1 /* SSL support via OpenSSL library.
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
3 2008 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. */
32 #define USE_GNULIB_ALLOC
43 #include <openssl/ssl.h>
44 #include <openssl/x509.h>
45 #include <openssl/err.h>
46 #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);
216 if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
217 key_type_to_ssl_type (opt.cert_type))
221 if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key,
222 key_type_to_ssl_type (opt.private_key_type))
226 /* Since fd_write unconditionally assumes partial writes (and
227 handles them correctly), allow them in OpenSSL. */
228 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE);
230 /* The OpenSSL library can handle renegotiations automatically, so
232 SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY);
238 SSL_CTX_free (ssl_ctx);
243 struct openssl_transport_context {
244 SSL *conn; /* SSL connection handle */
245 char *last_error; /* last error printed with openssl_errstr */
249 openssl_read (int fd, char *buf, int bufsize, void *arg)
252 struct openssl_transport_context *ctx = arg;
253 SSL *conn = ctx->conn;
255 ret = SSL_read (conn, buf, bufsize);
257 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
263 openssl_write (int fd, char *buf, int bufsize, void *arg)
266 struct openssl_transport_context *ctx = arg;
267 SSL *conn = ctx->conn;
269 ret = SSL_write (conn, buf, bufsize);
271 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
277 openssl_poll (int fd, double timeout, int wait_for, void *arg)
279 struct openssl_transport_context *ctx = arg;
280 SSL *conn = ctx->conn;
283 if (SSL_pending (conn))
285 return select_fd (fd, timeout, wait_for);
289 openssl_peek (int fd, char *buf, int bufsize, void *arg)
292 struct openssl_transport_context *ctx = arg;
293 SSL *conn = ctx->conn;
295 ret = SSL_peek (conn, buf, bufsize);
297 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL
303 openssl_errstr (int fd, void *arg)
305 struct openssl_transport_context *ctx = arg;
306 unsigned long errcode;
310 /* If there are no SSL-specific errors, just return NULL. */
311 if ((errcode = ERR_get_error ()) == 0)
314 /* Get rid of previous contents of ctx->last_error, if any. */
315 xfree_null (ctx->last_error);
317 /* Iterate over OpenSSL's error stack and accumulate errors in the
318 last_error buffer, separated by "; ". This is better than using
319 a static buffer, which *always* takes up space (and has to be
320 large, to fit more than one error message), whereas these
321 allocations are only performed when there is an actual error. */
325 const char *str = ERR_error_string (errcode, NULL);
326 int len = strlen (str);
328 /* Allocate space for the existing message, plus two more chars
329 for the "; " separator and one for the terminating \0. */
330 errmsg = xrealloc (errmsg, msglen + len + 2 + 1);
331 memcpy (errmsg + msglen, str, len);
334 /* Get next error and bail out if there are no more. */
335 errcode = ERR_get_error ();
339 errmsg[msglen++] = ';';
340 errmsg[msglen++] = ' ';
342 errmsg[msglen] = '\0';
344 /* Store the error in ctx->last_error where openssl_close will
345 eventually find it and free it. */
346 ctx->last_error = errmsg;
352 openssl_close (int fd, void *arg)
354 struct openssl_transport_context *ctx = arg;
355 SSL *conn = ctx->conn;
359 xfree_null (ctx->last_error);
362 #if defined(WINDOWS) || defined(MSDOS)
368 DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn)));
371 /* openssl_transport is the singleton that describes the SSL transport
372 methods provided by this file. */
374 static struct transport_implementation openssl_transport = {
375 openssl_read, openssl_write, openssl_poll,
376 openssl_peek, openssl_errstr, openssl_close
379 /* Perform the SSL handshake on file descriptor FD, which is assumed
380 to be connected to an SSL server. The SSL handle provided by
381 OpenSSL is registered with the file descriptor FD using
382 fd_register_transport, so that subsequent calls to fd_read,
383 fd_write, etc., will use the corresponding SSL functions.
385 Returns true on success, false on failure. */
391 struct openssl_transport_context *ctx;
393 DEBUGP (("Initiating SSL handshake.\n"));
395 assert (ssl_ctx != NULL);
396 conn = SSL_new (ssl_ctx);
399 if (!SSL_set_fd (conn, fd))
401 SSL_set_connect_state (conn);
402 if (SSL_connect (conn) <= 0 || conn->state != SSL_ST_OK)
405 ctx = xnew0 (struct openssl_transport_context);
408 /* Register FD with Wget's transport layer, i.e. arrange that our
409 functions are used for reading, writing, and polling. */
410 fd_register_transport (fd, &openssl_transport, ctx);
411 DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n",
412 fd, PTR_FORMAT (conn)));
416 DEBUGP (("SSL handshake failed.\n"));
423 #define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */
425 /* Return true is STRING (case-insensitively) matches PATTERN, false
426 otherwise. The recognized wildcard character is "*", which matches
427 any character in STRING except ".". Any number of the "*" wildcard
428 may be present in the pattern.
430 This is used to match of hosts as indicated in rfc2818: "Names may
431 contain the wildcard character * which is considered to match any
432 single domain name component or component fragment. E.g., *.a.com
433 matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but
434 not bar.com [or foo.bar.com]."
436 If the pattern contain no wildcards, pattern_match(a, b) is
437 equivalent to !strcasecmp(a, b). */
440 pattern_match (const char *pattern, const char *string)
442 const char *p = pattern, *n = string;
444 for (; (c = c_tolower (*p++)) != '\0'; n++)
447 for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p))
449 for (; *n != '\0'; n++)
450 if (c_tolower (*n) == c && pattern_match (p, n))
452 #ifdef ASTERISK_EXCLUDES_DOT
460 if (c != c_tolower (*n))
466 /* Verify the validity of the certificate presented by the server.
467 Also check that the "common name" of the server, as presented by
468 its certificate, corresponds to HOST. (HOST typically comes from
469 the URL and is what the user thinks he's connecting to.)
471 This assumes that ssl_connect has successfully finished, i.e. that
472 the SSL handshake has been performed and that FD is connected to an
475 If opt.check_cert is true (the default), this returns 1 if the
476 certificate is valid, 0 otherwise. If opt.check_cert is 0, the
477 function always returns 1, but should still be called because it
478 warns the user about any problems with the certificate. */
481 ssl_check_certificate (int fd, const char *host)
484 char common_name[256];
488 /* If the user has specified --no-check-cert, we still want to warn
489 him about problems with the server's certificate. */
490 const char *severity = opt.check_cert ? _("ERROR") : _("WARNING");
492 struct openssl_transport_context *ctx = fd_transport_context (fd);
493 SSL *conn = ctx->conn;
494 assert (conn != NULL);
496 cert = SSL_get_peer_certificate (conn);
499 logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
500 severity, escnonprint (host));
502 goto no_cert; /* must bail out since CERT is NULL */
507 char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
508 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
509 DEBUGP (("certificate:\n subject: %s\n issuer: %s\n",
510 escnonprint (subject), escnonprint (issuer)));
511 OPENSSL_free (subject);
512 OPENSSL_free (issuer);
515 vresult = SSL_get_verify_result (conn);
516 if (vresult != X509_V_OK)
518 char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
519 logprintf (LOG_NOTQUIET,
520 _("%s: cannot verify %s's certificate, issued by %s:\n"),
521 severity, escnonprint (host), quote (escnonprint (issuer)));
522 /* Try to print more user-friendly (and translated) messages for
523 the frequent verification errors. */
526 case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
527 logprintf (LOG_NOTQUIET,
528 _(" Unable to locally verify the issuer's authority.\n"));
530 case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN:
531 case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
532 logprintf (LOG_NOTQUIET, _(" Self-signed certificate encountered.\n"));
534 case X509_V_ERR_CERT_NOT_YET_VALID:
535 logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n"));
537 case X509_V_ERR_CERT_HAS_EXPIRED:
538 logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n"));
541 /* For the less frequent error strings, simply provide the
542 OpenSSL error message. */
543 logprintf (LOG_NOTQUIET, " %s\n",
544 X509_verify_cert_error_string (vresult));
547 /* Fall through, so that the user is warned about *all* issues
548 with the cert (important with --no-check-certificate.) */
551 /* Check that HOST matches the common name in the certificate.
552 #### The following remains to be done:
554 - It should use dNSName/ipAddress subjectAltName extensions if
555 available; according to rfc2818: "If a subjectAltName extension
556 of type dNSName is present, that MUST be used as the identity."
558 - When matching against common names, it should loop over all
559 common names and choose the most specific one, i.e. the last
560 one, not the first one, which the current code picks.
562 - Ensure that ASN1 strings from the certificate are encoded as
563 UTF-8 which can be meaningfully compared to HOST. */
565 common_name[0] = '\0';
566 X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
567 NID_commonName, common_name, sizeof (common_name));
568 if (!pattern_match (common_name, host))
570 logprintf (LOG_NOTQUIET, _("\
571 %s: certificate common name %s doesn't match requested host name %s.\n"),
572 severity, quote (escnonprint (common_name)), quote (escnonprint (host)));
577 DEBUGP (("X509 certificate successfully verified and matches host %s\n",
578 escnonprint (host)));
582 if (opt.check_cert && !success)
583 logprintf (LOG_NOTQUIET, _("\
584 To connect to %s insecurely, use `--no-check-certificate'.\n"),
587 /* Allow --no-check-cert to disable certificate checking. */
588 return opt.check_cert ? success : true;