Cppcheck report - cafe-screensaver (cppcheck 2.14.0-1+b1): src/gs-auth-pwent.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
 *
 * Copyright (c) 1993-1998 Jamie Zawinski <jwz@jwz.org>
 * Copyright (C) 2006 William Jon McCann <mccann@jhu.edu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 */

#include "config.h"

#include <stdlib.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif

#ifdef HAVE_CRYPT_H
# include <crypt.h>
#endif

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>

#ifdef __bsdi__
# include <sys/param.h>
# if _BSDI_VERSION >= 199608
#  define BSD_AUTH
# endif
#endif /* __bsdi__ */

#include <glib.h>
#include <glib/gi18n.h>

#if defined(HAVE_SHADOW_PASSWD)	      /* passwds live in /etc/shadow */

#   include <shadow.h>
#   define PWTYPE   struct spwd *
#   define PWPSLOT  sp_pwdp
#   define GETPW    getspnam

#elif defined(HAVE_ENHANCED_PASSWD)      /* passwds live in /tcb/files/auth/ */
/* M.Matsumoto <matsu@yao.sharp.co.jp> */
#   include <sys/security.h>
#   include <prot.h>

#   define PWTYPE   struct pr_passwd *
#   define PWPSLOT  ufld.fd_encrypt
#   define GETPW    getprpwnam

#elif defined(HAVE_ADJUNCT_PASSWD)

#   include <sys/label.h>
#   include <sys/audit.h>
#   include <pwdadj.h>

#   define PWTYPE   struct passwd_adjunct *
#   define PWPSLOT  pwa_passwd
#   define GETPW    getpwanam

#elif defined(HAVE_HPUX_PASSWD)

#   include <hpsecurity.h>
#   include <prot.h>

#   define PWTYPE   struct s_passwd *
#   define PWPSLOT  pw_passwd
#   define GETPW    getspwnam

#   define HAVE_BIGCRYPT

#endif

#include "gs-auth.h"

static gboolean verbose_enabled = FALSE;

static char *encrypted_user_passwd = NULL;

GQuark
gs_auth_error_quark (void)
{
	static GQuark quark = 0;
	if (! quark)
	{
		quark = g_quark_from_static_string ("gs_auth_error");
	}

	return quark;
}

void
gs_auth_set_verbose (gboolean enabled)
{
	verbose_enabled = enabled;
}

gboolean
gs_auth_get_verbose (void)
{
	return verbose_enabled;
}

static gboolean
passwd_known (const char *pw)
{
	return (pw &&
	        pw[0] != '*' &&	/* This would be sensible...         */
	        strlen (pw) > 4);	/* ...but this is what Solaris does. */
}

static char *
get_encrypted_passwd (const char *user)
{
	char *result = NULL;

#ifdef PWTYPE
	if (user && *user && !result)
	{
		/* First check the shadow passwords. */
		PWTYPE p = GETPW ((char *) user);
		if (p && passwd_known (p->PWPSLOT))
		{
			result = g_strdup (p->PWPSLOT);
		}
	}
#endif /* PWTYPE */

	if (user && *user && !result)
	{
		/* Check non-shadow passwords too. */
		struct passwd *p = getpwnam (user);
		if (p && passwd_known (p->pw_passwd))
		{
			result = g_strdup (p->pw_passwd);
		}
	}

	/* The manual for passwd(4) on HPUX 10.10 says:

	Password aging is put in effect for a particular user if his
	encrypted password in the password file is followed by a comma and
	a nonnull string of characters from the above alphabet.  This
	string defines the "age" needed to implement password aging.

	So this means that passwd->pw_passwd isn't simply a string of cyphertext,
	it might have trailing junk.  So, if there is a comma in the string, and
	that comma is beyond position 13, terminate the string before the comma.
	*/
	if (result && strlen (result) > 13)
	{
		char *s = strchr (result + 13, ',');
		if (s)
		{
			*s = 0;
		}
	}

#if !defined(HAVE_PAM) && !defined(HAVE_BSDAUTH)
	/* We only issue this warning if not compiled with support for PAM,
	   or bsd_auth(3). If we're using PAM, it's not unheard of that
	   normal pwent passwords would be unavailable. */

	if (!result)
	{
		g_warning ("Couldn't get password of \"%s\"",
		           (user ? user : "(null)"));
	}

#endif /* !HAVE_PAM */

	return result;
}

/* This has to be called before we've changed our effective user ID,
   because it might need privileges to get at the encrypted passwords.
   Returns false if we weren't able to get any passwords, and therefore,
   locking isn't possible.  (It will also have written to stderr.)
*/

gboolean
gs_auth_priv_init (void)
{
	const char *u;

	u = g_get_user_name ();

	encrypted_user_passwd = get_encrypted_passwd (u);

	if (encrypted_user_passwd != NULL)
	{
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}


gboolean
gs_auth_init (void)
{
	if (encrypted_user_passwd != NULL)
	{
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}

static gboolean
passwds_match (const char *cleartext,
               const char *ciphertext)
{
	char *s = NULL;  /* note that on some systems, crypt() may return null */<--- Variable 's' can be declared as pointer to const

	s = (char *) crypt (cleartext, ciphertext);
	if (s && !strcmp (s, ciphertext))
	{
		return TRUE;
	}

#ifdef HAVE_BIGCRYPT
	/* There seems to be no way to tell at runtime if an HP machine is in
	   "trusted" mode, and thereby, which of crypt() or bigcrypt() we should
	   be calling to compare passwords.  So call them both, and see which
	   one works. */

	s = (char *) bigcrypt (cleartext, ciphertext);
	if (s && !strcmp (s, ciphertext))
	{
		return TRUE;
	}

#endif /* HAVE_BIGCRYPT */

	return FALSE;
}

gboolean
gs_auth_verify_user (const char       *username,
                     const char       *display,
                     GSAuthMessageFunc func,
                     gpointer          data,
                     GError          **error)
{
	char *password;

	password = NULL;

	/* ask for the password for user */
	if (func != NULL)
	{
		func (GS_AUTH_MESSAGE_PROMPT_ECHO_OFF,
		      "Password: ",
		      &password,
		      data);
	}

	if (password == NULL)
	{
		return FALSE;
	}

	if (encrypted_user_passwd && passwds_match (password, encrypted_user_passwd))
	{
		return TRUE;
	}
	else
	{
		return FALSE;
	}
}