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#ifdef HAVE_NETDB_H
50#include <netdb.h>
51#endif
52
53#ifdef HAVE_UNISTD_H
54#include <unistd.h>
55#endif
56
57#ifdef HAVE_LIMITS_H
58#include <limits.h>
59#endif
60
61#include "urldata.h"
62#include "curl_base64.h"
63#include "curl_memory.h"
64#include "krb4.h"
65#include "ftp.h"
66#include "sendf.h"
67#include "rawstr.h"
68#include "warnless.h"
69
70/* The last #include file should be: */
71#include "memdebug.h"
72
73static const struct {
74  enum protection_level level;
75  const char *name;
76} level_names[] = {
77  { PROT_CLEAR, "clear" },
78  { PROT_SAFE, "safe" },
79  { PROT_CONFIDENTIAL, "confidential" },
80  { PROT_PRIVATE, "private" }
81};
82
83static enum protection_level
84name_to_level(const char *name)
85{
86  int i;
87  for(i = 0; i < (int)sizeof(level_names)/(int)sizeof(level_names[0]); i++)
88    if(checkprefix(name, level_names[i].name))
89      return level_names[i].level;
90  return PROT_NONE;
91}
92
93/* Convert a protocol |level| to its char representation.
94   We take an int to catch programming mistakes. */
95static char level_to_char(int level) {
96  switch(level) {
97  case PROT_CLEAR:
98    return 'C';
99  case PROT_SAFE:
100    return 'S';
101  case PROT_CONFIDENTIAL:
102    return 'E';
103  case PROT_PRIVATE:
104    return 'P';
105  case PROT_CMD:
106    /* Fall through */
107  default:
108    /* Those 2 cases should not be reached! */
109    break;
110  }
111  DEBUGASSERT(0);
112  /* Default to the most secure alternative. */
113  return 'P';
114}
115
116static const struct Curl_sec_client_mech * const mechs[] = {
117#if defined(HAVE_GSSAPI)
118  &Curl_krb5_client_mech,
119#endif
120#if defined(HAVE_KRB4)
121  &Curl_krb4_client_mech,
122#endif
123  NULL
124};
125
126/* Send an FTP command defined by |message| and the optional arguments. The
127   function returns the ftp_code. If an error occurs, -1 is returned. */
128static int ftp_send_command(struct connectdata *conn, const char *message, ...)
129{
130  int ftp_code;
131  ssize_t nread;
132  va_list args;
133  char print_buffer[50];
134
135  va_start(args, message);
136  vsnprintf(print_buffer, sizeof(print_buffer), message, args);
137  va_end(args);
138
139  if(Curl_ftpsendf(conn, print_buffer) != CURLE_OK) {
140    ftp_code = -1;
141  }
142  else {
143    if(Curl_GetFTPResponse(&nread, conn, &ftp_code) != CURLE_OK)
144      ftp_code = -1;
145  }
146
147  (void)nread; /* Unused */
148  return ftp_code;
149}
150
151/* Read |len| from the socket |fd| and store it in |to|. Return a CURLcode
152   saying whether an error occurred or CURLE_OK if |len| was read. */
153static CURLcode
154socket_read(curl_socket_t fd, void *to, size_t len)
155{
156  char *to_p = to;
157  CURLcode code;
158  ssize_t nread;
159
160  while(len > 0) {
161    code = Curl_read_plain(fd, to_p, len, &nread);
162    if(code == CURLE_OK) {
163      len -= nread;
164      to_p += nread;
165    }
166    else {
167      /* FIXME: We are doing a busy wait */
168      if(code == CURLE_AGAIN)
169        continue;
170      return code;
171    }
172  }
173  return CURLE_OK;
174}
175
176
177/* Write |len| bytes from the buffer |to| to the socket |fd|. Return a
178   CURLcode saying whether an error occurred or CURLE_OK if |len| was
179   written. */
180static CURLcode
181socket_write(struct connectdata *conn, curl_socket_t fd, const void *to,
182             size_t len)
183{
184  const char *to_p = to;
185  CURLcode code;
186  ssize_t written;
187
188  while(len > 0) {
189    code = Curl_write_plain(conn, fd, to_p, len, &written);
190    if(code == CURLE_OK) {
191      len -= written;
192      to_p += written;
193    }
194    else {
195      /* FIXME: We are doing a busy wait */
196      if(code == CURLE_AGAIN)
197        continue;
198      return code;
199    }
200  }
201  return CURLE_OK;
202}
203
204static CURLcode read_data(struct connectdata *conn,
205                          curl_socket_t fd,
206                          struct krb4buffer *buf)
207{
208  int len;
209  void* tmp;
210  CURLcode ret;
211
212  ret = socket_read(fd, &len, sizeof(len));
213  if(ret != CURLE_OK)
214    return ret;
215
216  len = ntohl(len);
217  tmp = realloc(buf->data, len);
218  if(tmp == NULL)
219    return CURLE_OUT_OF_MEMORY;
220
221  buf->data = tmp;
222  ret = socket_read(fd, buf->data, len);
223  if(ret != CURLE_OK)
224    return ret;
225  buf->size = conn->mech->decode(conn->app_data, buf->data, len,
226                                 conn->data_prot, conn);
227  buf->index = 0;
228  return CURLE_OK;
229}
230
231static size_t
232buffer_read(struct krb4buffer *buf, void *data, size_t len)
233{
234  if(buf->size - buf->index < len)
235    len = buf->size - buf->index;
236  memcpy(data, (char*)buf->data + buf->index, len);
237  buf->index += len;
238  return len;
239}
240
241/* Matches Curl_recv signature */
242static ssize_t sec_recv(struct connectdata *conn, int sockindex,
243                        char *buffer, size_t len, CURLcode *err)
244{
245  size_t bytes_read;
246  size_t total_read = 0;
247  curl_socket_t fd = conn->sock[sockindex];
248
249  *err = CURLE_OK;
250
251  /* Handle clear text response. */
252  if(conn->sec_complete == 0 || conn->data_prot == PROT_CLEAR)
253      return read(fd, buffer, len);
254
255  if(conn->in_buffer.eof_flag) {
256    conn->in_buffer.eof_flag = 0;
257    return 0;
258  }
259
260  bytes_read = buffer_read(&conn->in_buffer, buffer, len);
261  len -= bytes_read;
262  total_read += bytes_read;
263  buffer += bytes_read;
264
265  while(len > 0) {
266    if(read_data(conn, fd, &conn->in_buffer) != CURLE_OK)
267      return -1;
268    if(conn->in_buffer.size == 0) {
269      if(bytes_read > 0)
270        conn->in_buffer.eof_flag = 1;
271      return bytes_read;
272    }
273    bytes_read = buffer_read(&conn->in_buffer, buffer, len);
274    len -= bytes_read;
275    total_read += bytes_read;
276    buffer += bytes_read;
277  }
278  /* FIXME: Check for overflow */
279  return total_read;
280}
281
282/* Send |length| bytes from |from| to the |fd| socket taking care of encoding
283   and negociating with the server. |from| can be NULL. */
284/* FIXME: We don't check for errors nor report any! */
285static void do_sec_send(struct connectdata *conn, curl_socket_t fd,
286                        const char *from, int length)
287{
288  int bytes, htonl_bytes; /* 32-bit integers for htonl */
289  char *buffer = NULL;
290  char *cmd_buffer;
291  size_t cmd_size = 0;
292  CURLcode error;
293  enum protection_level prot_level = conn->data_prot;
294  bool iscmd = (prot_level == PROT_CMD)?TRUE:FALSE;
295
296  DEBUGASSERT(prot_level > PROT_NONE && prot_level < PROT_LAST);
297
298  if(iscmd) {
299    if(!strncmp(from, "PASS ", 5) || !strncmp(from, "ACCT ", 5))
300      prot_level = PROT_PRIVATE;
301    else
302      prot_level = conn->command_prot;
303  }
304  bytes = conn->mech->encode(conn->app_data, from, length, prot_level,
305                             (void**)&buffer, conn);
306  if(!buffer || bytes <= 0)
307    return; /* error */
308
309  if(iscmd) {
310    error = Curl_base64_encode(conn->data, buffer, curlx_sitouz(bytes),
311                               &cmd_buffer, &cmd_size);
312    if(error) {
313      free(buffer);
314      return; /* error */
315    }
316    if(cmd_size > 0) {
317      static const char *enc = "ENC ";
318      static const char *mic = "MIC ";
319      if(prot_level == PROT_PRIVATE)
320        socket_write(conn, fd, enc, 4);
321      else
322        socket_write(conn, fd, mic, 4);
323
324      socket_write(conn, fd, cmd_buffer, cmd_size);
325      socket_write(conn, fd, "\r\n", 2);
326      infof(conn->data, "Send: %s%s\n", prot_level == PROT_PRIVATE?enc:mic,
327            cmd_buffer);
328      free(cmd_buffer);
329    }
330  }
331  else {
332    htonl_bytes = htonl(bytes);
333    socket_write(conn, fd, &htonl_bytes, sizeof(htonl_bytes));
334    socket_write(conn, fd, buffer, curlx_sitouz(bytes));
335  }
336  free(buffer);
337}
338
339static ssize_t sec_write(struct connectdata *conn, curl_socket_t fd,
340                         const char *buffer, size_t length)
341{
342  /* FIXME: Check for overflow */
343  ssize_t len = conn->buffer_size;
344  int tx = 0;
345
346  len -= conn->mech->overhead(conn->app_data, conn->data_prot, len);
347  if(len <= 0)
348    len = length;
349  while(length) {
350    if(len >= 0 || length < (size_t)len) {
351      /* FIXME: Check for overflow. */
352      len = length;
353    }
354    do_sec_send(conn, fd, buffer, len);
355    length -= len;
356    buffer += len;
357    tx += len;
358  }
359  return tx;
360}
361
362/* Matches Curl_send signature */
363static ssize_t sec_send(struct connectdata *conn, int sockindex,
364                        const void *buffer, size_t len, CURLcode *err)
365{
366  curl_socket_t fd = conn->sock[sockindex];
367  *err = CURLE_OK;
368  return sec_write(conn, fd, buffer, len);
369}
370
371int Curl_sec_read_msg(struct connectdata *conn, char *buffer,
372                      enum protection_level level)
373{
374  /* decoded_len should be size_t or ssize_t but conn->mech->decode returns an
375     int */
376  int decoded_len;
377  char *buf;
378  int ret_code;
379  size_t decoded_sz = 0;
380  CURLcode error;
381
382  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
383
384  error = Curl_base64_decode(buffer + 4, (unsigned char **)&buf, &decoded_sz);
385  if(error || decoded_sz == 0)
386    return -1;
387
388  if(decoded_sz > (size_t)INT_MAX) {
389    free(buf);
390    return -1;
391  }
392  decoded_len = curlx_uztosi(decoded_sz);
393
394  decoded_len = conn->mech->decode(conn->app_data, buf, decoded_len,
395                                   level, conn);
396  if(decoded_len <= 0) {
397    free(buf);
398    return -1;
399  }
400
401  if(conn->data->set.verbose) {
402    buf[decoded_len] = '\n';
403    Curl_debug(conn->data, CURLINFO_HEADER_IN, buf, decoded_len + 1, conn);
404  }
405
406  buf[decoded_len] = '\0';
407  DEBUGASSERT(decoded_len > 3);
408  if(buf[3] == '-')
409    ret_code = 0;
410  else {
411    /* Check for error? */
412    sscanf(buf, "%d", &ret_code);
413  }
414
415  if(buf[decoded_len - 1] == '\n')
416    buf[decoded_len - 1] = '\0';
417  /* FIXME: Is |buffer| length always greater than |decoded_len|? */
418  strcpy(buffer, buf);
419  free(buf);
420  return ret_code;
421}
422
423/* FIXME: The error code returned here is never checked. */
424static int sec_set_protection_level(struct connectdata *conn)
425{
426  int code;
427  char* pbsz;
428  static unsigned int buffer_size = 1 << 20; /* 1048576 */
429  enum protection_level level = conn->request_data_prot;
430
431  DEBUGASSERT(level > PROT_NONE && level < PROT_LAST);
432
433  if(!conn->sec_complete) {
434    infof(conn->data, "Trying to change the protection level after the"
435                      "completion of the data exchange.\n");
436    return -1;
437  }
438
439  /* Bail out if we try to set up the same level */
440  if(conn->data_prot == level)
441    return 0;
442
443  if(level) {
444    code = ftp_send_command(conn, "PBSZ %u", buffer_size);
445    if(code < 0)
446      return -1;
447
448    if(code/100 != 2) {
449      failf(conn->data, "Failed to set the protection's buffer size.");
450      return -1;
451    }
452    conn->buffer_size = buffer_size;
453
454    pbsz = strstr(conn->data->state.buffer, "PBSZ=");
455    if(pbsz) {
456      /* FIXME: Checks for errors in sscanf? */
457      sscanf(pbsz, "PBSZ=%u", &buffer_size);
458      if(buffer_size < conn->buffer_size)
459        conn->buffer_size = buffer_size;
460    }
461  }
462
463  /* Now try to negiociate the protection level. */
464  code = ftp_send_command(conn, "PROT %c", level_to_char(level));
465
466  if(code < 0)
467    return -1;
468
469  if(code/100 != 2) {
470    failf(conn->data, "Failed to set the protection level.");
471    return -1;
472  }
473
474  conn->data_prot = level;
475  if(level == PROT_PRIVATE)
476    conn->command_prot = level;
477
478  return 0;
479}
480
481int
482Curl_sec_request_prot(struct connectdata *conn, const char *level)
483{
484  enum protection_level l = name_to_level(level);
485  if(l == PROT_NONE)
486    return -1;
487  DEBUGASSERT(l > PROT_NONE && l < PROT_LAST);
488  conn->request_data_prot = l;
489  return 0;
490}
491
492static CURLcode choose_mech(struct connectdata *conn)
493{
494  int ret;
495  struct SessionHandle *data = conn->data;
496  const struct Curl_sec_client_mech * const *mech;
497  void *tmp_allocation;
498  const char *mech_name;
499
500  for(mech = mechs; (*mech); ++mech) {
501    mech_name = (*mech)->name;
502    /* We have no mechanism with a NULL name but keep this check */
503    DEBUGASSERT(mech_name != NULL);
504    if(mech_name == NULL) {
505      infof(data, "Skipping mechanism with empty name (%p)\n", mech);
506      continue;
507    }
508    tmp_allocation = realloc(conn->app_data, (*mech)->size);
509    if(tmp_allocation == NULL) {
510      failf(data, "Failed realloc of size %u", (*mech)->size);
511      mech = NULL;
512      return CURLE_OUT_OF_MEMORY;
513    }
514    conn->app_data = tmp_allocation;
515
516    if((*mech)->init) {
517      ret = (*mech)->init(conn->app_data);
518      if(ret != 0) {
519        infof(data, "Failed initialization for %s. Skipping it.\n", mech_name);
520        continue;
521      }
522    }
523
524    infof(data, "Trying mechanism %s...\n", mech_name);
525    ret = ftp_send_command(conn, "AUTH %s", mech_name);
526    if(ret < 0)
527      /* FIXME: This error is too generic but it is OK for now. */
528      return CURLE_COULDNT_CONNECT;
529
530    if(ret/100 != 3) {
531      switch(ret) {
532      case 504:
533        infof(data, "Mechanism %s is not supported by the server (server "
534                    "returned ftp code: 504).\n", mech_name);
535        break;
536      case 534:
537        infof(data, "Mechanism %s was rejected by the server (server returned "
538                    "ftp code: 534).\n", mech_name);
539        break;
540      default:
541        if(ret/100 == 5) {
542          infof(data, "server does not support the security extensions\n");
543          return CURLE_USE_SSL_FAILED;
544        }
545        break;
546      }
547      continue;
548    }
549
550    /* Authenticate */
551    ret = (*mech)->auth(conn->app_data, conn);
552
553    if(ret == AUTH_CONTINUE)
554      continue;
555    else if(ret != AUTH_OK) {
556      /* Mechanism has dumped the error to stderr, don't error here. */
557      return -1;
558    }
559    DEBUGASSERT(ret == AUTH_OK);
560
561    conn->mech = *mech;
562    conn->sec_complete = 1;
563    conn->recv[FIRSTSOCKET] = sec_recv;
564    conn->send[FIRSTSOCKET] = sec_send;
565    conn->recv[SECONDARYSOCKET] = sec_recv;
566    conn->send[SECONDARYSOCKET] = sec_send;
567    conn->command_prot = PROT_SAFE;
568    /* Set the requested protection level */
569    /* BLOCKING */
570    (void)sec_set_protection_level(conn);
571    break;
572  }
573
574  return mech != NULL ? CURLE_OK : CURLE_FAILED_INIT;
575}
576
577CURLcode
578Curl_sec_login(struct connectdata *conn)
579{
580  return choose_mech(conn);
581}
582
583
584void
585Curl_sec_end(struct connectdata *conn)
586{
587  if(conn->mech != NULL && conn->mech->end)
588    conn->mech->end(conn->app_data);
589  if(conn->app_data) {
590    free(conn->app_data);
591    conn->app_data = NULL;
592  }
593  if(conn->in_buffer.data) {
594    free(conn->in_buffer.data);
595    conn->in_buffer.data = NULL;
596    conn->in_buffer.size = 0;
597    conn->in_buffer.index = 0;
598    /* FIXME: Is this really needed? */
599    conn->in_buffer.eof_flag = 0;
600  }
601  conn->sec_complete = 0;
602  conn->data_prot = PROT_CLEAR;
603  conn->mech = NULL;
604}
605
606#endif /* HAVE_KRB4 || HAVE_GSSAPI */
607
608#endif /* CURL_DISABLE_FTP */
609