[Devel] Re: [PATCH 2/4] C/R: Basic support for network namespaces and devices (v3)

[Louis Rilling]

Hi Dan,

On 10/02/10  9:55 -0800, Dan Smith wrote:
> Guilt dropped the new checkpoint_dev.c file when I switched to the
> newer branch.  Sorry about that.  Updated patch included below.
> 

[...]

> diff --git a/net/checkpoint_dev.c b/net/checkpoint_dev.c
> new file mode 100644
> index 0000000..0dddd15
> --- /dev/null
> +++ b/net/checkpoint_dev.c

[...]

> +
> +static struct nlmsghdr *rtnl_get_response(struct socket *rtnl,
> +					  struct sk_buff **skb)
> +{
> +	int ret;
> +	long timeo = MAX_SCHEDULE_TIMEOUT;
> +	struct nlmsghdr *nlh;
> +
> +	ret = sk_wait_data(rtnl->sk, &timeo);
> +	if (!ret)
> +		return ERR_PTR(-EPIPE);
> +
> +	*skb = skb_dequeue(&rtnl->sk->sk_receive_queue);
> +	if (!*skb)
> +		return ERR_PTR(-EPIPE);
> +
> +	ret = -EINVAL;
> +	nlh = nlmsg_hdr(*skb);
> +	if (!nlh)
> +		goto err;
> +
> +	if (nlh->nlmsg_type == NLMSG_ERROR) {
> +		struct nlmsgerr *errmsg = nlmsg_data(nlh);
> +		ret = errmsg->error;
> +		goto err;
> +	}
> +
> +	return nlh;
> + err:
> +	kfree_skb(*skb);
> +	*skb = NULL;
> +
> +	return ERR_PTR(ret);
> +}
> +

[...]

> +
> +static struct sk_buff *new_link_message(char *this_name, char *peer_name)
> +{
> +	int ret = -ENOMEM;
> +	int flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK;
> +	struct nlmsghdr *nlh;
> +	struct sk_buff *skb;
> +	struct ifinfomsg *ifm;
> +	struct nlattr *linkinfo;
> +
> +	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> +	if (!skb)
> +		goto out;
> +
> +	nlh = nlmsg_put(skb, 0, 0, RTM_NEWLINK, sizeof(*ifm), flags);
> +	if (!nlh)
> +		goto out;
> +
> +	ifm = nlmsg_data(nlh);
> +	memset(ifm, 0, sizeof(*ifm));
> +
> +	ret = nla_put_string(skb, IFLA_IFNAME, this_name);
> +	if (ret)
> +		goto out;
> +
> +	ret = -ENOMEM;
> +
> +	linkinfo = nla_nest_start(skb, IFLA_LINKINFO);
> +	if (!linkinfo)
> +		goto out;
> +
> +	if (nla_put_string(skb, IFLA_INFO_KIND, "veth") < 0)
> +		goto out;
> +
> +	ret = veth_peer_data(skb, peer_name);
> +	if (ret < 0)
> +		goto out;
> +
> +	nla_nest_end(skb, linkinfo);
> +	nlmsg_end(skb, nlh);
> +
> + out:
> +	if (ret < 0) {
> +		kfree(skb);

I'm definitely not a network expert, but this kfree(skb) should probably be
replaced by kfree_skb(skb).

> +		skb = ERR_PTR(ret);
> +	}
> +
> +	return skb;
> +}
> +
> +static struct net_device *new_veth_pair(char *this_name, char *peer_name)
> +{
> +	int ret = -ENOMEM;
> +	struct socket *rtnl;
> +	struct sk_buff *skb = NULL;
> +	struct nlmsghdr *nlh;
> +	struct msghdr msg;
> +	struct kvec kvec;
> +
> +	skb = new_link_message(this_name, peer_name);
> +	if (IS_ERR(skb)) {
> +		ret = PTR_ERR(skb);
> +		ckpt_debug("failed to create new link message: %i\n", ret);
> +		skb = NULL;
> +		goto out;
> +	}
> +
> +	memset(&msg, 0, sizeof(msg));
> +	kvec.iov_len = skb->len;
> +	kvec.iov_base = skb->head;
> +
> +	rtnl = rtnl_open();
> +	if (IS_ERR(rtnl)) {
> +		ret = PTR_ERR(rtnl);
> +		ckpt_debug("Unable to open rtnetlink socket: %i\n", ret);
> +		goto out_noclose;
> +	}
> +
> +	ret = kernel_sendmsg(rtnl, &msg, &kvec, 1, kvec.iov_len);
> +	if (ret < 0)
> +		goto out;
> +	else if (ret != skb->len) {
> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	/* Free the send skb to make room for the receive skb */
> +	kfree(skb);

Ditto.

> +
> +	nlh = rtnl_get_response(rtnl, &skb);
> +	if (IS_ERR(nlh)) {
> +		ret = PTR_ERR(nlh);
> +		ckpt_debug("RTNETLINK said: %i\n", ret);
> +	}
> + out:
> +	rtnl_close(rtnl);
> + out_noclose:
> +	kfree(skb);

Ditto.

Thanks,

Louis

[...]

-- 
Dr Louis Rilling			Kerlabs
Skype: louis.rilling			Batiment Germanium
Phone: (+33|0) 6 80 89 08 23		80 avenue des Buttes de Coesmes
http://www.kerlabs.com/			35700 Rennes
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