I'm trying to configure busybox to allow a non-root user to reboot and passwd because I'm attempting to build a shell for this new user.  I've spent the afternoon researching how this is done and everything I found points to the configuration in /etc/busybox.conf  (http://www.softforge.de/bb/suid.html as well as the make menuconfig help).  I compiled with option BUSYBOX_CONFIG_FEATURE_SUID_CONFIG set.  I even re-compiled after doing a make clean and after an svn update to version 27321 from svn://svn.openwrt.org/openwrt/branches/backfire.  I still get the following in my shell.

------------------------------------------------------------------------------
CONFIGURATION MENU
------------------------------------------------------------------------------
[1] Set IP Address
[2] Set IPv6 Address
[3] Set Password

[s]tatus
[R]eboot

[Q]uit

Command: 3

passwd: setresgid: Operation not permitted

My C code does a simple

system("passwd");

I'm at all not sure why I'm getting this error...if it's a bug in source or if I'm configuring something wrong in busybox.conf.  The docs say to make busybox.conf readable only by root via chmod 600 /etc/busybox.conf.  However, when I do that I get

Using fallback suid method
Using fallback suid method
passwd: must be suid to work properly

So, I set busybox.conf back to standard 644 permissions and get the same setresgid error.  I also tried (per the docs in make menuconfig) to chmod 4755 on /bin/busybox.  Wrt didn't like that at all.

root@wrt:/bin# chmod 4755 busybox 
chmod: busybox: No space left on device
root@RG-AP1000N:/bin# ls
Segmentation fault
root@RG-AP1000N:/bin# chmod -s busybox
Segmentation fault

This basically locks the board with these seg faults after every attempted command.  I can't do anything even after restarting.  I have to re-flash the image.

Relevant files/information

busybox.conf
------------
[SUID]
id      = ssx 0.0
halt    = ssx 0.0
reboot  = ssx 0.0
passwd  = ssx 0.0

busybox is owned and in root group
-----------------------------------------
-rw-r--r--    1 root     root           80 Jun 30 21:30 busybox.conf

/etc/passwd
---------------
root:$1$DMxkVWgn$EZIqoxRUQqa4RV9iQxhMW/:0:0:root:/root:/bin/ash
admin:$1$dfgYCqDu$7z10pMM2igc22XqgTaEKW0:1:100:admin:/:/usr/bin/myshell
ftp:*:55:55:ftp:/home/ftp:/bin/false
network:*:101:101:network:/var:/bin/false
nobody:*:65534:65534:nobody:/var:/bin/false
daemon:*:65534:65534:daemon:/var:/bin/false

/etc/group
------------
root:x:0:
admin:x:100:
nogroup:x:65534:

Anybody have any ideas?  Thanks in advance!  PS running image on a Compex WPJ543 board.

(Last edited by webasdf on 30 Jun 2011, 23:31)

I figured it out.  I REALLY DID run out of space.  Turns out I only had 4MB of flash and I was compiling too much into the image.  The image flashed, but that was about all I could do.  I took out some packages and libraries I don't really need (rrdtool being the biggest one w/ the graphics libraries and all), recompiled and eeked out enough space to do a:

chmod +s /bin/busybox

It actually required 200k of flash space to do this command.  I also kept the busybox.conf file the same, tested with the admin (non-root) user and viola, worked. 

(Last edited by webasdf on 7 Jul 2011, 15:05)