1/* GSSAPI/krb5 support for FTP - loosely based on old krb4.c
2 *
3 * Copyright (c) 1995, 1996, 1997, 1998, 1999, 2013 Kungliga Tekniska H�gskolan
4 * (Royal Institute of Technology, Stockholm, Sweden).
5 * Copyright (c) 2004 - 2012 Daniel Stenberg
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.  */
34
35#include "curl_setup.h"
36
37#ifndef CURL_DISABLE_FTP
38#ifdef HAVE_GSSAPI
39
40#ifdef HAVE_OLD_GSSMIT
41#define GSS_C_NT_HOSTBASED_SERVICE gss_nt_service_name
42#define NCOMPAT 1
43#endif
44
45#ifdef HAVE_NETDB_H
46#include <netdb.h>
47#endif
48
49#include "urldata.h"
50#include "curl_base64.h"
51#include "ftp.h"
52#include "curl_gssapi.h"
53#include "sendf.h"
54#include "curl_sec.h"
55#include "curl_memory.h"
56#include "warnless.h"
57
58#define _MPRINTF_REPLACE /* use our functions only */
59#include <curl/mprintf.h>
60
61/* The last #include file should be: */
62#include "memdebug.h"
63
64#define LOCAL_ADDR (&conn->local_addr)
65#define REMOTE_ADDR conn->ip_addr->ai_addr
66
67static int
68krb5_init(void *app_data)
69{
70  gss_ctx_id_t *context = app_data;
71  /* Make sure our context is initialized for krb5_end. */
72  *context = GSS_C_NO_CONTEXT;
73  return 0;
74}
75
76static int
77krb5_check_prot(void *app_data, int level)
78{
79  (void)app_data; /* unused */
80  if(level == PROT_CONFIDENTIAL)
81    return -1;
82  return 0;
83}
84
85static int
86krb5_decode(void *app_data, void *buf, int len,
87            int level UNUSED_PARAM,
88            struct connectdata *conn UNUSED_PARAM)
89{
90  gss_ctx_id_t *context = app_data;
91  OM_uint32 maj, min;
92  gss_buffer_desc enc, dec;
93
94  (void)level;
95  (void)conn;
96
97  enc.value = buf;
98  enc.length = len;
99  maj = gss_unseal(&min, *context, &enc, &dec, NULL, NULL);
100  if(maj != GSS_S_COMPLETE) {
101    if(len >= 4)
102      strcpy(buf, "599 ");
103    return -1;
104  }
105
106  memcpy(buf, dec.value, dec.length);
107  len = curlx_uztosi(dec.length);
108  gss_release_buffer(&min, &dec);
109
110  return len;
111}
112
113static int
114krb5_overhead(void *app_data, int level, int len)
115{
116  /* no arguments are used */
117  (void)app_data;
118  (void)level;
119  (void)len;
120  return 0;
121}
122
123static int
124krb5_encode(void *app_data, const void *from, int length, int level, void **to,
125            struct connectdata *conn UNUSED_PARAM)
126{
127  gss_ctx_id_t *context = app_data;
128  gss_buffer_desc dec, enc;
129  OM_uint32 maj, min;
130  int state;
131  int len;
132
133  /* shut gcc up */
134  conn = NULL;
135
136  /* NOTE that the cast is safe, neither of the krb5, gnu gss and heimdal
137   * libraries modify the input buffer in gss_seal()
138   */
139  dec.value = (void*)from;
140  dec.length = length;
141  maj = gss_seal(&min, *context,
142                 level == PROT_PRIVATE,
143                 GSS_C_QOP_DEFAULT,
144                 &dec, &state, &enc);
145
146  if(maj != GSS_S_COMPLETE)
147    return -1;
148
149  /* malloc a new buffer, in case gss_release_buffer doesn't work as
150     expected */
151  *to = malloc(enc.length);
152  if(!*to)
153    return -1;
154  memcpy(*to, enc.value, enc.length);
155  len = curlx_uztosi(enc.length);
156  gss_release_buffer(&min, &enc);
157  return len;
158}
159
160static int
161krb5_auth(void *app_data, struct connectdata *conn)
162{
163  int ret = AUTH_OK;
164  char *p;
165  const char *host = conn->host.name;
166  ssize_t nread;
167  curl_socklen_t l = sizeof(conn->local_addr);
168  struct SessionHandle *data = conn->data;
169  CURLcode result;
170  const char *service = "ftp", *srv_host = "host";
171  gss_buffer_desc input_buffer, output_buffer, _gssresp, *gssresp;
172  OM_uint32 maj, min;
173  gss_name_t gssname;
174  gss_ctx_id_t *context = app_data;
175  struct gss_channel_bindings_struct chan;
176  size_t base64_sz = 0;
177
178  if(getsockname(conn->sock[FIRSTSOCKET],
179                 (struct sockaddr *)LOCAL_ADDR, &l) < 0)
180    perror("getsockname()");
181
182  chan.initiator_addrtype = GSS_C_AF_INET;
183  chan.initiator_address.length = l - 4;
184  chan.initiator_address.value =
185    &((struct sockaddr_in *)LOCAL_ADDR)->sin_addr.s_addr;
186  chan.acceptor_addrtype = GSS_C_AF_INET;
187  chan.acceptor_address.length = l - 4;
188  chan.acceptor_address.value =
189    &((struct sockaddr_in *)REMOTE_ADDR)->sin_addr.s_addr;
190  chan.application_data.length = 0;
191  chan.application_data.value = NULL;
192
193  /* this loop will execute twice (once for service, once for host) */
194  for(;;) {
195    /* this really shouldn't be repeated here, but can't help it */
196    if(service == srv_host) {
197      result = Curl_ftpsendf(conn, "AUTH GSSAPI");
198
199      if(result)
200        return -2;
201      if(Curl_GetFTPResponse(&nread, conn, NULL))
202        return -1;
203
204      if(data->state.buffer[0] != '3')
205        return -1;
206    }
207
208    input_buffer.value = data->state.buffer;
209    input_buffer.length = snprintf(input_buffer.value, BUFSIZE, "%s@%s",
210                                   service, host);
211    maj = gss_import_name(&min, &input_buffer, GSS_C_NT_HOSTBASED_SERVICE,
212                          &gssname);
213    if(maj != GSS_S_COMPLETE) {
214      gss_release_name(&min, &gssname);
215      if(service == srv_host) {
216        Curl_failf(data, "Error importing service name %s",
217                   input_buffer.value);
218        return AUTH_ERROR;
219      }
220      service = srv_host;
221      continue;
222    }
223    /* We pass NULL as |output_name_type| to avoid a leak. */
224    gss_display_name(&min, gssname, &output_buffer, NULL);
225    Curl_infof(data, "Trying against %s\n", output_buffer.value);
226    gssresp = GSS_C_NO_BUFFER;
227    *context = GSS_C_NO_CONTEXT;
228
229    do {
230      /* Release the buffer at each iteration to avoid leaking: the first time
231         we are releasing the memory from gss_display_name. The last item is
232         taken care by a final gss_release_buffer. */
233      gss_release_buffer(&min, &output_buffer);
234      ret = AUTH_OK;
235      maj = Curl_gss_init_sec_context(data,
236                                      &min,
237                                      context,
238                                      gssname,
239                                      &chan,
240                                      gssresp,
241                                      &output_buffer,
242                                      NULL);
243
244      if(gssresp) {
245        free(_gssresp.value);
246        gssresp = NULL;
247      }
248
249      if(GSS_ERROR(maj)) {
250        Curl_infof(data, "Error creating security context\n");
251        ret = AUTH_ERROR;
252        break;
253      }
254
255      if(output_buffer.length != 0) {
256        result = Curl_base64_encode(data, (char *)output_buffer.value,
257                                    output_buffer.length, &p, &base64_sz);
258        if(result) {
259          Curl_infof(data,"base64-encoding: %s\n", curl_easy_strerror(result));
260          ret = AUTH_CONTINUE;
261          break;
262        }
263
264        result = Curl_ftpsendf(conn, "ADAT %s", p);
265
266        free(p);
267
268        if(result) {
269          ret = -2;
270          break;
271        }
272
273        if(Curl_GetFTPResponse(&nread, conn, NULL)) {
274          ret = -1;
275          break;
276        }
277
278        if(data->state.buffer[0] != '2' && data->state.buffer[0] != '3') {
279          Curl_infof(data, "Server didn't accept auth data\n");
280          ret = AUTH_ERROR;
281          break;
282        }
283
284        p = data->state.buffer + 4;
285        p = strstr(p, "ADAT=");
286        if(p) {
287          result = Curl_base64_decode(p + 5,
288                                      (unsigned char **)&_gssresp.value,
289                                      &_gssresp.length);
290          if(result) {
291            Curl_failf(data,"base64-decoding: %s", curl_easy_strerror(result));
292            ret = AUTH_CONTINUE;
293            break;
294          }
295        }
296
297        gssresp = &_gssresp;
298      }
299    } while(maj == GSS_S_CONTINUE_NEEDED);
300
301    gss_release_name(&min, &gssname);
302    gss_release_buffer(&min, &output_buffer);
303
304    if(gssresp)
305      free(_gssresp.value);
306
307    if(ret == AUTH_OK || service == srv_host)
308      return ret;
309
310    service = srv_host;
311  }
312  return ret;
313}
314
315static void krb5_end(void *app_data)
316{
317    OM_uint32 min;
318    gss_ctx_id_t *context = app_data;
319    if(*context != GSS_C_NO_CONTEXT) {
320#ifdef DEBUGBUILD
321      OM_uint32 maj =
322#endif
323      gss_delete_sec_context(&min, context, GSS_C_NO_BUFFER);
324      DEBUGASSERT(maj == GSS_S_COMPLETE);
325    }
326}
327
328struct Curl_sec_client_mech Curl_krb5_client_mech = {
329    "GSSAPI",
330    sizeof(gss_ctx_id_t),
331    krb5_init,
332    krb5_auth,
333    krb5_end,
334    krb5_check_prot,
335    krb5_overhead,
336    krb5_encode,
337    krb5_decode
338};
339
340#endif /* HAVE_GSSAPI */
341#endif /* CURL_DISABLE_FTP */
342