On Thu, Oct 19, 2017 at 11:48:34PM +0100, David Howells wrote: > Alexei Starovoitov <alexei.starovoi...@gmail.com> wrote: > > > > @@ -65,6 +65,11 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, > > > const void *, unsafe_ptr) > > > { > > > int ret; > > > > > > + if (kernel_is_locked_down("BPF")) { > > > + memset(dst, 0, size); > > > + return -EPERM; > > > + } > > > > That doesn't help the lockdown purpose. > > If you don't trust the root the only way to prevent bpf read > > memory is to disable the whole thing. > > Have a single check in sys_bpf() to disallow everything if > > kernel_is_locked_down() > > and don't add overhead to critical path like bpf_probe_read(). > > TBH, I've no idea how bpf does anything, so I can't say whether this is > better, overkill or insufficient.
ok. To make it clear: Nacked-by: Alexei Starovoitov <a...@kernel.org> For the current patch. Unnecessary checks for no good reason in performance critical functions are not acceptable. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html