internal/landlock: relocate from package container

This is not possible to use directly, so remove it from the public API.

Signed-off-by: Ophestra <cat@gensokyo.uk>

2 files changed, 324 insertions, 0 deletions

diff --git a/internal/landlock/landlock.go b/internal/landlock/landlock.go
new file mode 100644
index 00000000..b65e3ebe
--- /dev/null
+++ b/internal/landlock/landlock.go
@@ -0,0 +1,259 @@
+package landlock
+
+import (
+	"strings"
+	"syscall"
+	"unsafe"
+
+	"hakurei.app/ext"
+)
+
+// include/uapi/linux/landlock.h
+
+const (
+	LANDLOCK_CREATE_RULESET_VERSION = 1 << iota
+)
+
+// AccessFS is bitmask of handled filesystem actions.
+type AccessFS uint64
+
+const (
+	LANDLOCK_ACCESS_FS_EXECUTE AccessFS = 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
+)
+
+// String returns a space-separated string of [AccessFS] flags.
+func (f AccessFS) String() string {
+	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 []AccessFS
+		for i := AccessFS(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, " ")
+	}
+}
+
+// AccessNet is bitmask of handled network actions.
+type AccessNet uint64
+
+const (
+	LANDLOCK_ACCESS_NET_BIND_TCP AccessNet = 1 << iota
+	LANDLOCK_ACCESS_NET_CONNECT_TCP
+
+	_LANDLOCK_ACCESS_NET_DELIM
+)
+
+// String returns a space-separated string of [AccessNet] flags.
+func (f AccessNet) 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 []AccessNet
+		for i := AccessNet(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, " ")
+	}
+}
+
+// Scope is bitmask of scopes restricting a Landlock domain from accessing outside resources.
+type Scope uint64
+
+const (
+	LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET Scope = 1 << iota
+	LANDLOCK_SCOPE_SIGNAL
+
+	_LANDLOCK_SCOPE_DELIM
+)
+
+// String returns a space-separated string of [Scope] flags.
+func (f Scope) String() string {
+	switch f {
+	case LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET:
+		return "abstract_unix_socket"
+
+	case LANDLOCK_SCOPE_SIGNAL:
+		return "signal"
+
+	default:
+		var c []Scope
+		for i := Scope(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, " ")
+	}
+}
+
+// RulesetAttr is equivalent to struct landlock_ruleset_attr.
+type RulesetAttr struct {
+	// Bitmask of handled filesystem actions.
+	HandledAccessFS AccessFS
+	// Bitmask of handled network actions.
+	HandledAccessNet AccessNet
+	// Bitmask of scopes restricting a Landlock domain from accessing outside
+	// resources (e.g. IPCs).
+	Scoped Scope
+}
+
+// String returns a user-facing description of [RulesetAttr].
+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, ", ")
+}
+
+// Create loads the ruleset into the kernel.
+func (rulesetAttr *RulesetAttr) Create(flags uintptr) (fd int, err error) {
+	var pointer, size uintptr
+	// NULL needed for abi version
+	if rulesetAttr != nil {
+		pointer = uintptr(unsafe.Pointer(rulesetAttr))
+		size = unsafe.Sizeof(*rulesetAttr)
+	}
+
+	rulesetFd, _, errno := syscall.Syscall(
+		ext.SYS_LANDLOCK_CREATE_RULESET,
+		pointer, size,
+		flags,
+	)
+	fd = int(rulesetFd)
+	err = errno
+	if fd < 0 {
+		return
+	}
+
+	if rulesetAttr != nil { // not a fd otherwise
+		syscall.CloseOnExec(fd)
+	}
+	return fd, nil
+}
+
+// GetABI returns the ABI version supported by the kernel.
+func GetABI() (int, error) {
+	return (*RulesetAttr)(nil).Create(LANDLOCK_CREATE_RULESET_VERSION)
+}
+
+// RestrictSelf applies a loaded ruleset to the calling thread.
+func RestrictSelf(rulesetFd int, flags uintptr) error {
+	r, _, errno := syscall.Syscall(
+		ext.SYS_LANDLOCK_RESTRICT_SELF,
+		uintptr(rulesetFd),
+		flags,
+		0,
+	)
+	if r != 0 {
+		return errno
+	}
+	return nil
+}
diff --git a/internal/landlock/landlock_test.go b/internal/landlock/landlock_test.go
new file mode 100644
index 00000000..6f30fc6b
--- /dev/null
+++ b/internal/landlock/landlock_test.go
@@ -0,0 +1,65 @@
+package landlock_test
+
+import (
+	"testing"
+	"unsafe"
+
+	"hakurei.app/internal/landlock"
+)
+
+func TestLandlockString(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		name        string
+		rulesetAttr *landlock.RulesetAttr
+		want        string
+	}{
+		{"nil", nil, "NULL"},
+		{"zero", new(landlock.RulesetAttr), "0"},
+		{"some", &landlock.RulesetAttr{Scoped: landlock.LANDLOCK_SCOPE_SIGNAL}, "scoped: signal"},
+		{"set", &landlock.RulesetAttr{
+			HandledAccessFS:  landlock.LANDLOCK_ACCESS_FS_MAKE_SYM | landlock.LANDLOCK_ACCESS_FS_IOCTL_DEV | landlock.LANDLOCK_ACCESS_FS_WRITE_FILE,
+			HandledAccessNet: landlock.LANDLOCK_ACCESS_NET_BIND_TCP,
+			Scoped:           landlock.LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET | landlock.LANDLOCK_SCOPE_SIGNAL,
+		}, "fs: write_file make_sym fs_ioctl_dev, net: bind_tcp, scoped: abstract_unix_socket signal"},
+		{"all", &landlock.RulesetAttr{
+			HandledAccessFS: landlock.LANDLOCK_ACCESS_FS_EXECUTE |
+				landlock.LANDLOCK_ACCESS_FS_WRITE_FILE |
+				landlock.LANDLOCK_ACCESS_FS_READ_FILE |
+				landlock.LANDLOCK_ACCESS_FS_READ_DIR |
+				landlock.LANDLOCK_ACCESS_FS_REMOVE_DIR |
+				landlock.LANDLOCK_ACCESS_FS_REMOVE_FILE |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_CHAR |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_DIR |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_REG |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_SOCK |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_FIFO |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_BLOCK |
+				landlock.LANDLOCK_ACCESS_FS_MAKE_SYM |
+				landlock.LANDLOCK_ACCESS_FS_REFER |
+				landlock.LANDLOCK_ACCESS_FS_TRUNCATE |
+				landlock.LANDLOCK_ACCESS_FS_IOCTL_DEV,
+			HandledAccessNet: landlock.LANDLOCK_ACCESS_NET_BIND_TCP |
+				landlock.LANDLOCK_ACCESS_NET_CONNECT_TCP,
+			Scoped: landlock.LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET |
+				landlock.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) {
+			t.Parallel()
+			if got := tc.rulesetAttr.String(); got != tc.want {
+				t.Errorf("String: %s, want %s", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestLandlockAttrSize(t *testing.T) {
+	t.Parallel()
+	want := 24
+	if got := unsafe.Sizeof(landlock.RulesetAttr{}); got != uintptr(want) {
+		t.Errorf("Sizeof: %d, want %d", got, want)
+	}
+}