Subject: Re: [PATCH v2 net-next 17/23] net/namespace: Update rtnl_net_dumpid for strict data checking

From: David Ahern <[email-masked]>
Date: Mon, 8 Oct 2018 07:28:33 -0600

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 <[email-masked]>
>>
>> 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 <[email-masked]>
>> ---
>>  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?

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
>>