[PATCH net-next 1/2] netns: define extack error msg for nsis cmds

[Nicolas Dichtel]

It helps the user to identify errors.

CC: Jamal Hadi Salim <j...@mojatatu.com>
Signed-off-by: Nicolas Dichtel <nicolas.dich...@6wind.com>
---
 net/core/net_namespace.c | 42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 26bbfababff2..1f60c180e2de 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -596,6 +596,7 @@ static int rtnl_net_newid(struct sk_buff *skb, struct 
nlmsghdr *nlh,
 {
        struct net *net = sock_net(skb->sk);
        struct nlattr *tb[NETNSA_MAX + 1];
+       struct nlattr *nla;
        struct net *peer;
        int nsid, err;
 
@@ -603,23 +604,35 @@ static int rtnl_net_newid(struct sk_buff *skb, struct 
nlmsghdr *nlh,
                          rtnl_net_policy, extack);
        if (err < 0)
                return err;
-       if (!tb[NETNSA_NSID])
+       if (!tb[NETNSA_NSID]) {
+               NL_SET_ERR_MSG(extack, "nsid is missing");
                return -EINVAL;
+       }
        nsid = nla_get_s32(tb[NETNSA_NSID]);
 
-       if (tb[NETNSA_PID])
+       if (tb[NETNSA_PID]) {
                peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
-       else if (tb[NETNSA_FD])
+               nla = tb[NETNSA_PID];
+       } else if (tb[NETNSA_FD]) {
                peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
-       else
+               nla = tb[NETNSA_FD];
+       } else {
+               NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
                return -EINVAL;
-       if (IS_ERR(peer))
+       }
+       if (IS_ERR(peer)) {
+               NL_SET_BAD_ATTR(extack, nla);
+               NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
                return PTR_ERR(peer);
+       }
 
        spin_lock_bh(&net->nsid_lock);
        if (__peernet2id(net, peer) >= 0) {
                spin_unlock_bh(&net->nsid_lock);
                err = -EEXIST;
+               NL_SET_BAD_ATTR(extack, nla);
+               NL_SET_ERR_MSG(extack,
+                              "Peer netns already has a nsid assigned");
                goto out;
        }
 
@@ -628,6 +641,9 @@ static int rtnl_net_newid(struct sk_buff *skb, struct 
nlmsghdr *nlh,
        if (err >= 0) {
                rtnl_net_notifyid(net, RTM_NEWNSID, err);
                err = 0;
+       } else if (err == -ENOSPC && nsid >= 0) {
+               NL_SET_BAD_ATTR(extack, tb[NETNSA_NSID]);
+               NL_SET_ERR_MSG(extack, "The specified nsid is already used");
        }
 out:
        put_net(peer);
@@ -670,6 +686,7 @@ static int rtnl_net_getid(struct sk_buff *skb, struct 
nlmsghdr *nlh,
 {
        struct net *net = sock_net(skb->sk);
        struct nlattr *tb[NETNSA_MAX + 1];
+       struct nlattr *nla;
        struct sk_buff *msg;
        struct net *peer;
        int err, id;
@@ -678,15 +695,22 @@ static int rtnl_net_getid(struct sk_buff *skb, struct 
nlmsghdr *nlh,
                          rtnl_net_policy, extack);
        if (err < 0)
                return err;
-       if (tb[NETNSA_PID])
+       if (tb[NETNSA_PID]) {
                peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
-       else if (tb[NETNSA_FD])
+               nla = tb[NETNSA_PID];
+       } else if (tb[NETNSA_FD]) {
                peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
-       else
+               nla = tb[NETNSA_FD];
+       } else {
+               NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
                return -EINVAL;
+       }
 
-       if (IS_ERR(peer))
+       if (IS_ERR(peer)) {
+               NL_SET_BAD_ATTR(extack, nla);
+               NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
                return PTR_ERR(peer);
+       }
 
        msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
        if (!msg) {
-- 
2.8.1