/* checktty.c - linked into login, checks user against /etc/usertty
Created 25-Aug-95 by Peter Orbaek <poe@daimi.aau.dk>
Fixed by JDS June 1996 to clear lists and close files
1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
- added Native Language Support
*/
#include <sys/types.h>
#include <sys/param.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>
#include <sys/stat.h>
#include <malloc.h>
#include <netdb.h>
#include <sys/syslog.h>
#include "nls.h"
#include <sys/sysmacros.h>
#include <linux/major.h>
#include "pathnames.h"
#include "login.h"
#include "xstrncpy.h"
static gid_t mygroups[NGROUPS];
static int num_groups;
#define NAMELEN 128
/* linked list of names */
struct grplist {
struct grplist *next;
char name[NAMELEN];
};
enum State { StateUsers, StateGroups, StateClasses };
#define CLASSNAMELEN 32
struct ttyclass {
struct grplist *first;
struct ttyclass *next;
char classname[CLASSNAMELEN];
};
struct ttyclass *ttyclasses = NULL;
static int
am_in_group(char *group)
{
struct group *g;
gid_t *ge;
g = getgrnam(group);
if (g) {
for (ge = mygroups; ge < mygroups + num_groups; ge++) {
if (g->gr_gid== *ge) return 1;
}
}
return 0;
}
static void
find_groups(gid_t defgrp, const char *user)
{
num_groups = getgroups(NGROUPS, mygroups);
}
static struct ttyclass *
new_class(char *class)
{
struct ttyclass *tc;
tc = (struct ttyclass *)malloc(sizeof(struct ttyclass));
if (tc == NULL) {
printf(_("login: memory low, login may fail\n"));
syslog(LOG_WARNING, _("can't malloc for ttyclass"));
return NULL;
}
tc->next = ttyclasses;
tc->first = NULL;
xstrncpy(tc->classname, class, CLASSNAMELEN);
ttyclasses = tc;
return tc;
}
static void
add_to_class(struct ttyclass *tc, char *tty)
{
struct grplist *ge;
if (tc == NULL) return;
ge = (struct grplist *)malloc(sizeof(struct grplist));
if (ge == NULL) {
printf(_("login: memory low, login may fail\n"));
syslog(LOG_WARNING, _("can't malloc for grplist"));
return;
}
ge->next = tc->first;
xstrncpy(ge->name, tty, NAMELEN);
tc->first = ge;
}
/* return true if tty is a pty. Very linux dependent */
static int
isapty(const char *tty)
{
char devname[100];
struct stat stb;
/* avoid snprintf - old systems do not have it */
if (strlen(tty) + 6 > sizeof(devname))
return 0;
sprintf(devname, "/dev/%s", tty);
if((stat(devname, &stb) >= 0) && S_ISCHR(stb.st_mode)) {
int majordev = major(stb.st_rdev);
/* this is for linux versions before 1.3: use major 4 */
if(majordev == TTY_MAJOR && minor(stb.st_rdev) >= 192)
return 1;
#if defined(PTY_SLAVE_MAJOR)
/* this is for linux 1.3 and newer: use major 3 */
if(majordev == PTY_SLAVE_MAJOR)
return 1;
#endif
#if defined(UNIX98_PTY_SLAVE_MAJOR) && defined(UNIX98_PTY_MAJOR_COUNT)
/* this is for linux 2.1.116 and newer: use majors 136-143 */
if(majordev >= UNIX98_PTY_SLAVE_MAJOR &&
majordev < UNIX98_PTY_SLAVE_MAJOR + UNIX98_PTY_MAJOR_COUNT)
return 1;
#endif
}
return 0;
}
/* match the hostname hn against the pattern pat */
static int
hnmatch(const char *hn, const char *pat)
{
int x1, x2, x3, x4, y1, y2, y3, y4;
unsigned long p, mask, a;
unsigned char *ha;
int n, m;
if ((hn == NULL) && (strcmp(pat, "localhost") == 0)) return 1;
if ((hn == NULL) || hn[0] == 0) return 0;
if (pat[0] >= '0' && pat[0] <= '9') {
/* pattern is an IP QUAD address and a mask x.x.x.x/y.y.y.y */
sscanf(pat, "%d.%d.%d.%d/%d.%d.%d.%d", &x1, &x2, &x3, &x4,
&y1, &y2, &y3, &y4);
p = (((unsigned long)x1<<24)+((unsigned long)x2<<16)
+((unsigned long)x3<<8)+((unsigned long)x4));
mask = (((unsigned long)y1<<24)+((unsigned long)y2<<16)
+((unsigned long)y3<<8)+((unsigned long)y4));
if (hostaddress[0] == 0)
return 0;
ha = (unsigned char *)hostaddress;
a = (((unsigned long)ha[0]<<24)+((unsigned long)ha[1]<<16)
+((unsigned long)ha[2]<<8)+((unsigned long)ha[3]));
return ((p & mask) == (a & mask));
} else {
/* pattern is a suffix of a FQDN */
n = strlen(pat);
m = strlen(hn);
if (n > m) return 0;
return (strcasecmp(pat, hn + m - n) == 0);
}
}
static char *wdays[] = { "sun", "mon", "tue", "wed", "thu", "fri", "sat" };
/* example timespecs:
mon:tue:wed:8-17
meaning monday, tuesday or wednesday between 8:00 and 17:59
4:5:13:fri
meaning fridays from 4:00 to 5:59 and from 13:00 to 13:59
*/
static int
timeok(struct tm *t, char *spec)
{
char *p, *q;
int dayok = 0;
int hourok = 0;
int h, h2;
char *sp;
sp = spec;
while ((p = strsep(&sp, ":"))) {
if (*p >= '0' && *p <= '9') {
h = atoi(p);
if (h == t->tm_hour) hourok = 1;
if ((q = strchr(p, '-')) && (q[1] >= '0' && q[1] <= '9')) {
h2 = atoi(q+1);
if (h <= t->tm_hour && t->tm_hour <= h2) hourok = 1;
}
} else if (strcasecmp(wdays[t->tm_wday], p) == 0) {
dayok = 1;
}
}
return (dayok && hourok);
}
/* return true if tty equals class or is in the class defined by class.
Also return true if hostname matches the hostname pattern, class
or a pattern in the class named by class. */
static int
in_class(const char *tty, char *class)
{
struct ttyclass *tc;
struct grplist *ge;
time_t t;
char *p;
char timespec[256];
struct tm *tm;
char *n;
time(&t);
tm = localtime(&t);
if (class[0] == '[') {
if ((p = strchr(class, ']'))) {
*p = 0;
xstrncpy(timespec, class+1, sizeof(timespec));
*p = ']';
if(!timeok(tm, timespec)) return 0;
class = p+1;
}
/* really ought to warn about syntax error */
}
if (strcmp(tty, class) == 0) return 1;
if ((class[0] == '@') && isapty(tty)
&& hnmatch(hostname, class+1)) return 1;
for (tc = ttyclasses; tc; tc = tc->next) {
if (strcmp(tc->classname, class) == 0) {
for (ge = tc->first; ge; ge = ge->next) {
n = ge->name;
if (n[0] == '[') {
if ((p = strchr(n, ']'))) {
*p = 0;
xstrncpy(timespec, n+1, sizeof(timespec));
*p = ']';
if(!timeok(tm, timespec)) continue;
n = p+1;
}
/* really ought to warn about syntax error */
}
if (strcmp(n, tty) == 0) return 1;
if ((n[0] == '@') && isapty(tty)
&& hnmatch(hostname, n+1)) return 1;
}
return 0;
}
}
return 0;
}
/* start JDS - SBA */
static void
free_group(struct grplist *ge)
{
if (ge) {
memset(ge->name, 0, NAMELEN);
free_group(ge->next);
free(ge->next);
ge->next = NULL;
}
}
static void
free_class(struct ttyclass *tc)
{
if (tc) {
memset(tc->classname, 0, CLASSNAMELEN);
free_group(tc->first);
tc->first = NULL;
free_class(tc->next);
free(tc->next);
tc->next = NULL;
}
}
static void
free_all(void)
{
free_class(ttyclasses);
ttyclasses = NULL;
}
/* end JDS - SBA */
void
checktty(const char *user, const char *tty, struct passwd *pwd)
{
FILE *f;
char buf[256], defaultbuf[256];
char *ptr;
enum State state = StateUsers;
int found_match = 0;
/* no /etc/usertty, default to allow access */
if (!(f = fopen(_PATH_USERTTY, "r"))) return;
if (pwd == NULL) {
fclose(f);
return; /* misspelled username handled elsewhere */
}
find_groups(pwd->pw_gid, user);
defaultbuf[0] = 0;
while(fgets(buf, 255, f)) {
/* strip comments */
for(ptr = buf; ptr < buf + 256; ptr++)
if(*ptr == '#') *ptr = 0;
if (buf[0] == '*') {
xstrncpy(defaultbuf, buf, 256);
continue;
}
if (strncmp("GROUPS", buf, 6) == 0) {
state = StateGroups;
continue;
} else if (strncmp("USERS", buf, 5) == 0) {
state = StateUsers;
continue;
} else if (strncmp("CLASSES", buf, 7) == 0) {
state = StateClasses;
continue;
}
strtok(buf, " \t");
if((state == StateUsers && (strncmp(user, buf, 8) == 0))
|| (state == StateGroups && am_in_group(buf))) {
found_match = 1; /* we found a line matching the user */
while((ptr = strtok(NULL, "\t\n "))) {
if (in_class(tty, ptr)) {
fclose(f);
free_all(); /* JDS */
return;
}
}
} else if (state == StateClasses) {
/* define a new tty/host class */
struct ttyclass *tc = new_class(buf);
while ((ptr = strtok(NULL, "\t\n "))) {
add_to_class(tc, ptr);
}
}
}
fclose(f);
/* user is not explicitly mentioned in /etc/usertty, if there was
a default rule, use that */
if (defaultbuf[0]) {
strtok(defaultbuf, " \t");
while((ptr = strtok(NULL, "\t\n "))) {
if (in_class(tty, ptr)) {
free_all(); /* JDS */
return;
}
}
/* there was a default rule, but user didn't match, reject! */
printf(_("Login on %s from %s denied by default.\n"), tty, hostname);
badlogin(user);
sleepexit(1);
}
if (found_match) {
/* if we get here, /etc/usertty exists, there's a line
matching our username, but it doesn't contain the
name of the tty where the user is trying to log in.
So deny access! */
printf(_("Login on %s from %s denied.\n"), tty, hostname);
badlogin(user);
sleepexit(1);
}
/* users not matched in /etc/usertty are by default allowed access
on all tty's */
free_all(); /* JDS */
}
