1 /* Copyright (c) 2014, Google Inc.
2  *
3  * Permission to use, copy, modify, and/or distribute this software for any
4  * purpose with or without fee is hereby granted, provided that the above
5  * copyright notice and this permission notice appear in all copies.
6  *
7  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
14 
15 #include <openssl/x509.h>
16 
17 #include <assert.h>
18 #include <limits.h>
19 
20 #include <openssl/bytestring.h>
21 #include <openssl/err.h>
22 #include <openssl/mem.h>
23 #include <openssl/obj.h>
24 #include <openssl/pem.h>
25 #include <openssl/stack.h>
26 
27 #include "../bytestring/internal.h"
28 
29 
30 /* pkcs7_parse_header reads the non-certificate/non-CRL prefix of a PKCS#7
31  * SignedData blob from |cbs| and sets |*out| to point to the rest of the
32  * input. If the input is in BER format, then |*der_bytes| will be set to a
33  * pointer that needs to be freed by the caller once they have finished
34  * processing |*out| (which will be pointing into |*der_bytes|).
35  *
36  * It returns one on success or zero on error. On error, |*der_bytes| is
37  * NULL. */
pkcs7_parse_header(uint8_t ** der_bytes,CBS * out,CBS * cbs)38 static int pkcs7_parse_header(uint8_t **der_bytes, CBS *out, CBS *cbs) {
39   size_t der_len;
40   CBS in, content_info, content_type, wrapped_signed_data, signed_data;
41   uint64_t version;
42 
43   /* The input may be in BER format. */
44   *der_bytes = NULL;
45   if (!CBS_asn1_ber_to_der(cbs, der_bytes, &der_len)) {
46     return 0;
47   }
48   if (*der_bytes != NULL) {
49     CBS_init(&in, *der_bytes, der_len);
50   } else {
51     CBS_init(&in, CBS_data(cbs), CBS_len(cbs));
52   }
53 
54   /* See https://tools.ietf.org/html/rfc2315#section-7 */
55   if (!CBS_get_asn1(&in, &content_info, CBS_ASN1_SEQUENCE) ||
56       !CBS_get_asn1(&content_info, &content_type, CBS_ASN1_OBJECT)) {
57     goto err;
58   }
59 
60   if (OBJ_cbs2nid(&content_type) != NID_pkcs7_signed) {
61     OPENSSL_PUT_ERROR(X509, X509_R_NOT_PKCS7_SIGNED_DATA);
62     goto err;
63   }
64 
65   /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
66   if (!CBS_get_asn1(&content_info, &wrapped_signed_data,
67                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) ||
68       !CBS_get_asn1(&wrapped_signed_data, &signed_data, CBS_ASN1_SEQUENCE) ||
69       !CBS_get_asn1_uint64(&signed_data, &version) ||
70       !CBS_get_asn1(&signed_data, NULL /* digests */, CBS_ASN1_SET) ||
71       !CBS_get_asn1(&signed_data, NULL /* content */, CBS_ASN1_SEQUENCE)) {
72     goto err;
73   }
74 
75   if (version < 1) {
76     OPENSSL_PUT_ERROR(X509, X509_R_BAD_PKCS7_VERSION);
77     goto err;
78   }
79 
80   CBS_init(out, CBS_data(&signed_data), CBS_len(&signed_data));
81   return 1;
82 
83 err:
84   if (*der_bytes) {
85     OPENSSL_free(*der_bytes);
86     *der_bytes = NULL;
87   }
88 
89   return 0;
90 }
91 
PKCS7_get_certificates(STACK_OF (X509)* out_certs,CBS * cbs)92 int PKCS7_get_certificates(STACK_OF(X509) *out_certs, CBS *cbs) {
93   CBS signed_data, certificates;
94   uint8_t *der_bytes = NULL;
95   int ret = 0;
96   const size_t initial_certs_len = sk_X509_num(out_certs);
97 
98   if (!pkcs7_parse_header(&der_bytes, &signed_data, cbs)) {
99     return 0;
100   }
101 
102   /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
103   if (!CBS_get_asn1(&signed_data, &certificates,
104                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
105     OPENSSL_PUT_ERROR(X509, X509_R_NO_CERTIFICATES_INCLUDED);
106     goto err;
107   }
108 
109   while (CBS_len(&certificates) > 0) {
110     CBS cert;
111     X509 *x509;
112     const uint8_t *inp;
113 
114     if (!CBS_get_asn1_element(&certificates, &cert, CBS_ASN1_SEQUENCE)) {
115       goto err;
116     }
117 
118     if (CBS_len(&cert) > LONG_MAX) {
119       goto err;
120     }
121     inp = CBS_data(&cert);
122     x509 = d2i_X509(NULL, &inp, (long)CBS_len(&cert));
123     if (!x509) {
124       goto err;
125     }
126 
127     assert(inp == CBS_data(&cert) + CBS_len(&cert));
128 
129     if (sk_X509_push(out_certs, x509) == 0) {
130       X509_free(x509);
131       goto err;
132     }
133   }
134 
135   ret = 1;
136 
137 err:
138   if (der_bytes) {
139     OPENSSL_free(der_bytes);
140   }
141 
142   if (!ret) {
143     while (sk_X509_num(out_certs) != initial_certs_len) {
144       X509 *x509 = sk_X509_pop(out_certs);
145       X509_free(x509);
146     }
147   }
148 
149   return ret;
150 }
151 
PKCS7_get_CRLs(STACK_OF (X509_CRL)* out_crls,CBS * cbs)152 int PKCS7_get_CRLs(STACK_OF(X509_CRL) *out_crls, CBS *cbs) {
153   CBS signed_data, crls;
154   uint8_t *der_bytes = NULL;
155   int ret = 0;
156   const size_t initial_crls_len = sk_X509_CRL_num(out_crls);
157 
158   if (!pkcs7_parse_header(&der_bytes, &signed_data, cbs)) {
159     return 0;
160   }
161 
162   /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
163 
164   /* Even if only CRLs are included, there may be an empty certificates block.
165    * OpenSSL does this, for example. */
166   if (CBS_peek_asn1_tag(&signed_data,
167                         CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) &&
168       !CBS_get_asn1(&signed_data, NULL /* certificates */,
169                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
170     goto err;
171   }
172 
173   if (!CBS_get_asn1(&signed_data, &crls,
174                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1)) {
175     OPENSSL_PUT_ERROR(X509, X509_R_NO_CRLS_INCLUDED);
176     goto err;
177   }
178 
179   while (CBS_len(&crls) > 0) {
180     CBS crl_data;
181     X509_CRL *crl;
182     const uint8_t *inp;
183 
184     if (!CBS_get_asn1_element(&crls, &crl_data, CBS_ASN1_SEQUENCE)) {
185       goto err;
186     }
187 
188     if (CBS_len(&crl_data) > LONG_MAX) {
189       goto err;
190     }
191     inp = CBS_data(&crl_data);
192     crl = d2i_X509_CRL(NULL, &inp, (long)CBS_len(&crl_data));
193     if (!crl) {
194       goto err;
195     }
196 
197     assert(inp == CBS_data(&crl_data) + CBS_len(&crl_data));
198 
199     if (sk_X509_CRL_push(out_crls, crl) == 0) {
200       X509_CRL_free(crl);
201       goto err;
202     }
203   }
204 
205   ret = 1;
206 
207 err:
208   if (der_bytes) {
209     OPENSSL_free(der_bytes);
210   }
211 
212   if (!ret) {
213     while (sk_X509_CRL_num(out_crls) != initial_crls_len) {
214       X509_CRL_free(sk_X509_CRL_pop(out_crls));
215     }
216   }
217 
218   return ret;
219 }
220 
PKCS7_get_PEM_certificates(STACK_OF (X509)* out_certs,BIO * pem_bio)221 int PKCS7_get_PEM_certificates(STACK_OF(X509) *out_certs, BIO *pem_bio) {
222   uint8_t *data;
223   long len;
224   int ret;
225 
226   /* Even though we pass PEM_STRING_PKCS7 as the expected PEM type here, PEM
227    * internally will actually allow several other values too, including
228    * "CERTIFICATE". */
229   if (!PEM_bytes_read_bio(&data, &len, NULL /* PEM type output */,
230                           PEM_STRING_PKCS7, pem_bio,
231                           NULL /* password callback */,
232                           NULL /* password callback argument */)) {
233     return 0;
234   }
235 
236   CBS cbs;
237   CBS_init(&cbs, data, len);
238   ret = PKCS7_get_certificates(out_certs, &cbs);
239   OPENSSL_free(data);
240   return ret;
241 }
242 
PKCS7_get_PEM_CRLs(STACK_OF (X509_CRL)* out_crls,BIO * pem_bio)243 int PKCS7_get_PEM_CRLs(STACK_OF(X509_CRL) *out_crls, BIO *pem_bio) {
244   uint8_t *data;
245   long len;
246   int ret;
247 
248   /* Even though we pass PEM_STRING_PKCS7 as the expected PEM type here, PEM
249    * internally will actually allow several other values too, including
250    * "CERTIFICATE". */
251   if (!PEM_bytes_read_bio(&data, &len, NULL /* PEM type output */,
252                           PEM_STRING_PKCS7, pem_bio,
253                           NULL /* password callback */,
254                           NULL /* password callback argument */)) {
255     return 0;
256   }
257 
258   CBS cbs;
259   CBS_init(&cbs, data, len);
260   ret = PKCS7_get_CRLs(out_crls, &cbs);
261   OPENSSL_free(data);
262   return ret;
263 }
264 
265 /* pkcs7_bundle writes a PKCS#7, SignedData structure to |out| and then calls
266  * |cb| with a CBB to which certificate or CRL data can be written, and the
267  * opaque context pointer, |arg|. The callback can return zero to indicate an
268  * error.
269  *
270  * pkcs7_bundle returns one on success or zero on error. */
pkcs7_bundle(CBB * out,int (* cb)(CBB * out,const void * arg),const void * arg)271 static int pkcs7_bundle(CBB *out, int (*cb)(CBB *out, const void *arg),
272                         const void *arg) {
273   CBB outer_seq, wrapped_seq, seq, version_bytes, digest_algos_set,
274       content_info;
275 
276   /* See https://tools.ietf.org/html/rfc2315#section-7 */
277   if (!CBB_add_asn1(out, &outer_seq, CBS_ASN1_SEQUENCE) ||
278       !OBJ_nid2cbb(&outer_seq, NID_pkcs7_signed) ||
279       !CBB_add_asn1(&outer_seq, &wrapped_seq,
280                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0) ||
281       /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
282       !CBB_add_asn1(&wrapped_seq, &seq, CBS_ASN1_SEQUENCE) ||
283       !CBB_add_asn1(&seq, &version_bytes, CBS_ASN1_INTEGER) ||
284       !CBB_add_u8(&version_bytes, 1) ||
285       !CBB_add_asn1(&seq, &digest_algos_set, CBS_ASN1_SET) ||
286       !CBB_add_asn1(&seq, &content_info, CBS_ASN1_SEQUENCE) ||
287       !OBJ_nid2cbb(&content_info, NID_pkcs7_data) ||
288       !cb(&seq, arg)) {
289     return 0;
290   }
291 
292   return CBB_flush(out);
293 }
294 
pkcs7_bundle_certificates_cb(CBB * out,const void * arg)295 static int pkcs7_bundle_certificates_cb(CBB *out, const void *arg) {
296   const STACK_OF(X509) *certs = arg;
297   size_t i;
298   CBB certificates;
299 
300   /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
301   if (!CBB_add_asn1(out, &certificates,
302                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 0)) {
303     return 0;
304   }
305 
306   for (i = 0; i < sk_X509_num(certs); i++) {
307     X509 *x509 = sk_X509_value(certs, i);
308     uint8_t *buf;
309     int len = i2d_X509(x509, NULL);
310 
311     if (len < 0 ||
312         !CBB_add_space(&certificates, &buf, len) ||
313         i2d_X509(x509, &buf) < 0) {
314       return 0;
315     }
316   }
317 
318   return CBB_flush(out);
319 }
320 
PKCS7_bundle_certificates(CBB * out,const STACK_OF (X509)* certs)321 int PKCS7_bundle_certificates(CBB *out, const STACK_OF(X509) *certs) {
322   return pkcs7_bundle(out, pkcs7_bundle_certificates_cb, certs);
323 }
324 
pkcs7_bundle_crls_cb(CBB * out,const void * arg)325 static int pkcs7_bundle_crls_cb(CBB *out, const void *arg) {
326   const STACK_OF(X509_CRL) *crls = arg;
327   size_t i;
328   CBB crl_data;
329 
330   /* See https://tools.ietf.org/html/rfc2315#section-9.1 */
331   if (!CBB_add_asn1(out, &crl_data,
332                     CBS_ASN1_CONTEXT_SPECIFIC | CBS_ASN1_CONSTRUCTED | 1)) {
333     return 0;
334   }
335 
336   for (i = 0; i < sk_X509_CRL_num(crls); i++) {
337     X509_CRL *crl = sk_X509_CRL_value(crls, i);
338     uint8_t *buf;
339     int len = i2d_X509_CRL(crl, NULL);
340 
341     if (len < 0 ||
342         !CBB_add_space(&crl_data, &buf, len) ||
343         i2d_X509_CRL(crl, &buf) < 0) {
344       return 0;
345     }
346   }
347 
348   return CBB_flush(out);
349 }
350 
PKCS7_bundle_CRLs(CBB * out,const STACK_OF (X509_CRL)* crls)351 int PKCS7_bundle_CRLs(CBB *out, const STACK_OF(X509_CRL) *crls) {
352   return pkcs7_bundle(out, pkcs7_bundle_crls_cb, crls);
353 }
354