github.com/meulengracht/snapd@v0.0.0-20210719210640-8bde69bcc84e/sanity/apparmor_lxd.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2018 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     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 sanity
    21  
    22  import (
    23  	"fmt"
    24  	"os"
    25  )
    26  
    27  func init() {
    28  	checks = append(checks, checkApparmorUsable)
    29  }
    30  
    31  var apparmorProfilesPath = "/sys/kernel/security/apparmor/profiles"
    32  
    33  func checkApparmorUsable() error {
    34  	// Check that apparmor is actually usable. In some
    35  	// configurations of lxd, apparmor looks available when in
    36  	// reality it isn't. Eg, this can happen when a container runs
    37  	// unprivileged (eg, root in the container is non-root
    38  	// outside) and also unconfined (where lxd doesn't set up an
    39  	// apparmor policy namespace). We can therefore simply check
    40  	// if /sys/kernel/security/apparmor/profiles is readable (like
    41  	// aa-status does), and if it isn't, we know we can't manipulate
    42  	// policy.
    43  	f, err := os.Open(apparmorProfilesPath)
    44  	if os.IsPermission(err) {
    45  		return fmt.Errorf("apparmor detected but insufficient permissions to use it")
    46  	}
    47  	if f != nil {
    48  		f.Close()
    49  	}
    50  	return nil
    51  }