From f2e4b5ab932a3816e4957171b303db645fd04a94 Mon Sep 17 00:00:00 2001 From: Fabricio Voznika Date: Thu, 12 Mar 2020 12:31:16 -0700 Subject: Kill sandbox process when parent process terminates When the sandbox runs in attached more, e.g. runsc do, runsc run, the sandbox lifetime is controlled by the parent process. This wasn't working in all cases because PR_GET_PDEATHSIG doesn't propagate through execve when the process changes uid/gid. So it was getting dropped when the sandbox execve's to change to user nobody. PiperOrigin-RevId: 300601247 --- test/root/BUILD | 3 + test/root/runsc_test.go | 146 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 149 insertions(+) create mode 100644 test/root/runsc_test.go (limited to 'test') diff --git a/test/root/BUILD b/test/root/BUILD index 23ce2a70f..ddc9b4955 100644 --- a/test/root/BUILD +++ b/test/root/BUILD @@ -16,6 +16,7 @@ go_test( "crictl_test.go", "main_test.go", "oom_score_adj_test.go", + "runsc_test.go", ], data = [ "//runsc", @@ -37,7 +38,9 @@ go_test( "//runsc/specutils", "//runsc/testutil", "//test/root/testdata", + "@com_github_cenkalti_backoff//:go_default_library", "@com_github_opencontainers_runtime-spec//specs-go:go_default_library", "@com_github_syndtr_gocapability//capability:go_default_library", + "@org_golang_x_sys//unix:go_default_library", ], ) diff --git a/test/root/runsc_test.go b/test/root/runsc_test.go new file mode 100644 index 000000000..28bb60a12 --- /dev/null +++ b/test/root/runsc_test.go @@ -0,0 +1,146 @@ +// Copyright 2020 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 root + +import ( + "bytes" + "fmt" + "io/ioutil" + "os/exec" + "path/filepath" + "strconv" + "strings" + "testing" + "time" + + "github.com/cenkalti/backoff" + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/runsc/specutils" + "gvisor.dev/gvisor/runsc/testutil" +) + +// TestDoKill checks that when "runsc do..." is killed, the sandbox process is +// also terminated. This ensures that parent death signal is propagate to the +// sandbox process correctly. +func TestDoKill(t *testing.T) { + // Make the sandbox process be reparented here when it's killed, so we can + // wait for it. + if err := unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0); err != nil { + t.Fatalf("prctl(PR_SET_CHILD_SUBREAPER): %v", err) + } + + cmd := exec.Command(specutils.ExePath, "do", "sleep", "10000") + buf := &bytes.Buffer{} + cmd.Stdout = buf + cmd.Stderr = buf + cmd.Start() + + var pid int + findSandbox := func() error { + var err error + pid, err = sandboxPid(cmd.Process.Pid) + if err != nil { + return &backoff.PermanentError{Err: err} + } + if pid == 0 { + return fmt.Errorf("sandbox process not found") + } + return nil + } + if err := testutil.Poll(findSandbox, 10*time.Second); err != nil { + t.Fatalf("failed to find sandbox: %v", err) + } + t.Logf("Found sandbox, pid: %d", pid) + + if err := cmd.Process.Kill(); err != nil { + t.Fatalf("failed to kill run process: %v", err) + } + cmd.Wait() + t.Logf("Parent process killed (%d). Output: %s", cmd.Process.Pid, buf.String()) + + ch := make(chan struct{}) + go func() { + defer func() { ch <- struct{}{} }() + t.Logf("Waiting for sandbox process (%d) termination", pid) + if _, err := unix.Wait4(pid, nil, 0, nil); err != nil { + t.Errorf("error waiting for sandbox process (%d): %v", pid, err) + } + }() + select { + case <-ch: + // Done + case <-time.After(5 * time.Second): + t.Fatalf("timeout waiting for sandbox process (%d) to exit", pid) + } +} + +// sandboxPid looks for the sandbox process inside the process tree starting +// from "pid". It returns 0 and no error if no sandbox process is found. It +// returns error if anything failed. +func sandboxPid(pid int) (int, error) { + cmd := exec.Command("pgrep", "-P", strconv.Itoa(pid)) + buf := &bytes.Buffer{} + cmd.Stdout = buf + if err := cmd.Start(); err != nil { + return 0, err + } + ps, err := cmd.Process.Wait() + if err != nil { + return 0, err + } + if ps.ExitCode() == 1 { + // pgrep returns 1 when no process is found. + return 0, nil + } + + var children []int + for _, line := range strings.Split(buf.String(), "\n") { + if len(line) == 0 { + continue + } + child, err := strconv.Atoi(line) + if err != nil { + return 0, err + } + + cmdline, err := ioutil.ReadFile(filepath.Join("/proc", line, "cmdline")) + if err != nil { + return 0, err + } + args := strings.SplitN(string(cmdline), "\x00", 2) + if len(args) == 0 { + return 0, fmt.Errorf("malformed cmdline file: %q", cmdline) + } + // The sandbox process has the first argument set to "runsc-sandbox". + if args[0] == "runsc-sandbox" { + return child, nil + } + + children = append(children, child) + } + + // Sandbox process wasn't found, try another level down. + for _, pid := range children { + sand, err := sandboxPid(pid) + if err != nil { + return 0, err + } + if sand != 0 { + return sand, nil + } + // Not found, continue the search. + } + return 0, nil +} -- cgit v1.2.3