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
 16static 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	if (table->alloc_hint < ctx->file_alloc_start ||
 26	    table->alloc_hint >= ctx->file_alloc_end)
 27		table->alloc_hint = ctx->file_alloc_start;
 28
 29	do {
 30		ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
 31		if (ret != nr)
 32			return ret;
 33
 34		if (table->alloc_hint == ctx->file_alloc_start)
 35			break;
 36		nr = table->alloc_hint;
 37		table->alloc_hint = ctx->file_alloc_start;
 38	} while (1);
 39
 40	return -ENFILE;
 41}
 42
 43bool io_alloc_file_tables(struct io_ring_ctx *ctx, struct io_file_table *table,
 44			  unsigned nr_files)
 45{
 46	if (io_rsrc_data_alloc(&table->data, nr_files))
 47		return false;
 48	table->bitmap = bitmap_zalloc(nr_files, GFP_KERNEL_ACCOUNT);
 49	if (table->bitmap)
 50		return true;
 51	io_rsrc_data_free(ctx, &table->data);
 52	return false;
 53}
 54
 55void io_free_file_tables(struct io_ring_ctx *ctx, struct io_file_table *table)
 56{
 57	io_rsrc_data_free(ctx, &table->data);
 58	bitmap_free(table->bitmap);
 59	table->bitmap = NULL;
 60}
 61
 62static int io_install_fixed_file(struct io_ring_ctx *ctx, struct file *file,
 63				 u32 slot_index)
 64	__must_hold(&ctx->uring_lock)
 65{
 66	struct io_rsrc_node *node;
 67
 68	if (io_is_uring_fops(file))
 69		return -EBADF;
 70	if (!ctx->file_table.data.nr)
 71		return -ENXIO;
 72	if (slot_index >= ctx->file_table.data.nr)
 73		return -EINVAL;
 74
 75	node = io_rsrc_node_alloc(ctx, IORING_RSRC_FILE);
 76	if (!node)
 77		return -ENOMEM;
 78
 79	if (!io_reset_rsrc_node(ctx, &ctx->file_table.data, slot_index))
 80		io_file_bitmap_set(&ctx->file_table, slot_index);
 81
 82	ctx->file_table.data.nodes[slot_index] = node;
 83	io_fixed_file_set(node, file);
 84	return 0;
 85}
 86
 87int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file,
 88			  unsigned int file_slot)
 89{
 90	bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
 91	int ret;
 92
 93	if (alloc_slot) {
 94		ret = io_file_bitmap_get(ctx);
 95		if (unlikely(ret < 0))
 96			return ret;
 97		file_slot = ret;
 98	} else {
 99		file_slot--;
100	}
101
102	ret = io_install_fixed_file(ctx, file, file_slot);
103	if (!ret && alloc_slot)
104		ret = file_slot;
105	return ret;
106}
107/*
108 * Note when io_fixed_fd_install() returns error value, it will ensure
109 * fput() is called correspondingly.
110 */
111int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
112			struct file *file, unsigned int file_slot)
113{
114	struct io_ring_ctx *ctx = req->ctx;
115	int ret;
116
117	io_ring_submit_lock(ctx, issue_flags);
118	ret = __io_fixed_fd_install(ctx, file, file_slot);
119	io_ring_submit_unlock(ctx, issue_flags);
120
121	if (unlikely(ret < 0))
122		fput(file);
123	return ret;
124}
125
126int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
127{
128	struct io_rsrc_node *node;
129
130	if (unlikely(!ctx->file_table.data.nr))
131		return -ENXIO;
132	if (offset >= ctx->file_table.data.nr)
133		return -EINVAL;
134
135	node = io_rsrc_node_lookup(&ctx->file_table.data, offset);
136	if (!node)
137		return -EBADF;
138	io_reset_rsrc_node(ctx, &ctx->file_table.data, offset);
139	io_file_bitmap_clear(&ctx->file_table, offset);
140	return 0;
141}
142
143int io_register_file_alloc_range(struct io_ring_ctx *ctx,
144				 struct io_uring_file_index_range __user *arg)
145{
146	struct io_uring_file_index_range range;
147	u32 end;
148
149	if (copy_from_user(&range, arg, sizeof(range)))
150		return -EFAULT;
151	if (check_add_overflow(range.off, range.len, &end))
152		return -EOVERFLOW;
153	if (range.resv || end > ctx->file_table.data.nr)
154		return -EINVAL;
155
156	io_file_table_set_alloc_range(ctx, range.off, range.len);
157	return 0;
158}