kernel/bpf/net_namespace.c - linux - Git at Google

 // 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);
	// 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);