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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2018 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package syscheck
import (
"bytes"
"fmt"
"os"
"path/filepath"
"strings"
"github.com/snapcore/snapd/dirs"
"github.com/snapcore/snapd/logger"
"github.com/snapcore/snapd/osutil"
"github.com/snapcore/snapd/release"
"github.com/snapcore/snapd/strutil"
)
func init() {
checks = append(checks, checkKernelVersion)
}
// supportsMayDetachMounts checks whether a RHEL 7.4+ specific kernel knob is present
// and set to proper value
func supportsMayDetachMounts(kver string) error {
p := filepath.Join(dirs.GlobalRootDir, "/proc/sys/fs/may_detach_mounts")
value, err := os.ReadFile(p)
if err != nil {
return fmt.Errorf("cannot read the value of fs.may_detach_mounts kernel parameter: %v", err)
}
if !bytes.Equal(value, []byte("1\n")) {
return fmt.Errorf("fs.may_detach_mounts kernel parameter is supported but disabled")
}
return nil
}
// checkKernelVersion looks for some unsupported configurations that users may
// encounter and provides advice on how to resolve them.
func checkKernelVersion() error {
if !release.OnClassic {
return nil
}
switch release.ReleaseInfo.ID {
case "ubuntu":
if release.ReleaseInfo.VersionID == "14.04" {
kver := osutil.KernelVersion()
// a kernel version looks like this: "4.4.0-112-generic" and
// we are only interested in the bits before the "-"
kver = strings.SplitN(kver, "-", 2)[0]
cmp, err := strutil.VersionCompare(kver, "3.13.0")
if err != nil {
logger.Noticef("cannot check kernel: %v", err)
return nil
}
if cmp <= 0 {
return fmt.Errorf("you need to reboot into a 4.4 kernel to start using snapd")
}
}
case "rhel", "centos":
// check for kernel tweaks on RHEL/CentOS 7.5+
// CentoS 7.5 has VERSION_ID="7", RHEL 7.6 has VERSION_ID="7.6"
if release.ReleaseInfo.VersionID == "" || release.ReleaseInfo.VersionID[0] != '7' {
return nil
}
fullKver := osutil.KernelVersion()
// kernel version looks like this: "3.10.0-957.el7.x86_64"
kver := strings.SplitN(fullKver, "-", 2)[0]
cmp, err := strutil.VersionCompare(kver, "3.18.0")
if err != nil {
logger.Noticef("cannot check kernel: %v", err)
return nil
}
if cmp < 0 {
// pre 3.18 kernels here
if idx := strings.Index(fullKver, ".el7."); idx == -1 {
// non stock kernel, assume it's not supported
return fmt.Errorf("unsupported kernel version %q, you need to switch to the stock kernel", fullKver)
}
// stock kernel had bugfixes backported to it
return supportsMayDetachMounts(kver)
}
}
return nil
}
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