| Message ID | 3ce6c14decb494908bd516698ec7f4de6001eef3.1557829576.git.sd@queasysnail.net |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net,v3] rtnetlink: always put IFLA_LINK for links with a link-netnsid | expand |
From: Sabrina Dubroca <sd@queasysnail.net> Date: Tue, 14 May 2019 15:12:19 +0200 > 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> Applied and queued up for -stable, thank you.
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 2bd12afb9297..adcc045952c2 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 &&
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> --- net/core/rtnetlink.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)