Mastering Embedded Linux Programming - Second Edition

File ownership permissions in the staging directory

For security and stability reasons, it is vitally important to pay attention to the ownership and permissions of the files that will be placed on the target device. Generally speaking, you want to restrict sensitive resources to be accessible only by the root and wherever possible, to run programs using non-root users so that if they are compromised by an outside attack, they offer as few system resources to the attacker as possible. For example, the device node called /dev/mem gives access to system memory, which is necessary in some programs. But, if it is readable and writeable by everyone, then there is no security because everyone can access everything in memory. So, /dev/mem should ...