioctx *ctx;
411 unsigned long flags;
412 pgoff_t idx;
413 int rc;
414
415 /*
416 * We cannot support the _NO_COPY case here, because copy needs to
417 * happen under the ctx->completion_lock. That does not work with the
418 * migration workflow of MIGRATE_SYNC_NO_COPY.
419 */
420 if (mode == MIGRATE_SYNC_NO_COPY)
421 return -EINVAL;
422
423 rc = 0;
424
425 /* mapping->private_lock here protects against the kioctx teardown. */
426 spin_lock(&mapping->private_lock);
427 ctx = mapping->private_data;
428 if (!ctx) {
429 rc = -EINVAL;
430 goto out;
431 }
432
433 /* The ring_lock mutex. The prevents aio_read_events() from writing
434 * to the ring's head, and prevents page migration from mucking in
435 * a partially initialized kiotx.
436 */
437 if (!mutex_trylock(&ctx->ring_lock)) {
438 rc = -EAGAIN;
439 goto out;
440 }
441
442 idx = src->index;
443 if (idx < (pgoff_t)ctx->nr_pages) {
444 /* Make sure the old folio hasn't already been changed */
445 if (ctx->ring_pages[idx] != &src->page)
446 rc = -EAGAIN;
447 } else
448 rc = -EINVAL;
449
450 if (rc != 0)
451 goto out_unlock;
452
453 /* Writeback must be complete */
454 BUG_ON(folio_test_writeback(src));
455 folio_get(dst);
456
457 rc = folio_migrate_mapping(mapping, dst, src, 1);
458 if (rc != MIGRATEPAGE_SUCCESS) {
459 folio_put(dst);
460 goto out_unlock;
461 }
462
463 /* Take completion_lock to prevent other writes to the ring buffer
464 * while the old folio is copied to the new. This prevents new
465 * events from being lost.
466 */
467 spin_lock_irqsave(&ctx->completion_lock, flags);
468 folio_migrate_copy(dst, src);
469 BUG_ON(ctx->ring_pages[idx] != &src->page);
470 ctx->ring_pages[idx] = &dst->page;
471 spin_unlock_irqrestore(&ctx->completion_lock, flags);
472
473 /* The old folio is no longer accessible. */
474 folio_put(src);
475
476 out_unlock:
477 mutex_unlock(&ctx->ring_lock);
478 out:
479 spin_unlock(&mapping->private_lock);
480 return rc;
481 }
482 #else
483 #define aio_migrate_folio NULL
484 #endif
485
486 static const struct address_space_operations aio_ctx_aops = {
487 .dirty_folio = noop_dirty_folio,
488 .migrate_folio = aio_migrate_folio,
489 };
490
aio_setup_ring(struct kioctx * ctx,unsigned int nr_events)491 static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
492 {
493 struct aio_ring *ring;
494 struct mm_struct *mm = current->mm;
495 unsigned long size, unused;
496 int nr_pages;
497 int i;
498 struct file *file;
499
500 /* Compensate for the ring buffer's head/tail overlap entry */
501 nr_events += 2; /* 1 is required, 2 for good luck */
502
503 size = sizeof(struct aio_ring);
504 size += sizeof(struct io_event) * nr_events;
505
506 nr_pages = PFN_UP(size);
507 if (nr_pages < 0)
508 return -EINVAL;
509
510 file = aio_private_file(ctx, nr_pages);
511 if (IS_ERR(file)) {
512 ctx->aio_ring_file = NULL;
513 return -ENOMEM;
514 }
515
516 ctx->aio_ring_file = file;
517 nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
518 / sizeof(struct io_event);
519
520 ctx->ring_pages = ctx->internal_pages;
521 if (nr_pages > AIO_RING_PAGES) {
522 ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
523 GFP_KERNEL);
524 if (!ctx->ring_pages) {
525 put_aio_ring_file(ctx);
526 return -ENOMEM;
527 }
528 }
529
530 for (i = 0; i < nr_pages; i++) {
531 struct page *page;
532 page = find_or_create_page(file->f_mapping,
533 i, GFP_USER | __GFP_ZERO);
534 if (!page)
535 break;
536 pr_debug("pid(%d) page[%d]->count=%d\n",
537 current->pid, i, page_count(page));
538 SetPageUptodate(page);
539 unlock_page(page);
540
541 ctx->ring_pages[i] = page;
542 }
543 ctx->nr_pages = i;
544
545 if (unlikely(i != nr_pages)) {
546 aio_free_ring(ctx);
547 return -ENOMEM;
548 }
549
550 ctx->mmap_size = nr_pages * PAGE_SIZE;
551 pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
552
553 if (mmap_write_lock_killable(mm)) {
554 ctx->mmap_size = 0;
555 aio_free_ring(ctx);
556 return -EINTR;
557 }
558
559 ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
560 PROT_READ | PROT_WRITE,
561 MAP_SHARED, 0, 0, &unused, NULL);
562 mmap_write_unlock(mm);
563 if (IS_ERR((void *)ctx->mmap_base)) {
564 ctx->mmap_size = 0;
565 aio_free_ring(ctx);
566 return -ENOMEM;
567 }
568
569 pr_debug("mmap address: 0x%08lx\n", ctx->mmap_base);
570
571 ctx->user_id = ctx->mmap_base;
572 ctx->nr_events = nr_events; /* trusted copy */
573
574 ring = page_address(ctx->ring_pages[0]);
575 ring->nr = nr_events; /* user copy */
576 ring->id = ~0U;
577 ring->head = ring->tail = 0;
578 ring->magic = AIO_RING_MAGIC;
579 ring->compat_features = AIO_RING_COMPAT_FEATURES;
580 ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
581 ring->header_length = sizeof(struct aio_ring);
582 flush_dcache_page(ctx->ring_pages[0]);
583
584 return 0;
585 }
586
587 #define AIO_EVENTS_PER_PAGE (PAGE_SIZE / sizeof(struct io_event))
588 #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event))
589 #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE)
590
kiocb_set_cancel_fn(struct kiocb * iocb,kiocb_cancel_fn * cancel)591 void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
592 {
593 struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
594 struct kioctx *ctx = req->ki_ctx;
595 unsigned long flags;
596
597 /*
598 * kiocb didn't come from aio or is neither a read nor a write, hence
599 * ignore it.
600 */
601 if (!(iocb->ki_flags & IOCB_AIO_RW))
602 return;
603
604 if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
605 return;
606
607 spin_lock_irqsave(&ctx->ctx_lock, flags);
608 list_add_tail(&req->ki_list, &ctx->active_reqs);
609 req->ki_cancel = cancel;
610 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
611 }
612 EXPORT_SYMBOL(kiocb_set_cancel_fn);
613
614 /*
615 * free_ioctx() should be RCU delayed to synchronize against the RCU
616 * protected lookup_ioctx() and also needs process context to call
617 * aio_free_ring(). Use rcu_work.
618 */
free_ioctx(struct work_struct * work)619 static void free_ioctx(struct work_struct *work)
620 {
621 struct kioctx *ctx = container_of(to_rcu_work(work), struct kioctx,
622 free_rwork);
623 pr_debug("freeing %p\n", ctx);
624
625 aio_free_ring(ctx);
626 free_percpu(ctx->cpu);
627 percpu_ref_exit(&ctx->reqs);
628 percpu_ref_exit(&ctx->users);
629 kmem_cache_free(kioctx_cachep, ctx);
630 }
631
free_ioctx_reqs(struct percpu_ref * ref)632 static void free_ioctx_reqs(struct percpu_ref *ref)
633 {
634 struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
635
636 /* At this point we know that there are no any in-flight requests */
637 if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
638 complete(&ctx->rq_wait->comp);
639
640 /* Synchronize against RCU protected table->table[] dereferences */
641 INIT_RCU_WORK(&ctx->free_rwork, free_ioctx);
642 queue_rcu_work(system_wq, &ctx->free_rwork);
643 }
644
645 /*
646 * When this function runs, the kioctx has been removed from the "hash table"
647 * and ctx->users has dropped to 0, so we know no more kiocbs can be submitted -
648 * now it's safe to cancel any that need to be.
649 */
free_ioctx_users(struct percpu_ref * ref)650 static void free_ioctx_users(struct percpu_ref *ref)
651 {
652 struct kioctx *ctx = container_of(ref, struct kioctx, users);
653 struct aio_kiocb *req;
654
655 spin_lock_irq(&ctx->ctx_lock);
656
657 while (!list_empty(&ctx->active_reqs)) {
658 req = list_first_entry(&ctx->active_reqs,
659 struct aio_kiocb, ki_list);
660 req->ki_cancel(&req->rw);
661 list_del_init(&req->ki_list);
662 }
663
664 spin_unlock_irq(&ctx->ctx_lock);
665
666 percpu_ref_kill(&ctx->reqs);
667 percpu_ref_put(&ctx->reqs);
668 }
669
ioctx_add_table(struct kioctx * ctx,struct mm_struct * mm)670 static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
671 {
672 unsigned i, new_nr;
673 struct kioctx_table *table, *old;
674 struct aio_ring *ring;
675
676 spin_lock(&mm->ioctx_lock);
677 table = rcu_dereference_raw(mm->ioctx_table);
678
679 while (1) {
680 if (table)
681 for (i = 0; i < table->nr; i++)
682 if (!rcu_access_pointer(table->table[i])) {
683 ctx->id = i;
684 rcu_assign_pointer(table->table[i], ctx);
685 spin_unlock(&mm->ioctx_lock);
686
687 /* While kioctx setup is in progress,
688 * we are protected from page migration
689 * changes ring_pages by ->ring_lock.
690 */
691 ring = page_address(ctx->ring_pages[0]);
692 ring->id = ctx->id;
693 return 0;
694 }
695
696 new_nr = (table ? table->nr : 1) * 4;
697 spin_unlock(&mm->ioctx_lock);
698
699 table = kzalloc(struct_size(table, table, new_nr), GFP_KERNEL);
700 if (!table)
701 return -ENOMEM;
702
703 table->nr = new_nr;
704
705 spin_lock(&mm->ioctx_lock);
706 old = rcu_dereference_raw(mm->ioctx_table);
707
708 if (!old) {
709 rcu_assign_pointer(mm->ioctx_table, table);
710 } else if (table->nr > old->nr) {
711 memcpy(table->table, old->table,
712 old->nr * sizeof(struct kioctx *));
713
714 rcu_assign_pointer(mm->ioctx_table, table);
715 kfree_rcu(old, rcu);
716 } else {
717 kfree(table);
718 table = old;
719 }
720 }
721 }
722
aio_nr_sub(unsigned nr)723 static void aio_nr_sub(unsigned nr)
724 {
725 spin_lock(&aio_nr_lock);
726 if (WARN_ON(aio_nr - nr > aio_nr))
727 aio_nr = 0;
728 else
729 aio_nr -= nr;
730 spin_unlock(&aio_nr_lock);
731 }
732
733 /* ioctx_alloc
734 * Allocates and initializes an ioctx. Returns an ERR_PTR if it failed.
735 */
ioctx_alloc(unsigned nr_events)736 static struct kioctx *ioctx_alloc(unsigned nr_events)
737 {
738 struct mm_struct *mm = current->mm;
739 struct kioctx *ctx;
740 int err = -ENOMEM;
741
742 /*
743 * Store the original nr_events -- what userspace passed to io_setup(),
744 * for counting against the global limit -- before it changes.
745 */
746 unsigned int max_reqs = nr_events;
747
748 /*
749 * We keep track of the number of available ringbuffer slots, to prevent
750 * overflow (reqs_available), and we also use percpu counters for this.
751 *
752 * So since up to half the slots might be on other cpu's percpu counters
753 * and unavailable, double nr_events so userspace sees what they
754 * expected: additionally, we move req_batch slots to/from percpu
755 * counters at a time, so make sure that isn't 0:
756 */
757 nr_events = max(nr_events, num_possible_cpus() * 4);
758 nr_events *= 2;
759
760 /* Prevent overflows */
761 if (nr_events > (0x10000000U / sizeof(struct io_event))) {
762 pr_debug("ENOMEM: nr_events too high\n");
763 return ERR_PTR(-EINVAL);
764 }
765
766 if (!nr_events || (unsigned long)max_reqs > aio_max_nr)
767 return ERR_PTR(-EAGAIN);
768
769 ctx = kmem_cache_zalloc(kioctx_cachep, GFP_KERNEL);
770 if (!ctx)
771 return ERR_PTR(-ENOMEM);
772
773 ctx->max_reqs = max_reqs;
774
775 spin_lock_init(&ctx->ctx_lock);
776 spin_lock_init(&ctx->completion_lock);
777 mutex_init(&ctx->ring_lock);
778 /* Protect against page migration throughout kiotx setup by keeping
779 * the ring_lock mutex held until setup is complete. */
780 mutex_lock(&ctx->ring_lock);
781 init_waitqueue_head(&ctx->wait);
782
783 INIT_LIST_HEAD(&ctx->active_reqs);
784
785 if (percpu_ref_init(&ctx->users, free_ioctx_users, 0, GFP_KERNEL))
786 goto err;
787
788 if (percpu_ref_init(&ctx->reqs, free_ioctx_reqs, 0, GFP_KERNEL))
789 goto err;
790
791 ctx->cpu = alloc_percpu(struct kioctx_cpu);
792 if (!ctx->cpu)
793 goto err;
794
795 err = aio_setup_ring(ctx, nr_events);
796 if (err < 0)
797 goto err;
798
799 atomic_set(&ctx->reqs_available, ctx->nr_events - 1);
800 ctx->req_batch = (ctx->nr_events - 1) / (num_possible_cpus() * 4);
801 if (ctx->req_batch < 1)
802 ctx->req_batch = 1;
803
804 /* limit the number of system wide aios */
805 spin_lock(&aio_nr_lock);
806 if (aio_nr + ctx->max_reqs > aio_max_nr ||
807 aio_nr + ctx->max_reqs < aio_nr) {
808 spin_unlock(&aio_nr_lock);
809 err = -EAGAIN;
810 goto err_ctx;
811 }
812 aio_nr += ctx->max_reqs;
813 spin_unlock(&aio_nr_lock);
814
815 percpu_ref_get(&ctx->users); /* io_setup() will drop this ref */
816 percpu_ref_get(&ctx->reqs); /* free_ioctx_users() will drop this */
817
818 err = ioctx_add_table(ctx, mm);
819 if (err)
820 goto err_cleanup;
821
822 /* Release the ring_lock mutex now that all setup is complete. */
823 mutex_unlock(&ctx->ring_lock);
824
825 pr_debug("allocated ioctx %p[%ld]: mm=%p mask=0x%x\n",
826 ctx, ctx->user_id, mm, ctx->nr_events);
827 return ctx;
828
829 err_cleanup:
830 aio_nr_sub(ctx->max_reqs);
831 err_ctx:
832 atomic_set(&ctx->dead, 1);
833 if (ctx->mmap_size)
834 vm_munmap(ctx->mmap_base, ctx->mmap_size);
835 aio_free_ring(ctx);
836 err:
837 mutex_unlock(&ctx->ring_lock);
838 free_percpu(ctx->cpu);
839 percpu_ref_exit(&ctx->reqs);
840 percpu_ref_exit(&ctx->users);
841 kmem_cache_free(kioctx_cachep, ctx);
842 pr_debug("error allocating ioctx %d\n", err);
843 return ERR_PTR(err);
844 }
845
846 /* kill_ioctx
847 * Cancels all outstanding aio requests on an aio context. Used
848 * when the processes owning a context have all exited to encourage
849 * the rapid destruction of the kioctx.
850 */
kill_ioctx(struct mm_struct * mm,struct kioctx * ctx,struct ctx_rq_wait * wait)851 static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
852 struct ctx_rq_wait *wait)
853 {
854 struct kioctx_table *table;
855
856 spin_lock(&mm->ioctx_lock);
857 if (atomic_xchg(&ctx->dead, 1)) {
858 spin_unlock(&mm->ioctx_lock);
859 return -EINVAL;
860 }
861
862 table = rcu_dereference_raw(mm->ioctx_table);
863 WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
864 RCU_INIT_POINTER(table->table[ctx->id], NULL);
865 spin_unlock(&mm->ioctx_lock);
866
867 /* free_ioctx_reqs() will do the necessary RCU synchronization */
868 wake_up_all(&ctx->wait);
869
870 /*
871 * It'd be more correct to do this in free_ioctx(), after all
872 * the outstanding kiocbs have finished - but by then io_destroy
873 * has already returned, so io_setup() could potentially return
874 * -EAGAIN with no ioctxs actually in use (as far as userspace
875 * could tell).
876 */
877 aio_nr_sub(ctx->max_reqs);
878
879 if (ctx->mmap_size)
880 vm_munmap(ctx->mmap_base, ctx->mmap_size);
881
882 ctx->rq_wait = wait;
883 percpu_ref_kill(&ctx->users);
884 return 0;
885 }
886
887 /*
888 * exit_aio: called when the last user of mm goes away. At this point, there is
889 * no way for any new requests to be submited or any of the io_* syscalls to be
890 * called on the context.
891 *
892 * There may be outstanding kiocbs, but free_ioctx() will explicitly wait on
893 * them.
894 */
exit_aio(struct mm_struct * mm)895 void exit_aio(struct mm_struct *mm)
896 {
897 struct kioctx_table *table = rcu_dereference_raw(mm->ioctx_table);
898 struct ctx_rq_wait wait;
899 int i, skipped;
900
901 if (!table)
902 return;
903
904 atomic_set(&wait.count, table->nr);
905 init_completion(&wait.comp);
906
907 skipped = 0;
908 for (i = 0; i < table->nr; ++i) {
909 struct kioctx *ctx =
910 rcu_dereference_protected(table->table[i], true);
911
912 if (!ctx) {
913 skipped++;
914 continue;
915 }
916
917 /*
918 * We don't need to bother with munmap() here - exit_mmap(mm)
919 * is coming and it'll unmap everything. And we simply can't,
920 * this is not necessarily our ->mm.
921 * Since kill_ioctx() uses non-zero ->mmap_size as indicator
922 * that it needs to unmap the area, just set it to 0.
923 */
924 ctx->mmap_size = 0;
925 kill_ioctx(mm, ctx, &wait);
926 }
927
928 if (!atomic_sub_and_test(skipped, &wait.count)) {
929 /* Wait until all IO for the context are done. */
930 wait_for_completion(&wait.comp);
931 }
932
933 RCU_INIT_POINTER(mm->ioctx_table, NULL);
934 kfree(table);
935 }
936
put_reqs_available(struct kioctx * ctx,unsigned nr)937 static void put_reqs_available(struct kioctx *ctx, unsigned nr)
938 {
939 struct kioctx_cpu *kcpu;
940 unsigned long flags;
941
942 local_irq_save(flags);
943 kcpu = this_cpu_ptr(ctx->cpu);
944 kcpu->reqs_available += nr;
945
946 while (kcpu->reqs_available >= ctx->req_batch * 2) {
947 kcpu->reqs_available -= ctx->req_batch;
948 atomic_add(ctx->req_batch, &ctx->reqs_available);
949 }
950
951 local_irq_restore(flags);
952 }
953
__get_reqs_available(struct kioctx * ctx)954 static bool __get_reqs_available(struct kioctx *ctx)
955 {
956 struct kioctx_cpu *kcpu;
957 bool ret = false;
958 unsigned long flags;
959
960 local_irq_save(flags);
961 kcpu = this_cpu_ptr(ctx->cpu);
962 if (!kcpu->reqs_available) {
963 int avail = atomic_read(&ctx->reqs_available);
964
965 do {
966 if (avail < ctx->req_batch)
967 goto out;
968 } while (!atomic_try_cmpxchg(&ctx->reqs_available,
969 &avail, avail - ctx->req_batch));
970
971 kcpu->reqs_available += ctx->req_batch;
972 }
973
974 ret = true;
975 kcpu->reqs_available--;
976 out:
977 local_irq_restore(flags);
978 return ret;
979 }
980
981 /* refill_reqs_available
982 * Updates the reqs_available reference counts used for tracking the
983 * number of free slots in the completion ring. This can be called
984 * from aio_complete() (to optimistically update reqs_available) or
985 * from aio_get_req() (the we're out of events case). It must be
986 * called holding ctx->completion_lock.
987 */
refill_reqs_available(struct kioctx * ctx,unsigned head,unsigned tail)988 static void refill_reqs_available(struct kioctx *ctx, unsigned head,
989 unsigned tail)
990 {
991 unsigned events_in_ring, completed;
992
993 /* Clamp head since userland can write to it. */
994 head %= ctx->nr_events;
995 if (head <= tail)
996 events_in_ring = tail - head;
997 else
998 events_in_ring = ctx->nr_events - (head - tail);
999
1000 completed = ctx->completed_events;
1001 if (events_in_ring < completed)
1002 completed -= events_in_ring;
1003 else
1004 completed = 0;
1005
1006 if (!completed)
1007 return;
1008
1009 ctx->completed_events -= completed;
1010 put_reqs_available(ctx, completed);
1011 }
1012
1013 /* user_refill_reqs_available
1014 * Called to refill reqs_available when aio_get_req() encounters an
1015 * out of space in the completion ring.
1016 */
user_refill_reqs_available(struct kioctx * ctx)1017 static void user_refill_reqs_available(struct kioctx *ctx)
1018 {
1019 spin_lock_irq(&ctx->completion_lock);
1020 if (ctx->completed_events) {
1021 struct aio_ring *ring;
1022 unsigned head;
1023
1024 /* Access of ring->head may race with aio_read_events_ring()
1025 * here, but that's okay since whether we read the old version
1026 * or the new version, and either will be valid. The important
1027 * part is that head cannot pass tail since we prevent
1028 * aio_complete() from updating tail by holding
1029 * ctx->completion_lock. Even if head is invalid, the check
1030 * against ctx->completed_events below will make sure we do the
1031 * safe/right thing.
1032 */
1033 ring = page_address(ctx->ring_pages[0]);
1034 head = ring->head;
1035
1036 refill_reqs_available(ctx, head, ctx->tail);
1037 }
1038
1039 spin_unlock_irq(&ctx->completion_lock);
1040 }
1041
get_reqs_available(struct kioctx * ctx)1042 static bool get_reqs_available(struct kioctx *ctx)
1043 {
1044 if (__get_reqs_available(ctx))
1045 return true;
1046 user_refill_reqs_available(ctx);
1047 return __get_reqs_available(ctx);
1048 }
1049
1050 /* aio_get_req
1051 * Allocate a slot for an aio request.
1052 * Returns NULL if no requests are free.
1053 *
1054 * The refcount is initialized to 2 - one for the async op completion,
1055 * one for the synchronous code that does this.
1056 */
aio_get_req(struct kioctx * ctx)1057 static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
1058 {
1059 struct aio_kiocb *req;
1060
1061 req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL);
1062 if (unlikely(!req))
1063 return NULL;
1064
1065 if (unlikely(!get_reqs_available(ctx))) {
1066 kmem_cache_free(kiocb_cachep, req);
1067 return NULL;
1068 }
1069
1070 percpu_ref_get(&ctx->reqs);
1071 req->ki_ctx = ctx;
1072 INIT_LIST_HEAD(&req->ki_list);
1073 refcount_set(&req->ki_refcnt, 2);
1074 req->ki_eventfd = NULL;
1075 return req;
1076 }
1077
lookup_ioctx(unsigned long ctx_id)1078 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
1079 {
1080 struct aio_ring __user *ring = (void __user *)ctx_id;
1081 struct mm_struct *mm = current->mm;
1082 struct kioctx *ctx, *ret = NULL;
1083 struct kioctx_table *table;
1084 unsigned id;
1085
1086 if (get_user(id, &ring->id))
1087 return NULL;
1088
1089 rcu_read_lock();
1090 table = rcu_dereference(mm->ioctx_table);
1091
1092 if (!table || id >= table->nr)
1093 goto out;
1094
1095 id = array_index_nospec(id, table->nr);
1096 ctx = rcu_dereference(table->table[id]);
1097 if (ctx && ctx->user_id == ctx_id) {
1098 if (percpu_ref_tryget_live(&ctx->users))
1099 ret = ctx;
1100 }
1101 out:
1102 rcu_read_unlock();
1103 return ret;
1104 }
1105
iocb_destroy(struct aio_kiocb * iocb)1106 static inline void iocb_destroy(struct aio_kiocb *iocb)
1107 {
1108 if (iocb->ki_eventfd)
1109 eventfd_ctx_put(iocb->ki_eventfd);
1110 if (iocb->ki_filp)
1111 fput(iocb->ki_filp);
1112 percpu_ref_put(&iocb->ki_ctx->reqs);
1113 kmem_cache_free(kiocb_cachep, iocb);
1114 }
1115
1116 /* aio_complete
1117 * Called when the io request on the given iocb is complete.
1118 */
aio_complete(struct aio_kiocb * iocb)1119 static void aio_complete(struct aio_kiocb *iocb)
1120 {
1121 struct kioctx *ctx = iocb->ki_ctx;
1122 struct aio_ring *ring;
1123 struct io_event *ev_page, *event;
1124 unsigned tail, pos, head;
1125 unsigned long flags;
1126
1127 /*
1128 * Add a completion event to the ring buffer. Must be done holding
1129 * ctx->completion_lock to prevent other code from messing with the tail
1130 * pointer since we might be called from irq context.
1131 */
1132 spin_lock_irqsave(&ctx->completion_lock, flags);
1133
1134 tail = ctx->tail;
1135 pos = tail + AIO_EVENTS_OFFSET;
1136
1137 if (++tail >= ctx->nr_events)
1138 tail = 0;
1139
1140 ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1141 event = ev_page + pos % AIO_EVENTS_PER_PAGE;
1142
1143 *event = iocb->ki_res;
1144
1145 flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
1146
1147 pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
1148 (void __user *)(unsigned long)iocb->ki_res.obj,
1149 iocb->ki_res.data, iocb->ki_res.res, iocb->ki_res.res2);
1150
1151 /* after flagging the request as done, we
1152 * must never even look at it again
1153 */
1154 smp_wmb(); /* make event visible before updating tail */
1155
1156 ctx->tail = tail;
1157
1158 ring = page_address(ctx->ring_pages[0]);
1159 head = ring->head;
1160 ring->tail = tail;
1161 flush_dcache_page(ctx->ring_pages[0]);
1162
1163 ctx->completed_events++;
1164 if (ctx->completed_events > 1)
1165 refill_reqs_available(ctx, head, tail);
1166 spin_unlock_irqrestore(&ctx->completion_lock, flags);
1167
1168 pr_debug("added to ring %p at [%u]\n", iocb, tail);
1169
1170 /*
1171 * Check if the user asked us to deliver the result through an
1172 * eventfd. The eventfd_signal() function is safe to be called
1173 * from IRQ context.
1174 */
1175 if (iocb->ki_eventfd)
1176 eventfd_signal(iocb->ki_eventfd, 1);
1177
1178 /*
1179 * We have to order our ring_info tail store above and test
1180 * of the wait list below outside the wait lock. This is
1181 * like in wake_up_bit() where clearing a bit has to be
1182 * ordered with the unlocked test.
1183 */
1184 smp_mb();
1185
1186 if (waitqueue_active(&ctx->wait))
1187 wake_up(&ctx->wait);
1188 }
1189
iocb_put(struct aio_kiocb * iocb)1190 static inline void iocb_put(struct aio_kiocb *iocb)
1191 {
1192 if (refcount_dec_and_test(&iocb->ki_refcnt)) {
1193 aio_complete(iocb);
1194 iocb_destroy(iocb);
1195 }
1196 }
1197
1198 /* aio_read_events_ring
1199 * Pull an event off of the ioctx's event ring. Returns the number of
1200 * events fetched
1201 */
aio_read_events_ring(struct kioctx * ctx,struct io_event __user * event,long nr)1202 static long aio_read_events_ring(struct kioctx *ctx,
1203 struct io_event __user *event, long nr)
1204 {
1205 struct aio_ring *ring;
1206 unsigned head, tail, pos;
1207 long ret = 0;
1208 int copy_ret;
1209
1210 /*
1211 * The mutex can block and wake us up and that will cause
1212 * wait_event_interruptible_hrtimeout() to schedule without sleeping
1213 * and repeat. This should be rare enough that it doesn't cause
1214 * peformance issues. See the comment in read_events() for more detail.
1215 */
1216 sched_annotate_sleep();
1217 mutex_lock(&ctx->ring_lock);
1218
1219 /* Access to ->ring_pages here is protected by ctx->ring_lock. */
1220 ring = page_address(ctx->ring_pages[0]);
1221 head = ring->head;
1222 tail = ring->tail;
1223
1224 /*
1225 * Ensure that once we've read the current tail pointer, that
1226 * we also see the events that were stored up to the tail.
1227 */
1228 smp_rmb();
1229
1230 pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
1231
1232 if (head == tail)
1233 goto out;
1234
1235 head %= ctx->nr_events;
1236 tail %= ctx->nr_events;
1237
1238 while (ret < nr) {
1239 long avail;
1240 struct io_event *ev;
1241 struct page *page;
1242
1243 avail = (head <= tail ? tail : ctx->nr_events) - head;
1244 if (head == tail)
1245 break;
1246
1247 pos = head + AIO_EVENTS_OFFSET;
1248 page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
1249 pos %= AIO_EVENTS_PER_PAGE;
1250
1251 avail = min(avail, nr - ret);
1252 avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
1253
1254 ev = page_address(page);
1255 copy_ret = copy_to_user(event + ret, ev + pos,
1256 sizeof(*ev) * avail);
1257
1258 if (unlikely(copy_ret)) {
1259 ret = -EFAULT;
1260 goto out;
1261 }
1262
1263 ret += avail;
1264 head += avail;
1265 head %= ctx->nr_events;
1266 }
1267
1268 ring = page_address(ctx->ring_pages[0]);
1269 ring->head = head;
1270 flush_dcache_page(ctx->ring_pages[0]);
1271
1272 pr_debug("%li h%u t%u\n", ret, head, tail);
1273 out:
1274 mutex_unlock(&ctx->ring_lock);
1275
1276 return ret;
1277 }
1278
aio_read_events(struct kioctx * ctx,long min_nr,long nr,struct io_event __user * event,long * i)1279 static bool aio_read_events(struct kioctx *ctx, long min_nr, long nr,
1280 struct io_event __user *event, long *i)
1281 {
1282 long ret = aio_read_events_ring(ctx, event + *i, nr - *i);
1283
1284 if (ret > 0)
1285 *i += ret;
1286
1287 if (unlikely(atomic_read(&ctx->dead)))
1288 ret = -EINVAL;
1289
1290 if (!*i)
1291 *i = ret;
1292
1293 return ret < 0 || *i >= min_nr;
1294 }
1295
read_events(struct kioctx * ctx,long min_nr,long nr,struct io_event __user * event,ktime_t until)1296 static long read_events(struct kioctx *ctx, long min_nr, long nr,
1297 struct io_event __user *event,
1298 ktime_t until)
1299 {
1300 long ret = 0;
1301
1302 /*
1303 * Note that aio_read_events() is being called as the conditional - i.e.
1304 * we're calling it after prepare_to_wait() has set task state to
1305 * TASK_INTERRUPTIBLE.
1306 *
1307 * But aio_read_events() can block, and if it blocks it's going to flip
1308 * the task state back to TASK_RUNNING.
1309 *
1310 * This should be ok, provided it doesn't flip the state back to
1311 * TASK_RUNNING and return 0 too much - that causes us to spin. That
1312 * will only happen if the mutex_lock() call blocks, and we then find
1313 * the ringbuffer empty. So in practice we should be ok, but it's
1314 * something to be aware of when touching this code.
1315 */
1316 if (until == 0)
1317 aio_read_events(ctx, min_nr, nr, event, &ret);
1318 else
1319 wait_event_interruptible_hrtimeout(ctx->wait,
1320 aio_read_events(ctx, min_nr, nr, event, &ret),
1321 until);
1322 return ret;
1323 }
1324
1325 /* sys_io_setup:
1326 * Create an aio_context capable of receiving at least nr_events.
1327 * ctxp must not point to an aio_context that already exists, and
1328 * must be initialized to 0 prior to the call. On successful
1329 * creation of the aio_context, *ctxp is filled in with the resulting
1330 * handle. May fail with -EINVAL if *ctxp is not initialized,
1331 * if the specified nr_events exceeds internal limits. May fail
1332 * with -EAGAIN if the specified nr_events exceeds the user's limit
1333 * of available events. May fail with -ENOMEM if insufficient kernel
1334 * resources are available. May fail with -EFAULT if an invalid
1335 * pointer is passed for ctxp. Will fail with -ENOSYS if not
1336 * implemented.
1337 */
SYSCALL_DEFINE2(io_setup,unsigned,nr_events,aio_context_t __user *,ctxp)1338 SYSCALL_DEFINE2(io_setup, unsigned, nr_events, aio_context_t __user *, ctxp)
1339 {
1340 struct kioctx *ioctx = NULL;
1341 unsigned long ctx;
1342 long ret;
1343
1344 ret = get_user(ctx, ctxp);
1345 if (unlikely(ret))
1346 goto out;
1347
1348 ret = -EINVAL;
1349 if (unlikely(ctx || nr_events == 0)) {
1350 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1351 ctx, nr_events);
1352 goto out;
1353 }
1354
1355 ioctx = ioctx_alloc(nr_events);
1356 ret = PTR_ERR(ioctx);
1357 if (!IS_ERR(ioctx)) {
1358 ret = put_user(ioctx->user_id, ctxp);
1359 if (ret)
1360 kill_ioctx(current->mm, ioctx, NULL);
1361 percpu_ref_put(&ioctx->users);
1362 }
1363
1364 out:
1365 return ret;
1366 }
1367
1368 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(io_setup,unsigned,nr_events,u32 __user *,ctx32p)1369 COMPAT_SYSCALL_DEFINE2(io_setup, unsigned, nr_events, u32 __user *, ctx32p)
1370 {
1371 struct kioctx *ioctx = NULL;
1372 unsigned long ctx;
1373 long ret;
1374
1375 ret = get_user(ctx, ctx32p);
1376 if (unlikely(ret))
1377 goto out;
1378
1379 ret = -EINVAL;
1380 if (unlikely(ctx || nr_events == 0)) {
1381 pr_debug("EINVAL: ctx %lu nr_events %u\n",
1382 ctx, nr_events);
1383 goto out;
1384 }
1385
1386 ioctx = ioctx_alloc(nr_events);
1387 ret = PTR_ERR(ioctx);
1388 if (!IS_ERR(ioctx)) {
1389 /* truncating is ok because it's a user address */
1390 ret = put_user((u32)ioctx->user_id, ctx32p);
1391 if (ret)
1392 kill_ioctx(current->mm, ioctx, NULL);
1393 percpu_ref_put(&ioctx->users);
1394 }
1395
1396 out:
1397 return ret;
1398 }
1399 #endif
1400
1401 /* sys_io_destroy:
1402 * Destroy the aio_context specified. May cancel any outstanding
1403 * AIOs and block on completion. Will fail with -ENOSYS if not
1404 * implemented. May fail with -EINVAL if the context pointed to
1405 * is invalid.
1406 */
SYSCALL_DEFINE1(io_destroy,aio_context_t,ctx)1407 SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
1408 {
1409 struct kioctx *ioctx = lookup_ioctx(ctx);
1410 if (likely(NULL != ioctx)) {
1411 struct ctx_rq_wait wait;
1412 int ret;
1413
1414 init_completion(&wait.comp);
1415 atomic_set(&wait.count, 1);
1416
1417 /* Pass requests_done to kill_ioctx() where it can be set
1418 * in a thread-safe way. If we try to set it here then we have
1419 * a race condition if two io_destroy() called simultaneously.
1420 */
1421 ret = kill_ioctx(current->mm, ioctx, &wait);
1422 percpu_ref_put(&ioctx->users);
1423
1424 /* Wait until all IO for the context are done. Otherwise kernel
1425 * keep using user-space buffers even if user thinks the context
1426 * is destroyed.
1427 */
1428 if (!ret)
1429 wait_for_completion(&wait.comp);
1430
1431 return ret;
1432 }
1433 pr_debug("EINVAL: invalid context id\n");
1434 return -EINVAL;
1435 }
1436
aio_remove_iocb(struct aio_kiocb * iocb)1437 static void aio_remove_iocb(struct aio_kiocb *iocb)
1438 {
1439 struct kioctx *ctx = iocb->ki_ctx;
1440 unsigned long flags;
1441
1442 spin_lock_irqsave(&ctx->ctx_lock, flags);
1443 list_del(&iocb->ki_list);
1444 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1445 }
1446
aio_complete_rw(struct kiocb * kiocb,long res)1447 static void aio_complete_rw(struct kiocb *kiocb, long res)
1448 {
1449 struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
1450
1451 if (!list_empty_careful(&iocb->ki_list))
1452 aio_remove_iocb(iocb);
1453
1454 if (kiocb->ki_flags & IOCB_WRITE) {
1455 struct inode *inode = file_inode(kiocb->ki_filp);
1456
1457 if (S_ISREG(inode->i_mode))
1458 kiocb_end_write(kiocb);
1459 }
1460
1461 iocb->ki_res.res = res;
1462 iocb->ki_res.res2 = 0;
1463 iocb_put(iocb);
1464 }
1465
aio_prep_rw(struct kiocb * req,const struct iocb * iocb)1466 static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
1467 {
1468 int ret;
1469
1470 req->ki_complete = aio_complete_rw;
1471 req->private = NULL;
1472 req->ki_pos = iocb->aio_offset;
1473 req->ki_flags = req->ki_filp->f_iocb_flags | IOCB_AIO_RW;
1474 if (iocb->aio_flags & IOCB_FLAG_RESFD)
1475 req->ki_flags |= IOCB_EVENTFD;
1476 if (iocb->aio_flags & IOCB_FLAG_IOPRIO) {
1477 /*
1478 * If the IOCB_FLAG_IOPRIO flag of aio_flags is set, then
1479 * aio_reqprio is interpreted as an I/O scheduling
1480 * class and priority.
1481 */
1482 ret = ioprio_check_cap(iocb->aio_reqprio);
1483 if (ret) {
1484 pr_debug("aio ioprio check cap error: %d\n", ret);
1485 return ret;
1486 }
1487
1488 req->ki_ioprio = iocb->aio_reqprio;
1489 } else
1490 req->ki_ioprio = get_current_ioprio();
1491
1492 ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
1493 if (unlikely(ret))
1494 return ret;
1495
1496 req->ki_flags &= ~IOCB_HIPRI; /* no one is going to poll for this I/O */
1497 return 0;
1498 }
1499
aio_setup_rw(int rw,const struct iocb * iocb,struct iovec ** iovec,bool vectored,bool compat,struct iov_iter * iter)1500 static ssize_t aio_setup_rw(int rw, const struct iocb *iocb,
1501 struct iovec **iovec, bool vectored, bool compat,
1502 struct iov_iter *iter)
1503 {
1504 void __user *buf = (void __user *)(uintptr_t)iocb->aio_buf;
1505 size_t len = iocb->aio_nbytes;
1506
1507 if (!vectored) {
1508 ssize_t ret = import_single_range(rw, buf, len, *iovec, iter);
1509 *iovec = NULL;
1510 return ret;
1511 }
1512
1513 return __import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter, compat);
1514 }
1515
aio_rw_done(struct kiocb * req,ssize_t ret)1516 static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
1517 {
1518 switch (ret) {
1519 case -EIOCBQUEUED:
1520 break;
1521 case -ERESTARTSYS:
1522 case -ERESTARTNOINTR:
1523 case -ERESTARTNOHAND:
1524 case -ERESTART_RESTARTBLOCK:
1525 /*
1526 * There's no easy way to restart the syscall since other AIO's
1527 * may be already running. Just fail this IO with EINTR.
1528 */
1529 ret = -EINTR;
1530 fallthrough;
1531 default:
1532 req->ki_complete(req, ret);
1533 }
1534 }
1535
aio_read(struct kiocb * req,const struct iocb * iocb,bool vectored,bool compat)1536 static int aio_read(struct kiocb *req, const struct iocb *iocb,
1537 bool vectored, bool compat)
1538 {
1539 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1540 struct iov_iter iter;
1541 struct file *file;
1542 int ret;
1543
1544 ret = aio_prep_rw(req, iocb);
1545 if (ret)
1546 return ret;
1547 file = req->ki_filp;
1548 if (unlikely(!(file->f_mode & FMODE_READ)))
1549 return -EBADF;
1550 if (unlikely(!file->f_op->read_iter))
1551 return -EINVAL;
1552
1553 ret = aio_setup_rw(ITER_DEST, iocb, &iovec, vectored, compat, &iter);
1554 if (ret < 0)
1555 return ret;
1556 ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
1557 if (!ret)
1558 aio_rw_done(req, call_read_iter(file, req, &iter));
1559 kfree(iovec);
1560 return ret;
1561 }
1562
aio_write(struct kiocb * req,const struct iocb * iocb,bool vectored,bool compat)1563 static int aio_write(struct kiocb *req, const struct iocb *iocb,
1564 bool vectored, bool compat)
1565 {
1566 struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
1567 struct iov_iter iter;
1568 struct file *file;
1569 int ret;
1570
1571 ret = aio_prep_rw(req, iocb);
1572 if (ret)
1573 return ret;
1574 file = req->ki_filp;
1575
1576 if (unlikely(!(file->f_mode & FMODE_WRITE)))
1577 return -EBADF;
1578 if (unlikely(!file->f_op->write_iter))
1579 return -EINVAL;
1580
1581 ret = aio_setup_rw(ITER_SOURCE, iocb, &iovec, vectored, compat, &iter);
1582 if (ret < 0)
1583 return ret;
1584 ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
1585 if (!ret) {
1586 if (S_ISREG(file_inode(file)->i_mode))
1587 kiocb_start_write(req);
1588 req->ki_flags |= IOCB_WRITE;
1589 aio_rw_done(req, call_write_iter(file, req, &iter));
1590 }
1591 kfree(iovec);
1592 return ret;
1593 }
1594
aio_fsync_work(struct work_struct * work)1595 static void aio_fsync_work(struct work_struct *work)
1596 {
1597 struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
1598 const struct cred *old_cred = override_creds(iocb->fsync.creds);
1599
1600 iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
1601 revert_creds(old_cred);
1602 put_cred(iocb->fsync.creds);
1603 iocb_put(iocb);
1604 }
1605
aio_fsync(struct fsync_iocb * req,const struct iocb * iocb,bool datasync)1606 static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
1607 bool datasync)
1608 {
1609 if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
1610 iocb->aio_rw_flags))
1611 return -EINVAL;
1612
1613 if (unlikely(!req->file->f_op->fsync))
1614 return -EINVAL;
1615
1616 req->creds = prepare_creds();
1617 if (!req->creds)
1618 return -ENOMEM;
1619
1620 req->datasync = datasync;
1621 INIT_WORK(&req->work, aio_fsync_work);
1622 schedule_work(&req->work);
1623 return 0;
1624 }
1625
aio_poll_put_work(struct work_struct * work)1626 static void aio_poll_put_work(struct work_struct *work)
1627 {
1628 struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1629 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1630
1631 iocb_put(iocb);
1632 }
1633
1634 /*
1635 * Safely lock the waitqueue which the request is on, synchronizing with the
1636 * case where the ->poll() provider decides to free its waitqueue early.
1637 *
1638 * Returns true on success, meaning that req->head->lock was locked, req->wait
1639 * is on req->head, and an RCU read lock was taken. Returns false if the
1640 * request was already removed from its waitqueue (which might no longer exist).
1641 */
poll_iocb_lock_wq(struct poll_iocb * req)1642 static bool poll_iocb_lock_wq(struct poll_iocb *req)
1643 {
1644 wait_queue_head_t *head;
1645
1646 /*
1647 * While we hold the waitqueue lock and the waitqueue is nonempty,
1648 * wake_up_pollfree() will wait for us. However, taking the waitqueue
1649 * lock in the first place can race with the waitqueue being freed.
1650 *
1651 * We solve this as eventpoll does: by taking advantage of the fact that
1652 * all users of wake_up_pollfree() will RCU-delay the actual free. If
1653 * we enter rcu_read_lock() and see that the pointer to the queue is
1654 * non-NULL, we can then lock it without the memory being freed out from
1655 * under us, then check whether the request is still on the queue.
1656 *
1657 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
1658 * case the caller deletes the entry from the queue, leaving it empty.
1659 * In that case, only RCU prevents the queue memory from being freed.
1660 */
1661 rcu_read_lock();
1662 head = smp_load_acquire(&req->head);
1663 if (head) {
1664 spin_lock(&head->lock);
1665 if (!list_empty(&req->wait.entry))
1666 return true;
1667 spin_unlock(&head->lock);
1668 }
1669 rcu_read_unlock();
1670 return false;
1671 }
1672
poll_iocb_unlock_wq(struct poll_iocb * req)1673 static void poll_iocb_unlock_wq(struct poll_iocb *req)
1674 {
1675 spin_unlock(&req->head->lock);
1676 rcu_read_unlock();
1677 }
1678
aio_poll_complete_work(struct work_struct * work)1679 static void aio_poll_complete_work(struct work_struct *work)
1680 {
1681 struct poll_iocb *req = container_of(work, struct poll_iocb, work);
1682 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1683 struct poll_table_struct pt = { ._key = req->events };
1684 struct kioctx *ctx = iocb->ki_ctx;
1685 __poll_t mask = 0;
1686
1687 if (!READ_ONCE(req->cancelled))
1688 mask = vfs_poll(req->file, &pt) & req->events;
1689
1690 /*
1691 * Note that ->ki_cancel callers also delete iocb from active_reqs after
1692 * calling ->ki_cancel. We need the ctx_lock roundtrip here to
1693 * synchronize with them. In the cancellation case the list_del_init
1694 * itself is not actually needed, but harmless so we keep it in to
1695 * avoid further branches in the fast path.
1696 */
1697 spin_lock_irq(&ctx->ctx_lock);
1698 if (poll_iocb_lock_wq(req)) {
1699 if (!mask && !READ_ONCE(req->cancelled)) {
1700 /*
1701 * The request isn't actually ready to be completed yet.
1702 * Reschedule completion if another wakeup came in.
1703 */
1704 if (req->work_need_resched) {
1705 schedule_work(&req->work);
1706 req->work_need_resched = false;
1707 } else {
1708 req->work_scheduled = false;
1709 }
1710 poll_iocb_unlock_wq(req);
1711 spin_unlock_irq(&ctx->ctx_lock);
1712 return;
1713 }
1714 list_del_init(&req->wait.entry);
1715 poll_iocb_unlock_wq(req);
1716 } /* else, POLLFREE has freed the waitqueue, so we must complete */
1717 list_del_init(&iocb->ki_list);
1718 iocb->ki_res.res = mangle_poll(mask);
1719 spin_unlock_irq(&ctx->ctx_lock);
1720
1721 iocb_put(iocb);
1722 }
1723
1724 /* assumes we are called with irqs disabled */
aio_poll_cancel(struct kiocb * iocb)1725 static int aio_poll_cancel(struct kiocb *iocb)
1726 {
1727 struct aio_kiocb *aiocb = container_of(iocb, struct aio_kiocb, rw);
1728 struct poll_iocb *req = &aiocb->poll;
1729
1730 if (poll_iocb_lock_wq(req)) {
1731 WRITE_ONCE(req->cancelled, true);
1732 if (!req->work_scheduled) {
1733 schedule_work(&aiocb->poll.work);
1734 req->work_scheduled = true;
1735 }
1736 poll_iocb_unlock_wq(req);
1737 } /* else, the request was force-cancelled by POLLFREE already */
1738
1739 return 0;
1740 }
1741
aio_poll_wake(struct wait_queue_entry * wait,unsigned mode,int sync,void * key)1742 static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
1743 void *key)
1744 {
1745 struct poll_iocb *req = container_of(wait, struct poll_iocb, wait);
1746 struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll);
1747 __poll_t mask = key_to_poll(key);
1748 unsigned long flags;
1749
1750 /* for instances that support it check for an event match first: */
1751 if (mask && !(mask & req->events))
1752 return 0;
1753
1754 /*
1755 * Complete the request inline if possible. This requires that three
1756 * conditions be met:
1757 * 1. An event mask must have been passed. If a plain wakeup was done
1758 * instead, then mask == 0 and we have to call vfs_poll() to get
1759 * the events, so inline completion isn't possible.
1760 * 2. The completion work must not have already been scheduled.
1761 * 3. ctx_lock must not be busy. We have to use trylock because we
1762 * already hold the waitqueue lock, so this inverts the normal
1763 * locking order. Use irqsave/irqrestore because not all
1764 * filesystems (e.g. fuse) call this function with IRQs disabled,
1765 * yet IRQs have to be disabled before ctx_lock is obtained.
1766 */
1767 if (mask && !req->work_scheduled &&
1768 spin_trylock_irqsave(&iocb->ki_ctx->ctx_lock, flags)) {
1769 struct kioctx *ctx = iocb->ki_ctx;
1770
1771 list_del_init(&req->wait.entry);
1772 list_del(&iocb->ki_list);
1773 iocb->ki_res.res = mangle_poll(mask);
1774 if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
1775 iocb = NULL;
1776 INIT_WORK(&req->work, aio_poll_put_work);
1777 schedule_work(&req->work);
1778 }
1779 spin_unlock_irqrestore(&ctx->ctx_lock, flags);
1780 if (iocb)
1781 iocb_put(iocb);
1782 } else {
1783 /*
1784 * Schedule the completion work if needed. If it was already
1785 * scheduled, record that another wakeup came in.
1786 *
1787 * Don't remove the request from the waitqueue here, as it might
1788 * not actually be complete yet (we won't know until vfs_poll()
1789 * is called), and we must not miss any wakeups. POLLFREE is an
1790 * exception to this; see below.
1791 */
1792 if (req->work_scheduled) {
1793 req->work_need_resched = true;
1794 } else {
1795 schedule_work(&req->work);
1796 req->work_scheduled = true;
1797 }
1798
1799 /*
1800 * If the waitqueue is being freed early but we can't complete
1801 * the request inline, we have to tear down the request as best
1802 * we can. That means immediately removing the request from its
1803 * waitqueue and preventing all further accesses to the
1804 * waitqueue via the request. We also need to schedule the
1805 * completion work (done above). Also mark the request as
1806 * cancelled, to potentially skip an unneeded call to ->poll().
1807 */
1808 if (mask & POLLFREE) {
1809 WRITE_ONCE(req->cancelled, true);
1810 list_del_init(&req->wait.entry);
1811
1812 /*
1813 * Careful: this *must* be the last step, since as soon
1814 * as req->head is NULL'ed out, the request can be
1815 * completed and freed, since aio_poll_complete_work()
1816 * will no longer need to take the waitqueue lock.
1817 */
1818 smp_store_release(&req->head, NULL);
1819 }
1820 }
1821 return 1;
1822 }
1823
1824 struct aio_poll_table {
1825 struct poll_table_struct pt;
1826 struct aio_kiocb *iocb;
1827 bool queued;
1828 int error;
1829 };
1830
1831 static void
aio_poll_queue_proc(struct file * file,struct wait_queue_head * head,struct poll_table_struct * p)1832 aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
1833 struct poll_table_struct *p)
1834 {
1835 struct aio_poll_table *pt = container_of(p, struct aio_poll_table, pt);
1836
1837 /* multiple wait queues per file are not supported */
1838 if (unlikely(pt->queued)) {
1839 pt->error = -EINVAL;
1840 return;
1841 }
1842
1843 pt->queued = true;
1844 pt->error = 0;
1845 pt->iocb->poll.head = head;
1846 add_wait_queue(head, &pt->iocb->poll.wait);
1847 }
1848
aio_poll(struct aio_kiocb * aiocb,const struct iocb * iocb)1849 static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
1850 {
1851 struct kioctx *ctx = aiocb->ki_ctx;
1852 struct poll_iocb *req = &aiocb->poll;
1853 struct aio_poll_table apt;
1854 bool cancel = false;
1855 __poll_t mask;
1856
1857 /* reject any unknown events outside the normal event mask. */
1858 if ((u16)iocb->aio_buf != iocb->aio_buf)
1859 return -EINVAL;
1860 /* reject fields that are not defined for poll */
1861 if (iocb->aio_offset || iocb->aio_nbytes || iocb->aio_rw_flags)
1862 return -EINVAL;
1863
1864 INIT_WORK(&req->work, aio_poll_complete_work);
1865 req->events = demangle_poll(iocb->aio_buf) | EPOLLERR | EPOLLHUP;
1866
1867 req->head = NULL;
1868 req->cancelled = false;
1869 req->work_scheduled = false;
1870 req->work_need_resched = false;
1871
1872 apt.pt._qproc = aio_poll_queue_proc;
1873 apt.pt._key = req->events;
1874 apt.iocb = aiocb;
1875 apt.queued = false;
1876 apt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
1877
1878 /* initialized the list so that we can do list_empty checks */
1879 INIT_LIST_HEAD(&req->wait.entry);
1880 init_waitqueue_func_entry(&req->wait, aio_poll_wake);
1881
1882 mask = vfs_poll(req->file, &apt.pt) & req->events;
1883 spin_lock_irq(&ctx->ctx_lock);
1884 if (likely(apt.queued)) {
1885 bool on_queue = poll_iocb_lock_wq(req);
1886
1887 if (!on_queue || req->work_scheduled) {
1888 /*
1889 * aio_poll_wake() already either scheduled the async
1890 * completion work, or completed the request inline.
1891 */
1892 if (apt.error) /* unsupported case: multiple queues */
1893 cancel = true;
1894 apt.error = 0;
1895 mask = 0;
1896 }
1897 if (mask || apt.error) {
1898 /* Steal to complete synchronously. */
1899 list_del_init(&req->wait.entry);
1900 } else if (cancel) {
1901 /* Cancel if possible (may be too late though). */
1902 WRITE_ONCE(req->cancelled, true);
1903 } else if (on_queue) {
1904 /*
1905 * Actually waiting for an event, so add the request to
1906 * active_reqs so that it can be cancelled if needed.
1907 */
1908 list_add_tail(&aiocb->ki_list, &ctx->active_reqs);
1909 aiocb->ki_cancel = aio_poll_cancel;
1910 }
1911 if (on_queue)
1912 poll_iocb_unlock_wq(req);
1913 }
1914 if (mask) { /* no async, we'd stolen it */
1915 aiocb->ki_res.res = mangle_poll(mask);
1916 apt.error = 0;
1917 }
1918 spin_unlock_irq(&ctx->ctx_lock);
1919 if (mask)
1920 iocb_put(aiocb);
1921 return apt.error;
1922 }
1923
__io_submit_one(struct kioctx * ctx,const struct iocb * iocb,struct iocb __user * user_iocb,struct aio_kiocb * req,bool compat)1924 static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
1925 struct iocb __user *user_iocb, struct aio_kiocb *req,
1926 bool compat)
1927 {
1928 req->ki_filp = fget(iocb->aio_fildes);
1929 if (unlikely(!req->ki_filp))
1930 return -EBADF;
1931
1932 if (iocb->aio_flags & IOCB_FLAG_RESFD) {
1933 struct eventfd_ctx *eventfd;
1934 /*
1935 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
1936 * instance of the file* now. The file descriptor must be
1937 * an eventfd() fd, and will be signaled for each completed
1938 * event using the eventfd_signal() function.
1939 */
1940 eventfd = eventfd_ctx_fdget(iocb->aio_resfd);
1941 if (IS_ERR(eventfd))
1942 return PTR_ERR(eventfd);
1943
1944 req->ki_eventfd = eventfd;
1945 }
1946
1947 if (unlikely(put_user(KIOCB_KEY, &user_iocb->aio_key))) {
1948 pr_debug("EFAULT: aio_key\n");
1949 return -EFAULT;
1950 }
1951
1952 req->ki_res.obj = (u64)(unsigned long)user_iocb;
1953 req->ki_res.data = iocb->aio_data;
1954 req->ki_res.res = 0;
1955 req->ki_res.res2 = 0;
1956
1957 switch (iocb->aio_lio_opcode) {
1958 case IOCB_CMD_PREAD:
1959 return aio_read(&req->rw, iocb, false, compat);
1960 case IOCB_CMD_PWRITE:
1961 return aio_write(&req->rw, iocb, false, compat);
1962 case IOCB_CMD_PREADV:
1963 return aio_read(&req->rw, iocb, true, compat);
1964 case IOCB_CMD_PWRITEV:
1965 return aio_write(&req->rw, iocb, true, compat);
1966 case IOCB_CMD_FSYNC:
1967 return aio_fsync(&req->fsync, iocb, false);
1968 case IOCB_CMD_FDSYNC:
1969 return aio_fsync(&req->fsync, iocb, true);
1970 case IOCB_CMD_POLL:
1971 return aio_poll(req, iocb);
1972 default:
1973 pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
1974 return -EINVAL;
1975 }
1976 }
1977
io_submit_one(struct kioctx * ctx,struct iocb __user * user_iocb,bool compat)1978 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
1979 bool compat)
1980 {
1981 struct aio_kiocb *req;
1982 struct iocb iocb;
1983 int err;
1984
1985 if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
1986 return -EFAULT;
1987
1988 /* enforce forwards compatibility on users */
1989 if (unlikely(iocb.aio_reserved2)) {
1990 pr_debug("EINVAL: reserve field set\n");
1991 return -EINVAL;
1992 }
1993
1994 /* prevent overflows */
1995 if (unlikely(
1996 (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
1997 (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
1998 ((ssize_t)iocb.aio_nbytes < 0)
1999 )) {
2000 pr_debug("EINVAL: overflow check\n");
2001 return -EINVAL;
2002 }
2003
2004 req = aio_get_req(ctx);
2005 if (unlikely(!req))
2006 return -EAGAIN;
2007
2008 err = __io_submit_one(ctx, &iocb, user_iocb, req, compat);
2009
2010 /* Done with the synchronous reference */
2011 iocb_put(req);
2012
2013 /*
2014 * If err is 0, we'd either done aio_complete() ourselves or have
2015 * arranged for that to be done asynchronously. Anything non-zero
2016 * means that we need to destroy req ourselves.
2017 */
2018 if (unlikely(err)) {
2019 iocb_destroy(req);
2020 put_reqs_available(ctx, 1);
2021 }
2022 return err;
2023 }
2024
2025 /* sys_io_submit:
2026 * Queue the nr iocbs pointed to by iocbpp for processing. Returns
2027 * the number of iocbs queued. May return -EINVAL if the aio_context
2028 * specified by ctx_id is invalid, if nr is < 0, if the iocb at
2029 * *iocbpp[0] is not properly initialized, if the operation specified
2030 * is invalid for the file descriptor in the iocb. May fail with
2031 * -EFAULT if any of the data structures point to invalid data. May
2032 * fail with -EBADF if the file descriptor specified in the first
2033 * iocb is invalid. May fail with -EAGAIN if insufficient resources
2034 * are available to queue any iocbs. Will return 0 if nr is 0. Will
2035 * fail with -ENOSYS if not implemented.
2036 */
SYSCALL_DEFINE3(io_submit,aio_context_t,ctx_id,long,nr,struct iocb __user * __user *,iocbpp)2037 SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr,
2038 struct iocb __user * __user *, iocbpp)
2039 {
2040 struct kioctx *ctx;
2041 long ret = 0;
2042 int i = 0;
2043 struct blk_plug plug;
2044
2045 if (unlikely(nr < 0))
2046 return -EINVAL;
2047
2048 ctx = lookup_ioctx(ctx_id);
2049 if (unlikely(!ctx)) {
2050 pr_debug("EINVAL: invalid context id\n");
2051 return -EINVAL;
2052 }
2053
2054 if (nr > ctx->nr_events)
2055 nr = ctx->nr_events;
2056
2057 if (nr > AIO_PLUG_THRESHOLD)
2058 blk_start_plug(&plug);
2059 for (i = 0; i < nr; i++) {
2060 struct iocb __user *user_iocb;
2061
2062 if (unlikely(get_user(user_iocb, iocbpp + i))) {
2063 ret = -EFAULT;
2064 break;
2065 }
2066
2067 ret = io_submit_one(ctx, user_iocb, false);
2068 if (ret)
2069 break;
2070 }
2071 if (nr > AIO_PLUG_THRESHOLD)
2072 blk_finish_plug(&plug);
2073
2074 percpu_ref_put(&ctx->users);
2075 return i ? i : ret;
2076 }
2077
2078 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE3(io_submit,compat_aio_context_t,ctx_id,int,nr,compat_uptr_t __user *,iocbpp)2079 COMPAT_SYSCALL_DEFINE3(io_submit, compat_aio_context_t, ctx_id,
2080 int, nr, compat_uptr_t __user *, iocbpp)
2081 {
2082 struct kioctx *ctx;
2083 long ret = 0;
2084 int i = 0;
2085 struct blk_plug plug;
2086
2087 if (unlikely(nr < 0))
2088 return -EINVAL;
2089
2090 ctx = lookup_ioctx(ctx_id);
2091 if (unlikely(!ctx)) {
2092 pr_debug("EINVAL: invalid context id\n");
2093 return -EINVAL;
2094 }
2095
2096 if (nr > ctx->nr_events)
2097 nr = ctx->nr_events;
2098
2099 if (nr > AIO_PLUG_THRESHOLD)
2100 blk_start_plug(&plug);
2101 for (i = 0; i < nr; i++) {
2102 compat_uptr_t user_iocb;
2103
2104 if (unlikely(get_user(user_iocb, iocbpp + i))) {
2105 ret = -EFAULT;
2106 break;
2107 }
2108
2109 ret = io_submit_one(ctx, compat_ptr(user_iocb), true);
2110 if (ret)
2111 break;
2112 }
2113 if (nr > AIO_PLUG_THRESHOLD)
2114 blk_finish_plug(&plug);
2115
2116 percpu_ref_put(&ctx->users);
2117 return i ? i : ret;
2118 }
2119 #endif
2120
2121 /* sys_io_cancel:
2122 * Attempts to cancel an iocb previously passed to io_submit. If
2123 * the operation is successfully cancelled, the resulting event is
2124 * copied into the memory pointed to by result without being placed
2125 * into the completion queue and 0 is returned. May fail with
2126 * -EFAULT if any of the data structures pointed to are invalid.
2127 * May fail with -EINVAL if aio_context specified by ctx_id is
2128 * invalid. May fail with -EAGAIN if the iocb specified was not
2129 * cancelled. Will fail with -ENOSYS if not implemented.
2130 */
SYSCALL_DEFINE3(io_cancel,aio_context_t,ctx_id,struct iocb __user *,iocb,struct io_event __user *,result)2131 SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
2132 struct io_event __user *, result)
2133 {
2134 struct kioctx *ctx;
2135 struct aio_kiocb *kiocb;
2136 int ret = -EINVAL;
2137 u32 key;
2138 u64 obj = (u64)(unsigned long)iocb;
2139
2140 if (unlikely(get_user(key, &iocb->aio_key)))
2141 return -EFAULT;
2142 if (unlikely(key != KIOCB_KEY))
2143 return -EINVAL;
2144
2145 ctx = lookup_ioctx(ctx_id);
2146 if (unlikely(!ctx))
2147 return -EINVAL;
2148
2149 spin_lock_irq(&ctx->ctx_lock);
2150 /* TODO: use a hash or array, this sucks. */
2151 list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) {
2152 if (kiocb->ki_res.obj == obj) {
2153 ret = kiocb->ki_cancel(&kiocb->rw);
2154 list_del_init(&kiocb->ki_list);
2155 break;
2156 }
2157 }
2158 spin_unlock_irq(&ctx->ctx_lock);
2159
2160 if (!ret) {
2161 /*
2162 * The result argument is no longer used - the io_event is
2163 * always delivered via the ring buffer. -EINPROGRESS indicates
2164 * cancellation is progress:
2165 */
2166 ret = -EINPROGRESS;
2167 }
2168
2169 percpu_ref_put(&ctx->users);
2170
2171 return ret;
2172 }
2173
do_io_getevents(aio_context_t ctx_id,long min_nr,long nr,struct io_event __user * events,struct timespec64 * ts)2174 static long do_io_getevents(aio_context_t ctx_id,
2175 long min_nr,
2176 long nr,
2177 struct io_event __user *events,
2178 struct timespec64 *ts)
2179 {
2180 ktime_t until = ts ? timespec64_to_ktime(*ts) : KTIME_MAX;
2181 struct kioctx *ioctx = lookup_ioctx(ctx_id);
2182 long ret = -EINVAL;
2183
2184 if (likely(ioctx)) {
2185 if (likely(min_nr <= nr && min_nr >= 0))
2186 ret = read_events(ioctx, min_nr, nr, events, until);
2187 percpu_ref_put(&ioctx->users);
2188 }
2189
2190 return ret;
2191 }
2192
2193 /* io_getevents:
2194 * Attempts to read at least min_nr events and up to nr events from
2195 * the completion queue for the aio_context specified by ctx_id. If
2196 * it succeeds, the number of read events is returned. May fail with
2197 * -EINVAL if ctx_id is invalid, if min_nr is out of range, if nr is
2198 * out of range, if timeout is out of range. May fail with -EFAULT
2199 * if any of the memory specified is invalid. May return 0 or
2200 * < min_nr if the timeout specified by timeout has elapsed
2201 * before sufficient events are available, where timeout == NULL
2202 * specifies an infinite timeout. Note that the timeout pointed to by
2203 * timeout is relative. Will fail with -ENOSYS if not implemented.
2204 */
2205 #ifdef CONFIG_64BIT
2206
SYSCALL_DEFINE5(io_getevents,aio_context_t,ctx_id,long,min_nr,long,nr,struct io_event __user *,events,struct __kernel_timespec __user *,timeout)2207 SYSCALL_DEFINE5(io_getevents, aio_context_t, ctx_id,
2208 long, min_nr,
2209 long, nr,
2210 struct io_event __user *, events,
2211 struct __kernel_timespec __user *, timeout)
2212 {
2213 struct timespec64 ts;
2214 int ret;
2215
2216 if (timeout && unlikely(get_timespec64(&ts, timeout)))
2217 return -EFAULT;
2218
2219 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2220 if (!ret && signal_pending(current))
2221 ret = -EINTR;
2222 return ret;
2223 }
2224
2225 #endif
2226
2227 struct __aio_sigset {
2228 const sigset_t __user *sigmask;
2229 size_t sigsetsize;
2230 };
2231
SYSCALL_DEFINE6(io_pgetevents,aio_context_t,ctx_id,long,min_nr,long,nr,struct io_event __user *,events,struct __kernel_timespec __user *,timeout,const struct __aio_sigset __user *,usig)2232 SYSCALL_DEFINE6(io_pgetevents,
2233 aio_context_t, ctx_id,
2234 long, min_nr,
2235 long, nr,
2236 struct io_event __user *, events,
2237 struct __kernel_timespec __user *, timeout,
2238 const struct __aio_sigset __user *, usig)
2239 {
2240 struct __aio_sigset ksig = { NULL, };
2241 struct timespec64 ts;
2242 bool interrupted;
2243 int ret;
2244
2245 if (timeout && unlikely(get_timespec64(&ts, timeout)))
2246 return -EFAULT;
2247
2248 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2249 return -EFAULT;
2250
2251 ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2252 if (ret)
2253 return ret;
2254
2255 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2256
2257 interrupted = signal_pending(current);
2258 restore_saved_sigmask_unless(interrupted);
2259 if (interrupted && !ret)
2260 ret = -ERESTARTNOHAND;
2261
2262 return ret;
2263 }
2264
2265 #if defined(CONFIG_COMPAT_32BIT_TIME) && !defined(CONFIG_64BIT)
2266
SYSCALL_DEFINE6(io_pgetevents_time32,aio_context_t,ctx_id,long,min_nr,long,nr,struct io_event __user *,events,struct old_timespec32 __user *,timeout,const struct __aio_sigset __user *,usig)2267 SYSCALL_DEFINE6(io_pgetevents_time32,
2268 aio_context_t, ctx_id,
2269 long, min_nr,
2270 long, nr,
2271 struct io_event __user *, events,
2272 struct old_timespec32 __user *, timeout,
2273 const struct __aio_sigset __user *, usig)
2274 {
2275 struct __aio_sigset ksig = { NULL, };
2276 struct timespec64 ts;
2277 bool interrupted;
2278 int ret;
2279
2280 if (timeout && unlikely(get_old_timespec32(&ts, timeout)))
2281 return -EFAULT;
2282
2283 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2284 return -EFAULT;
2285
2286
2287 ret = set_user_sigmask(ksig.sigmask, ksig.sigsetsize);
2288 if (ret)
2289 return ret;
2290
2291 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
2292
2293 interrupted = signal_pending(current);
2294 restore_saved_sigmask_unless(interrupted);
2295 if (interrupted && !ret)
2296 ret = -ERESTARTNOHAND;
2297
2298 return ret;
2299 }
2300
2301 #endif
2302
2303 #if defined(CONFIG_COMPAT_32BIT_TIME)
2304
SYSCALL_DEFINE5(io_getevents_time32,__u32,ctx_id,__s32,min_nr,__s32,nr,struct io_event __user *,events,struct old_timespec32 __user *,timeout)2305 SYSCALL_DEFINE5(io_getevents_time32, __u32, ctx_id,
2306 __s32, min_nr,
2307 __s32, nr,
2308 struct io_event __user *, events,
2309 struct old_timespec32 __user *, timeout)
2310 {
2311 struct timespec64 t;
2312 int ret;
2313
2314 if (timeout && get_old_timespec32(&t, timeout))
2315 return -EFAULT;
2316
2317 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2318 if (!ret && signal_pending(current))
2319 ret = -EINTR;
2320 return ret;
2321 }
2322
2323 #endif
2324
2325 #ifdef CONFIG_COMPAT
2326
2327 struct __compat_aio_sigset {
2328 compat_uptr_t sigmask;
2329 compat_size_t sigsetsize;
2330 };
2331
2332 #if defined(CONFIG_COMPAT_32BIT_TIME)
2333
COMPAT_SYSCALL_DEFINE6(io_pgetevents,compat_aio_context_t,ctx_id,compat_long_t,min_nr,compat_long_t,nr,struct io_event __user *,events,struct old_timespec32 __user *,timeout,const struct __compat_aio_sigset __user *,usig)2334 COMPAT_SYSCALL_DEFINE6(io_pgetevents,
2335 compat_aio_context_t, ctx_id,
2336 compat_long_t, min_nr,
2337 compat_long_t, nr,
2338 struct io_event __user *, events,
2339 struct old_timespec32 __user *, timeout,
2340 const struct __compat_aio_sigset __user *, usig)
2341 {
2342 struct __compat_aio_sigset ksig = { 0, };
2343 struct timespec64 t;
2344 bool interrupted;
2345 int ret;
2346
2347 if (timeout && get_old_timespec32(&t, timeout))
2348 return -EFAULT;
2349
2350 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2351 return -EFAULT;
2352
2353 ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2354 if (ret)
2355 return ret;
2356
2357 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2358
2359 interrupted = signal_pending(current);
2360 restore_saved_sigmask_unless(interrupted);
2361 if (interrupted && !ret)
2362 ret = -ERESTARTNOHAND;
2363
2364 return ret;
2365 }
2366
2367 #endif
2368
COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,compat_aio_context_t,ctx_id,compat_long_t,min_nr,compat_long_t,nr,struct io_event __user *,events,struct __kernel_timespec __user *,timeout,const struct __compat_aio_sigset __user *,usig)2369 COMPAT_SYSCALL_DEFINE6(io_pgetevents_time64,
2370 compat_aio_context_t, ctx_id,
2371 compat_long_t, min_nr,
2372 compat_long_t, nr,
2373 struct io_event __user *, events,
2374 struct __kernel_timespec __user *, timeout,
2375 const struct __compat_aio_sigset __user *, usig)
2376 {
2377 struct __compat_aio_sigset ksig = { 0, };
2378 struct timespec64 t;
2379 bool interrupted;
2380 int ret;
2381
2382 if (timeout && get_timespec64(&t, timeout))
2383 return -EFAULT;
2384
2385 if (usig && copy_from_user(&ksig, usig, sizeof(ksig)))
2386 return -EFAULT;
2387
2388 ret = set_compat_user_sigmask(compat_ptr(ksig.sigmask), ksig.sigsetsize);
2389 if (ret)
2390 return ret;
2391
2392 ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
2393
2394 interrupted = signal_pending(current);
2395 restore_saved_sigmask_unless(interrupted);
2396 if (interrupted && !ret)
2397 ret = -ERESTARTNOHAND;
2398
2399 return ret;
2400 }
2401 #endif
2402