There is no general ability to modify kernel parameters. To edit /boot/cmdline.txt you must either already have root access, or the ability to physically swap the card. It only takes effect on the next boot too, so you already have the greatest possible denial of service capability.electronicsguy wrote:Let me put it this way - what specific purpose is being served by having the capability to modify kernel parameters already baked in, in the Raspbian distro, for its users?
Since this thread will not die, may I at least point out that init=shell is not what is properly called single-user mode. Single-user mode is when you add "single" to cmdline, or otherwise boot or transition into runlevel 1 or S. You have almost no background daemons started, and only root may login, on console. If a root password is set, it is normally required to be entered.
init=/bin/bash might be better called "single-process mode". The init system, and runlevels, and init scripts are skipped completely, and a root shell is launched instead. Even important pseudo-filesystems like /dev and /proc and /sys are not mounted, so many normal commands will fail. Job control is not available.