[linux.git] / kernel / bpf / bpf_cgrp_storage.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
 */

#include <linux/types.h>
#include <linux/bpf.h>
#include <linux/bpf_local_storage.h>
#include <uapi/linux/btf.h>
#include <linux/btf_ids.h>

DEFINE_BPF_STORAGE_CACHE(cgroup_cache);

static DEFINE_PER_CPU(int, bpf_cgrp_storage_busy);

static void bpf_cgrp_storage_lock(void)
{
	migrate_disable();
	this_cpu_inc(bpf_cgrp_storage_busy);
}

static void bpf_cgrp_storage_unlock(void)
{
	this_cpu_dec(bpf_cgrp_storage_busy);
	migrate_enable();
}

static bool bpf_cgrp_storage_trylock(void)
{
	migrate_disable();
	if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) {
		this_cpu_dec(bpf_cgrp_storage_busy);
		migrate_enable();
		return false;
	}
	return true;
}

static struct bpf_local_storage __rcu **cgroup_storage_ptr(void *owner)
{
	struct cgroup *cg = owner;

	return &cg->bpf_cgrp_storage;
}

void bpf_cgrp_storage_free(struct cgroup *cgroup)
{
	struct bpf_local_storage *local_storage;

	rcu_read_lock();
	local_storage = rcu_dereference(cgroup->bpf_cgrp_storage);
	if (!local_storage) {
		rcu_read_unlock();
		return;
	}

	bpf_cgrp_storage_lock();
	bpf_local_storage_destroy(local_storage);
	bpf_cgrp_storage_unlock();
	rcu_read_unlock();
}

static struct bpf_local_storage_data *
cgroup_storage_lookup(struct cgroup *cgroup, struct bpf_map *map, bool cacheit_lockit)
{
	struct bpf_local_storage *cgroup_storage;
	struct bpf_local_storage_map *smap;

	cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage,
					       bpf_rcu_lock_held());
	if (!cgroup_storage)
		return NULL;

	smap = (struct bpf_local_storage_map *)map;
	return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
}

static void *bpf_cgrp_storage_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_local_storage_data *sdata;
	struct cgroup *cgroup;
	int fd;

	fd = *(int *)key;
	cgroup = cgroup_v1v2_get_from_fd(fd);
	if (IS_ERR(cgroup))
		return ERR_CAST(cgroup);

	bpf_cgrp_storage_lock();
	sdata = cgroup_storage_lookup(cgroup, map, true);
	bpf_cgrp_storage_unlock();
	cgroup_put(cgroup);
	return sdata ? sdata->data : NULL;
}

static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
					 void *value, u64 map_flags)
{
	struct bpf_local_storage_data *sdata;
	struct cgroup *cgroup;
	int fd;

	fd = *(int *)key;
	cgroup = cgroup_v1v2_get_from_fd(fd);
	if (IS_ERR(cgroup))
		return PTR_ERR(cgroup);

	bpf_cgrp_storage_lock();
	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
					 value, map_flags, GFP_ATOMIC);
	bpf_cgrp_storage_unlock();
	cgroup_put(cgroup);
	return PTR_ERR_OR_ZERO(sdata);
}

static int cgroup_storage_delete(struct cgroup *cgroup, struct bpf_map *map)
{
	struct bpf_local_storage_data *sdata;

	sdata = cgroup_storage_lookup(cgroup, map, false);
	if (!sdata)
		return -ENOENT;

	bpf_selem_unlink(SELEM(sdata), false);
	return 0;
}

static long bpf_cgrp_storage_delete_elem(struct bpf_map *map, void *key)
{
	struct cgroup *cgroup;
	int err, fd;

	fd = *(int *)key;
	cgroup = cgroup_v1v2_get_from_fd(fd);
	if (IS_ERR(cgroup))
		return PTR_ERR(cgroup);

	bpf_cgrp_storage_lock();
	err = cgroup_storage_delete(cgroup, map);
	bpf_cgrp_storage_unlock();
	cgroup_put(cgroup);
	return err;
}

static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
	return -ENOTSUPP;
}

static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr)
{
	return bpf_local_storage_map_alloc(attr, &cgroup_cache, true);
}

static void cgroup_storage_map_free(struct bpf_map *map)
{
	bpf_local_storage_map_free(map, &cgroup_cache, NULL);
}

/* *gfp_flags* is a hidden argument provided by the verifier */
BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup,
	   void *, value, u64, flags, gfp_t, gfp_flags)
{
	struct bpf_local_storage_data *sdata;

	WARN_ON_ONCE(!bpf_rcu_lock_held());
	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
		return (unsigned long)NULL;

	if (!cgroup)
		return (unsigned long)NULL;

	if (!bpf_cgrp_storage_trylock())
		return (unsigned long)NULL;

	sdata = cgroup_storage_lookup(cgroup, map, true);
	if (sdata)
		goto unlock;

	/* only allocate new storage, when the cgroup is refcounted */
	if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
	    (flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
		sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
						 value, BPF_NOEXIST, gfp_flags);

unlock:
	bpf_cgrp_storage_unlock();
	return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
}

BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map *, map, struct cgroup *, cgroup)
{
	int ret;

	WARN_ON_ONCE(!bpf_rcu_lock_held());
	if (!cgroup)
		return -EINVAL;

	if (!bpf_cgrp_storage_trylock())
		return -EBUSY;

	ret = cgroup_storage_delete(cgroup, map);
	bpf_cgrp_storage_unlock();
	return ret;
}

const struct bpf_map_ops cgrp_storage_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = bpf_local_storage_map_alloc_check,
	.map_alloc = cgroup_storage_map_alloc,
	.map_free = cgroup_storage_map_free,
	.map_get_next_key = notsupp_get_next_key,
	.map_lookup_elem = bpf_cgrp_storage_lookup_elem,
	.map_update_elem = bpf_cgrp_storage_update_elem,
	.map_delete_elem = bpf_cgrp_storage_delete_elem,
	.map_check_btf = bpf_local_storage_map_check_btf,
	.map_mem_usage = bpf_local_storage_map_mem_usage,
	.map_btf_id = &bpf_local_storage_map_btf_id[0],
	.map_owner_storage_ptr = cgroup_storage_ptr,
};

const struct bpf_func_proto bpf_cgrp_storage_get_proto = {
	.func		= bpf_cgrp_storage_get,
	.gpl_only	= false,
	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,
	.arg1_type	= ARG_CONST_MAP_PTR,
	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
	.arg2_btf_id	= &bpf_cgroup_btf_id[0],
	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
	.arg4_type	= ARG_ANYTHING,
};

const struct bpf_func_proto bpf_cgrp_storage_delete_proto = {
	.func		= bpf_cgrp_storage_delete,
	.gpl_only	= false,
	.ret_type	= RET_INTEGER,
	.arg1_type	= ARG_CONST_MAP_PTR,
	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
	.arg2_btf_id	= &bpf_cgroup_btf_id[0],
};
Commit	Line	Data
c4bcfb38 YS	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
	4	*/
	5
	6	#include <linux/types.h>
	7	#include <linux/bpf.h>
	8	#include <linux/bpf_local_storage.h>
	9	#include <uapi/linux/btf.h>
	10	#include <linux/btf_ids.h>
	11
	12	DEFINE_BPF_STORAGE_CACHE(cgroup_cache);
	13
	14	static DEFINE_PER_CPU(int, bpf_cgrp_storage_busy);
	15
	16	static void bpf_cgrp_storage_lock(void)
	17	{
	18	migrate_disable();
	19	this_cpu_inc(bpf_cgrp_storage_busy);
	20	}
	21
	22	static void bpf_cgrp_storage_unlock(void)
	23	{
	24	this_cpu_dec(bpf_cgrp_storage_busy);
	25	migrate_enable();
	26	}
	27
	28	static bool bpf_cgrp_storage_trylock(void)
	29	{
	30	migrate_disable();
	31	if (unlikely(this_cpu_inc_return(bpf_cgrp_storage_busy) != 1)) {
	32	this_cpu_dec(bpf_cgrp_storage_busy);
	33	migrate_enable();
	34	return false;
	35	}
	36	return true;
	37	}
	38
	39	static struct bpf_local_storage __rcu *cgroup_storage_ptr(void owner)
	40	{
	41	struct cgroup *cg = owner;
	42
	43	return &cg->bpf_cgrp_storage;
	44	}
	45
	46	void bpf_cgrp_storage_free(struct cgroup *cgroup)
	47	{
	48	struct bpf_local_storage *local_storage;
c4bcfb38 YS	49
	50	rcu_read_lock();
	51	local_storage = rcu_dereference(cgroup->bpf_cgrp_storage);
	52	if (!local_storage) {
	53	rcu_read_unlock();
	54	return;
	55	}
	56
	57	bpf_cgrp_storage_lock();
2ffcb6fc	58	bpf_local_storage_destroy(local_storage);
c4bcfb38 YS	59	bpf_cgrp_storage_unlock();
c4bcfb38 YS	60	rcu_read_unlock();
c4bcfb38 YS	61	}
	62
	63	static struct bpf_local_storage_data *
	64	cgroup_storage_lookup(struct cgroup cgroup, struct bpf_map map, bool cacheit_lockit)
	65	{
	66	struct bpf_local_storage *cgroup_storage;
	67	struct bpf_local_storage_map *smap;
	68
	69	cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage,
	70	bpf_rcu_lock_held());
	71	if (!cgroup_storage)
	72	return NULL;
	73
	74	smap = (struct bpf_local_storage_map *)map;
	75	return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
	76	}
	77
	78	static void bpf_cgrp_storage_lookup_elem(struct bpf_map map, void *key)
	79	{
	80	struct bpf_local_storage_data *sdata;
	81	struct cgroup *cgroup;
	82	int fd;
	83
	84	fd = (int )key;
73d9eb34	85	cgroup = cgroup_v1v2_get_from_fd(fd);
c4bcfb38 YS	86	if (IS_ERR(cgroup))
	87	return ERR_CAST(cgroup);
	88
	89	bpf_cgrp_storage_lock();
	90	sdata = cgroup_storage_lookup(cgroup, map, true);
	91	bpf_cgrp_storage_unlock();
	92	cgroup_put(cgroup);
	93	return sdata ? sdata->data : NULL;
	94	}
	95
d7ba4cc9 JK	96	static long bpf_cgrp_storage_update_elem(struct bpf_map map, void key,
d7ba4cc9 JK	97	void *value, u64 map_flags)
c4bcfb38 YS	98	{
	99	struct bpf_local_storage_data *sdata;
	100	struct cgroup *cgroup;
	101	int fd;
	102
	103	fd = (int )key;
73d9eb34	104	cgroup = cgroup_v1v2_get_from_fd(fd);
c4bcfb38 YS	105	if (IS_ERR(cgroup))
	106	return PTR_ERR(cgroup);
	107
	108	bpf_cgrp_storage_lock();
	109	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
	110	value, map_flags, GFP_ATOMIC);
	111	bpf_cgrp_storage_unlock();
	112	cgroup_put(cgroup);
	113	return PTR_ERR_OR_ZERO(sdata);
	114	}
	115
	116	static int cgroup_storage_delete(struct cgroup cgroup, struct bpf_map map)
	117	{
	118	struct bpf_local_storage_data *sdata;
	119
	120	sdata = cgroup_storage_lookup(cgroup, map, false);
	121	if (!sdata)
	122	return -ENOENT;
	123
a47eabf2	124	bpf_selem_unlink(SELEM(sdata), false);
c4bcfb38 YS	125	return 0;
	126	}
	127
d7ba4cc9	128	static long bpf_cgrp_storage_delete_elem(struct bpf_map map, void key)
c4bcfb38 YS	129	{
	130	struct cgroup *cgroup;
	131	int err, fd;
	132
	133	fd = (int )key;
73d9eb34	134	cgroup = cgroup_v1v2_get_from_fd(fd);
c4bcfb38 YS	135	if (IS_ERR(cgroup))
	136	return PTR_ERR(cgroup);
	137
	138	bpf_cgrp_storage_lock();
	139	err = cgroup_storage_delete(cgroup, map);
	140	bpf_cgrp_storage_unlock();
	141	cgroup_put(cgroup);
	142	return err;
	143	}
	144
	145	static int notsupp_get_next_key(struct bpf_map map, void key, void *next_key)
	146	{
	147	return -ENOTSUPP;
	148	}
	149
	150	static struct bpf_map cgroup_storage_map_alloc(union bpf_attr attr)
	151	{
08a7ce38	152	return bpf_local_storage_map_alloc(attr, &cgroup_cache, true);
c4bcfb38 YS	153	}
	154
	155	static void cgroup_storage_map_free(struct bpf_map *map)
	156	{
	157	bpf_local_storage_map_free(map, &cgroup_cache, NULL);
	158	}
	159
	160	/* gfp_flags is a hidden argument provided by the verifier */
	161	BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map , map, struct cgroup , cgroup,
	162	void *, value, u64, flags, gfp_t, gfp_flags)
	163	{
	164	struct bpf_local_storage_data *sdata;
	165
	166	WARN_ON_ONCE(!bpf_rcu_lock_held());
	167	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
	168	return (unsigned long)NULL;
	169
	170	if (!cgroup)
	171	return (unsigned long)NULL;
	172
	173	if (!bpf_cgrp_storage_trylock())
	174	return (unsigned long)NULL;
	175
	176	sdata = cgroup_storage_lookup(cgroup, map, true);
	177	if (sdata)
	178	goto unlock;
	179
	180	/* only allocate new storage, when the cgroup is refcounted */
	181	if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
	182	(flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
	183	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
	184	value, BPF_NOEXIST, gfp_flags);
	185
	186	unlock:
	187	bpf_cgrp_storage_unlock();
	188	return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
	189	}
	190
	191	BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map , map, struct cgroup , cgroup)
	192	{
	193	int ret;
	194
	195	WARN_ON_ONCE(!bpf_rcu_lock_held());
	196	if (!cgroup)
	197	return -EINVAL;
	198
	199	if (!bpf_cgrp_storage_trylock())
	200	return -EBUSY;
	201
	202	ret = cgroup_storage_delete(cgroup, map);
	203	bpf_cgrp_storage_unlock();
	204	return ret;
	205	}
	206
c4bcfb38 YS	207	const struct bpf_map_ops cgrp_storage_map_ops = {
	208	.map_meta_equal = bpf_map_meta_equal,
	209	.map_alloc_check = bpf_local_storage_map_alloc_check,
	210	.map_alloc = cgroup_storage_map_alloc,
	211	.map_free = cgroup_storage_map_free,
	212	.map_get_next_key = notsupp_get_next_key,
	213	.map_lookup_elem = bpf_cgrp_storage_lookup_elem,
	214	.map_update_elem = bpf_cgrp_storage_update_elem,
	215	.map_delete_elem = bpf_cgrp_storage_delete_elem,
	216	.map_check_btf = bpf_local_storage_map_check_btf,
7490b7f1	217	.map_mem_usage = bpf_local_storage_map_mem_usage,
3144bfa5	218	.map_btf_id = &bpf_local_storage_map_btf_id[0],
c4bcfb38 YS	219	.map_owner_storage_ptr = cgroup_storage_ptr,
	220	};
	221
	222	const struct bpf_func_proto bpf_cgrp_storage_get_proto = {
	223	.func = bpf_cgrp_storage_get,
	224	.gpl_only = false,
	225	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
	226	.arg1_type = ARG_CONST_MAP_PTR,
91571a51	227	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
c4bcfb38 YS	228	.arg2_btf_id = &bpf_cgroup_btf_id[0],
	229	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
	230	.arg4_type = ARG_ANYTHING,
	231	};
	232
	233	const struct bpf_func_proto bpf_cgrp_storage_delete_proto = {
	234	.func = bpf_cgrp_storage_delete,
	235	.gpl_only = false,
	236	.ret_type = RET_INTEGER,
	237	.arg1_type = ARG_CONST_MAP_PTR,
91571a51	238	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
c4bcfb38 YS	239	.arg2_btf_id = &bpf_cgroup_btf_id[0],
c4bcfb38 YS	240	};