Remove special elevated privileges for the Web Interface (#536)

* Use the pi_shutdown method to restart the rascsi service

* Use the pi_shutdown method to restart the rascsi service

* Remove modifications to sudoers no longer needed

* Introduce sleeps attempting to connect to socket; reduce overall number of retries

* Remove systemd helped methods and the functionality that depends on it

* Attempts to speed up splash code

* Remove unneccessary verbosity

* Attempt to optimize service definition

easyinstall.sh

@@ -113,18 +113,6 @@ function installRaScsiWebInterface() {
 
     sudo usermod -a -G $USER www-data
 
-    if [[ `sudo grep -c "rascsi" /etc/sudoers` -eq 0 ]]; then
-        sudo bash -c 'echo "
-# Allow the web server to restart the rascsi service
-www-data ALL=NOPASSWD: /bin/systemctl restart rascsi.service
-www-data ALL=NOPASSWD: /bin/systemctl stop rascsi.service
-# Allow the web server to reboot the raspberry pi
-www-data ALL=NOPASSWD: /sbin/shutdown, /sbin/reboot
-" >> /etc/sudoers'
-    else
-        echo "The sudoers file is already modified for rascsi-web."
-    fi
-
     sudo systemctl reload nginx || true
 }
 

src/oled_monitor/monitor_rascsi.service

@@ -5,9 +5,10 @@ After=network.target rascsi.service
 [Service]
 Type=simple
 Restart=always
+RestartSec=2s
 ExecStart=/home/pi/RASCSI/src/oled_monitor/start.sh
-ExecStop=/bin/echo "Shutting down the OLED Monitor gracefully..."
 ExecStop=/bin/pkill --signal 2 -f "python3 rascsi_oled_monitor.py"
+# Sleep 2s as a crude way for the python interrupt handler to take effect and show the shutdown splash
 ExecStop=/bin/sleep 2
 SyslogIdentifier=RASCSIMON
 

src/oled_monitor/rascsi_oled_monitor.py

@@ -119,6 +119,11 @@ LINE_SPACING = 8
 # Some other nice fonts to try: http://www.dafont.com/bitmap.php
 FONT = ImageFont.truetype('type_writer.ttf', FONT_SIZE)
 
+# Load a bitmap image for start and stop splash screens and convert to monocrome
+# Make sure the splash bitmap image is in the same dir as this script
+SPLASH_START = Image.open(f"splash_start_{HEIGHT}.bmp").convert("1")
+SPLASH_STOP = Image.open(f"splash_stop_{HEIGHT}.bmp").convert("1")
+
 IP_ADDR, HOSTNAME = get_ip_and_host()
 
 
@@ -163,23 +168,18 @@ def formatted_output():
 def start_splash():
     """
     Displays a splash screen for the startup sequence
-    Make sure the splash bitmap image is in the same dir as this script
     """
-    splash = Image.open(f"splash_start_{HEIGHT}.bmp").convert("1")
-    DRAW.bitmap((0, 0), splash)
-    OLED.image(splash)
+    DRAW.bitmap((0, 0), SPLASH_START, fill=0)
+    OLED.image(SPLASH_START)
     OLED.show()
-    sleep(6)
+    sleep(4)
 
 def stop_splash():
     """
     Displays a splash screen for the shutdown sequence
-    Make sure the splash bitmap image is in the same dir as this script
     """
-    DRAW.rectangle((0, 0, WIDTH, HEIGHT), outline=0, fill=0)
-    splash = Image.open(f"splash_stop_{HEIGHT}.bmp").convert("1")
-    DRAW.bitmap((0, 0), splash)
-    OLED.image(splash)
+    DRAW.bitmap((0, 0), SPLASH_STOP, fill=0)
+    OLED.image(SPLASH_STOP)
     OLED.show()
 
 # Show a startup splash bitmap image before starting the main loop

src/oled_monitor/socket_cmds.py

@@ -5,6 +5,7 @@ and receiving results from the RaSCSI backend
 
 import socket
 from struct import pack, unpack
+from time import sleep
 
 def send_pb_command(payload):
     """
@@ -16,7 +17,7 @@ def send_pb_command(payload):
     port = 6868
 
     counter = 0
-    tries = 100
+    tries = 20
     error_msg = ""
 
     while counter < tries:
@@ -29,6 +30,7 @@ def send_pb_command(payload):
             print("The RaSCSI service is not responding - attempt %s/%s",
                   str(counter), str(tries))
             error_msg = str(error)
+            sleep(0.2)
 
     exit(error_msg)
 

src/oled_monitor/start.sh

@@ -60,9 +60,7 @@ fi
 
 # Compiler flags needed for gcc v10 and up
 if [[ `gcc --version | awk '/gcc/' | awk -F ' ' '{print $3}' | awk -F '.' '{print $1}'` -ge 10 ]]; then
-    echo -n "gcc 10 or later detected. Will compile with the following flags: "
     COMPILER_FLAGS="-fcommon"
-    echo $COMPILER_FLAGS
 fi
 
 # Test for two known broken venv states

src/web/pi_cmds.py

@@ -8,20 +8,6 @@ import logging
 from settings import AUTH_GROUP
 
 
-def systemd_service(service, action):
-    """
-    Takes (str) service and (str) action
-    Action can be any that systemctl supports, ex. start/stop/restart/show
-    Returns (dict) with (bool) status, (str) msg, (str) err
-    """
-    proc = asyncio.run(run_async(f"sudo /bin/systemctl {action} {service}"))
-    return {
-            "status": proc["returncode"] == 0,
-            "msg": proc["stdout"],
-            "err": proc["stderr"],
-            }
-
-
 def running_env():
     """
     Returns (str) git and (str) env

src/web/ractl_cmds.py

@@ -3,7 +3,6 @@ Module for commands sent to the RaSCSI backend service.
 """
 
 from settings import REMOVABLE_DEVICE_TYPES
-from pi_cmds import systemd_service
 from socket_cmds import send_pb_command
 import rascsi_interface_pb2 as proto
 
@@ -363,13 +362,6 @@ def shutdown_pi(mode):
     Takes (str) mode as an argument.
     Returns (bool) status and (str) msg.
     """
-    # This section proactively stops the monitor_rascsi systemd service, if running
-    # Otherwise, the monitor_rascsi script's interrupt handler won't take effect
-    monitor_service = "monitor_rascsi.service"
-    monitor_status = systemd_service(monitor_service, "show")
-    if "ActiveState=active" in monitor_status["msg"]:
-        systemd_service(monitor_service, "stop")
-
     command = proto.PbCommand()
     command.operation = proto.PbOperation.SHUT_DOWN
     command.params["mode"] = str(mode)

src/web/socket_cmds.py

@@ -4,6 +4,7 @@ Module for sending and receiving data over a socket connection with the RaSCSI b
 
 import logging
 from flask import abort
+from time import sleep
 
 def send_pb_command(payload):
     """
@@ -15,7 +16,7 @@ def send_pb_command(payload):
     port = 6868
 
     counter = 0
-    tries = 100
+    tries = 20
     error_msg = ""
 
     import socket
@@ -29,6 +30,7 @@ def send_pb_command(payload):
             logging.warning("The RaSCSI service is not responding - attempt %s/%s",
                             str(counter), str(tries))
             error_msg = str(error)
+            sleep(0.2)
 
     logging.error(error_msg)
 

src/web/templates/index.html

@@ -619,8 +619,8 @@
         Raspberry Pi Operations
     </summary>
     <ul>
-        <li>Issue reboot or shutdown commands to the Raspberry Pi.</li>
-        <li>You can also restart the RaSCSI backend service here.</li>
+        <li>Reboot or shut down the Raspberry Pi that RaSCSI is running on.</li>
+        <li>IMPORTANT: Always shut down the Pi before turning off the power. Failing to do so may lead to data corruption.</li>
     </ul>
 </details>
 <table style="border: none">
@@ -635,11 +635,6 @@
                 <input type="submit" value="Shut Down Raspberry Pi">
             </form>
         </td>
-        <td style="border: none; vertical-align:top;">
-            <form action="/rascsi/restart" method="post" onsubmit="return confirm('Restart RaSCSI?')">
-                <input type="submit" value="Restart RaSCSI Service">
-            </form>
-        </td>
     </tr>
 </table>
 

src/web/web.py

@@ -38,7 +38,6 @@ from file_cmds import (
 )
 from pi_cmds import (
     running_env,
-    systemd_service,
     running_proc,
     is_bridge_setup,
     disk_space,
@@ -661,38 +660,6 @@ def unreserve_id():
     flash(process["msg"], "error")
     return redirect(url_for("index"))
 
-@APP.route("/rascsi/restart", methods=["POST"])
-@login_required
-def rascsi_restart():
-    """
-    Restarts the RaSCSI backend service
-    """
-    service = "rascsi.service"
-    monitor_service = "monitor_rascsi.service"
-    rascsi_status = systemd_service(service, "show")
-    if rascsi_status["status"] and "ActiveState=active" not in rascsi_status["msg"]:
-        flash(
-                f"Failed to restart {service} because it is inactive. "
-                "You are probably running RaSCSI as a regular process.", "error"
-                )
-        return redirect(url_for("index"))
-
-    monitor_status = systemd_service(monitor_service, "show")
-    restart_proc = systemd_service(service, "restart")
-    if restart_proc["status"]:
-        flash(f"Restarted {service}")
-        restart_monitor = systemd_service(monitor_service, "restart")
-        if restart_monitor["status"] and "ActiveState=active" in monitor_status["msg"]:
-            flash(f"Restarted {monitor_service}")
-        elif not restart_monitor["status"] and "ActiveState=active" in monitor_status["msg"]:
-            flash(f"Failed to restart {monitor_service}:", "error")
-        return redirect(url_for("index"))
-
-    restart_monitor = systemd_service("monitor_rascsi.service", "restart")
-    flash(f"Failed to restart {service}:", "error")
-    flash(restart_proc["err"], "error")
-    return redirect(url_for("index"))
-
 
 @APP.route("/pi/reboot", methods=["POST"])
 @login_required