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rtnetlink: always put IFLA_LINK for links with a link-netnsid

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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: d8a5ec6727 ("[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>
This commit is contained in:
Sabrina Dubroca 2019-05-14 15:12:19 +02:00 committed by David S. Miller
parent 00f9fec481
commit feadc4b6cf
1 changed files with 10 additions and 6 deletions
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16
net/core/rtnetlink.c
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@ -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 &&