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                 io_file_bitmap_clear(&ctx->file_table, slot_index);
  88         }
  89
  90         ret = io_scm_file_account(ctx, file);
  91         if (!ret) {
  92                 *io_get_tag_slot(ctx->file_data, slot_index) = 0;
  93                 io_fixed_file_set(file_slot, file);
  94                 io_file_bitmap_set(&ctx->file_table, slot_index);
  95         }
  96         return ret;
  97 }
  98
  99 int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file,
 100                           unsigned int file_slot)
 101 {
 102         bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
 103         int ret;
 104
 105         if (alloc_slot) {
 106                 ret = io_file_bitmap_get(ctx);
 107                 if (unlikely(ret < 0))
 108                         return ret;
 109                 file_slot = ret;
 110         } else {
 111                 file_slot--;
 112         }
 113
 114         ret = io_install_fixed_file(ctx, file, file_slot);
 115         if (!ret && alloc_slot)
 116                 ret = file_slot;
 117         return ret;
 118 }
 119 /*
 120  * Note when io_fixed_fd_install() returns error value, it will ensure
 121  * fput() is called correspondingly.
 122  */
 123 int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
 124                         struct file *file, unsigned int file_slot)
 125 {
 126         struct io_ring_ctx *ctx = req->ctx;
 127         int ret;
 128
 129         io_ring_submit_lock(ctx, issue_flags);
 130         ret = __io_fixed_fd_install(ctx, file, file_slot);
 131         io_ring_submit_unlock(ctx, issue_flags);
 132
 133         if (unlikely(ret < 0))
 134                 fput(file);
 135         return ret;
 136 }
 137
 138 int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
 139 {
 140         struct io_fixed_file *file_slot;
 141         int ret;
 142
 143         if (unlikely(!ctx->file_data))
 144                 return -ENXIO;
 145         if (offset >= ctx->nr_user_files)
 146                 return -EINVAL;
 147
 148         offset = array_index_nospec(offset, ctx->nr_user_files);
 149         file_slot = io_fixed_file_slot(&ctx->file_table, offset);
 150         if (!file_slot->file_ptr)
 151                 return -EBADF;
 152
 153         ret = io_queue_rsrc_removal(ctx->file_data, offset,
 154                                     io_slot_file(file_slot));
 155         if (ret)
 156                 return ret;
 157
 158         file_slot->file_ptr = 0;
 159         io_file_bitmap_clear(&ctx->file_table, offset);
 160         return 0;
 161 }
 162
 163 int io_register_file_alloc_range(struct io_ring_ctx *ctx,
 164                                  struct io_uring_file_index_range __user *arg)
 165 {
 166         struct io_uring_file_index_range range;
 167         u32 end;
 168
 169         if (copy_from_user(&range, arg, sizeof(range)))
 170                 return -EFAULT;
 171         if (check_add_overflow(range.off, range.len, &end))
 172                 return -EOVERFLOW;
 173         if (range.resv || end > ctx->nr_user_files)
 174                 return -EINVAL;
 175
 176         io_file_table_set_alloc_range(ctx, range.off, range.len);
 177         return 0;
 178 }