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 extern const struct bpf_link_ops bpf_struct_ops_link_lops; 83 84 int 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; 144 out: 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 } 152 153 static int bpf_dummy_init(struct btf *btf) 154 { 155 bpf_dummy_ops_btf = btf; 156 return 0; 157 } 158 159 static 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 } 166 167 static 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 } 183 184 static 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 } 211 212 static 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 }; 216 217 static 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 } 223 224 static int bpf_dummy_reg(void *kdata) 225 { 226 return -EOPNOTSUPP; 227 } 228 229 static void bpf_dummy_unreg(void *kdata) 230 { 231 } 232 233 static int bpf_dummy_test_1(struct bpf_dummy_ops_state *cb) 234 { 235 return 0; 236 } 237 238 static 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 } 243 244 static int bpf_dummy_test_sleepable(struct bpf_dummy_ops_state *cb) 245 { 246 return 0; 247 } 248 249 static 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 }; 254 255 static 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 }; 266 267 static int __init bpf_dummy_struct_ops_init(void) 268 { 269 return register_bpf_struct_ops(&bpf_bpf_dummy_ops, bpf_dummy_ops); 270 } 271 late_initcall(bpf_dummy_struct_ops_init); 272