| 1 | //go:build unix |
| 2 | |
| 3 | package host |
| 4 | |
| 5 | import ( |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | "os" |
| 10 | "os/exec" |
| 11 | "path/filepath" |
| 12 | "strconv" |
| 13 | |
| 14 | "github.com/carlosframework/platform/internal/registry" |
| 15 | ) |
| 16 | |
| 17 | const registryChildCommand = "__registry-child" |
| 18 | |
| 19 | func openRegistryChild(path string, uid, gid int) (*registry.Registry, error) { |
| 20 | return openRegistryChildMode(path, uid, gid, false) |
| 21 | } |
| 22 | |
| 23 | func openRegistryChildReadOnly(path string, uid, gid int) (*registry.Registry, error) { |
| 24 | return openRegistryChildMode(path, uid, gid, true) |
| 25 | } |
| 26 | |
| 27 | func openRegistryChildMode(path string, uid, gid int, readOnly bool) (*registry.Registry, error) { |
| 28 | if uid <= 0 || gid < 0 { |
| 29 | return nil, errors.New("registry: invalid service credentials") |
| 30 | } |
| 31 | path, err := filepath.Abs(path) |
| 32 | if err != nil { |
| 33 | return nil, err |
| 34 | } |
| 35 | return registry.OpenRemoteReconnect(path, func() (io.WriteCloser, io.ReadCloser, func() error, error) { |
| 36 | cmd, err := registryChildExec(path, uid, gid) |
| 37 | if err != nil { |
| 38 | return nil, nil, nil, err |
| 39 | } |
| 40 | if readOnly { |
| 41 | cmd.Args = append(cmd.Args, "read-only") |
| 42 | } |
| 43 | return registryChildPipes(cmd, uid, gid) |
| 44 | }) |
| 45 | } |
| 46 | |
| 47 | func startRegistryChild(cmd *exec.Cmd, path string, uid, gid int) (*registry.Registry, error) { |
| 48 | input, output, wait, err := registryChildPipes(cmd, uid, gid) |
| 49 | if err != nil { |
| 50 | return nil, err |
| 51 | } |
| 52 | return registry.OpenRemote(path, input, output, wait) |
| 53 | } |
| 54 | |
| 55 | func registryChildPipes(cmd *exec.Cmd, uid, gid int) (io.WriteCloser, io.ReadCloser, func() error, error) { |
| 56 | if uid <= 0 || gid < 0 { |
| 57 | return nil, nil, nil, errors.New("registry: invalid service credentials") |
| 58 | } |
| 59 | if err := registryChildCloseExec(); err != nil { |
| 60 | return nil, nil, nil, err |
| 61 | } |
| 62 | cmd.Env = []string{} |
| 63 | if value, ok := os.LookupEnv("CARLOS_HOST_CLAIM"); ok { |
| 64 | cmd.Env = append(cmd.Env, "CARLOS_HOST_CLAIM="+value) |
| 65 | } |
| 66 | cmd.Dir = "/" |
| 67 | cmd.SysProcAttr = nil |
| 68 | cmd.Stderr = os.Stderr |
| 69 | input, err := cmd.StdinPipe() |
| 70 | if err != nil { |
| 71 | return nil, nil, nil, err |
| 72 | } |
| 73 | output, err := cmd.StdoutPipe() |
| 74 | if err != nil { |
| 75 | input.Close() |
| 76 | return nil, nil, nil, err |
| 77 | } |
| 78 | if err = registryChildStart(cmd); err != nil { |
| 79 | input.Close() |
| 80 | output.Close() |
| 81 | return nil, nil, nil, err |
| 82 | } |
| 83 | return input, output, cmd.Wait, nil |
| 84 | } |
| 85 | |
| 86 | // RunRegistryChild is the private re-exec entry point, before CLI dispatch. |
| 87 | func RunRegistryChild(args []string) error { |
| 88 | if err := registryChildHarden(); err != nil { |
| 89 | return err |
| 90 | } |
| 91 | closeRegistryExecutable() |
| 92 | readOnly := len(args) == 4 && args[3] == "read-only" |
| 93 | if len(args) != 3 && !readOnly { |
| 94 | return errors.New("registry: invalid child arguments") |
| 95 | } |
| 96 | uid, err := strconv.Atoi(args[1]) |
| 97 | if err != nil { |
| 98 | return err |
| 99 | } |
| 100 | gid, err := strconv.Atoi(args[2]) |
| 101 | if err != nil { |
| 102 | return err |
| 103 | } |
| 104 | groups, err := os.Getgroups() |
| 105 | if err != nil { |
| 106 | return err |
| 107 | } |
| 108 | if uid <= 0 || os.Getuid() != uid || os.Geteuid() != uid || os.Getgid() != gid || os.Getegid() != gid || len(groups) != 0 { |
| 109 | return fmt.Errorf("registry: child credentials were not dropped") |
| 110 | } |
| 111 | if readOnly { |
| 112 | return registry.ServeRemoteReadOnly(args[0], os.Stdin, os.Stdout) |
| 113 | } |
| 114 | return registry.ServeRemote(args[0], os.Stdin, os.Stdout) |
| 115 | } |
| 116 | |
amadan