On Mon, Aug 03, 2015 at 09:15:34PM -0600, Jason Gunthorpe wrote:
> On Thu, Jul 09, 2015 at 01:34:26PM -0400, [email protected] wrote:
> > From: Kaike Wan <[email protected]>
> >
> > This patch adds a function to check if listeners for a netlink multicast
> > group are present. It also adds a function to receive netlink response
> > messages.
> >
> > Signed-off-by: Kaike Wan <[email protected]>
> > Signed-off-by: John Fleck <[email protected]>
> > Signed-off-by: Ira Weiny <[email protected]>
> > drivers/infiniband/core/netlink.c | 55
> > +++++++++++++++++++++++++++++++++++++
> > include/rdma/rdma_netlink.h | 7 +++++
> > 2 files changed, 62 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/infiniband/core/netlink.c
> > b/drivers/infiniband/core/netlink.c
> > index 23dd5a5..d47df93 100644
> > +++ b/drivers/infiniband/core/netlink.c
> > @@ -49,6 +49,14 @@ static DEFINE_MUTEX(ibnl_mutex);
> > static struct sock *nls;
> > static LIST_HEAD(client_list);
> >
> > +int ibnl_chk_listeners(unsigned int group)
> > +{
> > + if (netlink_has_listeners(nls, group) == 0)
> > + return -1;
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(ibnl_chk_listeners);
>
> I was thinking about this today, and, where is the security?
>
> What prevents a non-root user from making the above true and/or worse?
We are using Netlink multicast. I believe that netlink_bind only allows root
to bind to multicast.
static int netlink_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
...
/* Only superuser is allowed to listen multicasts */
if (groups) {
if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
return -EPERM;
err = netlink_realloc_groups(sk);
if (err)
return err;
}
...
That said I have not tested the ability to change the timeout settings if one
were to bind without multicast and send a message.
I'll see if I can get some time to test this as Kaike is out on vacation.
Ira
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