On Sat, Oct 16, 2021 at 08:48:04PM +0800, Hou Tao wrote:
> +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;
> +
> + if (!nr || nr > MAX_BPF_FUNC_ARGS)
> + return ERR_PTR(-EINVAL);
> +
> + 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))
args is leaked.
> + return ERR_PTR(-EFAULT);
> +
> + u_state = u64_to_user_ptr(args->args[0]);
> + if (!u_state)
> + return args;
> +
> + if (copy_from_user(&args->state, u_state, sizeof(args->state))) {
> + kfree(args);
> + return ERR_PTR(-EFAULT);
> + }
> +
> + return args;
> +}
[ ... ]
> +int bpf_dummy_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 = prog->aux->attach_func_proto;
> + struct bpf_dummy_ops_test_args *args = NULL;
> + struct bpf_tramp_progs *tprogs = NULL;
args = NULL and tprogs = NULL are not needed.
> + void *image = NULL;
> + unsigned int op_idx;
> + int err;
> + int prog_ret;
> +
> + 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)
> +{
> + s32 type_id;
> +
> + type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state",
> + BTF_KIND_STRUCT);
> + if (type_id < 0)
> + return -EINVAL;
> +
> + dummy_ops_state = btf_type_by_id(btf, type_id);
Probably just do btf_find_by_name_kind("bpf_dummy_ops_state")
in bpf_dummy_ops_btf_struct_access() during each test. There is
no need to optimize and cache it only for the testing purpose.
> +
> + 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_check_btf_func_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)
> +{
> + int err;
> +
> + if (atype != BPF_READ && t != dummy_ops_state) {
I think this can be further simplified. The only struct that
the bpf_prog can access is bpf_dummy_ops_state, so the
"atype != BPF_READ" test can be removed. The log message
then needs to be adjusted.
Others lgtm.
> + bpf_log(log, "only write 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;
> +}
