Re: [PATCH net-next 11/20] rtnetlink: Update inet6_dump_ifinfo for strict data checking

[Christian Brauner <christian@brauner.io>]

On Fri, Oct 05, 2018 at 07:48:27PM +0200, Christian Brauner wrote:
> On Thu, Oct 04, 2018 at 02:33:46PM -0700, David Ahern wrote:
> > From: David Ahern <dsahern@gmail.com>
> > 
> > Update inet6_dump_ifinfo for strict data checking. If the flag is
> > set, the dump request is expected to have an ifinfomsg struct as
> > the header. All elements of the struct are expected to be 0 and no
> > attributes can be appended.
> > 
> > Signed-off-by: David Ahern <dsahern@gmail.com>
> 
> This is on top of current net-next? Are your patches ensuring that
> ipv6 addr requests don't generate log messages anymore when a wrong
> header is passed but the strict socket option is not passed? The context
> here doesn't seem to indicate that. :)

Nm, 9/10 takes care of that. Thanks! :)

> 
> > ---
> >  net/ipv6/addrconf.c | 35 +++++++++++++++++++++++++++++++++++
> >  1 file changed, 35 insertions(+)
> > 
> > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> > index f749a3ad721a..693199a29426 100644
> > --- a/net/ipv6/addrconf.c
> > +++ b/net/ipv6/addrconf.c
> > @@ -5628,6 +5628,31 @@ static int inet6_fill_ifinfo(struct sk_buff *skb, struct inet6_dev *idev,
> >  	return -EMSGSIZE;
> >  }
> >  
> > +static int inet6_valid_dump_ifinfo(const struct nlmsghdr *nlh,
> > +				   struct netlink_ext_ack *extack)
> > +{
> > +	struct ifinfomsg *ifm;
> > +
> > +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) {
> > +		NL_SET_ERR_MSG(extack, "Invalid header");
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (nlh->nlmsg_len > nlmsg_msg_size(sizeof(*ifm))) {
> > +		NL_SET_ERR_MSG(extack, "Invalid data after header");
> > +		return -EINVAL;
> > +	}
> > +
> > +	ifm = nlmsg_data(nlh);
> > +	if (ifm->__ifi_pad || ifm->ifi_type || ifm->ifi_flags ||
> > +	    ifm->ifi_change || ifm->ifi_index) {
> > +		NL_SET_ERR_MSG(extack, "Invalid values in header for dump request");
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
> >  {
> >  	struct net *net = sock_net(skb->sk);
> > @@ -5637,6 +5662,16 @@ static int inet6_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb)
> >  	struct inet6_dev *idev;
> >  	struct hlist_head *head;
> >  
> > +	/* only requests using strict checking can pass data to
> > +	 * influence the dump
> > +	 */
> > +	if (cb->strict_check) {
> > +		int err = inet6_valid_dump_ifinfo(cb->nlh, cb->extack);
> > +
> > +		if (err)
> > +			return err;
> > +	}
> > +
> >  	s_h = cb->args[0];
> >  	s_idx = cb->args[1];
> >  
> > -- 
> > 2.11.0
> >