1/*
2 * Copyright (C) 2013 Politecnico di Torino, Italy
3 *                    TORSEC group -- http://security.polito.it
4 *
5 * Author: Roberto Sassu <roberto.sassu@polito.it>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation, version 2 of the
10 * License.
11 *
12 * File: ima_template_lib.c
13 *      Library of supported template fields.
14 */
15#include <crypto/hash_info.h>
16
17#include "ima_template_lib.h"
18
19static bool ima_template_hash_algo_allowed(u8 algo)
20{
21	if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
22		return true;
23
24	return false;
25}
26
27enum data_formats {
28	DATA_FMT_DIGEST = 0,
29	DATA_FMT_DIGEST_WITH_ALGO,
30	DATA_FMT_STRING,
31	DATA_FMT_HEX
32};
33
34static int ima_write_template_field_data(const void *data, const u32 datalen,
35					 enum data_formats datafmt,
36					 struct ima_field_data *field_data)
37{
38	u8 *buf, *buf_ptr;
39	u32 buflen = datalen;
40
41	if (datafmt == DATA_FMT_STRING)
42		buflen = datalen + 1;
43
44	buf = kzalloc(buflen, GFP_KERNEL);
45	if (!buf)
46		return -ENOMEM;
47
48	memcpy(buf, data, datalen);
49
50	/*
51	 * Replace all space characters with underscore for event names and
52	 * strings. This avoid that, during the parsing of a measurements list,
53	 * filenames with spaces or that end with the suffix ' (deleted)' are
54	 * split into multiple template fields (the space is the delimitator
55	 * character for measurements lists in ASCII format).
56	 */
57	if (datafmt == DATA_FMT_STRING) {
58		for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
59			if (*buf_ptr == ' ')
60				*buf_ptr = '_';
61	}
62
63	field_data->data = buf;
64	field_data->len = buflen;
65	return 0;
66}
67
68static void ima_show_template_data_ascii(struct seq_file *m,
69					 enum ima_show_type show,
70					 enum data_formats datafmt,
71					 struct ima_field_data *field_data)
72{
73	u8 *buf_ptr = field_data->data;
74	u32 buflen = field_data->len;
75
76	switch (datafmt) {
77	case DATA_FMT_DIGEST_WITH_ALGO:
78		buf_ptr = strnchr(field_data->data, buflen, ':');
79		if (buf_ptr != field_data->data)
80			seq_printf(m, "%s", field_data->data);
81
82		/* skip ':' and '\0' */
83		buf_ptr += 2;
84		buflen -= buf_ptr - field_data->data;
85	case DATA_FMT_DIGEST:
86	case DATA_FMT_HEX:
87		if (!buflen)
88			break;
89		ima_print_digest(m, buf_ptr, buflen);
90		break;
91	case DATA_FMT_STRING:
92		seq_printf(m, "%s", buf_ptr);
93		break;
94	default:
95		break;
96	}
97}
98
99static void ima_show_template_data_binary(struct seq_file *m,
100					  enum ima_show_type show,
101					  enum data_formats datafmt,
102					  struct ima_field_data *field_data)
103{
104	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
105	    strlen(field_data->data) : field_data->len;
106
107	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
108		ima_putc(m, &len, sizeof(len));
109
110	if (!len)
111		return;
112
113	ima_putc(m, field_data->data, len);
114}
115
116static void ima_show_template_field_data(struct seq_file *m,
117					 enum ima_show_type show,
118					 enum data_formats datafmt,
119					 struct ima_field_data *field_data)
120{
121	switch (show) {
122	case IMA_SHOW_ASCII:
123		ima_show_template_data_ascii(m, show, datafmt, field_data);
124		break;
125	case IMA_SHOW_BINARY:
126	case IMA_SHOW_BINARY_NO_FIELD_LEN:
127	case IMA_SHOW_BINARY_OLD_STRING_FMT:
128		ima_show_template_data_binary(m, show, datafmt, field_data);
129		break;
130	default:
131		break;
132	}
133}
134
135void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
136			      struct ima_field_data *field_data)
137{
138	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
139}
140
141void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
142				 struct ima_field_data *field_data)
143{
144	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
145				     field_data);
146}
147
148void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
149			      struct ima_field_data *field_data)
150{
151	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
152}
153
154void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
155			   struct ima_field_data *field_data)
156{
157	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
158}
159
160static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
161				       struct ima_field_data *field_data)
162{
163	/*
164	 * digest formats:
165	 *  - DATA_FMT_DIGEST: digest
166	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
167	 *    where <hash algo> is provided if the hash algoritm is not
168	 *    SHA1 or MD5
169	 */
170	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
171	enum data_formats fmt = DATA_FMT_DIGEST;
172	u32 offset = 0;
173
174	if (hash_algo < HASH_ALGO__LAST) {
175		fmt = DATA_FMT_DIGEST_WITH_ALGO;
176		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
177				   hash_algo_name[hash_algo]);
178		buffer[offset] = ':';
179		offset += 2;
180	}
181
182	if (digest)
183		memcpy(buffer + offset, digest, digestsize);
184	else
185		/*
186		 * If digest is NULL, the event being recorded is a violation.
187		 * Make room for the digest by increasing the offset of
188		 * IMA_DIGEST_SIZE.
189		 */
190		offset += IMA_DIGEST_SIZE;
191
192	return ima_write_template_field_data(buffer, offset + digestsize,
193					     fmt, field_data);
194}
195
196/*
197 * This function writes the digest of an event (with size limit).
198 */
199int ima_eventdigest_init(struct integrity_iint_cache *iint, struct file *file,
200			 const unsigned char *filename,
201			 struct evm_ima_xattr_data *xattr_value, int xattr_len,
202			 struct ima_field_data *field_data)
203{
204	struct {
205		struct ima_digest_data hdr;
206		char digest[IMA_MAX_DIGEST_SIZE];
207	} hash;
208	u8 *cur_digest = NULL;
209	u32 cur_digestsize = 0;
210	struct inode *inode;
211	int result;
212
213	memset(&hash, 0, sizeof(hash));
214
215	if (!iint)		/* recording a violation. */
216		goto out;
217
218	if (ima_template_hash_algo_allowed(iint->ima_hash->algo)) {
219		cur_digest = iint->ima_hash->digest;
220		cur_digestsize = iint->ima_hash->length;
221		goto out;
222	}
223
224	if (!file)		/* missing info to re-calculate the digest */
225		return -EINVAL;
226
227	inode = file_inode(file);
228	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
229	    ima_hash_algo : HASH_ALGO_SHA1;
230	result = ima_calc_file_hash(file, &hash.hdr);
231	if (result) {
232		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
233				    filename, "collect_data",
234				    "failed", result, 0);
235		return result;
236	}
237	cur_digest = hash.hdr.digest;
238	cur_digestsize = hash.hdr.length;
239out:
240	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
241					   HASH_ALGO__LAST, field_data);
242}
243
244/*
245 * This function writes the digest of an event (without size limit).
246 */
247int ima_eventdigest_ng_init(struct integrity_iint_cache *iint,
248			    struct file *file, const unsigned char *filename,
249			    struct evm_ima_xattr_data *xattr_value,
250			    int xattr_len, struct ima_field_data *field_data)
251{
252	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
253	u32 cur_digestsize = 0;
254
255	/* If iint is NULL, we are recording a violation. */
256	if (!iint)
257		goto out;
258
259	cur_digest = iint->ima_hash->digest;
260	cur_digestsize = iint->ima_hash->length;
261
262	hash_algo = iint->ima_hash->algo;
263out:
264	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
265					   hash_algo, field_data);
266}
267
268static int ima_eventname_init_common(struct integrity_iint_cache *iint,
269				     struct file *file,
270				     const unsigned char *filename,
271				     struct ima_field_data *field_data,
272				     bool size_limit)
273{
274	const char *cur_filename = NULL;
275	u32 cur_filename_len = 0;
276
277	BUG_ON(filename == NULL && file == NULL);
278
279	if (filename) {
280		cur_filename = filename;
281		cur_filename_len = strlen(filename);
282
283		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
284			goto out;
285	}
286
287	if (file) {
288		cur_filename = file->f_path.dentry->d_name.name;
289		cur_filename_len = strlen(cur_filename);
290	} else
291		/*
292		 * Truncate filename if the latter is too long and
293		 * the file descriptor is not available.
294		 */
295		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
296out:
297	return ima_write_template_field_data(cur_filename, cur_filename_len,
298					     DATA_FMT_STRING, field_data);
299}
300
301/*
302 * This function writes the name of an event (with size limit).
303 */
304int ima_eventname_init(struct integrity_iint_cache *iint, struct file *file,
305		       const unsigned char *filename,
306		       struct evm_ima_xattr_data *xattr_value, int xattr_len,
307		       struct ima_field_data *field_data)
308{
309	return ima_eventname_init_common(iint, file, filename,
310					 field_data, true);
311}
312
313/*
314 * This function writes the name of an event (without size limit).
315 */
316int ima_eventname_ng_init(struct integrity_iint_cache *iint, struct file *file,
317			  const unsigned char *filename,
318			  struct evm_ima_xattr_data *xattr_value, int xattr_len,
319			  struct ima_field_data *field_data)
320{
321	return ima_eventname_init_common(iint, file, filename,
322					 field_data, false);
323}
324
325/*
326 *  ima_eventsig_init - include the file signature as part of the template data
327 */
328int ima_eventsig_init(struct integrity_iint_cache *iint, struct file *file,
329		      const unsigned char *filename,
330		      struct evm_ima_xattr_data *xattr_value, int xattr_len,
331		      struct ima_field_data *field_data)
332{
333	enum data_formats fmt = DATA_FMT_HEX;
334	int rc = 0;
335
336	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
337		goto out;
338
339	rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
340					   field_data);
341out:
342	return rc;
343}
344