Re: [PATCH v2] net: qrtr: Expand control port access to root

[Bjorn Andersson]

On Mon, Feb 16, 2026 at 02:11:45PM +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.
> 

This part looks better now.

> 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.
> 

Where is this discouraged? Who discouraged you do to this? Wasn't this
exactly what Stephen suggested you do in his feedback on v1?

Regards,
Bjorn

> 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.
> 
> Co-developed-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
> Signed-off-by: Deepak Kumar Singh <deepak.singh@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Replaced "qrtr-ns" with "QRTR NS" in the commit message to avoid
>   confusion with the deprecated userspace qrtr-ns tool and the NS
>   implementation inside the QRTR driver.
> - Link to v1: https://lore.kernel.org/r/20260205-qrtr-control-port-access-permission-v1-1-e900039e92d5@xxxxxxxxxxxxxxxx
> ---
>  net/qrtr/af_qrtr.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
> index dab839f61ee93b876021d904ae6b8dca8ed43745..b0e252c16f156c05973988fbdf317a149ad9840d 100644
> --- a/net/qrtr/af_qrtr.c
> +++ b/net/qrtr/af_qrtr.c
> @@ -8,6 +8,7 @@
>  #include <linux/qrtr.h>
>  #include <linux/termios.h>	/* For TIOCINQ/OUTQ */
>  #include <linux/spinlock.h>
> +#include <linux/uidgid.h>
>  #include <linux/wait.h>
>  
>  #include <net/sock.h>
> @@ -738,7 +739,8 @@ static int qrtr_port_assign(struct qrtr_sock *ipc, int *port)
>  	if (!*port) {
>  		rc = xa_alloc(&qrtr_ports, port, ipc, QRTR_EPH_PORT_RANGE,
>  				GFP_KERNEL);
> -	} else if (*port < QRTR_MIN_EPH_SOCKET && !capable(CAP_NET_ADMIN)) {
> +	} else if (*port < QRTR_MIN_EPH_SOCKET && !(capable(CAP_NET_ADMIN) ||
> +						   in_egroup_p(GLOBAL_ROOT_GID))) {
>  		rc = -EACCES;
>  	} else if (*port == QRTR_PORT_CTRL) {
>  		rc = xa_insert(&qrtr_ports, 0, ipc, GFP_KERNEL);
> 
> ---
> base-commit: 0f2acd3148e0ef42bdacbd477f90e8533f96b2ac
> change-id: 20260205-qrtr-control-port-access-permission-bfea19994a58
> 
> Best regards,
> -- 
> Vishnu Santhosh <vishnu.santhosh@xxxxxxxxxxxxxxxx>
>