[RFC PATCH bpf-next seccomp 10/12] seccomp-ebpf: Add ability to read user memory

[Alexei Starovoitov]

On Mon, May 10, 2021 at 12:22:47PM -0500, YiFei Zhu wrote:
>  
> +BPF_CALL_3(bpf_probe_read_user_dumpable, void *, dst, u32, size,
> +	   const void __user *, unsafe_ptr)
> +{
> +	int ret = -EPERM;
> +
> +	if (get_dumpable(current->mm))
> +		ret = copy_from_user_nofault(dst, unsafe_ptr, size);

Could you explain a bit more how dumpable flag makes it safe for unpriv?
The unpriv prog is attached to the children tasks only, right?
and dumpable gets cleared if euid changes?