jochen
5fc37b44a9
An account could replace ~/.claude with a link to /etc and have the node-engine chown, chmod or write through it on the next apply. Below a person's or an agent's home every component is now opened without following a link, and a link refuses the resource in words. The root judge also reads doas and polkit rules, the container runtimes' sockets with their ACLs, ACLs on the secrets, and setuid-root programs no package owns, in the C locale; Judged and NotJudged write down exactly what it covers (hq ADR 0266 review).
206 lines
7.2 KiB
Go
206 lines
7.2 KiB
Go
//go:build linux
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package apply
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import (
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"context"
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"errors"
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"os"
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"path/filepath"
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"strings"
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"testing"
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"github.com/novox/mesh-host/internal/store"
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)
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// Defends novox/hq ADR 0266 (the review of 2026-10-08): below a home, the node-engine — root — follows no
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// symbolic link an account can put there: not to chown or chmod, not to write, not to make a directory.
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// aLinkedHome is a home the test names as one, with `.claude` replaced by a link to a directory outside it,
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// as an account would to have root change /etc.
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func aLinkedHome(t *testing.T) (home, outside string) {
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t.Helper()
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root := t.TempDir()
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home = filepath.Join(root, "home", "agent")
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outside = filepath.Join(root, "etc")
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for _, d := range []string{home, outside} {
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if err := os.MkdirAll(d, 0o755); err != nil {
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t.Fatal(err)
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}
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}
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if err := os.WriteFile(filepath.Join(outside, "shadow"), []byte("root's"), 0o600); err != nil {
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t.Fatal(err)
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}
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was := homes
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homes = func() []string { return []string{home} }
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t.Cleanup(func() { homes = was })
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return home, outside
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}
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func link(t *testing.T, target, at string) {
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t.Helper()
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if err := os.Symlink(target, at); err != nil {
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t.Fatal(err)
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}
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}
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func applyOneResource(t *testing.T, resource string) error {
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t.Helper()
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d := declare(t, resource)
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_, _, err := Apply(context.Background(), archHost(t), d, store.State{}, store.OriginDeclared, noServices, nil, nil)
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return err
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}
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func mustBeLinkRefusal(t *testing.T, err error) {
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t.Helper()
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var refused *LinkUnderHomeError
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if !errors.As(err, &refused) {
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t.Fatalf("refused as a link under a home, got %v", err)
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}
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if !strings.Contains(err.Error(), "never follows a link") {
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t.Fatalf("said in words: %v", err)
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}
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}
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func modeOfPath(t *testing.T, p string) os.FileMode {
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t.Helper()
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info, err := os.Stat(p)
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if err != nil {
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t.Fatal(err)
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}
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return info.Mode().Perm()
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}
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func TestADirectoryUnderAHomeThatIsALinkIsRefusedAndItsTargetUntouched(t *testing.T) {
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home, outside := aLinkedHome(t)
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link(t, outside, filepath.Join(home, ".claude"))
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err := applyOneResource(t, `{"id":"claude-code.agent-home","type":"directory","path":"`+
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filepath.Join(home, ".claude")+`","mode":"0700"}`)
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mustBeLinkRefusal(t, err)
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if m := modeOfPath(t, outside); m != 0o755 {
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t.Fatalf("the link's target was chmodded to %o", m)
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}
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}
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func TestAFileThroughALinkedParentUnderAHomeIsRefused(t *testing.T) {
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home, outside := aLinkedHome(t)
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link(t, outside, filepath.Join(home, ".claude"))
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err := applyOneResource(t, `{"id":"m.f","type":"file","path":"`+filepath.Join(home, ".claude", "shadow")+
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`","content":"the mesh's\n","mode":"0644"}`)
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mustBeLinkRefusal(t, err)
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if got, _ := os.ReadFile(filepath.Join(outside, "shadow")); string(got) != "root's" {
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t.Fatalf("written through the link: %q", got)
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}
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if m := modeOfPath(t, filepath.Join(outside, "shadow")); m != 0o600 {
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t.Fatalf("chmodded through the link: %o", m)
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}
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}
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func TestAFileThatIsItselfALinkUnderAHomeIsRefused(t *testing.T) {
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home, outside := aLinkedHome(t)
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link(t, filepath.Join(outside, "shadow"), filepath.Join(home, ".zshrc"))
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err := applyOneResource(t, `{"id":"m.f","type":"file","path":"`+filepath.Join(home, ".zshrc")+
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`","content":"x\n"}`)
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mustBeLinkRefusal(t, err)
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if got, _ := os.ReadFile(filepath.Join(outside, "shadow")); string(got) != "root's" {
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t.Fatalf("written through the link: %q", got)
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}
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}
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func TestADirectoryAndAFileUnderAHomeAreMadeAsBefore(t *testing.T) {
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home, _ := aLinkedHome(t)
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dir := filepath.Join(home, ".claude")
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if err := applyOneResource(t, `{"id":"m.d","type":"directory","path":"`+dir+`","mode":"0700"}`); err != nil {
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t.Fatal(err)
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}
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if m := modeOfPath(t, dir); m != 0o700 {
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t.Fatalf("mode %o", m)
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}
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file := filepath.Join(home, ".config", "mesh", "env.sh")
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if err := applyOneResource(t, `{"id":"m.f","type":"file","path":"`+file+`","content":"A=1\n","mode":"0640"}`); err != nil {
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t.Fatal(err)
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}
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if got, _ := os.ReadFile(file); string(got) != "A=1\n" || modeOfPath(t, file) != 0o640 {
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t.Fatalf("written %q mode %o", got, modeOfPath(t, file))
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}
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}
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// The descriptor half: a link put in place after any check is still not followed.
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func TestTheDescriptorCallsFollowNoLinkBelowAHome(t *testing.T) {
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home, outside := aLinkedHome(t)
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link(t, outside, filepath.Join(home, ".claude"))
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mustBeLinkRefusal(t, chmodPath(filepath.Join(home, ".claude"), 0o777))
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mustBeLinkRefusal(t, chmodPath(filepath.Join(home, ".claude", "shadow"), 0o777))
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if m := modeOfPath(t, filepath.Join(outside, "shadow")); m != 0o600 {
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t.Fatalf("chmodded through the link: %o", m)
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}
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mustBeLinkRefusal(t, writeAtomically(filepath.Join(home, ".claude", "new"), []byte("x"), 0o644))
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if _, err := os.Stat(filepath.Join(outside, "new")); !os.IsNotExist(err) {
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t.Fatal("written through the link")
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}
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if _, err := makeDirsSaying(filepath.Join(home, ".claude", "a", "b"), 0o755, ""); err == nil {
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t.Fatal("made directories through the link")
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}
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if _, err := os.Stat(filepath.Join(outside, "a")); !os.IsNotExist(err) {
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t.Fatal("made a directory through the link")
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}
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if _, err := readPath(filepath.Join(home, ".claude", "shadow")); err == nil {
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t.Fatal("read through the link")
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}
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me := os.Getuid()
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// A link itself is owned as a link, never its target.
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if err := chownPath(filepath.Join(home, ".claude"), me, os.Getgid()); err != nil {
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t.Fatalf("a link is owned as a link: %v", err)
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}
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}
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func TestRemovalThroughALinkUnderAHomeIsRefused(t *testing.T) {
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home, outside := aLinkedHome(t)
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link(t, outside, filepath.Join(home, ".claude"))
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_, _, err := remove(context.Background(), archHost(t), store.Applied{ID: "m.f", Type: "file",
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Target: filepath.Join(home, ".claude", "shadow")}, nil, nil)
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mustBeLinkRefusal(t, err)
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if _, err := os.Stat(filepath.Join(outside, "shadow")); err != nil {
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t.Fatal("removed through the link")
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}
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}
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func TestAPathOutsideEveryHomeIsHandledAsBefore(t *testing.T) {
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_, outside := aLinkedHome(t)
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elsewhere := filepath.Join(filepath.Dir(outside), "srv")
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if err := os.MkdirAll(elsewhere, 0o755); err != nil {
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t.Fatal(err)
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}
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link(t, outside, filepath.Join(elsewhere, "linked"))
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if homeAbove(filepath.Join(elsewhere, "linked", "x")) != "" {
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t.Fatal("not below a home")
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}
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if err := refuseLinksUnderHome(filepath.Join(elsewhere, "linked", "x")); err != nil {
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t.Fatal("a system path may be a link the machine set up; only a home's are refused")
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}
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}
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func TestHomesAreAPersonsOrAnAgentsNotAServicesOrRoots(t *testing.T) {
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dir := t.TempDir()
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passwd := filepath.Join(dir, "passwd")
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if err := os.WriteFile(passwd, []byte("root:x:0:0::/root:/bin/bash\n"+
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"postgres:x:968:968::/var/lib/postgres:/usr/bin/nologin\n"+
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"nobody:x:65534:65534::/:/usr/bin/nologin\n"+
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"operator:x:1000:1000::/home/operator:/bin/zsh\n"+
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"agent:x:1001:1001::/home/agent:/bin/bash\n"+
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"svc:x:990:990::/home/svc:/usr/bin/nologin\n"), 0o644); err != nil {
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t.Fatal(err)
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}
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was := passwdFile
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passwdFile = passwd
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t.Cleanup(func() { passwdFile = was })
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got := strings.Join(homes(), ",")
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if got != "/home/operator,/home/agent,/home/svc" {
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t.Fatalf("homes %s", got)
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}
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if homeAbove("/home/agent/.claude") != "/home/agent" || homeAbove("/home/agent") != "" ||
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homeAbove("/var/lib/postgres/data") != "" || homeAbove("/root/.ssh") != "" {
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t.Fatal("strictly below a person's or an agent's home, and nothing else")
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}
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}
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