6 files changed, 245 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 9de900572633..9b91d9f0257e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6578,6 +6578,7 @@ F:	include/linux/netdevice.h
 F:      include/uapi/linux/in.h
 F:      include/uapi/linux/net.h
 F:      include/uapi/linux/netdevice.h
+F:      include/uapi/linux/net_namespace.h
 F:      tools/net/
 F:      tools/testing/selftests/net/
 F:      lib/random32.c
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 2e8756b8c775..36faf4990c4b 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -60,6 +60,7 @@ struct net {
         struct list_head        exit_list;      /* Use only net_mutex */
 
         struct user_namespace   *user_ns;       /* Owning user namespace */
+        struct idr              netns_ids;
 
         struct ns_common        ns;
 
@@ -290,6 +291,9 @@ static inline struct net *read_pnet(struct net * const *pnet)
 #define __net_initconst __initconst
 #endif
 
+int peernet2id(struct net *net, struct net *peer);
+struct net *get_net_ns_by_id(struct net *net, int id);
+
 struct pernet_operations {
         struct list_head list;
         int (*init)(struct net *net);
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index 00b100023c47..14b7b6e44c77 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -283,6 +283,7 @@ header-y += net.h
 header-y += netlink_diag.h
 header-y += netlink.h
 header-y += netrom.h
+header-y += net_namespace.h
 header-y += net_tstamp.h
 header-y += nfc.h
 header-y += nfs2.h
diff --git a/include/uapi/linux/net_namespace.h b/include/uapi/linux/net_namespace.h
new file mode 100644
index 000000000000..778cd2c3ebf4
--- /dev/null
+++ b/include/uapi/linux/net_namespace.h
@@ -0,0 +1,23 @@
+/* Copyright (c) 2015 6WIND S.A.
+ * Author: Nicolas Dichtel <nicolas.dichtel@6wind.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+#ifndef _UAPI_LINUX_NET_NAMESPACE_H_
+#define _UAPI_LINUX_NET_NAMESPACE_H_
+
+/* Attributes of RTM_NEWNSID/RTM_GETNSID messages */
+enum {
+        NETNSA_NONE,
+#define NETNSA_NSID_NOT_ASSIGNED -1
+        NETNSA_NSID,
+        NETNSA_PID,
+        NETNSA_FD,
+        __NETNSA_MAX,
+};
+
+#define NETNSA_MAX              (__NETNSA_MAX - 1)
+
+#endif /* _UAPI_LINUX_NET_NAMESPACE_H_ */
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h
index a1d18593f41e..5cc5d66bf519 100644
--- a/include/uapi/linux/rtnetlink.h
+++ b/include/uapi/linux/rtnetlink.h
@@ -132,6 +132,11 @@ enum {
         RTM_GETMDB = 86,
 #define RTM_GETMDB RTM_GETMDB
 
+        RTM_NEWNSID = 88,
+#define RTM_NEWNSID RTM_NEWNSID
+        RTM_GETNSID = 90,
+#define RTM_GETNSID RTM_GETNSID
+
         __RTM_MAX,
 #define RTM_MAX         (((__RTM_MAX + 3) & ~3) - 1)
 };
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index ce780c722e48..9d1a4cac83b6 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -15,6 +15,10 @@
 #include <linux/file.h>
 #include <linux/export.h>
 #include <linux/user_namespace.h>
+#include <linux/net_namespace.h>
+#include <linux/rtnetlink.h>
+#include <net/sock.h>
+#include <net/netlink.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -144,6 +148,77 @@ static void ops_free_list(const struct pernet_operations *ops,
         }
 }
 
+static int alloc_netid(struct net *net, struct net *peer, int reqid)
+{
+        int min = 0, max = 0;
+
+        ASSERT_RTNL();
+
+        if (reqid >= 0) {
+                min = reqid;
+                max = reqid + 1;
+        }
+
+        return idr_alloc(&net->netns_ids, peer, min, max, GFP_KERNEL);
+}
+
+/* This function is used by idr_for_each(). If net is equal to peer, the
+ * function returns the id so that idr_for_each() stops. Because we cannot
+ * returns the id 0 (idr_for_each() will not stop), we return the magic value
+ * NET_ID_ZERO (-1) for it.
+ */
+#define NET_ID_ZERO -1
+static int net_eq_idr(int id, void *net, void *peer)
+{
+        if (net_eq(net, peer))
+                return id ? : NET_ID_ZERO;
+        return 0;
+}
+
+static int __peernet2id(struct net *net, struct net *peer, bool alloc)
+{
+        int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
+
+        ASSERT_RTNL();
+
+        /* Magic value for id 0. */
+        if (id == NET_ID_ZERO)
+                return 0;
+        if (id > 0)
+                return id;
+
+        if (alloc)
+                return alloc_netid(net, peer, -1);
+
+        return -ENOENT;
+}
+
+/* This function returns the id of a peer netns. If no id is assigned, one will
+ * be allocated and returned.
+ */
+int peernet2id(struct net *net, struct net *peer)
+{
+        int id = __peernet2id(net, peer, true);
+
+        return id >= 0 ? id : NETNSA_NSID_NOT_ASSIGNED;
+}
+
+struct net *get_net_ns_by_id(struct net *net, int id)
+{
+        struct net *peer;
+
+        if (id < 0)
+                return NULL;
+
+        rcu_read_lock();
+        peer = idr_find(&net->netns_ids, id);
+        if (peer)
+                get_net(peer);
+        rcu_read_unlock();
+
+        return peer;
+}
+
 /*
  * setup_net runs the initializers for the network namespace object.
  */
@@ -158,6 +233,7 @@ static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
         atomic_set(&net->passive, 1);
         net->dev_base_seq = 1;
         net->user_ns = user_ns;
+        idr_init(&net->netns_ids);
 
 #ifdef NETNS_REFCNT_DEBUG
         atomic_set(&net->use_count, 0);
@@ -288,6 +364,14 @@ static void cleanup_net(struct work_struct *work)
         list_for_each_entry(net, &net_kill_list, cleanup_list) {
                 list_del_rcu(&net->list);
                 list_add_tail(&net->exit_list, &net_exit_list);
+                for_each_net(tmp) {
+                        int id = __peernet2id(tmp, net, false);
+
+                        if (id >= 0)
+                                idr_remove(&tmp->netns_ids, id);
+                }
+                idr_destroy(&net->netns_ids);
+
         }
         rtnl_unlock();
 
@@ -402,6 +486,130 @@ static struct pernet_operations __net_initdata net_ns_ops = {
         .exit = net_ns_net_exit,
 };
 
+static struct nla_policy rtnl_net_policy[NETNSA_MAX + 1] = {
+        [NETNSA_NONE]           = { .type = NLA_UNSPEC },
+        [NETNSA_NSID]           = { .type = NLA_S32 },
+        [NETNSA_PID]            = { .type = NLA_U32 },
+        [NETNSA_FD]             = { .type = NLA_U32 },
+};
+
+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 net *peer;
+        int nsid, err;
+
+        err = nlmsg_parse(nlh, sizeof(struct rtgenmsg), tb, NETNSA_MAX,
+                          rtnl_net_policy);
+        if (err < 0)
+                return err;
+        if (!tb[NETNSA_NSID])
+                return -EINVAL;
+        nsid = nla_get_s32(tb[NETNSA_NSID]);
+
+        if (tb[NETNSA_PID])
+                peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
+        else if (tb[NETNSA_FD])
+                peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
+        else
+                return -EINVAL;
+        if (IS_ERR(peer))
+                return PTR_ERR(peer);
+
+        if (__peernet2id(net, peer, false) >= 0) {
+                err = -EEXIST;
+                goto out;
+        }
+
+        err = alloc_netid(net, peer, nsid);
+        if (err > 0)
+                err = 0;
+out:
+        put_net(peer);
+        return err;
+}
+
+static int rtnl_net_get_size(void)
+{
+        return NLMSG_ALIGN(sizeof(struct rtgenmsg))
+               + nla_total_size(sizeof(s32)) /* NETNSA_NSID */
+               ;
+}
+
+static int rtnl_net_fill(struct sk_buff *skb, u32 portid, u32 seq, int flags,
+                         int cmd, struct net *net, struct net *peer)
+{
+        struct nlmsghdr *nlh;
+        struct rtgenmsg *rth;
+        int id;
+
+        ASSERT_RTNL();
+
+        nlh = nlmsg_put(skb, portid, seq, cmd, sizeof(*rth), flags);
+        if (!nlh)
+                return -EMSGSIZE;
+
+        rth = nlmsg_data(nlh);
+        rth->rtgen_family = AF_UNSPEC;
+
+        id = __peernet2id(net, peer, false);
+        if  (id < 0)
+                id = NETNSA_NSID_NOT_ASSIGNED;
+        if (nla_put_s32(skb, NETNSA_NSID, id))
+                goto nla_put_failure;
+
+        nlmsg_end(skb, nlh);
+        return 0;
+
+nla_put_failure:
+        nlmsg_cancel(skb, nlh);
+        return -EMSGSIZE;
+}
+
+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 sk_buff *msg;
+        int err = -ENOBUFS;
+        struct net *peer;
+
+        err = nlmsg_parse(nlh, sizeof(struct rtgenmsg), tb, NETNSA_MAX,
+                          rtnl_net_policy);
+        if (err < 0)
+                return err;
+        if (tb[NETNSA_PID])
+                peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
+        else if (tb[NETNSA_FD])
+                peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
+        else
+                return -EINVAL;
+
+        if (IS_ERR(peer))
+                return PTR_ERR(peer);
+
+        msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
+        if (!msg) {
+                err = -ENOMEM;
+                goto out;
+        }
+
+        err = rtnl_net_fill(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq, 0,
+                            RTM_GETNSID, net, peer);
+        if (err < 0)
+                goto err_out;
+
+        err = rtnl_unicast(msg, net, NETLINK_CB(skb).portid);
+        goto out;
+
+err_out:
+        nlmsg_free(msg);
+out:
+        put_net(peer);
+        return err;
+}
+
 static int __init net_ns_init(void)
 {
         struct net_generic *ng;
@@ -435,6 +643,9 @@ static int __init net_ns_init(void)
 
         register_pernet_subsys(&net_ns_ops);
 
+        rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL, NULL);
+        rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, NULL, NULL);
+
         return 0;
 }