linux/io_uring/openclose.c
Amir Goldstein 7b8c9d7bb4 fsnotify: move fsnotify_open() hook into do_dentry_open()
fsnotify_open() hook is called only from high level system calls
context and not called for the very many helpers to open files.

This may makes sense for many of the special file open cases, but it is
inconsistent with fsnotify_close() hook that is called for every last
fput() of on a file object with FMODE_OPENED.

As a result, it is possible to observe ACCESS, MODIFY and CLOSE events
without ever observing an OPEN event.

Fix this inconsistency by replacing all the fsnotify_open() hooks with
a single hook inside do_dentry_open().

If there are special cases that would like to opt-out of the possible
overhead of fsnotify() call in fsnotify_open(), they would probably also
want to avoid the overhead of fsnotify() call in the rest of the fsnotify
hooks, so they should be opening that file with the __FMODE_NONOTIFY flag.

However, in the majority of those cases, the s_fsnotify_connectors
optimization in fsnotify_parent() would be sufficient to avoid the
overhead of fsnotify() call anyway.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230611122429.1499617-1-amir73il@gmail.com>
2023-06-12 10:43:45 +02:00

262 lines
6.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/fsnotify.h>
#include <linux/namei.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "../fs/internal.h"
#include "io_uring.h"
#include "rsrc.h"
#include "openclose.h"
struct io_open {
struct file *file;
int dfd;
u32 file_slot;
struct filename *filename;
struct open_how how;
unsigned long nofile;
};
struct io_close {
struct file *file;
int fd;
u32 file_slot;
};
static bool io_openat_force_async(struct io_open *open)
{
/*
* Don't bother trying for O_TRUNC, O_CREAT, or O_TMPFILE open,
* it'll always -EAGAIN
*/
return open->how.flags & (O_TRUNC | O_CREAT | O_TMPFILE);
}
static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
const char __user *fname;
int ret;
if (unlikely(sqe->buf_index))
return -EINVAL;
if (unlikely(req->flags & REQ_F_FIXED_FILE))
return -EBADF;
/* open.how should be already initialised */
if (!(open->how.flags & O_PATH) && force_o_largefile())
open->how.flags |= O_LARGEFILE;
open->dfd = READ_ONCE(sqe->fd);
fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
open->filename = getname(fname);
if (IS_ERR(open->filename)) {
ret = PTR_ERR(open->filename);
open->filename = NULL;
return ret;
}
open->file_slot = READ_ONCE(sqe->file_index);
if (open->file_slot && (open->how.flags & O_CLOEXEC))
return -EINVAL;
open->nofile = rlimit(RLIMIT_NOFILE);
req->flags |= REQ_F_NEED_CLEANUP;
if (io_openat_force_async(open))
req->flags |= REQ_F_FORCE_ASYNC;
return 0;
}
int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
u64 mode = READ_ONCE(sqe->len);
u64 flags = READ_ONCE(sqe->open_flags);
open->how = build_open_how(flags, mode);
return __io_openat_prep(req, sqe);
}
int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
struct open_how __user *how;
size_t len;
int ret;
how = u64_to_user_ptr(READ_ONCE(sqe->addr2));
len = READ_ONCE(sqe->len);
if (len < OPEN_HOW_SIZE_VER0)
return -EINVAL;
ret = copy_struct_from_user(&open->how, sizeof(open->how), how, len);
if (ret)
return ret;
return __io_openat_prep(req, sqe);
}
int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
struct open_flags op;
struct file *file;
bool resolve_nonblock, nonblock_set;
bool fixed = !!open->file_slot;
int ret;
ret = build_open_flags(&open->how, &op);
if (ret)
goto err;
nonblock_set = op.open_flag & O_NONBLOCK;
resolve_nonblock = open->how.resolve & RESOLVE_CACHED;
if (issue_flags & IO_URING_F_NONBLOCK) {
WARN_ON_ONCE(io_openat_force_async(open));
op.lookup_flags |= LOOKUP_CACHED;
op.open_flag |= O_NONBLOCK;
}
if (!fixed) {
ret = __get_unused_fd_flags(open->how.flags, open->nofile);
if (ret < 0)
goto err;
}
file = do_filp_open(open->dfd, open->filename, &op);
if (IS_ERR(file)) {
/*
* We could hang on to this 'fd' on retrying, but seems like
* marginal gain for something that is now known to be a slower
* path. So just put it, and we'll get a new one when we retry.
*/
if (!fixed)
put_unused_fd(ret);
ret = PTR_ERR(file);
/* only retry if RESOLVE_CACHED wasn't already set by application */
if (ret == -EAGAIN &&
(!resolve_nonblock && (issue_flags & IO_URING_F_NONBLOCK)))
return -EAGAIN;
goto err;
}
if ((issue_flags & IO_URING_F_NONBLOCK) && !nonblock_set)
file->f_flags &= ~O_NONBLOCK;
if (!fixed)
fd_install(ret, file);
else
ret = io_fixed_fd_install(req, issue_flags, file,
open->file_slot);
err:
putname(open->filename);
req->flags &= ~REQ_F_NEED_CLEANUP;
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}
int io_openat(struct io_kiocb *req, unsigned int issue_flags)
{
return io_openat2(req, issue_flags);
}
void io_open_cleanup(struct io_kiocb *req)
{
struct io_open *open = io_kiocb_to_cmd(req, struct io_open);
if (open->filename)
putname(open->filename);
}
int __io_close_fixed(struct io_ring_ctx *ctx, unsigned int issue_flags,
unsigned int offset)
{
int ret;
io_ring_submit_lock(ctx, issue_flags);
ret = io_fixed_fd_remove(ctx, offset);
io_ring_submit_unlock(ctx, issue_flags);
return ret;
}
static inline int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_close *close = io_kiocb_to_cmd(req, struct io_close);
return __io_close_fixed(req->ctx, issue_flags, close->file_slot - 1);
}
int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_close *close = io_kiocb_to_cmd(req, struct io_close);
if (sqe->off || sqe->addr || sqe->len || sqe->rw_flags || sqe->buf_index)
return -EINVAL;
if (req->flags & REQ_F_FIXED_FILE)
return -EBADF;
close->fd = READ_ONCE(sqe->fd);
close->file_slot = READ_ONCE(sqe->file_index);
if (close->file_slot && close->fd)
return -EINVAL;
return 0;
}
int io_close(struct io_kiocb *req, unsigned int issue_flags)
{
struct files_struct *files = current->files;
struct io_close *close = io_kiocb_to_cmd(req, struct io_close);
struct fdtable *fdt;
struct file *file;
int ret = -EBADF;
if (close->file_slot) {
ret = io_close_fixed(req, issue_flags);
goto err;
}
spin_lock(&files->file_lock);
fdt = files_fdtable(files);
if (close->fd >= fdt->max_fds) {
spin_unlock(&files->file_lock);
goto err;
}
file = rcu_dereference_protected(fdt->fd[close->fd],
lockdep_is_held(&files->file_lock));
if (!file || io_is_uring_fops(file)) {
spin_unlock(&files->file_lock);
goto err;
}
/* if the file has a flush method, be safe and punt to async */
if (file->f_op->flush && (issue_flags & IO_URING_F_NONBLOCK)) {
spin_unlock(&files->file_lock);
return -EAGAIN;
}
file = __close_fd_get_file(close->fd);
spin_unlock(&files->file_lock);
if (!file)
goto err;
/* No ->flush() or already async, safely close from here */
ret = filp_close(file, current->files);
err:
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}