From: Xiao Liang shaw.leon@gmail.com
[ Upstream commit ec061546c6cffbb8929495bba3953f0cc5e177fa ]
When creating link, lookup for existing device in target net namespace instead of current one. For example, two links created by:
# ip link add dummy1 type dummy # ip link add netns ns1 dummy1 type dummy
should have no conflict since they are in different namespaces.
Signed-off-by: Xiao Liang shaw.leon@gmail.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://patch.msgid.link/20250219125039.18024-2-shaw.leon@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/rtnetlink.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 80e006940f51a..ab7041150f295 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3865,20 +3865,26 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh, { struct nlattr ** const tb = tbs->tb; struct net *net = sock_net(skb->sk); + struct net *device_net; struct net_device *dev; struct ifinfomsg *ifm; bool link_specified;
+ /* When creating, lookup for existing device in target net namespace */ + device_net = (nlh->nlmsg_flags & NLM_F_CREATE) && + (nlh->nlmsg_flags & NLM_F_EXCL) ? + tgt_net : net; + ifm = nlmsg_data(nlh); if (ifm->ifi_index > 0) { link_specified = true; - dev = __dev_get_by_index(net, ifm->ifi_index); + dev = __dev_get_by_index(device_net, ifm->ifi_index); } else if (ifm->ifi_index < 0) { NL_SET_ERR_MSG(extack, "ifindex can't be negative"); return -EINVAL; } else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME]) { link_specified = true; - dev = rtnl_dev_get(net, tb); + dev = rtnl_dev_get(device_net, tb); } else { link_specified = false; dev = NULL;