virt-sysprep: Switch to using guestmount, add more features.

This switches virt-sysprep to use guestmount instead of guestfish.
This makes the script a little bit easier to modify for sysadmins.

This commit also adds:

 - dhcp-client-state
 - dhcp-server-state
 - logfiles
 - random-seed
 - smolt-uuid
 - yum-uuid

SELinux relabelling, and a section on security in the manual page.

2 files changed, 280 insertions, 138 deletions

diff --git a/clone/virt-sysprep.in b/clone/virt-sysprep.in
index cf4ad969..981ed964 100644
--- a/clone/virt-sysprep.in
+++ b/clone/virt-sysprep.in
@@ -21,9 +21,12 @@ unset CDPATH
 program="virt-sysprep"
 version="@PACKAGE_VERSION@"
 
+# Uncomment this to see every shell command that is executed.
+#set -x
+
 TEMP=`getopt \
         -o a:c:d:vVx \
-        --long help,add:,connect:,domain:,enable:,format::,hostname:,list-operations,verbose,version \
+        --long help,add:,connect:,domain:,enable:,format::,hostname:,list-operations,selinux-relabel,no-selinux-relabel,verbose,version \
         -n $program -- "$@"`
 if [ $? != 0 ]; then
     echo "$program: problem parsing the command line arguments"
@@ -31,18 +34,15 @@ if [ $? != 0 ]; then
 fi
 eval set -- "$TEMP"
 
-# This array accumulates the arguments we pass through to guestfish.
-declare -a guestfish
-guestfish[0]="guestfish"
-guestfish[1]="--rw"
-guestfish[2]="--listen"
-guestfish[3]="-i"
-i=4
+# This array accumulates the arguments we pass through to guestmount.
+declare -a params
+i=0
 
 verbose=
 add_params=0
 enable=
 hostname_param=localhost.localdomain
+selinux_relabel=auto
 
 usage ()
 {
@@ -59,17 +59,17 @@ usage ()
 while true; do
     case "$1" in
         -a|--add)
-            guestfish[i++]="-a"
-            guestfish[i++]="$2"
+            params[i++]="-a"
+            params[i++]="$2"
             ((add_params++))
             shift 2;;
         -c|--connect)
-            guestfish[i++]="-c"
-            guestfish[i++]="$2"
+            params[i++]="-c"
+            params[i++]="$2"
             shift 2;;
         -d|--domain)
-            guestfish[i++]="-d"
-            guestfish[i++]="$2"
+            params[i++]="-d"
+            params[i++]="$2"
             ((add_params++))
             shift 2;;
         --enable)
@@ -81,9 +81,9 @@ while true; do
             shift 2;;
         --format)
             if [ -n "$2" ]; then
-                guestfish[i++]="--format=$2"
+                params[i++]="--format=$2"
             else
-                guestfish[i++]="--format"
+                params[i++]="--format"
             fi
             shift 2;;
         --help)
@@ -94,15 +94,29 @@ while true; do
         --list-operations)
             enable=list
             shift;;
+        --selinux-relabel)
+            selinux_relabel=yes
+            shift;;
+        --no-selinux-relabel)
+            selinux_relabel=no
+            shift;;
         -v|--verbose)
-            guestfish[i++]="-v"
+            params[i++]="-v"
             verbose=yes
             shift;;
         -V|--version)
             echo "$program $version"
             exit 0;;
         -x)
-            guestfish[i++]="-x"
+            # Can't pass the -x option directly to guestmount because
+            # that stops guestmount from forking, which means we can't
+            # coordinate with guestmount when it has finished
+            # initializing.  So instead set just the underlying option
+            # in libguestfs by exporting LIBGUESTFS_TRACE.
+            # Unfortunately (a) this omits FUSE calls, but don't worry
+            # about that for now, and more importantly (b) trace
+            # messages disappear into never-never land after the fork.
+            export LIBGUESTFS_TRACE=1
             shift;;
         --)
             shift
@@ -117,23 +131,41 @@ done
 # enable all of these, although some of them are only done on certain
 # guest types (see details below).
 if [ -z "$enable" ]; then
+    dhcp_client_state=yes
+    dhcp_server_state=yes
     hostname=yes
+    logfiles=yes
     net_hwaddr=yes
+    random_seed=yes
+    smolt_uuid=yes
     ssh_hostkeys=yes
     udev_persistent_net=yes
+    yum_uuid=yes
 elif [ "$enable" = "list" ]; then
+    echo "dhcp-client-state"
+    echo "dhcp-server-state"
     echo "hostname"
+    echo "logfiles"
     echo "net-hwaddr"
+    echo "random-seed"
+    echo "smolt-uuid"
     echo "ssh-hostkeys"
     echo "udev-persistent-net"
+    echo "yum-uuid"
     exit 0
 else
     for opt in $(echo "$enable" | sed 's/,/ /g'); do
         case "$opt" in
+            dhcp-client-state)     dhcp_client_state=yes ;;
+            dhcp-server-state)     dhcp_server_state=yes ;;
             hostname)              hostname=yes ;;
+            logfiles)              logfiles=yes ;;
             net-hwaddr)            net_hwaddr=yes ;;
+            random-seed)           random_seed=yes ;;
+            smolt-uuid)            smolt_uuid=yes ;;
             ssh-hostkeys)          ssh_hostkeys=yes ;;
             udev-persistent-net)   udev_persistent_net=yes ;;
+            yum-uuid)              yum_uuid=yes ;;
             *)
                 echo "error: unknown --enable feature: $opt"
                 exit 1
@@ -161,126 +193,99 @@ fi
 set -e
 
 if [ "$verbose" = "yes" ]; then
-    echo command: "${guestfish[@]}"
+    echo params: "${params[@]}"
 fi
 
 # Create a temporary directory for general purpose use during operations.
 tmpdir="$(mktemp -d)"
 
-# Increase the amount of memory allocated to the appliance because
-# we're using augeas.  The user can override this by setting
-# $LIBGUESTFS_MEMSIZE before running the script.
-export LIBGUESTFS_MEMSIZE=${LIBGUESTFS_MEMSIZE:-2048}
-
-# Call guestfish.
-GUESTFISH_PID=
-eval $("${guestfish[@]}")
-if [ -z "$GUESTFISH_PID" ]; then
-    echo "$program: guestfish didn't start up, see error messages above"
-    exit 1
-fi
-
-# Helper.
-gf="guestfish --remote --"
-
 cleanup ()
 {
-    $gf exit >/dev/null 2>&1 ||:
-    rm -rf "$tmpdir" ||:
+    if [ -d $tmpdir/mnt ]; then
+        fusermount -u $tmpdir/mnt >/dev/null 2>&1 ||:
+    fi
+    rm -rf $tmpdir ||:
 }
 trap cleanup EXIT ERR
 
-# Launch back-end, inspect for operating systems, and get the guest
-# root disk.
-root=$($gf inspect-get-roots)
-
-if [ "$root" = "" ]; then
-    echo "$program: no operating system was found on this disk"
-    exit 1
-fi
-
-if [ "$verbose" = "yes" ]; then
-    echo root: "$root"
-fi
-
-# Get the guest type.
-type="$($gf -inspect-get-type $root)"
+# Run virt-inspector and grab inspection information about this guest.
+virt-inspector "${params[@]}" > $tmpdir/xml
+xmlstarlet sel -t -c \
+    "string(/operatingsystems/operatingsystem[position()=1]/name)" \
+    $tmpdir/xml > $tmpdir/type
+xmlstarlet sel -t -c \
+    "string(/operatingsystems/operatingsystem[position()=1]/distro)" \
+    $tmpdir/xml > $tmpdir/distro ||:
+xmlstarlet sel -t -c \
+    "string(/operatingsystems/operatingsystem[position()=1]/package_format)" \
+    $tmpdir/xml > $tmpdir/package_format ||:
+xmlstarlet sel -t -c \
+    "string(/operatingsystems/operatingsystem[position()=1]/package_management)" \
+    $tmpdir/xml > $tmpdir/package_management ||:
+
+type="$(cat $tmpdir/type)"
+distro="$(cat $tmpdir/distro)"
+package_format="$(cat $tmpdir/package_format)"
+package_management="$(cat $tmpdir/package_management)"
+
+# Mount the disk.
+mkdir $tmpdir/mnt
+guestmount --rw -i "${params[@]}" $tmpdir/mnt
+
+mnt="$tmpdir/mnt"
 
-if [ "$type" = "linux" ]; then
-    distro="$($gf -inspect-get-distro $root)"
-fi
+#----------------------------------------------------------------------
+# The sysprep operations.
 
-if [ "$type" = "windows" ]; then
-    systemroot="$($gf -inspect-get-windows-systemroot $root)"
+if [ "$dhcp_client_state" = "yes" ]; then
+    case "$type" in
+        linux)
+            rm -rf $mnt/var/lib/dhclient/*
+            # RHEL 3:
+            rm -rf $mnt/var/lib/dhcp/*
+            ;;
+    esac
 fi
 
-# Start Augeas if it's a Linux guest.
-if [ "$type" = "linux" ]; then
-    $gf aug-init / 0
-    using_augeas=yes
+if [ "$dhcp_server_state" = "yes" ]; then
+    case "$type" in
+        linux)
+            rm -rf $mnt/var/lib/dhcpd/*
+            ;;
+    esac
 fi
 
-#----------------------------------------------------------------------
-# Useful functions.
-
-# erase_line filename regex
-#
-# Erase line(s) in a file that match the given regex.
-erase_line ()
-{
-    $gf download "$1" "$tmpdir/file"
-    sed "/$2/d" < "$tmpdir/file" > "$tmpdir/file.1"
-    $gf upload "$tmpdir/file.1" "$1"
-}
-
-# prepend_line filename line
-#
-# Prepend a line to a file (this is better than appending, because it
-# works even when the original file isn't terminated with a newline).
-prepend_line ()
-{
-    $gf download "$1" "$tmpdir/file"
-    echo "$2" > "$tmpdir/file.1"
-    cat "$tmpdir/file.1" "$tmpdir/file" >> "$tmpdir/file.2"
-    $gf upload "$tmpdir/file.2" "$1"
-}
-
-# rm_files wildcard
-#
-# Remove files.  Doesn't fail if no files exist.  Note the wildcard
-# parameter cannot contain spaces or characters that need special
-# quoting.
-rm_files ()
-{
-    files=$($gf glob-expand "$1")
-    for f in $files; do
-        $gf rm "$f"
-    done
-}
-
-# rm_file filename
-#
-# Remove a single file.  No error if the file doesn't exist or is not
-# a file.
-rm_file ()
-{
-    t=$($gf is-file "$1")
-    if [ "$t" = "true" ]; then
-        $gf rm "$1"
-    fi
-}
-
-#----------------------------------------------------------------------
-# The sysprep operations.
-
 if [ "$hostname" = "yes" ]; then
     case "$type/$distro" in
         linux/fedora)
-            $gf aug-set /files/etc/sysconfig/network/HOSTNAME "$hostname_param"
-            augeas_save_needed=yes
+            echo "HOSTNAME=$hostname_param" > $mnt/etc/sysconfig/network.new
+            sed '/^HOSTNAME=/d' < $mnt/etc/sysconfig/network >> $mnt/etc/sysconfig/network.new
+            mv -f $mnt/etc/sysconfig/network.new $mnt/etc/sysconfig/network
+            created_files=yes
             ;;
         linux/debian|linux/ubuntu)
-            $gf write /etc/hostname "$hostname_param"
+            echo "$hostname_param" > $mnt/etc/hostname
+            created_files=yes
+            ;;
+    esac
+fi
+
+if [ "$logfiles" = "yes" ]; then
+    case "$type" in
+        linux)
+            rm -rf $mnt/var/log/*.log*
+            rm -rf $mnt/var/log/audit/*
+            rm -rf $mnt/var/log/btmp*
+            rm -rf $mnt/var/log/cron*
+            rm -rf $mnt/var/log/dmesg*
+            rm -rf $mnt/var/log/lastlog*
+            rm -rf $mnt/var/log/maillog*
+            rm -rf $mnt/var/log/mail/*
+            rm -rf $mnt/var/log/messages*
+            rm -rf $mnt/var/log/secure*
+            rm -rf $mnt/var/log/spooler*
+            rm -rf $mnt/var/log/tallylog*
+            rm -rf $mnt/var/log/wtmp*
             ;;
     esac
 fi
@@ -288,35 +293,77 @@ fi
 if [ "$net_hwaddr" = "yes" ]; then
     case "$type/$distro" in
         linux/fedora)
-            # XXX these filenames can have spaces and untrusted chars in them!
-            nodes=$( $gf aug-ls /files/etc/sysconfig/network-scripts |
-                     grep /files/etc/sysconfig/network-scripts/ifcfg- )
-            for node in $nodes; do
-                $gf -aug-rm "$node/HWADDR" >/dev/null
-                augeas_save_needed=yes
-            done
+            if [ -d $mnt/etc/sysconfig/network-scripts ]; then
+                rm_hwaddr ()
+                {
+                    sed '/^HWADDR=/d' < "$1" > "$1.new"
+                    mv -f "$1.new" "$1"
+                }
+                export -f rm_hwaddr
+                find $mnt/etc/sysconfig/network-scripts \
+                    -name 'ifcfg-*' -type f \
+                    -exec bash -c 'rm_hwaddr "$0"' {} \;
+                created_files=yes
+            fi
             ;;
     esac
 fi
 
+if [ "$random_seed" = "yes" -a "$type" = "linux" ]; then
+    f=
+    if [ -f $mnt/var/lib/random-seed ]; then
+        # Fedora
+        f=$mnt/var/lib/random-seed
+    elif [ -f $mnt/var/lib/urandom/random-seed ]; then
+        # Debian
+        f=$mnt/var/lib/urandom/random-seed
+    fi
+    if [ -n "$f" ]; then
+        dd if=/dev/random of="$f" bs=8 count=1 conv=nocreat,notrunc 2>/dev/null
+    fi
+fi
+
+if [ "$smolt_uuid" = "yes" -a "$type" = "linux" ]; then
+    rm -f $mnt/etc/sysconfig/hw-uuid
+    rm -f $mnt/etc/smolt/uuid
+    rm -f $mnt/etc/smolt/hw-uuid
+fi
+
 if [ "$ssh_hostkeys" = "yes" -a "$type" != "windows" ]; then
-    rm_files "/etc/ssh/*_host_*"
+    rm -rf $mnt/etc/ssh/*_host_*
 fi
 
 if [ "$udev_persistent_net" = "yes" -a "$type" = "linux" ]; then
-    rm_file /etc/udev/rules.d/70-persistent-net.rules
+    rm -f $mnt/etc/udev/rules.d/70-persistent-net.rules
+fi
+
+if [ "$yum_uuid" = "yes" -a "$package_management" = "yum" ]; then
+    rm -f $mnt/var/lib/yum/uuid
 fi
 
 #----------------------------------------------------------------------
 # Clean up and close down.
 
-if [ "$using_augeas" = "yes" -a "$augeas_save_needed" = "yes" ]; then
-    $gf aug-save
-    $gf aug-close
-fi
+# If we created any new files and the guest uses SELinux, then we have
+# to relabel the filesystem on boot.  Could do with a better way to
+# test "guest uses SELinux" (XXX).
+case "$selinux_relabel/$created_files" in
+    yes/*)
+        touch $mnt/.autorelabel;;
+    auto/yes)
+        case "$type/$distro" in
+            linux/fedora|linux/rhel|linux/centos|linux/scientificlinux|linux/redhat-based)
+                touch $mnt/.autorelabel
+                ;;
+        esac
+        ;;
+esac
+
+sync
+
+fusermount -u $tmpdir/mnt
+rm -rf $tmpdir
 
-$gf umount-all
-$gf sync
-$gf exit
+trap - EXIT ERR
 
 exit 0
diff --git a/clone/virt-sysprep.pod b/clone/virt-sysprep.pod
index cc8e44f4..fa10b9ea 100755
--- a/clone/virt-sysprep.pod
+++ b/clone/virt-sysprep.pod
@@ -26,6 +26,12 @@ must be shut down.  If you want to preserve the existing contents of
 the guest, you I<must copy or clone the disk first>.
 See L</COPYING AND CLONING> below.
 
+You do I<not> need to run virt-sysprep as root.  In fact we'd
+generally recommend that you don't.  The time you might want to run it
+as root is when you need root in order to access the disk image, but
+even in this case it would be better to change the permissions on the
+disk image to be writable as the non-root user running virt-sysprep.
+
 "Sysprep" stands for "system preparation" tool.  The name comes from
 the Microsoft program C<sysprep.exe> which is used to unconfigure
 Windows machines in preparation for cloning them.  Having said that,
@@ -119,6 +125,16 @@ If not given, defaults to C<localhost.localdomain>.
 
 List the operations supported by the virt-sysprep program.
 
+=item B<--selinux-relabel>
+
+=item B<--no-selinux-relabel>
+
+I<--selinux-relabel> forces SELinux relabelling next time the guest
+boots.  I<--no-selinux-relabel> disables relabelling.
+
+The default is to try to detect if SELinux relabelling is required.
+See L</SELINUX RELABELLING> below for more details.
+
 =item B<-v>
 
 =item B<--verbose>
@@ -151,22 +167,45 @@ Use a comma-separated list, for example:
 To list the operations supported by the current version of
 virt-sysprep, use I<--list-operations>.
 
+=head2 dhcp-client-state
+
+Remove DHCP client leases.
+
+=head2 dhcp-server-state
+
+Remove DHCP server leases.
+
 =head2 hostname
 
-This changes the hostname of the guest to the value given in the
+Changes the hostname of the guest to the value given in the
 I<--hostname> parameter.
 
 If the I<--hostname> parameter is not given, then the hostname is
 changed to C<localhost.localdomain>.
 
+=head2 logfiles
+
+Remove many log files.
+
 =head2 net-hwaddr
 
 Remove HWADDR (hard-coded MAC address) configuration.  For Fedora and
 Red Hat Enterprise Linux, this is removed from C<ifcfg-*> files.
 
+=head2 random-seed
+
+Write some random bytes from the host into the random seed file of
+the guest.
+
+See C</RANDOM SEED> below.
+
+=head2 smolt-uuid
+
+Remove the Smolt hardware UUID.
+
 =head2 ssh-hostkeys
 
-This erases the SSH host keys in the guest.
+Remove the SSH host keys in the guest.
 
 The SSH host keys are regenerated (differently) next time the guest is
 booted.
@@ -181,14 +220,21 @@ you a stark warning about the host key changing:
 
 =head2 udev-persistent-net
 
-This erases udev persistent net rules which map the guest's existing
-MAC address to a fixed ethernet device (eg. eth0).
+Remove udev persistent net rules which map the guest's existing MAC
+address to a fixed ethernet device (eg. eth0).
 
 After a guest is cloned, the MAC address usually changes.  Since the
 old MAC address occupies the old name (eg. eth0), this means the fresh
 MAC address is assigned to a new name (eg. eth1) and this is usually
 undesirable.  Erasing the udev persistent net rules avoids this.
 
+=head2 yum-uuid
+
+Remove the yum UUID.
+
+yum creates a fresh UUID the next time it runs when it notices that
+the original UUID has been erased.
+
 =head1 COPYING AND CLONING
 
 Virt-sysprep can be used as part of a process of cloning guests, or to
@@ -356,6 +402,54 @@ to pay for disk space), then instead of copying the template, you can
 run L<virt-resize(1)>.  Virt-resize performs a copy and resize, and
 thus is ideal for cloning guests from a template.
 
+=head1 SECURITY
+
+Although virt-sysprep removes some sensitive information from
+the guest, it does not pretend to remove all of it.  You should
+examine the L</OPERATIONS> above, and the implementation of
+the operations in the shell script.
+
+You should also examine the guest afterwards.
+
+Sensitive files are simply removed.  The data they contained may still
+exist on the disk, easily recovered with a hex editor or undelete
+tool.  Use L<virt-sparsify(1)> as one way to remove this content.  See
+also the L<scrub(1)> command to get rid of deleted content in
+directory entries and inodes.
+
+=head2 RANDOM SEED
+
+I<(This section applies to Linux guests only)>
+
+The virt-sysprep C<random-seed> operation writes a few bytes of
+randomness from the host into the guest's random seed file.
+
+If this is just done once and the guest is cloned from the same
+template, then each guest will start with the same entropy, and things
+like SSH host keys and TCP sequence numbers may be predictable.
+
+Therefore you should arrange to add more randomness I<after> cloning
+from a template too, which can be done by just enabling the
+C<random-seed> operation:
+
+ cp template.img newguest.img
+ virt-sysprep --enable=random-seed -a newguest.img
+
+=head2 SELINUX RELABELLING
+
+I<(This section applies to Linux guests using SELinux only)>
+
+If any new files are created by virt-sysprep, then virt-sysprep
+touches C</.autorelabel> so that these will be correctly labelled by
+SELinux the next time the guest is booted.  This process interrupts
+boot and can take some time.
+
+You can force relabelling for all guests by supplying the
+I<--selinux-relabel> option.
+
+You can disable relabelling entirely by supplying the
+I<--no-selinux-relabel> option.
+
 =head1 SHELL QUOTING
 
 Libvirt guest names can contain arbitrary characters, some of which
@@ -376,8 +470,9 @@ L<virt-rescue(1)>,
 L<virt-resize(1)>,
 L<virt-sparsify(1)>,
 L<virsh(1)>,
-L<qemu-img(1)>,
 L<lvcreate(8)>,
+L<qemu-img(1)>,
+L<scrub(1)>,
 L<http://libguestfs.org/>,
 L<http://libvirt.org/>.