opt/bin/become

   1 #!/bin/bash
   2
   3 chdir=0
   4 kerberos=0
   5 x11=0
   6 dir=
   7 while getopts ":cd:kx" opt; do
   8   case $opt in
   9     c) chdir=1;;
  10     d) dir=$OPTARG;;
  11     k) kerberos=1;;
  12     x) x11=1;;
  13   esac
  14 done
  15 shift $((OPTIND-1))
  16
  17 if [ -z "$dir" ]; then
  18   dir=${0%/*}
  19   [ "$dir" = "$0" -o "$dir" = "." ] && dir=$PWD
  20 fi
  21
  22 user="$1"; shift
  23 if [ -z "$user" ]; then
  24   echo >&2 "Usage: become [-c] [-d <dir>] [-k] [-x] <user>"
  25   echo >&2 "Options: -c         Stay in current directory even if target user is not root."
  26   echo >&2 "         -d <dir>   Look for \"became\" script in given directory."
  27   echo >&2 "         -k         Delegate Kerberos credentials even if target user is not root."
  28   echo >&2 "         -x         Delegate X11 cookie even if target user is not root."
  29   exit 1
  30 fi
  31
  32 uid=$(PATH=/usr/xpg4/bin:/usr/bin id -u "$user" 2>/dev/null)
  33 if [ -z "$uid" ]; then
  34   echo >&2 "Who is $user?"
  35   exit 2
  36 fi
  37
  38 if [ $uid = 0 ]; then
  39   chdir=1
  40   kerberos=1
  41   x11=1
  42 fi
  43
  44 PRINCIPAL=$(klist 2>/dev/null | sed -n 's/^Default principal: //p')
  45 if [ $x11 = 1 -a -n "$DISPLAY" -a "${DISPLAY##localhost:}" = "$DISPLAY" ]; then
  46   COOKIE="$(xauth list $DISPLAY)"
  47 fi
  48 ignore_profile_user=0
  49 for candidate in "$HOME" "$PROFILE_HOME"; do
  50   [ -n "$candidate" ] || continue
  51   BECOME="$candidate/.become"
  52   [ -d "$BECOME" ] || continue
  53
  54   # Script to run when becoming any user.
  55   [ -z "$allusersprofile" ] && allusersprofile="$BECOME/all"
  56   [ -f "$allusersprofile" ] || allusersprofile=
  57
  58   # Set $HOME/all sticky to ignore $PROFILE_HOME/$user.
  59   if [ "$candidate" = "$HOME" ]; then
  60     [ -k "$BECOME/all" ] && ignore_profile_user=1
  61   else
  62     [ $ignore_profile_user = 1 ] && continue
  63   fi
  64
  65   # Script to run (after the one mentioned above) when becoming this user.
  66   [ -z "$userprofile" ] && userprofile="$BECOME/$user"
  67   [ -f "$userprofile" ] || userprofile=
  68 done
  69
  70 # Preserve environment variables.
  71 ignore_environment_user=0
  72 for candidate in "$HOME" "$PROFILE_HOME"; do
  73   [ -n "$candidate" ] || continue
  74   BECOME="$candidate/.become/environment"
  75   [ -d "$BECOME" ] || continue
  76
  77   # Script to run when becoming any user.
  78   [ -z "$allusersenvironment" ] && allusersenvironment="$BECOME/all"
  79   [ -f "$allusersenvironment" ] || allusersenvironment=
  80
  81   # Set $HOME/all sticky to ignore $PROFILE_HOME/$user.
  82   if [ "$candidate" = "$HOME" ]; then
  83     [ -k "$BECOME/all" ] && ignore_environment_user=1
  84   else
  85     [ $ignore_environment_user = 1 ] && continue
  86   fi
  87
  88   # Environment variables to preserve when becomeing this user.
  89   [ -z "$userenvironment" ] && userenvironment="$BECOME/$user"
  90   [ -f "$userenvironment" ] || userenvironment=
  91 done
  92
  93 file="${TMPDIR:-/tmp}/$USER.become.$user.$RANDOM.$$"
  94 umask=$(builtin umask -p)
  95 builtin umask 077
  96 if exec 3>"$file" && exec <"$file" && rm "$file"; then
  97   builtin $umask
  98   echo >&3 "cd"
  99   echo >&3 "PROFILE_HOME='${PROFILE_HOME:-$HOME}'"
 100   if [ -n "$PRINCIPAL" ]; then
 101     echo >&3 "PRINCIPAL='$PRINCIPAL'"
 102     if [ $kerberos = 1 ]; then
 103       ccname=$(klist 2>/dev/null | sed -n 's/^Ticket cache: [DF]I[LR][E:]://p')
 104       if [ -f "$ccname" ]; then
 105         echo >&3 "export KRB5CCNAME='$KRB5CCNAME'"
 106         openssl=$(find_working openssl)
 107         if [ -n "$openssl" ]; then
 108           echo >&3 "KRB5OPENSSL='$openssl'"
 109           echo >&3 "KRB5BASE64='$($openssl enc -a -in $ccname)'"
 110         fi
 111       fi
 112     fi
 113   fi
 114   if [ -n "$DISPLAY" -a -n "$COOKIE" ]; then
 115     echo >&3 "xauth add $COOKIE"
 116   else
 117     echo >&3 "unset DISPLAY"
 118   fi
 119   if [ ! "$PROFILE_HOME" = "$HOME" ]; then
 120     echo >&3 "export SCREENRC=$PROFILE_HOME/.screenrc"
 121   fi
 122 else
 123   exit 111
 124 fi
 125
 126 echo >&3 ". ${PROFILE_HOME:-$HOME}/.bash_profile"
 127 for profile in "$allusersprofile" "$userprofile"; do
 128   [ -f "$profile" ] && cat >&3 2>/dev/null "$profile"
 129 done
 130 for environment in "$allusersenvironment" "$userenvironment"; do
 131   [ -f "$environment" ] || continue
 132   while read -d $'\n' variable; do
 133     variable=${variable%%=*}
 134     eval "[ -z \${$variable:+set} ] || echo >&3 \"$variable='\$$variable'\""
 135   done < "$environment"
 136 done
 137 [ $chdir = 1 ] && echo >&3 2>/dev/null "cd - &>/dev/null"
 138
 139 exec 3>&-
 140 exec sudo -H -u "$user" "$dir/became"
 141 exit 111