Re: install.sh is wrong with libc.so

[orc <orc@sibserver.ru>]

Christian Wiese <chris@opensde.net> пишет:
>Hi,
>
>On Wed, 15 Jan 2014 16:42:08 +0800
>orc <orc@sibserver.ru> wrote:
>
>> In case of executable files (which libc.so is), install.sh is wrong
>> and dangerous.
>Just for curiosity, what do you mean in particular to be "dangerous"?

Dangerous in case after performing installation, dynamic linked system becomes unusable: no logins are accepted, no shell can be spawned, even self-boot with init= kernel command line will give you nothing but a kernel panic.
(Of course I should have a static linked busybox, but I even did not expected such a change will occur since 0.9.12)

>> 
>> The sequence of commands of install.sh from 0.9.15:
>> 
>> umask 077
>> cat < lib/libc.so > /lib/libc.so.tmp.pid # /lib/libc.so.tmp.pid is
>> created with mode 600
>> mv -f /lib/libc.so.tmp.pid /lib/libc.so
>> chmod 755 /lib/libc.so # failed with "Permission denied"
>
>I just checked the build logs on my own musl based builds that are
>installing things into a dedicated "sysroot directory" for that build,
>and the install just works fine.
>I think what you are doing is calling 'make install' as a non-root
>user which will obviously fail.
>What I do not really get is why a normal user should be able to install
>a '/lib/lbc.so' anyway. That somehow feels more dangerous to me, but
>maybe I do not get the whole picture here, as you just provided some
>snippets and you are not telling us how your build process actually
>looks like.
>
>I think the info about how you are building would be quite helpful.

I did installation as root user. I also do not run restrictive/hardened kernels.
Sorry I lost log of installation, but after installing 0.9.15' libc.so "make install" refused to run with "Permission denied" error. Rest is simple: no command can be executed, login attempts refused, symptoms like "rm -fr /" was executed, only with "Permission denied".
Only boot from rescue flash drive with prepared initrd showed that /lib/libc.so was half-installed with mode 600.

>
>Cheers,
>Chris