// SPDX-License-Identifier: GPL-2.0-only
/*
 * Functions to manage eBPF programs attached to cgroups
 *
 * Copyright (c) 2016 Daniel Mack
 */

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

#include "../cgroup/cgroup-internal.h"

DEFINE_STATIC_KEY_ARRAY_FALSE(cgroup_bpf_enabled_key, MAX_BPF_ATTACH_TYPE);
EXPORT_SYMBOL(cgroup_bpf_enabled_key);

void cgroup_bpf_offline(struct cgroup *cgrp)
{
        cgroup_get(cgrp);
        percpu_ref_kill(&cgrp->bpf.refcnt);
}

static void bpf_cgroup_storages_free(struct bpf_cgroup_storage *storages[])
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                bpf_cgroup_storage_free(storages[stype]);
}

static int bpf_cgroup_storages_alloc(struct bpf_cgroup_storage *storages[],
                                     struct bpf_cgroup_storage *new_storages[],
                                     enum bpf_attach_type type,
                                     struct bpf_prog *prog,
                                     struct cgroup *cgrp)
{
        enum bpf_cgroup_storage_type stype;
        struct bpf_cgroup_storage_key key;
        struct bpf_map *map;

        key.cgroup_inode_id = cgroup_id(cgrp);
        key.attach_type = type;

        for_each_cgroup_storage_type(stype) {
                map = prog->aux->cgroup_storage[stype];
                if (!map)
                        continue;

                storages[stype] = cgroup_storage_lookup((void *)map, &key, false);
                if (storages[stype])
                        continue;

                storages[stype] = bpf_cgroup_storage_alloc(prog, stype);
                if (IS_ERR(storages[stype])) {
                        bpf_cgroup_storages_free(new_storages);
                        return -ENOMEM;
                }

                new_storages[stype] = storages[stype];
        }

        return 0;
}

static void bpf_cgroup_storages_assign(struct bpf_cgroup_storage *dst[],
                                       struct bpf_cgroup_storage *src[])
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                dst[stype] = src[stype];
}

static void bpf_cgroup_storages_link(struct bpf_cgroup_storage *storages[],
                                     struct cgroup *cgrp,
                                     enum bpf_attach_type attach_type)
{
        enum bpf_cgroup_storage_type stype;

        for_each_cgroup_storage_type(stype)
                bpf_cgroup_storage_link(storages[stype], cgrp, attach_type);
}

/* Called when bpf_cgroup_link is auto-detached from dying cgroup.
 * It drops cgroup and bpf_prog refcounts, and marks bpf_link as defunct. It
 * doesn't free link memory, which will eventually be done by bpf_link's
 * release() callback, when its last FD is closed.
 */
static void bpf_cgroup_link_auto_detach(struct bpf_cgroup_link *link)
{
        cgroup_put(link->cgroup);
        link->cgroup = NULL;
}

/**
 * cgroup_bpf_release() - put references of all bpf programs and
 *                        release all cgroup bpf data
 * @work: work structure embedded into the cgroup to modify
 */
static void cgroup_bpf_release(struct work_struct *work)
{
        struct cgroup *p, *cgrp = container_of(work, struct cgroup,
                                               bpf.release_work);
        struct bpf_prog_array *old_array;
        struct list_head *storages = &cgrp->bpf.storages;
        struct bpf_cgroup_storage *storage, *stmp;

        unsigned int type;

        mutex_lock(&cgroup_mutex);

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

                list_for_each_entry_safe(pl, pltmp, progs, node) {
                        list_del(&pl->node);
                        if (pl->prog)
                                bpf_prog_put(pl->prog);
                        if (pl->link)
                                bpf_cgroup_link_auto_detach(pl->link);
                        kfree(pl);
                        static_branch_dec(&cgroup_bpf_enabled_key[type]);
                }
                old_array = rcu_dereference_protected(
                                cgrp->bpf.effective[type],
                                lockdep_is_held(&cgroup_mutex));
                bpf_prog_array_free(old_array);
        }

        list_for_each_entry_safe(storage, stmp, storages, list_cg) {
                bpf_cgroup_storage_unlink(storage);
                bpf_cgroup_storage_free(storage);
        }

        mutex_unlock(&cgroup_mutex);

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_put(p);

        percpu_ref_exit(&cgrp->bpf.refcnt);
        cgroup_put(cgrp);
}

/**
 * cgroup_bpf_release_fn() - callback used to schedule releasing
 *                           of bpf cgroup data
 * @ref: percpu ref counter structure
 */
static void cgroup_bpf_release_fn(struct percpu_ref *ref)
{
        struct cgroup *cgrp = container_of(ref, struct cgroup, bpf.refcnt);

        INIT_WORK(&cgrp->bpf.release_work, cgroup_bpf_release);
        queue_work(system_wq, &cgrp->bpf.release_work);
}

/* Get underlying bpf_prog of bpf_prog_list entry, regardless if it's through
 * link or direct prog.
 */
static struct bpf_prog *prog_list_prog(struct bpf_prog_list *pl)
{
        if (pl->prog)
                return pl->prog;
        if (pl->link)
                return pl->link->link.prog;
        return NULL;
}

/* 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 (!prog_list_prog(pl))
                        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)
{
        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 **array)
{
        struct bpf_prog_array_item *item;
        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))
                        continue;

                list_for_each_entry(pl, &p->bpf.progs[type], node) {
                        if (!prog_list_prog(pl))
                                continue;

                        item = &progs->items[cnt];
                        item->prog = prog_list_prog(pl);
                        bpf_cgroup_storages_assign(item->cgroup_storage,
                                                   pl->storage);
                        cnt++;
                }
        } while ((p = cgroup_parent(p)));

        *array = progs;
        return 0;
}

static void activate_effective_progs(struct cgroup *cgrp,
                                     enum bpf_attach_type type,
                                     struct bpf_prog_array *old_array)
{
        old_array = rcu_replace_pointer(cgrp->bpf.effective[type], old_array,
                                        lockdep_is_held(&cgroup_mutex));
        /* 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 *arrays[NR] = {};
        struct cgroup *p;
        int ret, i;

        ret = percpu_ref_init(&cgrp->bpf.refcnt, cgroup_bpf_release_fn, 0,
                              GFP_KERNEL);
        if (ret)
                return ret;

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_get(p);

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

        INIT_LIST_HEAD(&cgrp->bpf.storages);

        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]);

        for (p = cgroup_parent(cgrp); p; p = cgroup_parent(p))
                cgroup_bpf_put(p);

        percpu_ref_exit(&cgrp->bpf.refcnt);

        return -ENOMEM;
}

static int update_effective_progs(struct cgroup *cgrp,
                                  enum bpf_attach_type type)
{
        struct cgroup_subsys_state *css;
        int err;

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

                if (percpu_ref_is_zero(&desc->bpf.refcnt))
                        continue;

                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);

                if (percpu_ref_is_zero(&desc->bpf.refcnt)) {
                        if (unlikely(desc->bpf.inactive)) {
                                bpf_prog_array_free(desc->bpf.inactive);
                                desc->bpf.inactive = NULL;
                        }
                        continue;
                }

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

        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;
        }

        return err;
}

#define BPF_CGROUP_MAX_PROGS 64

static struct bpf_prog_list *find_attach_entry(struct list_head *progs,
                                               struct bpf_prog *prog,
                                               struct bpf_cgroup_link *link,
                                               struct bpf_prog *replace_prog,
                                               bool allow_multi)
{
        struct bpf_prog_list *pl;

        /* single-attach case */
        if (!allow_multi) {
                if (list_empty(progs))
                        return NULL;
                return list_first_entry(progs, typeof(*pl), node);
        }

        list_for_each_entry(pl, progs, node) {
                if (prog && pl->prog == prog && prog != replace_prog)
                        /* disallow attaching the same prog twice */
                        return ERR_PTR(-EINVAL);
                if (link && pl->link == link)
                        /* disallow attaching the same link twice */
                        return ERR_PTR(-EINVAL);
        }

        /* direct prog multi-attach w/ replacement case */
        if (replace_prog) {
                list_for_each_entry(pl, progs, node) {
                        if (pl->prog == replace_prog)
                                /* a match found */
                                return pl;
                }
                /* prog to replace not found for cgroup */
                return ERR_PTR(-ENOENT);
        }

        return NULL;
}

/**
 * __cgroup_bpf_attach() - Attach the program or the link to a cgroup, and
 *                         propagate the change to descendants
 * @cgrp: The cgroup which descendants to traverse
 * @prog: A program to attach
 * @link: A link to attach
 * @replace_prog: Previously attached program to replace if BPF_F_REPLACE is set
 * @type: Type of attach operation
 * @flags: Option flags
 *
 * Exactly one of @prog or @link can be non-null.
 * Must be called with cgroup_mutex held.
 */
int __cgroup_bpf_attach(struct cgroup *cgrp,
                        struct bpf_prog *prog, struct bpf_prog *replace_prog,
                        struct bpf_cgroup_link *link,
                        enum bpf_attach_type type, u32 flags)
{
        u32 saved_flags = (flags & (BPF_F_ALLOW_OVERRIDE | BPF_F_ALLOW_MULTI));
        struct list_head *progs = &cgrp->bpf.progs[type];
        struct bpf_prog *old_prog = NULL;
        struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
        struct bpf_cgroup_storage *new_storage[MAX_BPF_CGROUP_STORAGE_TYPE] = {};
        struct bpf_prog_list *pl;
        int err;

        if (((flags & BPF_F_ALLOW_OVERRIDE) && (flags & BPF_F_ALLOW_MULTI)) ||
            ((flags & BPF_F_REPLACE) && !(flags & BPF_F_ALLOW_MULTI)))
                /* invalid combination */
                return -EINVAL;
        if (link && (prog || replace_prog))
                /* only either link or prog/replace_prog can be specified */
                return -EINVAL;
        if (!!replace_prog != !!(flags & BPF_F_REPLACE))
                /* replace_prog implies BPF_F_REPLACE, and vice versa */
                return -EINVAL;

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

        if (!list_empty(progs) && cgrp->bpf.flags[type] != saved_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;

        pl = find_attach_entry(progs, prog, link, replace_prog,
                               flags & BPF_F_ALLOW_MULTI);
        if (IS_ERR(pl))
                return PTR_ERR(pl);

        if (bpf_cgroup_storages_alloc(storage, new_storage, type,
                                      prog ? : link->link.prog, cgrp))
                return -ENOMEM;

        if (pl) {
                old_prog = pl->prog;
        } else {
                pl = kmalloc(sizeof(*pl), GFP_KERNEL);
                if (!pl) {
                        bpf_cgroup_storages_free(new_storage);
                        return -ENOMEM;
                }
                list_add_tail(&pl->node, progs);
        }

        pl->prog = prog;
        pl->link = link;
        bpf_cgroup_storages_assign(pl->storage, storage);
        cgrp->bpf.flags[type] = saved_flags;

        err = update_effective_progs(cgrp, type);
        if (err)
                goto cleanup;

        if (old_prog)
                bpf_prog_put(old_prog);
        else
                static_branch_inc(&cgroup_bpf_enabled_key[type]);
        bpf_cgroup_storages_link(new_storage, cgrp, type);
        return 0;

cleanup:
        if (old_prog) {
                pl->prog = old_prog;
                pl->link = NULL;
        }
        bpf_cgroup_storages_free(new_storage);
        if (!old_prog) {
                list_del(&pl->node);
                kfree(pl);
        }
        return err;
}

/* Swap updated BPF program for given link in effective program arrays across
 * all descendant cgroups. This function is guaranteed to succeed.
 */
static void replace_effective_prog(struct cgroup *cgrp,
                                   enum bpf_attach_type type,
                                   struct bpf_cgroup_link *link)
{
        struct bpf_prog_array_item *item;
        struct cgroup_subsys_state *css;
        struct bpf_prog_array *progs;
        struct bpf_prog_list *pl;
        struct list_head *head;
        struct cgroup *cg;
        int pos;

        css_for_each_descendant_pre(css, &cgrp->self) {
                struct cgroup *desc = container_of(css, struct cgroup, self);

                if (percpu_ref_is_zero(&desc->bpf.refcnt))
                        continue;

                /* find position of link in effective progs array */
                for (pos = 0, cg = desc; cg; cg = cgroup_parent(cg)) {
                        if (pos && !(cg->bpf.flags[type] & BPF_F_ALLOW_MULTI))
                                continue;

                        head = &cg->bpf.progs[type];
                        list_for_each_entry(pl, head, node) {
                                if (!prog_list_prog(pl))
                                        continue;
                                if (pl->link == link)
                                        goto found;
                                pos++;
                        }
                }
found:
                BUG_ON(!cg);
                progs = rcu_dereference_protected(
                                desc->bpf.effective[type],
                                lockdep_is_held(&cgroup_mutex));
                item = &progs->items[pos];
                WRITE_ONCE(item->prog, link->link.prog);
        }
}

/**
 * __cgroup_bpf_replace() - Replace link's program and propagate the change
 *                          to descendants
 * @cgrp: The cgroup which descendants to traverse
 * @link: A link for which to replace BPF program
 * @type: Type of attach operation
 *
 * Must be called with cgroup_mutex held.
 */
static int __cgroup_bpf_replace(struct cgroup *cgrp,
                                struct bpf_cgroup_link *link,
                                struct bpf_prog *new_prog)
{
        struct list_head *progs = &cgrp->bpf.progs[link->type];
        struct bpf_prog *old_prog;
        struct bpf_prog_list *pl;
        bool found = false;

        if (link->link.prog->type != new_prog->type)
                return -EINVAL;

        list_for_each_entry(pl, progs, node) {
                if (pl->link == link) {
                        found = true;
                        break;
                }
        }
        if (!found)
                return -ENOENT;

        old_prog = xchg(&link->link.prog, new_prog);
        replace_effective_prog(cgrp, link->type, link);
        bpf_prog_put(old_prog);
        return 0;
}

static int cgroup_bpf_replace(struct bpf_link *link, struct bpf_prog *new_prog,
                              struct bpf_prog *old_prog)
{
        struct bpf_cgroup_link *cg_link;
        int ret;

        cg_link = container_of(link, struct bpf_cgroup_link, link);

        mutex_lock(&cgroup_mutex);
        /* link might have been auto-released by dying cgroup, so fail */
        if (!cg_link->cgroup) {
                ret = -ENOLINK;
                goto out_unlock;
        }
        if (old_prog && link->prog != old_prog) {
                ret = -EPERM;
                goto out_unlock;
        }
        ret = __cgroup_bpf_replace(cg_link->cgroup, cg_link, new_prog);
out_unlock:
        mutex_unlock(&cgroup_mutex);
        return ret;
}

static struct bpf_prog_list *find_detach_entry(struct list_head *progs,
                                               struct bpf_prog *prog,
                                               struct bpf_cgroup_link *link,
                                               bool allow_multi)
{
        struct bpf_prog_list *pl;

        if (!allow_multi) {
                if (list_empty(progs))
                        /* report error when trying to detach and nothing is attached */
                        return ERR_PTR(-ENOENT);

                /* to maintain backward compatibility NONE and OVERRIDE cgroups
                 * allow detaching with invalid FD (prog==NULL) in legacy mode
                 */
                return list_first_entry(progs, typeof(*pl), node);
        }

        if (!prog && !link)
                /* to detach MULTI prog the user has to specify valid FD
                 * of the program or link to be detached
                 */
                return ERR_PTR(-EINVAL);

        /* find the prog or link and detach it */
        list_for_each_entry(pl, progs, node) {
                if (pl->prog == prog && pl->link == link)
                        return pl;
        }
        return ERR_PTR(-ENOENT);
}

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

        if (prog && link)
                /* only one of prog or link can be specified */
                return -EINVAL;

        pl = find_detach_entry(progs, prog, link, flags & BPF_F_ALLOW_MULTI);
        if (IS_ERR(pl))
                return PTR_ERR(pl);

        /* mark it deleted, so it's ignored while recomputing effective */
        old_prog = pl->prog;
        pl->prog = NULL;
        pl->link = NULL;

        err = update_effective_progs(cgrp, type);
        if (err)
                goto cleanup;

        /* 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;
        if (old_prog)
                bpf_prog_put(old_prog);
        static_branch_dec(&cgroup_bpf_enabled_key[type]);
        return 0;

cleanup:
        /* restore back prog or link */
        pl->prog = old_prog;
        pl->link = link;
        return err;
}

/* Must be called with cgroup_mutex held to avoid races. */
int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
                       union bpf_attr __user *uattr)
{
        __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
        enum bpf_attach_type type = attr->query.attach_type;
        struct list_head *progs = &cgrp->bpf.progs[type];
        u32 flags = cgrp->bpf.flags[type];
        struct bpf_prog_array *effective;
        struct bpf_prog *prog;
        int cnt, ret = 0, i;

        effective = rcu_dereference_protected(cgrp->bpf.effective[type],
                                              lockdep_is_held(&cgroup_mutex));

        if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
                cnt = bpf_prog_array_length(effective);
        else
                cnt = prog_list_length(progs);

        if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
                return -EFAULT;
        if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt)))
                return -EFAULT;
        if (attr->query.prog_cnt == 0 || !prog_ids || !cnt)
                /* return early if user requested only program count + flags */
                return 0;
        if (attr->query.prog_cnt < cnt) {
                cnt = attr->query.prog_cnt;
                ret = -ENOSPC;
        }

        if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
                return bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
        } else {
                struct bpf_prog_list *pl;
                u32 id;

                i = 0;
                list_for_each_entry(pl, progs, node) {
                        prog = prog_list_prog(pl);
                        id = prog->aux->id;
                        if (copy_to_user(prog_ids + i, &id, sizeof(id)))
                                return -EFAULT;
                        if (++i == cnt)
                                break;
                }
        }
        return ret;
}

int cgroup_bpf_prog_attach(const union bpf_attr *attr,
                           enum bpf_prog_type ptype, struct bpf_prog *prog)
{
        struct bpf_prog *replace_prog = NULL;
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        if ((attr->attach_flags & BPF_F_ALLOW_MULTI) &&
            (attr->attach_flags & BPF_F_REPLACE)) {
                replace_prog = bpf_prog_get_type(attr->replace_bpf_fd, ptype);
                if (IS_ERR(replace_prog)) {
                        cgroup_put(cgrp);
                        return PTR_ERR(replace_prog);
                }
        }

        ret = cgroup_bpf_attach(cgrp, prog, replace_prog, NULL,
                                attr->attach_type, attr->attach_flags);

        if (replace_prog)
                bpf_prog_put(replace_prog);
        cgroup_put(cgrp);
        return ret;
}

int cgroup_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
{
        struct bpf_prog *prog;
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
        if (IS_ERR(prog))
                prog = NULL;

        ret = cgroup_bpf_detach(cgrp, prog, attr->attach_type);
        if (prog)
                bpf_prog_put(prog);

        cgroup_put(cgrp);
        return ret;
}

static void bpf_cgroup_link_release(struct bpf_link *link)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        struct cgroup *cg;

        /* link might have been auto-detached by dying cgroup already,
         * in that case our work is done here
         */
        if (!cg_link->cgroup)
                return;

        mutex_lock(&cgroup_mutex);

        /* re-check cgroup under lock again */
        if (!cg_link->cgroup) {
                mutex_unlock(&cgroup_mutex);
                return;
        }

        WARN_ON(__cgroup_bpf_detach(cg_link->cgroup, NULL, cg_link,
                                    cg_link->type));

        cg = cg_link->cgroup;
        cg_link->cgroup = NULL;

        mutex_unlock(&cgroup_mutex);

        cgroup_put(cg);
}

static void bpf_cgroup_link_dealloc(struct bpf_link *link)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);

        kfree(cg_link);
}

static int bpf_cgroup_link_detach(struct bpf_link *link)
{
        bpf_cgroup_link_release(link);

        return 0;
}

static void bpf_cgroup_link_show_fdinfo(const struct bpf_link *link,
                                        struct seq_file *seq)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        u64 cg_id = 0;

        mutex_lock(&cgroup_mutex);
        if (cg_link->cgroup)
                cg_id = cgroup_id(cg_link->cgroup);
        mutex_unlock(&cgroup_mutex);

        seq_printf(seq,
                   "cgroup_id:\t%llu\n"
                   "attach_type:\t%d\n",
                   cg_id,
                   cg_link->type);
}

static int bpf_cgroup_link_fill_link_info(const struct bpf_link *link,
                                          struct bpf_link_info *info)
{
        struct bpf_cgroup_link *cg_link =
                container_of(link, struct bpf_cgroup_link, link);
        u64 cg_id = 0;

        mutex_lock(&cgroup_mutex);
        if (cg_link->cgroup)
                cg_id = cgroup_id(cg_link->cgroup);
        mutex_unlock(&cgroup_mutex);

        info->cgroup.cgroup_id = cg_id;
        info->cgroup.attach_type = cg_link->type;
        return 0;
}

static const struct bpf_link_ops bpf_cgroup_link_lops = {
        .release = bpf_cgroup_link_release,
        .dealloc = bpf_cgroup_link_dealloc,
        .detach = bpf_cgroup_link_detach,
        .update_prog = cgroup_bpf_replace,
        .show_fdinfo = bpf_cgroup_link_show_fdinfo,
        .fill_link_info = bpf_cgroup_link_fill_link_info,
};

int cgroup_bpf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
        struct bpf_link_primer link_primer;
        struct bpf_cgroup_link *link;
        struct cgroup *cgrp;
        int err;

        if (attr->link_create.flags)
                return -EINVAL;

        cgrp = cgroup_get_from_fd(attr->link_create.target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        link = kzalloc(sizeof(*link), GFP_USER);
        if (!link) {
                err = -ENOMEM;
                goto out_put_cgroup;
        }
        bpf_link_init(&link->link, BPF_LINK_TYPE_CGROUP, &bpf_cgroup_link_lops,
                      prog);
        link->cgroup = cgrp;
        link->type = attr->link_create.attach_type;

        err  = bpf_link_prime(&link->link, &link_primer);
        if (err) {
                kfree(link);
                goto out_put_cgroup;
        }

        err = cgroup_bpf_attach(cgrp, NULL, NULL, link, link->type,
                                BPF_F_ALLOW_MULTI);
        if (err) {
                bpf_link_cleanup(&link_primer);
                goto out_put_cgroup;
        }

        return bpf_link_settle(&link_primer);

out_put_cgroup:
        cgroup_put(cgrp);
        return err;
}

int cgroup_bpf_prog_query(const union bpf_attr *attr,
                          union bpf_attr __user *uattr)
{
        struct cgroup *cgrp;
        int ret;

        cgrp = cgroup_get_from_fd(attr->query.target_fd);
        if (IS_ERR(cgrp))
                return PTR_ERR(cgrp);

        ret = cgroup_bpf_query(cgrp, attr, uattr);

        cgroup_put(cgrp);
        return ret;
}

/**
 * __cgroup_bpf_run_filter_skb() - 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.
 *
 * For egress packets, this function can return:
 *   NET_XMIT_SUCCESS    (0)    - continue with packet output
 *   NET_XMIT_DROP       (1)    - drop packet and notify TCP to call cwr
 *   NET_XMIT_CN         (2)    - continue with packet output and notify TCP
 *                                to call cwr
 *   -EPERM                     - drop packet
 *
 * For ingress packets, this function will return -EPERM if any
 * attached program was found and if it returned != 1 during execution.
 * Otherwise 0 is returned.
 */
int __cgroup_bpf_run_filter_skb(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;
        void *saved_data_end;
        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);

        /* compute pointers for the bpf prog */
        bpf_compute_and_save_data_end(skb, &saved_data_end);

        if (type == BPF_CGROUP_INET_EGRESS) {
                ret = BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY(
                        cgrp->bpf.effective[type], skb, __bpf_prog_run_save_cb);
        } else {
                ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
                                          __bpf_prog_run_save_cb);
                ret = (ret == 1 ? 0 : -EPERM);
        }
        bpf_restore_data_end(skb, saved_data_end);
        __skb_pull(skb, offset);
        skb->sk = save_sk;

        return ret;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);

/**
 * __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);
        int ret;

        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sk, BPF_PROG_RUN);
        return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);

/**
 * __cgroup_bpf_run_filter_sock_addr() - Run a program on a sock and
 *                                       provided by user sockaddr
 * @sk: sock struct that will use sockaddr
 * @uaddr: sockaddr struct provided by user
 * @type: The type of program to be exectuted
 * @t_ctx: Pointer to attach type specific context
 * @flags: Pointer to u32 which contains higher bits of BPF program
 *         return value (OR'ed together).
 *
 * socket is expected to be of type INET or INET6.
 *
 * This function will return %-EPERM if an attached program is found and
 * returned value != 1 during execution. In all other cases, 0 is returned.
 */
int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
                                      struct sockaddr *uaddr,
                                      enum bpf_attach_type type,
                                      void *t_ctx,
                                      u32 *flags)
{
        struct bpf_sock_addr_kern ctx = {
                .sk = sk,
                .uaddr = uaddr,
                .t_ctx = t_ctx,
        };
        struct sockaddr_storage unspec;
        struct cgroup *cgrp;
        int ret;

        /* Check socket family since not all sockets represent network
         * endpoint (e.g. AF_UNIX).
         */
        if (sk->sk_family != AF_INET && sk->sk_family != AF_INET6)
                return 0;

        if (!ctx.uaddr) {
                memset(&unspec, 0, sizeof(unspec));
                ctx.uaddr = (struct sockaddr *)&unspec;
        }

        cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        ret = BPF_PROG_RUN_ARRAY_FLAGS(cgrp->bpf.effective[type], &ctx,
                                       BPF_PROG_RUN, flags);

        return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_addr);

/**
 * __cgroup_bpf_run_filter_sock_ops() - Run a program on a sock
 * @sk: socket to get cgroup from
 * @sock_ops: bpf_sock_ops_kern struct to pass to program. Contains
 * sk with connection information (IP addresses, etc.) May not contain
 * cgroup info if it is a req sock.
 * @type: The type of program to be exectuted
 *
 * socket passed is expected to be of type INET or INET6.
 *
 * The program type passed in via @type must be suitable for sock_ops
 * 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_sock_ops(struct sock *sk,
                                     struct bpf_sock_ops_kern *sock_ops,
                                     enum bpf_attach_type type)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        int ret;

        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], sock_ops,
                                 BPF_PROG_RUN);
        return ret == 1 ? 0 : -EPERM;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_sock_ops);

int __cgroup_bpf_check_dev_permission(short dev_type, u32 major, u32 minor,
                                      short access, enum bpf_attach_type type)
{
        struct cgroup *cgrp;
        struct bpf_cgroup_dev_ctx ctx = {
                .access_type = (access << 16) | dev_type,
                .major = major,
                .minor = minor,
        };
        int allow = 1;

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        allow = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx,
                                   BPF_PROG_RUN);
        rcu_read_unlock();

        return !allow;
}

static const struct bpf_func_proto *
cgroup_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_get_current_uid_gid:
                return &bpf_get_current_uid_gid_proto;
        case BPF_FUNC_get_local_storage:
                return &bpf_get_local_storage_proto;
        case BPF_FUNC_get_current_cgroup_id:
                return &bpf_get_current_cgroup_id_proto;
        case BPF_FUNC_perf_event_output:
                return &bpf_event_output_data_proto;
        default:
                return bpf_base_func_proto(func_id);
        }
}

static const struct bpf_func_proto *
cgroup_dev_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        return cgroup_base_func_proto(func_id, prog);
}

static bool cgroup_dev_is_valid_access(int off, int size,
                                       enum bpf_access_type type,
                                       const struct bpf_prog *prog,
                                       struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (type == BPF_WRITE)
                return false;

        if (off < 0 || off + size > sizeof(struct bpf_cgroup_dev_ctx))
                return false;
        /* The verifier guarantees that size > 0. */
        if (off % size != 0)
                return false;

        switch (off) {
        case bpf_ctx_range(struct bpf_cgroup_dev_ctx, access_type):
                bpf_ctx_record_field_size(info, size_default);
                if (!bpf_ctx_narrow_access_ok(off, size, size_default))
                        return false;
                break;
        default:
                if (size != size_default)
                        return false;
        }

        return true;
}

const struct bpf_prog_ops cg_dev_prog_ops = {
};

const struct bpf_verifier_ops cg_dev_verifier_ops = {
        .get_func_proto         = cgroup_dev_func_proto,
        .is_valid_access        = cgroup_dev_is_valid_access,
};

/**
 * __cgroup_bpf_run_filter_sysctl - Run a program on sysctl
 *
 * @head: sysctl table header
 * @table: sysctl table
 * @write: sysctl is being read (= 0) or written (= 1)
 * @buf: pointer to buffer (in and out)
 * @pcount: value-result argument: value is size of buffer pointed to by @buf,
 *      result is size of @new_buf if program set new value, initial value
 *      otherwise
 * @ppos: value-result argument: value is position at which read from or write
 *      to sysctl is happening, result is new position if program overrode it,
 *      initial value otherwise
 * @type: type of program to be executed
 *
 * Program is run when sysctl is being accessed, either read or written, and
 * can allow or deny such access.
 *
 * This function will return %-EPERM if an attached program is found and
 * returned value != 1 during execution. In all other cases 0 is returned.
 */
int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
                                   struct ctl_table *table, int write,
                                   char **buf, size_t *pcount, loff_t *ppos,
                                   enum bpf_attach_type type)
{
        struct bpf_sysctl_kern ctx = {
                .head = head,
                .table = table,
                .write = write,
                .ppos = ppos,
                .cur_val = NULL,
                .cur_len = PAGE_SIZE,
                .new_val = NULL,
                .new_len = 0,
                .new_updated = 0,
        };
        struct cgroup *cgrp;
        loff_t pos = 0;
        int ret;

        ctx.cur_val = kmalloc_track_caller(ctx.cur_len, GFP_KERNEL);
        if (!ctx.cur_val ||
            table->proc_handler(table, 0, ctx.cur_val, &ctx.cur_len, &pos)) {
                /* Let BPF program decide how to proceed. */
                ctx.cur_len = 0;
        }

        if (write && *buf && *pcount) {
                /* BPF program should be able to override new value with a
                 * buffer bigger than provided by user.
                 */
                ctx.new_val = kmalloc_track_caller(PAGE_SIZE, GFP_KERNEL);
                ctx.new_len = min_t(size_t, PAGE_SIZE, *pcount);
                if (ctx.new_val) {
                        memcpy(ctx.new_val, *buf, ctx.new_len);
                } else {
                        /* Let BPF program decide how to proceed. */
                        ctx.new_len = 0;
                }
        }

        rcu_read_lock();
        cgrp = task_dfl_cgroup(current);
        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], &ctx, BPF_PROG_RUN);
        rcu_read_unlock();

        kfree(ctx.cur_val);

        if (ret == 1 && ctx.new_updated) {
                kfree(*buf);
                *buf = ctx.new_val;
                *pcount = ctx.new_len;
        } else {
                kfree(ctx.new_val);
        }

        return ret == 1 ? 0 : -EPERM;
}

#ifdef CONFIG_NET
static bool __cgroup_bpf_prog_array_is_empty(struct cgroup *cgrp,
                                             enum bpf_attach_type attach_type)
{
        struct bpf_prog_array *prog_array;
        bool empty;

        rcu_read_lock();
        prog_array = rcu_dereference(cgrp->bpf.effective[attach_type]);
        empty = bpf_prog_array_is_empty(prog_array);
        rcu_read_unlock();

        return empty;
}

static int sockopt_alloc_buf(struct bpf_sockopt_kern *ctx, int max_optlen,
                             struct bpf_sockopt_buf *buf)
{
        if (unlikely(max_optlen < 0))
                return -EINVAL;

        if (unlikely(max_optlen > PAGE_SIZE)) {
                /* We don't expose optvals that are greater than PAGE_SIZE
                 * to the BPF program.
                 */
                max_optlen = PAGE_SIZE;
        }

        if (max_optlen <= sizeof(buf->data)) {
                /* When the optval fits into BPF_SOCKOPT_KERN_BUF_SIZE
                 * bytes avoid the cost of kzalloc.
                 */
                ctx->optval = buf->data;
                ctx->optval_end = ctx->optval + max_optlen;
                return max_optlen;
        }

        ctx->optval = kzalloc(max_optlen, GFP_USER);
        if (!ctx->optval)
                return -ENOMEM;

        ctx->optval_end = ctx->optval + max_optlen;

        return max_optlen;
}

static void sockopt_free_buf(struct bpf_sockopt_kern *ctx,
                             struct bpf_sockopt_buf *buf)
{
        if (ctx->optval == buf->data)
                return;
        kfree(ctx->optval);
}

static bool sockopt_buf_allocated(struct bpf_sockopt_kern *ctx,
                                  struct bpf_sockopt_buf *buf)
{
        return ctx->optval != buf->data;
}

int __cgroup_bpf_run_filter_setsockopt(struct sock *sk, int *level,
                                       int *optname, char __user *optval,
                                       int *optlen, char **kernel_optval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_buf buf = {};
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = *level,
                .optname = *optname,
        };
        int ret, max_optlen;

        /* Opportunistic check to see whether we have any BPF program
         * attached to the hook so we don't waste time allocating
         * memory and locking the socket.
         */
        if (__cgroup_bpf_prog_array_is_empty(cgrp, BPF_CGROUP_SETSOCKOPT))
                return 0;

        /* Allocate a bit more than the initial user buffer for
         * BPF program. The canonical use case is overriding
         * TCP_CONGESTION(nv) to TCP_CONGESTION(cubic).
         */
        max_optlen = max_t(int, 16, *optlen);

        max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
        if (max_optlen < 0)
                return max_optlen;

        ctx.optlen = *optlen;

        if (copy_from_user(ctx.optval, optval, min(*optlen, max_optlen)) != 0) {
                ret = -EFAULT;
                goto out;
        }

        lock_sock(sk);
        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_SETSOCKOPT],
                                 &ctx, BPF_PROG_RUN);
        release_sock(sk);

        if (!ret) {
                ret = -EPERM;
                goto out;
        }

        if (ctx.optlen == -1) {
                /* optlen set to -1, bypass kernel */
                ret = 1;
        } else if (ctx.optlen > max_optlen || ctx.optlen < -1) {
                /* optlen is out of bounds */
                ret = -EFAULT;
        } else {
                /* optlen within bounds, run kernel handler */
                ret = 0;

                /* export any potential modifications */
                *level = ctx.level;
                *optname = ctx.optname;

                /* optlen == 0 from BPF indicates that we should
                 * use original userspace data.
                 */
                if (ctx.optlen != 0) {
                        *optlen = ctx.optlen;
                        /* We've used bpf_sockopt_kern->buf as an intermediary
                         * storage, but the BPF program indicates that we need
                         * to pass this data to the kernel setsockopt handler.
                         * No way to export on-stack buf, have to allocate a
                         * new buffer.
                         */
                        if (!sockopt_buf_allocated(&ctx, &buf)) {
                                void *p = kmalloc(ctx.optlen, GFP_USER);

                                if (!p) {
                                        ret = -ENOMEM;
                                        goto out;
                                }
                                memcpy(p, ctx.optval, ctx.optlen);
                                *kernel_optval = p;
                        } else {
                                *kernel_optval = ctx.optval;
                        }
                        /* export and don't free sockopt buf */
                        return 0;
                }
        }

out:
        sockopt_free_buf(&ctx, &buf);
        return ret;
}

int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
                                       int optname, char __user *optval,
                                       int __user *optlen, int max_optlen,
                                       int retval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_buf buf = {};
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = level,
                .optname = optname,
                .retval = retval,
        };
        int ret;

        /* Opportunistic check to see whether we have any BPF program
         * attached to the hook so we don't waste time allocating
         * memory and locking the socket.
         */
        if (__cgroup_bpf_prog_array_is_empty(cgrp, BPF_CGROUP_GETSOCKOPT))
                return retval;

        ctx.optlen = max_optlen;

        max_optlen = sockopt_alloc_buf(&ctx, max_optlen, &buf);
        if (max_optlen < 0)
                return max_optlen;

        if (!retval) {
                /* If kernel getsockopt finished successfully,
                 * copy whatever was returned to the user back
                 * into our temporary buffer. Set optlen to the
                 * one that kernel returned as well to let
                 * BPF programs inspect the value.
                 */

                if (get_user(ctx.optlen, optlen)) {
                        ret = -EFAULT;
                        goto out;
                }

                if (ctx.optlen < 0) {
                        ret = -EFAULT;
                        goto out;
                }

                if (copy_from_user(ctx.optval, optval,
                                   min(ctx.optlen, max_optlen)) != 0) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        lock_sock(sk);
        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
                                 &ctx, BPF_PROG_RUN);
        release_sock(sk);

        if (!ret) {
                ret = -EPERM;
                goto out;
        }

        if (ctx.optlen > max_optlen || ctx.optlen < 0) {
                ret = -EFAULT;
                goto out;
        }

        /* BPF programs only allowed to set retval to 0, not some
         * arbitrary value.
         */
        if (ctx.retval != 0 && ctx.retval != retval) {
                ret = -EFAULT;
                goto out;
        }

        if (ctx.optlen != 0) {
                if (copy_to_user(optval, ctx.optval, ctx.optlen) ||
                    put_user(ctx.optlen, optlen)) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        ret = ctx.retval;

out:
        sockopt_free_buf(&ctx, &buf);
        return ret;
}

int __cgroup_bpf_run_filter_getsockopt_kern(struct sock *sk, int level,
                                            int optname, void *optval,
                                            int *optlen, int retval)
{
        struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
        struct bpf_sockopt_kern ctx = {
                .sk = sk,
                .level = level,
                .optname = optname,
                .retval = retval,
                .optlen = *optlen,
                .optval = optval,
                .optval_end = optval + *optlen,
        };
        int ret;

        /* Note that __cgroup_bpf_run_filter_getsockopt doesn't copy
         * user data back into BPF buffer when reval != 0. This is
         * done as an optimization to avoid extra copy, assuming
         * kernel won't populate the data in case of an error.
         * Here we always pass the data and memset() should
         * be called if that data shouldn't be "exported".
         */

        ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[BPF_CGROUP_GETSOCKOPT],
                                 &ctx, BPF_PROG_RUN);
        if (!ret)
                return -EPERM;

        if (ctx.optlen > *optlen)
                return -EFAULT;

        /* BPF programs only allowed to set retval to 0, not some
         * arbitrary value.
         */
        if (ctx.retval != 0 && ctx.retval != retval)
                return -EFAULT;

        /* BPF programs can shrink the buffer, export the modifications.
         */
        if (ctx.optlen != 0)
                *optlen = ctx.optlen;

        return ctx.retval;
}
#endif

static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
                              size_t *lenp)
{
        ssize_t tmp_ret = 0, ret;

        if (dir->header.parent) {
                tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp);
                if (tmp_ret < 0)
                        return tmp_ret;
        }

        ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp);
        if (ret < 0)
                return ret;
        *bufp += ret;
        *lenp -= ret;
        ret += tmp_ret;

        /* Avoid leading slash. */
        if (!ret)
                return ret;

        tmp_ret = strscpy(*bufp, "/", *lenp);
        if (tmp_ret < 0)
                return tmp_ret;
        *bufp += tmp_ret;
        *lenp -= tmp_ret;

        return ret + tmp_ret;
}

BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf,
           size_t, buf_len, u64, flags)
{
        ssize_t tmp_ret = 0, ret;

        if (!buf)
                return -EINVAL;

        if (!(flags & BPF_F_SYSCTL_BASE_NAME)) {
                if (!ctx->head)
                        return -EINVAL;
                tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len);
                if (tmp_ret < 0)
                        return tmp_ret;
        }

        ret = strscpy(buf, ctx->table->procname, buf_len);

        return ret < 0 ? ret : tmp_ret + ret;
}

static const struct bpf_func_proto bpf_sysctl_get_name_proto = {
        .func           = bpf_sysctl_get_name,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_MEM,
        .arg3_type      = ARG_CONST_SIZE,
        .arg4_type      = ARG_ANYTHING,
};

static int copy_sysctl_value(char *dst, size_t dst_len, char *src,
                             size_t src_len)
{
        if (!dst)
                return -EINVAL;

        if (!dst_len)
                return -E2BIG;

        if (!src || !src_len) {
                memset(dst, 0, dst_len);
                return -EINVAL;
        }

        memcpy(dst, src, min(dst_len, src_len));

        if (dst_len > src_len) {
                memset(dst + src_len, '\0', dst_len - src_len);
                return src_len;
        }

        dst[dst_len - 1] = '\0';

        return -E2BIG;
}

BPF_CALL_3(bpf_sysctl_get_current_value, struct bpf_sysctl_kern *, ctx,
           char *, buf, size_t, buf_len)
{
        return copy_sysctl_value(buf, buf_len, ctx->cur_val, ctx->cur_len);
}

static const struct bpf_func_proto bpf_sysctl_get_current_value_proto = {
        .func           = bpf_sysctl_get_current_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

BPF_CALL_3(bpf_sysctl_get_new_value, struct bpf_sysctl_kern *, ctx, char *, buf,
           size_t, buf_len)
{
        if (!ctx->write) {
                if (buf && buf_len)
                        memset(buf, '\0', buf_len);
                return -EINVAL;
        }
        return copy_sysctl_value(buf, buf_len, ctx->new_val, ctx->new_len);
}

static const struct bpf_func_proto bpf_sysctl_get_new_value_proto = {
        .func           = bpf_sysctl_get_new_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_UNINIT_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

BPF_CALL_3(bpf_sysctl_set_new_value, struct bpf_sysctl_kern *, ctx,
           const char *, buf, size_t, buf_len)
{
        if (!ctx->write || !ctx->new_val || !ctx->new_len || !buf || !buf_len)
                return -EINVAL;

        if (buf_len > PAGE_SIZE - 1)
                return -E2BIG;

        memcpy(ctx->new_val, buf, buf_len);
        ctx->new_len = buf_len;
        ctx->new_updated = 1;

        return 0;
}

static const struct bpf_func_proto bpf_sysctl_set_new_value_proto = {
        .func           = bpf_sysctl_set_new_value,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .arg1_type      = ARG_PTR_TO_CTX,
        .arg2_type      = ARG_PTR_TO_MEM,
        .arg3_type      = ARG_CONST_SIZE,
};

static const struct bpf_func_proto *
sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
        case BPF_FUNC_strtol:
                return &bpf_strtol_proto;
        case BPF_FUNC_strtoul:
                return &bpf_strtoul_proto;
        case BPF_FUNC_sysctl_get_name:
                return &bpf_sysctl_get_name_proto;
        case BPF_FUNC_sysctl_get_current_value:
                return &bpf_sysctl_get_current_value_proto;
        case BPF_FUNC_sysctl_get_new_value:
                return &bpf_sysctl_get_new_value_proto;
        case BPF_FUNC_sysctl_set_new_value:
                return &bpf_sysctl_set_new_value_proto;
        default:
                return cgroup_base_func_proto(func_id, prog);
        }
}

static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,
                                   const struct bpf_prog *prog,
                                   struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (off < 0 || off + size > sizeof(struct bpf_sysctl) || off % size)
                return false;

        switch (off) {
        case bpf_ctx_range(struct bpf_sysctl, write):
                if (type != BPF_READ)
                        return false;
                bpf_ctx_record_field_size(info, size_default);
                return bpf_ctx_narrow_access_ok(off, size, size_default);
        case bpf_ctx_range(struct bpf_sysctl, file_pos):
                if (type == BPF_READ) {
                        bpf_ctx_record_field_size(info, size_default);
                        return bpf_ctx_narrow_access_ok(off, size, size_default);
                } else {
                        return size == size_default;
                }
        default:
                return false;
        }
}

static u32 sysctl_convert_ctx_access(enum bpf_access_type type,
                                     const struct bpf_insn *si,
                                     struct bpf_insn *insn_buf,
                                     struct bpf_prog *prog, u32 *target_size)
{
        struct bpf_insn *insn = insn_buf;
        u32 read_size;

        switch (si->off) {
        case offsetof(struct bpf_sysctl, write):
                *insn++ = BPF_LDX_MEM(
                        BPF_SIZE(si->code), si->dst_reg, si->src_reg,
                        bpf_target_off(struct bpf_sysctl_kern, write,
                                       sizeof_field(struct bpf_sysctl_kern,
                                                    write),
                                       target_size));
                break;
        case offsetof(struct bpf_sysctl, file_pos):
                /* ppos is a pointer so it should be accessed via indirect
                 * loads and stores. Also for stores additional temporary
                 * register is used since neither src_reg nor dst_reg can be
                 * overridden.
                 */
                if (type == BPF_WRITE) {
                        int treg = BPF_REG_9;

                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        if (si->src_reg == treg || si->dst_reg == treg)
                                --treg;
                        *insn++ = BPF_STX_MEM(
                                BPF_DW, si->dst_reg, treg,
                                offsetof(struct bpf_sysctl_kern, tmp_reg));
                        *insn++ = BPF_LDX_MEM(
                                BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
                                treg, si->dst_reg,
                                offsetof(struct bpf_sysctl_kern, ppos));
                        *insn++ = BPF_STX_MEM(
                                BPF_SIZEOF(u32), treg, si->src_reg,
                                bpf_ctx_narrow_access_offset(
                                        0, sizeof(u32), sizeof(loff_t)));
                        *insn++ = BPF_LDX_MEM(
                                BPF_DW, treg, si->dst_reg,
                                offsetof(struct bpf_sysctl_kern, tmp_reg));
                } else {
                        *insn++ = BPF_LDX_MEM(
                                BPF_FIELD_SIZEOF(struct bpf_sysctl_kern, ppos),
                                si->dst_reg, si->src_reg,
                                offsetof(struct bpf_sysctl_kern, ppos));
                        read_size = bpf_size_to_bytes(BPF_SIZE(si->code));
                        *insn++ = BPF_LDX_MEM(
                                BPF_SIZE(si->code), si->dst_reg, si->dst_reg,
                                bpf_ctx_narrow_access_offset(
                                        0, read_size, sizeof(loff_t)));
                }
                *target_size = sizeof(u32);
                break;
        }

        return insn - insn_buf;
}

const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
        .get_func_proto         = sysctl_func_proto,
        .is_valid_access        = sysctl_is_valid_access,
        .convert_ctx_access     = sysctl_convert_ctx_access,
};

const struct bpf_prog_ops cg_sysctl_prog_ops = {
};

static const struct bpf_func_proto *
cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
        switch (func_id) {
#ifdef CONFIG_NET
        case BPF_FUNC_sk_storage_get:
                return &bpf_sk_storage_get_proto;
        case BPF_FUNC_sk_storage_delete:
                return &bpf_sk_storage_delete_proto;
#endif
#ifdef CONFIG_INET
        case BPF_FUNC_tcp_sock:
                return &bpf_tcp_sock_proto;
#endif
        default:
                return cgroup_base_func_proto(func_id, prog);
        }
}

static bool cg_sockopt_is_valid_access(int off, int size,
                                       enum bpf_access_type type,
                                       const struct bpf_prog *prog,
                                       struct bpf_insn_access_aux *info)
{
        const int size_default = sizeof(__u32);

        if (off < 0 || off >= sizeof(struct bpf_sockopt))
                return false;

        if (off % size != 0)
                return false;

        if (type == BPF_WRITE) {
                switch (off) {
                case offsetof(struct bpf_sockopt, retval):
                        if (size != size_default)
                                return false;
                        return prog->expected_attach_type ==
                                BPF_CGROUP_GETSOCKOPT;
                case offsetof(struct bpf_sockopt, optname):
                        fallthrough;
                case offsetof(struct bpf_sockopt, level):
                        if (size != size_default)
                                return false;
                        return prog->expected_attach_type ==
                                BPF_CGROUP_SETSOCKOPT;
                case offsetof(struct bpf_sockopt, optlen):
                        return size == size_default;
                default:
                        return false;
                }
        }

        switch (off) {
        case offsetof(struct bpf_sockopt, sk):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_SOCKET;
                break;
        case offsetof(struct bpf_sockopt, optval):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_PACKET;
                break;
        case offsetof(struct bpf_sockopt, optval_end):
                if (size != sizeof(__u64))
                        return false;
                info->reg_type = PTR_TO_PACKET_END;
                break;
        case offsetof(struct bpf_sockopt, retval):
                if (size != size_default)
                        return false;
                return prog->expected_attach_type == BPF_CGROUP_GETSOCKOPT;
        default:
                if (size != size_default)
                        return false;
                break;
        }
        return true;
}

#define CG_SOCKOPT_ACCESS_FIELD(T, F)                                   \
        T(BPF_FIELD_SIZEOF(struct bpf_sockopt_kern, F),                 \
          si->dst_reg, si->src_reg,                                     \
          offsetof(struct bpf_sockopt_kern, F))

static u32 cg_sockopt_convert_ctx_access(enum bpf_access_type type,
                                         const struct bpf_insn *si,
                                         struct bpf_insn *insn_buf,
                                         struct bpf_prog *prog,
                                         u32 *target_size)
{
        struct bpf_insn *insn = insn_buf;

        switch (si->off) {
        case offsetof(struct bpf_sockopt, sk):
                *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, sk);
                break;
        case offsetof(struct bpf_sockopt, level):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, level);
                else
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, level);
                break;
        case offsetof(struct bpf_sockopt, optname):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, optname);
                else
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optname);
                break;
        case offsetof(struct bpf_sockopt, optlen):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, optlen);
                else
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optlen);
                break;
        case offsetof(struct bpf_sockopt, retval):
                if (type == BPF_WRITE)
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_STX_MEM, retval);
                else
                        *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, retval);
                break;
        case offsetof(struct bpf_sockopt, optval):
                *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optval);
                break;
        case offsetof(struct bpf_sockopt, optval_end):
                *insn++ = CG_SOCKOPT_ACCESS_FIELD(BPF_LDX_MEM, optval_end);
                break;
        }

        return insn - insn_buf;
}

static int cg_sockopt_get_prologue(struct bpf_insn *insn_buf,
                                   bool direct_write,
                                   const struct bpf_prog *prog)
{
        /* Nothing to do for sockopt argument. The data is kzalloc'ated.
         */
        return 0;
}

const struct bpf_verifier_ops cg_sockopt_verifier_ops = {
        .get_func_proto         = cg_sockopt_func_proto,
        .is_valid_access        = cg_sockopt_is_valid_access,
        .convert_ctx_access     = cg_sockopt_convert_ctx_access,
        .gen_prologue           = cg_sockopt_get_prologue,
};

const struct bpf_prog_ops cg_sockopt_prog_ops = {
};