normal user core dumping after calling setresuid

[Aviansh]

Hi,

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

Regards
-Avinash

[Laurent Menase]

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-

[Dennis Handly]

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

[Aviansh]

Hi Laurent,

Please describe in little more details..

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

Regards
-Avinash

[Laurent Menase]

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.

[Laurent Menase]

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

[Aviansh]

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.

[Aviansh]

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

[Laurent Menase]

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

[Aviansh]

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

Thanks for your efforts

[Laurent Menase]

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

[Aviansh]

Thanks a lot laurent, it works..

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

[Laurent Menase]

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.

[Aviansh]

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

[Aviansh]

I mean to say..

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

[Laurent Menase]

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.

[Laurent Menase]

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

[Aviansh]

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.

[Aviansh]

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

[Dennis Handly]

>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.)