shadow/lib/port.c
Samanta Navarro ffc480c2e9 Explicitly override only newlines
Override only newlines with '\0' to avoid undesired truncation of
actual line content.

Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
2023-02-01 15:47:35 -06:00

455 lines
9.7 KiB
C

/*
* SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 1997, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2005 , Tomasz Kłoczko
* SPDX-FileCopyrightText: 2008 , Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ident "$Id$"
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include "defines.h"
#include "prototypes.h"
#include "port.h"
static FILE *ports;
/*
* portcmp - compare the name of a port to a /etc/porttime entry
*
* portcmp works like strcmp, except that if the last character
* in a failing match is a '*', the match is considered to have
* passed. The "*" match is suppressed whenever the port is "SU",
* which is the token the "su" command uses to validate access.
* A match returns 0, failure returns non-zero.
*/
static int portcmp (const char *pattern, const char *port)
{
const char *orig = port;
while (('\0' != *pattern) && (*pattern == *port)) {
pattern++;
port++;
}
if (('\0' == *pattern) && ('\0' == *port)) {
return 0;
}
if (('S' == orig[0]) && ('U' == orig[1]) && ('\0' == orig[2])) {
return 1;
}
return (*pattern == '*') ? 0 : 1;
}
/*
* setportent - open /etc/porttime file or rewind
*
* the /etc/porttime file is rewound if already open, or
* opened for reading.
*/
static void setportent (void)
{
if (NULL != ports) {
rewind (ports);
} else {
ports = fopen (PORTS, "r");
}
}
/*
* endportent - close the /etc/porttime file
*
* the /etc/porttime file is closed and the ports variable set
* to NULL to indicate that the /etc/porttime file is no longer
* open.
*/
static void endportent (void)
{
if (NULL != ports) {
(void) fclose (ports);
}
ports = (FILE *) 0;
}
/*
* getportent - read a single entry from /etc/porttime
*
* the next line in /etc/porttime is converted to a (struct port)
* and a pointer to a static (struct port) is returned to the
* invoker. NULL is returned on either EOF or error. errno is
* set to EINVAL on error to distinguish the two conditions.
*/
static struct port *getportent (void)
{
static struct port port; /* static struct to point to */
static char buf[BUFSIZ]; /* some space for stuff */
static char *ttys[PORT_TTY + 1]; /* some pointers to tty names */
static char *users[PORT_IDS + 1]; /* some pointers to user ids */
static struct pt_time ptimes[PORT_TIMES + 1]; /* time ranges */
char *cp; /* pointer into line */
int dtime; /* scratch time of day */
int i, j;
int saveerr = errno; /* errno value on entry */
/*
* If the ports file is not open, open the file. Do not rewind
* since we want to search from the beginning each time.
*/
if (NULL == ports) {
setportent ();
}
if (NULL == ports) {
errno = saveerr;
return 0;
}
/*
* Common point for beginning a new line -
*
* - read a line, and NUL terminate
* - skip lines which begin with '#'
* - parse off the tty names
* - parse off a list of user names
* - parse off a list of days and times
*/
again:
/*
* Get the next line and remove optional trailing '\n'.
* Lines which begin with '#' are all ignored.
*/
if (fgets (buf, (int) sizeof buf, ports) == 0) {
errno = saveerr;
return 0;
}
if ('#' == buf[0]) {
goto again;
}
/*
* Get the name of the TTY device. It is the first colon
* separated field, and is the name of the TTY with no
* leading "/dev". The entry '*' is used to specify all
* TTY devices.
*/
buf[strcspn (buf, "\n")] = 0;
port.pt_names = ttys;
for (cp = buf, j = 0; j < PORT_TTY; j++) {
port.pt_names[j] = cp;
while (('\0' != *cp) && (':' != *cp) && (',' != *cp)) {
cp++;
}
if ('\0' == *cp) {
goto again; /* line format error */
}
if (':' == *cp) { /* end of tty name list */
break;
}
if (',' == *cp) { /* end of current tty name */
*cp++ = '\0';
}
}
*cp = '\0';
cp++;
port.pt_names[j + 1] = (char *) 0;
/*
* Get the list of user names. It is the second colon
* separated field, and is a comma separated list of user
* names. The entry '*' is used to specify all usernames.
* The last entry in the list is a (char *) 0 pointer.
*/
if (':' != *cp) {
port.pt_users = users;
port.pt_users[0] = cp;
for (j = 1; ':' != *cp; cp++) {
if ((',' == *cp) && (j < PORT_IDS)) {
*cp = '\0';
cp++;
port.pt_users[j] = cp;
j++;
}
}
port.pt_users[j] = 0;
} else {
port.pt_users = 0;
}
if (':' != *cp) {
goto again;
}
*cp = '\0';
cp++;
/*
* Get the list of valid times. The times field is the third
* colon separated field and is a list of days of the week and
* times during which this port may be used by this user. The
* valid days are 'Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', and 'Sa'.
*
* In addition, the value 'Al' represents all 7 days, and 'Wk'
* represents the 5 weekdays.
*
* Times are given as HHMM-HHMM. The ending time may be before
* the starting time. Days are presumed to wrap at 0000.
*/
if ('\0' == *cp) {
port.pt_times = 0;
return &port;
}
port.pt_times = ptimes;
/*
* Get the next comma separated entry
*/
for (j = 0; ('\0' != *cp) && (j < PORT_TIMES); j++) {
/*
* Start off with no days of the week
*/
port.pt_times[j].t_days = 0;
/*
* Check each two letter sequence to see if it is
* one of the abbreviations for the days of the
* week or the other two values.
*/
for (i = 0;
('\0' != cp[i]) && ('\0' != cp[i + 1]) && isalpha (cp[i]);
i += 2) {
switch ((cp[i] << 8) | (cp[i + 1])) {
case ('S' << 8) | 'u':
port.pt_times[j].t_days |= 01;
break;
case ('M' << 8) | 'o':
port.pt_times[j].t_days |= 02;
break;
case ('T' << 8) | 'u':
port.pt_times[j].t_days |= 04;
break;
case ('W' << 8) | 'e':
port.pt_times[j].t_days |= 010;
break;
case ('T' << 8) | 'h':
port.pt_times[j].t_days |= 020;
break;
case ('F' << 8) | 'r':
port.pt_times[j].t_days |= 040;
break;
case ('S' << 8) | 'a':
port.pt_times[j].t_days |= 0100;
break;
case ('W' << 8) | 'k':
port.pt_times[j].t_days |= 076;
break;
case ('A' << 8) | 'l':
port.pt_times[j].t_days |= 0177;
break;
default:
errno = EINVAL;
return 0;
}
}
/*
* The default is 'Al' if no days were seen.
*/
if (0 == i) {
port.pt_times[j].t_days = 0177;
}
/*
* The start and end times are separated from each
* other by a '-'. The times are four digit numbers
* representing the times of day.
*/
for (dtime = 0; ('\0' != cp[i]) && isdigit (cp[i]); i++) {
dtime = dtime * 10 + cp[i] - '0';
}
if (('-' != cp[i]) || (dtime > 2400) || ((dtime % 100) > 59)) {
goto again;
}
port.pt_times[j].t_start = dtime;
cp = cp + i + 1;
for (dtime = 0, i = 0;
('\0' != cp[i]) && isdigit (cp[i]);
i++) {
dtime = dtime * 10 + cp[i] - '0';
}
if ( ((',' != cp[i]) && ('\0' != cp[i]))
|| (dtime > 2400)
|| ((dtime % 100) > 59)) {
goto again;
}
port.pt_times[j].t_end = dtime;
cp = cp + i + 1;
}
/*
* The end of the list is indicated by a pair of -1's for the
* start and end times.
*/
port.pt_times[j].t_start = port.pt_times[j].t_end = -1;
return &port;
}
/*
* getttyuser - get ports information for user and tty
*
* getttyuser() searches the ports file for an entry with a TTY
* and user field both of which match the supplied TTY and
* user name. The file is searched from the beginning, so the
* entries are treated as an ordered list.
*/
static struct port *getttyuser (const char *tty, const char *user)
{
int i, j;
struct port *port;
setportent ();
while ((port = getportent ()) != NULL) {
if ( (0 == port->pt_names)
|| (0 == port->pt_users)) {
continue;
}
for (i = 0; NULL != port->pt_names[i]; i++) {
if (portcmp (port->pt_names[i], tty) == 0) {
break;
}
}
if (port->pt_names[i] == 0) {
continue;
}
for (j = 0; NULL != port->pt_users[j]; j++) {
if ( (strcmp (user, port->pt_users[j]) == 0)
|| (strcmp (port->pt_users[j], "*") == 0)) {
break;
}
}
if (port->pt_users[j] != 0) {
break;
}
}
endportent ();
return port;
}
/*
* isttytime - tell if a given user may login at a particular time
*
* isttytime searches the ports file for an entry which matches
* the user name and TTY given.
*/
bool isttytime (const char *id, const char *port, time_t when)
{
int i;
int dtime;
struct port *pp;
struct tm *tm;
/*
* Try to find a matching entry for this user. Default to
* letting the user in - there are plenty of ways to have an
* entry to match all users.
*/
pp = getttyuser (port, id);
if (NULL == pp) {
return true;
}
/*
* The entry is there, but has no time entries - don't
* ever let them login.
*/
if (0 == pp->pt_times) {
return false;
}
/*
* The current time is converted to HHMM format for
* comparison against the time values in the TTY entry.
*/
tm = localtime (&when);
dtime = tm->tm_hour * 100 + tm->tm_min;
/*
* Each time entry is compared against the current
* time. For entries with the start after the end time,
* the comparison is made so that the time is between
* midnight and either the start or end time.
*/
for (i = 0; pp->pt_times[i].t_start != -1; i++) {
if (!(pp->pt_times[i].t_days & PORT_DAY (tm->tm_wday))) {
continue;
}
if (pp->pt_times[i].t_start <= pp->pt_times[i].t_end) {
if ( (dtime >= pp->pt_times[i].t_start)
&& (dtime <= pp->pt_times[i].t_end)) {
return true;
}
} else {
if ( (dtime >= pp->pt_times[i].t_start)
|| (dtime <= pp->pt_times[i].t_end)) {
return true;
}
}
}
/*
* No matching time entry was found, user shouldn't
* be let in right now.
*/
return false;
}