unsafe-browser

#!/bin/sh

set -e

CMD=$(basename ${0})
LOCK=/var/lock/${CMD}

. gettext.sh
TEXTDOMAIN="tails"
export TEXTDOMAIN

CONF_DIR=/var/lib/unsafe-browser
COW=${CONF_DIR}/cow
CHROOT=${CONF_DIR}/chroot
CLEARNET_USER=clearnet

# Import tor_is_working()
. /usr/local/lib/tails-shell-library/tor.sh

# Import the TBB_INSTALL, TBB_EXT and TBB_PROFILE variables, and
# exec_firefox(), configure_xulrunner_app_locale() and
# guess_best_tor_browser_locale()
. /usr/local/lib/tails-shell-library/tor-browser.sh

. /usr/local/lib/tails-shell-library/chroot-browser.sh

WARNING_PAGE='/usr/share/doc/tails/website/misc/unsafe_browser_warning'
LANG_CODE="$(echo ${LANG} | head -c 2)"
if [ -r "${WARNING_PAGE}.${LANG_CODE}.html" ]; then
   START_PAGE="${WARNING_PAGE}.${LANG_CODE}.html"
else
   START_PAGE="${WARNING_PAGE}.en.html"
fi

if [ -e /var/lib/gdm3/tails.camouflage ]; then
    CAMOUFLAGE=yes
fi

cleanup () {
    try_cleanup_browser_chroot ${CHROOT} ${COW} ${CLEARNET_USER}
}

error () {
    local cli_text="${CMD}: `gettext \"error:\"` ${@}"
    local dialog_text="<b><big>`gettext \"Error\"`</big></b>

${@}"
    echo "${cli_text}" >&2
    sudo -u ${SUDO_USER} zenity --error --title "" --text "${dialog_text}"
    exit 1
}

verify_start () {
    # Make sure the user really wants to start the browser
    local dialog_msg="<b><big>`gettext \"Do you really want to launch the Unsafe Browser?\"`</big></b>

`gettext \"Network activity within the Unsafe Browser is <b>not anonymous</b>. Only use the Unsafe Browser if necessary, for example if you have to login or register to activate your Internet connection.\"`"
    local launch="`gettext \"_Launch\"`"
    local exit="`gettext \"_Exit\"`"
    # Since zenity can't set the default button to cancel, we switch the
    # labels and interpret the return value as its negation.
    if sudo -u ${SUDO_USER} zenity --question --title "" --ok-label "${exit}" \
       --cancel-label "${launch}" --text "${dialog_msg}"; then
        exit 0
    fi
}

show_start_notification () {
    local title="`gettext \"Starting the Unsafe Browser...\"`"
    local body="`gettext \"This may take a while, so please be patient.\"`"
    tails-notify-user "${title}" "${body}" 10000
}

setup_chroot () {
    # Setup a chroot on an aufs "fork" of the filesystem.
    # FIXME: When LXC matures to the point where it becomes a viable option
    # for creating isolated jails, the chroot can be used as its rootfs.
    echo "* Setting up chroot"

    trap cleanup INT
    trap cleanup EXIT

    local rootfs_dir
    local rootfs_dirs_path=/lib/live/mount/rootfs
    local tails_module_path=/lib/live/mount/medium/live/Tails.module
    local aufs_dirs=

    # We have to pay attention to the order we stack the filesystems;
    # newest must be first, and remember that the .module file lists
    # oldest first, newest last.
    while read rootfs_dir; do
        rootfs_dir="${rootfs_dirs_path}/${rootfs_dir}"
        mountpoint -q "${rootfs_dir}" && \
        aufs_dirs="${rootfs_dir}=rr+wh:${aufs_dirs}"
    done < "${tails_module_path}"
    # But our copy-on-write dir must be at the very top.
    aufs_dirs="${COW}=rw:${aufs_dirs}"

    mkdir -p ${COW} ${CHROOT} && \
    mount -t tmpfs tmpfs ${COW} && \
    mount -t aufs -o "noatime,noxino,dirs=${aufs_dirs}" aufs ${CHROOT} && \
    mount -t proc proc ${CHROOT}/proc && \
    mount --bind /dev ${CHROOT}/dev || \
    error "`gettext \"Failed to setup chroot.\"`"

    # Workaround for todo/buggy_aufs_vs_unsafe-browser
    chmod -t ${COW}
}

set_chroot_browser_name () {
    NAME="${1}"
    LOCALE="${2}"
    EXT_DIR=${CHROOT}/"${TBB_EXT}"
    if [ "${LOCALE}" != en-US ]; then
        PACK="${EXT_DIR}/langpack-${LOCALE}@firefox.mozilla.org.xpi"
        TOP=browser/chrome
        REST=${LOCALE}/locale
    else
        PACK="${CHROOT}/${TBB_INSTALL}/browser/omni.ja"
        TOP=chrome
        REST=en-US/locale
    fi
    TMP=$(mktemp -d)
    BRANDING="${TOP}/${REST}/branding/brand.dtd"
    # Non-zero exit code due to non-standard ZIP archive.
    # The following steps will fail soon if the extraction failed anyway.
    7z x -o"${TMP}" "${PACK}" "${BRANDING}" || true
    sed -i "s/<"'!'"ENTITY\s\+brand\(Full\|Short\)Name.*$/<"'!'"ENTITY brand\1Name \"${NAME}\">/" "${TMP}/${BRANDING}"
    (cd $TMP ; 7z u -tzip "${PACK}" .)
    chmod a+r "${PACK}"
    rm -Rf "${TMP}"
}

configure_chroot () {
    echo "* Configuring chroot"

    # Set the chroot's DNS servers to those obtained through DHCP
    rm -f ${CHROOT}/etc/resolv.conf
    for NS in ${IP4_NAMESERVERS}; do
        echo "nameserver ${NS}" >> ${CHROOT}/etc/resolv.conf
    done
    chmod a+r ${CHROOT}/etc/resolv.conf

    # Remove all addons: some adds proxying, which we don't
    # want; some may change the fingerprint compared to a standard
    # Firefox install. Note: We cannot use apt-get since we don't ship its
    # lists (#6531). Too bad, APT supports globbing, while dkpg does not.
    dpkg -l 'xul-ext-*' | /bin/grep '^ii' | awk '{print $2}' | \
        xargs chroot ${CHROOT} dpkg --remove

    # Create a fresh browser profile for the clearnet user
    CLEARNET_PROFILE="${CHROOT}"/home/clearnet/.tor-browser/profile.default

    CLEARNET_EXT="${CLEARNET_PROFILE}"/extensions
    mkdir -p "${CLEARNET_EXT}"
    cp -Pr "${TBB_PROFILE}"/extensions/langpack-*.xpi "${CLEARNET_EXT}"

    CLEARNET_PREFS="${CLEARNET_PROFILE}"/preferences/prefs.js
    mkdir -p "$(dirname "${CLEARNET_PREFS}")"

    # Localization
    BEST_LOCALE="$(guess_best_tor_browser_locale)"
    configure_xulrunner_app_locale "${CLEARNET_PROFILE}" "${BEST_LOCALE}"

    # Disable proxying in the chroot
    echo 'pref("network.proxy.type", 0);' >> "${CLEARNET_PREFS}"
    echo 'pref("network.proxy.socks_remote_dns", false);' >>  "${CLEARNET_PREFS}"

    # Prevent File -> Print or CTRL+P from causing the browser to hang
    # for several minutes while trying to communicate with CUPS, since
    # access to port 631 isn't allowed through.
    echo 'pref("print.postscript.cups.enabled", false);' >> "${CLEARNET_PREFS}"
    # Hide "Get Addons" in Add-ons manager
    echo 'user_pref("extensions.getAddons.showPane", false);' >> "${CLEARNET_PREFS}"

    # Set the name (e.g. window title) of the browser
    set_chroot_browser_name "`gettext \"Unsafe Browser\"`" "${BEST_LOCALE}"

    # Set start page to something that explains what's going on
    echo 'user_pref("browser.startup.homepage", "'${START_PAGE}'");' >> \
        "${CLEARNET_PREFS}"
    BROWSER_CHROME="${CLEARNET_PROFILE}/chrome/userChrome.css"
    mkdir -p "$(dirname "${BROWSER_CHROME}")"
    cat > ${BROWSER_CHROME} << EOF
/* Required, do not remove */
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

/* Hide TorBrowser Health Report and its configuration option */
#appmenu_healthReport,
#dataChoicesTab,
#healthReport

{display: none !important}
EOF

    # Remove all bookmarks
    rm -f ${CHROOT}/"${TBB_PROFILE}"/bookmarks.html
    rm -f ${CLEARNET_PROFILE}/bookmarks.html
    rm -f ${CLEARNET_PROFILE}/places.sqlite

    chown -R clearnet:clearnet ${CHROOT}/home/clearnet/.tor-browser

    # Set a scary theme (except if we're using Windows
    # camouflage). Note that the tails-activate-win8-theme script that
    # we may run below requires that the browser profile is writable
    # by the user running the script (i.e. clearnet).
    if [ -z "${CAMOUFLAGE}" ]; then
        cat >> "${CLEARNET_PREFS}" <<EOF
pref("lightweightThemes.isThemeSelected", true);
pref("lightweightThemes.usedThemes", "[{\"id\":\"1\",\"name\":\"Unsafe Browser\",\"headerURL\":\"file:///usr/share/pixmaps/red_dot.png\",\"footerURL\":\"file:///usr/share/pixmaps/red_dot.png\",\"textcolor\":\"#FFFFFF\",\"accentcolor\":\"#CC0000\",\"updateDate\":0,\"installDate\":0}]");
EOF
    else
        # The camouflage activation script requires a dbus server for
        # properly configuring GNOME, so we start one in the chroot
        chroot ${CHROOT} sudo -H -u clearnet sh -c 'eval `dbus-launch --auto-syntax`; tails-activate-win8-theme' || :
    fi

}

run_browser_in_chroot () {
    # Start the browser in the chroot
    echo "* Starting Unsafe Browser"

    sudo -u ${SUDO_USER} xhost +SI:localuser:${CLEARNET_USER} 2>/dev/null
    chroot ${CHROOT} sudo -u ${CLEARNET_USER} /bin/sh -c \
        '. /usr/local/lib/tails-shell-library/tor-browser.sh && \
         exec_firefox -DISPLAY=:0.0 \
                      -profile /home/clearnet/.tor-browser/profile.default'
    sudo -u ${SUDO_USER} xhost -SI:localuser:${CLEARNET_USER} 2>/dev/null
}

show_shutdown_notification () {
    local title="`gettext \"Shutting down the Unsafe Browser...\"`"
    local body="`gettext \"This may take a while, and you may not restart the Unsafe Browser until it is properly shut down.\"`"
    tails-notify-user "${title}" "${body}" 10000
}

maybe_restart_tor () {
    # Restart Tor if it's not working (a captive portal may have prevented
    # Tor from bootstrapping, and a restart is the fastest way to get
    # wheels turning)
    if ! tor_is_working; then
        echo "* Restarting Tor"
        restart-tor
        if ! service tor status >/dev/null; then
            error "`gettext \"Failed to restart Tor.\"`"
        fi
    fi
}

# Prevent multiple instances of the script.
exec 9>${LOCK}
if ! flock -x -n 9; then
    error "`gettext \"Another Unsafe Browser is currently running, or being cleaned up. Please retry in a while.\"`"
fi

# Get the DNS servers that was obtained from NetworkManager, if any...
NM_ENV=/var/lib/NetworkManager/env
if [ -r "${NM_ENV}" ]; then
    . ${NM_ENV}
fi
# ... otherwise fail.
# FIXME: Or would it make sense to fallback to Google's DNS or OpenDNS?
# Some stupid captive portals may allow DNS to any host, but chances are
# that only the portal's DNS would forward to the login page.
if [ -z "${IP4_NAMESERVERS}" ]; then
    error "`gettext \"No DNS server was obtained through DHCP or manually configured in NetworkManager.\"`"
fi

verify_start
show_start_notification
setup_chroot
configure_chroot
run_browser_in_chroot
show_shutdown_notification
maybe_restart_tor

exit 0