Crate modinsert

A dirty module-loading library for the Linux kernel.

This abuses Linux modules auto-loading mechanism to trick the kernel into shelling out to the userspace modprobe helper.

A side-effect of SIOCGIFINDEX ioctl results in the kernel looking up and loading arbitrary modules by name. This isn’t strictly a privilege escalation as the caller must have CAP_SYS_MODULE capability; however it allows containerized process to load modules in the host namespace.

This is a dirty mechanism, as the ioctl syscall will induce a context-switch back from kernel-space to user-space to run a host binary outside of caller context.

Typically this results in modprobe being called in the host, however arbitrary binaries can be run by tweaking the usermode helper sysctl at /proc/sys/kernel/modprobe.

Functions

try_load

Try to load a host kernel module via the modprobe userspace helper.