Re: [ptxdist] rootfs: /dev/null creation fails with 'Operation not permitted'

["Koch, Alexander" <akoch@initse.com>]

Am Thu, 30 Sep 2021 12:00:50 +0000
schrieb "Koch, Alexander" <akoch@initse.com>:

> Am Thu, 30 Sep 2021 12:44:34 +0200
> schrieb Michael Olbrich <m.olbrich@pengutronix.de>:
> 
> > On Thu, Sep 30, 2021 at 07:59:45AM +0000, Koch, Alexander wrote:  
> > > Hi #PTXdist,
> > > 
> > > I'm currently facing the issue that all my PTXdist builds fail in 
> > > 'rootfs.make' during the creation of the /dev/null device node:
> > > 
> > > 
> > > --------------------------------------( ... )--
> > > 
> > > install directory:
> > >    dir=/dev
> > >    owner=0
> > >    group=0
> > >    permissions=0755
> > > 
> > > install device node:
> > >    owner=0
> > >    group=0
> > >    permissions=0666
> > >    type=c
> > >    major=1
> > >    minor=3
> > >    name=/dev/null
> > > 
> > > mknod:
> > > /mnt/work/ptxdist/platform-pm3/packages/rootfs.tmp/dev/null:
> > > Operation not permitted Error: install_node failed!
> > > 
> > > xpkg_finish: failed.
> > > 
> > > make: *** [/usr/lib/ptxdist-2020.01.0/rules/rootfs.make:93: 
> > > /mnt/work/ptxdist/platform-pm3/state/rootfs.targetinstall] Error 1
> > > 
> > > ------------------------------------------------
> > > 
> > > 
> > > As you can see I'm using ptxdist-2020.01.0 for this but I've taken
> > > a look at the current release code base and can't see any
> > > substantial changes to the device node creation part in
> > > `install_node()`. So I doubt it's an issue of that particular
> > > version.
> > > 
> > > I've also checked I'm not using any fancy mount options for the 
> > > filesystem I'm building on (btrfs) and I do not use
> > > SELinux/AppArmor or any other restriction framework.
> > > 
> > > Builds used to work fine for years, so I'm running out of clues
> > > what could be causing this issue.
> > > 
> > > 
> > > Does anybody have an idea what I could check?    
> > 
> > mknod is run with fakeroot specifically to avoid permissions errors
> > like this. So either fakeroot is not working properly or there is
> > some bad interaction with btrfs.
> > Can you run mknod with platform-*/sysroot-host/bin/fakeroot to see
> > if it works manually?
> > Try to create a device file on the same filesystem but also on a
> > tmpfs. Do you get the same errors?  
> 
> Thanks for the hint with `fakeroot`.
> 
> It seems that one is not working at all, I get the exact same
> permission error as when running without it.
> 
> And I do even get it on a fresh tmpfs:
> 
>   $ mkdir /tmp/test-fs
>   $ sudo mount -t tmpfs -o dev none /tmp/test-fs
>   $ ./platform-pm3/sysroot-host/bin/fakeroot -- mknod \
>       /tmp/test-fs/null c 1 3
>   mknod: /tmp/test-fs/null: Operation not permitted
> 
> 
> Maybe I should backport the latest 'fakeroot' package into my PTXdist
> project?
> 

Confirmed: upgrading 'host-fakeroot' to the latest package version
1.25.3 fixes the issue.

Upstream (as well as Arch) has 1.26 but it seems that's not a trivial
upgrade so I'll stick with 1.25.3.

Thanks again for the hint!


Best regards,

Alex
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