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3b77495a JA |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/kernel.h> | |
3 | #include <linux/errno.h> | |
4 | #include <linux/fs.h> | |
5 | #include <linux/file.h> | |
6 | #include <linux/mm.h> | |
7 | #include <linux/slab.h> | |
8 | #include <linux/namei.h> | |
9 | #include <linux/poll.h> | |
10 | #include <linux/io_uring.h> | |
11 | ||
12 | #include <uapi/linux/io_uring.h> | |
13 | ||
3b77495a JA |
14 | #include "io_uring.h" |
15 | #include "opdef.h" | |
16 | #include "kbuf.h" | |
17 | ||
18 | #define IO_BUFFER_LIST_BUF_PER_PAGE (PAGE_SIZE / sizeof(struct io_uring_buf)) | |
19 | ||
20 | #define BGID_ARRAY 64 | |
21 | ||
22 | struct io_provide_buf { | |
23 | struct file *file; | |
24 | __u64 addr; | |
25 | __u32 len; | |
26 | __u32 bgid; | |
27 | __u16 nbufs; | |
28 | __u16 bid; | |
29 | }; | |
30 | ||
31 | static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx, | |
32 | unsigned int bgid) | |
33 | { | |
34 | if (ctx->io_bl && bgid < BGID_ARRAY) | |
35 | return &ctx->io_bl[bgid]; | |
36 | ||
37 | return xa_load(&ctx->io_bl_xa, bgid); | |
38 | } | |
39 | ||
024b8fde HX |
40 | static int io_buffer_add_list(struct io_ring_ctx *ctx, |
41 | struct io_buffer_list *bl, unsigned int bgid) | |
42 | { | |
43 | bl->bgid = bgid; | |
44 | if (bgid < BGID_ARRAY) | |
45 | return 0; | |
46 | ||
47 | return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL)); | |
48 | } | |
49 | ||
50 | void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags) | |
3b77495a JA |
51 | { |
52 | struct io_ring_ctx *ctx = req->ctx; | |
53 | struct io_buffer_list *bl; | |
54 | struct io_buffer *buf; | |
55 | ||
56 | /* | |
024b8fde HX |
57 | * For legacy provided buffer mode, don't recycle if we already did |
58 | * IO to this buffer. For ring-mapped provided buffer mode, we should | |
59 | * increment ring->head to explicitly monopolize the buffer to avoid | |
60 | * multiple use. | |
3b77495a | 61 | */ |
024b8fde | 62 | if (req->flags & REQ_F_PARTIAL_IO) |
3b77495a | 63 | return; |
3b77495a JA |
64 | |
65 | io_ring_submit_lock(ctx, issue_flags); | |
66 | ||
67 | buf = req->kbuf; | |
68 | bl = io_buffer_get_list(ctx, buf->bgid); | |
69 | list_add(&buf->list, &bl->buf_list); | |
70 | req->flags &= ~REQ_F_BUFFER_SELECTED; | |
71 | req->buf_index = buf->bgid; | |
72 | ||
73 | io_ring_submit_unlock(ctx, issue_flags); | |
024b8fde | 74 | return; |
3b77495a JA |
75 | } |
76 | ||
53ccf69b PB |
77 | unsigned int __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags) |
78 | { | |
79 | unsigned int cflags; | |
80 | ||
81 | /* | |
82 | * We can add this buffer back to two lists: | |
83 | * | |
84 | * 1) The io_buffers_cache list. This one is protected by the | |
85 | * ctx->uring_lock. If we already hold this lock, add back to this | |
86 | * list as we can grab it from issue as well. | |
87 | * 2) The io_buffers_comp list. This one is protected by the | |
88 | * ctx->completion_lock. | |
89 | * | |
90 | * We migrate buffers from the comp_list to the issue cache list | |
91 | * when we need one. | |
92 | */ | |
93 | if (req->flags & REQ_F_BUFFER_RING) { | |
94 | /* no buffers to recycle for this case */ | |
95 | cflags = __io_put_kbuf_list(req, NULL); | |
96 | } else if (issue_flags & IO_URING_F_UNLOCKED) { | |
97 | struct io_ring_ctx *ctx = req->ctx; | |
98 | ||
99 | spin_lock(&ctx->completion_lock); | |
100 | cflags = __io_put_kbuf_list(req, &ctx->io_buffers_comp); | |
101 | spin_unlock(&ctx->completion_lock); | |
102 | } else { | |
103 | lockdep_assert_held(&req->ctx->uring_lock); | |
104 | ||
105 | cflags = __io_put_kbuf_list(req, &req->ctx->io_buffers_cache); | |
106 | } | |
107 | return cflags; | |
108 | } | |
109 | ||
3b77495a JA |
110 | static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len, |
111 | struct io_buffer_list *bl) | |
112 | { | |
113 | if (!list_empty(&bl->buf_list)) { | |
114 | struct io_buffer *kbuf; | |
115 | ||
116 | kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list); | |
117 | list_del(&kbuf->list); | |
b8c01559 | 118 | if (*len == 0 || *len > kbuf->len) |
3b77495a JA |
119 | *len = kbuf->len; |
120 | req->flags |= REQ_F_BUFFER_SELECTED; | |
121 | req->kbuf = kbuf; | |
122 | req->buf_index = kbuf->bid; | |
123 | return u64_to_user_ptr(kbuf->addr); | |
124 | } | |
125 | return NULL; | |
126 | } | |
127 | ||
128 | static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len, | |
129 | struct io_buffer_list *bl, | |
130 | unsigned int issue_flags) | |
131 | { | |
132 | struct io_uring_buf_ring *br = bl->buf_ring; | |
133 | struct io_uring_buf *buf; | |
134 | __u16 head = bl->head; | |
135 | ||
136 | if (unlikely(smp_load_acquire(&br->tail) == head)) | |
137 | return NULL; | |
138 | ||
139 | head &= bl->mask; | |
140 | if (head < IO_BUFFER_LIST_BUF_PER_PAGE) { | |
141 | buf = &br->bufs[head]; | |
142 | } else { | |
143 | int off = head & (IO_BUFFER_LIST_BUF_PER_PAGE - 1); | |
144 | int index = head / IO_BUFFER_LIST_BUF_PER_PAGE; | |
145 | buf = page_address(bl->buf_pages[index]); | |
146 | buf += off; | |
147 | } | |
b8c01559 | 148 | if (*len == 0 || *len > buf->len) |
3b77495a JA |
149 | *len = buf->len; |
150 | req->flags |= REQ_F_BUFFER_RING; | |
151 | req->buf_list = bl; | |
152 | req->buf_index = buf->bid; | |
153 | ||
154 | if (issue_flags & IO_URING_F_UNLOCKED || !file_can_poll(req->file)) { | |
155 | /* | |
156 | * If we came in unlocked, we have no choice but to consume the | |
f09c8643 HX |
157 | * buffer here, otherwise nothing ensures that the buffer won't |
158 | * get used by others. This does mean it'll be pinned until the | |
159 | * IO completes, coming in unlocked means we're being called from | |
160 | * io-wq context and there may be further retries in async hybrid | |
161 | * mode. For the locked case, the caller must call commit when | |
162 | * the transfer completes (or if we get -EAGAIN and must poll of | |
163 | * retry). | |
3b77495a JA |
164 | */ |
165 | req->buf_list = NULL; | |
166 | bl->head++; | |
167 | } | |
168 | return u64_to_user_ptr(buf->addr); | |
169 | } | |
170 | ||
171 | void __user *io_buffer_select(struct io_kiocb *req, size_t *len, | |
172 | unsigned int issue_flags) | |
173 | { | |
174 | struct io_ring_ctx *ctx = req->ctx; | |
175 | struct io_buffer_list *bl; | |
176 | void __user *ret = NULL; | |
177 | ||
178 | io_ring_submit_lock(req->ctx, issue_flags); | |
179 | ||
180 | bl = io_buffer_get_list(ctx, req->buf_index); | |
181 | if (likely(bl)) { | |
182 | if (bl->buf_nr_pages) | |
183 | ret = io_ring_buffer_select(req, len, bl, issue_flags); | |
184 | else | |
185 | ret = io_provided_buffer_select(req, len, bl); | |
186 | } | |
187 | io_ring_submit_unlock(req->ctx, issue_flags); | |
188 | return ret; | |
189 | } | |
190 | ||
191 | static __cold int io_init_bl_list(struct io_ring_ctx *ctx) | |
192 | { | |
193 | int i; | |
194 | ||
195 | ctx->io_bl = kcalloc(BGID_ARRAY, sizeof(struct io_buffer_list), | |
196 | GFP_KERNEL); | |
197 | if (!ctx->io_bl) | |
198 | return -ENOMEM; | |
199 | ||
200 | for (i = 0; i < BGID_ARRAY; i++) { | |
201 | INIT_LIST_HEAD(&ctx->io_bl[i].buf_list); | |
202 | ctx->io_bl[i].bgid = i; | |
203 | } | |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
208 | static int __io_remove_buffers(struct io_ring_ctx *ctx, | |
209 | struct io_buffer_list *bl, unsigned nbufs) | |
210 | { | |
211 | unsigned i = 0; | |
212 | ||
213 | /* shouldn't happen */ | |
214 | if (!nbufs) | |
215 | return 0; | |
216 | ||
217 | if (bl->buf_nr_pages) { | |
218 | int j; | |
219 | ||
220 | i = bl->buf_ring->tail - bl->head; | |
221 | for (j = 0; j < bl->buf_nr_pages; j++) | |
222 | unpin_user_page(bl->buf_pages[j]); | |
223 | kvfree(bl->buf_pages); | |
224 | bl->buf_pages = NULL; | |
225 | bl->buf_nr_pages = 0; | |
226 | /* make sure it's seen as empty */ | |
227 | INIT_LIST_HEAD(&bl->buf_list); | |
228 | return i; | |
229 | } | |
230 | ||
231 | /* the head kbuf is the list itself */ | |
232 | while (!list_empty(&bl->buf_list)) { | |
233 | struct io_buffer *nxt; | |
234 | ||
235 | nxt = list_first_entry(&bl->buf_list, struct io_buffer, list); | |
236 | list_del(&nxt->list); | |
237 | if (++i == nbufs) | |
238 | return i; | |
239 | cond_resched(); | |
240 | } | |
241 | i++; | |
242 | ||
243 | return i; | |
244 | } | |
245 | ||
246 | void io_destroy_buffers(struct io_ring_ctx *ctx) | |
247 | { | |
248 | struct io_buffer_list *bl; | |
249 | unsigned long index; | |
250 | int i; | |
251 | ||
252 | for (i = 0; i < BGID_ARRAY; i++) { | |
253 | if (!ctx->io_bl) | |
254 | break; | |
255 | __io_remove_buffers(ctx, &ctx->io_bl[i], -1U); | |
256 | } | |
257 | ||
258 | xa_for_each(&ctx->io_bl_xa, index, bl) { | |
259 | xa_erase(&ctx->io_bl_xa, bl->bgid); | |
260 | __io_remove_buffers(ctx, bl, -1U); | |
261 | kfree(bl); | |
262 | } | |
263 | ||
264 | while (!list_empty(&ctx->io_buffers_pages)) { | |
265 | struct page *page; | |
266 | ||
267 | page = list_first_entry(&ctx->io_buffers_pages, struct page, lru); | |
268 | list_del_init(&page->lru); | |
269 | __free_page(page); | |
270 | } | |
271 | } | |
272 | ||
273 | int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) | |
274 | { | |
f2ccb5ae | 275 | struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); |
3b77495a JA |
276 | u64 tmp; |
277 | ||
278 | if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off || | |
279 | sqe->splice_fd_in) | |
280 | return -EINVAL; | |
281 | ||
282 | tmp = READ_ONCE(sqe->fd); | |
283 | if (!tmp || tmp > USHRT_MAX) | |
284 | return -EINVAL; | |
285 | ||
286 | memset(p, 0, sizeof(*p)); | |
287 | p->nbufs = tmp; | |
288 | p->bgid = READ_ONCE(sqe->buf_group); | |
289 | return 0; | |
290 | } | |
291 | ||
292 | int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags) | |
293 | { | |
f2ccb5ae | 294 | struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); |
3b77495a JA |
295 | struct io_ring_ctx *ctx = req->ctx; |
296 | struct io_buffer_list *bl; | |
297 | int ret = 0; | |
298 | ||
299 | io_ring_submit_lock(ctx, issue_flags); | |
300 | ||
301 | ret = -ENOENT; | |
302 | bl = io_buffer_get_list(ctx, p->bgid); | |
303 | if (bl) { | |
304 | ret = -EINVAL; | |
305 | /* can't use provide/remove buffers command on mapped buffers */ | |
306 | if (!bl->buf_nr_pages) | |
307 | ret = __io_remove_buffers(ctx, bl, p->nbufs); | |
308 | } | |
309 | if (ret < 0) | |
310 | req_set_fail(req); | |
311 | ||
312 | /* complete before unlock, IOPOLL may need the lock */ | |
313 | io_req_set_res(req, ret, 0); | |
314 | __io_req_complete(req, issue_flags); | |
315 | io_ring_submit_unlock(ctx, issue_flags); | |
316 | return IOU_ISSUE_SKIP_COMPLETE; | |
317 | } | |
318 | ||
319 | int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) | |
320 | { | |
321 | unsigned long size, tmp_check; | |
f2ccb5ae | 322 | struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); |
3b77495a JA |
323 | u64 tmp; |
324 | ||
325 | if (sqe->rw_flags || sqe->splice_fd_in) | |
326 | return -EINVAL; | |
327 | ||
328 | tmp = READ_ONCE(sqe->fd); | |
329 | if (!tmp || tmp > USHRT_MAX) | |
330 | return -E2BIG; | |
331 | p->nbufs = tmp; | |
332 | p->addr = READ_ONCE(sqe->addr); | |
333 | p->len = READ_ONCE(sqe->len); | |
334 | ||
335 | if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs, | |
336 | &size)) | |
337 | return -EOVERFLOW; | |
338 | if (check_add_overflow((unsigned long)p->addr, size, &tmp_check)) | |
339 | return -EOVERFLOW; | |
340 | ||
341 | size = (unsigned long)p->len * p->nbufs; | |
342 | if (!access_ok(u64_to_user_ptr(p->addr), size)) | |
343 | return -EFAULT; | |
344 | ||
345 | p->bgid = READ_ONCE(sqe->buf_group); | |
346 | tmp = READ_ONCE(sqe->off); | |
347 | if (tmp > USHRT_MAX) | |
348 | return -E2BIG; | |
349 | p->bid = tmp; | |
350 | return 0; | |
351 | } | |
352 | ||
353 | static int io_refill_buffer_cache(struct io_ring_ctx *ctx) | |
354 | { | |
355 | struct io_buffer *buf; | |
356 | struct page *page; | |
357 | int bufs_in_page; | |
358 | ||
359 | /* | |
360 | * Completions that don't happen inline (eg not under uring_lock) will | |
361 | * add to ->io_buffers_comp. If we don't have any free buffers, check | |
362 | * the completion list and splice those entries first. | |
363 | */ | |
364 | if (!list_empty_careful(&ctx->io_buffers_comp)) { | |
365 | spin_lock(&ctx->completion_lock); | |
366 | if (!list_empty(&ctx->io_buffers_comp)) { | |
367 | list_splice_init(&ctx->io_buffers_comp, | |
368 | &ctx->io_buffers_cache); | |
369 | spin_unlock(&ctx->completion_lock); | |
370 | return 0; | |
371 | } | |
372 | spin_unlock(&ctx->completion_lock); | |
373 | } | |
374 | ||
375 | /* | |
376 | * No free buffers and no completion entries either. Allocate a new | |
377 | * page worth of buffer entries and add those to our freelist. | |
378 | */ | |
379 | page = alloc_page(GFP_KERNEL_ACCOUNT); | |
380 | if (!page) | |
381 | return -ENOMEM; | |
382 | ||
383 | list_add(&page->lru, &ctx->io_buffers_pages); | |
384 | ||
385 | buf = page_address(page); | |
386 | bufs_in_page = PAGE_SIZE / sizeof(*buf); | |
387 | while (bufs_in_page) { | |
388 | list_add_tail(&buf->list, &ctx->io_buffers_cache); | |
389 | buf++; | |
390 | bufs_in_page--; | |
391 | } | |
392 | ||
393 | return 0; | |
394 | } | |
395 | ||
396 | static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf, | |
397 | struct io_buffer_list *bl) | |
398 | { | |
399 | struct io_buffer *buf; | |
400 | u64 addr = pbuf->addr; | |
401 | int i, bid = pbuf->bid; | |
402 | ||
403 | for (i = 0; i < pbuf->nbufs; i++) { | |
404 | if (list_empty(&ctx->io_buffers_cache) && | |
405 | io_refill_buffer_cache(ctx)) | |
406 | break; | |
407 | buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer, | |
408 | list); | |
409 | list_move_tail(&buf->list, &bl->buf_list); | |
410 | buf->addr = addr; | |
411 | buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT); | |
412 | buf->bid = bid; | |
413 | buf->bgid = pbuf->bgid; | |
414 | addr += pbuf->len; | |
415 | bid++; | |
416 | cond_resched(); | |
417 | } | |
418 | ||
419 | return i ? 0 : -ENOMEM; | |
420 | } | |
421 | ||
422 | int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags) | |
423 | { | |
f2ccb5ae | 424 | struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); |
3b77495a JA |
425 | struct io_ring_ctx *ctx = req->ctx; |
426 | struct io_buffer_list *bl; | |
427 | int ret = 0; | |
428 | ||
429 | io_ring_submit_lock(ctx, issue_flags); | |
430 | ||
431 | if (unlikely(p->bgid < BGID_ARRAY && !ctx->io_bl)) { | |
432 | ret = io_init_bl_list(ctx); | |
433 | if (ret) | |
434 | goto err; | |
435 | } | |
436 | ||
437 | bl = io_buffer_get_list(ctx, p->bgid); | |
438 | if (unlikely(!bl)) { | |
cc18cc5e | 439 | bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT); |
3b77495a JA |
440 | if (!bl) { |
441 | ret = -ENOMEM; | |
442 | goto err; | |
443 | } | |
444 | INIT_LIST_HEAD(&bl->buf_list); | |
445 | ret = io_buffer_add_list(ctx, bl, p->bgid); | |
446 | if (ret) { | |
447 | kfree(bl); | |
448 | goto err; | |
449 | } | |
450 | } | |
451 | /* can't add buffers via this command for a mapped buffer ring */ | |
452 | if (bl->buf_nr_pages) { | |
453 | ret = -EINVAL; | |
454 | goto err; | |
455 | } | |
456 | ||
457 | ret = io_add_buffers(ctx, p, bl); | |
458 | err: | |
459 | if (ret < 0) | |
460 | req_set_fail(req); | |
461 | /* complete before unlock, IOPOLL may need the lock */ | |
462 | io_req_set_res(req, ret, 0); | |
463 | __io_req_complete(req, issue_flags); | |
464 | io_ring_submit_unlock(ctx, issue_flags); | |
465 | return IOU_ISSUE_SKIP_COMPLETE; | |
466 | } | |
467 | ||
468 | int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) | |
469 | { | |
470 | struct io_uring_buf_ring *br; | |
471 | struct io_uring_buf_reg reg; | |
472 | struct io_buffer_list *bl, *free_bl = NULL; | |
473 | struct page **pages; | |
474 | int nr_pages; | |
475 | ||
476 | if (copy_from_user(®, arg, sizeof(reg))) | |
477 | return -EFAULT; | |
478 | ||
479 | if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2]) | |
480 | return -EINVAL; | |
481 | if (!reg.ring_addr) | |
482 | return -EFAULT; | |
483 | if (reg.ring_addr & ~PAGE_MASK) | |
484 | return -EINVAL; | |
485 | if (!is_power_of_2(reg.ring_entries)) | |
486 | return -EINVAL; | |
487 | ||
488 | /* cannot disambiguate full vs empty due to head/tail size */ | |
489 | if (reg.ring_entries >= 65536) | |
490 | return -EINVAL; | |
491 | ||
492 | if (unlikely(reg.bgid < BGID_ARRAY && !ctx->io_bl)) { | |
493 | int ret = io_init_bl_list(ctx); | |
494 | if (ret) | |
495 | return ret; | |
496 | } | |
497 | ||
498 | bl = io_buffer_get_list(ctx, reg.bgid); | |
499 | if (bl) { | |
500 | /* if mapped buffer ring OR classic exists, don't allow */ | |
501 | if (bl->buf_nr_pages || !list_empty(&bl->buf_list)) | |
502 | return -EEXIST; | |
503 | } else { | |
504 | free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL); | |
505 | if (!bl) | |
506 | return -ENOMEM; | |
507 | } | |
508 | ||
509 | pages = io_pin_pages(reg.ring_addr, | |
510 | struct_size(br, bufs, reg.ring_entries), | |
511 | &nr_pages); | |
512 | if (IS_ERR(pages)) { | |
513 | kfree(free_bl); | |
514 | return PTR_ERR(pages); | |
515 | } | |
516 | ||
517 | br = page_address(pages[0]); | |
518 | bl->buf_pages = pages; | |
519 | bl->buf_nr_pages = nr_pages; | |
520 | bl->nr_entries = reg.ring_entries; | |
521 | bl->buf_ring = br; | |
522 | bl->mask = reg.ring_entries - 1; | |
523 | io_buffer_add_list(ctx, bl, reg.bgid); | |
524 | return 0; | |
525 | } | |
526 | ||
527 | int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) | |
528 | { | |
529 | struct io_uring_buf_reg reg; | |
530 | struct io_buffer_list *bl; | |
531 | ||
532 | if (copy_from_user(®, arg, sizeof(reg))) | |
533 | return -EFAULT; | |
534 | if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2]) | |
535 | return -EINVAL; | |
536 | ||
537 | bl = io_buffer_get_list(ctx, reg.bgid); | |
538 | if (!bl) | |
539 | return -ENOENT; | |
540 | if (!bl->buf_nr_pages) | |
541 | return -EINVAL; | |
542 | ||
543 | __io_remove_buffers(ctx, bl, -1U); | |
544 | if (bl->bgid >= BGID_ARRAY) { | |
545 | xa_erase(&ctx->io_bl_xa, bl->bgid); | |
546 | kfree(bl); | |
547 | } | |
548 | return 0; | |
549 | } |