1/* 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;
32	const void	*raw_serial;
33	unsigned	raw_serial_size;
34	unsigned	raw_issuer_size;
35	const void	*raw_issuer;
36};
37
38/*
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);
46		kfree(sinfo->signing_cert_id);
47		kfree(sinfo);
48	}
49}
50
51/**
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;
74			pkcs7_free_signed_info(sinfo);
75		}
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;
89	struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
90	int ret;
91
92	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
93	if (!ctx)
94		goto out_no_ctx;
95	ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
96	if (!ctx->msg)
97		goto out_no_msg;
98	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
99	if (!ctx->sinfo)
100		goto out_no_sinfo;
101
102	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);
108	if (ret < 0) {
109		msg = ERR_PTR(ret);
110		goto out;
111	}
112
113	msg = ctx->msg;
114	ctx->msg = NULL;
115
116out:
117	while (ctx->certs) {
118		struct x509_certificate *cert = ctx->certs;
119		ctx->certs = cert->next;
120		x509_free_certificate(cert);
121	}
122	pkcs7_free_signed_info(ctx->sinfo);
123out_no_sinfo:
124	pkcs7_free_message(ctx->msg);
125out_no_msg:
126	kfree(ctx);
127out_no_ctx:
128	return msg;
129}
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
259	x509->index = ++ctx->x509_index;
260	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
263	*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;
351	ctx->raw_serial = value;
352	ctx->raw_serial_size = vlen;
353	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;
364	ctx->raw_issuer = value;
365	ctx->raw_issuer_size = vlen;
366	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;
398	struct pkcs7_signed_info *sinfo = ctx->sinfo;
399	struct asymmetric_key_id *kid;
400
401	/* 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;
413	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
414	if (!ctx->sinfo)
415		return -ENOMEM;
416	return 0;
417}
418