set_ugid.c

[詳解]

/*++
/* NAME
/*  set_ugid 3
/* SUMMARY
/*  set real, effective and saved user and group attributes
/* SYNOPSIS
/*  #include <set_ugid.h>
/*
/*  void    set_ugid(uid, gid)
/*  uid_t   uid;
/*  gid_t   gid;
/* DESCRIPTION
/*  set_ugid() sets the real, effective and saved user and group process
/*  attributes and updates the process group access list to be just the
/*  user's primary group. This operation is irreversible.
/* DIAGNOSTICS
/*  All system call errors are fatal.
/* SEE ALSO
/*  setuid(2), setgid(2), setgroups(2)
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <grp.h>
#include <errno.h>

/* Utility library. */

#include "msg.h"
#include "set_ugid.h"

/* set_ugid - set real, effective and saved user and group attributes */

void    set_ugid(uid_t uid, gid_t gid)
{
    int     saved_errno = errno;

    if (geteuid() != 0)
    if (seteuid(0) < 0)
        msg_fatal("seteuid(0): %m");
    if (setgid(gid) < 0)
    msg_fatal("setgid(%ld): %m", (long) gid);
    if (setgroups(1, &gid) < 0)
    msg_fatal("setgroups(1, &%ld): %m", (long) gid);
    if (setuid(uid) < 0)
    msg_fatal("setuid(%ld): %m", (long) uid);
    if (msg_verbose > 1)
    msg_info("setugid: uid %ld gid %ld", (long) uid, (long) gid);
    errno = saved_errno;
}