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. */
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 ssl_ctx = SSL_CTX_new (meth);
208 SSL_CTX_set_default_verify_paths (ssl_ctx);
209 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
211 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
212 certificate is invalid. We verify the certificate separately in
213 ssl_check_certificate, which provides much better diagnostics
214 than examining the error stack after a failed SSL_connect. */
215 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
217 /* Use the private key from the cert file unless otherwise specified. */
218 if (opt.cert_file && !opt.private_key)
220 opt.private_key = opt.cert_file;
221 opt.private_key_type = opt.cert_type;
225 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
226 key_type_to_ssl_type (opt.cert_type))
230 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
231 key_type_to_ssl_type (opt.private_key_type))
235 /* Since fd_write unconditionally assumes partial writes (and
236 handles them correctly), allow them in OpenSSL. */
237 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
239 /* The OpenSSL library can handle renegotiations automatically, so
241 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
247 SSL_CTX_free (ssl_ctx);
252 struct openssl_transport_context {
253 SSL *conn; /* SSL connection handle */
254 char *last_error; /* last error printed with openssl_errstr */
258 openssl_read (int fd, char *buf, int bufsize, void *arg)
261 struct openssl_transport_context *ctx = arg;
262 SSL *conn = ctx->conn;
264 ret = SSL_read (conn, buf, bufsize);
266 || (SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
273 openssl_write (int fd, char *buf, int bufsize, void *arg)
276 struct openssl_transport_context *ctx = arg;
277 SSL *conn = ctx->conn;
279 ret = SSL_write (conn, buf, bufsize);
281 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
287 openssl_poll (int fd, double timeout, int wait_for, void *arg)
289 struct openssl_transport_context *ctx = arg;
290 SSL *conn = ctx->conn;
291 if (SSL_pending (conn))
295 return select_fd (fd, timeout, wait_for);
299 openssl_peek (int fd, char *buf, int bufsize, void *arg)
302 struct openssl_transport_context *ctx = arg;
303 SSL *conn = ctx->conn;
304 if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg))
307 ret = SSL_peek (conn, buf, bufsize);
309 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
315 openssl_errstr (int fd, void *arg)
317 struct openssl_transport_context *ctx = arg;
318 unsigned long errcode;
322 /* If there are no SSL-specific errors, just return NULL. */
323 if ((errcode = ERR_get_error ()) == 0)
326 /* Get rid of previous contents of ctx->last_error, if any. */
327 xfree_null (ctx->last_error);
329 /* Iterate over OpenSSL's error stack and accumulate errors in the
330 last_error buffer, separated by "; ". This is better than using
331 a static buffer, which *always* takes up space (and has to be
332 large, to fit more than one error message), whereas these
333 allocations are only performed when there is an actual error. */
337 const char *str = ERR_error_string (errcode, NULL);
338 int len = strlen (str);
340 /* Allocate space for the existing message, plus two more chars
341 for the "; " separator and one for the terminating \0. */
342 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
343 memcpy (errmsg + msglen, str, len);
346 /* Get next error and bail out if there are no more. */
347 errcode = ERR_get_error ();
351 errmsg[msglen++] = ';';
352 errmsg[msglen++] = ' ';
354 errmsg[msglen] = '\0';
356 /* Store the error in ctx->last_error where openssl_close will
357 eventually find it and free it. */
358 ctx->last_error = errmsg;
364 openssl_close (int fd, void *arg)
366 struct openssl_transport_context *ctx = arg;
367 SSL *conn = ctx->conn;
371 xfree_null (ctx->last_error);
376 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
379 /* openssl_transport is the singleton that describes the SSL transport
380 methods provided by this file. */
382 static struct transport_implementation openssl_transport = {
383 openssl_read, openssl_write, openssl_poll,
384 openssl_peek, openssl_errstr, openssl_close
387 /* Perform the SSL handshake on file descriptor FD, which is assumed
388 to be connected to an SSL server. The SSL handle provided by
389 OpenSSL is registered with the file descriptor FD using
390 fd_register_transport, so that subsequent calls to fd_read,
391 fd_write, etc., will use the corresponding SSL functions.
393 Returns true on success, false on failure. */
396 ssl_connect_wget (int fd)
399 struct openssl_transport_context *ctx;
401 DEBUGP (("Initiating SSL handshake.\n"));
403 assert (ssl_ctx != NULL);
404 conn = SSL_new (ssl_ctx);
408 # define FD_TO_SOCKET(X) (X)
410 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
412 SSL_set_connect_state (conn);
413 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
416 ctx = xnew0 (struct openssl_transport_context);
419 /* Register FD with Wget's transport layer, i.e. arrange that our
420 functions are used for reading, writing, and polling. */
421 fd_register_transport (fd, &openssl_transport, ctx);
422 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
423 fd, PTR_FORMAT (conn)));
427 DEBUGP (("SSL handshake failed.\n"));
434 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
436 /* Return true is STRING (case-insensitively) matches PATTERN, false
437 otherwise. The recognized wildcard character is "*", which matches
438 any character in STRING except ".". Any number of the "*" wildcard
439 may be present in the pattern.
441 This is used to match of hosts as indicated in rfc2818: "Names may
442 contain the wildcard character * which is considered to match any
443 single domain name component or component fragment. E.g., *.a.com
444 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
445 not bar.com [or foo.bar.com]."
447 If the pattern contain no wildcards, pattern_match(a, b) is
448 equivalent to !strcasecmp(a, b). */
451 pattern_match (const char *pattern, const char *string)
453 const char *p = pattern, *n = string;
455 for (; (c = c_tolower (*p++)) != '\0'; n++)
458 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
460 for (; *n != '\0'; n++)
461 if (c_tolower (*n) == c && pattern_match (p, n))
463 #ifdef ASTERISK_EXCLUDES_DOT
471 if (c != c_tolower (*n))
477 /* Verify the validity of the certificate presented by the server.
478 Also check that the "common name" of the server, as presented by
479 its certificate, corresponds to HOST. (HOST typically comes from
480 the URL and is what the user thinks he's connecting to.)
482 This assumes that ssl_connect_wget has successfully finished, i.e. that
483 the SSL handshake has been performed and that FD is connected to an
486 If opt.check_cert is true (the default), this returns 1 if the
487 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
488 function always returns 1, but should still be called because it
489 warns the user about any problems with the certificate. */
492 ssl_check_certificate (int fd, const char *host)
495 GENERAL_NAMES *subjectAltNames;
496 char common_name[256];
499 bool alt_name_checked = false;
501 /* If the user has specified --no-check-cert, we still want to warn
502 him about problems with the server's certificate. */
503 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
505 struct openssl_transport_context *ctx = fd_transport_context (fd);
506 SSL *conn = ctx->conn;
507 assert (conn != NULL);
509 cert = SSL_get_peer_certificate (conn);
512 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
513 severity, quotearg_style (escape_quoting_style, host));
515 goto no_cert; /* must bail out since CERT is NULL */
520 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
521 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
522 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
523 quotearg_n_style (0, escape_quoting_style, subject),
524 quotearg_n_style (1, escape_quoting_style, issuer)));
525 OPENSSL_free (subject);
526 OPENSSL_free (issuer);
529 vresult = SSL_get_verify_result (conn);
530 if (vresult != X509_V_OK)
532 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
533 logprintf (LOG_NOTQUIET,
534 _("%s: cannot verify %s's certificate, issued by %s:\n"),
535 severity, quotearg_n_style (0, escape_quoting_style, host),
536 quote_n (1, issuer));
537 /* Try to print more user-friendly (and translated) messages for
538 the frequent verification errors. */
541 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
542 logprintf (LOG_NOTQUIET,
543 _(" Unable to locally verify the issuer's authority.\n"));
545 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
546 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
547 logprintf (LOG_NOTQUIET,
548 _(" Self-signed certificate encountered.\n"));
550 case X509_V_ERR_CERT_NOT_YET_VALID:
551 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
553 case X509_V_ERR_CERT_HAS_EXPIRED:
554 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
557 /* For the less frequent error strings, simply provide the
558 OpenSSL error message. */
559 logprintf (LOG_NOTQUIET, " %s\n",
560 X509_verify_cert_error_string (vresult));
563 /* Fall through, so that the user is warned about *all* issues
564 with the cert (important with --no-check-certificate.) */
567 /* Check that HOST matches the common name in the certificate.
568 #### The following remains to be done:
570 - When matching against common names, it should loop over all
571 common names and choose the most specific one, i.e. the last
572 one, not the first one, which the current code picks.
574 - Ensure that ASN1 strings from the certificate are encoded as
575 UTF-8 which can be meaningfully compared to HOST. */
577 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
581 /* Test subject alternative names */
583 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
584 * Signal it by host_in_octet_string. */
585 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
587 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
589 for (i=0; i < numaltnames; i++)
591 const GENERAL_NAME *name =
592 sk_GENERAL_NAME_value (subjectAltNames, i);
595 if (host_in_octet_string)
597 if (name->type == GEN_IPADD)
599 /* Check for ipAddress */
600 /* TODO: Should we convert between IPv4-mapped IPv6
601 * addresses and IPv4 addresses? */
602 alt_name_checked = true;
603 if (!ASN1_STRING_cmp (host_in_octet_string,
608 else if (name->type == GEN_DNS)
610 /* dNSName should be IA5String (i.e. ASCII), however who
611 * does trust CA? Convert it into UTF-8 for sure. */
612 unsigned char *name_in_utf8 = NULL;
614 /* Check for dNSName */
615 alt_name_checked = true;
617 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
619 /* Compare and check for NULL attack in ASN1_STRING */
620 if (pattern_match ((char *)name_in_utf8, host) &&
621 (strlen ((char *)name_in_utf8) ==
622 ASN1_STRING_length (name->d.dNSName)))
624 OPENSSL_free (name_in_utf8);
627 OPENSSL_free (name_in_utf8);
632 sk_GENERAL_NAME_free (subjectAltNames);
633 if (host_in_octet_string)
634 ASN1_OCTET_STRING_free(host_in_octet_string);
636 if (alt_name_checked == true && i >= numaltnames)
638 logprintf (LOG_NOTQUIET,
639 _("%s: no certificate subject alternative name matches\n"
640 "\trequested host name %s.\n"),
641 severity, quote_n (1, host));
646 if (alt_name_checked == false)
648 /* Test commomName */
649 X509_NAME *xname = X509_get_subject_name(cert);
650 common_name[0] = '\0';
651 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
652 sizeof (common_name));
654 if (!pattern_match (common_name, host))
656 logprintf (LOG_NOTQUIET, _("\
657 %s: certificate common name %s doesn't match requested host name %s.\n"),
658 severity, quote_n (0, common_name), quote_n (1, host));
663 /* We now determine the length of the ASN1 string. If it
664 * differs from common_name's length, then there is a \0
665 * before the string terminates. This can be an instance of a
666 * null-prefix attack.
668 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
672 X509_NAME_ENTRY *xentry;
678 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
684 xentry = X509_NAME_get_entry(xname,i);
685 sdata = X509_NAME_ENTRY_get_data(xentry);
686 if (strlen (common_name) != ASN1_STRING_length (sdata))
688 logprintf (LOG_NOTQUIET, _("\
689 %s: certificate common name is invalid (contains a NUL character).\n\
690 This may be an indication that the host is not who it claims to be\n\
691 (that is, it is not the real %s).\n"),
692 severity, quote (host));
700 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
701 quotearg_style (escape_quoting_style, host)));
705 if (opt.check_cert && !success)
706 logprintf (LOG_NOTQUIET, _("\
707 To connect to %s insecurely, use `--no-check-certificate'.\n"),
708 quotearg_style (escape_quoting_style, host));
710 /* Allow --no-check-cert to disable certificate checking. */
711 return opt.check_cert ? success : true;
715 * vim: tabstop=2 shiftwidth=2 softtabstop=2