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
 10extern 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
 15struct bpf_dummy_ops_test_args {
 16	u64 args[MAX_BPF_FUNC_ARGS];
 17	struct bpf_dummy_ops_state state;
 18};
 19
 20static struct bpf_dummy_ops_test_args *
 21dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
 22{
 23	__u32 size_in;
 24	struct bpf_dummy_ops_test_args *args;
 25	void __user *ctx_in;
 26	void __user *u_state;
 27
 28	size_in = kattr->test.ctx_size_in;
 29	if (size_in != sizeof(u64) * nr)
 30		return ERR_PTR(-EINVAL);
 31
 32	args = kzalloc(sizeof(*args), GFP_KERNEL);
 33	if (!args)
 34		return ERR_PTR(-ENOMEM);
 35
 36	ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
 37	if (copy_from_user(args->args, ctx_in, size_in))
 38		goto out;
 39
 40	/* args[0] is 0 means state argument of test_N will be NULL */
 41	u_state = u64_to_user_ptr(args->args[0]);
 42	if (u_state && copy_from_user(&args->state, u_state,
 43				      sizeof(args->state)))
 44		goto out;
 45
 46	return args;
 47out:
 48	kfree(args);
 49	return ERR_PTR(-EFAULT);
 50}
 51
 52static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
 53{
 54	void __user *u_state;
 55
 56	u_state = u64_to_user_ptr(args->args[0]);
 57	if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
 58		return -EFAULT;
 59
 60	return 0;
 61}
 62
 63static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
 64{
 65	dummy_ops_test_ret_fn test = (void *)image;
 66	struct bpf_dummy_ops_state *state = NULL;
 67
 68	/* state needs to be NULL if args[0] is 0 */
 69	if (args->args[0])
 70		state = &args->state;
 71	return test(state, args->args[1], args->args[2],
 72		    args->args[3], args->args[4]);
 73}
 74
 75extern const struct bpf_link_ops bpf_struct_ops_link_lops;
 76
 77int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
 78			    union bpf_attr __user *uattr)
 79{
 80	const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
 81	const struct btf_type *func_proto;
 82	struct bpf_dummy_ops_test_args *args;
 83	struct bpf_tramp_links *tlinks;
 84	struct bpf_tramp_link *link = NULL;
 85	void *image = NULL;
 86	unsigned int op_idx;
 87	int prog_ret;
 88	int err;
 89
 90	if (prog->aux->attach_btf_id != st_ops->type_id)
 91		return -EOPNOTSUPP;
 92
 93	func_proto = prog->aux->attach_func_proto;
 94	args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
 95	if (IS_ERR(args))
 96		return PTR_ERR(args);
 97
 98	tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
 99	if (!tlinks) {
100		err = -ENOMEM;
101		goto out;
102	}
103
104	image = bpf_jit_alloc_exec(PAGE_SIZE);
105	if (!image) {
106		err = -ENOMEM;
107		goto out;
108	}
109	set_vm_flush_reset_perms(image);
110
111	link = kzalloc(sizeof(*link), GFP_USER);
112	if (!link) {
113		err = -ENOMEM;
114		goto out;
115	}
116	/* prog doesn't take the ownership of the reference from caller */
117	bpf_prog_inc(prog);
118	bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
119
120	op_idx = prog->expected_attach_type;
121	err = bpf_struct_ops_prepare_trampoline(tlinks, link,
122						&st_ops->func_models[op_idx],
123						image, image + PAGE_SIZE);
124	if (err < 0)
125		goto out;
126
127	set_memory_rox((long)image, 1);
128	prog_ret = dummy_ops_call_op(image, args);
129
130	err = dummy_ops_copy_args(args);
131	if (err)
132		goto out;
133	if (put_user(prog_ret, &uattr->test.retval))
134		err = -EFAULT;
135out:
136	kfree(args);
137	bpf_jit_free_exec(image);
138	if (link)
139		bpf_link_put(&link->link);
140	kfree(tlinks);
141	return err;
142}
143
144static int bpf_dummy_init(struct btf *btf)
145{
146	return 0;
147}
148
149static bool bpf_dummy_ops_is_valid_access(int off, int size,
150					  enum bpf_access_type type,
151					  const struct bpf_prog *prog,
152					  struct bpf_insn_access_aux *info)
153{
154	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
155}
156
157static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
158					   const struct bpf_reg_state *reg,
159					   int off, int size, enum bpf_access_type atype,
160					   u32 *next_btf_id,
161					   enum bpf_type_flag *flag)
162{
163	const struct btf_type *state;
164	const struct btf_type *t;
165	s32 type_id;
166	int err;
167
168	type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state",
169					BTF_KIND_STRUCT);
170	if (type_id < 0)
171		return -EINVAL;
172
173	t = btf_type_by_id(reg->btf, reg->btf_id);
174	state = btf_type_by_id(reg->btf, type_id);
175	if (t != state) {
176		bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
177		return -EACCES;
178	}
179
180	err = btf_struct_access(log, reg, off, size, atype, next_btf_id, flag);
181	if (err < 0)
182		return err;
183
184	return atype == BPF_READ ? err : NOT_INIT;
185}
186
187static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
188	.is_valid_access = bpf_dummy_ops_is_valid_access,
189	.btf_struct_access = bpf_dummy_ops_btf_struct_access,
190};
191
192static int bpf_dummy_init_member(const struct btf_type *t,
193				 const struct btf_member *member,
194				 void *kdata, const void *udata)
195{
196	return -EOPNOTSUPP;
197}
198
199static int bpf_dummy_reg(void *kdata)
200{
201	return -EOPNOTSUPP;
202}
203
204static void bpf_dummy_unreg(void *kdata)
205{
206}
207
208struct bpf_struct_ops bpf_bpf_dummy_ops = {
209	.verifier_ops = &bpf_dummy_verifier_ops,
210	.init = bpf_dummy_init,
211	.init_member = bpf_dummy_init_member,
212	.reg = bpf_dummy_reg,
213	.unreg = bpf_dummy_unreg,
214	.name = "bpf_dummy_ops",
215};