sudo/plugins/sudoers/auth/sudo_auth.c

/*
 * Copyright (c) 1999-2005, 2008-2013 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Sponsored in part by the Defense Advanced Research Projects
 * Agency (DARPA) and Air Force Research Laboratory, Air Force
 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
 */

#include <config.h>

#include <sys/types.h>
#include <stdio.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <stddef.h>
#else
# ifdef HAVE_STDLIB_H
#  include <stdlib.h>
# endif
#endif /* STDC_HEADERS */
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include <pwd.h>
#include <time.h>
#include <signal.h>

#include "sudoers.h"
#include "sudo_auth.h"
#include "insults.h"

static sudo_auth auth_switch[] = {
/* Standalone entries first */
#ifdef HAVE_PAM
    AUTH_ENTRY("pam", FLAG_STANDALONE, sudo_pam_init, NULL, sudo_pam_verify, sudo_pam_cleanup, sudo_pam_begin_session, sudo_pam_end_session)
#endif
#ifdef HAVE_SECURID
    AUTH_ENTRY("SecurId", FLAG_STANDALONE, sudo_securid_init, sudo_securid_setup, sudo_securid_verify, NULL, NULL, NULL)
#endif
#ifdef HAVE_SIA_SES_INIT
    AUTH_ENTRY("sia", FLAG_STANDALONE, NULL, sudo_sia_setup, sudo_sia_verify, sudo_sia_cleanup, NULL, NULL)
#endif
#ifdef HAVE_AIXAUTH
    AUTH_ENTRY("aixauth", FLAG_STANDALONE, NULL, NULL, sudo_aix_verify, sudo_aix_cleanup, NULL, NULL)
#endif
#ifdef HAVE_FWTK
    AUTH_ENTRY("fwtk", FLAG_STANDALONE, sudo_fwtk_init, NULL, sudo_fwtk_verify, sudo_fwtk_cleanup, NULL, NULL)
#endif
#ifdef HAVE_BSD_AUTH_H
    AUTH_ENTRY("bsdauth", FLAG_STANDALONE, bsdauth_init, NULL, bsdauth_verify, bsdauth_cleanup, NULL, NULL)
#endif

/* Non-standalone entries */
#ifndef WITHOUT_PASSWD
    AUTH_ENTRY("passwd", 0, sudo_passwd_init, NULL, sudo_passwd_verify, sudo_passwd_cleanup, NULL, NULL)
#endif
#if defined(HAVE_GETPRPWNAM) && !defined(WITHOUT_PASSWD)
    AUTH_ENTRY("secureware", 0, sudo_secureware_init, NULL, sudo_secureware_verify, sudo_secureware_cleanup, NULL, NULL)
#endif
#ifdef HAVE_AFS
    AUTH_ENTRY("afs", 0, NULL, NULL, sudo_afs_verify, NULL, NULL, NULL)
#endif
#ifdef HAVE_DCE
    AUTH_ENTRY("dce", 0, NULL, NULL, sudo_dce_verify, NULL, NULL, NULL)
#endif
#ifdef HAVE_KERB5
    AUTH_ENTRY("kerb5", 0, sudo_krb5_init, sudo_krb5_setup, sudo_krb5_verify, sudo_krb5_cleanup, NULL, NULL)
#endif
#ifdef HAVE_SKEY
    AUTH_ENTRY("S/Key", 0, NULL, sudo_rfc1938_setup, sudo_rfc1938_verify, NULL, NULL, NULL)
#endif
#ifdef HAVE_OPIE
    AUTH_ENTRY("OPIE", 0, NULL, sudo_rfc1938_setup, sudo_rfc1938_verify, NULL, NULL, NULL)
#endif
    AUTH_ENTRY(NULL, 0, NULL, NULL, NULL, NULL, NULL, NULL)
};

static int standalone;

extern char **NewArgv; /* XXX - for auditing */

static void pass_warn(void);

/*
 * Initialize sudoers authentication method(s).
 * Returns 0 on success and -1 on error.
 */
int
sudo_auth_init(struct passwd *pw)
{
    sudo_auth *auth;
    int status = AUTH_SUCCESS;
    debug_decl(sudo_auth_init, SUDO_DEBUG_AUTH)

    if (auth_switch[0].name == NULL)
	debug_return_int(0);

    /* Make sure we haven't mixed standalone and shared auth methods. */
    standalone = IS_STANDALONE(&auth_switch[0]);
    if (standalone && auth_switch[1].name != NULL) {
	audit_failure(NewArgv, N_("invalid authentication methods"));
    	log_fatal(0, N_("Invalid authentication methods compiled into sudo!  "
	    "You may not mix standalone and non-standalone authentication."));
	debug_return_int(-1);
    }

    /* Set FLAG_ONEANDONLY if there is only one auth method. */
    if (auth_switch[1].name == NULL)
	SET(auth_switch[0].flags, FLAG_ONEANDONLY);

    /* Initialize auth methods and unconfigure the method if necessary. */
    for (auth = auth_switch; auth->name; auth++) {
	if (auth->init && !IS_DISABLED(auth)) {
	    if (NEEDS_USER(auth))
		set_perms(PERM_USER);

	    status = (auth->init)(pw, auth);

	    if (NEEDS_USER(auth))
		restore_perms();

	    /* Disable if it failed to init unless there was a fatal error. */
	    if (status == AUTH_FAILURE)
		SET(auth->flags, FLAG_DISABLED);
	    else if (status == AUTH_FATAL)
		break;		/* assume error msg already printed */
	}
    }
    debug_return_int(status == AUTH_FATAL ? -1 : 0);
}

/*
 * Cleanup all authentication methods.
 * Returns 0 on success and -1 on error.
 */
int
sudo_auth_cleanup(struct passwd *pw)
{
    sudo_auth *auth;
    int status = AUTH_SUCCESS;
    debug_decl(sudo_auth_cleanup, SUDO_DEBUG_AUTH)

    /* Call cleanup routines. */
    for (auth = auth_switch; auth->name; auth++) {
	if (auth->cleanup && !IS_DISABLED(auth)) {
	    if (NEEDS_USER(auth))
		set_perms(PERM_USER);

	    status = (auth->cleanup)(pw, auth);

	    if (NEEDS_USER(auth))
		restore_perms();

	    if (status == AUTH_FATAL)
		break;		/* assume error msg already printed */
	}
    }
    debug_return_int(status == AUTH_FATAL ? -1 : 0);
}

/*
 * Verify the specified user.
 * Returns true if verified, false if not or -1 on error.
 */
int
verify_user(struct passwd *pw, char *prompt, int validated)
{
    int counter = def_passwd_tries + 1;
    int success = AUTH_FAILURE;
    int status, rval;
    char *p;
    sudo_auth *auth;
    sigaction_t sa, osa;
    debug_decl(verify_user, SUDO_DEBUG_AUTH)

    /* Enable suspend during password entry. */
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    sa.sa_handler = SIG_DFL;
    (void) sigaction(SIGTSTP, &sa, &osa);

    /* Make sure we have at least one auth method. */
    /* XXX - check FLAG_DISABLED too */
    if (auth_switch[0].name == NULL) {
	audit_failure(NewArgv, N_("no authentication methods"));
    	log_warning(0,
	    N_("There are no authentication methods compiled into sudo!  "
	    "If you want to turn off authentication, use the "
	    "--disable-authentication configure option."));
	debug_return_int(-1);
    }

    while (--counter) {
	/* Do any per-method setup and unconfigure the method if needed */
	for (auth = auth_switch; auth->name; auth++) {
	    if (auth->setup && !IS_DISABLED(auth)) {
		if (NEEDS_USER(auth))
		    set_perms(PERM_USER);

		status = (auth->setup)(pw, &prompt, auth);

		if (NEEDS_USER(auth))
		    restore_perms();

		if (status == AUTH_FAILURE)
		    SET(auth->flags, FLAG_DISABLED);
		else if (status == AUTH_FATAL)
		    goto done;		/* assume error msg already printed */
	    }
	}

	/* Get the password unless the auth function will do it for us */
	if (standalone) {
	    p = prompt;
	} else {
	    p = auth_getpass(prompt, def_passwd_timeout * 60,
		SUDO_CONV_PROMPT_ECHO_OFF);
	    if (p == NULL)
		break;
	}

	/* Call authentication functions. */
	for (auth = auth_switch; auth->name; auth++) {
	    if (IS_DISABLED(auth))
		continue;

	    if (NEEDS_USER(auth))
		set_perms(PERM_USER);

	    success = auth->status = (auth->verify)(pw, p, auth);

	    if (NEEDS_USER(auth))
		restore_perms();

	    if (auth->status != AUTH_FAILURE)
		goto done;
	}
	if (!standalone)
	    memset_s(p, SUDO_CONV_REPL_MAX, 0, strlen(p));
	pass_warn();
    }

done:
    switch (success) {
	case AUTH_SUCCESS:
	    (void) sigaction(SIGTSTP, &osa, NULL);
	    rval = true;
	    break;
	case AUTH_INTR:
	case AUTH_FAILURE:
	    if (counter != def_passwd_tries)
		validated |= FLAG_BAD_PASSWORD;
	    log_auth_failure(validated, def_passwd_tries - counter);
	    rval = false;
	    break;
	case AUTH_FATAL:
	default:
	    log_auth_failure(validated | FLAG_AUTH_ERROR, 0);
	    rval = -1;
	    break;
    }

    debug_return_int(rval);
}

/*
 * Call authentication method begin session hooks.
 * Returns 1 on success and -1 on error.
 */
int
sudo_auth_begin_session(struct passwd *pw, char **user_env[])
{
    sudo_auth *auth;
    int status = AUTH_SUCCESS;
    debug_decl(sudo_auth_begin_session, SUDO_DEBUG_AUTH)

    for (auth = auth_switch; auth->name; auth++) {
	if (auth->begin_session && !IS_DISABLED(auth)) {
	    status = (auth->begin_session)(pw, user_env, auth);
	    if (status == AUTH_FATAL)
		break;		/* assume error msg already printed */
	}
    }
    debug_return_int(status == AUTH_FATAL ? -1 : 1);
}

bool
sudo_auth_needs_end_session(void)
{
    sudo_auth *auth;
    bool needed = false;
    debug_decl(sudo_auth_needs_end_session, SUDO_DEBUG_AUTH)

    for (auth = auth_switch; auth->name; auth++) {
	if (auth->end_session && !IS_DISABLED(auth)) {
	    needed = true;
	    break;
	}
    }
    debug_return_bool(needed);
}

/*
 * Call authentication method end session hooks.
 * Returns 1 on success and -1 on error.
 */
int
sudo_auth_end_session(struct passwd *pw)
{
    sudo_auth *auth;
    int status = AUTH_SUCCESS;
    debug_decl(sudo_auth_end_session, SUDO_DEBUG_AUTH)

    for (auth = auth_switch; auth->name; auth++) {
	if (auth->end_session && !IS_DISABLED(auth)) {
	    status = (auth->end_session)(pw, auth);
	    if (status == AUTH_FATAL)
		break;			/* assume error msg already printed */
	}
    }
    debug_return_int(status == AUTH_FATAL ? -1 : 1);
}

static void
pass_warn(void)
{
    const char *warning = def_badpass_message;
    debug_decl(pass_warn, SUDO_DEBUG_AUTH)

#ifdef INSULT
    if (def_insults)
	warning = INSULT;
#endif
    sudo_printf(SUDO_CONV_ERROR_MSG, "%s\n", warning);

    debug_return;
}

char *
auth_getpass(const char *prompt, int timeout, int type)
{
    struct sudo_conv_message msg;
    struct sudo_conv_reply repl;
    debug_decl(auth_getpass, SUDO_DEBUG_AUTH)

    /* Mask user input if pwfeedback set and echo is off. */
    if (type == SUDO_CONV_PROMPT_ECHO_OFF && def_pwfeedback)
	type = SUDO_CONV_PROMPT_MASK;

    /* If visiblepw set, do not error out if there is no tty. */
    if (def_visiblepw)
	type |= SUDO_CONV_PROMPT_ECHO_OK;

    /* Call conversation function */
    memset(&msg, 0, sizeof(msg));
    msg.msg_type = type;
    msg.timeout = def_passwd_timeout * 60;
    msg.msg = prompt;
    memset(&repl, 0, sizeof(repl));
    sudo_conv(1, &msg, &repl);
    /* XXX - check for ENOTTY? */
    debug_return_str_masked(repl.reply);
}

void
dump_auth_methods(void)
{
    sudo_auth *auth;
    debug_decl(dump_auth_methods, SUDO_DEBUG_AUTH)

    sudo_printf(SUDO_CONV_INFO_MSG, _("Authentication methods:"));
    for (auth = auth_switch; auth->name; auth++)
	sudo_printf(SUDO_CONV_INFO_MSG, " '%s'", auth->name);
    sudo_printf(SUDO_CONV_INFO_MSG, "\n");

    debug_return;
}