Re: Checking integrity of /sbin/init from within kernel

["Torsten Valentin" <winsock2@musiker.de>]

> boot from a ramdisk kernel, don't compile ata or scsi support
> into the kernel. much simpler, no modification needed.

I cannot leave out scsi support, because (besides other reasons) I need
physical access to a hd for writing logs. I could use a ramdisk-kernel
though. Does that help? Does that make sure that init is guaranteed
unmodified? Isn't there a possibility to separate the contents of a
ramdisk kernel from the kernel itself, alter files and reassemble it?

This thread is drifting away from my initial request.

I hope I could make clear to all participants of this thread, that my
concept is not breakable "just so" between a coffee and a cake.

Now that I hope you agree with me that my concept improves security of a
machine significantly, I'd like to ask my initial question again:

How difficult is it to access a file (/sbin/init) from the kernel and
build a checksum of it and decide whether the kernel should now start
that file or not?
Has the kernel itself routines in it to access files that could be
reused, or would that have to be completely new code? 
How difficult would it be to implement code that would do a md5-sum? I
don't have a lot of knowledge of kernel architecture, so I don't know
how much work this would mean. How many hours would a skilled programmer
have to spend on this?

Besides: To those, telling me, that I have to ensure physical security
first: Are you the kind of guys that leave the car unlocked in their
garage, just because the garage itself is locked? Physical security is
very important, but if I can do more, why shouldn't I?

T.