1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
3 2009 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. */
41 #include <openssl/ssl.h>
42 #include <openssl/x509.h>
43 #include <openssl/err.h>
44 #include <openssl/rand.h>
51 /* Application-wide SSL context. This is common to all SSL
53 static SSL_CTX *ssl_ctx;
55 /* Initialize the SSL's PRNG using various methods. */
61 const char *random_file;
64 /* The PRNG has been seeded; no further action is necessary. */
67 /* Seed from a file specified by the user. This will be the file
68 specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it
71 random_file = opt.random_file;
74 /* Get the random file name using RAND_file_name. */
76 random_file = RAND_file_name (namebuf, sizeof (namebuf));
79 if (random_file && *random_file)
80 /* Seed at most 16k (apparently arbitrary value borrowed from
81 curl) from random file. */
82 RAND_load_file (random_file, 16384);
87 /* Get random data from EGD if opt.egd_file was used. */
88 if (opt.egd_file && *opt.egd_file)
89 RAND_egd (opt.egd_file);
95 /* Under Windows, we can try to seed the PRNG using screen content.
96 This may or may not work, depending on whether we'll calling Wget
104 #if 0 /* don't do this by default */
108 /* Still not random enough, presumably because neither /dev/random
109 nor EGD were available. Try to seed OpenSSL's PRNG with libc
110 PRNG. This is cryptographically weak and defeats the purpose
111 of using OpenSSL, which is why it is highly discouraged. */
113 logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n"));
115 while (RAND_status () == 0 && maxrand-- > 0)
117 unsigned char rnd = random_number (256);
118 RAND_seed (&rnd, sizeof (rnd));
124 /* Print errors in the OpenSSL error stack. */
130 while ((err = ERR_get_error ()) != 0)
131 logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL));
134 /* Convert keyfile type as used by options.h to a type as accepted by
135 SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file.
137 (options.h intentionally doesn't use values from openssl/ssl.h so
138 it doesn't depend specifically on OpenSSL for SSL functionality.) */
141 key_type_to_ssl_type (enum keyfile_type type)
146 return SSL_FILETYPE_PEM;
148 return SSL_FILETYPE_ASN1;
154 /* Create an SSL Context and set default paths etc. Called the first
155 time an HTTP download is attempted.
157 Returns true on success, false otherwise. */
165 /* The SSL has already been initialized. */
168 /* Init the PRNG. If that fails, bail out. */
170 if (RAND_status () != 1)
172 logprintf (LOG_NOTQUIET,
173 _("Could not seed PRNG; consider using --random-file.\n"));
178 SSL_load_error_strings ();
179 SSLeay_add_all_algorithms ();
180 SSLeay_add_ssl_algorithms ();
182 switch (opt.secure_protocol)
184 case secure_protocol_auto:
185 meth = SSLv23_client_method ();
187 case secure_protocol_sslv2:
188 meth = SSLv2_client_method ();
190 case secure_protocol_sslv3:
191 meth = SSLv3_client_method ();
193 case secure_protocol_tlsv1:
194 meth = TLSv1_client_method ();
200 ssl_ctx = SSL_CTX_new (meth);
204 SSL_CTX_set_default_verify_paths (ssl_ctx);
205 SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory);
207 /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the
208 certificate is invalid. We verify the certificate separately in
209 ssl_check_certificate, which provides much better diagnostics
210 than examining the error stack after a failed SSL_connect. */
211 SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
213 /* Use the private key from the cert file unless otherwise specified. */
214 if (opt.cert_file && !opt.private_key)
216 opt.private_key = opt.cert_file;
217 opt.private_key_type = opt.cert_type;
221 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
222 key_type_to_ssl_type (opt.cert_type))
226 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
227 key_type_to_ssl_type (opt.private_key_type))
231 /* Since fd_write unconditionally assumes partial writes (and
232 handles them correctly), allow them in OpenSSL. */
233 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
235 /* The OpenSSL library can handle renegotiations automatically, so
237 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
243 SSL_CTX_free (ssl_ctx);
248 struct openssl_transport_context {
249 SSL *conn; /* SSL connection handle */
250 char *last_error; /* last error printed with openssl_errstr */
254 openssl_read (int fd, char *buf, int bufsize, void *arg)
257 struct openssl_transport_context *ctx = arg;
258 SSL *conn = ctx->conn;
260 ret = SSL_read (conn, buf, bufsize);
262 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
268 openssl_write (int fd, char *buf, int bufsize, void *arg)
271 struct openssl_transport_context *ctx = arg;
272 SSL *conn = ctx->conn;
274 ret = SSL_write (conn, buf, bufsize);
276 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
282 openssl_poll (int fd, double timeout, int wait_for, void *arg)
284 struct openssl_transport_context *ctx = arg;
285 SSL *conn = ctx->conn;
288 if (SSL_pending (conn))
290 return select_fd (fd, timeout, wait_for);
294 openssl_peek (int fd, char *buf, int bufsize, void *arg)
297 struct openssl_transport_context *ctx = arg;
298 SSL *conn = ctx->conn;
300 ret = SSL_peek (conn, buf, bufsize);
302 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
308 openssl_errstr (int fd, void *arg)
310 struct openssl_transport_context *ctx = arg;
311 unsigned long errcode;
315 /* If there are no SSL-specific errors, just return NULL. */
316 if ((errcode = ERR_get_error ()) == 0)
319 /* Get rid of previous contents of ctx->last_error, if any. */
320 xfree_null (ctx->last_error);
322 /* Iterate over OpenSSL's error stack and accumulate errors in the
323 last_error buffer, separated by "; ". This is better than using
324 a static buffer, which *always* takes up space (and has to be
325 large, to fit more than one error message), whereas these
326 allocations are only performed when there is an actual error. */
330 const char *str = ERR_error_string (errcode, NULL);
331 int len = strlen (str);
333 /* Allocate space for the existing message, plus two more chars
334 for the "; " separator and one for the terminating \0. */
335 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
336 memcpy (errmsg + msglen, str, len);
339 /* Get next error and bail out if there are no more. */
340 errcode = ERR_get_error ();
344 errmsg[msglen++] = ';';
345 errmsg[msglen++] = ' ';
347 errmsg[msglen] = '\0';
349 /* Store the error in ctx->last_error where openssl_close will
350 eventually find it and free it. */
351 ctx->last_error = errmsg;
357 openssl_close (int fd, void *arg)
359 struct openssl_transport_context *ctx = arg;
360 SSL *conn = ctx->conn;
364 xfree_null (ctx->last_error);
367 #if defined(WINDOWS) || defined(USE_WATT32)
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);
404 if (!SSL_set_fd (conn, fd))
406 SSL_set_connect_state (conn);
407 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
410 ctx = xnew0 (struct openssl_transport_context);
413 /* Register FD with Wget's transport layer, i.e. arrange that our
414 functions are used for reading, writing, and polling. */
415 fd_register_transport (fd, &openssl_transport, ctx);
416 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
417 fd, PTR_FORMAT (conn)));
421 DEBUGP (("SSL handshake failed.\n"));
428 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
430 /* Return true is STRING (case-insensitively) matches PATTERN, false
431 otherwise. The recognized wildcard character is "*", which matches
432 any character in STRING except ".". Any number of the "*" wildcard
433 may be present in the pattern.
435 This is used to match of hosts as indicated in rfc2818: "Names may
436 contain the wildcard character * which is considered to match any
437 single domain name component or component fragment. E.g., *.a.com
438 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
439 not bar.com [or foo.bar.com]."
441 If the pattern contain no wildcards, pattern_match(a, b) is
442 equivalent to !strcasecmp(a, b). */
445 pattern_match (const char *pattern, const char *string)
447 const char *p = pattern, *n = string;
449 for (; (c = c_tolower (*p++)) != '\0'; n++)
452 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
454 for (; *n != '\0'; n++)
455 if (c_tolower (*n) == c && pattern_match (p, n))
457 #ifdef ASTERISK_EXCLUDES_DOT
465 if (c != c_tolower (*n))
471 /* Verify the validity of the certificate presented by the server.
472 Also check that the "common name" of the server, as presented by
473 its certificate, corresponds to HOST. (HOST typically comes from
474 the URL and is what the user thinks he's connecting to.)
476 This assumes that ssl_connect_wget has successfully finished, i.e. that
477 the SSL handshake has been performed and that FD is connected to an
480 If opt.check_cert is true (the default), this returns 1 if the
481 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
482 function always returns 1, but should still be called because it
483 warns the user about any problems with the certificate. */
486 ssl_check_certificate (int fd, const char *host)
489 char common_name[256];
493 /* If the user has specified --no-check-cert, we still want to warn
494 him about problems with the server's certificate. */
495 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
497 struct openssl_transport_context *ctx = fd_transport_context (fd);
498 SSL *conn = ctx->conn;
499 assert (conn != NULL);
501 cert = SSL_get_peer_certificate (conn);
504 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
505 severity, quotearg_style (escape_quoting_style, host));
507 goto no_cert; /* must bail out since CERT is NULL */
512 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
513 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
514 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
515 quotearg_n_style (0, escape_quoting_style, subject),
516 quotearg_n_style (1, escape_quoting_style, issuer)));
517 OPENSSL_free (subject);
518 OPENSSL_free (issuer);
521 vresult = SSL_get_verify_result (conn);
522 if (vresult != X509_V_OK)
524 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
525 logprintf (LOG_NOTQUIET,
526 _("%s: cannot verify %s's certificate, issued by %s:\n"),
527 severity, quotearg_n_style (0, escape_quoting_style, host),
528 quote_n (1, issuer));
529 /* Try to print more user-friendly (and translated) messages for
530 the frequent verification errors. */
533 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
534 logprintf (LOG_NOTQUIET,
535 _(" Unable to locally verify the issuer's authority.\n"));
537 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
538 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
539 logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
541 case X509_V_ERR_CERT_NOT_YET_VALID:
542 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
544 case X509_V_ERR_CERT_HAS_EXPIRED:
545 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
548 /* For the less frequent error strings, simply provide the
549 OpenSSL error message. */
550 logprintf (LOG_NOTQUIET, " %s\n",
551 X509_verify_cert_error_string (vresult));
554 /* Fall through, so that the user is warned about *all* issues
555 with the cert (important with --no-check-certificate.) */
558 /* Check that HOST matches the common name in the certificate.
559 #### The following remains to be done:
561 - It should use dNSName/ipAddress subjectAltName extensions if
562 available; according to rfc2818: "If a subjectAltName extension
563 of type dNSName is present, that MUST be used as the identity."
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 X509_NAME *xname = X509_get_subject_name(cert);
573 common_name[0] = '\0';
574 X509_NAME_get_text_by_NID (xname, NID_commonName, common_name,
575 sizeof (common_name));
577 if (!pattern_match (common_name, host))
579 logprintf (LOG_NOTQUIET, _("\
580 %s: certificate common name %s doesn't match requested host name %s.\n"),
581 severity, quote_n (0, common_name), quote_n (1, host));
586 /* We now determine the length of the ASN1 string. If it differs from
587 * common_name's length, then there is a \0 before the string terminates.
588 * This can be an instance of a null-prefix attack.
590 * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
594 X509_NAME_ENTRY *xentry;
600 j = X509_NAME_get_index_by_NID (xname, NID_commonName, i);
606 xentry = X509_NAME_get_entry(xname,i);
607 sdata = X509_NAME_ENTRY_get_data(xentry);
608 if (strlen (common_name) != ASN1_STRING_length (sdata))
610 logprintf (LOG_NOTQUIET, _("\
611 %s: certificate common name is invalid (contains a NUL character).\n\
612 This may be an indication that the host is not who it claims to be\n\
613 (that is, it is not the real %s).\n"),
614 severity, quote (host));
621 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
622 quotearg_style (escape_quoting_style, host)));
626 if (opt.check_cert && !success)
627 logprintf (LOG_NOTQUIET, _("\
628 To connect to %s insecurely, use `--no-check-certificate'.\n"),
629 quotearg_style (escape_quoting_style, host));
631 /* Allow --no-check-cert to disable certificate checking. */
632 return opt.check_cert ? success : true;