[RFC PATCH net-next v2 2/5] netns: add genl cmd to get the id of a netns
Nicolas Dichtel
nicolas.dichtel at 6wind.com
Tue Sep 23 13:20:27 UTC 2014
This patch allows a user to get an id of a peer netns. It will be usefull for
userland to be able to associate a netns file descriptor with a netns id.
Note: to be able to got an id, both netns should be in the same user ns.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
---
MAINTAINERS | 1 +
include/net/net_namespace.h | 1 +
include/uapi/linux/Kbuild | 1 +
include/uapi/linux/netns.h | 29 +++++++++++++
net/core/net_namespace.c | 99 +++++++++++++++++++++++++++++++++++++++++++++
net/netlink/genetlink.c | 4 ++
6 files changed, 135 insertions(+)
create mode 100644 include/uapi/linux/netns.h
diff --git a/MAINTAINERS b/MAINTAINERS
index b4e23acc6441..dbf691c68473 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6278,6 +6278,7 @@ 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 92b5f94e2842..1b65f5ccacf5 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -299,6 +299,7 @@ static inline int peernet2id(struct net *net, struct net *peer)
}
struct net *get_net_from_netnsid(struct net *net, int id);
+int netns_genl_register(void);
struct pernet_operations {
struct list_head list;
diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
index fb3f7b675229..840f049c48fa 100644
--- a/include/uapi/linux/Kbuild
+++ b/include/uapi/linux/Kbuild
@@ -275,6 +275,7 @@ 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..72537e31d7d2
--- /dev/null
+++ b/include/uapi/linux/netns.h
@@ -0,0 +1,29 @@
+#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_GET,
+ __NETNS_CMD_MAX,
+};
+
+#define NETNS_CMD_MAX (__NETNS_CMD_MAX - 1)
+
+/* Attributes */
+enum {
+ NETNSA_NONE,
+ NETNSA_NSINDEX,
+ 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 f44378de7831..a60f2bbf4302 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>
@@ -417,6 +419,103 @@ static struct pernet_operations __net_initdata net_ns_ops = {
.exit = net_ns_net_exit,
};
+static struct genl_family netns_nl_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_NSINDEX] = { .type = NLA_U32, },
+ [NETNSA_PID] = { .type = NLA_U32 },
+ [NETNSA_FD] = { .type = NLA_U32 },
+};
+
+static int netns_nl_get_size(void)
+{
+ return nla_total_size(sizeof(u32)) /* NETNSA_NSINDEX */
+ ;
+}
+
+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_nl_family, flags, cmd);
+ if (!hdr)
+ return -EMSGSIZE;
+
+ id = peernet2id(net, peer);
+ if (id < 0)
+ return id;
+ if (nla_put_u32(skb, NETNSA_NSINDEX, 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 net *peer;
+ struct sk_buff *msg;
+ int err = -ENOBUFS;
+
+ 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_nl_ops[] = {
+ {
+ .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_nl_family, netns_nl_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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