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Move RunningInUserNS() to its own package

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This allows using the utility without bringing whole of "sys" with it.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This commit is contained in:
Sebastiaan van Stijn
2021-03-23 10:51:24 +01:00
parent edf6484165
commit 708299ca40
9 changed files with 38 additions and 13 deletions
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4
sys/oom_unix.go
View File

@@ -24,6 +24,8 @@ import (
"os"
"strconv"
"strings"
"github.com/containerd/containerd/pkg/userns"
)
const (
@@ -42,7 +44,7 @@ func SetOOMScore(pid, score int) error {
}
defer f.Close()
if _, err = f.WriteString(strconv.Itoa(score)); err != nil {
if os.IsPermission(err) && (RunningInUserNS() || RunningUnprivileged()) {
if os.IsPermission(err) && (userns.RunningInUserNS() || RunningUnprivileged()) {
return nil
}
return err

12
sys/userns_unsupported.go → sys/userns_deprecated.go
View File

@@ -1,5 +1,3 @@
// +build !linux
/*
Copyright The containerd Authors.
@@ -18,8 +16,8 @@
package sys
// RunningInUserNS is a stub for non-Linux systems
// Always returns false
func RunningInUserNS() bool {
return false
}
import "github.com/containerd/containerd/pkg/userns"
// RunningInUserNS detects whether we are currently running in a user namespace.
// Deprecated: use github.com/containerd/containerd/pkg/userns.RunningInUserNS instead.
var RunningInUserNS = userns.RunningInUserNS

62
sys/userns_linux.go
View File

@@ -1,62 +0,0 @@
/*
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 sys
import (
"bufio"
"fmt"
"os"
"sync"
)
var (
inUserNS bool
nsOnce sync.Once
)
// RunningInUserNS detects whether we are currently running in a user namespace.
// Originally copied from github.com/lxc/lxd/shared/util.go
func RunningInUserNS() bool {
nsOnce.Do(func() {
file, err := os.Open("/proc/self/uid_map")
if err != nil {
// This kernel-provided file only exists if user namespaces are supported
return
}
defer file.Close()
buf := bufio.NewReader(file)
l, _, err := buf.ReadLine()
if err != nil {
return
}
line := string(l)
var a, b, c int64
fmt.Sscanf(line, "%d %d %d", &a, &b, &c)
/*
* We assume we are in the initial user namespace if we have a full
* range - 4294967295 uids starting at uid 0.
*/
if a == 0 && b == 0 && c == 4294967295 {
return
}
inUserNS = true
})
return inUserNS
}