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 #include <linux/rcupdate_trace.h>
21
22 DEFINE_BPF_STORAGE_CACHE(inode_cache);
23
24 static struct bpf_local_storage __rcu **
25 inode_storage_ptr(void *owner)
26 {
27 struct inode *inode = owner;
28 struct bpf_storage_blob *bsb;
29
30 bsb = bpf_inode(inode);
31 if (!bsb)
32 return NULL;
33 return &bsb->storage;
34 }
35
36 static struct bpf_local_storage_data *inode_storage_lookup(struct inode *inode,
37 struct bpf_map *map,
38 bool cacheit_lockit)
39 {
40 struct bpf_local_storage *inode_storage;
41 struct bpf_local_storage_map *smap;
42 struct bpf_storage_blob *bsb;
43
44 bsb = bpf_inode(inode);
45 if (!bsb)
46 return NULL;
47
48 inode_storage =
49 rcu_dereference_check(bsb->storage, bpf_rcu_lock_held());
50 if (!inode_storage)
51 return NULL;
52
53 smap = (struct bpf_local_storage_map *)map;
54 return bpf_local_storage_lookup(inode_storage, smap, cacheit_lockit);
55 }
56
57 void bpf_inode_storage_free(struct inode *inode)
58 {
59 struct bpf_local_storage *local_storage;
60 struct bpf_storage_blob *bsb;
61
62 bsb = bpf_inode(inode);
63 if (!bsb)
64 return;
65
66 rcu_read_lock();
67
68 local_storage = rcu_dereference(bsb->storage);
69 if (!local_storage) {
70 rcu_read_unlock();
71 return;
72 }
73
74 bpf_local_storage_destroy(local_storage);
75 rcu_read_unlock();
76 }
77
78 static void *bpf_fd_inode_storage_lookup_elem(struct bpf_map *map, void *key)
79 {
80 struct bpf_local_storage_data *sdata;
81 struct fd f = fdget_raw(*(int *)key);
82
83 if (!f.file)
84 return ERR_PTR(-EBADF);
85
86 sdata = inode_storage_lookup(file_inode(f.file), map, true);
87 fdput(f);
88 return sdata ? sdata->data : NULL;
89 }
90
91 static long bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
92 void *value, u64 map_flags)
93 {
94 struct bpf_local_storage_data *sdata;
95 struct fd f = fdget_raw(*(int *)key);
96
97 if (!f.file)
98 return -EBADF;
99 if (!inode_storage_ptr(file_inode(f.file))) {
100 fdput(f);
101 return -EBADF;
102 }
103
104 sdata = bpf_local_storage_update(file_inode(f.file),
105 (struct bpf_local_storage_map *)map,
106 value, map_flags, GFP_ATOMIC);
107 fdput(f);
108 return PTR_ERR_OR_ZERO(sdata);
109 }
110
111 static int inode_storage_delete(struct inode *inode, struct bpf_map *map)
112 {
113 struct bpf_local_storage_data *sdata;
114
115 sdata = inode_storage_lookup(inode, map, false);
116 if (!sdata)
117 return -ENOENT;
118
119 bpf_selem_unlink(SELEM(sdata), false);
120
121 return 0;
122 }
123
124 static long bpf_fd_inode_storage_delete_elem(struct bpf_map *map, void *key)
125 {
126 struct fd f = fdget_raw(*(int *)key);
127 int err;
128
129 if (!f.file)
130 return -EBADF;
131
132 err = inode_storage_delete(file_inode(f.file), map);
133 fdput(f);
134 return err;
135 }
136
137 /* *gfp_flags* is a hidden argument provided by the verifier */
138 BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
139 void *, value, u64, flags, gfp_t, gfp_flags)
140 {
141 struct bpf_local_storage_data *sdata;
142
143 WARN_ON_ONCE(!bpf_rcu_lock_held());
144 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
145 return (unsigned long)NULL;
146
147 /* explicitly check that the inode_storage_ptr is not
148 * NULL as inode_storage_lookup returns NULL in this case and
149 * bpf_local_storage_update expects the owner to have a
150 * valid storage pointer.
151 */
152 if (!inode || !inode_storage_ptr(inode))
153 return (unsigned long)NULL;
154
155 sdata = inode_storage_lookup(inode, map, true);
156 if (sdata)
157 return (unsigned long)sdata->data;
158
159 /* This helper must only called from where the inode is guaranteed
160 * to have a refcount and cannot be freed.
161 */
162 if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
163 sdata = bpf_local_storage_update(
164 inode, (struct bpf_local_storage_map *)map, value,
165 BPF_NOEXIST, gfp_flags);
166 return IS_ERR(sdata) ? (unsigned long)NULL :
167 (unsigned long)sdata->data;
168 }
169
170 return (unsigned long)NULL;
171 }
172
173 BPF_CALL_2(bpf_inode_storage_delete,
174 struct bpf_map *, map, struct inode *, inode)
175 {
176 WARN_ON_ONCE(!bpf_rcu_lock_held());
177 if (!inode)
178 return -EINVAL;
179
180 /* This helper must only called from where the inode is guaranteed
181 * to have a refcount and cannot be freed.
182 */
183 return inode_storage_delete(inode, map);
184 }
185
186 static int notsupp_get_next_key(struct bpf_map *map, void *key,
187 void *next_key)
188 {
189 return -ENOTSUPP;
190 }
191
192 static struct bpf_map *inode_storage_map_alloc(union bpf_attr *attr)
193 {
194 return bpf_local_storage_map_alloc(attr, &inode_cache, false);
195 }
196
197 static void inode_storage_map_free(struct bpf_map *map)
198 {
199 bpf_local_storage_map_free(map, &inode_cache, NULL);
200 }
201
202 const struct bpf_map_ops inode_storage_map_ops = {
203 .map_meta_equal = bpf_map_meta_equal,
204 .map_alloc_check = bpf_local_storage_map_alloc_check,
205 .map_alloc = inode_storage_map_alloc,
206 .map_free = inode_storage_map_free,
207 .map_get_next_key = notsupp_get_next_key,
208 .map_lookup_elem = bpf_fd_inode_storage_lookup_elem,
209 .map_update_elem = bpf_fd_inode_storage_update_elem,
210 .map_delete_elem = bpf_fd_inode_storage_delete_elem,
211 .map_check_btf = bpf_local_storage_map_check_btf,
212 .map_mem_usage = bpf_local_storage_map_mem_usage,
213 .map_btf_id = &bpf_local_storage_map_btf_id[0],
214 .map_owner_storage_ptr = inode_storage_ptr,
215 };
216
217 BTF_ID_LIST_SINGLE(bpf_inode_storage_btf_ids, struct, inode)
218
219 const struct bpf_func_proto bpf_inode_storage_get_proto = {
220 .func = bpf_inode_storage_get,
221 .gpl_only = false,
222 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
223 .arg1_type = ARG_CONST_MAP_PTR,
224 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
225 .arg2_btf_id = &bpf_inode_storage_btf_ids[0],
226 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
227 .arg4_type = ARG_ANYTHING,
228 };
229
230 const struct bpf_func_proto bpf_inode_storage_delete_proto = {
231 .func = bpf_inode_storage_delete,
232 .gpl_only = false,
233 .ret_type = RET_INTEGER,
234 .arg1_type = ARG_CONST_MAP_PTR,
235 .arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,
236 .arg2_btf_id = &bpf_inode_storage_btf_ids[0],
237 };
238
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