guix environment: error: cannot create container: unprivileged user cannot create user namespaces

guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[yasu]

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Hi Guix Development,

I rely on the -C option below to compile ./pre-inst-env  .

guix environment -C guix


(I learned the technique through 
https://gitlab.com/pjotrp/guix-notes/blob/master/INSTALL.org - 
./pre-inst-env just won't compile correctly unless I follow the
instructions on the page)

However, this feature has become unavailable after the
commit  8bc5ca5160db...

~/co/guix (master)$ guix environment -C guix
guix environment: error: cannot create container: unprivileged user
cannot create user namespaces
guix environment: error: please set
/proc/sys/kernel/unprivileged_userns_clone to "1"



The commit details are below:
commit 8bc5ca5160db3d82bd5b6b2b7ed80c96f42bd33e
Author: Paul Garlick <pgarlick@tourbillion-technology.com>
Date:   Thu Dec 3 16:00:18 2020 +0000

    linux-container: Correct test for unprivileged user namespace
support.

    Fixes <https://bugs.gnu.org/31977>;;.
    Reported by Paul Garlick <pgarlick@tourbillion-technology.com>.

    * gnu/build/linux-container.scm (unprivileged-user-namespace-
supported?):
    Return #f when the 'userns-file' does not exist.

diff --git a/gnu/build/linux-container.scm b/gnu/build/linux-
container.scm
index 4a8bed5a9a..3870b50907 100644
--- a/gnu/build/linux-container.scm
+++ b/gnu/build/linux-container.scm
@@ -44,7 +44,7 @@
   (let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
     (if (file-exists? userns-file)
         (eqv? #\1 (call-with-input-file userns-file read-char))
-        #t)))
+        #f)))

 (define (setgroups-supported?)
   "Return #t if the setgroups proc file, introduced in Linux-libre
3.19,



I hope this is a bug that can be fixed.   Otherwise, it looks like I
won't  be able to compile pre-inst-env?

Cheers,
Yasu

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Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Ricardo Wurmus]

Hi Yasu,

> I rely on the -C option below to compile ./pre-inst-env  .
[…]
> I hope this is a bug that can be fixed.   Otherwise, it looks like I
> won't  be able to compile pre-inst-env?

Is “guix environment --pure” not enough?

-- 
Ricardo

Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Yasuaki Kudo]

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Hi Ricardo,

No, it wasn't enough.  (I could be wrong - I am still learning Guix. 😅)  

But I spent a lot of time picking my hair out, trying to figure out why guix edit hello would not find the scm file under my locally checked out guix repository.

When I followed the instructions on the link, the "bulletproof" way, my problem immediately went away.   And I thought it was probably fixed by the  -C option (creating a container) 😄

-Yasu



> On Dec 5, 2020, at 01:04, Ricardo Wurmus <rekado@elephly.net> wrote:
> 
> 
> Hi Yasu,
> 
>> I rely on the -C option below to compile ./pre-inst-env  .
> […]
>> I hope this is a bug that can be fixed.   Otherwise, it looks like I
>> won't  be able to compile pre-inst-env?
> 
> Is “guix environment --pure” not enough?
> 
> -- 
> Ricardo

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Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[zimoun]

Hi,

Thanks for the report.  Are you using Guix System or Guix on foreign?


On Fri, 4 Dec 2020 at 16:53, yasu <yasu@yasuaki.com> wrote:

> I rely on the -C option below to compile ./pre-inst-env .

Aside that nothing, --pure, or -C should work.  The nothing could not,
depending on your setup.  Anyway.


> ~/co/guix (master)$ guix environment -C guix
> guix environment: error: cannot create container: unprivileged user cannot create user namespaces
> guix environment: error: please set /proc/sys/kernel/unprivileged_userns_clone to "1"

Have you tried to do the recommandation?

     please set /proc/sys/kernel/unprivileged_userns_clone to "1"

(as root if you can).  For example, on Debian, I have been doing that
since ever.  And even I have documented it to not forget when I
reinstall. :-)

--8<---------------cut here---------------start------------->8---
    Be careful !
    #+begin_src shell
      # as root
      echo "kernel.unprivileged_userns_clone = 1" > /etc/sysctl.d/local.conf
      sysctl --system
    #+end_src
--8<---------------cut here---------------end--------------->8---


All the best,
simon

Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Pjotr Prins]

On Fri, Dec 04, 2020 at 05:32:08PM +0100, zimoun wrote:
> Have you tried to do the recommandation?
> 
>      please set /proc/sys/kernel/unprivileged_userns_clone to "1"

As root:

echo 1 > /proc/sys/kernel/unprivileged_userns_clone

Yes, it is common on Debian and such.

Pj.

Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Yasuaki Kudo]

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Hi everyone!

I use both:
* Guix System with Linux(non-Libre) Kernel, straight on my desktop PC
* Guix System on Linux subsystem on Windows 10 (https://github.com/giuliano108/guix-packages/blob/master/notes/Guix-on-WSL2.md) on Microsoft Surface Book

and both started to exhibit the same problem with the commitid I reported.

When switch to the commit id immediately before that, the problem goes away.

I tried to set the number as mentioned but I could not figure out how to do it...  Do you know how to do this on Guix System?

Cheers,
Yasu

> On Dec 5, 2020, at 03:55, Pjotr Prins <pjotr.public12@thebird.nl> wrote:
> 
> On Fri, Dec 04, 2020 at 05:32:08PM +0100, zimoun wrote:
>> Have you tried to do the recommandation?
>>    please set /proc/sys/kernel/unprivileged_userns_clone to "1"
> 
> As root:
> 
> echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> 
> Yes, it is common on Debian and such.
> 
> Pj.

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Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[yasu]

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Hi Pj,

Thank you for you reply (and your wonderful Hacking Guide 
https://gitlab.com/pjotrp/guix-notes/blob/master/HACKING.org)!

I tried the command and it didn't work...
I use Guix System (not  a foreign distribution) as described at the
bottom :-)

-Yasu


On Fri, 2020-12-04 at 19:55 +0100, Pjotr Prins wrote:
> On Fri, Dec 04, 2020 at 05:32:08PM +0100, zimoun wrote:
> > Have you tried to do the recommandation?
> > 
> >      please set /proc/sys/kernel/unprivileged_userns_clone to "1"
> 
> As root:
> 
> echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> 
> Yes, it is common on Debian and such.
> 
> Pj.

root@guix ~# echo 1 > /proc/sys/kernel/unprivileged_userns_clone
-bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or
directory

root@guix ~# guix system describe
Generation 5631	Dec 05 2020 09:09:16	(current)
  file name: /var/guix/profiles/system-5631-link
  canonical file name: /gnu/store/qqzk4kvrhxjcia3hcq3xqrcdi36azzz9-
system
  label: GNU with Linux 5.9.12
  bootloader: grub-efi
  root device: label: "my-root"
  kernel: /gnu/store/9a93vpq4aa1c3adiaaa3blwc18r9r7zz-linux-
5.9.12/bzImage
  channels:
    guix:
      repository URL: https://git.savannah.gnu.org/git/guix.git
      branch: master
      commit: 86d635b85035086d21c319f31f628761df5c82e5
    nonguix:
      repository URL: https://gitlab.com/nonguix/nonguix
      branch: master
      commit: b08ea529d4d36468b20ef4aff6dc87b3de0eff70
    guix-chromium:
      repository URL: https://gitlab.com/mbakke/guix-chromium.git
      branch: master
      commit: 2de450b92e5f2624d4f964407686934e22239f7b
  configuration file: /gnu/store/hlma107m2004g6qq00ihm190am5mh9z0-
configuration.scm

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BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[yasu]

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Hi,

I really don't know much about Linux but it looks like the problem I
reported has something to do with Debian?

https://unix.stackexchange.com/questions/303213/how-to-enable-user-namespaces-in-the-kernel-for-unprivileged-unshare

Now, I don't use Debian at all (I use Guix System) and do you think
this is a Bug in Guix (in that this Debian specific word should never
even be mentioned in Guix?)

To summarize this bug again:

The Bug:
The container command no longer works,  after the commit
8bc5ca5160db3d82bd5b6b2b7ed80c96f42bd33e.
guix environment -C


Additional Information:
	Instead of working as it did until the commit, the command now
dies with the following error mesage:
		guix environment: error: cannot create container:
unprivileged user cannot create user namespaces
		guix environment: error: please set
/proc/sys/kernel/unprivileged_userns_clone to "1"

	The message "please set
/proc/sys/kernel/unprivileged_userns_clone to "1",
	seems irrelevant to Guix System users as it may only relate to
Debian users.
	I don't know why this Debian specific message is here in the
first place...	

Disclaimer :-):
	I am assuming this is indeed Debian specific (I tried to
install LinuxLinux (the Guix default) but failed - my AMD graphics card
won't allow me to even boot, unless I use regular Linux.	)

	I scanned for the phrase in LinuxLibre source code but there
was no mention of it:
~/Downloads$ tar -xf linux-libre-5.9.12-gnu.tar.xz
~/Downloads$ cd linux-5.9.12/
~/Downloads/linux-5.9.12$ rg -i unprivileged_userns_clone


	Just FYI: the problem phrase is indeed found in the Debian
Kernel Patch:
~/co/debian$ rg -i unprivileged_userns_clone

	linux/debian/patches/debian/add-sysctl-to-disallow-
unprivileged-CLONE_NEWUSER-by-default.patch
	25:+extern int unprivileged_userns_clone;
	27:+#define unprivileged_userns_clone 0
	36:+    if ((clone_flags & CLONE_NEWUSER) &&
!unprivileged_userns_clone)
	47:+    if ((unshare_flags & CLONE_NEWUSER) &&
!unprivileged_userns_clone) {
	65:+extern int unprivileged_userns_clone;
	77:+            .procname       = "unprivileged_userns_clone",
	78:+            .data           = &unprivileged_userns_clone,
	96:+int unprivileged_userns_clone;





Cheers,
Yasu




commit 8bc5ca5160db3d82bd5b6b2b7ed80c96f42bd33eAuthor: Paul Garlick <
pgarlick@tourbillion-technology.com>Date:   Thu Dec 3 16:00:18 2020
+0000
    linux-container: Correct test for unprivileged user namespace
support.
    Fixes <https://bugs.gnu.org/31977>;.    Reported by Paul Garlick
<pgarlick@tourbillion-technology.com>.
    * gnu/build/linux-container.scm (unprivileged-user-namespace-
supported?):    Return #f when the 'userns-file' does not exist.
diff --git a/gnu/build/linux-container.scm b/gnu/build/linux-
container.scmindex 4a8bed5a9a..3870b50907 100644--- a/gnu/build/linux-
container.scm+++ b/gnu/build/linux-container.scm@@ -44,7 +44,7
@@   (let ((userns-file
"/proc/sys/kernel/unprivileged_userns_clone"))     (if (file-exists?
userns-file)         (eqv? #\1 (call-with-input-file userns-file read-
char))-        #t)))+        #f)))

On Sat, 2020-12-05 at 09:20 +0900, yasu wrote:
> Hi Pj,
> Thank you for you reply (and your wonderful Hacking Guide 
> https://gitlab.com/pjotrp/guix-notes/blob/master/HACKING.org)!
> I tried the command and it didn't work...
> I use Guix System (not  a foreign distribution) as described at the
> bottom 
> -Yasu
> 
> On Fri, 2020-12-04 at 19:55 +0100, Pjotr Prins wrote:
> > On Fri, Dec 04, 2020 at 05:32:08PM +0100, zimoun wrote:
> > > Have you tried to do the recommandation?
> > > 
> > >      please set /proc/sys/kernel/unprivileged_userns_clone to "1"
> > 
> > As root:
> > 
> > echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> > 
> > Yes, it is common on Debian and such.
> > 
> > Pj.
> 
> root@guix ~# echo 1 > /proc/sys/kernel/unprivileged_userns_clone-
> bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or
> directory
> root@guix ~# guix system describeGeneration 5631	Dec 05 2020
> 09:09:16	(current)  file name: /var/guix/profiles/system-5631-
> link  canonical file name:
> /gnu/store/qqzk4kvrhxjcia3hcq3xqrcdi36azzz9-system  label: GNU with
> Linux 5.9.12  bootloader: grub-efi  root device: label: "my-root" 
> kernel: /gnu/store/9a93vpq4aa1c3adiaaa3blwc18r9r7zz-linux-
> 5.9.12/bzImage  channels:    guix:      repository URL: 
> https://git.savannah.gnu.org/git/guix.git      branch:
> master      commit:
> 86d635b85035086d21c319f31f628761df5c82e5    nonguix:      repository
> URL: https://gitlab.com/nonguix/nonguix      branch:
> master      commit: b08ea529d4d36468b20ef4aff6dc87b3de0eff70    guix-
> chromium:      repository URL: 
> https://gitlab.com/mbakke/guix-chromium.git      branch:
> master      commit: 2de450b92e5f2624d4f964407686934e22239f7b 
> configuration file: /gnu/store/hlma107m2004g6qq00ihm190am5mh9z0-
> configuration.scm

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bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Tobias Geerinckx-Rice via Bug reports for GNU Guix]

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yasu 写道：
> Now, I don't use Debian at all (I use Guix System) and do you 
> think
> this is a Bug in Guix (in that this Debian specific word should 
> never
> even be mentioned in Guix?)

It's not Debian-specific.  It is a bug in Guix.

It should try to create a namespace and properly report an error 
iff that fails, not prematurely abort after farting about in 
/proc.

A separate unprivileged-user-namespace-supported? is broken by 
design.  Reverting commit 8bc5ca5 works around this but it wasn't 
to blame.

Kind regards,

T G-R

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Re: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[zimoun]

Hi,

Please try the recommendation. Have you tried it?

  please set /proc/sys/kernel/unprivileged_userns_clone to "1"

As root, you just do:

  echo 1 > /proc/sys/kernel/unprivileged_userns_clone

then “guix environment -C” should work as expected.  To do the trick
automatically with Sheperd, I do not know, but I am sure that the
systemd equivalent 

  echo "kernel.unprivileged_userns_clone = 1" > /etc/sysctl.d/local.conf
  sysctl --system

seems doable with Guix System.


On my system, and I need explanations if it does not work similarly on
yours, I simply do:

--8<---------------cut here---------------start------------->8---
$ guix environment -C --ad-hoc hello -- hello 
guix environment: error: cannot create container: unprivileged user cannot create user namespaces
guix environment: error: please set /proc/sys/kernel/unprivileged_userns_clone to "1"

$ su -
Password:
# echo 1 > /proc/sys/kernel/unprivileged_userns_clone 
# logout

$ guix environment -C --ad-hoc hello -- hello 
Hello, world!
--8<---------------cut here---------------end--------------->8---

Hope that helps,
simon

Re: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[yasu]

Hi Zimoun,

I tried as you suggested but it didn't work...


   root@guix ~# echo "kernel.unprivileged_userns_clone = 1" >
   /etc/sysctl.d/local.conf
   -bash: /etc/sysctl.d/local.conf: No such file or directory
   root@guix ~# sysctl --system
   root@guix ~# logout
   ~$ guix environment -C
   guix environment: error: cannot create container: unprivileged user
   cannot create user namespaces
   guix environment: error: please set
   /proc/sys/kernel/unprivileged_userns_clone to "1"


Now, if this posting were to be belived, I think this term
   kernel.unprivileged_userns_clone

   is specific to Debian Linux, and does not exist outside of that circle.
       
   It disables a bit of "hardening" that Debian patches into their 
   distribution kernel. If you're not running such a kernel, it will
   fail 
   and not do anything, as such a setting doesn't even exist in the
   mainline Linux kernel.

    
   I wonder how this term came in to Guix in the first place?

   -Yasu


   On Sun, 2020-12-06 at 17:56 +0100, zimoun wrote:
   > Hi,
> 
> Please try the recommendation. Have you tried it?
> 
>   please set /proc/sys/kernel/unprivileged_userns_clone to "1"
> 
> As root, you just do:
> 
>   echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> 
> then “guix environment -C” should work as expected.  To do the trick
> automatically with Sheperd, I do not know, but I am sure that the
> systemd equivalent 
> 
>   echo "kernel.unprivileged_userns_clone = 1" >
> /etc/sysctl.d/local.conf
>   sysctl --system
> 
> seems doable with Guix System.
> 
> 
> On my system, and I need explanations if it does not work similarly
> on
> yours, I simply do:
> 
> --8<---------------cut here---------------start------------->8---
> $ guix environment -C --ad-hoc hello -- hello 
> guix environment: error: cannot create container: unprivileged user
> cannot create user namespaces
> guix environment: error: please set
> /proc/sys/kernel/unprivileged_userns_clone to "1"
> 
> $ su -
> Password:
> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone 
> # logout
> 
> $ guix environment -C --ad-hoc hello -- hello 
> Hello, world!
> --8<---------------cut here---------------end--------------->8---
> 
> Hope that helps,
> simon

Re: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[raingloom]

On Mon, 07 Dec 2020 05:51:05 +0900
yasu <yasu@yasuaki.com> wrote:

> Hi Zimoun,
> 
> I tried as you suggested but it didn't work...
> 
> 
>    root@guix ~# echo "kernel.unprivileged_userns_clone = 1" >
>    /etc/sysctl.d/local.conf
>    -bash: /etc/sysctl.d/local.conf: No such file or directory

This could mean you have to create the sysctl.d directory.
Try running this:
```
# mkdir -p /etc/sysctl.d/
# echo "kernel.unprivileged_userns_clone = 1" > /etc/sysctl.d/local.conf
```

Re: bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Jesse Dowell]

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Hi All,

I believe the recommended suggestion is Debian specific is it not?

My kernel supports user namespaces and doesn't expose that file at that
location.

The only way I can work around the issue is to downgrade guix to the commit
on the master branch right before 8bc5ca5160db3d82bd5b6b2b7ed80c96f42bd33e

guix pull --commit=0d5d1bdf911659f60601058e8e1678187b7ba664
--allow-downgrades

Best,
Jesse

On Sun, Dec 6, 2020 at 12:03 PM zimoun <zimon.toutoune@gmail.com> wrote:

> Hi,
>
> Please try the recommendation. Have you tried it?
>
>   please set /proc/sys/kernel/unprivileged_userns_clone to "1"
>
> As root, you just do:
>
>   echo 1 > /proc/sys/kernel/unprivileged_userns_clone
>
> then “guix environment -C” should work as expected.  To do the trick
> automatically with Sheperd, I do not know, but I am sure that the
> systemd equivalent
>
>   echo "kernel.unprivileged_userns_clone = 1" > /etc/sysctl.d/local.conf
>   sysctl --system
>
> seems doable with Guix System.
>
>
> On my system, and I need explanations if it does not work similarly on
> yours, I simply do:
>
> --8<---------------cut here---------------start------------->8---
> $ guix environment -C --ad-hoc hello -- hello
> guix environment: error: cannot create container: unprivileged user cannot
> create user namespaces
> guix environment: error: please set
> /proc/sys/kernel/unprivileged_userns_clone to "1"
>
> $ su -
> Password:
> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> # logout
>
> $ guix environment -C --ad-hoc hello -- hello
> Hello, world!
> --8<---------------cut here---------------end--------------->8---
>
> Hope that helps,
> simon
>
>
>
>

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bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Pierre Neidhardt]

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Hi!

I can reproduce the issue since I 'recondigure'd my Guix System.
I'm on cebfb29abb151ede95696181d2446c63504593d7.

Guix' bug?

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Re: bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Paul Garlick]

Hi Pierre,

Can you try, as root on Guix System:

$ echo 1 > /proc/sys/kernel/unprivileged_userns_clone

If you could report success or failure that would be helpful; the
unprivileged-user-namespace-supported? test in gnu/build/linux-
container.scm should be the same irrespective of the underlying
distribution (Debian, CentOS, Guix System ...).

Best regards,

Paul.

On Mon, 2020-12-07 at 12:57 +0100, Pierre Neidhardt wrote:
> Hi!
> 
> I can reproduce the issue since I 'recondigure'd my Guix System.
> I'm on cebfb29abb151ede95696181d2446c63504593d7.
> 
> Guix' bug?
> 
> 

bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Yasuaki Kudo]

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Just FYI (sorry to interject) , my original email was stripped of html elements?  anyway, I was referring to this link https://security.stackexchange.com/questions/209529/what-does-enabling-kernel-unprivileged-userns-clone-do#comment442083_209533  -Yasu

> On Dec 7, 2020, at 21:31, Paul Garlick <pgarlick@tourbillion-technology.com> wrote:
> 
> Hi Pierre,
> 
> Can you try, as root on Guix System:
> 
> $ echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> 
> If you could report success or failure that would be helpful; the
> unprivileged-user-namespace-supported? test in gnu/build/linux-
> container.scm should be the same irrespective of the underlying
> distribution (Debian, CentOS, Guix System ...).
> 
> Best regards,
> 
> Paul.
> 
>> On Mon, 2020-12-07 at 12:57 +0100, Pierre Neidhardt wrote:
>> Hi!
>> 
>> I can reproduce the issue since I 'recondigure'd my Guix System.
>> I'm on cebfb29abb151ede95696181d2446c63504593d7.
>> 
>> Guix' bug?
>> 
>> 
> 
> 

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Re: bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Pierre Neidhardt]

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Hi Paul,

> Can you try, as root on Guix System:
>
> $ echo 1 > /proc/sys/kernel/unprivileged_userns_clone

# echo 1 > /proc/sys/kernel/unprivileged_userns_clone
-bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or directory

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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bug#45069: Guix System: unprivileged user cannot create user namespaces?

[zimoun]

Hi,

On Mon, 07 Dec 2020 at 18:13, Pierre Neidhardt <mail@ambrevar.xyz> wrote:

>> Can you try, as root on Guix System:
>>
>> $ echo 1 > /proc/sys/kernel/unprivileged_userns_clone
>
> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> -bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or directory

In gnu/build/linux-container.scm, it reads:

--8<---------------cut here---------------start------------->8---
(define (unprivileged-user-namespace-supported?)
  "Return #t if user namespaces can be created by unprivileged users."
  (let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
    (if (file-exists? userns-file)
        (eqv? #\1 (call-with-input-file userns-file read-char))
        #t)))
--8<---------------cut here---------------end--------------->8---

Does it mean that the Linux kernel on Guix System does not support
namespaces by unprivileged users?

Turning #t to #f should work on Guix System and it appears to me a
severe bug if not.  What do I miss?  Please could someone fill my gap? :-)


All the best,
simon

Re: bug#45069: Guix System: unprivileged user cannot create user namespaces?

[Vagrant Cascadian]

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On 2020-12-07, zimoun wrote:
> On Mon, 07 Dec 2020 at 18:13, Pierre Neidhardt <mail@ambrevar.xyz> wrote:
>
>>> Can you try, as root on Guix System:
>>>
>>> $ echo 1 > /proc/sys/kernel/unprivileged_userns_clone
>>
>> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
>> -bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or directory
>
> In gnu/build/linux-container.scm, it reads:
>
> --8<---------------cut here---------------start------------->8---
> (define (unprivileged-user-namespace-supported?)
>   "Return #t if user namespaces can be created by unprivileged users."
>   (let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
>     (if (file-exists? userns-file)
>         (eqv? #\1 (call-with-input-file userns-file read-char))
>         #t)))
> --8<---------------cut here---------------end--------------->8---
>
> Does it mean that the Linux kernel on Guix System does not support
> namespaces by unprivileged users?

> Turning #t to #f should work on Guix System and it appears to me a
> severe bug if not.  What do I miss?  Please could someone fill my gap? :-)

The /proc/sys/kernel_unprivileged_userns_clone file is specific to
Debian and Ubuntu packaged linux kernel; it is a patchset not applied
upstream, as far as I am aware. I'm not sure if other distros support
disabling and enabling this feature using this mechanism.

  https://salsa.debian.org/kernel-team/linux/-/blob/master/debian/patches/debian/add-sysctl-to-disallow-unprivileged-CLONE_NEWUSER-by-default.patch

live well,
  vagrant

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Re: bug#45069: Guix System: unprivileged user cannot create user namespaces?

[zimoun]

Hi Vagrant,

Sorry if I am naive, I am trying to understand and it appears that
pieces are missing in my bag. :-)


On Mon, 07 Dec 2020 at 09:55, Vagrant Cascadian <vagrant@debian.org> wrote:

> The /proc/sys/kernel_unprivileged_userns_clone file is specific to
> Debian and Ubuntu packaged linux kernel; it is a patchset not applied
> upstream, as far as I am aware. I'm not sure if other distros support
> disabling and enabling this feature using this mechanism.

Thanks.  I still do not understand the message from Guix System:

--8<---------------cut here---------------start------------->8---
~/co/guix (master)$ guix environment -C guix
guix environment: error: cannot create container: unprivileged user cannot create user namespaces
guix environment: error: please set /proc/sys/kernel/unprivileged_userns_clone to "1"
--8<---------------cut here---------------end--------------->8---

(see
<https://yhetil.org/guix/e5c86d238ca5174b745b8ea6cb0cb6ad6b20aa5e.camel@yasuaki.com>)

Why does this appear if «set /proc/sys/kernel/unprivileged_userns_clone to "1"» 
does not make sense on Guix System?


Then Tobias answered: (see <https://yhetil.org/guix/87k0tux63a.fsf@nckx>)

        yasu 写道：
        > Now, I don't use Debian at all (I use Guix System) and do you 
        > think
        > this is a Bug in Guix (in that this Debian specific word should 
        > never
        > even be mentioned in Guix?)

        It's not Debian-specific.  It is a bug in Guix.

        It should try to create a namespace and properly report an error 
        iff that fails, not prematurely abort after farting about in 
        /proc.

        A separate unprivileged-user-namespace-supported? is broken by 
        design.  Reverting commit 8bc5ca5 works around this but it wasn't 
        to blame.

so I miss why does a similar patch as,

>   https://salsa.debian.org/kernel-team/linux/-/blob/master/debian/patches/debian/add-sysctl-to-disallow-unprivileged-CLONE_NEWUSER-by-default.patch

is not applied to Guix System?  Is it because a technical or else reason
behind?  Or is it simply because no one takes the time to fix the
problem?



All the best,
simon

Re: bug#45069: Guix System: unprivileged user cannot create user namespaces?

[Bengt Richter]

Hi Vagrant,

On +2020-12-07 09:55:31 -0800, Vagrant Cascadian wrote:
> On 2020-12-07, zimoun wrote:
> > On Mon, 07 Dec 2020 at 18:13, Pierre Neidhardt <mail@ambrevar.xyz> wrote:
> >
> >>> Can you try, as root on Guix System:
> >>>
> >>> $ echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> >>
> >> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> >> -bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or directory
> >
> > In gnu/build/linux-container.scm, it reads:
> >
> > --8<---------------cut here---------------start------------->8---
> > (define (unprivileged-user-namespace-supported?)
> >   "Return #t if user namespaces can be created by unprivileged users."
> >   (let ((userns-file "/proc/sys/kernel/unprivileged_userns_clone"))
> >     (if (file-exists? userns-file)
> >         (eqv? #\1 (call-with-input-file userns-file read-char))
> >         #t)))
> > --8<---------------cut here---------------end--------------->8---
> >
> > Does it mean that the Linux kernel on Guix System does not support
> > namespaces by unprivileged users?
> 
> > Turning #t to #f should work on Guix System and it appears to me a
> > severe bug if not.  What do I miss?  Please could someone fill my gap? :-)
> 
> The /proc/sys/kernel_unprivileged_userns_clone file is specific to
> Debian and Ubuntu packaged linux kernel; it is a patchset not applied
> upstream, as far as I am aware. I'm not sure if other distros support
> disabling and enabling this feature using this mechanism.
> 
>   https://salsa.debian.org/kernel-team/linux/-/blob/master/debian/patches/debian/add-sysctl-to-disallow-unprivileged-CLONE_NEWUSER-by-default.patch
> 
> live well,
    and as virtuously as you are able ... so that spies can't help but admire and reflect :)
>   vagrant

Another data point FYI:

On my pureos system, which is based on debian upstream:
    uname -a
    =-> Linux LionPure 4.19.0-12-amd64 #1 SMP Debian 4.19.152-1 (2020-10-18) x86_64 GNU/Linux
and
    ls -l /proc/sys/kernel/unprivileged_userns_clone
        -rw-r--r-- 1 root root 0 Dec  8 03:03 /proc/sys/kernel/unprivileged_userns_clone

and (noticing that the items appear to be short and ascii lines, hence thereupon  head :)

--8<---------------cut here---------------start------------->8---
od -a -t x1 /proc/sys/kernel/unprivileged_userns_clone 
0000000   0  nl
         30  0a
0000002
head /proc/sys/kernel/unprivileged_userns_clone 
0
--8<---------------cut here---------------end--------------->8---

Not sure this tells you anything useful, but there is also:
--8<---------------cut here---------------start------------->8---
head /proc/sys/user/*
==> /proc/sys/user/max_cgroup_namespaces <==
128163

==> /proc/sys/user/max_inotify_instances <==
128

==> /proc/sys/user/max_inotify_watches <==
65536

==> /proc/sys/user/max_ipc_namespaces <==
128163

==> /proc/sys/user/max_mnt_namespaces <==
128163

==> /proc/sys/user/max_net_namespaces <==
128163

==> /proc/sys/user/max_pid_namespaces <==
128163

==> /proc/sys/user/max_user_namespaces <==
128163

==> /proc/sys/user/max_uts_namespaces <==
128163
--8<---------------cut here---------------end--------------->8---

HTH some way :)
-- 
Regards,
Bengt Richter

bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Paul Garlick]

Hi Pierre,

> # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
> -bash: /proc/sys/kernel/unprivileged_userns_clone: No such file or
> directory

Thanks, that gives us a clue.  So all or part of the path
'/proc/sys/kernel' is missing?

Best regards,

Paul.

Re: bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Pierre Neidhardt]

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Hi again,

Paul Garlick <pgarlick@tourbillion-technology.com> writes:

> Thanks, that gives us a clue.  So all or part of the path
> '/proc/sys/kernel' is missing?

Nope, my /proc/sys/kernel has 121 direct files and directories :/

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[zimoun]

Hi,

On Mon, 07 Dec 2020 at 21:35, Pierre Neidhardt <mail@ambrevar.xyz> wrote:

>> Thanks, that gives us a clue.  So all or part of the path
>> '/proc/sys/kernel' is missing?
>
> Nope, my /proc/sys/kernel has 121 direct files and directories :/

Well, it is expected.  And now all is clear.  Explanations starting
there:

   <http://logs.guix.gnu.org/guix/2020-12-07.log#211011>

Quickly said, the initial code was assuming Debian-like kernel patches
as Vagrant reported and this is not in the linux-libre source code with
a wrong Guix error message.

One bug is still there. :-)


All the best,
simon

Re: bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[Pierre Neidhardt]

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This issue seems to be gone for me with kernel 5.10.x.
I guess it was a kernel bug then.

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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bug#45069: BUG: Re: guix environment: error: cannot create container: unprivileged user cannot create user namespaces

[zimoun]

Hi Pierre,

On Mon, 07 Dec 2020 at 12:57, Pierre Neidhardt <mail@ambrevar.xyz> wrote:

> Guix' bug?

You get something as:

  $ guix environment -C guix
  guix environment: error: cannot create container: unprivileged user cannot create user namespaces
  guix environment: error: please set /proc/sys/kernel/unprivileged_userns_clone to "1"

right?   Have you tried to do the recommendation?

      please set /proc/sys/kernel/unprivileged_userns_clone to "1"

in other words, as root:

  # echo 1 > /proc/sys/kernel/unprivileged_userns_clone
  $ guix environment -C --ad-hoc hello -- hello

and report.


Thanks,
simon