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NetBSD/usr.bin/su/su.c

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/* $NetBSD: su.c,v 1.64 2005/01/10 03:11:50 christos 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. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT(
"@(#) Copyright (c) 1988 The Regents of the University of California.\n\
All rights reserved.\n");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)su.c 8.3 (Berkeley) 4/2/94";*/
#else
__RCSID("$NetBSD: su.c,v 1.64 2005/01/10 03:11:50 christos 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 <paths.h>
#include <pwd.h>
#include <stdio.h>
#ifdef SKEY
#include <skey.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <tzfile.h>
#include <unistd.h>
#ifdef LOGIN_CAP
#include <login_cap.h>
#endif
#ifdef KERBEROS
#include <des.h>
#include <krb.h>
#include <netdb.h>
static int kerberos(char *, char *, int);
static int koktologin(char *, char *, char *);
#endif
#ifdef KERBEROS5
#include <krb5.h>
static int kerberos5(char *, char *, int);
#endif
#if defined(KERBEROS) || defined(KERBEROS5)
#define ARGSTRX "-Kdflm"
int use_kerberos = 1;
#else
#define ARGSTRX "-dflm"
#endif
#ifndef SU_GROUP
#define SU_GROUP "wheel"
#endif
#ifdef LOGIN_CAP
#define ARGSTR ARGSTRX "c:"
#else
#define ARGSTR ARGSTRX
#endif
static int chshell(const char *);
static char *ontty(void);
static int check_ingroup(int, const char *, const char *, int);
int main(int, char **);
int
main(int argc, char **argv)
{
extern char **environ;
struct passwd *pwd;
char *p;
#ifdef BSD4_4
struct timeval tp;
#endif
uid_t ruid;
int asme, ch, asthem, fastlogin, prio, gohome;
enum { UNSET, YES, NO } iscsh = UNSET;
char *user, *shell, *avshell, *username, **np;
char *userpass, *class;
char shellbuf[MAXPATHLEN], avshellbuf[MAXPATHLEN];
time_t pw_warntime = _PASSWORD_WARNDAYS * SECSPERDAY;
#ifdef LOGIN_CAP
login_cap_t *lc;
#endif
asme = asthem = fastlogin = 0;
gohome = 1;
shell = class = NULL;
while ((ch = getopt(argc, argv, ARGSTR)) != -1)
switch((char)ch) {
#if defined(KERBEROS) || defined(KERBEROS5)
case 'K':
use_kerberos = 0;
break;
#endif
#ifdef LOGIN_CAP
case 'c':
class = optarg;
break;
#endif
case 'd':
asme = 0;
asthem = 1;
gohome = 0;
break;
case 'f':
fastlogin = 1;
break;
case '-':
case 'l':
asme = 0;
asthem = 1;
break;
case 'm':
asme = 1;
asthem = 0;
break;
case '?':
default:
(void)fprintf(stderr,
"usage: %s [%s] [login [shell arguments]]\n",
getprogname(), ARGSTR);
exit(1);
}
argv += optind;
/* Lower the priority so su runs faster */
errno = 0;
prio = getpriority(PRIO_PROCESS, 0);
if (errno)
prio = 0;
if (prio > -2)
(void)setpriority(PRIO_PROCESS, 0, -2);
openlog("su", 0, LOG_AUTH);
/* get current login name and shell */
ruid = getuid();
username = getlogin();
if (username == NULL || (pwd = getpwnam(username)) == NULL ||
pwd->pw_uid != ruid)
pwd = getpwuid(ruid);
if (pwd == NULL)
errx(1, "who are you?");
username = strdup(pwd->pw_name);
userpass = strdup(pwd->pw_passwd);
if (username == NULL || userpass == NULL)
err(1, "strdup");
if (asme) {
if (pwd->pw_shell && *pwd->pw_shell) {
strlcpy(shellbuf, pwd->pw_shell, sizeof(shellbuf));
shell = shellbuf;
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
}
/* get target login information, default to root */
user = *argv ? *argv : "root";
np = *argv ? argv : argv-1;
if ((pwd = getpwnam(user)) == NULL)
errx(1, "unknown login %s", user);
#ifdef LOGIN_CAP
/* force the usage of specified class */
if (class) {
if (ruid)
errx(1, "Only root may use -c");
pwd->pw_class = class;
}
if ((lc = login_getclass(pwd->pw_class)) == NULL)
errx(1, "Unknown class %s\n", pwd->pw_class);
pw_warntime = login_getcaptime(lc, "password-warn",
_PASSWORD_WARNDAYS * SECSPERDAY,
_PASSWORD_WARNDAYS * SECSPERDAY);
#endif
if (ruid
#ifdef KERBEROS5
&& (!use_kerberos || kerberos5(username, user, pwd->pw_uid))
#endif
#ifdef KERBEROS
&& (!use_kerberos || kerberos(username, user, pwd->pw_uid))
#endif
) {
char *pass = pwd->pw_passwd;
int ok = pwd->pw_uid != 0;
#ifdef SU_ROOTAUTH
/*
* Allow those in group rootauth to su to root, by supplying
* their own password.
*/
if (!ok) {
if ((ok = check_ingroup(-1, SU_ROOTAUTH, username, 0))) {
pass = userpass;
user = username;
}
}
#endif
/*
* Only allow those in group SU_GROUP to su to root,
* but only if that group has any members.
* If SU_GROUP has no members, allow anyone to su root
*/
if (!ok) {
ok = check_ingroup(-1, SU_GROUP, username, 1);
}
if (!ok)
errx(1,
"you are not listed in the correct secondary group (%s) to su %s.",
SU_GROUP, user);
/* if target requires a password, verify it */
if (*pass) {
p = getpass("Password:");
#ifdef SKEY
if (strcasecmp(p, "s/key") == 0) {
if (skey_haskey(user))
errx(1, "Sorry, you have no s/key.");
else {
if (skey_authenticate(user)) {
goto badlogin;
}
}
} else
#endif
if (strcmp(pass, crypt(p, pass))) {
#ifdef SKEY
badlogin:
#endif
fprintf(stderr, "Sorry\n");
syslog(LOG_WARNING,
"BAD SU %s to %s%s", username,
pwd->pw_name, ontty());
exit(1);
}
}
}
if (asme) {
/* if asme and non-standard target shell, must be root */
if (!chshell(pwd->pw_shell) && ruid)
errx(1,"permission denied (shell).");
} else if (pwd->pw_shell && *pwd->pw_shell) {
shell = pwd->pw_shell;
iscsh = UNSET;
} else {
shell = _PATH_BSHELL;
iscsh = NO;
}
if ((p = strrchr(shell, '/')) != NULL)
avshell = p+1;
else
avshell = shell;
/* if we're forking a csh, we want to slightly muck the args */
if (iscsh == UNSET)
iscsh = strstr(avshell, "csh") ? YES : NO;
/* set permissions */
#ifdef LOGIN_CAP
if (setusercontext(lc, pwd, pwd->pw_uid,
(asthem ? (LOGIN_SETPRIORITY | LOGIN_SETUMASK) : 0) |
LOGIN_SETRESOURCES | LOGIN_SETGROUP | LOGIN_SETUSER))
err(1, "setting user context");
#else
if (setgid(pwd->pw_gid) < 0)
err(1, "setgid");
if (initgroups(user, pwd->pw_gid))
errx(1, "initgroups failed");
if (setuid(pwd->pw_uid) < 0)
err(1, "setuid");
#endif
if (!asme) {
if (asthem) {
p = getenv("TERM");
/* Create an empty environment */
if ((environ = malloc(sizeof(char *))) == NULL)
err(1, NULL);
environ[0] = NULL;
#ifdef LOGIN_CAP
if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETPATH))
err(1, "setting user context");
#else
(void)setenv("PATH", _PATH_DEFPATH, 1);
#endif
if (p)
(void)setenv("TERM", p, 1);
if (gohome && chdir(pwd->pw_dir) < 0)
errx(1, "no directory");
}
if (asthem || pwd->pw_uid)
(void)setenv("USER", pwd->pw_name, 1);
(void)setenv("HOME", pwd->pw_dir, 1);
(void)setenv("SHELL", shell, 1);
}
(void)setenv("SU_FROM", username, 1);
if (iscsh == YES) {
if (fastlogin)
*np-- = "-f";
if (asme)
*np-- = "-m";
} else {
if (fastlogin)
unsetenv("ENV");
}
if (asthem) {
avshellbuf[0] = '-';
(void)strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
} else if (iscsh == YES) {
/* csh strips the first character... */
avshellbuf[0] = '_';
(void)strlcpy(avshellbuf+1, avshell, sizeof(avshellbuf) - 1);
avshell = avshellbuf;
}
*np = avshell;
#ifdef BSD4_4
if (pwd->pw_change || pwd->pw_expire)
(void)gettimeofday(&tp, (struct timezone *)NULL);
if (pwd->pw_change) {
if (tp.tv_sec >= pwd->pw_change) {
(void)printf("%s -- %s's password has expired.\n",
(ruid ? "Sorry" : "Note"), user);
if (ruid != 0)
exit(1);
} else if (pwd->pw_change - tp.tv_sec < pw_warntime)
(void)printf("Warning: %s's password expires on %s",
user, ctime(&pwd->pw_change));
}
if (pwd->pw_expire) {
if (tp.tv_sec >= pwd->pw_expire) {
(void)printf("%s -- %s's account has expired.\n",
(ruid ? "Sorry" : "Note"), user);
if (ruid != 0)
exit(1);
} else if (pwd->pw_expire - tp.tv_sec <
_PASSWORD_WARNDAYS * SECSPERDAY)
(void)printf("Warning: %s's account expires on %s",
user, ctime(&pwd->pw_expire));
}
#endif
if (ruid != 0)
syslog(LOG_NOTICE, "%s to %s%s",
username, pwd->pw_name, ontty());
/* Raise our priority back to what we had before */
(void)setpriority(PRIO_PROCESS, 0, prio);
execv(shell, np);
err(1, "%s", shell);
/* NOTREACHED */
}
static int
chshell(const char *sh)
{
const char *cp;
setusershell();
while ((cp = getusershell()) != NULL)
if (!strcmp(cp, sh))
return 1;
return 0;
}
static char *
ontty(void)
{
char *p;
static char buf[MAXPATHLEN + 4];
buf[0] = 0;
if ((p = ttyname(STDERR_FILENO)) != NULL)
(void)snprintf(buf, sizeof buf, " on %s", p);
return buf;
}
#ifdef KERBEROS5
static int
kerberos5(char *username, char *user, int uid)
{
krb5_error_code ret;
krb5_context context;
krb5_principal princ = NULL;
krb5_ccache ccache, ccache2;
char *cc_name;
const char *filename;
ret = krb5_init_context(&context);
if (ret)
return (1);
if (strcmp (user, "root") == 0)
ret = krb5_make_principal(context, &princ,
NULL, username, "root", NULL);
else
ret = krb5_make_principal(context, &princ,
NULL, user, NULL);
if (ret)
goto fail;
if (!krb5_kuserok(context, princ, user) && !uid) {
warnx ("kerberos5: not in %s's ACL.", user);
goto fail;
}
ret = krb5_cc_gen_new(context, &krb5_mcc_ops, &ccache);
if (ret)
goto fail;
ret = krb5_verify_user_lrealm(context, princ, ccache, NULL, TRUE,
NULL);
if (ret) {
krb5_cc_destroy(context, ccache);
switch (ret) {
case KRB5_LIBOS_PWDINTR :
break;
case KRB5KRB_AP_ERR_BAD_INTEGRITY:
case KRB5KRB_AP_ERR_MODIFIED:
krb5_warnx(context, "Password incorrect");
break;
default :
krb5_warn(context, ret, "krb5_verify_user");
break;
}
goto fail;
}
ret = krb5_cc_gen_new(context, &krb5_fcc_ops, &ccache2);
if (ret) {
krb5_cc_destroy(context, ccache);
goto fail;
}
ret = krb5_cc_copy_cache(context, ccache, ccache2);
if (ret) {
krb5_cc_destroy(context, ccache);
krb5_cc_destroy(context, ccache2);
goto fail;
}
filename = krb5_cc_get_name(context, ccache2);
asprintf(&cc_name, "%s:%s", krb5_cc_get_type(context, ccache2),
filename);
if (chown (filename, uid, -1) < 0) {
warn("chown %s", filename);
free(cc_name);
krb5_cc_destroy(context, ccache);
krb5_cc_destroy(context, ccache2);
goto fail;
}
setenv("KRB5CCNAME", cc_name, 1);
free(cc_name);
krb5_cc_close(context, ccache2);
krb5_cc_destroy(context, ccache);
return (0);
fail:
if (princ != NULL)
krb5_free_principal (context, princ);
krb5_free_context (context);
return (1);
}
#endif
#ifdef KERBEROS
static int
kerberos(char *username, char *user, int uid)
{
KTEXT_ST ticket;
AUTH_DAT authdata;
struct hostent *hp;
int kerno;
u_long faddr;
char lrealm[REALM_SZ], krbtkfile[MAXPATHLEN];
char hostname[MAXHOSTNAMELEN + 1], savehost[MAXHOSTNAMELEN + 1];
if (krb_get_lrealm(lrealm, 1) != KSUCCESS)
return (1);
if (koktologin(username, lrealm, user) && !uid) {
warnx("kerberos: not in %s's ACL.", user);
return (1);
}
(void)snprintf(krbtkfile, sizeof krbtkfile, "%s_%s_%d", TKT_ROOT,
user, getuid());
(void)setenv("KRBTKFILE", krbtkfile, 1);
(void)krb_set_tkt_string(krbtkfile);
/*
* Set real as well as effective ID to 0 for the moment,
* to make the kerberos library do the right thing.
*/
if (setuid(0) < 0) {
warn("setuid");
return (1);
}
/*
* Little trick here -- if we are su'ing to root,
* we need to get a ticket for "xxx.root", where xxx represents
* the name of the person su'ing. Otherwise (non-root case),
* we need to get a ticket for "yyy.", where yyy represents
* the name of the person being su'd to, and the instance is null
*
* We should have a way to set the ticket lifetime,
* with a system default for root.
*/
{
char prompt[128];
char passw[256];
(void)snprintf (prompt, sizeof(prompt),
"%s's Password: ",
krb_unparse_name_long ((uid == 0 ? username : user),
(uid == 0 ? "root" : ""),
lrealm));
if (des_read_pw_string (passw, sizeof (passw), prompt, 0)) {
memset (passw, 0, sizeof (passw));
return (1);
}
if (strlen(passw) == 0)
return (1); /* Empty passwords are not allowed */
kerno = krb_get_pw_in_tkt((uid == 0 ? username : user),
(uid == 0 ? "root" : ""), lrealm,
KRB_TICKET_GRANTING_TICKET,
lrealm,
DEFAULT_TKT_LIFE,
passw);
memset (passw, 0, strlen (passw));
}
if (kerno != KSUCCESS) {
if (kerno == KDC_PR_UNKNOWN) {
warnx("kerberos: principal unknown: %s.%s@%s",
(uid == 0 ? username : user),
(uid == 0 ? "root" : ""), lrealm);
return (1);
}
warnx("kerberos: unable to su: %s", krb_err_txt[kerno]);
syslog(LOG_WARNING,
"BAD Kerberos SU: %s to %s%s: %s",
username, user, ontty(), krb_err_txt[kerno]);
return (1);
}
if (chown(krbtkfile, uid, -1) < 0) {
warn("chown");
(void)unlink(krbtkfile);
return (1);
}
(void)setpriority(PRIO_PROCESS, 0, -2);
if (gethostname(hostname, sizeof(hostname)) == -1) {
warn("gethostname");
dest_tkt();
return (1);
}
hostname[sizeof(hostname) - 1] = '\0';
(void)strlcpy(savehost, krb_get_phost(hostname), sizeof(savehost));
savehost[sizeof(savehost) - 1] = '\0';
kerno = krb_mk_req(&ticket, "rcmd", savehost, lrealm, 33);
if (kerno == KDC_PR_UNKNOWN) {
warnx("Warning: TGT not verified.");
syslog(LOG_WARNING,
"%s to %s%s, TGT not verified (%s); %s.%s not registered?",
username, user, ontty(), krb_err_txt[kerno],
"rcmd", savehost);
} else if (kerno != KSUCCESS) {
warnx("Unable to use TGT: %s", krb_err_txt[kerno]);
syslog(LOG_WARNING, "failed su: %s to %s%s: %s",
username, user, ontty(), krb_err_txt[kerno]);
dest_tkt();
return (1);
} else {
if (!(hp = gethostbyname(hostname))) {
warnx("can't get addr of %s", hostname);
dest_tkt();
return (1);
}
memmove((char *)&faddr, (char *)hp->h_addr, sizeof(faddr));
if ((kerno = krb_rd_req(&ticket, "rcmd", savehost, faddr,
&authdata, "")) != KSUCCESS) {
warnx("kerberos: unable to verify rcmd ticket: %s",
krb_err_txt[kerno]);
syslog(LOG_WARNING,
"failed su: %s to %s%s: %s", username,
user, ontty(), krb_err_txt[kerno]);
dest_tkt();
return (1);
}
}
return (0);
}
static int
koktologin(char *name, char *realm, char *toname)
{
return krb_kuserok(name,
strcmp (toname, "root") == 0 ? "root" : "",
realm,
toname);
}
#endif
static int
check_ingroup (int gid, const char *gname, const char *user, int ifempty)
{
struct group *gr;
char **g;
#ifdef SU_INDIRECT_GROUP
char **gr_mem;
int n = 0;
int i = 0;
#endif
int ok = 0;
if (gname == NULL)
gr = getgrgid((gid_t) gid);
else
gr = getgrnam(gname);
/*
* XXX we are relying on the fact that we only set ifempty when
* calling to check for SU_GROUP and that is the only time a
* missing group is acceptable.
*/
if (gr == NULL)
return ifempty;
if (!*gr->gr_mem) /* empty */
return ifempty;
/*
* Ok, first see if user is in gr_mem
*/
for (g = gr->gr_mem; *g; ++g) {
if (strcmp(*g, user) == 0)
return 1; /* ok */
#ifdef SU_INDIRECT_GROUP
++n; /* count them */
#endif
}
#ifdef SU_INDIRECT_GROUP
/*
* No.
* Now we need to duplicate the gr_mem list, and recurse for
* each member to see if it is a group, and if so whether user is
* in it.
*/
gr_mem = malloc((n + 1) * sizeof (char *));
for (g = gr->gr_mem, i = 0; *g; ++g) {
gr_mem[i] = strdup(*g);
if (!gr_mem[i])
err(1, "strdup");
i++;
}
gr_mem[i++] = NULL;
for (g = gr_mem; ok == 0 && *g; ++g) {
/*
* If we get this far we don't accept empty/missing groups.
*/
ok = check_ingroup(-1, *g, user, 0);
}
for (g = gr_mem; *g; ++g) {
free(*g);
}
free(gr_mem);
#endif
return ok;
}
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