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cgroup.c
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// 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_FALSE(cgroup_bpf_enabled_key);
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_prog *prog)
{
enum bpf_cgroup_storage_type stype;
for_each_cgroup_storage_type(stype) {
storages[stype] = bpf_cgroup_storage_alloc(prog, stype);
if (IS_ERR(storages[stype])) {
storages[stype] = NULL;
bpf_cgroup_storages_free(storages);
return -ENOMEM;
}
}
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);
}
static void bpf_cgroup_storages_unlink(struct bpf_cgroup_storage *storages[])
{
enum bpf_cgroup_storage_type stype;
for_each_cgroup_storage_type(stype)
bpf_cgroup_storage_unlink(storages[stype]);
}
/* 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;
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, *tmp;
list_for_each_entry_safe(pl, tmp, progs, node) {
list_del(&pl->node);
if (pl->prog)
bpf_prog_put(pl->prog);
if (pl->link)
bpf_cgroup_link_auto_detach(pl->link);
bpf_cgroup_storages_unlink(pl->storage);
bpf_cgroup_storages_free(pl->storage);
kfree(pl);
static_branch_dec(&cgroup_bpf_enabled_key);
}
old_array = rcu_dereference_protected(
cgrp->bpf.effective[type],
lockdep_is_held(&cgroup_mutex));
bpf_prog_array_free(old_array);
}
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]);
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)
/* 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 *old_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, prog ? : link->link.prog))
return -ENOMEM;
if (pl) {
old_prog = pl->prog;
bpf_cgroup_storages_unlink(pl->storage);
bpf_cgroup_storages_assign(old_storage, pl->storage);
} else {
pl = kmalloc(sizeof(*pl), GFP_KERNEL);
if (!pl) {
bpf_cgroup_storages_free(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;
bpf_cgroup_storages_free(old_storage);
if (old_prog)
bpf_prog_put(old_prog);
else
static_branch_inc(&cgroup_bpf_enabled_key);
bpf_cgroup_storages_link(pl->storage, cgrp, type);
return 0;
cleanup:
if (old_prog) {
pl->prog = old_prog;
pl->link = NULL;
}
bpf_cgroup_storages_free(pl->storage);
bpf_cgroup_storages_assign(pl->storage, old_storage);
bpf_cgroup_storages_link(pl->storage, cgrp, type);
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);
bpf_cgroup_storages_unlink(pl->storage);
bpf_cgroup_storages_free(pl->storage);
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);
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);
/* 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));
mutex_unlock(&cgroup_mutex);
cgroup_put(cg_link->cgroup);
}
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 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,
.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;
}