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();
 66
 67	local_storage = rcu_dereference(bsb->storage);
 68	if (!local_storage) {
 69		rcu_read_unlock();
 70		return;
 71	}
 72
 73	bpf_local_storage_destroy(local_storage);
 74	rcu_read_unlock();
 75}
 76
 77static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
 78{
 79	struct bpf_local_storage_data *sdata;
 80	CLASS(fd_raw, f)(*(int *)key);
 81
 82	if (fd_empty(f))
 83		return ERR_PTR(-EBADF);
 84
 85	sdata = inode_storage_lookup(file_inode(fd_file(f)), map, true);
 86	return sdata ? sdata->data : NULL;
 87}
 88
 89static long bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
 90					     void *value, u64 map_flags)
 91{
 92	struct bpf_local_storage_data *sdata;
 93	CLASS(fd_raw, f)(*(int *)key);
 94
 95	if (fd_empty(f))
 96		return -EBADF;
 97	if (!inode_storage_ptr(file_inode(fd_file(f))))
 98		return -EBADF;
 99
100	sdata = bpf_local_storage_update(file_inode(fd_file(f)),
101					 (struct bpf_local_storage_map *)map,
102					 value, map_flags, false, GFP_ATOMIC);
103	return PTR_ERR_OR_ZERO(sdata);
104}
105
106static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
107{
108	struct bpf_local_storage_data *sdata;
109
110	sdata = inode_storage_lookup(inode, map, false);
111	if (!sdata)
112		return -ENOENT;
113
114	bpf_selem_unlink(SELEM(sdata), false);
115
116	return 0;
117}
118
119static long bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
120{
121	CLASS(fd_raw, f)(*(int *)key);
122
123	if (fd_empty(f))
124		return -EBADF;
125	return inode_storage_delete(file_inode(fd_file(f)), map);
126}
127
128/* *gfp_flags* is a hidden argument provided by the verifier */
129BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
130	   void *, value, u64, flags, gfp_t, gfp_flags)
131{
132	struct bpf_local_storage_data *sdata;
133
134	WARN_ON_ONCE(!bpf_rcu_lock_held());
135	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
136		return (unsigned long)NULL;
137
138	/* explicitly check that the inode_storage_ptr is not
139	 * NULL as inode_storage_lookup returns NULL in this case and
140	 * bpf_local_storage_update expects the owner to have a
141	 * valid storage pointer.
142	 */
143	if (!inode || !inode_storage_ptr(inode))
144		return (unsigned long)NULL;
145
146	sdata = inode_storage_lookup(inode, map, true);
147	if (sdata)
148		return (unsigned long)sdata->data;
149
150	/* This helper must only called from where the inode is guaranteed
151	 * to have a refcount and cannot be freed.
152	 */
153	if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
154		sdata = bpf_local_storage_update(
155			inode, (struct bpf_local_storage_map *)map, value,
156			BPF_NOEXIST, false, gfp_flags);
157		return IS_ERR(sdata) ? (unsigned long)NULL :
158					     (unsigned long)sdata->data;
159	}
160
161	return (unsigned long)NULL;
162}
163
164BPF_CALL_2(bpf_inode_storage_delete,
165	   struct bpf_map *, map, struct inode *, inode)
166{
167	WARN_ON_ONCE(!bpf_rcu_lock_held());
168	if (!inode)
169		return -EINVAL;
170
171	/* This helper must only called from where the inode is guaranteed
172	 * to have a refcount and cannot be freed.
173	 */
174	return inode_storage_delete(inode, map);
175}
176
177static int notsupp_get_next_key(struct bpf_map *map, void *key,
178				void *next_key)
179{
180	return -ENOTSUPP;
181}
182
183static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
184{
185	return bpf_local_storage_map_alloc(attr, &inode_cache, false);
186}
187
188static void inode_storage_map_free(struct bpf_map *map)
189{
190	bpf_local_storage_map_free(map, &inode_cache, NULL);
191}
192
193const struct bpf_map_ops inode_storage_map_ops = {
194	.map_meta_equal = bpf_map_meta_equal,
195	.map_alloc_check = bpf_local_storage_map_alloc_check,
196	.map_alloc = inode_storage_map_alloc,
197	.map_free = inode_storage_map_free,
198	.map_get_next_key = notsupp_get_next_key,
199	.map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
200	.map_update_elem = bpf_fd_inode_storage_update_elem,
201	.map_delete_elem = bpf_fd_inode_storage_delete_elem,
202	.map_check_btf = bpf_local_storage_map_check_btf,
203	.map_mem_usage = bpf_local_storage_map_mem_usage,
204	.map_btf_id = &bpf_local_storage_map_btf_id[0],
205	.map_owner_storage_ptr = inode_storage_ptr,
206};
207
208BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode)
209
210const struct bpf_func_proto bpf_inode_storage_get_proto = {
211	.func		= bpf_inode_storage_get,
212	.gpl_only	= false,
213	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,
214	.arg1_type	= ARG_CONST_MAP_PTR,
215	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
216	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
217	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,
218	.arg4_type	= ARG_ANYTHING,
219};
220
221const struct bpf_func_proto bpf_inode_storage_delete_proto = {
222	.func		= bpf_inode_storage_delete,
223	.gpl_only	= false,
224	.ret_type	= RET_INTEGER,
225	.arg1_type	= ARG_CONST_MAP_PTR,
226	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,
227	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],
228};