File: [local] / src / usr.bin / su / su.c (download)
Revision 1.50, Sun Dec 8 16:50:07 2002 UTC (21 years, 6 months ago) by millert
Branch: MAIN
Changes since 1.49: +3 -3 lines
GNU semantics say that if optstring begins with '-' then
each non-option shall be treated as arguments to option '\1'.
BSD getopt match '-' in optstring with a '-' on the command line.
This is used to support deprecated options like "su -" that would
otherwise prevent the use of getopt().
Resolving this simply requires that the leading '-' be moved somewhere
else (I moved it to the end of optstring) since position within
optstring is not meaningful.
|
/* $OpenBSD: su.c,v 1.50 2002/12/08 16:50:07 millert Exp $ */
/*
* Copyright (c) 1988 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
static const char copyright[] =
"@(#) Copyright (c) 1988 The Regents of the University of California.\n\
All rights reserved.\n";
#endif /* not lint */
#ifndef lint
#if 0
static const char sccsid[] = "from: @(#)su.c 5.26 (Berkeley) 7/6/91";
#else
static const char rcsid[] = "$OpenBSD: su.c,v 1.50 2002/12/08 16:50:07 millert Exp $";
#endif
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <err.h>
#include <errno.h>
#include <grp.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <utmp.h>
#include <stdarg.h>
#include <bsd_auth.h>
char *getloginname(void);
char *ontty(void);
int chshell(char *);
int verify_user(char *, struct passwd *, char *, login_cap_t *,
auth_session_t *);
void usage(void);
void auth_err(auth_session_t *, int, const char *, ...);
void auth_errx(auth_session_t *, int, const char *, ...);
int
main(int argc, char **argv)
{
int asme = 0, asthem = 0, ch, fastlogin = 0, emlogin = 0, flags, prio;
char *user, *shell = NULL, *avshell, *username, **np;
char *class = NULL, *style = NULL, *p;
enum { UNSET, YES, NO } iscsh = UNSET;
char avshellbuf[MAXPATHLEN];
extern char **environ;
auth_session_t *as;
struct passwd *pwd;
login_cap_t *lc;
uid_t ruid;
while ((ch = getopt(argc, argv, "a:c:fKLlm-")) != -1)
switch (ch) {
case 'a':
if (style)
usage();
style = optarg;
break;
case 'c':
if (class)
usage();
class = optarg;
break;
case 'f':
fastlogin = 1;
break;
case 'K':
if (style)
usage();
style = "passwd";
break;
case 'L':
emlogin = 1;
break;
case 'l':
case '-':
asme = 0;
asthem = 1;
break;
case 'm':
asme = 1;
asthem = 0;
break;
default:
usage();
}
argv += optind;
errno = 0;
prio = getpriority(PRIO_PROCESS, 0);
if (errno)
prio = 0;
(void)setpriority(PRIO_PROCESS, 0, -2);
openlog("su", LOG_CONS, 0);
if ((as = auth_open()) == NULL) {
syslog(LOG_ERR, "auth_open: %m");
err(1, "unable to initialize BSD authentication");
}
auth_setoption(as, "login", "yes");
/* get current login name and shell */
ruid = getuid();
username = getlogin();
if (ruid && class)
auth_errx(as, 1, "only the superuser may specify a login class");
if (username != NULL)
auth_setoption(as, "invokinguser", username);
if (username == NULL || (pwd = getpwnam(username)) == NULL ||
pwd->pw_uid != ruid)
pwd = getpwuid(ruid);
if (pwd == NULL)
auth_errx(as, 1, "who are you?");
if ((username = strdup(pwd->pw_name)) == NULL)
auth_errx(as, 1, "can't allocate memory");
if (asme) {
if (pwd->pw_shell && *pwd->pw_shell) {
if ((shell = strdup(pwd->pw_shell)) == NULL)
auth_errx(as, 1, "can't allocate memory");
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
}
for (;;) {
/* get target user, default to root unless in -L mode */
if (*argv) {
user = *argv;
} else if (emlogin) {
if ((user = getloginname()) == NULL) {
auth_close(as);
exit(1);
}
} else {
user = "root";
}
/* style may be specified as part of the username */
if ((p = strchr(user, ':')) != NULL) {
*p++ = '\0';
style = p; /* XXX overrides -a flag */
}
/*
* Clean and setup our current authentication session.
* Note that options *are* not cleared.
*/
auth_clean(as);
if (auth_setitem(as, AUTHV_INTERACTIVE, "True") != 0 ||
auth_setitem(as, AUTHV_NAME, user) != 0)
auth_errx(as, 1, "can't allocate memory");
if ((user = auth_getitem(as, AUTHV_NAME)) == NULL)
auth_errx(as, 1, "internal error");
if (auth_setpwd(as, NULL) || (pwd = auth_getpwd(as)) == NULL) {
if (emlogin)
pwd = NULL;
else
auth_errx(as, 1, "unknown login %s", user);
}
/* If the user specified a login class, use it */
if (!class && pwd && pwd->pw_class && pwd->pw_class[0] != '\0')
class = pwd->pw_class;
if ((lc = login_getclass(class)) == NULL)
auth_errx(as, 1, "no such login class: %s",
class ? class : LOGIN_DEFCLASS);
if ((ruid == 0 && !emlogin) ||
verify_user(username, pwd, style, lc, as) == 0)
break;
syslog(LOG_AUTH|LOG_WARNING, "BAD SU %s to %s%s",
username, user, ontty());
if (!emlogin) {
fprintf(stderr, "Sorry\n");
auth_close(as);
exit(1);
}
fprintf(stderr, "Login incorrect\n");
}
if (asme) {
/* if asme and non-standard target shell, must be root */
if (!chshell(pwd->pw_shell) && ruid)
auth_errx(as, 1, "permission denied (shell).");
} else if (pwd->pw_shell && *pwd->pw_shell) {
if ((shell = strdup(pwd->pw_shell)) == NULL)
auth_errx(as, 1, "can't allocate memory");
iscsh = UNSET;
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
if ((p = strrchr(shell, '/')))
avshell = p+1;
else
avshell = shell;
/* if we're forking a csh, we want to slightly muck the args */
if (iscsh == UNSET)
iscsh = strcmp(avshell, "csh") ? NO : YES;
if (!asme) {
if (asthem) {
p = getenv("TERM");
if ((environ = calloc(1, sizeof (char *))) == NULL)
auth_errx(as, 1, "calloc");
if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
auth_err(as, 1, "unable to set user context");
if (p && setenv("TERM", p, 1) == -1)
auth_err(as, 1, "unable to set environment");
seteuid(pwd->pw_uid);
setegid(pwd->pw_gid);
if (chdir(pwd->pw_dir) < 0)
auth_err(as, 1, "%s", pwd->pw_dir);
seteuid(0);
setegid(0); /* XXX use a saved gid instead? */
} else if (pwd->pw_uid == 0) {
if (setusercontext(lc,
pwd, pwd->pw_uid, LOGIN_SETPATH|LOGIN_SETUMASK))
auth_err(as, 1, "unable to set user context");
}
if (asthem || pwd->pw_uid) {
if (setenv("LOGNAME", pwd->pw_name, 1) == -1 ||
setenv("USER", pwd->pw_name, 1) == -1)
auth_err(as, 1, "unable to set environment");
}
if (setenv("HOME", pwd->pw_dir, 1) == -1 ||
setenv("SHELL", shell, 1) == -1)
auth_err(as, 1, "unable to set environment");
}
np = *argv ? argv : argv - 1;
if (iscsh == YES) {
if (fastlogin)
*np-- = "-f";
if (asme)
*np-- = "-m";
}
if (asthem) {
avshellbuf[0] = '-';
strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
} else if (iscsh == YES) {
/* csh strips the first character... */
avshellbuf[0] = '_';
strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
}
*np = avshell;
if (ruid != 0)
syslog(LOG_NOTICE|LOG_AUTH, "%s to %s%s",
username, user, ontty());
(void)setpriority(PRIO_PROCESS, 0, prio);
if (emlogin)
flags = LOGIN_SETALL & ~LOGIN_SETPATH;
else
flags = (asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER;
if (setusercontext(lc, pwd, pwd->pw_uid, flags) != 0)
auth_err(as, 1, "unable to set user context");
if (pwd->pw_uid && auth_approval(as, lc, pwd->pw_name, "su") <= 0)
auth_err(as, 1, "approval failure");
auth_close(as);
execv(shell, np);
err(1, "%s", shell);
}
int
verify_user(char *from, struct passwd *pwd, char *style,
login_cap_t *lc, auth_session_t *as)
{
struct group *gr;
char **g, *cp;
int authok;
/*
* If we are trying to become root and the default style
* is being used, don't bother to look it up (we might be
* be su'ing up to fix /etc/login.conf)
*/
if ((pwd == NULL || pwd->pw_uid != 0 || style == NULL ||
strcmp(style, LOGIN_DEFSTYLE) != 0) &&
(style = login_getstyle(lc, style, "auth-su")) == NULL)
auth_errx(as, 1, "invalid authentication type");
/*
* Let the authentication program know whether they are
* in group wheel or not (if trying to become super user)
*/
if (pwd != NULL && pwd->pw_uid == 0 && (gr = getgrgid(0)) != NULL &&
gr->gr_mem != NULL && *(gr->gr_mem) != NULL) {
for (g = gr->gr_mem; *g; ++g) {
if (strcmp(from, *g) == 0) {
auth_setoption(as, "wheel", "yes");
break;
}
}
if (!*g)
auth_setoption(as, "wheel", "no");
}
auth_verify(as, style, NULL, lc->lc_class, (char *)NULL);
authok = auth_getstate(as);
if ((authok & AUTH_ALLOW) == 0) {
if ((cp = auth_getvalue(as, "errormsg")) != NULL)
fprintf(stderr, "%s\n", cp);
return(1);
}
return(0);
}
int
chshell(char *sh)
{
char *cp;
while ((cp = getusershell()) != NULL)
if (strcmp(cp, sh) == 0)
return (1);
return (0);
}
char *
ontty(void)
{
static char buf[MAXPATHLEN + 4];
char *p;
buf[0] = 0;
if ((p = ttyname(STDERR_FILENO)))
snprintf(buf, sizeof(buf), " on %s", p);
return (buf);
}
/*
* Allow for a '.' and 16 characters for any instance as well as
* space for a ':' and 16 charcters defining the authentication type.
*/
#define NBUFSIZ (UT_NAMESIZE + 1 + 16 + 1 + 16)
char *
getloginname(void)
{
static char nbuf[NBUFSIZ], *p;
int ch;
for (;;) {
(void)printf("login: ");
for (p = nbuf; (ch = getchar()) != '\n'; ) {
if (ch == EOF)
return (NULL);
if (p < nbuf + (NBUFSIZ - 1))
*p++ = ch;
}
if (p > nbuf) {
if (nbuf[0] == '-') {
(void)fprintf(stderr,
"login names may not start with '-'.\n");
} else {
*p = '\0';
break;
}
}
}
return (nbuf);
}
void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-fKLlm] [-a auth-type] [-c login-class] "
"[login [shell arguments]]\n", __progname);
exit(1);
}
void
auth_err(auth_session_t *as, int eval, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vwarn(fmt, ap);
va_end(ap);
auth_close(as);
exit(eval);
}
void
auth_errx(auth_session_t *as, int eval, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vwarnx(fmt, ap);
va_end(ap);
auth_close(as);
exit(eval);
}