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From: serini@ghost.dsi.unimi.it (Piero Serini)
Subject: id(1) bugs and new source
Organization: Computer Science Dep. - Milan University
Date: Fri, 19 Feb 1993 13:54:50 GMT
Message-ID: <1993Feb19.135450.3052@ghost.dsi.unimi.it>
Summary: new id.c
Lines: 374
Hi.
I found that id(1) doesn't handle properly the "gid"
and "groups" entries:
1) "normal" id:
$ id
uid=100(piero) gid=20(staff) groups=5(opr), 20(staff)
redundant ^^^^^^^^
2) id [user] doesn't work: it uses the uid to seek for group name:
$ id giulia
uid=500(giulia) gid=100
In /etc/group gid 100 = users, but id looks for 500 and doesn't
find it. Another test:
$ id piero (myself)
uid=100(piero) gid=20(users) groups=5(opr)
As you can see in the example at 1), gid 20 = staff,
but id looks for 100 which is = users
3) after a setuid() AND a setgid(), "groups" is a mix between the original
groups and the new ones. Here follows an id from a "super-shell":
uid=0(root) gid=0(root) groups=0(root), 5(opr), 20(staff)
uid and gid are right;
groups: 0(root) is redundant (root has gid 0 = root)
5(opr) is wrong (piero is in group 5, not root)
20(staff) is right, but we can't tell: both piero
and root are in group 20.
The new id.c source follows.
Bye all
--
------------------------------------------ Piero Serini ------------
Via Giambologna, 1 E-mail: piero@strider.st.dsi.unimi.it
20136 - Milano - ITALY or: serini@ghost.dsi.unimi.it
-------- PUBLIC KEY AVAILABLE VIA finger(1) or mail request --------
/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1991 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char sccsid[] = "@(#)id.c 5.1 (Berkeley) 6/29/91";
#endif /* not lint */
#include <sys/param.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
typedef struct passwd PW;
typedef struct group GR;
void err __P((const char *, ...));
int gcmp __P((const void *, const void *));
void sgroup __P((PW *));
void ugroup __P((PW *));
void usage __P((void));
void user __P((PW *));
PW *who __P((char *));
int Gflag, gflag, nflag, rflag, uflag;
main(argc, argv)
int argc;
char *argv[];
{
GR *gr;
PW *pw;
int ch, id;
while ((ch = getopt(argc, argv, "Ggnru")) != EOF)
switch(ch) {
case 'G':
Gflag = 1;
break;
case 'g':
gflag = 1;
break;
case 'n':
nflag = 1;
break;
case 'r':
rflag = 1;
break;
case 'u':
uflag = 1;
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
pw = *argv ? who(*argv) : NULL;
if (Gflag + gflag + uflag > 1)
usage();
if (Gflag) {
if (nflag)
sgroup(pw);
else
ugroup(pw);
exit(0);
}
if (gflag) {
id = pw ? pw->pw_gid : rflag ? getgid() : getegid();
if (nflag && (gr = getgrgid(id))) {
(void)printf("%s\n", gr->gr_name);
exit(0);
}
(void)printf("%u\n", id);
exit(0);
}
if (uflag) {
id = pw ? pw->pw_uid : rflag ? getuid() : geteuid();
if (nflag && (pw = getpwuid(id))) {
(void)printf("%s\n", pw->pw_name);
exit(0);
}
(void)printf("%u\n", id);
exit(0);
}
if (!pw)
pw = getpwuid(getuid());
user(pw);
exit(0);
}
void
sgroup(pw)
PW *pw;
{
register int id, lastid;
char *fmt;
if (pw) {
register GR *gr;
register char *name, **p;
name = pw->pw_name;
for (fmt = "%s", lastid = -1; gr = getgrent(); lastid = id) {
for (p = gr->gr_mem; p && *p; p++)
if (!strcmp(*p, name)) {
(void)printf(fmt, gr->gr_name);
fmt = " %s";
break;
}
}
} else {
GR *gr;
register int ngroups;
int groups[NGROUPS + 1];
groups[0] = getgid();
ngroups = getgroups(NGROUPS, groups + 1) + 1;
heapsort(groups, ngroups, sizeof(groups[0]), gcmp);
for (fmt = "%s", lastid = -1; --ngroups >= 0;) {
if (lastid == (id = groups[ngroups]))
continue;
if (gr = getgrgid(id))
(void)printf(fmt, gr->gr_name);
else
(void)printf(*fmt == ' ' ? " %u" : "%u", id);
fmt = " %s";
lastid = id;
}
}
(void)printf("\n");
}
void
ugroup(pw)
PW *pw;
{
register int id, lastid;
register char *fmt;
if (pw) {
register GR *gr;
register char *name, **p;
name = pw->pw_name;
for (fmt = "%u", lastid = -1; gr = getgrent(); lastid = id) {
for (p = gr->gr_mem; p && *p; p++)
if (!strcmp(*p, name)) {
(void)printf(fmt, gr->gr_gid);
fmt = " %u";
break;
}
}
} else {
register int ngroups;
int groups[NGROUPS + 1];
groups[0] = getgid();
ngroups = getgroups(NGROUPS, groups + 1) + 1;
heapsort(groups, ngroups, sizeof(groups[0]), gcmp);
for (fmt = "%u", lastid = -1; --ngroups >= 0;) {
if (lastid == (id = groups[ngroups]))
continue;
(void)printf(fmt, id);
fmt = " %u";
lastid = id;
}
}
(void)printf("\n");
}
void
user(pw)
register PW *pw;
{
register GR *gr;
register int id, lastid;
int eid, gid, egid;
register char *fmt, **p;
id = pw->pw_uid;
gid = pw->pw_gid;
(void)printf("uid=%u(%s)", id, pw->pw_name);
if (id == getuid())
if ((eid = geteuid()) != id) {
(void)printf(" euid=%u", eid);
if (pw = getpwuid(eid))
(void)printf("(%s)", pw->pw_name);
}
/* endif id == getuid() */
(void)printf(" gid=%u", gid);
if (gr = getgrgid(gid))
(void)printf("(%s)", gr->gr_name);
if (id == getuid())
if ((egid = getegid()) != gid) {
(void)printf(" egid=%u", egid);
if (gr = getgrgid(egid))
(void)printf("(%s)", gr->gr_name);
}
/* endif id == getuid() */
/* now pw points to Euid, so we must reset it */
pw = getpwuid(id);
for (fmt = " groups=%u(%s)", lastid = -1; gr = getgrent();
lastid = id) {
if (pw->pw_gid == gr->gr_gid)
continue;
for (p = gr->gr_mem; p && *p; p++)
if (!strcmp(*p, pw->pw_name)) {
(void)printf(fmt, gr->gr_gid, gr->gr_name);
fmt = ", %u(%s)";
break;
}
}
(void)printf("\n");
}
PW *
who(u)
char *u;
{
PW *pw;
long id;
char *ep;
/*
* Translate user argument into a pw pointer. First, try to
* get it as specified. If that fails, try it as a number.
*/
if (pw = getpwnam(u))
return(pw);
id = strtol(u, &ep, 10);
if (*u && !*ep && (pw = getpwuid(id)))
return(pw);
err("%s: No such user", u);
/* NOTREACHED */
}
gcmp(a, b)
const void *a, *b;
{
return(*(int *)b - *(int *)a);
}
#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
void
#if __STDC__
err(const char *fmt, ...)
#else
err(fmt, va_alist)
char *fmt;
va_dcl
#endif
{
va_list ap;
#if __STDC__
va_start(ap, fmt);
#else
va_start(ap);
#endif
(void)fprintf(stderr, "id: ");
(void)vfprintf(stderr, fmt, ap);
va_end(ap);
(void)fprintf(stderr, "\n");
exit(1);
/* NOTREACHED */
}
void
usage()
{
(void)fprintf(stderr, "usage: id [user]\n");
(void)fprintf(stderr, " id -G [-n] [user]\n");
(void)fprintf(stderr, " id -g [-nr] [user]\n");
(void)fprintf(stderr, " id -u [-nr] [user]\n");
exit(1);
}