On Mon, 5 Apr 2021 00:12:23 -0700 Andrei Vagin wrote:
> Currently, we can specify ifindex on link creation. This change allows
> to specify ifindex when a device is moved to another network namespace.
>
> Even now, a device ifindex can be changed if there is another device
> with the same ifindex in the target namespace. So this change doesn't
> introduce completely new behavior, it adds more control to the process.
>
> CRIU users want to restore containers with pre-created network devices.
> A user will provide network devices and instructions where they have to
> be restored, then CRIU will restore network namespaces and move devices
> into them. The problem is that devices have to be restored with the same
> indexes that they have before C/R.
>
> Cc: Alexander Mikhalitsyn <alexander.mikhalit...@virtuozzo.com>
> Suggested-by: Christian Brauner <christian.brau...@ubuntu.com>
> Signed-off-by: Andrei Vagin <ava...@gmail.com>
> @@ -2354,7 +2354,7 @@ static int netvsc_register_vf(struct net_device
> *vf_netdev)
> */
> if (!net_eq(dev_net(ndev), dev_net(vf_netdev))) {
> ret = dev_change_net_namespace(vf_netdev,
> - dev_net(ndev), "eth%d");
> + dev_net(ndev), "eth%d", 0);
Given vast majority of callers pass 0 as the new param - perhaps
dev_change_net_namespace() should become a static inline wrapper
over a function with more parameters?
> if (ret)
> netdev_err(vf_netdev,
> "could not move to same namespace as %s:
> %d\n",
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index 1bdcb33fb561..d51252afde0a 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -2266,6 +2266,9 @@ static int validate_linkmsg(struct net_device *dev,
> struct nlattr *tb[])
> return -EINVAL;
> }
>
> + if (tb[IFLA_NEW_IFINDEX] && nla_get_s32(tb[IFLA_NEW_IFINDEX]) <= 0)
> + return -EINVAL;
I think you need to add IFLA_NEW_IFINDEX to ifla_policy, it used to be
an output only attribute, it's missing input validation. You can add
policy right there NLA_POLICY_MIN(NLA_S32, 0) - .min is 16 bit but it'd
get promoted correctly, I believe?
> if (tb[IFLA_AF_SPEC]) {
> struct nlattr *af;
> int rem, err;
