[linux-block.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;
	bool free_cgroup_storage = false;
	unsigned long flags;

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

	bpf_cgrp_storage_lock();
	raw_spin_lock_irqsave(&local_storage->lock, flags);
	free_cgroup_storage = bpf_local_storage_unlink_nolock(local_storage);
	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
	bpf_cgrp_storage_unlock();
	rcu_read_unlock();

	if (free_cgroup_storage)
		kfree_rcu(local_storage, rcu);
}

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_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 int 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_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), true);
	return 0;
}

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

	fd = *(int *)key;
	cgroup = cgroup_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);
}

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_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,
	.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,
	.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;
	49	bool free_cgroup_storage = false;
	50	unsigned long flags;
	51
	52	rcu_read_lock();
	53	local_storage = rcu_dereference(cgroup->bpf_cgrp_storage);
	54	if (!local_storage) {
	55	rcu_read_unlock();
	56	return;
	57	}
	58
	59	bpf_cgrp_storage_lock();
	60	raw_spin_lock_irqsave(&local_storage->lock, flags);
	61	free_cgroup_storage = bpf_local_storage_unlink_nolock(local_storage);
	62	raw_spin_unlock_irqrestore(&local_storage->lock, flags);
	63	bpf_cgrp_storage_unlock();
	64	rcu_read_unlock();
65
66	if (free_cgroup_storage)
67	kfree_rcu(local_storage, rcu);
68	}
69
70	static struct bpf_local_storage_data *
71	cgroup_storage_lookup(struct cgroup cgroup, struct bpf_map map, bool cacheit_lockit)
72	{
73	struct bpf_local_storage *cgroup_storage;
74	struct bpf_local_storage_map *smap;
75
76	cgroup_storage = rcu_dereference_check(cgroup->bpf_cgrp_storage,
77	bpf_rcu_lock_held());
78	if (!cgroup_storage)
79	return NULL;
80
81	smap = (struct bpf_local_storage_map *)map;
82	return bpf_local_storage_lookup(cgroup_storage, smap, cacheit_lockit);
83	}
84
85	static void bpf_cgrp_storage_lookup_elem(struct bpf_map map, void *key)
86	{
87	struct bpf_local_storage_data *sdata;
88	struct cgroup *cgroup;
89	int fd;
90
91	fd = (int )key;
92	cgroup = cgroup_get_from_fd(fd);
93	if (IS_ERR(cgroup))
94	return ERR_CAST(cgroup);
95
96	bpf_cgrp_storage_lock();
97	sdata = cgroup_storage_lookup(cgroup, map, true);
98	bpf_cgrp_storage_unlock();
99	cgroup_put(cgroup);
100	return sdata ? sdata->data : NULL;
101	}
102
103	static int bpf_cgrp_storage_update_elem(struct bpf_map map, void key,
104	void *value, u64 map_flags)
105	{
106	struct bpf_local_storage_data *sdata;
107	struct cgroup *cgroup;
108	int fd;
109
110	fd = (int )key;
111	cgroup = cgroup_get_from_fd(fd);
112	if (IS_ERR(cgroup))
113	return PTR_ERR(cgroup);
114
115	bpf_cgrp_storage_lock();
116	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
117	value, map_flags, GFP_ATOMIC);
118	bpf_cgrp_storage_unlock();
119	cgroup_put(cgroup);
120	return PTR_ERR_OR_ZERO(sdata);
121	}
122
123	static int cgroup_storage_delete(struct cgroup cgroup, struct bpf_map map)
124	{
125	struct bpf_local_storage_data *sdata;
126
127	sdata = cgroup_storage_lookup(cgroup, map, false);
128	if (!sdata)
129	return -ENOENT;
130
131	bpf_selem_unlink(SELEM(sdata), true);
132	return 0;
133	}
134
135	static int bpf_cgrp_storage_delete_elem(struct bpf_map map, void key)
136	{
137	struct cgroup *cgroup;
138	int err, fd;
139
140	fd = (int )key;
141	cgroup = cgroup_get_from_fd(fd);
142	if (IS_ERR(cgroup))
143	return PTR_ERR(cgroup);
144
145	bpf_cgrp_storage_lock();
146	err = cgroup_storage_delete(cgroup, map);
147	bpf_cgrp_storage_unlock();
148	cgroup_put(cgroup);
149	return err;
150	}
151
152	static int notsupp_get_next_key(struct bpf_map map, void key, void *next_key)
153	{
154	return -ENOTSUPP;
155	}
156
157	static struct bpf_map cgroup_storage_map_alloc(union bpf_attr attr)
158	{
159	return bpf_local_storage_map_alloc(attr, &cgroup_cache);
160	}
161
162	static void cgroup_storage_map_free(struct bpf_map *map)
163	{
164	bpf_local_storage_map_free(map, &cgroup_cache, NULL);
165	}
166
167	/* gfp_flags is a hidden argument provided by the verifier */
168	BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map , map, struct cgroup , cgroup,
169	void *, value, u64, flags, gfp_t, gfp_flags)
170	{
171	struct bpf_local_storage_data *sdata;
172
173	WARN_ON_ONCE(!bpf_rcu_lock_held());
174	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
175	return (unsigned long)NULL;
176
177	if (!cgroup)
178	return (unsigned long)NULL;
179
180	if (!bpf_cgrp_storage_trylock())
181	return (unsigned long)NULL;
182
183	sdata = cgroup_storage_lookup(cgroup, map, true);
184	if (sdata)
185	goto unlock;
186
187	/* only allocate new storage, when the cgroup is refcounted */
188	if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
189	(flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
190	sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
191	value, BPF_NOEXIST, gfp_flags);
192
193	unlock:
194	bpf_cgrp_storage_unlock();
195	return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data;
196	}
197
198	BPF_CALL_2(bpf_cgrp_storage_delete, struct bpf_map , map, struct cgroup , cgroup)
199	{
200	int ret;
201
202	WARN_ON_ONCE(!bpf_rcu_lock_held());
203	if (!cgroup)
204	return -EINVAL;
205
206	if (!bpf_cgrp_storage_trylock())
207	return -EBUSY;
208
209	ret = cgroup_storage_delete(cgroup, map);
210	bpf_cgrp_storage_unlock();
211	return ret;
212	}
213
c4bcfb38 YS	214	const struct bpf_map_ops cgrp_storage_map_ops = {
	215	.map_meta_equal = bpf_map_meta_equal,
	216	.map_alloc_check = bpf_local_storage_map_alloc_check,
	217	.map_alloc = cgroup_storage_map_alloc,
	218	.map_free = cgroup_storage_map_free,
	219	.map_get_next_key = notsupp_get_next_key,
	220	.map_lookup_elem = bpf_cgrp_storage_lookup_elem,
	221	.map_update_elem = bpf_cgrp_storage_update_elem,
	222	.map_delete_elem = bpf_cgrp_storage_delete_elem,
	223	.map_check_btf = bpf_local_storage_map_check_btf,
3144bfa5	224	.map_btf_id = &bpf_local_storage_map_btf_id[0],
c4bcfb38 YS	225	.map_owner_storage_ptr = cgroup_storage_ptr,
	226	};
	227
	228	const struct bpf_func_proto bpf_cgrp_storage_get_proto = {
	229	.func = bpf_cgrp_storage_get,
	230	.gpl_only = false,
	231	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
	232	.arg1_type = ARG_CONST_MAP_PTR,
	233	.arg2_type = ARG_PTR_TO_BTF_ID,
	234	.arg2_btf_id = &bpf_cgroup_btf_id[0],
	235	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
	236	.arg4_type = ARG_ANYTHING,
	237	};
	238
	239	const struct bpf_func_proto bpf_cgrp_storage_delete_proto = {
	240	.func = bpf_cgrp_storage_delete,
	241	.gpl_only = false,
	242	.ret_type = RET_INTEGER,
	243	.arg1_type = ARG_CONST_MAP_PTR,
	244	.arg2_type = ARG_PTR_TO_BTF_ID,
	245	.arg2_btf_id = &bpf_cgroup_btf_id[0],
	246	};