bpf_inode_storage.c

  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/rcupdate_trace.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 =
 48		rcu_dereference_check(bsb->storage, bpf_rcu_lock_held());
 49	if (!inode_storage)
 50		return NULL;
 51
 52	smap = (struct bpf_local_storage_map *)map;
 53	return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit);
 54}
 55
 56void bpf_inode_storage_free(struct inode *inode)
 57{
 58	struct bpf_local_storage *local_storage;
 59	struct bpf_storage_blob *bsb;
 60
 61	bsb = bpf_inode(inode);
 62	if (!bsb)
 63		return;
 64
 65	rcu_read_lock_dont_migrate();
 66
 67	local_storage = rcu_dereference(bsb->storage);
 68	if (!local_storage)
 69		goto out;
 70
 71	bpf_local_storage_destroy(local_storage);
 72out:
 73	rcu_read_unlock_migrate();
 74}
 75
 76static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
 77{
 78	struct bpf_local_storage_data *sdata;
 79	CLASS(fd_raw, f)(*(int *)key);
 80
 81	if (fd_empty(f))
 82		return ERR_PTR(-EBADF);
 83
 84	sdata = inode_storage_lookup(file_inode(fd_file(f)), map, true);
 85	return sdata ? sdata->data : NULL;
 86}
 87
 88static long bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
 89					     void *value, u64 map_flags)
 90{
 91	struct bpf_local_storage_data *sdata;
 92	CLASS(fd_raw, f)(*(int *)key);
 93
 94	if (fd_empty(f))
 95		return -EBADF;
 96	if (!inode_storage_ptr(file_inode(fd_file(f))))
 97		return -EBADF;
 98
 99	sdata = bpf_local_storage_update(file_inode(fd_file(f)),
100					 (struct bpf_local_storage_map *)map,
101					 value, map_flags, false, GFP_ATOMIC);
102	return PTR_ERR_OR_ZERO(sdata);
103}
104
105static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
106{
107	struct bpf_local_storage_data *sdata;
108
109	sdata = inode_storage_lookup(inode, map, false);
110	if (!sdata)
111		return -ENOENT;
112
113	bpf_selem_unlink(SELEM(sdata), false);
114
115	return 0;
116}
117
118static long bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
119{
120	CLASS(fd_raw, f)(*(int *)key);
121
122	if (fd_empty(f))
123		return -EBADF;
124	return inode_storage_delete(file_inode(fd_file(f)), map);
125}
126
127/* *gfp_flags* is a hidden argument provided by the verifier */
128BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
129	   void *, value, u64, flags, gfp_t, gfp_flags)
130{
131	struct bpf_local_storage_data *sdata;
132
133	WARN_ON_ONCE(!bpf_rcu_lock_held());
134	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
135		return (unsigned long)NULL;
136
137	/* explicitly check that the inode_storage_ptr is not
138	 * NULL as inode_storage_lookup returns NULL in this case and
139	 * bpf_local_storage_update expects the owner to have a
140	 * valid storage pointer.
141	 */
142	if (!inode || !inode_storage_ptr(inode))
143		return (unsigned long)NULL;
144
145	sdata = inode_storage_lookup(inode, map, true);
146	if (sdata)
147		return (unsigned long)sdata->data;
148
149	/* This helper must only called from where the inode is guaranteed
150	 * to have a refcount and cannot be freed.
151	 */
152	if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
153		sdata = bpf_local_storage_update(
154			inode, (struct bpf_local_storage_map *)map, value,
155			BPF_NOEXIST, false, gfp_flags);
156		return IS_ERR(sdata) ? (unsigned long)NULL :
157					     (unsigned long)sdata->data;
158	}
159
160	return (unsigned long)NULL;
161}
162
163BPF_CALL_2(bpf_inode_storage_delete,
164	   struct bpf_map *, map, struct inode *, inode)
165{
166	WARN_ON_ONCE(!bpf_rcu_lock_held());
167	if (!inode)
168		return -EINVAL;
169
170	/* This helper must only called from where the inode is guaranteed
171	 * to have a refcount and cannot be freed.
172	 */
173	return inode_storage_delete(inode, map);
174}
175
176static int notsupp_get_next_key(struct bpf_map *map, void *key,
177				void *next_key)
178{
179	return -ENOTSUPP;
180}
181
182static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
183{
184	return bpf_local_storage_map_alloc(attr, &inode_cache, false);
185}
186
187static void inode_storage_map_free(struct bpf_map *map)
188{
189	bpf_local_storage_map_free(map, &inode_cache, NULL);
190}
191
192const struct bpf_map_ops inode_storage_map_ops = {
193	.map_meta_equal = bpf_map_meta_equal,
194	.map_alloc_check = bpf_local_storage_map_alloc_check,
195	.map_alloc = inode_storage_map_alloc,
196	.map_free = inode_storage_map_free,
197	.map_get_next_key = notsupp_get_next_key,
198	.map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
199	.map_update_elem = bpf_fd_inode_storage_update_elem,
200	.map_delete_elem = bpf_fd_inode_storage_delete_elem,
201	.map_check_btf = bpf_local_storage_map_check_btf,
202	.map_mem_usage = bpf_local_storage_map_mem_usage,
203	.map_btf_id = &bpf_local_storage_map_btf_id[0],
204	.map_owner_storage_ptr = inode_storage_ptr,
205};
206
207BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode)
208
209const struct bpf_func_proto bpf_inode_storage_get_proto = {
210	.func		= bpf_inode_storage_get,
211	.gpl_only	= false,
212	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,
213	.arg1_type	= ARG_CONST_MAP_PTR,
214	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
215	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
216	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
217	.arg4_type	= ARG_ANYTHING,
218};
219
220const struct bpf_func_proto bpf_inode_storage_delete_proto = {
221	.func		= bpf_inode_storage_delete,
222	.gpl_only	= false,
223	.ret_type	= RET_INTEGER,
224	.arg1_type	= ARG_CONST_MAP_PTR,
225	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
226	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
227};