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 static int dummy_ops_test_ret_function(struct bpf_dummy_ops_state *state, ...) 16 { 17 return 0; 18 } 19 20 struct bpf_dummy_ops_test_args { 21 u64 args[MAX_BPF_FUNC_ARGS]; 22 struct bpf_dummy_ops_state state; 23 }; 24 25 static struct bpf_dummy_ops_test_args * 26 dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr) 27 { 28 __u32 size_in; 29 struct bpf_dummy_ops_test_args *args; 30 void __user *ctx_in; 31 void __user *u_state; 32 33 size_in = kattr->test.ctx_size_in; 34 if (size_in != sizeof(u64) * nr) 35 return ERR_PTR(-EINVAL); 36 37 args = kzalloc(sizeof(*args), GFP_KERNEL); 38 if (!args) 39 return ERR_PTR(-ENOMEM); 40 41 ctx_in = u64_to_user_ptr(kattr->test.ctx_in); 42 if (copy_from_user(args->args, ctx_in, size_in)) 43 goto out; 44 45 /* args[0] is 0 means state argument of test_N will be NULL */ 46 u_state = u64_to_user_ptr(args->args[0]); 47 if (u_state && copy_from_user(&args->state, u_state, 48 sizeof(args->state))) 49 goto out; 50 51 return args; 52 out: 53 kfree(args); 54 return ERR_PTR(-EFAULT); 55 } 56 57 static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args) 58 { 59 void __user *u_state; 60 61 u_state = u64_to_user_ptr(args->args[0]); 62 if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state))) 63 return -EFAULT; 64 65 return 0; 66 } 67 68 static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args) 69 { 70 dummy_ops_test_ret_fn test = (void *)image + cfi_get_offset(); 71 struct bpf_dummy_ops_state *state = NULL; 72 73 /* state needs to be NULL if args[0] is 0 */ 74 if (args->args[0]) 75 state = &args->state; 76 return test(state, args->args[1], args->args[2], 77 args->args[3], args->args[4]); 78 } 79 80 extern const struct bpf_link_ops bpf_struct_ops_link_lops; 81 82 int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, 83 union bpf_attr __user *uattr) 84 { 85 const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops; 86 const struct btf_type *func_proto; 87 struct bpf_dummy_ops_test_args *args; 88 struct bpf_tramp_links *tlinks; 89 struct bpf_tramp_link *link = NULL; 90 void *image = NULL; 91 unsigned int op_idx; 92 int prog_ret; 93 int err; 94 95 if (prog->aux->attach_btf_id != st_ops->type_id) 96 return -EOPNOTSUPP; 97 98 func_proto = prog->aux->attach_func_proto; 99 args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto)); 100 if (IS_ERR(args)) 101 return PTR_ERR(args); 102 103 tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL); 104 if (!tlinks) { 105 err = -ENOMEM; 106 goto out; 107 } 108 109 image = arch_alloc_bpf_trampoline(PAGE_SIZE); 110 if (!image) { 111 err = -ENOMEM; 112 goto out; 113 } 114 115 link = kzalloc(sizeof(*link), GFP_USER); 116 if (!link) { 117 err = -ENOMEM; 118 goto out; 119 } 120 /* prog doesn't take the ownership of the reference from caller */ 121 bpf_prog_inc(prog); 122 bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog); 123 124 op_idx = prog->expected_attach_type; 125 err = bpf_struct_ops_prepare_trampoline(tlinks, link, 126 &st_ops->func_models[op_idx], 127 &dummy_ops_test_ret_function, 128 image, image + PAGE_SIZE); 129 if (err < 0) 130 goto out; 131 132 arch_protect_bpf_trampoline(image, PAGE_SIZE); 133 prog_ret = dummy_ops_call_op(image, args); 134 135 err = dummy_ops_copy_args(args); 136 if (err) 137 goto out; 138 if (put_user(prog_ret, &uattr->test.retval)) 139 err = -EFAULT; 140 out: 141 kfree(args); 142 arch_free_bpf_trampoline(image, PAGE_SIZE); 143 if (link) 144 bpf_link_put(&link->link); 145 kfree(tlinks); 146 return err; 147 } 148 149 static int bpf_dummy_init(struct btf *btf) 150 { 151 return 0; 152 } 153 154 static bool bpf_dummy_ops_is_valid_access(int off, int size, 155 enum bpf_access_type type, 156 const struct bpf_prog *prog, 157 struct bpf_insn_access_aux *info) 158 { 159 return bpf_tracing_btf_ctx_access(off, size, type, prog, info); 160 } 161 162 static int bpf_dummy_ops_check_member(const struct btf_type *t, 163 const struct btf_member *member, 164 const struct bpf_prog *prog) 165 { 166 u32 moff = __btf_member_bit_offset(t, member) / 8; 167 168 switch (moff) { 169 case offsetof(struct bpf_dummy_ops, test_sleepable): 170 break; 171 default: 172 if (prog->aux->sleepable) 173 return -EINVAL; 174 } 175 176 return 0; 177 } 178 179 static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log, 180 const struct bpf_reg_state *reg, 181 int off, int size) 182 { 183 const struct btf_type *state; 184 const struct btf_type *t; 185 s32 type_id; 186 187 type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state", 188 BTF_KIND_STRUCT); 189 if (type_id < 0) 190 return -EINVAL; 191 192 t = btf_type_by_id(reg->btf, reg->btf_id); 193 state = btf_type_by_id(reg->btf, type_id); 194 if (t != state) { 195 bpf_log(log, "only access to bpf_dummy_ops_state is supported\n"); 196 return -EACCES; 197 } 198 199 if (off + size > sizeof(struct bpf_dummy_ops_state)) { 200 bpf_log(log, "write access at off %d with size %d\n", off, size); 201 return -EACCES; 202 } 203 204 return NOT_INIT; 205 } 206 207 static const struct bpf_verifier_ops bpf_dummy_verifier_ops = { 208 .is_valid_access = bpf_dummy_ops_is_valid_access, 209 .btf_struct_access = bpf_dummy_ops_btf_struct_access, 210 }; 211 212 static int bpf_dummy_init_member(const struct btf_type *t, 213 const struct btf_member *member, 214 void *kdata, const void *udata) 215 { 216 return -EOPNOTSUPP; 217 } 218 219 static int bpf_dummy_reg(void *kdata) 220 { 221 return -EOPNOTSUPP; 222 } 223 224 static void bpf_dummy_unreg(void *kdata) 225 { 226 } 227 228 static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb) 229 { 230 return 0; 231 } 232 233 static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2, 234 char a3, unsigned long a4) 235 { 236 return 0; 237 } 238 239 static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb) 240 { 241 return 0; 242 } 243 244 static struct bpf_dummy_ops __bpf_bpf_dummy_ops = { 245 .test_1 = bpf_dummy_test_1, 246 .test_2 = bpf_dummy_test_2, 247 .test_sleepable = bpf_dummy_test_sleepable, 248 }; 249 250 struct bpf_struct_ops bpf_bpf_dummy_ops = { 251 .verifier_ops = &bpf_dummy_verifier_ops, 252 .init = bpf_dummy_init, 253 .check_member = bpf_dummy_ops_check_member, 254 .init_member = bpf_dummy_init_member, 255 .reg = bpf_dummy_reg, 256 .unreg = bpf_dummy_unreg, 257 .name = "bpf_dummy_ops", 258 .cfi_stubs = &__bpf_bpf_dummy_ops, 259 }; 260