crypto/dist/heimdal/appl/kx/krb5.c

   1 /*
   2  * Copyright (c) 1995 - 2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "kx.h"
  35
  36 __RCSID("$Heimdal: krb5.c 17450 2006-05-05 11:11:43Z lha $"
  37         "$NetBSD$");
  38
  39 #ifdef KRB5
  40
  41 struct krb5_kx_context {
  42     krb5_context context;
  43     krb5_keyblock *keyblock;
  44     krb5_crypto crypto;
  45     krb5_principal client;
  46     krb5_log_facility *log;
  47
  48 };
  49
  50 typedef struct krb5_kx_context krb5_kx_context;
  51
  52 #define K5DATA(kc) ((krb5_kx_context*)kc->data)
  53 #define CONTEXT(kc) (K5DATA(kc)->context)
  54
  55 /*
  56  * Destroy the krb5 context in `c'.
  57  */
  58
  59 static void
  60 krb5_destroy (kx_context *kc)
  61 {
  62     if (K5DATA(kc)->keyblock)
  63         krb5_free_keyblock (CONTEXT(kc), K5DATA(kc)->keyblock);
  64     if (K5DATA(kc)->crypto)
  65         krb5_crypto_destroy (CONTEXT(kc), K5DATA(kc)->crypto);
  66     if (K5DATA(kc)->client)
  67         krb5_free_principal (CONTEXT(kc), K5DATA(kc)->client);
  68     if (CONTEXT(kc))
  69         krb5_free_context (CONTEXT(kc));
  70     memset (kc->data, 0, sizeof(krb5_kx_context));
  71     free (kc->data);
  72 }
  73
  74 /*
  75  * Read the authentication information from `s' and return 0 if
  76  * succesful, else -1.
  77  */
  78
  79 static int
  80 krb5_authenticate (kx_context *kc, int s)
  81 {
  82     krb5_auth_context auth_context = NULL;
  83     krb5_error_code ret;
  84     krb5_principal server;
  85     const char *host = kc->host;
  86
  87     ret = krb5_sname_to_principal (CONTEXT(kc),
  88                                    host, "host", KRB5_NT_SRV_HST, &server);
  89     if (ret) {
  90         krb5_warn (CONTEXT(kc), ret, "krb5_sname_to_principal: %s", host);
  91         return 1;
  92     }
  93
  94     ret = krb5_sendauth (CONTEXT(kc),
  95                          &auth_context,
  96                          &s,
  97                          KX_VERSION,
  98                          NULL,
  99                          server,
 100                          AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
 101                          NULL,
 102                          NULL,
 103                          NULL,
 104                          NULL,
 105                          NULL,
 106                          NULL);
 107     if (ret) {
 108         if(ret != KRB5_SENDAUTH_BADRESPONSE)
 109             krb5_warn (CONTEXT(kc), ret, "krb5_sendauth: %s", host);
 110         return 1;
 111     }
 112
 113     ret = krb5_auth_con_getkey (CONTEXT(kc), auth_context,
 114                                 &K5DATA(kc)->keyblock);
 115     if (ret) {
 116         krb5_warn (CONTEXT(kc), ret, "krb5_auth_con_getkey: %s", host);
 117         krb5_auth_con_free (CONTEXT(kc), auth_context);
 118         return 1;
 119     }
 120
 121     ret = krb5_crypto_init (CONTEXT(kc), K5DATA(kc)->keyblock,
 122                             0, &K5DATA(kc)->crypto);
 123     if (ret) {
 124         krb5_warn (CONTEXT(kc), ret, "krb5_crypto_init");
 125         krb5_auth_con_free (CONTEXT(kc), auth_context);
 126         return 1;
 127     }
 128     return 0;
 129 }
 130
 131 /*
 132  * Read an encapsulated krb5 packet from `fd' into `buf' (of size
 133  * `len').  Return the number of bytes read or 0 on EOF or -1 on
 134  * error.
 135  */
 136
 137 static ssize_t
 138 krb5_read (kx_context *kc,
 139            int fd, void *buf, size_t len)
 140 {
 141     size_t data_len, outer_len;
 142     krb5_error_code ret;
 143     unsigned char tmp[4];
 144     krb5_data data;
 145     int l;
 146
 147     l = krb5_net_read (CONTEXT(kc), &fd, tmp, 4);
 148     if (l == 0)
 149         return l;
 150     if (l != 4)
 151         return -1;
 152     data_len  = (tmp[0] << 24) | (tmp[1] << 16) | (tmp[2] << 8) | tmp[3];
 153     outer_len = krb5_get_wrapped_length (CONTEXT(kc),
 154                                          K5DATA(kc)->crypto, data_len);
 155     if (outer_len > len)
 156         return -1;
 157     if (krb5_net_read (CONTEXT(kc), &fd, buf, outer_len) != outer_len)
 158         return -1;
 159
 160     ret = krb5_decrypt (CONTEXT(kc), K5DATA(kc)->crypto,
 161                         KRB5_KU_OTHER_ENCRYPTED,
 162                         buf, outer_len, &data);
 163     if (ret) {
 164         krb5_warn (CONTEXT(kc), ret, "krb5_decrypt");
 165         return -1;
 166     }
 167     if (data_len > data.length) {
 168         krb5_data_free (&data);
 169         return -1;
 170     }
 171     memmove (buf, data.data, data_len);
 172     krb5_data_free (&data);
 173     return data_len;
 174 }
 175
 176 /*
 177  * Write an encapsulated krb5 packet on `fd' with the data in `buf,
 178  * len'.  Return len or -1 on error.
 179  */
 180
 181 static ssize_t
 182 krb5_write(kx_context *kc,
 183            int fd, const void *buf, size_t len)
 184 {
 185     krb5_data data;
 186     krb5_error_code ret;
 187     unsigned char tmp[4];
 188     size_t outlen;
 189
 190     ret = krb5_encrypt (CONTEXT(kc), K5DATA(kc)->crypto,
 191                         KRB5_KU_OTHER_ENCRYPTED,
 192                         buf, len, &data);
 193     if (ret){
 194         krb5_warn (CONTEXT(kc), ret, "krb5_write");
 195         return -1;
 196     }
 197
 198     outlen = data.length;
 199     tmp[0] = (len >> 24) & 0xFF;
 200     tmp[1] = (len >> 16) & 0xFF;
 201     tmp[2] = (len >>  8) & 0xFF;
 202     tmp[3] = (len >>  0) & 0xFF;
 203
 204     if (krb5_net_write (CONTEXT(kc), &fd, tmp, 4) != 4 ||
 205         krb5_net_write (CONTEXT(kc), &fd, data.data, outlen) != outlen) {
 206         krb5_data_free (&data);
 207         return -1;
 208     }
 209     krb5_data_free (&data);
 210     return len;
 211 }
 212
 213 /*
 214  * Copy from the unix socket `from_fd' encrypting to `to_fd'.
 215  * Return 0, -1 or len.
 216  */
 217
 218 static int
 219 copy_out (kx_context *kc, int from_fd, int to_fd)
 220 {
 221     char buf[32768];
 222     ssize_t len;
 223
 224     len = read (from_fd, buf, sizeof(buf));
 225     if (len == 0)
 226         return 0;
 227     if (len < 0) {
 228         krb5_warn (CONTEXT(kc), errno, "read");
 229         return len;
 230     }
 231     return krb5_write (kc, to_fd, buf, len);
 232 }
 233
 234 /*
 235  * Copy from the socket `from_fd' decrypting to `to_fd'.
 236  * Return 0, -1 or len.
 237  */
 238
 239 static int
 240 copy_in (kx_context *kc, int from_fd, int to_fd)
 241 {
 242     char buf[33000];            /* XXX */
 243
 244     ssize_t len;
 245
 246     len = krb5_read (kc, from_fd, buf, sizeof(buf));
 247     if (len == 0)
 248         return 0;
 249     if (len < 0) {
 250         krb5_warn (CONTEXT(kc), errno, "krb5_read");
 251         return len;
 252     }
 253
 254     return krb5_net_write (CONTEXT(kc), &to_fd, buf, len);
 255 }
 256
 257 /*
 258  * Copy data between `fd1' and `fd2', encrypting in one direction and
 259  * decrypting in the other.
 260  */
 261
 262 static int
 263 krb5_copy_encrypted (kx_context *kc, int fd1, int fd2)
 264 {
 265     for (;;) {
 266         fd_set fdset;
 267         int ret;
 268
 269         if (fd1 >= FD_SETSIZE || fd2 >= FD_SETSIZE) {
 270             krb5_warnx (CONTEXT(kc), "fd too large");
 271             return 1;
 272         }
 273
 274         FD_ZERO(&fdset);
 275         FD_SET(fd1, &fdset);
 276         FD_SET(fd2, &fdset);
 277
 278         ret = select (max(fd1, fd2)+1, &fdset, NULL, NULL, NULL);
 279         if (ret < 0 && errno != EINTR) {
 280             krb5_warn (CONTEXT(kc), errno, "select");
 281             return 1;
 282         }
 283         if (FD_ISSET(fd1, &fdset)) {
 284             ret = copy_out (kc, fd1, fd2);
 285             if (ret <= 0)
 286                 return ret;
 287         }
 288         if (FD_ISSET(fd2, &fdset)) {
 289             ret = copy_in (kc, fd2, fd1);
 290             if (ret <= 0)
 291                 return ret;
 292         }
 293     }
 294 }
 295
 296 /*
 297  * Return 0 if the user authenticated on `kc' is allowed to login as
 298  * `user'.
 299  */
 300
 301 static int
 302 krb5_userok (kx_context *kc, char *user)
 303 {
 304     krb5_error_code ret;
 305     char *tmp;
 306
 307     ret = krb5_unparse_name (CONTEXT(kc), K5DATA(kc)->client, &tmp);
 308     if (ret)
 309         krb5_err (CONTEXT(kc), 1, ret, "krb5_unparse_name");
 310     kc->user = tmp;
 311
 312     return !krb5_kuserok (CONTEXT(kc), K5DATA(kc)->client, user);
 313 }
 314
 315 /*
 316  * Create an instance of an krb5 context.
 317  */
 318
 319 void
 320 krb5_make_context (kx_context *kc)
 321 {
 322     krb5_kx_context *c;
 323     krb5_error_code ret;
 324
 325     kc->authenticate    = krb5_authenticate;
 326     kc->userok          = krb5_userok;
 327     kc->read            = krb5_read;
 328     kc->write           = krb5_write;
 329     kc->copy_encrypted  = krb5_copy_encrypted;
 330     kc->destroy         = krb5_destroy;
 331     kc->user            = NULL;
 332     kc->data            = malloc(sizeof(krb5_kx_context));
 333
 334     if (kc->data == NULL) {
 335         syslog (LOG_ERR, "failed to malloc %lu bytes",
 336                 (unsigned long)sizeof(krb5_kx_context));
 337         exit(1);
 338     }
 339     memset (kc->data, 0, sizeof(krb5_kx_context));
 340     c = (krb5_kx_context *)kc->data;
 341     ret = krb5_init_context (&c->context);
 342     if (ret) {
 343         syslog (LOG_ERR, "failed initialise krb5 context");
 344         exit(1);
 345     }
 346 }
 347
 348 /*
 349  * Receive authentication information on `sock' (first four bytes
 350  * in `buf').
 351  */
 352
 353 int
 354 recv_v5_auth (kx_context *kc, int sock, u_char *buf)
 355 {
 356     uint32_t len;
 357     krb5_error_code ret;
 358     krb5_principal server;
 359     krb5_auth_context auth_context = NULL;
 360     krb5_ticket *ticket;
 361
 362     if (memcmp (buf, "\x00\x00\x00\x13", 4) != 0)
 363         return 1;
 364     len = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3]);
 365     if (net_read(sock, buf, len) != len) {
 366         syslog (LOG_ERR, "read: %m");
 367         exit (1);
 368     }
 369     if (len != sizeof(KRB5_SENDAUTH_VERSION)
 370         || memcmp (buf, KRB5_SENDAUTH_VERSION, len) != 0) {
 371         syslog (LOG_ERR, "bad sendauth version: %.8s", buf);
 372         exit (1);
 373     }
 374
 375     krb5_make_context (kc);
 376     krb5_openlog(CONTEXT(kc), "kxd", &K5DATA(kc)->log);
 377     krb5_set_warn_dest(CONTEXT(kc), K5DATA(kc)->log);
 378
 379     ret = krb5_sock_to_principal (CONTEXT(kc), sock, "host",
 380                                   KRB5_NT_SRV_HST, &server);
 381     if (ret) {
 382         syslog (LOG_ERR, "krb5_sock_to_principal: %s",
 383                 krb5_get_err_text (CONTEXT(kc), ret));
 384         exit (1);
 385     }
 386
 387     ret = krb5_recvauth (CONTEXT(kc),
 388                          &auth_context,
 389                          &sock,
 390                          KX_VERSION,
 391                          server,
 392                          KRB5_RECVAUTH_IGNORE_VERSION,
 393                          NULL,
 394                          &ticket);
 395     krb5_free_principal (CONTEXT(kc), server);
 396     if (ret) {
 397         syslog (LOG_ERR, "krb5_sock_to_principal: %s",
 398                 krb5_get_err_text (CONTEXT(kc), ret));
 399         exit (1);
 400     }
 401
 402     ret = krb5_auth_con_getkey (CONTEXT(kc), auth_context, &K5DATA(kc)->keyblock);
 403     if (ret) {
 404         syslog (LOG_ERR, "krb5_auth_con_getkey: %s",
 405                 krb5_get_err_text (CONTEXT(kc), ret));
 406         exit (1);
 407     }
 408
 409     ret = krb5_crypto_init (CONTEXT(kc), K5DATA(kc)->keyblock, 0, &K5DATA(kc)->crypto);
 410     if (ret) {
 411         syslog (LOG_ERR, "krb5_crypto_init: %s",
 412                 krb5_get_err_text (CONTEXT(kc), ret));
 413         exit (1);
 414     }
 415
 416     K5DATA(kc)->client = ticket->client;
 417     ticket->client = NULL;
 418     krb5_free_ticket (CONTEXT(kc), ticket);
 419
 420     return 0;
 421 }
 422
 423 #endif /* KRB5 */