bpf_dummy_struct_ops.c (5282B)
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_ro((long)image, 1); 128 set_memory_x((long)image, 1); 129 prog_ret = dummy_ops_call_op(image, args); 130 131 err = dummy_ops_copy_args(args); 132 if (err) 133 goto out; 134 if (put_user(prog_ret, &uattr->test.retval)) 135 err = -EFAULT; 136out: 137 kfree(args); 138 bpf_jit_free_exec(image); 139 if (link) 140 bpf_link_put(&link->link); 141 kfree(tlinks); 142 return err; 143} 144 145static int bpf_dummy_init(struct btf *btf) 146{ 147 return 0; 148} 149 150static bool bpf_dummy_ops_is_valid_access(int off, int size, 151 enum bpf_access_type type, 152 const struct bpf_prog *prog, 153 struct bpf_insn_access_aux *info) 154{ 155 return bpf_tracing_btf_ctx_access(off, size, type, prog, info); 156} 157 158static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log, 159 const struct btf *btf, 160 const struct btf_type *t, int off, 161 int size, enum bpf_access_type atype, 162 u32 *next_btf_id, 163 enum bpf_type_flag *flag) 164{ 165 const struct btf_type *state; 166 s32 type_id; 167 int err; 168 169 type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state", 170 BTF_KIND_STRUCT); 171 if (type_id < 0) 172 return -EINVAL; 173 174 state = btf_type_by_id(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, btf, t, off, size, atype, next_btf_id, 181 flag); 182 if (err < 0) 183 return err; 184 185 return atype == BPF_READ ? err : NOT_INIT; 186} 187 188static const struct bpf_verifier_ops bpf_dummy_verifier_ops = { 189 .is_valid_access = bpf_dummy_ops_is_valid_access, 190 .btf_struct_access = bpf_dummy_ops_btf_struct_access, 191}; 192 193static int bpf_dummy_init_member(const struct btf_type *t, 194 const struct btf_member *member, 195 void *kdata, const void *udata) 196{ 197 return -EOPNOTSUPP; 198} 199 200static int bpf_dummy_reg(void *kdata) 201{ 202 return -EOPNOTSUPP; 203} 204 205static void bpf_dummy_unreg(void *kdata) 206{ 207} 208 209struct bpf_struct_ops bpf_bpf_dummy_ops = { 210 .verifier_ops = &bpf_dummy_verifier_ops, 211 .init = bpf_dummy_init, 212 .init_member = bpf_dummy_init_member, 213 .reg = bpf_dummy_reg, 214 .unreg = bpf_dummy_unreg, 215 .name = "bpf_dummy_ops", 216};