container: optionally isolate host abstract UNIX domain sockets via landlock

internal/app/seal_linux.go

@@ -12,7 +12,6 @@ import (
 	"path"
 	"regexp"
 	"slices"
-	"strconv"
 	"strings"
 	"sync/atomic"
 	"syscall"
@@ -391,22 +390,6 @@ func (seal *outcome) finalise(ctx context.Context, sys sys.State, config *hst.Co
 			seal.env[display] = d
 			socketDir := container.AbsFHSTmp.Append(".X11-unix")
 			seal.container.Bind(socketDir, socketDir, 0)
-
-			// the socket file at `/tmp/.X11-unix/X%d` is typically owned by the priv user
-			// and not accessible by the target user
-			var socketPath *container.Absolute
-			if len(d) > 1 && d[0] == ':' { // `:%d`
-				if n, err := strconv.Atoi(d[1:]); err == nil && n >= 0 {
-					socketPath = socketDir.Append("X" + strconv.Itoa(n))
-				}
-			} else if len(d) > 5 && strings.HasPrefix(d, "unix:") { // `unix:%s`
-				if a, err := container.NewAbs(d[5:]); err == nil {
-					socketPath = a
-				}
-			}
-			if socketPath != nil {
-				seal.sys.UpdatePermTypeOptional(system.EX11, socketPath.String(), acl.Read, acl.Write, acl.Execute)
-			}
 		}
 	}
 

system/acl.go

@@ -21,17 +21,7 @@ func (sys *I) UpdatePermType(et Enablement, path string, perms ...acl.Perm) *I {
 	sys.lock.Lock()
 	defer sys.lock.Unlock()
 
-	sys.ops = append(sys.ops, &ACL{et, path, perms, false})
+	sys.ops = append(sys.ops, &ACL{et, path, perms})
-
-	return sys
-}
-
-// UpdatePermTypeOptional appends an acl update Op that silently continues if the target does not exist.
-func (sys *I) UpdatePermTypeOptional(et Enablement, path string, perms ...acl.Perm) *I {
-	sys.lock.Lock()
-	defer sys.lock.Unlock()
-
-	sys.ops = append(sys.ops, &ACL{et, path, perms, true})
 
 	return sys
 }
@@ -40,24 +30,14 @@ type ACL struct {
 	et    Enablement
 	path  string
 	perms acl.Perms
-
-	// since revert operations are cross-process, the success of apply must not affect the outcome of revert
-	skipNotExist bool
 }
 
 func (a *ACL) Type() Enablement { return a.et }
 
 func (a *ACL) apply(sys *I) error {
 	msg.Verbose("applying ACL", a)
-	if err := acl.Update(a.path, sys.uid, a.perms...); err != nil {
+	return wrapErrSuffix(acl.Update(a.path, sys.uid, a.perms...),
-		if !a.skipNotExist || !os.IsNotExist(err) {
-			return wrapErrSuffix(err,
 		fmt.Sprintf("cannot apply ACL entry to %q:", a.path))
-		}
-		msg.Verbosef("path %q does not exist", a.path)
-		return nil
-	}
-	return nil
 }
 
 func (a *ACL) revert(sys *I, ec *Criteria) error {

system/acl_test.go

@@ -20,7 +20,7 @@ func TestUpdatePerm(t *testing.T) {
 		t.Run(tc.path+permSubTestSuffix(tc.perms), func(t *testing.T) {
 			sys := New(150)
 			sys.UpdatePerm(tc.path, tc.perms...)
-			(&tcOp{Process, tc.path}).test(t, sys.ops, []Op{&ACL{Process, tc.path, tc.perms, false}}, "UpdatePerm")
+			(&tcOp{Process, tc.path}).test(t, sys.ops, []Op{&ACL{Process, tc.path, tc.perms}}, "UpdatePerm")
 		})
 	}
 }
@@ -42,7 +42,7 @@ func TestUpdatePermType(t *testing.T) {
 		t.Run(tc.path+"_"+TypeString(tc.et)+permSubTestSuffix(tc.perms), func(t *testing.T) {
 			sys := New(150)
 			sys.UpdatePermType(tc.et, tc.path, tc.perms...)
-			tc.test(t, sys.ops, []Op{&ACL{tc.et, tc.path, tc.perms, false}}, "UpdatePermType")
+			tc.test(t, sys.ops, []Op{&ACL{tc.et, tc.path, tc.perms}}, "UpdatePermType")
 		})
 	}
 }

test/sandbox/assert.go

@@ -15,7 +15,6 @@ import (
 	"errors"
 	"io/fs"
 	"log"
-	"net"
 	"os"
 	"syscall"
 )
@@ -34,10 +33,6 @@ type TestCase struct {
 	FS      *FS               `json:"fs"`
 	Mount   []*MountinfoEntry `json:"mount"`
 	Seccomp bool              `json:"seccomp"`
-
-	TrySocket      string `json:"try_socket,omitempty"`
-	SocketAbstract bool   `json:"socket_abstract,omitempty"`
-	SocketPathname bool   `json:"socket_pathname,omitempty"`
 }
 
 type T struct {
@@ -130,47 +125,6 @@ func (t *T) MustCheck(want *TestCase) {
 	} else {
 		printf("[SKIP] skipping seccomp check")
 	}
-
-	if want.TrySocket != "" {
-		abstractConn, abstractErr := net.Dial("unix", "@"+want.TrySocket)
-		pathnameConn, pathnameErr := net.Dial("unix", want.TrySocket)
-		ok := true
-
-		if abstractErr == nil {
-			if err := abstractConn.Close(); err != nil {
-				ok = false
-				log.Printf("Close: %v", err)
-			}
-		}
-		if pathnameErr == nil {
-			if err := pathnameConn.Close(); err != nil {
-				ok = false
-				log.Printf("Close: %v", err)
-			}
-		}
-
-		abstractWantErr := error(syscall.EPERM)
-		pathnameWantErr := error(syscall.ENOENT)
-		if want.SocketAbstract {
-			abstractWantErr = nil
-		}
-		if want.SocketPathname {
-			pathnameWantErr = nil
-		}
-
-		if !errors.Is(abstractErr, abstractWantErr) {
-			ok = false
-			log.Printf("abstractErr: %v, want %v", abstractErr, abstractWantErr)
-		}
-		if !errors.Is(pathnameErr, pathnameWantErr) {
-			ok = false
-			log.Printf("pathnameErr: %v, want %v", pathnameErr, pathnameWantErr)
-		}
-
-		if !ok {
-			os.Exit(1)
-		}
-	}
 }
 
 func MustCheckFilter(pid int, want string) {

test/sandbox/case/default.nix

@@ -50,9 +50,6 @@ let
         useCommonPaths
         userns
         ;
-      enablements = {
-        inherit (tc) x11;
-      };
       share = testProgram;
       packages = [ ];
       path = "${testProgram}/bin/hakurei-test";

test/sandbox/case/device.nix

@@ -25,7 +25,6 @@ in
   mapRealUid = false;
   useCommonPaths = true;
   userns = false;
-  x11 = true;
 
   # 0, PresetStrict
   expectedFilter = {
@@ -36,7 +35,6 @@ in
   want = {
     env = [
       "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/65534/bus"
-      "DISPLAY=:0"
       "HOME=/var/lib/hakurei/u0/a4"
       "PULSE_SERVER=unix:/run/user/65534/pulse/native"
       "SHELL=/run/current-system/sw/bin/bash"
@@ -163,9 +161,7 @@ in
         } null;
         devices = fs "800001ed" null null;
       } null;
-      tmp = fs "800001f8" {
+      tmp = fs "800001f8" { } null;
-        ".X11-unix" = fs "801001ff" { X0 = fs "10001fd" null null; } null;
-      } null;
       usr = fs "800001c0" { bin = fs "800001ed" { env = fs "80001ff" null null; } null; } null;
       var = fs "800001c0" {
         lib = fs "800001c0" {
@@ -235,15 +231,10 @@ in
       (ent ignore "/etc/passwd" "ro,nosuid,nodev,relatime" "tmpfs" "rootfs" "rw,uid=1000004,gid=1000004")
       (ent ignore "/etc/group" "ro,nosuid,nodev,relatime" "tmpfs" "rootfs" "rw,uid=1000004,gid=1000004")
       (ent ignore "/run/user/65534/wayland-0" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
-      (ent "/tmp/.X11-unix" "/tmp/.X11-unix" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
       (ent ignore "/run/user/65534/pulse/native" "ro,nosuid,nodev,relatime" "tmpfs" "tmpfs" ignore)
       (ent ignore "/run/user/65534/bus" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
     ];
 
     seccomp = true;
-
-    try_socket = "/tmp/.X11-unix/X0";
-    socket_abstract = false;
-    socket_pathname = true;
   };
 }

test/sandbox/case/mapuid.nix

@@ -34,7 +34,6 @@ in
   mapRealUid = true;
   useCommonPaths = true;
   userns = false;
-  x11 = false;
 
   # 0, PresetStrict
   expectedFilter = {
@@ -267,9 +266,5 @@ in
     ];
 
     seccomp = true;
-
-    try_socket = "/tmp/.X11-unix/X0";
-    socket_abstract = false;
-    socket_pathname = false;
   };
 }

test/sandbox/case/pdlike.nix

@@ -34,7 +34,6 @@ in
   mapRealUid = false;
   useCommonPaths = false;
   userns = true;
-  x11 = false;
 
   # 0, PresetExt | PresetDenyDevel
   expectedFilter = {
@@ -262,9 +261,5 @@ in
     ];
 
     seccomp = true;
-
-    try_socket = "/tmp/.X11-unix/X0";
-    socket_abstract = false;
-    socket_pathname = false;
   };
 }

test/sandbox/case/preset.nix

@@ -34,7 +34,6 @@ in
   mapRealUid = false;
   useCommonPaths = false;
   userns = false;
-  x11 = false;
 
   # 0, PresetStrict
   expectedFilter = {
@@ -260,9 +259,5 @@ in
     ];
 
     seccomp = true;
-
-    try_socket = "/tmp/.X11-unix/X0";
-    socket_abstract = false;
-    socket_pathname = false;
   };
 }

test/sandbox/case/tty.nix

@@ -34,7 +34,6 @@ in
   mapRealUid = false;
   useCommonPaths = true;
   userns = false;
-  x11 = true;
 
   # 0, PresetExt | PresetDenyNS | PresetDenyDevel
   expectedFilter = {
@@ -45,7 +44,6 @@ in
   want = {
     env = [
       "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/65534/bus"
-      "DISPLAY=:0"
       "HOME=/var/lib/hakurei/u0/a2"
       "PULSE_SERVER=unix:/run/user/65534/pulse/native"
       "SHELL=/run/current-system/sw/bin/bash"
@@ -190,9 +188,7 @@ in
         } null;
         devices = fs "800001ed" null null;
       } null;
-      tmp = fs "800001f8" {
+      tmp = fs "800001f8" { } null;
-        ".X11-unix" = fs "801001ff" { X0 = fs "10001fd" null null; } null;
-      } null;
       usr = fs "800001c0" { bin = fs "800001ed" { env = fs "80001ff" null null; } null; } null;
       var = fs "800001c0" {
         lib = fs "800001c0" {
@@ -267,15 +263,10 @@ in
       (ent ignore "/etc/passwd" "ro,nosuid,nodev,relatime" "tmpfs" "rootfs" "rw,uid=1000002,gid=1000002")
       (ent ignore "/etc/group" "ro,nosuid,nodev,relatime" "tmpfs" "rootfs" "rw,uid=1000002,gid=1000002")
       (ent ignore "/run/user/65534/wayland-0" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
-      (ent "/tmp/.X11-unix" "/tmp/.X11-unix" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
       (ent ignore "/run/user/65534/pulse/native" "ro,nosuid,nodev,relatime" "tmpfs" "tmpfs" ignore)
       (ent ignore "/run/user/65534/bus" "ro,nosuid,nodev,relatime" "ext4" "/dev/disk/by-label/nixos" "rw")
     ];
 
     seccomp = true;
-
-    try_socket = "/tmp/.X11-unix/X0";
-    socket_abstract = false;
-    socket_pathname = true;
   };
 }