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authorLinus Torvalds <torvalds@linux-foundation.org>2021-08-31 12:00:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-31 12:00:07 -0700
commit927bc120a248b658acc2f5206ec4e81a794d8a57 (patch)
tree8dd8cae41b2c74c8ea914c9a03a9036fc05367c0
parent1dd5915a5cbda100e67823e7a4ca7af919185ea6 (diff)
parent03ba0fe4d09f2eb0a91888caaa057ed67462ae2d (diff)
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 9b5b872215fe ("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 03ba0fe4d09f ("file: simplify logic in __close_range()") Link: https://lore.kernel.org/linux-fsdevel/20210402123548.108372-3-brauner@kernel.org Commit f49fd6d3c070 ("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
-rw-r--r--fs/file.c64
1 files changed, 40 insertions, 24 deletions
diff --git a/fs/file.c b/fs/file.c
index 86dc9956af32..d8afa8266859 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -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)
+ if (!IS_ERR(file)) {
+ /* found a valid file to close */
+ filp_close(file, cur_fds);
+ cond_resched();
continue;
+ }
- filp_close(file, cur_fds);
- cond_resched();
+ /* 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) && (max_fd >= cur_max))
- max_unshare_fds = fd;
+ 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.
+ */
+ 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

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