From b3d373ad52b5671234fbe6361e509fef08ac2111 Mon Sep 17 00:00:00 2001
From: Iain Patterson <me@iain.cx>
Date: Fri, 5 Mar 2010 12:14:01 +0000
Subject: [PATCH] Allow passing Kerberos credentials when becoming.

Use the -k flag to become to pass Kerberos credentials to the
target user even if this is not root.
---
 .profile.d/krb5.bashrc | 26 +++++++++++++++++---------
 opt/bin/become         | 25 +++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/.profile.d/krb5.bashrc b/.profile.d/krb5.bashrc
index 979bd71..9a1f2e9 100644
--- a/.profile.d/krb5.bashrc
+++ b/.profile.d/krb5.bashrc
@@ -61,15 +61,23 @@ if [ -z "$OLDSOLARIS" -a -z "$OLDREDHAT" ]; then
       if [ ! "$cache" = "$KRB5CCNAME" ]; then
         ccname="${cache/_$SUDO_UID/_${UID}_sudo_$SUDO_UID}_$$"
         export KRB5CCNAME="FILE:$ccname"
-        if cat "$cache" > "$ccname" 2>/dev/null; then
-          klist -s 2>/dev/null && kinit -R 2>/dev/null || kinit $PRINCIPAL
-        else
-          # XXX: Don't kinit every time if we aren't root.
-          # TODO: Split the "set my cache" and "get my credentials" parts so
-          #       that becoming a user other than root will work without
-          #       extraneous kinits.
-          rm "$ccname" 2>/dev/null
-        fi
+        (
+          umask 077
+          if cat "$cache" > "$ccname" 2>/dev/null; then
+            klist -s 2>/dev/null && kinit -R 2>/dev/null || kinit $PRINCIPAL
+          elif [ -n "$KRB5BASE64" ]; then
+            if [ -n "$KRB5OPENSSL" ]; then
+              builtin echo "$KRB5BASE64" | $KRB5OPENSSL enc -a -d -out "$ccname"
+            fi
+            unset KRB5BASE64 KRB5OPENSSL
+          else
+            # XXX: Don't kinit every time if we aren't root.
+            # TODO: Split the "set my cache" and "get my credentials" parts so
+            #       that becoming a user other than root will work without
+            #       extraneous kinits.
+            rm "$ccname" 2>/dev/null
+          fi
+        )
         trap "kdestroy 2>/dev/null" EXIT
       fi
     fi
diff --git a/opt/bin/become b/opt/bin/become
index f7f037e..9be0b9b 100755
--- a/opt/bin/become
+++ b/opt/bin/become
@@ -1,8 +1,17 @@
 #!/bin/bash
 
+kerberos=0
+while getopts ":k" opt; do
+  case $opt in
+    k) kerberos=1
+  esac
+done
+shift $((OPTIND-1))
+
 user="$1"; shift
 if [ -z "$user" ]; then
-  echo >&2 "Usage: become <user>"
+  echo >&2 "Usage: become [-k] <user>"
+  echo >&2 "Options: -k   Delegate Kerberos credentials even if target user is not root."
   exit 1
 fi
 
@@ -22,7 +31,19 @@ if [ -n "$file" ]; then
 
   echo >&3 "cd"
   echo >&3 "PROFILE_HOME='$HOME'"
-  [ -n "$PRINCIPAL" ] && echo >&3 "PRINCIPAL='$PRINCIPAL'"
+  if [ -n "$PRINCIPAL" ]; then
+    echo >&3 "PRINCIPAL='$PRINCIPAL'"
+    if [ $kerberos = 1 ]; then
+      ccname=$(klist 2>/dev/null | sed -n 's/^Ticket cache: FILE://p')
+      if [ -f "$ccname" ]; then
+        openssl=$(find_working openssl)
+        if [ -n "$openssl" ]; then
+          echo >&3 "KRB5OPENSSL='$openssl'"
+          echo >&3 "KRB5BASE64='$($openssl enc -a -in $ccname)'"
+        fi
+      fi
+    fi
+  fi
   if [ -n "$DISPLAY" -a -n "$COOKIE" ]; then
     echo >&3 "xauth add $COOKIE"
   else
-- 
2.7.4