Switching Security Contexts

I would like to impersonate a user. For example if I want to being
"nobody" I was thinking I could use getpwnam(3) to retrieve the
associated uid and gid with which I would call setuid and setgid
respectively. Is this a secure procedure? What other state in a process
is user specific? Locales?

Thanks,
Mike

Michael B Allen <mba2000@ioplex.com> wrote:
> I would like to impersonate a user. For example if I want to being
> "nobody" I was thinking I could use getpwnam(3) to retrieve the
> associated uid and gid with which I would call setuid and setgid
> respectively. Is this a secure procedure? What other state in a process
> is user specific?

Use following steps: getpwnam -> setgid -> setgroups -> setuid.

In setgroups() set zero item to GID of the user.