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Diffstat (limited to 'src/lib/libtls/tls_verify.c')
-rw-r--r--src/lib/libtls/tls_verify.c394
1 files changed, 0 insertions, 394 deletions
diff --git a/src/lib/libtls/tls_verify.c b/src/lib/libtls/tls_verify.c
deleted file mode 100644
index 2935278383..0000000000
--- a/src/lib/libtls/tls_verify.c
+++ /dev/null
@@ -1,394 +0,0 @@
1/* $OpenBSD: tls_verify.c,v 1.32 2024/12/10 08:40:30 tb Exp $ */
2/*
3 * Copyright (c) 2014 Jeremie Courreges-Anglas <jca@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include <sys/socket.h>
19
20#include <arpa/inet.h>
21#include <netinet/in.h>
22
23#include <string.h>
24
25#include <openssl/x509v3.h>
26
27#include <tls.h>
28#include "tls_internal.h"
29
30static int
31tls_match_name(const char *cert_name, const char *name)
32{
33 const char *cert_domain, *domain, *next_dot;
34
35 if (strcasecmp(cert_name, name) == 0)
36 return 0;
37
38 /* Wildcard match? */
39 if (cert_name[0] == '*') {
40 /*
41 * Valid wildcards:
42 * - "*.domain.tld"
43 * - "*.sub.domain.tld"
44 * - etc.
45 * Reject "*.tld".
46 * No attempt to prevent the use of eg. "*.co.uk".
47 */
48 cert_domain = &cert_name[1];
49 /* Disallow "*" */
50 if (cert_domain[0] == '\0')
51 return -1;
52 /* Disallow "*foo" */
53 if (cert_domain[0] != '.')
54 return -1;
55 /* Disallow "*.." */
56 if (cert_domain[1] == '.')
57 return -1;
58 next_dot = strchr(&cert_domain[1], '.');
59 /* Disallow "*.bar" */
60 if (next_dot == NULL)
61 return -1;
62 /* Disallow "*.bar.." */
63 if (next_dot[1] == '.')
64 return -1;
65
66 domain = strchr(name, '.');
67
68 /* No wildcard match against a name with no host part. */
69 if (name[0] == '.')
70 return -1;
71 /* No wildcard match against a name with no domain part. */
72 if (domain == NULL || strlen(domain) == 1)
73 return -1;
74
75 if (strcasecmp(cert_domain, domain) == 0)
76 return 0;
77 }
78
79 return -1;
80}
81
82/*
83 * See RFC 5280 section 4.2.1.6 for SubjectAltName details.
84 * alt_match is set to 1 if a matching alternate name is found.
85 * alt_exists is set to 1 if any known alternate name exists in the certificate.
86 */
87static int
88tls_check_subject_altname(struct tls *ctx, X509 *cert, const char *name,
89 int *alt_match, int *alt_exists)
90{
91 STACK_OF(GENERAL_NAME) *altname_stack = NULL;
92 union tls_addr addrbuf;
93 int addrlen, type;
94 int count, i;
95 int critical = 0;
96 int rv = -1;
97
98 *alt_match = 0;
99 *alt_exists = 0;
100
101 altname_stack = X509_get_ext_d2i(cert, NID_subject_alt_name, &critical,
102 NULL);
103 if (altname_stack == NULL) {
104 if (critical != -1) {
105 tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
106 "error decoding subjectAltName");
107 goto err;
108 }
109 goto done;
110 }
111
112 if (inet_pton(AF_INET, name, &addrbuf) == 1) {
113 type = GEN_IPADD;
114 addrlen = 4;
115 } else if (inet_pton(AF_INET6, name, &addrbuf) == 1) {
116 type = GEN_IPADD;
117 addrlen = 16;
118 } else {
119 type = GEN_DNS;
120 addrlen = 0;
121 }
122
123 count = sk_GENERAL_NAME_num(altname_stack);
124 for (i = 0; i < count; i++) {
125 GENERAL_NAME *altname;
126
127 altname = sk_GENERAL_NAME_value(altname_stack, i);
128
129 if (altname->type == GEN_DNS || altname->type == GEN_IPADD)
130 *alt_exists = 1;
131
132 if (altname->type != type)
133 continue;
134
135 if (type == GEN_DNS) {
136 const unsigned char *data;
137 int format, len;
138
139 format = ASN1_STRING_type(altname->d.dNSName);
140 if (format == V_ASN1_IA5STRING) {
141 data = ASN1_STRING_get0_data(altname->d.dNSName);
142 len = ASN1_STRING_length(altname->d.dNSName);
143
144 if (len < 0 || (size_t)len != strlen(data)) {
145 tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
146 "error verifying name '%s': "
147 "NUL byte in subjectAltName, "
148 "probably a malicious certificate",
149 name);
150 goto err;
151 }
152
153 /*
154 * Per RFC 5280 section 4.2.1.6:
155 * " " is a legal domain name, but that
156 * dNSName must be rejected.
157 */
158 if (strcmp(data, " ") == 0) {
159 tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
160 "error verifying name '%s': "
161 "a dNSName of \" \" must not be "
162 "used", name);
163 goto err;
164 }
165
166 if (tls_match_name(data, name) == 0) {
167 *alt_match = 1;
168 goto done;
169 }
170 } else {
171#ifdef DEBUG
172 fprintf(stdout, "%s: unhandled subjectAltName "
173 "dNSName encoding (%d)\n", getprogname(),
174 format);
175#endif
176 }
177
178 } else if (type == GEN_IPADD) {
179 const unsigned char *data;
180 int datalen;
181
182 datalen = ASN1_STRING_length(altname->d.iPAddress);
183 data = ASN1_STRING_get0_data(altname->d.iPAddress);
184
185 if (datalen < 0) {
186 tls_set_errorx(ctx, TLS_ERROR_UNKNOWN,
187 "Unexpected negative length for an "
188 "IP address: %d", datalen);
189 goto err;
190 }
191
192 /*
193 * Per RFC 5280 section 4.2.1.6:
194 * IPv4 must use 4 octets and IPv6 must use 16 octets.
195 */
196 if (datalen == addrlen &&
197 memcmp(data, &addrbuf, addrlen) == 0) {
198 *alt_match = 1;
199 goto done;
200 }
201 }
202 }
203
204 done:
205 rv = 0;
206
207 err:
208 sk_GENERAL_NAME_pop_free(altname_stack, GENERAL_NAME_free);
209 return rv;
210}
211
212static int
213tls_get_common_name_internal(X509 *cert, char **out_common_name,
214 unsigned int *out_tlserr, const char **out_errstr)
215{
216 unsigned char *utf8_bytes = NULL;
217 X509_NAME *subject_name;
218 char *common_name = NULL;
219 int common_name_len;
220 ASN1_STRING *data;
221 int lastpos = -1;
222 int rv = -1;
223
224 *out_tlserr = TLS_ERROR_UNKNOWN;
225 *out_errstr = "unknown";
226
227 free(*out_common_name);
228 *out_common_name = NULL;
229
230 subject_name = X509_get_subject_name(cert);
231 if (subject_name == NULL)
232 goto err;
233
234 lastpos = X509_NAME_get_index_by_NID(subject_name,
235 NID_commonName, lastpos);
236 if (lastpos == -1)
237 goto done;
238 if (lastpos < 0)
239 goto err;
240 if (X509_NAME_get_index_by_NID(subject_name, NID_commonName, lastpos)
241 != -1) {
242 /*
243 * Having multiple CN's is possible, and even happened back in
244 * the glory days of mullets and Hammer pants. In anything like
245 * a modern TLS cert, CN is as close to deprecated as it gets,
246 * and having more than one is bad. We therefore fail if we have
247 * more than one CN fed to us in the subject, treating the
248 * certificate as hostile.
249 */
250 *out_tlserr = TLS_ERROR_UNKNOWN;
251 *out_errstr = "error getting common name: "
252 "Certificate subject contains multiple Common Name fields, "
253 "probably a malicious or malformed certificate";
254 goto err;
255 }
256
257 data = X509_NAME_ENTRY_get_data(X509_NAME_get_entry(subject_name,
258 lastpos));
259 /*
260 * Fail if we cannot encode the CN bytes as UTF-8.
261 */
262 if ((common_name_len = ASN1_STRING_to_UTF8(&utf8_bytes, data)) < 0) {
263 *out_tlserr = TLS_ERROR_UNKNOWN;
264 *out_errstr = "error getting common name: "
265 "Common Name field cannot be encoded as a UTF-8 string, "
266 "probably a malicious certificate";
267 goto err;
268 }
269 /*
270 * Fail if the CN is of invalid length. RFC 5280 specifies that a CN
271 * must be between 1 and 64 bytes long.
272 */
273 if (common_name_len < 1 || common_name_len > 64) {
274 *out_tlserr = TLS_ERROR_UNKNOWN;
275 *out_errstr = "error getting common name: "
276 "Common Name field has invalid length, "
277 "probably a malicious certificate";
278 goto err;
279 }
280 /*
281 * Fail if the resulting text contains a NUL byte.
282 */
283 if (memchr(utf8_bytes, 0, common_name_len) != NULL) {
284 *out_tlserr = TLS_ERROR_UNKNOWN;
285 *out_errstr = "error getting common name: "
286 "NUL byte in Common Name field, "
287 "probably a malicious certificate";
288 goto err;
289 }
290
291 common_name = strndup(utf8_bytes, common_name_len);
292 if (common_name == NULL) {
293 *out_tlserr = TLS_ERROR_OUT_OF_MEMORY;
294 *out_errstr = "out of memory";
295 goto err;
296 }
297
298 *out_common_name = common_name;
299 common_name = NULL;
300
301 done:
302 if (*out_common_name == NULL)
303 *out_common_name = strdup("");
304 if (*out_common_name == NULL) {
305 *out_tlserr = TLS_ERROR_OUT_OF_MEMORY;
306 *out_errstr = "out of memory";
307 goto err;
308 }
309
310 rv = 0;
311
312 err:
313 free(utf8_bytes);
314 free(common_name);
315 return rv;
316}
317
318int
319tls_get_common_name(struct tls *ctx, X509 *cert, const char *in_name,
320 char **out_common_name)
321{
322 unsigned int errcode = TLS_ERROR_UNKNOWN;
323 const char *errstr = "unknown";
324
325 if (tls_get_common_name_internal(cert, out_common_name, &errcode,
326 &errstr) == -1) {
327 const char *name = in_name;
328 const char *space = " ";
329
330 if (name == NULL)
331 name = space = "";
332
333 tls_set_errorx(ctx, errcode, "%s%s%s", name, space, errstr);
334 return -1;
335 }
336
337 return 0;
338}
339
340static int
341tls_check_common_name(struct tls *ctx, X509 *cert, const char *name,
342 int *cn_match)
343{
344 char *common_name = NULL;
345 union tls_addr addrbuf;
346 int rv = -1;
347
348 if (tls_get_common_name(ctx, cert, name, &common_name) == -1)
349 goto err;
350 if (strlen(common_name) == 0)
351 goto done;
352
353 /*
354 * We don't want to attempt wildcard matching against IP addresses,
355 * so perform a simple comparison here.
356 */
357 if (inet_pton(AF_INET, name, &addrbuf) == 1 ||
358 inet_pton(AF_INET6, name, &addrbuf) == 1) {
359 if (strcmp(common_name, name) == 0)
360 *cn_match = 1;
361 goto done;
362 }
363
364 if (tls_match_name(common_name, name) == 0)
365 *cn_match = 1;
366
367 done:
368 rv = 0;
369
370 err:
371 free(common_name);
372 return rv;
373}
374
375int
376tls_check_name(struct tls *ctx, X509 *cert, const char *name, int *match)
377{
378 int alt_exists;
379
380 *match = 0;
381
382 if (tls_check_subject_altname(ctx, cert, name, match,
383 &alt_exists) == -1)
384 return -1;
385
386 /*
387 * As per RFC 6125 section 6.4.4, if any known alternate name existed
388 * in the certificate, we do not attempt to match on the CN.
389 */
390 if (*match || alt_exists)
391 return 0;
392
393 return tls_check_common_name(ctx, cert, name, match);
394}
generated by cgit v1.2.3-55-g6feb (git 2.39.1) at 2025-12-26 23:48:52 +0000