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 case secure_protocol_sslv2:
190 meth = SSLv2_client_method ();
192 case secure_protocol_sslv3:
193 meth = SSLv3_client_method ();
195 case secure_protocol_tlsv1:
196 meth = TLSv1_client_method ();
202 ssl_ctx = SSL_CTX_new (meth);
206 SSL_CTX_set_default_verify_paths (ssl_ctx);
207 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
209 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
210 certificate is invalid. We verify the certificate separately in
211 ssl_check_certificate, which provides much better diagnostics
212 than examining the error stack after a failed SSL_connect. */
213 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
215 /* Use the private key from the cert file unless otherwise specified. */
216 if (opt.cert_file && !opt.private_key)
218 opt.private_key = opt.cert_file;
219 opt.private_key_type = opt.cert_type;
223 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
224 key_type_to_ssl_type (opt.cert_type))
228 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
229 key_type_to_ssl_type (opt.private_key_type))
233 /* Since fd_write unconditionally assumes partial writes (and
234 handles them correctly), allow them in OpenSSL. */
235 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
237 /* The OpenSSL library can handle renegotiations automatically, so
239 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
245 SSL_CTX_free (ssl_ctx);
250 struct openssl_transport_context {
251 SSL *conn; /* SSL connection handle */
252 char *last_error; /* last error printed with openssl_errstr */
256 openssl_read (int fd, char *buf, int bufsize, void *arg)
259 struct openssl_transport_context *ctx = arg;
260 SSL *conn = ctx->conn;
262 ret = SSL_read (conn, buf, bufsize);
264 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
270 openssl_write (int fd, char *buf, int bufsize, void *arg)
273 struct openssl_transport_context *ctx = arg;
274 SSL *conn = ctx->conn;
276 ret = SSL_write (conn, buf, bufsize);
278 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
284 openssl_poll (int fd, double timeout, int wait_for, void *arg)
286 struct openssl_transport_context *ctx = arg;
287 SSL *conn = ctx->conn;
290 if (SSL_pending (conn))
292 return select_fd (fd, timeout, wait_for);
296 openssl_peek (int fd, char *buf, int bufsize, void *arg)
299 struct openssl_transport_context *ctx = arg;
300 SSL *conn = ctx->conn;
302 ret = SSL_peek (conn, buf, bufsize);
304 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
310 openssl_errstr (int fd, void *arg)
312 struct openssl_transport_context *ctx = arg;
313 unsigned long errcode;
317 /* If there are no SSL-specific errors, just return NULL. */
318 if ((errcode = ERR_get_error ()) == 0)
321 /* Get rid of previous contents of ctx->last_error, if any. */
322 xfree_null (ctx->last_error);
324 /* Iterate over OpenSSL's error stack and accumulate errors in the
325 last_error buffer, separated by "; ". This is better than using
326 a static buffer, which *always* takes up space (and has to be
327 large, to fit more than one error message), whereas these
328 allocations are only performed when there is an actual error. */
332 const char *str = ERR_error_string (errcode, NULL);
333 int len = strlen (str);
335 /* Allocate space for the existing message, plus two more chars
336 for the "; " separator and one for the terminating \0. */
337 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
338 memcpy (errmsg + msglen, str, len);
341 /* Get next error and bail out if there are no more. */
342 errcode = ERR_get_error ();
346 errmsg[msglen++] = ';';
347 errmsg[msglen++] = ' ';
349 errmsg[msglen] = '\0';
351 /* Store the error in ctx->last_error where openssl_close will
352 eventually find it and free it. */
353 ctx->last_error = errmsg;
359 openssl_close (int fd, void *arg)
361 struct openssl_transport_context *ctx = arg;
362 SSL *conn = ctx->conn;
366 xfree_null (ctx->last_error);
371 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
374 /* openssl_transport is the singleton that describes the SSL transport
375 methods provided by this file. */
377 static struct transport_implementation openssl_transport = {
378 openssl_read, openssl_write, openssl_poll,
379 openssl_peek, openssl_errstr, openssl_close
382 /* Perform the SSL handshake on file descriptor FD, which is assumed
383 to be connected to an SSL server. The SSL handle provided by
384 OpenSSL is registered with the file descriptor FD using
385 fd_register_transport, so that subsequent calls to fd_read,
386 fd_write, etc., will use the corresponding SSL functions.
388 Returns true on success, false on failure. */
391 ssl_connect_wget (int fd)
394 struct openssl_transport_context *ctx;
396 DEBUGP (("Initiating SSL handshake.\n"));
398 assert (ssl_ctx != NULL);
399 conn = SSL_new (ssl_ctx);
403 # define FD_TO_SOCKET(X) (X)
405 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
407 SSL_set_connect_state (conn);
408 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
411 ctx = xnew0 (struct openssl_transport_context);
414 /* Register FD with Wget's transport layer, i.e. arrange that our
415 functions are used for reading, writing, and polling. */
416 fd_register_transport (fd, &openssl_transport, ctx);
417 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
418 fd, PTR_FORMAT (conn)));
422 DEBUGP (("SSL handshake failed.\n"));
429 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
431 /* Return true is STRING (case-insensitively) matches PATTERN, false
432 otherwise. The recognized wildcard character is "*", which matches
433 any character in STRING except ".". Any number of the "*" wildcard
434 may be present in the pattern.
436 This is used to match of hosts as indicated in rfc2818: "Names may
437 contain the wildcard character * which is considered to match any
438 single domain name component or component fragment. E.g., *.a.com
439 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
440 not bar.com [or foo.bar.com]."
442 If the pattern contain no wildcards, pattern_match(a, b) is
443 equivalent to !strcasecmp(a, b). */
446 pattern_match (const char *pattern, const char *string)
448 const char *p = pattern, *n = string;
450 for (; (c = c_tolower (*p++)) != '\0'; n++)
453 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
455 for (; *n != '\0'; n++)
456 if (c_tolower (*n) == c && pattern_match (p, n))
458 #ifdef ASTERISK_EXCLUDES_DOT
466 if (c != c_tolower (*n))
472 /* Verify the validity of the certificate presented by the server.
473 Also check that the "common name" of the server, as presented by
474 its certificate, corresponds to HOST. (HOST typically comes from
475 the URL and is what the user thinks he's connecting to.)
477 This assumes that ssl_connect_wget has successfully finished, i.e. that
478 the SSL handshake has been performed and that FD is connected to an
481 If opt.check_cert is true (the default), this returns 1 if the
482 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
483 function always returns 1, but should still be called because it
484 warns the user about any problems with the certificate. */
487 ssl_check_certificate (int fd, const char *host)
490 GENERAL_NAMES *subjectAltNames;
491 char common_name[256];
494 bool alt_name_checked = false;
496 /* If the user has specified --no-check-cert, we still want to warn
497 him about problems with the server's certificate. */
498 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
500 struct openssl_transport_context *ctx = fd_transport_context (fd);
501 SSL *conn = ctx->conn;
502 assert (conn != NULL);
504 cert = SSL_get_peer_certificate (conn);
507 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
508 severity, quotearg_style (escape_quoting_style, host));
510 goto no_cert; /* must bail out since CERT is NULL */
515 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
516 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
517 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
518 quotearg_n_style (0, escape_quoting_style, subject),
519 quotearg_n_style (1, escape_quoting_style, issuer)));
520 OPENSSL_free (subject);
521 OPENSSL_free (issuer);
524 vresult = SSL_get_verify_result (conn);
525 if (vresult != X509_V_OK)
527 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
528 logprintf (LOG_NOTQUIET,
529 _("%s: cannot verify %s's certificate, issued by %s:\n"),
530 severity, quotearg_n_style (0, escape_quoting_style, host),
531 quote_n (1, issuer));
532 /* Try to print more user-friendly (and translated) messages for
533 the frequent verification errors. */
536 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
537 logprintf (LOG_NOTQUIET,
538 _(" Unable to locally verify the issuer's authority.\n"));
540 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
541 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
542 logprintf (LOG_NOTQUIET,
543 _(" Self-signed certificate encountered.\n"));
545 case X509_V_ERR_CERT_NOT_YET_VALID:
546 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
548 case X509_V_ERR_CERT_HAS_EXPIRED:
549 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
552 /* For the less frequent error strings, simply provide the
553 OpenSSL error message. */
554 logprintf (LOG_NOTQUIET, " %s\n",
555 X509_verify_cert_error_string (vresult));
558 /* Fall through, so that the user is warned about *all* issues
559 with the cert (important with --no-check-certificate.) */
562 /* Check that HOST matches the common name in the certificate.
563 #### The following remains to be done:
565 - When matching against common names, it should loop over all
566 common names and choose the most specific one, i.e. the last
567 one, not the first one, which the current code picks.
569 - Ensure that ASN1 strings from the certificate are encoded as
570 UTF-8 which can be meaningfully compared to HOST. */
572 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
576 /* Test subject alternative names */
578 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
579 * Signal it by host_in_octet_string. */
580 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
582 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
584 for (i=0; i < numaltnames; i++)
586 const GENERAL_NAME *name =
587 sk_GENERAL_NAME_value (subjectAltNames, i);
590 if (host_in_octet_string)
592 if (name->type == GEN_IPADD)
594 /* Check for ipAddress */
595 /* TODO: Should we convert between IPv4-mapped IPv6
596 * addresses and IPv4 addresses? */
597 alt_name_checked = true;
598 if (!ASN1_STRING_cmp (host_in_octet_string,
603 else if (name->type == GEN_DNS)
605 /* dNSName should be IA5String (i.e. ASCII), however who
606 * does trust CA? Convert it into UTF-8 for sure. */
607 unsigned char *name_in_utf8 = NULL;
609 /* Check for dNSName */
610 alt_name_checked = true;
612 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
614 /* Compare and check for NULL attack in ASN1_STRING */
615 if (pattern_match ((char *)name_in_utf8, host) &&
616 (strlen ((char *)name_in_utf8) ==
617 ASN1_STRING_length (name->d.dNSName)))
619 OPENSSL_free (name_in_utf8);
622 OPENSSL_free (name_in_utf8);
627 sk_GENERAL_NAME_free (subjectAltNames);
628 if (host_in_octet_string)
629 ASN1_OCTET_STRING_free(host_in_octet_string);
631 if (alt_name_checked == true && i >= numaltnames)
633 logprintf (LOG_NOTQUIET,
634 _("%s: no certificate subject alternative name matches\n"
635 "\trequested host name %s.\n"),
636 severity, quote_n (1, host));
641 if (alt_name_checked == false)
643 /* Test commomName */
644 X509_NAME *xname = X509_get_subject_name(cert);
645 common_name[0] = '\0';
646 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
647 sizeof (common_name));
649 if (!pattern_match (common_name, host))
651 logprintf (LOG_NOTQUIET, _("\
652 %s: certificate common name %s doesn't match requested host name %s.\n"),
653 severity, quote_n (0, common_name), quote_n (1, host));
658 /* We now determine the length of the ASN1 string. If it
659 * differs from common_name's length, then there is a \0
660 * before the string terminates. This can be an instance of a
661 * null-prefix attack.
663 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
667 X509_NAME_ENTRY *xentry;
673 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
679 xentry = X509_NAME_get_entry(xname,i);
680 sdata = X509_NAME_ENTRY_get_data(xentry);
681 if (strlen (common_name) != ASN1_STRING_length (sdata))
683 logprintf (LOG_NOTQUIET, _("\
684 %s: certificate common name is invalid (contains a NUL character).\n\
685 This may be an indication that the host is not who it claims to be\n\
686 (that is, it is not the real %s).\n"),
687 severity, quote (host));
695 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
696 quotearg_style (escape_quoting_style, host)));
700 if (opt.check_cert && !success)
701 logprintf (LOG_NOTQUIET, _("\
702 To connect to %s insecurely, use `--no-check-certificate'.\n"),
703 quotearg_style (escape_quoting_style, host));
705 /* Allow --no-check-cert to disable certificate checking. */
706 return opt.check_cert ? success : true;
710 * vim: tabstop=2 shiftwidth=2 softtabstop=2