summaryrefslogtreecommitdiffstats
path: root/kernel/bpf/bpf_inode_storage.c
blob: 6639640523c0bb1afb6a51d9e3e141fc30d8be8a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2019 Facebook
 * Copyright 2020 Google LLC.
 */

#include <linux/rculist.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/bpf.h>
#include <linux/bpf_local_storage.h>
#include <net/sock.h>
#include <uapi/linux/sock_diag.h>
#include <uapi/linux/btf.h>
#include <linux/bpf_lsm.h>
#include <linux/btf_ids.h>
#include <linux/fdtable.h>

DEFINE_BPF_STORAGE_CACHE(inode_cache);

static struct bpf_local_storage __rcu **
inode_storage_ptr(void *owner)
{
	struct inode *inode = owner;
	struct bpf_storage_blob *bsb;

	bsb = bpf_inode(inode);
	if (!bsb)
		return NULL;
	return &bsb->storage;
}

static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode,
							   struct bpf_map *map,
							   bool cacheit_lockit)
{
	struct bpf_local_storage *inode_storage;
	struct bpf_local_storage_map *smap;
	struct bpf_storage_blob *bsb;

	bsb = bpf_inode(inode);
	if (!bsb)
		return NULL;

	inode_storage = rcu_dereference(bsb->storage);
	if (!inode_storage)
		return NULL;

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

void bpf_inode_storage_free(struct inode *inode)
{
	struct bpf_local_storage_elem *selem;
	struct bpf_local_storage *local_storage;
	bool free_inode_storage = false;
	struct bpf_storage_blob *bsb;
	struct hlist_node *n;

	bsb = bpf_inode(inode);
	if (!bsb)
		return;

	rcu_read_lock();

	local_storage = rcu_dereference(bsb->storage);
	if (!local_storage) {
		rcu_read_unlock();
		return;
	}

	/* Netiher the bpf_prog nor the bpf-map's syscall
	 * could be modifying the local_storage->list now.
	 * Thus, no elem can be added-to or deleted-from the
	 * local_storage->list by the bpf_prog or by the bpf-map's syscall.
	 *
	 * It is racing with bpf_local_storage_map_free() alone
	 * when unlinking elem from the local_storage->list and
	 * the map's bucket->list.
	 */
	raw_spin_lock_bh(&local_storage->lock);
	hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
		/* Always unlink from map before unlinking from
		 * local_storage.
		 */
		bpf_selem_unlink_map(selem);
		free_inode_storage = bpf_selem_unlink_storage_nolock(
			local_storage, selem, false);
	}
	raw_spin_unlock_bh(&local_storage->lock);
	rcu_read_unlock();

	/* free_inoode_storage should always be true as long as
	 * local_storage->list was non-empty.
	 */
	if (free_inode_storage)
		kfree_rcu(local_storage, rcu);
}

static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_local_storage_data *sdata;
	struct file *f;
	int fd;

	fd = *(int *)key;
	f = fget_raw(fd);
	if (!f)
		return NULL;

	sdata = inode_storage_lookup(f->f_inode, map, true);
	fput(f);
	return sdata ? sdata->data : NULL;
}

static int bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
					 void *value, u64 map_flags)
{
	struct bpf_local_storage_data *sdata;
	struct file *f;
	int fd;

	fd = *(int *)key;
	f = fget_raw(fd);
	if (!f)
		return -EBADF;
	if (!inode_storage_ptr(f->f_inode)) {
		fput(f);
		return -EBADF;
	}

	sdata = bpf_local_storage_update(f->f_inode,
					 (struct bpf_local_storage_map *)map,
					 value, map_flags);
	fput(f);
	return PTR_ERR_OR_ZERO(sdata);
}

static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
{
	struct bpf_local_storage_data *sdata;

	sdata = inode_storage_lookup(inode, map, false);
	if (!sdata)
		return -ENOENT;

	bpf_selem_unlink(SELEM(sdata));

	return 0;
}

static int bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
{
	struct file *f;
	int fd, err;

	fd = *(int *)key;
	f = fget_raw(fd);
	if (!f)
		return -EBADF;

	err = inode_storage_delete(f->f_inode, map);
	fput(f);
	return err;
}

BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
	   void *, value, u64, flags)
{
	struct bpf_local_storage_data *sdata;

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

	/* explicitly check that the inode_storage_ptr is not
	 * NULL as inode_storage_lookup returns NULL in this case and
	 * bpf_local_storage_update expects the owner to have a
	 * valid storage pointer.
	 */
	if (!inode || !inode_storage_ptr(inode))
		return (unsigned long)NULL;

	sdata = inode_storage_lookup(inode, map, true);
	if (sdata)
		return (unsigned long)sdata->data;

	/* This helper must only called from where the inode is guaranteed
	 * to have a refcount and cannot be freed.
	 */
	if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
		sdata = bpf_local_storage_update(
			inode, (struct bpf_local_storage_map *)map, value,
			BPF_NOEXIST);
		return IS_ERR(sdata) ? (unsigned long)NULL :
					     (unsigned long)sdata->data;
	}

	return (unsigned long)NULL;
}

BPF_CALL_2(bpf_inode_storage_delete,
	   struct bpf_map *, map, struct inode *, inode)
{
	if (!inode)
		return -EINVAL;

	/* This helper must only called from where the inode is guaranteed
	 * to have a refcount and cannot be freed.
	 */
	return inode_storage_delete(inode, map);
}

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

static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
{
	struct bpf_local_storage_map *smap;

	smap = bpf_local_storage_map_alloc(attr);
	if (IS_ERR(smap))
		return ERR_CAST(smap);

	smap->cache_idx = bpf_local_storage_cache_idx_get(&inode_cache);
	return &smap->map;
}

static void inode_storage_map_free(struct bpf_map *map)
{
	struct bpf_local_storage_map *smap;

	smap = (struct bpf_local_storage_map *)map;
	bpf_local_storage_cache_idx_free(&inode_cache, smap->cache_idx);
	bpf_local_storage_map_free(smap);
}

static int inode_storage_map_btf_id;
const struct bpf_map_ops inode_storage_map_ops = {
	.map_meta_equal = bpf_map_meta_equal,
	.map_alloc_check = bpf_local_storage_map_alloc_check,
	.map_alloc = inode_storage_map_alloc,
	.map_free = inode_storage_map_free,
	.map_get_next_key = notsupp_get_next_key,
	.map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
	.map_update_elem = bpf_fd_inode_storage_update_elem,
	.map_delete_elem = bpf_fd_inode_storage_delete_elem,
	.map_check_btf = bpf_local_storage_map_check_btf,
	.map_btf_name = "bpf_local_storage_map",
	.map_btf_id = &inode_storage_map_btf_id,
	.map_owner_storage_ptr = inode_storage_ptr,
};

BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode)

const struct bpf_func_proto bpf_inode_storage_get_proto = {
	.func		= bpf_inode_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_inode_storage_btf_ids[0],
	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
	.arg4_type	= ARG_ANYTHING,
};

const struct bpf_func_proto bpf_inode_storage_delete_proto = {
	.func		= bpf_inode_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_inode_storage_btf_ids[0],
};