Owner and permissions in debian - bash

Question

I've just installed DEBIAN today and installed XXXXX application.
This application create ~/.XXXXX/ folder configuration.
I find that the ~/.XXXXX folder is owned by root. Applying any change for instance, then closing and reopening XXXXX, should reflect the applied change.
However, any channel or setting change is forgotten immediately.
A simple chown command solves all.
I was a little confused to start with when I couldn't save my settings... but a little digging shows the problem. It's a little annoying, and the only additional application I've installed so far which behaves this way, which kinda singles it out.
Because this application not have maintainer, I want to resolve this problem for another users.
I beleve that the proble is in debian/postinst file:
set -e
setuid () {
db_get XXXXX/setuid
if [ -x /usr/bin/XXXXX ] && [ "$RET" = "false" ] ; then
if [ ! -x /usr/sbin/dpkg-statoverride ] ||\
! /usr/sbin/dpkg-statoverride --list /usr/bin/XXXXX >/dev/null; then
chown root:root /usr/bin/XXXXX
chmod u=rwx,go=rx /usr/bin/XXXXX
fi
else
if [ ! -x /usr/sbin/dpkg-statoverride ] || \
! /usr/sbin/dpkg-statoverride --list /usr/bin/XXXXX >/dev/null; then
chown root:root /usr/bin/XXXXX
chmod u=rwxs,go=rx /usr/bin/XXXXX
fi
fi
}
# Parse the option requested from XXXXX-configure
get_option () {
OPTION=`XXXXX-configure --$1 2>/dev/null | awk -F: '{ print \$2 }'`
}
suck_XXXXX_xml () {
# If XXXXX-configure was not there at Debconf, but
# /etc/XXXXX/XXXXX.xml was, then we presume that the
# administrator knew what he was doing. We will therefore suck
# this information into the Debconf database now that
# XXXXX-configure is installed.
if [ -f /etc/XXXXX/debconf.XXXXX.xml ]; then
get_option norm
db_set XXXXX/norm "$OPTION"
get_option frequencies
db_set XXXXX/frequencies-ntsc "$OPTION"
db_set XXXXX/frequencies-jp "$OPTION"
db_set XXXXX/frequencies-pal "$OPTION"
get_option device
db_set XXXXX/v4ldevice "$OPTION"
get_option vbidevice
db_set XXXXX/vbidevice "$OPTION"
get_option priority
db_set XXXXX/processpriority "$OPTION"
fi
}
### MAIN POSTINST ###
case "$1" in
configure)
# Load Debconf library
. /usr/share/debconf/confmodule
# Handle the setuid bit.
setuid
# Load /etc/XXXXX/XXXXX.xml into Debconf, if necessary
suck_XXXXX_xml
# Try to set the /var/run/XXXXX directory to video group
if [ -d /var/run/XXXXX ] ; then
if [ ! -x /usr/sbin/dpkg-statoverride ] || \
! /usr/sbin/dpkg-statoverride --list /var/run/XXXXX >/dev/null; then
chmod ug=rwx,o=rxt /var/run/XXXXX
chown root:video /var/run/XXXXX
fi
fi
CONFIGFILE=/etc/XXXXX/XXXXX.xml
db_get XXXXX/norm
NORM=$RET
case "$NORM" in
NTSC|PAL-M|PAL-Nc)
db_get XXXXX/frequencies-ntsc
case "$RET" in
Cable) FREQTABLE=us-cable ;;
Broadcast) FREQTABLE=us-broadcast ;;
*) FREQTABLE=us-cable100 ;;
esac
;;
NTSC-JP)
db_get XXXXX/frequencies-jp
case "$RET" in
Cable) FREQTABLE=japan-cable ;;
*) FREQTABLE=japan-broadcast ;;
esac
;;
PAL|PAL-60|PAL-N|SECAM)
db_get XXXXX/frequencies-pal
case "$RET" in
Europe) FREQTABLE=europe ;;
France) FREQTABLE=france ;;
Russia) FREQTABLE=russia ;;
Australia) FREQTABLE=australia ;;
"New Zealand") FREQTABLE=newzealand ;;
"China Broadcast") FREQTABLE=china-broadcast ;;
"Australia Optus cable") FREQTABLE=australia-optus ;;
*) FREQTABLE=custom ;;
esac
;;
*)
FREQTABLE=custom
;;
esac
db_get XXXXX/v4ldevice
V4LDEV=$RET
db_get XXXXX/vbidevice
VBIDEV=$RET
db_get XXXXX/processpriority
PRI=$RET
db_stop
# Create the configuration file if it doesn't exist
if [ ! -f $CONFIGFILE ]; then
cp /usr/share/doc/XXXXX/examples/default.XXXXX.xml $CONFIGFILE
fi
# Configure XXXXX.
XXXXX-configure --configfile="$CONFIGFILE" --norm="$NORM" \
--frequencies="$FREQTABLE" --device="$V4LDEV" \
--vbidevice="$VBIDEV" --priority="$PRI" 2>/dev/null
;;
abort-upgrade|abort-remove|abort-deconfigure)
;;
*)
echo "postinst called with unknown argument \`$1'" >&2
exit 1
;;
esac
Any help is welcome,
Regards.
From app code
int mkdir_and_force_owner( const char *path, uid_t uid, gid_t gid )
{
if( mkdir( path, S_IRWXU ) < 0 ) {
if( errno != EEXIST ) {
lfprintf( stderr, _("Cannot create %s: %s\n"),
path, strerror( errno ) );
} else {
/* It exists, make sure it's a directory. */
DIR *temp_dir = opendir( path );
if( !path ) {
lfprintf( stderr, _("Cannot open %s: %s\n"),
path, strerror( errno ) );
} else {
closedir( temp_dir );
return 1;
}
}
} else {
/* We created the directory, now force it to be owned by the user. */
if( chown( path, uid, gid ) < 0 ) {
lfprintf( stderr, _("Cannot change owner of %s: %s.\n"),
path, strerror( errno ) );
} else {
return 1;
}
}
return 0;
}
ct->uid = getuid();
/* Make the ~/.XXXXX directory every time on startup, to be safe. */
if( asprintf( &temp_dirname, "%s/.XXXXX", getenv( "HOME" ) ) < 0 ) {
/* FIXME: Clean up ?? */
return 0;
}
mkdir_and_force_owner( temp_dirname, ct->uid, getgid() );
free( temp_dirname );
This is main app with create initial directory in home. Drop root privileges as early as possible. Only re-enable them to get access to the real-time scheduler. This not work in debian.
int main( int argc, char **argv )
{
rtctimer_t *rtctimer = 0;
int read_stdin = 1;
int result = 0;
int realtime = 0;
uid_t priv_uid = geteuid();
uid_t user_uid = getuid();
/*
* Temporarily drop down to user-level access, so that files aren't
* created setuid root.
*/
if( seteuid( user_uid ) == -1 ) {
lfprintf( stderr, _("\n"
" Failed to drop root privileges: %s.\n"
" motv will now exit to avoid security problems.\n\n"),
strerror( errno ) );
return 1;
}
setup_i18n();
setup_utf8();
lfprintf( stderr, _("Running %s.\n"), PACKAGE_STRING );
/* Steal system resources in the name of performance. */
/* Get maximum priority before dropping root privileges. We'll drop back */
/* to the value specified in the config file (or the default) later. */
seteuid( priv_uid );
setpriority( PRIO_PROCESS, 0, -19 );
if( set_realtime_priority( 0 ) ) {
realtime = 1;
}
rtctimer = rtctimer_new( 0 );
if( rtctimer ) {
if( !rtctimer_set_interval( rtctimer, 1024 ) &&
!rtctimer_set_interval( rtctimer, 64 ) ) {
rtctimer_delete( rtctimer );
rtctimer = 0;
} else {
rtctimer_start_clock( rtctimer );
if( rtctimer_get_resolution( rtctimer ) < 1024 ) {
rtctimer_delete( rtctimer );
rtctimer = 0;
}
}
}
/* We've now stolen all our root-requiring resources, drop to a user. */
if( setuid( user_uid ) == -1 ) {
/*
* This used to say "Unknown problems", but we're printing an
* error string, so that didn't really make sense, did it?
*/
lfprintf( stderr, _("\n"
" Failed to drop root privileges: %s.\n"
" motv will now exit to avoid security problems.\n\n"),
strerror( errno ) );
return 1;
}
/* Ditch stdin early. */
if( isatty( STDIN_FILENO ) ) {
read_stdin = 0;
close( STDIN_FILENO );
}
/* Run motv. */
for(;;) {
if( result == 2 ) {
char *new_argv[ 2 ];
new_argv[ 0 ] = "motv";
new_argv[ 1 ] = 0;
result = motv_main( rtctimer, read_stdin, realtime, 0, new_argv );
} else {
result = motv_main( rtctimer, read_stdin, realtime, argc, argv );
}
if( result != 2 ) break;
}
if( rtctimer ) {
rtctimer_delete( rtctimer );
}
return result;
}

Answer 1

The problem is not created by the debian package postinst script because it never creates the ~/.XXXXX directory.
Check the values of ct->uid and getgid() when you call mkdir_and_force_owner(): that function is not called on your main() so I cannot read how you are calling it.
You have to be sure that they are not 0 and 0: print the values for debug. In this case the function will create and chown() the dir root:root; BTW you are running the software as root due to the setuid bit, otherwise you couldn't chown() your configuration dir.