Re: [PATCH 3/7] selinux: Fix user namespace creation after breaking kernel change

["Richard W.M. Jones" <rjones@redhat.com>]

On Wed, Aug 16, 2023 at 08:00:34AM +0200, Stefano Brivio wrote:
> Kernel commit ed5d44d42c95 ("selinux: Implement userns_create hook")
> seems to just introduce a new functionality, but given that SELinux
> implements a form of mandatory access control, introducing the new
> permission breaks any application (shipping with SELinux policies)
> that needs to create user namespaces, such as passt and pasta for
> sandboxing purposes.
> 
> Add the new 'allow' rules. They appear to be backward compatible,
> kernel-wise, and the policy now requires the new 'user_namespace'
> class to build, but that's something distributions already ship.
> 
> Reported-by: Richard W.M. Jones <rjones@redhat.com>
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
> ---
>  contrib/selinux/passt.te | 2 ++
>  contrib/selinux/pasta.te | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/contrib/selinux/passt.te b/contrib/selinux/passt.te
> index 687ae40..5868a41 100644
> --- a/contrib/selinux/passt.te
> +++ b/contrib/selinux/passt.te
> @@ -51,6 +51,7 @@ require {
>  
>  	class capability sys_tty_config;
>  	class cap_userns { setpcap sys_admin sys_ptrace };
> +	class user_namespace create;
>  }
>  
>  type passt_t;
> @@ -90,6 +91,7 @@ allow syslogd_t self:cap_userns sys_ptrace;
>  allow passt_t self:process setcap;
>  allow passt_t self:capability { sys_tty_config setpcap net_bind_service };
>  allow passt_t self:cap_userns { setpcap sys_admin sys_ptrace };
> +allow passt_t self:user_namespace create;
>  
>  allow passt_t proc_net_t:file read;
>  allow passt_t net_conf_t:file { open read };
> diff --git a/contrib/selinux/pasta.te b/contrib/selinux/pasta.te
> index 367d09f..645ccee 100644
> --- a/contrib/selinux/pasta.te
> +++ b/contrib/selinux/pasta.te
> @@ -80,6 +80,7 @@ require {
>  	type init_t;
>  
>  	class cap_userns { setpcap sys_admin sys_ptrace net_bind_service net_admin };
> +	class user_namespace create;
>  }
>  
>  type pasta_t;
> @@ -104,6 +105,7 @@ init_daemon_domain(pasta_t, pasta_exec_t)
>  
>  allow pasta_t self:capability { setpcap net_bind_service sys_tty_config dac_read_search net_admin sys_resource };
>  allow pasta_t self:cap_userns { setpcap sys_admin sys_ptrace net_admin net_bind_service };
> +allow pasta_t self:user_namespace create;
>  
>  allow pasta_t bin_t:file { execute execute_no_trans map };
>  allow pasta_t nsfs_t:file { open read };

Looks sensible:

Reviewed-by: Richard W.M. Jones <rjones@redhat.com>

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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