diff options
| -rw-r--r-- | runsc/boot/BUILD | 1 | ||||
| -rw-r--r-- | runsc/boot/loader.go | 32 | ||||
| -rw-r--r-- | runsc/boot/user.go | 28 | ||||
| -rw-r--r-- | runsc/boot/user_test.go | 3 | ||||
| -rw-r--r-- | runsc/cmd/exec.go | 1 | ||||
| -rw-r--r-- | runsc/dockerutil/dockerutil.go | 8 | ||||
| -rw-r--r-- | test/e2e/exec_test.go | 42 |
7 files changed, 95 insertions, 20 deletions
diff --git a/runsc/boot/BUILD b/runsc/boot/BUILD index 588bb8851..54d1ab129 100644 --- a/runsc/boot/BUILD +++ b/runsc/boot/BUILD @@ -109,6 +109,7 @@ go_test( "//pkg/sentry/arch:registers_go_proto", "//pkg/sentry/context/contexttest", "//pkg/sentry/fs", + "//pkg/sentry/kernel/auth", "//pkg/unet", "//runsc/fsgofer", "@com_github_opencontainers_runtime-spec//specs-go:go_default_library", diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go index 823a34619..d824d7dc5 100644 --- a/runsc/boot/loader.go +++ b/runsc/boot/loader.go @@ -20,7 +20,6 @@ import ( mrand "math/rand" "os" "runtime" - "strings" "sync" "sync/atomic" "syscall" @@ -535,23 +534,12 @@ func (l *Loader) run() error { return err } - // Read /etc/passwd for the user's HOME directory and set the HOME - // environment variable as required by POSIX if it is not overridden by - // the user. - hasHomeEnvv := false - for _, envv := range l.rootProcArgs.Envv { - if strings.HasPrefix(envv, "HOME=") { - hasHomeEnvv = true - } - } - if !hasHomeEnvv { - homeDir, err := getExecUserHome(ctx, l.rootProcArgs.MountNamespace, uint32(l.rootProcArgs.Credentials.RealKUID)) - if err != nil { - return fmt.Errorf("error reading exec user: %v", err) - } - - l.rootProcArgs.Envv = append(l.rootProcArgs.Envv, "HOME="+homeDir) + // Add the HOME enviroment variable if it is not already set. + envv, err := maybeAddExecUserHome(ctx, l.rootProcArgs.MountNamespace, l.rootProcArgs.Credentials.RealKUID, l.rootProcArgs.Envv) + if err != nil { + return err } + l.rootProcArgs.Envv = envv // Create the root container init task. It will begin running // when the kernel is started. @@ -815,6 +803,16 @@ func (l *Loader) executeAsync(args *control.ExecArgs) (kernel.ThreadID, error) { }) defer args.MountNamespace.DecRef() + // Add the HOME enviroment varible if it is not already set. + root := args.MountNamespace.Root() + defer root.DecRef() + ctx := fs.WithRoot(l.k.SupervisorContext(), root) + envv, err := maybeAddExecUserHome(ctx, args.MountNamespace, args.KUID, args.Envv) + if err != nil { + return 0, err + } + args.Envv = envv + // Start the process. proc := control.Proc{Kernel: l.k} args.PIDNamespace = tg.PIDNamespace() diff --git a/runsc/boot/user.go b/runsc/boot/user.go index d1d423a5c..56cc12ee0 100644 --- a/runsc/boot/user.go +++ b/runsc/boot/user.go @@ -16,6 +16,7 @@ package boot import ( "bufio" + "fmt" "io" "strconv" "strings" @@ -23,6 +24,7 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/sentry/context" "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/usermem" ) @@ -42,7 +44,7 @@ func (r *fileReader) Read(buf []byte) (int, error) { // getExecUserHome returns the home directory of the executing user read from // /etc/passwd as read from the container filesystem. -func getExecUserHome(ctx context.Context, rootMns *fs.MountNamespace, uid uint32) (string, error) { +func getExecUserHome(ctx context.Context, rootMns *fs.MountNamespace, uid auth.KUID) (string, error) { // The default user home directory to return if no user matching the user // if found in the /etc/passwd found in the image. const defaultHome = "/" @@ -82,7 +84,7 @@ func getExecUserHome(ctx context.Context, rootMns *fs.MountNamespace, uid uint32 File: f, } - homeDir, err := findHomeInPasswd(uid, r, defaultHome) + homeDir, err := findHomeInPasswd(uint32(uid), r, defaultHome) if err != nil { return "", err } @@ -90,6 +92,28 @@ func getExecUserHome(ctx context.Context, rootMns *fs.MountNamespace, uid uint32 return homeDir, nil } +// maybeAddExecUserHome returns a new slice with the HOME enviroment variable +// set if the slice does not already contain it, otherwise it returns the +// original slice unmodified. +func maybeAddExecUserHome(ctx context.Context, mns *fs.MountNamespace, uid auth.KUID, envv []string) ([]string, error) { + // Check if the envv already contains HOME. + for _, env := range envv { + if strings.HasPrefix(env, "HOME=") { + // We have it. Return the original slice unmodified. + return envv, nil + } + } + + // Read /etc/passwd for the user's HOME directory and set the HOME + // environment variable as required by POSIX if it is not overridden by + // the user. + homeDir, err := getExecUserHome(ctx, mns, uid) + if err != nil { + return nil, fmt.Errorf("error reading exec user: %v", err) + } + return append(envv, "HOME="+homeDir), nil +} + // findHomeInPasswd parses a passwd file and returns the given user's home // directory. This function does it's best to replicate the runc's behavior. func findHomeInPasswd(uid uint32, passwd io.Reader, defaultHome string) (string, error) { diff --git a/runsc/boot/user_test.go b/runsc/boot/user_test.go index 906baf3e5..9aee2ad07 100644 --- a/runsc/boot/user_test.go +++ b/runsc/boot/user_test.go @@ -25,6 +25,7 @@ import ( specs "github.com/opencontainers/runtime-spec/specs-go" "gvisor.dev/gvisor/pkg/sentry/context/contexttest" "gvisor.dev/gvisor/pkg/sentry/fs" + "gvisor.dev/gvisor/pkg/sentry/kernel/auth" ) func setupTempDir() (string, error) { @@ -68,7 +69,7 @@ func setupPasswd(contents string, perms os.FileMode) func() (string, error) { // TestGetExecUserHome tests the getExecUserHome function. func TestGetExecUserHome(t *testing.T) { tests := map[string]struct { - uid uint32 + uid auth.KUID createRoot func() (string, error) expected string }{ diff --git a/runsc/cmd/exec.go b/runsc/cmd/exec.go index e817eff77..bf1225e1c 100644 --- a/runsc/cmd/exec.go +++ b/runsc/cmd/exec.go @@ -127,6 +127,7 @@ func (ex *Exec) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) Fatalf("getting environment variables: %v", err) } } + if e.Capabilities == nil { // enableRaw is set to true to prevent the filtering out of // CAP_NET_RAW. This is the opposite of Create() because exec diff --git a/runsc/dockerutil/dockerutil.go b/runsc/dockerutil/dockerutil.go index c073d8f75..e37ec0ffd 100644 --- a/runsc/dockerutil/dockerutil.go +++ b/runsc/dockerutil/dockerutil.go @@ -287,6 +287,14 @@ func (d *Docker) Exec(args ...string) (string, error) { return do(a...) } +// ExecAsUser calls 'docker exec' as the given user with the arguments +// provided. +func (d *Docker) ExecAsUser(user string, args ...string) (string, error) { + a := []string{"exec", "--user", user, d.Name} + a = append(a, args...) + return do(a...) +} + // ExecWithTerminal calls 'docker exec -it' with the arguments provided and // attaches a pty to stdio. func (d *Docker) ExecWithTerminal(args ...string) (*exec.Cmd, *os.File, error) { diff --git a/test/e2e/exec_test.go b/test/e2e/exec_test.go index 267679268..7238c2afe 100644 --- a/test/e2e/exec_test.go +++ b/test/e2e/exec_test.go @@ -177,3 +177,45 @@ func TestExecEnv(t *testing.T) { t.Errorf("wanted exec output to contain %q, got %q", want, got) } } + +// Test that exec always has HOME environment set, even when not set in run. +func TestExecEnvHasHome(t *testing.T) { + // Base alpine image does not have any environment variables set. + if err := dockerutil.Pull("alpine"); err != nil { + t.Fatalf("docker pull failed: %v", err) + } + d := dockerutil.MakeDocker("exec-env-test") + + // We will check that HOME is set for root user, and also for a new + // non-root user we will create. + newUID := 1234 + newHome := "/foo/bar" + + // Create a new user with a home directory, and then sleep. + script := fmt.Sprintf(` + mkdir -p -m 777 %s && \ + adduser foo -D -u %d -h %s && \ + sleep 1000`, newHome, newUID, newHome) + if err := d.Run("alpine", "/bin/sh", "-c", script); err != nil { + t.Fatalf("docker run failed: %v", err) + } + defer d.CleanUp() + + // Exec "echo $HOME", and expect to see "/root". + got, err := d.Exec("/bin/sh", "-c", "echo $HOME") + if err != nil { + t.Fatalf("docker exec failed: %v", err) + } + if want := "/root"; !strings.Contains(got, want) { + t.Errorf("wanted exec output to contain %q, got %q", want, got) + } + + // Execute the same as uid 123 and expect newHome. + got, err = d.ExecAsUser(strconv.Itoa(newUID), "/bin/sh", "-c", "echo $HOME") + if err != nil { + t.Fatalf("docker exec failed: %v", err) + } + if want := newHome; !strings.Contains(got, want) { + t.Errorf("wanted exec output to contain %q, got %q", want, got) + } +} |