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_pfs:
198 case secure_protocol_tlsv1:
199 meth = TLSv1_client_method ();
205 /* The type cast below accommodates older OpenSSL versions (0.9.8)
206 where SSL_CTX_new() is declared without a "const" argument. */
207 ssl_ctx = SSL_CTX_new ((SSL_METHOD *)meth);
211 /* OpenSSL ciphers: https://www.openssl.org/docs/apps/ciphers.html
212 * Since we want a good protection, we also use HIGH (that excludes MD4 ciphers and some more)
214 if (opt.secure_protocol == secure_protocol_pfs)
215 SSL_CTX_set_cipher_list (ssl_ctx, "HIGH:MEDIUM:!RC4:!SRP:!PSK:!RSA:!aNULL@STRENGTH");
217 SSL_CTX_set_default_verify_paths (ssl_ctx);
218 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
220 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
221 certificate is invalid. We verify the certificate separately in
222 ssl_check_certificate, which provides much better diagnostics
223 than examining the error stack after a failed SSL_connect. */
224 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
226 /* Use the private key from the cert file unless otherwise specified. */
227 if (opt.cert_file && !opt.private_key)
229 opt.private_key = opt.cert_file;
230 opt.private_key_type = opt.cert_type;
234 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
235 key_type_to_ssl_type (opt.cert_type))
239 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
240 key_type_to_ssl_type (opt.private_key_type))
244 /* Since fd_write unconditionally assumes partial writes (and
245 handles them correctly), allow them in OpenSSL. */
246 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
248 /* The OpenSSL library can handle renegotiations automatically, so
250 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
256 SSL_CTX_free (ssl_ctx);
261 struct openssl_transport_context
263 SSL *conn; /* SSL connection handle */
264 char *last_error; /* last error printed with openssl_errstr */
267 struct openssl_read_args
270 struct openssl_transport_context *ctx;
276 static void openssl_read_callback(void *arg)
278 struct openssl_read_args *args = (struct openssl_read_args *) arg;
279 struct openssl_transport_context *ctx = args->ctx;
280 SSL *conn = ctx->conn;
281 char *buf = args->buf;
282 int bufsize = args->bufsize;
286 ret = SSL_read (conn, buf, bufsize);
287 while (ret == -1 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
293 openssl_read (int fd, char *buf, int bufsize, void *arg)
295 struct openssl_read_args args;
298 args.bufsize = bufsize;
299 args.ctx = (struct openssl_transport_context*) arg;
301 if (run_with_timeout(opt.read_timeout, openssl_read_callback, &args)) {
308 openssl_write (int fd _GL_UNUSED, char *buf, int bufsize, void *arg)
311 struct openssl_transport_context *ctx = arg;
312 SSL *conn = ctx->conn;
314 ret = SSL_write (conn, buf, bufsize);
316 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
322 openssl_poll (int fd, double timeout, int wait_for, void *arg)
324 struct openssl_transport_context *ctx = arg;
325 SSL *conn = ctx->conn;
326 if (SSL_pending (conn))
330 return select_fd (fd, timeout, wait_for);
334 openssl_peek (int fd, char *buf, int bufsize, void *arg)
337 struct openssl_transport_context *ctx = arg;
338 SSL *conn = ctx->conn;
339 if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg))
342 ret = SSL_peek (conn, buf, bufsize);
344 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
350 openssl_errstr (int fd _GL_UNUSED, void *arg)
352 struct openssl_transport_context *ctx = arg;
353 unsigned long errcode;
357 /* If there are no SSL-specific errors, just return NULL. */
358 if ((errcode = ERR_get_error ()) == 0)
361 /* Get rid of previous contents of ctx->last_error, if any. */
362 xfree_null (ctx->last_error);
364 /* Iterate over OpenSSL's error stack and accumulate errors in the
365 last_error buffer, separated by "; ". This is better than using
366 a static buffer, which *always* takes up space (and has to be
367 large, to fit more than one error message), whereas these
368 allocations are only performed when there is an actual error. */
372 const char *str = ERR_error_string (errcode, NULL);
373 int len = strlen (str);
375 /* Allocate space for the existing message, plus two more chars
376 for the "; " separator and one for the terminating \0. */
377 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
378 memcpy (errmsg + msglen, str, len);
381 /* Get next error and bail out if there are no more. */
382 errcode = ERR_get_error ();
386 errmsg[msglen++] = ';';
387 errmsg[msglen++] = ' ';
389 errmsg[msglen] = '\0';
391 /* Store the error in ctx->last_error where openssl_close will
392 eventually find it and free it. */
393 ctx->last_error = errmsg;
399 openssl_close (int fd, void *arg)
401 struct openssl_transport_context *ctx = arg;
402 SSL *conn = ctx->conn;
406 xfree_null (ctx->last_error);
411 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
414 /* openssl_transport is the singleton that describes the SSL transport
415 methods provided by this file. */
417 static struct transport_implementation openssl_transport = {
418 openssl_read, openssl_write, openssl_poll,
419 openssl_peek, openssl_errstr, openssl_close
429 ssl_connect_with_timeout_callback(void *arg)
431 struct scwt_context *ctx = (struct scwt_context *)arg;
432 ctx->result = SSL_connect(ctx->ssl);
435 /* Perform the SSL handshake on file descriptor FD, which is assumed
436 to be connected to an SSL server. The SSL handle provided by
437 OpenSSL is registered with the file descriptor FD using
438 fd_register_transport, so that subsequent calls to fd_read,
439 fd_write, etc., will use the corresponding SSL functions.
441 Returns true on success, false on failure. */
444 ssl_connect_wget (int fd, const char *hostname)
447 struct scwt_context scwt_ctx;
448 struct openssl_transport_context *ctx;
450 DEBUGP (("Initiating SSL handshake.\n"));
452 assert (ssl_ctx != NULL);
453 conn = SSL_new (ssl_ctx);
456 #if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT)
457 /* If the SSL library was build with support for ServerNameIndication
458 then use it whenever we have a hostname. If not, don't, ever. */
459 if (! is_valid_ip_address (hostname))
461 if (! SSL_set_tlsext_host_name (conn, hostname))
463 DEBUGP (("Failed to set TLS server-name indication."));
470 # define FD_TO_SOCKET(X) (X)
472 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
474 SSL_set_connect_state (conn);
477 if (run_with_timeout(opt.read_timeout, ssl_connect_with_timeout_callback,
479 DEBUGP (("SSL handshake timed out.\n"));
482 if (scwt_ctx.result <= 0 || conn->state != SSL_ST_OK)
485 ctx = xnew0 (struct openssl_transport_context);
488 /* Register FD with Wget's transport layer, i.e. arrange that our
489 functions are used for reading, writing, and polling. */
490 fd_register_transport (fd, &openssl_transport, ctx);
491 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
492 fd, PTR_FORMAT (conn)));
496 DEBUGP (("SSL handshake failed.\n"));
504 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
506 /* Return true is STRING (case-insensitively) matches PATTERN, false
507 otherwise. The recognized wildcard character is "*", which matches
508 any character in STRING except ".". Any number of the "*" wildcard
509 may be present in the pattern.
511 This is used to match of hosts as indicated in rfc2818: "Names may
512 contain the wildcard character * which is considered to match any
513 single domain name component or component fragment. E.g., *.a.com
514 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
515 not bar.com [or foo.bar.com]."
517 If the pattern contain no wildcards, pattern_match(a, b) is
518 equivalent to !strcasecmp(a, b). */
521 pattern_match (const char *pattern, const char *string)
523 const char *p = pattern, *n = string;
525 for (; (c = c_tolower (*p++)) != '\0'; n++)
528 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
530 for (; *n != '\0'; n++)
531 if (c_tolower (*n) == c && pattern_match (p, n))
533 #ifdef ASTERISK_EXCLUDES_DOT
541 if (c != c_tolower (*n))
547 /* Verify the validity of the certificate presented by the server.
548 Also check that the "common name" of the server, as presented by
549 its certificate, corresponds to HOST. (HOST typically comes from
550 the URL and is what the user thinks he's connecting to.)
552 This assumes that ssl_connect_wget has successfully finished, i.e. that
553 the SSL handshake has been performed and that FD is connected to an
556 If opt.check_cert is true (the default), this returns 1 if the
557 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
558 function always returns 1, but should still be called because it
559 warns the user about any problems with the certificate. */
562 ssl_check_certificate (int fd, const char *host)
565 GENERAL_NAMES *subjectAltNames;
566 char common_name[256];
569 bool alt_name_checked = false;
571 /* If the user has specified --no-check-cert, we still want to warn
572 him about problems with the server's certificate. */
573 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
575 struct openssl_transport_context *ctx = fd_transport_context (fd);
576 SSL *conn = ctx->conn;
577 assert (conn != NULL);
579 cert = SSL_get_peer_certificate (conn);
582 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
583 severity, quotearg_style (escape_quoting_style, host));
585 goto no_cert; /* must bail out since CERT is NULL */
590 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
591 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
592 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
593 quotearg_n_style (0, escape_quoting_style, subject),
594 quotearg_n_style (1, escape_quoting_style, issuer)));
595 OPENSSL_free (subject);
596 OPENSSL_free (issuer);
599 vresult = SSL_get_verify_result (conn);
600 if (vresult != X509_V_OK)
602 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
603 logprintf (LOG_NOTQUIET,
604 _("%s: cannot verify %s's certificate, issued by %s:\n"),
605 severity, quotearg_n_style (0, escape_quoting_style, host),
606 quote_n (1, issuer));
607 /* Try to print more user-friendly (and translated) messages for
608 the frequent verification errors. */
611 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
612 logprintf (LOG_NOTQUIET,
613 _(" Unable to locally verify the issuer's authority.\n"));
615 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
616 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
617 logprintf (LOG_NOTQUIET,
618 _(" Self-signed certificate encountered.\n"));
620 case X509_V_ERR_CERT_NOT_YET_VALID:
621 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
623 case X509_V_ERR_CERT_HAS_EXPIRED:
624 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
627 /* For the less frequent error strings, simply provide the
628 OpenSSL error message. */
629 logprintf (LOG_NOTQUIET, " %s\n",
630 X509_verify_cert_error_string (vresult));
633 /* Fall through, so that the user is warned about *all* issues
634 with the cert (important with --no-check-certificate.) */
637 /* Check that HOST matches the common name in the certificate.
638 #### The following remains to be done:
640 - When matching against common names, it should loop over all
641 common names and choose the most specific one, i.e. the last
642 one, not the first one, which the current code picks.
644 - Ensure that ASN1 strings from the certificate are encoded as
645 UTF-8 which can be meaningfully compared to HOST. */
647 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
651 /* Test subject alternative names */
653 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
654 * Signal it by host_in_octet_string. */
655 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
657 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
659 for (i=0; i < numaltnames; i++)
661 const GENERAL_NAME *name =
662 sk_GENERAL_NAME_value (subjectAltNames, i);
665 if (host_in_octet_string)
667 if (name->type == GEN_IPADD)
669 /* Check for ipAddress */
670 /* TODO: Should we convert between IPv4-mapped IPv6
671 * addresses and IPv4 addresses? */
672 alt_name_checked = true;
673 if (!ASN1_STRING_cmp (host_in_octet_string,
678 else if (name->type == GEN_DNS)
680 /* dNSName should be IA5String (i.e. ASCII), however who
681 * does trust CA? Convert it into UTF-8 for sure. */
682 unsigned char *name_in_utf8 = NULL;
684 /* Check for dNSName */
685 alt_name_checked = true;
687 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
689 /* Compare and check for NULL attack in ASN1_STRING */
690 if (pattern_match ((char *)name_in_utf8, host) &&
691 (strlen ((char *)name_in_utf8) ==
692 (size_t) ASN1_STRING_length (name->d.dNSName)))
694 OPENSSL_free (name_in_utf8);
697 OPENSSL_free (name_in_utf8);
702 sk_GENERAL_NAME_free (subjectAltNames);
703 if (host_in_octet_string)
704 ASN1_OCTET_STRING_free(host_in_octet_string);
706 if (alt_name_checked == true && i >= numaltnames)
708 logprintf (LOG_NOTQUIET,
709 _("%s: no certificate subject alternative name matches\n"
710 "\trequested host name %s.\n"),
711 severity, quote_n (1, host));
716 if (alt_name_checked == false)
718 /* Test commomName */
719 X509_NAME *xname = X509_get_subject_name(cert);
720 common_name[0] = '\0';
721 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
722 sizeof (common_name));
724 if (!pattern_match (common_name, host))
726 logprintf (LOG_NOTQUIET, _("\
727 %s: certificate common name %s doesn't match requested host name %s.\n"),
728 severity, quote_n (0, common_name), quote_n (1, host));
733 /* We now determine the length of the ASN1 string. If it
734 * differs from common_name's length, then there is a \0
735 * before the string terminates. This can be an instance of a
736 * null-prefix attack.
738 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
742 X509_NAME_ENTRY *xentry;
748 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
754 xentry = X509_NAME_get_entry(xname,i);
755 sdata = X509_NAME_ENTRY_get_data(xentry);
756 if (strlen (common_name) != (size_t) ASN1_STRING_length (sdata))
758 logprintf (LOG_NOTQUIET, _("\
759 %s: certificate common name is invalid (contains a NUL character).\n\
760 This may be an indication that the host is not who it claims to be\n\
761 (that is, it is not the real %s).\n"),
762 severity, quote (host));
770 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
771 quotearg_style (escape_quoting_style, host)));
775 if (opt.check_cert && !success)
776 logprintf (LOG_NOTQUIET, _("\
777 To connect to %s insecurely, use `--no-check-certificate'.\n"),
778 quotearg_style (escape_quoting_style, host));
780 /* Allow --no-check-cert to disable certificate checking. */
781 return opt.check_cert ? success : true;
785 * vim: tabstop=2 shiftwidth=2 softtabstop=2