netdev - Re: [PATCH v2 net-next 17/23] net/namespace: Update rtnl_net

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Date:   Mon, 8 Oct 2018 15:37:29 +0200
From:   Christian Brauner <christian@...uner.io>
To:     David Ahern <dsahern@...il.com>
Cc:     David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org,
        davem@...emloft.net, jbenc@...hat.com, stephen@...workplumber.org
Subject: Re: [PATCH v2 net-next 17/23] net/namespace: Update rtnl_net_dumpid
 for strict data checking

On Mon, Oct 08, 2018 at 07:28:33AM -0600, David Ahern wrote:
> On 10/8/18 4:54 AM, Christian Brauner wrote:
> > On Sun, Oct 07, 2018 at 08:16:38PM -0700, David Ahern wrote:
> >> From: David Ahern <dsahern@...il.com>
> >>
> >> Update rtnl_net_dumpid for strict data checking. If the flag is set,
> >> the dump request is expected to have an rtgenmsg struct as the header
> >> which has the family as the only element. No data may be appended.
> >>
> >> Signed-off-by: David Ahern <dsahern@...il.com>
> >> ---
> >>  net/core/net_namespace.c | 6 ++++++
> >>  1 file changed, 6 insertions(+)
> >>
> >> diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
> >> index 670c84b1bfc2..fefe72774aeb 100644
> >> --- a/net/core/net_namespace.c
> >> +++ b/net/core/net_namespace.c
> >> @@ -853,6 +853,12 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
> >>  		.s_idx = cb->args[0],
> >>  	};
> >>  
> >> +	if (cb->strict_check &&
> > 
> > Hm, shouldn't this also verify that the passed header is indeed struct
> > rtgenmsg before checking whether there are any attributes?

Thanks!

> 
> rtgenmsg is only a struct with only the family as an element.
> rtnetlink_rcv_msg has already verified that the nl msg header contains
> at least the rtgenmsg struct.
> 
> 
> > 
> >> +	    nlmsg_attrlen(cb->nlh, sizeof(struct rtgenmsg))) {
> >> +			NL_SET_ERR_MSG(cb->extack, "Unknown data in network namespace id dump request");
> >> +			return -EINVAL;
> >> +	}
> >> +
> >>  	spin_lock_bh(&net->nsid_lock);
> >>  	idr_for_each(&net->netns_ids, rtnl_net_dumpid_one, &net_cb);
> >>  	spin_unlock_bh(&net->nsid_lock);
> >> -- 
> >> 2.11.0
> >>
>