helper/seccomp: implement reader interface via pipe

This also does not require the libc tmpfile call.

BPF programs emitted by libseccomp seems to be deterministic. The tests would catch regressions as it verifies the program against known good output backed by manual testing.

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

1 files changed, 123 insertions, 0 deletions

diff --git a/helper/seccomp/export_test.go b/helper/seccomp/export_test.go
new file mode 100644
index 00000000..bbafa3b1
--- /dev/null
+++ b/helper/seccomp/export_test.go
@@ -0,0 +1,123 @@
+package seccomp_test
+
+import (
+	"crypto/sha512"
+	"errors"
+	"io"
+	"slices"
+	"syscall"
+	"testing"
+
+	"git.gensokyo.uk/security/fortify/helper/seccomp"
+	"git.gensokyo.uk/security/fortify/internal/fmsg"
+)
+
+func TestExport(t *testing.T) {
+	testCases := []struct {
+		name    string
+		opts    seccomp.SyscallOpts
+		want    []byte
+		wantErr bool
+	}{
+		{"compat", 0, []byte{
+			0x95, 0xec, 0x69, 0xd0, 0x17, 0x73, 0x3e, 0x07,
+			0x21, 0x60, 0xe0, 0xda, 0x80, 0xfd, 0xeb, 0xec,
+			0xdf, 0x27, 0xae, 0x81, 0x66, 0xf5, 0xe2, 0xa7,
+			0x31, 0x27, 0x0c, 0x98, 0xea, 0x2d, 0x29, 0x46,
+			0xcb, 0x52, 0x31, 0x02, 0x90, 0x63, 0x66, 0x8a,
+			0xf2, 0x15, 0x87, 0x91, 0x55, 0xda, 0x21, 0xac,
+			0xa7, 0x9b, 0x07, 0x0e, 0x04, 0xc0, 0xee, 0x9a,
+			0xcd, 0xf5, 0x8f, 0x55, 0xcf, 0xa8, 0x15, 0xa5,
+		}, false},
+		{"base", seccomp.FlagExt, []byte{
+			0xdc, 0x7f, 0x2e, 0x1c, 0x5e, 0x82, 0x9b, 0x79,
+			0xeb, 0xb7, 0xef, 0xc7, 0x59, 0x15, 0x0f, 0x54,
+			0xa8, 0x3a, 0x75, 0xc8, 0xdf, 0x6f, 0xee, 0x4d,
+			0xce, 0x5d, 0xad, 0xc4, 0x73, 0x6c, 0x58, 0x5d,
+			0x4d, 0xee, 0xbf, 0xeb, 0x3c, 0x79, 0x69, 0xaf,
+			0x3a, 0x07, 0x7e, 0x90, 0xb7, 0x7b, 0xb4, 0x74,
+			0x1d, 0xb0, 0x5d, 0x90, 0x99, 0x7c, 0x86, 0x59,
+			0xb9, 0x58, 0x91, 0x20, 0x6a, 0xc9, 0x95, 0x2d,
+		}, false},
+		{"everything", seccomp.FlagExt |
+			seccomp.FlagDenyNS | seccomp.FlagDenyTTY | seccomp.FlagDenyDevel |
+			seccomp.FlagMultiarch | seccomp.FlagLinux32 | seccomp.FlagCan |
+			seccomp.FlagBluetooth, []byte{
+			0xe9, 0x9d, 0xd3, 0x45, 0xe1, 0x95, 0x41, 0x34,
+			0x73, 0xd3, 0xcb, 0xee, 0x07, 0xb4, 0xed, 0x57,
+			0xb9, 0x08, 0xbf, 0xa8, 0x9e, 0xa2, 0x07, 0x2f,
+			0xe9, 0x34, 0x82, 0x84, 0x7f, 0x50, 0xb5, 0xb7,
+			0x58, 0xda, 0x17, 0xe7, 0x4c, 0xa2, 0xbb, 0xc0,
+			0x08, 0x13, 0xde, 0x49, 0xa2, 0xb9, 0xbf, 0x83,
+			0x4c, 0x02, 0x4e, 0xd4, 0x88, 0x50, 0xbe, 0x69,
+			0xb6, 0x8a, 0x9a, 0x4c, 0x5f, 0x53, 0xa9, 0xdb,
+		}, false},
+		{"strict", seccomp.FlagExt |
+			seccomp.FlagDenyNS | seccomp.FlagDenyTTY | seccomp.FlagDenyDevel, []byte{
+			0xe8, 0x80, 0x29, 0x8d, 0xf2, 0xbd, 0x67, 0x51,
+			0xd0, 0x04, 0x0f, 0xc2, 0x1b, 0xc0, 0xed, 0x4c,
+			0x00, 0xf9, 0x5d, 0xc0, 0xd7, 0xba, 0x50, 0x6c,
+			0x24, 0x4d, 0x8b, 0x8c, 0xf6, 0x86, 0x6d, 0xba,
+			0x8e, 0xf4, 0xa3, 0x32, 0x96, 0xf2, 0x87, 0xb6,
+			0x6c, 0xcc, 0xc1, 0xd7, 0x8e, 0x97, 0x02, 0x65,
+			0x97, 0xf8, 0x4c, 0xc7, 0xde, 0xc1, 0x57, 0x3e,
+			0x14, 0x89, 0x60, 0xfb, 0xd3, 0x5c, 0xd7, 0x35,
+		}, false},
+		{"strict compat", 0 |
+			seccomp.FlagDenyNS | seccomp.FlagDenyTTY | seccomp.FlagDenyDevel, []byte{
+			0x39, 0x87, 0x1b, 0x93, 0xff, 0xaf, 0xc8, 0xb9,
+			0x79, 0xfc, 0xed, 0xc0, 0xb0, 0xc3, 0x7b, 0x9e,
+			0x03, 0x92, 0x2f, 0x5b, 0x02, 0x74, 0x8d, 0xc5,
+			0xc3, 0xc1, 0x7c, 0x92, 0x52, 0x7f, 0x6e, 0x02,
+			0x2e, 0xde, 0x1f, 0x48, 0xbf, 0xf5, 0x92, 0x46,
+			0xea, 0x45, 0x2c, 0x0d, 0x1d, 0xe5, 0x48, 0x27,
+			0x80, 0x8b, 0x1a, 0x6f, 0x84, 0xf3, 0x2b, 0xbd,
+			0xe1, 0xaa, 0x02, 0xae, 0x30, 0xee, 0xdc, 0xfa,
+		}, false},
+	}
+
+	buf := make([]byte, 8)
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			seccomp.CPrintln = fmsg.Println
+			t.Cleanup(func() { seccomp.CPrintln = nil })
+
+			e := seccomp.New(tc.opts)
+			digest := sha512.New()
+
+			if _, err := io.CopyBuffer(digest, e, buf); (err != nil) != tc.wantErr {
+				t.Errorf("Exporter: error = %v, wantErr %v", err, tc.wantErr)
+				return
+			}
+			if err := e.Close(); err != nil {
+				t.Errorf("Close: error = %v", err)
+				return
+			}
+			if got := digest.Sum(nil); slices.Compare(got, tc.want) != 0 {
+				t.Fatalf("Export() hash = %x, want %x",
+					got, tc.want)
+				return
+			}
+		})
+	}
+
+	t.Run("close without use", func(t *testing.T) {
+		e := seccomp.New(0)
+		if err := e.Close(); !errors.Is(err, syscall.EINVAL) {
+			t.Errorf("Close: error = %v", err)
+			return
+		}
+	})
+
+	t.Run("close partial read", func(t *testing.T) {
+		e := seccomp.New(0)
+		if _, err := e.Read(make([]byte, 0)); err != nil {
+			t.Errorf("Read: error = %v", err)
+			return
+		}
+		if err := e.Close(); err == nil || err.Error() != "seccomp_export_bpf failed: operation canceled" {
+			t.Errorf("Close: error = %v", err)
+			return
+		}
+	})
+}