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I have a home server with some GUI to play internet radio using mplayer. But when I play it from the server, it wouldn't play and apache error log said access denied to to home directory.

I also use a exec(pkill mplayer) to stop a service before creating a new one.

So currently I have to add www-data to /etc/sudoer with ALL access and it worked. I tried to did /home/ but it won't start either.

So I want to know what is the best way to start mplayer from webserver without security risks.

This is my code

exec("pkill mplayer");
exec("mplayer -slave -quiet http://iedm-fl.akacast.akamaistream.net/7/293/156397/v1/auth.akacast.akamaistream.net/iedm-fl </dev/null >/dev/null 2>&1 &");
Casper
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3 Answers3

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If you want the sound to come out of the server:

Run sudo adduser www-data audio and reboot your server. This will give the user www-data permission to produce audio. After that, your original code should work. If it doesn't, try something simpler:

exec("pkill mplayer");
exec("mplayer http://iedm-fl.akacast.akamaistream.net/7/293/156397/v1/auth.akacast.akamaistream.net/iedm-fl&");
Anonymous
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I guess when you try to run something from your /home www-data probably doesn't have rights for this location.

About security i'm not so sure but you are giving www-data users rights to run mplayer as root. Therefor mplayer becomes vulnerable to exploitation.

maybe you can isolate rights to a single script to run mplayer for them. Than give this script only execute rights so it can't be eddited so easy.

TMpic
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I've been trying to do this with video, but I just couldn't get the permissions right to display mplayer on the screen. So I created a BASH script to wait for a file change with inotifywait and then run mplayer as a user with permission to use it.

#!/bin/bash
# Mplayer server
# Watches for a file to be populated; then launches mplayer
PLAYFILE=/tmp/mserver_play.txt
CONTROL=/tmp/mserver_control
if [ -f $PLAYFILE ] ; then rm -f $PLAYFILE ; fi
while true ; do
  touch $PLAYFILE
  chmod a+w $PLAYFILE
  r="$(inotifywait $PLAYFILE 2> /dev/null)"
  if [ "$(echo $r | tail -1 | cut -d' ' -f2)" != "MODIFY" ] ; then
    echo File removed or changed, exiting
    exit 1
  fi
  # The wait is over!  Play the file.
  PLAYPATH="$(head -1 $PLAYFILE)"
  rm $PLAYFILE
  # TODO: Put in security checks on PLAYPATH.

  if [[ -p $CONTROL ]]; then
    rm -f $CONTROL
  fi
  mkfifo $CONTROL
  chmod a+w $CONTROL

  mplayer -autosync 30 -mc 2 -cache 10240 -cache-min 50 -ao sdl -lavdopts skiploopfilter=all -vf cropdetect -quiet -slave -input file=$CONTROL "$PLAYPATH" 2> /dev/null > /dev/null
done

Run that script as a user with permissions to run mplayer. mplayer probably has more tags here than are necessary for either of our purposes, but it works for both video and audio. Then in PHP you just write the path you want to play into the $PLAYFILE, e.g. with file_put_contents('/tmp/mserver_play.txt', $the_file_to_play).

Security, of course, is relative. Any user can write to the file to launch mplayer, and I couldn't find an easy way to restrict that; but adding www-data to your group and removing the chmods should probably work. You might, for example, want to restrict files to play to local files with test -f $PLAYPATH, but I want the ability to use http URLs there.

Ken_g6
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