setuid Post: 19706

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Top Forums UNIX for Advanced & Expert Users setuid Post 19706 by sanjay92 on Monday 15th of April 2002 06:36:19 PM

04-15-2002

sanjay92

Guest

Neo,
Thanks for reply.
Can you please give me example how to do exec process with the UID, you want.

Please see my test case below :-

[IPLAY] $ ls -al a.ksh
-rwx------ 1 oracle dba 46 Apr 15 15:54 a.ksh

Where a.ksh is as follows :-

#!/usr/bin/ksh
# There are more lines of code here that should be executed
# as oracle user.
# but the line below (sqlplus) should be executed as the calling user i.e. real user.
sqlplus system/cub4@idev1

*************************************

This is C Wrapper script.
[IPLAY] $ cat a.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
/**********************************************
This is the wrapper script

***********************************************/

int main(int argc, char *argv[]) {
int i;
i=system("/local1/USERS/oracle/a.ksh");
if ( i == 0 )
return 0;
else
return 1;
}

I have compiled gcc a.c -o a

Now, I have changed permission of a as 4711

So when I will execute a as some other user e.g. sanjay,
the sqlplus session is started but I want to start the sqlplus session as the sanjay user which is the real user, oracle is the effective user in this case.

Thanks

Quote:

Originally posted by Neo
One suggestion is to fork() and perhaps exec() a process with the UID you want. Then have the new process make the system call with the UID you gave it.......

You can't change the UID of a running process..... but you can fork new processes and give UIDs to the new processes.

Last edited by sanjay92; 04-15-2002 at 08:22 PM..

sanjay92

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LEARN ABOUT LINUX

user-session-keyring

USER-SESSION-KEYRING(7) 				     Linux Programmer's Manual					   USER-SESSION-KEYRING(7)

NAME

       user-session-keyring - per-user default session keyring

DESCRIPTION

       The  user  session  keyring  is a keyring used to anchor keys on behalf of a user.  Each UID the kernel deals with has its own user session
       keyring that is shared by all processes with that UID.  The user session keyring has a name (description) of the form _uid_ses.<UID>  where
       <UID> is the user ID of the corresponding user.

       The  user  session  keyring  is	associated  with the record that the kernel maintains for the UID.  It comes into existence upon the first
       attempt to access either the user session keyring, the user-keyring(7), or the session-keyring(7).  The keyring remains pinned in existence
       so  long as there are processes running with that real UID or files opened by those processes remain open.  (The keyring can also be pinned
       indefinitely by linking it into another keyring.)

       The user session keyring is created on demand when a thread requests it or when a thread asks for its session-keyring(7) and  that  keyring
       doesn't	exist.	In the latter case, a user session keyring will be created and, if the session keyring wasn't to be created, the user ses-
       sion keyring will be set as the process's actual session keyring.

       The user session keyring is searched by request_key(2) if the actual session keyring does not exist and is ignored otherwise.

       A special serial number value, KEY_SPEC_USER_SESSION_KEYRING, is defined that can be used in lieu of the actual serial number of the  call-
       ing process's user session keyring.

       From the keyctl(1) utility, '@us' can be used instead of a numeric key ID in much the same way.

       User  session keyrings are independent of clone(2), fork(2), vfork(2), execve(2), and _exit(2) excepting that the keyring is destroyed when
       the UID record is destroyed when the last process pinning it exits.

       If a user session keyring does not exist when it is accessed, it will be created.

       Rather than relying on the user session keyring, it is strongly recommended--especially if the process is running as root--that a  session-
       keyring(7) be set explicitly, for example by pam_keyinit(8).

NOTES

       The user session keyring was added to support situations where a process doesn't have a session keyring, perhaps because it was created via
       a pathway that didn't involve PAM (e.g., perhaps it was a daemon started by inetd(8)).  In such a scenario, the user session  keyring  acts
       as a substitute for the session-keyring(7).

SEE ALSO

       keyctl(1), keyctl(3), keyrings(7), persistent-keyring(7), process-keyring(7), session-keyring(7), thread-keyring(7), user-keyring(7)

Linux								    2017-03-13						   USER-SESSION-KEYRING(7)

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