netdev - RE: [PATCH v2 bpf-next 01/16] bpf: Introduce bpf_sys

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Date:   Tue, 27 Apr 2021 11:45:29 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        davem@...emloft.net
Cc:     daniel@...earbox.net, andrii@...nel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, kernel-team@...com
Subject: RE: [PATCH v2 bpf-next 01/16] bpf: Introduce bpf_sys_bpf() helper and
 program type.

Alexei Starovoitov wrote:
> From: Alexei Starovoitov <ast@...nel.org>
> 
> Add placeholders for bpf_sys_bpf() helper and new program type.
> 
> v1->v2:
> - check that expected_attach_type is zero
> - allow more helper functions to be used in this program type, since they will
>   only execute from user context via bpf_prog_test_run.
> 
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> ---

Acked-by: John Fastabend <john.fastabend@...il.com>

> +int bpf_prog_test_run_syscall(struct bpf_prog *prog,
> +			      const union bpf_attr *kattr,
> +			      union bpf_attr __user *uattr)
> +{
> +	void __user *ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
> +	__u32 ctx_size_in = kattr->test.ctx_size_in;
> +	void *ctx = NULL;
> +	u32 retval;
> +	int err = 0;
> +
> +	/* doesn't support data_in/out, ctx_out, duration, or repeat or flags */
> +	if (kattr->test.data_in || kattr->test.data_out ||
> +	    kattr->test.ctx_out || kattr->test.duration ||
> +	    kattr->test.repeat || kattr->test.flags)
> +		return -EINVAL;
> +
> +	if (ctx_size_in < prog->aux->max_ctx_offset ||
> +	    ctx_size_in > U16_MAX)
> +		return -EINVAL;
> +
> +	if (ctx_size_in) {
> +		ctx = kzalloc(ctx_size_in, GFP_USER);
> +		if (!ctx)
> +			return -ENOMEM;
> +		if (copy_from_user(ctx, ctx_in, ctx_size_in)) {
> +			err = -EFAULT;
> +			goto out;
> +		}
> +	}
> +	retval = bpf_prog_run_pin_on_cpu(prog, ctx);
> +
> +	if (copy_to_user(&uattr->test.retval, &retval, sizeof(u32)))
> +		err = -EFAULT;
> +	if (ctx_size_in)
> +		if (copy_to_user(ctx_in, ctx, ctx_size_in)) {
> +			err = -EFAULT;
> +			goto out;
> +		}

stupid nit, the last goto there is not needed.

> +out:
> +	kfree(ctx);
> +	return err;
> +}