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 
10 extern struct bpf_struct_ops bpf_bpf_dummy_ops;
11 
12 /* A common type for test_N with return value in bpf_dummy_ops */
13 typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
14 
15 struct bpf_dummy_ops_test_args {
16 	u64 args[MAX_BPF_FUNC_ARGS];
17 	struct bpf_dummy_ops_state state;
18 };
19 
20 static struct bpf_dummy_ops_test_args *
21 dummy_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;
47 out:
48 	kfree(args);
49 	return ERR_PTR(-EFAULT);
50 }
51 
52 static 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 
63 static 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 
75 int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
76 			    union bpf_attr __user *uattr)
77 {
78 	const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
79 	const struct btf_type *func_proto;
80 	struct bpf_dummy_ops_test_args *args;
81 	struct bpf_tramp_progs *tprogs;
82 	void *image = NULL;
83 	unsigned int op_idx;
84 	int prog_ret;
85 	int err;
86 
87 	if (prog->aux->attach_btf_id != st_ops->type_id)
88 		return -EOPNOTSUPP;
89 
90 	func_proto = prog->aux->attach_func_proto;
91 	args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
92 	if (IS_ERR(args))
93 		return PTR_ERR(args);
94 
95 	tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
96 	if (!tprogs) {
97 		err = -ENOMEM;
98 		goto out;
99 	}
100 
101 	image = bpf_jit_alloc_exec(PAGE_SIZE);
102 	if (!image) {
103 		err = -ENOMEM;
104 		goto out;
105 	}
106 	set_vm_flush_reset_perms(image);
107 
108 	op_idx = prog->expected_attach_type;
109 	err = bpf_struct_ops_prepare_trampoline(tprogs, prog,
110 						&st_ops->func_models[op_idx],
111 						image, image + PAGE_SIZE);
112 	if (err < 0)
113 		goto out;
114 
115 	set_memory_ro((long)image, 1);
116 	set_memory_x((long)image, 1);
117 	prog_ret = dummy_ops_call_op(image, args);
118 
119 	err = dummy_ops_copy_args(args);
120 	if (err)
121 		goto out;
122 	if (put_user(prog_ret, &uattr->test.retval))
123 		err = -EFAULT;
124 out:
125 	kfree(args);
126 	bpf_jit_free_exec(image);
127 	kfree(tprogs);
128 	return err;
129 }
130 
131 static int bpf_dummy_init(struct btf *btf)
132 {
133 	return 0;
134 }
135 
136 static bool bpf_dummy_ops_is_valid_access(int off, int size,
137 					  enum bpf_access_type type,
138 					  const struct bpf_prog *prog,
139 					  struct bpf_insn_access_aux *info)
140 {
141 	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
142 }
143 
144 static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
145 					   const struct btf *btf,
146 					   const struct btf_type *t, int off,
147 					   int size, enum bpf_access_type atype,
148 					   u32 *next_btf_id,
149 					   enum bpf_type_flag *flag)
150 {
151 	const struct btf_type *state;
152 	s32 type_id;
153 	int err;
154 
155 	type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state",
156 					BTF_KIND_STRUCT);
157 	if (type_id < 0)
158 		return -EINVAL;
159 
160 	state = btf_type_by_id(btf, type_id);
161 	if (t != state) {
162 		bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
163 		return -EACCES;
164 	}
165 
166 	err = btf_struct_access(log, btf, t, off, size, atype, next_btf_id,
167 				flag);
168 	if (err < 0)
169 		return err;
170 
171 	return atype == BPF_READ ? err : NOT_INIT;
172 }
173 
174 static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
175 	.is_valid_access = bpf_dummy_ops_is_valid_access,
176 	.btf_struct_access = bpf_dummy_ops_btf_struct_access,
177 };
178 
179 static int bpf_dummy_init_member(const struct btf_type *t,
180 				 const struct btf_member *member,
181 				 void *kdata, const void *udata)
182 {
183 	return -EOPNOTSUPP;
184 }
185 
186 static int bpf_dummy_reg(void *kdata)
187 {
188 	return -EOPNOTSUPP;
189 }
190 
191 static void bpf_dummy_unreg(void *kdata)
192 {
193 }
194 
195 struct bpf_struct_ops bpf_bpf_dummy_ops = {
196 	.verifier_ops = &bpf_dummy_verifier_ops,
197 	.init = bpf_dummy_init,
198 	.init_member = bpf_dummy_init_member,
199 	.reg = bpf_dummy_reg,
200 	.unreg = bpf_dummy_unreg,
201 	.name = "bpf_dummy_ops",
202 };
203