github.com/bugraaydogar/snapd@v0.0.0-20210315170335-8c70bb858939/daemon/ucrednet.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2015 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 daemon
    21  
    22  import (
    23  	"errors"
    24  	"fmt"
    25  	"net"
    26  	"regexp"
    27  	"strconv"
    28  	"sync"
    29  	sys "syscall"
    30  )
    31  
    32  var errNoID = errors.New("no pid/uid found")
    33  
    34  const (
    35  	ucrednetNoProcess = int32(0)
    36  	ucrednetNobody    = uint32((1 << 32) - 1)
    37  )
    38  
    39  var raddrRegexp = regexp.MustCompile(`^pid=(\d+);uid=(\d+);socket=([^;]*);$`)
    40  
    41  var ucrednetGet = ucrednetGetImpl
    42  
    43  func ucrednetGetImpl(remoteAddr string) (pid int32, uid uint32, socket string, err error) {
    44  	// NOTE treat remoteAddr at one point included a user-controlled
    45  	// string. In case that happens again by accident, treat it as tainted,
    46  	// and be very suspicious of it.
    47  	pid = ucrednetNoProcess
    48  	uid = ucrednetNobody
    49  	subs := raddrRegexp.FindStringSubmatch(remoteAddr)
    50  	if subs != nil {
    51  		if v, err := strconv.ParseInt(subs[1], 10, 32); err == nil {
    52  			pid = int32(v)
    53  		}
    54  		if v, err := strconv.ParseUint(subs[2], 10, 32); err == nil {
    55  			uid = uint32(v)
    56  		}
    57  		socket = subs[3]
    58  	}
    59  	if pid == ucrednetNoProcess || uid == ucrednetNobody {
    60  		err = errNoID
    61  	}
    62  
    63  	return pid, uid, socket, err
    64  }
    65  
    66  type ucrednet struct {
    67  	pid    int32
    68  	uid    uint32
    69  	socket string
    70  }
    71  
    72  func (un *ucrednet) String() string {
    73  	if un == nil {
    74  		return "pid=;uid=;socket=;"
    75  	}
    76  	return fmt.Sprintf("pid=%d;uid=%d;socket=%s;", un.pid, un.uid, un.socket)
    77  }
    78  
    79  type ucrednetAddr struct {
    80  	net.Addr
    81  	*ucrednet
    82  }
    83  
    84  func (wa *ucrednetAddr) String() string {
    85  	// NOTE we drop the original (user-supplied) net.Addr from the
    86  	// serialization entirely. We carry it this far so it helps debugging
    87  	// (via %#v logging), but from here on in it's not helpful.
    88  	return wa.ucrednet.String()
    89  }
    90  
    91  type ucrednetConn struct {
    92  	net.Conn
    93  	*ucrednet
    94  }
    95  
    96  func (wc *ucrednetConn) RemoteAddr() net.Addr {
    97  	return &ucrednetAddr{wc.Conn.RemoteAddr(), wc.ucrednet}
    98  }
    99  
   100  type ucrednetListener struct {
   101  	net.Listener
   102  
   103  	idempotClose sync.Once
   104  	closeErr     error
   105  }
   106  
   107  var getUcred = sys.GetsockoptUcred
   108  
   109  func (wl *ucrednetListener) Accept() (net.Conn, error) {
   110  	con, err := wl.Listener.Accept()
   111  	if err != nil {
   112  		return nil, err
   113  	}
   114  
   115  	var unet *ucrednet
   116  	if ucon, ok := con.(*net.UnixConn); ok {
   117  		f, err := ucon.File()
   118  		if err != nil {
   119  			return nil, err
   120  		}
   121  		// File() is a dup(); needs closing
   122  		defer f.Close()
   123  
   124  		ucred, err := getUcred(int(f.Fd()), sys.SOL_SOCKET, sys.SO_PEERCRED)
   125  		if err != nil {
   126  			return nil, err
   127  		}
   128  
   129  		unet = &ucrednet{
   130  			pid:    ucred.Pid,
   131  			uid:    ucred.Uid,
   132  			socket: ucon.LocalAddr().String(),
   133  		}
   134  	}
   135  
   136  	return &ucrednetConn{con, unet}, nil
   137  }
   138  
   139  func (wl *ucrednetListener) Close() error {
   140  	wl.idempotClose.Do(func() {
   141  		wl.closeErr = wl.Listener.Close()
   142  	})
   143  	return wl.closeErr
   144  }