container: optionally isolate host abstract UNIX domain sockets via landlock

container/container.go

@@ -189,10 +189,11 @@ func (p *Container) Start() error {
 
 			// landlock: depends on per-thread state but acts on a process group
 			{
-				rulesetAttr := &RulesetAttr{Scoped: LANDLOCK_SCOPE_SIGNAL}
+				scoped := LANDLOCK_SCOPE_SIGNAL
 				if !p.HostAbstract {
-					rulesetAttr.Scoped |= LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET
+					scoped |= LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET
 				}
+				rulesetAttr := NewRulesetAttr(scoped)
 
 				if abi, err := LandlockGetABI(); err != nil {
 					if p.HostAbstract {
@@ -213,11 +214,12 @@ func (p *Container) Start() error {
 					msg.Verbosef("landlock abi version %d", abi)
 				}
 
-				if rulesetFd, err := rulesetAttr.Create(0); err != nil {
+				msg.Verbosef("creating landlock ruleset scoped %#x", int(scoped))
+				if rulesetFd, err := LandlockCreateRuleset(&rulesetAttr, 0); err != nil {
 					return wrapErrSuffix(err,
 						"cannot create landlock ruleset:")
 				} else {
-					msg.Verbosef("enforcing landlock ruleset %s", rulesetAttr)
+					msg.Verbose("enforcing landlock ruleset")
 					if err = LandlockRestrictSelf(rulesetFd, 0); err != nil {
 						_ = Close(rulesetFd)
 						return wrapErrSuffix(err,

container/landlock.go

@@ -1,210 +1,30 @@
 package container
 
+/*
+#include <linux/landlock.h>
+#include <sys/syscall.h>
+*/
+import "C"
 import (
-	"strings"
 	"syscall"
 	"unsafe"
 
 	"hakurei.app/container/seccomp"
 )
 
-// include/uapi/linux/landlock.h
-
 const (
-	LANDLOCK_CREATE_RULESET_VERSION = 1 << iota
+	LANDLOCK_CREATE_RULESET_VERSION     = C.LANDLOCK_CREATE_RULESET_VERSION
+	LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET = C.LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET
+	LANDLOCK_SCOPE_SIGNAL               = C.LANDLOCK_SCOPE_SIGNAL
 )
 
-type LandlockAccessFS uintptr
+type RulesetAttr = C.struct_landlock_ruleset_attr
 
-const (
+func NewRulesetAttr(scoped int) RulesetAttr { return RulesetAttr{scoped: C.__u64(scoped)} }
-	LANDLOCK_ACCESS_FS_EXECUTE LandlockAccessFS = 1 << iota
-	LANDLOCK_ACCESS_FS_WRITE_FILE
-	LANDLOCK_ACCESS_FS_READ_FILE
-	LANDLOCK_ACCESS_FS_READ_DIR
-	LANDLOCK_ACCESS_FS_REMOVE_DIR
-	LANDLOCK_ACCESS_FS_REMOVE_FILE
-	LANDLOCK_ACCESS_FS_MAKE_CHAR
-	LANDLOCK_ACCESS_FS_MAKE_DIR
-	LANDLOCK_ACCESS_FS_MAKE_REG
-	LANDLOCK_ACCESS_FS_MAKE_SOCK
-	LANDLOCK_ACCESS_FS_MAKE_FIFO
-	LANDLOCK_ACCESS_FS_MAKE_BLOCK
-	LANDLOCK_ACCESS_FS_MAKE_SYM
-	LANDLOCK_ACCESS_FS_REFER
-	LANDLOCK_ACCESS_FS_TRUNCATE
-	LANDLOCK_ACCESS_FS_IOCTL_DEV
 
-	_LANDLOCK_ACCESS_FS_DELIM
+/* TODO: remove everything above this */
-)
 
-func (f LandlockAccessFS) String() string {
+func LandlockCreateRuleset(rulesetAttr *RulesetAttr, flags uintptr) (fd int, err error) {
-	switch f {
-	case LANDLOCK_ACCESS_FS_EXECUTE:
-		return "execute"
-
-	case LANDLOCK_ACCESS_FS_WRITE_FILE:
-		return "write_file"
-
-	case LANDLOCK_ACCESS_FS_READ_FILE:
-		return "read_file"
-
-	case LANDLOCK_ACCESS_FS_READ_DIR:
-		return "read_dir"
-
-	case LANDLOCK_ACCESS_FS_REMOVE_DIR:
-		return "remove_dir"
-
-	case LANDLOCK_ACCESS_FS_REMOVE_FILE:
-		return "remove_file"
-
-	case LANDLOCK_ACCESS_FS_MAKE_CHAR:
-		return "make_char"
-
-	case LANDLOCK_ACCESS_FS_MAKE_DIR:
-		return "make_dir"
-
-	case LANDLOCK_ACCESS_FS_MAKE_REG:
-		return "make_reg"
-
-	case LANDLOCK_ACCESS_FS_MAKE_SOCK:
-		return "make_sock"
-
-	case LANDLOCK_ACCESS_FS_MAKE_FIFO:
-		return "make_fifo"
-
-	case LANDLOCK_ACCESS_FS_MAKE_BLOCK:
-		return "make_block"
-
-	case LANDLOCK_ACCESS_FS_MAKE_SYM:
-		return "make_sym"
-
-	case LANDLOCK_ACCESS_FS_REFER:
-		return "fs_refer"
-
-	case LANDLOCK_ACCESS_FS_TRUNCATE:
-		return "fs_truncate"
-
-	case LANDLOCK_ACCESS_FS_IOCTL_DEV:
-		return "fs_ioctl_dev"
-
-	default:
-		var c []LandlockAccessFS
-		for i := LandlockAccessFS(1); i < _LANDLOCK_ACCESS_FS_DELIM; i <<= 1 {
-			if f&i != 0 {
-				c = append(c, i)
-			}
-		}
-		if len(c) == 0 {
-			return "NULL"
-		}
-		s := make([]string, len(c))
-		for i, v := range c {
-			s[i] = v.String()
-		}
-		return strings.Join(s, " ")
-	}
-}
-
-type LandlockAccessNet uintptr
-
-const (
-	LANDLOCK_ACCESS_NET_BIND_TCP LandlockAccessNet = 1 << iota
-	LANDLOCK_ACCESS_NET_CONNECT_TCP
-
-	_LANDLOCK_ACCESS_NET_DELIM
-)
-
-func (f LandlockAccessNet) String() string {
-	switch f {
-	case LANDLOCK_ACCESS_NET_BIND_TCP:
-		return "bind_tcp"
-
-	case LANDLOCK_ACCESS_NET_CONNECT_TCP:
-		return "connect_tcp"
-
-	default:
-		var c []LandlockAccessNet
-		for i := LandlockAccessNet(1); i < _LANDLOCK_ACCESS_NET_DELIM; i <<= 1 {
-			if f&i != 0 {
-				c = append(c, i)
-			}
-		}
-		if len(c) == 0 {
-			return "NULL"
-		}
-		s := make([]string, len(c))
-		for i, v := range c {
-			s[i] = v.String()
-		}
-		return strings.Join(s, " ")
-	}
-}
-
-type LandlockScope uintptr
-
-const (
-	LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET LandlockScope = 1 << iota
-	LANDLOCK_SCOPE_SIGNAL
-
-	_LANDLOCK_SCOPE_DELIM
-)
-
-func (f LandlockScope) String() string {
-	switch f {
-	case LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET:
-		return "abstract_unix_socket"
-
-	case LANDLOCK_SCOPE_SIGNAL:
-		return "signal"
-
-	default:
-		var c []LandlockScope
-		for i := LandlockScope(1); i < _LANDLOCK_SCOPE_DELIM; i <<= 1 {
-			if f&i != 0 {
-				c = append(c, i)
-			}
-		}
-		if len(c) == 0 {
-			return "NULL"
-		}
-		s := make([]string, len(c))
-		for i, v := range c {
-			s[i] = v.String()
-		}
-		return strings.Join(s, " ")
-	}
-}
-
-type RulesetAttr struct {
-	// Bitmask of handled filesystem actions.
-	HandledAccessFS LandlockAccessFS
-	// Bitmask of handled network actions.
-	HandledAccessNet LandlockAccessNet
-	// Bitmask of scopes restricting a Landlock domain from accessing outside resources (e.g. IPCs).
-	Scoped LandlockScope
-}
-
-func (rulesetAttr *RulesetAttr) String() string {
-	if rulesetAttr == nil {
-		return "NULL"
-	}
-	elems := make([]string, 0, 3)
-	if rulesetAttr.HandledAccessFS > 0 {
-		elems = append(elems, "fs: "+rulesetAttr.HandledAccessFS.String())
-	}
-	if rulesetAttr.HandledAccessNet > 0 {
-		elems = append(elems, "net: "+rulesetAttr.HandledAccessNet.String())
-	}
-	if rulesetAttr.Scoped > 0 {
-		elems = append(elems, "scoped: "+rulesetAttr.Scoped.String())
-	}
-	if len(elems) == 0 {
-		return "0"
-	}
-	return strings.Join(elems, ", ")
-}
-
-func (rulesetAttr *RulesetAttr) Create(flags uintptr) (fd int, err error) {
 	var pointer, size uintptr
 	// NULL needed for abi version
 	if rulesetAttr != nil {
@@ -227,7 +47,7 @@ func (rulesetAttr *RulesetAttr) Create(flags uintptr) (fd int, err error) {
 }
 
 func LandlockGetABI() (int, error) {
-	return (*RulesetAttr)(nil).Create(LANDLOCK_CREATE_RULESET_VERSION)
+	return LandlockCreateRuleset(nil, LANDLOCK_CREATE_RULESET_VERSION)
 }
 
 func LandlockRestrictSelf(rulesetFd int, flags uintptr) error {

container/landlock_test.go

@@ -1,61 +0,0 @@
-package container_test
-
-import (
-	"testing"
-	"unsafe"
-
-	"hakurei.app/container"
-)
-
-func TestLandlockString(t *testing.T) {
-	testCases := []struct {
-		name        string
-		rulesetAttr *container.RulesetAttr
-		want        string
-	}{
-		{"nil", nil, "NULL"},
-		{"zero", new(container.RulesetAttr), "0"},
-		{"some", &container.RulesetAttr{Scoped: container.LANDLOCK_SCOPE_SIGNAL}, "scoped: signal"},
-		{"set", &container.RulesetAttr{
-			HandledAccessFS:  container.LANDLOCK_ACCESS_FS_MAKE_SYM | container.LANDLOCK_ACCESS_FS_IOCTL_DEV | container.LANDLOCK_ACCESS_FS_WRITE_FILE,
-			HandledAccessNet: container.LANDLOCK_ACCESS_NET_BIND_TCP,
-			Scoped:           container.LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET | container.LANDLOCK_SCOPE_SIGNAL,
-		}, "fs: write_file make_sym fs_ioctl_dev, net: bind_tcp, scoped: abstract_unix_socket signal"},
-		{"all", &container.RulesetAttr{
-			HandledAccessFS: container.LANDLOCK_ACCESS_FS_EXECUTE |
-				container.LANDLOCK_ACCESS_FS_WRITE_FILE |
-				container.LANDLOCK_ACCESS_FS_READ_FILE |
-				container.LANDLOCK_ACCESS_FS_READ_DIR |
-				container.LANDLOCK_ACCESS_FS_REMOVE_DIR |
-				container.LANDLOCK_ACCESS_FS_REMOVE_FILE |
-				container.LANDLOCK_ACCESS_FS_MAKE_CHAR |
-				container.LANDLOCK_ACCESS_FS_MAKE_DIR |
-				container.LANDLOCK_ACCESS_FS_MAKE_REG |
-				container.LANDLOCK_ACCESS_FS_MAKE_SOCK |
-				container.LANDLOCK_ACCESS_FS_MAKE_FIFO |
-				container.LANDLOCK_ACCESS_FS_MAKE_BLOCK |
-				container.LANDLOCK_ACCESS_FS_MAKE_SYM |
-				container.LANDLOCK_ACCESS_FS_REFER |
-				container.LANDLOCK_ACCESS_FS_TRUNCATE |
-				container.LANDLOCK_ACCESS_FS_IOCTL_DEV,
-			HandledAccessNet: container.LANDLOCK_ACCESS_NET_BIND_TCP |
-				container.LANDLOCK_ACCESS_NET_CONNECT_TCP,
-			Scoped: container.LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET |
-				container.LANDLOCK_SCOPE_SIGNAL,
-		}, "fs: execute write_file read_file read_dir remove_dir remove_file make_char make_dir make_reg make_sock make_fifo make_block make_sym fs_refer fs_truncate fs_ioctl_dev, net: bind_tcp connect_tcp, scoped: abstract_unix_socket signal"},
-	}
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			if got := tc.rulesetAttr.String(); got != tc.want {
-				t.Errorf("String: %s, want %s", got, tc.want)
-			}
-		})
-	}
-}
-
-func TestLandlockAttrSize(t *testing.T) {
-	want := 24
-	if got := unsafe.Sizeof(container.RulesetAttr{}); got != uintptr(want) {
-		t.Errorf("Sizeof: %d, want %d", got, want)
-	}
-}