rtnetlink: always put IFLA_LINK for links with a link-netnsid
Currently, nla_put_iflink() doesn't put the IFLA_LINK attribute when
iflink == ifindex.
In some cases, a device can be created in a different netns with the
same ifindex as its parent. That device will not dump its IFLA_LINK
attribute, which can confuse some userspace software that expects it.
For example, if the last ifindex created in init_net and foo are both
8, these commands will trigger the issue:
ip link add parent type dummy # ifindex 9
ip link add link parent netns foo type macvlan # ifindex 9 in ns foo
So, in case a device puts the IFLA_LINK_NETNSID attribute in a dump,
always put the IFLA_LINK attribute as well.
Thanks to Dan Winship for analyzing the original OpenShift bug down to
the missing netlink attribute.
v2: change Fixes tag, it's been here forever, as Nicolas Dichtel said
add Nicolas' ack
v3: change Fixes tag
fix subject typo, spotted by Edward Cree
Analyzed-by: Dan Winship <danw@redhat.com>
Fixes: d8a5ec672768 ("[NET]: netlink support for moving devices between network namespaces.")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2bd12af..adcc045 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1496,14 +1496,15 @@ static int put_master_ifindex(struct sk_buff *skb, struct net_device *dev)
return ret;
}
-static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev)
+static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev,
+ bool force)
{
int ifindex = dev_get_iflink(dev);
- if (dev->ifindex == ifindex)
- return 0;
+ if (force || dev->ifindex != ifindex)
+ return nla_put_u32(skb, IFLA_LINK, ifindex);
- return nla_put_u32(skb, IFLA_LINK, ifindex);
+ return 0;
}
static noinline_for_stack int nla_put_ifalias(struct sk_buff *skb,
@@ -1520,6 +1521,8 @@ static int rtnl_fill_link_netnsid(struct sk_buff *skb,
const struct net_device *dev,
struct net *src_net)
{
+ bool put_iflink = false;
+
if (dev->rtnl_link_ops && dev->rtnl_link_ops->get_link_net) {
struct net *link_net = dev->rtnl_link_ops->get_link_net(dev);
@@ -1528,10 +1531,12 @@ static int rtnl_fill_link_netnsid(struct sk_buff *skb,
if (nla_put_s32(skb, IFLA_LINK_NETNSID, id))
return -EMSGSIZE;
+
+ put_iflink = true;
}
}
- return 0;
+ return nla_put_iflink(skb, dev, put_iflink);
}
static int rtnl_fill_link_af(struct sk_buff *skb,
@@ -1617,7 +1622,6 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
#ifdef CONFIG_RPS
nla_put_u32(skb, IFLA_NUM_RX_QUEUES, dev->num_rx_queues) ||
#endif
- nla_put_iflink(skb, dev) ||
put_master_ifindex(skb, dev) ||
nla_put_u8(skb, IFLA_CARRIER, netif_carrier_ok(dev)) ||
(dev->qdisc &&