fst: rename from fipc

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

fst/config.go

@@ -0,0 +1,242 @@
+package fst
+
+import (
+	"errors"
+
+	"git.ophivana.moe/security/fortify/dbus"
+	"git.ophivana.moe/security/fortify/helper/bwrap"
+	"git.ophivana.moe/security/fortify/internal/linux"
+	"git.ophivana.moe/security/fortify/internal/system"
+)
+
+const fTmp = "/fortify"
+
+// Config is used to seal an *App
+type Config struct {
+	// D-Bus application ID
+	ID string `json:"id"`
+	// value passed through to the child process as its argv
+	Command []string `json:"command"`
+
+	// child confinement configuration
+	Confinement ConfinementConfig `json:"confinement"`
+}
+
+// ConfinementConfig defines fortified child's confinement
+type ConfinementConfig struct {
+	// numerical application id, determines uid in the init namespace
+	AppID int `json:"app_id"`
+	// list of supplementary groups to inherit
+	Groups []string `json:"groups"`
+	// passwd username in the sandbox, defaults to chronos
+	Username string `json:"username,omitempty"`
+	// home directory in sandbox, empty for outer
+	Inner string `json:"home_inner"`
+	// home directory in init namespace
+	Outer string `json:"home"`
+	// bwrap sandbox confinement configuration
+	Sandbox *SandboxConfig `json:"sandbox"`
+
+	// reference to a system D-Bus proxy configuration,
+	// nil value disables system bus proxy
+	SystemBus *dbus.Config `json:"system_bus,omitempty"`
+	// reference to a session D-Bus proxy configuration,
+	// nil value makes session bus proxy assume built-in defaults
+	SessionBus *dbus.Config `json:"session_bus,omitempty"`
+
+	// child capability enablements
+	Enablements system.Enablements `json:"enablements"`
+}
+
+// SandboxConfig describes resources made available to the sandbox.
+type SandboxConfig struct {
+	// unix hostname within sandbox
+	Hostname string `json:"hostname,omitempty"`
+	// userns availability within sandbox
+	UserNS bool `json:"userns,omitempty"`
+	// share net namespace
+	Net bool `json:"net,omitempty"`
+	// share all devices
+	Dev bool `json:"dev,omitempty"`
+	// do not run in new session
+	NoNewSession bool `json:"no_new_session,omitempty"`
+	// map target user uid to privileged user uid in the user namespace
+	MapRealUID bool `json:"map_real_uid"`
+	// direct access to wayland socket
+	DirectWayland bool `json:"direct_wayland,omitempty"`
+
+	// final environment variables
+	Env map[string]string `json:"env"`
+	// sandbox host filesystem access
+	Filesystem []*FilesystemConfig `json:"filesystem"`
+	// symlinks created inside the sandbox
+	Link [][2]string `json:"symlink"`
+	// automatically set up /etc symlinks
+	AutoEtc bool `json:"auto_etc"`
+	// paths to override by mounting tmpfs over them
+	Override []string `json:"override"`
+}
+
+type FilesystemConfig struct {
+	// mount point in sandbox, same as src if empty
+	Dst string `json:"dst,omitempty"`
+	// host filesystem path to make available to sandbox
+	Src string `json:"src"`
+	// write access
+	Write bool `json:"write,omitempty"`
+	// device access
+	Device bool `json:"dev,omitempty"`
+	// exit if unable to share
+	Must bool `json:"require,omitempty"`
+}
+
+// Bwrap returns the address of the corresponding bwrap.Config to s.
+// Note that remaining tmpfs entries must be queued by the caller prior to launch.
+func (s *SandboxConfig) Bwrap(os linux.System) (*bwrap.Config, error) {
+	if s == nil {
+		return nil, errors.New("nil sandbox config")
+	}
+
+	var uid int
+	if !s.MapRealUID {
+		uid = 65534
+	} else {
+		uid = os.Geteuid()
+	}
+
+	conf := (&bwrap.Config{
+		Net:           s.Net,
+		UserNS:        s.UserNS,
+		Hostname:      s.Hostname,
+		Clearenv:      true,
+		SetEnv:        s.Env,
+		NewSession:    !s.NoNewSession,
+		DieWithParent: true,
+		AsInit:        true,
+
+		// initialise map
+		Chmod: make(bwrap.ChmodConfig),
+	}).
+		SetUID(uid).SetGID(uid).
+		Procfs("/proc").
+		Tmpfs(fTmp, 4*1024)
+
+	if !s.Dev {
+		conf.DevTmpfs("/dev").Mqueue("/dev/mqueue")
+	} else {
+		conf.Bind("/dev", "/dev", false, true, true)
+	}
+
+	if !s.AutoEtc {
+		conf.Dir("/etc")
+	}
+
+	for _, c := range s.Filesystem {
+		if c == nil {
+			continue
+		}
+		src := c.Src
+		dest := c.Dst
+		if c.Dst == "" {
+			dest = c.Src
+		}
+		conf.Bind(src, dest, !c.Must, c.Write, c.Device)
+	}
+
+	for _, l := range s.Link {
+		conf.Symlink(l[0], l[1])
+	}
+
+	if s.AutoEtc {
+		conf.Bind("/etc", fTmp+"/etc")
+
+		// link host /etc contents to prevent passwd/group from being overwritten
+		if d, err := os.ReadDir("/etc"); err != nil {
+			return nil, err
+		} else {
+			for _, ent := range d {
+				name := ent.Name()
+				switch name {
+				case "passwd":
+				case "group":
+
+				case "mtab":
+					conf.Symlink("/proc/mounts", "/etc/"+name)
+				default:
+					conf.Symlink(fTmp+"/etc/"+name, "/etc/"+name)
+				}
+			}
+		}
+	}
+
+	return conf, nil
+}
+
+// Template returns a fully populated instance of Config.
+func Template() *Config {
+	return &Config{
+		ID: "org.chromium.Chromium",
+		Command: []string{
+			"chromium",
+			"--ignore-gpu-blocklist",
+			"--disable-smooth-scrolling",
+			"--enable-features=UseOzonePlatform",
+			"--ozone-platform=wayland",
+		},
+		Confinement: ConfinementConfig{
+			AppID:    9,
+			Groups:   []string{"video"},
+			Username: "chronos",
+			Outer:    "/var/lib/persist/home/org.chromium.Chromium",
+			Inner:    "/var/lib/fortify",
+			Sandbox: &SandboxConfig{
+				Hostname:      "localhost",
+				UserNS:        true,
+				Net:           true,
+				NoNewSession:  true,
+				MapRealUID:    true,
+				Dev:           true,
+				DirectWayland: false,
+				// example API credentials pulled from Google Chrome
+				// DO NOT USE THESE IN A REAL BROWSER
+				Env: map[string]string{
+					"GOOGLE_API_KEY":               "AIzaSyBHDrl33hwRp4rMQY0ziRbj8K9LPA6vUCY",
+					"GOOGLE_DEFAULT_CLIENT_ID":     "77185425430.apps.googleusercontent.com",
+					"GOOGLE_DEFAULT_CLIENT_SECRET": "OTJgUOQcT7lO7GsGZq2G4IlT",
+				},
+				Filesystem: []*FilesystemConfig{
+					{Src: "/nix/store"},
+					{Src: "/run/current-system"},
+					{Src: "/run/opengl-driver"},
+					{Src: "/var/db/nix-channels"},
+					{Src: "/home/chronos", Write: true, Must: true},
+					{Src: "/dev/dri", Device: true},
+				},
+				Link:     [][2]string{{"/run/user/65534", "/run/user/150"}},
+				AutoEtc:  true,
+				Override: []string{"/var/run/nscd"},
+			},
+			SystemBus: &dbus.Config{
+				See:       nil,
+				Talk:      []string{"org.bluez", "org.freedesktop.Avahi", "org.freedesktop.UPower"},
+				Own:       nil,
+				Call:      nil,
+				Broadcast: nil,
+				Log:       false,
+				Filter:    true,
+			},
+			SessionBus: &dbus.Config{
+				See: nil,
+				Talk: []string{"org.freedesktop.Notifications", "org.freedesktop.FileManager1", "org.freedesktop.ScreenSaver",
+					"org.freedesktop.secrets", "org.kde.kwalletd5", "org.kde.kwalletd6", "org.gnome.SessionManager"},
+				Own: []string{"org.chromium.Chromium.*", "org.mpris.MediaPlayer2.org.chromium.Chromium.*",
+					"org.mpris.MediaPlayer2.chromium.*"},
+				Call:      map[string]string{"org.freedesktop.portal.*": "*"},
+				Broadcast: map[string]string{"org.freedesktop.portal.*": "@/org/freedesktop/portal/*"},
+				Log:       false,
+				Filter:    true,
+			},
+			Enablements: system.EWayland.Mask() | system.EDBus.Mask() | system.EPulse.Mask(),
+		},
+	}
+}

fst/shared.go

@@ -0,0 +1,18 @@
+// Package fst exports shared fortify types.
+package fst
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+)
+
+type ID [16]byte
+
+func (a *ID) String() string {
+	return hex.EncodeToString(a[:])
+}
+
+func NewAppID(id *ID) error {
+	_, err := rand.Read(id[:])
+	return err
+}