topic Re: normal user core dumping after calling setresuid in Operating System - HP-UX

normal user core dumping after calling setresuid

Aviansh — Wed, 25 Feb 2009 09:01:24 GMT

Hi,

Can anyone please tell me how to force child process to dump core.
I'm using setresuid inside the signal handler.

Regards
-Avinash

Re: normal user core dumping after calling setresuid

Laurent Menase — Wed, 25 Feb 2009 10:16:09 GMT

do you mean that you have a process which has the setuid bit- we called that pink process-, and you want it to coredump?

Once a process is pink, then it won't generate core even if the resuid is made to set it back to a normal user

there are some way to generate it in that case,
removing that security.- the way to do it depends of hpux revision-

Re: normal user core dumping after calling setresuid

Dennis Handly — Sun, 04 Sep 2011 05:15:32 GMT

This looks like a continuation of your other thread. It is better to continue your related questions in the same thread.
http://h30499.www3.hp.com/t5/Languages-and-Scripting/problem-with-setresuid-in-child-process-Pink-Process/td-p/4362801

Re: normal user core dumping after calling setresuid

Aviansh — Thu, 26 Feb 2009 04:43:59 GMT

Hi Laurent,

Please describe in little more details..

also how this is achieved on hp-ux different versions..

Regards
-Avinash

Re: normal user core dumping after calling setresuid

Laurent Menase — Thu, 26 Feb 2009 09:54:48 GMT

Hi Aviansh

on 11.31 look at man coreadm
on 11.23
echo dump_all/W 1| adb -o /stand/vmunix /dev/kmem
on 11.11
echo dump_all/W 1| adb /stand/vmunix /dev/kmem

limit this to your debug session because it opens security holes on your system.

Re: normal user core dumping after calling setresuid

Laurent Menase — Thu, 26 Feb 2009 09:56:17 GMT

to come back to normal behavior
- pink process don't generate core-
11.11
echo dump_all/W 0 | adb /stand/vmunix /dev/kmem

11.23
echo dump_all/W 0 | adb -o /stand/vmunix /dev/kmem

Re: normal user core dumping after calling setresuid

Aviansh — Thu, 26 Feb 2009 10:01:48 GMT

I'm getting the following error when I run this on 11iv2 machine..

# echo dump_all/W 1| adb -o /stand/vmunix /dev/kmem
dump_all: 0 =
adb: error: /dev/kmem: Bad file number.

Re: normal user core dumping after calling setresuid

Aviansh — Thu, 26 Feb 2009 10:07:25 GMT

sorry I should have executed
echo dump_all | adb -o /stand/vmunix /dev/kmem

Re: normal user core dumping after calling setresuid

Laurent Menase — Thu, 26 Feb 2009 10:15:51 GMT

I forgot -w

it is
echo dump_all/W 1 | adb -o -w /stand/vmunix /dev/kmem

and to revert back
echo dump_all/W 0|adb -o -w /stand/vmunix /dev/kmem

Re: normal user core dumping after calling setresuid

Aviansh — Thu, 26 Feb 2009 10:20:57 GMT

I'll inform about this..
currently my build machine is down..!!!!!

Thanks for your efforts

Re: normal user core dumping after calling setresuid

Laurent Menase — Thu, 26 Feb 2009 10:23:44 GMT

just a remark, this is to be done before the process core dump

Re: normal user core dumping after calling setresuid

Aviansh — Fri, 27 Feb 2009 08:23:00 GMT

Thanks a lot laurent, it works..

But this can only be used temporarily for the debugging purpose, as it breaches the unix security...

Re: normal user core dumping after calling setresuid

Laurent Menase — Fri, 27 Feb 2009 10:06:25 GMT

you can try to do it with a launcher which has the setuid bit

promoter.c
main()
{
setreuid(0,0);
execl("/mypath/commandtopromote","commandtopromore","param1",....,0);
}

I am not sure that the commandtopromote will be pink too.

or the other way if you need promotion just temporarily:
1 simple process with promotion to perform restricted ops.
1 process as normal user which makes the main operations
and the 2 processes talk using unix domain sockets, pipes, or other

- or simply launching it if it is really occasionnally. - like grandpt() does for instance.

Else if you are happy, don't forget points.

Re: normal user core dumping after calling setresuid

Aviansh — Tue, 03 Mar 2009 10:24:49 GMT

Hi Laurent,

Can you please tell me how hp-ux login/shell does the same thing.

Because the normal user sometimes are given root permission(like passwd file updation), yet they dump core..!!!

Regards
-Avinash

Re: normal user core dumping after calling setresuid

Aviansh — Tue, 03 Mar 2009 10:26:30 GMT

I mean to say..

Normal users can generate core from his login shell..
Then why not Pink Processes.?

Re: normal user core dumping after calling setresuid

Laurent Menase — Tue, 03 Mar 2009 11:43:43 GMT

Hi Avinash,
no, passwd, login generate a core dump only if they are started by root user.

so a way to do it:
main(c,v)
int c;
char**v;
{
if(getuid()!=0)
{
printf("need to recall");
setreuid(0,0);
execvp(v[0],v); /* restart the process as really root user */
}
printf ("%d\n",getuid());
kill(getpid(),10);
sleep(10);
}

it will generate a core, but all the process is executed as root.

Re: normal user core dumping after calling setresuid

Laurent Menase — Tue, 03 Mar 2009 12:08:30 GMT

or
main(c,v)
int c;
char**v;
{
if(getuid()!=10)
{
printf("need to recall");
setreuid(10,10);
execvp("./r",v);
}
printf ("%d\n",getuid());
kill(getpid(),10);
sleep(10);
}

cc k.c -o k
cp k r
chmod 6555 k
chmod 555 r

./k setuid to 10 10 then exec r which is the same program but without setuid bit set.
so not pink

Re: normal user core dumping after calling setresuid

Aviansh — Wed, 04 Mar 2009 06:57:12 GMT

my daemon is not having 6555 permission. It has 555 permissions.

when we connect to this server(daemon) using non-root id it forks a copy of itself to serve the request.

we are using setresuid in our code and inside the signal handler.

Re: normal user core dumping after calling setresuid

Aviansh — Thu, 05 Mar 2009 04:49:53 GMT

Hi Laurent,

I have some confusion over the concept of Pink process..

a process is called a pink process when it becomes a privileged user or if it executes setresuid ..??

Please clarify on this..

Regards
-Avinash

Re: normal user core dumping after calling setresuid

Dennis Handly — Thu, 05 Mar 2009 05:35:41 GMT

>I have some confusion over the concept of Pink process.

Don explained what it (pinko) meant in your other thread.
http://forums.itrc.hp.com/service/forums/questionanswer.do?threadId=1315932#tdIdName5

(This is why you shouldn't have created another related thread.)