// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package seccomp

import (
	"fmt"
	"syscall"
	"testing"

	specs "github.com/opencontainers/runtime-spec/specs-go"
	"gvisor.dev/gvisor/pkg/binary"
	"gvisor.dev/gvisor/pkg/bpf"
)

type seccompData struct {
	nr                 uint32
	arch               uint32
	instructionPointer uint64
	args               [6]uint64
}

// asInput converts a seccompData to a bpf.Input.
func asInput(d seccompData) bpf.Input {
	return bpf.InputBytes{binary.Marshal(nil, binary.LittleEndian, d), binary.LittleEndian}
}

// testInput creates an Input struct with given seccomp input values.
func testInput(arch uint32, syscallName string, args *[6]uint64) bpf.Input {
	syscallNo, err := lookupSyscallNo(arch, syscallName)
	if err != nil {
		// Assume tests set valid syscall names.
		panic(err)
	}

	if args == nil {
		argArray := [6]uint64{0, 0, 0, 0, 0, 0}
		args = &argArray
	}

	data := seccompData{
		nr:   syscallNo,
		arch: arch,
		args: *args,
	}

	return asInput(data)
}

// testCase holds a seccomp test case.
type testCase struct {
	name     string
	config   specs.LinuxSeccomp
	input    bpf.Input
	expected uint32
}

var (
	// seccompTests is a list of speccomp test cases.
	seccompTests = []testCase{
		{
			name: "default_allow",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
			},
			input:    testInput(nativeArchAuditNo, "read", nil),
			expected: uint32(allowAction),
		},
		{
			name: "default_deny",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActErrno,
			},
			input:    testInput(nativeArchAuditNo, "read", nil),
			expected: uint32(errnoAction),
		},
		{
			name: "deny_arch",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getcwd",
						},
						Action: specs.ActErrno,
					},
				},
			},
			// Syscall matches but the arch is AUDIT_ARCH_X86 so the return
			// value is the bad arch action.
			input:    asInput(seccompData{nr: 183, arch: 0x40000003}), //
			expected: uint32(killThreadAction),
		},
		{
			name: "match_name_errno",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getcwd",
							"chmod",
						},
						Action: specs.ActErrno,
					},
					{
						Names: []string{
							"write",
						},
						Action: specs.ActTrace,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "getcwd", nil),
			expected: uint32(errnoAction),
		},
		{
			name: "match_name_trace",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getcwd",
							"chmod",
						},
						Action: specs.ActErrno,
					},
					{
						Names: []string{
							"write",
						},
						Action: specs.ActTrace,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "write", nil),
			expected: uint32(traceAction),
		},
		{
			name: "no_match_name_allow",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getcwd",
							"chmod",
						},
						Action: specs.ActErrno,
					},
					{
						Names: []string{
							"write",
						},
						Action: specs.ActTrace,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "open", nil),
			expected: uint32(allowAction),
		},
		{
			name: "simple_match_args",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index: 0,
								Value: syscall.CLONE_FS,
								Op:    specs.OpEqualTo,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{syscall.CLONE_FS}),
			expected: uint32(errnoAction),
		},
		{
			name: "match_args_or",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index: 0,
								Value: syscall.CLONE_FS,
								Op:    specs.OpEqualTo,
							},
							{
								Index: 0,
								Value: syscall.CLONE_VM,
								Op:    specs.OpEqualTo,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{syscall.CLONE_FS}),
			expected: uint32(errnoAction),
		},
		{
			name: "match_args_and",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getsockopt",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index: 1,
								Value: syscall.SOL_SOCKET,
								Op:    specs.OpEqualTo,
							},
							{
								Index: 2,
								Value: syscall.SO_PEERCRED,
								Op:    specs.OpEqualTo,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "getsockopt", &[6]uint64{0, syscall.SOL_SOCKET, syscall.SO_PEERCRED}),
			expected: uint32(errnoAction),
		},
		{
			name: "no_match_args_and",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"getsockopt",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index: 1,
								Value: syscall.SOL_SOCKET,
								Op:    specs.OpEqualTo,
							},
							{
								Index: 2,
								Value: syscall.SO_PEERCRED,
								Op:    specs.OpEqualTo,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "getsockopt", &[6]uint64{0, syscall.SOL_SOCKET}),
			expected: uint32(allowAction),
		},
		{
			name: "Simple args (no match)",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index: 0,
								Value: syscall.CLONE_FS,
								Op:    specs.OpEqualTo,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{syscall.CLONE_VM}),
			expected: uint32(allowAction),
		},
		{
			name: "OpMaskedEqual (match)",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index:    0,
								Value:    syscall.CLONE_FS,
								ValueTwo: syscall.CLONE_FS,
								Op:       specs.OpMaskedEqual,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{syscall.CLONE_FS | syscall.CLONE_VM}),
			expected: uint32(errnoAction),
		},
		{
			name: "OpMaskedEqual (no match)",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActAllow,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						Args: []specs.LinuxSeccompArg{
							{
								Index:    0,
								Value:    syscall.CLONE_FS | syscall.CLONE_VM,
								ValueTwo: syscall.CLONE_FS | syscall.CLONE_VM,
								Op:       specs.OpMaskedEqual,
							},
						},
						Action: specs.ActErrno,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{syscall.CLONE_FS}),
			expected: uint32(allowAction),
		},
		{
			name: "OpMaskedEqual (clone)",
			config: specs.LinuxSeccomp{
				DefaultAction: specs.ActErrno,
				Syscalls: []specs.LinuxSyscall{
					{
						Names: []string{
							"clone",
						},
						// This comes from the Docker default seccomp
						// profile for clone.
						Args: []specs.LinuxSeccompArg{
							{
								Index:    0,
								Value:    0x7e020000,
								ValueTwo: 0x0,
								Op:       specs.OpMaskedEqual,
							},
						},
						Action: specs.ActAllow,
					},
				},
			},
			input:    testInput(nativeArchAuditNo, "clone", &[6]uint64{0x50f00}),
			expected: uint32(allowAction),
		},
	}
)

// TestRunscSeccomp generates seccomp programs from OCI config and executes
// them using runsc's library, comparing against expected results.
func TestRunscSeccomp(t *testing.T) {
	for _, tc := range seccompTests {
		t.Run(tc.name, func(t *testing.T) {
			runscProgram, err := BuildProgram(&tc.config)
			if err != nil {
				t.Fatalf("generating runsc BPF: %v", err)
			}

			if err := checkProgram(runscProgram, tc.input, tc.expected); err != nil {
				t.Fatalf("running runsc BPF: %v", err)
			}
		})
	}
}

// checkProgram runs the given program over the given input and checks the
// result against the expected output.
func checkProgram(p bpf.Program, in bpf.Input, expected uint32) error {
	result, err := bpf.Exec(p, in)
	if err != nil {
		return err
	}

	if result != expected {
		// Include a decoded version of the program in output for debugging purposes.
		decoded, _ := bpf.DecodeProgram(p)
		return fmt.Errorf("Unexpected result: got: %d, expected: %d\nBPF Program\n%s", result, expected, decoded)
	}

	return nil
}