1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2019 Facebook
  4 * Copyright 2020 Google LLC.
  5 */
  6
  7#include <linux/rculist.h>
  8#include <linux/list.h>
  9#include <linux/hash.h>
 10#include <linux/types.h>
 11#include <linux/spinlock.h>
 12#include <linux/bpf.h>
 13#include <linux/bpf_local_storage.h>
 14#include <net/sock.h>
 15#include <uapi/linux/sock_diag.h>
 16#include <uapi/linux/btf.h>
 17#include <linux/bpf_lsm.h>
 18#include <linux/btf_ids.h>
 19#include <linux/fdtable.h>
 20
 21DEFINE_BPF_STORAGE_CACHE(inode_cache);
 22
 23static struct bpf_local_storage __rcu **
 24inode_storage_ptr(void *owner)
 25{
 26	struct inode *inode = owner;
 27	struct bpf_storage_blob *bsb;
 28
 29	bsb = bpf_inode(inode);
 30	if (!bsb)
 31		return NULL;
 32	return &bsb->storage;
 33}
 34
 35static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode,
 36							   struct bpf_map *map,
 37							   bool cacheit_lockit)
 38{
 39	struct bpf_local_storage *inode_storage;
 40	struct bpf_local_storage_map *smap;
 41	struct bpf_storage_blob *bsb;
 42
 43	bsb = bpf_inode(inode);
 44	if (!bsb)
 45		return NULL;
 46
 47	inode_storage = rcu_dereference(bsb->storage);
 48	if (!inode_storage)
 49		return NULL;
 50
 51	smap = (struct bpf_local_storage_map *)map;
 52	return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit);
 53}
 54
 55void bpf_inode_storage_free(struct inode *inode)
 56{
 57	struct bpf_local_storage_elem *selem;
 58	struct bpf_local_storage *local_storage;
 59	bool free_inode_storage = false;
 60	struct bpf_storage_blob *bsb;
 61	struct hlist_node *n;
 62
 63	bsb = bpf_inode(inode);
 64	if (!bsb)
 65		return;
 66
 67	rcu_read_lock();
 68
 69	local_storage = rcu_dereference(bsb->storage);
 70	if (!local_storage) {
 71		rcu_read_unlock();
 72		return;
 73	}
 74
 75	/* Neither the bpf_prog nor the bpf-map's syscall
 76	 * could be modifying the local_storage->list now.
 77	 * Thus, no elem can be added-to or deleted-from the
 78	 * local_storage->list by the bpf_prog or by the bpf-map's syscall.
 79	 *
 80	 * It is racing with bpf_local_storage_map_free() alone
 81	 * when unlinking elem from the local_storage->list and
 82	 * the map's bucket->list.
 83	 */
 84	raw_spin_lock_bh(&local_storage->lock);
 85	hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
 86		/* Always unlink from map before unlinking from
 87		 * local_storage.
 88		 */
 89		bpf_selem_unlink_map(selem);
 90		free_inode_storage = bpf_selem_unlink_storage_nolock(
 91			local_storage, selem, false);
 92	}
 93	raw_spin_unlock_bh(&local_storage->lock);
 94	rcu_read_unlock();
 95
 96	/* free_inoode_storage should always be true as long as
 97	 * local_storage->list was non-empty.
 98	 */
 99	if (free_inode_storage)
100		kfree_rcu(local_storage, rcu);
101}
102
103static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
104{
105	struct bpf_local_storage_data *sdata;
106	struct file *f;
107	int fd;
108
109	fd = *(int *)key;
110	f = fget_raw(fd);
111	if (!f)
112		return ERR_PTR(-EBADF);
113
114	sdata = inode_storage_lookup(f->f_inode, map, true);
115	fput(f);
116	return sdata ? sdata->data : NULL;
117}
118
119static int bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
120					 void *value, u64 map_flags)
121{
122	struct bpf_local_storage_data *sdata;
123	struct file *f;
124	int fd;
125
126	fd = *(int *)key;
127	f = fget_raw(fd);
128	if (!f)
129		return -EBADF;
130	if (!inode_storage_ptr(f->f_inode)) {
131		fput(f);
132		return -EBADF;
133	}
134
135	sdata = bpf_local_storage_update(f->f_inode,
136					 (struct bpf_local_storage_map *)map,
137					 value, map_flags);
138	fput(f);
139	return PTR_ERR_OR_ZERO(sdata);
140}
141
142static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
143{
144	struct bpf_local_storage_data *sdata;
145
146	sdata = inode_storage_lookup(inode, map, false);
147	if (!sdata)
148		return -ENOENT;
149
150	bpf_selem_unlink(SELEM(sdata));
151
152	return 0;
153}
154
155static int bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
156{
157	struct file *f;
158	int fd, err;
159
160	fd = *(int *)key;
161	f = fget_raw(fd);
162	if (!f)
163		return -EBADF;
164
165	err = inode_storage_delete(f->f_inode, map);
166	fput(f);
167	return err;
168}
169
170BPF_CALL_4(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
171	   void *, value, u64, flags)
172{
173	struct bpf_local_storage_data *sdata;
174
175	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
176		return (unsigned long)NULL;
177
178	/* explicitly check that the inode_storage_ptr is not
179	 * NULL as inode_storage_lookup returns NULL in this case and
180	 * bpf_local_storage_update expects the owner to have a
181	 * valid storage pointer.
182	 */
183	if (!inode || !inode_storage_ptr(inode))
184		return (unsigned long)NULL;
185
186	sdata = inode_storage_lookup(inode, map, true);
187	if (sdata)
188		return (unsigned long)sdata->data;
189
190	/* This helper must only called from where the inode is guaranteed
191	 * to have a refcount and cannot be freed.
192	 */
193	if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
194		sdata = bpf_local_storage_update(
195			inode, (struct bpf_local_storage_map *)map, value,
196			BPF_NOEXIST);
197		return IS_ERR(sdata) ? (unsigned long)NULL :
198					     (unsigned long)sdata->data;
199	}
200
201	return (unsigned long)NULL;
202}
203
204BPF_CALL_2(bpf_inode_storage_delete,
205	   struct bpf_map *, map, struct inode *, inode)
206{
207	if (!inode)
208		return -EINVAL;
209
210	/* This helper must only called from where the inode is guaranteed
211	 * to have a refcount and cannot be freed.
212	 */
213	return inode_storage_delete(inode, map);
214}
215
216static int notsupp_get_next_key(struct bpf_map *map, void *key,
217				void *next_key)
218{
219	return -ENOTSUPP;
220}
221
222static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
223{
224	struct bpf_local_storage_map *smap;
225
226	smap = bpf_local_storage_map_alloc(attr);
227	if (IS_ERR(smap))
228		return ERR_CAST(smap);
229
230	smap->cache_idx = bpf_local_storage_cache_idx_get(&inode_cache);
231	return &smap->map;
232}
233
234static void inode_storage_map_free(struct bpf_map *map)
235{
236	struct bpf_local_storage_map *smap;
237
238	smap = (struct bpf_local_storage_map *)map;
239	bpf_local_storage_cache_idx_free(&inode_cache, smap->cache_idx);
240	bpf_local_storage_map_free(smap, NULL);
241}
242
243static int inode_storage_map_btf_id;
244const struct bpf_map_ops inode_storage_map_ops = {
245	.map_meta_equal = bpf_map_meta_equal,
246	.map_alloc_check = bpf_local_storage_map_alloc_check,
247	.map_alloc = inode_storage_map_alloc,
248	.map_free = inode_storage_map_free,
249	.map_get_next_key = notsupp_get_next_key,
250	.map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
251	.map_update_elem = bpf_fd_inode_storage_update_elem,
252	.map_delete_elem = bpf_fd_inode_storage_delete_elem,
253	.map_check_btf = bpf_local_storage_map_check_btf,
254	.map_btf_name = "bpf_local_storage_map",
255	.map_btf_id = &inode_storage_map_btf_id,
256	.map_owner_storage_ptr = inode_storage_ptr,
257};
258
259BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode)
260
261const struct bpf_func_proto bpf_inode_storage_get_proto = {
262	.func		= bpf_inode_storage_get,
263	.gpl_only	= false,
264	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,
265	.arg1_type	= ARG_CONST_MAP_PTR,
266	.arg2_type	= ARG_PTR_TO_BTF_ID,
267	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
268	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
269	.arg4_type	= ARG_ANYTHING,
270};
271
272const struct bpf_func_proto bpf_inode_storage_delete_proto = {
273	.func		= bpf_inode_storage_delete,
274	.gpl_only	= false,
275	.ret_type	= RET_INTEGER,
276	.arg1_type	= ARG_CONST_MAP_PTR,
277	.arg2_type	= ARG_PTR_TO_BTF_ID,
278	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
279};