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Tap plugin

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This PR adds a plugin to create tap devices.
The plugin adds a tap device to the container.

The plugin has a workaround for a golang netlink library
which does not allow for tap devices with no owner/group
to be created. When no tap owner/group is requested, the
plugin will fall back to using the ip tool for creating
the tap device. A fix to the golang netlink lib is pending.

Signed-off-by: mmirecki <mmirecki@redhat.com>
This commit is contained in:
mmirecki
2022-11-17 16:09:26 +01:00
parent 98e01b7c80
commit 01d0031487
27 changed files with 4351 additions and 0 deletions
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/*
Package selinux provides a high-level interface for interacting with selinux.
Usage:
import "github.com/opencontainers/selinux/go-selinux"
// Ensure that selinux is enforcing mode.
if selinux.EnforceMode() != selinux.Enforcing {
selinux.SetEnforceMode(selinux.Enforcing)
}
*/
package selinux

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package selinux
import (
"github.com/pkg/errors"
)
const (
// Enforcing constant indicate SELinux is in enforcing mode
Enforcing = 1
// Permissive constant to indicate SELinux is in permissive mode
Permissive = 0
// Disabled constant to indicate SELinux is disabled
Disabled = -1
// maxCategory is the maximum number of categories used within containers
maxCategory = 1024
// DefaultCategoryRange is the upper bound on the category range
DefaultCategoryRange = uint32(maxCategory)
)
var (
// ErrMCSAlreadyExists is returned when trying to allocate a duplicate MCS.
ErrMCSAlreadyExists = errors.New("MCS label already exists")
// ErrEmptyPath is returned when an empty path has been specified.
ErrEmptyPath = errors.New("empty path")
// InvalidLabel is returned when an invalid label is specified.
InvalidLabel = errors.New("Invalid Label")
// ErrIncomparable is returned two levels are not comparable
ErrIncomparable = errors.New("incomparable levels")
// ErrLevelSyntax is returned when a sensitivity or category do not have correct syntax in a level
ErrLevelSyntax = errors.New("invalid level syntax")
// ErrContextMissing is returned if a requested context is not found in a file.
ErrContextMissing = errors.New("context does not have a match")
// ErrVerifierNil is returned when a context verifier function is nil.
ErrVerifierNil = errors.New("verifier function is nil")
// CategoryRange allows the upper bound on the category range to be adjusted
CategoryRange = DefaultCategoryRange
)
// Context is a representation of the SELinux label broken into 4 parts
type Context map[string]string
// SetDisabled disables SELinux support for the package
func SetDisabled() {
setDisabled()
}
// GetEnabled returns whether SELinux is currently enabled.
func GetEnabled() bool {
return getEnabled()
}
// ClassIndex returns the int index for an object class in the loaded policy,
// or -1 and an error
func ClassIndex(class string) (int, error) {
return classIndex(class)
}
// SetFileLabel sets the SELinux label for this path or returns an error.
func SetFileLabel(fpath string, label string) error {
return setFileLabel(fpath, label)
}
// FileLabel returns the SELinux label for this path or returns an error.
func FileLabel(fpath string) (string, error) {
return fileLabel(fpath)
}
// SetFSCreateLabel tells the kernel what label to use for all file system objects
// created by this task.
// Set the label to an empty string to return to the default label. Calls to SetFSCreateLabel
// should be wrapped in runtime.LockOSThread()/runtime.UnlockOSThread() until file system
// objects created by this task are finished to guarantee another goroutine does not migrate
// to the current thread before execution is complete.
func SetFSCreateLabel(label string) error {
return setFSCreateLabel(label)
}
// FSCreateLabel returns the default label the kernel which the kernel is using
// for file system objects created by this task. "" indicates default.
func FSCreateLabel() (string, error) {
return fsCreateLabel()
}
// CurrentLabel returns the SELinux label of the current process thread, or an error.
func CurrentLabel() (string, error) {
return currentLabel()
}
// PidLabel returns the SELinux label of the given pid, or an error.
func PidLabel(pid int) (string, error) {
return pidLabel(pid)
}
// ExecLabel returns the SELinux label that the kernel will use for any programs
// that are executed by the current process thread, or an error.
func ExecLabel() (string, error) {
return execLabel()
}
// CanonicalizeContext takes a context string and writes it to the kernel
// the function then returns the context that the kernel will use. Use this
// function to check if two contexts are equivalent
func CanonicalizeContext(val string) (string, error) {
return canonicalizeContext(val)
}
// ComputeCreateContext requests the type transition from source to target for
// class from the kernel.
func ComputeCreateContext(source string, target string, class string) (string, error) {
return computeCreateContext(source, target, class)
}
// CalculateGlbLub computes the glb (greatest lower bound) and lub (least upper bound)
// of a source and target range.
// The glblub is calculated as the greater of the low sensitivities and
// the lower of the high sensitivities and the and of each category bitset.
func CalculateGlbLub(sourceRange, targetRange string) (string, error) {
return calculateGlbLub(sourceRange, targetRange)
}
// SetExecLabel sets the SELinux label that the kernel will use for any programs
// that are executed by the current process thread, or an error. Calls to SetExecLabel
// should be wrapped in runtime.LockOSThread()/runtime.UnlockOSThread() until execution
// of the program is finished to guarantee another goroutine does not migrate to the current
// thread before execution is complete.
func SetExecLabel(label string) error {
return setExecLabel(label)
}
// SetTaskLabel sets the SELinux label for the current thread, or an error.
// This requires the dyntransition permission. Calls to SetTaskLabel should
// be wrapped in runtime.LockOSThread()/runtime.UnlockOSThread() to guarantee
// the current thread does not run in a new mislabeled thread.
func SetTaskLabel(label string) error {
return setTaskLabel(label)
}
// SetSocketLabel takes a process label and tells the kernel to assign the
// label to the next socket that gets created. Calls to SetSocketLabel
// should be wrapped in runtime.LockOSThread()/runtime.UnlockOSThread() until
// the the socket is created to guarantee another goroutine does not migrate
// to the current thread before execution is complete.
func SetSocketLabel(label string) error {
return setSocketLabel(label)
}
// SocketLabel retrieves the current socket label setting
func SocketLabel() (string, error) {
return socketLabel()
}
// PeerLabel retrieves the label of the client on the other side of a socket
func PeerLabel(fd uintptr) (string, error) {
return peerLabel(fd)
}
// SetKeyLabel takes a process label and tells the kernel to assign the
// label to the next kernel keyring that gets created. Calls to SetKeyLabel
// should be wrapped in runtime.LockOSThread()/runtime.UnlockOSThread() until
// the kernel keyring is created to guarantee another goroutine does not migrate
// to the current thread before execution is complete.
func SetKeyLabel(label string) error {
return setKeyLabel(label)
}
// KeyLabel retrieves the current kernel keyring label setting
func KeyLabel() (string, error) {
return keyLabel()
}
// Get returns the Context as a string
func (c Context) Get() string {
return c.get()
}
// NewContext creates a new Context struct from the specified label
func NewContext(label string) (Context, error) {
return newContext(label)
}
// ClearLabels clears all reserved labels
func ClearLabels() {
clearLabels()
}
// ReserveLabel reserves the MLS/MCS level component of the specified label
func ReserveLabel(label string) {
reserveLabel(label)
}
// EnforceMode returns the current SELinux mode Enforcing, Permissive, Disabled
func EnforceMode() int {
return enforceMode()
}
// SetEnforceMode sets the current SELinux mode Enforcing, Permissive.
// Disabled is not valid, since this needs to be set at boot time.
func SetEnforceMode(mode int) error {
return setEnforceMode(mode)
}
// DefaultEnforceMode returns the systems default SELinux mode Enforcing,
// Permissive or Disabled. Note this is is just the default at boot time.
// EnforceMode tells you the systems current mode.
func DefaultEnforceMode() int {
return defaultEnforceMode()
}
// ReleaseLabel un-reserves the MLS/MCS Level field of the specified label,
// allowing it to be used by another process.
func ReleaseLabel(label string) {
releaseLabel(label)
}
// ROFileLabel returns the specified SELinux readonly file label
func ROFileLabel() string {
return roFileLabel()
}
// KVMContainerLabels returns the default processLabel and mountLabel to be used
// for kvm containers by the calling process.
func KVMContainerLabels() (string, string) {
return kvmContainerLabels()
}
// InitContainerLabels returns the default processLabel and file labels to be
// used for containers running an init system like systemd by the calling process.
func InitContainerLabels() (string, string) {
return initContainerLabels()
}
// ContainerLabels returns an allocated processLabel and fileLabel to be used for
// container labeling by the calling process.
func ContainerLabels() (processLabel string, fileLabel string) {
return containerLabels()
}
// SecurityCheckContext validates that the SELinux label is understood by the kernel
func SecurityCheckContext(val string) error {
return securityCheckContext(val)
}
// CopyLevel returns a label with the MLS/MCS level from src label replaced on
// the dest label.
func CopyLevel(src, dest string) (string, error) {
return copyLevel(src, dest)
}
// Chcon changes the fpath file object to the SELinux label label.
// If fpath is a directory and recurse is true, then Chcon walks the
// directory tree setting the label.
func Chcon(fpath string, label string, recurse bool) error {
return chcon(fpath, label, recurse)
}
// DupSecOpt takes an SELinux process label and returns security options that
// can be used to set the SELinux Type and Level for future container processes.
func DupSecOpt(src string) ([]string, error) {
return dupSecOpt(src)
}
// DisableSecOpt returns a security opt that can be used to disable SELinux
// labeling support for future container processes.
func DisableSecOpt() []string {
return disableSecOpt()
}
// GetDefaultContextWithLevel gets a single context for the specified SELinux user
// identity that is reachable from the specified scon context. The context is based
// on the per-user /etc/selinux/{SELINUXTYPE}/contexts/users/<username> if it exists,
// and falls back to the global /etc/selinux/{SELINUXTYPE}/contexts/default_contexts
// file.
func GetDefaultContextWithLevel(user, level, scon string) (string, error) {
return getDefaultContextWithLevel(user, level, scon)
}
// PrivContainerMountLabel returns mount label for privileged containers
func PrivContainerMountLabel() string {
return privContainerMountLabel
}

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// +build !linux
package selinux
const privContainerMountLabel = ""
func setDisabled() {
}
func getEnabled() bool {
return false
}
func classIndex(class string) (int, error) {
return -1, nil
}
func setFileLabel(fpath string, label string) error {
return nil
}
func fileLabel(fpath string) (string, error) {
return "", nil
}
func setFSCreateLabel(label string) error {
return nil
}
func fsCreateLabel() (string, error) {
return "", nil
}
func currentLabel() (string, error) {
return "", nil
}
func pidLabel(pid int) (string, error) {
return "", nil
}
func execLabel() (string, error) {
return "", nil
}
func canonicalizeContext(val string) (string, error) {
return "", nil
}
func computeCreateContext(source string, target string, class string) (string, error) {
return "", nil
}
func calculateGlbLub(sourceRange, targetRange string) (string, error) {
return "", nil
}
func setExecLabel(label string) error {
return nil
}
func setTaskLabel(label string) error {
return nil
}
func setSocketLabel(label string) error {
return nil
}
func socketLabel() (string, error) {
return "", nil
}
func peerLabel(fd uintptr) (string, error) {
return "", nil
}
func setKeyLabel(label string) error {
return nil
}
func keyLabel() (string, error) {
return "", nil
}
func (c Context) get() string {
return ""
}
func newContext(label string) (Context, error) {
c := make(Context)
return c, nil
}
func clearLabels() {
}
func reserveLabel(label string) {
}
func enforceMode() int {
return Disabled
}
func setEnforceMode(mode int) error {
return nil
}
func defaultEnforceMode() int {
return Disabled
}
func releaseLabel(label string) {
}
func roFileLabel() string {
return ""
}
func kvmContainerLabels() (string, string) {
return "", ""
}
func initContainerLabels() (string, string) {
return "", ""
}
func containerLabels() (processLabel string, fileLabel string) {
return "", ""
}
func securityCheckContext(val string) error {
return nil
}
func copyLevel(src, dest string) (string, error) {
return "", nil
}
func chcon(fpath string, label string, recurse bool) error {
return nil
}
func dupSecOpt(src string) ([]string, error) {
return nil, nil
}
func disableSecOpt() []string {
return []string{"disable"}
}
func getDefaultContextWithLevel(user, level, scon string) (string, error) {
return "", nil
}

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package selinux
import (
"golang.org/x/sys/unix"
)
// lgetxattr returns a []byte slice containing the value of
// an extended attribute attr set for path.
func lgetxattr(path, attr string) ([]byte, error) {
// Start with a 128 length byte array
dest := make([]byte, 128)
sz, errno := doLgetxattr(path, attr, dest)
for errno == unix.ERANGE {
// Buffer too small, use zero-sized buffer to get the actual size
sz, errno = doLgetxattr(path, attr, []byte{})
if errno != nil {
return nil, errno
}
dest = make([]byte, sz)
sz, errno = doLgetxattr(path, attr, dest)
}
if errno != nil {
return nil, errno
}
return dest[:sz], nil
}
// doLgetxattr is a wrapper that retries on EINTR
func doLgetxattr(path, attr string, dest []byte) (int, error) {
for {
sz, err := unix.Lgetxattr(path, attr, dest)
if err != unix.EINTR {
return sz, err
}
}
}

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## pwalk: parallel implementation of filepath.Walk
This is a wrapper for [filepath.Walk](https://pkg.go.dev/path/filepath?tab=doc#Walk)
which may speed it up by calling multiple callback functions (WalkFunc) in parallel,
utilizing goroutines.
By default, it utilizes 2\*runtime.NumCPU() goroutines for callbacks.
This can be changed by using WalkN function which has the additional
parameter, specifying the number of goroutines (concurrency).
### Caveats
Please note the following limitations of this code:
* Unlike filepath.Walk, the order of calls is non-deterministic;
* Only primitive error handling is supported:
* filepath.SkipDir is not supported;
* no errors are ever passed to WalkFunc;
* once any error is returned from any WalkFunc instance, no more new calls
to WalkFunc are made, and the error is returned to the caller of Walk;
* if more than one walkFunc instance will return an error, only one
of such errors will be propagated and returned by Walk, others
will be silently discarded.
### Documentation
For the official documentation, see
https://pkg.go.dev/github.com/opencontainers/selinux/pkg/pwalk?tab=doc
### Benchmarks
For a WalkFunc that consists solely of the return statement, this
implementation is about 10% slower than the standard library's
filepath.Walk.
Otherwise (if a WalkFunc is doing something) this is usually faster,
except when the WalkN(..., 1) is used.

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package pwalk
import (
"os"
"path/filepath"
"runtime"
"sync"
"github.com/pkg/errors"
)
type WalkFunc = filepath.WalkFunc
// Walk is a wrapper for filepath.Walk which can call multiple walkFn
// in parallel, allowing to handle each item concurrently. A maximum of
// twice the runtime.NumCPU() walkFn will be called at any one time.
// If you want to change the maximum, use WalkN instead.
//
// The order of calls is non-deterministic.
//
// Note that this implementation only supports primitive error handling:
//
// - no errors are ever passed to WalkFn;
//
// - once a walkFn returns any error, all further processing stops
// and the error is returned to the caller of Walk;
//
// - filepath.SkipDir is not supported;
//
// - if more than one walkFn instance will return an error, only one
// of such errors will be propagated and returned by Walk, others
// will be silently discarded.
func Walk(root string, walkFn WalkFunc) error {
return WalkN(root, walkFn, runtime.NumCPU()*2)
}
// WalkN is a wrapper for filepath.Walk which can call multiple walkFn
// in parallel, allowing to handle each item concurrently. A maximum of
// num walkFn will be called at any one time.
//
// Please see Walk documentation for caveats of using this function.
func WalkN(root string, walkFn WalkFunc, num int) error {
// make sure limit is sensible
if num < 1 {
return errors.Errorf("walk(%q): num must be > 0", root)
}
files := make(chan *walkArgs, 2*num)
errCh := make(chan error, 1) // get the first error, ignore others
// Start walking a tree asap
var (
err error
wg sync.WaitGroup
)
wg.Add(1)
go func() {
err = filepath.Walk(root, func(p string, info os.FileInfo, err error) error {
if err != nil {
close(files)
return err
}
// add a file to the queue unless a callback sent an error
select {
case e := <-errCh:
close(files)
return e
default:
files <- &walkArgs{path: p, info: &info}
return nil
}
})
if err == nil {
close(files)
}
wg.Done()
}()
wg.Add(num)
for i := 0; i < num; i++ {
go func() {
for file := range files {
if e := walkFn(file.path, *file.info, nil); e != nil {
select {
case errCh <- e: // sent ok
default: // buffer full
}
}
}
wg.Done()
}()
}
wg.Wait()
return err
}
// walkArgs holds the arguments that were passed to the Walk or WalkLimit
// functions.
type walkArgs struct {
path string
info *os.FileInfo
}