swh:1:snp:3c665ee4f67729f27f2e40193ab88e7298cf0fef
Tip revision: b3a9e3b9622ae10064826dccb4f7a52bd88c7407 authored by Linus Torvalds on 14 June 2020, 19:45:04 UTC
Linux 5.8-rc1
Linux 5.8-rc1
Tip revision: b3a9e3b
net_namespace.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <linux/filter.h>
#include <net/net_namespace.h>
/*
* Functions to manage BPF programs attached to netns
*/
struct bpf_netns_link {
struct bpf_link link;
enum bpf_attach_type type;
enum netns_bpf_attach_type netns_type;
/* We don't hold a ref to net in order to auto-detach the link
* when netns is going away. Instead we rely on pernet
* pre_exit callback to clear this pointer. Must be accessed
* with netns_bpf_mutex held.
*/
struct net *net;
};
/* Protects updates to netns_bpf */
DEFINE_MUTEX(netns_bpf_mutex);
/* Must be called with netns_bpf_mutex held. */
static void __net_exit bpf_netns_link_auto_detach(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
net_link->net = NULL;
}
static void bpf_netns_link_release(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
enum netns_bpf_attach_type type = net_link->netns_type;
struct net *net;
/* Link auto-detached by dying netns. */
if (!net_link->net)
return;
mutex_lock(&netns_bpf_mutex);
/* Recheck after potential sleep. We can race with cleanup_net
* here, but if we see a non-NULL struct net pointer pre_exit
* has not happened yet and will block on netns_bpf_mutex.
*/
net = net_link->net;
if (!net)
goto out_unlock;
net->bpf.links[type] = NULL;
RCU_INIT_POINTER(net->bpf.progs[type], NULL);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
}
static void bpf_netns_link_dealloc(struct bpf_link *link)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
kfree(net_link);
}
static int bpf_netns_link_update_prog(struct bpf_link *link,
struct bpf_prog *new_prog,
struct bpf_prog *old_prog)
{
struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
enum netns_bpf_attach_type type = net_link->netns_type;
struct net *net;
int ret = 0;
if (old_prog && old_prog != link->prog)
return -EPERM;
if (new_prog->type != link->prog->type)
return -EINVAL;
mutex_lock(&netns_bpf_mutex);
net = net_link->net;
if (!net || !check_net(net)) {
/* Link auto-detached or netns dying */
ret = -ENOLINK;
goto out_unlock;
}
old_prog = xchg(&link->prog, new_prog);
rcu_assign_pointer(net->bpf.progs[type], new_prog);
bpf_prog_put(old_prog);
out_unlock:
mutex_unlock(&netns_bpf_mutex);
return ret;
}
static int bpf_netns_link_fill_info(const struct bpf_link *link,
struct bpf_link_info *info)
{
const struct bpf_netns_link *net_link =
container_of(link, struct bpf_netns_link, link);
unsigned int inum = 0;
struct net *net;
mutex_lock(&netns_bpf_mutex);
net = net_link->net;
if (net && check_net(net))
inum = net->ns.inum;
mutex_unlock(&netns_bpf_mutex);
info->netns.netns_ino = inum;
info->netns.attach_type = net_link->type;
return 0;
}
static void bpf_netns_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
struct bpf_link_info info = {};
bpf_netns_link_fill_info(link, &info);
seq_printf(seq,
"netns_ino:\t%u\n"
"attach_type:\t%u\n",
info.netns.netns_ino,
info.netns.attach_type);
}
static const struct bpf_link_ops bpf_netns_link_ops = {
.release = bpf_netns_link_release,
.dealloc = bpf_netns_link_dealloc,
.update_prog = bpf_netns_link_update_prog,
.fill_link_info = bpf_netns_link_fill_info,
.show_fdinfo = bpf_netns_link_show_fdinfo,
};
int netns_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
u32 prog_id, prog_cnt = 0, flags = 0;
enum netns_bpf_attach_type type;
struct bpf_prog *attached;
struct net *net;
if (attr->query.query_flags)
return -EINVAL;
type = to_netns_bpf_attach_type(attr->query.attach_type);
if (type < 0)
return -EINVAL;
net = get_net_ns_by_fd(attr->query.target_fd);
if (IS_ERR(net))
return PTR_ERR(net);
rcu_read_lock();
attached = rcu_dereference(net->bpf.progs[type]);
if (attached) {
prog_cnt = 1;
prog_id = attached->aux->id;
}
rcu_read_unlock();
put_net(net);
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
return -EFAULT;
if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
return -EFAULT;
if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
return 0;
if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
return -EFAULT;
return 0;
}
int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
enum netns_bpf_attach_type type;
struct net *net;
int ret;
type = to_netns_bpf_attach_type(attr->attach_type);
if (type < 0)
return -EINVAL;
net = current->nsproxy->net_ns;
mutex_lock(&netns_bpf_mutex);
/* Attaching prog directly is not compatible with links */
if (net->bpf.links[type]) {
ret = -EEXIST;
goto out_unlock;
}
switch (type) {
case NETNS_BPF_FLOW_DISSECTOR:
ret = flow_dissector_bpf_prog_attach(net, prog);
break;
default:
ret = -EINVAL;
break;
}
out_unlock:
mutex_unlock(&netns_bpf_mutex);
return ret;
}
/* Must be called with netns_bpf_mutex held. */
static int __netns_bpf_prog_detach(struct net *net,
enum netns_bpf_attach_type type)
{
struct bpf_prog *attached;
/* Progs attached via links cannot be detached */
if (net->bpf.links[type])
return -EINVAL;
attached = rcu_dereference_protected(net->bpf.progs[type],
lockdep_is_held(&netns_bpf_mutex));
if (!attached)
return -ENOENT;
RCU_INIT_POINTER(net->bpf.progs[type], NULL);
bpf_prog_put(attached);
return 0;
}
int netns_bpf_prog_detach(const union bpf_attr *attr)
{
enum netns_bpf_attach_type type;
int ret;
type = to_netns_bpf_attach_type(attr->attach_type);
if (type < 0)
return -EINVAL;
mutex_lock(&netns_bpf_mutex);
ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type);
mutex_unlock(&netns_bpf_mutex);
return ret;
}
static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
enum netns_bpf_attach_type type)
{
struct bpf_prog *prog;
int err;
mutex_lock(&netns_bpf_mutex);
/* Allow attaching only one prog or link for now */
if (net->bpf.links[type]) {
err = -E2BIG;
goto out_unlock;
}
/* Links are not compatible with attaching prog directly */
prog = rcu_dereference_protected(net->bpf.progs[type],
lockdep_is_held(&netns_bpf_mutex));
if (prog) {
err = -EEXIST;
goto out_unlock;
}
switch (type) {
case NETNS_BPF_FLOW_DISSECTOR:
err = flow_dissector_bpf_prog_attach(net, link->prog);
break;
default:
err = -EINVAL;
break;
}
if (err)
goto out_unlock;
net->bpf.links[type] = link;
out_unlock:
mutex_unlock(&netns_bpf_mutex);
return err;
}
int netns_bpf_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
{
enum netns_bpf_attach_type netns_type;
struct bpf_link_primer link_primer;
struct bpf_netns_link *net_link;
enum bpf_attach_type type;
struct net *net;
int err;
if (attr->link_create.flags)
return -EINVAL;
type = attr->link_create.attach_type;
netns_type = to_netns_bpf_attach_type(type);
if (netns_type < 0)
return -EINVAL;
net = get_net_ns_by_fd(attr->link_create.target_fd);
if (IS_ERR(net))
return PTR_ERR(net);
net_link = kzalloc(sizeof(*net_link), GFP_USER);
if (!net_link) {
err = -ENOMEM;
goto out_put_net;
}
bpf_link_init(&net_link->link, BPF_LINK_TYPE_NETNS,
&bpf_netns_link_ops, prog);
net_link->net = net;
net_link->type = type;
net_link->netns_type = netns_type;
err = bpf_link_prime(&net_link->link, &link_primer);
if (err) {
kfree(net_link);
goto out_put_net;
}
err = netns_bpf_link_attach(net, &net_link->link, netns_type);
if (err) {
bpf_link_cleanup(&link_primer);
goto out_put_net;
}
put_net(net);
return bpf_link_settle(&link_primer);
out_put_net:
put_net(net);
return err;
}
static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
{
enum netns_bpf_attach_type type;
struct bpf_link *link;
mutex_lock(&netns_bpf_mutex);
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) {
link = net->bpf.links[type];
if (link)
bpf_netns_link_auto_detach(link);
else
__netns_bpf_prog_detach(net, type);
}
mutex_unlock(&netns_bpf_mutex);
}
static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
.pre_exit = netns_bpf_pernet_pre_exit,
};
static int __init netns_bpf_init(void)
{
return register_pernet_subsys(&netns_bpf_pernet_ops);
}
subsys_initcall(netns_bpf_init);