[PATCH net-next v4 1/4] netns: add genl cmd to add and get peer netns ids
Eric W. Biederman
ebiederm at xmission.com
Thu Oct 30 18:35:31 UTC 2014
Nicolas Dichtel <nicolas.dichtel at 6wind.com> writes:
> 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).
Scratches head. Do you actually find value in using the pid instead of
a file descriptor?
Doing things by pid was an early attempt to make things work, and has
been a bit clutsy. If you don't find value in it I would recommend just
supporting getting/setting the network namespace by file descriptor.
Eric
> This will be useful for netlink messages when a x-netns interface is dumped.
>
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel at 6wind.com>
> ---
> 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 at 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_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:
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