pam_modules/unix_auth/unix_auth.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */


#include <stdlib.h>
#include <pwd.h>
#include <shadow.h>
#include <syslog.h>
#include <errno.h>
#include <string.h>
#include <crypt.h>
#include <unistd.h>
#include <user_attr.h>
#include <auth_attr.h>
#include <userdefs.h>
#include <deflt.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <stdarg.h>

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_impl.h>

#include <libintl.h>

#include <passwdutil.h>

#define LOGINADMIN  "/etc/default/login"
#define MAXTRYS     5

/*PRINTFLIKE2*/
void
error(pam_handle_t *pamh, char *fmt, ...)
{
    va_list ap;
    char messages[1][PAM_MAX_MSG_SIZE];

    va_start(ap, fmt);
    (void) vsnprintf(messages[0], sizeof (messages[0]), fmt, ap);
    (void) __pam_display_msg(pamh, PAM_ERROR_MSG, 1, messages, NULL);
    va_end(ap);
}

static int
get_max_failed(char *user)
{
    char *val = NULL;
    userattr_t *uattr;
    int do_lock = 0;
    int retval = 0;
    char *p;
    void    *defp;

    if ((uattr = getusernam(user)) != NULL)
        val = kva_match(uattr->attr, USERATTR_LOCK_AFTER_RETRIES_KW);

    if (val != NULL) {
        do_lock = (strcasecmp(val, "yes") == 0);
    } else if ((defp = defopen_r(AUTH_POLICY)) != NULL) {
        int flags;
        flags = defcntl_r(DC_GETFLAGS, 0, defp);
        TURNOFF(flags, DC_CASE);
        (void) defcntl_r(DC_SETFLAGS, flags, defp);
        if ((p = defread_r("LOCK_AFTER_RETRIES=", defp)) != NULL)
            do_lock = (strcasecmp(p, "yes") == 0);
        defclose_r(defp);
    }

    if (uattr != NULL)
        free_userattr(uattr);

    if (do_lock) {
        retval = MAXTRYS;
        if ((defp = defopen_r(LOGINADMIN)) != NULL) {
            if ((p = defread_r("RETRIES=", defp)) != NULL)
                retval = atoi(p);
            defclose_r(defp);
        }
    }

    return (retval);
}

static void
display_warning(pam_handle_t *pamh, int failures, char *homedir)
{
    char hushpath[MAXPATHLEN];
    struct stat buf;

    (void) snprintf(hushpath, sizeof (hushpath), "%s/.hushlogin", homedir);
    if (stat(hushpath, &buf) == 0)
        return;

    if (failures == 1)
        error(pamh, "Warning: 1 failed login attempt since last "
            "successful login.");
    else if (failures < FAILCOUNT_MASK)
        error(pamh, "Warning: %d failed login attempts since last "
            "successful login.", failures);
    else
        error(pamh, "Warning: at least %d failed login attempts since "
            "last successful login.", failures);
}

/*
 * int pam_sm_authenticate(pamh, flags, arc, argv)
 *
 * This routine verifies that the password as stored in the
 * PAM_AUTHTOK item is indeed the password that belongs to the user
 * as stored in PAM_USER.
 *
 * This routine will not establish Secure RPC Credentials, the pam_dhkeys
 * module should be stacked before us if Secure RPC Credentials are needed
 * to obtain passwords.
 */
int
pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
    int i;
    int debug = 0;
    int nowarn = (flags & PAM_SILENT) != 0;
    char    *user;
    char    *passwd;
    char    *rep_passwd;
    char    *crypt_passwd;
    char    *repository_name;
    struct pam_repository *auth_rep;
    pwu_repository_t *pwu_rep;
    attrlist attr_pw[4];
    int result;
    int server_policy = 0;
    int old_failed_count;
    char    *homedir = NULL;
    int dolock = 1;

    for (i = 0; i < argc; i++) {
        if (strcmp(argv[i], "debug") == 0)
            debug = 1;
        else if (strcmp(argv[i], "nowarn") == 0)
            nowarn = 1;
        else if (strcmp(argv[i], "server_policy") == 0)
            server_policy = 1;
        else if (strcmp(argv[i], "nolock") == 0)
            dolock = 0;
    }

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_unix_auth: entering pam_sm_authenticate()");

    if (pam_get_item(pamh, PAM_USER, (void **)&user) != PAM_SUCCESS) {
        __pam_log(LOG_AUTH | LOG_DEBUG, "pam_unix_auth: USER not set");
        return (PAM_SYSTEM_ERR);
    }

    if (user == NULL || *user == '\0') {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_unix_auth: USER NULL or empty!\n");
        return (PAM_USER_UNKNOWN);
    }

    if (pam_get_item(pamh, PAM_AUTHTOK, (void **)&passwd) != PAM_SUCCESS) {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_unix_auth: AUTHTOK not set!\n");
        return (PAM_SYSTEM_ERR);
    }

    result = pam_get_item(pamh, PAM_REPOSITORY, (void **)&auth_rep);
    if (result == PAM_SUCCESS && auth_rep != NULL) {
        if ((pwu_rep = calloc(1, sizeof (*pwu_rep))) == NULL)
            return (PAM_BUF_ERR);
        pwu_rep->type = auth_rep->type;
        pwu_rep->scope = auth_rep->scope;
        pwu_rep->scope_len = auth_rep->scope_len;
    } else {
        pwu_rep = PWU_DEFAULT_REP;
    }

    /*
     * Get password and the name of the repository where the
     * password resides.
     */
    attr_pw[0].type = ATTR_PASSWD;      attr_pw[0].next = &attr_pw[1];
    attr_pw[1].type = ATTR_REP_NAME;    attr_pw[1].next = &attr_pw[2];
    /*
     * Also get the current number of failed logins; we use
     * this later to determine whether we need to reset the count
     * on a succesful authentication. We use the home-directory
     * to look for .hushlogin in order to optionaly surpress the
     * "failed attempts" message.
     */
    attr_pw[2].type = ATTR_FAILED_LOGINS;   attr_pw[2].next = &attr_pw[3];
    attr_pw[3].type = ATTR_HOMEDIR;     attr_pw[3].next = NULL;

    result = __get_authtoken_attr(user, pwu_rep, attr_pw);

    if (pwu_rep != PWU_DEFAULT_REP)
        free(pwu_rep);

    if (result == PWU_NOT_FOUND) {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_unix_auth: user %s not found\n", user);
        return (PAM_USER_UNKNOWN);
    }

    if (result == PWU_DENIED) {
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "pam_unix_auth: failed to obtain attributes");
        return (PAM_PERM_DENIED);
    }

    if (result != PWU_SUCCESS)
        return (PAM_SYSTEM_ERR);

    rep_passwd = attr_pw[0].data.val_s;
    repository_name = attr_pw[1].data.val_s;
    old_failed_count = attr_pw[2].data.val_i;
    homedir = attr_pw[3].data.val_s;

    /*
     * Chop off old SunOS-style password aging information.
     *
     * Note: old style password aging is only defined for UNIX-style
     *   crypt strings, hence the comma will always be at position 14.
     * Note: This code is here because some other vendors might still
     *   support this style of password aging. If we don't remove
     *   the age field, no one will be able to login.
     * XXX   yank this code when we're certain this "compatibility"
     *   isn't needed anymore.
     */
    if (rep_passwd != NULL && rep_passwd[0] != '$' &&
        strlen(rep_passwd) > 13 && rep_passwd[13] == ',')
        rep_passwd[13] = '\0';

    /* Is a password check required? */
    if (rep_passwd == NULL || *rep_passwd == '\0') {
        if (flags & PAM_DISALLOW_NULL_AUTHTOK) {
            result = PAM_AUTH_ERR;
            __pam_log(LOG_AUTH | LOG_NOTICE,
                "pam_unix_auth: empty password for %s not allowed.",
                user);
            goto out;
        } else {
            result = PAM_SUCCESS;
            goto out;
        }
    }

    /*
     * Password check *is* required. Make sure we have a valid
     * pointer in PAM_AUTHTOK
     */
    if (passwd == NULL) {
        result = PAM_AUTH_ERR;
        goto out;
    }

    if (server_policy &&
        strcmp(repository_name, "files") != 0 &&
        strcmp(repository_name, "nis") != 0) {
        result = PAM_IGNORE;
        goto out;
    }

    /* Now check the entered password */
    if ((crypt_passwd = crypt(passwd, rep_passwd)) == NULL) {
        switch (errno) {
        case ENOMEM:
            result = PAM_BUF_ERR;
            break;
        case ELIBACC:
            result = PAM_OPEN_ERR;
            break;
        default:
            result = PAM_SYSTEM_ERR;
        }
        goto out;
    }

    if (strcmp(crypt_passwd, rep_passwd) == 0)
        result = PAM_SUCCESS;
    else
        result = PAM_AUTH_ERR;

    /* Clear or increment failed failed count */
    if (dolock && (result == PAM_SUCCESS && old_failed_count > 0)) {
        old_failed_count = __rst_failed_count(user, repository_name);
        if (nowarn == 0 && old_failed_count > 0)
            display_warning(pamh, old_failed_count, homedir);
    } else if (dolock && result == PAM_AUTH_ERR) {
        int max_failed = get_max_failed(user);
        if (max_failed != 0) {
            if (__incr_failed_count(user, repository_name,
                max_failed) == PWU_ACCOUNT_LOCKED)
                result = PAM_MAXTRIES;
        }
    }
out:
    if (rep_passwd)
        free(rep_passwd);
    if (repository_name)
        free(repository_name);
    if (homedir)
        free(homedir);
    return (result);
}

/*ARGSUSED*/
int
pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
    return (PAM_IGNORE);
}