From 7c4f63ba824302492985553018881455982241d6 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 24 Jan 2018 15:26:32 +0100 Subject: [PATCH] rtnetlink: enable IFLA_IF_NETNSID in do_setlink() RTM_{NEW,SET}LINK already allow operations on other network namespaces by identifying the target network namespace through IFLA_NET_NS_{FD,PID} properties. This is done by looking for the corresponding properties in do_setlink(). Extend do_setlink() to also look for the IFLA_IF_NETNSID property. This introduces no functional changes since all callers of do_setlink() currently block IFLA_IF_NETNSID by reporting an error before they reach do_setlink(). This introduces the helpers: static struct net *rtnl_link_get_net_by_nlattr(struct net *src_net, struct nlattr *tb[]) static struct net *rtnl_link_get_net_capable(const struct sk_buff *skb, struct net *src_net, struct nlattr *tb[], int cap) to simplify permission checks and target network namespace retrieval for RTM_* requests that already support IFLA_NET_NS_{FD,PID} but get extended to IFLA_IF_NETNSID. To perserve backwards compatibility the helpers look for IFLA_NET_NS_{FD,PID} properties first before checking for IFLA_IF_NETNSID. Signed-off-by: Christian Brauner Signed-off-by: David S. Miller --- net/core/rtnetlink.c | 54 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 47 insertions(+), 7 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 97874daa1336..f7e99c25dfe4 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1902,6 +1902,49 @@ struct net *rtnl_link_get_net(struct net *src_net, struct nlattr *tb[]) } EXPORT_SYMBOL(rtnl_link_get_net); +/* Figure out which network namespace we are talking about by + * examining the link attributes in the following order: + * + * 1. IFLA_NET_NS_PID + * 2. IFLA_NET_NS_FD + * 3. IFLA_IF_NETNSID + */ +static struct net *rtnl_link_get_net_by_nlattr(struct net *src_net, + struct nlattr *tb[]) +{ + struct net *net; + + if (tb[IFLA_NET_NS_PID] || tb[IFLA_NET_NS_FD]) + return rtnl_link_get_net(src_net, tb); + + if (!tb[IFLA_IF_NETNSID]) + return get_net(src_net); + + net = get_net_ns_by_id(src_net, nla_get_u32(tb[IFLA_IF_NETNSID])); + if (!net) + return ERR_PTR(-EINVAL); + + return net; +} + +static struct net *rtnl_link_get_net_capable(const struct sk_buff *skb, + struct net *src_net, + struct nlattr *tb[], int cap) +{ + struct net *net; + + net = rtnl_link_get_net_by_nlattr(src_net, tb); + if (IS_ERR(net)) + return net; + + if (!netlink_ns_capable(skb, net->user_ns, cap)) { + put_net(net); + return ERR_PTR(-EPERM); + } + + return net; +} + static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[]) { if (dev) { @@ -2164,17 +2207,14 @@ static int do_setlink(const struct sk_buff *skb, const struct net_device_ops *ops = dev->netdev_ops; int err; - if (tb[IFLA_NET_NS_PID] || tb[IFLA_NET_NS_FD]) { - struct net *net = rtnl_link_get_net(dev_net(dev), tb); + if (tb[IFLA_NET_NS_PID] || tb[IFLA_NET_NS_FD] || tb[IFLA_IF_NETNSID]) { + struct net *net = rtnl_link_get_net_capable(skb, dev_net(dev), + tb, CAP_NET_ADMIN); if (IS_ERR(net)) { err = PTR_ERR(net); goto errout; } - if (!netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN)) { - put_net(net); - err = -EPERM; - goto errout; - } + err = dev_change_net_namespace(dev, net, ifname); put_net(net); if (err)