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Implement sysfs.
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PiperOrigin-RevId: 290822487
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@mrahatm @gvisor-bot
mrahatm authored and gvisor-bot committed Jan 21, 2020
1 parent dc99897 commit ad1968e
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Showing 11 changed files with 519 additions and 171 deletions.
13 changes: 13 additions & 0 deletions pkg/abi/linux/file.go
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,19 @@ const (
DT_WHT = 14
)

// DirentType are the friendly strings for linux_dirent64.d_type.
var DirentType = abi.ValueSet{
DT_UNKNOWN: "DT_UNKNOWN",
DT_FIFO: "DT_FIFO",
DT_CHR: "DT_CHR",
DT_DIR: "DT_DIR",
DT_BLK: "DT_BLK",
DT_REG: "DT_REG",
DT_LNK: "DT_LNK",
DT_SOCK: "DT_SOCK",
DT_WHT: "DT_WHT",
}

// Values for preadv2/pwritev2.
const (
// Note: gVisor does not implement the RWF_HIPRI feature, but the flag is
Expand Down
3 changes: 1 addition & 2 deletions pkg/sentry/fsimpl/kernfs/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -51,13 +51,12 @@ go_test(
deps = [
":kernfs",
"//pkg/abi/linux",
"//pkg/fspath",
"//pkg/sentry/context",
"//pkg/sentry/context/contexttest",
"//pkg/sentry/fsimpl/testutil",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/usermem",
"//pkg/sentry/vfs",
"//pkg/sync",
"//pkg/syserror",
"@com_github_google_go-cmp//cmp:go_default_library",
],
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175 changes: 29 additions & 146 deletions pkg/sentry/fsimpl/kernfs/kernfs_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -17,20 +17,17 @@ package kernfs_test
import (
"bytes"
"fmt"
"io"
"runtime"
"testing"

"github.com/google/go-cmp/cmp"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/fspath"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/context/contexttest"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
"gvisor.dev/gvisor/pkg/sentry/fsimpl/testutil"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/syserror"
)

Expand All @@ -41,21 +38,11 @@ const staticFileContent = "This is sample content for a static test file."
// filesystem. See newTestSystem.
type RootDentryFn func(*auth.Credentials, *filesystem) *kernfs.Dentry

// TestSystem represents the context for a single test.
type TestSystem struct {
t *testing.T
ctx context.Context
creds *auth.Credentials
vfs *vfs.VirtualFilesystem
mns *vfs.MountNamespace
root vfs.VirtualDentry
}

// newTestSystem sets up a minimal environment for running a test, including an
// instance of a test filesystem. Tests can control the contents of the
// filesystem by providing an appropriate rootFn, which should return a
// pre-populated root dentry.
func newTestSystem(t *testing.T, rootFn RootDentryFn) *TestSystem {
func newTestSystem(t *testing.T, rootFn RootDentryFn) *testutil.System {
ctx := contexttest.Context(t)
creds := auth.CredentialsFromContext(ctx)
v := vfs.New()
Expand All @@ -66,57 +53,7 @@ func newTestSystem(t *testing.T, rootFn RootDentryFn) *TestSystem {
if err != nil {
t.Fatalf("Failed to create testfs root mount: %v", err)
}

s := &TestSystem{
t: t,
ctx: ctx,
creds: creds,
vfs: v,
mns: mns,
root: mns.Root(),
}
runtime.SetFinalizer(s, func(s *TestSystem) { s.root.DecRef() })
return s
}

// PathOpAtRoot constructs a vfs.PathOperation for a path from the
// root of the test filesystem.
//
// Precondition: path should be relative path.
func (s *TestSystem) PathOpAtRoot(path string) vfs.PathOperation {
return vfs.PathOperation{
Root: s.root,
Start: s.root,
Path: fspath.Parse(path),
}
}

// GetDentryOrDie attempts to resolve a dentry referred to by the
// provided path operation. If unsuccessful, the test fails.
func (s *TestSystem) GetDentryOrDie(pop vfs.PathOperation) vfs.VirtualDentry {
vd, err := s.vfs.GetDentryAt(s.ctx, s.creds, &pop, &vfs.GetDentryOptions{})
if err != nil {
s.t.Fatalf("GetDentryAt(pop:%+v) failed: %v", pop, err)
}
return vd
}

func (s *TestSystem) ReadToEnd(fd *vfs.FileDescription) (string, error) {
buf := make([]byte, usermem.PageSize)
bufIOSeq := usermem.BytesIOSequence(buf)
opts := vfs.ReadOptions{}

var content bytes.Buffer
for {
n, err := fd.Impl().Read(s.ctx, bufIOSeq, opts)
if n == 0 || err != nil {
if err == io.EOF {
err = nil
}
return content.String(), err
}
content.Write(buf[:n])
}
return testutil.NewSystem(ctx, t, v, mns)
}

type fsType struct {
Expand Down Expand Up @@ -260,6 +197,7 @@ func TestBasic(t *testing.T) {
"file1": fs.newFile(creds, staticFileContent),
})
})
defer sys.Destroy()
sys.GetDentryOrDie(sys.PathOpAtRoot("file1")).DecRef()
}

Expand All @@ -269,9 +207,10 @@ func TestMkdirGetDentry(t *testing.T) {
"dir1": fs.newDir(creds, 0755, nil),
})
})
defer sys.Destroy()

pop := sys.PathOpAtRoot("dir1/a new directory")
if err := sys.vfs.MkdirAt(sys.ctx, sys.creds, &pop, &vfs.MkdirOptions{Mode: 0755}); err != nil {
if err := sys.VFS.MkdirAt(sys.Ctx, sys.Creds, &pop, &vfs.MkdirOptions{Mode: 0755}); err != nil {
t.Fatalf("MkdirAt for PathOperation %+v failed: %v", pop, err)
}
sys.GetDentryOrDie(pop).DecRef()
Expand All @@ -283,20 +222,21 @@ func TestReadStaticFile(t *testing.T) {
"file1": fs.newFile(creds, staticFileContent),
})
})
defer sys.Destroy()

pop := sys.PathOpAtRoot("file1")
fd, err := sys.vfs.OpenAt(sys.ctx, sys.creds, &pop, &vfs.OpenOptions{})
fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, &pop, &vfs.OpenOptions{})
if err != nil {
sys.t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
}
defer fd.DecRef()

content, err := sys.ReadToEnd(fd)
if err != nil {
sys.t.Fatalf("Read failed: %v", err)
t.Fatalf("Read failed: %v", err)
}
if diff := cmp.Diff(staticFileContent, content); diff != "" {
sys.t.Fatalf("Read returned unexpected data:\n--- want\n+++ got\n%v", diff)
t.Fatalf("Read returned unexpected data:\n--- want\n+++ got\n%v", diff)
}
}

Expand All @@ -306,83 +246,44 @@ func TestCreateNewFileInStaticDir(t *testing.T) {
"dir1": fs.newDir(creds, 0755, nil),
})
})
defer sys.Destroy()

pop := sys.PathOpAtRoot("dir1/newfile")
opts := &vfs.OpenOptions{Flags: linux.O_CREAT | linux.O_EXCL, Mode: defaultMode}
fd, err := sys.vfs.OpenAt(sys.ctx, sys.creds, &pop, opts)
fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, &pop, opts)
if err != nil {
sys.t.Fatalf("OpenAt(pop:%+v, opts:%+v) failed: %v", pop, opts, err)
t.Fatalf("OpenAt(pop:%+v, opts:%+v) failed: %v", pop, opts, err)
}

// Close the file. The file should persist.
fd.DecRef()

fd, err = sys.vfs.OpenAt(sys.ctx, sys.creds, &pop, &vfs.OpenOptions{})
fd, err = sys.VFS.OpenAt(sys.Ctx, sys.Creds, &pop, &vfs.OpenOptions{})
if err != nil {
sys.t.Fatalf("OpenAt(pop:%+v) = %+v failed: %v", pop, fd, err)
t.Fatalf("OpenAt(pop:%+v) = %+v failed: %v", pop, fd, err)
}
fd.DecRef()
}

// direntCollector provides an implementation for vfs.IterDirentsCallback for
// testing. It simply iterates to the end of a given directory FD and collects
// all dirents emitted by the callback.
type direntCollector struct {
mu sync.Mutex
dirents map[string]vfs.Dirent
}

// Handle implements vfs.IterDirentsCallback.Handle.
func (d *direntCollector) Handle(dirent vfs.Dirent) bool {
d.mu.Lock()
if d.dirents == nil {
d.dirents = make(map[string]vfs.Dirent)
}
d.dirents[dirent.Name] = dirent
d.mu.Unlock()
return true
}

// count returns the number of dirents currently in the collector.
func (d *direntCollector) count() int {
d.mu.Lock()
defer d.mu.Unlock()
return len(d.dirents)
}

// contains checks whether the collector has a dirent with the given name and
// type.
func (d *direntCollector) contains(name string, typ uint8) error {
d.mu.Lock()
defer d.mu.Unlock()
dirent, ok := d.dirents[name]
if !ok {
return fmt.Errorf("No dirent named %q found", name)
}
if dirent.Type != typ {
return fmt.Errorf("Dirent named %q found, but was expecting type %d, got: %+v", name, typ, dirent)
}
return nil
}

func TestDirFDReadWrite(t *testing.T) {
sys := newTestSystem(t, func(creds *auth.Credentials, fs *filesystem) *kernfs.Dentry {
return fs.newReadonlyDir(creds, 0755, nil)
})
defer sys.Destroy()

pop := sys.PathOpAtRoot("/")
fd, err := sys.vfs.OpenAt(sys.ctx, sys.creds, &pop, &vfs.OpenOptions{})
fd, err := sys.VFS.OpenAt(sys.Ctx, sys.Creds, &pop, &vfs.OpenOptions{})
if err != nil {
sys.t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
}
defer fd.DecRef()

// Read/Write should fail for directory FDs.
if _, err := fd.Read(sys.ctx, usermem.BytesIOSequence([]byte{}), vfs.ReadOptions{}); err != syserror.EISDIR {
sys.t.Fatalf("Read for directory FD failed with unexpected error: %v", err)
if _, err := fd.Read(sys.Ctx, usermem.BytesIOSequence([]byte{}), vfs.ReadOptions{}); err != syserror.EISDIR {
t.Fatalf("Read for directory FD failed with unexpected error: %v", err)
}
if _, err := fd.Write(sys.ctx, usermem.BytesIOSequence([]byte{}), vfs.WriteOptions{}); err != syserror.EISDIR {
sys.t.Fatalf("Wrire for directory FD failed with unexpected error: %v", err)
if _, err := fd.Write(sys.Ctx, usermem.BytesIOSequence([]byte{}), vfs.WriteOptions{}); err != syserror.EISDIR {
t.Fatalf("Write for directory FD failed with unexpected error: %v", err)
}
}

Expand All @@ -397,30 +298,12 @@ func TestDirFDIterDirents(t *testing.T) {
"file1": fs.newFile(creds, staticFileContent),
})
})
defer sys.Destroy()

pop := sys.PathOpAtRoot("/")
fd, err := sys.vfs.OpenAt(sys.ctx, sys.creds, &pop, &vfs.OpenOptions{})
if err != nil {
sys.t.Fatalf("OpenAt for PathOperation %+v failed: %v", pop, err)
}
defer fd.DecRef()

collector := &direntCollector{}
if err := fd.IterDirents(sys.ctx, collector); err != nil {
sys.t.Fatalf("IterDirent failed: %v", err)
}

// Root directory should contain ".", ".." and 3 children:
if collector.count() != 5 {
sys.t.Fatalf("IterDirent returned too many dirents")
}
for _, dirName := range []string{".", "..", "dir1", "dir2"} {
if err := collector.contains(dirName, linux.DT_DIR); err != nil {
sys.t.Fatalf("IterDirent had unexpected results: %v", err)
}
}
if err := collector.contains("file1", linux.DT_REG); err != nil {
sys.t.Fatalf("IterDirent had unexpected results: %v", err)
}

sys.AssertDirectoryContains(&pop, map[string]testutil.DirentType{
"dir1": linux.DT_DIR,
"dir2": linux.DT_DIR,
"file1": linux.DT_REG,
})
}
13 changes: 1 addition & 12 deletions pkg/sentry/fsimpl/proc/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -44,30 +44,19 @@ go_test(
name = "proc_test",
size = "small",
srcs = [
"boot_test.go",
"tasks_sys_test.go",
"tasks_test.go",
],
embed = [":proc"],
deps = [
"//pkg/abi/linux",
"//pkg/cpuid",
"//pkg/fspath",
"//pkg/memutil",
"//pkg/sentry/context",
"//pkg/sentry/context/contexttest",
"//pkg/sentry/fs",
"//pkg/sentry/fsimpl/testutil",
"//pkg/sentry/inet",
"//pkg/sentry/kernel",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/kernel/sched",
"//pkg/sentry/limits",
"//pkg/sentry/loader",
"//pkg/sentry/pgalloc",
"//pkg/sentry/platform",
"//pkg/sentry/platform/kvm",
"//pkg/sentry/platform/ptrace",
"//pkg/sentry/time",
"//pkg/sentry/usermem",
"//pkg/sentry/vfs",
"//pkg/syserror",
Expand Down
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