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;
292 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;
305 if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg))
308 ret = SSL_peek (conn, buf, bufsize);
310 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
316 openssl_errstr (int fd, void *arg)
318 struct openssl_transport_context *ctx = arg;
319 unsigned long errcode;
323 /* If there are no SSL-specific errors, just return NULL. */
324 if ((errcode = ERR_get_error ()) == 0)
327 /* Get rid of previous contents of ctx->last_error, if any. */
328 xfree_null (ctx->last_error);
330 /* Iterate over OpenSSL's error stack and accumulate errors in the
331 last_error buffer, separated by "; ". This is better than using
332 a static buffer, which *always* takes up space (and has to be
333 large, to fit more than one error message), whereas these
334 allocations are only performed when there is an actual error. */
338 const char *str = ERR_error_string (errcode, NULL);
339 int len = strlen (str);
341 /* Allocate space for the existing message, plus two more chars
342 for the "; " separator and one for the terminating \0. */
343 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
344 memcpy (errmsg + msglen, str, len);
347 /* Get next error and bail out if there are no more. */
348 errcode = ERR_get_error ();
352 errmsg[msglen++] = ';';
353 errmsg[msglen++] = ' ';
355 errmsg[msglen] = '\0';
357 /* Store the error in ctx->last_error where openssl_close will
358 eventually find it and free it. */
359 ctx->last_error = errmsg;
365 openssl_close (int fd, void *arg)
367 struct openssl_transport_context *ctx = arg;
368 SSL *conn = ctx->conn;
372 xfree_null (ctx->last_error);
377 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
380 /* openssl_transport is the singleton that describes the SSL transport
381 methods provided by this file. */
383 static struct transport_implementation openssl_transport = {
384 openssl_read, openssl_write, openssl_poll,
385 openssl_peek, openssl_errstr, openssl_close
388 /* Perform the SSL handshake on file descriptor FD, which is assumed
389 to be connected to an SSL server. The SSL handle provided by
390 OpenSSL is registered with the file descriptor FD using
391 fd_register_transport, so that subsequent calls to fd_read,
392 fd_write, etc., will use the corresponding SSL functions.
394 Returns true on success, false on failure. */
397 ssl_connect_wget (int fd)
400 struct openssl_transport_context *ctx;
402 DEBUGP (("Initiating SSL handshake.\n"));
404 assert (ssl_ctx != NULL);
405 conn = SSL_new (ssl_ctx);
409 # define FD_TO_SOCKET(X) (X)
411 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
413 SSL_set_connect_state (conn);
414 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
417 ctx = xnew0 (struct openssl_transport_context);
420 /* Register FD with Wget's transport layer, i.e. arrange that our
421 functions are used for reading, writing, and polling. */
422 fd_register_transport (fd, &openssl_transport, ctx);
423 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
424 fd, PTR_FORMAT (conn)));
428 DEBUGP (("SSL handshake failed.\n"));
435 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
437 /* Return true is STRING (case-insensitively) matches PATTERN, false
438 otherwise. The recognized wildcard character is "*", which matches
439 any character in STRING except ".". Any number of the "*" wildcard
440 may be present in the pattern.
442 This is used to match of hosts as indicated in rfc2818: "Names may
443 contain the wildcard character * which is considered to match any
444 single domain name component or component fragment. E.g., *.a.com
445 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
446 not bar.com [or foo.bar.com]."
448 If the pattern contain no wildcards, pattern_match(a, b) is
449 equivalent to !strcasecmp(a, b). */
452 pattern_match (const char *pattern, const char *string)
454 const char *p = pattern, *n = string;
456 for (; (c = c_tolower (*p++)) != '\0'; n++)
459 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
461 for (; *n != '\0'; n++)
462 if (c_tolower (*n) == c && pattern_match (p, n))
464 #ifdef ASTERISK_EXCLUDES_DOT
472 if (c != c_tolower (*n))
478 /* Verify the validity of the certificate presented by the server.
479 Also check that the "common name" of the server, as presented by
480 its certificate, corresponds to HOST. (HOST typically comes from
481 the URL and is what the user thinks he's connecting to.)
483 This assumes that ssl_connect_wget has successfully finished, i.e. that
484 the SSL handshake has been performed and that FD is connected to an
487 If opt.check_cert is true (the default), this returns 1 if the
488 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
489 function always returns 1, but should still be called because it
490 warns the user about any problems with the certificate. */
493 ssl_check_certificate (int fd, const char *host)
496 GENERAL_NAMES *subjectAltNames;
497 char common_name[256];
500 bool alt_name_checked = false;
502 /* If the user has specified --no-check-cert, we still want to warn
503 him about problems with the server's certificate. */
504 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
506 struct openssl_transport_context *ctx = fd_transport_context (fd);
507 SSL *conn = ctx->conn;
508 assert (conn != NULL);
510 cert = SSL_get_peer_certificate (conn);
513 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
514 severity, quotearg_style (escape_quoting_style, host));
516 goto no_cert; /* must bail out since CERT is NULL */
521 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
522 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
523 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
524 quotearg_n_style (0, escape_quoting_style, subject),
525 quotearg_n_style (1, escape_quoting_style, issuer)));
526 OPENSSL_free (subject);
527 OPENSSL_free (issuer);
530 vresult = SSL_get_verify_result (conn);
531 if (vresult != X509_V_OK)
533 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
534 logprintf (LOG_NOTQUIET,
535 _("%s: cannot verify %s's certificate, issued by %s:\n"),
536 severity, quotearg_n_style (0, escape_quoting_style, host),
537 quote_n (1, issuer));
538 /* Try to print more user-friendly (and translated) messages for
539 the frequent verification errors. */
542 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
543 logprintf (LOG_NOTQUIET,
544 _(" Unable to locally verify the issuer's authority.\n"));
546 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
547 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
548 logprintf (LOG_NOTQUIET,
549 _(" Self-signed certificate encountered.\n"));
551 case X509_V_ERR_CERT_NOT_YET_VALID:
552 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
554 case X509_V_ERR_CERT_HAS_EXPIRED:
555 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
558 /* For the less frequent error strings, simply provide the
559 OpenSSL error message. */
560 logprintf (LOG_NOTQUIET, " %s\n",
561 X509_verify_cert_error_string (vresult));
564 /* Fall through, so that the user is warned about *all* issues
565 with the cert (important with --no-check-certificate.) */
568 /* Check that HOST matches the common name in the certificate.
569 #### The following remains to be done:
571 - When matching against common names, it should loop over all
572 common names and choose the most specific one, i.e. the last
573 one, not the first one, which the current code picks.
575 - Ensure that ASN1 strings from the certificate are encoded as
576 UTF-8 which can be meaningfully compared to HOST. */
578 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
582 /* Test subject alternative names */
584 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
585 * Signal it by host_in_octet_string. */
586 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
588 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
590 for (i=0; i < numaltnames; i++)
592 const GENERAL_NAME *name =
593 sk_GENERAL_NAME_value (subjectAltNames, i);
596 if (host_in_octet_string)
598 if (name->type == GEN_IPADD)
600 /* Check for ipAddress */
601 /* TODO: Should we convert between IPv4-mapped IPv6
602 * addresses and IPv4 addresses? */
603 alt_name_checked = true;
604 if (!ASN1_STRING_cmp (host_in_octet_string,
609 else if (name->type == GEN_DNS)
611 /* dNSName should be IA5String (i.e. ASCII), however who
612 * does trust CA? Convert it into UTF-8 for sure. */
613 unsigned char *name_in_utf8 = NULL;
615 /* Check for dNSName */
616 alt_name_checked = true;
618 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
620 /* Compare and check for NULL attack in ASN1_STRING */
621 if (pattern_match ((char *)name_in_utf8, host) &&
622 (strlen ((char *)name_in_utf8) ==
623 ASN1_STRING_length (name->d.dNSName)))
625 OPENSSL_free (name_in_utf8);
628 OPENSSL_free (name_in_utf8);
633 sk_GENERAL_NAME_free (subjectAltNames);
634 if (host_in_octet_string)
635 ASN1_OCTET_STRING_free(host_in_octet_string);
637 if (alt_name_checked == true && i >= numaltnames)
639 logprintf (LOG_NOTQUIET,
640 _("%s: no certificate subject alternative name matches\n"
641 "\trequested host name %s.\n"),
642 severity, quote_n (1, host));
647 if (alt_name_checked == false)
649 /* Test commomName */
650 X509_NAME *xname = X509_get_subject_name(cert);
651 common_name[0] = '\0';
652 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
653 sizeof (common_name));
655 if (!pattern_match (common_name, host))
657 logprintf (LOG_NOTQUIET, _("\
658 %s: certificate common name %s doesn't match requested host name %s.\n"),
659 severity, quote_n (0, common_name), quote_n (1, host));
664 /* We now determine the length of the ASN1 string. If it
665 * differs from common_name's length, then there is a \0
666 * before the string terminates. This can be an instance of a
667 * null-prefix attack.
669 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
673 X509_NAME_ENTRY *xentry;
679 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
685 xentry = X509_NAME_get_entry(xname,i);
686 sdata = X509_NAME_ENTRY_get_data(xentry);
687 if (strlen (common_name) != ASN1_STRING_length (sdata))
689 logprintf (LOG_NOTQUIET, _("\
690 %s: certificate common name is invalid (contains a NUL character).\n\
691 This may be an indication that the host is not who it claims to be\n\
692 (that is, it is not the real %s).\n"),
693 severity, quote (host));
701 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
702 quotearg_style (escape_quoting_style, host)));
706 if (opt.check_cert && !success)
707 logprintf (LOG_NOTQUIET, _("\
708 To connect to %s insecurely, use `--no-check-certificate'.\n"),
709 quotearg_style (escape_quoting_style, host));
711 /* Allow --no-check-cert to disable certificate checking. */
712 return opt.check_cert ? success : true;
716 * vim: tabstop=2 shiftwidth=2 softtabstop=2