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// +build seccomp
package seccomp
import (
"encoding/json"
"errors"
"fmt"
"github.com/docker/docker/pkg/stringutils"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/opencontainers/runtime-tools/generate"
libseccomp "github.com/seccomp/libseccomp-golang"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
// IsEnabled returns true if seccomp is enabled for the host.
func IsEnabled() bool {
enabled := false
// 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 {
enabled = true
}
}
logrus.Debugf("seccomp status: %v", enabled)
return enabled
}
// LoadProfileFromStruct takes a Seccomp struct and setup seccomp in the spec.
func LoadProfileFromStruct(config Seccomp, specgen *generate.Generator) error {
return setupSeccomp(&config, specgen)
}
// LoadProfileFromBytes takes a byte slice and decodes the seccomp profile.
func LoadProfileFromBytes(body []byte, specgen *generate.Generator) error {
var config Seccomp
if err := json.Unmarshal(body, &config); err != nil {
return fmt.Errorf("decoding seccomp profile failed: %v", err)
}
return setupSeccomp(&config, specgen)
}
var nativeToSeccomp = map[string]Arch{
"amd64": ArchX86_64,
"arm64": ArchAARCH64,
"mips64": ArchMIPS64,
"mips64n32": ArchMIPS64N32,
"mipsel64": ArchMIPSEL64,
"mipsel64n32": ArchMIPSEL64N32,
"s390x": ArchS390X,
}
func setupSeccomp(config *Seccomp, specgen *generate.Generator) error {
if config == nil {
return nil
}
// No default action specified, no syscalls listed, assume seccomp disabled
if config.DefaultAction == "" && len(config.Syscalls) == 0 {
return nil
}
var arch string
var native, err = libseccomp.GetNativeArch()
if err == nil {
arch = native.String()
}
if len(config.Architectures) != 0 && len(config.ArchMap) != 0 {
return errors.New("'architectures' and 'archMap' were specified in the seccomp profile, use either 'architectures' or 'archMap'")
}
customspec := specgen.Spec()
customspec.Linux.Seccomp = &specs.LinuxSeccomp{}
// if config.Architectures == 0 then libseccomp will figure out the architecture to use
if len(config.Architectures) != 0 {
for _, a := range config.Architectures {
customspec.Linux.Seccomp.Architectures = append(customspec.Linux.Seccomp.Architectures, specs.Arch(a))
}
}
if len(config.ArchMap) != 0 {
for _, a := range config.ArchMap {
seccompArch, ok := nativeToSeccomp[arch]
if ok {
if a.Arch == seccompArch {
customspec.Linux.Seccomp.Architectures = append(customspec.Linux.Seccomp.Architectures, specs.Arch(a.Arch))
for _, sa := range a.SubArches {
customspec.Linux.Seccomp.Architectures = append(customspec.Linux.Seccomp.Architectures, specs.Arch(sa))
}
break
}
}
}
}
customspec.Linux.Seccomp.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 stringutils.InSlice(call.Excludes.Arches, arch) {
continue Loop
}
}
if len(call.Excludes.Caps) > 0 {
for _, c := range call.Excludes.Caps {
if stringutils.InSlice(customspec.Process.Capabilities.Permitted, c) {
continue Loop
}
}
}
if len(call.Includes.Arches) > 0 {
if !stringutils.InSlice(call.Includes.Arches, arch) {
continue Loop
}
}
if len(call.Includes.Caps) > 0 {
for _, c := range call.Includes.Caps {
if !stringutils.InSlice(customspec.Process.Capabilities.Permitted, c) {
continue Loop
}
}
}
if call.Name != "" && len(call.Names) != 0 {
return errors.New("'name' and 'names' were specified in the seccomp profile, use either 'name' or 'names'")
}
if call.Name != "" {
customspec.Linux.Seccomp.Syscalls = append(customspec.Linux.Seccomp.Syscalls, createSpecsSyscall(call.Name, call.Action, call.Args))
}
for _, n := range call.Names {
customspec.Linux.Seccomp.Syscalls = append(customspec.Linux.Seccomp.Syscalls, createSpecsSyscall(n, call.Action, call.Args))
}
}
return nil
}
func createSpecsSyscall(name string, action Action, args []*Arg) specs.LinuxSyscall {
newCall := specs.LinuxSyscall{
Names: []string{name},
Action: specs.LinuxSeccompAction(action),
}
// 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
}
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