To enable kexec makes sense for a generic distro kernel. But if your users have root and you want to make it hard for them to run code in ring 0, you commonly disable further module loading and you also want to disable kexec[1]. Kees Cook wrote up a patch[2] that we'd like to see applied to the Ubuntu kernel to avoid recompilation of the distro kernel.
I'm marking this as a security issue on the ground that it's quite surprising that setting kernel.modules_disabled=1 as a hardening feature can be subverted by using kexec.
To enable kexec makes sense for a generic distro kernel. But if your users have root and you want to make it hard for them to run code in ring 0, you commonly disable further module loading and you also want to disable kexec[1]. Kees Cook wrote up a patch[2] that we'd like to see applied to the Ubuntu kernel to avoid recompilation of the distro kernel.
I'm marking this as a security issue on the ground that it's quite surprising that setting kernel. modules_ disabled= 1 as a hardening feature can be subverted by using kexec.
[1] http:// mjg59.dreamwidt h.org/28746. html /lkml.org/ lkml/2013/ 12/9/765
[2] https:/