netdev - Re: [PATCH v2 net-next 08/23] net/ipv6: Update inet6_dump

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Date:   Mon, 8 Oct 2018 12:10:42 +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 v2 net-next 08/23] net/ipv6: Update inet6_dump_addr for
 strict data checking

On Sun, Oct 07, 2018 at 08:16:29PM -0700, David Ahern wrote:
> From: David Ahern <dsahern@...il.com>
> 
> Update inet6_dump_addr for strict data checking. If the flag is set, the
> dump request is expected to have an ifaddrmsg struct as the header
> potentially followed by one or more attributes. Any data passed in the
> header or as an attribute is taken as a request to influence the data
> returned. Only values suppored by the dump handler are allowed to be
> non-0 or set in the request. At the moment only the IFA_TARGET_NETNSID
> attribute is supported. Follow on patches can add support for other fields
> (e.g., honor ifa_index and only return data for the given device index).
> 
> Signed-off-by: David Ahern <dsahern@...il.com>

Same as ipv4, looks way cleaner with the new *_strict() helper! :)

Acked-by: Christian Brauner <christian@...uner.io>

> ---
>  net/ipv6/addrconf.c | 69 +++++++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 59 insertions(+), 10 deletions(-)
> 
> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
> index afa279170ba5..095d3f56f0a9 100644
> --- a/net/ipv6/addrconf.c
> +++ b/net/ipv6/addrconf.c
> @@ -4998,9 +4998,62 @@ static int in6_dump_addrs(struct inet6_dev *idev, struct sk_buff *skb,
>  	return err;
>  }
>  
> +static int inet6_valid_dump_ifaddr_req(const struct nlmsghdr *nlh,
> +				       struct inet6_fill_args *fillargs,
> +				       struct net **tgt_net, struct sock *sk,
> +				       struct netlink_ext_ack *extack)
> +{
> +	struct nlattr *tb[IFA_MAX+1];
> +	struct ifaddrmsg *ifm;
> +	int err, i;
> +
> +	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) {
> +		NL_SET_ERR_MSG_MOD(extack, "Invalid header for address dump request");
> +		return -EINVAL;
> +	}
> +
> +	ifm = nlmsg_data(nlh);
> +	if (ifm->ifa_prefixlen || ifm->ifa_flags || ifm->ifa_scope) {
> +		NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for address dump request");
> +		return -EINVAL;
> +	}
> +	if (ifm->ifa_index) {
> +		NL_SET_ERR_MSG_MOD(extack, "Filter by device index not supported for address dump");
> +		return -EINVAL;
> +	}
> +
> +	err = nlmsg_parse_strict(nlh, sizeof(*ifm), tb, IFA_MAX,
> +				 ifa_ipv6_policy, extack);
> +	if (err < 0)
> +		return err;
> +
> +	for (i = 0; i <= IFA_MAX; ++i) {
> +		if (!tb[i])
> +			continue;
> +
> +		if (i == IFA_TARGET_NETNSID) {
> +			struct net *net;
> +
> +			fillargs->netnsid = nla_get_s32(tb[i]);
> +			net = rtnl_get_net_ns_capable(sk, fillargs->netnsid);
> +			if (IS_ERR(net)) {
> +				NL_SET_ERR_MSG_MOD(extack, "Invalid target network namespace id");
> +				return PTR_ERR(net);
> +			}
> +			*tgt_net = net;
> +		} else {
> +			NL_SET_ERR_MSG_MOD(extack, "Unsupported attribute in dump request");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
>  			   enum addr_type_t type)
>  {
> +	const struct nlmsghdr *nlh = cb->nlh;
>  	struct inet6_fill_args fillargs = {
>  		.portid = NETLINK_CB(cb->skb).portid,
>  		.seq = cb->nlh->nlmsg_seq,
> @@ -5009,7 +5062,6 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
>  		.type = type,
>  	};
>  	struct net *net = sock_net(skb->sk);
> -	struct nlattr *tb[IFA_MAX+1];
>  	struct net *tgt_net = net;
>  	int h, s_h;
>  	int idx, ip_idx;
> @@ -5022,16 +5074,13 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb,
>  	s_idx = idx = cb->args[1];
>  	s_ip_idx = ip_idx = cb->args[2];
>  
> -	if (nlmsg_parse(cb->nlh, sizeof(struct ifaddrmsg), tb, IFA_MAX,
> -			ifa_ipv6_policy, cb->extack) >= 0) {
> -		if (tb[IFA_TARGET_NETNSID]) {
> -			fillargs.netnsid = nla_get_s32(tb[IFA_TARGET_NETNSID]);
> +	if (cb->strict_check) {
> +		int err;
>  
> -			tgt_net = rtnl_get_net_ns_capable(skb->sk,
> -							  fillargs.netnsid);
> -			if (IS_ERR(tgt_net))
> -				return PTR_ERR(tgt_net);
> -		}
> +		err = inet6_valid_dump_ifaddr_req(nlh, &fillargs, &tgt_net,
> +						  skb->sk, cb->extack);
> +		if (err < 0)
> +			return err;
>  	}
>  
>  	rcu_read_lock();
> -- 
> 2.11.0
>