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David Howells2e3fadb2014-07-01 16:40:19 +01001/* PKCS#7 parser
2 *
3 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#define pr_fmt(fmt) "PKCS7: "fmt
13#include <linux/kernel.h>
14#include <linux/export.h>
15#include <linux/slab.h>
16#include <linux/err.h>
17#include <linux/oid_registry.h>
18#include "public_key.h"
19#include "pkcs7_parser.h"
20#include "pkcs7-asn1.h"
21
22struct pkcs7_parse_context {
23 struct pkcs7_message *msg; /* Message being constructed */
24 struct pkcs7_signed_info *sinfo; /* SignedInfo being constructed */
25 struct pkcs7_signed_info **ppsinfo;
26 struct x509_certificate *certs; /* Certificate cache */
27 struct x509_certificate **ppcerts;
28 unsigned long data; /* Start of data */
29 enum OID last_oid; /* Last OID encountered */
30 unsigned x509_index;
31 unsigned sinfo_index;
David Howells46963b72014-09-16 17:36:13 +010032 const void *raw_serial;
33 unsigned raw_serial_size;
34 unsigned raw_issuer_size;
35 const void *raw_issuer;
David Howells2e3fadb2014-07-01 16:40:19 +010036};
37
David Howells3cd09202014-09-16 17:29:03 +010038/*
39 * Free a signed information block.
40 */
41static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
42{
43 if (sinfo) {
44 mpi_free(sinfo->sig.mpi[0]);
45 kfree(sinfo->sig.digest);
David Howells46963b72014-09-16 17:36:13 +010046 kfree(sinfo->signing_cert_id);
David Howells3cd09202014-09-16 17:29:03 +010047 kfree(sinfo);
48 }
49}
50
David Howells2e3fadb2014-07-01 16:40:19 +010051/**
52 * pkcs7_free_message - Free a PKCS#7 message
53 * @pkcs7: The PKCS#7 message to free
54 */
55void pkcs7_free_message(struct pkcs7_message *pkcs7)
56{
57 struct x509_certificate *cert;
58 struct pkcs7_signed_info *sinfo;
59
60 if (pkcs7) {
61 while (pkcs7->certs) {
62 cert = pkcs7->certs;
63 pkcs7->certs = cert->next;
64 x509_free_certificate(cert);
65 }
66 while (pkcs7->crl) {
67 cert = pkcs7->crl;
68 pkcs7->crl = cert->next;
69 x509_free_certificate(cert);
70 }
71 while (pkcs7->signed_infos) {
72 sinfo = pkcs7->signed_infos;
73 pkcs7->signed_infos = sinfo->next;
David Howells3cd09202014-09-16 17:29:03 +010074 pkcs7_free_signed_info(sinfo);
David Howells2e3fadb2014-07-01 16:40:19 +010075 }
76 kfree(pkcs7);
77 }
78}
79EXPORT_SYMBOL_GPL(pkcs7_free_message);
80
81/**
82 * pkcs7_parse_message - Parse a PKCS#7 message
83 * @data: The raw binary ASN.1 encoded message to be parsed
84 * @datalen: The size of the encoded message
85 */
86struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
87{
88 struct pkcs7_parse_context *ctx;
David Howellscecf5d2e2014-09-16 17:29:03 +010089 struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
90 int ret;
David Howells2e3fadb2014-07-01 16:40:19 +010091
David Howells2e3fadb2014-07-01 16:40:19 +010092 ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
93 if (!ctx)
David Howellscecf5d2e2014-09-16 17:29:03 +010094 goto out_no_ctx;
95 ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
96 if (!ctx->msg)
97 goto out_no_msg;
David Howells2e3fadb2014-07-01 16:40:19 +010098 ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
99 if (!ctx->sinfo)
David Howellscecf5d2e2014-09-16 17:29:03 +0100100 goto out_no_sinfo;
David Howells2e3fadb2014-07-01 16:40:19 +0100101
David Howells2e3fadb2014-07-01 16:40:19 +0100102 ctx->data = (unsigned long)data;
103 ctx->ppcerts = &ctx->certs;
104 ctx->ppsinfo = &ctx->msg->signed_infos;
105
106 /* Attempt to decode the signature */
107 ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
David Howellscecf5d2e2014-09-16 17:29:03 +0100108 if (ret < 0) {
109 msg = ERR_PTR(ret);
110 goto out;
111 }
David Howells2e3fadb2014-07-01 16:40:19 +0100112
David Howellscecf5d2e2014-09-16 17:29:03 +0100113 msg = ctx->msg;
114 ctx->msg = NULL;
115
116out:
David Howells2e3fadb2014-07-01 16:40:19 +0100117 while (ctx->certs) {
118 struct x509_certificate *cert = ctx->certs;
119 ctx->certs = cert->next;
120 x509_free_certificate(cert);
121 }
David Howells3cd09202014-09-16 17:29:03 +0100122 pkcs7_free_signed_info(ctx->sinfo);
David Howellscecf5d2e2014-09-16 17:29:03 +0100123out_no_sinfo:
124 pkcs7_free_message(ctx->msg);
125out_no_msg:
David Howells2e3fadb2014-07-01 16:40:19 +0100126 kfree(ctx);
David Howellscecf5d2e2014-09-16 17:29:03 +0100127out_no_ctx:
David Howells2e3fadb2014-07-01 16:40:19 +0100128 return msg;
David Howells2e3fadb2014-07-01 16:40:19 +0100129}
130EXPORT_SYMBOL_GPL(pkcs7_parse_message);
131
132/**
133 * pkcs7_get_content_data - Get access to the PKCS#7 content
134 * @pkcs7: The preparsed PKCS#7 message to access
135 * @_data: Place to return a pointer to the data
136 * @_data_len: Place to return the data length
137 * @want_wrapper: True if the ASN.1 object header should be included in the data
138 *
139 * Get access to the data content of the PKCS#7 message, including, optionally,
140 * the header of the ASN.1 object that contains it. Returns -ENODATA if the
141 * data object was missing from the message.
142 */
143int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
144 const void **_data, size_t *_data_len,
145 bool want_wrapper)
146{
147 size_t wrapper;
148
149 if (!pkcs7->data)
150 return -ENODATA;
151
152 wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
153 *_data = pkcs7->data - wrapper;
154 *_data_len = pkcs7->data_len + wrapper;
155 return 0;
156}
157EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
158
159/*
160 * Note an OID when we find one for later processing when we know how
161 * to interpret it.
162 */
163int pkcs7_note_OID(void *context, size_t hdrlen,
164 unsigned char tag,
165 const void *value, size_t vlen)
166{
167 struct pkcs7_parse_context *ctx = context;
168
169 ctx->last_oid = look_up_OID(value, vlen);
170 if (ctx->last_oid == OID__NR) {
171 char buffer[50];
172 sprint_oid(value, vlen, buffer, sizeof(buffer));
173 printk("PKCS7: Unknown OID: [%lu] %s\n",
174 (unsigned long)value - ctx->data, buffer);
175 }
176 return 0;
177}
178
179/*
180 * Note the digest algorithm for the signature.
181 */
182int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
183 unsigned char tag,
184 const void *value, size_t vlen)
185{
186 struct pkcs7_parse_context *ctx = context;
187
188 switch (ctx->last_oid) {
189 case OID_md4:
190 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD4;
191 break;
192 case OID_md5:
193 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD5;
194 break;
195 case OID_sha1:
196 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA1;
197 break;
198 case OID_sha256:
199 ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA256;
200 break;
201 default:
202 printk("Unsupported digest algo: %u\n", ctx->last_oid);
203 return -ENOPKG;
204 }
205 return 0;
206}
207
208/*
209 * Note the public key algorithm for the signature.
210 */
211int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
212 unsigned char tag,
213 const void *value, size_t vlen)
214{
215 struct pkcs7_parse_context *ctx = context;
216
217 switch (ctx->last_oid) {
218 case OID_rsaEncryption:
219 ctx->sinfo->sig.pkey_algo = PKEY_ALGO_RSA;
220 break;
221 default:
222 printk("Unsupported pkey algo: %u\n", ctx->last_oid);
223 return -ENOPKG;
224 }
225 return 0;
226}
227
228/*
229 * Extract a certificate and store it in the context.
230 */
231int pkcs7_extract_cert(void *context, size_t hdrlen,
232 unsigned char tag,
233 const void *value, size_t vlen)
234{
235 struct pkcs7_parse_context *ctx = context;
236 struct x509_certificate *x509;
237
238 if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
239 pr_debug("Cert began with tag %02x at %lu\n",
240 tag, (unsigned long)ctx - ctx->data);
241 return -EBADMSG;
242 }
243
244 /* We have to correct for the header so that the X.509 parser can start
245 * from the beginning. Note that since X.509 stipulates DER, there
246 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
247 * stipulates BER).
248 */
249 value -= hdrlen;
250 vlen += hdrlen;
251
252 if (((u8*)value)[1] == 0x80)
253 vlen += 2; /* Indefinite length - there should be an EOC */
254
255 x509 = x509_cert_parse(value, vlen);
256 if (IS_ERR(x509))
257 return PTR_ERR(x509);
258
David Howells2e3fadb2014-07-01 16:40:19 +0100259 x509->index = ++ctx->x509_index;
David Howells46963b72014-09-16 17:36:13 +0100260 pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
261 pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
262
David Howells2e3fadb2014-07-01 16:40:19 +0100263 *ctx->ppcerts = x509;
264 ctx->ppcerts = &x509->next;
265 return 0;
266}
267
268/*
269 * Save the certificate list
270 */
271int pkcs7_note_certificate_list(void *context, size_t hdrlen,
272 unsigned char tag,
273 const void *value, size_t vlen)
274{
275 struct pkcs7_parse_context *ctx = context;
276
277 pr_devel("Got cert list (%02x)\n", tag);
278
279 *ctx->ppcerts = ctx->msg->certs;
280 ctx->msg->certs = ctx->certs;
281 ctx->certs = NULL;
282 ctx->ppcerts = &ctx->certs;
283 return 0;
284}
285
286/*
287 * Extract the data from the message and store that and its content type OID in
288 * the context.
289 */
290int pkcs7_note_data(void *context, size_t hdrlen,
291 unsigned char tag,
292 const void *value, size_t vlen)
293{
294 struct pkcs7_parse_context *ctx = context;
295
296 pr_debug("Got data\n");
297
298 ctx->msg->data = value;
299 ctx->msg->data_len = vlen;
300 ctx->msg->data_hdrlen = hdrlen;
301 ctx->msg->data_type = ctx->last_oid;
302 return 0;
303}
304
305/*
306 * Parse authenticated attributes
307 */
308int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
309 unsigned char tag,
310 const void *value, size_t vlen)
311{
312 struct pkcs7_parse_context *ctx = context;
313
314 pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
315
316 switch (ctx->last_oid) {
317 case OID_messageDigest:
318 if (tag != ASN1_OTS)
319 return -EBADMSG;
320 ctx->sinfo->msgdigest = value;
321 ctx->sinfo->msgdigest_len = vlen;
322 return 0;
323 default:
324 return 0;
325 }
326}
327
328/*
329 * Note the set of auth attributes for digestion purposes [RFC2315 9.3]
330 */
331int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
332 unsigned char tag,
333 const void *value, size_t vlen)
334{
335 struct pkcs7_parse_context *ctx = context;
336
337 /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
338 ctx->sinfo->authattrs = value - (hdrlen - 1);
339 ctx->sinfo->authattrs_len = vlen + (hdrlen - 1);
340 return 0;
341}
342
343/*
344 * Note the issuing certificate serial number
345 */
346int pkcs7_sig_note_serial(void *context, size_t hdrlen,
347 unsigned char tag,
348 const void *value, size_t vlen)
349{
350 struct pkcs7_parse_context *ctx = context;
David Howells46963b72014-09-16 17:36:13 +0100351 ctx->raw_serial = value;
352 ctx->raw_serial_size = vlen;
David Howells2e3fadb2014-07-01 16:40:19 +0100353 return 0;
354}
355
356/*
357 * Note the issuer's name
358 */
359int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
360 unsigned char tag,
361 const void *value, size_t vlen)
362{
363 struct pkcs7_parse_context *ctx = context;
David Howells46963b72014-09-16 17:36:13 +0100364 ctx->raw_issuer = value;
365 ctx->raw_issuer_size = vlen;
David Howells2e3fadb2014-07-01 16:40:19 +0100366 return 0;
367}
368
369/*
370 * Note the signature data
371 */
372int pkcs7_sig_note_signature(void *context, size_t hdrlen,
373 unsigned char tag,
374 const void *value, size_t vlen)
375{
376 struct pkcs7_parse_context *ctx = context;
377 MPI mpi;
378
379 BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
380
381 mpi = mpi_read_raw_data(value, vlen);
382 if (!mpi)
383 return -ENOMEM;
384
385 ctx->sinfo->sig.mpi[0] = mpi;
386 ctx->sinfo->sig.nr_mpi = 1;
387 return 0;
388}
389
390/*
391 * Note a signature information block
392 */
393int pkcs7_note_signed_info(void *context, size_t hdrlen,
394 unsigned char tag,
395 const void *value, size_t vlen)
396{
397 struct pkcs7_parse_context *ctx = context;
David Howells46963b72014-09-16 17:36:13 +0100398 struct pkcs7_signed_info *sinfo = ctx->sinfo;
399 struct asymmetric_key_id *kid;
David Howells2e3fadb2014-07-01 16:40:19 +0100400
David Howells46963b72014-09-16 17:36:13 +0100401 /* Generate cert issuer + serial number key ID */
402 kid = asymmetric_key_generate_id(ctx->raw_serial,
403 ctx->raw_serial_size,
404 ctx->raw_issuer,
405 ctx->raw_issuer_size);
406 if (IS_ERR(kid))
407 return PTR_ERR(kid);
408
409 sinfo->signing_cert_id = kid;
410 sinfo->index = ++ctx->sinfo_index;
411 *ctx->ppsinfo = sinfo;
412 ctx->ppsinfo = &sinfo->next;
David Howells2e3fadb2014-07-01 16:40:19 +0100413 ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
414 if (!ctx->sinfo)
415 return -ENOMEM;
416 return 0;
417}