[lxc-devel] [PATCH] CentOS and Fedora Templates: Harden root passwords and add static MAC network addresses.
Michael H. Warfield
mhw at WittsEnd.com
Mon Jan 13 19:03:49 UTC 2014
Hey,
On Mon, 2014-01-13 at 18:13 +0200, Marian Marinov wrote:
> On 12/27/2013 01:08 AM, Michael H. Warfield wrote:
> > CentOS and Fedora Templates: Harden root passwords and add static MAC network addresses.
> >
> > 1) Add logic to root password setting. Root password is now set to
> > "Root-${name}-${RANDOM} to defeat common brute force scans.
> > 2) Enhance exit messages to explain root password and password changing.
> > 3) Add random generated hwaddr (MAC) entires for any network interfaces
> > in default config copied to container.
> I'm using both the fedora and centos templates and having a static MAC is a problem.
I don't understand what you're saying here. The code to create static
MAC addresses was never committed to the repository (as I've just
learned from Serge).
> I have replaced static MAC with $(gen_mac) shell function.
Since the code for creating a static MAC never existed in templates you
were using, I'm not sure how you "replaced" it per se. I've resubmitted
patches for that code now, and it's waiting approval.
> function gen_mac() {
> mac_vars=(0 1 2 3 4 5 6 7 8 9 a b c d e f)
> mac_base='52:53:54:'
> ret=''
> for i in {1..6}; do
> n=$RANDOM
> let 'n %= 16'
> ret="${ret}${mac_vars[$n]}"
> if [ $i -eq 2 ] || [ $i -eq 4 ]; then
> ret="${ret}:"
> fi
> done
> echo "${mac_base}${ret}"
> }
I really don't like the above function as it's just seems unnecessarily
complex and inelegant to me.
> There is also another variant of this function:
> function gen_mac() {
> echo "52:53:54:$(openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')"
> }
Now like like this function. Use of openssl that way is attractive and
the substitution reduction by doing the global substitute in the sed
command, which that enables, is a bonus.
The function I wrote and submitted as a template patch was this:
# Generate a random hardware (MAC) address composed of FE followed by
# 5 random bytes...
create_hwaddr()
{
echo $(dd if=/dev/urandom bs=8 count=1 2>/dev/null | md5sum |
sed -e 's/\(..\)\(..\)\(..\)\(..\)\(..\).*/fe:\1:\2:\3:\4:\5/')
}
That could equally be done without the echo command and reduced further,
using the openssl command, like this:
openssl rand -hex 5 | sed -e 's/\(..\)/:\1/g; s/^/fe/'
I like that. That was a nice suggestion. Thank you. I think I'll
figure that for my next round of patches (which may or may not make 1.0)
just because it's more elegant that anything else I've seen.
Regards,
Mike
> > 4) Add shell variable expansion of default config.
> > 5) Cross patch templates to bring them more into coherence with each other.
> >
> > Signed-off-by: Michael H. Warfield <mhw at WittsEnd.com>
> > ---
> > templates/lxc-centos.in | 114 +++++++++++++++++++++++++++++++++++++-----------
> > templates/lxc-fedora.in | 99 +++++++++++++++++++++++++++++++++++++----
> > 2 files changed, 180 insertions(+), 33 deletions(-)
> >
> > diff --git a/templates/lxc-centos.in b/templates/lxc-centos.in
> > index 7d47715..5bb5349 100644
> > --- a/templates/lxc-centos.in
> > +++ b/templates/lxc-centos.in
> > @@ -33,6 +33,7 @@ default_path=@LXCPATH@
> > # We really need something better here!
> > root_password=root
> >
> > +# These are only going into comments in the resulting config...
> > lxc_network_type=veth
> > lxc_network_link=lxcbr0
> >
> > @@ -256,8 +257,10 @@ EOF
> > mknod -m 600 ${dev_path}/initctl p
> > mknod -m 666 ${dev_path}/ptmx c 5 2
> >
> > - echo "setting root passwd to $root_password"
> > + echo "Setting root passwd to '$root_password'"
> > echo "root:$root_password" | chroot $rootfs_path chpasswd
> > + # Also set this password as expired to force the user to change it!
> > + chroot $rootfs_path passwd -e root
> >
> > # This will need to be enhanced for CentOS 7 when systemd
> > # comes into play... /\/\|=mhw=|\/\/
> > @@ -374,6 +377,7 @@ copy_centos()
> > # i prefer rsync (no reason really)
> > mkdir -p $rootfs_path
> > rsync -a $cache/rootfs/ $rootfs_path/
> > + echo
> > return 0
> > }
> >
> > @@ -428,28 +432,71 @@ install_centos()
> > return $?
> > }
> >
> > -copy_configuration()
> > +create_hwaddr()
> > {
> > + echo $(dd if=/dev/urandom bs=8 count=1 2>/dev/null | md5sum
> > + | sed -e 's/\(..\)\(..\)\(..\)\(..\)\(..\).*/fe:\1:\2:\3:\4:\5/')
> > +}
> >
> > +copy_configuration()
> > +{
> > mkdir -p $config_path
> > +
> > + grep -q "^lxc.rootfs" $config_path/config 2>/dev/null || echo "
> > +lxc.rootfs = $rootfs_path
> > +" >> $config_path/config
> > +
> > + # The following code is to create static MAC addresses for each
> > + # interface in the container. This code will work for multiple
> > + # interfaces in the default config.
> > + mv $config_path/config $config_path/config.def
> > + while read LINE
> > + do
> > + # This should catch variable expansions from the default config...
> > + if expr "${LINE}" : '.*\$' > /dev/null 2>&1
> > + then
> > + LINE=$(eval "echo \"${LINE}\"")
> > + fi
> > +
> > + # There is a tab and a space in the regex bracket below!
> > + # Seems that \s doesn't work in brackets.
> > + KEY=$(expr $LINE : '\s*\([^ ]*\)\s*=')
> > +
> > + if [[ "${KEY}" != "lxc.network.hwaddr" ]]
> > + then
> > + echo ${LINE} >> $config_path/config
> > +
> > + if [[ "${KEY}" == "lxc.network.link" ]]
> > + then
> > + echo "lxc.network.hwaddr = $(create_hwaddr)" >> $config_path/config
> > + fi
> > + fi
> > + done < $config_path/config.def
> > +
> > + rm -f $config_path/config.def
> > +
> > cat <<EOF >> $config_path/config
> > lxc.utsname = $utsname
> > lxc.tty = 4
> > lxc.pts = 1024
> > -lxc.rootfs = $rootfs_path
> > -lxc.mount = $config_path/fstab
> > +lxc.mount = $config_path/fstab
> > lxc.cap.drop = sys_module mac_admin mac_override sys_time
> >
> > lxc.autodev = $auto_dev
> >
> > +# When using LXC with apparmor, uncomment the next line to run unconfined:
> > +#lxc.aa_profile = unconfined
> > +
> > # example simple networking setup, uncomment to enable
> > #lxc.network.type = $lxc_network_type
> > #lxc.network.flags = up
> > #lxc.network.link = $lxc_network_link
> > #lxc.network.name = eth0
> > -# additional example for veth network type, static MAC address,
> > -# and persistent veth device name on host side
> > +# Additional example for veth network type
> > +# static MAC address,
> > #lxc.network.hwaddr = 00:16:3e:77:52:20
> > +# persistent veth device name on host side
> > +# Note: This may potentially collide with other containers of same name!
> > #lxc.network.veth.pair = v-$name-e0
> >
> > #cgroups
> > @@ -460,8 +507,6 @@ lxc.cgroup.devices.allow = c 1:5 rwm
> > # consoles
> > lxc.cgroup.devices.allow = c 5:1 rwm
> > lxc.cgroup.devices.allow = c 5:0 rwm
> > -lxc.cgroup.devices.allow = c 4:0 rwm
> > -lxc.cgroup.devices.allow = c 4:1 rwm
> > # /dev/{,u}random
> > lxc.cgroup.devices.allow = c 1:9 rwm
> > lxc.cgroup.devices.allow = c 1:8 rwm
> > @@ -473,13 +518,12 @@ EOF
> >
> > cat <<EOF > $config_path/fstab
> > proc proc proc nodev,noexec,nosuid 0 0
> > -devpts dev/pts devpts defaults 0 0
> > sysfs sys sysfs defaults 0 0
> > EOF
> >
> > if [ $? -ne 0 ]; then
> > - echo "Failed to add configuration"
> > - return 1
> > + echo "Failed to add configuration"
> > + return 1
> > fi
> >
> > return 0
> > @@ -489,22 +533,21 @@ clean()
> > {
> >
> > if [ ! -e $cache ]; then
> > - exit 0
> > + exit 0
> > fi
> >
> > # lock, so we won't purge while someone is creating a repository
> > (
> > - flock -x 200
> > - if [ $? != 0 ]; then
> > - echo "Cache repository is busy."
> > - exit 1
> > - fi
> > -
> > - echo -n "Purging the download cache for centos-$release..."
> > - rm --preserve-root --one-file-system -rf $cache && echo "Done." || exit 1
> > - exit 0
> > + flock -x 200
> > + if [ $? != 0 ]; then
> > + echo "Cache repository is busy."
> > + exit 1
> > + fi
> >
> > - ) 200>/var/lock/subsys/lxc-centos
> > + echo -n "Purging the download cache for centos-$release..."
> > + rm --preserve-root --one-file-system -rf $cache && echo "Done." || exit 1
> > + exit 0
> > + ) 200>@LOCALSTATEDIR@/lock/subsys/lxc-centos
> > }
> >
> > usage()
> > @@ -554,6 +597,12 @@ if [ ! -z "$clean" -a -z "$path" ]; then
> > exit 0
> > fi
> >
> > +# Let's do something better for the initial root password.
> > +# It's not perfect but it will defeat common scanning brute force
> > +# attacks in the case where ssh is exposed. It will also be set to
> > +# expired, forcing the user to change it at first login.
> > +root_password=Root-${name}-${RANDOM}
> > +
> > if [ -z "${utsname}" ]; then
> > utsname=${name}
> > fi
> > @@ -572,7 +621,7 @@ fi
> > # utsname and hostname = Container_Name.Domain_Name
> >
> > if [ $(expr "$utsname" : '.*\..*\.') = 0 ]; then
> > - if [ -n "$(dnsdomainname)" ]; then
> > + if [[ "$(dnsdomainname)" != "" && "$(dnsdomainname)" != "localdomain" ]]; then
> > utsname=${utsname}.$(dnsdomainname)
> > fi
> > fi
> > @@ -666,5 +715,20 @@ if [ ! -z $clean ]; then
> > clean || exit 1
> > exit 0
> > fi
> > -echo "container rootfs and config created, default root password is '$root_password'"
> > -echo "edit the config file to check/enable networking setup"
> > +echo "
> > +Container rootfs and config have been created.
> > +Edit the config file to check/enable networking setup.
> > +"
> > +
> > +echo "The temporary password for root is: '$root_password'
> > +
> > +You may want to note that password down before starting the container.
> > +
> > +The password set up as "expired" and will require it to be changed it at
> > +first login, which you should do as soon as possible. If you lose the
> > +root password or wish to change it without starting the container, you
> > +can change it from the host by running the following command (which will
> > +also reset the expired flag):
> > +
> > + chroot ${rootfs_path} passwd
> > +"
> > diff --git a/templates/lxc-fedora.in b/templates/lxc-fedora.in
> > index 5f66ff1..b0c214a 100644
> > --- a/templates/lxc-fedora.in
> > +++ b/templates/lxc-fedora.in
> > @@ -33,6 +33,10 @@ default_path=@LXCPATH@
> > # We really need something better here!
> > root_password=root
> >
> > +# These are only going into comments in the resulting config...
> > +lxc_network_type=veth
> > +lxc_network_link=lxcbr0
> > +
> > # is this fedora?
> > # Alow for weird remixes like the Raspberry Pi
> > #
> > @@ -194,8 +198,10 @@ EOF
> > mknod -m 600 ${dev_path}/initctl p
> > mknod -m 666 ${dev_path}/ptmx c 5 2
> >
> > - echo "setting root passwd to $root_password"
> > + echo "Setting root passwd to '$root_password'"
> > echo "root:$root_password" | chroot $rootfs_path chpasswd
> > + # Also set this password as expired to force the user to change it!
> > + chroot $rootfs_path passwd -e root
> >
> > # specifying this in the initial packages doesn't always work.
> > # Even though it should have...
> > @@ -243,7 +249,7 @@ configure_fedora_init()
> >
> > configure_fedora_systemd()
> > {
> > - unlink ${rootfs_path}/etc/systemd/system/default.target
> > + rm -f ${rootfs_path}/etc/systemd/system/default.target
> > touch ${rootfs_path}/etc/fstab
> > chroot ${rootfs_path} ln -s /dev/null /etc/systemd/system/udev.service
> > chroot ${rootfs_path} ln -s /lib/systemd/system/multi-user.target /etc/systemd/system/default.target
> > @@ -837,6 +843,7 @@ copy_fedora()
> > # i prefer rsync (no reason really)
> > mkdir -p $rootfs_path
> > rsync -Ha $cache/rootfs/ $rootfs_path/
> > + echo
> > return 0
> > }
> >
> > @@ -891,11 +898,53 @@ install_fedora()
> > return $?
> > }
> >
> > -copy_configuration()
> > +# Generate a random hardware (MAC) address composed of FE followed by
> > +# 5 random bytes...
> > +create_hwaddr()
> > {
> > + echo $(dd if=/dev/urandom bs=8 count=1 2>/dev/null | md5sum |
> > + sed -e 's/\(..\)\(..\)\(..\)\(..\)\(..\).*/fe:\1:\2:\3:\4:\5/')
> > +}
> >
> > +copy_configuration()
> > +{
> > mkdir -p $config_path
> > - grep -q "^lxc.rootfs" $config_path/config 2>/dev/null || echo "lxc.rootfs = $rootfs_path" >> $config_path/config
> > +
> > + grep -q "^lxc.rootfs" $config_path/config 2>/dev/null || echo "
> > +lxc.rootfs = $rootfs_path
> > +" >> $config_path/config
> > +
> > + # The following code is to create static MAC addresses for each
> > + # interface in the container. This code will work for multiple
> > + # interfaces in the default config. It will also strip any
> > + # hwaddr stanzas out of the default config since we can not share
> > + # MAC addresses between containers.
> > + mv $config_path/config $config_path/config.def
> > + while read LINE
> > + do
> > + # This should catch variable expansions from the default config...
> > + if expr "${LINE}" : '.*\$' > /dev/null 2>&1
> > + then
> > + LINE=$(eval "echo \"${LINE}\"")
> > + fi
> > +
> > + # There is a tab and a space in the regex bracket below!
> > + # Seems that \s doesn't work in brackets.
> > + KEY=$(expr "${LINE}" : '\s*\([^ ]*\)\s*=')
> > +
> > + if [[ "${KEY}" != "lxc.network.hwaddr" ]]
> > + then
> > + echo "${LINE}" >> $config_path/config
> > +
> > + if [[ "${KEY}" == "lxc.network.link" ]]
> > + then
> > + echo "lxc.network.hwaddr = $(create_hwaddr)" >> $config_path/config
> > + fi
> > + fi
> > + done < $config_path/config.def
> > +
> > + rm -f $config_path/config.def
> > +
> > cat <<EOF >> $config_path/config
> > lxc.utsname = $utsname
> > lxc.tty = 4
> > @@ -908,6 +957,18 @@ lxc.autodev = $auto_dev
> > # When using LXC with apparmor, uncomment the next line to run unconfined:
> > #lxc.aa_profile = unconfined
> >
> > +# example simple networking setup, uncomment to enable
> > +#lxc.network.type = $lxc_network_type
> > +#lxc.network.flags = up
> > +#lxc.network.link = $lxc_network_link
> > +#lxc.network.name = eth0
> > +# Additional example for veth network type
> > +# static MAC address,
> > +#lxc.network.hwaddr = 00:16:3e:77:52:20
> > +# persistent veth device name on host side
> > +# Note: This may potentially collide with other containers of same name!
> > +#lxc.network.veth.pair = v-$name-e0
> > +
> > #cgroups
> > lxc.cgroup.devices.deny = a
> > # /dev/null and zero
> > @@ -929,6 +990,7 @@ EOF
> > proc proc proc nodev,noexec,nosuid 0 0
> > sysfs sys sysfs defaults 0 0
> > EOF
> > +
> > if [ $? -ne 0 ]; then
> > echo "Failed to add configuration"
> > return 1
> > @@ -1006,6 +1068,12 @@ if [ ! -z "$clean" -a -z "$path" ]; then
> > exit 0
> > fi
> >
> > +# Let's do something better for the initial root password.
> > +# It's not perfect but it will defeat common scanning brute force
> > +# attacks in the case where ssh is exposed. It will also be set to
> > +# expired, forcing the user to change it at first login.
> > +root_password=Root-${name}-${RANDOM}
> > +
> > if [ -z "${utsname}" ]; then
> > utsname=${name}
> > fi
> > @@ -1024,7 +1092,7 @@ fi
> > # utsname and hostname = Container_Name.Domain_Name
> >
> > if [ $(expr "$utsname" : '.*\..*\.') = 0 ]; then
> > - if [ -n "$(dnsdomainname)" ]; then
> > + if [[ "$(dnsdomainname)" != "" && "$(dnsdomainname)" != "localdomain" ]]; then
> > utsname=${utsname}.$(dnsdomainname)
> > fi
> > fi
> > @@ -1128,12 +1196,14 @@ if [ ! -z $clean ]; then
> > clean || exit 1
> > exit 0
> > fi
> > -echo "container rootfs and config created"
> > +echo "
> > +Container rootfs and config have been created.
> > +Edit the config file to check/enable networking setup.
> > +"
> >
> > if [[ -d ${cache_base}/bootstrap ]]
> > then
> > - echo "
> > -You have successfully built a Fedora container and cache. This cache may
> > + echo "You have successfully built a Fedora container and cache. This cache may
> > be used to create future containers of various revisions. The directory
> > ${cache_base}/bootstrap contains a bootstrap
> > which may no longer needed and can be removed.
> > @@ -1147,3 +1217,16 @@ This is only used in the creation of the bootstrap run-time-environment
> > and may be removed.
> > "
> > fi
> > +
> > +echo "The temporary password for root is: '$root_password'
> > +
> > +You may want to note that password down before starting the container.
> > +
> > +The password set up as "expired" and will require it to be changed it at
> > +first login, which you should do as soon as possible. If you lose the
> > +root password or wish to change it without starting the container, you
> > +can change it from the host by running the following command (which will
> > +also reset the expired flag):
> > +
> > + chroot ${rootfs_path} passwd
> > +"
> >
> >
> >
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
> >
>
> _______________________________________________
> lxc-devel mailing list
> lxc-devel at lists.linuxcontainers.org
> http://lists.linuxcontainers.org/listinfo/lxc-devel
>
--
Michael H. Warfield (AI4NB) | (770) 978-7061 | mhw at WittsEnd.com
/\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/
NIC whois: MHW9 | An optimist believes we live in the best of all
PGP Key: 0x674627FF | possible worlds. A pessimist is sure of it!
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