github.com/imran-kn/cilium-fork@v1.6.9/pkg/cgroups/cgroups.go (about)

     1  // Copyright 2018 Authors of Cilium
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package cgroups
    16  
    17  import (
    18  	"fmt"
    19  	"os"
    20  	"sync"
    21  	"syscall"
    22  
    23  	"github.com/cilium/cilium/pkg/defaults"
    24  	"github.com/cilium/cilium/pkg/logging"
    25  	"github.com/cilium/cilium/pkg/logging/logfields"
    26  	"github.com/cilium/cilium/pkg/mountinfo"
    27  )
    28  
    29  var (
    30  	// Path to where cgroup is mounted
    31  	cgroupRoot = defaults.DefaultCgroupRoot
    32  
    33  	// Only mount a single instance
    34  	cgrpMountOnce sync.Once
    35  )
    36  
    37  var log = logging.DefaultLogger.WithField(logfields.LogSubsys, "cgroups")
    38  
    39  // setCgroupRoot will set the path to mount cgroupv2
    40  func setCgroupRoot(path string) {
    41  	cgroupRoot = path
    42  }
    43  
    44  // GetCgroupRoot returns the path for the cgroupv2 mount
    45  func GetCgroupRoot() string {
    46  	return cgroupRoot
    47  }
    48  
    49  // mountCgroup mounts the Cgroup v2 filesystem into the desired cgroupRoot directory.
    50  func mountCgroup() error {
    51  	cgroupRootStat, err := os.Stat(cgroupRoot)
    52  	if err != nil {
    53  		if os.IsNotExist(err) {
    54  			if err := os.MkdirAll(cgroupRoot, 0755); err != nil {
    55  				return fmt.Errorf("Unable to create cgroup mount directory: %s", err)
    56  			}
    57  		} else {
    58  			return fmt.Errorf("Failed to stat the mount path %s: %s", cgroupRoot, err)
    59  		}
    60  	} else if !cgroupRootStat.IsDir() {
    61  		return fmt.Errorf("%s is a file which is not a directory", cgroupRoot)
    62  	}
    63  
    64  	if err := syscall.Mount("none", cgroupRoot, mountinfo.FilesystemTypeCgroup2, 0, ""); err != nil {
    65  		return fmt.Errorf("failed to mount %s: %s", cgroupRoot, err)
    66  	}
    67  
    68  	return nil
    69  }
    70  
    71  // checkOrMountCustomLocation tries to check or mount the BPF filesystem in the
    72  // given path.
    73  func cgrpCheckOrMountLocation(cgroupRoot string) error {
    74  	setCgroupRoot(cgroupRoot)
    75  
    76  	// Check whether the custom location has a mount.
    77  	mounted, cgroupInstance, err := mountinfo.IsMountFS(mountinfo.FilesystemTypeCgroup2, cgroupRoot)
    78  	if err != nil {
    79  		return err
    80  	}
    81  
    82  	// If the custom location has no mount, let's mount there.
    83  	if !mounted {
    84  		if err := mountCgroup(); err != nil {
    85  			return err
    86  		}
    87  	}
    88  
    89  	if !cgroupInstance {
    90  		return fmt.Errorf("Mount in the custom directory %s has a different filesystem than cgroup2", cgroupRoot)
    91  	}
    92  	return nil
    93  }
    94  
    95  // CheckOrMountCgrpFS this checks if the cilium cgroup2 root mount point is
    96  // mounted and if not mounts it. If mapRoot is "" it will mount the default
    97  // location. It is harmless to have multiple cgroupv2 root mounts so unlike
    98  // BPFFS case we simply mount at the cilium default regardless if the system
    99  // has another mount created by systemd or otherwise.
   100  func CheckOrMountCgrpFS(mapRoot string) {
   101  	cgrpMountOnce.Do(func() {
   102  		if mapRoot == "" {
   103  			mapRoot = cgroupRoot
   104  		}
   105  		err := cgrpCheckOrMountLocation(mapRoot)
   106  		// Failed cgroup2 mount is not a fatal error, sockmap will be disabled however
   107  		if err == nil {
   108  			log.Infof("Mounted cgroupv2 filesystem at %s", mapRoot)
   109  		}
   110  	})
   111  }