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