opt/bin/become

   1 #!/bin/bash
   2
   3 chdir=0
   4 kerberos=0
   5 x11=0
   6 while getopts ":kx" opt; do
   7   case $opt in
   8     c) chdir=1;;
   9     k) kerberos=1;;
  10     x) x11=1;;
  11   esac
  12 done
  13 shift $((OPTIND-1))
  14
  15 user="$1"; shift
  16 if [ -z "$user" ]; then
  17   echo >&2 "Usage: become [-c] [-k] [-x] <user>"
  18   echo >&2 "Options: -c   Stay in current directory even if target user is not root."
  19   echo >&2 "         -k   Delegate Kerberos credentials even if target user is not root."
  20   echo >&2 "         -x   Delegate X11 cookie even if target user is not root."
  21   exit 1
  22 fi
  23
  24 uid=$(PATH=/usr/xpg4/bin:/usr/bin id -u "$user" 2>/dev/null)
  25 if [ -z "$uid" ]; then
  26   echo >&2 "Who is $user?"
  27   exit 2
  28 fi
  29
  30 if [ $uid = 0 ]; then
  31   chdir=1
  32   kerberos=1
  33   x11=1
  34 fi
  35
  36 PRINCIPAL=$(klist 2>/dev/null | sed -n 's/^Default principal: //p')
  37 if [ $x11 = 1 -a -n "$DISPLAY" -a "${DISPLAY##localhost:}" = "$DISPLAY" ]; then
  38   COOKIE="$(xauth list $DISPLAY)"
  39 fi
  40 ignore_profile_user=0
  41 for candidate in "$HOME" "$PROFILE_HOME"; do
  42   [ -n "$candidate" ] || continue
  43   BECOME="$candidate/.become"
  44   [ -d "$BECOME" ] || continue
  45
  46   # Script to run when becoming any user.
  47   [ -z "$allusersprofile" ] && allusersprofile="$BECOME/all"
  48   [ -f "$allusersprofile" ] || allusersprofile=
  49
  50   # Set $HOME/all sticky to ignore $PROFILE_HOME/$user.
  51   if [ "$candidate" = "$HOME" ]; then
  52     [ -k "$BECOME/all" ] && ignore_profile_user=1
  53   else
  54     [ $ignore_profile_user = 1 ] && continue
  55   fi
  56
  57   # Script to run (after the one mentioned above) when becoming this user.
  58   [ -z "$userprofile" ] && userprofile="$BECOME/$user"
  59   [ -f "$userprofile" ] || userprofile=
  60 done
  61
  62 # Preserve environment variables.
  63 ignore_environment_user=0
  64 for candidate in "$HOME" "$PROFILE_HOME"; do
  65   [ -n "$candidate" ] || continue
  66   BECOME="$candidate/.become/environment"
  67   [ -d "$BECOME" ] || continue
  68
  69   # Script to run when becoming any user.
  70   [ -z "$allusersenvironment" ] && allusersenvironment="$BECOME/all"
  71   [ -f "$allusersenvironment" ] || allusersenvironment=
  72
  73   # Set $HOME/all sticky to ignore $PROFILE_HOME/$user.
  74   if [ "$candidate" = "$HOME" ]; then
  75     [ -k "$BECOME/all" ] && ignore_environment_user=1
  76   else
  77     [ $ignore_environment_user = 1 ] && continue
  78   fi
  79
  80   # Environment variables to preserve when becomeing this user.
  81   [ -z "$userenvironment" ] && userenvironment="$BECOME/$user"
  82   [ -f "$userenvironment" ] || userenvironment=
  83 done
  84
  85 file="${TMPDIR:-/tmp}/$USER.become.$user.$RANDOM.$$"
  86 umask=$(builtin umask -p)
  87 builtin umask 077
  88 if exec 3>"$file" && exec <"$file" && rm "$file"; then
  89   builtin $umask
  90   echo >&3 "cd"
  91   echo >&3 "PROFILE_HOME='${PROFILE_HOME:-$HOME}'"
  92   if [ -n "$PRINCIPAL" ]; then
  93     echo >&3 "PRINCIPAL='$PRINCIPAL'"
  94     if [ $kerberos = 1 ]; then
  95       ccname=$(klist 2>/dev/null | sed -n 's/^Ticket cache: [DF]I[LR][E:]://p')
  96       if [ -f "$ccname" ]; then
  97         echo >&3 "export KRB5CCNAME='$KRB5CCNAME'"
  98         openssl=$(find_working openssl)
  99         if [ -n "$openssl" ]; then
 100           echo >&3 "KRB5OPENSSL='$openssl'"
 101           echo >&3 "KRB5BASE64='$($openssl enc -a -in $ccname)'"
 102         fi
 103       fi
 104     fi
 105   fi
 106   if [ -n "$DISPLAY" -a -n "$COOKIE" ]; then
 107     echo >&3 "xauth add $COOKIE"
 108   else
 109     echo >&3 "unset DISPLAY"
 110   fi
 111   if [ ! "$PROFILE_HOME" = "$HOME" ]; then
 112     echo >&3 "export SCREENRC=$PROFILE_HOME/.screenrc"
 113   fi
 114 else
 115   exit 111
 116 fi
 117
 118 echo >&3 ". ${PROFILE_HOME:-$HOME}/.bash_profile"
 119 for profile in "$allusersprofile" "$userprofile"; do
 120   [ -f "$profile" ] && cat >&3 2>/dev/null "$profile"
 121 done
 122 for environment in "$allusersenvironment" "$userenvironment"; do
 123   [ -f "$environment" ] || continue
 124   while read -d $'\n' variable; do
 125     variable=${variable%%=*}
 126     eval "[ -z \${$variable:+set} ] || echo >&3 \"$variable='\$$variable'\""
 127   done < "$environment"
 128 done
 129 [ $chdir = 1 ] && echo >&3 2>/dev/null "cd - &>/dev/null"
 130
 131 exec 3>&-
 132 dir=$(dirname "$0")
 133 [ "$dir" = "." ] && dir="$PWD"
 134 exec sudo -H -u "$user" "$dir/became"
 135 exit 111