github.com/psiphon-labs/psiphon-tunnel-core@v2.0.28+incompatible/psiphon/common/networkConfig_linux.go (about)

     1  /*
     2   * Copyright (c) 2020, Psiphon Inc.
     3   * All rights reserved.
     4   *
     5   * This program is free software: you can redistribute it and/or modify
     6   * it under the terms of the GNU General Public License as published by
     7   * the Free Software Foundation, either version 3 of the License, or
     8   * (at your option) any later version.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package common
    21  
    22  import (
    23  	"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/errors"
    24  	"github.com/syndtr/gocapability/capability"
    25  )
    26  
    27  func configureNetworkConfigSubprocessCapabilities() error {
    28  
    29  	// If this process has CAP_NET_ADMIN, make it available to be inherited
    30  	// be child processes via ambient mechanism described here:
    31  	// https://github.com/torvalds/linux/commit/58319057b7847667f0c9585b9de0e8932b0fdb08
    32  	//
    33  	// The ambient mechanism is available in Linux kernel 4.3 and later.
    34  
    35  	// When using capabilities, this process should have CAP_NET_ADMIN in order
    36  	// to create tun devices. And the subprocess operations such as using "ifconfig"
    37  	// and "iptables" for network config require the same CAP_NET_ADMIN capability.
    38  
    39  	cap, err := capability.NewPid(0)
    40  	if err != nil {
    41  		return errors.Trace(err)
    42  	}
    43  
    44  	if cap.Get(capability.EFFECTIVE, capability.CAP_NET_ADMIN) {
    45  
    46  		cap.Set(capability.INHERITABLE|capability.AMBIENT, capability.CAP_NET_ADMIN)
    47  
    48  		err = cap.Apply(capability.AMBIENT)
    49  		if err != nil {
    50  			return errors.Trace(err)
    51  		}
    52  	}
    53  
    54  	return nil
    55  }