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. */
17 typedef 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 */
23 struct 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
cmp(const void * A,const void * B)32 static 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 */
nodups_specs(struct saved_data * data,const char * path)50 static 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,
60 curr_spec->property_key)) {
61 rc = -1;
62 errno = EINVAL;
63 if (strcmp(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
process_line(struct selabel_handle * rec,const char * path,char * line_buf,int pass,unsigned lineno)83 static int process_line(struct selabel_handle *rec,
84 const char *path, char *line_buf,
85 int pass, unsigned lineno)
86 {
87 int items;
88 char *prop = NULL, *context = NULL;
89 struct saved_data *data = (struct saved_data *)rec->data;
90 spec_t *spec_arr = data->spec_arr;
91 unsigned int nspec = data->nspec;
92 const char *errbuf = NULL;
93
94 items = read_spec_entries(line_buf, &errbuf, 2, &prop, &context);
95 if (items < 0) {
96 items = errno;
97 selinux_log(SELINUX_ERROR,
98 "%s: line %u error due to: %s\n", path,
99 lineno, errbuf ?: strerror(errno));
100 errno = items;
101 return -1;
102 }
103
104 if (items == 0)
105 return items;
106
107 if (items != 2) {
108 selinux_log(SELINUX_ERROR,
109 "%s: line %u is missing fields\n", path,
110 lineno);
111 free(prop);
112 errno = EINVAL;
113 return -1;
114 }
115
116 if (pass == 0) {
117 free(prop);
118 free(context);
119 } else if (pass == 1) {
120 /* On the second pass, process and store the specification in spec. */
121 spec_arr[nspec].property_key = prop;
122 spec_arr[nspec].lr.ctx_raw = context;
123
124 if (rec->validating) {
125 if (selabel_validate(rec, &spec_arr[nspec].lr) < 0) {
126 selinux_log(SELINUX_ERROR,
127 "%s: line %u has invalid context %s\n",
128 path, lineno, spec_arr[nspec].lr.ctx_raw);
129 errno = EINVAL;
130 return -1;
131 }
132 }
133 }
134
135 data->nspec = ++nspec;
136 return 0;
137 }
138
init(struct selabel_handle * rec,const struct selinux_opt * opts,unsigned n)139 static int init(struct selabel_handle *rec, const struct selinux_opt *opts,
140 unsigned n)
141 {
142 struct saved_data *data = (struct saved_data *)rec->data;
143 const char *path = NULL;
144 FILE *fp;
145 char line_buf[BUFSIZ];
146 unsigned int lineno, maxnspec, pass;
147 int status = -1;
148 struct stat sb;
149
150 /* Process arguments */
151 while (n--)
152 switch (opts[n].type) {
153 case SELABEL_OPT_PATH:
154 path = opts[n].value;
155 break;
156 }
157
158 if (!path)
159 return -1;
160
161 /* Open the specification file. */
162 if ((fp = fopen(path, "r")) == NULL)
163 return -1;
164
165 if (fstat(fileno(fp), &sb) < 0)
166 goto finish;
167 errno = EINVAL;
168 if (!S_ISREG(sb.st_mode))
169 goto finish;
170
171 /*
172 * Two passes of the specification file. First is to get the size.
173 * After the first pass, the spec array is malloced to the appropriate
174 * size. Second pass is to populate the spec array and check for
175 * dups.
176 */
177 maxnspec = UINT_MAX / sizeof(spec_t);
178 for (pass = 0; pass < 2; pass++) {
179 data->nspec = 0;
180 lineno = 0;
181
182 while (fgets(line_buf, sizeof(line_buf) - 1, fp)
183 && data->nspec < maxnspec) {
184 if (process_line(rec, path, line_buf, pass, ++lineno)
185 != 0)
186 goto finish;
187 }
188
189 if (pass == 1) {
190 status = nodups_specs(data, path);
191
192 if (status)
193 goto finish;
194 }
195
196 if (pass == 0) {
197 if (data->nspec == 0) {
198 status = 0;
199 goto finish;
200 }
201
202 if (NULL == (data->spec_arr =
203 malloc(sizeof(spec_t) * data->nspec)))
204 goto finish;
205
206 memset(data->spec_arr, 0, sizeof(spec_t) * data->nspec);
207 maxnspec = data->nspec;
208 rewind(fp);
209 }
210 }
211
212 qsort(data->spec_arr, data->nspec, sizeof(struct spec), cmp);
213
214 status = 0;
215 finish:
216 fclose(fp);
217 return status;
218 }
219
220 /*
221 * Backend interface routines
222 */
closef(struct selabel_handle * rec)223 static void closef(struct selabel_handle *rec)
224 {
225 struct saved_data *data = (struct saved_data *)rec->data;
226 struct spec *spec;
227 unsigned int i;
228
229 for (i = 0; i < data->nspec; i++) {
230 spec = &data->spec_arr[i];
231 free(spec->property_key);
232 free(spec->lr.ctx_raw);
233 free(spec->lr.ctx_trans);
234 }
235
236 if (data->spec_arr)
237 free(data->spec_arr);
238
239 free(data);
240 }
241
lookup(struct selabel_handle * rec,const char * key,int type)242 static struct selabel_lookup_rec *lookup(struct selabel_handle *rec,
243 const char *key,
244 int __attribute__((unused)) type)
245 {
246 struct saved_data *data = (struct saved_data *)rec->data;
247 spec_t *spec_arr = data->spec_arr;
248 unsigned int i;
249 struct selabel_lookup_rec *ret = NULL;
250
251 if (!data->nspec) {
252 errno = ENOENT;
253 goto finish;
254 }
255
256 for (i = 0; i < data->nspec; i++) {
257 if (strncmp(spec_arr[i].property_key, key,
258 strlen(spec_arr[i].property_key)) == 0) {
259 break;
260 }
261 if (strncmp(spec_arr[i].property_key, "*", 1) == 0)
262 break;
263 }
264
265 if (i >= data->nspec) {
266 /* No matching specification. */
267 errno = ENOENT;
268 goto finish;
269 }
270
271 ret = &spec_arr[i].lr;
272
273 finish:
274 return ret;
275 }
276
stats(struct selabel_handle * rec)277 static void stats(struct selabel_handle __attribute__((unused)) *rec)
278 {
279 selinux_log(SELINUX_WARNING, "'stats' functionality not implemented.\n");
280 }
281
selabel_property_init(struct selabel_handle * rec,const struct selinux_opt * opts,unsigned nopts)282 int selabel_property_init(struct selabel_handle *rec,
283 const struct selinux_opt *opts,
284 unsigned nopts)
285 {
286 struct saved_data *data;
287
288 data = (struct saved_data *)malloc(sizeof(*data));
289 if (!data)
290 return -1;
291 memset(data, 0, sizeof(*data));
292
293 rec->data = data;
294 rec->func_close = &closef;
295 rec->func_stats = &stats;
296 rec->func_lookup = &lookup;
297
298 return init(rec, opts, nopts);
299 }
300