On Sun, Oct 07, 2018 at 08:16:28PM -0700, David Ahern wrote:
> From: David Ahern <dsah...@gmail.com>
>
> Update inet_dump_ifaddr 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 supported 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 support for other fields
> (e.g., honor ifa_index and only return data for the given device index).
>
> Signed-off-by: David Ahern <dsah...@gmail.com>
Thanks, with the *_strict() it looks way cleaner now.
Acked-by: Christian Brauner <christ...@brauner.io>
> ---
> net/ipv4/devinet.c | 72
> +++++++++++++++++++++++++++++++++++++++++++++---------
> 1 file changed, 61 insertions(+), 11 deletions(-)
>
> diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
> index ab2b11df5ea4..6f2bbd04e950 100644
> --- a/net/ipv4/devinet.c
> +++ b/net/ipv4/devinet.c
> @@ -1660,17 +1660,70 @@ static int inet_fill_ifaddr(struct sk_buff *skb,
> struct in_ifaddr *ifa,
> return -EMSGSIZE;
> }
>
> +static int inet_valid_dump_ifaddr_req(const struct nlmsghdr *nlh,
> + struct inet_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(extack, "ipv4: 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(extack, "ipv4: Invalid values in header for
> address dump request");
> + return -EINVAL;
> + }
> + if (ifm->ifa_index) {
> + NL_SET_ERR_MSG(extack, "ipv4: Filter by device index not
> supported for address dump");
> + return -EINVAL;
> + }
> +
> + err = nlmsg_parse_strict(nlh, sizeof(*ifm), tb, IFA_MAX,
> + ifa_ipv4_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(extack, "ipv4: Invalid target
> network namespace id");
> + return PTR_ERR(net);
> + }
> + *tgt_net = net;
> + } else {
> + NL_SET_ERR_MSG(extack, "ipv4: Unsupported attribute in
> dump request");
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
> +
> static int inet_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
> {
> + const struct nlmsghdr *nlh = cb->nlh;
> struct inet_fill_args fillargs = {
> .portid = NETLINK_CB(cb->skb).portid,
> - .seq = cb->nlh->nlmsg_seq,
> + .seq = nlh->nlmsg_seq,
> .event = RTM_NEWADDR,
> .flags = NLM_F_MULTI,
> .netnsid = -1,
> };
> struct net *net = sock_net(skb->sk);
> - struct nlattr *tb[IFA_MAX+1];
> struct net *tgt_net = net;
> int h, s_h;
> int idx, s_idx;
> @@ -1684,16 +1737,13 @@ static int inet_dump_ifaddr(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_ipv4_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 = inet_valid_dump_ifaddr_req(nlh, &fillargs, &tgt_net,
> + skb->sk, cb->extack);
> + if (err < 0)
> + return err;
> }
>
> for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) {
> --
> 2.11.0
>
