releases/5.1.5/rtnetlink-always-put-ifla_link-for-links-with-a-link-netnsid.patch

   1 From foo@baz Wed 22 May 2019 08:34:59 AM CEST
   2 From: Sabrina Dubroca <sd@queasysnail.net>
   3 Date: Tue, 14 May 2019 15:12:19 +0200
   4 Subject: rtnetlink: always put IFLA_LINK for links with a link-netnsid
   5
   6 From: Sabrina Dubroca <sd@queasysnail.net>
   7
   8 [ Upstream commit feadc4b6cf42a53a8a93c918a569a0b7e62bd350 ]
   9
  10 Currently, nla_put_iflink() doesn't put the IFLA_LINK attribute when
  11 iflink == ifindex.
  12
  13 In some cases, a device can be created in a different netns with the
  14 same ifindex as its parent. That device will not dump its IFLA_LINK
  15 attribute, which can confuse some userspace software that expects it.
  16 For example, if the last ifindex created in init_net and foo are both
  17 8, these commands will trigger the issue:
  18
  19     ip link add parent type dummy                   # ifindex 9
  20     ip link add link parent netns foo type macvlan  # ifindex 9 in ns foo
  21
  22 So, in case a device puts the IFLA_LINK_NETNSID attribute in a dump,
  23 always put the IFLA_LINK attribute as well.
  24
  25 Thanks to Dan Winship for analyzing the original OpenShift bug down to
  26 the missing netlink attribute.
  27
  28 v2: change Fixes tag, it's been here forever, as Nicolas Dichtel said
  29     add Nicolas' ack
  30 v3: change Fixes tag
  31     fix subject typo, spotted by Edward Cree
  32
  33 Analyzed-by: Dan Winship <danw@redhat.com>
  34 Fixes: d8a5ec672768 ("[NET]: netlink support for moving devices between network namespaces.")
  35 Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
  36 Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
  37 Signed-off-by: David S. Miller <davem@davemloft.net>
  38 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  39 ---
  40  net/core/rtnetlink.c |   16 ++++++++++------
  41  1 file changed, 10 insertions(+), 6 deletions(-)
  42
  43 --- a/net/core/rtnetlink.c
  44 +++ b/net/core/rtnetlink.c
  45 @@ -1496,14 +1496,15 @@ static int put_master_ifindex(struct sk_
  46         return ret;
  47  }
  48
  49 -static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev)
  50 +static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev,
  51 +                         bool force)
  52  {
  53         int ifindex = dev_get_iflink(dev);
  54
  55 -       if (dev->ifindex == ifindex)
  56 -               return 0;
  57 +       if (force || dev->ifindex != ifindex)
  58 +               return nla_put_u32(skb, IFLA_LINK, ifindex);
  59
  60 -       return nla_put_u32(skb, IFLA_LINK, ifindex);
  61 +       return 0;
  62  }
  63
  64  static noinline_for_stack int nla_put_ifalias(struct sk_buff *skb,
  65 @@ -1520,6 +1521,8 @@ static int rtnl_fill_link_netnsid(struct
  66                                   const struct net_device *dev,
  67                                   struct net *src_net)
  68  {
  69 +       bool put_iflink = false;
  70 +
  71         if (dev->rtnl_link_ops && dev->rtnl_link_ops->get_link_net) {
  72                 struct net *link_net = dev->rtnl_link_ops->get_link_net(dev);
  73
  74 @@ -1528,10 +1531,12 @@ static int rtnl_fill_link_netnsid(struct
  75
  76                         if (nla_put_s32(skb, IFLA_LINK_NETNSID, id))
  77                                 return -EMSGSIZE;
  78 +
  79 +                       put_iflink = true;
  80                 }
  81         }
  82
  83 -       return 0;
  84 +       return nla_put_iflink(skb, dev, put_iflink);
  85  }
  86
  87  static int rtnl_fill_link_af(struct sk_buff *skb,
  88 @@ -1617,7 +1622,6 @@ static int rtnl_fill_ifinfo(struct sk_bu
  89  #ifdef CONFIG_RPS
  90             nla_put_u32(skb, IFLA_NUM_RX_QUEUES, dev->num_rx_queues) ||
  91  #endif
  92 -           nla_put_iflink(skb, dev) ||
  93             put_master_ifindex(skb, dev) ||
  94             nla_put_u8(skb, IFLA_CARRIER, netif_carrier_ok(dev)) ||
  95             (dev->qdisc &&