netns: enable to dump full nsid translation table

Like the previous patch, the goal is to ease to convert nsids from one
netns to another netns.
A new attribute (NETNSA_CURRENT_NSID) is added to the kernel answer when
NETNSA_TARGET_NSID is provided, thus the user can easily convert nsids.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/net_namespace.h b/include/uapi/linux/net_namespace.h
index 0ed9dd61d32a1ed7a66ad235566fff8d9a2d63a7..9f99568095651228b2d1bf142ae4954810c337c1 100644 (file)
--- a/include/uapi/linux/net_namespace.h
+++ b/include/uapi/linux/net_namespace.h
@@ -17,6 +17,7 @@ enum {
        NETNSA_PID,
        NETNSA_FD,
        NETNSA_TARGET_NSID,
+       NETNSA_CURRENT_NSID,
        __NETNSA_MAX,
 };
 

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index dd25fb22ad459bce51548e345ceb4d035a726206..05b23b285058ad9bb29fab107bd269edc8411c2b 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -736,6 +736,7 @@ static int rtnl_net_get_size(void)
 {
        return NLMSG_ALIGN(sizeof(struct rtgenmsg))
               + nla_total_size(sizeof(s32)) /* NETNSA_NSID */
+              + nla_total_size(sizeof(s32)) /* NETNSA_CURRENT_NSID */
               ;
 }
 
@@ -745,6 +746,8 @@ struct net_fill_args {
        int flags;
        int cmd;
        int nsid;
+       bool add_ref;
+       int ref_nsid;
 };
 
 static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
@@ -763,6 +766,10 @@ static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
        if (nla_put_s32(skb, NETNSA_NSID, args->nsid))
                goto nla_put_failure;
 
+       if (args->add_ref &&
+           nla_put_s32(skb, NETNSA_CURRENT_NSID, args->ref_nsid))
+               goto nla_put_failure;
+
        nlmsg_end(skb, nlh);
        return 0;
 
@@ -782,7 +789,6 @@ static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
                .cmd = RTM_NEWNSID,
        };
        struct net *peer, *target = net;
-       bool put_target = false;
        struct nlattr *nla;
        struct sk_buff *msg;
        int err;
@@ -824,7 +830,8 @@ static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
                        err = PTR_ERR(target);
                        goto out;
                }
-               put_target = true;
+               fillargs.add_ref = true;
+               fillargs.ref_nsid = peernet2id(net, peer);
        }
 
        msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
@@ -844,7 +851,7 @@ static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
 err_out:
        nlmsg_free(msg);
 out:
-       if (put_target)
+       if (fillargs.add_ref)
                put_net(target);
        put_net(peer);
        return err;
@@ -852,11 +859,11 @@ out:
 
 struct rtnl_net_dump_cb {
        struct net *tgt_net;
+       struct net *ref_net;
        struct sk_buff *skb;
        struct net_fill_args fillargs;
        int idx;
        int s_idx;
-       bool put_tgt_net;
 };
 
 static int rtnl_net_dumpid_one(int id, void *peer, void *data)
@@ -868,6 +875,8 @@ static int rtnl_net_dumpid_one(int id, void *peer, void *data)
                goto cont;
 
        net_cb->fillargs.nsid = id;
+       if (net_cb->fillargs.add_ref)
+               net_cb->fillargs.ref_nsid = __peernet2id(net_cb->ref_net, peer);
        ret = rtnl_net_fill(net_cb->skb, &net_cb->fillargs);
        if (ret < 0)
                return ret;
@@ -904,8 +913,9 @@ static int rtnl_valid_dump_net_req(const struct nlmsghdr *nlh, struct sock *sk,
                                               "Invalid target network namespace id");
                                return PTR_ERR(net);
                        }
+                       net_cb->fillargs.add_ref = true;
+                       net_cb->ref_net = net_cb->tgt_net;
                        net_cb->tgt_net = net;
-                       net_cb->put_tgt_net = true;
                } else {
                        NL_SET_BAD_ATTR(extack, tb[i]);
                        NL_SET_ERR_MSG(extack,
@@ -940,12 +950,22 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
        }
 
        spin_lock_bh(&net_cb.tgt_net->nsid_lock);
+       if (net_cb.fillargs.add_ref &&
+           !net_eq(net_cb.ref_net, net_cb.tgt_net) &&
+           !spin_trylock_bh(&net_cb.ref_net->nsid_lock)) {
+               spin_unlock_bh(&net_cb.tgt_net->nsid_lock);
+               err = -EAGAIN;
+               goto end;
+       }
        idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
+       if (net_cb.fillargs.add_ref &&
+           !net_eq(net_cb.ref_net, net_cb.tgt_net))
+               spin_unlock_bh(&net_cb.ref_net->nsid_lock);
        spin_unlock_bh(&net_cb.tgt_net->nsid_lock);
 
        cb->args[0] = net_cb.idx;
 end:
-       if (net_cb.put_tgt_net)
+       if (net_cb.fillargs.add_ref)
                put_net(net_cb.tgt_net);
        return err < 0 ? err : skb->len;
 }