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	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
39bool 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
55void 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
63static 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
96int __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 */
120int 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
135int 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
160int 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}
176