Add EventChannel messages for uncaught signals.

PiperOrigin-RevId: 226936778
Change-Id: I2a6dda157c55d39d81e1b543ab11a58a0bfe5c05

pkg/sentry/kernel/BUILD

@@ -1,3 +1,5 @@
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+
 package(licenses = ["notice"])  # Apache 2.0
 
 load("//tools/go_generics:defs.bzl", "go_template_instance")
@@ -62,6 +64,21 @@ go_template_instance(
     },
 )
 
+proto_library(
+    name = "uncaught_signal_proto",
+    srcs = ["uncaught_signal.proto"],
+    visibility = ["//visibility:public"],
+    deps = ["//pkg/sentry/arch:registers_proto"],
+)
+
+go_proto_library(
+    name = "uncaught_signal_go_proto",
+    importpath = "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto",
+    proto = ":uncaught_signal_proto",
+    visibility = ["//visibility:public"],
+    deps = ["//pkg/sentry/arch:registers_go_proto"],
+)
+
 go_library(
     name = "kernel",
     srcs = [
@@ -122,6 +139,7 @@ go_library(
     ],
     visibility = ["//:sandbox"],
     deps = [
+        ":uncaught_signal_go_proto",
         "//pkg/abi",
         "//pkg/abi/linux",
         "//pkg/amutex",

pkg/sentry/kernel/task_signals.go

@@ -22,8 +22,10 @@ import (
 	"time"
 
 	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/eventchannel"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
+	ucspb "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
 	"gvisor.googlesource.com/gvisor/pkg/syserror"
 )
@@ -184,6 +186,23 @@ func (t *Task) deliverSignal(info *arch.SignalInfo, act arch.SignalAct) taskRunS
 	case SignalActionTerm, SignalActionCore:
 		// "Default action is to terminate the process." - signal(7)
 		t.Debugf("Signal %d: terminating thread group", info.Signo)
+
+		// Emit an event channel messages related to this uncaught signal.
+		ucs := &ucspb.UncaughtSignal{
+			Tid:          int32(t.Kernel().TaskSet().Root.IDOfTask(t)),
+			Pid:          int32(t.Kernel().TaskSet().Root.IDOfThreadGroup(t.ThreadGroup())),
+			Registers:    t.Arch().StateData().Proto(),
+			SignalNumber: info.Signo,
+		}
+
+		// Attach an fault address if appropriate.
+		switch linux.Signal(info.Signo) {
+		case linux.SIGSEGV, linux.SIGFPE, linux.SIGILL, linux.SIGTRAP, linux.SIGBUS:
+			ucs.FaultAddr = info.Addr()
+		}
+
+		eventchannel.Emit(ucs)
+
 		t.PrepareGroupExit(ExitStatus{Signo: int(info.Signo)})
 		return (*runExit)(nil)
 

pkg/sentry/kernel/uncaught_signal.proto

@@ -0,0 +1,37 @@
+// Copyright 2018 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package gvisor;
+
+import "pkg/sentry/arch/registers.proto";
+
+message UncaughtSignal {
+  // Thread ID.
+  int32 tid = 1;
+
+  // Process ID.
+  int32 pid = 2;
+
+  // Registers at the time of the fault or signal.
+  Registers registers = 3;
+
+  // Signal number.
+  int32 signal_number = 4;
+
+  // The memory location which caused the fault (set if applicable, 0
+  // otherwise). This will be set for SIGILL, SIGFPE, SIGSEGV, and SIGBUS.
+  uint64 fault_addr = 5;
+}