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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
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
22struct io_provide_buf {
23 struct file *file;
24 __u64 addr;
25 __u32 len;
26 __u32 bgid;
27 __u16 nbufs;
28 __u16 bid;
29};
30
31static 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
40static 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
50void io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags)
51{
52 struct io_ring_ctx *ctx = req->ctx;
53 struct io_buffer_list *bl;
54 struct io_buffer *buf;
55
56 /*
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.
61 */
62 if (req->flags & REQ_F_PARTIAL_IO)
63 return;
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);
74 return;
75}
76
77unsigned 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
110static 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);
118 if (*len == 0 || *len > kbuf->len)
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
128static 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 }
148 if (*len == 0 || *len > buf->len)
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
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).
164 */
165 req->buf_list = NULL;
166 bl->head++;
167 }
168 return u64_to_user_ptr(buf->addr);
169}
170
171void __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
191static __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
208static 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
246void 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
273int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
274{
275 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
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
292int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
293{
294 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
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 io_ring_submit_unlock(ctx, issue_flags);
310 if (ret < 0)
311 req_set_fail(req);
312 io_req_set_res(req, ret, 0);
313 return IOU_OK;
314}
315
316int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
317{
318 unsigned long size, tmp_check;
319 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
320 u64 tmp;
321
322 if (sqe->rw_flags || sqe->splice_fd_in)
323 return -EINVAL;
324
325 tmp = READ_ONCE(sqe->fd);
326 if (!tmp || tmp > USHRT_MAX)
327 return -E2BIG;
328 p->nbufs = tmp;
329 p->addr = READ_ONCE(sqe->addr);
330 p->len = READ_ONCE(sqe->len);
331
332 if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs,
333 &size))
334 return -EOVERFLOW;
335 if (check_add_overflow((unsigned long)p->addr, size, &tmp_check))
336 return -EOVERFLOW;
337
338 size = (unsigned long)p->len * p->nbufs;
339 if (!access_ok(u64_to_user_ptr(p->addr), size))
340 return -EFAULT;
341
342 p->bgid = READ_ONCE(sqe->buf_group);
343 tmp = READ_ONCE(sqe->off);
344 if (tmp > USHRT_MAX)
345 return -E2BIG;
346 if (tmp + p->nbufs >= USHRT_MAX)
347 return -EINVAL;
348 p->bid = tmp;
349 return 0;
350}
351
352static int io_refill_buffer_cache(struct io_ring_ctx *ctx)
353{
354 struct io_buffer *buf;
355 struct page *page;
356 int bufs_in_page;
357
358 /*
359 * Completions that don't happen inline (eg not under uring_lock) will
360 * add to ->io_buffers_comp. If we don't have any free buffers, check
361 * the completion list and splice those entries first.
362 */
363 if (!list_empty_careful(&ctx->io_buffers_comp)) {
364 spin_lock(&ctx->completion_lock);
365 if (!list_empty(&ctx->io_buffers_comp)) {
366 list_splice_init(&ctx->io_buffers_comp,
367 &ctx->io_buffers_cache);
368 spin_unlock(&ctx->completion_lock);
369 return 0;
370 }
371 spin_unlock(&ctx->completion_lock);
372 }
373
374 /*
375 * No free buffers and no completion entries either. Allocate a new
376 * page worth of buffer entries and add those to our freelist.
377 */
378 page = alloc_page(GFP_KERNEL_ACCOUNT);
379 if (!page)
380 return -ENOMEM;
381
382 list_add(&page->lru, &ctx->io_buffers_pages);
383
384 buf = page_address(page);
385 bufs_in_page = PAGE_SIZE / sizeof(*buf);
386 while (bufs_in_page) {
387 list_add_tail(&buf->list, &ctx->io_buffers_cache);
388 buf++;
389 bufs_in_page--;
390 }
391
392 return 0;
393}
394
395static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf,
396 struct io_buffer_list *bl)
397{
398 struct io_buffer *buf;
399 u64 addr = pbuf->addr;
400 int i, bid = pbuf->bid;
401
402 for (i = 0; i < pbuf->nbufs; i++) {
403 if (list_empty(&ctx->io_buffers_cache) &&
404 io_refill_buffer_cache(ctx))
405 break;
406 buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer,
407 list);
408 list_move_tail(&buf->list, &bl->buf_list);
409 buf->addr = addr;
410 buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);
411 buf->bid = bid;
412 buf->bgid = pbuf->bgid;
413 addr += pbuf->len;
414 bid++;
415 cond_resched();
416 }
417
418 return i ? 0 : -ENOMEM;
419}
420
421int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
422{
423 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);
424 struct io_ring_ctx *ctx = req->ctx;
425 struct io_buffer_list *bl;
426 int ret = 0;
427
428 io_ring_submit_lock(ctx, issue_flags);
429
430 if (unlikely(p->bgid < BGID_ARRAY && !ctx->io_bl)) {
431 ret = io_init_bl_list(ctx);
432 if (ret)
433 goto err;
434 }
435
436 bl = io_buffer_get_list(ctx, p->bgid);
437 if (unlikely(!bl)) {
438 bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT);
439 if (!bl) {
440 ret = -ENOMEM;
441 goto err;
442 }
443 INIT_LIST_HEAD(&bl->buf_list);
444 ret = io_buffer_add_list(ctx, bl, p->bgid);
445 if (ret) {
446 kfree(bl);
447 goto err;
448 }
449 }
450 /* can't add buffers via this command for a mapped buffer ring */
451 if (bl->buf_nr_pages) {
452 ret = -EINVAL;
453 goto err;
454 }
455
456 ret = io_add_buffers(ctx, p, bl);
457err:
458 io_ring_submit_unlock(ctx, issue_flags);
459
460 if (ret < 0)
461 req_set_fail(req);
462 io_req_set_res(req, ret, 0);
463 return IOU_OK;
464}
465
466int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
467{
468 struct io_uring_buf_ring *br;
469 struct io_uring_buf_reg reg;
470 struct io_buffer_list *bl, *free_bl = NULL;
471 struct page **pages;
472 int nr_pages;
473
474 if (copy_from_user(®, arg, sizeof(reg)))
475 return -EFAULT;
476
477 if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
478 return -EINVAL;
479 if (!reg.ring_addr)
480 return -EFAULT;
481 if (reg.ring_addr & ~PAGE_MASK)
482 return -EINVAL;
483 if (!is_power_of_2(reg.ring_entries))
484 return -EINVAL;
485
486 /* cannot disambiguate full vs empty due to head/tail size */
487 if (reg.ring_entries >= 65536)
488 return -EINVAL;
489
490 if (unlikely(reg.bgid < BGID_ARRAY && !ctx->io_bl)) {
491 int ret = io_init_bl_list(ctx);
492 if (ret)
493 return ret;
494 }
495
496 bl = io_buffer_get_list(ctx, reg.bgid);
497 if (bl) {
498 /* if mapped buffer ring OR classic exists, don't allow */
499 if (bl->buf_nr_pages || !list_empty(&bl->buf_list))
500 return -EEXIST;
501 } else {
502 free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
503 if (!bl)
504 return -ENOMEM;
505 }
506
507 pages = io_pin_pages(reg.ring_addr,
508 struct_size(br, bufs, reg.ring_entries),
509 &nr_pages);
510 if (IS_ERR(pages)) {
511 kfree(free_bl);
512 return PTR_ERR(pages);
513 }
514
515 br = page_address(pages[0]);
516 bl->buf_pages = pages;
517 bl->buf_nr_pages = nr_pages;
518 bl->nr_entries = reg.ring_entries;
519 bl->buf_ring = br;
520 bl->mask = reg.ring_entries - 1;
521 io_buffer_add_list(ctx, bl, reg.bgid);
522 return 0;
523}
524
525int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
526{
527 struct io_uring_buf_reg reg;
528 struct io_buffer_list *bl;
529
530 if (copy_from_user(®, arg, sizeof(reg)))
531 return -EFAULT;
532 if (reg.pad || reg.resv[0] || reg.resv[1] || reg.resv[2])
533 return -EINVAL;
534
535 bl = io_buffer_get_list(ctx, reg.bgid);
536 if (!bl)
537 return -ENOENT;
538 if (!bl->buf_nr_pages)
539 return -EINVAL;
540
541 __io_remove_buffers(ctx, bl, -1U);
542 if (bl->bgid >= BGID_ARRAY) {
543 xa_erase(&ctx->io_bl_xa, bl->bgid);
544 kfree(bl);
545 }
546 return 0;
547}