// 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;
|
struct list_head node; /* node in list of links attached to net */
|
};
|
|
/* Protects updates to netns_bpf */
|
DEFINE_MUTEX(netns_bpf_mutex);
|
|
static void netns_bpf_attach_type_unneed(enum netns_bpf_attach_type type)
|
{
|
switch (type) {
|
#ifdef CONFIG_INET
|
case NETNS_BPF_SK_LOOKUP:
|
static_branch_dec(&bpf_sk_lookup_enabled);
|
break;
|
#endif
|
default:
|
break;
|
}
|
}
|
|
static void netns_bpf_attach_type_need(enum netns_bpf_attach_type type)
|
{
|
switch (type) {
|
#ifdef CONFIG_INET
|
case NETNS_BPF_SK_LOOKUP:
|
static_branch_inc(&bpf_sk_lookup_enabled);
|
break;
|
#endif
|
default:
|
break;
|
}
|
}
|
|
/* Must be called with netns_bpf_mutex held. */
|
static void netns_bpf_run_array_detach(struct net *net,
|
enum netns_bpf_attach_type type)
|
{
|
struct bpf_prog_array *run_array;
|
|
run_array = rcu_replace_pointer(net->bpf.run_array[type], NULL,
|
lockdep_is_held(&netns_bpf_mutex));
|
bpf_prog_array_free(run_array);
|
}
|
|
static int link_index(struct net *net, enum netns_bpf_attach_type type,
|
struct bpf_netns_link *link)
|
{
|
struct bpf_netns_link *pos;
|
int i = 0;
|
|
list_for_each_entry(pos, &net->bpf.links[type], node) {
|
if (pos == link)
|
return i;
|
i++;
|
}
|
return -ENOENT;
|
}
|
|
static int link_count(struct net *net, enum netns_bpf_attach_type type)
|
{
|
struct list_head *pos;
|
int i = 0;
|
|
list_for_each(pos, &net->bpf.links[type])
|
i++;
|
return i;
|
}
|
|
static void fill_prog_array(struct net *net, enum netns_bpf_attach_type type,
|
struct bpf_prog_array *prog_array)
|
{
|
struct bpf_netns_link *pos;
|
unsigned int i = 0;
|
|
list_for_each_entry(pos, &net->bpf.links[type], node) {
|
prog_array->items[i].prog = pos->link.prog;
|
i++;
|
}
|
}
|
|
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 bpf_prog_array *old_array, *new_array;
|
struct net *net;
|
int cnt, idx;
|
|
mutex_lock(&netns_bpf_mutex);
|
|
/* We can race with cleanup_net, but if we see a non-NULL
|
* struct net pointer, pre_exit has not run yet and wait for
|
* netns_bpf_mutex.
|
*/
|
net = net_link->net;
|
if (!net)
|
goto out_unlock;
|
|
/* Mark attach point as unused */
|
netns_bpf_attach_type_unneed(type);
|
|
/* Remember link position in case of safe delete */
|
idx = link_index(net, type, net_link);
|
list_del(&net_link->node);
|
|
cnt = link_count(net, type);
|
if (!cnt) {
|
netns_bpf_run_array_detach(net, type);
|
goto out_unlock;
|
}
|
|
old_array = rcu_dereference_protected(net->bpf.run_array[type],
|
lockdep_is_held(&netns_bpf_mutex));
|
new_array = bpf_prog_array_alloc(cnt, GFP_KERNEL);
|
if (!new_array) {
|
WARN_ON(bpf_prog_array_delete_safe_at(old_array, idx));
|
goto out_unlock;
|
}
|
fill_prog_array(net, type, new_array);
|
rcu_assign_pointer(net->bpf.run_array[type], new_array);
|
bpf_prog_array_free(old_array);
|
|
out_unlock:
|
net_link->net = NULL;
|
mutex_unlock(&netns_bpf_mutex);
|
}
|
|
static int bpf_netns_link_detach(struct bpf_link *link)
|
{
|
bpf_netns_link_release(link);
|
return 0;
|
}
|
|
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 bpf_prog_array *run_array;
|
struct net *net;
|
int idx, ret;
|
|
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;
|
}
|
|
run_array = rcu_dereference_protected(net->bpf.run_array[type],
|
lockdep_is_held(&netns_bpf_mutex));
|
idx = link_index(net, type, net_link);
|
ret = bpf_prog_array_update_at(run_array, idx, new_prog);
|
if (ret)
|
goto out_unlock;
|
|
old_prog = xchg(&link->prog, 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,
|
.detach = bpf_netns_link_detach,
|
.update_prog = bpf_netns_link_update_prog,
|
.fill_link_info = bpf_netns_link_fill_info,
|
.show_fdinfo = bpf_netns_link_show_fdinfo,
|
};
|
|
/* Must be called with netns_bpf_mutex held. */
|
static int __netns_bpf_prog_query(const union bpf_attr *attr,
|
union bpf_attr __user *uattr,
|
struct net *net,
|
enum netns_bpf_attach_type type)
|
{
|
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
|
struct bpf_prog_array *run_array;
|
u32 prog_cnt = 0, flags = 0;
|
|
run_array = rcu_dereference_protected(net->bpf.run_array[type],
|
lockdep_is_held(&netns_bpf_mutex));
|
if (run_array)
|
prog_cnt = bpf_prog_array_length(run_array);
|
|
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;
|
|
return bpf_prog_array_copy_to_user(run_array, prog_ids,
|
attr->query.prog_cnt);
|
}
|
|
int netns_bpf_prog_query(const union bpf_attr *attr,
|
union bpf_attr __user *uattr)
|
{
|
enum netns_bpf_attach_type type;
|
struct net *net;
|
int ret;
|
|
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);
|
|
mutex_lock(&netns_bpf_mutex);
|
ret = __netns_bpf_prog_query(attr, uattr, net, type);
|
mutex_unlock(&netns_bpf_mutex);
|
|
put_net(net);
|
return ret;
|
}
|
|
int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
|
{
|
struct bpf_prog_array *run_array;
|
enum netns_bpf_attach_type type;
|
struct bpf_prog *attached;
|
struct net *net;
|
int ret;
|
|
if (attr->target_fd || attr->attach_flags || attr->replace_bpf_fd)
|
return -EINVAL;
|
|
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 (!list_empty(&net->bpf.links[type])) {
|
ret = -EEXIST;
|
goto out_unlock;
|
}
|
|
switch (type) {
|
case NETNS_BPF_FLOW_DISSECTOR:
|
ret = flow_dissector_bpf_prog_attach_check(net, prog);
|
break;
|
default:
|
ret = -EINVAL;
|
break;
|
}
|
if (ret)
|
goto out_unlock;
|
|
attached = net->bpf.progs[type];
|
if (attached == prog) {
|
/* The same program cannot be attached twice */
|
ret = -EINVAL;
|
goto out_unlock;
|
}
|
|
run_array = rcu_dereference_protected(net->bpf.run_array[type],
|
lockdep_is_held(&netns_bpf_mutex));
|
if (run_array) {
|
WRITE_ONCE(run_array->items[0].prog, prog);
|
} else {
|
run_array = bpf_prog_array_alloc(1, GFP_KERNEL);
|
if (!run_array) {
|
ret = -ENOMEM;
|
goto out_unlock;
|
}
|
run_array->items[0].prog = prog;
|
rcu_assign_pointer(net->bpf.run_array[type], run_array);
|
}
|
|
net->bpf.progs[type] = prog;
|
if (attached)
|
bpf_prog_put(attached);
|
|
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 *old)
|
{
|
struct bpf_prog *attached;
|
|
/* Progs attached via links cannot be detached */
|
if (!list_empty(&net->bpf.links[type]))
|
return -EINVAL;
|
|
attached = net->bpf.progs[type];
|
if (!attached || attached != old)
|
return -ENOENT;
|
netns_bpf_run_array_detach(net, type);
|
net->bpf.progs[type] = NULL;
|
bpf_prog_put(attached);
|
return 0;
|
}
|
|
int netns_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
|
{
|
enum netns_bpf_attach_type type;
|
struct bpf_prog *prog;
|
int ret;
|
|
if (attr->target_fd)
|
return -EINVAL;
|
|
type = to_netns_bpf_attach_type(attr->attach_type);
|
if (type < 0)
|
return -EINVAL;
|
|
prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
|
if (IS_ERR(prog))
|
return PTR_ERR(prog);
|
|
mutex_lock(&netns_bpf_mutex);
|
ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type, prog);
|
mutex_unlock(&netns_bpf_mutex);
|
|
bpf_prog_put(prog);
|
|
return ret;
|
}
|
|
static int netns_bpf_max_progs(enum netns_bpf_attach_type type)
|
{
|
switch (type) {
|
case NETNS_BPF_FLOW_DISSECTOR:
|
return 1;
|
case NETNS_BPF_SK_LOOKUP:
|
return 64;
|
default:
|
return 0;
|
}
|
}
|
|
static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
|
enum netns_bpf_attach_type type)
|
{
|
struct bpf_netns_link *net_link =
|
container_of(link, struct bpf_netns_link, link);
|
struct bpf_prog_array *run_array;
|
int cnt, err;
|
|
mutex_lock(&netns_bpf_mutex);
|
|
cnt = link_count(net, type);
|
if (cnt >= netns_bpf_max_progs(type)) {
|
err = -E2BIG;
|
goto out_unlock;
|
}
|
/* Links are not compatible with attaching prog directly */
|
if (net->bpf.progs[type]) {
|
err = -EEXIST;
|
goto out_unlock;
|
}
|
|
switch (type) {
|
case NETNS_BPF_FLOW_DISSECTOR:
|
err = flow_dissector_bpf_prog_attach_check(net, link->prog);
|
break;
|
case NETNS_BPF_SK_LOOKUP:
|
err = 0; /* nothing to check */
|
break;
|
default:
|
err = -EINVAL;
|
break;
|
}
|
if (err)
|
goto out_unlock;
|
|
run_array = bpf_prog_array_alloc(cnt + 1, GFP_KERNEL);
|
if (!run_array) {
|
err = -ENOMEM;
|
goto out_unlock;
|
}
|
|
list_add_tail(&net_link->node, &net->bpf.links[type]);
|
|
fill_prog_array(net, type, run_array);
|
run_array = rcu_replace_pointer(net->bpf.run_array[type], run_array,
|
lockdep_is_held(&netns_bpf_mutex));
|
bpf_prog_array_free(run_array);
|
|
/* Mark attach point as used */
|
netns_bpf_attach_type_need(type);
|
|
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 int __net_init netns_bpf_pernet_init(struct net *net)
|
{
|
int type;
|
|
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++)
|
INIT_LIST_HEAD(&net->bpf.links[type]);
|
|
return 0;
|
}
|
|
static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
|
{
|
enum netns_bpf_attach_type type;
|
struct bpf_netns_link *net_link;
|
|
mutex_lock(&netns_bpf_mutex);
|
for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) {
|
netns_bpf_run_array_detach(net, type);
|
list_for_each_entry(net_link, &net->bpf.links[type], node) {
|
net_link->net = NULL; /* auto-detach link */
|
netns_bpf_attach_type_unneed(type);
|
}
|
if (net->bpf.progs[type])
|
bpf_prog_put(net->bpf.progs[type]);
|
}
|
mutex_unlock(&netns_bpf_mutex);
|
}
|
|
static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
|
.init = netns_bpf_pernet_init,
|
.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);
|
