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package main
import (
"encoding/json"
"flag"
"os"
"path"
"git.gensokyo.uk/security/fortify/fst"
"git.gensokyo.uk/security/fortify/internal/fmsg"
)
func actionInstall(args []string) {
set := flag.NewFlagSet("install", flag.ExitOnError)
var (
dropShellInstall bool
dropShellActivate bool
)
set.BoolVar(&dropShellInstall, "si", false, "Drop to a shell on installation")
set.BoolVar(&dropShellActivate, "sa", false, "Drop to a shell on activation")
// Ignore errors; set is set for ExitOnError.
_ = set.Parse(args)
args = set.Args()
if len(args) != 1 {
fmsg.Fatal("invalid argument")
}
pkgPath := args[0]
if !path.IsAbs(pkgPath) {
if dir, err := os.Getwd(); err != nil {
fmsg.Fatalf("cannot get current directory: %v", err)
} else {
pkgPath = path.Join(dir, pkgPath)
}
}
/*
Look up paths to programs started by fpkg.
This is done here to ease error handling as cleanup is not yet required.
*/
var (
_ = lookPath("zstd")
tar = lookPath("tar")
chmod = lookPath("chmod")
rm = lookPath("rm")
)
/*
Extract package and set up for cleanup.
*/
var workDir string
if p, err := os.MkdirTemp("", "fpkg.*"); err != nil {
fmsg.Fatalf("cannot create temporary directory: %v", err)
} else {
workDir = p
}
cleanup := func() {
// should be faster than a native implementation
mustRun(chmod, "-R", "+w", workDir)
mustRun(rm, "-rf", workDir)
}
beforeRunFail.Store(&cleanup)
mustRun(tar, "-C", workDir, "-xf", pkgPath)
/*
Parse bundle and app metadata, do pre-install checks.
*/
bundle := loadBundleInfo(path.Join(workDir, "bundle.json"), cleanup)
pathSet := pathSetByApp(bundle.ID)
app := bundle
if s, err := os.Stat(pathSet.metaPath); err != nil {
if !os.IsNotExist(err) {
cleanup()
fmsg.Fatalf("cannot access %q: %v", pathSet.metaPath, err)
panic("unreachable")
}
// did not modify app, clean installation condition met later
} else if s.IsDir() {
cleanup()
fmsg.Fatalf("metadata path %q is not a file", pathSet.metaPath)
panic("unreachable")
} else {
app = loadBundleInfo(pathSet.metaPath, cleanup)
if app.ID != bundle.ID {
cleanup()
fmsg.Fatalf("app %q claims to have identifier %q", bundle.ID, app.ID)
}
// sec: should verify credentials
}
if app != bundle {
// do not try to re-install
if app.Launcher == bundle.Launcher {
cleanup()
fmsg.Printf("package %q is identical to local application %q", pkgPath, app.ID)
fmsg.Exit(0)
}
// AppID determines uid
if app.AppID != bundle.AppID {
cleanup()
fmsg.Fatalf("package %q app id %d differs from installed %d", pkgPath, bundle.AppID, app.AppID)
panic("unreachable")
}
// sec: should compare version string
fmsg.VPrintf("installing application %q version %q over local %q", bundle.ID, bundle.Version, app.Version)
} else {
fmsg.VPrintf("application %q clean installation", bundle.ID)
// sec: should install credentials
}
/*
Setup steps for files owned by the target user.
*/
installConfig := &fst.Config{
ID: bundle.ID,
Command: []string{shell, "-lc", "export BUNDLE=" + fst.Tmp + "/bundle && " + // export inner bundle path in the environment
"mkdir -p etc && chmod -R +w etc && rm -rf etc && cp -dRf $BUNDLE/etc etc && " + // replace inner /etc
"mkdir -p nix && chmod -R +w nix && rm -rf nix && cp -dRf /nix nix && " + // replace inner /nix
"nix copy --offline --no-check-sigs --all --from file://$BUNDLE/res --to $PWD && " + // copy from binary cache
"chmod 0755 .", // make cache directory world-readable for autoetc
},
Confinement: fst.ConfinementConfig{
AppID: bundle.AppID,
Username: "nixos",
Inner: path.Join("/data/data", bundle.ID, "cache"),
Outer: pathSet.cacheDir, // this also ensures cacheDir via fshim
Sandbox: &fst.SandboxConfig{
Hostname: formatHostname(bundle.Name) + "-install",
NoNewSession: dropShellInstall, // nix copy should not need job control
Filesystem: []*fst.FilesystemConfig{
{Src: path.Join(workDir, "nix"), Dst: "/nix", Must: true},
{Src: workDir, Dst: path.Join(fst.Tmp, "bundle"), Must: true},
},
Link: [][2]string{
{bundle.CurrentSystem, "/run/current-system"},
{"/run/current-system/sw/bin", "/bin"},
{"/run/current-system/sw/bin", "/usr/bin"},
},
Etc: path.Join(workDir, "etc"),
AutoEtc: true,
},
ExtraPerms: []*fst.ExtraPermConfig{
{Path: dataHome, Execute: true},
{Ensure: true, Path: pathSet.baseDir, Read: true, Write: true, Execute: true},
{Path: workDir, Execute: true},
},
},
}
if dropShellInstall {
installConfig.Command = []string{shell, "-l"}
fortifyApp(installConfig, cleanup)
cleanup()
fmsg.Exit(0)
}
fortifyApp(installConfig, cleanup)
/*
Activate home-manager generation.
*/
activateConfig := &fst.Config{
ID: bundle.ID,
Command: []string{shell, "-lc", "nix-daemon --store / & " + // start nix-daemon
"(while [ ! -S /nix/var/nix/daemon-socket/socket ]; do sleep 0.01; done) && " + // wait for socket to appear
bundle.ActivationPackage + "/activate && " + // run activation script
"pkill nix-daemon", // terminate nix-daemon
},
Confinement: fst.ConfinementConfig{
AppID: bundle.AppID,
Groups: bundle.Groups,
Username: "fortify",
Inner: path.Join("/data/data", bundle.ID),
Outer: pathSet.homeDir,
Sandbox: &fst.SandboxConfig{
Hostname: formatHostname(bundle.Name) + "-activate",
UserNS: true, // nix sandbox requires userns
NoNewSession: dropShellActivate, // home-manager activation should not need job control
Filesystem: []*fst.FilesystemConfig{
{Src: pathSet.nixPath, Dst: "/nix", Write: true, Must: true},
},
Link: [][2]string{
{bundle.CurrentSystem, "/run/current-system"},
{"/run/current-system/sw/bin", "/bin"},
{"/run/current-system/sw/bin", "/usr/bin"},
},
Etc: path.Join(pathSet.cacheDir, "etc"),
AutoEtc: true,
},
ExtraPerms: []*fst.ExtraPermConfig{
{Path: dataHome, Execute: true},
{Ensure: true, Path: pathSet.baseDir, Read: true, Write: true, Execute: true},
{Path: workDir, Execute: true},
},
},
}
if dropShellActivate {
activateConfig.Command = []string{shell, "-l"}
fortifyApp(activateConfig, cleanup)
cleanup()
fmsg.Exit(0)
}
fortifyApp(activateConfig, cleanup)
/*
Installation complete. Write metadata to block re-installs or downgrades.
*/
// serialise metadata to ensure consistency
if f, err := os.OpenFile(pathSet.metaPath+"~", os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644); err != nil {
cleanup()
fmsg.Fatalf("cannot create metadata file: %v", err)
panic("unreachable")
} else if err = json.NewEncoder(f).Encode(bundle); err != nil {
cleanup()
fmsg.Fatalf("cannot write metadata: %v", err)
panic("unreachable")
} else if err = f.Close(); err != nil {
fmsg.Printf("cannot close metadata file: %v", err)
// not fatal
}
if err := os.Rename(pathSet.metaPath+"~", pathSet.metaPath); err != nil {
cleanup()
fmsg.Fatalf("cannot rename metadata file: %v", err)
panic("unreachable")
}
cleanup()
}
|
