From 6de37b6dc085e7c5e092b69289af66876526da44 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Tue, 10 Jul 2018 13:12:05 -0400
Subject: [PATCH] pass creds to get_empty_filp(), make sure dentry_open()
 passes the right creds

... and rename get_empty_filp() to alloc_empty_file().

dentry_open() gets creds as argument, but the only thing that sees those is
security_file_open() - file->f_cred still ends up with current_cred().  For
almost all callers it's the same thing, but there are several broken cases.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/file_table.c | 5 ++---
 fs/internal.h   | 2 +-
 fs/namei.c      | 2 +-
 fs/open.c       | 2 +-
 4 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index 086c3f5ec31a..76cfa4c43e13 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -101,9 +101,8 @@ int proc_nr_files(struct ctl_table *table, int write,
  * done, you will imbalance int the mount's writer count
  * and a warning at __fput() time.
  */
-struct file *get_empty_filp(void)
+struct file *alloc_empty_file(const struct cred *cred)
 {
-	const struct cred *cred = current_cred();
 	static long old_max;
 	struct file *f;
 	int error;
@@ -161,7 +160,7 @@ struct file *alloc_file(const struct path *path, int flags,
 {
 	struct file *file;
 
-	file = get_empty_filp();
+	file = alloc_empty_file(current_cred());
 	if (IS_ERR(file))
 		return file;
 
diff --git a/fs/internal.h b/fs/internal.h
index 5645b4ebf494..66473bf388e4 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -93,7 +93,7 @@ extern void chroot_fs_refs(const struct path *, const struct path *);
 /*
  * file_table.c
  */
-extern struct file *get_empty_filp(void);
+extern struct file *alloc_empty_file(const struct cred *);
 
 /*
  * super.c
diff --git a/fs/namei.c b/fs/namei.c
index 734cef54fdf8..af2ec1803f57 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3513,7 +3513,7 @@ static struct file *path_openat(struct nameidata *nd,
 	int opened = 0;
 	int error;
 
-	file = get_empty_filp();
+	file = alloc_empty_file(current_cred());
 	if (IS_ERR(file))
 		return file;
 
diff --git a/fs/open.c b/fs/open.c
index 530da965e369..0061f9ea044d 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -921,7 +921,7 @@ struct file *dentry_open(const struct path *path, int flags,
 	/* We must always pass in a valid mount pointer. */
 	BUG_ON(!path->mnt);
 
-	f = get_empty_filp();
+	f = alloc_empty_file(cred);
 	if (!IS_ERR(f)) {
 		f->f_flags = flags;
 		error = vfs_open(path, f, cred);
-- 
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