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;