label_android_property.c revision 35b01083fe5e34cbd318a78ef9b1a13432ae24d9 
1/*
2 * Property Service contexts backend for labeling Android
3 * property keys
4 */
5
6#include <stdarg.h>
7#include <string.h>
8#include <ctype.h>
9#include <errno.h>
10#include <limits.h>
11#include <sys/types.h>
12#include <sys/stat.h>
13#include "callbacks.h"
14#include "label_internal.h"
15
16/* A property security context specification. */
17typedef struct spec {
18	struct selabel_lookup_rec lr;	 /* holds contexts for lookup result */
19	char *property_key;	         /* property key string */
20} spec_t;
21
22/* Our stored configuration */
23struct saved_data {
24	/*
25	 * The array of specifications is sorted for longest
26	 * prefix match
27	 */
28	spec_t *spec_arr;
29	unsigned int nspec; /* total number of specifications */
30};
31
32static int cmp(const void *A, const void *B)
33{
34	const struct spec *sp1 = A, *sp2 = B;
35
36	if (strncmp(sp1->property_key,"*",1) == 0)
37		return 1;
38	if (strncmp(sp2->property_key,"*",1) == 0)
39		return -1;
40
41	size_t L1 = strlen(sp1->property_key);
42	size_t L2 = strlen(sp2->property_key);
43
44	return (L1 < L2) - (L1 > L2);
45}
46
47/*
48 * Warn about duplicate specifications.
49 */
50static int nodups_specs(struct saved_data *data, const char *path)
51{
52	int rc = 0;
53	unsigned int ii, jj;
54	struct spec *curr_spec, *spec_arr = data->spec_arr;
55
56	for (ii = 0; ii < data->nspec; ii++) {
57		curr_spec = &spec_arr[ii];
58		for (jj = ii + 1; jj < data->nspec; jj++) {
59			if ((!strcmp(spec_arr[jj].property_key, curr_spec->property_key))) {
60				rc = -1;
61				errno = EINVAL;
62				if (strcmp
63				    (spec_arr[jj].lr.ctx_raw,
64				     curr_spec->lr.ctx_raw)) {
65					selinux_log
66						(SELINUX_ERROR,
67						 "%s: Multiple different specifications for %s  (%s and %s).\n",
68						 path, curr_spec->property_key,
69						 spec_arr[jj].lr.ctx_raw,
70						 curr_spec->lr.ctx_raw);
71				} else {
72					selinux_log
73						(SELINUX_ERROR,
74						 "%s: Multiple same specifications for %s.\n",
75						 path, curr_spec->property_key);
76				}
77			}
78		}
79	}
80	return rc;
81}
82
83static int process_line(struct selabel_handle *rec,
84			const char *path, char *line_buf,
85			int pass, unsigned lineno)
86{
87	int items, len;
88	char buf1[BUFSIZ], buf2[BUFSIZ];
89	char *buf_p, *prop = buf1, *context = buf2;
90	struct saved_data *data = (struct saved_data *)rec->data;
91	spec_t *spec_arr = data->spec_arr;
92	unsigned int nspec = data->nspec;
93
94	len = strlen(line_buf);
95	if (line_buf[len - 1] == '\n')
96		line_buf[len - 1] = 0;
97	buf_p = line_buf;
98	while (isspace(*buf_p))
99		buf_p++;
100	/* Skip comment lines and empty lines. */
101	if (*buf_p == '#' || *buf_p == 0)
102		return 0;
103	items = sscanf(line_buf, "%255s %255s", prop, context);
104	if (items != 2) {
105		selinux_log(SELINUX_WARNING,
106			    "%s:  line %d is missing fields, skipping\n", path,
107			    lineno);
108		return 0;
109	}
110
111	if (pass == 1) {
112		/* On the second pass, process and store the specification in spec. */
113		spec_arr[nspec].property_key = strdup(prop);
114		if (!spec_arr[nspec].property_key) {
115			selinux_log(SELINUX_WARNING,
116				    "%s:  out of memory at line %d on prop %s\n",
117				    path, lineno, prop);
118		return -1;
119
120		}
121
122		spec_arr[nspec].lr.ctx_raw = strdup(context);
123		if (!spec_arr[nspec].lr.ctx_raw) {
124			selinux_log(SELINUX_WARNING,
125				    "%s:  out of memory at line %d on context %s\n",
126				    path, lineno, context);
127		return -1;
128		}
129     	}
130
131	data->nspec = ++nspec;
132	return 0;
133}
134
135static int init(struct selabel_handle *rec, struct selinux_opt *opts,
136		unsigned n)
137{
138	struct saved_data *data = (struct saved_data *)rec->data;
139	const char *path = NULL;
140	FILE *fp;
141	char line_buf[BUFSIZ];
142	unsigned int lineno = 0, maxnspec, pass;
143	int status = -1;
144	struct stat sb;
145
146	/* Process arguments */
147	while (n--)
148		switch (opts[n].type) {
149		case SELABEL_OPT_PATH:
150			path = opts[n].value;
151			break;
152		default:
153			selinux_log(SELINUX_WARNING,
154				    "Argument type (%d) not recognized. Skipping\n", opts[n].type);
155			break;
156		}
157
158	/* Open the specification file. */
159	if ((fp = fopen(path, "r")) == NULL)
160		return -1;
161
162	if (fstat(fileno(fp), &sb) < 0)
163		return -1;
164	if (!S_ISREG(sb.st_mode)) {
165		errno = EINVAL;
166		return -1;
167	}
168
169	/*
170	 * Two passes of the specification file. First is to get the size.
171	 * After the first pass, the spec array is malloced to the appropriate
172	 * size. Second pass is to populate the spec array and check for
173	 * dups.
174	 */
175	maxnspec = UINT_MAX / sizeof(spec_t);
176	for (pass = 0; pass < 2; pass++) {
177		data->nspec = 0;
178
179		while (fgets(line_buf, sizeof line_buf - 1, fp)
180		       && data->nspec < maxnspec) {
181			if (process_line(rec, path, line_buf, pass, ++lineno) != 0) {
182				goto finish;
183			}
184		}
185
186		if (pass == 1) {
187			status = nodups_specs(data, path);
188
189			if (status)
190				goto finish;
191		}
192
193		if (pass == 0) {
194
195			if (data->nspec == 0) {
196				status = 0;
197				goto finish;
198			}
199
200			if (NULL == (data->spec_arr =
201				     malloc(sizeof(spec_t) * data->nspec)))
202				goto finish;
203
204			memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
205			maxnspec = data->nspec;
206			rewind(fp);
207		}
208	}
209
210	qsort(data->spec_arr, data->nspec, sizeof(struct spec), cmp);
211
212	status = 0;
213finish:
214	fclose(fp);
215	return status;
216}
217
218/*
219 * Backend interface routines
220 */
221static void closef(struct selabel_handle *rec)
222{
223	struct saved_data *data = (struct saved_data *)rec->data;
224	struct spec *spec;
225	unsigned int i;
226
227	for (i = 0; i < data->nspec; i++) {
228		spec = &data->spec_arr[i];
229		free(spec->property_key);
230		free(spec->lr.ctx_raw);
231		free(spec->lr.ctx_trans);
232	}
233
234	if (data->spec_arr)
235		free(data->spec_arr);
236
237	free(data);
238}
239
240static struct selabel_lookup_rec *lookup(struct selabel_handle *rec,
241					 const char *key,
242					 int __attribute__((unused)) type)
243{
244	struct saved_data *data = (struct saved_data *)rec->data;
245	spec_t *spec_arr = data->spec_arr;
246	unsigned int i;
247	struct selabel_lookup_rec *ret = NULL;
248
249	if (!data->nspec) {
250		errno = ENOENT;
251		goto finish;
252	}
253
254	for (i = 0; i < data->nspec; i++) {
255		if (strncmp(spec_arr[i].property_key, key,
256		    strlen(spec_arr[i].property_key)) == 0) {
257			break;
258		}
259		if (strncmp(spec_arr[i].property_key, "*", 1) == 0)
260			break;
261	}
262
263	if (i >= data->nspec) {
264		/* No matching specification. */
265		errno = ENOENT;
266		goto finish;
267	}
268
269	ret = &spec_arr[i].lr;
270
271finish:
272	return ret;
273}
274
275static void stats(struct selabel_handle __attribute__((unused)) *rec)
276{
277	selinux_log(SELINUX_WARNING, "'stats' functionality not implemented.\n");
278}
279
280int selabel_property_init(struct selabel_handle *rec, struct selinux_opt *opts,
281		      unsigned nopts)
282{
283	struct saved_data *data;
284
285	data = (struct saved_data *)malloc(sizeof(*data));
286	if (!data)
287		return -1;
288	memset(data, 0, sizeof(*data));
289
290	rec->data = data;
291	rec->func_close = &closef;
292	rec->func_stats = &stats;
293	rec->func_lookup = &lookup;
294
295	return init(rec, opts, nopts);
296}
297