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/vmalloc.h> 11#include <linux/io_uring.h> 12 13#include <uapi/linux/io_uring.h> 14 15#include "io_uring.h" 16#include "opdef.h" 17#include "kbuf.h" 18#include "memmap.h" 19 20/* BIDs are addressed by a 16-bit field in a CQE */ 21#define MAX_BIDS_PER_BGID (1 << 16) 22 23struct kmem_cache *io_buf_cachep; 24 25struct io_provide_buf { 26 struct file *file; 27 __u64 addr; 28 __u32 len; 29 __u32 bgid; 30 __u32 nbufs; 31 __u16 bid; 32}; 33 34static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx, 35 unsigned int bgid) 36{ 37 lockdep_assert_held(&ctx->uring_lock); 38 39 return xa_load(&ctx->io_bl_xa, bgid); 40} 41 42static int io_buffer_add_list(struct io_ring_ctx *ctx, 43 struct io_buffer_list *bl, unsigned int bgid) 44{ 45 /* 46 * Store buffer group ID and finally mark the list as visible. 47 * The normal lookup doesn't care about the visibility as we're 48 * always under the ->uring_lock, but the RCU lookup from mmap does. 49 */ 50 bl->bgid = bgid; 51 atomic_set(&bl->refs, 1); 52 return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL)); 53} 54 55bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags) 56{ 57 struct io_ring_ctx *ctx = req->ctx; 58 struct io_buffer_list *bl; 59 struct io_buffer *buf; 60 61 io_ring_submit_lock(ctx, issue_flags); 62 63 buf = req->kbuf; 64 bl = io_buffer_get_list(ctx, buf->bgid); 65 list_add(&buf->list, &bl->buf_list); 66 req->flags &= ~REQ_F_BUFFER_SELECTED; 67 req->buf_index = buf->bgid; 68 69 io_ring_submit_unlock(ctx, issue_flags); 70 return true; 71} 72 73void __io_put_kbuf(struct io_kiocb *req, unsigned issue_flags) 74{ 75 /* 76 * We can add this buffer back to two lists: 77 * 78 * 1) The io_buffers_cache list. This one is protected by the 79 * ctx->uring_lock. If we already hold this lock, add back to this 80 * list as we can grab it from issue as well. 81 * 2) The io_buffers_comp list. This one is protected by the 82 * ctx->completion_lock. 83 * 84 * We migrate buffers from the comp_list to the issue cache list 85 * when we need one. 86 */ 87 if (issue_flags & IO_URING_F_UNLOCKED) { 88 struct io_ring_ctx *ctx = req->ctx; 89 90 spin_lock(&ctx->completion_lock); 91 __io_put_kbuf_list(req, &ctx->io_buffers_comp); 92 spin_unlock(&ctx->completion_lock); 93 } else { 94 lockdep_assert_held(&req->ctx->uring_lock); 95 96 __io_put_kbuf_list(req, &req->ctx->io_buffers_cache); 97 } 98} 99 100static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len, 101 struct io_buffer_list *bl) 102{ 103 if (!list_empty(&bl->buf_list)) { 104 struct io_buffer *kbuf; 105 106 kbuf = list_first_entry(&bl->buf_list, struct io_buffer, list); 107 list_del(&kbuf->list); 108 if (*len == 0 || *len > kbuf->len) 109 *len = kbuf->len; 110 if (list_empty(&bl->buf_list)) 111 req->flags |= REQ_F_BL_EMPTY; 112 req->flags |= REQ_F_BUFFER_SELECTED; 113 req->kbuf = kbuf; 114 req->buf_index = kbuf->bid; 115 return u64_to_user_ptr(kbuf->addr); 116 } 117 return NULL; 118} 119 120static int io_provided_buffers_select(struct io_kiocb *req, size_t *len, 121 struct io_buffer_list *bl, 122 struct iovec *iov) 123{ 124 void __user *buf; 125 126 buf = io_provided_buffer_select(req, len, bl); 127 if (unlikely(!buf)) 128 return -ENOBUFS; 129 130 iov[0].iov_base = buf; 131 iov[0].iov_len = *len; 132 return 0; 133} 134 135static struct io_uring_buf *io_ring_head_to_buf(struct io_uring_buf_ring *br, 136 __u16 head, __u16 mask) 137{ 138 return &br->bufs[head & mask]; 139} 140 141static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len, 142 struct io_buffer_list *bl, 143 unsigned int issue_flags) 144{ 145 struct io_uring_buf_ring *br = bl->buf_ring; 146 __u16 tail, head = bl->head; 147 struct io_uring_buf *buf; 148 149 tail = smp_load_acquire(&br->tail); 150 if (unlikely(tail == head)) 151 return NULL; 152 153 if (head + 1 == tail) 154 req->flags |= REQ_F_BL_EMPTY; 155 156 buf = io_ring_head_to_buf(br, head, bl->mask); 157 if (*len == 0 || *len > buf->len) 158 *len = buf->len; 159 req->flags |= REQ_F_BUFFER_RING | REQ_F_BUFFERS_COMMIT; 160 req->buf_list = bl; 161 req->buf_index = buf->bid; 162 163 if (issue_flags & IO_URING_F_UNLOCKED || !io_file_can_poll(req)) { 164 /* 165 * If we came in unlocked, we have no choice but to consume the 166 * buffer here, otherwise nothing ensures that the buffer won't 167 * get used by others. This does mean it'll be pinned until the 168 * IO completes, coming in unlocked means we're being called from 169 * io-wq context and there may be further retries in async hybrid 170 * mode. For the locked case, the caller must call commit when 171 * the transfer completes (or if we get -EAGAIN and must poll of 172 * retry). 173 */ 174 req->flags &= ~REQ_F_BUFFERS_COMMIT; 175 req->buf_list = NULL; 176 bl->head++; 177 } 178 return u64_to_user_ptr(buf->addr); 179} 180 181void __user *io_buffer_select(struct io_kiocb *req, size_t *len, 182 unsigned int issue_flags) 183{ 184 struct io_ring_ctx *ctx = req->ctx; 185 struct io_buffer_list *bl; 186 void __user *ret = NULL; 187 188 io_ring_submit_lock(req->ctx, issue_flags); 189 190 bl = io_buffer_get_list(ctx, req->buf_index); 191 if (likely(bl)) { 192 if (bl->is_buf_ring) 193 ret = io_ring_buffer_select(req, len, bl, issue_flags); 194 else 195 ret = io_provided_buffer_select(req, len, bl); 196 } 197 io_ring_submit_unlock(req->ctx, issue_flags); 198 return ret; 199} 200 201/* cap it at a reasonable 256, will be one page even for 4K */ 202#define PEEK_MAX_IMPORT 256 203 204static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg, 205 struct io_buffer_list *bl) 206{ 207 struct io_uring_buf_ring *br = bl->buf_ring; 208 struct iovec *iov = arg->iovs; 209 int nr_iovs = arg->nr_iovs; 210 __u16 nr_avail, tail, head; 211 struct io_uring_buf *buf; 212 213 tail = smp_load_acquire(&br->tail); 214 head = bl->head; 215 nr_avail = min_t(__u16, tail - head, UIO_MAXIOV); 216 if (unlikely(!nr_avail)) 217 return -ENOBUFS; 218 219 buf = io_ring_head_to_buf(br, head, bl->mask); 220 if (arg->max_len) { 221 int needed; 222 223 needed = (arg->max_len + buf->len - 1) / buf->len; 224 needed = min(needed, PEEK_MAX_IMPORT); 225 if (nr_avail > needed) 226 nr_avail = needed; 227 } 228 229 /* 230 * only alloc a bigger array if we know we have data to map, eg not 231 * a speculative peek operation. 232 */ 233 if (arg->mode & KBUF_MODE_EXPAND && nr_avail > nr_iovs && arg->max_len) { 234 iov = kmalloc_array(nr_avail, sizeof(struct iovec), GFP_KERNEL); 235 if (unlikely(!iov)) 236 return -ENOMEM; 237 if (arg->mode & KBUF_MODE_FREE) 238 kfree(arg->iovs); 239 arg->iovs = iov; 240 nr_iovs = nr_avail; 241 } else if (nr_avail < nr_iovs) { 242 nr_iovs = nr_avail; 243 } 244 245 /* set it to max, if not set, so we can use it unconditionally */ 246 if (!arg->max_len) 247 arg->max_len = INT_MAX; 248 249 req->buf_index = buf->bid; 250 do { 251 /* truncate end piece, if needed */ 252 if (buf->len > arg->max_len) 253 buf->len = arg->max_len; 254 255 iov->iov_base = u64_to_user_ptr(buf->addr); 256 iov->iov_len = buf->len; 257 iov++; 258 259 arg->out_len += buf->len; 260 arg->max_len -= buf->len; 261 if (!arg->max_len) 262 break; 263 264 buf = io_ring_head_to_buf(br, ++head, bl->mask); 265 } while (--nr_iovs); 266 267 if (head == tail) 268 req->flags |= REQ_F_BL_EMPTY; 269 270 req->flags |= REQ_F_BUFFER_RING; 271 req->buf_list = bl; 272 return iov - arg->iovs; 273} 274 275int io_buffers_select(struct io_kiocb *req, struct buf_sel_arg *arg, 276 unsigned int issue_flags) 277{ 278 struct io_ring_ctx *ctx = req->ctx; 279 struct io_buffer_list *bl; 280 int ret = -ENOENT; 281 282 io_ring_submit_lock(ctx, issue_flags); 283 bl = io_buffer_get_list(ctx, req->buf_index); 284 if (unlikely(!bl)) 285 goto out_unlock; 286 287 if (bl->is_buf_ring) { 288 ret = io_ring_buffers_peek(req, arg, bl); 289 /* 290 * Don't recycle these buffers if we need to go through poll. 291 * Nobody else can use them anyway, and holding on to provided 292 * buffers for a send/write operation would happen on the app 293 * side anyway with normal buffers. Besides, we already 294 * committed them, they cannot be put back in the queue. 295 */ 296 if (ret > 0) { 297 req->flags |= REQ_F_BL_NO_RECYCLE; 298 req->buf_list->head += ret; 299 } 300 } else { 301 ret = io_provided_buffers_select(req, &arg->out_len, bl, arg->iovs); 302 } 303out_unlock: 304 io_ring_submit_unlock(ctx, issue_flags); 305 return ret; 306} 307 308int io_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg) 309{ 310 struct io_ring_ctx *ctx = req->ctx; 311 struct io_buffer_list *bl; 312 int ret; 313 314 lockdep_assert_held(&ctx->uring_lock); 315 316 bl = io_buffer_get_list(ctx, req->buf_index); 317 if (unlikely(!bl)) 318 return -ENOENT; 319 320 if (bl->is_buf_ring) { 321 ret = io_ring_buffers_peek(req, arg, bl); 322 if (ret > 0) 323 req->flags |= REQ_F_BUFFERS_COMMIT; 324 return ret; 325 } 326 327 /* don't support multiple buffer selections for legacy */ 328 return io_provided_buffers_select(req, &arg->max_len, bl, arg->iovs); 329} 330 331static int __io_remove_buffers(struct io_ring_ctx *ctx, 332 struct io_buffer_list *bl, unsigned nbufs) 333{ 334 unsigned i = 0; 335 336 /* shouldn't happen */ 337 if (!nbufs) 338 return 0; 339 340 if (bl->is_buf_ring) { 341 i = bl->buf_ring->tail - bl->head; 342 if (bl->buf_nr_pages) { 343 int j; 344 345 if (!bl->is_mmap) { 346 for (j = 0; j < bl->buf_nr_pages; j++) 347 unpin_user_page(bl->buf_pages[j]); 348 } 349 io_pages_unmap(bl->buf_ring, &bl->buf_pages, 350 &bl->buf_nr_pages, bl->is_mmap); 351 bl->is_mmap = 0; 352 } 353 /* make sure it's seen as empty */ 354 INIT_LIST_HEAD(&bl->buf_list); 355 bl->is_buf_ring = 0; 356 return i; 357 } 358 359 /* protects io_buffers_cache */ 360 lockdep_assert_held(&ctx->uring_lock); 361 362 while (!list_empty(&bl->buf_list)) { 363 struct io_buffer *nxt; 364 365 nxt = list_first_entry(&bl->buf_list, struct io_buffer, list); 366 list_move(&nxt->list, &ctx->io_buffers_cache); 367 if (++i == nbufs) 368 return i; 369 cond_resched(); 370 } 371 372 return i; 373} 374 375void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl) 376{ 377 if (atomic_dec_and_test(&bl->refs)) { 378 __io_remove_buffers(ctx, bl, -1U); 379 kfree_rcu(bl, rcu); 380 } 381} 382 383void io_destroy_buffers(struct io_ring_ctx *ctx) 384{ 385 struct io_buffer_list *bl; 386 struct list_head *item, *tmp; 387 struct io_buffer *buf; 388 unsigned long index; 389 390 xa_for_each(&ctx->io_bl_xa, index, bl) { 391 xa_erase(&ctx->io_bl_xa, bl->bgid); 392 io_put_bl(ctx, bl); 393 } 394 395 /* 396 * Move deferred locked entries to cache before pruning 397 */ 398 spin_lock(&ctx->completion_lock); 399 if (!list_empty(&ctx->io_buffers_comp)) 400 list_splice_init(&ctx->io_buffers_comp, &ctx->io_buffers_cache); 401 spin_unlock(&ctx->completion_lock); 402 403 list_for_each_safe(item, tmp, &ctx->io_buffers_cache) { 404 buf = list_entry(item, struct io_buffer, list); 405 kmem_cache_free(io_buf_cachep, buf); 406 } 407} 408 409int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 410{ 411 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 412 u64 tmp; 413 414 if (sqe->rw_flags || sqe->addr || sqe->len || sqe->off || 415 sqe->splice_fd_in) 416 return -EINVAL; 417 418 tmp = READ_ONCE(sqe->fd); 419 if (!tmp || tmp > MAX_BIDS_PER_BGID) 420 return -EINVAL; 421 422 memset(p, 0, sizeof(*p)); 423 p->nbufs = tmp; 424 p->bgid = READ_ONCE(sqe->buf_group); 425 return 0; 426} 427 428int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags) 429{ 430 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 431 struct io_ring_ctx *ctx = req->ctx; 432 struct io_buffer_list *bl; 433 int ret = 0; 434 435 io_ring_submit_lock(ctx, issue_flags); 436 437 ret = -ENOENT; 438 bl = io_buffer_get_list(ctx, p->bgid); 439 if (bl) { 440 ret = -EINVAL; 441 /* can't use provide/remove buffers command on mapped buffers */ 442 if (!bl->is_buf_ring) 443 ret = __io_remove_buffers(ctx, bl, p->nbufs); 444 } 445 io_ring_submit_unlock(ctx, issue_flags); 446 if (ret < 0) 447 req_set_fail(req); 448 io_req_set_res(req, ret, 0); 449 return IOU_OK; 450} 451 452int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) 453{ 454 unsigned long size, tmp_check; 455 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 456 u64 tmp; 457 458 if (sqe->rw_flags || sqe->splice_fd_in) 459 return -EINVAL; 460 461 tmp = READ_ONCE(sqe->fd); 462 if (!tmp || tmp > MAX_BIDS_PER_BGID) 463 return -E2BIG; 464 p->nbufs = tmp; 465 p->addr = READ_ONCE(sqe->addr); 466 p->len = READ_ONCE(sqe->len); 467 468 if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs, 469 &size)) 470 return -EOVERFLOW; 471 if (check_add_overflow((unsigned long)p->addr, size, &tmp_check)) 472 return -EOVERFLOW; 473 474 size = (unsigned long)p->len * p->nbufs; 475 if (!access_ok(u64_to_user_ptr(p->addr), size)) 476 return -EFAULT; 477 478 p->bgid = READ_ONCE(sqe->buf_group); 479 tmp = READ_ONCE(sqe->off); 480 if (tmp > USHRT_MAX) 481 return -E2BIG; 482 if (tmp + p->nbufs > MAX_BIDS_PER_BGID) 483 return -EINVAL; 484 p->bid = tmp; 485 return 0; 486} 487 488#define IO_BUFFER_ALLOC_BATCH 64 489 490static int io_refill_buffer_cache(struct io_ring_ctx *ctx) 491{ 492 struct io_buffer *bufs[IO_BUFFER_ALLOC_BATCH]; 493 int allocated; 494 495 /* 496 * Completions that don't happen inline (eg not under uring_lock) will 497 * add to ->io_buffers_comp. If we don't have any free buffers, check 498 * the completion list and splice those entries first. 499 */ 500 if (!list_empty_careful(&ctx->io_buffers_comp)) { 501 spin_lock(&ctx->completion_lock); 502 if (!list_empty(&ctx->io_buffers_comp)) { 503 list_splice_init(&ctx->io_buffers_comp, 504 &ctx->io_buffers_cache); 505 spin_unlock(&ctx->completion_lock); 506 return 0; 507 } 508 spin_unlock(&ctx->completion_lock); 509 } 510 511 /* 512 * No free buffers and no completion entries either. Allocate a new 513 * batch of buffer entries and add those to our freelist. 514 */ 515 516 allocated = kmem_cache_alloc_bulk(io_buf_cachep, GFP_KERNEL_ACCOUNT, 517 ARRAY_SIZE(bufs), (void **) bufs); 518 if (unlikely(!allocated)) { 519 /* 520 * Bulk alloc is all-or-nothing. If we fail to get a batch, 521 * retry single alloc to be on the safe side. 522 */ 523 bufs[0] = kmem_cache_alloc(io_buf_cachep, GFP_KERNEL); 524 if (!bufs[0]) 525 return -ENOMEM; 526 allocated = 1; 527 } 528 529 while (allocated) 530 list_add_tail(&bufs[--allocated]->list, &ctx->io_buffers_cache); 531 532 return 0; 533} 534 535static int io_add_buffers(struct io_ring_ctx *ctx, struct io_provide_buf *pbuf, 536 struct io_buffer_list *bl) 537{ 538 struct io_buffer *buf; 539 u64 addr = pbuf->addr; 540 int i, bid = pbuf->bid; 541 542 for (i = 0; i < pbuf->nbufs; i++) { 543 if (list_empty(&ctx->io_buffers_cache) && 544 io_refill_buffer_cache(ctx)) 545 break; 546 buf = list_first_entry(&ctx->io_buffers_cache, struct io_buffer, 547 list); 548 list_move_tail(&buf->list, &bl->buf_list); 549 buf->addr = addr; 550 buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT); 551 buf->bid = bid; 552 buf->bgid = pbuf->bgid; 553 addr += pbuf->len; 554 bid++; 555 cond_resched(); 556 } 557 558 return i ? 0 : -ENOMEM; 559} 560 561int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags) 562{ 563 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 564 struct io_ring_ctx *ctx = req->ctx; 565 struct io_buffer_list *bl; 566 int ret = 0; 567 568 io_ring_submit_lock(ctx, issue_flags); 569 570 bl = io_buffer_get_list(ctx, p->bgid); 571 if (unlikely(!bl)) { 572 bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT); 573 if (!bl) { 574 ret = -ENOMEM; 575 goto err; 576 } 577 INIT_LIST_HEAD(&bl->buf_list); 578 ret = io_buffer_add_list(ctx, bl, p->bgid); 579 if (ret) { 580 /* 581 * Doesn't need rcu free as it was never visible, but 582 * let's keep it consistent throughout. 583 */ 584 kfree_rcu(bl, rcu); 585 goto err; 586 } 587 } 588 /* can't add buffers via this command for a mapped buffer ring */ 589 if (bl->is_buf_ring) { 590 ret = -EINVAL; 591 goto err; 592 } 593 594 ret = io_add_buffers(ctx, p, bl); 595err: 596 io_ring_submit_unlock(ctx, issue_flags); 597 598 if (ret < 0) 599 req_set_fail(req); 600 io_req_set_res(req, ret, 0); 601 return IOU_OK; 602} 603 604static int io_pin_pbuf_ring(struct io_uring_buf_reg *reg, 605 struct io_buffer_list *bl) 606{ 607 struct io_uring_buf_ring *br = NULL; 608 struct page **pages; 609 int nr_pages, ret; 610 611 pages = io_pin_pages(reg->ring_addr, 612 flex_array_size(br, bufs, reg->ring_entries), 613 &nr_pages); 614 if (IS_ERR(pages)) 615 return PTR_ERR(pages); 616 617 br = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); 618 if (!br) { 619 ret = -ENOMEM; 620 goto error_unpin; 621 } 622 623#ifdef SHM_COLOUR 624 /* 625 * On platforms that have specific aliasing requirements, SHM_COLOUR 626 * is set and we must guarantee that the kernel and user side align 627 * nicely. We cannot do that if IOU_PBUF_RING_MMAP isn't set and 628 * the application mmap's the provided ring buffer. Fail the request 629 * if we, by chance, don't end up with aligned addresses. The app 630 * should use IOU_PBUF_RING_MMAP instead, and liburing will handle 631 * this transparently. 632 */ 633 if ((reg->ring_addr | (unsigned long) br) & (SHM_COLOUR - 1)) { 634 ret = -EINVAL; 635 goto error_unpin; 636 } 637#endif 638 bl->buf_pages = pages; 639 bl->buf_nr_pages = nr_pages; 640 bl->buf_ring = br; 641 bl->is_buf_ring = 1; 642 bl->is_mmap = 0; 643 return 0; 644error_unpin: 645 unpin_user_pages(pages, nr_pages); 646 kvfree(pages); 647 vunmap(br); 648 return ret; 649} 650 651static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx, 652 struct io_uring_buf_reg *reg, 653 struct io_buffer_list *bl) 654{ 655 size_t ring_size; 656 657 ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring); 658 659 bl->buf_ring = io_pages_map(&bl->buf_pages, &bl->buf_nr_pages, ring_size); 660 if (!bl->buf_ring) 661 return -ENOMEM; 662 663 bl->is_buf_ring = 1; 664 bl->is_mmap = 1; 665 return 0; 666} 667 668int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) 669{ 670 struct io_uring_buf_reg reg; 671 struct io_buffer_list *bl, *free_bl = NULL; 672 int ret; 673 674 lockdep_assert_held(&ctx->uring_lock); 675 676 if (copy_from_user(®, arg, sizeof(reg))) 677 return -EFAULT; 678 679 if (reg.resv[0] || reg.resv[1] || reg.resv[2]) 680 return -EINVAL; 681 if (reg.flags & ~IOU_PBUF_RING_MMAP) 682 return -EINVAL; 683 if (!(reg.flags & IOU_PBUF_RING_MMAP)) { 684 if (!reg.ring_addr) 685 return -EFAULT; 686 if (reg.ring_addr & ~PAGE_MASK) 687 return -EINVAL; 688 } else { 689 if (reg.ring_addr) 690 return -EINVAL; 691 } 692 693 if (!is_power_of_2(reg.ring_entries)) 694 return -EINVAL; 695 696 /* cannot disambiguate full vs empty due to head/tail size */ 697 if (reg.ring_entries >= 65536) 698 return -EINVAL; 699 700 bl = io_buffer_get_list(ctx, reg.bgid); 701 if (bl) { 702 /* if mapped buffer ring OR classic exists, don't allow */ 703 if (bl->is_buf_ring || !list_empty(&bl->buf_list)) 704 return -EEXIST; 705 } else { 706 free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL); 707 if (!bl) 708 return -ENOMEM; 709 } 710 711 if (!(reg.flags & IOU_PBUF_RING_MMAP)) 712 ret = io_pin_pbuf_ring(®, bl); 713 else 714 ret = io_alloc_pbuf_ring(ctx, ®, bl); 715 716 if (!ret) { 717 bl->nr_entries = reg.ring_entries; 718 bl->mask = reg.ring_entries - 1; 719 720 io_buffer_add_list(ctx, bl, reg.bgid); 721 return 0; 722 } 723 724 kfree_rcu(free_bl, rcu); 725 return ret; 726} 727 728int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) 729{ 730 struct io_uring_buf_reg reg; 731 struct io_buffer_list *bl; 732 733 lockdep_assert_held(&ctx->uring_lock); 734 735 if (copy_from_user(®, arg, sizeof(reg))) 736 return -EFAULT; 737 if (reg.resv[0] || reg.resv[1] || reg.resv[2]) 738 return -EINVAL; 739 if (reg.flags) 740 return -EINVAL; 741 742 bl = io_buffer_get_list(ctx, reg.bgid); 743 if (!bl) 744 return -ENOENT; 745 if (!bl->is_buf_ring) 746 return -EINVAL; 747 748 xa_erase(&ctx->io_bl_xa, bl->bgid); 749 io_put_bl(ctx, bl); 750 return 0; 751} 752 753int io_register_pbuf_status(struct io_ring_ctx *ctx, void __user *arg) 754{ 755 struct io_uring_buf_status buf_status; 756 struct io_buffer_list *bl; 757 int i; 758 759 if (copy_from_user(&buf_status, arg, sizeof(buf_status))) 760 return -EFAULT; 761 762 for (i = 0; i < ARRAY_SIZE(buf_status.resv); i++) 763 if (buf_status.resv[i]) 764 return -EINVAL; 765 766 bl = io_buffer_get_list(ctx, buf_status.buf_group); 767 if (!bl) 768 return -ENOENT; 769 if (!bl->is_buf_ring) 770 return -EINVAL; 771 772 buf_status.head = bl->head; 773 if (copy_to_user(arg, &buf_status, sizeof(buf_status))) 774 return -EFAULT; 775 776 return 0; 777} 778 779struct io_buffer_list *io_pbuf_get_bl(struct io_ring_ctx *ctx, 780 unsigned long bgid) 781{ 782 struct io_buffer_list *bl; 783 bool ret; 784 785 /* 786 * We have to be a bit careful here - we're inside mmap and cannot grab 787 * the uring_lock. This means the buffer_list could be simultaneously 788 * going away, if someone is trying to be sneaky. Look it up under rcu 789 * so we know it's not going away, and attempt to grab a reference to 790 * it. If the ref is already zero, then fail the mapping. If successful, 791 * the caller will call io_put_bl() to drop the the reference at at the 792 * end. This may then safely free the buffer_list (and drop the pages) 793 * at that point, vm_insert_pages() would've already grabbed the 794 * necessary vma references. 795 */ 796 rcu_read_lock(); 797 bl = xa_load(&ctx->io_bl_xa, bgid); 798 /* must be a mmap'able buffer ring and have pages */ 799 ret = false; 800 if (bl && bl->is_mmap) 801 ret = atomic_inc_not_zero(&bl->refs); 802 rcu_read_unlock(); 803 804 if (ret) 805 return bl; 806 807 return ERR_PTR(-EINVAL); 808} 809 810int io_pbuf_mmap(struct file *file, struct vm_area_struct *vma) 811{ 812 struct io_ring_ctx *ctx = file->private_data; 813 loff_t pgoff = vma->vm_pgoff << PAGE_SHIFT; 814 struct io_buffer_list *bl; 815 int bgid, ret; 816 817 bgid = (pgoff & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT; 818 bl = io_pbuf_get_bl(ctx, bgid); 819 if (IS_ERR(bl)) 820 return PTR_ERR(bl); 821 822 ret = io_uring_mmap_pages(ctx, vma, bl->buf_pages, bl->buf_nr_pages); 823 io_put_bl(ctx, bl); 824 return ret; 825} 826