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 		ima_putc(m, &len, sizeof(len));
108 
109 	if (!len)
110 		return;
111 
112 	ima_putc(m, field_data->data, len);
113 }
114 
115 static void ima_show_template_field_data(struct seq_file *m,
116 					 enum ima_show_type show,
117 					 enum data_formats datafmt,
118 					 struct ima_field_data *field_data)
119 {
120 	switch (show) {
121 	case IMA_SHOW_ASCII:
122 		ima_show_template_data_ascii(m, show, datafmt, field_data);
123 		break;
124 	case IMA_SHOW_BINARY:
125 	case IMA_SHOW_BINARY_NO_FIELD_LEN:
126 	case IMA_SHOW_BINARY_OLD_STRING_FMT:
127 		ima_show_template_data_binary(m, show, datafmt, field_data);
128 		break;
129 	default:
130 		break;
131 	}
132 }
133 
134 void ima_show_template_digest(struct seq_file *m, enum ima_show_type show,
135 			      struct ima_field_data *field_data)
136 {
137 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST, field_data);
138 }
139 
140 void ima_show_template_digest_ng(struct seq_file *m, enum ima_show_type show,
141 				 struct ima_field_data *field_data)
142 {
143 	ima_show_template_field_data(m, show, DATA_FMT_DIGEST_WITH_ALGO,
144 				     field_data);
145 }
146 
147 void ima_show_template_string(struct seq_file *m, enum ima_show_type show,
148 			      struct ima_field_data *field_data)
149 {
150 	ima_show_template_field_data(m, show, DATA_FMT_STRING, field_data);
151 }
152 
153 void ima_show_template_sig(struct seq_file *m, enum ima_show_type show,
154 			   struct ima_field_data *field_data)
155 {
156 	ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data);
157 }
158 
159 static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo,
160 				       struct ima_field_data *field_data)
161 {
162 	/*
163 	 * digest formats:
164 	 *  - DATA_FMT_DIGEST: digest
165 	 *  - DATA_FMT_DIGEST_WITH_ALGO: [<hash algo>] + ':' + '\0' + digest,
166 	 *    where <hash algo> is provided if the hash algoritm is not
167 	 *    SHA1 or MD5
168 	 */
169 	u8 buffer[CRYPTO_MAX_ALG_NAME + 2 + IMA_MAX_DIGEST_SIZE] = { 0 };
170 	enum data_formats fmt = DATA_FMT_DIGEST;
171 	u32 offset = 0;
172 
173 	if (hash_algo < HASH_ALGO__LAST) {
174 		fmt = DATA_FMT_DIGEST_WITH_ALGO;
175 		offset += snprintf(buffer, CRYPTO_MAX_ALG_NAME + 1, "%s",
176 				   hash_algo_name[hash_algo]);
177 		buffer[offset] = ':';
178 		offset += 2;
179 	}
180 
181 	if (digest)
182 		memcpy(buffer + offset, digest, digestsize);
183 	else
184 		/*
185 		 * If digest is NULL, the event being recorded is a violation.
186 		 * Make room for the digest by increasing the offset of
187 		 * IMA_DIGEST_SIZE.
188 		 */
189 		offset += IMA_DIGEST_SIZE;
190 
191 	return ima_write_template_field_data(buffer, offset + digestsize,
192 					     fmt, field_data);
193 }
194 
195 /*
196  * This function writes the digest of an event (with size limit).
197  */
198 int ima_eventdigest_init(struct ima_event_data *event_data,
199 			 struct ima_field_data *field_data)
200 {
201 	struct {
202 		struct ima_digest_data hdr;
203 		char digest[IMA_MAX_DIGEST_SIZE];
204 	} hash;
205 	u8 *cur_digest = NULL;
206 	u32 cur_digestsize = 0;
207 	struct inode *inode;
208 	int result;
209 
210 	memset(&hash, 0, sizeof(hash));
211 
212 	if (event_data->violation)	/* recording a violation. */
213 		goto out;
214 
215 	if (ima_template_hash_algo_allowed(event_data->iint->ima_hash->algo)) {
216 		cur_digest = event_data->iint->ima_hash->digest;
217 		cur_digestsize = event_data->iint->ima_hash->length;
218 		goto out;
219 	}
220 
221 	if (!event_data->file)	/* missing info to re-calculate the digest */
222 		return -EINVAL;
223 
224 	inode = file_inode(event_data->file);
225 	hash.hdr.algo = ima_template_hash_algo_allowed(ima_hash_algo) ?
226 	    ima_hash_algo : HASH_ALGO_SHA1;
227 	result = ima_calc_file_hash(event_data->file, &hash.hdr);
228 	if (result) {
229 		integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
230 				    event_data->filename, "collect_data",
231 				    "failed", result, 0);
232 		return result;
233 	}
234 	cur_digest = hash.hdr.digest;
235 	cur_digestsize = hash.hdr.length;
236 out:
237 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
238 					   HASH_ALGO__LAST, field_data);
239 }
240 
241 /*
242  * This function writes the digest of an event (without size limit).
243  */
244 int ima_eventdigest_ng_init(struct ima_event_data *event_data,
245 			    struct ima_field_data *field_data)
246 {
247 	u8 *cur_digest = NULL, hash_algo = HASH_ALGO_SHA1;
248 	u32 cur_digestsize = 0;
249 
250 	if (event_data->violation)	/* recording a violation. */
251 		goto out;
252 
253 	cur_digest = event_data->iint->ima_hash->digest;
254 	cur_digestsize = event_data->iint->ima_hash->length;
255 
256 	hash_algo = event_data->iint->ima_hash->algo;
257 out:
258 	return ima_eventdigest_init_common(cur_digest, cur_digestsize,
259 					   hash_algo, field_data);
260 }
261 
262 static int ima_eventname_init_common(struct ima_event_data *event_data,
263 				     struct ima_field_data *field_data,
264 				     bool size_limit)
265 {
266 	const char *cur_filename = NULL;
267 	u32 cur_filename_len = 0;
268 
269 	BUG_ON(event_data->filename == NULL && event_data->file == NULL);
270 
271 	if (event_data->filename) {
272 		cur_filename = event_data->filename;
273 		cur_filename_len = strlen(event_data->filename);
274 
275 		if (!size_limit || cur_filename_len <= IMA_EVENT_NAME_LEN_MAX)
276 			goto out;
277 	}
278 
279 	if (event_data->file) {
280 		cur_filename = event_data->file->f_path.dentry->d_name.name;
281 		cur_filename_len = strlen(cur_filename);
282 	} else
283 		/*
284 		 * Truncate filename if the latter is too long and
285 		 * the file descriptor is not available.
286 		 */
287 		cur_filename_len = IMA_EVENT_NAME_LEN_MAX;
288 out:
289 	return ima_write_template_field_data(cur_filename, cur_filename_len,
290 					     DATA_FMT_STRING, field_data);
291 }
292 
293 /*
294  * This function writes the name of an event (with size limit).
295  */
296 int ima_eventname_init(struct ima_event_data *event_data,
297 		       struct ima_field_data *field_data)
298 {
299 	return ima_eventname_init_common(event_data, field_data, true);
300 }
301 
302 /*
303  * This function writes the name of an event (without size limit).
304  */
305 int ima_eventname_ng_init(struct ima_event_data *event_data,
306 			  struct ima_field_data *field_data)
307 {
308 	return ima_eventname_init_common(event_data, field_data, false);
309 }
310 
311 /*
312  *  ima_eventsig_init - include the file signature as part of the template data
313  */
314 int ima_eventsig_init(struct ima_event_data *event_data,
315 		      struct ima_field_data *field_data)
316 {
317 	enum data_formats fmt = DATA_FMT_HEX;
318 	struct evm_ima_xattr_data *xattr_value = event_data->xattr_value;
319 	int xattr_len = event_data->xattr_len;
320 	int rc = 0;
321 
322 	if ((!xattr_value) || (xattr_value->type != EVM_IMA_XATTR_DIGSIG))
323 		goto out;
324 
325 	rc = ima_write_template_field_data(xattr_value, xattr_len, fmt,
326 					   field_data);
327 out:
328 	return rc;
329 }
330