Send SIGPIPE for closed pipes.

Fixes #5974
Updates #161

PiperOrigin-RevId: 375024740

pkg/abi/linux/BUILD

@@ -15,6 +15,7 @@ go_library(
         "bpf.go",
         "capability.go",
         "clone.go",
+        "context.go",
         "dev.go",
         "elf.go",
         "epoll.go",
@@ -77,6 +78,7 @@ go_library(
     deps = [
         "//pkg/abi",
         "//pkg/bits",
+        "//pkg/context",
         "//pkg/marshal",
         "//pkg/marshal/primitive",
     ],

pkg/abi/linux/context.go

@@ -0,0 +1,36 @@
+// Copyright 2021 The gVisor Authors.
+//
+// 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.
+
+package linux
+
+import (
+	"gvisor.dev/gvisor/pkg/context"
+)
+
+// contextID is the linux package's type for context.Context.Value keys.
+type contextID int
+
+const (
+	// CtxSignalNoInfoFunc is a Context.Value key for a function to send signals.
+	CtxSignalNoInfoFunc contextID = iota
+)
+
+// SignalNoInfoFuncFromContext returns a callback function that can be used to send a
+// signal to the given context.
+func SignalNoInfoFuncFromContext(ctx context.Context) func(Signal) error {
+	if f := ctx.Value(CtxSignalNoInfoFunc); f != nil {
+		return f.(func(Signal) error)
+	}
+	return nil
+}

pkg/sentry/kernel/pipe/pipe_util.go

@@ -86,6 +86,12 @@ func (p *Pipe) Write(ctx context.Context, src usermem.IOSequence) (int64, error)
 	if n > 0 {
 		p.Notify(waiter.ReadableEvents)
 	}
+	if err == unix.EPIPE {
+		// If we are returning EPIPE send SIGPIPE to the task.
+		if sendSig := linux.SignalNoInfoFuncFromContext(ctx); sendSig != nil {
+			sendSig(linux.SIGPIPE)
+		}
+	}
 	return n, err
 }
 

pkg/sentry/kernel/task_context.go

@@ -17,6 +17,7 @@ package kernel
 import (
 	"time"
 
+	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/fs"
@@ -113,6 +114,10 @@ func (t *Task) contextValue(key interface{}, isTaskGoroutine bool) interface{} {
 		return t.k.RealtimeClock()
 	case limits.CtxLimits:
 		return t.tg.limits
+	case linux.CtxSignalNoInfoFunc:
+		return func(sig linux.Signal) error {
+			return t.SendSignal(SignalInfoNoInfo(sig, t, t))
+		}
 	case pgalloc.CtxMemoryFile:
 		return t.k.mf
 	case pgalloc.CtxMemoryFileProvider:

test/syscalls/linux/BUILD

@@ -1575,6 +1575,7 @@ cc_binary(
         "@com_google_absl//absl/time",
         gtest,
         "//test/util:posix_error",
+        "//test/util:signal_util",
         "//test/util:temp_path",
         "//test/util:test_main",
         "//test/util:test_util",

test/syscalls/linux/pipe.cc

@@ -14,6 +14,7 @@
 
 #include <fcntl.h> /* Obtain O_* constant definitions */
 #include <linux/magic.h>
+#include <signal.h>
 #include <sys/ioctl.h>
 #include <sys/statfs.h>
 #include <sys/uio.h>
@@ -29,6 +30,7 @@
 #include "test/util/file_descriptor.h"
 #include "test/util/fs_util.h"
 #include "test/util/posix_error.h"
+#include "test/util/signal_util.h"
 #include "test/util/temp_path.h"
 #include "test/util/test_util.h"
 #include "test/util/thread_util.h"
@@ -44,6 +46,28 @@ constexpr int kTestValue = 0x12345678;
 // Used for synchronization in race tests.
 const absl::Duration syncDelay = absl::Seconds(2);
 
+std::atomic<int> global_num_signals_received = 0;
+void SigRecordingHandler(int signum, siginfo_t* siginfo,
+                         void* unused_ucontext) {
+  global_num_signals_received++;
+}
+
+PosixErrorOr<Cleanup> RegisterSignalHandler(int signum) {
+  struct sigaction handler;
+  handler.sa_sigaction = SigRecordingHandler;
+  sigemptyset(&handler.sa_mask);
+  handler.sa_flags = SA_SIGINFO;
+  return ScopedSigaction(signum, handler);
+}
+
+void WaitForSignalDelivery(absl::Duration timeout, int max_expected) {
+  absl::Time wait_start = absl::Now();
+  while (global_num_signals_received < max_expected &&
+         absl::Now() - wait_start < timeout) {
+    absl::SleepFor(absl::Milliseconds(10));
+  }
+}
+
 struct PipeCreator {
   std::string name_;
 
@@ -333,10 +357,16 @@ TEST_P(PipeTest, WriterSideClosesReadDataFirst) {
 TEST_P(PipeTest, ReaderSideCloses) {
   SKIP_IF(!CreateBlocking());
 
+  const auto signal_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(RegisterSignalHandler(SIGPIPE));
+
   ASSERT_THAT(close(rfd_.release()), SyscallSucceeds());
   int buf = kTestValue;
   EXPECT_THAT(write(wfd_.get(), &buf, sizeof(buf)),
               SyscallFailsWithErrno(EPIPE));
+
+  WaitForSignalDelivery(absl::Seconds(1), 1);
+  ASSERT_EQ(global_num_signals_received, 1);
 }
 
 TEST_P(PipeTest, CloseTwice) {
@@ -355,6 +385,9 @@ TEST_P(PipeTest, CloseTwice) {
 TEST_P(PipeTest, BlockWriteClosed) {
   SKIP_IF(!CreateBlocking());
 
+  const auto signal_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(RegisterSignalHandler(SIGPIPE));
+
   absl::Notification notify;
   ScopedThread t([this, &notify]() {
     std::vector<char> buf(Size());
@@ -371,6 +404,10 @@ TEST_P(PipeTest, BlockWriteClosed) {
 
   notify.WaitForNotification();
   ASSERT_THAT(close(rfd_.release()), SyscallSucceeds());
+
+  WaitForSignalDelivery(absl::Seconds(1), 1);
+  ASSERT_EQ(global_num_signals_received, 1);
+
   t.Join();
 }
 
@@ -379,6 +416,9 @@ TEST_P(PipeTest, BlockWriteClosed) {
 TEST_P(PipeTest, BlockPartialWriteClosed) {
   SKIP_IF(!CreateBlocking());
 
+  const auto signal_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(RegisterSignalHandler(SIGPIPE));
+
   ScopedThread t([this]() {
     const int pipe_size = Size();
     std::vector<char> buf(2 * pipe_size);
@@ -396,6 +436,10 @@ TEST_P(PipeTest, BlockPartialWriteClosed) {
 
   // Unblock the above.
   ASSERT_THAT(close(rfd_.release()), SyscallSucceeds());
+
+  WaitForSignalDelivery(absl::Seconds(1), 2);
+  ASSERT_EQ(global_num_signals_received, 2);
+
   t.Join();
 }