oci.WithPrivileged: set the current caps, not the known caps
This change is needed for running the latest containerd inside Docker that is not aware of the recently added caps (BPF, PERFMON, CHECKPOINT_RESTORE). Without this change, containerd inside Docker fails to run containers with "apply caps: operation not permitted" error. See kubernetes-sigs/kind 2058 NOTE: The caller process of this function is now assumed to be as privileged as possible. Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
This commit is contained in:
Akihiro Suda
172
pkg/cap/cap_linux.go
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172
pkg/cap/cap_linux.go
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@@ -0,0 +1,172 @@
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package cap provides Linux capability utility
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package cap
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import (
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"bufio"
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"io"
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"os"
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"strconv"
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"strings"
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"github.com/pkg/errors"
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"github.com/syndtr/gocapability/capability"
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)
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// FromUint64 parses an integer into string slice like
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// []{"CAP_SYS_ADMIN", ...}.
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//
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// Unknown cap numbers are returned as []int.
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func FromUint64(v uint64) ([]string, []int) {
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var (
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res []string
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unknown []int
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)
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knownList := capability.List()
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known := make(map[string]struct{}, len(knownList))
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for _, f := range knownList {
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known[f.String()] = struct{}{}
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}
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for i := 0; i <= 63; i++ {
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if b := (v >> i) & 0x1; b == 0x1 {
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c := capability.Cap(i)
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sRaw := c.String()
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if _, ok := known[sRaw]; ok {
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s := "CAP_" + strings.ToUpper(sRaw)
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res = append(res, s)
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} else {
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unknown = append(unknown, i)
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}
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}
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}
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return res, unknown
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}
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// ParseProcPIDStatus returns uint64 value from /proc/<PID>/status file
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func ParseProcPIDStatus(r io.Reader) (map[capability.CapType]uint64, error) {
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res := make(map[capability.CapType]uint64)
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scanner := bufio.NewScanner(r)
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for scanner.Scan() {
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line := scanner.Text()
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pair := strings.SplitN(line, ":", 2)
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if len(pair) != 2 {
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continue
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}
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k := strings.TrimSpace(pair[0])
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v := strings.TrimSpace(pair[1])
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switch k {
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case "CapInh", "CapPrm", "CapEff", "CapBnd", "CapAmb":
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ui64, err := strconv.ParseUint(v, 16, 64)
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if err != nil {
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return nil, errors.Errorf("failed to parse line %q", line)
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}
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switch k {
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case "CapInh":
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res[capability.INHERITABLE] = ui64
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case "CapPrm":
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res[capability.PERMITTED] = ui64
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case "CapEff":
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res[capability.EFFECTIVE] = ui64
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case "CapBnd":
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res[capability.BOUNDING] = ui64
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case "CapAmb":
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res[capability.AMBIENT] = ui64
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}
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}
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}
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if err := scanner.Err(); err != nil {
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return nil, err
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}
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return res, nil
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}
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// Current returns the list of the effective and the known caps of
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// the current process.
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//
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// The result is like []string{"CAP_SYS_ADMIN", ...}.
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//
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// The result does not contain caps that are not recognized by
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// the "github.com/syndtr/gocapability" library.
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func Current() ([]string, error) {
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f, err := os.Open("/proc/self/status")
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if err != nil {
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return nil, err
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}
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defer f.Close()
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caps, err := ParseProcPIDStatus(f)
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if err != nil {
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return nil, err
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}
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capEff := caps[capability.EFFECTIVE]
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names, _ := FromUint64(capEff)
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return names, nil
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}
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var (
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// caps35 is the caps of kernel 3.5 (37 entries)
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caps35 = []string{
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"CAP_CHOWN", // 2.2
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"CAP_DAC_OVERRIDE", // 2.2
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"CAP_DAC_READ_SEARCH", // 2.2
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"CAP_FOWNER", // 2.2
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"CAP_FSETID", // 2.2
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"CAP_KILL", // 2.2
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"CAP_SETGID", // 2.2
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"CAP_SETUID", // 2.2
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"CAP_SETPCAP", // 2.2
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"CAP_LINUX_IMMUTABLE", // 2.2
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"CAP_NET_BIND_SERVICE", // 2.2
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"CAP_NET_BROADCAST", // 2.2
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"CAP_NET_ADMIN", // 2.2
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"CAP_NET_RAW", // 2.2
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"CAP_IPC_LOCK", // 2.2
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"CAP_IPC_OWNER", // 2.2
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"CAP_SYS_MODULE", // 2.2
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"CAP_SYS_RAWIO", // 2.2
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"CAP_SYS_CHROOT", // 2.2
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"CAP_SYS_PTRACE", // 2.2
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"CAP_SYS_PACCT", // 2.2
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"CAP_SYS_ADMIN", // 2.2
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"CAP_SYS_BOOT", // 2.2
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"CAP_SYS_NICE", // 2.2
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"CAP_SYS_RESOURCE", // 2.2
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"CAP_SYS_TIME", // 2.2
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"CAP_SYS_TTY_CONFIG", // 2.2
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"CAP_MKNOD", // 2.4
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"CAP_LEASE", // 2.4
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"CAP_AUDIT_WRITE", // 2.6.11
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"CAP_AUDIT_CONTROL", // 2.6.11
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"CAP_SETFCAP", // 2.6.24
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"CAP_MAC_OVERRIDE", // 2.6.25
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"CAP_MAC_ADMIN", // 2.6.25
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"CAP_SYSLOG", // 2.6.37
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"CAP_WAKE_ALARM", // 3.0
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"CAP_BLOCK_SUSPEND", // 3.5
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}
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// caps316 is the caps of kernel 3.16 (38 entries)
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caps316 = append(caps35, "CAP_AUDIT_READ")
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// caps58 is the caps of kernel 5.8 (40 entries)
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caps58 = append(caps316, []string{"CAP_PERFMON", "CAP_BPF"}...)
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// caps59 is the caps of kernel 5.9 (41 entries)
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caps59 = append(caps58, "CAP_CHECKPOINT_RESTORE")
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)
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// Known returns the known cap strings as of kernel 5.9
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func Known() []string {
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return caps59
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}
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161
pkg/cap/cap_linux_test.go
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161
pkg/cap/cap_linux_test.go
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@@ -0,0 +1,161 @@
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cap
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import (
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"strings"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/syndtr/gocapability/capability"
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)
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func TestCapsList(t *testing.T) {
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assert.Len(t, caps316, 38)
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assert.Len(t, caps58, 40)
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assert.Len(t, caps59, 41)
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}
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func TestFromUint64(t *testing.T) {
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type testCase struct {
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comment string
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v uint64
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knownNames []string
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unknown []int
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}
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testCases := []testCase{
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{
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comment: "No cap",
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v: 0x0000000000000000,
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},
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{
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// 3.10 (same caps as 3.5) is the oldest kernel version we want to support
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comment: "All caps on kernel 3.5 (last = CAP_BLOCK_SUSPEND)",
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v: 0x0000001fffffffff,
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knownNames: caps35,
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},
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{
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comment: "All caps on kernel 3.16 (last = CAP_AUDIT_READ)",
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v: 0x0000003fffffffff,
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knownNames: caps316,
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},
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{
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comment: "All caps on kernel 5.8 (last = CAP_BPF)",
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v: 0x000000ffffffffff,
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knownNames: caps58,
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},
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{
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comment: "All caps on kernel 5.9 (last = CAP_CHECKPOINT_RESTORE)",
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v: 0x000001ffffffffff,
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knownNames: caps59,
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},
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{
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comment: "Unknown caps",
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v: 0xf00001ffffffffff,
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knownNames: caps59,
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unknown: []int{60, 61, 62, 63},
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},
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}
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for _, tc := range testCases {
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knownNames, unknown := FromUint64(tc.v)
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t.Logf("[%s] v=0x%x, got=%+v (%d entries), unknown=%v",
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tc.comment, tc.v, knownNames, len(knownNames), unknown)
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assert.Equal(t, tc.knownNames, knownNames)
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assert.Equal(t, tc.unknown, unknown)
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}
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}
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func TestParseProcPIDStatus(t *testing.T) {
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procPIDStatus := `Name: cat
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Umask: 0022
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State: R (running)
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Tgid: 170065
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Ngid: 0
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Pid: 170065
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PPid: 170064
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TracerPid: 0
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Uid: 0 0 0 0
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Gid: 0 0 0 0
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FDSize: 64
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Groups: 0
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NStgid: 170065
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NSpid: 170065
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NSpgid: 170064
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NSsid: 3784
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VmPeak: 8216 kB
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VmSize: 8216 kB
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VmLck: 0 kB
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VmPin: 0 kB
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VmHWM: 676 kB
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VmRSS: 676 kB
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RssAnon: 72 kB
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RssFile: 604 kB
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RssShmem: 0 kB
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VmData: 324 kB
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VmStk: 132 kB
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VmExe: 20 kB
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VmLib: 1612 kB
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VmPTE: 56 kB
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VmSwap: 0 kB
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HugetlbPages: 0 kB
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CoreDumping: 0
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THP_enabled: 1
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Threads: 1
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SigQ: 0/63692
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SigPnd: 0000000000000000
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ShdPnd: 0000000000000000
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SigBlk: 0000000000000000
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SigIgn: 0000000000000000
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SigCgt: 0000000000000000
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CapInh: 0000000000000000
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CapPrm: 000000ffffffffff
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CapEff: 000000ffffffffff
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CapBnd: 000000ffffffffff
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CapAmb: 0000000000000000
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NoNewPrivs: 0
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Seccomp: 0
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Speculation_Store_Bypass: thread vulnerable
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Cpus_allowed: 00000000,00000000,00000000,0000000f
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Cpus_allowed_list: 0-3
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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
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Mems_allowed_list: 0
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voluntary_ctxt_switches: 0
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nonvoluntary_ctxt_switches: 0
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`
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res, err := ParseProcPIDStatus(strings.NewReader(procPIDStatus))
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assert.NoError(t, err)
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expected := map[capability.CapType]uint64{
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capability.INHERITABLE: 0,
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capability.PERMITTED: 0xffffffffff,
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capability.EFFECTIVE: 0xffffffffff,
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capability.BOUNDING: 0xffffffffff,
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capability.AMBIENT: 0,
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}
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assert.EqualValues(t, expected, res)
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}
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func TestCurrent(t *testing.T) {
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caps, err := Current()
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assert.NoError(t, err)
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t.Logf("verify the result manually: %+v", caps)
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}
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func TestKnown(t *testing.T) {
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caps := Known()
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assert.EqualValues(t, caps59, caps)
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}
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