io_uring/filetable.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/errno.h>
   4 #include <linux/file.h>
   5 #include <linux/mm.h>
   6 #include <linux/slab.h>
   7 #include <linux/nospec.h>
   8 #include <linux/io_uring.h>
   9
  10 #include <uapi/linux/io_uring.h>
  11
  12 #include "io_uring.h"
  13 #include "rsrc.h"
  14 #include "filetable.h"
  15
  16 static int io_file_bitmap_get(struct io_ring_ctx *ctx)
  17 {
  18         struct io_file_table *table = &ctx->file_table;
  19         unsigned long nr = ctx->file_alloc_end;
  20         int ret;
  21
  22         if (!table->bitmap)
  23                 return -ENFILE;
  24
  25         do {
  26                 ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
  27                 if (ret != nr)
  28                         return ret;
  29
  30                 if (table->alloc_hint == ctx->file_alloc_start)
  31                         break;
  32                 nr = table->alloc_hint;
  33                 table->alloc_hint = ctx->file_alloc_start;
  34         } while (1);
  35
  36         return -ENFILE;
  37 }
  38
  39 bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
  40 {
  41         table->files = kvcalloc(nr_files, sizeof(table->files[0]),
  42                                 GFP_KERNEL_ACCOUNT);
  43         if (unlikely(!table->files))
  44                 return false;
  45
  46         table->bitmap = bitmap_zalloc(nr_files, GFP_KERNEL_ACCOUNT);
  47         if (unlikely(!table->bitmap)) {
  48                 kvfree(table->files);
  49                 return false;
  50         }
  51
  52         return true;
  53 }
  54
  55 void io_free_file_tables(struct io_file_table *table)
  56 {
  57         kvfree(table->files);
  58         bitmap_free(table->bitmap);
  59         table->files = NULL;
  60         table->bitmap = NULL;
  61 }
  62
  63 static int io_install_fixed_file(struct io_ring_ctx *ctx, struct file *file,
  64                                  u32 slot_index)
  65         __must_hold(&req->ctx->uring_lock)
  66 {
  67         struct io_fixed_file *file_slot;
  68         int ret;
  69
  70         if (io_is_uring_fops(file))
  71                 return -EBADF;
  72         if (!ctx->file_data)
  73                 return -ENXIO;
  74         if (slot_index >= ctx->nr_user_files)
  75                 return -EINVAL;
  76
  77         slot_index = array_index_nospec(slot_index, ctx->nr_user_files);
  78         file_slot = io_fixed_file_slot(&ctx->file_table, slot_index);
  79
  80         if (file_slot->file_ptr) {
  81                 ret = io_queue_rsrc_removal(ctx->file_data, slot_index,
  82                                             io_slot_file(file_slot));
  83                 if (ret)
  84                         return ret;
  85
  86                 file_slot->file_ptr = 0;
  87         } else {
  88                 io_file_bitmap_set(&ctx->file_table, slot_index);
  89         }
  90
  91         *io_get_tag_slot(ctx->file_data, slot_index) = 0;
  92         io_fixed_file_set(file_slot, file);
  93         return 0;
  94 }
  95
  96 int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file,
  97                           unsigned int file_slot)
  98 {
  99         bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
 100         int ret;
 101
 102         if (alloc_slot) {
 103                 ret = io_file_bitmap_get(ctx);
 104                 if (unlikely(ret < 0))
 105                         return ret;
 106                 file_slot = ret;
 107         } else {
 108                 file_slot--;
 109         }
 110
 111         ret = io_install_fixed_file(ctx, file, file_slot);
 112         if (!ret && alloc_slot)
 113                 ret = file_slot;
 114         return ret;
 115 }
 116 /*
 117  * Note when io_fixed_fd_install() returns error value, it will ensure
 118  * fput() is called correspondingly.
 119  */
 120 int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
 121                         struct file *file, unsigned int file_slot)
 122 {
 123         struct io_ring_ctx *ctx = req->ctx;
 124         int ret;
 125
 126         io_ring_submit_lock(ctx, issue_flags);
 127         ret = __io_fixed_fd_install(ctx, file, file_slot);
 128         io_ring_submit_unlock(ctx, issue_flags);
 129
 130         if (unlikely(ret < 0))
 131                 fput(file);
 132         return ret;
 133 }
 134
 135 int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
 136 {
 137         struct io_fixed_file *file_slot;
 138         int ret;
 139
 140         if (unlikely(!ctx->file_data))
 141                 return -ENXIO;
 142         if (offset >= ctx->nr_user_files)
 143                 return -EINVAL;
 144
 145         offset = array_index_nospec(offset, ctx->nr_user_files);
 146         file_slot = io_fixed_file_slot(&ctx->file_table, offset);
 147         if (!file_slot->file_ptr)
 148                 return -EBADF;
 149
 150         ret = io_queue_rsrc_removal(ctx->file_data, offset,
 151                                     io_slot_file(file_slot));
 152         if (ret)
 153                 return ret;
 154
 155         file_slot->file_ptr = 0;
 156         io_file_bitmap_clear(&ctx->file_table, offset);
 157         return 0;
 158 }
 159
 160 int io_register_file_alloc_range(struct io_ring_ctx *ctx,
 161                                  struct io_uring_file_index_range __user *arg)
 162 {
 163         struct io_uring_file_index_range range;
 164         u32 end;
 165
 166         if (copy_from_user(&range, arg, sizeof(range)))
 167                 return -EFAULT;
 168         if (check_add_overflow(range.off, range.len, &end))
 169                 return -EOVERFLOW;
 170         if (range.resv || end > ctx->nr_user_files)
 171                 return -EINVAL;
 172
 173         io_file_table_set_alloc_range(ctx, range.off, range.len);
 174         return 0;
 175 }