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 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 } 315 316 int 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 } 351 352 static 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 } 394 395 static 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 } 420 421 int 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); 457 err: 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 } 465 466 int 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 flex_array_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 } 524 525 int 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 } 548