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Merge pull request #5017 from AkihiroSuda/parse-cap

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oci.WithPrivileged: set the current caps, not the known caps
This commit is contained in:
Phil Estes
2021-02-23 09:10:57 -05:00
committed by GitHub
parent 9173d3e929 51f985cb1f
commit 757be0a090
13 changed files with 530 additions and 117 deletions
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172
pkg/cap/cap_linux.go Normal file
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@@ -0,0 +1,172 @@
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// Package cap provides Linux capability utility
package cap
import (
"bufio"
"io"
"os"
"strconv"
"strings"
"github.com/pkg/errors"
"github.com/syndtr/gocapability/capability"
)
// FromUint64 parses an integer into string slice like
// []{"CAP_SYS_ADMIN", ...}.
//
// Unknown cap numbers are returned as []int.
func FromUint64(v uint64) ([]string, []int) {
var (
res []string
unknown []int
)
knownList := capability.List()
known := make(map[string]struct{}, len(knownList))
for _, f := range knownList {
known[f.String()] = struct{}{}
}
for i := 0; i <= 63; i++ {
if b := (v >> i) & 0x1; b == 0x1 {
c := capability.Cap(i)
sRaw := c.String()
if _, ok := known[sRaw]; ok {
s := "CAP_" + strings.ToUpper(sRaw)
res = append(res, s)
} else {
unknown = append(unknown, i)
}
}
}
return res, unknown
}
// ParseProcPIDStatus returns uint64 value from /proc/<PID>/status file
func ParseProcPIDStatus(r io.Reader) (map[capability.CapType]uint64, error) {
res := make(map[capability.CapType]uint64)
scanner := bufio.NewScanner(r)
for scanner.Scan() {
line := scanner.Text()
pair := strings.SplitN(line, ":", 2)
if len(pair) != 2 {
continue
}
k := strings.TrimSpace(pair[0])
v := strings.TrimSpace(pair[1])
switch k {
case "CapInh", "CapPrm", "CapEff", "CapBnd", "CapAmb":
ui64, err := strconv.ParseUint(v, 16, 64)
if err != nil {
return nil, errors.Errorf("failed to parse line %q", line)
}
switch k {
case "CapInh":
res[capability.INHERITABLE] = ui64
case "CapPrm":
res[capability.PERMITTED] = ui64
case "CapEff":
res[capability.EFFECTIVE] = ui64
case "CapBnd":
res[capability.BOUNDING] = ui64
case "CapAmb":
res[capability.AMBIENT] = ui64
}
}
}
if err := scanner.Err(); err != nil {
return nil, err
}
return res, nil
}
// Current returns the list of the effective and the known caps of
// the current process.
//
// The result is like []string{"CAP_SYS_ADMIN", ...}.
//
// The result does not contain caps that are not recognized by
// the "github.com/syndtr/gocapability" library.
func Current() ([]string, error) {
f, err := os.Open("/proc/self/status")
if err != nil {
return nil, err
}
defer f.Close()
caps, err := ParseProcPIDStatus(f)
if err != nil {
return nil, err
}
capEff := caps[capability.EFFECTIVE]
names, _ := FromUint64(capEff)
return names, nil
}
var (
// caps35 is the caps of kernel 3.5 (37 entries)
caps35 = []string{
"CAP_CHOWN", // 2.2
"CAP_DAC_OVERRIDE", // 2.2
"CAP_DAC_READ_SEARCH", // 2.2
"CAP_FOWNER", // 2.2
"CAP_FSETID", // 2.2
"CAP_KILL", // 2.2
"CAP_SETGID", // 2.2
"CAP_SETUID", // 2.2
"CAP_SETPCAP", // 2.2
"CAP_LINUX_IMMUTABLE", // 2.2
"CAP_NET_BIND_SERVICE", // 2.2
"CAP_NET_BROADCAST", // 2.2
"CAP_NET_ADMIN", // 2.2
"CAP_NET_RAW", // 2.2
"CAP_IPC_LOCK", // 2.2
"CAP_IPC_OWNER", // 2.2
"CAP_SYS_MODULE", // 2.2
"CAP_SYS_RAWIO", // 2.2
"CAP_SYS_CHROOT", // 2.2
"CAP_SYS_PTRACE", // 2.2
"CAP_SYS_PACCT", // 2.2
"CAP_SYS_ADMIN", // 2.2
"CAP_SYS_BOOT", // 2.2
"CAP_SYS_NICE", // 2.2
"CAP_SYS_RESOURCE", // 2.2
"CAP_SYS_TIME", // 2.2
"CAP_SYS_TTY_CONFIG", // 2.2
"CAP_MKNOD", // 2.4
"CAP_LEASE", // 2.4
"CAP_AUDIT_WRITE", // 2.6.11
"CAP_AUDIT_CONTROL", // 2.6.11
"CAP_SETFCAP", // 2.6.24
"CAP_MAC_OVERRIDE", // 2.6.25
"CAP_MAC_ADMIN", // 2.6.25
"CAP_SYSLOG", // 2.6.37
"CAP_WAKE_ALARM", // 3.0
"CAP_BLOCK_SUSPEND", // 3.5
}
// caps316 is the caps of kernel 3.16 (38 entries)
caps316 = append(caps35, "CAP_AUDIT_READ")
// caps58 is the caps of kernel 5.8 (40 entries)
caps58 = append(caps316, []string{"CAP_PERFMON", "CAP_BPF"}...)
// caps59 is the caps of kernel 5.9 (41 entries)
caps59 = append(caps58, "CAP_CHECKPOINT_RESTORE")
)
// Known returns the known cap strings as of kernel 5.9
func Known() []string {
return caps59
}

161
pkg/cap/cap_linux_test.go Normal file
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@@ -0,0 +1,161 @@
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cap
import (
"strings"
"testing"
"github.com/stretchr/testify/assert"
"github.com/syndtr/gocapability/capability"
)
func TestCapsList(t *testing.T) {
assert.Len(t, caps316, 38)
assert.Len(t, caps58, 40)
assert.Len(t, caps59, 41)
}
func TestFromUint64(t *testing.T) {
type testCase struct {
comment string
v uint64
knownNames []string
unknown []int
}
testCases := []testCase{
{
comment: "No cap",
v: 0x0000000000000000,
},
{
// 3.10 (same caps as 3.5) is the oldest kernel version we want to support
comment: "All caps on kernel 3.5 (last = CAP_BLOCK_SUSPEND)",
v: 0x0000001fffffffff,
knownNames: caps35,
},
{
comment: "All caps on kernel 3.16 (last = CAP_AUDIT_READ)",
v: 0x0000003fffffffff,
knownNames: caps316,
},
{
comment: "All caps on kernel 5.8 (last = CAP_BPF)",
v: 0x000000ffffffffff,
knownNames: caps58,
},
{
comment: "All caps on kernel 5.9 (last = CAP_CHECKPOINT_RESTORE)",
v: 0x000001ffffffffff,
knownNames: caps59,
},
{
comment: "Unknown caps",
v: 0xf00001ffffffffff,
knownNames: caps59,
unknown: []int{60, 61, 62, 63},
},
}
for _, tc := range testCases {
knownNames, unknown := FromUint64(tc.v)
t.Logf("[%s] v=0x%x, got=%+v (%d entries), unknown=%v",
tc.comment, tc.v, knownNames, len(knownNames), unknown)
assert.Equal(t, tc.knownNames, knownNames)
assert.Equal(t, tc.unknown, unknown)
}
}
func TestParseProcPIDStatus(t *testing.T) {
procPIDStatus := `Name: cat
Umask: 0022
State: R (running)
Tgid: 170065
Ngid: 0
Pid: 170065
PPid: 170064
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 64
Groups: 0
NStgid: 170065
NSpid: 170065
NSpgid: 170064
NSsid: 3784
VmPeak: 8216 kB
VmSize: 8216 kB
VmLck: 0 kB
VmPin: 0 kB
VmHWM: 676 kB
VmRSS: 676 kB
RssAnon: 72 kB
RssFile: 604 kB
RssShmem: 0 kB
VmData: 324 kB
VmStk: 132 kB
VmExe: 20 kB
VmLib: 1612 kB
VmPTE: 56 kB
VmSwap: 0 kB
HugetlbPages: 0 kB
CoreDumping: 0
THP_enabled: 1
Threads: 1
SigQ: 0/63692
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000000000000
CapInh: 0000000000000000
CapPrm: 000000ffffffffff
CapEff: 000000ffffffffff
CapBnd: 000000ffffffffff
CapAmb: 0000000000000000
NoNewPrivs: 0
Seccomp: 0
Speculation_Store_Bypass: thread vulnerable
Cpus_allowed: 00000000,00000000,00000000,0000000f
Cpus_allowed_list: 0-3
Mems_allowed: 00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
Mems_allowed_list: 0
voluntary_ctxt_switches: 0
nonvoluntary_ctxt_switches: 0
`
res, err := ParseProcPIDStatus(strings.NewReader(procPIDStatus))
assert.NoError(t, err)
expected := map[capability.CapType]uint64{
capability.INHERITABLE: 0,
capability.PERMITTED: 0xffffffffff,
capability.EFFECTIVE: 0xffffffffff,
capability.BOUNDING: 0xffffffffff,
capability.AMBIENT: 0,
}
assert.EqualValues(t, expected, res)
}
func TestCurrent(t *testing.T) {
caps, err := Current()
assert.NoError(t, err)
t.Logf("verify the result manually: %+v", caps)
}
func TestKnown(t *testing.T) {
caps := Known()
assert.EqualValues(t, caps59, caps)
}

4
pkg/cri/opts/spec_linux.go
View File

@@ -354,7 +354,7 @@ func WithDevices(osi osinterface.OS, config *runtime.ContainerConfig) oci.SpecOp
}
// WithCapabilities sets the provided capabilities from the security context
func WithCapabilities(sc *runtime.LinuxContainerSecurityContext) oci.SpecOpts {
func WithCapabilities(sc *runtime.LinuxContainerSecurityContext, allCaps []string) oci.SpecOpts {
capabilities := sc.GetCapabilities()
if capabilities == nil {
return nullOpt
@@ -366,7 +366,7 @@ func WithCapabilities(sc *runtime.LinuxContainerSecurityContext) oci.SpecOpts {
// AddCapabilities: []string{"ALL"}, DropCapabilities: []string{"CHOWN"}
// will be all capabilities without `CAP_CHOWN`.
if util.InStringSlice(capabilities.GetAddCapabilities(), "ALL") {
opts = append(opts, oci.WithAllCapabilities)
opts = append(opts, oci.WithCapabilities(allCaps))
}
if util.InStringSlice(capabilities.GetDropCapabilities(), "ALL") {
opts = append(opts, oci.WithCapabilities(nil))

6
pkg/cri/server/container_create_linux.go
View File

@@ -217,10 +217,12 @@ func (c *criService) containerSpec(
specOpts = append(specOpts, oci.WithHostDevices, oci.WithAllDevicesAllowed)
} else {
// add requested devices by the config as host devices are not automatically added
specOpts = append(specOpts, customopts.WithDevices(c.os, config), customopts.WithCapabilities(securityContext))
specOpts = append(specOpts, customopts.WithDevices(c.os, config),
customopts.WithCapabilities(securityContext, c.allCaps))
}
} else { // not privileged
specOpts = append(specOpts, customopts.WithDevices(c.os, config), customopts.WithCapabilities(securityContext))
specOpts = append(specOpts, customopts.WithDevices(c.os, config),
customopts.WithCapabilities(securityContext, c.allCaps))
}
// Clear all ambient capabilities. The implication of non-root + caps

11
pkg/cri/server/container_create_linux_test.go
View File

@@ -39,6 +39,7 @@ import (
"github.com/stretchr/testify/require"
runtime "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
"github.com/containerd/containerd/pkg/cap"
"github.com/containerd/containerd/pkg/cri/annotations"
"github.com/containerd/containerd/pkg/cri/config"
"github.com/containerd/containerd/pkg/cri/opts"
@@ -191,6 +192,7 @@ func TestContainerCapabilities(t *testing.T) {
testSandboxID := "sandbox-id"
testContainerName := "container-name"
testPid := uint32(1234)
allCaps := cap.Known()
for desc, test := range map[string]struct {
capability *runtime.Capability
includes []string
@@ -208,20 +210,20 @@ func TestContainerCapabilities(t *testing.T) {
capability: &runtime.Capability{
AddCapabilities: []string{"ALL"},
},
includes: oci.GetAllCapabilities(),
includes: allCaps,
},
"should be able to drop all capabilities": {
capability: &runtime.Capability{
DropCapabilities: []string{"ALL"},
},
excludes: oci.GetAllCapabilities(),
excludes: allCaps,
},
"should be able to drop capabilities with add all": {
capability: &runtime.Capability{
AddCapabilities: []string{"ALL"},
DropCapabilities: []string{"CHOWN"},
},
includes: util.SubtractStringSlice(oci.GetAllCapabilities(), "CAP_CHOWN"),
includes: util.SubtractStringSlice(allCaps, "CAP_CHOWN"),
excludes: []string{"CAP_CHOWN"},
},
"should be able to add capabilities with drop all": {
@@ -230,13 +232,14 @@ func TestContainerCapabilities(t *testing.T) {
DropCapabilities: []string{"ALL"},
},
includes: []string{"CAP_SYS_ADMIN"},
excludes: util.SubtractStringSlice(oci.GetAllCapabilities(), "CAP_SYS_ADMIN"),
excludes: util.SubtractStringSlice(allCaps, "CAP_SYS_ADMIN"),
},
} {
t.Logf("TestCase %q", desc)
containerConfig, sandboxConfig, imageConfig, specCheck := getCreateContainerTestData()
ociRuntime := config.Runtime{}
c := newTestCRIService()
c.allCaps = allCaps
containerConfig.Linux.SecurityContext.Capabilities = test.capability
spec, err := c.containerSpec(testID, testSandboxID, testPid, "", testContainerName, testImageName, containerConfig, sandboxConfig, imageConfig, nil, ociRuntime)

3
pkg/cri/server/service.go
View File

@@ -101,6 +101,9 @@ type criService struct {
cniNetConfMonitor *cniNetConfSyncer
// baseOCISpecs contains cached OCI specs loaded via `Runtime.BaseRuntimeSpec`
baseOCISpecs map[string]*oci.Spec
// allCaps is the list of the capabilities.
// When nil, parsed from CapEff of /proc/self/status.
allCaps []string // nolint
}
// NewCRIService returns a new instance of CRIService

8
pkg/cri/server/service_linux.go
View File

@@ -17,6 +17,7 @@
package server
import (
"github.com/containerd/containerd/pkg/cap"
"github.com/containerd/containerd/sys"
cni "github.com/containerd/go-cni"
"github.com/opencontainers/selinux/go-selinux"
@@ -61,6 +62,13 @@ func (c *criService) initPlatform() error {
return errors.Wrap(err, "failed to initialize cni")
}
if c.allCaps == nil {
c.allCaps, err = cap.Current()
if err != nil {
return errors.Wrap(err, "failed to get caps")
}
}
return nil
}