rlm_pam.c

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/*
 *   This program is 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
 */
 
/**
 * $Id: f10826c607fd4f50093476e1d696b611a844ccc4 $
 * @file rlm_pam.c
 * @brief Interfaces with the PAM library to allow auth via PAM.
 *
 * @note This was taken from the hacks that miguel a.l. paraz <map@iphil.net>
 *      did on radiusd-cistron-1.5.3 and migrated to a separate file.
 *      That, in fact, was again based on the original stuff from
 *      Jeph Blaize <jblaize@kiva.net> done in May 1997.
 *
 * @copyright 2000,2006 The FreeRADIUS server project
 * @copyright 1997 Jeph Blaize (jblaize@kiva.net)
 * @copyright 1999 miguel a.l. paraz (map@iphil.net)
 */
RCSID("$Id: f10826c607fd4f50093476e1d696b611a844ccc4 $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/module_rlm.h>
 
#include "config.h"
 
#ifdef HAVE_SECURITY_PAM_APPL_H
#  include <security/pam_appl.h>
#endif
 
#ifdef HAVE_PAM_PAM_APPL_H
#  include <pam/pam_appl.h>
#endif
 
#ifdef HAVE_SYSLOG_H
#  include <syslog.h>
#endif
 
typedef struct {
        char const *pam_auth_name;
} rlm_pam_t;
 
typedef struct {
        request_t               *request;       //!< The current request.
        char const      *username;      //!< Username to provide to PAM when prompted.
        char const      *password;      //!< Password to provide to PAM when prompted.
        bool            error;          //!< True if pam_conv failed.
} rlm_pam_data_t;
 
static const conf_parser_t module_config[] = {
        { FR_CONF_OFFSET("pam_auth", rlm_pam_t, pam_auth_name) },
        CONF_PARSER_TERMINATOR
};
 
static fr_dict_t const *dict_freeradius;
static fr_dict_t const *dict_radius;
 
extern fr_dict_autoload_t rlm_pam_dict[];
fr_dict_autoload_t rlm_pam_dict[] = {
        { .out = &dict_freeradius, .proto = "freeradius" },
        { .out = &dict_radius, .proto = "radius" },
        { NULL }
};
 
static fr_dict_attr_t const *attr_pam_auth;
static fr_dict_attr_t const *attr_user_name;
static fr_dict_attr_t const *attr_user_password;
 
extern fr_dict_attr_autoload_t rlm_pam_dict_attr[];
fr_dict_attr_autoload_t rlm_pam_dict_attr[] = {
        { .out = &attr_pam_auth, .name = "Pam-Auth", .type = FR_TYPE_STRING, .dict = &dict_freeradius },
        { .out = &attr_user_name, .name = "User-Name", .type = FR_TYPE_STRING, .dict = &dict_radius },
        { .out = &attr_user_password, .name = "User-Password", .type = FR_TYPE_STRING, .dict = &dict_radius },
        { NULL }
};
 
static int mod_instantiate(module_inst_ctx_t const *mctx)
{
        rlm_pam_t *inst = talloc_get_type_abort(mctx->inst->data, rlm_pam_t);
 
        if (!inst->pam_auth_name) inst->pam_auth_name = main_config->name;
 
        return 0;
}
 
/** Dialogue between RADIUS and PAM modules
 *
 * Uses PAM's appdata_ptr so it's thread safe, and doesn't
 * have any nasty static variables hanging around.
 */
static int pam_conv(int num_msg, struct pam_message const **msg, struct pam_response **resp, void *appdata_ptr)
{
        int             count;
        struct          pam_response *reply;
        request_t               *request;
        rlm_pam_data_t  *pam_config = (rlm_pam_data_t *) appdata_ptr;
 
        request = pam_config->request;
 
#define COPY_STRING(s) ((s) ? talloc_strdup(reply, s) : NULL)
        MEM(reply = talloc_zero_array(NULL, struct pam_response, num_msg));
        for (count = 0; count < num_msg; count++) {
                switch (msg[count]->msg_style) {
                case PAM_PROMPT_ECHO_ON:
                        reply[count].resp_retcode = PAM_SUCCESS;
                        reply[count].resp = COPY_STRING(pam_config->username);
                        break;
 
                case PAM_PROMPT_ECHO_OFF:
                        reply[count].resp_retcode = PAM_SUCCESS;
                        reply[count].resp = COPY_STRING(pam_config->password);
                        break;
 
                case PAM_TEXT_INFO:
                        RDEBUG2("%s", msg[count]->msg);
                        break;
 
                case PAM_ERROR_MSG:
                default:
                        RERROR("PAM conversation failed");
                        /* Must be an error of some sort... */
                        for (count = 0; count < num_msg; count++) {
                                if (msg[count]->msg_style == PAM_ERROR_MSG) RERROR("%s", msg[count]->msg);
                                if (reply[count].resp) {
                                        /* could be a password, let's be sanitary */
                                        memset(reply[count].resp, 0, strlen(reply[count].resp));
                                }
                        }
                        talloc_free(reply);
                        pam_config->error = true;
                        return PAM_CONV_ERR;
                }
        }
        *resp = reply;
        /* PAM frees reply (including reply[].resp) */
 
        return PAM_SUCCESS;
}
 
/** Check the users password against the standard UNIX password table + PAM.
 *
 * @note For most flexibility, passing a pamauth type to this function
 *       allows you to have multiple authentication types (i.e. multiple
 *       files associated with radius in /etc/pam.d).
 *
 * @param request The current request.
 * @param username User to authenticate.
 * @param passwd Password to authenticate with,
 * @param pamauth Type of PAM authentication.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
static int do_pam(request_t *request, char const *username, char const *passwd, char const *pamauth)
{
        pam_handle_t *handle = NULL;
        int ret;
        rlm_pam_data_t pam_config;
        struct pam_conv conv;
 
        /*
         *  Initialize the structures
         */
        conv.conv = pam_conv;
        conv.appdata_ptr = &pam_config;
        pam_config.request = request;
        pam_config.username = username;
        pam_config.password = passwd;
        pam_config.error = false;
 
        RDEBUG2("Using pamauth string \"%s\" for pam.conf lookup", pamauth);
 
        ret = pam_start(pamauth, username, &conv, &handle);
        if (ret != PAM_SUCCESS) {
                RERROR("pam_start failed: %s", pam_strerror(handle, ret));
                return -1;
        }
 
        ret = pam_authenticate(handle, 0);
        if (ret != PAM_SUCCESS) {
                RERROR("pam_authenticate failed: %s", pam_strerror(handle, ret));
                pam_end(handle, ret);
                return -1;
        }
 
        /*
         *      FreeBSD 3.x doesn't have account and session management
         *      functions in PAM, while 4.0 does.
         */
#if !defined(__FreeBSD_version) || (__FreeBSD_version >= 400000)
        ret = pam_acct_mgmt(handle, 0);
        if (ret != PAM_SUCCESS) {
                RERROR("pam_acct_mgmt failed: %s", pam_strerror(handle, ret));
                pam_end(handle, ret);
                return -1;
        }
#endif
        RDEBUG2("Authentication succeeded");
        pam_end(handle, ret);
        return 0;
}
 
static unlang_action_t CC_HINT(nonnull) mod_authenticate(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_pam_t const         *data = talloc_get_type_abort_const(mctx->inst->data, rlm_pam_t);
        int                     ret;
        fr_pair_t               *pair;
 
        char const              *pam_auth_string = data->pam_auth_name;
        fr_pair_t               *username, *password;
 
        username = fr_pair_find_by_da(&request->request_pairs, NULL, attr_user_name);
        password = fr_pair_find_by_da(&request->request_pairs, NULL, attr_user_password);
 
        /*
         *      We can only authenticate user requests which HAVE
         *      a User-Name attribute.
         */
        if (!username) {
                REDEBUG("Attribute \"User-Name\" is required for authentication");
                RETURN_MODULE_INVALID;
        }
 
        if (!password) {
                REDEBUG("Attribute \"User-Password\" is required for authentication");
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      Make sure the supplied password isn't empty
         */
        if (password->vp_length == 0) {
                REDEBUG("User-Password must not be empty");
                RETURN_MODULE_INVALID;
        }
 
        /*
         *      Log the password
         */
        if (RDEBUG_ENABLED3) {
                RDEBUG("Login attempt with password \"%pV\"", &password->data);
        } else {
                RDEBUG2("Login attempt with password");
        }
 
        /*
         *      Let control list over-ride the PAM auth name string,
         *      for backwards compatibility.
         */
        pair = fr_pair_find_by_da(&request->control_pairs, NULL, attr_pam_auth);
        if (pair) pam_auth_string = pair->vp_strvalue;
 
        ret = do_pam(request, username->vp_strvalue, password->vp_strvalue, pam_auth_string);
        if (ret < 0) RETURN_MODULE_REJECT;
 
        RETURN_MODULE_OK;
}
 
extern module_rlm_t rlm_pam;
module_rlm_t rlm_pam = {
        .common = {
                .magic          = MODULE_MAGIC_INIT,
                .name           = "pam",
                .flags          = MODULE_TYPE_THREAD_UNSAFE,    /* The PAM libraries are not thread-safe */
                .inst_size      = sizeof(rlm_pam_t),
                .config         = module_config,
                .instantiate    = mod_instantiate
        },
        .method_names = (module_method_name_t[]){
                { .name1 = "authenticate",      .name2 = CF_IDENT_ANY,          .method = mod_authenticate },
                MODULE_NAME_TERMINATOR
        }
};