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NetBSD/usr.sbin/pppd/auth.c

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/*
* auth.c - PPP authentication and phase control.
*
* Copyright (c) 1993 The Australian National University.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the Australian National University. The name of the University
* may not be used to endorse or promote products derived from this
* software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* Copyright (c) 1989 Carnegie Mellon University.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by Carnegie Mellon University. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char rcsid[] = "$Id: auth.c,v 1.4 1994/01/25 05:58:02 paulus Exp $";
#endif
#include <stdio.h>
#include <stddef.h>
#include <syslog.h>
#include <pwd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "ppp.h"
#include "pppd.h"
#include "fsm.h"
#include "lcp.h"
#include "upap.h"
#include "chap.h"
#include "ipcp.h"
#include "pathnames.h"
#if defined(sun) && defined(sparc)
#include <alloca.h>
#ifndef __GNUC__
/* why alloca.h doesn't define what alloca() returns is a mystery */
/* char *alloca __ARGS((int)); */
#endif /*__GNUC__*/
#endif /*sun&sparc*/
/* Used for storing a sequence of words. Usually malloced. */
struct wordlist {
struct wordlist *next;
char word[1];
};
/* Bits in scan_authfile return value */
#define NONWILD_SERVER 1
#define NONWILD_CLIENT 2
#define ISWILD(word) (word[0] == '*' && word[1] == 0)
#define FALSE 0
#define TRUE 1
extern char user[];
extern char passwd[];
extern char devname[];
extern char our_name[];
extern char remote_name[];
extern char hostname[];
extern int uselogin;
extern int usehostname;
extern int auth_required;
/* Records which authentication operations haven't completed yet. */
static int auth_pending[NPPP];
static int logged_in;
static struct wordlist *addresses[NPPP];
/* Bits in auth_pending[] */
#define UPAP_WITHPEER 1
#define UPAP_PEER 2
#define CHAP_WITHPEER 4
#define CHAP_PEER 8
/* Prototypes */
void check_access __ARGS((FILE *, char *));
static int login __ARGS((char *, char *, char **, int *));
static void logout __ARGS((void));
static int get_upap_passwd __ARGS((void));
static int have_upap_secret __ARGS((void));
static int have_chap_secret __ARGS((char *, char *));
static int scan_authfile __ARGS((FILE *, char *, char *, char *,
struct wordlist **, char *));
static void free_wordlist __ARGS((struct wordlist *));
extern char *crypt __ARGS((char *, char *));
/*
* An Open on LCP has requested a change from Dead to Establish phase.
* Do what's necessary to bring the physical layer up.
*/
void
link_required(unit)
int unit;
{
}
/*
* LCP has terminated the link; go to the Dead phase and take the
* physical layer down.
*/
void
link_terminated(unit)
int unit;
{
if (logged_in)
logout();
if (lcp_wantoptions[unit].restart) {
lcp_lowerdown(unit);
lcp_lowerup(unit);
} else
EXIT(unit);
}
/*
* The link is established.
* Proceed to the Dead, Authenticate or Network phase as appropriate.
*/
void
link_established(unit)
int unit;
{
int auth;
lcp_options *wo = &lcp_wantoptions[unit];
lcp_options *go = &lcp_gotoptions[unit];
lcp_options *ho = &lcp_hisoptions[unit];
if (auth_required && !(go->neg_chap || go->neg_upap)) {
/*
* We wanted the peer to authenticate himself, and he refused:
* tell him to go away.
*/
syslog(LOG_WARNING, "peer refused to authenticate");
lcp_close(unit);
return;
}
auth = 0;
if (go->neg_chap) {
ChapAuthPeer(unit, our_name, go->chap_mdtype);
auth |= CHAP_PEER;
} else if (go->neg_upap) {
upap_authpeer(unit);
auth |= UPAP_PEER;
}
if (ho->neg_chap) {
ChapAuthWithPeer(unit, our_name, ho->chap_mdtype);
auth |= CHAP_WITHPEER;
} else if (ho->neg_upap) {
upap_authwithpeer(unit, user, passwd);
auth |= UPAP_WITHPEER;
}
auth_pending[unit] = auth;
if (!auth)
ipcp_open(unit);
}
/*
* The peer has failed to authenticate himself using `protocol'.
*/
void
auth_peer_fail(unit, protocol)
int unit, protocol;
{
/*
* Authentication failure: take the link down
*/
lcp_close(unit);
}
/*
* The peer has been successfully authenticated using `protocol'.
*/
void
auth_peer_success(unit, protocol)
int unit, protocol;
{
int bit;
switch (protocol) {
case CHAP:
bit = CHAP_PEER;
break;
case UPAP:
bit = UPAP_PEER;
break;
default:
syslog(LOG_WARNING, "auth_peer_success: unknown protocol %x",
protocol);
return;
}
/*
* If there is no more authentication still to be done,
* proceed to the network phase.
*/
if ((auth_pending[unit] &= ~bit) == 0)
ipcp_open(unit);
}
/*
* We have failed to authenticate ourselves to the peer using `protocol'.
*/
void
auth_withpeer_fail(unit, protocol)
int unit, protocol;
{
/*
* We've failed to authenticate ourselves to our peer.
* He'll probably take the link down, and there's not much
* we can do except wait for that.
*/
}
/*
* We have successfully authenticated ourselves with the peer using `protocol'.
*/
void
auth_withpeer_success(unit, protocol)
int unit, protocol;
{
int bit;
switch (protocol) {
case CHAP:
bit = CHAP_WITHPEER;
break;
case UPAP:
bit = UPAP_WITHPEER;
break;
default:
syslog(LOG_WARNING, "auth_peer_success: unknown protocol %x",
protocol);
}
/*
* If there is no more authentication still being done,
* proceed to the network phase.
*/
if ((auth_pending[unit] &= ~bit) == 0)
ipcp_open(unit);
}
/*
* check_auth_options - called to check authentication options.
*/
void
check_auth_options()
{
lcp_options *wo = &lcp_wantoptions[0];
lcp_options *ao = &lcp_allowoptions[0];
/* Default our_name to hostname, and user to our_name */
if (our_name[0] == 0 || usehostname)
strcpy(our_name, hostname);
if (user[0] == 0)
strcpy(user, our_name);
/* If authentication is required, ask peer for CHAP or PAP. */
if (auth_required && !wo->neg_chap && !wo->neg_upap) {
wo->neg_chap = 1;
wo->neg_upap = 1;
}
/*
* Check whether we have appropriate secrets to use
* to authenticate ourselves and/or the peer.
*/
if (ao->neg_upap && passwd[0] == 0 && !get_upap_passwd())
ao->neg_upap = 0;
if (wo->neg_upap && !uselogin && !have_upap_secret())
wo->neg_upap = 0;
if (ao->neg_chap && !have_chap_secret(our_name, remote_name))
ao->neg_chap = 0;
if (wo->neg_chap && !have_chap_secret(remote_name, our_name))
wo->neg_chap = 0;
if (auth_required && !wo->neg_chap && !wo->neg_upap) {
fprintf(stderr, "\
pppd: peer authentication required but no authentication files accessible\n");
exit(1);
}
}
/*
* check_passwd - Check the user name and passwd against the PAP secrets
* file. If requested, also check against the system password database,
* and login the user if OK.
*
* returns:
* UPAP_AUTHNAK: Authentication failed.
* UPAP_AUTHACK: Authentication succeeded.
* In either case, msg points to an appropriate message.
*/
int
check_passwd(unit, auser, userlen, apasswd, passwdlen, msg, msglen)
int unit;
char *auser;
int userlen;
char *apasswd;
int passwdlen;
char **msg;
int *msglen;
{
int ret;
char *filename;
FILE *f;
struct wordlist *addrs;
char passwd[256], user[256];
char secret[MAXWORDLEN];
static int attempts = 0;
/*
* Make copies of apasswd and auser, then null-terminate them.
*/
BCOPY(apasswd, passwd, passwdlen);
passwd[passwdlen] = '\0';
BCOPY(auser, user, userlen);
user[userlen] = '\0';
/*
* Open the file of upap secrets and scan for a suitable secret
* for authenticating this user.
*/
filename = _PATH_UPAPFILE;
addrs = NULL;
ret = UPAP_AUTHACK;
f = fopen(filename, "r");
if (f == NULL) {
if (!uselogin) {
syslog(LOG_ERR, "Can't open upap password file %s: %m", filename);
ret = UPAP_AUTHNAK;
}
} else {
check_access(f, filename);
if (scan_authfile(f, user, our_name, secret, &addrs, filename) < 0
|| (secret[0] != 0 && strcmp(passwd, secret) != 0
&& strcmp(crypt(passwd, secret), secret) != 0)) {
syslog(LOG_WARNING, "upap authentication failure for %s", user);
ret = UPAP_AUTHNAK;
}
fclose(f);
}
if (uselogin && ret == UPAP_AUTHACK) {
ret = login(user, passwd, msg, msglen);
if (ret == UPAP_AUTHNAK) {
syslog(LOG_WARNING, "upap login failure for %s", user);
}
}
if (ret == UPAP_AUTHNAK) {
*msg = "Login incorrect";
*msglen = strlen(*msg);
/*
* Frustrate passwd stealer programs.
* Allow 10 tries, but start backing off after 3 (stolen from login).
* On 10'th, drop the connection.
*/
if (attempts++ >= 10) {
syslog(LOG_WARNING, "%d LOGIN FAILURES ON %s, %s",
attempts, devname, user);
quit();
}
if (attempts > 3)
sleep((u_int) (attempts - 3) * 5);
if (addrs != NULL)
free_wordlist(addrs);
} else {
attempts = 0; /* Reset count */
*msg = "Login ok";
*msglen = strlen(*msg);
if (addresses[unit] != NULL)
free_wordlist(addresses[unit]);
addresses[unit] = addrs;
}
return ret;
}
/*
* login - Check the user name and password against the system
* password database, and login the user if OK.
*
* returns:
* UPAP_AUTHNAK: Login failed.
* UPAP_AUTHACK: Login succeeded.
* In either case, msg points to an appropriate message.
*/
static int
login(user, passwd, msg, msglen)
char *user;
char *passwd;
char **msg;
int *msglen;
{
struct passwd *pw;
char *epasswd;
char *tty;
if ((pw = getpwnam(user)) == NULL) {
return (UPAP_AUTHNAK);
}
/*
* XXX If no passwd, let them login without one.
*/
if (pw->pw_passwd == '\0') {
return (UPAP_AUTHACK);
}
epasswd = crypt(passwd, pw->pw_passwd);
if (strcmp(epasswd, pw->pw_passwd)) {
return (UPAP_AUTHNAK);
}
syslog(LOG_INFO, "user %s logged in", user);
/*
* Write a wtmp entry for this user.
*/
tty = strrchr(devname, '/');
if (tty == NULL)
tty = devname;
else
tty++;
logwtmp(tty, user, ""); /* Add wtmp login entry */
logged_in = TRUE;
return (UPAP_AUTHACK);
}
/*
* logout - Logout the user.
*/
static void
logout()
{
char *tty;
tty = strrchr(devname, '/');
if (tty == NULL)
tty = devname;
else
tty++;
logwtmp(tty, "", ""); /* Wipe out wtmp logout entry */
logged_in = FALSE;
}
/*
* get_upap_passwd - get a password for authenticating ourselves with
* our peer using PAP. Returns 1 on success, 0 if no suitable password
* could be found.
*/
static int
get_upap_passwd()
{
char *filename;
FILE *f;
struct wordlist *addrs;
char secret[MAXWORDLEN];
filename = _PATH_UPAPFILE;
addrs = NULL;
f = fopen(filename, "r");
if (f == NULL)
return 0;
check_access(f, filename);
if (scan_authfile(f, user, remote_name, secret, NULL, filename) < 0)
return 0;
strncpy(passwd, secret, MAXSECRETLEN);
passwd[MAXSECRETLEN-1] = 0;
return 1;
}
/*
* have_upap_secret - check whether we have a PAP file with any
* secrets that we could possibly use for authenticating the peer.
*/
static int
have_upap_secret()
{
FILE *f;
int ret;
char *filename;
filename = _PATH_UPAPFILE;
f = fopen(filename, "r");
if (f == NULL)
return 0;
ret = scan_authfile(f, NULL, our_name, NULL, NULL, filename);
fclose(f);
if (ret < 0)
return 0;
return 1;
}
/*
* have_chap_secret - check whether we have a CHAP file with a
* secret that we could possibly use for authenticating `client'
* on `server'. Either can be the null string, meaning we don't
* know the identity yet.
*/
static int
have_chap_secret(client, server)
char *client;
char *server;
{
FILE *f;
int ret;
char *filename;
filename = _PATH_CHAPFILE;
f = fopen(filename, "r");
if (f == NULL)
return 0;
if (client[0] == 0)
client = NULL;
else if (server[0] == 0)
server = NULL;
ret = scan_authfile(f, client, server, NULL, NULL, filename);
fclose(f);
if (ret < 0)
return 0;
return 1;
}
/*
* get_secret - open the CHAP secret file and return the secret
* for authenticating the given client on the given server.
* (We could be either client or server).
*/
int
get_secret(unit, client, server, secret, secret_len, save_addrs)
int unit;
char *client;
char *server;
char *secret;
int *secret_len;
{
FILE *f;
int ret, len;
char *filename;
struct wordlist *addrs;
char secbuf[MAXWORDLEN];
filename = _PATH_CHAPFILE;
addrs = NULL;
secbuf[0] = 0;
f = fopen(filename, "r");
if (f == NULL) {
syslog(LOG_ERR, "Can't open chap secret file %s: %m", filename);
return 0;
}
check_access(f, filename);
ret = scan_authfile(f, client, server, secbuf, &addrs, filename);
fclose(f);
if (ret < 0)
return 0;
if (save_addrs) {
if (addresses[unit] != NULL)
free_wordlist(addresses[unit]);
addresses[unit] = addrs;
}
len = strlen(secbuf);
if (len > MAXSECRETLEN) {
syslog(LOG_ERR, "Secret for %s on %s is too long", client, server);
len = MAXSECRETLEN;
}
BCOPY(secbuf, secret, len);
*secret_len = len;
return 1;
}
/*
* auth_ip_addr - check whether the peer is authorized to use
* a given IP address. Returns 1 if authorized, 0 otherwise.
*/
int
auth_ip_addr(unit, addr)
int unit;
u_long addr;
{
u_long a;
struct hostent *hp;
struct wordlist *addrs;
if ((addrs = addresses[unit]) == NULL)
return 1; /* no restriction */
for (; addrs != NULL; addrs = addrs->next) {
/* "-" means no addresses authorized */
if (strcmp(addrs->word, "-") == 0)
break;
if ((a = inet_addr(addrs->word)) == -1) {
if ((hp = gethostbyname(addrs->word)) == NULL) {
syslog(LOG_WARNING, "unknown host %s in auth. address list",
addrs->word);
continue;
} else
a = *(u_long *)hp->h_addr;
}
if (addr == a)
return 1;
}
return 0; /* not in list => can't have it */
}
/*
* check_access - complain if a secret file has too-liberal permissions.
*/
void
check_access(f, filename)
FILE *f;
char *filename;
{
struct stat sbuf;
if (fstat(fileno(f), &sbuf) < 0) {
syslog(LOG_WARNING, "cannot stat secret file %s: %m", filename);
} else if ((sbuf.st_mode & (S_IRWXG | S_IRWXO)) != 0) {
syslog(LOG_WARNING, "Warning - secret file %s has world and/or group access", filename);
}
}
/*
* scan_authfile - Scan an authorization file for a secret suitable
* for authenticating `client' on `server'. The return value is -1
* if no secret is found, otherwise >= 0. The return value has
* NONWILD_CLIENT set if the secret didn't have "*" for the client, and
* NONWILD_SERVER set if the secret didn't have "*" for the server.
* Any following words on the line (i.e. address authorization
* info) are placed in a wordlist and returned in *addrs.
*/
static int
scan_authfile(f, client, server, secret, addrs, filename)
FILE *f;
char *client;
char *server;
char *secret;
struct wordlist **addrs;
char *filename;
{
int newline, xxx;
int got_flag, best_flag;
FILE *sf;
struct wordlist *ap, *addr_list, *addr_last;
char word[MAXWORDLEN];
char atfile[MAXWORDLEN];
if (addrs != NULL)
*addrs = NULL;
addr_list = NULL;
if (!getword(f, word, &newline, filename))
return -1; /* file is empty??? */
newline = 1;
best_flag = -1;
for (;;) {
/*
* Skip until we find a word at the start of a line.
*/
while (!newline && getword(f, word, &newline, filename))
;
if (!newline)
break; /* got to end of file */
/*
* Got a client - check if it's a match or a wildcard.
*/
got_flag = 0;
if (client != NULL && strcmp(word, client) != 0 && !ISWILD(word)) {
newline = 0;
continue;
}
if (!ISWILD(word))
got_flag = NONWILD_CLIENT;
/*
* Now get a server and check if it matches.
*/
if (!getword(f, word, &newline, filename))
break;
if (newline)
continue;
if (server != NULL && strcmp(word, server) != 0 && !ISWILD(word))
continue;
if (!ISWILD(word))
got_flag |= NONWILD_SERVER;
/*
* Got some sort of a match - see if it's better than what
* we have already.
*/
if (got_flag <= best_flag)
continue;
/*
* Get the secret.
*/
if (!getword(f, word, &newline, filename))
break;
if (newline)
continue;
/*
* Special syntax: @filename means read secret from file.
*/
if (word[0] == '@') {
strcpy(atfile, word+1);
if ((sf = fopen(atfile, "r")) == NULL) {
syslog(LOG_WARNING, "can't open indirect secret file %s",
atfile);
continue;
}
check_access(sf, atfile);
if (!getword(sf, word, &xxx, atfile)) {
syslog(LOG_WARNING, "no secret in indirect secret file %s",
atfile);
fclose(sf);
continue;
}
fclose(sf);
}
if (secret != NULL)
strcpy(secret, word);
best_flag = got_flag;
/*
* Now read address authorization info and make a wordlist.
*/
if (addr_list)
free_wordlist(addr_list);
addr_list = NULL;
for (;;) {
if (!getword(f, word, &newline, filename) || newline)
break;
ap = (struct wordlist *) malloc(sizeof(struct wordlist)
+ strlen(word));
if (ap == NULL)
novm("authorized addresses");
ap->next = NULL;
strcpy(ap->word, word);
if (addr_list == NULL)
addr_list = ap;
else
addr_last->next = ap;
addr_last = ap;
}
if (!newline)
break;
}
if (addrs != NULL)
*addrs = addr_list;
else if (addr_list != NULL)
free_wordlist(addr_list);
return best_flag;
}
/*
* free_wordlist - release memory allocated for a wordlist.
*/
static void
free_wordlist(wp)
struct wordlist *wp;
{
struct wordlist *next;
while (wp != NULL) {
next = wp->next;
free(wp);
wp = next;
}
}
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