linux/net/core/net_namespace.c
Daniel Borkmann f318903c0b bpf: Add netns cookie and enable it for bpf cgroup hooks
In Cilium we're mainly using BPF cgroup hooks today in order to implement
kube-proxy free Kubernetes service translation for ClusterIP, NodePort (*),
ExternalIP, and LoadBalancer as well as HostPort mapping [0] for all traffic
between Cilium managed nodes. While this works in its current shape and avoids
packet-level NAT for inter Cilium managed node traffic, there is one major
limitation we're facing today, that is, lack of netns awareness.

In Kubernetes, the concept of Pods (which hold one or multiple containers)
has been built around network namespaces, so while we can use the global scope
of attaching to root BPF cgroup hooks also to our advantage (e.g. for exposing
NodePort ports on loopback addresses), we also have the need to differentiate
between initial network namespaces and non-initial one. For example, ExternalIP
services mandate that non-local service IPs are not to be translated from the
host (initial) network namespace as one example. Right now, we have an ugly
work-around in place where non-local service IPs for ExternalIP services are
not xlated from connect() and friends BPF hooks but instead via less efficient
packet-level NAT on the veth tc ingress hook for Pod traffic.

On top of determining whether we're in initial or non-initial network namespace
we also have a need for a socket-cookie like mechanism for network namespaces
scope. Socket cookies have the nice property that they can be combined as part
of the key structure e.g. for BPF LRU maps without having to worry that the
cookie could be recycled. We are planning to use this for our sessionAffinity
implementation for services. Therefore, add a new bpf_get_netns_cookie() helper
which would resolve both use cases at once: bpf_get_netns_cookie(NULL) would
provide the cookie for the initial network namespace while passing the context
instead of NULL would provide the cookie from the application's network namespace.
We're using a hole, so no size increase; the assignment happens only once.
Therefore this allows for a comparison on initial namespace as well as regular
cookie usage as we have today with socket cookies. We could later on enable
this helper for other program types as well as we would see need.

  (*) Both externalTrafficPolicy={Local|Cluster} types
  [0] https://github.com/cilium/cilium/blob/master/bpf/bpf_sock.c

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/c47d2346982693a9cf9da0e12690453aded4c788.1585323121.git.daniel@iogearbox.net
2020-03-27 19:40:38 -07:00

1383 lines
32 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/workqueue.h>
#include <linux/rtnetlink.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <linux/rculist.h>
#include <linux/nsproxy.h>
#include <linux/fs.h>
#include <linux/proc_ns.h>
#include <linux/file.h>
#include <linux/export.h>
#include <linux/user_namespace.h>
#include <linux/net_namespace.h>
#include <linux/sched/task.h>
#include <linux/uidgid.h>
#include <net/sock.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
/*
* Our network namespace constructor/destructor lists
*/
static LIST_HEAD(pernet_list);
static struct list_head *first_device = &pernet_list;
LIST_HEAD(net_namespace_list);
EXPORT_SYMBOL_GPL(net_namespace_list);
/* Protects net_namespace_list. Nests iside rtnl_lock() */
DECLARE_RWSEM(net_rwsem);
EXPORT_SYMBOL_GPL(net_rwsem);
#ifdef CONFIG_KEYS
static struct key_tag init_net_key_domain = { .usage = REFCOUNT_INIT(1) };
#endif
struct net init_net = {
.count = REFCOUNT_INIT(1),
.dev_base_head = LIST_HEAD_INIT(init_net.dev_base_head),
#ifdef CONFIG_KEYS
.key_domain = &init_net_key_domain,
#endif
};
EXPORT_SYMBOL(init_net);
static bool init_net_initialized;
/*
* pernet_ops_rwsem: protects: pernet_list, net_generic_ids,
* init_net_initialized and first_device pointer.
* This is internal net namespace object. Please, don't use it
* outside.
*/
DECLARE_RWSEM(pernet_ops_rwsem);
EXPORT_SYMBOL_GPL(pernet_ops_rwsem);
#define MIN_PERNET_OPS_ID \
((sizeof(struct net_generic) + sizeof(void *) - 1) / sizeof(void *))
#define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */
static unsigned int max_gen_ptrs = INITIAL_NET_GEN_PTRS;
static atomic64_t cookie_gen;
u64 net_gen_cookie(struct net *net)
{
while (1) {
u64 res = atomic64_read(&net->net_cookie);
if (res)
return res;
res = atomic64_inc_return(&cookie_gen);
atomic64_cmpxchg(&net->net_cookie, 0, res);
}
}
static struct net_generic *net_alloc_generic(void)
{
struct net_generic *ng;
unsigned int generic_size = offsetof(struct net_generic, ptr[max_gen_ptrs]);
ng = kzalloc(generic_size, GFP_KERNEL);
if (ng)
ng->s.len = max_gen_ptrs;
return ng;
}
static int net_assign_generic(struct net *net, unsigned int id, void *data)
{
struct net_generic *ng, *old_ng;
BUG_ON(id < MIN_PERNET_OPS_ID);
old_ng = rcu_dereference_protected(net->gen,
lockdep_is_held(&pernet_ops_rwsem));
if (old_ng->s.len > id) {
old_ng->ptr[id] = data;
return 0;
}
ng = net_alloc_generic();
if (ng == NULL)
return -ENOMEM;
/*
* Some synchronisation notes:
*
* The net_generic explores the net->gen array inside rcu
* read section. Besides once set the net->gen->ptr[x]
* pointer never changes (see rules in netns/generic.h).
*
* That said, we simply duplicate this array and schedule
* the old copy for kfree after a grace period.
*/
memcpy(&ng->ptr[MIN_PERNET_OPS_ID], &old_ng->ptr[MIN_PERNET_OPS_ID],
(old_ng->s.len - MIN_PERNET_OPS_ID) * sizeof(void *));
ng->ptr[id] = data;
rcu_assign_pointer(net->gen, ng);
kfree_rcu(old_ng, s.rcu);
return 0;
}
static int ops_init(const struct pernet_operations *ops, struct net *net)
{
int err = -ENOMEM;
void *data = NULL;
if (ops->id && ops->size) {
data = kzalloc(ops->size, GFP_KERNEL);
if (!data)
goto out;
err = net_assign_generic(net, *ops->id, data);
if (err)
goto cleanup;
}
err = 0;
if (ops->init)
err = ops->init(net);
if (!err)
return 0;
cleanup:
kfree(data);
out:
return err;
}
static void ops_free(const struct pernet_operations *ops, struct net *net)
{
if (ops->id && ops->size) {
kfree(net_generic(net, *ops->id));
}
}
static void ops_pre_exit_list(const struct pernet_operations *ops,
struct list_head *net_exit_list)
{
struct net *net;
if (ops->pre_exit) {
list_for_each_entry(net, net_exit_list, exit_list)
ops->pre_exit(net);
}
}
static void ops_exit_list(const struct pernet_operations *ops,
struct list_head *net_exit_list)
{
struct net *net;
if (ops->exit) {
list_for_each_entry(net, net_exit_list, exit_list)
ops->exit(net);
}
if (ops->exit_batch)
ops->exit_batch(net_exit_list);
}
static void ops_free_list(const struct pernet_operations *ops,
struct list_head *net_exit_list)
{
struct net *net;
if (ops->size && ops->id) {
list_for_each_entry(net, net_exit_list, exit_list)
ops_free(ops, net);
}
}
/* should be called with nsid_lock held */
static int alloc_netid(struct net *net, struct net *peer, int reqid)
{
int min = 0, max = 0;
if (reqid >= 0) {
min = reqid;
max = reqid + 1;
}
return idr_alloc(&net->netns_ids, peer, min, max, GFP_ATOMIC);
}
/* 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;
}
/* Must be called from RCU-critical section or with nsid_lock held */
static int __peernet2id(const struct net *net, struct net *peer)
{
int id = idr_for_each(&net->netns_ids, net_eq_idr, peer);
/* Magic value for id 0. */
if (id == NET_ID_ZERO)
return 0;
if (id > 0)
return id;
return NETNSA_NSID_NOT_ASSIGNED;
}
static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
struct nlmsghdr *nlh, gfp_t gfp);
/* This function returns the id of a peer netns. If no id is assigned, one will
* be allocated and returned.
*/
int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
{
int id;
if (refcount_read(&net->count) == 0)
return NETNSA_NSID_NOT_ASSIGNED;
spin_lock(&net->nsid_lock);
id = __peernet2id(net, peer);
if (id >= 0) {
spin_unlock(&net->nsid_lock);
return id;
}
/* When peer is obtained from RCU lists, we may race with
* its cleanup. Check whether it's alive, and this guarantees
* we never hash a peer back to net->netns_ids, after it has
* just been idr_remove()'d from there in cleanup_net().
*/
if (!maybe_get_net(peer)) {
spin_unlock(&net->nsid_lock);
return NETNSA_NSID_NOT_ASSIGNED;
}
id = alloc_netid(net, peer, -1);
spin_unlock(&net->nsid_lock);
put_net(peer);
if (id < 0)
return NETNSA_NSID_NOT_ASSIGNED;
rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
return id;
}
EXPORT_SYMBOL_GPL(peernet2id_alloc);
/* This function returns, if assigned, the id of a peer netns. */
int peernet2id(const struct net *net, struct net *peer)
{
int id;
rcu_read_lock();
id = __peernet2id(net, peer);
rcu_read_unlock();
return id;
}
EXPORT_SYMBOL(peernet2id);
/* This function returns true is the peer netns has an id assigned into the
* current netns.
*/
bool peernet_has_id(const struct net *net, struct net *peer)
{
return peernet2id(net, peer) >= 0;
}
struct net *get_net_ns_by_id(const 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)
peer = maybe_get_net(peer);
rcu_read_unlock();
return peer;
}
/*
* setup_net runs the initializers for the network namespace object.
*/
static __net_init int setup_net(struct net *net, struct user_namespace *user_ns)
{
/* Must be called with pernet_ops_rwsem held */
const struct pernet_operations *ops, *saved_ops;
int error = 0;
LIST_HEAD(net_exit_list);
refcount_set(&net->count, 1);
refcount_set(&net->passive, 1);
get_random_bytes(&net->hash_mix, sizeof(u32));
net->dev_base_seq = 1;
net->user_ns = user_ns;
idr_init(&net->netns_ids);
spin_lock_init(&net->nsid_lock);
mutex_init(&net->ipv4.ra_mutex);
list_for_each_entry(ops, &pernet_list, list) {
error = ops_init(ops, net);
if (error < 0)
goto out_undo;
}
down_write(&net_rwsem);
list_add_tail_rcu(&net->list, &net_namespace_list);
up_write(&net_rwsem);
out:
return error;
out_undo:
/* Walk through the list backwards calling the exit functions
* for the pernet modules whose init functions did not fail.
*/
list_add(&net->exit_list, &net_exit_list);
saved_ops = ops;
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_pre_exit_list(ops, &net_exit_list);
synchronize_rcu();
ops = saved_ops;
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_exit_list(ops, &net_exit_list);
ops = saved_ops;
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_free_list(ops, &net_exit_list);
rcu_barrier();
goto out;
}
static int __net_init net_defaults_init_net(struct net *net)
{
net->core.sysctl_somaxconn = SOMAXCONN;
return 0;
}
static struct pernet_operations net_defaults_ops = {
.init = net_defaults_init_net,
};
static __init int net_defaults_init(void)
{
if (register_pernet_subsys(&net_defaults_ops))
panic("Cannot initialize net default settings");
return 0;
}
core_initcall(net_defaults_init);
#ifdef CONFIG_NET_NS
static struct ucounts *inc_net_namespaces(struct user_namespace *ns)
{
return inc_ucount(ns, current_euid(), UCOUNT_NET_NAMESPACES);
}
static void dec_net_namespaces(struct ucounts *ucounts)
{
dec_ucount(ucounts, UCOUNT_NET_NAMESPACES);
}
static struct kmem_cache *net_cachep __ro_after_init;
static struct workqueue_struct *netns_wq;
static struct net *net_alloc(void)
{
struct net *net = NULL;
struct net_generic *ng;
ng = net_alloc_generic();
if (!ng)
goto out;
net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
if (!net)
goto out_free;
#ifdef CONFIG_KEYS
net->key_domain = kzalloc(sizeof(struct key_tag), GFP_KERNEL);
if (!net->key_domain)
goto out_free_2;
refcount_set(&net->key_domain->usage, 1);
#endif
rcu_assign_pointer(net->gen, ng);
out:
return net;
#ifdef CONFIG_KEYS
out_free_2:
kmem_cache_free(net_cachep, net);
net = NULL;
#endif
out_free:
kfree(ng);
goto out;
}
static void net_free(struct net *net)
{
kfree(rcu_access_pointer(net->gen));
kmem_cache_free(net_cachep, net);
}
void net_drop_ns(void *p)
{
struct net *ns = p;
if (ns && refcount_dec_and_test(&ns->passive))
net_free(ns);
}
struct net *copy_net_ns(unsigned long flags,
struct user_namespace *user_ns, struct net *old_net)
{
struct ucounts *ucounts;
struct net *net;
int rv;
if (!(flags & CLONE_NEWNET))
return get_net(old_net);
ucounts = inc_net_namespaces(user_ns);
if (!ucounts)
return ERR_PTR(-ENOSPC);
net = net_alloc();
if (!net) {
rv = -ENOMEM;
goto dec_ucounts;
}
refcount_set(&net->passive, 1);
net->ucounts = ucounts;
get_user_ns(user_ns);
rv = down_read_killable(&pernet_ops_rwsem);
if (rv < 0)
goto put_userns;
rv = setup_net(net, user_ns);
up_read(&pernet_ops_rwsem);
if (rv < 0) {
put_userns:
key_remove_domain(net->key_domain);
put_user_ns(user_ns);
net_drop_ns(net);
dec_ucounts:
dec_net_namespaces(ucounts);
return ERR_PTR(rv);
}
return net;
}
/**
* net_ns_get_ownership - get sysfs ownership data for @net
* @net: network namespace in question (can be NULL)
* @uid: kernel user ID for sysfs objects
* @gid: kernel group ID for sysfs objects
*
* Returns the uid/gid pair of root in the user namespace associated with the
* given network namespace.
*/
void net_ns_get_ownership(const struct net *net, kuid_t *uid, kgid_t *gid)
{
if (net) {
kuid_t ns_root_uid = make_kuid(net->user_ns, 0);
kgid_t ns_root_gid = make_kgid(net->user_ns, 0);
if (uid_valid(ns_root_uid))
*uid = ns_root_uid;
if (gid_valid(ns_root_gid))
*gid = ns_root_gid;
} else {
*uid = GLOBAL_ROOT_UID;
*gid = GLOBAL_ROOT_GID;
}
}
EXPORT_SYMBOL_GPL(net_ns_get_ownership);
static void unhash_nsid(struct net *net, struct net *last)
{
struct net *tmp;
/* This function is only called from cleanup_net() work,
* and this work is the only process, that may delete
* a net from net_namespace_list. So, when the below
* is executing, the list may only grow. Thus, we do not
* use for_each_net_rcu() or net_rwsem.
*/
for_each_net(tmp) {
int id;
spin_lock(&tmp->nsid_lock);
id = __peernet2id(tmp, net);
if (id >= 0)
idr_remove(&tmp->netns_ids, id);
spin_unlock(&tmp->nsid_lock);
if (id >= 0)
rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
GFP_KERNEL);
if (tmp == last)
break;
}
spin_lock(&net->nsid_lock);
idr_destroy(&net->netns_ids);
spin_unlock(&net->nsid_lock);
}
static LLIST_HEAD(cleanup_list);
static void cleanup_net(struct work_struct *work)
{
const struct pernet_operations *ops;
struct net *net, *tmp, *last;
struct llist_node *net_kill_list;
LIST_HEAD(net_exit_list);
/* Atomically snapshot the list of namespaces to cleanup */
net_kill_list = llist_del_all(&cleanup_list);
down_read(&pernet_ops_rwsem);
/* Don't let anyone else find us. */
down_write(&net_rwsem);
llist_for_each_entry(net, net_kill_list, cleanup_list)
list_del_rcu(&net->list);
/* Cache last net. After we unlock rtnl, no one new net
* added to net_namespace_list can assign nsid pointer
* to a net from net_kill_list (see peernet2id_alloc()).
* So, we skip them in unhash_nsid().
*
* Note, that unhash_nsid() does not delete nsid links
* between net_kill_list's nets, as they've already
* deleted from net_namespace_list. But, this would be
* useless anyway, as netns_ids are destroyed there.
*/
last = list_last_entry(&net_namespace_list, struct net, list);
up_write(&net_rwsem);
llist_for_each_entry(net, net_kill_list, cleanup_list) {
unhash_nsid(net, last);
list_add_tail(&net->exit_list, &net_exit_list);
}
/* Run all of the network namespace pre_exit methods */
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_pre_exit_list(ops, &net_exit_list);
/*
* Another CPU might be rcu-iterating the list, wait for it.
* This needs to be before calling the exit() notifiers, so
* the rcu_barrier() below isn't sufficient alone.
* Also the pre_exit() and exit() methods need this barrier.
*/
synchronize_rcu();
/* Run all of the network namespace exit methods */
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_exit_list(ops, &net_exit_list);
/* Free the net generic variables */
list_for_each_entry_reverse(ops, &pernet_list, list)
ops_free_list(ops, &net_exit_list);
up_read(&pernet_ops_rwsem);
/* Ensure there are no outstanding rcu callbacks using this
* network namespace.
*/
rcu_barrier();
/* Finally it is safe to free my network namespace structure */
list_for_each_entry_safe(net, tmp, &net_exit_list, exit_list) {
list_del_init(&net->exit_list);
dec_net_namespaces(net->ucounts);
key_remove_domain(net->key_domain);
put_user_ns(net->user_ns);
net_drop_ns(net);
}
}
/**
* net_ns_barrier - wait until concurrent net_cleanup_work is done
*
* cleanup_net runs from work queue and will first remove namespaces
* from the global list, then run net exit functions.
*
* Call this in module exit path to make sure that all netns
* ->exit ops have been invoked before the function is removed.
*/
void net_ns_barrier(void)
{
down_write(&pernet_ops_rwsem);
up_write(&pernet_ops_rwsem);
}
EXPORT_SYMBOL(net_ns_barrier);
static DECLARE_WORK(net_cleanup_work, cleanup_net);
void __put_net(struct net *net)
{
/* Cleanup the network namespace in process context */
if (llist_add(&net->cleanup_list, &cleanup_list))
queue_work(netns_wq, &net_cleanup_work);
}
EXPORT_SYMBOL_GPL(__put_net);
struct net *get_net_ns_by_fd(int fd)
{
struct file *file;
struct ns_common *ns;
struct net *net;
file = proc_ns_fget(fd);
if (IS_ERR(file))
return ERR_CAST(file);
ns = get_proc_ns(file_inode(file));
if (ns->ops == &netns_operations)
net = get_net(container_of(ns, struct net, ns));
else
net = ERR_PTR(-EINVAL);
fput(file);
return net;
}
#else
struct net *get_net_ns_by_fd(int fd)
{
return ERR_PTR(-EINVAL);
}
#endif
EXPORT_SYMBOL_GPL(get_net_ns_by_fd);
struct net *get_net_ns_by_pid(pid_t pid)
{
struct task_struct *tsk;
struct net *net;
/* Lookup the network namespace */
net = ERR_PTR(-ESRCH);
rcu_read_lock();
tsk = find_task_by_vpid(pid);
if (tsk) {
struct nsproxy *nsproxy;
task_lock(tsk);
nsproxy = tsk->nsproxy;
if (nsproxy)
net = get_net(nsproxy->net_ns);
task_unlock(tsk);
}
rcu_read_unlock();
return net;
}
EXPORT_SYMBOL_GPL(get_net_ns_by_pid);
static __net_init int net_ns_net_init(struct net *net)
{
#ifdef CONFIG_NET_NS
net->ns.ops = &netns_operations;
#endif
return ns_alloc_inum(&net->ns);
}
static __net_exit void net_ns_net_exit(struct net *net)
{
ns_free_inum(&net->ns);
}
static struct pernet_operations __net_initdata net_ns_ops = {
.init = net_ns_net_init,
.exit = net_ns_net_exit,
};
static const 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 },
[NETNSA_TARGET_NSID] = { .type = NLA_S32 },
};
static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[NETNSA_MAX + 1];
struct nlattr *nla;
struct net *peer;
int nsid, err;
err = nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg), tb,
NETNSA_MAX, rtnl_net_policy, extack);
if (err < 0)
return err;
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]) {
peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
nla = tb[NETNSA_PID];
} else if (tb[NETNSA_FD]) {
peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
nla = tb[NETNSA_FD];
} else {
NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
return -EINVAL;
}
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(&net->nsid_lock);
if (__peernet2id(net, peer) >= 0) {
spin_unlock(&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;
}
err = alloc_netid(net, peer, nsid);
spin_unlock(&net->nsid_lock);
if (err >= 0) {
rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
nlh, GFP_KERNEL);
err = 0;
} else if (err == -ENOSPC && nsid >= 0) {
err = -EEXIST;
NL_SET_BAD_ATTR(extack, tb[NETNSA_NSID]);
NL_SET_ERR_MSG(extack, "The specified nsid is already used");
}
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 */
+ nla_total_size(sizeof(s32)) /* NETNSA_CURRENT_NSID */
;
}
struct net_fill_args {
u32 portid;
u32 seq;
int flags;
int cmd;
int nsid;
bool add_ref;
int ref_nsid;
};
static int rtnl_net_fill(struct sk_buff *skb, struct net_fill_args *args)
{
struct nlmsghdr *nlh;
struct rtgenmsg *rth;
nlh = nlmsg_put(skb, args->portid, args->seq, args->cmd, sizeof(*rth),
args->flags);
if (!nlh)
return -EMSGSIZE;
rth = nlmsg_data(nlh);
rth->rtgen_family = AF_UNSPEC;
if (nla_put_s32(skb, NETNSA_NSID, args->nsid))
goto nla_put_failure;
if (args->add_ref &&
nla_put_s32(skb, NETNSA_CURRENT_NSID, args->ref_nsid))
goto nla_put_failure;
nlmsg_end(skb, nlh);
return 0;
nla_put_failure:
nlmsg_cancel(skb, nlh);
return -EMSGSIZE;
}
static int rtnl_net_valid_getid_req(struct sk_buff *skb,
const struct nlmsghdr *nlh,
struct nlattr **tb,
struct netlink_ext_ack *extack)
{
int i, err;
if (!netlink_strict_get_check(skb))
return nlmsg_parse_deprecated(nlh, sizeof(struct rtgenmsg),
tb, NETNSA_MAX, rtnl_net_policy,
extack);
err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
NETNSA_MAX, rtnl_net_policy,
extack);
if (err)
return err;
for (i = 0; i <= NETNSA_MAX; i++) {
if (!tb[i])
continue;
switch (i) {
case NETNSA_PID:
case NETNSA_FD:
case NETNSA_NSID:
case NETNSA_TARGET_NSID:
break;
default:
NL_SET_ERR_MSG(extack, "Unsupported attribute in peer netns getid request");
return -EINVAL;
}
}
return 0;
}
static int rtnl_net_getid(struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack)
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[NETNSA_MAX + 1];
struct net_fill_args fillargs = {
.portid = NETLINK_CB(skb).portid,
.seq = nlh->nlmsg_seq,
.cmd = RTM_NEWNSID,
};
struct net *peer, *target = net;
struct nlattr *nla;
struct sk_buff *msg;
int err;
err = rtnl_net_valid_getid_req(skb, nlh, tb, extack);
if (err < 0)
return err;
if (tb[NETNSA_PID]) {
peer = get_net_ns_by_pid(nla_get_u32(tb[NETNSA_PID]));
nla = tb[NETNSA_PID];
} else if (tb[NETNSA_FD]) {
peer = get_net_ns_by_fd(nla_get_u32(tb[NETNSA_FD]));
nla = tb[NETNSA_FD];
} else if (tb[NETNSA_NSID]) {
peer = get_net_ns_by_id(net, nla_get_s32(tb[NETNSA_NSID]));
if (!peer)
peer = ERR_PTR(-ENOENT);
nla = tb[NETNSA_NSID];
} else {
NL_SET_ERR_MSG(extack, "Peer netns reference is missing");
return -EINVAL;
}
if (IS_ERR(peer)) {
NL_SET_BAD_ATTR(extack, nla);
NL_SET_ERR_MSG(extack, "Peer netns reference is invalid");
return PTR_ERR(peer);
}
if (tb[NETNSA_TARGET_NSID]) {
int id = nla_get_s32(tb[NETNSA_TARGET_NSID]);
target = rtnl_get_net_ns_capable(NETLINK_CB(skb).sk, id);
if (IS_ERR(target)) {
NL_SET_BAD_ATTR(extack, tb[NETNSA_TARGET_NSID]);
NL_SET_ERR_MSG(extack,
"Target netns reference is invalid");
err = PTR_ERR(target);
goto out;
}
fillargs.add_ref = true;
fillargs.ref_nsid = peernet2id(net, peer);
}
msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
if (!msg) {
err = -ENOMEM;
goto out;
}
fillargs.nsid = peernet2id(target, peer);
err = rtnl_net_fill(msg, &fillargs);
if (err < 0)
goto err_out;
err = rtnl_unicast(msg, net, NETLINK_CB(skb).portid);
goto out;
err_out:
nlmsg_free(msg);
out:
if (fillargs.add_ref)
put_net(target);
put_net(peer);
return err;
}
struct rtnl_net_dump_cb {
struct net *tgt_net;
struct net *ref_net;
struct sk_buff *skb;
struct net_fill_args fillargs;
int idx;
int s_idx;
};
/* Runs in RCU-critical section. */
static int rtnl_net_dumpid_one(int id, void *peer, void *data)
{
struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data;
int ret;
if (net_cb->idx < net_cb->s_idx)
goto cont;
net_cb->fillargs.nsid = id;
if (net_cb->fillargs.add_ref)
net_cb->fillargs.ref_nsid = __peernet2id(net_cb->ref_net, peer);
ret = rtnl_net_fill(net_cb->skb, &net_cb->fillargs);
if (ret < 0)
return ret;
cont:
net_cb->idx++;
return 0;
}
static int rtnl_valid_dump_net_req(const struct nlmsghdr *nlh, struct sock *sk,
struct rtnl_net_dump_cb *net_cb,
struct netlink_callback *cb)
{
struct netlink_ext_ack *extack = cb->extack;
struct nlattr *tb[NETNSA_MAX + 1];
int err, i;
err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct rtgenmsg), tb,
NETNSA_MAX, rtnl_net_policy,
extack);
if (err < 0)
return err;
for (i = 0; i <= NETNSA_MAX; i++) {
if (!tb[i])
continue;
if (i == NETNSA_TARGET_NSID) {
struct net *net;
net = rtnl_get_net_ns_capable(sk, nla_get_s32(tb[i]));
if (IS_ERR(net)) {
NL_SET_BAD_ATTR(extack, tb[i]);
NL_SET_ERR_MSG(extack,
"Invalid target network namespace id");
return PTR_ERR(net);
}
net_cb->fillargs.add_ref = true;
net_cb->ref_net = net_cb->tgt_net;
net_cb->tgt_net = net;
} else {
NL_SET_BAD_ATTR(extack, tb[i]);
NL_SET_ERR_MSG(extack,
"Unsupported attribute in dump request");
return -EINVAL;
}
}
return 0;
}
static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
{
struct rtnl_net_dump_cb net_cb = {
.tgt_net = sock_net(skb->sk),
.skb = skb,
.fillargs = {
.portid = NETLINK_CB(cb->skb).portid,
.seq = cb->nlh->nlmsg_seq,
.flags = NLM_F_MULTI,
.cmd = RTM_NEWNSID,
},
.idx = 0,
.s_idx = cb->args[0],
};
int err = 0;
if (cb->strict_check) {
err = rtnl_valid_dump_net_req(cb->nlh, skb->sk, &net_cb, cb);
if (err < 0)
goto end;
}
rcu_read_lock();
idr_for_each(&net_cb.tgt_net->netns_ids, rtnl_net_dumpid_one, &net_cb);
rcu_read_unlock();
cb->args[0] = net_cb.idx;
end:
if (net_cb.fillargs.add_ref)
put_net(net_cb.tgt_net);
return err < 0 ? err : skb->len;
}
static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
struct nlmsghdr *nlh, gfp_t gfp)
{
struct net_fill_args fillargs = {
.portid = portid,
.seq = nlh ? nlh->nlmsg_seq : 0,
.cmd = cmd,
.nsid = id,
};
struct sk_buff *msg;
int err = -ENOMEM;
msg = nlmsg_new(rtnl_net_get_size(), gfp);
if (!msg)
goto out;
err = rtnl_net_fill(msg, &fillargs);
if (err < 0)
goto err_out;
rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, gfp);
return;
err_out:
nlmsg_free(msg);
out:
rtnl_set_sk_err(net, RTNLGRP_NSID, err);
}
static int __init net_ns_init(void)
{
struct net_generic *ng;
#ifdef CONFIG_NET_NS
net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
SMP_CACHE_BYTES,
SLAB_PANIC|SLAB_ACCOUNT, NULL);
/* Create workqueue for cleanup */
netns_wq = create_singlethread_workqueue("netns");
if (!netns_wq)
panic("Could not create netns workq");
#endif
ng = net_alloc_generic();
if (!ng)
panic("Could not allocate generic netns");
rcu_assign_pointer(init_net.gen, ng);
net_gen_cookie(&init_net);
down_write(&pernet_ops_rwsem);
if (setup_net(&init_net, &init_user_ns))
panic("Could not setup the initial network namespace");
init_net_initialized = true;
up_write(&pernet_ops_rwsem);
if (register_pernet_subsys(&net_ns_ops))
panic("Could not register network namespace subsystems");
rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL,
RTNL_FLAG_DOIT_UNLOCKED);
rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
RTNL_FLAG_DOIT_UNLOCKED);
return 0;
}
pure_initcall(net_ns_init);
#ifdef CONFIG_NET_NS
static int __register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
struct net *net;
int error;
LIST_HEAD(net_exit_list);
list_add_tail(&ops->list, list);
if (ops->init || (ops->id && ops->size)) {
/* We held write locked pernet_ops_rwsem, and parallel
* setup_net() and cleanup_net() are not possible.
*/
for_each_net(net) {
error = ops_init(ops, net);
if (error)
goto out_undo;
list_add_tail(&net->exit_list, &net_exit_list);
}
}
return 0;
out_undo:
/* If I have an error cleanup all namespaces I initialized */
list_del(&ops->list);
ops_pre_exit_list(ops, &net_exit_list);
synchronize_rcu();
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
return error;
}
static void __unregister_pernet_operations(struct pernet_operations *ops)
{
struct net *net;
LIST_HEAD(net_exit_list);
list_del(&ops->list);
/* See comment in __register_pernet_operations() */
for_each_net(net)
list_add_tail(&net->exit_list, &net_exit_list);
ops_pre_exit_list(ops, &net_exit_list);
synchronize_rcu();
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
}
#else
static int __register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
if (!init_net_initialized) {
list_add_tail(&ops->list, list);
return 0;
}
return ops_init(ops, &init_net);
}
static void __unregister_pernet_operations(struct pernet_operations *ops)
{
if (!init_net_initialized) {
list_del(&ops->list);
} else {
LIST_HEAD(net_exit_list);
list_add(&init_net.exit_list, &net_exit_list);
ops_pre_exit_list(ops, &net_exit_list);
synchronize_rcu();
ops_exit_list(ops, &net_exit_list);
ops_free_list(ops, &net_exit_list);
}
}
#endif /* CONFIG_NET_NS */
static DEFINE_IDA(net_generic_ids);
static int register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
int error;
if (ops->id) {
error = ida_alloc_min(&net_generic_ids, MIN_PERNET_OPS_ID,
GFP_KERNEL);
if (error < 0)
return error;
*ops->id = error;
max_gen_ptrs = max(max_gen_ptrs, *ops->id + 1);
}
error = __register_pernet_operations(list, ops);
if (error) {
rcu_barrier();
if (ops->id)
ida_free(&net_generic_ids, *ops->id);
}
return error;
}
static void unregister_pernet_operations(struct pernet_operations *ops)
{
__unregister_pernet_operations(ops);
rcu_barrier();
if (ops->id)
ida_free(&net_generic_ids, *ops->id);
}
/**
* register_pernet_subsys - register a network namespace subsystem
* @ops: pernet operations structure for the subsystem
*
* Register a subsystem which has init and exit functions
* that are called when network namespaces are created and
* destroyed respectively.
*
* When registered all network namespace init functions are
* called for every existing network namespace. Allowing kernel
* modules to have a race free view of the set of network namespaces.
*
* When a new network namespace is created all of the init
* methods are called in the order in which they were registered.
*
* When a network namespace is destroyed all of the exit methods
* are called in the reverse of the order with which they were
* registered.
*/
int register_pernet_subsys(struct pernet_operations *ops)
{
int error;
down_write(&pernet_ops_rwsem);
error = register_pernet_operations(first_device, ops);
up_write(&pernet_ops_rwsem);
return error;
}
EXPORT_SYMBOL_GPL(register_pernet_subsys);
/**
* unregister_pernet_subsys - unregister a network namespace subsystem
* @ops: pernet operations structure to manipulate
*
* Remove the pernet operations structure from the list to be
* used when network namespaces are created or destroyed. In
* addition run the exit method for all existing network
* namespaces.
*/
void unregister_pernet_subsys(struct pernet_operations *ops)
{
down_write(&pernet_ops_rwsem);
unregister_pernet_operations(ops);
up_write(&pernet_ops_rwsem);
}
EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
/**
* register_pernet_device - register a network namespace device
* @ops: pernet operations structure for the subsystem
*
* Register a device which has init and exit functions
* that are called when network namespaces are created and
* destroyed respectively.
*
* When registered all network namespace init functions are
* called for every existing network namespace. Allowing kernel
* modules to have a race free view of the set of network namespaces.
*
* When a new network namespace is created all of the init
* methods are called in the order in which they were registered.
*
* When a network namespace is destroyed all of the exit methods
* are called in the reverse of the order with which they were
* registered.
*/
int register_pernet_device(struct pernet_operations *ops)
{
int error;
down_write(&pernet_ops_rwsem);
error = register_pernet_operations(&pernet_list, ops);
if (!error && (first_device == &pernet_list))
first_device = &ops->list;
up_write(&pernet_ops_rwsem);
return error;
}
EXPORT_SYMBOL_GPL(register_pernet_device);
/**
* unregister_pernet_device - unregister a network namespace netdevice
* @ops: pernet operations structure to manipulate
*
* Remove the pernet operations structure from the list to be
* used when network namespaces are created or destroyed. In
* addition run the exit method for all existing network
* namespaces.
*/
void unregister_pernet_device(struct pernet_operations *ops)
{
down_write(&pernet_ops_rwsem);
if (&ops->list == first_device)
first_device = first_device->next;
unregister_pernet_operations(ops);
up_write(&pernet_ops_rwsem);
}
EXPORT_SYMBOL_GPL(unregister_pernet_device);
#ifdef CONFIG_NET_NS
static struct ns_common *netns_get(struct task_struct *task)
{
struct net *net = NULL;
struct nsproxy *nsproxy;
task_lock(task);
nsproxy = task->nsproxy;
if (nsproxy)
net = get_net(nsproxy->net_ns);
task_unlock(task);
return net ? &net->ns : NULL;
}
static inline struct net *to_net_ns(struct ns_common *ns)
{
return container_of(ns, struct net, ns);
}
static void netns_put(struct ns_common *ns)
{
put_net(to_net_ns(ns));
}
static int netns_install(struct nsproxy *nsproxy, struct ns_common *ns)
{
struct net *net = to_net_ns(ns);
if (!ns_capable(net->user_ns, CAP_SYS_ADMIN) ||
!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
return -EPERM;
put_net(nsproxy->net_ns);
nsproxy->net_ns = get_net(net);
return 0;
}
static struct user_namespace *netns_owner(struct ns_common *ns)
{
return to_net_ns(ns)->user_ns;
}
const struct proc_ns_operations netns_operations = {
.name = "net",
.type = CLONE_NEWNET,
.get = netns_get,
.put = netns_put,
.install = netns_install,
.owner = netns_owner,
};
#endif