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 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 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) 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 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 } 109 110 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); 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 } 127 128 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 } 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 } 170 171 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 { 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 } 291 292 int 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 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; 322 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 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 { 424 struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf); 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)) { 439 bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT); 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 } 550