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 static 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 btf *bpf_dummy_ops_btf; 26 27 static struct bpf_dummy_ops_test_args * 28 dummy_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; 54 out: 55 kfree(args); 56 return ERR_PTR(-EFAULT); 57 } 58 59 static 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 70 static 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 82 static 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 */ 96 static 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 } 126 127 extern const struct bpf_link_ops bpf_struct_ops_link_lops; 128 129 int 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_links *tlinks = 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 tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL); 162 if (!tlinks) { 163 err = -ENOMEM; 164 goto out; 165 } 166 167 link = kzalloc(sizeof(*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_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog); 175 176 op_idx = prog->expected_attach_type; 177 err = bpf_struct_ops_prepare_trampoline(tlinks, link, 178 &st_ops->func_models[op_idx], 179 &dummy_ops_test_ret_function, 180 &image, &image_off, 181 true); 182 if (err < 0) 183 goto out; 184 185 err = arch_protect_bpf_trampoline(image, PAGE_SIZE); 186 if (err) 187 goto out; 188 prog_ret = dummy_ops_call_op(image, args); 189 190 err = dummy_ops_copy_args(args); 191 if (err) 192 goto out; 193 if (put_user(prog_ret, &uattr->test.retval)) 194 err = -EFAULT; 195 out: 196 kfree(args); 197 bpf_struct_ops_image_free(image); 198 if (link) 199 bpf_link_put(&link->link); 200 kfree(tlinks); 201 return err; 202 } 203 204 static int bpf_dummy_init(struct btf *btf) 205 { 206 bpf_dummy_ops_btf = btf; 207 return 0; 208 } 209 210 static bool bpf_dummy_ops_is_valid_access(int off, int size, 211 enum bpf_access_type type, 212 const struct bpf_prog *prog, 213 struct bpf_insn_access_aux *info) 214 { 215 return bpf_tracing_btf_ctx_access(off, size, type, prog, info); 216 } 217 218 static int bpf_dummy_ops_check_member(const struct btf_type *t, 219 const struct btf_member *member, 220 const struct bpf_prog *prog) 221 { 222 u32 moff = __btf_member_bit_offset(t, member) / 8; 223 224 switch (moff) { 225 case offsetof(struct bpf_dummy_ops, test_sleepable): 226 break; 227 default: 228 if (prog->sleepable) 229 return -EINVAL; 230 } 231 232 return 0; 233 } 234 235 static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log, 236 const struct bpf_reg_state *reg, 237 int off, int size) 238 { 239 const struct btf_type *state; 240 const struct btf_type *t; 241 s32 type_id; 242 243 type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state", 244 BTF_KIND_STRUCT); 245 if (type_id < 0) 246 return -EINVAL; 247 248 t = btf_type_by_id(reg->btf, reg->btf_id); 249 state = btf_type_by_id(reg->btf, type_id); 250 if (t != state) { 251 bpf_log(log, "only access to bpf_dummy_ops_state is supported\n"); 252 return -EACCES; 253 } 254 255 if (off + size > sizeof(struct bpf_dummy_ops_state)) { 256 bpf_log(log, "write access at off %d with size %d\n", off, size); 257 return -EACCES; 258 } 259 260 return NOT_INIT; 261 } 262 263 static const struct bpf_verifier_ops bpf_dummy_verifier_ops = { 264 .is_valid_access = bpf_dummy_ops_is_valid_access, 265 .btf_struct_access = bpf_dummy_ops_btf_struct_access, 266 }; 267 268 static int bpf_dummy_init_member(const struct btf_type *t, 269 const struct btf_member *member, 270 void *kdata, const void *udata) 271 { 272 return -EOPNOTSUPP; 273 } 274 275 static int bpf_dummy_reg(void *kdata, struct bpf_link *link) 276 { 277 return -EOPNOTSUPP; 278 } 279 280 static void bpf_dummy_unreg(void *kdata, struct bpf_link *link) 281 { 282 } 283 284 static int bpf_dummy_ops__test_1(struct bpf_dummy_ops_state *cb__nullable) 285 { 286 return 0; 287 } 288 289 static int bpf_dummy_test_2(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2, 290 char a3, unsigned long a4) 291 { 292 return 0; 293 } 294 295 static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb) 296 { 297 return 0; 298 } 299 300 static struct bpf_dummy_ops __bpf_bpf_dummy_ops = { 301 .test_1 = bpf_dummy_ops__test_1, 302 .test_2 = bpf_dummy_test_2, 303 .test_sleepable = bpf_dummy_test_sleepable, 304 }; 305 306 static struct bpf_struct_ops bpf_bpf_dummy_ops = { 307 .verifier_ops = &bpf_dummy_verifier_ops, 308 .init = bpf_dummy_init, 309 .check_member = bpf_dummy_ops_check_member, 310 .init_member = bpf_dummy_init_member, 311 .reg = bpf_dummy_reg, 312 .unreg = bpf_dummy_unreg, 313 .name = "bpf_dummy_ops", 314 .cfi_stubs = &__bpf_bpf_dummy_ops, 315 .owner = THIS_MODULE, 316 }; 317 318 static int __init bpf_dummy_struct_ops_init(void) 319 { 320 return register_bpf_struct_ops(&bpf_bpf_dummy_ops, bpf_dummy_ops); 321 } 322 late_initcall(bpf_dummy_struct_ops_init); 323