gvisor/test/e2e/integration_test.go

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// Copyright 2018 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 integration provides end-to-end integration tests for runsc.
//
// Each test calls docker commands to start up a container, and tests that it is
// behaving properly, with various runsc commands. The container is killed and
// deleted at the end.
//
// Setup instruction in test/README.md.
package integration
import (
"context"
"flag"
"fmt"
"io/ioutil"
"net"
"net/http"
"os"
"path/filepath"
"strconv"
"strings"
"testing"
"time"
"github.com/docker/docker/api/types/mount"
"gvisor.dev/gvisor/pkg/test/dockerutil"
"gvisor.dev/gvisor/pkg/test/testutil"
)
// defaultWait is the default wait time used for tests.
const defaultWait = time.Minute
// httpRequestSucceeds sends a request to a given url and checks that the status is OK.
func httpRequestSucceeds(client http.Client, server string, port int) error {
url := fmt.Sprintf("http://%s:%d", server, port)
// Ensure that content is being served.
resp, err := client.Get(url)
if err != nil {
return fmt.Errorf("error reaching http server: %v", err)
}
if want := http.StatusOK; resp.StatusCode != want {
return fmt.Errorf("wrong response code, got: %d, want: %d", resp.StatusCode, want)
}
return nil
}
// TestLifeCycle tests a basic Create/Start/Stop docker container life cycle.
func TestLifeCycle(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Start the container.
if err := d.Create(ctx, dockerutil.RunOpts{
Image: "basic/nginx",
Ports: []int{80},
}); err != nil {
t.Fatalf("docker create failed: %v", err)
}
if err := d.Start(ctx); err != nil {
t.Fatalf("docker start failed: %v", err)
}
// Test that container is working.
port, err := d.FindPort(ctx, 80)
if err != nil {
t.Fatalf("docker.FindPort(80) failed: %v", err)
}
if err := testutil.WaitForHTTP(port, defaultWait); err != nil {
t.Fatalf("WaitForHTTP() timeout: %v", err)
}
client := http.Client{Timeout: defaultWait}
if err := httpRequestSucceeds(client, "localhost", port); err != nil {
t.Errorf("http request failed: %v", err)
}
if err := d.Stop(ctx); err != nil {
t.Fatalf("docker stop failed: %v", err)
}
if err := d.Remove(ctx); err != nil {
t.Fatalf("docker rm failed: %v", err)
}
}
func TestPauseResume(t *testing.T) {
if !testutil.IsCheckpointSupported() {
t.Skip("Checkpoint is not supported.")
}
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Start the container.
if err := d.Spawn(ctx, dockerutil.RunOpts{
Image: "basic/python",
Ports: []int{8080}, // See Dockerfile.
}); err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Find where port 8080 is mapped to.
port, err := d.FindPort(ctx, 8080)
if err != nil {
t.Fatalf("docker.FindPort(8080) failed: %v", err)
}
// Wait until it's up and running.
if err := testutil.WaitForHTTP(port, defaultWait); err != nil {
t.Fatalf("WaitForHTTP() timeout: %v", err)
}
// Check that container is working.
client := http.Client{Timeout: defaultWait}
if err := httpRequestSucceeds(client, "localhost", port); err != nil {
t.Error("http request failed:", err)
}
if err := d.Pause(ctx); err != nil {
t.Fatalf("docker pause failed: %v", err)
}
// Check if container is paused.
client = http.Client{Timeout: 10 * time.Millisecond} // Don't wait a minute.
switch _, err := client.Get(fmt.Sprintf("http://localhost:%d", port)); v := err.(type) {
case nil:
t.Errorf("http req expected to fail but it succeeded")
case net.Error:
if !v.Timeout() {
t.Errorf("http req got error %v, wanted timeout", v)
}
default:
t.Errorf("http req got unexpected error %v", v)
}
if err := d.Unpause(ctx); err != nil {
t.Fatalf("docker unpause failed: %v", err)
}
// Wait until it's up and running.
if err := testutil.WaitForHTTP(port, defaultWait); err != nil {
t.Fatalf("WaitForHTTP() timeout: %v", err)
}
// Check if container is working again.
client = http.Client{Timeout: defaultWait}
if err := httpRequestSucceeds(client, "localhost", port); err != nil {
t.Error("http request failed:", err)
}
}
func TestCheckpointRestore(t *testing.T) {
if !testutil.IsCheckpointSupported() {
t.Skip("Pause/resume is not supported.")
}
// TODO(gvisor.dev/issue/3373): Remove after implementing.
if usingVFS2, err := dockerutil.UsingVFS2(); err != nil {
t.Fatalf("failed to read config for runtime %s: %v", dockerutil.Runtime(), err)
} else if usingVFS2 {
t.Skip("CheckpointRestore not implemented in VFS2.")
}
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Start the container.
if err := d.Spawn(ctx, dockerutil.RunOpts{
Image: "basic/python",
Ports: []int{8080}, // See Dockerfile.
}); err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Create a snapshot.
if err := d.Checkpoint(ctx, "test"); err != nil {
t.Fatalf("docker checkpoint failed: %v", err)
}
if err := d.WaitTimeout(ctx, defaultWait); err != nil {
t.Fatalf("wait failed: %v", err)
}
// TODO(b/143498576): Remove Poll after github.com/moby/moby/issues/38963 is fixed.
if err := testutil.Poll(func() error { return d.Restore(ctx, "test") }, defaultWait); err != nil {
t.Fatalf("docker restore failed: %v", err)
}
// Find where port 8080 is mapped to.
port, err := d.FindPort(ctx, 8080)
if err != nil {
t.Fatalf("docker.FindPort(8080) failed: %v", err)
}
// Wait until it's up and running.
if err := testutil.WaitForHTTP(port, defaultWait); err != nil {
t.Fatalf("WaitForHTTP() timeout: %v", err)
}
// Check if container is working again.
client := http.Client{Timeout: defaultWait}
if err := httpRequestSucceeds(client, "localhost", port); err != nil {
t.Error("http request failed:", err)
}
}
// Create client and server that talk to each other using the local IP.
func TestConnectToSelf(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Creates server that replies "server" and exists. Sleeps at the end because
// 'docker exec' gets killed if the init process exists before it can finish.
if err := d.Spawn(ctx, dockerutil.RunOpts{
Image: "basic/ubuntu",
}, "/bin/sh", "-c", "echo server | nc -l -p 8080 && sleep 1"); err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Finds IP address for host.
ip, err := d.Exec(ctx, dockerutil.ExecOpts{}, "/bin/sh", "-c", "cat /etc/hosts | grep ${HOSTNAME} | awk '{print $1}'")
if err != nil {
t.Fatalf("docker exec failed: %v", err)
}
ip = strings.TrimRight(ip, "\n")
// Runs client that sends "client" to the server and exits.
reply, err := d.Exec(ctx, dockerutil.ExecOpts{}, "/bin/sh", "-c", fmt.Sprintf("echo client | nc %s 8080", ip))
if err != nil {
t.Fatalf("docker exec failed: %v", err)
}
// Ensure both client and server got the message from each other.
if want := "server\n"; reply != want {
t.Errorf("Error on server, want: %q, got: %q", want, reply)
}
if _, err := d.WaitForOutput(ctx, "^client\n$", defaultWait); err != nil {
t.Fatalf("docker.WaitForOutput(client) timeout: %v", err)
}
}
func TestMemLimit(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// N.B. Because the size of the memory file may grow in large chunks,
// there is a minimum threshold of 1GB for the MemTotal figure.
allocMemory := 1024 * 1024 // In kb.
out, err := d.Run(ctx, dockerutil.RunOpts{
Image: "basic/alpine",
Memory: allocMemory * 1024, // In bytes.
}, "sh", "-c", "cat /proc/meminfo | grep MemTotal: | awk '{print $2}'")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Remove warning message that swap isn't present.
if strings.HasPrefix(out, "WARNING") {
lines := strings.Split(out, "\n")
if len(lines) != 3 {
t.Fatalf("invalid output: %s", out)
}
out = lines[1]
}
// Ensure the memory matches what we want.
got, err := strconv.ParseUint(strings.TrimSpace(out), 10, 64)
if err != nil {
t.Fatalf("failed to parse %q: %v", out, err)
}
if want := uint64(allocMemory); got != want {
t.Errorf("MemTotal got: %d, want: %d", got, want)
}
}
func TestNumCPU(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Read how many cores are in the container.
out, err := d.Run(ctx, dockerutil.RunOpts{
Image: "basic/alpine",
CpusetCpus: "0",
}, "sh", "-c", "cat /proc/cpuinfo | grep 'processor.*:' | wc -l")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Ensure it matches what we want.
got, err := strconv.Atoi(strings.TrimSpace(out))
if err != nil {
t.Fatalf("failed to parse %q: %v", out, err)
}
if want := 1; got != want {
t.Errorf("MemTotal got: %d, want: %d", got, want)
}
}
// TestJobControl tests that job control characters are handled properly.
func TestJobControl(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
// Start the container with an attached PTY.
p, err := d.SpawnProcess(ctx, dockerutil.RunOpts{
Image: "basic/alpine",
}, "sh", "-c", "sleep 100 | cat")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
// Give shell a few seconds to start executing the sleep.
time.Sleep(2 * time.Second)
if _, err := p.Write(time.Second, []byte{0x03}); err != nil {
t.Fatalf("error exit: %v", err)
}
if err := d.WaitTimeout(ctx, 3*time.Second); err != nil {
t.Fatalf("WaitTimeout failed: %v", err)
}
want := 130
got, err := p.WaitExitStatus(ctx)
if err != nil {
t.Fatalf("wait for exit failed with: %v", err)
} else if got != want {
t.Fatalf("got: %d want: %d", got, want)
}
}
// TestWorkingDirCreation checks that working dir is created if it doesn't exit.
func TestWorkingDirCreation(t *testing.T) {
for _, tc := range []struct {
name string
workingDir string
}{
{name: "root", workingDir: "/foo"},
{name: "tmp", workingDir: "/tmp/foo"},
} {
for _, readonly := range []bool{true, false} {
name := tc.name
if readonly {
name += "-readonly"
}
t.Run(name, func(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
opts := dockerutil.RunOpts{
Image: "basic/alpine",
WorkDir: tc.workingDir,
ReadOnly: readonly,
}
got, err := d.Run(ctx, opts, "sh", "-c", "echo ${PWD}")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
if want := tc.workingDir + "\n"; want != got {
t.Errorf("invalid working dir, want: %q, got: %q", want, got)
}
})
}
}
}
// TestTmpFile checks that files inside '/tmp' are not overridden.
func TestTmpFile(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
opts := dockerutil.RunOpts{Image: "basic/tmpfile"}
got, err := d.Run(ctx, opts, "cat", "/tmp/foo/file.txt")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
if want := "123\n"; want != got {
t.Errorf("invalid file content, want: %q, got: %q", want, got)
}
}
// TestTmpMount checks that mounts inside '/tmp' are not overridden.
func TestTmpMount(t *testing.T) {
ctx := context.Background()
dir, err := ioutil.TempDir(testutil.TmpDir(), "tmp-mount")
if err != nil {
t.Fatalf("TempDir(): %v", err)
}
want := "123"
if err := ioutil.WriteFile(filepath.Join(dir, "file.txt"), []byte("123"), 0666); err != nil {
t.Fatalf("WriteFile(): %v", err)
}
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
opts := dockerutil.RunOpts{
Image: "basic/alpine",
Mounts: []mount.Mount{
{
Type: mount.TypeBind,
Source: dir,
Target: "/tmp/foo",
},
},
}
got, err := d.Run(ctx, opts, "cat", "/tmp/foo/file.txt")
if err != nil {
t.Fatalf("docker run failed: %v", err)
}
if want != got {
t.Errorf("invalid file content, want: %q, got: %q", want, got)
}
}
Enable overlayfs_stale_read by default for runsc. Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-13 17:51:50 +00:00
// TestHostOverlayfsCopyUp tests that the --overlayfs-stale-read option causes
// runsc to hide the incoherence of FDs opened before and after overlayfs
// copy-up on the host.
func TestHostOverlayfsCopyUp(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
Enable overlayfs_stale_read by default for runsc. Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-13 17:51:50 +00:00
if got, err := d.Run(ctx, dockerutil.RunOpts{
Image: "basic/hostoverlaytest",
Enable overlayfs_stale_read by default for runsc. Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-13 17:51:50 +00:00
WorkDir: "/root",
}, "./test_copy_up"); err != nil {
t.Fatalf("docker run failed: %v", err)
} else if got != "" {
t.Errorf("test failed:\n%s", got)
}
}
// TestHostOverlayfsRewindDir tests that rewinddir() "causes the directory
// stream to refer to the current state of the corresponding directory, as a
// call to opendir() would have done" as required by POSIX, when the directory
// in question is host overlayfs.
//
// This test specifically targets host overlayfs because, per POSIX, "if a file
// is removed from or added to the directory after the most recent call to
// opendir() or rewinddir(), whether a subsequent call to readdir() returns an
// entry for that file is unspecified"; the host filesystems used by other
// automated tests yield newly-added files from readdir() even if the fsgofer
// does not explicitly rewinddir(), but overlayfs does not.
func TestHostOverlayfsRewindDir(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
if got, err := d.Run(ctx, dockerutil.RunOpts{
Image: "basic/hostoverlaytest",
WorkDir: "/root",
}, "./test_rewinddir"); err != nil {
Enable overlayfs_stale_read by default for runsc. Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-13 17:51:50 +00:00
t.Fatalf("docker run failed: %v", err)
} else if got != "" {
t.Errorf("test failed:\n%s", got)
Enable overlayfs_stale_read by default for runsc. Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-13 17:51:50 +00:00
}
}
// Basic test for linkat(2). Syscall tests requires CAP_DAC_READ_SEARCH and it
// cannot use tricks like userns as root. For this reason, run a basic link test
// to ensure some coverage.
func TestLink(t *testing.T) {
ctx := context.Background()
d := dockerutil.MakeContainer(ctx, t)
defer d.CleanUp(ctx)
if got, err := d.Run(ctx, dockerutil.RunOpts{
Image: "basic/linktest",
WorkDir: "/root",
}, "./link_test"); err != nil {
t.Fatalf("docker run failed: %v", err)
} else if got != "" {
t.Errorf("test failed:\n%s", got)
}
}
func TestMain(m *testing.M) {
dockerutil.EnsureSupportedDockerVersion()
flag.Parse()
os.Exit(m.Run())
}