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(sizeof(*args), GFP_KERNEL);
 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
 82extern const struct bpf_link_ops bpf_struct_ops_link_lops;
 83
 84int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 85			    union bpf_attr __user *uattr)
 86{
 87	const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
 88	const struct btf_type *func_proto;
 89	struct bpf_dummy_ops_test_args *args;
 90	struct bpf_tramp_links *tlinks;
 91	struct bpf_tramp_link *link = NULL;
 92	void *image = NULL;
 93	unsigned int op_idx;
 94	u32 image_off = 0;
 95	int prog_ret;
 96	s32 type_id;
 97	int err;
 98
 99	type_id = btf_find_by_name_kind(bpf_dummy_ops_btf,
100					bpf_bpf_dummy_ops.name,
101					BTF_KIND_STRUCT);
102	if (type_id < 0)
103		return -EINVAL;
104	if (prog->aux->attach_btf_id != type_id)
105		return -EOPNOTSUPP;
106
107	func_proto = prog->aux->attach_func_proto;
108	args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
109	if (IS_ERR(args))
110		return PTR_ERR(args);
111
112	tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
113	if (!tlinks) {
114		err = -ENOMEM;
115		goto out;
116	}
117
118	link = kzalloc(sizeof(*link), GFP_USER);
119	if (!link) {
120		err = -ENOMEM;
121		goto out;
122	}
123	/* prog doesn't take the ownership of the reference from caller */
124	bpf_prog_inc(prog);
125	bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
126
127	op_idx = prog->expected_attach_type;
128	err = bpf_struct_ops_prepare_trampoline(tlinks, link,
129						&st_ops->func_models[op_idx],
130						&dummy_ops_test_ret_function,
131						&image, &image_off,
132						true);
133	if (err < 0)
134		goto out;
135
136	arch_protect_bpf_trampoline(image, PAGE_SIZE);
137	prog_ret = dummy_ops_call_op(image, args);
138
139	err = dummy_ops_copy_args(args);
140	if (err)
141		goto out;
142	if (put_user(prog_ret, &uattr->test.retval))
143		err = -EFAULT;
144out:
145	kfree(args);
146	bpf_struct_ops_image_free(image);
147	if (link)
148		bpf_link_put(&link->link);
149	kfree(tlinks);
150	return err;
151}
152
153static int bpf_dummy_init(struct btf *btf)
154{
155	bpf_dummy_ops_btf = btf;
156	return 0;
157}
158
159static bool bpf_dummy_ops_is_valid_access(int off, int size,
160					  enum bpf_access_type type,
161					  const struct bpf_prog *prog,
162					  struct bpf_insn_access_aux *info)
163{
164	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
165}
166
167static int bpf_dummy_ops_check_member(const struct btf_type *t,
168				      const struct btf_member *member,
169				      const struct bpf_prog *prog)
170{
171	u32 moff = __btf_member_bit_offset(t, member) / 8;
172
173	switch (moff) {
174	case offsetof(struct bpf_dummy_ops, test_sleepable):
175		break;
176	default:
177		if (prog->sleepable)
178			return -EINVAL;
179	}
180
181	return 0;
182}
183
184static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
185					   const struct bpf_reg_state *reg,
186					   int off, int size)
187{
188	const struct btf_type *state;
189	const struct btf_type *t;
190	s32 type_id;
191
192	type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state",
193					BTF_KIND_STRUCT);
194	if (type_id < 0)
195		return -EINVAL;
196
197	t = btf_type_by_id(reg->btf, reg->btf_id);
198	state = btf_type_by_id(reg->btf, type_id);
199	if (t != state) {
200		bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
201		return -EACCES;
202	}
203
204	if (off + size > sizeof(struct bpf_dummy_ops_state)) {
205		bpf_log(log, "write access at off %d with size %d\n", off, size);
206		return -EACCES;
207	}
208
209	return NOT_INIT;
210}
211
212static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
213	.is_valid_access = bpf_dummy_ops_is_valid_access,
214	.btf_struct_access = bpf_dummy_ops_btf_struct_access,
215};
216
217static int bpf_dummy_init_member(const struct btf_type *t,
218				 const struct btf_member *member,
219				 void *kdata, const void *udata)
220{
221	return -EOPNOTSUPP;
222}
223
224static int bpf_dummy_reg(void *kdata)
225{
226	return -EOPNOTSUPP;
227}
228
229static void bpf_dummy_unreg(void *kdata)
230{
231}
232
233static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb)
234{
235	return 0;
236}
237
238static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
239			    char a3, unsigned long a4)
240{
241	return 0;
242}
243
244static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb)
245{
246	return 0;
247}
248
249static struct bpf_dummy_ops __bpf_bpf_dummy_ops = {
250	.test_1 = bpf_dummy_test_1,
251	.test_2 = bpf_dummy_test_2,
252	.test_sleepable = bpf_dummy_test_sleepable,
253};
254
255static struct bpf_struct_ops bpf_bpf_dummy_ops = {
256	.verifier_ops = &bpf_dummy_verifier_ops,
257	.init = bpf_dummy_init,
258	.check_member = bpf_dummy_ops_check_member,
259	.init_member = bpf_dummy_init_member,
260	.reg = bpf_dummy_reg,
261	.unreg = bpf_dummy_unreg,
262	.name = "bpf_dummy_ops",
263	.cfi_stubs = &__bpf_bpf_dummy_ops,
264	.owner = THIS_MODULE,
265};
266
267static int __init bpf_dummy_struct_ops_init(void)
268{
269	return register_bpf_struct_ops(&bpf_bpf_dummy_ops, bpf_dummy_ops);
270}
271late_initcall(bpf_dummy_struct_ops_init);