summaryrefslogtreecommitdiff
path: root/src/libbasic/src/selinux-util.c
blob: 34d2dcdccff032cbcde6f38620458c1477009b70 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <errno.h>
#include <malloc.h>
#include <stddef.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/un.h>
#include <syslog.h>

#ifdef HAVE_SELINUX
#include <selinux/context.h>
#include <selinux/label.h>
#include <selinux/selinux.h>
#endif

#include "basic/alloc-util.h"
#include "basic/log.h"
#include "basic/macro.h"
#include "basic/path-util.h"
#include "basic/selinux-util.h"
#include "basic/time-util.h"
#include "basic/util.h"

#ifdef HAVE_SELINUX
DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon);
DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);

#define _cleanup_security_context_free_ _cleanup_(freeconp)
#define _cleanup_context_free_ _cleanup_(context_freep)

static int cached_use = -1;
static struct selabel_handle *label_hnd = NULL;

#define log_enforcing(...) log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, __VA_ARGS__)
#endif

bool mac_selinux_have(void) {
#ifdef HAVE_SELINUX
        if (cached_use < 0)
                cached_use = is_selinux_enabled() > 0;

        return cached_use;
#else
        return false;
#endif
}

bool mac_selinux_use(void) {
        if (!mac_selinux_have())
                return false;

        /* Never try to configure SELinux features if we aren't
         * root */

        return getuid() == 0;
}

void mac_selinux_retest(void) {
#ifdef HAVE_SELINUX
        cached_use = -1;
#endif
}

int mac_selinux_init(void) {
        int r = 0;

#ifdef HAVE_SELINUX
        usec_t before_timestamp, after_timestamp;
        struct mallinfo before_mallinfo, after_mallinfo;

        if (label_hnd)
                return 0;

        if (!mac_selinux_use())
                return 0;

        before_mallinfo = mallinfo();
        before_timestamp = now(CLOCK_MONOTONIC);

        label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
        if (!label_hnd) {
                log_enforcing("Failed to initialize SELinux context: %m");
                r = security_getenforce() == 1 ? -errno : 0;
        } else  {
                char timespan[FORMAT_TIMESPAN_MAX];
                int l;

                after_timestamp = now(CLOCK_MONOTONIC);
                after_mallinfo = mallinfo();

                l = after_mallinfo.uordblks > before_mallinfo.uordblks ? after_mallinfo.uordblks - before_mallinfo.uordblks : 0;

                log_debug("Successfully loaded SELinux database in %s, size on heap is %iK.",
                          format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0),
                          (l+1023)/1024);
        }
#endif

        return r;
}

void mac_selinux_finish(void) {

#ifdef HAVE_SELINUX
        if (!label_hnd)
                return;

        selabel_close(label_hnd);
        label_hnd = NULL;
#endif
}

int mac_selinux_fix(const char *path, bool ignore_enoent, bool ignore_erofs) {

#ifdef HAVE_SELINUX
        struct stat st;
        int r;

        assert(path);

        /* if mac_selinux_init() wasn't called before we are a NOOP */
        if (!label_hnd)
                return 0;

        r = lstat(path, &st);
        if (r >= 0) {
                _cleanup_security_context_free_ security_context_t fcon = NULL;

                r = selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode);

                /* If there's no label to set, then exit without warning */
                if (r < 0 && errno == ENOENT)
                        return 0;

                if (r >= 0) {
                        r = lsetfilecon_raw(path, fcon);

                        /* If the FS doesn't support labels, then exit without warning */
                        if (r < 0 && errno == EOPNOTSUPP)
                                return 0;
                }
        }

        if (r < 0) {
                /* Ignore ENOENT in some cases */
                if (ignore_enoent && errno == ENOENT)
                        return 0;

                if (ignore_erofs && errno == EROFS)
                        return 0;

                log_enforcing("Unable to fix SELinux security context of %s: %m", path);
                if (security_getenforce() == 1)
                        return -errno;
        }
#endif

        return 0;
}

int mac_selinux_apply(const char *path, const char *label) {

#ifdef HAVE_SELINUX
        if (!mac_selinux_use())
                return 0;

        assert(path);
        assert(label);

        if (setfilecon(path, (security_context_t) label) < 0) {
                log_enforcing("Failed to set SELinux security context %s on path %s: %m", label, path);
                if (security_getenforce() > 0)
                        return -errno;
        }
#endif
        return 0;
}

int mac_selinux_get_create_label_from_exe(const char *exe, char **label) {
        int r = -EOPNOTSUPP;

#ifdef HAVE_SELINUX
        _cleanup_security_context_free_ security_context_t mycon = NULL, fcon = NULL;
        security_class_t sclass;

        assert(exe);
        assert(label);

        if (!mac_selinux_have())
                return -EOPNOTSUPP;

        r = getcon_raw(&mycon);
        if (r < 0)
                return -errno;

        r = getfilecon_raw(exe, &fcon);
        if (r < 0)
                return -errno;

        sclass = string_to_security_class("process");
        r = security_compute_create_raw(mycon, fcon, sclass, (security_context_t *) label);
        if (r < 0)
                return -errno;
#endif

        return r;
}

int mac_selinux_get_our_label(char **label) {
        int r = -EOPNOTSUPP;

        assert(label);

#ifdef HAVE_SELINUX
        if (!mac_selinux_have())
                return -EOPNOTSUPP;

        r = getcon_raw(label);
        if (r < 0)
                return -errno;
#endif

        return r;
}

int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **label) {
        int r = -EOPNOTSUPP;

#ifdef HAVE_SELINUX
        _cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL;
        _cleanup_context_free_ context_t pcon = NULL, bcon = NULL;
        security_class_t sclass;
        const char *range = NULL;

        assert(socket_fd >= 0);
        assert(exe);
        assert(label);

        if (!mac_selinux_have())
                return -EOPNOTSUPP;

        r = getcon_raw(&mycon);
        if (r < 0)
                return -errno;

        r = getpeercon_raw(socket_fd, &peercon);
        if (r < 0)
                return -errno;

        if (!exec_label) {
                /* If there is no context set for next exec let's use context
                   of target executable */
                r = getfilecon_raw(exe, &fcon);
                if (r < 0)
                        return -errno;
        }

        bcon = context_new(mycon);
        if (!bcon)
                return -ENOMEM;

        pcon = context_new(peercon);
        if (!pcon)
                return -ENOMEM;

        range = context_range_get(pcon);
        if (!range)
                return -errno;

        r = context_range_set(bcon, range);
        if (r)
                return -errno;

        freecon(mycon);
        mycon = strdup(context_str(bcon));
        if (!mycon)
                return -ENOMEM;

        sclass = string_to_security_class("process");
        r = security_compute_create_raw(mycon, fcon, sclass, (security_context_t *) label);
        if (r < 0)
                return -errno;
#endif

        return r;
}

char* mac_selinux_free(char *label) {

#ifdef HAVE_SELINUX
        if (!label)
                return NULL;

        if (!mac_selinux_have())
                return NULL;


        freecon((security_context_t) label);
#endif

        return NULL;
}

int mac_selinux_create_file_prepare(const char *path, mode_t mode) {

#ifdef HAVE_SELINUX
        _cleanup_security_context_free_ security_context_t filecon = NULL;
        int r;

        assert(path);

        if (!label_hnd)
                return 0;

        if (path_is_absolute(path))
                r = selabel_lookup_raw(label_hnd, &filecon, path, mode);
        else {
                _cleanup_free_ char *newpath = NULL;

                r = path_make_absolute_cwd(path, &newpath);
                if (r < 0)
                        return r;

                r = selabel_lookup_raw(label_hnd, &filecon, newpath, mode);
        }

        if (r < 0) {
                /* No context specified by the policy? Proceed without setting it. */
                if (errno == ENOENT)
                        return 0;

                log_enforcing("Failed to determine SELinux security context for %s: %m", path);
        } else {
                if (setfscreatecon_raw(filecon) >= 0)
                        return 0; /* Success! */

                log_enforcing("Failed to set SELinux security context %s for %s: %m", filecon, path);
        }

        if (security_getenforce() > 0)
                return -errno;

#endif
        return 0;
}

void mac_selinux_create_file_clear(void) {

#ifdef HAVE_SELINUX
        PROTECT_ERRNO;

        if (!mac_selinux_use())
                return;

        setfscreatecon_raw(NULL);
#endif
}

int mac_selinux_create_socket_prepare(const char *label) {

#ifdef HAVE_SELINUX
        if (!mac_selinux_use())
                return 0;

        assert(label);

        if (setsockcreatecon((security_context_t) label) < 0) {
                log_enforcing("Failed to set SELinux security context %s for sockets: %m", label);

                if (security_getenforce() == 1)
                        return -errno;
        }
#endif

        return 0;
}

void mac_selinux_create_socket_clear(void) {

#ifdef HAVE_SELINUX
        PROTECT_ERRNO;

        if (!mac_selinux_use())
                return;

        setsockcreatecon_raw(NULL);
#endif
}

int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) {

        /* Binds a socket and label its file system object according to the SELinux policy */

#ifdef HAVE_SELINUX
        _cleanup_security_context_free_ security_context_t fcon = NULL;
        const struct sockaddr_un *un;
        bool context_changed = false;
        char *path;
        int r;

        assert(fd >= 0);
        assert(addr);
        assert(addrlen >= sizeof(sa_family_t));

        if (!label_hnd)
                goto skipped;

        /* Filter out non-local sockets */
        if (addr->sa_family != AF_UNIX)
                goto skipped;

        /* Filter out anonymous sockets */
        if (addrlen < offsetof(struct sockaddr_un, sun_path) + 1)
                goto skipped;

        /* Filter out abstract namespace sockets */
        un = (const struct sockaddr_un*) addr;
        if (un->sun_path[0] == 0)
                goto skipped;

        path = strndupa(un->sun_path, addrlen - offsetof(struct sockaddr_un, sun_path));

        if (path_is_absolute(path))
                r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFSOCK);
        else {
                _cleanup_free_ char *newpath = NULL;

                r = path_make_absolute_cwd(path, &newpath);
                if (r < 0)
                        return r;

                r = selabel_lookup_raw(label_hnd, &fcon, newpath, S_IFSOCK);
        }

        if (r < 0) {
                /* No context specified by the policy? Proceed without setting it */
                if (errno == ENOENT)
                        goto skipped;

                log_enforcing("Failed to determine SELinux security context for %s: %m", path);
                if (security_getenforce() > 0)
                        return -errno;

        } else {
                if (setfscreatecon_raw(fcon) < 0) {
                        log_enforcing("Failed to set SELinux security context %s for %s: %m", fcon, path);
                        if (security_getenforce() > 0)
                                return -errno;
                } else
                        context_changed = true;
        }

        r = bind(fd, addr, addrlen) < 0 ? -errno : 0;

        if (context_changed)
                setfscreatecon_raw(NULL);

        return r;

skipped:
#endif
        if (bind(fd, addr, addrlen) < 0)
                return -errno;

        return 0;
}