Running DOSEMU as user

dosemu

log_level= 1
root c_all unrestricted
all c_all unrestricted

I set the 'suid' bit to 'dosemu.bin':

  # ll /usr/bin/dosemu.bin
  -rwsr-xr-x 1 root root 1816368 Oct 24 10:19 /usr/bin/dosemu.bin

Did you start dosemu with the -s option? The suid bit alone doesn't give enough rights any longer.

The question is do they need such rights? You should be able to run dosmeu as a user without getting the ability to go direct to hardware (which -s allows) unless that is a real requirement for users.

Quoted 2 lines

Did you start dosemu with the -s option? The suid bit alone doesn't give enough rights any longer.

The question is do they need such rights? You should be able to run dosmeu as a user without getting the ability to go direct to hardware (which -s allows) unless that is a real requirement for users.

For most things (serial ports and printing) you don't need this and don't want to give it out.

We do in our application as we need direct hardware access, but that is not given to all+sundry who can log in.

Every DOSEMU session has to connect to a Novell (IPX based) server. I used 'direct networking' on the old version and it worked well, so
I'd like to keep using it.

And as far as I know IPX requires root privileges.

Every DOSEMU session has to connect to a Novell (IPX based) server. I used 'direct networking' on the old version and it worked well, so I'd like to keep using it.

And as far as I know IPX requires root privileges.

When users login (via telnet over a SSH tunnel) DOS is automatically started for them, they're automatically logged into Novell server and their application start automatically.

Hi,

I administer an old system (dated back to 2002) running DOSEMU (1.0.0). Multiple users connect to the machine with SSH / Telnet (over modem / ISDN dial-in) and run DOS / Novell IPX based applications. The system has worked so well that despite initial intentions to replace the system with something more up-to-date, they're still using it and the number of users increased. So much, that the old server is not coping anymore.

So now it's finally time to get new hardware and I intended to also use a more up-to-date distribution and DOSEMU. I decided to use OpenSuSE 11.2, as I grown most comfortable with OpenSuSE. It comes with DOSEMU 1.4.0.1.

I have the system up and running on a test machine (which is a humble desktop machine, but still more powerfull then the old server). I also managed to get DOSEMU running with IPX (using 'direct' networking) and those old Novell applications run too - but only if I run DOSEMU as 'root' (either directly or via 'sudo'). Now that is a bit of a problem, because sometimes, people forget to logout or their connection is interrupted - on the old system a login script would check whether DOSEMU is already running for the user and it would terminate the process. Of course, if I run all DOSEMU's as root, this is no longer possible, so I'm trying to find a way to run DOSEMU as users, but with all features.

I set the 'suid' bit to 'dosemu.bin':

  # ll /usr/bin/dosemu.bin
  -rwsr-xr-x 1 root root 1816368 Oct 24 10:19 /usr/bin/dosemu.bin

If I try to run DOSEMU as a user, I get this:

Quoted 1 line

dosemu

LOWRAM mmap: Invalid argument
Segmentation fault

Actuaclly, this output is the same whether dosemu.bin has the suid bit or not.

My 'dosemu.users':

Quoted 4 lines

log_level= 1
root c_all unrestricted
all c_all unrestricted

I found several references to the 'LOWRAM mmap' error and changed my '/proc/sys/vm/mmap_min_addr' to '0' - but it's still the same.

Running dosemu with 'strace', I get this (the last part of the output):

killed by SIGSEGV +++

Quoted 33 lines

mprotect(0xb6d40000, 7405568, PROT_READ|PROT_WRITE) = 0 mprotect(0xb6d40000, 1114112, PROT_READ|PROT_WRITE) = 0 mmap2(NULL, 1114112, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_FIXED, 5, 0) = -1 EACCES (Permission denied) mmap2(NULL, 1114112, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 5, 0) = -1 EACCES (Permission denied)
mprotect(0xffffffff, 1114112, PROT_READ|PROT_WRITE|PROT_EXEC) = -1 EINVAL (Invalid argument)

munmap(0, 655360)                       = 0
dup(2)                                  = 6
fcntl64(6, F_GETFL)                     = 0x8002 (flags

O_RDWR|O_LARGEFILE)
fstat64(6, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 1), ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xb753e000
_llseek(6, 0, 0xbf913b00, SEEK_CUR) = -1 ESPIPE (Illegal seek)
---- removed some probably harmles 'locale' messages' ---- write(6, "LOWRAM mmap: Invalid argument\n", 30LOWRAM mmap: Invalid argument
) = 30
close(6) = 0
munmap(0xb753e000, 4096) = 0
stat64("/home/danci/.dosemu/disclaimer", {st_mode=S_IFREG|0644, st_size=402, ...}) = 0
munmap(0x100000, 65536) = 0
mmap2(0x100000, 65536, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_FIXED, 5, 0) = 0x100000
mmap2(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6c40000
write(4, "CONF: reserving 1088Kb at 0x1000"..., 71) = 71

killed by SIGSEGV +++ renamed from SIGSEGV (Segmentation fault) @ 0 (0) --- +0 -0

So... What am I doing wrong? What do I need to do to be able to run DOSEMU as non-root user?

Thanks, Danilo

PS: I sure hope this list is still 'alive'.

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