Re: [PATCH 1/3] init/main.c: introduce function ramdisk_exec_exist()

[Menglong Dong]

On Tue, May 25, 2021 at 9:02 AM Josh Triplett <josh@xxxxxxxxxxxxxxxx> wrote:
>
......
>
> As far as I can tell, this will break if the user wants to use
> ".mybinary" or ".mydir/mybinary" as the name of their init program.
>
> For that matter, it would break "...prog" or "...somedir/prog", which
> would be strange but not something the kernel should prevent.
>

Wow, seems I didn't give enough thought to it.

> I don't think this code should be attempting to recreate
> relative-to-absolute filename resolution.

Trust me, I don't want to do it either. However, I need to check if
ramdisk_execute_command exist before chroot while the cpio is unpacked
to '/root'.

Maybe I can check it after chroot, but I need to chroot back if it not
exist. Can I chroot back in a nice way?

I tried to move the mount on '/root' to '/' before I do this check in
absolute path, but seems '/' is special, the lookup of '/init' never
follow the mount on '/' and it can't be found. However, if I lookup
'/../init', it can be found!

Is there any one have a good idea? Or I have to dig into the code
of 'kern_path()' and figure out the reason.

Thanks!
Menglong Dong