From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: permission denied: /gnu/store/...guile...
Date: Fri, 22 May 2015 15:33:10 +0200
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	(rekado@elephly.net's message of "Fri, 22 May 2015 16:33:17 +0800")
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To: rekado <rekado@elephly.net>
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rekado <rekado@elephly.net> skribis:

> ---- On Fri, 22 May 2015 05:53:51 +0800 Ludovic Court=C3=A8s<ludo@gnu.org=
> wrote ----=20
>  > Could you try this:=20
>  >=20=20
>  > --8<---------------cut here---------------start------------->8---=20
>  > (chdir "/tmp")=20
>  > (setgroups #())=20
>  > (setgid 30000)=20
>  > (setuid 30001)=20
>  > (pk 'uid/gid (getuid) (getgid))=20
>  > (pk 'euid/egid (geteuid) (getegid))=20
>  > (let loop ((i 3))=20
>  >   (when (< i 1024)=20
>  >     (false-if-exception (close-fdes i))=20
>  >     (loop (+ 1 i))))=20
>  > (execl "/gnu/store/cnqmkmj40jmssnx6fkf9n0n3bqj5x426-guile-2.0.11/bin/g=
uile" "guile"=20
>  >        "-c" "(pk 'running (getuid) (geteuid))")=20
>  > --8<---------------cut here---------------end--------------->8---=20
>  >=20=20
>  > and then as root run:=20
>  >=20=20
>  >   # guile the-above-file.scm=20
>  >=20=20
>  > It should return zero and print:=20
>  >=20=20
>  > --8<---------------cut here---------------start------------->8---=20
>  > ;;; (uid/gid 30001 30000)=20
>  >=20=20
>  > ;;; (euid/egid 30001 30000)=20
>  >=20=20
>  > ;;; (running 30001 30001)=20
>  > --8<---------------cut here---------------end--------------->8---=20
>
> I ran it in a guile REPL (as root) and I got the first two outputs, but a=
n error on (execl ...).  It's an unhelpful message:
>
>     ERROR: In procedure execl:
>     ERROR: In procedure execl: Permission denied

Great, that means that we have a reduced test case now!

Now, could you try to comment out some of the lines before the =E2=80=98exe=
cl=E2=80=99
until you find which one is responsible for that?

IIRC you said that
"/gnu/store/cnqmkmj40jmssnx6fkf9n0n3bqj5x426-guile-2.0.11/bin/guile" is
555, so normally every user on the machine can run it.  It can only
imagine an obscure kernel or file system setting that would somehow
prevent execution, but we=E2=80=99ll see.

Thank you,
Ludo=E2=80=99.