1/* This source code was modified by Martin Hedenfalk <mhe@stacken.kth.se> for
2 * use in Curl. His latest changes were done 2000-09-18.
3 *
4 * It has since been patched and modified a lot by Daniel Stenberg
5 * <daniel@haxx.se> to make it better applied to curl conditions, and to make
6 * it not use globals, pollute name space and more. This source code awaits a
7 * rewrite to work around the paragraph 2 in the BSD licenses as explained
8 * below.
9 *
10 * Copyright (c) 1998, 1999 Kungliga Tekniska H�gskolan
11 * (Royal Institute of Technology, Stockholm, Sweden).
12 *
13 * Copyright (C) 2001 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
14 *
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 *
21 * 1. Redistributions of source code must retain the above copyright
22 *    notice, this list of conditions and the following disclaimer.
23 *
24 * 2. Redistributions in binary form must reproduce the above copyright
25 *    notice, this list of conditions and the following disclaimer in the
26 *    documentation and/or other materials provided with the distribution.
27 *
28 * 3. Neither the name of the Institute nor the names of its contributors
29 *    may be used to endorse or promote products derived from this software
30 *    without specific prior written permission.
31 *
32 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
35 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
42 * SUCH DAMAGE.  */
43
44#include "setup.h"
45
46#ifndef CURL_DISABLE_FTP
47#if defined(HAVE_KRB4) || defined(HAVE_GSSAPI)
48
49#include <stdarg.h>
50#include <string.h>
51
52#ifdef HAVE_NETDB_H
53#include <netdb.h>
54#endif
55
56#ifdef HAVE_UNISTD_H
57#include <unistd.h>
58#endif
59
60#include "urldata.h"
61#include "curl_base64.h"
62#include "curl_memory.h"
63#include "krb4.h"
64#include "ftp.h"
65#include "sendf.h"
66#include "rawstr.h"
67
68/* The last #include file should be: */
69#include "memdebug.h"
70
71static const struct {
72  enum protection_level level;
73  const char *name;
74} level_names[] = {
75  { PROT_CLEAR, "clear" },
76  { PROT_SAFE, "safe" },
77  { PROT_CONFIDENTIAL, "confidential" },
78  { PROT_PRIVATE, "private" }
79};
80
81static enum protection_level
82name_to_level(const char *name)
83{
84  int i;
85  for(i = 0; i < (int)sizeof(level_names)/(int)sizeof(level_names[0]); i++)
86    if(checkprefix(name, level_names[i].name))
87      return level_names[i].level;
88  return PROT_NONE;
89}
90
91/* Convert a protocol |level| to its char representation.
92   We take an int to catch programming mistakes. */
93static char level_to_char(int level) {
94  switch(level) {
95  case PROT_CLEAR:
96    return 'C';
97  case PROT_SAFE:
98    return 'S';
99  case PROT_CONFIDENTIAL:
100    return 'E';
101  case PROT_PRIVATE:
102    return 'P';
103  case PROT_CMD:
104    /* Fall through */
105  default:
106    /* Those 2 cases should not be reached! */
107    break;
108  }
109  DEBUGASSERT(0);
110  /* Default to the most secure alternative. */
111  return 'P';
112}
113
114static const struct Curl_sec_client_mech * const mechs[] = {
115#if defined(HAVE_GSSAPI)
116  &Curl_krb5_client_mech,
117#endif
118#if defined(HAVE_KRB4)
119  &Curl_krb4_client_mech,
120#endif
121  NULL
122};
123
124/* Send an FTP command defined by |message| and the optional arguments. The
125   function returns the ftp_code. If an error occurs, -1 is returned. */
126static int ftp_send_command(struct connectdata *conn, const char *message, ...)
127{
128  int ftp_code;
129  ssize_t nread;
130  va_list args;
131  char print_buffer[50];
132
133  va_start(args, message);
134  vsnprintf(print_buffer, sizeof(print_buffer), message, args);
135  va_end(args);
136
137  if(Curl_ftpsendf(conn, print_buffer) != CURLE_OK) {
138    ftp_code = -1;
139  }
140  else {
141    if(Curl_GetFTPResponse(&nread, conn, &ftp_code) != CURLE_OK)
142      ftp_code = -1;
143  }
144
145  (void)nread; /* Unused */
146  return ftp_code;
147}
148
149/* Read |len| from the socket |fd| and store it in |to|. Return a CURLcode
150   saying whether an error occurred or CURLE_OK if |len| was read. */
151static CURLcode
152socket_read(curl_socket_t fd, void *to, size_t len)
153{
154  char *to_p = to;
155  CURLcode code;
156  ssize_t nread;
157
158  while(len > 0) {
159    code = Curl_read_plain(fd, to_p, len, &nread);
160    if(code == CURLE_OK) {
161      len -= nread;
162      to_p += nread;
163    }
164    else {
165      /* FIXME: We are doing a busy wait */
166      if(code == CURLE_AGAIN)
167        continue;
168      return code;
169    }
170  }
171  return CURLE_OK;
172}
173
174
175/* Write |len| bytes from the buffer |to| to the socket |fd|. Return a
176   CURLcode saying whether an error occurred or CURLE_OK if |len| was
177   written. */
178static CURLcode
179socket_write(struct connectdata *conn, curl_socket_t fd, const void *to,
180             size_t len)
181{
182  const char *to_p = to;
183  CURLcode code;
184  ssize_t written;
185
186  while(len > 0) {
187    code = Curl_write_plain(conn, fd, to_p, len, &written);
188    if(code == CURLE_OK) {
189      len -= written;
190      to_p += written;
191    }
192    else {
193      /* FIXME: We are doing a busy wait */
194      if(code == CURLE_AGAIN)
195        continue;
196      return code;
197    }
198  }
199  return CURLE_OK;
200}
201
202static CURLcode read_data(struct connectdata *conn,
203                          curl_socket_t fd,
204                          struct krb4buffer *buf)
205{
206  int len;
207  void* tmp;
208  CURLcode ret;
209
210  ret = socket_read(fd, &len, sizeof(len));
211  if(ret != CURLE_OK)
212    return ret;
213
214  len = ntohl(len);
215  tmp = realloc(buf->data, len);
216  if(tmp == NULL)
217    return CURLE_OUT_OF_MEMORY;
218
219  buf->data = tmp;
220  ret = socket_read(fd, buf->data, len);
221  if(ret != CURLE_OK)
222    return ret;
223  buf->size = conn->mech->decode(conn->app_data, buf->data, len,
224                                 conn->data_prot, conn);
225  buf->index = 0;
226  return CURLE_OK;
227}
228
229static size_t
230buffer_read(struct krb4buffer *buf, void *data, size_t len)
231{
232  if(buf->size - buf->index < len)
233    len = buf->size - buf->index;
234  memcpy(data, (char*)buf->data + buf->index, len);
235  buf->index += len;
236  return len;
237}
238
239/* Matches Curl_recv signature */
240static ssize_t sec_recv(struct connectdata *conn, int sockindex,
241                        char *buffer, size_t len, CURLcode *err)
242{
243  size_t bytes_read;
244  size_t total_read = 0;
245  curl_socket_t fd = conn->sock[sockindex];
246
247  *err = CURLE_OK;
248
249  /* Handle clear text response. */
250  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR)
251      return read(fd, buffer, len);
252
253  if(conn->in_buffer.eof_flag) {
254    conn->in_buffer.eof_flag = 0;
255    return 0;
256  }
257
258  bytes_read = buffer_read(&conn->in_buffer, buffer, len);
259  len -= bytes_read;
260  total_read += bytes_read;
261  buffer += bytes_read;
262
263  while(len > 0) {
264    if(read_data(conn, fd, &conn->in_buffer) != CURLE_OK)
265      return -1;
266    if(conn->in_buffer.size == 0) {
267      if(bytes_read > 0)
268        conn->in_buffer.eof_flag = 1;
269      return bytes_read;
270    }
271    bytes_read = buffer_read(&conn->in_buffer, buffer, len);
272    len -= bytes_read;
273    total_read += bytes_read;
274    buffer += bytes_read;
275  }
276  /* FIXME: Check for overflow */
277  return total_read;
278}
279
280/* Send |length| bytes from |from| to the |fd| socket taking care of encoding
281   and negociating with the server. |from| can be NULL. */
282/* FIXME: We don't check for errors nor report any! */
283static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
284                        const char *from, int length)
285{
286  size_t bytes;
287  size_t htonl_bytes;
288  char *buffer;
289  char *cmd_buffer;
290  enum protection_level prot_level = conn->data_prot;
291  bool iscmd = prot_level == PROT_CMD;
292
293  DEBUGASSERT(prot_level > PROT_NONE && prot_level < PROT_LAST);
294
295  if(iscmd) {
296    if(!strncmp(from, "PASS ", 5) || !strncmp(from, "ACCT ", 5))
297      prot_level = PROT_PRIVATE;
298    else
299      prot_level = conn->command_prot;
300  }
301  bytes = conn->mech->encode(conn->app_data, from, length, prot_level,
302                             (void**)&buffer, conn);
303  if(iscmd) {
304    bytes = Curl_base64_encode(conn->data, buffer, bytes, &cmd_buffer);
305    if(bytes > 0) {
306      static const char *enc = "ENC ";
307      static const char *mic = "MIC ";
308      if(prot_level == PROT_PRIVATE)
309        socket_write(conn, fd, enc, 4);
310      else
311        socket_write(conn, fd, mic, 4);
312
313      socket_write(conn, fd, cmd_buffer, bytes);
314      socket_write(conn, fd, "\r\n", 2);
315      infof(conn->data, "Send: %s%s\n", prot_level == PROT_PRIVATE?enc:mic,
316            cmd_buffer);
317      free(cmd_buffer);
318    }
319  }
320  else {
321    htonl_bytes = htonl(bytes);
322    socket_write(conn, fd, &htonl_bytes, sizeof(htonl_bytes));
323    socket_write(conn, fd, buffer, bytes);
324  }
325  free(buffer);
326}
327
328static ssize_t sec_write(struct connectdata *conn, curl_socket_t fd,
329                         const char *buffer, size_t length)
330{
331  /* FIXME: Check for overflow */
332  ssize_t len = conn->buffer_size;
333  int tx = 0;
334
335  len -= conn->mech->overhead(conn->app_data, conn->data_prot, len);
336  if(len <= 0)
337    len = length;
338  while(length) {
339    if(len >= 0 || length < (size_t)len) {
340      /* FIXME: Check for overflow. */
341      len = length;
342    }
343    do_sec_send(conn, fd, buffer, len);
344    length -= len;
345    buffer += len;
346    tx += len;
347  }
348  return tx;
349}
350
351/* Matches Curl_send signature */
352static ssize_t sec_send(struct connectdata *conn, int sockindex,
353                        const void *buffer, size_t len, CURLcode *err)
354{
355  curl_socket_t fd = conn->sock[sockindex];
356  *err = CURLE_OK;
357  return sec_write(conn, fd, buffer, len);
358}
359
360int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
361                      enum protection_level level)
362{
363  /* decoded_len should be size_t or ssize_t but conn->mech->decode returns an
364     int */
365  int decoded_len;
366  char *buf;
367  int ret_code;
368
369  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
370
371  decoded_len = Curl_base64_decode(buffer + 4, (unsigned char **)&buf);
372  if(decoded_len <= 0) {
373    free(buf);
374    return -1;
375  }
376
377  decoded_len = conn->mech->decode(conn->app_data, buf, decoded_len,
378                                   level, conn);
379  if(decoded_len <= 0) {
380    free(buf);
381    return -1;
382  }
383
384  if(conn->data->set.verbose) {
385    buf[decoded_len] = '\n';
386    Curl_debug(conn->data, CURLINFO_HEADER_IN, buf, decoded_len + 1, conn);
387  }
388
389  buf[decoded_len] = '\0';
390  DEBUGASSERT(decoded_len > 3);
391  if(buf[3] == '-')
392    ret_code = 0;
393  else {
394    /* Check for error? */
395    sscanf(buf, "%d", &ret_code);
396  }
397
398  if(buf[decoded_len - 1] == '\n')
399    buf[decoded_len - 1] = '\0';
400  /* FIXME: Is |buffer| length always greater than |decoded_len|? */
401  strcpy(buffer, buf);
402  free(buf);
403  return ret_code;
404}
405
406/* FIXME: The error code returned here is never checked. */
407static int sec_set_protection_level(struct connectdata *conn)
408{
409  int code;
410  char* pbsz;
411  static unsigned int buffer_size = 1 << 20; /* 1048576 */
412  enum protection_level level = conn->request_data_prot;
413
414  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
415
416  if(!conn->sec_complete) {
417    infof(conn->data, "Trying to change the protection level after the"
418                      "completion of the data exchange.\n");
419    return -1;
420  }
421
422  /* Bail out if we try to set up the same level */
423  if(conn->data_prot == level)
424    return 0;
425
426  if(level) {
427    code = ftp_send_command(conn, "PBSZ %u", buffer_size);
428    if(code < 0)
429      return -1;
430
431    if(code/100 != 2) {
432      failf(conn->data, "Failed to set the protection's buffer size.");
433      return -1;
434    }
435    conn->buffer_size = buffer_size;
436
437    pbsz = strstr(conn->data->state.buffer, "PBSZ=");
438    if(pbsz) {
439      /* FIXME: Checks for errors in sscanf? */
440      sscanf(pbsz, "PBSZ=%u", &buffer_size);
441      if(buffer_size < conn->buffer_size)
442        conn->buffer_size = buffer_size;
443    }
444  }
445
446  /* Now try to negiociate the protection level. */
447  code = ftp_send_command(conn, "PROT %c", level_to_char(level));
448
449  if(code < 0)
450    return -1;
451
452  if(code/100 != 2) {
453    failf(conn->data, "Failed to set the protection level.");
454    return -1;
455  }
456
457  conn->data_prot = level;
458  if(level == PROT_PRIVATE)
459    conn->command_prot = level;
460
461  return 0;
462}
463
464int
465Curl_sec_request_prot(struct connectdata *conn, const char *level)
466{
467  enum protection_level l = name_to_level(level);
468  if(l == PROT_NONE)
469    return -1;
470  DEBUGASSERT(l > PROT_NONE && l < PROT_LAST);
471  conn->request_data_prot = l;
472  return 0;
473}
474
475static CURLcode choose_mech(struct connectdata *conn)
476{
477  int ret;
478  struct SessionHandle *data = conn->data;
479  const struct Curl_sec_client_mech * const *mech;
480  void *tmp_allocation;
481  const char *mech_name;
482
483  for(mech = mechs; (*mech); ++mech) {
484    mech_name = (*mech)->name;
485    /* We have no mechanism with a NULL name but keep this check */
486    DEBUGASSERT(mech_name != NULL);
487    if(mech_name == NULL) {
488      infof(data, "Skipping mechanism with empty name (%p)\n", mech);
489      continue;
490    }
491    tmp_allocation = realloc(conn->app_data, (*mech)->size);
492    if(tmp_allocation == NULL) {
493      failf(data, "Failed realloc of size %u", (*mech)->size);
494      mech = NULL;
495      return CURLE_OUT_OF_MEMORY;
496    }
497    conn->app_data = tmp_allocation;
498
499    if((*mech)->init) {
500      ret = (*mech)->init(conn->app_data);
501      if(ret != 0) {
502        infof(data, "Failed initialization for %s. Skipping it.\n", mech_name);
503        continue;
504      }
505    }
506
507    infof(data, "Trying mechanism %s...\n", mech_name);
508    ret = ftp_send_command(conn, "AUTH %s", mech_name);
509    if(ret < 0)
510      /* FIXME: This error is too generic but it is OK for now. */
511      return CURLE_COULDNT_CONNECT;
512
513    if(ret/100 != 3) {
514      switch(ret) {
515      case 504:
516        infof(data, "Mechanism %s is not supported by the server (server "
517                    "returned ftp code: 504).\n", mech_name);
518        break;
519      case 534:
520        infof(data, "Mechanism %s was rejected by the server (server returned "
521                    "ftp code: 534).\n", mech_name);
522        break;
523      default:
524        if(ret/100 == 5) {
525          infof(data, "server does not support the security extensions\n");
526          return CURLE_USE_SSL_FAILED;
527        }
528        break;
529      }
530      continue;
531    }
532
533    /* Authenticate */
534    ret = (*mech)->auth(conn->app_data, conn);
535
536    if(ret == AUTH_CONTINUE)
537      continue;
538    else if(ret != AUTH_OK) {
539      /* Mechanism has dumped the error to stderr, don't error here. */
540      return -1;
541    }
542    DEBUGASSERT(ret == AUTH_OK);
543
544    conn->mech = *mech;
545    conn->sec_complete = 1;
546    conn->recv[FIRSTSOCKET] = sec_recv;
547    conn->send[FIRSTSOCKET] = sec_send;
548    conn->recv[SECONDARYSOCKET] = sec_recv;
549    conn->send[SECONDARYSOCKET] = sec_send;
550    conn->command_prot = PROT_SAFE;
551    /* Set the requested protection level */
552    /* BLOCKING */
553    (void)sec_set_protection_level(conn);
554    break;
555  }
556
557  return mech != NULL ? CURLE_OK : CURLE_FAILED_INIT;
558}
559
560CURLcode
561Curl_sec_login(struct connectdata *conn)
562{
563  return choose_mech(conn);
564}
565
566
567void
568Curl_sec_end(struct connectdata *conn)
569{
570  if(conn->mech != NULL && conn->mech->end)
571    conn->mech->end(conn->app_data);
572  if(conn->app_data) {
573    free(conn->app_data);
574    conn->app_data = NULL;
575  }
576  if(conn->in_buffer.data) {
577    free(conn->in_buffer.data);
578    conn->in_buffer.data = NULL;
579    conn->in_buffer.size = 0;
580    conn->in_buffer.index = 0;
581    /* FIXME: Is this really needed? */
582    conn->in_buffer.eof_flag = 0;
583  }
584  conn->sec_complete = 0;
585  conn->data_prot = PROT_CLEAR;
586  conn->mech = NULL;
587}
588
589#endif /* HAVE_KRB4 || HAVE_GSSAPI */
590
591#endif /* CURL_DISABLE_FTP */
592