netdev - Re: [PATCH net-next 11/20] rtnetlink: Update inet6_dump

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Message-ID: <20181005174827.iudgcjd3r2cc7xqu@brauner.io>
Date:   Fri, 5 Oct 2018 19:48:28 +0200
From:   Christian Brauner <christian@...uner.io>
To:     David Ahern <dsahern@...nel.org>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, jbenc@...hat.com,
        stephen@...workplumber.org, David Ahern <dsahern@...il.com>
Subject: Re: [PATCH net-next 11/20] rtnetlink: Update inet6_dump_ifinfo for
 strict data checking

On Thu, Oct 04, 2018 at 02:33:46PM -0700, David Ahern wrote:
> From: David Ahern <dsahern@...il.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@...il.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. :)

> ---
>  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
>