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 }
176
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