ext-authz: Envoy crashes when a gRPC service responds with UNKNOWN status.

[gsagula]

Description:
When a gRPC authorization server responds with a message that contains google.rpc.UNKNOWN status, Envoy crashes.

Repro steps:
Implement an Authorization gRPC service that responds with a message contains a CheckResponse message with google.rpc.UNKNOWN status. Envoy should return 403 instead of crashing.

For more details emissary-ingress/emissary#1291

Call Stack:

[2019-03-06 21:27:58.435][000078][critical][assert] [source/extensions/filters/common/ext_authz/ext_authz_grpc_impl.cc:42] assert failure: response->status().code() != Grpc::Status::GrpcStatus::Unknown.
[2019-03-06 21:27:58.435][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:125] Caught Aborted, suspect faulting address 0x45
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:94] Backtrace thr<78> obj</usr/glibc-compat/lib/libc.so.6> (If unsymbolized, use tools/stack_decode.py):
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #0 0x7fa19a53f46b (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #1 0x7fa19a540790 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:104] thr<78> obj<envoy>
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #2 0x6b8b4e (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #3 0x6bae27 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #4 0xd6c0d7 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #5 0xd6b560 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #6 0xd70638 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #7 0xd7dbdb (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #8 0xd7f5aa (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #9 0xcc880c (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #10 0xe030dc (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #11 0xe04ed2 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #12 0xe04f02 (unknown)
[2019-03-06 21:27:58.436][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #13 0xe1557b (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #14 0xe024d1 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #15 0xd57508 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #16 0xd57f2b (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #17 0xa9b24a (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #18 0xa9b35e (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #19 0xa91f2c (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #20 0xa935b9 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #21 0xa9335a (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #22 0xa8fc5c (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #23 0xa952fd (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #24 0xa8890b (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #25 0xa88610 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #26 0xa8868f (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #27 0x10d6854 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #28 0x10d6f9e (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #29 0x10d9d27 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #30 0xa83f9d (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #31 0xa75b52 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #32 0xa754e5 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #33 0xa76bea (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #34 0x502bd5 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #35 0x10e8157 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #36 0x10e817c (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:104] thr<78> obj</usr/glibc-compat/lib/libpthread.so.0>
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #37 0x7fa19ac10cf7 (unknown)
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:104] thr<78> obj</usr/glibc-compat/lib/libc.so.6>
[2019-03-06 21:27:58.437][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:117] thr<78> #38 0x7fa19a6010de (unknown)
[2019-03-06 21:27:58.438][000078][critical][backtrace] [bazel-out/k8-dbg/bin/source/server/_virtual_includes/backtrace_lib/server/backtrace.h:121] end backtrace thread 78

[gsagula]

/assign gsagula

[stale]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or other activity occurs. Thank you for your contributions.

[gsagula]

Working on that.