With this patch, a user can define an id for a peer netns by providing a FD or a
PID. These ids are local to netns (ie valid only into one netns).
This will be useful for netlink messages when a x-netns interface is dumped.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
---
MAINTAINERS | 1 +
include/net/net_namespace.h | 5 ++
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/netns.h | 38 +++++++++
net/core/net_namespace.c | 195 ++++++++++++++++++++++++++++++++++++++++++++
net/netlink/genetlink.c | 4 +
6 files changed, 244 insertions(+)
create mode 100644 include/uapi/linux/netns.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 43898b1a8a2d..de7e6fcbd5c2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6382,6 +6382,7 @@ 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/netns.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 e0d64667a4b3..0f1367a71b81 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -59,6 +59,7 @@ struct net {
struct list_head exit_list; /* Use only net_mutex */
struct user_namespace *user_ns; /* Owning user namespace */
+ struct idr netns_ids;
unsigned int proc_inum;
@@ -289,6 +290,10 @@ 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);
+int netns_genl_register(void);
+
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 6cad97485bad..d7f49c69585a 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -277,6 +277,7 @@ header-y += netfilter_decnet.h
header-y += netfilter_ipv4.h
header-y += netfilter_ipv6.h
header-y += netlink.h
+header-y += netns.h
header-y += netrom.h
header-y += nfc.h
header-y += nfs.h
diff --git a/include/uapi/linux/netns.h b/include/uapi/linux/netns.h
new file mode 100644
index 000000000000..2edf129377de
--- /dev/null
+++ b/include/uapi/linux/netns.h
@@ -0,0 +1,38 @@
+/* Copyright (c) 2014 6WIND S.A.
+ * Author: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
+ *
+ * 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_NETNS_H_
+#define _UAPI_LINUX_NETNS_H_
+
+/* Generic netlink messages */
+
+#define NETNS_GENL_NAME "netns"
+#define NETNS_GENL_VERSION 0x1
+
+/* Commands */
+enum {
+ NETNS_CMD_UNSPEC,
+ NETNS_CMD_NEWID,
+ NETNS_CMD_GETID,
+ __NETNS_CMD_MAX,
+};
+
+#define NETNS_CMD_MAX (__NETNS_CMD_MAX - 1)
+
+/* Attributes */
+enum {
+ NETNSA_NONE,
+#define NETNSA_NSINDEX_UNKNOWN -1
+ NETNSA_NSID,
+ NETNSA_PID,
+ NETNSA_FD,
+ __NETNSA_MAX,
+};
+
+#define NETNSA_MAX (__NETNSA_MAX - 1)
+
+#endif /* _UAPI_LINUX_NETNS_H_ */
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 7f155175bba8..4a5680ed42fb 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -15,6 +15,8 @@
#include <linux/file.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
+#include <linux/netns.h>
+#include <net/genetlink.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
@@ -144,6 +146,50 @@ static void ops_free_list(const struct pernet_operations *ops,
}
}
+/* 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
+ * -1 for it.
+ */
+static int net_eq_idr(int id, void *net, void *peer)
+{
+ if (net_eq(net, peer))
+ return id ? : -1;
+ return 0;
+}
+
+/* returns NETNSA_NSINDEX_UNKNOWN if not found */
+int peernet2id(struct net *net, struct net *peer)
+{
+ int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
+
+ ASSERT_RTNL();
+
+ /* Magic value for id 0. */
+ if (id == -1)
+ return 0;
+ if (id == 0)
+ return NETNSA_NSINDEX_UNKNOWN;
+
+ return id;
+}
+
+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 +204,7 @@ 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 +335,14 @@ 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);
+
+ if (id >= 0)
+ idr_remove(&tmp->netns_ids, id);
+ }
+ idr_destroy(&net->netns_ids);
+
}
rtnl_unlock();
@@ -399,6 +454,146 @@ static struct pernet_operations __net_initdata net_ns_ops = {
.exit = net_ns_net_exit,
};
+static struct genl_family netns_genl_family = {
+ .id = GENL_ID_GENERATE,
+ .name = NETNS_GENL_NAME,
+ .version = NETNS_GENL_VERSION,
+ .hdrsize = 0,
+ .maxattr = NETNSA_MAX,
+ .netnsok = true,
+};
+
+static struct nla_policy netns_nl_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 netns_nl_cmd_newid(struct sk_buff *skb, struct genl_info *info)
+{
+ struct net *net = genl_info_net(info);
+ struct net *peer;
+ int nsid, err;
+
+ if (!info->attrs[NETNSA_NSID])
+ return -EINVAL;
+ nsid = nla_get_s32(info->attrs[NETNSA_NSID]);
+ if (nsid < 0)
+ return -EINVAL;
+
+ if (info->attrs[NETNSA_PID])
+ peer = get_net_ns_by_pid(nla_get_u32(info->attrs[NETNSA_PID]));
+ else if (info->attrs[NETNSA_FD])
+ peer = get_net_ns_by_fd(nla_get_u32(info->attrs[NETNSA_FD]));
+ else
+ return -EINVAL;
+ if (IS_ERR(peer))
+ return PTR_ERR(peer);
+
+ rtnl_lock();
+ if (peernet2id(net, peer) >= 0) {
+ err = -EEXIST;
+ goto out;
+ }
+
+ err = idr_alloc(&net->netns_ids, peer, nsid, nsid + 1, GFP_KERNEL);
+ if (err >= 0)
+ err = 0;
+out:
+ rtnl_unlock();
+ put_net(peer);
+ return err;
+}
+
+static int netns_nl_get_size(void)
+{
+ return nla_total_size(sizeof(s32)) /* NETNSA_NSID */
+ ;
+}
+
+static int netns_nl_fill(struct sk_buff *skb, u32 portid, u32 seq, int flags,
+ int cmd, struct net *net, struct net *peer)
+{
+ void *hdr;
+ int id;
+
+ hdr = genlmsg_put(skb, portid, seq, &netns_genl_family, flags, cmd);
+ if (!hdr)
+ return -EMSGSIZE;
+
+ rtnl_lock();
+ id = peernet2id(net, peer);
+ rtnl_unlock();
+ if (nla_put_s32(skb, NETNSA_NSID, id))
+ goto nla_put_failure;
+
+ return genlmsg_end(skb, hdr);
+
+nla_put_failure:
+ genlmsg_cancel(skb, hdr);
+ return -EMSGSIZE;
+}
+
+static int netns_nl_cmd_getid(struct sk_buff *skb, struct genl_info *info)
+{
+ struct net *net = genl_info_net(info);
+ struct sk_buff *msg;
+ int err = -ENOBUFS;
+ struct net *peer;
+
+ if (info->attrs[NETNSA_PID])
+ peer = get_net_ns_by_pid(nla_get_u32(info->attrs[NETNSA_PID]));
+ else if (info->attrs[NETNSA_FD])
+ peer = get_net_ns_by_fd(nla_get_u32(info->attrs[NETNSA_FD]));
+ else
+ return -EINVAL;
+
+ if (IS_ERR(peer))
+ return PTR_ERR(peer);
+
+ msg = genlmsg_new(netns_nl_get_size(), GFP_KERNEL);
+ if (!msg) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ err = netns_nl_fill(msg, info->snd_portid, info->snd_seq,
+ NLM_F_ACK, NETNS_CMD_GETID, net, peer);
+ if (err < 0)
+ goto err_out;
+
+ err = genlmsg_unicast(net, msg, info->snd_portid);
+ goto out;
+
+err_out:
+ nlmsg_free(msg);
+out:
+ put_net(peer);
+ return err;
+}
+
+static struct genl_ops netns_genl_ops[] = {
+ {
+ .cmd = NETNS_CMD_NEWID,
+ .policy = netns_nl_policy,
+ .doit = netns_nl_cmd_newid,
+ .flags = GENL_ADMIN_PERM,
+ },
+ {
+ .cmd = NETNS_CMD_GETID,
+ .policy = netns_nl_policy,
+ .doit = netns_nl_cmd_getid,
+ .flags = GENL_ADMIN_PERM,
+ },
+};
+
+int netns_genl_register(void)
+{
+ return genl_register_family_with_ops(&netns_genl_family,
+ netns_genl_ops);
+}
+
static int __init net_ns_init(void)
{
struct net_generic *ng;
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 76393f2f4b22..c6f39e40c9f3 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1029,6 +1029,10 @@ static int __init genl_init(void)
if (err)
goto problem;
+ err = netns_genl_register();
+ if (err < 0)
+ goto problem;
+
return 0;
problem:
--
2.1.0
--
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