[PATCH 04/16] gtp: select netns based on NL attribute

[Pablo Neira Ayuso]

On Mon, Nov 16, 2015 at 04:06:45PM +0100, Andreas Schultz wrote:
> This permits a split namespace setup where the GTP transport
> sockets are in one namespace the gtp tunnel interface is in
> another namespace.
> 
> The target namespece is selected by the new GTPA_NET_NS_FD NL
> attributes. It fall back to the netns of the GTP-U sockets if
> the NL attr is not present.
> 
> Signed-off-by: Andreas Schultz <aschultz at tpip.net>
> ---
>  gtp.c    | 41 +++++++++++++++++++++++++++++++++++++----
>  gtp_nl.h |  1 +
>  2 files changed, 38 insertions(+), 4 deletions(-)
> 
> diff --git a/gtp.c b/gtp.c
> index 7c61e61..11f8fad 100644
> --- a/gtp.c
> +++ b/gtp.c
> @@ -330,6 +330,8 @@ static int gtp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
>  	if (!gti)
>  		goto user;
>  
> +	netdev_dbg(gti->dev, "encap_recv %p\n", sk);
> +
>  	switch (udp_sk(sk)->encap_type) {
>  	case UDP_ENCAP_GTP0:
>  		netdev_dbg(gti->dev, "received GTP0 packet\n");
> @@ -738,7 +740,7 @@ static int gtp_encap_enable(struct net_device *dev, struct gtp_instance *gti,
>  static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  			struct nlattr *tb[], struct nlattr *data[])
>  {
> -	struct gtp_net *gn = net_generic(src_net, gtp_net_id);
> +	struct gtp_net *gn;
>  	struct net_device *real_dev;
>  	struct gtp_instance *gti;
>  	int hashsize, err, fd0, fd1;
> @@ -778,6 +780,7 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
>  	if (err < 0)
>  		goto err1;
>  
> +	gn = net_generic(dev_net(dev), gtp_net_id);
>  	list_add_rcu(&gti->list, &gn->gtp_instance_list);
>  
>  	netdev_dbg(dev, "registered new interface\n");
> @@ -845,6 +848,19 @@ static struct rtnl_link_ops gtp_link_ops __read_mostly = {
>  	.fill_info	= gtp_fill_info,
>  };
>  
> +static struct net *gtp_genl_get_net(struct net *src_net, struct nlattr *tb[])
> +{
> +	struct net *net;
> +	/* Examine the link attributes and figure out which
> +	 * network namespace we are talking about.
> +	 */
> +	if (tb[GTPA_NET_NS_FD])
> +		net = get_net_ns_by_fd(nla_get_u32(tb[GTPA_NET_NS_FD]));

I can see this returns ERR_PTR() so...

> +	else
> +		net = get_net(src_net);
> +	return net;
> +}
> +
>  static int gtp_hashtable_new(struct gtp_instance *gti, int hsize)
>  {
>  	int i;
> @@ -893,6 +909,8 @@ static int gtp_encap_enable(struct net_device *dev, struct gtp_instance *gti,
>  	struct socket *sock0, *sock1u;
>  	struct sock *sk;
>  
> +	netdev_dbg(dev, "enable gtp on %d, %d\n", fd_gtp0, fd_gtp1);
> +
>  	sock0 = sockfd_lookup(fd_gtp0, &err);
>  	if (sock0 == NULL) {
>  		netdev_dbg(dev, "socket fd=%d not found (gtp0)\n", fd_gtp0);
> @@ -918,6 +936,8 @@ static int gtp_encap_enable(struct net_device *dev, struct gtp_instance *gti,
>  		goto err2;
>  	}
>  
> +	netdev_dbg(dev, "enable gtp on %p, %p\n", sock0, sock1u);
> +
>  	gti->sock0 = sock0;
>  	gti->sock1u = sock1u;
>  
> @@ -1059,7 +1079,7 @@ static int ipv4_pdp_add(struct net_device *dev, struct genl_info *info)
>  
>  static int gtp_genl_tunnel_new(struct sk_buff *skb, struct genl_info *info)
>  {
> -	struct net *net = sock_net(skb->sk);
> +	struct net *net;
>  	struct net_device *dev;
>  
>  	if (!info->attrs[GTPA_VERSION] ||
> @@ -1069,6 +1089,10 @@ static int gtp_genl_tunnel_new(struct sk_buff *skb, struct genl_info *info)
>  	    !info->attrs[GTPA_TID])
>  		return -EINVAL;
>  
> +	net = gtp_genl_get_net(sock_net(skb->sk), info->attrs);
> +	if (net == NULL)

This has to be IS_ERR().

> +		return -EINVAL;
> +
>  	/* Check if there's an existing gtpX device to configure */
>  	dev = gtp_find_dev(net, nla_get_u32(info->attrs[GTPA_LINK]));
>  	if (dev == NULL)
> @@ -1079,7 +1103,7 @@ static int gtp_genl_tunnel_new(struct sk_buff *skb, struct genl_info *info)
>  
>  static int gtp_genl_tunnel_delete(struct sk_buff *skb, struct genl_info *info)
>  {
> -	struct net *net = sock_net(skb->sk);
> +	struct net *net;
>  	struct gtp_instance *gti;
>  	struct net_device *dev;
>  	struct pdp_ctx *pctx;
> @@ -1107,6 +1131,10 @@ static int gtp_genl_tunnel_delete(struct sk_buff *skb, struct genl_info *info)
>  	if (gtp_version == GTP_V1 && tid > UINT_MAX)
>  		return -EINVAL;
>  
> +	net = gtp_genl_get_net(sock_net(skb->sk), info->attrs);
> +	if (net == NULL)

This one too.

> +		return -EINVAL;
> +
>  	/* Check if there's an existing gtpX device to configure */
>  	dev = gtp_find_dev(net, nla_get_u32(info->attrs[GTPA_LINK]));
>  	if (dev == NULL)
> @@ -1175,7 +1203,7 @@ nla_put_failure:
>  
>  static int gtp_genl_tunnel_get(struct sk_buff *skb, struct genl_info *info)
>  {
> -	struct net *net = sock_net(skb->sk);
> +	struct net *net;
>  	struct net_device *dev;
>  	struct gtp_instance *gti;
>  	struct pdp_ctx *pctx = NULL;
> @@ -1196,6 +1224,10 @@ static int gtp_genl_tunnel_get(struct sk_buff *skb, struct genl_info *info)
>  		return -EINVAL;
>  	}
>  
> +	net = gtp_genl_get_net(sock_net(skb->sk), info->attrs);
> +	if (net == NULL)

And here.

BTW, I'd appreciate if you can add netdev_dbg stuff in a separated
patch.