contrib/hostapd/eap_tls_common.c

   1 /*
   2  * hostapd / EAP-TLS/PEAP/TTLS common functions
   3  * Copyright (c) 2004-2006, Jouni Malinen <j@w1.fi>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Alternatively, this software may be distributed under the terms of BSD
  10  * license.
  11  *
  12  * See README and COPYING for more details.
  13  */
  14
  15 #include "includes.h"
  16
  17 #include "hostapd.h"
  18 #include "common.h"
  19 #include "eap_i.h"
  20 #include "eap_tls_common.h"
  21 #include "sha1.h"
  22 #include "tls.h"
  23
  24
  25 int eap_tls_ssl_init(struct eap_sm *sm, struct eap_ssl_data *data,
  26                      int verify_peer)
  27 {
  28         data->eap = sm;
  29         data->phase2 = sm->init_phase2;
  30
  31         data->conn = tls_connection_init(sm->ssl_ctx);
  32         if (data->conn == NULL) {
  33                 wpa_printf(MSG_INFO, "SSL: Failed to initialize new TLS "
  34                            "connection");
  35                 return -1;
  36         }
  37
  38         if (tls_connection_set_verify(sm->ssl_ctx, data->conn, verify_peer)) {
  39                 wpa_printf(MSG_INFO, "SSL: Failed to configure verification "
  40                            "of TLS peer certificate");
  41                 tls_connection_deinit(sm->ssl_ctx, data->conn);
  42                 data->conn = NULL;
  43                 return -1;
  44         }
  45
  46         /* TODO: make this configurable */
  47         data->tls_out_limit = 1398;
  48         if (data->phase2) {
  49                 /* Limit the fragment size in the inner TLS authentication
  50                  * since the outer authentication with EAP-PEAP does not yet
  51                  * support fragmentation */
  52                 if (data->tls_out_limit > 100)
  53                         data->tls_out_limit -= 100;
  54         }
  55         return 0;
  56 }
  57
  58
  59 void eap_tls_ssl_deinit(struct eap_sm *sm, struct eap_ssl_data *data)
  60 {
  61         tls_connection_deinit(sm->ssl_ctx, data->conn);
  62         free(data->tls_in);
  63         free(data->tls_out);
  64 }
  65
  66
  67 u8 * eap_tls_derive_key(struct eap_sm *sm, struct eap_ssl_data *data,
  68                         char *label, size_t len)
  69 {
  70         struct tls_keys keys;
  71         u8 *rnd = NULL, *out;
  72
  73         out = malloc(len);
  74         if (out == NULL)
  75                 return NULL;
  76
  77         if (tls_connection_prf(sm->ssl_ctx, data->conn, label, 0, out, len) ==
  78             0)
  79                 return out;
  80
  81         if (tls_connection_get_keys(sm->ssl_ctx, data->conn, &keys))
  82                 goto fail;
  83
  84         if (keys.client_random == NULL || keys.server_random == NULL ||
  85             keys.master_key == NULL)
  86                 goto fail;
  87
  88         rnd = malloc(keys.client_random_len + keys.server_random_len);
  89         if (rnd == NULL)
  90                 goto fail;
  91         memcpy(rnd, keys.client_random, keys.client_random_len);
  92         memcpy(rnd + keys.client_random_len, keys.server_random,
  93                keys.server_random_len);
  94
  95         if (tls_prf(keys.master_key, keys.master_key_len,
  96                     label, rnd, keys.client_random_len +
  97                     keys.server_random_len, out, len))
  98                 goto fail;
  99
 100         free(rnd);
 101         return out;
 102
 103 fail:
 104         free(out);
 105         free(rnd);
 106         return NULL;
 107 }
 108
 109
 110 int eap_tls_data_reassemble(struct eap_sm *sm, struct eap_ssl_data *data,
 111                             u8 **in_data, size_t *in_len)
 112 {
 113         u8 *buf;
 114
 115         if (data->tls_in_left > *in_len || data->tls_in) {
 116                 if (*in_len == 0) {
 117                         wpa_printf(MSG_INFO, "SSL: Empty fragment when trying "
 118                                    "to reassemble");
 119                         return -1;
 120                 }
 121                 if (data->tls_in_len + *in_len > 65536) {
 122                         /* Limit length to avoid rogue peers from causing large
 123                          * memory allocations. */
 124                         free(data->tls_in);
 125                         data->tls_in = NULL;
 126                         data->tls_in_len = 0;
 127                         wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
 128                                    " over 64 kB)");
 129                         return -1;
 130                 }
 131                 buf = realloc(data->tls_in, data->tls_in_len + *in_len);
 132                 if (buf == NULL) {
 133                         free(data->tls_in);
 134                         data->tls_in = NULL;
 135                         data->tls_in_len = 0;
 136                         wpa_printf(MSG_INFO, "SSL: Could not allocate memory "
 137                                    "for TLS data");
 138                         return -1;
 139                 }
 140                 memcpy(buf + data->tls_in_len, *in_data, *in_len);
 141                 data->tls_in = buf;
 142                 data->tls_in_len += *in_len;
 143                 if (*in_len > data->tls_in_left) {
 144                         wpa_printf(MSG_INFO, "SSL: more data than TLS message "
 145                                    "length indicated");
 146                         data->tls_in_left = 0;
 147                         return -1;
 148                 }
 149                 data->tls_in_left -= *in_len;
 150                 if (data->tls_in_left > 0) {
 151                         wpa_printf(MSG_DEBUG, "SSL: Need %lu bytes more input "
 152                                    "data", (unsigned long) data->tls_in_left);
 153                         return 1;
 154                 }
 155
 156                 *in_data = data->tls_in;
 157                 *in_len = data->tls_in_len;
 158         } else
 159                 data->tls_in_left = 0;
 160
 161         return 0;
 162 }
 163
 164
 165 int eap_tls_process_helper(struct eap_sm *sm, struct eap_ssl_data *data,
 166                            u8 *in_data, size_t in_len)
 167 {
 168         WPA_ASSERT(data->tls_out_len == 0 || in_len == 0);
 169
 170         if (data->tls_out_len == 0) {
 171                 /* No more data to send out - expect to receive more data from
 172                  * the peer. */
 173                 int res = eap_tls_data_reassemble(sm, data, &in_data, &in_len);
 174                 if (res < 0 || res == 1) {
 175                         wpa_printf(MSG_DEBUG, "SSL: data reassembly failed");
 176                         return res;
 177                 }
 178                 /* Full TLS message reassembled - continue handshake processing
 179                  */
 180                 if (data->tls_out) {
 181                         /* This should not happen.. */
 182                         wpa_printf(MSG_INFO, "SSL: eap_tls_process_helper - "
 183                                    "pending tls_out data even though "
 184                                    "tls_out_len = 0");
 185                         free(data->tls_out);
 186                         WPA_ASSERT(data->tls_out == NULL);
 187                 }
 188                 data->tls_out = tls_connection_server_handshake(
 189                         sm->ssl_ctx, data->conn, in_data, in_len,
 190                         &data->tls_out_len);
 191
 192                 /* Clear reassembled input data (if the buffer was needed). */
 193                 data->tls_in_left = data->tls_in_total = data->tls_in_len = 0;
 194                 free(data->tls_in);
 195                 data->tls_in = NULL;
 196         }
 197
 198         if (data->tls_out == NULL) {
 199                 wpa_printf(MSG_DEBUG, "SSL: failed to generate output data");
 200                 data->tls_out_len = 0;
 201                 return -1;
 202         }
 203         if (data->tls_out_len == 0) {
 204                 /* TLS negotiation should now be complete since all other cases
 205                  * needing more that should have been catched above based on
 206                  * the TLS Message Length field. */
 207                 wpa_printf(MSG_DEBUG, "SSL: No data to be sent out");
 208                 free(data->tls_out);
 209                 data->tls_out = NULL;
 210
 211                 if (tls_connection_get_read_alerts(sm->ssl_ctx, data->conn)) {
 212                         wpa_printf(MSG_DEBUG, "SSL: Remote end sent a fatal "
 213                                    "alert - abort handshake");
 214                         return -1;
 215                 }
 216
 217                 return 1;
 218         }
 219
 220         wpa_printf(MSG_DEBUG, "SSL: %lu bytes left to be sent out (of total "
 221                    "%lu bytes)",
 222                    (unsigned long) data->tls_out_len - data->tls_out_pos,
 223                    (unsigned long) data->tls_out_len);
 224
 225         return 0;
 226 }
 227
 228
 229 int eap_tls_buildReq_helper(struct eap_sm *sm, struct eap_ssl_data *data,
 230                             int eap_type, int peap_version, u8 id,
 231                             u8 **out_data, size_t *out_len)
 232 {
 233         size_t len;
 234         u8 *pos, *flags;
 235         struct eap_hdr *req;
 236
 237         *out_len = 0;
 238
 239         req = malloc(sizeof(struct eap_hdr) + 2 + 4 + data->tls_out_limit);
 240         if (req == NULL) {
 241                 *out_data = NULL;
 242                 return -1;
 243         }
 244         req->code = EAP_CODE_REQUEST;
 245         req->identifier = id;
 246         pos = (u8 *) (req + 1);
 247         *pos++ = eap_type;
 248         flags = pos++;
 249         *flags = peap_version;
 250         if (data->tls_out_pos == 0 &&
 251             data->tls_out_len > data->tls_out_limit) {
 252                 *flags |= EAP_TLS_FLAGS_LENGTH_INCLUDED;
 253                 *pos++ = (data->tls_out_len >> 24) & 0xff;
 254                 *pos++ = (data->tls_out_len >> 16) & 0xff;
 255                 *pos++ = (data->tls_out_len >> 8) & 0xff;
 256                 *pos++ = data->tls_out_len & 0xff;
 257         }
 258
 259         len = data->tls_out_len - data->tls_out_pos;
 260         if (len > data->tls_out_limit) {
 261                 *flags |= EAP_TLS_FLAGS_MORE_FRAGMENTS;
 262                 len = data->tls_out_limit;
 263                 wpa_printf(MSG_DEBUG, "SSL: sending %lu bytes, more fragments "
 264                            "will follow", (unsigned long) len);
 265         }
 266         memcpy(pos, &data->tls_out[data->tls_out_pos], len);
 267         data->tls_out_pos += len;
 268         *out_len = (pos - (u8 *) req) + len;
 269         req->length = htons(*out_len);
 270         *out_data = (u8 *) req;
 271
 272         if (!(*flags & EAP_TLS_FLAGS_MORE_FRAGMENTS)) {
 273                 data->tls_out_len = 0;
 274                 data->tls_out_pos = 0;
 275                 free(data->tls_out);
 276                 data->tls_out = NULL;
 277         }
 278
 279         return 0;
 280 }
 281
 282
 283 u8 * eap_tls_build_ack(size_t *reqDataLen, u8 id, int eap_type,
 284                        int peap_version)
 285 {
 286         struct eap_hdr *req;
 287         u8 *pos;
 288
 289         *reqDataLen = sizeof(struct eap_hdr) + 2;
 290         req = malloc(*reqDataLen);
 291         if (req == NULL)
 292                 return NULL;
 293         wpa_printf(MSG_DEBUG, "SSL: Building ACK");
 294         req->code = EAP_CODE_REQUEST;
 295         req->identifier = id;
 296         req->length = htons(*reqDataLen);
 297         pos = (u8 *) (req + 1);
 298         *pos++ = eap_type; /* Type */
 299         *pos = peap_version; /* Flags */
 300         return (u8 *) req;
 301 }