Commit 927bc120 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'fs.close_range.v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux 

Pull close_range() cleanup from Christian Brauner:
 "This is a cleanup for close_range() which was sent as part of a bugfix
  we did some time ago in commit 9b5b8722 ("file: fix close_range()
  for unshare+cloexec").

  We used to share more code between some helpers for close_range()
  which made retrieving the maximum number of open fds before calling
  into the helpers sensible. But with the introduction of
  CLOSE_RANGE_CLOEXEC and the need to retrieve the number of maximum fds
  once more for CLOSE_RANGE_CLOEXEC that stopped making sense. So the
  code was in a dumb in-limbo state.

  Fix this by simplifying the code a bit.

  The original idea was to only fix the bug itself and make backporting
  easy. And since the cleanup wasn't very pressing I left it in
  linux-next for a very long time. I didn't pull the patches from the
  list again back then which is why they don't have lore-links. So I'm
  listing them below explicitly"

Commit 03ba0fe4 ("file: simplify logic in __close_range()")
Link: https://lore.kernel.org/linux-fsdevel/20210402123548.108372-3-brauner@kernel.org

Commit f49fd6d3 ("file: let pick_file() tell caller it's done")
Link: https://lore.kernel.org/linux-fsdevel/20210402123548.108372-4-brauner@kernel.org

* tag 'fs.close_range.v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  file: simplify logic in __close_range()
  file: let pick_file() tell caller it's done
parents 1dd5915a 03ba0fe4

fs/file.c

+40 −24
Original line number Diff line number Diff line
@@ -596,18 +596,32 @@ void fd_install(unsigned int fd, struct file *file) 


EXPORT_SYMBOL(fd_install);



/**

 * pick_file - return file associatd with fd

 * @files: file struct to retrieve file from

 * @fd: file descriptor to retrieve file for

 *

 * If this functions returns an EINVAL error pointer the fd was beyond the

 * current maximum number of file descriptors for that fdtable.

 *

 * Returns: The file associated with @fd, on error returns an error pointer.

 */

static struct file *pick_file(struct files_struct *files, unsigned fd)

{

	struct file *file = NULL;

	struct file *file;

	struct fdtable *fdt;



	spin_lock(&files->file_lock);

	fdt = files_fdtable(files);

	if (fd >= fdt->max_fds)

	if (fd >= fdt->max_fds) {

		file = ERR_PTR(-EINVAL);

		goto out_unlock;

	}

	file = fdt->fd[fd];

	if (!file)

	if (!file) {

		file = ERR_PTR(-EBADF);

		goto out_unlock;

	}

	rcu_assign_pointer(fdt->fd[fd], NULL);

	__put_unused_fd(files, fd);
@@ -622,7 +636,7 @@ int close_fd(unsigned fd) 
	struct file *file;



	file = pick_file(files, fd);

	if (!file)

	if (IS_ERR(file))

		return -EBADF;



	return filp_close(file, files);
@@ -663,11 +677,16 @@ static inline void __range_close(struct files_struct *cur_fds, unsigned int fd, 
		struct file *file;



		file = pick_file(cur_fds, fd++);

		if (!file)

			continue;



		if (!IS_ERR(file)) {

			/* found a valid file to close */

			filp_close(file, cur_fds);

			cond_resched();

			continue;

		}



		/* beyond the last fd in that table */

		if (PTR_ERR(file) == -EINVAL)

			return;

	}

}
@@ -682,7 +701,6 @@ static inline void __range_close(struct files_struct *cur_fds, unsigned int fd, 
 */

int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)

{

	unsigned int cur_max;

	struct task_struct *me = current;

	struct files_struct *cur_fds = me->files, *fds = NULL;
@@ -692,26 +710,26 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) 
	if (fd > max_fd)

		return -EINVAL;



	rcu_read_lock();

	cur_max = files_fdtable(cur_fds)->max_fds;

	rcu_read_unlock();



	/* cap to last valid index into fdtable */

	cur_max--;



	if (flags & CLOSE_RANGE_UNSHARE) {

		int ret;

		unsigned int max_unshare_fds = NR_OPEN_MAX;



		/*

		 * If the requested range is greater than the current maximum,

		 * we're closing everything so only copy all file descriptors

		 * beneath the lowest file descriptor.

		 * If the caller requested all fds to be made cloexec copy all

		 * of the file descriptors since they still want to use them.

		 * If the caller requested all fds to be made cloexec we always

		 * copy all of the file descriptors since they still want to

		 * use them.

		 */

		if (!(flags & CLOSE_RANGE_CLOEXEC)) {

			/*

			 * If the requested range is greater than the current

			 * maximum, we're closing everything so only copy all

			 * file descriptors beneath the lowest file descriptor.

			 */

		if (!(flags & CLOSE_RANGE_CLOEXEC) && (max_fd >= cur_max))

			rcu_read_lock();

			if (max_fd >= last_fd(files_fdtable(cur_fds)))

				max_unshare_fds = fd;

			rcu_read_unlock();

		}



		ret = unshare_fd(CLONE_FILES, max_unshare_fds, &fds);

		if (ret)
@@ -725,8 +743,6 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) 
			swap(cur_fds, fds);

	}



	max_fd = min(max_fd, cur_max);



	if (flags & CLOSE_RANGE_CLOEXEC)

		__range_cloexec(cur_fds, fd, max_fd);

	else