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package security
import (
"context"
"fmt"
"os"
"sync"
"github.com/containerd/containerd/containers"
"github.com/containerd/containerd/oci"
"github.com/containerd/containerd/pkg/cap"
"github.com/containerd/containerd/pkg/userns"
"github.com/moby/buildkit/util/bklog"
specs "github.com/opencontainers/runtime-spec/specs-go"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
)
// WithInsecureSpec sets spec with All capability.
func WithInsecureSpec() oci.SpecOpts {
return func(ctx context.Context, _ oci.Client, _ *containers.Container, s *specs.Spec) error {
addCaps, err := getAllCaps(ctx)
if err != nil {
return err
}
s.Process.Capabilities.Bounding = append(s.Process.Capabilities.Bounding, addCaps...)
s.Process.Capabilities.Ambient = append(s.Process.Capabilities.Ambient, addCaps...)
s.Process.Capabilities.Effective = append(s.Process.Capabilities.Effective, addCaps...)
s.Process.Capabilities.Inheritable = append(s.Process.Capabilities.Inheritable, addCaps...)
s.Process.Capabilities.Permitted = append(s.Process.Capabilities.Permitted, addCaps...)
s.Linux.ReadonlyPaths = []string{}
s.Linux.MaskedPaths = []string{}
s.Process.ApparmorProfile = ""
s.Linux.Resources.Devices = []specs.LinuxDeviceCgroup{
{
Allow: true,
Type: "c",
Access: "rwm",
},
{
Allow: true,
Type: "b",
Access: "rwm",
},
}
if !userns.RunningInUserNS() {
// Devices automatically mounted on insecure mode
s.Linux.Devices = append(s.Linux.Devices, []specs.LinuxDevice{
// Writes to this come out as printk's, reads export the buffered printk records. (dmesg)
{
Path: "/dev/kmsg",
Type: "c",
Major: 1,
Minor: 11,
},
// Cuse (character device in user-space)
{
Path: "/dev/cuse",
Type: "c",
Major: 10,
Minor: 203,
},
// Fuse (virtual filesystem in user-space)
{
Path: "/dev/fuse",
Type: "c",
Major: 10,
Minor: 229,
},
// Kernel-based virtual machine (hardware virtualization extensions)
{
Path: "/dev/kvm",
Type: "c",
Major: 10,
Minor: 232,
},
// TAP/TUN network device
{
Path: "/dev/net/tun",
Type: "c",
Major: 10,
Minor: 200,
},
// Loopback control device
{
Path: "/dev/loop-control",
Type: "c",
Major: 10,
Minor: 237,
},
}...)
loopID, err := getFreeLoopID()
if err != nil {
bklog.G(ctx).Debugf("failed to get next free loop device: %v", err)
}
for i := 0; i <= loopID+7; i++ {
s.Linux.Devices = append(s.Linux.Devices, specs.LinuxDevice{
Path: fmt.Sprintf("/dev/loop%d", i),
Type: "b",
Major: 7,
Minor: int64(i),
})
}
}
return nil
}
}
func getFreeLoopID() (int, error) {
fd, err := os.OpenFile("/dev/loop-control", os.O_RDWR, 0644)
if err != nil {
return 0, err
}
defer fd.Close()
const _LOOP_CTL_GET_FREE = 0x4C82 //nolint:revive
r1, _, uerr := unix.Syscall(unix.SYS_IOCTL, fd.Fd(), _LOOP_CTL_GET_FREE, 0)
if uerr == 0 {
return int(r1), nil
}
return 0, errors.Errorf("error getting free loop device: %v", uerr)
}
var (
currentCaps []string
currentCapsError error //nolint:errname
currentCapsOnce sync.Once
)
func getCurrentCaps() ([]string, error) {
currentCapsOnce.Do(func() {
currentCaps, currentCapsError = cap.Current()
})
return currentCaps, currentCapsError
}
func getAllCaps(ctx context.Context) ([]string, error) {
availableCaps, err := getCurrentCaps()
if err != nil {
return nil, errors.Errorf("error getting current capabilities: %s", err)
}
// see if any of the base linux35Caps are not available to be granted
// they are either not supported by the kernel or dropped at the process level
for _, cap := range availableCaps {
if _, exists := linux35Caps[cap]; !exists {
bklog.G(ctx).Warnf("capability %s could not be granted for insecure mode", cap)
}
}
return availableCaps, nil
}
// linux35Caps provides a list of capabilities available on Linux 3.5 kernel
var linux35Caps = map[string]struct{}{
"CAP_FSETID": {},
"CAP_KILL": {},
"CAP_FOWNER": {},
"CAP_MKNOD": {},
"CAP_CHOWN": {},
"CAP_DAC_OVERRIDE": {},
"CAP_NET_RAW": {},
"CAP_SETGID": {},
"CAP_SETUID": {},
"CAP_SETPCAP": {},
"CAP_SETFCAP": {},
"CAP_NET_BIND_SERVICE": {},
"CAP_SYS_CHROOT": {},
"CAP_AUDIT_WRITE": {},
"CAP_MAC_ADMIN": {},
"CAP_MAC_OVERRIDE": {},
"CAP_DAC_READ_SEARCH": {},
"CAP_SYS_PTRACE": {},
"CAP_SYS_MODULE": {},
"CAP_SYSLOG": {},
"CAP_SYS_RAWIO": {},
"CAP_SYS_ADMIN": {},
"CAP_LINUX_IMMUTABLE": {},
"CAP_SYS_BOOT": {},
"CAP_SYS_NICE": {},
"CAP_SYS_PACCT": {},
"CAP_SYS_TTY_CONFIG": {},
"CAP_SYS_TIME": {},
"CAP_WAKE_ALARM": {},
"CAP_AUDIT_READ": {},
"CAP_AUDIT_CONTROL": {},
"CAP_SYS_RESOURCE": {},
"CAP_BLOCK_SUSPEND": {},
"CAP_IPC_LOCK": {},
"CAP_IPC_OWNER": {},
"CAP_LEASE": {},
"CAP_NET_ADMIN": {},
"CAP_NET_BROADCAST": {},
}
|
