1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
3 2009, 2010, 2011 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. */
39 #include <openssl/ssl.h>
40 #include <openssl/x509v3.h>
41 #include <openssl/err.h>
42 #include <openssl/rand.h>
53 /* Application-wide SSL context. This is common to all SSL
55 static SSL_CTX *ssl_ctx;
57 /* Initialize the SSL's PRNG using various methods. */
63 const char *random_file;
66 /* The PRNG has been seeded; no further action is necessary. */
69 /* Seed from a file specified by the user. This will be the file
70 specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it
73 random_file = opt.random_file;
76 /* Get the random file name using RAND_file_name. */
78 random_file = RAND_file_name (namebuf, sizeof (namebuf));
81 if (random_file && *random_file)
82 /* Seed at most 16k (apparently arbitrary value borrowed from
83 curl) from random file. */
84 RAND_load_file (random_file, 16384);
89 /* Get random data from EGD if opt.egd_file was used. */
90 if (opt.egd_file && *opt.egd_file)
91 RAND_egd (opt.egd_file);
97 /* Under Windows, we can try to seed the PRNG using screen content.
98 This may or may not work, depending on whether we'll calling Wget
106 #if 0 /* don't do this by default */
110 /* Still not random enough, presumably because neither /dev/random
111 nor EGD were available. Try to seed OpenSSL's PRNG with libc
112 PRNG. This is cryptographically weak and defeats the purpose
113 of using OpenSSL, which is why it is highly discouraged. */
115 logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n"));
117 while (RAND_status () == 0 && maxrand-- > 0)
119 unsigned char rnd = random_number (256);
120 RAND_seed (&rnd, sizeof (rnd));
126 /* Print errors in the OpenSSL error stack. */
132 while ((err = ERR_get_error ()) != 0)
133 logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL));
136 /* Convert keyfile type as used by options.h to a type as accepted by
137 SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file.
139 (options.h intentionally doesn't use values from openssl/ssl.h so
140 it doesn't depend specifically on OpenSSL for SSL functionality.) */
143 key_type_to_ssl_type (enum keyfile_type type)
148 return SSL_FILETYPE_PEM;
150 return SSL_FILETYPE_ASN1;
156 /* Create an SSL Context and set default paths etc. Called the first
157 time an HTTP download is attempted.
159 Returns true on success, false otherwise. */
164 SSL_METHOD const *meth;
167 /* The SSL has already been initialized. */
170 /* Init the PRNG. If that fails, bail out. */
172 if (RAND_status () != 1)
174 logprintf (LOG_NOTQUIET,
175 _("Could not seed PRNG; consider using --random-file.\n"));
180 SSL_load_error_strings ();
181 SSLeay_add_all_algorithms ();
182 SSLeay_add_ssl_algorithms ();
184 switch (opt.secure_protocol)
186 case secure_protocol_auto:
187 meth = SSLv23_client_method ();
189 #ifndef OPENSSL_NO_SSL2
190 case secure_protocol_sslv2:
191 meth = SSLv2_client_method ();
194 case secure_protocol_sslv3:
195 meth = SSLv3_client_method ();
197 case secure_protocol_tlsv1:
198 meth = TLSv1_client_method ();
204 /* The type cast below accommodates older OpenSSL versions (0.9.8)
205 where SSL_CTX_new() is declared without a "const" argument. */
206 ssl_ctx = SSL_CTX_new ((SSL_METHOD *)meth);
210 SSL_CTX_set_default_verify_paths (ssl_ctx);
211 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
213 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
214 certificate is invalid. We verify the certificate separately in
215 ssl_check_certificate, which provides much better diagnostics
216 than examining the error stack after a failed SSL_connect. */
217 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
219 /* Use the private key from the cert file unless otherwise specified. */
220 if (opt.cert_file && !opt.private_key)
222 opt.private_key = opt.cert_file;
223 opt.private_key_type = opt.cert_type;
227 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
228 key_type_to_ssl_type (opt.cert_type))
232 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
233 key_type_to_ssl_type (opt.private_key_type))
237 /* Since fd_write unconditionally assumes partial writes (and
238 handles them correctly), allow them in OpenSSL. */
239 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
241 /* The OpenSSL library can handle renegotiations automatically, so
243 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
249 SSL_CTX_free (ssl_ctx);
254 struct openssl_transport_context {
255 SSL *conn; /* SSL connection handle */
256 char *last_error; /* last error printed with openssl_errstr */
260 openssl_read (int fd, char *buf, int bufsize, void *arg)
263 struct openssl_transport_context *ctx = arg;
264 SSL *conn = ctx->conn;
266 ret = SSL_read (conn, buf, bufsize);
268 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
275 openssl_write (int fd, char *buf, int bufsize, void *arg)
278 struct openssl_transport_context *ctx = arg;
279 SSL *conn = ctx->conn;
281 ret = SSL_write (conn, buf, bufsize);
283 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
289 openssl_poll (int fd, double timeout, int wait_for, void *arg)
291 struct openssl_transport_context *ctx = arg;
292 SSL *conn = ctx->conn;
293 if (SSL_pending (conn))
297 return select_fd (fd, timeout, wait_for);
301 openssl_peek (int fd, char *buf, int bufsize, void *arg)
304 struct openssl_transport_context *ctx = arg;
305 SSL *conn = ctx->conn;
306 if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg))
309 ret = SSL_peek (conn, buf, bufsize);
311 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
317 openssl_errstr (int fd, void *arg)
319 struct openssl_transport_context *ctx = arg;
320 unsigned long errcode;
324 /* If there are no SSL-specific errors, just return NULL. */
325 if ((errcode = ERR_get_error ()) == 0)
328 /* Get rid of previous contents of ctx->last_error, if any. */
329 xfree_null (ctx->last_error);
331 /* Iterate over OpenSSL's error stack and accumulate errors in the
332 last_error buffer, separated by "; ". This is better than using
333 a static buffer, which *always* takes up space (and has to be
334 large, to fit more than one error message), whereas these
335 allocations are only performed when there is an actual error. */
339 const char *str = ERR_error_string (errcode, NULL);
340 int len = strlen (str);
342 /* Allocate space for the existing message, plus two more chars
343 for the "; " separator and one for the terminating \0. */
344 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
345 memcpy (errmsg + msglen, str, len);
348 /* Get next error and bail out if there are no more. */
349 errcode = ERR_get_error ();
353 errmsg[msglen++] = ';';
354 errmsg[msglen++] = ' ';
356 errmsg[msglen] = '\0';
358 /* Store the error in ctx->last_error where openssl_close will
359 eventually find it and free it. */
360 ctx->last_error = errmsg;
366 openssl_close (int fd, void *arg)
368 struct openssl_transport_context *ctx = arg;
369 SSL *conn = ctx->conn;
373 xfree_null (ctx->last_error);
378 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
381 /* openssl_transport is the singleton that describes the SSL transport
382 methods provided by this file. */
384 static struct transport_implementation openssl_transport = {
385 openssl_read, openssl_write, openssl_poll,
386 openssl_peek, openssl_errstr, openssl_close
389 /* Perform the SSL handshake on file descriptor FD, which is assumed
390 to be connected to an SSL server. The SSL handle provided by
391 OpenSSL is registered with the file descriptor FD using
392 fd_register_transport, so that subsequent calls to fd_read,
393 fd_write, etc., will use the corresponding SSL functions.
395 Returns true on success, false on failure. */
398 ssl_connect_wget (int fd)
401 struct openssl_transport_context *ctx;
403 DEBUGP (("Initiating SSL handshake.\n"));
405 assert (ssl_ctx != NULL);
406 conn = SSL_new (ssl_ctx);
410 # define FD_TO_SOCKET(X) (X)
412 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
414 SSL_set_connect_state (conn);
415 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
418 ctx = xnew0 (struct openssl_transport_context);
421 /* Register FD with Wget's transport layer, i.e. arrange that our
422 functions are used for reading, writing, and polling. */
423 fd_register_transport (fd, &openssl_transport, ctx);
424 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
425 fd, PTR_FORMAT (conn)));
429 DEBUGP (("SSL handshake failed.\n"));
436 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
438 /* Return true is STRING (case-insensitively) matches PATTERN, false
439 otherwise. The recognized wildcard character is "*", which matches
440 any character in STRING except ".". Any number of the "*" wildcard
441 may be present in the pattern.
443 This is used to match of hosts as indicated in rfc2818: "Names may
444 contain the wildcard character * which is considered to match any
445 single domain name component or component fragment. E.g., *.a.com
446 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
447 not bar.com [or foo.bar.com]."
449 If the pattern contain no wildcards, pattern_match(a, b) is
450 equivalent to !strcasecmp(a, b). */
453 pattern_match (const char *pattern, const char *string)
455 const char *p = pattern, *n = string;
457 for (; (c = c_tolower (*p++)) != '\0'; n++)
460 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
462 for (; *n != '\0'; n++)
463 if (c_tolower (*n) == c && pattern_match (p, n))
465 #ifdef ASTERISK_EXCLUDES_DOT
473 if (c != c_tolower (*n))
479 /* Verify the validity of the certificate presented by the server.
480 Also check that the "common name" of the server, as presented by
481 its certificate, corresponds to HOST. (HOST typically comes from
482 the URL and is what the user thinks he's connecting to.)
484 This assumes that ssl_connect_wget has successfully finished, i.e. that
485 the SSL handshake has been performed and that FD is connected to an
488 If opt.check_cert is true (the default), this returns 1 if the
489 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
490 function always returns 1, but should still be called because it
491 warns the user about any problems with the certificate. */
494 ssl_check_certificate (int fd, const char *host)
497 GENERAL_NAMES *subjectAltNames;
498 char common_name[256];
501 bool alt_name_checked = false;
503 /* If the user has specified --no-check-cert, we still want to warn
504 him about problems with the server's certificate. */
505 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
507 struct openssl_transport_context *ctx = fd_transport_context (fd);
508 SSL *conn = ctx->conn;
509 assert (conn != NULL);
511 cert = SSL_get_peer_certificate (conn);
514 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
515 severity, quotearg_style (escape_quoting_style, host));
517 goto no_cert; /* must bail out since CERT is NULL */
522 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
523 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
524 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
525 quotearg_n_style (0, escape_quoting_style, subject),
526 quotearg_n_style (1, escape_quoting_style, issuer)));
527 OPENSSL_free (subject);
528 OPENSSL_free (issuer);
531 vresult = SSL_get_verify_result (conn);
532 if (vresult != X509_V_OK)
534 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
535 logprintf (LOG_NOTQUIET,
536 _("%s: cannot verify %s's certificate, issued by %s:\n"),
537 severity, quotearg_n_style (0, escape_quoting_style, host),
538 quote_n (1, issuer));
539 /* Try to print more user-friendly (and translated) messages for
540 the frequent verification errors. */
543 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
544 logprintf (LOG_NOTQUIET,
545 _(" Unable to locally verify the issuer's authority.\n"));
547 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
548 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
549 logprintf (LOG_NOTQUIET,
550 _(" Self-signed certificate encountered.\n"));
552 case X509_V_ERR_CERT_NOT_YET_VALID:
553 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
555 case X509_V_ERR_CERT_HAS_EXPIRED:
556 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
559 /* For the less frequent error strings, simply provide the
560 OpenSSL error message. */
561 logprintf (LOG_NOTQUIET, " %s\n",
562 X509_verify_cert_error_string (vresult));
565 /* Fall through, so that the user is warned about *all* issues
566 with the cert (important with --no-check-certificate.) */
569 /* Check that HOST matches the common name in the certificate.
570 #### The following remains to be done:
572 - When matching against common names, it should loop over all
573 common names and choose the most specific one, i.e. the last
574 one, not the first one, which the current code picks.
576 - Ensure that ASN1 strings from the certificate are encoded as
577 UTF-8 which can be meaningfully compared to HOST. */
579 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
583 /* Test subject alternative names */
585 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
586 * Signal it by host_in_octet_string. */
587 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
589 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
591 for (i=0; i < numaltnames; i++)
593 const GENERAL_NAME *name =
594 sk_GENERAL_NAME_value (subjectAltNames, i);
597 if (host_in_octet_string)
599 if (name->type == GEN_IPADD)
601 /* Check for ipAddress */
602 /* TODO: Should we convert between IPv4-mapped IPv6
603 * addresses and IPv4 addresses? */
604 alt_name_checked = true;
605 if (!ASN1_STRING_cmp (host_in_octet_string,
610 else if (name->type == GEN_DNS)
612 /* dNSName should be IA5String (i.e. ASCII), however who
613 * does trust CA? Convert it into UTF-8 for sure. */
614 unsigned char *name_in_utf8 = NULL;
616 /* Check for dNSName */
617 alt_name_checked = true;
619 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
621 /* Compare and check for NULL attack in ASN1_STRING */
622 if (pattern_match ((char *)name_in_utf8, host) &&
623 (strlen ((char *)name_in_utf8) ==
624 ASN1_STRING_length (name->d.dNSName)))
626 OPENSSL_free (name_in_utf8);
629 OPENSSL_free (name_in_utf8);
634 sk_GENERAL_NAME_free (subjectAltNames);
635 if (host_in_octet_string)
636 ASN1_OCTET_STRING_free(host_in_octet_string);
638 if (alt_name_checked == true && i >= numaltnames)
640 logprintf (LOG_NOTQUIET,
641 _("%s: no certificate subject alternative name matches\n"
642 "\trequested host name %s.\n"),
643 severity, quote_n (1, host));
648 if (alt_name_checked == false)
650 /* Test commomName */
651 X509_NAME *xname = X509_get_subject_name(cert);
652 common_name[0] = '\0';
653 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
654 sizeof (common_name));
656 if (!pattern_match (common_name, host))
658 logprintf (LOG_NOTQUIET, _("\
659 %s: certificate common name %s doesn't match requested host name %s.\n"),
660 severity, quote_n (0, common_name), quote_n (1, host));
665 /* We now determine the length of the ASN1 string. If it
666 * differs from common_name's length, then there is a \0
667 * before the string terminates. This can be an instance of a
668 * null-prefix attack.
670 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
674 X509_NAME_ENTRY *xentry;
680 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
686 xentry = X509_NAME_get_entry(xname,i);
687 sdata = X509_NAME_ENTRY_get_data(xentry);
688 if (strlen (common_name) != ASN1_STRING_length (sdata))
690 logprintf (LOG_NOTQUIET, _("\
691 %s: certificate common name is invalid (contains a NUL character).\n\
692 This may be an indication that the host is not who it claims to be\n\
693 (that is, it is not the real %s).\n"),
694 severity, quote (host));
702 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
703 quotearg_style (escape_quoting_style, host)));
707 if (opt.check_cert && !success)
708 logprintf (LOG_NOTQUIET, _("\
709 To connect to %s insecurely, use `--no-check-certificate'.\n"),
710 quotearg_style (escape_quoting_style, host));
712 /* Allow --no-check-cert to disable certificate checking. */
713 return opt.check_cert ? success : true;
717 * vim: tabstop=2 shiftwidth=2 softtabstop=2