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323 lines · 7.8 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2021. Huawei Technologies Co., Ltd
4 */
5#include <linux/kernel.h>
6#include <linux/bpf_verifier.h>
7#include <linux/bpf.h>
8#include <linux/btf.h>
9
10static struct bpf_struct_ops bpf_bpf_dummy_ops;
11
12/* A common type for test_N with return value in bpf_dummy_ops */
13typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
14
15static int dummy_ops_test_ret_function(struct bpf_dummy_ops_state *state, ...)
16{
17 return 0;
18}
19
20struct bpf_dummy_ops_test_args {
21 u64 args[MAX_BPF_FUNC_ARGS];
22 struct bpf_dummy_ops_state state;
23};
24
25static struct btf *bpf_dummy_ops_btf;
26
27static struct bpf_dummy_ops_test_args *
28dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
29{
30 __u32 size_in;
31 struct bpf_dummy_ops_test_args *args;
32 void __user *ctx_in;
33 void __user *u_state;
34
35 size_in = kattr->test.ctx_size_in;
36 if (size_in != sizeof(u64) * nr)
37 return ERR_PTR(-EINVAL);
38
39 args = kzalloc_obj(*args);
40 if (!args)
41 return ERR_PTR(-ENOMEM);
42
43 ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
44 if (copy_from_user(args->args, ctx_in, size_in))
45 goto out;
46
47 /* args[0] is 0 means state argument of test_N will be NULL */
48 u_state = u64_to_user_ptr(args->args[0]);
49 if (u_state && copy_from_user(&args->state, u_state,
50 sizeof(args->state)))
51 goto out;
52
53 return args;
54out:
55 kfree(args);
56 return ERR_PTR(-EFAULT);
57}
58
59static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
60{
61 void __user *u_state;
62
63 u_state = u64_to_user_ptr(args->args[0]);
64 if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
65 return -EFAULT;
66
67 return 0;
68}
69
70static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
71{
72 dummy_ops_test_ret_fn test = (void *)image + cfi_get_offset();
73 struct bpf_dummy_ops_state *state = NULL;
74
75 /* state needs to be NULL if args[0] is 0 */
76 if (args->args[0])
77 state = &args->state;
78 return test(state, args->args[1], args->args[2],
79 args->args[3], args->args[4]);
80}
81
82static const struct bpf_ctx_arg_aux *find_ctx_arg_info(struct bpf_prog_aux *aux, int offset)
83{
84 int i;
85
86 for (i = 0; i < aux->ctx_arg_info_size; i++)
87 if (aux->ctx_arg_info[i].offset == offset)
88 return &aux->ctx_arg_info[i];
89
90 return NULL;
91}
92
93/* There is only one check at the moment:
94 * - zero should not be passed for pointer parameters not marked as nullable.
95 */
96static int check_test_run_args(struct bpf_prog *prog, struct bpf_dummy_ops_test_args *args)
97{
98 const struct btf_type *func_proto = prog->aux->attach_func_proto;
99
100 for (u32 arg_no = 0; arg_no < btf_type_vlen(func_proto) ; ++arg_no) {
101 const struct btf_param *param = &btf_params(func_proto)[arg_no];
102 const struct bpf_ctx_arg_aux *info;
103 const struct btf_type *t;
104 int offset;
105
106 if (args->args[arg_no] != 0)
107 continue;
108
109 /* Program is validated already, so there is no need
110 * to check if t is NULL.
111 */
112 t = btf_type_skip_modifiers(bpf_dummy_ops_btf, param->type, NULL);
113 if (!btf_type_is_ptr(t))
114 continue;
115
116 offset = btf_ctx_arg_offset(bpf_dummy_ops_btf, func_proto, arg_no);
117 info = find_ctx_arg_info(prog->aux, offset);
118 if (info && type_may_be_null(info->reg_type))
119 continue;
120
121 return -EINVAL;
122 }
123
124 return 0;
125}
126
127extern const struct bpf_link_ops bpf_struct_ops_link_lops;
128
129int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
130 union bpf_attr __user *uattr)
131{
132 const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
133 const struct btf_type *func_proto;
134 struct bpf_dummy_ops_test_args *args;
135 struct bpf_tramp_nodes *tnodes = NULL;
136 struct bpf_tramp_link *link = NULL;
137 void *image = NULL;
138 unsigned int op_idx;
139 u32 image_off = 0;
140 int prog_ret;
141 s32 type_id;
142 int err;
143
144 type_id = btf_find_by_name_kind(bpf_dummy_ops_btf,
145 bpf_bpf_dummy_ops.name,
146 BTF_KIND_STRUCT);
147 if (type_id < 0)
148 return -EINVAL;
149 if (prog->aux->attach_btf_id != type_id)
150 return -EOPNOTSUPP;
151
152 func_proto = prog->aux->attach_func_proto;
153 args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
154 if (IS_ERR(args))
155 return PTR_ERR(args);
156
157 err = check_test_run_args(prog, args);
158 if (err)
159 goto out;
160
161 tnodes = kzalloc_objs(*tnodes, BPF_TRAMP_MAX);
162 if (!tnodes) {
163 err = -ENOMEM;
164 goto out;
165 }
166
167 link = kzalloc_obj(*link, GFP_USER);
168 if (!link) {
169 err = -ENOMEM;
170 goto out;
171 }
172 /* prog doesn't take the ownership of the reference from caller */
173 bpf_prog_inc(prog);
174 bpf_tramp_link_init(link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops,
175 prog, prog->expected_attach_type, 0);
176
177 op_idx = prog->expected_attach_type;
178 err = bpf_struct_ops_prepare_trampoline(tnodes, &link->node,
179 &st_ops->func_models[op_idx],
180 &dummy_ops_test_ret_function,
181 &image, &image_off,
182 true);
183 if (err < 0)
184 goto out;
185
186 err = arch_protect_bpf_trampoline(image, PAGE_SIZE);
187 if (err)
188 goto out;
189 prog_ret = dummy_ops_call_op(image, args);
190
191 err = dummy_ops_copy_args(args);
192 if (err)
193 goto out;
194 if (put_user(prog_ret, &uattr->test.retval))
195 err = -EFAULT;
196out:
197 kfree(args);
198 bpf_struct_ops_image_free(image);
199 if (link)
200 bpf_link_put(&link->link);
201 kfree(tnodes);
202 return err;
203}
204
205static int bpf_dummy_init(struct btf *btf)
206{
207 bpf_dummy_ops_btf = btf;
208 return 0;
209}
210
211static bool bpf_dummy_ops_is_valid_access(int off, int size,
212 enum bpf_access_type type,
213 const struct bpf_prog *prog,
214 struct bpf_insn_access_aux *info)
215{
216 return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
217}
218
219static int bpf_dummy_ops_check_member(const struct btf_type *t,
220 const struct btf_member *member,
221 const struct bpf_prog *prog)
222{
223 u32 moff = __btf_member_bit_offset(t, member) / 8;
224
225 switch (moff) {
226 case offsetof(struct bpf_dummy_ops, test_sleepable):
227 break;
228 default:
229 if (prog->sleepable)
230 return -EINVAL;
231 }
232
233 return 0;
234}
235
236static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
237 const struct bpf_reg_state *reg,
238 int off, int size)
239{
240 const struct btf_type *state;
241 const struct btf_type *t;
242 s32 type_id;
243
244 type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state",
245 BTF_KIND_STRUCT);
246 if (type_id < 0)
247 return -EINVAL;
248
249 t = btf_type_by_id(reg->btf, reg->btf_id);
250 state = btf_type_by_id(reg->btf, type_id);
251 if (t != state) {
252 bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
253 return -EACCES;
254 }
255
256 if (off + size > sizeof(struct bpf_dummy_ops_state)) {
257 bpf_log(log, "write access at off %d with size %d\n", off, size);
258 return -EACCES;
259 }
260
261 return NOT_INIT;
262}
263
264static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
265 .is_valid_access = bpf_dummy_ops_is_valid_access,
266 .btf_struct_access = bpf_dummy_ops_btf_struct_access,
267};
268
269static int bpf_dummy_init_member(const struct btf_type *t,
270 const struct btf_member *member,
271 void *kdata, const void *udata)
272{
273 return -EOPNOTSUPP;
274}
275
276static int bpf_dummy_reg(void *kdata, struct bpf_link *link)
277{
278 return -EOPNOTSUPP;
279}
280
281static void bpf_dummy_unreg(void *kdata, struct bpf_link *link)
282{
283}
284
285static int bpf_dummy_ops__test_1(struct bpf_dummy_ops_state *cb__nullable)
286{
287 return 0;
288}
289
290static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
291 char a3, unsigned long a4)
292{
293 return 0;
294}
295
296static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb)
297{
298 return 0;
299}
300
301static struct bpf_dummy_ops __bpf_bpf_dummy_ops = {
302 .test_1 = bpf_dummy_ops__test_1,
303 .test_2 = bpf_dummy_test_2,
304 .test_sleepable = bpf_dummy_test_sleepable,
305};
306
307static struct bpf_struct_ops bpf_bpf_dummy_ops = {
308 .verifier_ops = &bpf_dummy_verifier_ops,
309 .init = bpf_dummy_init,
310 .check_member = bpf_dummy_ops_check_member,
311 .init_member = bpf_dummy_init_member,
312 .reg = bpf_dummy_reg,
313 .unreg = bpf_dummy_unreg,
314 .name = "bpf_dummy_ops",
315 .cfi_stubs = &__bpf_bpf_dummy_ops,
316 .owner = THIS_MODULE,
317};
318
319static int __init bpf_dummy_struct_ops_init(void)
320{
321 return register_bpf_struct_ops(&bpf_bpf_dummy_ops, bpf_dummy_ops);
322}
323late_initcall(bpf_dummy_struct_ops_init);