On Sun, Oct 07, 2018 at 08:16:31PM -0700, David Ahern wrote:
> From: David Ahern <dsah...@gmail.com>
>
> Update rtnl_bridge_getlink for strict data checking. If the flag is set,
> the dump request is expected to have an ifinfomsg 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 IFLA_EXT_MASK
> attribute is supported.
>
> Signed-off-by: David Ahern <dsah...@gmail.com>
Acked-by: Christian Brauner <christ...@brauner.io>
> ---
> net/core/rtnetlink.c | 70
> ++++++++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 57 insertions(+), 13 deletions(-)
>
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 12fd52105005..e38e1f178611 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -4021,28 +4021,72 @@ int ndo_dflt_bridge_getlink(struct sk_buff *skb, u32
> pid, u32 seq,
> }
> EXPORT_SYMBOL_GPL(ndo_dflt_bridge_getlink);
>
> +static int valid_bridge_getlink_req(const struct nlmsghdr *nlh,
> + bool strict_check, u32 *filter_mask,
> + struct netlink_ext_ack *extack)
> +{
> + struct nlattr *tb[IFLA_MAX+1];
> + int err, i;
> +
> + if (strict_check) {
> + struct ifinfomsg *ifm;
> +
> + if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) {
> + NL_SET_ERR_MSG(extack, "Invalid header for bridge link
> dump");
> + 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
> bridge link dump request");
> + return -EINVAL;
> + }
> +
> + err = nlmsg_parse_strict(nlh, sizeof(struct ifinfomsg), tb,
> + IFLA_MAX, ifla_policy, extack);
> + } else {
> + err = nlmsg_parse(nlh, sizeof(struct ifinfomsg), tb,
> + IFLA_MAX, ifla_policy, extack);
> + }
> + if (err < 0)
> + return err;
> +
> + /* new attributes should only be added with strict checking */
> + for (i = 0; i <= IFLA_MAX; ++i) {
> + if (!tb[i])
> + continue;
> +
> + switch (i) {
> + case IFLA_EXT_MASK:
> + *filter_mask = nla_get_u32(tb[i]);
> + break;
> + default:
> + if (strict_check) {
> + NL_SET_ERR_MSG(extack, "Unsupported attribute
> in bridge link dump request");
> + return -EINVAL;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> static int rtnl_bridge_getlink(struct sk_buff *skb, struct netlink_callback
> *cb)
> {
> + const struct nlmsghdr *nlh = cb->nlh;
> struct net *net = sock_net(skb->sk);
> struct net_device *dev;
> int idx = 0;
> u32 portid = NETLINK_CB(cb->skb).portid;
> - u32 seq = cb->nlh->nlmsg_seq;
> + u32 seq = nlh->nlmsg_seq;
> u32 filter_mask = 0;
> int err;
>
> - if (nlmsg_len(cb->nlh) > sizeof(struct ifinfomsg)) {
> - struct nlattr *extfilt;
> -
> - extfilt = nlmsg_find_attr(cb->nlh, sizeof(struct ifinfomsg),
> - IFLA_EXT_MASK);
> - if (extfilt) {
> - if (nla_len(extfilt) < sizeof(filter_mask))
> - return -EINVAL;
> -
> - filter_mask = nla_get_u32(extfilt);
> - }
> - }
> + err = valid_bridge_getlink_req(nlh, cb->strict_check, &filter_mask,
> + cb->extack);
> + if (err < 0 && cb->strict_check)
> + return err;
>
> rcu_read_lock();
> for_each_netdev_rcu(net, dev) {
> --
> 2.11.0
>
