diff options
Diffstat (limited to 'net/bpf/bpf_dummy_struct_ops.c')
| -rw-r--r-- | net/bpf/bpf_dummy_struct_ops.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c new file mode 100644 index 000000000000..fbc896323bec --- /dev/null +++ b/net/bpf/bpf_dummy_struct_ops.c @@ -0,0 +1,200 @@ +// 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]); +} + +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_progs *tprogs; + 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); + + tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL); + if (!tprogs) { + err = -ENOMEM; + goto out; + } + + image = bpf_jit_alloc_exec(PAGE_SIZE); + if (!image) { + err = -ENOMEM; + goto out; + } + set_vm_flush_reset_perms(image); + + op_idx = prog->expected_attach_type; + err = bpf_struct_ops_prepare_trampoline(tprogs, prog, + &st_ops->func_models[op_idx], + image, image + PAGE_SIZE); + if (err < 0) + goto out; + + set_memory_ro((long)image, 1); + set_memory_x((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); + kfree(tprogs); + 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 btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id) +{ + const struct btf_type *state; + s32 type_id; + int err; + + type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state", + BTF_KIND_STRUCT); + if (type_id < 0) + return -EINVAL; + + state = btf_type_by_id(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, btf, t, off, size, atype, next_btf_id); + 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", +}; |