To fix list

• Unveil driver does not support multiprocess.
• Child processes do not inherit the parent's pledge and unveil calls.
• Vulnerable to Time-of-check to time-of-use attack.
• Unveil driver only works with absolute paths. It uses a very simple string comparison to check for allowed paths and it can be fooled in many ways. For example, ../../,/d?v/ or using a network address.
• Unveil driver hooks only openat system call to check if opened files are allowed. Other system calls need to be hooked like open.
• A lot of functions lack error checking.
• Incomplete mapping from pledge promises to Linux system calls.
• Pledge second parameter char *execpromises is not implemented
• Unveil second parameter char *permissions is not implemented.

unveil_driver/ftrace_helper.h is a modified copy form https://github.com/shubham0d/Immutable-file-linux