fs: Fix S_NOSEC handling

commit 2426f3910069ed47c0cc58559a6d088af7920201 upstream.

file_remove_suid() could mistakenly set S_NOSEC inode bit when root was
modifying the file. As a result following writes to the file by ordinary
user would avoid clearing suid or sgid bits.

Fix the bug by checking actual mode bits before setting S_NOSEC.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

diff --git a/fs/inode.c b/fs/inode.c
index d9134a0f5dd99763fc669c0149f7a2bad783acd3..9ec57cb0aacd9ee33d64ea369932f1c3a570f9ec 100644 (file)
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1599,8 +1599,8 @@ int file_remove_suid(struct file *file)
                error = security_inode_killpriv(dentry);
        if (!error && killsuid)
                error = __remove_suid(dentry, killsuid);
-       if (!error && (inode->i_sb->s_flags & MS_NOSEC))
-               inode->i_flags |= S_NOSEC;
+       if (!error)
+               inode_has_no_xattr(inode);
 
        return error;
 }