rtnetlink: Call rtnl_link_get_net_capable() in rtnl_newlink().

As a prerequisite of per-netns RTNL, we must fetch netns before
looking up dev or moving it to another netns.

rtnl_link_get_net_capable() is called in rtnl_newlink_create() and
do_setlink(), but both of them need to be moved to the RTNL-independent
region, which will be rtnl_newlink().

Let's call rtnl_link_get_net_capable() in rtnl_newlink() and pass the
netns down to where needed.

Note that the latter two have not passed the nets to do_setlink() yet
but will do so after the remaining rtnl_link_get_net_capable() is moved
to rtnl_setlink() later.

While at it, dest_net is renamed to tgt_net in rtnl_newlink_create() to
align with rtnl_{del,set}link().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 31b105b3a8344b0c8b715184db5e8c1e045c927f..f6823c8d21ad017b957d5111bc6021b7719cf58f 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3549,7 +3549,7 @@ struct rtnl_newlink_tbs {
 
 static int rtnl_changelink(const struct sk_buff *skb, struct nlmsghdr *nlh,
                           const struct rtnl_link_ops *ops,
-                          struct net_device *dev,
+                          struct net_device *dev, struct net *tgt_net,
                           struct rtnl_newlink_tbs *tbs,
                           struct nlattr **data,
                           struct netlink_ext_ack *extack)
@@ -3613,10 +3613,10 @@ static int rtnl_changelink(const struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 
 static int rtnl_group_changelink(const struct sk_buff *skb,
-               struct net *net, int group,
-               struct ifinfomsg *ifm,
-               struct netlink_ext_ack *extack,
-               struct nlattr **tb)
+                                struct net *net, struct net *tgt_net,
+                                int group, struct ifinfomsg *ifm,
+                                struct netlink_ext_ack *extack,
+                                struct nlattr **tb)
 {
        struct net_device *dev, *aux;
        int err;
@@ -3634,6 +3634,7 @@ static int rtnl_group_changelink(const struct sk_buff *skb,
 
 static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
                               const struct rtnl_link_ops *ops,
+                              struct net *tgt_net,
                               const struct nlmsghdr *nlh,
                               struct nlattr **tb, struct nlattr **data,
                               struct netlink_ext_ack *extack)
@@ -3641,9 +3642,9 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
        unsigned char name_assign_type = NET_NAME_USER;
        struct net *net = sock_net(skb->sk);
        u32 portid = NETLINK_CB(skb).portid;
-       struct net *dest_net, *link_net;
        struct net_device *dev;
        char ifname[IFNAMSIZ];
+       struct net *link_net;
        int err;
 
        if (!ops->alloc && !ops->setup)
@@ -3656,14 +3657,10 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
                name_assign_type = NET_NAME_ENUM;
        }
 
-       dest_net = rtnl_link_get_net_capable(skb, net, tb, CAP_NET_ADMIN);
-       if (IS_ERR(dest_net))
-               return PTR_ERR(dest_net);
-
        if (tb[IFLA_LINK_NETNSID]) {
                int id = nla_get_s32(tb[IFLA_LINK_NETNSID]);
 
-               link_net = get_net_ns_by_id(dest_net, id);
+               link_net = get_net_ns_by_id(tgt_net, id);
                if (!link_net) {
                        NL_SET_ERR_MSG(extack, "Unknown network namespace id");
                        err =  -EINVAL;
@@ -3676,7 +3673,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
                link_net = NULL;
        }
 
-       dev = rtnl_create_link(link_net ? : dest_net, ifname,
+       dev = rtnl_create_link(link_net ? : tgt_net, ifname,
                               name_assign_type, ops, tb, extack);
        if (IS_ERR(dev)) {
                err = PTR_ERR(dev);
@@ -3698,7 +3695,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
        if (err < 0)
                goto out_unregister;
        if (link_net) {
-               err = dev_change_net_namespace(dev, dest_net, ifname);
+               err = dev_change_net_namespace(dev, tgt_net, ifname);
                if (err < 0)
                        goto out_unregister;
        }
@@ -3710,7 +3707,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 out:
        if (link_net)
                put_net(link_net);
-       put_net(dest_net);
+
        return err;
 out_unregister:
        if (ops->newlink) {
@@ -3726,6 +3723,7 @@ out_unregister:
 
 static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
                          const struct rtnl_link_ops *ops,
+                         struct net *tgt_net,
                          struct rtnl_newlink_tbs *tbs,
                          struct nlattr **data,
                          struct netlink_ext_ack *extack)
@@ -3752,19 +3750,18 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
        }
 
        if (dev)
-               return rtnl_changelink(skb, nlh, ops, dev, tbs, data, extack);
+               return rtnl_changelink(skb, nlh, ops, dev, tgt_net, tbs, data, extack);
 
        if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
                /* No dev found and NLM_F_CREATE not set. Requested dev does not exist,
                 * or it's for a group
                */
-               if (link_specified)
+               if (link_specified || !tb[IFLA_GROUP])
                        return -ENODEV;
-               if (tb[IFLA_GROUP])
-                       return rtnl_group_changelink(skb, net,
-                                               nla_get_u32(tb[IFLA_GROUP]),
-                                               ifm, extack, tb);
-               return -ENODEV;
+
+               return rtnl_group_changelink(skb, net, tgt_net,
+                                            nla_get_u32(tb[IFLA_GROUP]),
+                                            ifm, extack, tb);
        }
 
        if (tb[IFLA_MAP] || tb[IFLA_PROTINFO])
@@ -3775,7 +3772,7 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
                return -EOPNOTSUPP;
        }
 
-       return rtnl_newlink_create(skb, ifm, ops, nlh, tb, data, extack);
+       return rtnl_newlink_create(skb, ifm, ops, tgt_net, nlh, tb, data, extack);
 }
 
 static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
@@ -3784,6 +3781,7 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
        struct nlattr **tb, **linkinfo, **data = NULL;
        struct rtnl_link_ops *ops = NULL;
        struct rtnl_newlink_tbs *tbs;
+       struct net *tgt_net;
        int ops_srcu_index;
        int ret;
 
@@ -3848,8 +3846,15 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
                }
        }
 
-       ret = __rtnl_newlink(skb, nlh, ops, tbs, data, extack);
+       tgt_net = rtnl_link_get_net_capable(skb, sock_net(skb->sk), tb, CAP_NET_ADMIN);
+       if (IS_ERR(tgt_net)) {
+               ret = PTR_ERR(tgt_net);
+               goto put_ops;
+       }
+
+       ret = __rtnl_newlink(skb, nlh, ops, tgt_net, tbs, data, extack);
 
+       put_net(tgt_net);
 put_ops:
        if (ops)
                rtnl_link_ops_put(ops, ops_srcu_index);