1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
3 2008 Free Software Foundation, Inc.
4 Originally contributed by Christian Fraenkel.
6 This file is part of GNU Wget.
8 GNU Wget is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 GNU Wget is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with Wget. If not, see <http://www.gnu.org/licenses/>.
21 Additional permission under GNU GPL version 3 section 7
23 If you modify this program, or any covered work, by linking or
24 combining it with the OpenSSL project's OpenSSL library (or a
25 modified version of that library), containing parts covered by the
26 terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
27 grants you additional permission to convey the resulting work.
28 Corresponding Source for a non-source form of such a combination
29 shall include the source code for the parts of OpenSSL used as well
30 as that of the covered work. */
41 #include <openssl/ssl.h>
42 #include <openssl/x509.h>
43 #include <openssl/err.h>
44 #include <openssl/rand.h>
52 /* Application-wide SSL context. This is common to all SSL
54 static SSL_CTX *ssl_ctx;
56 /* Initialize the SSL's PRNG using various methods. */
62 const char *random_file;
65 /* The PRNG has been seeded; no further action is necessary. */
68 /* Seed from a file specified by the user. This will be the file
69 specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it
72 random_file = opt.random_file;
75 /* Get the random file name using RAND_file_name. */
77 random_file = RAND_file_name (namebuf, sizeof (namebuf));
80 if (random_file && *random_file)
81 /* Seed at most 16k (apparently arbitrary value borrowed from
82 curl) from random file. */
83 RAND_load_file (random_file, 16384);
88 /* Get random data from EGD if opt.egd_file was used. */
89 if (opt.egd_file && *opt.egd_file)
90 RAND_egd (opt.egd_file);
96 /* Under Windows, we can try to seed the PRNG using screen content.
97 This may or may not work, depending on whether we'll calling Wget
105 #if 0 /* don't do this by default */
109 /* Still not random enough, presumably because neither /dev/random
110 nor EGD were available. Try to seed OpenSSL's PRNG with libc
111 PRNG. This is cryptographically weak and defeats the purpose
112 of using OpenSSL, which is why it is highly discouraged. */
114 logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n"));
116 while (RAND_status () == 0 && maxrand-- > 0)
118 unsigned char rnd = random_number (256);
119 RAND_seed (&rnd, sizeof (rnd));
125 /* Print errors in the OpenSSL error stack. */
131 while ((err = ERR_get_error ()) != 0)
132 logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL));
135 /* Convert keyfile type as used by options.h to a type as accepted by
136 SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file.
138 (options.h intentionally doesn't use values from openssl/ssl.h so
139 it doesn't depend specifically on OpenSSL for SSL functionality.) */
142 key_type_to_ssl_type (enum keyfile_type type)
147 return SSL_FILETYPE_PEM;
149 return SSL_FILETYPE_ASN1;
155 /* Create an SSL Context and set default paths etc. Called the first
156 time an HTTP download is attempted.
158 Returns true on success, false otherwise. */
166 /* The SSL has already been initialized. */
169 /* Init the PRNG. If that fails, bail out. */
171 if (RAND_status () != 1)
173 logprintf (LOG_NOTQUIET,
174 _("Could not seed PRNG; consider using --random-file.\n"));
179 SSL_load_error_strings ();
180 SSLeay_add_all_algorithms ();
181 SSLeay_add_ssl_algorithms ();
183 switch (opt.secure_protocol)
185 case secure_protocol_auto:
186 meth = SSLv23_client_method ();
188 case secure_protocol_sslv2:
189 meth = SSLv2_client_method ();
191 case secure_protocol_sslv3:
192 meth = SSLv3_client_method ();
194 case secure_protocol_tlsv1:
195 meth = TLSv1_client_method ();
201 ssl_ctx = SSL_CTX_new (meth);
205 SSL_CTX_set_default_verify_paths (ssl_ctx);
206 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
208 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
209 certificate is invalid. We verify the certificate separately in
210 ssl_check_certificate, which provides much better diagnostics
211 than examining the error stack after a failed SSL_connect. */
212 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
215 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
216 key_type_to_ssl_type (opt.cert_type))
220 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
221 key_type_to_ssl_type (opt.private_key_type))
225 /* Since fd_write unconditionally assumes partial writes (and
226 handles them correctly), allow them in OpenSSL. */
227 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
229 /* The OpenSSL library can handle renegotiations automatically, so
231 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
237 SSL_CTX_free (ssl_ctx);
242 struct openssl_transport_context {
243 SSL *conn; /* SSL connection handle */
244 char *last_error; /* last error printed with openssl_errstr */
248 openssl_read (int fd, char *buf, int bufsize, void *arg)
251 struct openssl_transport_context *ctx = arg;
252 SSL *conn = ctx->conn;
254 ret = SSL_read (conn, buf, bufsize);
256 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
262 openssl_write (int fd, char *buf, int bufsize, void *arg)
265 struct openssl_transport_context *ctx = arg;
266 SSL *conn = ctx->conn;
268 ret = SSL_write (conn, buf, bufsize);
270 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
276 openssl_poll (int fd, double timeout, int wait_for, void *arg)
278 struct openssl_transport_context *ctx = arg;
279 SSL *conn = ctx->conn;
282 if (SSL_pending (conn))
284 return select_fd (fd, timeout, wait_for);
288 openssl_peek (int fd, char *buf, int bufsize, void *arg)
291 struct openssl_transport_context *ctx = arg;
292 SSL *conn = ctx->conn;
294 ret = SSL_peek (conn, buf, bufsize);
296 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
302 openssl_errstr (int fd, void *arg)
304 struct openssl_transport_context *ctx = arg;
305 unsigned long errcode;
309 /* If there are no SSL-specific errors, just return NULL. */
310 if ((errcode = ERR_get_error ()) == 0)
313 /* Get rid of previous contents of ctx->last_error, if any. */
314 xfree_null (ctx->last_error);
316 /* Iterate over OpenSSL's error stack and accumulate errors in the
317 last_error buffer, separated by "; ". This is better than using
318 a static buffer, which *always* takes up space (and has to be
319 large, to fit more than one error message), whereas these
320 allocations are only performed when there is an actual error. */
324 const char *str = ERR_error_string (errcode, NULL);
325 int len = strlen (str);
327 /* Allocate space for the existing message, plus two more chars
328 for the "; " separator and one for the terminating \0. */
329 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
330 memcpy (errmsg + msglen, str, len);
333 /* Get next error and bail out if there are no more. */
334 errcode = ERR_get_error ();
338 errmsg[msglen++] = ';';
339 errmsg[msglen++] = ' ';
341 errmsg[msglen] = '\0';
343 /* Store the error in ctx->last_error where openssl_close will
344 eventually find it and free it. */
345 ctx->last_error = errmsg;
351 openssl_close (int fd, void *arg)
353 struct openssl_transport_context *ctx = arg;
354 SSL *conn = ctx->conn;
358 xfree_null (ctx->last_error);
361 #if defined(WINDOWS) || defined(MSDOS)
367 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
370 /* openssl_transport is the singleton that describes the SSL transport
371 methods provided by this file. */
373 static struct transport_implementation openssl_transport = {
374 openssl_read, openssl_write, openssl_poll,
375 openssl_peek, openssl_errstr, openssl_close
378 /* Perform the SSL handshake on file descriptor FD, which is assumed
379 to be connected to an SSL server. The SSL handle provided by
380 OpenSSL is registered with the file descriptor FD using
381 fd_register_transport, so that subsequent calls to fd_read,
382 fd_write, etc., will use the corresponding SSL functions.
384 Returns true on success, false on failure. */
390 struct openssl_transport_context *ctx;
392 DEBUGP (("Initiating SSL handshake.\n"));
394 assert (ssl_ctx != NULL);
395 conn = SSL_new (ssl_ctx);
398 if (!SSL_set_fd (conn, fd))
400 SSL_set_connect_state (conn);
401 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
404 ctx = xnew0 (struct openssl_transport_context);
407 /* Register FD with Wget's transport layer, i.e. arrange that our
408 functions are used for reading, writing, and polling. */
409 fd_register_transport (fd, &openssl_transport, ctx);
410 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
411 fd, PTR_FORMAT (conn)));
415 DEBUGP (("SSL handshake failed.\n"));
422 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
424 /* Return true is STRING (case-insensitively) matches PATTERN, false
425 otherwise. The recognized wildcard character is "*", which matches
426 any character in STRING except ".". Any number of the "*" wildcard
427 may be present in the pattern.
429 This is used to match of hosts as indicated in rfc2818: "Names may
430 contain the wildcard character * which is considered to match any
431 single domain name component or component fragment. E.g., *.a.com
432 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
433 not bar.com [or foo.bar.com]."
435 If the pattern contain no wildcards, pattern_match(a, b) is
436 equivalent to !strcasecmp(a, b). */
439 pattern_match (const char *pattern, const char *string)
441 const char *p = pattern, *n = string;
443 for (; (c = TOLOWER (*p++)) != '\0'; n++)
446 for (c = TOLOWER (*p); c == '*'; c = TOLOWER (*++p))
448 for (; *n != '\0'; n++)
449 if (TOLOWER (*n) == c && pattern_match (p, n))
451 #ifdef ASTERISK_EXCLUDES_DOT
459 if (c != TOLOWER (*n))
465 /* Verify the validity of the certificate presented by the server.
466 Also check that the "common name" of the server, as presented by
467 its certificate, corresponds to HOST. (HOST typically comes from
468 the URL and is what the user thinks he's connecting to.)
470 This assumes that ssl_connect has successfully finished, i.e. that
471 the SSL handshake has been performed and that FD is connected to an
474 If opt.check_cert is true (the default), this returns 1 if the
475 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
476 function always returns 1, but should still be called because it
477 warns the user about any problems with the certificate. */
480 ssl_check_certificate (int fd, const char *host)
483 char common_name[256];
487 /* If the user has specified --no-check-cert, we still want to warn
488 him about problems with the server's certificate. */
489 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
491 struct openssl_transport_context *ctx = fd_transport_context (fd);
492 SSL *conn = ctx->conn;
493 assert (conn != NULL);
495 cert = SSL_get_peer_certificate (conn);
498 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
499 severity, escnonprint (host));
501 goto no_cert; /* must bail out since CERT is NULL */
506 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
507 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
508 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
509 escnonprint (subject), escnonprint (issuer)));
510 OPENSSL_free (subject);
511 OPENSSL_free (issuer);
514 vresult = SSL_get_verify_result (conn);
515 if (vresult != X509_V_OK)
517 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
518 logprintf (LOG_NOTQUIET,
519 _("%s: cannot verify %s's certificate, issued by `%s':\n"),
520 severity, escnonprint (host), escnonprint (issuer));
521 /* Try to print more user-friendly (and translated) messages for
522 the frequent verification errors. */
525 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
526 logprintf (LOG_NOTQUIET,
527 _(" Unable to locally verify the issuer's authority.\n"));
529 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
530 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
531 logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
533 case X509_V_ERR_CERT_NOT_YET_VALID:
534 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
536 case X509_V_ERR_CERT_HAS_EXPIRED:
537 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
540 /* For the less frequent error strings, simply provide the
541 OpenSSL error message. */
542 logprintf (LOG_NOTQUIET, " %s\n",
543 X509_verify_cert_error_string (vresult));
546 /* Fall through, so that the user is warned about *all* issues
547 with the cert (important with --no-check-certificate.) */
550 /* Check that HOST matches the common name in the certificate.
551 #### The following remains to be done:
553 - It should use dNSName/ipAddress subjectAltName extensions if
554 available; according to rfc2818: "If a subjectAltName extension
555 of type dNSName is present, that MUST be used as the identity."
557 - When matching against common names, it should loop over all
558 common names and choose the most specific one, i.e. the last
559 one, not the first one, which the current code picks.
561 - Ensure that ASN1 strings from the certificate are encoded as
562 UTF-8 which can be meaningfully compared to HOST. */
564 common_name[0] = '\0';
565 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
566 NID_commonName, common_name, sizeof (common_name));
567 if (!pattern_match (common_name, host))
569 logprintf (LOG_NOTQUIET, _("\
570 %s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
571 severity, escnonprint (common_name), escnonprint (host));
576 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
577 escnonprint (host)));
581 if (opt.check_cert && !success)
582 logprintf (LOG_NOTQUIET, _("\
583 To connect to %s insecurely, use `--no-check-certificate'.\n"),
586 /* Allow --no-check-cert to disable certificate checking. */
587 return opt.check_cert ? success : true;