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moby--moby/vendor/github.com/syndtr/gocapability/capability/capability_linux.go

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// Copyright (c) 2013, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package capability
import (
"bufio"
"errors"
"fmt"
"io"
"os"
"strings"
"syscall"
)
var errUnknownVers = errors.New("unknown capability version")
const (
linuxCapVer1 = 0x19980330
linuxCapVer2 = 0x20071026
linuxCapVer3 = 0x20080522
)
var (
capVers uint32
capLastCap Cap
)
func init() {
var hdr capHeader
capget(&hdr, nil)
capVers = hdr.version
if initLastCap() == nil {
CAP_LAST_CAP = capLastCap
if capLastCap > 31 {
capUpperMask = (uint32(1) << (uint(capLastCap) - 31)) - 1
} else {
capUpperMask = 0
}
}
}
func initLastCap() error {
if capLastCap != 0 {
return nil
}
f, err := os.Open("/proc/sys/kernel/cap_last_cap")
if err != nil {
return err
}
defer f.Close()
var b []byte = make([]byte, 11)
_, err = f.Read(b)
if err != nil {
return err
}
fmt.Sscanf(string(b), "%d", &capLastCap)
return nil
}
func mkStringCap(c Capabilities, which CapType) (ret string) {
for i, first := Cap(0), true; i <= CAP_LAST_CAP; i++ {
if !c.Get(which, i) {
continue
}
if first {
first = false
} else {
ret += ", "
}
ret += i.String()
}
return
}
func mkString(c Capabilities, max CapType) (ret string) {
ret = "{"
for i := CapType(1); i <= max; i <<= 1 {
ret += " " + i.String() + "=\""
if c.Empty(i) {
ret += "empty"
} else if c.Full(i) {
ret += "full"
} else {
ret += c.StringCap(i)
}
ret += "\""
}
ret += " }"
return
}
func newPid(pid int) (c Capabilities, err error) {
switch capVers {
case linuxCapVer1:
p := new(capsV1)
p.hdr.version = capVers
p.hdr.pid = pid
c = p
case linuxCapVer2, linuxCapVer3:
p := new(capsV3)
p.hdr.version = capVers
p.hdr.pid = pid
c = p
default:
err = errUnknownVers
return
}
err = c.Load()
if err != nil {
c = nil
}
return
}
type capsV1 struct {
hdr capHeader
data capData
}
func (c *capsV1) Get(which CapType, what Cap) bool {
if what > 32 {
return false
}
switch which {
case EFFECTIVE:
return (1<<uint(what))&c.data.effective != 0
case PERMITTED:
return (1<<uint(what))&c.data.permitted != 0
case INHERITABLE:
return (1<<uint(what))&c.data.inheritable != 0
}
return false
}
func (c *capsV1) getData(which CapType) (ret uint32) {
switch which {
case EFFECTIVE:
ret = c.data.effective
case PERMITTED:
ret = c.data.permitted
case INHERITABLE:
ret = c.data.inheritable
}
return
}
func (c *capsV1) Empty(which CapType) bool {
return c.getData(which) == 0
}
func (c *capsV1) Full(which CapType) bool {
return (c.getData(which) & 0x7fffffff) == 0x7fffffff
}
func (c *capsV1) Set(which CapType, caps ...Cap) {
for _, what := range caps {
if what > 32 {
continue
}
if which&EFFECTIVE != 0 {
c.data.effective |= 1 << uint(what)
}
if which&PERMITTED != 0 {
c.data.permitted |= 1 << uint(what)
}
if which&INHERITABLE != 0 {
c.data.inheritable |= 1 << uint(what)
}
}
}
func (c *capsV1) Unset(which CapType, caps ...Cap) {
for _, what := range caps {
if what > 32 {
continue
}
if which&EFFECTIVE != 0 {
c.data.effective &= ^(1 << uint(what))
}
if which&PERMITTED != 0 {
c.data.permitted &= ^(1 << uint(what))
}
if which&INHERITABLE != 0 {
c.data.inheritable &= ^(1 << uint(what))
}
}
}
func (c *capsV1) Fill(kind CapType) {
if kind&CAPS == CAPS {
c.data.effective = 0x7fffffff
c.data.permitted = 0x7fffffff
c.data.inheritable = 0
}
}
func (c *capsV1) Clear(kind CapType) {
if kind&CAPS == CAPS {
c.data.effective = 0
c.data.permitted = 0
c.data.inheritable = 0
}
}
func (c *capsV1) StringCap(which CapType) (ret string) {
return mkStringCap(c, which)
}
func (c *capsV1) String() (ret string) {
return mkString(c, BOUNDING)
}
func (c *capsV1) Load() (err error) {
return capget(&c.hdr, &c.data)
}
func (c *capsV1) Apply(kind CapType) error {
if kind&CAPS == CAPS {
return capset(&c.hdr, &c.data)
}
return nil
}
type capsV3 struct {
hdr capHeader
data [2]capData
bounds [2]uint32
}
func (c *capsV3) Get(which CapType, what Cap) bool {
var i uint
if what > 31 {
i = uint(what) >> 5
what %= 32
}
switch which {
case EFFECTIVE:
return (1<<uint(what))&c.data[i].effective != 0
case PERMITTED:
return (1<<uint(what))&c.data[i].permitted != 0
case INHERITABLE:
return (1<<uint(what))&c.data[i].inheritable != 0
case BOUNDING:
return (1<<uint(what))&c.bounds[i] != 0
}
return false
}
func (c *capsV3) getData(which CapType, dest []uint32) {
switch which {
case EFFECTIVE:
dest[0] = c.data[0].effective
dest[1] = c.data[1].effective
case PERMITTED:
dest[0] = c.data[0].permitted
dest[1] = c.data[1].permitted
case INHERITABLE:
dest[0] = c.data[0].inheritable
dest[1] = c.data[1].inheritable
case BOUNDING:
dest[0] = c.bounds[0]
dest[1] = c.bounds[1]
}
}
func (c *capsV3) Empty(which CapType) bool {
var data [2]uint32
c.getData(which, data[:])
return data[0] == 0 && data[1] == 0
}
func (c *capsV3) Full(which CapType) bool {
var data [2]uint32
c.getData(which, data[:])
if (data[0] & 0xffffffff) != 0xffffffff {
return false
}
return (data[1] & capUpperMask) == capUpperMask
}
func (c *capsV3) Set(which CapType, caps ...Cap) {
for _, what := range caps {
var i uint
if what > 31 {
i = uint(what) >> 5
what %= 32
}
if which&EFFECTIVE != 0 {
c.data[i].effective |= 1 << uint(what)
}
if which&PERMITTED != 0 {
c.data[i].permitted |= 1 << uint(what)
}
if which&INHERITABLE != 0 {
c.data[i].inheritable |= 1 << uint(what)
}
if which&BOUNDING != 0 {
c.bounds[i] |= 1 << uint(what)
}
}
}
func (c *capsV3) Unset(which CapType, caps ...Cap) {
for _, what := range caps {
var i uint
if what > 31 {
i = uint(what) >> 5
what %= 32
}
if which&EFFECTIVE != 0 {
c.data[i].effective &= ^(1 << uint(what))
}
if which&PERMITTED != 0 {
c.data[i].permitted &= ^(1 << uint(what))
}
if which&INHERITABLE != 0 {
c.data[i].inheritable &= ^(1 << uint(what))
}
if which&BOUNDING != 0 {
c.bounds[i] &= ^(1 << uint(what))
}
}
}
func (c *capsV3) Fill(kind CapType) {
if kind&CAPS == CAPS {
c.data[0].effective = 0xffffffff
c.data[0].permitted = 0xffffffff
c.data[0].inheritable = 0
c.data[1].effective = 0xffffffff
c.data[1].permitted = 0xffffffff
c.data[1].inheritable = 0
}
if kind&BOUNDS == BOUNDS {
c.bounds[0] = 0xffffffff
c.bounds[1] = 0xffffffff
}
}
func (c *capsV3) Clear(kind CapType) {
if kind&CAPS == CAPS {
c.data[0].effective = 0
c.data[0].permitted = 0
c.data[0].inheritable = 0
c.data[1].effective = 0
c.data[1].permitted = 0
c.data[1].inheritable = 0
}
if kind&BOUNDS == BOUNDS {
c.bounds[0] = 0
c.bounds[1] = 0
}
}
func (c *capsV3) StringCap(which CapType) (ret string) {
return mkStringCap(c, which)
}
func (c *capsV3) String() (ret string) {
return mkString(c, BOUNDING)
}
func (c *capsV3) Load() (err error) {
err = capget(&c.hdr, &c.data[0])
if err != nil {
return
}
var status_path string
if c.hdr.pid == 0 {
status_path = fmt.Sprintf("/proc/self/status")
} else {
status_path = fmt.Sprintf("/proc/%d/status", c.hdr.pid)
}
f, err := os.Open(status_path)
if err != nil {
return
}
b := bufio.NewReader(f)
for {
line, e := b.ReadString('\n')
if e != nil {
if e != io.EOF {
err = e
}
break
}
if strings.HasPrefix(line, "CapB") {
fmt.Sscanf(line[4:], "nd: %08x%08x", &c.bounds[1], &c.bounds[0])
break
}
}
f.Close()
return
}
func (c *capsV3) Apply(kind CapType) (err error) {
if kind&BOUNDS == BOUNDS {
var data [2]capData
err = capget(&c.hdr, &data[0])
if err != nil {
return
}
if (1<<uint(CAP_SETPCAP))&data[0].effective != 0 {
for i := Cap(0); i <= CAP_LAST_CAP; i++ {
if c.Get(BOUNDING, i) {
continue
}
err = prctl(syscall.PR_CAPBSET_DROP, uintptr(i), 0, 0, 0)
if err != nil {
// Ignore EINVAL since the capability may not be supported in this system.
if errno, ok := err.(syscall.Errno); ok && errno == syscall.EINVAL {
err = nil
continue
}
return
}
}
}
}
if kind&CAPS == CAPS {
return capset(&c.hdr, &c.data[0])
}
return
}
func newFile(path string) (c Capabilities, err error) {
c = &capsFile{path: path}
err = c.Load()
if err != nil {
c = nil
}
return
}
type capsFile struct {
path string
data vfscapData
}
func (c *capsFile) Get(which CapType, what Cap) bool {
var i uint
if what > 31 {
if c.data.version == 1 {
return false
}
i = uint(what) >> 5
what %= 32
}
switch which {
case EFFECTIVE:
return (1<<uint(what))&c.data.effective[i] != 0
case PERMITTED:
return (1<<uint(what))&c.data.data[i].permitted != 0
case INHERITABLE:
return (1<<uint(what))&c.data.data[i].inheritable != 0
}
return false
}
func (c *capsFile) getData(which CapType, dest []uint32) {
switch which {
case EFFECTIVE:
dest[0] = c.data.effective[0]
dest[1] = c.data.effective[1]
case PERMITTED:
dest[0] = c.data.data[0].permitted
dest[1] = c.data.data[1].permitted
case INHERITABLE:
dest[0] = c.data.data[0].inheritable
dest[1] = c.data.data[1].inheritable
}
}
func (c *capsFile) Empty(which CapType) bool {
var data [2]uint32
c.getData(which, data[:])
return data[0] == 0 && data[1] == 0
}
func (c *capsFile) Full(which CapType) bool {
var data [2]uint32
c.getData(which, data[:])
if c.data.version == 0 {
return (data[0] & 0x7fffffff) == 0x7fffffff
}
if (data[0] & 0xffffffff) != 0xffffffff {
return false
}
return (data[1] & capUpperMask) == capUpperMask
}
func (c *capsFile) Set(which CapType, caps ...Cap) {
for _, what := range caps {
var i uint
if what > 31 {
if c.data.version == 1 {
continue
}
i = uint(what) >> 5
what %= 32
}
if which&EFFECTIVE != 0 {
c.data.effective[i] |= 1 << uint(what)
}
if which&PERMITTED != 0 {
c.data.data[i].permitted |= 1 << uint(what)
}
if which&INHERITABLE != 0 {
c.data.data[i].inheritable |= 1 << uint(what)
}
}
}
func (c *capsFile) Unset(which CapType, caps ...Cap) {
for _, what := range caps {
var i uint
if what > 31 {
if c.data.version == 1 {
continue
}
i = uint(what) >> 5
what %= 32
}
if which&EFFECTIVE != 0 {
c.data.effective[i] &= ^(1 << uint(what))
}
if which&PERMITTED != 0 {
c.data.data[i].permitted &= ^(1 << uint(what))
}
if which&INHERITABLE != 0 {
c.data.data[i].inheritable &= ^(1 << uint(what))
}
}
}
func (c *capsFile) Fill(kind CapType) {
if kind&CAPS == CAPS {
c.data.effective[0] = 0xffffffff
c.data.data[0].permitted = 0xffffffff
c.data.data[0].inheritable = 0
if c.data.version == 2 {
c.data.effective[1] = 0xffffffff
c.data.data[1].permitted = 0xffffffff
c.data.data[1].inheritable = 0
}
}
}
func (c *capsFile) Clear(kind CapType) {
if kind&CAPS == CAPS {
c.data.effective[0] = 0
c.data.data[0].permitted = 0
c.data.data[0].inheritable = 0
if c.data.version == 2 {
c.data.effective[1] = 0
c.data.data[1].permitted = 0
c.data.data[1].inheritable = 0
}
}
}
func (c *capsFile) StringCap(which CapType) (ret string) {
return mkStringCap(c, which)
}
func (c *capsFile) String() (ret string) {
return mkString(c, INHERITABLE)
}
func (c *capsFile) Load() (err error) {
return getVfsCap(c.path, &c.data)
}
func (c *capsFile) Apply(kind CapType) (err error) {
if kind&CAPS == CAPS {
return setVfsCap(c.path, &c.data)
}
return
}