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 
16 #include "ima_template_lib.h"
17 
18 static bool ima_template_hash_algo_allowed(u8 algo)
19 {
20 	if (algo == HASH_ALGO_SHA1 || algo == HASH_ALGO_MD5)
21 		return true;
22 
23 	return false;
24 }
25 
26 enum data_formats {
27 	DATA_FMT_DIGEST = 0,
28 	DATA_FMT_DIGEST_WITH_ALGO,
29 	DATA_FMT_STRING,
30 	DATA_FMT_HEX
31 };
32 
33 static int ima_write_template_field_data(const void *data, const u32 datalen,
34 					 enum data_formats datafmt,
35 					 struct ima_field_data *field_data)
36 {
37 	u8 *buf, *buf_ptr;
38 	u32 buflen = datalen;
39 
40 	if (datafmt == DATA_FMT_STRING)
41 		buflen = datalen + 1;
42 
43 	buf = kzalloc(buflen, GFP_KERNEL);
44 	if (!buf)
45 		return -ENOMEM;
46 
47 	memcpy(buf, data, datalen);
48 
49 	/*
50 	 * Replace all space characters with underscore for event names and
51 	 * strings. This avoid that, during the parsing of a measurements list,
52 	 * filenames with spaces or that end with the suffix ' (deleted)' are
53 	 * split into multiple template fields (the space is the delimitator
54 	 * character for measurements lists in ASCII format).
55 	 */
56 	if (datafmt == DATA_FMT_STRING) {
57 		for (buf_ptr = buf; buf_ptr - buf < datalen; buf_ptr++)
58 			if (*buf_ptr == ' ')
59 				*buf_ptr = '_';
60 	}
61 
62 	field_data->data = buf;
63 	field_data->len = buflen;
64 	return 0;
65 }
66 
67 static void ima_show_template_data_ascii(struct seq_file *m,
68 					 enum ima_show_type show,
69 					 enum data_formats datafmt,
70 					 struct ima_field_data *field_data)
71 {
72 	u8 *buf_ptr = field_data->data;
73 	u32 buflen = field_data->len;
74 
75 	switch (datafmt) {
76 	case DATA_FMT_DIGEST_WITH_ALGO:
77 		buf_ptr = strnchr(field_data->data, buflen, ':');
78 		if (buf_ptr != field_data->data)
79 			seq_printf(m, "%s", field_data->data);
80 
81 		/* skip ':' and '\0' */
82 		buf_ptr += 2;
83 		buflen -= buf_ptr - field_data->data;
84 	case DATA_FMT_DIGEST:
85 	case DATA_FMT_HEX:
86 		if (!buflen)
87 			break;
88 		ima_print_digest(m, buf_ptr, buflen);
89 		break;
90 	case DATA_FMT_STRING:
91 		seq_printf(m, "%s", buf_ptr);
92 		break;
93 	default:
94 		break;
95 	}
96 }
97 
98 static void ima_show_template_data_binary(struct seq_file *m,
99 					  enum ima_show_type show,
100 					  enum data_formats datafmt,
101 					  struct ima_field_data *field_data)
102 {
103 	u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
104 	    strlen(field_data->data) : field_data->len;
105 
106 	if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
107 		u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
108 
109 		ima_putc(m, &field_len, sizeof(field_len));
110 	}
111 
112 	if (!len)
113 		return;
114 
115 	ima_putc(m, field_data->data, len);
116 }
117 
118 static void ima_show_template_field_data(struct seq_file *m,
119 					 enum ima_show_type show,
120 					 enum data_formats datafmt,
121 					 struct ima_field_data *field_data)
122 {
123 	switch (show) {
124 	case IMA_SHOW_ASCII:
125 		ima_show_template_data_ascii(m, show, datafmt, field_data);
126 		break;
127 	case IMA_SHOW_BINARY:
128 	case IMA_SHOW_BINARY_NO_FIELD_LEN:
129 	case IMA_SHOW_BINARY_OLD_STRING_FMT:
130 		ima_show_template_data_binary(m, show, datafmt, field_data);
131 		break;
132 	default:
133 		break;
134 	}
135 }
136 
137 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
138 			      struct ima_field_data *field_data)
139 {
140 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
141 }
142 
143 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
144 				 struct ima_field_data *field_data)
145 {
146 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
147 				     field_data);
148 }
149 
150 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
151 			      struct ima_field_data *field_data)
152 {
153 	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
154 }
155 
156 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
157 			   struct ima_field_data *field_data)
158 {
159 	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
160 }
161 
162 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
163 				       struct ima_field_data *field_data)
164 {
165 	/*
166 	 * digest formats:
167 	 *  - DATA_FMT_DIGEST: digest
168 	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
169 	 *    where <hash algo> is provided if the hash algoritm is not
170 	 *    SHA1 or MD5
171 	 */
172 	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
173 	enum data_formats fmt = DATA_FMT_DIGEST;
174 	u32 offset = 0;
175 
176 	if (hash_algo < HASH_ALGO__LAST) {
177 		fmt = DATA_FMT_DIGEST_WITH_ALGO;
178 		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
179 				   hash_algo_name[hash_algo]);
180 		buffer[offset] = ':';
181 		offset += 2;
182 	}
183 
184 	if (digest)
185 		memcpy(buffer + offset, digest, digestsize);
186 	else
187 		/*
188 		 * If digest is NULL, the event being recorded is a violation.
189 		 * Make room for the digest by increasing the offset of
190 		 * IMA_DIGEST_SIZE.
191 		 */
192 		offset += IMA_DIGEST_SIZE;
193 
194 	return ima_write_template_field_data(buffer, offset + digestsize,
195 					     fmt, field_data);
196 }
197 
198 /*
199  * This function writes the digest of an event (with size limit).
200  */
201 int ima_eventdigest_init(struct ima_event_data *event_data,
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 (event_data->violation)	/* recording a violation. */
216 		goto out;
217 
218 	if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
219 		cur_digest = event_data->iint->ima_hash->digest;
220 		cur_digestsize = event_data->iint->ima_hash->length;
221 		goto out;
222 	}
223 
224 	if (!event_data->file)	/* missing info to re-calculate the digest */
225 		return -EINVAL;
226 
227 	inode = file_inode(event_data->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(event_data->file, &hash.hdr);
231 	if (result) {
232 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
233 				    event_data->filename, "collect_data",
234 				    "failed", result, 0);
235 		return result;
236 	}
237 	cur_digest = hash.hdr.digest;
238 	cur_digestsize = hash.hdr.length;
239 out:
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  */
247 int ima_eventdigest_ng_init(struct ima_event_data *event_data,
248 			    struct ima_field_data *field_data)
249 {
250 	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
251 	u32 cur_digestsize = 0;
252 
253 	if (event_data->violation)	/* recording a violation. */
254 		goto out;
255 
256 	cur_digest = event_data->iint->ima_hash->digest;
257 	cur_digestsize = event_data->iint->ima_hash->length;
258 
259 	hash_algo = event_data->iint->ima_hash->algo;
260 out:
261 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
262 					   hash_algo, field_data);
263 }
264 
265 static int ima_eventname_init_common(struct ima_event_data *event_data,
266 				     struct ima_field_data *field_data,
267 				     bool size_limit)
268 {
269 	const char *cur_filename = NULL;
270 	u32 cur_filename_len = 0;
271 
272 	BUG_ON(event_data->filename == NULL && event_data->file == NULL);
273 
274 	if (event_data->filename) {
275 		cur_filename = event_data->filename;
276 		cur_filename_len = strlen(event_data->filename);
277 
278 		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
279 			goto out;
280 	}
281 
282 	if (event_data->file) {
283 		cur_filename = event_data->file->f_path.dentry->d_name.name;
284 		cur_filename_len = strlen(cur_filename);
285 	} else
286 		/*
287 		 * Truncate filename if the latter is too long and
288 		 * the file descriptor is not available.
289 		 */
290 		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
291 out:
292 	return ima_write_template_field_data(cur_filename, cur_filename_len,
293 					     DATA_FMT_STRING, field_data);
294 }
295 
296 /*
297  * This function writes the name of an event (with size limit).
298  */
299 int ima_eventname_init(struct ima_event_data *event_data,
300 		       struct ima_field_data *field_data)
301 {
302 	return ima_eventname_init_common(event_data, field_data, true);
303 }
304 
305 /*
306  * This function writes the name of an event (without size limit).
307  */
308 int ima_eventname_ng_init(struct ima_event_data *event_data,
309 			  struct ima_field_data *field_data)
310 {
311 	return ima_eventname_init_common(event_data, field_data, false);
312 }
313 
314 /*
315  *  ima_eventsig_init - include the file signature as part of the template data
316  */
317 int ima_eventsig_init(struct ima_event_data *event_data,
318 		      struct ima_field_data *field_data)
319 {
320 	enum data_formats fmt = DATA_FMT_HEX;
321 	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
322 	int xattr_len = event_data->xattr_len;
323 	int rc = 0;
324 
325 	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
326 		goto out;
327 
328 	rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
329 					   field_data);
330 out:
331 	return rc;
332 }
333