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 do { 23 ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint); 24 if (ret != nr) 25 return ret; 26 27 if (table->alloc_hint == ctx->file_alloc_start) 28 break; 29 nr = table->alloc_hint; 30 table->alloc_hint = ctx->file_alloc_start; 31 } while (1); 32 33 return -ENFILE; 34 } 35 36 bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files) 37 { 38 table->files = kvcalloc(nr_files, sizeof(table->files[0]), 39 GFP_KERNEL_ACCOUNT); 40 if (unlikely(!table->files)) 41 return false; 42 43 table->bitmap = bitmap_zalloc(nr_files, GFP_KERNEL_ACCOUNT); 44 if (unlikely(!table->bitmap)) { 45 kvfree(table->files); 46 return false; 47 } 48 49 return true; 50 } 51 52 void io_free_file_tables(struct io_file_table *table) 53 { 54 kvfree(table->files); 55 bitmap_free(table->bitmap); 56 table->files = NULL; 57 table->bitmap = NULL; 58 } 59 60 static int io_install_fixed_file(struct io_ring_ctx *ctx, struct file *file, 61 u32 slot_index) 62 __must_hold(&req->ctx->uring_lock) 63 { 64 bool needs_switch = false; 65 struct io_fixed_file *file_slot; 66 int ret; 67 68 if (io_is_uring_fops(file)) 69 return -EBADF; 70 if (!ctx->file_data) 71 return -ENXIO; 72 if (slot_index >= ctx->nr_user_files) 73 return -EINVAL; 74 75 slot_index = array_index_nospec(slot_index, ctx->nr_user_files); 76 file_slot = io_fixed_file_slot(&ctx->file_table, slot_index); 77 78 if (file_slot->file_ptr) { 79 struct file *old_file; 80 81 ret = io_rsrc_node_switch_start(ctx); 82 if (ret) 83 goto err; 84 85 old_file = (struct file *)(file_slot->file_ptr & FFS_MASK); 86 ret = io_queue_rsrc_removal(ctx->file_data, slot_index, 87 ctx->rsrc_node, old_file); 88 if (ret) 89 goto err; 90 file_slot->file_ptr = 0; 91 io_file_bitmap_clear(&ctx->file_table, slot_index); 92 needs_switch = true; 93 } 94 95 ret = io_scm_file_account(ctx, file); 96 if (!ret) { 97 *io_get_tag_slot(ctx->file_data, slot_index) = 0; 98 io_fixed_file_set(file_slot, file); 99 io_file_bitmap_set(&ctx->file_table, slot_index); 100 } 101 err: 102 if (needs_switch) 103 io_rsrc_node_switch(ctx, ctx->file_data); 104 return ret; 105 } 106 107 int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file, 108 unsigned int file_slot) 109 { 110 bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC; 111 int ret; 112 113 if (alloc_slot) { 114 ret = io_file_bitmap_get(ctx); 115 if (unlikely(ret < 0)) 116 return ret; 117 file_slot = ret; 118 } else { 119 file_slot--; 120 } 121 122 ret = io_install_fixed_file(ctx, file, file_slot); 123 if (!ret && alloc_slot) 124 ret = file_slot; 125 return ret; 126 } 127 /* 128 * Note when io_fixed_fd_install() returns error value, it will ensure 129 * fput() is called correspondingly. 130 */ 131 int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags, 132 struct file *file, unsigned int file_slot) 133 { 134 struct io_ring_ctx *ctx = req->ctx; 135 int ret; 136 137 io_ring_submit_lock(ctx, issue_flags); 138 ret = __io_fixed_fd_install(ctx, file, file_slot); 139 io_ring_submit_unlock(ctx, issue_flags); 140 141 if (unlikely(ret < 0)) 142 fput(file); 143 return ret; 144 } 145 146 int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset) 147 { 148 struct io_fixed_file *file_slot; 149 struct file *file; 150 int ret; 151 152 if (unlikely(!ctx->file_data)) 153 return -ENXIO; 154 if (offset >= ctx->nr_user_files) 155 return -EINVAL; 156 ret = io_rsrc_node_switch_start(ctx); 157 if (ret) 158 return ret; 159 160 offset = array_index_nospec(offset, ctx->nr_user_files); 161 file_slot = io_fixed_file_slot(&ctx->file_table, offset); 162 if (!file_slot->file_ptr) 163 return -EBADF; 164 165 file = (struct file *)(file_slot->file_ptr & FFS_MASK); 166 ret = io_queue_rsrc_removal(ctx->file_data, offset, ctx->rsrc_node, file); 167 if (ret) 168 return ret; 169 170 file_slot->file_ptr = 0; 171 io_file_bitmap_clear(&ctx->file_table, offset); 172 io_rsrc_node_switch(ctx, ctx->file_data); 173 return 0; 174 } 175 176 int io_register_file_alloc_range(struct io_ring_ctx *ctx, 177 struct io_uring_file_index_range __user *arg) 178 { 179 struct io_uring_file_index_range range; 180 u32 end; 181 182 if (copy_from_user(&range, arg, sizeof(range))) 183 return -EFAULT; 184 if (check_add_overflow(range.off, range.len, &end)) 185 return -EOVERFLOW; 186 if (range.resv || end > ctx->nr_user_files) 187 return -EINVAL; 188 189 io_file_table_set_alloc_range(ctx, range.off, range.len); 190 return 0; 191 } 192