github.com/inspektor-gadget/inspektor-gadget@v0.28.1/pkg/netnsenter/netnsenter.go (about)

     1  // Copyright 2021 The Inspektor Gadget authors
     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 netnsenter
    16  
    17  import (
    18  	"runtime"
    19  
    20  	"github.com/vishvananda/netns"
    21  
    22  	"github.com/inspektor-gadget/inspektor-gadget/pkg/utils/host"
    23  	netnsig "github.com/inspektor-gadget/inspektor-gadget/pkg/utils/netns"
    24  )
    25  
    26  func NetnsEnter(pid int, f func() error) error {
    27  	if pid == 0 {
    28  		return f()
    29  	}
    30  
    31  	// Lock the OS Thread so we don't accidentally switch namespaces
    32  	runtime.LockOSThread()
    33  	defer runtime.UnlockOSThread()
    34  
    35  	// Save the current network namespace
    36  	origns, _ := netns.Get()
    37  	defer origns.Close()
    38  
    39  	netnsHandle, err := netnsig.GetFromPidWithAltProcfs(pid, host.HostProcFs)
    40  	if err != nil {
    41  		return err
    42  	}
    43  	defer netnsHandle.Close()
    44  	err = netns.Set(netnsHandle)
    45  	if err != nil {
    46  		return err
    47  	}
    48  
    49  	// Switch back to the original namespace
    50  	defer netns.Set(origns)
    51  
    52  	return f()
    53  }