On 04/04/2017 08:33 PM, Aaron Conole wrote:
The eBPF framework is used for more than just socket level filtering. It can also provide tracing, and even change the way packets coming into the system look. Most of the eBPF callable symbols are available to non-gpl programs, and this includes helper functions which modify packets. This allows proprietary eBPF code to link to the kernel and make decisions which can negatively impact network performance.Since the sources for these programs are only available under a proprietary license, it seems better to treat them the same as other proprietary modules: set the system taint flag. An exemption is made for socket-level filters, since they do not really impact networking for the whole kernel. Signed-off-by: Aaron Conole <acon...@bytheb.org> --- kernel/bpf/syscall.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ab0cf4c4..1255b51 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -860,6 +860,11 @@ static int bpf_prog_load(union bpf_attr *attr) bpf_prog_kallsyms_add(prog); trace_bpf_prog_load(prog, err); + if (type != BPF_PROG_TYPE_SOCKET_FILTER && !is_gpl && !(err < 0)) { + if (!test_taint(TAINT_PROPRIETARY_MODULE)) + pr_warn("bpf license '%s' taints kernel.\n", license); + add_taint(TAINT_PROPRIETARY_MODULE, LOCKDEP_STILL_OK); + } return err; free_used_maps:
Nacked-by: Daniel Borkmann <dan...@iogearbox.net> This is proposal completely unreasonable; what the purpose of .gpl_only flags is agreed upon since the beginning is that some of the helpers are only available if the program is loaded as gpl, f.e. bpf_ktime_get_ns(), bpf_probe_read(), bpf_probe_write_user(), bpf_trace_printk(), bpf_skb_event_output(), etc. Now, suddenly switching from one kernel version to another, existing programs would out of a sudden taint the kernel, which by itself is unacceptable. There are also many other subsystems that can modify packets, or affect system performance negatively if configured wrongly and which in addition *don't require* a hard capable(CAP_SYS_ADMIN) restriction like such eBPF programs already do, perhaps should we taint them as well? Plus tracing programs are attached to passively monitor systems performance, not even modifying data structures ... The current purpose of .gpl_only is fine as-is, and there's work in progress for a generic dump mechanism that works with all program types to improve introspection aspect if that's what you're after, starting to taint is, in a way, breaking existing applications and this is not acceptable.
