linux-kernel - Re: [PATCH] net: qrtr: Expand control port access to root

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Message-ID: <CAEjxPJ4VA58rtSEEZpxeUZHMjURtrUbZCvV8kAkWwJaoR1YN2A@mail.gmail.com>
Date: Wed, 11 Feb 2026 13:37:44 -0500
From: Stephen Smalley <stephen.smalley.work@...il.com>
To: Manivannan Sadhasivam <mani@...nel.org>
Cc: Jakub Kicinski <kuba@...nel.org>, Paul Moore <paul@...l-moore.com>, 
	Ondrej Mosnacek <omosnace@...hat.com>, selinux@...r.kernel.org, 
	Vishnu Santhosh <vishnu.santhosh@....qualcomm.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	linux-arm-msm@...r.kernel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, bjorn.andersson@....qualcomm.com, 
	chris.lew@....qualcomm.com, 
	Deepak Kumar Singh <deepak.singh@....qualcomm.com>
Subject: Re: [PATCH] net: qrtr: Expand control port access to root

On Wed, Feb 11, 2026 at 12:20 PM Manivannan Sadhasivam <mani@...nel.org> wrote:
>
> + SELinux folks
>
> On Fri, Feb 06, 2026 at 06:36:57PM -0800, Jakub Kicinski wrote:
> > On Thu, 05 Feb 2026 13:51:31 +0530 Vishnu Santhosh wrote:
> > > When qrtr is loaded as module, qrtr-ns runs from SELinux kmod_t
> > > domain. On targets using upstream SELinux policies, this domain
> > > does not receive CAP_NET_ADMIN, which prevents it from binding
> > > control port even though qrtr-ns is a trusted system component.
> > >
> > > Granting kmod_t the CAP_NET_ADMIN capability in policy is possible,
> > > but not desirable, as kmod_t is not expected to perform networking
> > > operations and widening its capability set is discouraged.
> > >
> > > To address this in a contained way within qrtr, extend the control
> > > port permission check to allow binding when either:
> > >
> > >   - the process has CAP_NET_ADMIN, or
> > >   - the process belongs to GLOBAL_ROOT_GID (root-equivalent tasks)
> > >
> > > This permits qrtr-ns to successfully bind its control port in
> > > kmod_t restricted environments without broadening SELinux capability
> > > assignments.
> >
> > This really feels like a one-off hack, but it's far from my area
> > of expertise.. Could you get an ack or review tag from some kernel
> > maintainer working on security, capabilities or permissions?
>
> I'm also not too sure about the problem because it looks like kmod_t has almost
> near root privileges, but cannot do network administration.
>
> Maybe there is a valid reason for that?

On Fedora, kmod_t is an unconfined domain and is allowed all capabilities.
Upstream refpolicy likely hasn't encountered a need for net_admin
during module initialization previously and thus doesn't allow it just
as a matter of least privilege.
Since you referenced kmod_t, I assume this is just for Linux, not
Android (which has an entirely different policy).
I would fix this in policy rather than changing the kernel module code.