On Tue, Apr 03, 2018 at 08:11:07AM -0700, Andy Lutomirski wrote: > > > >> "bpf: Restrict kernel image access functions when the kernel is locked down": > >> This patch just sucks in general. > > > > Yes - but that's what Alexei Starovoitov specified. bpf kind of sucks since > > it gives you unrestricted access to the kernel. > > bpf, in certain contexts, gives you unrestricted access to *reading* > kernel memory. bpf should, under no circumstances, let you write to > the kernel unless you're using fault injection or similar. > > I'm surprised that Alexei acked this patch. If something like XDP or > bpfilter starts becoming widely used, this patch will require a lot of > reworking to avoid breaking standard distros. my understanding was that this lockdown set attemps to disallow _reads_ of kernel memory from anything, so first version of patch was adding run-time checks for bpf_probe_read() which is no-go and without this helper the bpf for tracing is losing a lot of its power, so the easiest is to disable it all. I think lockdown suppose to disable xdp, bpfilter, nflog, raw sockets + pcap too otherwise even cap_net_admin can see traffic coming into host. Similarly kprobe, perf_event, ftrace should be off as well? -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
