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// +build seccomp
// SPDX-License-Identifier: Apache-2.0
// Copyright 2013-2018 Docker, Inc.
package seccomp // import "github.com/seccomp/containers-golang"
import (
"encoding/json"
"errors"
"fmt"
"github.com/opencontainers/runtime-spec/specs-go"
libseccomp "github.com/seccomp/libseccomp-golang"
"golang.org/x/sys/unix"
)
//go:generate go run -tags 'seccomp' generate.go
// GetDefaultProfile returns the default seccomp profile.
func GetDefaultProfile(rs *specs.Spec) (*specs.LinuxSeccomp, error) {
return setupSeccomp(DefaultProfile(), rs)
}
// LoadProfile takes a json string and decodes the seccomp profile.
func LoadProfile(body string, rs *specs.Spec) (*specs.LinuxSeccomp, error) {
var config Seccomp
if err := json.Unmarshal([]byte(body), &config); err != nil {
return nil, fmt.Errorf("decoding seccomp profile failed: %v", err)
}
return setupSeccomp(&config, rs)
}
// LoadProfileFromBytes takes a byte slice and decodes the seccomp profile.
func LoadProfileFromBytes(body []byte, rs *specs.Spec) (*specs.LinuxSeccomp, error) {
config := &Seccomp{}
if err := json.Unmarshal(body, config); err != nil {
return nil, fmt.Errorf("decoding seccomp profile failed: %v", err)
}
return setupSeccomp(config, rs)
}
// LoadProfileFromConfig takes a Seccomp struct and a spec to retrieve a LinuxSeccomp
func LoadProfileFromConfig(config *Seccomp, specgen *specs.Spec) (*specs.LinuxSeccomp, error) {
return setupSeccomp(config, specgen)
}
var nativeToSeccomp = map[string]Arch{
"amd64": ArchX86_64,
"arm64": ArchAARCH64,
"mips64": ArchMIPS64,
"mips64n32": ArchMIPS64N32,
"mipsel64": ArchMIPSEL64,
"mipsel64n32": ArchMIPSEL64N32,
"s390x": ArchS390X,
}
// inSlice tests whether a string is contained in a slice of strings or not.
// Comparison is case sensitive
func inSlice(slice []string, s string) bool {
for _, ss := range slice {
if s == ss {
return true
}
}
return false
}
func setupSeccomp(config *Seccomp, rs *specs.Spec) (*specs.LinuxSeccomp, error) {
if config == nil {
return nil, nil
}
// No default action specified, no syscalls listed, assume seccomp disabled
if config.DefaultAction == "" && len(config.Syscalls) == 0 {
return nil, nil
}
newConfig := &specs.LinuxSeccomp{}
var arch string
var native, err = libseccomp.GetNativeArch()
if err == nil {
arch = native.String()
}
if len(config.Architectures) != 0 && len(config.ArchMap) != 0 {
return nil, errors.New("'architectures' and 'archMap' were specified in the seccomp profile, use either 'architectures' or 'archMap'")
}
// if config.Architectures == 0 then libseccomp will figure out the architecture to use
if len(config.Architectures) != 0 {
for _, a := range config.Architectures {
newConfig.Architectures = append(newConfig.Architectures, specs.Arch(a))
}
}
if len(config.ArchMap) != 0 {
for _, a := range config.ArchMap {
seccompArch, ok := nativeToSeccomp[arch]
if ok {
if a.Arch == seccompArch {
newConfig.Architectures = append(newConfig.Architectures, specs.Arch(a.Arch))
for _, sa := range a.SubArches {
newConfig.Architectures = append(newConfig.Architectures, specs.Arch(sa))
}
break
}
}
}
}
newConfig.DefaultAction = specs.LinuxSeccompAction(config.DefaultAction)
Loop:
// Loop through all syscall blocks and convert them to libcontainer format after filtering them
for _, call := range config.Syscalls {
if len(call.Excludes.Arches) > 0 {
if inSlice(call.Excludes.Arches, arch) {
continue Loop
}
}
if len(call.Excludes.Caps) > 0 {
for _, c := range call.Excludes.Caps {
if inSlice(rs.Process.Capabilities.Bounding, c) {
continue Loop
}
}
}
if len(call.Includes.Arches) > 0 {
if !inSlice(call.Includes.Arches, arch) {
continue Loop
}
}
if len(call.Includes.Caps) > 0 {
for _, c := range call.Includes.Caps {
if !inSlice(rs.Process.Capabilities.Bounding, c) {
continue Loop
}
}
}
if call.Name != "" && len(call.Names) != 0 {
return nil, errors.New("'name' and 'names' were specified in the seccomp profile, use either 'name' or 'names'")
}
if call.Name != "" {
newConfig.Syscalls = append(newConfig.Syscalls, createSpecsSyscall([]string{call.Name}, call.Action, call.Args, call.ErrnoRet))
}
if len(call.Names) > 0 {
newConfig.Syscalls = append(newConfig.Syscalls, createSpecsSyscall(call.Names, call.Action, call.Args, call.ErrnoRet))
}
}
return newConfig, nil
}
func createSpecsSyscall(names []string, action Action, args []*Arg, errnoRet *uint) specs.LinuxSyscall {
newCall := specs.LinuxSyscall{
Names: names,
Action: specs.LinuxSeccompAction(action),
ErrnoRet: errnoRet,
}
// Loop through all the arguments of the syscall and convert them
for _, arg := range args {
newArg := specs.LinuxSeccompArg{
Index: arg.Index,
Value: arg.Value,
ValueTwo: arg.ValueTwo,
Op: specs.LinuxSeccompOperator(arg.Op),
}
newCall.Args = append(newCall.Args, newArg)
}
return newCall
}
// IsEnabled returns true if seccomp is enabled for the host.
func IsEnabled() bool {
// Check if Seccomp is supported, via CONFIG_SECCOMP.
if err := unix.Prctl(unix.PR_GET_SECCOMP, 0, 0, 0, 0); err != unix.EINVAL {
// Make sure the kernel has CONFIG_SECCOMP_FILTER.
if err := unix.Prctl(unix.PR_SET_SECCOMP, unix.SECCOMP_MODE_FILTER, 0, 0, 0); err != unix.EINVAL {
return true
}
}
return false
}
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