On 4/8/17 1:48 PM, Johannes Berg wrote:
> @@ -2267,21 +2284,37 @@ int __netlink_dump_start(struct sock *ssk, struct
> sk_buff *skb,
> }
> EXPORT_SYMBOL(__netlink_dump_start);
>
> -void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
> +void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
> + const struct netlink_ext_ack *extack)
> {
> struct sk_buff *skb;
> struct nlmsghdr *rep;
> struct nlmsgerr *errmsg;
> size_t payload = sizeof(*errmsg);
> + size_t acksize = sizeof(*errmsg);
> struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
>
> /* Error messages get the original request appened, unless the user
> - * requests to cap the error message.
> + * requests to cap the error message, and get extra error data if
> + * requested.
> */
> - if (!(nlk->flags & NETLINK_F_CAP_ACK) && err)
> - payload += nlmsg_len(nlh);
> + if (err) {
> + if (!(nlk->flags & NETLINK_F_CAP_ACK))
> + payload += nlmsg_len(nlh);
> + acksize = payload;
> + if (nlk->flags & NETLINK_F_EXT_ACK) {
> + if (extack && extack->_msg)
> + acksize +=
> + nla_total_size(strlen(extack->_msg) +
> 1);
> + if (extack && extack->bad_attr)
> + acksize += nla_total_size(sizeof(u32));
> + if (extack &&
> + (extack->missing_attr || extack->bad_attr))
> + acksize += nla_total_size(sizeof(u16));
If you create a v3, the extack check can by pulled up to the (flags &
NETLINK_F_EXT_ACK) check.
> + }
> + }
>
> - skb = nlmsg_new(payload, GFP_KERNEL);
> + skb = nlmsg_new(acksize, GFP_KERNEL);
> if (!skb) {
> struct sock *sk;
>
> @@ -2300,14 +2333,35 @@ void netlink_ack(struct sk_buff *in_skb, struct
> nlmsghdr *nlh, int err)
> NLMSG_ERROR, payload, 0);
> errmsg = nlmsg_data(rep);
> errmsg->error = err;
> - memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len :
> sizeof(*nlh));
> + memcpy(&errmsg->msg, nlh,
> + !(nlk->flags & NETLINK_F_CAP_ACK) ? nlh->nlmsg_len
> + : sizeof(*nlh));
> +
> + if (err && nlk->flags & NETLINK_F_EXT_ACK) {
> + if (extack && extack->_msg)
> + WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
> + extack->_msg));
> + if (extack && extack->bad_attr &&
> + !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
> + (u8 *)extack->bad_attr >= in_skb->data +
> + in_skb->len))
> + WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
> + (u8 *)extack->bad_attr -
> + in_skb->data));
> + if (extack && extack->missing_attr)
> + WARN_ON(nla_put_u16(skb, NLMSGERR_ATTR_ATTR,
> + extack->missing_attr));
same here
