shadow/lib/shadow.c

/*
 * SPDX-FileCopyrightText: 1989 - 1994, Julianne Frances Haugh
 * SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
 * SPDX-FileCopyrightText: 2003 - 2005, Tomasz Kłoczko
 * SPDX-FileCopyrightText: 2009       , Nicolas François
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <config.h>

/* Newer versions of Linux libc already have shadow support.  */
#ifndef HAVE_GETSPNAM

#ident "$Id$"

#include <sys/types.h>
#include "prototypes.h"
#include "defines.h"
#include <stdio.h>
#ifdef	USE_NIS
static bool nis_used;
static bool nis_ignore;
static enum { native, start, middle, native2 } nis_state;
static bool nis_bound;
static char *nis_domain;
static char *nis_key;
static int nis_keylen;
static char *nis_val;
static int nis_vallen;

#define	IS_NISCHAR(c) ((c)=='+')
#endif

static FILE *shadow;

#define	FIELDS	9
#define	OFIELDS	5

#ifdef	USE_NIS

/*
 * __setspNIS - turn on or off NIS searches
 */

void __setspNIS (bool flag)
{
	nis_ignore = !flag;

	if (nis_ignore) {
		nis_used = false;
	}
}

/*
 * bind_nis - bind to NIS server
 */

static int bind_nis (void)
{
	if (yp_get_default_domain (&nis_domain)) {
		return -1;
	}

	nis_bound = true;
	return 0;
}
#endif

/*
 * setspent - initialize access to shadow text and DBM files
 */

void setspent (void)
{
	if (NULL != shadow) {
		rewind (shadow);
	}else {
		shadow = fopen (SHADOW_FILE, "r");
	}

#ifdef	USE_NIS
	nis_state = native;
#endif
}

/*
 * endspent - terminate access to shadow text and DBM files
 */

void endspent (void)
{
	if (NULL != shadow) {
		(void) fclose (shadow);
	}

	shadow = (FILE *) 0;
}

/*
 * my_sgetspent - convert string in shadow file format to (struct spwd *)
 */

static struct spwd *my_sgetspent (const char *string)
{
	static char spwbuf[BUFSIZ];
	static struct spwd spwd;
	char *fields[FIELDS];
	char *cp;
	int i;

	/*
	 * Copy string to local buffer.  It has to be tokenized and we
	 * have to do that to our private copy.
	 */

	if (strlen (string) >= sizeof spwbuf)
		return 0;
	strcpy (spwbuf, string);

	cp = strrchr (spwbuf, '\n');
	if (NULL != cp)
		*cp = '\0';

	/*
	 * Tokenize the string into colon separated fields.  Allow up to
	 * FIELDS different fields.
	 */

	for (cp = spwbuf, i = 0; *cp && i < FIELDS; i++) {
		fields[i] = cp;
		while (*cp && *cp != ':')
			cp++;

		if (*cp)
			*cp++ = '\0';
	}

	if (i == (FIELDS - 1))
		fields[i++] = cp;

	if ((cp && *cp) || (i != FIELDS && i != OFIELDS))
		return 0;

	/*
	 * Start populating the structure.  The fields are all in
	 * static storage, as is the structure we pass back.  If we
	 * ever see a name with '+' as the first character, we try
	 * to turn on NIS processing.
	 */

	spwd.sp_namp = fields[0];
#ifdef	USE_NIS
	if (IS_NISCHAR (fields[0][0])) {
		nis_used = true;
	}
#endif
	spwd.sp_pwdp = fields[1];

	/*
	 * Get the last changed date.  For all of the integer fields,
	 * we check for proper format.  It is an error to have an
	 * incorrectly formatted number, unless we are using NIS.
	 */

	if (fields[2][0] == '\0') {
		spwd.sp_lstchg = -1;
	} else {
		if (getlong (fields[2], &spwd.sp_lstchg) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_lstchg = -1;
			} else
#endif
				return 0;
		} else if (spwd.sp_lstchg < 0) {
			return 0;
		}
	}

	/*
	 * Get the minimum period between password changes.
	 */

	if (fields[3][0] == '\0') {
		spwd.sp_min = -1;
	} else {
		if (getlong (fields[3], &spwd.sp_min) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_min = -1;
			} else
#endif
			{
				return 0;
			}
		} else if (spwd.sp_min < 0) {
			return 0;
		}
	}

	/*
	 * Get the maximum number of days a password is valid.
	 */

	if (fields[4][0] == '\0') {
		spwd.sp_max = -1;
	} else {
		if (getlong (fields[4], &spwd.sp_max) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_max = -1;
			} else
#endif
				return 0;
		} else if (spwd.sp_max < 0) {
			return 0;
		}
	}

	/*
	 * If there are only OFIELDS fields (this is a SVR3.2 /etc/shadow
	 * formatted file), initialize the other field members to -1.
	 */

	if (i == OFIELDS) {
		spwd.sp_warn   = -1;
		spwd.sp_inact  = -1;
		spwd.sp_expire = -1;
		spwd.sp_flag   = SHADOW_SP_FLAG_UNSET;

		return &spwd;
	}

	/*
	 * Get the number of days of password expiry warning.
	 */

	if (fields[5][0] == '\0') {
		spwd.sp_warn = -1;
	} else {
		if (getlong (fields[5], &spwd.sp_warn) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_warn = -1;
			} else
#endif
			{
				return 0;
			}
		} else if (spwd.sp_warn < 0) {
			return 0;
		}
	}

	/*
	 * Get the number of days of inactivity before an account is
	 * disabled.
	 */

	if (fields[6][0] == '\0') {
		spwd.sp_inact = -1;
	} else {
		if (getlong (fields[6], &spwd.sp_inact) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_inact = -1;
			} else
#endif
			{
				return 0;
			}
		} else if (spwd.sp_inact < 0) {
			return 0;
		}
	}

	/*
	 * Get the number of days after the epoch before the account is
	 * set to expire.
	 */

	if (fields[7][0] == '\0') {
		spwd.sp_expire = -1;
	} else {
		if (getlong (fields[7], &spwd.sp_expire) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_expire = -1;
			} else
#endif
			{
				return 0;
			}
		} else if (spwd.sp_expire < 0) {
			return 0;
		}
	}

	/*
	 * This field is reserved for future use.  But it isn't supposed
	 * to have anything other than a valid integer in it.
	 */

	if (fields[8][0] == '\0') {
		spwd.sp_flag = SHADOW_SP_FLAG_UNSET;
	} else {
		if (getulong (fields[8], &spwd.sp_flag) == 0) {
#ifdef	USE_NIS
			if (nis_used) {
				spwd.sp_flag = SHADOW_SP_FLAG_UNSET;
			} else
#endif
			{
				return 0;
			}
		} else if (spwd.sp_flag < 0) {
			return 0;
		}
	}

	return (&spwd);
}

/*
 * fgetspent - get an entry from a /etc/shadow formatted stream
 */

struct spwd *fgetspent (FILE * fp)
{
	char buf[BUFSIZ];
	char *cp;

	if (NULL == fp) {
		return (0);
	}

#ifdef	USE_NIS
	while (fgets (buf, (int) sizeof buf, fp) != (char *) 0)
#else
	if (fgets (buf, (int) sizeof buf, fp) != (char *) 0)
#endif
	{
		cp = strchr (buf, '\n');
		if (NULL != cp) {
			*cp = '\0';
		}
#ifdef	USE_NIS
		if (nis_ignore && IS_NISCHAR (buf[0])) {
			continue;
		}
#endif
		return my_sgetspent (buf);
	}
	return 0;
}

/*
 * getspent - get a (struct spwd *) from the current shadow file
 */

struct spwd *getspent (void)
{
#ifdef	USE_NIS
	int nis_1_user = 0;
	struct spwd *val;
#endif
	if (NULL == shadow) {
		setspent ();
	}

#ifdef	USE_NIS
      again:
	/*
	 * See if we are reading from the local file.
	 */

	if (nis_state == native || nis_state == native2) {

		/*
		 * Get the next entry from the shadow file.  Return NULL
		 * right away if there is none.
		 */

		val = fgetspent (shadow);
		if (NULL == val)
			return 0;

		/*
		 * If this entry began with a NIS escape character, we have
		 * to see if this is just a single user, or if the entire
		 * map is being asked for.
		 */

		if (IS_NISCHAR (val->sp_namp[0])) {
			if (val->sp_namp[1])
				nis_1_user = 1;
			else
				nis_state = start;
		}

		/*
		 * If this isn't a NIS user and this isn't an escape to go
		 * use a NIS map, it must be a regular local user.
		 */

		if (nis_1_user == 0 && nis_state != start)
			return val;

		/*
		 * If this is an escape to use an NIS map, switch over to
		 * that bunch of code.
		 */

		if (nis_state == start)
			goto again;

		/*
		 * NEEDSWORK.  Here we substitute pieces-parts of this entry.
		 */

		return 0;
	} else {
		if (!nis_bound) {
			if (bind_nis ()) {
				nis_state = native2;
				goto again;
			}
		}
		if (nis_state == start) {
			if (yp_first (nis_domain, "shadow.bynam", &nis_key,
			              &nis_keylen, &nis_val, &nis_vallen)) {
				nis_state = native2;
				goto again;
			}
			nis_state = middle;
		} else if (nis_state == middle) {
			if (yp_next (nis_domain, "shadow.bynam", nis_key,
			             nis_keylen, &nis_key, &nis_keylen,
			             &nis_val, &nis_vallen)) {
				nis_state = native2;
				goto again;
			}
		}
		return my_sgetspent (nis_val);
	}
#else
	return (fgetspent (shadow));
#endif
}

/*
 * getspnam - get a shadow entry by name
 */

struct spwd *getspnam (const char *name)
{
	struct spwd *sp;

#ifdef	USE_NIS
	static char save_name[16];
	bool nis_disabled = false;
#endif

	setspent ();

#ifdef	USE_NIS
	/*
	 * Search the shadow.byname map for this user.
	 */

	if (!nis_ignore && !nis_bound) {
		bind_nis ();
	}

	if (!nis_ignore && nis_bound) {
		char *cp;

		if (yp_match (nis_domain, "shadow.byname", name,
		              strlen (name), &nis_val, &nis_vallen) == 0) {

			cp = strchr (nis_val, '\n');
			if (NULL != cp) {
				*cp = '\0';
			}

			nis_state = middle;
			sp = my_sgetspent (nis_val);
			if (NULL != sp) {
				strcpy (save_name, sp->sp_namp);
				nis_key = save_name;
				nis_keylen = strlen (save_name);
			}
			endspent ();
			return sp;
		} else {
			nis_state = native2;
		}
	}
#endif
#ifdef	USE_NIS
	/*
	 * NEEDSWORK -- this is a mess, and it is the same mess in the
	 * other three files.  I can't just blindly turn off NIS because
	 * this might be the first pass through the local files.  In
	 * that case, I never discover that NIS is present.
	 */

	if (nis_used) {
		nis_ignore = true;
		nis_disabled = true;
	}
#endif
	while ((sp = getspent ()) != (struct spwd *) 0) {
		if (strcmp (name, sp->sp_namp) == 0) {
			break;
		}
	}
#ifdef	USE_NIS
	if (nis_disabled) {
		nis_ignore = false;
	}
#endif
	endspent ();
	return (sp);
}
#else
extern int errno;		/* warning: ANSI C forbids an empty source file */
#endif