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_WANT_READ
265 || (SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
266 && errno == EINTR)));
272 openssl_write (int fd, char *buf, int bufsize, void *arg)
275 struct openssl_transport_context *ctx = arg;
276 SSL *conn = ctx->conn;
278 ret = SSL_write (conn, buf, bufsize);
280 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
286 openssl_poll (int fd, double timeout, int wait_for, void *arg)
288 struct openssl_transport_context *ctx = arg;
289 SSL *conn = ctx->conn;
292 if (SSL_pending (conn))
294 return select_fd (fd, timeout, wait_for);
298 openssl_peek (int fd, char *buf, int bufsize, void *arg)
301 struct openssl_transport_context *ctx = arg;
302 SSL *conn = ctx->conn;
304 ret = SSL_peek (conn, buf, bufsize);
306 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
312 openssl_errstr (int fd, void *arg)
314 struct openssl_transport_context *ctx = arg;
315 unsigned long errcode;
319 /* If there are no SSL-specific errors, just return NULL. */
320 if ((errcode = ERR_get_error ()) == 0)
323 /* Get rid of previous contents of ctx->last_error, if any. */
324 xfree_null (ctx->last_error);
326 /* Iterate over OpenSSL's error stack and accumulate errors in the
327 last_error buffer, separated by "; ". This is better than using
328 a static buffer, which *always* takes up space (and has to be
329 large, to fit more than one error message), whereas these
330 allocations are only performed when there is an actual error. */
334 const char *str = ERR_error_string (errcode, NULL);
335 int len = strlen (str);
337 /* Allocate space for the existing message, plus two more chars
338 for the "; " separator and one for the terminating \0. */
339 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
340 memcpy (errmsg + msglen, str, len);
343 /* Get next error and bail out if there are no more. */
344 errcode = ERR_get_error ();
348 errmsg[msglen++] = ';';
349 errmsg[msglen++] = ' ';
351 errmsg[msglen] = '\0';
353 /* Store the error in ctx->last_error where openssl_close will
354 eventually find it and free it. */
355 ctx->last_error = errmsg;
361 openssl_close (int fd, void *arg)
363 struct openssl_transport_context *ctx = arg;
364 SSL *conn = ctx->conn;
368 xfree_null (ctx->last_error);
373 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
376 /* openssl_transport is the singleton that describes the SSL transport
377 methods provided by this file. */
379 static struct transport_implementation openssl_transport = {
380 openssl_read, openssl_write, openssl_poll,
381 openssl_peek, openssl_errstr, openssl_close
384 /* Perform the SSL handshake on file descriptor FD, which is assumed
385 to be connected to an SSL server. The SSL handle provided by
386 OpenSSL is registered with the file descriptor FD using
387 fd_register_transport, so that subsequent calls to fd_read,
388 fd_write, etc., will use the corresponding SSL functions.
390 Returns true on success, false on failure. */
393 ssl_connect_wget (int fd)
396 struct openssl_transport_context *ctx;
398 DEBUGP (("Initiating SSL handshake.\n"));
400 assert (ssl_ctx != NULL);
401 conn = SSL_new (ssl_ctx);
405 # define FD_TO_SOCKET(X) (X)
407 if (!SSL_set_fd (conn, FD_TO_SOCKET (fd)))
409 SSL_set_connect_state (conn);
410 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
413 ctx = xnew0 (struct openssl_transport_context);
416 /* Register FD with Wget's transport layer, i.e. arrange that our
417 functions are used for reading, writing, and polling. */
418 fd_register_transport (fd, &openssl_transport, ctx);
419 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
420 fd, PTR_FORMAT (conn)));
424 DEBUGP (("SSL handshake failed.\n"));
431 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
433 /* Return true is STRING (case-insensitively) matches PATTERN, false
434 otherwise. The recognized wildcard character is "*", which matches
435 any character in STRING except ".". Any number of the "*" wildcard
436 may be present in the pattern.
438 This is used to match of hosts as indicated in rfc2818: "Names may
439 contain the wildcard character * which is considered to match any
440 single domain name component or component fragment. E.g., *.a.com
441 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
442 not bar.com [or foo.bar.com]."
444 If the pattern contain no wildcards, pattern_match(a, b) is
445 equivalent to !strcasecmp(a, b). */
448 pattern_match (const char *pattern, const char *string)
450 const char *p = pattern, *n = string;
452 for (; (c = c_tolower (*p++)) != '\0'; n++)
455 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
457 for (; *n != '\0'; n++)
458 if (c_tolower (*n) == c && pattern_match (p, n))
460 #ifdef ASTERISK_EXCLUDES_DOT
468 if (c != c_tolower (*n))
474 /* Verify the validity of the certificate presented by the server.
475 Also check that the "common name" of the server, as presented by
476 its certificate, corresponds to HOST. (HOST typically comes from
477 the URL and is what the user thinks he's connecting to.)
479 This assumes that ssl_connect_wget has successfully finished, i.e. that
480 the SSL handshake has been performed and that FD is connected to an
483 If opt.check_cert is true (the default), this returns 1 if the
484 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
485 function always returns 1, but should still be called because it
486 warns the user about any problems with the certificate. */
489 ssl_check_certificate (int fd, const char *host)
492 GENERAL_NAMES *subjectAltNames;
493 char common_name[256];
496 bool alt_name_checked = false;
498 /* If the user has specified --no-check-cert, we still want to warn
499 him about problems with the server's certificate. */
500 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
502 struct openssl_transport_context *ctx = fd_transport_context (fd);
503 SSL *conn = ctx->conn;
504 assert (conn != NULL);
506 cert = SSL_get_peer_certificate (conn);
509 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
510 severity, quotearg_style (escape_quoting_style, host));
512 goto no_cert; /* must bail out since CERT is NULL */
517 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
518 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
519 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
520 quotearg_n_style (0, escape_quoting_style, subject),
521 quotearg_n_style (1, escape_quoting_style, issuer)));
522 OPENSSL_free (subject);
523 OPENSSL_free (issuer);
526 vresult = SSL_get_verify_result (conn);
527 if (vresult != X509_V_OK)
529 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
530 logprintf (LOG_NOTQUIET,
531 _("%s: cannot verify %s's certificate, issued by %s:\n"),
532 severity, quotearg_n_style (0, escape_quoting_style, host),
533 quote_n (1, issuer));
534 /* Try to print more user-friendly (and translated) messages for
535 the frequent verification errors. */
538 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
539 logprintf (LOG_NOTQUIET,
540 _(" Unable to locally verify the issuer's authority.\n"));
542 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
543 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
544 logprintf (LOG_NOTQUIET,
545 _(" Self-signed certificate encountered.\n"));
547 case X509_V_ERR_CERT_NOT_YET_VALID:
548 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
550 case X509_V_ERR_CERT_HAS_EXPIRED:
551 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
554 /* For the less frequent error strings, simply provide the
555 OpenSSL error message. */
556 logprintf (LOG_NOTQUIET, " %s\n",
557 X509_verify_cert_error_string (vresult));
560 /* Fall through, so that the user is warned about *all* issues
561 with the cert (important with --no-check-certificate.) */
564 /* Check that HOST matches the common name in the certificate.
565 #### The following remains to be done:
567 - When matching against common names, it should loop over all
568 common names and choose the most specific one, i.e. the last
569 one, not the first one, which the current code picks.
571 - Ensure that ASN1 strings from the certificate are encoded as
572 UTF-8 which can be meaningfully compared to HOST. */
574 subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
578 /* Test subject alternative names */
580 /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)?
581 * Signal it by host_in_octet_string. */
582 ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (host);
584 int numaltnames = sk_GENERAL_NAME_num (subjectAltNames);
586 for (i=0; i < numaltnames; i++)
588 const GENERAL_NAME *name =
589 sk_GENERAL_NAME_value (subjectAltNames, i);
592 if (host_in_octet_string)
594 if (name->type == GEN_IPADD)
596 /* Check for ipAddress */
597 /* TODO: Should we convert between IPv4-mapped IPv6
598 * addresses and IPv4 addresses? */
599 alt_name_checked = true;
600 if (!ASN1_STRING_cmp (host_in_octet_string,
605 else if (name->type == GEN_DNS)
607 /* dNSName should be IA5String (i.e. ASCII), however who
608 * does trust CA? Convert it into UTF-8 for sure. */
609 unsigned char *name_in_utf8 = NULL;
611 /* Check for dNSName */
612 alt_name_checked = true;
614 if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName))
616 /* Compare and check for NULL attack in ASN1_STRING */
617 if (pattern_match ((char *)name_in_utf8, host) &&
618 (strlen ((char *)name_in_utf8) ==
619 ASN1_STRING_length (name->d.dNSName)))
621 OPENSSL_free (name_in_utf8);
624 OPENSSL_free (name_in_utf8);
629 sk_GENERAL_NAME_free (subjectAltNames);
630 if (host_in_octet_string)
631 ASN1_OCTET_STRING_free(host_in_octet_string);
633 if (alt_name_checked == true && i >= numaltnames)
635 logprintf (LOG_NOTQUIET,
636 _("%s: no certificate subject alternative name matches\n"
637 "\trequested host name %s.\n"),
638 severity, quote_n (1, host));
643 if (alt_name_checked == false)
645 /* Test commomName */
646 X509_NAME *xname = X509_get_subject_name(cert);
647 common_name[0] = '\0';
648 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
649 sizeof (common_name));
651 if (!pattern_match (common_name, host))
653 logprintf (LOG_NOTQUIET, _("\
654 %s: certificate common name %s doesn't match requested host name %s.\n"),
655 severity, quote_n (0, common_name), quote_n (1, host));
660 /* We now determine the length of the ASN1 string. If it
661 * differs from common_name's length, then there is a \0
662 * before the string terminates. This can be an instance of a
663 * null-prefix attack.
665 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
669 X509_NAME_ENTRY *xentry;
675 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
681 xentry = X509_NAME_get_entry(xname,i);
682 sdata = X509_NAME_ENTRY_get_data(xentry);
683 if (strlen (common_name) != ASN1_STRING_length (sdata))
685 logprintf (LOG_NOTQUIET, _("\
686 %s: certificate common name is invalid (contains a NUL character).\n\
687 This may be an indication that the host is not who it claims to be\n\
688 (that is, it is not the real %s).\n"),
689 severity, quote (host));
697 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
698 quotearg_style (escape_quoting_style, host)));
702 if (opt.check_cert && !success)
703 logprintf (LOG_NOTQUIET, _("\
704 To connect to %s insecurely, use `--no-check-certificate'.\n"),
705 quotearg_style (escape_quoting_style, host));
707 /* Allow --no-check-cert to disable certificate checking. */
708 return opt.check_cert ? success : true;
712 * vim: tabstop=2 shiftwidth=2 softtabstop=2