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// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "rsrc.h"
#include "filetable.h"
static int io_file_bitmap_get(struct io_ring_ctx *ctx)
{
struct io_file_table *table = &ctx->file_table;
unsigned long nr = ctx->nr_user_files;
int ret;
do {
ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
if (ret != nr)
return ret;
if (!table->alloc_hint)
break;
nr = table->alloc_hint;
table->alloc_hint = 0;
} while (1);
return -ENFILE;
}
bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
{
table->files = kvcalloc(nr_files, sizeof(table->files[0]),
GFP_KERNEL_ACCOUNT);
if (unlikely(!table->files))
return false;
table->bitmap = bitmap_zalloc(nr_files, GFP_KERNEL_ACCOUNT);
if (unlikely(!table->bitmap)) {
kvfree(table->files);
return false;
}
return true;
}
void io_free_file_tables(struct io_file_table *table)
{
kvfree(table->files);
bitmap_free(table->bitmap);
table->files = NULL;
table->bitmap = NULL;
}
static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
unsigned int issue_flags, u32 slot_index)
__must_hold(&req->ctx->uring_lock)
{
struct io_ring_ctx *ctx = req->ctx;
bool needs_switch = false;
struct io_fixed_file *file_slot;
int ret;
if (io_is_uring_fops(file))
return -EBADF;
if (!ctx->file_data)
return -ENXIO;
if (slot_index >= ctx->nr_user_files)
return -EINVAL;
slot_index = array_index_nospec(slot_index, ctx->nr_user_files);
file_slot = io_fixed_file_slot(&ctx->file_table, slot_index);
if (file_slot->file_ptr) {
struct file *old_file;
ret = io_rsrc_node_switch_start(ctx);
if (ret)
goto err;
old_file = (struct file *)(file_slot->file_ptr & FFS_MASK);
ret = io_queue_rsrc_removal(ctx->file_data, slot_index,
ctx->rsrc_node, old_file);
if (ret)
goto err;
file_slot->file_ptr = 0;
io_file_bitmap_clear(&ctx->file_table, slot_index);
needs_switch = true;
}
ret = io_scm_file_account(ctx, file);
if (!ret) {
*io_get_tag_slot(ctx->file_data, slot_index) = 0;
io_fixed_file_set(file_slot, file);
io_file_bitmap_set(&ctx->file_table, slot_index);
}
err:
if (needs_switch)
io_rsrc_node_switch(ctx, ctx->file_data);
if (ret)
fput(file);
return ret;
}
/*
* Note when io_fixed_fd_install() returns error value, it will ensure
* fput() is called correspondingly.
*/
int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
struct file *file, unsigned int file_slot)
{
bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
struct io_ring_ctx *ctx = req->ctx;
int ret;
io_ring_submit_lock(ctx, issue_flags);
if (alloc_slot) {
ret = io_file_bitmap_get(ctx);
if (unlikely(ret < 0))
goto err;
file_slot = ret;
} else {
file_slot--;
}
ret = io_install_fixed_file(req, file, issue_flags, file_slot);
if (!ret && alloc_slot)
ret = file_slot;
err:
io_ring_submit_unlock(ctx, issue_flags);
if (unlikely(ret < 0))
fput(file);
return ret;
}
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