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>

1 files changed, 259 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
+}