1/* GSSAPI/krb5 support for FTP - loosely based on old krb4.c
2 *
3 * Copyright (c) 1995, 1996, 1997, 1998, 1999 Kungliga Tekniska Högskolan
4 * (Royal Institute of Technology, Stockholm, Sweden).
5 * Copyright (c) 2004 - 2019 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#if defined(HAVE_GSSAPI) && !defined(CURL_DISABLE_FTP)
38
39#ifdef HAVE_NETDB_H
40#include <netdb.h>
41#endif
42
43#include "urldata.h"
44#include "curl_base64.h"
45#include "ftp.h"
46#include "curl_gssapi.h"
47#include "sendf.h"
48#include "curl_sec.h"
49#include "warnless.h"
50
51/* The last 3 #include files should be in this order */
52#include "curl_printf.h"
53#include "curl_memory.h"
54#include "memdebug.h"
55
56static int
57krb5_init(void *app_data)
58{
59 gss_ctx_id_t *context = app_data;
60 /* Make sure our context is initialized for krb5_end. */
61 *context = GSS_C_NO_CONTEXT;
62 return 0;
63}
64
65static int
66krb5_check_prot(void *app_data, int level)
67{
68 (void)app_data; /* unused */
69 if(level == PROT_CONFIDENTIAL)
70 return -1;
71 return 0;
72}
73
74static int
75krb5_decode(void *app_data, void *buf, int len,
76 int level UNUSED_PARAM,
77 struct connectdata *conn UNUSED_PARAM)
78{
79 gss_ctx_id_t *context = app_data;
80 OM_uint32 maj, min;
81 gss_buffer_desc enc, dec;
82
83 (void)level;
84 (void)conn;
85
86 enc.value = buf;
87 enc.length = len;
88 maj = gss_unwrap(&min, *context, &enc, &dec, NULL, NULL);
89 if(maj != GSS_S_COMPLETE) {
90 if(len >= 4)
91 strcpy(buf, "599 ");
92 return -1;
93 }
94
95 memcpy(buf, dec.value, dec.length);
96 len = curlx_uztosi(dec.length);
97 gss_release_buffer(&min, &dec);
98
99 return len;
100}
101
102static int
103krb5_overhead(void *app_data, int level, int len)
104{
105 /* no arguments are used */
106 (void)app_data;
107 (void)level;
108 (void)len;
109 return 0;
110}
111
112static int
113krb5_encode(void *app_data, const void *from, int length, int level, void **to)
114{
115 gss_ctx_id_t *context = app_data;
116 gss_buffer_desc dec, enc;
117 OM_uint32 maj, min;
118 int state;
119 int len;
120
121 /* NOTE that the cast is safe, neither of the krb5, gnu gss and heimdal
122 * libraries modify the input buffer in gss_wrap()
123 */
124 dec.value = (void *)from;
125 dec.length = length;
126 maj = gss_wrap(&min, *context,
127 level == PROT_PRIVATE,
128 GSS_C_QOP_DEFAULT,
129 &dec, &state, &enc);
130
131 if(maj != GSS_S_COMPLETE)
132 return -1;
133
134 /* malloc a new buffer, in case gss_release_buffer doesn't work as
135 expected */
136 *to = malloc(enc.length);
137 if(!*to)
138 return -1;
139 memcpy(*to, enc.value, enc.length);
140 len = curlx_uztosi(enc.length);
141 gss_release_buffer(&min, &enc);
142 return len;
143}
144
145static int
146krb5_auth(void *app_data, struct connectdata *conn)
147{
148 int ret = AUTH_OK;
149 char *p;
150 const char *host = conn->host.name;
151 ssize_t nread;
152 curl_socklen_t l = sizeof(conn->local_addr);
153 struct Curl_easy *data = conn->data;
154 CURLcode result;
155 const char *service = data->set.str[STRING_SERVICE_NAME] ?
156 data->set.str[STRING_SERVICE_NAME] :
157 "ftp";
158 const char *srv_host = "host";
159 gss_buffer_desc input_buffer, output_buffer, _gssresp, *gssresp;
160 OM_uint32 maj, min;
161 gss_name_t gssname;
162 gss_ctx_id_t *context = app_data;
163 struct gss_channel_bindings_struct chan;
164 size_t base64_sz = 0;
165 struct sockaddr_in **remote_addr =
166 (struct sockaddr_in **)&conn->ip_addr->ai_addr;
167 char *stringp;
168
169 if(getsockname(conn->sock[FIRSTSOCKET],
170 (struct sockaddr *)&conn->local_addr, &l) < 0)
171 perror("getsockname()");
172
173 chan.initiator_addrtype = GSS_C_AF_INET;
174 chan.initiator_address.length = l - 4;
175 chan.initiator_address.value = &conn->local_addr.sin_addr.s_addr;
176 chan.acceptor_addrtype = GSS_C_AF_INET;
177 chan.acceptor_address.length = l - 4;
178 chan.acceptor_address.value = &(*remote_addr)->sin_addr.s_addr;
179 chan.application_data.length = 0;
180 chan.application_data.value = NULL;
181
182 /* this loop will execute twice (once for service, once for host) */
183 for(;;) {
184 /* this really shouldn't be repeated here, but can't help it */
185 if(service == srv_host) {
186 result = Curl_ftpsend(conn, "AUTH GSSAPI");
187 if(result)
188 return -2;
189
190 if(Curl_GetFTPResponse(&nread, conn, NULL))
191 return -1;
192
193 if(data->state.buffer[0] != '3')
194 return -1;
195 }
196
197 stringp = aprintf("%s@%s", service, host);
198 if(!stringp)
199 return -2;
200
201 input_buffer.value = stringp;
202 input_buffer.length = strlen(stringp);
203 maj = gss_import_name(&min, &input_buffer, GSS_C_NT_HOSTBASED_SERVICE,
204 &gssname);
205 free(stringp);
206 if(maj != GSS_S_COMPLETE) {
207 gss_release_name(&min, &gssname);
208 if(service == srv_host) {
209 failf(data, "Error importing service name %s@%s", service, host);
210 return AUTH_ERROR;
211 }
212 service = srv_host;
213 continue;
214 }
215 /* We pass NULL as |output_name_type| to avoid a leak. */
216 gss_display_name(&min, gssname, &output_buffer, NULL);
217 Curl_infof(data, "Trying against %s\n", output_buffer.value);
218 gssresp = GSS_C_NO_BUFFER;
219 *context = GSS_C_NO_CONTEXT;
220
221 do {
222 /* Release the buffer at each iteration to avoid leaking: the first time
223 we are releasing the memory from gss_display_name. The last item is
224 taken care by a final gss_release_buffer. */
225 gss_release_buffer(&min, &output_buffer);
226 ret = AUTH_OK;
227 maj = Curl_gss_init_sec_context(data,
228 &min,
229 context,
230 gssname,
231 &Curl_krb5_mech_oid,
232 &chan,
233 gssresp,
234 &output_buffer,
235 TRUE,
236 NULL);
237
238 if(gssresp) {
239 free(_gssresp.value);
240 gssresp = NULL;
241 }
242
243 if(GSS_ERROR(maj)) {
244 Curl_infof(data, "Error creating security context\n");
245 ret = AUTH_ERROR;
246 break;
247 }
248
249 if(output_buffer.length != 0) {
250 char *cmd;
251
252 result = Curl_base64_encode(data, (char *)output_buffer.value,
253 output_buffer.length, &p, &base64_sz);
254 if(result) {
255 Curl_infof(data, "base64-encoding: %s\n",
256 curl_easy_strerror(result));
257 ret = AUTH_ERROR;
258 break;
259 }
260
261 cmd = aprintf("ADAT %s", p);
262 if(cmd)
263 result = Curl_ftpsend(conn, cmd);
264 else
265 result = CURLE_OUT_OF_MEMORY;
266
267 free(p);
268 free(cmd);
269
270 if(result) {
271 ret = -2;
272 break;
273 }
274
275 if(Curl_GetFTPResponse(&nread, conn, NULL)) {
276 ret = -1;
277 break;
278 }
279
280 if(data->state.buffer[0] != '2' && data->state.buffer[0] != '3') {
281 Curl_infof(data, "Server didn't accept auth data\n");
282 ret = AUTH_ERROR;
283 break;
284 }
285
286 _gssresp.value = NULL; /* make sure it is initialized */
287 p = data->state.buffer + 4;
288 p = strstr(p, "ADAT=");
289 if(p) {
290 result = Curl_base64_decode(p + 5,
291 (unsigned char **)&_gssresp.value,
292 &_gssresp.length);
293 if(result) {
294 failf(data, "base64-decoding: %s", curl_easy_strerror(result));
295 ret = AUTH_CONTINUE;
296 break;
297 }
298 }
299
300 gssresp = &_gssresp;
301 }
302 } while(maj == GSS_S_CONTINUE_NEEDED);
303
304 gss_release_name(&min, &gssname);
305 gss_release_buffer(&min, &output_buffer);
306
307 if(gssresp)
308 free(_gssresp.value);
309
310 if(ret == AUTH_OK || service == srv_host)
311 return ret;
312
313 service = srv_host;
314 }
315 return ret;
316}
317
318static void krb5_end(void *app_data)
319{
320 OM_uint32 min;
321 gss_ctx_id_t *context = app_data;
322 if(*context != GSS_C_NO_CONTEXT) {
323 OM_uint32 maj = gss_delete_sec_context(&min, context, GSS_C_NO_BUFFER);
324 (void)maj;
325 DEBUGASSERT(maj == GSS_S_COMPLETE);
326 }
327}
328
329struct Curl_sec_client_mech Curl_krb5_client_mech = {
330 "GSSAPI",
331 sizeof(gss_ctx_id_t),
332 krb5_init,
333 krb5_auth,
334 krb5_end,
335 krb5_check_prot,
336 krb5_overhead,
337 krb5_encode,
338 krb5_decode
339};
340
341#endif /* HAVE_GSSAPI && !CURL_DISABLE_FTP */
342