kernel/bpf/cgroup.c - LeafOS-Devices/android_kernel_samsung_universal7904 - Gitiles

 /*
  * Functions to manage eBPF programs attached to cgroups
  *
  * Copyright (c) 2016 Daniel Mack
  *
  * This file is subject to the terms and conditions of version 2 of the GNU
  * General Public License.  See the file COPYING in the main directory of the
  * Linux distribution for more details.
  */

 #include <linux/kernel.h>
 #include <linux/atomic.h>
 #include <linux/cgroup.h>
 #include <linux/slab.h>
 #include <linux/bpf.h>
 #include <linux/bpf-cgroup.h>
 #include <net/sock.h>

 DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key);
 EXPORT_SYMBOL(cgroup_bpf_enabled_key);

 /**
  * cgroup_bpf_put() - put references of all bpf programs
  * @cgrp: the cgroup to modify
  */
 void cgroup_bpf_put(struct cgroup *cgrp)
 {
 	unsigned int type;

 	for (type = 0; type < ARRAY_SIZE(cgrp->bpf.progs); type++) {
 		struct list_head *progs = &cgrp->bpf.progs[type];
 		struct bpf_prog_list *pl, *tmp;

 		list_for_each_entry_safe(pl, tmp, progs, node) {
 			list_del(&pl->node);
 			bpf_prog_put(pl->prog);
 			kfree(pl);
 			static_branch_dec(&cgroup_bpf_enabled_key);
 		}
 		bpf_prog_array_free(cgrp->bpf.effective[type]);
 	}
 }

 /* count number of elements in the list.
  * it's slow but the list cannot be long
  */
 static u32 prog_list_length(struct list_head *head)
 {
 	struct bpf_prog_list *pl;
 	u32 cnt = 0;

 	list_for_each_entry(pl, head, node) {
 		if (!pl->prog)
 			continue;
 		cnt++;
 	}
 	return cnt;
 }

 /* if parent has non-overridable prog attached,
  * disallow attaching new programs to the descendent cgroup.
  * if parent has overridable or multi-prog, allow attaching
  */
 static bool hierarchy_allows_attach(struct cgroup *cgrp,
 				    enum bpf_attach_type type,
 				    u32 new_flags)
 {
 	struct cgroup *p;

 	p = cgroup_parent(cgrp);
 	if (!p)
 		return true;
 	do {
 		u32 flags = p->bpf.flags[type];
 		u32 cnt;

 		if (flags & BPF_F_ALLOW_MULTI)
 			return true;
 		cnt = prog_list_length(&p->bpf.progs[type]);
 		WARN_ON_ONCE(cnt > 1);
 		if (cnt == 1)
 			return !!(flags & BPF_F_ALLOW_OVERRIDE);
 		p = cgroup_parent(p);
 	} while (p);
 	return true;
 }

 /* compute a chain of effective programs for a given cgroup:
  * start from the list of programs in this cgroup and add
  * all parent programs.
  * Note that parent's F_ALLOW_OVERRIDE-type program is yielding
  * to programs in this cgroup
  */
 static int compute_effective_progs(struct cgroup *cgrp,
 				   enum bpf_attach_type type,
 				   struct bpf_prog_array __rcu **array)
 {
 	struct bpf_prog_array *progs;
 	struct bpf_prog_list *pl;
 	struct cgroup *p = cgrp;
 	int cnt = 0;

 	/* count number of effective programs by walking parents */
 	do {
 		if (cnt == 0 || (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
 			cnt += prog_list_length(&p->bpf.progs[type]);
 		p = cgroup_parent(p);
 	} while (p);

 	progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
 	if (!progs)
 		return -ENOMEM;

 	/* populate the array with effective progs */
 	cnt = 0;
 	p = cgrp;
 	do {
 		if (cnt == 0 || (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
 			list_for_each_entry(pl,
 					    &p->bpf.progs[type], node) {
 				if (!pl->prog)
 					continue;
 				progs->progs[cnt++] = pl->prog;
 			}
 		p = cgroup_parent(p);
 	} while (p);

 	rcu_assign_pointer(*array, progs);
 	return 0;
 }

 static void activate_effective_progs(struct cgroup *cgrp,
 				     enum bpf_attach_type type,
 				     struct bpf_prog_array __rcu *array)
 {
 	struct bpf_prog_array __rcu *old_array;

 	old_array = xchg(&cgrp->bpf.effective[type], array);
 	/* free prog array after grace period, since __cgroup_bpf_run_*()
 	 * might be still walking the array
 	 */
 	bpf_prog_array_free(old_array);
 }

 /**
  * cgroup_bpf_inherit() - inherit effective programs from parent
  * @cgrp: the cgroup to modify
  */
 int cgroup_bpf_inherit(struct cgroup *cgrp)
 {
 /* has to use marco instead of const int, since compiler thinks
  * that array below is variable length
  */
 #define	NR ARRAY_SIZE(cgrp->bpf.effective)
 	struct bpf_prog_array __rcu *arrays[NR] = {};
 	int i;

 	for (i = 0; i < NR; i++)
 		INIT_LIST_HEAD(&cgrp->bpf.progs[i]);

 	for (i = 0; i < NR; i++)
 		if (compute_effective_progs(cgrp, i, &arrays[i]))
 			goto cleanup;

 	for (i = 0; i < NR; i++)
 		activate_effective_progs(cgrp, i, arrays[i]);

 	return 0;
 cleanup:
 	for (i = 0; i < NR; i++)
 		bpf_prog_array_free(arrays[i]);
 	return -ENOMEM;
 }

 #define BPF_CGROUP_MAX_PROGS 64

 /**
  * __cgroup_bpf_attach() - Attach the program to a cgroup, and
  *                         propagate the change to descendants
  * @cgrp: The cgroup which descendants to traverse
  * @prog: A program to attach
  * @type: Type of attach operation
  *
  * Must be called with cgroup_mutex held.
  */
 int __cgroup_bpf_attach(struct cgroup *cgrp, struct bpf_prog *prog,
 			enum bpf_attach_type type, u32 flags)
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
 	struct bpf_prog *old_prog = NULL;
 	struct cgroup_subsys_state *css;
 	struct bpf_prog_list *pl;
 	bool pl_was_allocated;
 	u32 old_flags;
 	int err;

 	if ((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI))
 		/* invalid combination */
 		return -EINVAL;

 	if (!hierarchy_allows_attach(cgrp, type, flags))
 		return -EPERM;

 	if (!list_empty(progs) && cgrp->bpf.flags[type] != flags)
 		/* Disallow attaching non-overridable on top
 		 * of existing overridable in this cgroup.
 		 * Disallow attaching multi-prog if overridable or none
 		 */
 		return -EPERM;

 	if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
 		return -E2BIG;

 	if (flags & BPF_F_ALLOW_MULTI) {
 		list_for_each_entry(pl, progs, node)
 			if (pl->prog == prog)
 				/* disallow attaching the same prog twice */
 				return -EINVAL;

 		pl = kmalloc(sizeof(*pl), GFP_KERNEL);
 		if (!pl)
 			return -ENOMEM;
 		pl_was_allocated = true;
 		pl->prog = prog;
 		list_add_tail(&pl->node, progs);
 	} else {
 		if (list_empty(progs)) {
 			pl = kmalloc(sizeof(*pl), GFP_KERNEL);
 			if (!pl)
 				return -ENOMEM;
 			pl_was_allocated = true;
 			list_add_tail(&pl->node, progs);
 		} else {
 			pl = list_first_entry(progs, typeof(*pl), node);
 			old_prog = pl->prog;
 			pl_was_allocated = false;
 		}
 		pl->prog = prog;
 	}

 	old_flags = cgrp->bpf.flags[type];
 	cgrp->bpf.flags[type] = flags;

 	/* allocate and recompute effective prog arrays */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		err = compute_effective_progs(desc, type, &desc->bpf.inactive);
 		if (err)
 			goto cleanup;
 	}

 	/* all allocations were successful. Activate all prog arrays */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		activate_effective_progs(desc, type, desc->bpf.inactive);
 		desc->bpf.inactive = NULL;
 	}

 	static_branch_inc(&cgroup_bpf_enabled_key);
 	if (old_prog) {
 		bpf_prog_put(old_prog);
 		static_branch_dec(&cgroup_bpf_enabled_key);
 	}
 	return 0;

 cleanup:
 	/* oom while computing effective. Free all computed effective arrays
 	 * since they were not activated
 	 */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		bpf_prog_array_free(desc->bpf.inactive);
 		desc->bpf.inactive = NULL;
 	}

 	/* and cleanup the prog list */
 	pl->prog = old_prog;
 	if (pl_was_allocated) {
 		list_del(&pl->node);
 		kfree(pl);
 	}
 	return err;
 }

 /**
  * __cgroup_bpf_detach() - Detach the program from a cgroup, and
  *                         propagate the change to descendants
  * @cgrp: The cgroup which descendants to traverse
  * @prog: A program to detach or NULL
  * @type: Type of detach operation
  *
  * Must be called with cgroup_mutex held.
  */
 int __cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog,
 			enum bpf_attach_type type, u32 unused_flags)
 {
 	struct list_head *progs = &cgrp->bpf.progs[type];
 	u32 flags = cgrp->bpf.flags[type];
 	struct bpf_prog *old_prog = NULL;
 	struct cgroup_subsys_state *css;
 	struct bpf_prog_list *pl;
 	int err;

 	if (flags & BPF_F_ALLOW_MULTI) {
 		if (!prog)
 			/* to detach MULTI prog the user has to specify valid FD
 			 * of the program to be detached
 			 */
 			return -EINVAL;
 	} else {
 		if (list_empty(progs))
 			/* report error when trying to detach and nothing is attached */
 			return -ENOENT;
 	}

 	if (flags & BPF_F_ALLOW_MULTI) {
 		/* find the prog and detach it */
 		list_for_each_entry(pl, progs, node) {
 			if (pl->prog != prog)
 				continue;
 			old_prog = prog;
 			/* mark it deleted, so it's ignored while
 			 * recomputing effective
 			 */
 			pl->prog = NULL;
 			break;
 		}
 		if (!old_prog)
 			return -ENOENT;
 	} else {
 		/* to maintain backward compatibility NONE and OVERRIDE cgroups
 		 * allow detaching with invalid FD (prog==NULL)
 		 */
 		pl = list_first_entry(progs, typeof(*pl), node);
 		old_prog = pl->prog;
 		pl->prog = NULL;
 	}

 	/* allocate and recompute effective prog arrays */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		err = compute_effective_progs(desc, type, &desc->bpf.inactive);
 		if (err)
 			goto cleanup;
 	}

 	/* all allocations were successful. Activate all prog arrays */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		activate_effective_progs(desc, type, desc->bpf.inactive);
 		desc->bpf.inactive = NULL;
 	}

 	/* now can actually delete it from this cgroup list */
 	list_del(&pl->node);
 	kfree(pl);
 	if (list_empty(progs))
 		/* last program was detached, reset flags to zero */
 		cgrp->bpf.flags[type] = 0;

 	bpf_prog_put(old_prog);
 	static_branch_dec(&cgroup_bpf_enabled_key);
 	return 0;

 cleanup:
 	/* oom while computing effective. Free all computed effective arrays
 	 * since they were not activated
 	 */
 	css_for_each_descendant_pre(css, &cgrp->self) {
 		struct cgroup *desc = container_of(css, struct cgroup, self);

 		bpf_prog_array_free(desc->bpf.inactive);
 		desc->bpf.inactive = NULL;
 	}

 	/* and restore back old_prog */
 	pl->prog = old_prog;
 	return err;
 }

 /**
  * __cgroup_bpf_run_filter() - Run a program for packet filtering
  * @sk: The socket sending or receiving traffic
  * @skb: The skb that is being sent or received
  * @type: The type of program to be exectuted
  *
  * If no socket is passed, or the socket is not of type INET or INET6,
  * this function does nothing and returns 0.
  *
  * The program type passed in via @type must be suitable for network
  * filtering. No further check is performed to assert that.
  *
  * This function will return %-EPERM if any if an attached program was found
  * and if it returned != 1 during execution. In all other cases, 0 is returned.
  */
 int __cgroup_bpf_run_filter(struct sock *sk,
 			    struct sk_buff *skb,
 			    enum bpf_attach_type type)
 {
 	unsigned int offset = skb->data - skb_network_header(skb);
 	struct sock *save_sk;
 	struct cgroup *cgrp;
 	int ret;

 	if (!sk || !sk_fullsock(sk))
 		return 0;

 	if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
 		return 0;

 	cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
 	save_sk = skb->sk;
 	skb->sk = sk;
 	__skb_push(skb, offset);
 	ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
 				 bpf_prog_run_save_cb);
 	__skb_pull(skb, offset);
 	skb->sk = save_sk;
 	return ret == 1 ? 0 : -EPERM;
 }
 EXPORT_SYMBOL(__cgroup_bpf_run_filter);

 /**
  * __cgroup_bpf_run_filter_sk() - Run a program on a sock
  * @sk: sock structure to manipulate
  * @type: The type of program to be exectuted
  *
  * socket is passed is expected to be of type INET or INET6.
  *
  * The program type passed in via @type must be suitable for sock
  * filtering. No further check is performed to assert that.
  *
  * This function will return %-EPERM if any if an attached program was found
  * and if it returned != 1 during execution. In all other cases, 0 is returned.
  */
 int __cgroup_bpf_run_filter_sk(struct sock *sk,
 			       enum bpf_attach_type type)
 {
 	struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
 	struct bpf_prog *prog;
 	int ret = 0;


 	rcu_read_lock();

 	prog = rcu_dereference(cgrp->bpf.effective[type]->progs[0]);
 	if (prog)
 		ret = BPF_PROG_RUN(prog, sk) == 1 ? 0 : -EPERM;

 	rcu_read_unlock();

 	return ret;
 }
 EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
	/*
	* Functions to manage eBPF programs attached to cgroups
	*
	* Copyright (c) 2016 Daniel Mack
	*
	* This file is subject to the terms and conditions of version 2 of the GNU
	* General Public License. See the file COPYING in the main directory of the
	* Linux distribution for more details.
	*/

	#include <linux/kernel.h>
	#include <linux/atomic.h>
	#include <linux/cgroup.h>
	#include <linux/slab.h>
	#include <linux/bpf.h>
	#include <linux/bpf-cgroup.h>
	#include <net/sock.h>

	DEFINE_STATIC_KEY_FALSE(cgroup_bpf_enabled_key);
	EXPORT_SYMBOL(cgroup_bpf_enabled_key);

	/**
	* cgroup_bpf_put() - put references of all bpf programs
	* @cgrp: the cgroup to modify
	*/
	void cgroup_bpf_put(struct cgroup *cgrp)
	{
	unsigned int type;

	for (type = 0; type < ARRAY_SIZE(cgrp->bpf.progs); type++) {
	struct list_head *progs = &cgrp->bpf.progs[type];
	struct bpf_prog_list pl, tmp;

	list_for_each_entry_safe(pl, tmp, progs, node) {
	list_del(&pl->node);
	bpf_prog_put(pl->prog);
	kfree(pl);
	static_branch_dec(&cgroup_bpf_enabled_key);
	}
	bpf_prog_array_free(cgrp->bpf.effective[type]);
	}
	}

	/* count number of elements in the list.
	* it's slow but the list cannot be long
	*/
	static u32 prog_list_length(struct list_head *head)
	{
	struct bpf_prog_list *pl;
	u32 cnt = 0;

	list_for_each_entry(pl, head, node) {
	if (!pl->prog)
	continue;
	cnt++;
	}
	return cnt;
	}

	/* if parent has non-overridable prog attached,
	* disallow attaching new programs to the descendent cgroup.
	* if parent has overridable or multi-prog, allow attaching
	*/
	static bool hierarchy_allows_attach(struct cgroup *cgrp,
	enum bpf_attach_type type,
	u32 new_flags)
	{
	struct cgroup *p;

	p = cgroup_parent(cgrp);
	if (!p)
	return true;
	do {
	u32 flags = p->bpf.flags[type];
	u32 cnt;

	if (flags & BPF_F_ALLOW_MULTI)
	return true;
	cnt = prog_list_length(&p->bpf.progs[type]);
	WARN_ON_ONCE(cnt > 1);
	if (cnt == 1)
	return !!(flags & BPF_F_ALLOW_OVERRIDE);
	p = cgroup_parent(p);
	} while (p);
	return true;
	}

	/* compute a chain of effective programs for a given cgroup:
	* start from the list of programs in this cgroup and add
	* all parent programs.
	* Note that parent's F_ALLOW_OVERRIDE-type program is yielding
	* to programs in this cgroup
	*/
	static int compute_effective_progs(struct cgroup *cgrp,
	enum bpf_attach_type type,
	struct bpf_prog_array __rcu **array)
	{
	struct bpf_prog_array *progs;
	struct bpf_prog_list *pl;
	struct cgroup *p = cgrp;
	int cnt = 0;

	/* count number of effective programs by walking parents */
	do {
	if (cnt == 0 \|\| (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
	cnt += prog_list_length(&p->bpf.progs[type]);
	p = cgroup_parent(p);
	} while (p);

	progs = bpf_prog_array_alloc(cnt, GFP_KERNEL);
	if (!progs)
	return -ENOMEM;

	/* populate the array with effective progs */
	cnt = 0;
	p = cgrp;
	do {
	if (cnt == 0 \|\| (p->bpf.flags[type] & BPF_F_ALLOW_MULTI))
	list_for_each_entry(pl,
	&p->bpf.progs[type], node) {
	if (!pl->prog)
	continue;
	progs->progs[cnt++] = pl->prog;
	}
	p = cgroup_parent(p);
	} while (p);

	rcu_assign_pointer(*array, progs);
	return 0;
	}

	static void activate_effective_progs(struct cgroup *cgrp,
	enum bpf_attach_type type,
	struct bpf_prog_array __rcu *array)
	{
	struct bpf_prog_array __rcu *old_array;

	old_array = xchg(&cgrp->bpf.effective[type], array);
	/* free prog array after grace period, since __cgroup_bpf_run_*()
	* might be still walking the array
	*/
	bpf_prog_array_free(old_array);
	}

	/**
	* cgroup_bpf_inherit() - inherit effective programs from parent
	* @cgrp: the cgroup to modify
	*/
	int cgroup_bpf_inherit(struct cgroup *cgrp)
	{
	/* has to use marco instead of const int, since compiler thinks
	* that array below is variable length
	*/
	#define NR ARRAY_SIZE(cgrp->bpf.effective)
	struct bpf_prog_array __rcu *arrays[NR] = {};
	int i;

	for (i = 0; i < NR; i++)
	INIT_LIST_HEAD(&cgrp->bpf.progs[i]);

	for (i = 0; i < NR; i++)
	if (compute_effective_progs(cgrp, i, &arrays[i]))
	goto cleanup;

	for (i = 0; i < NR; i++)
	activate_effective_progs(cgrp, i, arrays[i]);

	return 0;
	cleanup:
	for (i = 0; i < NR; i++)
	bpf_prog_array_free(arrays[i]);
	return -ENOMEM;
	}

	#define BPF_CGROUP_MAX_PROGS 64

	/**
	* __cgroup_bpf_attach() - Attach the program to a cgroup, and
	* propagate the change to descendants
	* @cgrp: The cgroup which descendants to traverse
	* @prog: A program to attach
	* @type: Type of attach operation
	*
	* Must be called with cgroup_mutex held.
	*/
	int __cgroup_bpf_attach(struct cgroup cgrp, struct bpf_prog prog,
	enum bpf_attach_type type, u32 flags)
	{
	struct list_head *progs = &cgrp->bpf.progs[type];
	struct bpf_prog *old_prog = NULL;
	struct cgroup_subsys_state *css;
	struct bpf_prog_list *pl;
	bool pl_was_allocated;
	u32 old_flags;
	int err;

	if ((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI))
	/* invalid combination */
	return -EINVAL;

	if (!hierarchy_allows_attach(cgrp, type, flags))
	return -EPERM;

	if (!list_empty(progs) && cgrp->bpf.flags[type] != flags)
	/* Disallow attaching non-overridable on top
	* of existing overridable in this cgroup.
	* Disallow attaching multi-prog if overridable or none
	*/
	return -EPERM;

	if (prog_list_length(progs) >= BPF_CGROUP_MAX_PROGS)
	return -E2BIG;

	if (flags & BPF_F_ALLOW_MULTI) {
	list_for_each_entry(pl, progs, node)
	if (pl->prog == prog)
	/* disallow attaching the same prog twice */
	return -EINVAL;

	pl = kmalloc(sizeof(*pl), GFP_KERNEL);
	if (!pl)
	return -ENOMEM;
	pl_was_allocated = true;
	pl->prog = prog;
	list_add_tail(&pl->node, progs);
	} else {
	if (list_empty(progs)) {
	pl = kmalloc(sizeof(*pl), GFP_KERNEL);
	if (!pl)
	return -ENOMEM;
	pl_was_allocated = true;
	list_add_tail(&pl->node, progs);
	} else {
	pl = list_first_entry(progs, typeof(*pl), node);
	old_prog = pl->prog;
	pl_was_allocated = false;
	}
	pl->prog = prog;
	}

	old_flags = cgrp->bpf.flags[type];
	cgrp->bpf.flags[type] = flags;

	/* allocate and recompute effective prog arrays */
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	err = compute_effective_progs(desc, type, &desc->bpf.inactive);
	if (err)
	goto cleanup;
	}

	/* all allocations were successful. Activate all prog arrays */
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	activate_effective_progs(desc, type, desc->bpf.inactive);
	desc->bpf.inactive = NULL;
	}

	static_branch_inc(&cgroup_bpf_enabled_key);
	if (old_prog) {
	bpf_prog_put(old_prog);
	static_branch_dec(&cgroup_bpf_enabled_key);
	}
	return 0;

	cleanup:
	/* oom while computing effective. Free all computed effective arrays
	* since they were not activated
	*/
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	bpf_prog_array_free(desc->bpf.inactive);
	desc->bpf.inactive = NULL;
	}

	/* and cleanup the prog list */
	pl->prog = old_prog;
	if (pl_was_allocated) {
	list_del(&pl->node);
	kfree(pl);
	}
	return err;
	}

	/**
	* __cgroup_bpf_detach() - Detach the program from a cgroup, and
	* propagate the change to descendants
	* @cgrp: The cgroup which descendants to traverse
	* @prog: A program to detach or NULL
	* @type: Type of detach operation
	*
	* Must be called with cgroup_mutex held.
	*/
	int __cgroup_bpf_detach(struct cgroup cgrp, struct bpf_prog prog,
	enum bpf_attach_type type, u32 unused_flags)
	{
	struct list_head *progs = &cgrp->bpf.progs[type];
	u32 flags = cgrp->bpf.flags[type];
	struct bpf_prog *old_prog = NULL;
	struct cgroup_subsys_state *css;
	struct bpf_prog_list *pl;
	int err;

	if (flags & BPF_F_ALLOW_MULTI) {
	if (!prog)
	/* to detach MULTI prog the user has to specify valid FD
	* of the program to be detached
	*/
	return -EINVAL;
	} else {
	if (list_empty(progs))
	/* report error when trying to detach and nothing is attached */
	return -ENOENT;
	}

	if (flags & BPF_F_ALLOW_MULTI) {
	/* find the prog and detach it */
	list_for_each_entry(pl, progs, node) {
	if (pl->prog != prog)
	continue;
	old_prog = prog;
	/* mark it deleted, so it's ignored while
	* recomputing effective
	*/
	pl->prog = NULL;
	break;
	}
	if (!old_prog)
	return -ENOENT;
	} else {
	/* to maintain backward compatibility NONE and OVERRIDE cgroups
	* allow detaching with invalid FD (prog==NULL)
	*/
	pl = list_first_entry(progs, typeof(*pl), node);
	old_prog = pl->prog;
	pl->prog = NULL;
	}

	/* allocate and recompute effective prog arrays */
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	err = compute_effective_progs(desc, type, &desc->bpf.inactive);
	if (err)
	goto cleanup;
	}

	/* all allocations were successful. Activate all prog arrays */
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	activate_effective_progs(desc, type, desc->bpf.inactive);
	desc->bpf.inactive = NULL;
	}

	/* now can actually delete it from this cgroup list */
	list_del(&pl->node);
	kfree(pl);
	if (list_empty(progs))
	/* last program was detached, reset flags to zero */
	cgrp->bpf.flags[type] = 0;

	bpf_prog_put(old_prog);
	static_branch_dec(&cgroup_bpf_enabled_key);
	return 0;

	cleanup:
	/* oom while computing effective. Free all computed effective arrays
	* since they were not activated
	*/
	css_for_each_descendant_pre(css, &cgrp->self) {
	struct cgroup *desc = container_of(css, struct cgroup, self);

	bpf_prog_array_free(desc->bpf.inactive);
	desc->bpf.inactive = NULL;
	}

	/* and restore back old_prog */
	pl->prog = old_prog;
	return err;
	}

	/**
	* __cgroup_bpf_run_filter() - Run a program for packet filtering
	* @sk: The socket sending or receiving traffic
	* @skb: The skb that is being sent or received
	* @type: The type of program to be exectuted
	*
	* If no socket is passed, or the socket is not of type INET or INET6,
	* this function does nothing and returns 0.
	*
	* The program type passed in via @type must be suitable for network
	* filtering. No further check is performed to assert that.
	*
	* This function will return %-EPERM if any if an attached program was found
	* and if it returned != 1 during execution. In all other cases, 0 is returned.
	*/
	int __cgroup_bpf_run_filter(struct sock *sk,
	struct sk_buff *skb,
	enum bpf_attach_type type)
	{
	unsigned int offset = skb->data - skb_network_header(skb);
	struct sock *save_sk;
	struct cgroup *cgrp;
	int ret;

	if (!sk \|\| !sk_fullsock(sk))
	return 0;

	if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
	return 0;

	cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
	save_sk = skb->sk;
	skb->sk = sk;
	__skb_push(skb, offset);
	ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
	bpf_prog_run_save_cb);
	__skb_pull(skb, offset);
	skb->sk = save_sk;
	return ret == 1 ? 0 : -EPERM;
	}
	EXPORT_SYMBOL(__cgroup_bpf_run_filter);

	/**
	* __cgroup_bpf_run_filter_sk() - Run a program on a sock
	* @sk: sock structure to manipulate
	* @type: The type of program to be exectuted
	*
	* socket is passed is expected to be of type INET or INET6.
	*
	* The program type passed in via @type must be suitable for sock
	* filtering. No further check is performed to assert that.
	*
	* This function will return %-EPERM if any if an attached program was found
	* and if it returned != 1 during execution. In all other cases, 0 is returned.
	*/
	int __cgroup_bpf_run_filter_sk(struct sock *sk,
	enum bpf_attach_type type)
	{
	struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
	struct bpf_prog *prog;
	int ret = 0;


	rcu_read_lock();

	prog = rcu_dereference(cgrp->bpf.effective[type]->progs[0]);
	if (prog)
	ret = BPF_PROG_RUN(prog, sk) == 1 ? 0 : -EPERM;

	rcu_read_unlock();

	return ret;
	}
	EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);