[RFC PATCH v1 07/18] fs: split off need_remove_file_privs() do_remove_file_privs()

[Stefan Roesch <shr@fb.com>]

This splits off the function need_remove_file_privs() from the function
do_remove_file_privs() from the function file_remove_privs().

No intended functional changes in this patch.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/inode.c         | 56 +++++++++++++++++++++++++++++++---------------
 include/linux/fs.h |  3 +++
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 9d9b422504d1..79c5702ef7c3 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2010,17 +2010,8 @@ static int __remove_privs(struct user_namespace *mnt_userns,
 	return notify_change(mnt_userns, dentry, &newattrs, NULL);
 }
 
-/*
- * Remove special file priviledges (suid, capabilities) when file is written
- * to or truncated.
- */
-int file_remove_privs(struct file *file)
+int need_file_remove_privs(struct inode *inode, struct dentry *dentry)
 {
-	struct dentry *dentry = file_dentry(file);
-	struct inode *inode = file_inode(file);
-	int kill;
-	int error = 0;
-
 	/*
 	 * Fast path for nothing security related.
 	 * As well for non-regular files, e.g. blkdev inodes.
@@ -2030,16 +2021,37 @@ int file_remove_privs(struct file *file)
 	if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
 		return 0;
 
-	kill = dentry_needs_remove_privs(dentry);
-	if (kill < 0)
-		return kill;
-	if (kill)
-		error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
+	return dentry_needs_remove_privs(dentry);
+}
+
+int do_file_remove_privs(struct file *file, struct inode *inode,
+			struct dentry *dentry, int kill)
+{
+	int error = 0;
+
+	error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
 	if (!error)
 		inode_has_no_xattr(inode);
 
 	return error;
 }
+
+/*
+ * Remove special file privileges (suid, capabilities) when file is written
+ * to or truncated.
+ */
+int file_remove_privs(struct file *file)
+{
+	struct dentry *dentry = file_dentry(file);
+	struct inode *inode = file_inode(file);
+	int kill;
+
+	kill = need_file_remove_privs(inode, dentry);
+	if (kill <= 0)
+		return kill;
+
+	return do_file_remove_privs(file, inode, dentry, kill);
+}
 EXPORT_SYMBOL(file_remove_privs);
 
 /**
@@ -2094,14 +2106,22 @@ EXPORT_SYMBOL(file_update_time);
 int file_modified(struct file *file)
 {
 	int err;
+	int ret;
+	struct dentry *dentry = file_dentry(file);
+	struct inode *inode = file_inode(file);
 
 	/*
 	 * Clear the security bits if the process is not being run by root.
 	 * This keeps people from modifying setuid and setgid binaries.
 	 */
-	err = file_remove_privs(file);
-	if (err)
-		return err;
+	ret = need_file_remove_privs(inode, dentry);
+	if (ret < 0) {
+		return ret;
+	} else if (ret > 0) {
+		ret = do_file_remove_privs(file, inode, dentry, ret);
+		if (ret)
+			return ret;
+	}
 
 	if (unlikely(file->f_mode & FMODE_NOCMTIME))
 		return 0;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3b479d02e210..c2992d12601f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2381,6 +2381,9 @@ static inline void file_accessed(struct file *file)
 		touch_atime(&file->f_path);
 }
 
+extern int need_file_remove_privs(struct inode *inode, struct dentry *dentry);
+extern int do_file_remove_privs(struct file *file, struct inode *inode,
+				struct dentry *dentry, int kill);
 extern int file_modified(struct file *file);
 
 int sync_inode_metadata(struct inode *inode, int wait);
-- 
2.30.2