1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
3 2009, 2010, 2011, 2012 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
256 SSL *conn; /* SSL connection handle */
257 char *last_error; /* last error printed with openssl_errstr */
260 struct openssl_read_args
263 struct openssl_transport_context *ctx;
269 static void openssl_read_callback(void *arg)
271 struct openssl_read_args *args = (struct openssl_read_args *) arg;
272 struct openssl_transport_context *ctx = args->ctx;
273 SSL *conn = ctx->conn;
274 char *buf = args->buf;
275 int bufsize = args->bufsize;
279 ret = SSL_read (conn, buf, bufsize);
280 while (ret == -1 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
286 openssl_read (int fd, char *buf, int bufsize, void *arg)
288 struct openssl_read_args args;
291 args.bufsize = bufsize;
292 args.ctx = (struct openssl_transport_context*) arg;
294 if (run_with_timeout(opt.read_timeout, openssl_read_callback, &args)) {
301 openssl_write (int fd, char *buf, int bufsize, void *arg)
304 struct openssl_transport_context *ctx = arg;
305 SSL *conn = ctx->conn;
307 ret = SSL_write (conn, buf, bufsize);
309 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
315 openssl_poll (int fd, double timeout, int wait_for, void *arg)
317 struct openssl_transport_context *ctx = arg;
318 SSL *conn = ctx->conn;
319 if (SSL_pending (conn))
323 return select_fd (fd, timeout, wait_for);
327 openssl_peek (int fd, char *buf, int bufsize, void *arg)
330 struct openssl_transport_context *ctx = arg;
331 SSL *conn = ctx->conn;
332 if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg))
335 ret = SSL_peek (conn, buf, bufsize);
337 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
343 openssl_errstr (int fd, void *arg)
345 struct openssl_transport_context *ctx = arg;
346 unsigned long errcode;
350 /* If there are no SSL-specific errors, just return NULL. */
351 if ((errcode = ERR_get_error ()) == 0)
354 /* Get rid of previous contents of ctx->last_error, if any. */
355 xfree_null (ctx->last_error);
357 /* Iterate over OpenSSL's error stack and accumulate errors in the
358 last_error buffer, separated by "; ". This is better than using
359 a static buffer, which *always* takes up space (and has to be
360 large, to fit more than one error message), whereas these
361 allocations are only performed when there is an actual error. */
365 const char *str = ERR_error_string (errcode, NULL);
366 int len = strlen (str);
368 /* Allocate space for the existing message, plus two more chars
369 for the "; " separator and one for the terminating \0. */
370 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
371 memcpy (errmsg + msglen, str, len);
374 /* Get next error and bail out if there are no more. */
375 errcode = ERR_get_error ();
379 errmsg[msglen++] = ';';
380 errmsg[msglen++] = ' ';
382 errmsg[msglen] = '\0';
384 /* Store the error in ctx->last_error where openssl_close will
385 eventually find it and free it. */
386 ctx->last_error = errmsg;
392 openssl_close (int fd, void *arg)
394 struct openssl_transport_context *ctx = arg;
395 SSL *conn = ctx->conn;
399 xfree_null (ctx->last_error);
404 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
407 /* openssl_transport is the singleton that describes the SSL transport
408 methods provided by this file. */
410 static struct transport_implementation openssl_transport = {
411 openssl_read, openssl_write, openssl_poll,
412 openssl_peek, openssl_errstr, openssl_close
422 ssl_connect_with_timeout_callback(void *arg)
424 struct scwt_context *ctx = (struct scwt_context *)arg;
425 ctx->result = SSL_connect(ctx->ssl);
428 /* Perform the SSL handshake on file descriptor FD, which is assumed
429 to be connected to an SSL server. The SSL handle provided by
430 OpenSSL is registered with the file descriptor FD using
431 fd_register_transport, so that subsequent calls to fd_read,
432 fd_write, etc., will use the corresponding SSL functions.
434 Returns true on success, false on failure. */
437 ssl_connect_wget (int fd, const char *hostname)
440 struct scwt_context scwt_ctx;
441 struct openssl_transport_context *ctx;
443 DEBUGP (("Initiating SSL handshake.\n"));
445 assert (ssl_ctx != NULL);
446 conn = SSL_new (ssl_ctx);
449 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
450 /* If the SSL library was build with support for ServerNameIndication
451 then use it whenever we have a hostname. If not, don't, ever. */
452 if (! is_valid_ip_address (hostname))
454 if (! SSL_set_tlsext_host_name (conn, hostname))
456 DEBUGP (("Failed to set TLS server-name indication."));
463 # define FD_TO_SOCKET(X) (X)
465 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
467 SSL_set_connect_state (conn);
470 if (run_with_timeout(opt.read_timeout, ssl_connect_with_timeout_callback,
472 DEBUGP (("SSL handshake timed out.\n"));
475 if (scwt_ctx.result <= 0 || conn->state != SSL_ST_OK)
478 ctx = xnew0 (struct openssl_transport_context);
481 /* Register FD with Wget's transport layer, i.e. arrange that our
482 functions are used for reading, writing, and polling. */
483 fd_register_transport (fd, &openssl_transport, ctx);
484 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
485 fd, PTR_FORMAT (conn)));
489 DEBUGP (("SSL handshake failed.\n"));
497 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
499 /* Return true is STRING (case-insensitively) matches PATTERN, false
500 otherwise. The recognized wildcard character is "*", which matches
501 any character in STRING except ".". Any number of the "*" wildcard
502 may be present in the pattern.
504 This is used to match of hosts as indicated in rfc2818: "Names may
505 contain the wildcard character * which is considered to match any
506 single domain name component or component fragment. E.g., *.a.com
507 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
508 not bar.com [or foo.bar.com]."
510 If the pattern contain no wildcards, pattern_match(a, b) is
511 equivalent to !strcasecmp(a, b). */
514 pattern_match (const char *pattern, const char *string)
516 const char *p = pattern, *n = string;
518 for (; (c = c_tolower (*p++)) != '\0'; n++)
521 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
523 for (; *n != '\0'; n++)
524 if (c_tolower (*n) == c && pattern_match (p, n))
526 #ifdef ASTERISK_EXCLUDES_DOT
534 if (c != c_tolower (*n))
540 /* Verify the validity of the certificate presented by the server.
541 Also check that the "common name" of the server, as presented by
542 its certificate, corresponds to HOST. (HOST typically comes from
543 the URL and is what the user thinks he's connecting to.)
545 This assumes that ssl_connect_wget has successfully finished, i.e. that
546 the SSL handshake has been performed and that FD is connected to an
549 If opt.check_cert is true (the default), this returns 1 if the
550 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
551 function always returns 1, but should still be called because it
552 warns the user about any problems with the certificate. */
555 ssl_check_certificate (int fd, const char *host)
558 GENERAL_NAMES *subjectAltNames;
559 char common_name[256];
562 bool alt_name_checked = false;
564 /* If the user has specified --no-check-cert, we still want to warn
565 him about problems with the server's certificate. */
566 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
568 struct openssl_transport_context *ctx = fd_transport_context (fd);
569 SSL *conn = ctx->conn;
570 assert (conn != NULL);
572 cert = SSL_get_peer_certificate (conn);
575 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
576 severity, quotearg_style (escape_quoting_style, host));
578 goto no_cert; /* must bail out since CERT is NULL */
583 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
584 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
585 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
586 quotearg_n_style (0, escape_quoting_style, subject),
587 quotearg_n_style (1, escape_quoting_style, issuer)));
588 OPENSSL_free (subject);
589 OPENSSL_free (issuer);
592 vresult = SSL_get_verify_result (conn);
593 if (vresult != X509_V_OK)
595 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
596 logprintf (LOG_NOTQUIET,
597 _("%s: cannot verify %s's certificate, issued by %s:\n"),
598 severity, quotearg_n_style (0, escape_quoting_style, host),
599 quote_n (1, issuer));
600 /* Try to print more user-friendly (and translated) messages for
601 the frequent verification errors. */
604 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
605 logprintf (LOG_NOTQUIET,
606 _(" Unable to locally verify the issuer's authority.\n"));
608 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
609 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
610 logprintf (LOG_NOTQUIET,
611 _(" Self-signed certificate encountered.\n"));
613 case X509_V_ERR_CERT_NOT_YET_VALID:
614 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
616 case X509_V_ERR_CERT_HAS_EXPIRED:
617 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
620 /* For the less frequent error strings, simply provide the
621 OpenSSL error message. */
622 logprintf (LOG_NOTQUIET, " %s\n",
623 X509_verify_cert_error_string (vresult));
626 /* Fall through, so that the user is warned about *all* issues
627 with the cert (important with --no-check-certificate.) */
630 /* Check that HOST matches the common name in the certificate.
631 #### The following remains to be done:
633 - When matching against common names, it should loop over all
634 common names and choose the most specific one, i.e. the last
635 one, not the first one, which the current code picks.
637 - Ensure that ASN1 strings from the certificate are encoded as
638 UTF-8 which can be meaningfully compared to HOST. */
640 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
644 /* Test subject alternative names */
646 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
647 * Signal it by host_in_octet_string. */
648 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
650 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
652 for (i=0; i < numaltnames; i++)
654 const GENERAL_NAME *name =
655 sk_GENERAL_NAME_value (subjectAltNames, i);
658 if (host_in_octet_string)
660 if (name->type == GEN_IPADD)
662 /* Check for ipAddress */
663 /* TODO: Should we convert between IPv4-mapped IPv6
664 * addresses and IPv4 addresses? */
665 alt_name_checked = true;
666 if (!ASN1_STRING_cmp (host_in_octet_string,
671 else if (name->type == GEN_DNS)
673 /* dNSName should be IA5String (i.e. ASCII), however who
674 * does trust CA? Convert it into UTF-8 for sure. */
675 unsigned char *name_in_utf8 = NULL;
677 /* Check for dNSName */
678 alt_name_checked = true;
680 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
682 /* Compare and check for NULL attack in ASN1_STRING */
683 if (pattern_match ((char *)name_in_utf8, host) &&
684 (strlen ((char *)name_in_utf8) ==
685 ASN1_STRING_length (name->d.dNSName)))
687 OPENSSL_free (name_in_utf8);
690 OPENSSL_free (name_in_utf8);
695 sk_GENERAL_NAME_free (subjectAltNames);
696 if (host_in_octet_string)
697 ASN1_OCTET_STRING_free(host_in_octet_string);
699 if (alt_name_checked == true && i >= numaltnames)
701 logprintf (LOG_NOTQUIET,
702 _("%s: no certificate subject alternative name matches\n"
703 "\trequested host name %s.\n"),
704 severity, quote_n (1, host));
709 if (alt_name_checked == false)
711 /* Test commomName */
712 X509_NAME *xname = X509_get_subject_name(cert);
713 common_name[0] = '\0';
714 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
715 sizeof (common_name));
717 if (!pattern_match (common_name, host))
719 logprintf (LOG_NOTQUIET, _("\
720 %s: certificate common name %s doesn't match requested host name %s.\n"),
721 severity, quote_n (0, common_name), quote_n (1, host));
726 /* We now determine the length of the ASN1 string. If it
727 * differs from common_name's length, then there is a \0
728 * before the string terminates. This can be an instance of a
729 * null-prefix attack.
731 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
735 X509_NAME_ENTRY *xentry;
741 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
747 xentry = X509_NAME_get_entry(xname,i);
748 sdata = X509_NAME_ENTRY_get_data(xentry);
749 if (strlen (common_name) != ASN1_STRING_length (sdata))
751 logprintf (LOG_NOTQUIET, _("\
752 %s: certificate common name is invalid (contains a NUL character).\n\
753 This may be an indication that the host is not who it claims to be\n\
754 (that is, it is not the real %s).\n"),
755 severity, quote (host));
763 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
764 quotearg_style (escape_quoting_style, host)));
768 if (opt.check_cert && !success)
769 logprintf (LOG_NOTQUIET, _("\
770 To connect to %s insecurely, use `--no-check-certificate'.\n"),
771 quotearg_style (escape_quoting_style, host));
773 /* Allow --no-check-cert to disable certificate checking. */
774 return opt.check_cert ? success : true;
778 * vim: tabstop=2 shiftwidth=2 softtabstop=2