linux-kernel - Re: [PATCH] builddeb: fix file permissions before packaging

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Date:	Thu, 7 Jul 2016 16:56:49 +0200
From:	Henning Schild <henning.schild@...mens.com>
To:	"Michal Marek" <mmarek@...e.com>
Cc:	<linux-kernel@...r.kernel.org>, <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH] builddeb: fix file permissions before packaging

On Thu, 7 Jul 2016 16:50:37 +0200
Henning Schild <henning.schild@...mens.com> wrote:

> Builddep is not very explicit about file permissions. Actually the
> file permissions in the package are largely influenced by the umask
> of the user cloning the git and building the package. If that umask
> does not set go+r the resulting linux-headers package will prevent
> non-root users from building out-of-tree modules. And that is
> probably just one unexpected effect.

This problem was found in a CI-system (buildbot) running with a 0077
umask and building packages. These packages contained headers with 600
instead of 644 and users could not build there modules anymore.

Reproduce with "umask 0077", "git clone ..", ... "make deb-pkg"

> Being a packaging/install tool builddep should make sure the file
> permissions are set correctly and not just derived from a value that
> is never checked.

If that patch is not accepted i strongly suggest at least asserting
that the headers in linux-headers.deb have 644. I am not sure which is
the better solution, but builddeb should not produce such broken
packages.

> This patch derives the "r" and "x" bits for all files from the file
> owner, all directories in the package will be 755.
> 
> Signed-off-by: Henning Schild <henning.schild@...mens.com>
> ---
>  scripts/package/builddeb | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/scripts/package/builddeb b/scripts/package/builddeb
> index 86e56fe..615e0ed 100755
> --- a/scripts/package/builddeb
> +++ b/scripts/package/builddeb
> @@ -26,6 +26,11 @@ create_package() {
>  	# Fix ownership and permissions
>  	chown -R root:root "$pdir"
>  	chmod -R go-w "$pdir"
> +	# in case we are in a restrictive umask environment like 0077
> +	# set permissions for dirs and derive "go"-"rx" permissions
> from "u"
> +	find $pdir -type d -exec chmod 0755 {} +
> +	find $pdir -type f -perm -u+r -exec chmod go+r {} +
> +	find $pdir -type f -perm -u+x -exec chmod go+x {} +
>  
>  	# Create the package
>  	dpkg-gencontrol $forcearch -Vkernel:debarch="${debarch}"
> -p$pname -P"$pdir"