io_uring/rsrc.c

   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/nospec.h>
   9 #include <linux/hugetlb.h>
  10 #include <linux/compat.h>
  11 #include <linux/io_uring.h>
  12
  13 #include <uapi/linux/io_uring.h>
  14
  15 #include "io_uring.h"
  16 #include "openclose.h"
  17 #include "rsrc.h"
  18 #include "memmap.h"
  19 #include "register.h"
  20
  21 struct io_rsrc_update {
  22         struct file                     *file;
  23         u64                             arg;
  24         u32                             nr_args;
  25         u32                             offset;
  26 };
  27
  28 static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
  29                         struct iovec *iov, struct page **last_hpage);
  30
  31 /* only define max */
  32 #define IORING_MAX_FIXED_FILES  (1U << 20)
  33 #define IORING_MAX_REG_BUFFERS  (1U << 14)
  34
  35 int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
  36 {
  37         unsigned long page_limit, cur_pages, new_pages;
  38
  39         if (!nr_pages)
  40                 return 0;
  41
  42         /* Don't allow more pages than we can safely lock */
  43         page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  44
  45         cur_pages = atomic_long_read(&user->locked_vm);
  46         do {
  47                 new_pages = cur_pages + nr_pages;
  48                 if (new_pages > page_limit)
  49                         return -ENOMEM;
  50         } while (!atomic_long_try_cmpxchg(&user->locked_vm,
  51                                           &cur_pages, new_pages));
  52         return 0;
  53 }
  54
  55 static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
  56 {
  57         if (ctx->user)
  58                 __io_unaccount_mem(ctx->user, nr_pages);
  59
  60         if (ctx->mm_account)
  61                 atomic64_sub(nr_pages, &ctx->mm_account->pinned_vm);
  62 }
  63
  64 static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
  65 {
  66         int ret;
  67
  68         if (ctx->user) {
  69                 ret = __io_account_mem(ctx->user, nr_pages);
  70                 if (ret)
  71                         return ret;
  72         }
  73
  74         if (ctx->mm_account)
  75                 atomic64_add(nr_pages, &ctx->mm_account->pinned_vm);
  76
  77         return 0;
  78 }
  79
  80 static int io_buffer_validate(struct iovec *iov)
  81 {
  82         unsigned long tmp, acct_len = iov->iov_len + (PAGE_SIZE - 1);
  83
  84         /*
  85          * Don't impose further limits on the size and buffer
  86          * constraints here, we'll -EINVAL later when IO is
  87          * submitted if they are wrong.
  88          */
  89         if (!iov->iov_base)
  90                 return iov->iov_len ? -EFAULT : 0;
  91         if (!iov->iov_len)
  92                 return -EFAULT;
  93
  94         /* arbitrary limit, but we need something */
  95         if (iov->iov_len > SZ_1G)
  96                 return -EFAULT;
  97
  98         if (check_add_overflow((unsigned long)iov->iov_base, acct_len, &tmp))
  99                 return -EOVERFLOW;
 100
 101         return 0;
 102 }
 103
 104 static void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 105 {
 106         unsigned int i;
 107
 108         if (node->buf) {
 109                 struct io_mapped_ubuf *imu = node->buf;
 110
 111                 if (!refcount_dec_and_test(&imu->refs))
 112                         return;
 113                 for (i = 0; i < imu->nr_bvecs; i++)
 114                         unpin_user_page(imu->bvec[i].bv_page);
 115                 if (imu->acct_pages)
 116                         io_unaccount_mem(ctx, imu->acct_pages);
 117                 kvfree(imu);
 118         }
 119 }
 120
 121 struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx, int type)
 122 {
 123         struct io_rsrc_node *node;
 124
 125         node = kzalloc(sizeof(*node), GFP_KERNEL);
 126         if (node) {
 127                 node->type = type;
 128                 node->refs = 1;
 129         }
 130         return node;
 131 }
 132
 133 __cold void io_rsrc_data_free(struct io_ring_ctx *ctx, struct io_rsrc_data *data)
 134 {
 135         if (!data->nr)
 136                 return;
 137         while (data->nr--) {
 138                 if (data->nodes[data->nr])
 139                         io_put_rsrc_node(ctx, data->nodes[data->nr]);
 140         }
 141         kvfree(data->nodes);
 142         data->nodes = NULL;
 143         data->nr = 0;
 144 }
 145
 146 __cold int io_rsrc_data_alloc(struct io_rsrc_data *data, unsigned nr)
 147 {
 148         data->nodes = kvmalloc_array(nr, sizeof(struct io_rsrc_node *),
 149                                         GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 150         if (data->nodes) {
 151                 data->nr = nr;
 152                 return 0;
 153         }
 154         return -ENOMEM;
 155 }
 156
 157 static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 158                                  struct io_uring_rsrc_update2 *up,
 159                                  unsigned nr_args)
 160 {
 161         u64 __user *tags = u64_to_user_ptr(up->tags);
 162         __s32 __user *fds = u64_to_user_ptr(up->data);
 163         int fd, i, err = 0;
 164         unsigned int done;
 165
 166         if (!ctx->file_table.data.nr)
 167                 return -ENXIO;
 168         if (up->offset + nr_args > ctx->file_table.data.nr)
 169                 return -EINVAL;
 170
 171         for (done = 0; done < nr_args; done++) {
 172                 u64 tag = 0;
 173
 174                 if ((tags && copy_from_user(&tag, &tags[done], sizeof(tag))) ||
 175                     copy_from_user(&fd, &fds[done], sizeof(fd))) {
 176                         err = -EFAULT;
 177                         break;
 178                 }
 179                 if ((fd == IORING_REGISTER_FILES_SKIP || fd == -1) && tag) {
 180                         err = -EINVAL;
 181                         break;
 182                 }
 183                 if (fd == IORING_REGISTER_FILES_SKIP)
 184                         continue;
 185
 186                 i = up->offset + done;
 187                 if (io_reset_rsrc_node(ctx, &ctx->file_table.data, i))
 188                         io_file_bitmap_clear(&ctx->file_table, i);
 189
 190                 if (fd != -1) {
 191                         struct file *file = fget(fd);
 192                         struct io_rsrc_node *node;
 193
 194                         if (!file) {
 195                                 err = -EBADF;
 196                                 break;
 197                         }
 198                         /*
 199                          * Don't allow io_uring instances to be registered.
 200                          */
 201                         if (io_is_uring_fops(file)) {
 202                                 fput(file);
 203                                 err = -EBADF;
 204                                 break;
 205                         }
 206                         node = io_rsrc_node_alloc(ctx, IORING_RSRC_FILE);
 207                         if (!node) {
 208                                 err = -ENOMEM;
 209                                 fput(file);
 210                                 break;
 211                         }
 212                         ctx->file_table.data.nodes[i] = node;
 213                         if (tag)
 214                                 node->tag = tag;
 215                         io_fixed_file_set(node, file);
 216                         io_file_bitmap_set(&ctx->file_table, i);
 217                 }
 218         }
 219         return done ? done : err;
 220 }
 221
 222 static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 223                                    struct io_uring_rsrc_update2 *up,
 224                                    unsigned int nr_args)
 225 {
 226         u64 __user *tags = u64_to_user_ptr(up->tags);
 227         struct iovec fast_iov, *iov;
 228         struct page *last_hpage = NULL;
 229         struct iovec __user *uvec;
 230         u64 user_data = up->data;
 231         __u32 done;
 232         int i, err;
 233
 234         if (!ctx->buf_table.nr)
 235                 return -ENXIO;
 236         if (up->offset + nr_args > ctx->buf_table.nr)
 237                 return -EINVAL;
 238
 239         for (done = 0; done < nr_args; done++) {
 240                 struct io_rsrc_node *node;
 241                 u64 tag = 0;
 242
 243                 uvec = u64_to_user_ptr(user_data);
 244                 iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
 245                 if (IS_ERR(iov)) {
 246                         err = PTR_ERR(iov);
 247                         break;
 248                 }
 249                 if (tags && copy_from_user(&tag, &tags[done], sizeof(tag))) {
 250                         err = -EFAULT;
 251                         break;
 252                 }
 253                 err = io_buffer_validate(iov);
 254                 if (err)
 255                         break;
 256                 node = io_sqe_buffer_register(ctx, iov, &last_hpage);
 257                 if (IS_ERR(node)) {
 258                         err = PTR_ERR(node);
 259                         break;
 260                 }
 261                 if (tag) {
 262                         if (!node) {
 263                                 err = -EINVAL;
 264                                 break;
 265                         }
 266                         node->tag = tag;
 267                 }
 268                 i = array_index_nospec(up->offset + done, ctx->buf_table.nr);
 269                 io_reset_rsrc_node(ctx, &ctx->buf_table, i);
 270                 ctx->buf_table.nodes[i] = node;
 271                 if (ctx->compat)
 272                         user_data += sizeof(struct compat_iovec);
 273                 else
 274                         user_data += sizeof(struct iovec);
 275         }
 276         return done ? done : err;
 277 }
 278
 279 static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
 280                                      struct io_uring_rsrc_update2 *up,
 281                                      unsigned nr_args)
 282 {
 283         __u32 tmp;
 284
 285         lockdep_assert_held(&ctx->uring_lock);
 286
 287         if (check_add_overflow(up->offset, nr_args, &tmp))
 288                 return -EOVERFLOW;
 289
 290         switch (type) {
 291         case IORING_RSRC_FILE:
 292                 return __io_sqe_files_update(ctx, up, nr_args);
 293         case IORING_RSRC_BUFFER:
 294                 return __io_sqe_buffers_update(ctx, up, nr_args);
 295         }
 296         return -EINVAL;
 297 }
 298
 299 int io_register_files_update(struct io_ring_ctx *ctx, void __user *arg,
 300                              unsigned nr_args)
 301 {
 302         struct io_uring_rsrc_update2 up;
 303
 304         if (!nr_args)
 305                 return -EINVAL;
 306         memset(&up, 0, sizeof(up));
 307         if (copy_from_user(&up, arg, sizeof(struct io_uring_rsrc_update)))
 308                 return -EFAULT;
 309         if (up.resv || up.resv2)
 310                 return -EINVAL;
 311         return __io_register_rsrc_update(ctx, IORING_RSRC_FILE, &up, nr_args);
 312 }
 313
 314 int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
 315                             unsigned size, unsigned type)
 316 {
 317         struct io_uring_rsrc_update2 up;
 318
 319         if (size != sizeof(up))
 320                 return -EINVAL;
 321         if (copy_from_user(&up, arg, sizeof(up)))
 322                 return -EFAULT;
 323         if (!up.nr || up.resv || up.resv2)
 324                 return -EINVAL;
 325         return __io_register_rsrc_update(ctx, type, &up, up.nr);
 326 }
 327
 328 __cold int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
 329                             unsigned int size, unsigned int type)
 330 {
 331         struct io_uring_rsrc_register rr;
 332
 333         /* keep it extendible */
 334         if (size != sizeof(rr))
 335                 return -EINVAL;
 336
 337         memset(&rr, 0, sizeof(rr));
 338         if (copy_from_user(&rr, arg, size))
 339                 return -EFAULT;
 340         if (!rr.nr || rr.resv2)
 341                 return -EINVAL;
 342         if (rr.flags & ~IORING_RSRC_REGISTER_SPARSE)
 343                 return -EINVAL;
 344
 345         switch (type) {
 346         case IORING_RSRC_FILE:
 347                 if (rr.flags & IORING_RSRC_REGISTER_SPARSE && rr.data)
 348                         break;
 349                 return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),
 350                                              rr.nr, u64_to_user_ptr(rr.tags));
 351         case IORING_RSRC_BUFFER:
 352                 if (rr.flags & IORING_RSRC_REGISTER_SPARSE && rr.data)
 353                         break;
 354                 return io_sqe_buffers_register(ctx, u64_to_user_ptr(rr.data),
 355                                                rr.nr, u64_to_user_ptr(rr.tags));
 356         }
 357         return -EINVAL;
 358 }
 359
 360 int io_files_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 361 {
 362         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 363
 364         if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
 365                 return -EINVAL;
 366         if (sqe->rw_flags || sqe->splice_fd_in)
 367                 return -EINVAL;
 368
 369         up->offset = READ_ONCE(sqe->off);
 370         up->nr_args = READ_ONCE(sqe->len);
 371         if (!up->nr_args)
 372                 return -EINVAL;
 373         up->arg = READ_ONCE(sqe->addr);
 374         return 0;
 375 }
 376
 377 static int io_files_update_with_index_alloc(struct io_kiocb *req,
 378                                             unsigned int issue_flags)
 379 {
 380         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 381         __s32 __user *fds = u64_to_user_ptr(up->arg);
 382         unsigned int done;
 383         struct file *file;
 384         int ret, fd;
 385
 386         if (!req->ctx->file_table.data.nr)
 387                 return -ENXIO;
 388
 389         for (done = 0; done < up->nr_args; done++) {
 390                 if (copy_from_user(&fd, &fds[done], sizeof(fd))) {
 391                         ret = -EFAULT;
 392                         break;
 393                 }
 394
 395                 file = fget(fd);
 396                 if (!file) {
 397                         ret = -EBADF;
 398                         break;
 399                 }
 400                 ret = io_fixed_fd_install(req, issue_flags, file,
 401                                           IORING_FILE_INDEX_ALLOC);
 402                 if (ret < 0)
 403                         break;
 404                 if (copy_to_user(&fds[done], &ret, sizeof(ret))) {
 405                         __io_close_fixed(req->ctx, issue_flags, ret);
 406                         ret = -EFAULT;
 407                         break;
 408                 }
 409         }
 410
 411         if (done)
 412                 return done;
 413         return ret;
 414 }
 415
 416 int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 417 {
 418         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 419         struct io_ring_ctx *ctx = req->ctx;
 420         struct io_uring_rsrc_update2 up2;
 421         int ret;
 422
 423         up2.offset = up->offset;
 424         up2.data = up->arg;
 425         up2.nr = 0;
 426         up2.tags = 0;
 427         up2.resv = 0;
 428         up2.resv2 = 0;
 429
 430         if (up->offset == IORING_FILE_INDEX_ALLOC) {
 431                 ret = io_files_update_with_index_alloc(req, issue_flags);
 432         } else {
 433                 io_ring_submit_lock(ctx, issue_flags);
 434                 ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
 435                                                 &up2, up->nr_args);
 436                 io_ring_submit_unlock(ctx, issue_flags);
 437         }
 438
 439         if (ret < 0)
 440                 req_set_fail(req);
 441         io_req_set_res(req, ret, 0);
 442         return IOU_OK;
 443 }
 444
 445 void io_free_rsrc_node(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
 446 {
 447         lockdep_assert_held(&ctx->uring_lock);
 448
 449         if (node->tag)
 450                 io_post_aux_cqe(ctx, node->tag, 0, 0);
 451
 452         switch (node->type) {
 453         case IORING_RSRC_FILE:
 454                 if (io_slot_file(node))
 455                         fput(io_slot_file(node));
 456                 break;
 457         case IORING_RSRC_BUFFER:
 458                 if (node->buf)
 459                         io_buffer_unmap(ctx, node);
 460                 break;
 461         default:
 462                 WARN_ON_ONCE(1);
 463                 break;
 464         }
 465
 466         kfree(node);
 467 }
 468
 469 int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 470 {
 471         if (!ctx->file_table.data.nr)
 472                 return -ENXIO;
 473
 474         io_free_file_tables(ctx, &ctx->file_table);
 475         io_file_table_set_alloc_range(ctx, 0, 0);
 476         return 0;
 477 }
 478
 479 int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 480                           unsigned nr_args, u64 __user *tags)
 481 {
 482         __s32 __user *fds = (__s32 __user *) arg;
 483         struct file *file;
 484         int fd, ret;
 485         unsigned i;
 486
 487         if (ctx->file_table.data.nr)
 488                 return -EBUSY;
 489         if (!nr_args)
 490                 return -EINVAL;
 491         if (nr_args > IORING_MAX_FIXED_FILES)
 492                 return -EMFILE;
 493         if (nr_args > rlimit(RLIMIT_NOFILE))
 494                 return -EMFILE;
 495         if (!io_alloc_file_tables(ctx, &ctx->file_table, nr_args))
 496                 return -ENOMEM;
 497
 498         for (i = 0; i < nr_args; i++) {
 499                 struct io_rsrc_node *node;
 500                 u64 tag = 0;
 501
 502                 ret = -EFAULT;
 503                 if (tags && copy_from_user(&tag, &tags[i], sizeof(tag)))
 504                         goto fail;
 505                 if (fds && copy_from_user(&fd, &fds[i], sizeof(fd)))
 506                         goto fail;
 507                 /* allow sparse sets */
 508                 if (!fds || fd == -1) {
 509                         ret = -EINVAL;
 510                         if (tag)
 511                                 goto fail;
 512                         continue;
 513                 }
 514
 515                 file = fget(fd);
 516                 ret = -EBADF;
 517                 if (unlikely(!file))
 518                         goto fail;
 519
 520                 /*
 521                  * Don't allow io_uring instances to be registered.
 522                  */
 523                 if (io_is_uring_fops(file)) {
 524                         fput(file);
 525                         goto fail;
 526                 }
 527                 ret = -ENOMEM;
 528                 node = io_rsrc_node_alloc(ctx, IORING_RSRC_FILE);
 529                 if (!node) {
 530                         fput(file);
 531                         goto fail;
 532                 }
 533                 if (tag)
 534                         node->tag = tag;
 535                 ctx->file_table.data.nodes[i] = node;
 536                 io_fixed_file_set(node, file);
 537                 io_file_bitmap_set(&ctx->file_table, i);
 538         }
 539
 540         /* default it to the whole table */
 541         io_file_table_set_alloc_range(ctx, 0, ctx->file_table.data.nr);
 542         return 0;
 543 fail:
 544         io_sqe_files_unregister(ctx);
 545         return ret;
 546 }
 547
 548 int io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
 549 {
 550         if (!ctx->buf_table.nr)
 551                 return -ENXIO;
 552         io_rsrc_data_free(ctx, &ctx->buf_table);
 553         return 0;
 554 }
 555
 556 /*
 557  * Not super efficient, but this is just a registration time. And we do cache
 558  * the last compound head, so generally we'll only do a full search if we don't
 559  * match that one.
 560  *
 561  * We check if the given compound head page has already been accounted, to
 562  * avoid double accounting it. This allows us to account the full size of the
 563  * page, not just the constituent pages of a huge page.
 564  */
 565 static bool headpage_already_acct(struct io_ring_ctx *ctx, struct page **pages,
 566                                   int nr_pages, struct page *hpage)
 567 {
 568         int i, j;
 569
 570         /* check current page array */
 571         for (i = 0; i < nr_pages; i++) {
 572                 if (!PageCompound(pages[i]))
 573                         continue;
 574                 if (compound_head(pages[i]) == hpage)
 575                         return true;
 576         }
 577
 578         /* check previously registered pages */
 579         for (i = 0; i < ctx->buf_table.nr; i++) {
 580                 struct io_rsrc_node *node = ctx->buf_table.nodes[i];
 581                 struct io_mapped_ubuf *imu;
 582
 583                 if (!node)
 584                         continue;
 585                 imu = node->buf;
 586                 for (j = 0; j < imu->nr_bvecs; j++) {
 587                         if (!PageCompound(imu->bvec[j].bv_page))
 588                                 continue;
 589                         if (compound_head(imu->bvec[j].bv_page) == hpage)
 590                                 return true;
 591                 }
 592         }
 593
 594         return false;
 595 }
 596
 597 static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages,
 598                                  int nr_pages, struct io_mapped_ubuf *imu,
 599                                  struct page **last_hpage)
 600 {
 601         int i, ret;
 602
 603         imu->acct_pages = 0;
 604         for (i = 0; i < nr_pages; i++) {
 605                 if (!PageCompound(pages[i])) {
 606                         imu->acct_pages++;
 607                 } else {
 608                         struct page *hpage;
 609
 610                         hpage = compound_head(pages[i]);
 611                         if (hpage == *last_hpage)
 612                                 continue;
 613                         *last_hpage = hpage;
 614                         if (headpage_already_acct(ctx, pages, i, hpage))
 615                                 continue;
 616                         imu->acct_pages += page_size(hpage) >> PAGE_SHIFT;
 617                 }
 618         }
 619
 620         if (!imu->acct_pages)
 621                 return 0;
 622
 623         ret = io_account_mem(ctx, imu->acct_pages);
 624         if (ret)
 625                 imu->acct_pages = 0;
 626         return ret;
 627 }
 628
 629 static bool io_do_coalesce_buffer(struct page ***pages, int *nr_pages,
 630                                 struct io_imu_folio_data *data, int nr_folios)
 631 {
 632         struct page **page_array = *pages, **new_array = NULL;
 633         int nr_pages_left = *nr_pages, i, j;
 634
 635         /* Store head pages only*/
 636         new_array = kvmalloc_array(nr_folios, sizeof(struct page *),
 637                                         GFP_KERNEL);
 638         if (!new_array)
 639                 return false;
 640
 641         new_array[0] = compound_head(page_array[0]);
 642         /*
 643          * The pages are bound to the folio, it doesn't
 644          * actually unpin them but drops all but one reference,
 645          * which is usually put down by io_buffer_unmap().
 646          * Note, needs a better helper.
 647          */
 648         if (data->nr_pages_head > 1)
 649                 unpin_user_pages(&page_array[1], data->nr_pages_head - 1);
 650
 651         j = data->nr_pages_head;
 652         nr_pages_left -= data->nr_pages_head;
 653         for (i = 1; i < nr_folios; i++) {
 654                 unsigned int nr_unpin;
 655
 656                 new_array[i] = page_array[j];
 657                 nr_unpin = min_t(unsigned int, nr_pages_left - 1,
 658                                         data->nr_pages_mid - 1);
 659                 if (nr_unpin)
 660                         unpin_user_pages(&page_array[j+1], nr_unpin);
 661                 j += data->nr_pages_mid;
 662                 nr_pages_left -= data->nr_pages_mid;
 663         }
 664         kvfree(page_array);
 665         *pages = new_array;
 666         *nr_pages = nr_folios;
 667         return true;
 668 }
 669
 670 static bool io_try_coalesce_buffer(struct page ***pages, int *nr_pages,
 671                                          struct io_imu_folio_data *data)
 672 {
 673         struct page **page_array = *pages;
 674         struct folio *folio = page_folio(page_array[0]);
 675         unsigned int count = 1, nr_folios = 1;
 676         int i;
 677
 678         if (*nr_pages <= 1)
 679                 return false;
 680
 681         data->nr_pages_mid = folio_nr_pages(folio);
 682         if (data->nr_pages_mid == 1)
 683                 return false;
 684
 685         data->folio_shift = folio_shift(folio);
 686         /*
 687          * Check if pages are contiguous inside a folio, and all folios have
 688          * the same page count except for the head and tail.
 689          */
 690         for (i = 1; i < *nr_pages; i++) {
 691                 if (page_folio(page_array[i]) == folio &&
 692                         page_array[i] == page_array[i-1] + 1) {
 693                         count++;
 694                         continue;
 695                 }
 696
 697                 if (nr_folios == 1) {
 698                         if (folio_page_idx(folio, page_array[i-1]) !=
 699                                 data->nr_pages_mid - 1)
 700                                 return false;
 701
 702                         data->nr_pages_head = count;
 703                 } else if (count != data->nr_pages_mid) {
 704                         return false;
 705                 }
 706
 707                 folio = page_folio(page_array[i]);
 708                 if (folio_size(folio) != (1UL << data->folio_shift) ||
 709                         folio_page_idx(folio, page_array[i]) != 0)
 710                         return false;
 711
 712                 count = 1;
 713                 nr_folios++;
 714         }
 715         if (nr_folios == 1)
 716                 data->nr_pages_head = count;
 717
 718         return io_do_coalesce_buffer(pages, nr_pages, data, nr_folios);
 719 }
 720
 721 static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx,
 722                                                    struct iovec *iov,
 723                                                    struct page **last_hpage)
 724 {
 725         struct io_mapped_ubuf *imu = NULL;
 726         struct page **pages = NULL;
 727         struct io_rsrc_node *node;
 728         unsigned long off;
 729         size_t size;
 730         int ret, nr_pages, i;
 731         struct io_imu_folio_data data;
 732         bool coalesced;
 733
 734         if (!iov->iov_base)
 735                 return NULL;
 736
 737         node = io_rsrc_node_alloc(ctx, IORING_RSRC_BUFFER);
 738         if (!node)
 739                 return ERR_PTR(-ENOMEM);
 740         node->buf = NULL;
 741
 742         ret = -ENOMEM;
 743         pages = io_pin_pages((unsigned long) iov->iov_base, iov->iov_len,
 744                                 &nr_pages);
 745         if (IS_ERR(pages)) {
 746                 ret = PTR_ERR(pages);
 747                 pages = NULL;
 748                 goto done;
 749         }
 750
 751         /* If it's huge page(s), try to coalesce them into fewer bvec entries */
 752         coalesced = io_try_coalesce_buffer(&pages, &nr_pages, &data);
 753
 754         imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
 755         if (!imu)
 756                 goto done;
 757
 758         ret = io_buffer_account_pin(ctx, pages, nr_pages, imu, last_hpage);
 759         if (ret) {
 760                 unpin_user_pages(pages, nr_pages);
 761                 goto done;
 762         }
 763
 764         size = iov->iov_len;
 765         /* store original address for later verification */
 766         imu->ubuf = (unsigned long) iov->iov_base;
 767         imu->len = iov->iov_len;
 768         imu->nr_bvecs = nr_pages;
 769         imu->folio_shift = PAGE_SHIFT;
 770         if (coalesced)
 771                 imu->folio_shift = data.folio_shift;
 772         refcount_set(&imu->refs, 1);
 773         off = (unsigned long) iov->iov_base & ((1UL << imu->folio_shift) - 1);
 774         node->buf = imu;
 775         ret = 0;
 776
 777         for (i = 0; i < nr_pages; i++) {
 778                 size_t vec_len;
 779
 780                 vec_len = min_t(size_t, size, (1UL << imu->folio_shift) - off);
 781                 bvec_set_page(&imu->bvec[i], pages[i], vec_len, off);
 782                 off = 0;
 783                 size -= vec_len;
 784         }
 785 done:
 786         if (ret) {
 787                 kvfree(imu);
 788                 if (node)
 789                         io_put_rsrc_node(ctx, node);
 790                 node = ERR_PTR(ret);
 791         }
 792         kvfree(pages);
 793         return node;
 794 }
 795
 796 int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
 797                             unsigned int nr_args, u64 __user *tags)
 798 {
 799         struct page *last_hpage = NULL;
 800         struct io_rsrc_data data;
 801         struct iovec fast_iov, *iov = &fast_iov;
 802         const struct iovec __user *uvec;
 803         int i, ret;
 804
 805         BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
 806
 807         if (ctx->buf_table.nr)
 808                 return -EBUSY;
 809         if (!nr_args || nr_args > IORING_MAX_REG_BUFFERS)
 810                 return -EINVAL;
 811         ret = io_rsrc_data_alloc(&data, nr_args);
 812         if (ret)
 813                 return ret;
 814
 815         if (!arg)
 816                 memset(iov, 0, sizeof(*iov));
 817
 818         for (i = 0; i < nr_args; i++) {
 819                 struct io_rsrc_node *node;
 820                 u64 tag = 0;
 821
 822                 if (arg) {
 823                         uvec = (struct iovec __user *) arg;
 824                         iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
 825                         if (IS_ERR(iov)) {
 826                                 ret = PTR_ERR(iov);
 827                                 break;
 828                         }
 829                         ret = io_buffer_validate(iov);
 830                         if (ret)
 831                                 break;
 832                         if (ctx->compat)
 833                                 arg += sizeof(struct compat_iovec);
 834                         else
 835                                 arg += sizeof(struct iovec);
 836                 }
 837
 838                 if (tags) {
 839                         if (copy_from_user(&tag, &tags[i], sizeof(tag))) {
 840                                 ret = -EFAULT;
 841                                 break;
 842                         }
 843                 }
 844
 845                 node = io_sqe_buffer_register(ctx, iov, &last_hpage);
 846                 if (IS_ERR(node)) {
 847                         ret = PTR_ERR(node);
 848                         break;
 849                 }
 850                 if (tag) {
 851                         if (!node) {
 852                                 ret = -EINVAL;
 853                                 break;
 854                         }
 855                         node->tag = tag;
 856                 }
 857                 data.nodes[i] = node;
 858         }
 859
 860         ctx->buf_table = data;
 861         if (ret)
 862                 io_sqe_buffers_unregister(ctx);
 863         return ret;
 864 }
 865
 866 int io_import_fixed(int ddir, struct iov_iter *iter,
 867                            struct io_mapped_ubuf *imu,
 868                            u64 buf_addr, size_t len)
 869 {
 870         u64 buf_end;
 871         size_t offset;
 872
 873         if (WARN_ON_ONCE(!imu))
 874                 return -EFAULT;
 875         if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
 876                 return -EFAULT;
 877         /* not inside the mapped region */
 878         if (unlikely(buf_addr < imu->ubuf || buf_end > (imu->ubuf + imu->len)))
 879                 return -EFAULT;
 880
 881         /*
 882          * Might not be a start of buffer, set size appropriately
 883          * and advance us to the beginning.
 884          */
 885         offset = buf_addr - imu->ubuf;
 886         iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, offset + len);
 887
 888         if (offset) {
 889                 /*
 890                  * Don't use iov_iter_advance() here, as it's really slow for
 891                  * using the latter parts of a big fixed buffer - it iterates
 892                  * over each segment manually. We can cheat a bit here, because
 893                  * we know that:
 894                  *
 895                  * 1) it's a BVEC iter, we set it up
 896                  * 2) all bvecs are the same in size, except potentially the
 897                  *    first and last bvec
 898                  *
 899                  * So just find our index, and adjust the iterator afterwards.
 900                  * If the offset is within the first bvec (or the whole first
 901                  * bvec, just use iov_iter_advance(). This makes it easier
 902                  * since we can just skip the first segment, which may not
 903                  * be folio_size aligned.
 904                  */
 905                 const struct bio_vec *bvec = imu->bvec;
 906
 907                 if (offset < bvec->bv_len) {
 908                         iter->count -= offset;
 909                         iter->iov_offset = offset;
 910                 } else {
 911                         unsigned long seg_skip;
 912
 913                         /* skip first vec */
 914                         offset -= bvec->bv_len;
 915                         seg_skip = 1 + (offset >> imu->folio_shift);
 916
 917                         iter->bvec += seg_skip;
 918                         iter->nr_segs -= seg_skip;
 919                         iter->count -= bvec->bv_len + offset;
 920                         iter->iov_offset = offset & ((1UL << imu->folio_shift) - 1);
 921                 }
 922         }
 923
 924         return 0;
 925 }
 926
 927 static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx,
 928                             struct io_uring_clone_buffers *arg)
 929 {
 930         struct io_rsrc_data data;
 931         int i, ret, off, nr;
 932         unsigned int nbufs;
 933
 934         /* if offsets are given, must have nr specified too */
 935         if (!arg->nr && (arg->dst_off || arg->src_off))
 936                 return -EINVAL;
 937         /* not allowed unless REPLACE is set */
 938         if (ctx->buf_table.nr && !(arg->flags & IORING_REGISTER_DST_REPLACE))
 939                 return -EBUSY;
 940
 941         nbufs = READ_ONCE(src_ctx->buf_table.nr);
 942         if (!arg->nr)
 943                 arg->nr = nbufs;
 944         else if (arg->nr > nbufs)
 945                 return -EINVAL;
 946         else if (arg->nr > IORING_MAX_REG_BUFFERS)
 947                 return -EINVAL;
 948         if (check_add_overflow(arg->nr, arg->dst_off, &nbufs))
 949                 return -EOVERFLOW;
 950
 951         ret = io_rsrc_data_alloc(&data, max(nbufs, ctx->buf_table.nr));
 952         if (ret)
 953                 return ret;
 954
 955         /* Fill entries in data from dst that won't overlap with src */
 956         for (i = 0; i < min(arg->dst_off, ctx->buf_table.nr); i++) {
 957                 struct io_rsrc_node *src_node = ctx->buf_table.nodes[i];
 958
 959                 if (src_node) {
 960                         data.nodes[i] = src_node;
 961                         src_node->refs++;
 962                 }
 963         }
 964
 965         /*
 966          * Drop our own lock here. We'll setup the data we need and reference
 967          * the source buffers, then re-grab, check, and assign at the end.
 968          */
 969         mutex_unlock(&ctx->uring_lock);
 970
 971         mutex_lock(&src_ctx->uring_lock);
 972         ret = -ENXIO;
 973         nbufs = src_ctx->buf_table.nr;
 974         if (!nbufs)
 975                 goto out_unlock;
 976         ret = -EINVAL;
 977         if (!arg->nr)
 978                 arg->nr = nbufs;
 979         else if (arg->nr > nbufs)
 980                 goto out_unlock;
 981         ret = -EOVERFLOW;
 982         if (check_add_overflow(arg->nr, arg->src_off, &off))
 983                 goto out_unlock;
 984         if (off > nbufs)
 985                 goto out_unlock;
 986
 987         off = arg->dst_off;
 988         i = arg->src_off;
 989         nr = arg->nr;
 990         while (nr--) {
 991                 struct io_rsrc_node *dst_node, *src_node;
 992
 993                 src_node = io_rsrc_node_lookup(&src_ctx->buf_table, i);
 994                 if (!src_node) {
 995                         dst_node = NULL;
 996                 } else {
 997                         dst_node = io_rsrc_node_alloc(ctx, IORING_RSRC_BUFFER);
 998                         if (!dst_node) {
 999                                 ret = -ENOMEM;
1000                                 goto out_put_free;
1001                         }
1002
1003                         refcount_inc(&src_node->buf->refs);
1004                         dst_node->buf = src_node->buf;
1005                 }
1006                 data.nodes[off++] = dst_node;
1007                 i++;
1008         }
1009
1010         /* Have a ref on the bufs now, drop src lock and re-grab our own lock */
1011         mutex_unlock(&src_ctx->uring_lock);
1012         mutex_lock(&ctx->uring_lock);
1013
1014         /*
1015          * If asked for replace, put the old table. data->nodes[] holds both
1016          * old and new nodes at this point.
1017          */
1018         if (arg->flags & IORING_REGISTER_DST_REPLACE)
1019                 io_rsrc_data_free(ctx, &ctx->buf_table);
1020
1021         /*
1022          * ctx->buf_table should be empty now - either the contents are being
1023          * replaced and we just freed the table, or someone raced setting up
1024          * a buffer table while the clone was happening. If not empty, fall
1025          * through to failure handling.
1026          */
1027         if (!ctx->buf_table.nr) {
1028                 ctx->buf_table = data;
1029                 return 0;
1030         }
1031
1032         mutex_unlock(&ctx->uring_lock);
1033         mutex_lock(&src_ctx->uring_lock);
1034         /* someone raced setting up buffers, dump ours */
1035         ret = -EBUSY;
1036 out_put_free:
1037         i = data.nr;
1038         while (i--) {
1039                 io_buffer_unmap(src_ctx, data.nodes[i]);
1040                 kfree(data.nodes[i]);
1041         }
1042 out_unlock:
1043         io_rsrc_data_free(ctx, &data);
1044         mutex_unlock(&src_ctx->uring_lock);
1045         mutex_lock(&ctx->uring_lock);
1046         return ret;
1047 }
1048
1049 /*
1050  * Copy the registered buffers from the source ring whose file descriptor
1051  * is given in the src_fd to the current ring. This is identical to registering
1052  * the buffers with ctx, except faster as mappings already exist.
1053  *
1054  * Since the memory is already accounted once, don't account it again.
1055  */
1056 int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg)
1057 {
1058         struct io_uring_clone_buffers buf;
1059         bool registered_src;
1060         struct file *file;
1061         int ret;
1062
1063         if (copy_from_user(&buf, arg, sizeof(buf)))
1064                 return -EFAULT;
1065         if (buf.flags & ~(IORING_REGISTER_SRC_REGISTERED|IORING_REGISTER_DST_REPLACE))
1066                 return -EINVAL;
1067         if (!(buf.flags & IORING_REGISTER_DST_REPLACE) && ctx->buf_table.nr)
1068                 return -EBUSY;
1069         if (memchr_inv(buf.pad, 0, sizeof(buf.pad)))
1070                 return -EINVAL;
1071
1072         registered_src = (buf.flags & IORING_REGISTER_SRC_REGISTERED) != 0;
1073         file = io_uring_register_get_file(buf.src_fd, registered_src);
1074         if (IS_ERR(file))
1075                 return PTR_ERR(file);
1076         ret = io_clone_buffers(ctx, file->private_data, &buf);
1077         if (!registered_src)
1078                 fput(file);
1079         return ret;
1080 }