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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021. Huawei Technologies Co., Ltd
*/
#include <linux/kernel.h>
#include <linux/bpf_verifier.h>
#include <linux/bpf.h>
#include <linux/btf.h>
extern struct bpf_struct_ops bpf_bpf_dummy_ops;
/* A common type for test_N with return value in bpf_dummy_ops */
typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
struct bpf_dummy_ops_test_args {
u64 args[MAX_BPF_FUNC_ARGS];
struct bpf_dummy_ops_state state;
};
static struct bpf_dummy_ops_test_args *
dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
{
__u32 size_in;
struct bpf_dummy_ops_test_args *args;
void __user *ctx_in;
void __user *u_state;
size_in = kattr->test.ctx_size_in;
if (size_in != sizeof(u64) * nr)
return ERR_PTR(-EINVAL);
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args)
return ERR_PTR(-ENOMEM);
ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
if (copy_from_user(args->args, ctx_in, size_in))
goto out;
/* args[0] is 0 means state argument of test_N will be NULL */
u_state = u64_to_user_ptr(args->args[0]);
if (u_state && copy_from_user(&args->state, u_state,
sizeof(args->state)))
goto out;
return args;
out:
kfree(args);
return ERR_PTR(-EFAULT);
}
static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
{
void __user *u_state;
u_state = u64_to_user_ptr(args->args[0]);
if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
return -EFAULT;
return 0;
}
static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
{
dummy_ops_test_ret_fn test = (void *)image;
struct bpf_dummy_ops_state *state = NULL;
/* state needs to be NULL if args[0] is 0 */
if (args->args[0])
state = &args->state;
return test(state, args->args[1], args->args[2],
args->args[3], args->args[4]);
}
extern const struct bpf_link_ops bpf_struct_ops_link_lops;
int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
const struct btf_type *func_proto;
struct bpf_dummy_ops_test_args *args;
struct bpf_tramp_links *tlinks;
struct bpf_tramp_link *link = NULL;
void *image = NULL;
unsigned int op_idx;
int prog_ret;
int err;
if (prog->aux->attach_btf_id != st_ops->type_id)
return -EOPNOTSUPP;
func_proto = prog->aux->attach_func_proto;
args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
if (IS_ERR(args))
return PTR_ERR(args);
tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
if (!tlinks) {
err = -ENOMEM;
goto out;
}
image = bpf_jit_alloc_exec(PAGE_SIZE);
if (!image) {
err = -ENOMEM;
goto out;
}
set_vm_flush_reset_perms(image);
link = kzalloc(sizeof(*link), GFP_USER);
if (!link) {
err = -ENOMEM;
goto out;
}
/* prog doesn't take the ownership of the reference from caller */
bpf_prog_inc(prog);
bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, &bpf_struct_ops_link_lops, prog);
op_idx = prog->expected_attach_type;
err = bpf_struct_ops_prepare_trampoline(tlinks, link,
&st_ops->func_models[op_idx],
image, image + PAGE_SIZE);
if (err < 0)
goto out;
set_memory_rox((long)image, 1);
prog_ret = dummy_ops_call_op(image, args);
err = dummy_ops_copy_args(args);
if (err)
goto out;
if (put_user(prog_ret, &uattr->test.retval))
err = -EFAULT;
out:
kfree(args);
bpf_jit_free_exec(image);
if (link)
bpf_link_put(&link->link);
kfree(tlinks);
return err;
}
static int bpf_dummy_init(struct btf *btf)
{
return 0;
}
static bool bpf_dummy_ops_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
}
static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
const struct bpf_reg_state *reg,
int off, int size, enum bpf_access_type atype,
u32 *next_btf_id,
enum bpf_type_flag *flag)
{
const struct btf_type *state;
const struct btf_type *t;
s32 type_id;
int err;
type_id = btf_find_by_name_kind(reg->btf, "bpf_dummy_ops_state",
BTF_KIND_STRUCT);
if (type_id < 0)
return -EINVAL;
t = btf_type_by_id(reg->btf, reg->btf_id);
state = btf_type_by_id(reg->btf, type_id);
if (t != state) {
bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
return -EACCES;
}
err = btf_struct_access(log, reg, off, size, atype, next_btf_id, flag);
if (err < 0)
return err;
return atype == BPF_READ ? err : NOT_INIT;
}
static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
.is_valid_access = bpf_dummy_ops_is_valid_access,
.btf_struct_access = bpf_dummy_ops_btf_struct_access,
};
static int bpf_dummy_init_member(const struct btf_type *t,
const struct btf_member *member,
void *kdata, const void *udata)
{
return -EOPNOTSUPP;
}
static int bpf_dummy_reg(void *kdata)
{
return -EOPNOTSUPP;
}
static void bpf_dummy_unreg(void *kdata)
{
}
struct bpf_struct_ops bpf_bpf_dummy_ops = {
.verifier_ops = &bpf_dummy_verifier_ops,
.init = bpf_dummy_init,
.init_member = bpf_dummy_init_member,
.reg = bpf_dummy_reg,
.unreg = bpf_dummy_unreg,
.name = "bpf_dummy_ops",
};
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