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linux-sg2042/kernel/bpf/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_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 = {
};
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