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_WANT_READ
267 || (SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
268 && errno == EINTR)));
274 openssl_write (int fd, char *buf, int bufsize, void *arg)
277 struct openssl_transport_context *ctx = arg;
278 SSL *conn = ctx->conn;
280 ret = SSL_write (conn, buf, bufsize);
282 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
288 openssl_poll (int fd, double timeout, int wait_for, void *arg)
290 struct openssl_transport_context *ctx = arg;
291 SSL *conn = ctx->conn;
294 if (SSL_pending (conn))
296 return select_fd (fd, timeout, wait_for);
300 openssl_peek (int fd, char *buf, int bufsize, void *arg)
303 struct openssl_transport_context *ctx = arg;
304 SSL *conn = ctx->conn;
306 ret = SSL_peek (conn, buf, bufsize);
308 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
314 openssl_errstr (int fd, void *arg)
316 struct openssl_transport_context *ctx = arg;
317 unsigned long errcode;
321 /* If there are no SSL-specific errors, just return NULL. */
322 if ((errcode = ERR_get_error ()) == 0)
325 /* Get rid of previous contents of ctx->last_error, if any. */
326 xfree_null (ctx->last_error);
328 /* Iterate over OpenSSL's error stack and accumulate errors in the
329 last_error buffer, separated by "; ". This is better than using
330 a static buffer, which *always* takes up space (and has to be
331 large, to fit more than one error message), whereas these
332 allocations are only performed when there is an actual error. */
336 const char *str = ERR_error_string (errcode, NULL);
337 int len = strlen (str);
339 /* Allocate space for the existing message, plus two more chars
340 for the "; " separator and one for the terminating \0. */
341 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
342 memcpy (errmsg + msglen, str, len);
345 /* Get next error and bail out if there are no more. */
346 errcode = ERR_get_error ();
350 errmsg[msglen++] = ';';
351 errmsg[msglen++] = ' ';
353 errmsg[msglen] = '\0';
355 /* Store the error in ctx->last_error where openssl_close will
356 eventually find it and free it. */
357 ctx->last_error = errmsg;
363 openssl_close (int fd, void *arg)
365 struct openssl_transport_context *ctx = arg;
366 SSL *conn = ctx->conn;
370 xfree_null (ctx->last_error);
375 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
378 /* openssl_transport is the singleton that describes the SSL transport
379 methods provided by this file. */
381 static struct transport_implementation openssl_transport = {
382 openssl_read, openssl_write, openssl_poll,
383 openssl_peek, openssl_errstr, openssl_close
386 /* Perform the SSL handshake on file descriptor FD, which is assumed
387 to be connected to an SSL server. The SSL handle provided by
388 OpenSSL is registered with the file descriptor FD using
389 fd_register_transport, so that subsequent calls to fd_read,
390 fd_write, etc., will use the corresponding SSL functions.
392 Returns true on success, false on failure. */
395 ssl_connect_wget (int fd)
398 struct openssl_transport_context *ctx;
400 DEBUGP (("Initiating SSL handshake.\n"));
402 assert (ssl_ctx != NULL);
403 conn = SSL_new (ssl_ctx);
407 # define FD_TO_SOCKET(X) (X)
409 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
411 SSL_set_connect_state (conn);
412 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
415 ctx = xnew0 (struct openssl_transport_context);
418 /* Register FD with Wget's transport layer, i.e. arrange that our
419 functions are used for reading, writing, and polling. */
420 fd_register_transport (fd, &openssl_transport, ctx);
421 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
422 fd, PTR_FORMAT (conn)));
426 DEBUGP (("SSL handshake failed.\n"));
433 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
435 /* Return true is STRING (case-insensitively) matches PATTERN, false
436 otherwise. The recognized wildcard character is "*", which matches
437 any character in STRING except ".". Any number of the "*" wildcard
438 may be present in the pattern.
440 This is used to match of hosts as indicated in rfc2818: "Names may
441 contain the wildcard character * which is considered to match any
442 single domain name component or component fragment. E.g., *.a.com
443 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
444 not bar.com [or foo.bar.com]."
446 If the pattern contain no wildcards, pattern_match(a, b) is
447 equivalent to !strcasecmp(a, b). */
450 pattern_match (const char *pattern, const char *string)
452 const char *p = pattern, *n = string;
454 for (; (c = c_tolower (*p++)) != '\0'; n++)
457 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
459 for (; *n != '\0'; n++)
460 if (c_tolower (*n) == c && pattern_match (p, n))
462 #ifdef ASTERISK_EXCLUDES_DOT
470 if (c != c_tolower (*n))
476 /* Verify the validity of the certificate presented by the server.
477 Also check that the "common name" of the server, as presented by
478 its certificate, corresponds to HOST. (HOST typically comes from
479 the URL and is what the user thinks he's connecting to.)
481 This assumes that ssl_connect_wget has successfully finished, i.e. that
482 the SSL handshake has been performed and that FD is connected to an
485 If opt.check_cert is true (the default), this returns 1 if the
486 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
487 function always returns 1, but should still be called because it
488 warns the user about any problems with the certificate. */
491 ssl_check_certificate (int fd, const char *host)
494 GENERAL_NAMES *subjectAltNames;
495 char common_name[256];
498 bool alt_name_checked = false;
500 /* If the user has specified --no-check-cert, we still want to warn
501 him about problems with the server's certificate. */
502 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
504 struct openssl_transport_context *ctx = fd_transport_context (fd);
505 SSL *conn = ctx->conn;
506 assert (conn != NULL);
508 cert = SSL_get_peer_certificate (conn);
511 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
512 severity, quotearg_style (escape_quoting_style, host));
514 goto no_cert; /* must bail out since CERT is NULL */
519 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
520 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
521 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
522 quotearg_n_style (0, escape_quoting_style, subject),
523 quotearg_n_style (1, escape_quoting_style, issuer)));
524 OPENSSL_free (subject);
525 OPENSSL_free (issuer);
528 vresult = SSL_get_verify_result (conn);
529 if (vresult != X509_V_OK)
531 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
532 logprintf (LOG_NOTQUIET,
533 _("%s: cannot verify %s's certificate, issued by %s:\n"),
534 severity, quotearg_n_style (0, escape_quoting_style, host),
535 quote_n (1, issuer));
536 /* Try to print more user-friendly (and translated) messages for
537 the frequent verification errors. */
540 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
541 logprintf (LOG_NOTQUIET,
542 _(" Unable to locally verify the issuer's authority.\n"));
544 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
545 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
546 logprintf (LOG_NOTQUIET,
547 _(" Self-signed certificate encountered.\n"));
549 case X509_V_ERR_CERT_NOT_YET_VALID:
550 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
552 case X509_V_ERR_CERT_HAS_EXPIRED:
553 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
556 /* For the less frequent error strings, simply provide the
557 OpenSSL error message. */
558 logprintf (LOG_NOTQUIET, " %s\n",
559 X509_verify_cert_error_string (vresult));
562 /* Fall through, so that the user is warned about *all* issues
563 with the cert (important with --no-check-certificate.) */
566 /* Check that HOST matches the common name in the certificate.
567 #### The following remains to be done:
569 - When matching against common names, it should loop over all
570 common names and choose the most specific one, i.e. the last
571 one, not the first one, which the current code picks.
573 - Ensure that ASN1 strings from the certificate are encoded as
574 UTF-8 which can be meaningfully compared to HOST. */
576 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
580 /* Test subject alternative names */
582 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
583 * Signal it by host_in_octet_string. */
584 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
586 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
588 for (i=0; i < numaltnames; i++)
590 const GENERAL_NAME *name =
591 sk_GENERAL_NAME_value (subjectAltNames, i);
594 if (host_in_octet_string)
596 if (name->type == GEN_IPADD)
598 /* Check for ipAddress */
599 /* TODO: Should we convert between IPv4-mapped IPv6
600 * addresses and IPv4 addresses? */
601 alt_name_checked = true;
602 if (!ASN1_STRING_cmp (host_in_octet_string,
607 else if (name->type == GEN_DNS)
609 /* dNSName should be IA5String (i.e. ASCII), however who
610 * does trust CA? Convert it into UTF-8 for sure. */
611 unsigned char *name_in_utf8 = NULL;
613 /* Check for dNSName */
614 alt_name_checked = true;
616 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
618 /* Compare and check for NULL attack in ASN1_STRING */
619 if (pattern_match ((char *)name_in_utf8, host) &&
620 (strlen ((char *)name_in_utf8) ==
621 ASN1_STRING_length (name->d.dNSName)))
623 OPENSSL_free (name_in_utf8);
626 OPENSSL_free (name_in_utf8);
631 sk_GENERAL_NAME_free (subjectAltNames);
632 if (host_in_octet_string)
633 ASN1_OCTET_STRING_free(host_in_octet_string);
635 if (alt_name_checked == true && i >= numaltnames)
637 logprintf (LOG_NOTQUIET,
638 _("%s: no certificate subject alternative name matches\n"
639 "\trequested host name %s.\n"),
640 severity, quote_n (1, host));
645 if (alt_name_checked == false)
647 /* Test commomName */
648 X509_NAME *xname = X509_get_subject_name(cert);
649 common_name[0] = '\0';
650 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
651 sizeof (common_name));
653 if (!pattern_match (common_name, host))
655 logprintf (LOG_NOTQUIET, _("\
656 %s: certificate common name %s doesn't match requested host name %s.\n"),
657 severity, quote_n (0, common_name), quote_n (1, host));
662 /* We now determine the length of the ASN1 string. If it
663 * differs from common_name's length, then there is a \0
664 * before the string terminates. This can be an instance of a
665 * null-prefix attack.
667 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
671 X509_NAME_ENTRY *xentry;
677 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
683 xentry = X509_NAME_get_entry(xname,i);
684 sdata = X509_NAME_ENTRY_get_data(xentry);
685 if (strlen (common_name) != ASN1_STRING_length (sdata))
687 logprintf (LOG_NOTQUIET, _("\
688 %s: certificate common name is invalid (contains a NUL character).\n\
689 This may be an indication that the host is not who it claims to be\n\
690 (that is, it is not the real %s).\n"),
691 severity, quote (host));
699 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
700 quotearg_style (escape_quoting_style, host)));
704 if (opt.check_cert && !success)
705 logprintf (LOG_NOTQUIET, _("\
706 To connect to %s insecurely, use `--no-check-certificate'.\n"),
707 quotearg_style (escape_quoting_style, host));
709 /* Allow --no-check-cert to disable certificate checking. */
710 return opt.check_cert ? success : true;
714 * vim: tabstop=2 shiftwidth=2 softtabstop=2