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7029 want per-process exploit mitigation features (secflags)
7030 want basic address space layout randomization (aslr)
7031 noexec_user_stack should be a secflag
7032 want a means to forbid mappings around NULL.
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--- old/usr/src/uts/common/os/priv.c
+++ new/usr/src/uts/common/os/priv.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21 /*
22 22 * Copyright 2010 Sun Microsystems, Inc. All rights reserved.
23 23 * Use is subject to license terms.
24 24 */
25 25
26 26 /*
27 27 * Privilege implementation.
28 28 *
29 29 * This file provides the infrastructure for privilege sets and limits
30 30 * the number of files that requires to include <sys/cred_impl.h> and/or
31 31 * <sys/priv_impl.h>.
32 32 *
33 33 * The Solaris privilege mechanism has been designed in a
34 34 * future proof manner. While the kernel may use fixed size arrays
35 35 * and fixed bitmasks and bit values, the representation of those
36 36 * is kernel private. All external interfaces as well as K-to-K interfaces
37 37 * have been constructed in a manner to provide the maximum flexibility.
38 38 *
39 39 * There can be X privilege sets each containing Y 32 bit words.
40 40 * <X, Y> are constant for a kernel invocation.
41 41 *
42 42 * As a consequence, all privilege set manipulation happens in functions
43 43 * below.
44 44 *
45 45 */
46 46
47 47 #include <sys/systm.h>
48 48 #include <sys/ddi.h>
49 49 #include <sys/kmem.h>
50 50 #include <sys/sunddi.h>
51 51 #include <sys/errno.h>
52 52 #include <sys/debug.h>
53 53 #include <sys/priv_impl.h>
54 54 #include <sys/procfs.h>
55 55 #include <sys/policy.h>
56 56 #include <sys/cred_impl.h>
57 57 #include <sys/devpolicy.h>
58 58 #include <sys/atomic.h>
59 59
60 60 /*
61 61 * Privilege name to number mapping table consists in the generated
62 62 * priv_const.c file. This lock protects against updates of the privilege
63 63 * names and counts; all other priv_info fields are read-only.
64 64 * The actual protected values are:
65 65 * global variable nprivs
66 66 * the priv_max field
67 67 * the priv_names field
68 68 * the priv names info item (cnt/strings)
69 69 */
70 70 krwlock_t privinfo_lock;
71 71
72 72 static boolean_t priv_valid(const cred_t *);
73 73
74 74 priv_set_t priv_fullset; /* set of all privileges */
75 75 priv_set_t priv_unsafe; /* unsafe to exec set-uid root if these are not in L */
76 76
77 77 /*
78 78 * Privilege initialization functions.
79 79 * Called from common/os/cred.c when cred_init is called.
80 80 */
81 81
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82 82 void
83 83 priv_init(void)
84 84 {
85 85 #ifdef DEBUG
86 86 int alloc_test_priv = 1;
87 87 #else
88 88 int alloc_test_priv = priv_debug;
89 89 #endif
90 90 rw_init(&privinfo_lock, NULL, RW_DRIVER, NULL);
91 91
92 - PRIV_BASIC_ASSERT(priv_basic);
93 - PRIV_UNSAFE_ASSERT(&priv_unsafe);
92 + PRIV_BASIC_ADDSET(priv_basic);
93 + PRIV_UNSAFE_ADDSET(&priv_unsafe);
94 94 priv_fillset(&priv_fullset);
95 95
96 96 /*
97 97 * When booting with priv_debug set or in a DEBUG kernel, then we'll
98 98 * add an additional basic privilege and we verify that it is always
99 99 * present in E.
100 100 */
101 101 if (alloc_test_priv != 0 &&
102 102 (priv_basic_test = priv_getbyname("basic_test", PRIV_ALLOC)) >= 0) {
103 103 priv_addset(priv_basic, priv_basic_test);
104 104 }
105 105
106 106 devpolicy_init();
107 107 }
108 108
109 109 /* Utility functions: privilege sets as opaque data types */
110 110
111 111 /*
112 112 * Guts of prgetprivsize.
113 113 */
114 114 int
115 115 priv_prgetprivsize(prpriv_t *tmpl)
116 116 {
117 117 return (sizeof (prpriv_t) +
118 118 PRIV_SETBYTES - sizeof (priv_chunk_t) +
119 119 (tmpl ? tmpl->pr_infosize : priv_info->priv_infosize));
120 120 }
121 121
122 122 /*
123 123 * Guts of prgetpriv.
124 124 */
125 125 void
126 126 cred2prpriv(const cred_t *cp, prpriv_t *pr)
127 127 {
128 128 priv_set_t *psa;
129 129 int i;
130 130
131 131 pr->pr_nsets = PRIV_NSET;
132 132 pr->pr_setsize = PRIV_SETSIZE;
133 133 pr->pr_infosize = priv_info->priv_infosize;
134 134
135 135 psa = (priv_set_t *)pr->pr_sets;
136 136
137 137 for (i = 0; i < PRIV_NSET; i++)
138 138 psa[i] = *priv_getset(cp, i);
139 139
140 140 priv_getinfo(cp, (char *)pr + PRIV_PRPRIV_INFO_OFFSET(pr));
141 141 }
142 142
143 143 /*
144 144 * Guts of pr_spriv:
145 145 *
146 146 * Set the privileges of a process.
147 147 *
148 148 * In order to set the privileges, the setting process will need to
149 149 * have those privileges in its effective set in order to prevent
150 150 * specially privileged processes to easily gain additional privileges.
151 151 * Pre-existing privileges can be retained. To change any privileges,
152 152 * PRIV_PROC_OWNER needs to be asserted.
153 153 *
154 154 * In formula:
155 155 *
156 156 * S' <= S || S' <= S + Ea
157 157 *
158 158 * the new set must either be subset of the old set or a subset of
159 159 * the oldset merged with the effective set of the acting process; or just:
160 160 *
161 161 * S' <= S + Ea
162 162 *
163 163 * It's not legal to grow the limit set this way.
164 164 *
165 165 */
166 166 int
167 167 priv_pr_spriv(proc_t *p, prpriv_t *prpriv, const cred_t *cr)
168 168 {
169 169 cred_t *oldcred;
170 170 cred_t *newcred;
171 171 int i;
172 172 int err = EPERM;
173 173 cred_priv_t *cp, *ocp;
174 174 priv_set_t eset;
175 175
176 176 ASSERT(MUTEX_HELD(&p->p_lock));
177 177
178 178 /*
179 179 * Set must have proper dimension; infosize must be absent
180 180 * or properly sized.
181 181 */
182 182 if (prpriv->pr_nsets != PRIV_NSET ||
183 183 prpriv->pr_setsize != PRIV_SETSIZE ||
184 184 (prpriv->pr_infosize & (sizeof (uint32_t) - 1)) != 0 ||
185 185 prpriv->pr_infosize > priv_info->priv_infosize ||
186 186 prpriv->pr_infosize < 0)
187 187 return (EINVAL);
188 188
189 189 mutex_exit(&p->p_lock);
190 190
191 191 if (priv_proc_cred_perm(cr, p, &oldcred, VWRITE) != 0) {
192 192 mutex_enter(&p->p_lock);
193 193 return (EPERM);
194 194 }
195 195
196 196 newcred = crdup(oldcred);
197 197
198 198 /* Copy the privilege sets from prpriv to newcred */
199 199 bcopy(prpriv->pr_sets, CR_PRIVSETS(newcred), PRIV_SETBYTES);
200 200
201 201 cp = &newcred->cr_priv;
202 202 ocp = &oldcred->cr_priv;
203 203 eset = CR_OEPRIV(cr);
204 204
205 205 priv_intersect(&CR_LPRIV(oldcred), &eset);
206 206
207 207 /*
208 208 * Verify the constraints laid out:
209 209 * for the limit set, we require that the new set is a subset
210 210 * of the old limit set.
211 211 * for all other sets, we require that the new set is either a
212 212 * subset of the old set or a subset of the intersection of
213 213 * the old limit set and the effective set of the acting process.
214 214 */
215 215 for (i = 0; i < PRIV_NSET; i++)
216 216 if (!priv_issubset(&cp->crprivs[i], &ocp->crprivs[i]) &&
217 217 (i == PRIV_LIMIT || !priv_issubset(&cp->crprivs[i], &eset)))
218 218 break;
219 219
220 220 crfree(oldcred);
221 221
222 222 if (i < PRIV_NSET || !priv_valid(newcred))
223 223 goto err;
224 224
225 225 /* Load the settable privilege information */
226 226 if (prpriv->pr_infosize > 0) {
227 227 char *x = (char *)prpriv + PRIV_PRPRIV_INFO_OFFSET(prpriv);
228 228 char *lastx = x + prpriv->pr_infosize;
229 229
230 230 while (x < lastx) {
231 231 priv_info_t *pi = (priv_info_t *)x;
232 232 priv_info_uint_t *pii;
233 233
234 234 switch (pi->priv_info_type) {
235 235 case PRIV_INFO_FLAGS:
236 236 pii = (priv_info_uint_t *)x;
237 237 if (pii->info.priv_info_size != sizeof (*pii)) {
238 238 err = EINVAL;
239 239 goto err;
240 240 }
241 241 CR_FLAGS(newcred) &= ~PRIV_USER;
242 242 CR_FLAGS(newcred) |= (pii->val & PRIV_USER);
243 243 break;
244 244 default:
245 245 err = EINVAL;
246 246 goto err;
247 247 }
248 248 /* Guarantee alignment and forward progress */
249 249 if ((pi->priv_info_size & (sizeof (uint32_t) - 1)) ||
250 250 pi->priv_info_size < sizeof (*pi) ||
251 251 lastx - x > pi->priv_info_size) {
252 252 err = EINVAL;
253 253 goto err;
254 254 }
255 255
256 256 x += pi->priv_info_size;
257 257 }
258 258 }
259 259
260 260 /*
261 261 * We'll try to copy the privilege aware flag; but since the
262 262 * privileges sets are all individually set, they are set
263 263 * as if we're privilege aware. If PRIV_AWARE wasn't set
264 264 * or was explicitely unset, we need to set the flag and then
265 265 * try to get rid of it.
266 266 */
267 267 if ((CR_FLAGS(newcred) & PRIV_AWARE) == 0) {
268 268 CR_FLAGS(newcred) |= PRIV_AWARE;
269 269 priv_adjust_PA(newcred);
270 270 }
271 271
272 272 mutex_enter(&p->p_crlock);
273 273 oldcred = p->p_cred;
274 274 p->p_cred = newcred;
275 275 mutex_exit(&p->p_crlock);
276 276 crfree(oldcred);
277 277
278 278 mutex_enter(&p->p_lock);
279 279 return (0);
280 280
281 281 err:
282 282 crfree(newcred);
283 283 mutex_enter(&p->p_lock);
284 284 return (err);
285 285 }
286 286
287 287 priv_impl_info_t
288 288 *priv_hold_implinfo(void)
289 289 {
290 290 rw_enter(&privinfo_lock, RW_READER);
291 291 return (priv_info);
292 292 }
293 293
294 294 void
295 295 priv_release_implinfo(void)
296 296 {
297 297 rw_exit(&privinfo_lock);
298 298 }
299 299
300 300 size_t
301 301 priv_get_implinfo_size(void)
302 302 {
303 303 return (privinfosize);
304 304 }
305 305
306 306
307 307 /*
308 308 * Return the nth privilege set
309 309 */
310 310 const priv_set_t *
311 311 priv_getset(const cred_t *cr, int set)
312 312 {
313 313 ASSERT(PRIV_VALIDSET(set));
314 314
315 315 if ((CR_FLAGS(cr) & PRIV_AWARE) == 0)
316 316 switch (set) {
317 317 case PRIV_EFFECTIVE:
318 318 return (&CR_OEPRIV(cr));
319 319 case PRIV_PERMITTED:
320 320 return (&CR_OPPRIV(cr));
321 321 }
322 322 return (&CR_PRIVS(cr)->crprivs[set]);
323 323 }
324 324
325 325 /*
326 326 * Buf must be allocated by caller and contain sufficient space to
327 327 * contain all additional info structures using priv_info.priv_infosize.
328 328 * The buffer must be properly aligned.
329 329 */
330 330 /*ARGSUSED*/
331 331 void
332 332 priv_getinfo(const cred_t *cr, void *buf)
333 333 {
334 334 struct priv_info_uint *ii;
335 335
336 336 ii = buf;
337 337 ii->val = CR_FLAGS(cr);
338 338 ii->info.priv_info_size = (uint32_t)sizeof (*ii);
339 339 ii->info.priv_info_type = PRIV_INFO_FLAGS;
340 340 }
341 341
342 342 int
343 343 priv_getbyname(const char *name, uint_t flag)
344 344 {
345 345 int i;
346 346 int wheld = 0;
347 347 int len;
348 348 char *p;
349 349
350 350 if (flag != 0 && flag != PRIV_ALLOC)
351 351 return (-EINVAL);
352 352
353 353 if (strncasecmp(name, "priv_", 5) == 0)
354 354 name += 5;
355 355
356 356 rw_enter(&privinfo_lock, RW_READER);
357 357 rescan:
358 358 for (i = 0; i < nprivs; i++)
359 359 if (strcasecmp(priv_names[i], name) == 0) {
360 360 rw_exit(&privinfo_lock);
361 361 return (i);
362 362 }
363 363
364 364
365 365 if (!wheld) {
366 366 if (!(flag & PRIV_ALLOC)) {
367 367 rw_exit(&privinfo_lock);
368 368 return (-EINVAL);
369 369 }
370 370
371 371 /* check length, validity and available space */
372 372 len = strlen(name) + 1;
373 373
374 374 if (len > PRIVNAME_MAX) {
375 375 rw_exit(&privinfo_lock);
376 376 return (-ENAMETOOLONG);
377 377 }
378 378
379 379 for (p = (char *)name; *p != '\0'; p++) {
380 380 char c = *p;
381 381
382 382 if (!((c >= 'A' && c <= 'Z') ||
383 383 (c >= 'a' && c <= 'z') ||
384 384 (c >= '0' && c <= '9') ||
385 385 c == '_')) {
386 386 rw_exit(&privinfo_lock);
387 387 return (-EINVAL);
388 388 }
389 389 }
390 390
391 391 if (!rw_tryupgrade(&privinfo_lock)) {
392 392 rw_exit(&privinfo_lock);
393 393 rw_enter(&privinfo_lock, RW_WRITER);
394 394 wheld = 1;
395 395 /* Someone may have added our privilege */
396 396 goto rescan;
397 397 }
398 398 }
399 399
400 400 if (nprivs == MAX_PRIVILEGE || len + privbytes > maxprivbytes) {
401 401 rw_exit(&privinfo_lock);
402 402 return (-ENOMEM);
403 403 }
404 404
405 405 priv_names[i] = p = priv_str + privbytes;
406 406
407 407 bcopy(name, p, len);
408 408
409 409 /* make the priv_names[i] and privilege name globally visible */
410 410 membar_producer();
411 411
412 412 /* adjust priv count and bytes count */
413 413 priv_ninfo->cnt = priv_info->priv_max = ++nprivs;
414 414 privbytes += len;
415 415
416 416 rw_exit(&privinfo_lock);
417 417 return (i);
418 418 }
419 419
420 420 /*
421 421 * We can't afford locking the privileges here because of the locations
422 422 * we call this from; so we make sure that the privileges table
423 423 * is visible to us; it is made visible before the value of nprivs is
424 424 * updated.
425 425 */
426 426 const char *
427 427 priv_getbynum(int priv)
428 428 {
429 429 int maxpriv = nprivs;
430 430
431 431 membar_consumer();
432 432
433 433 if (priv >= 0 && priv < maxpriv)
434 434 return (priv_names[priv]);
435 435
436 436 return (NULL);
437 437 }
438 438
439 439 const char *
440 440 priv_getsetbynum(int setno)
441 441 {
442 442 if (!PRIV_VALIDSET(setno))
443 443 return (NULL);
444 444
445 445 return (priv_setnames[setno]);
446 446 }
447 447
448 448 /*
449 449 * Privilege sanity checking when setting: E <= P.
450 450 */
451 451 static boolean_t
452 452 priv_valid(const cred_t *cr)
453 453 {
454 454 return (priv_issubset(&CR_EPRIV(cr), &CR_PPRIV(cr)));
455 455 }
456 456
457 457 /*
458 458 * Privilege manipulation functions
459 459 *
460 460 * Without knowing the details of the privilege set implementation,
461 461 * opaque pointers can be used to manipulate sets at will.
462 462 */
463 463 void
464 464 priv_emptyset(priv_set_t *set)
465 465 {
466 466 bzero(set, sizeof (*set));
467 467 }
468 468
469 469 void
470 470 priv_fillset(priv_set_t *set)
471 471 {
472 472 int i;
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473 473
474 474 /* memset? */
475 475 for (i = 0; i < PRIV_SETSIZE; i++)
476 476 set->pbits[i] = ~(priv_chunk_t)0;
477 477 }
478 478
479 479 void
480 480 priv_addset(priv_set_t *set, int priv)
481 481 {
482 482 ASSERT(priv >= 0 && priv < MAX_PRIVILEGE);
483 - __PRIV_ASSERT(set, priv);
483 + __PRIV_ADDSET(set, priv);
484 484 }
485 485
486 486 void
487 487 priv_delset(priv_set_t *set, int priv)
488 488 {
489 489 ASSERT(priv >= 0 && priv < MAX_PRIVILEGE);
490 - __PRIV_CLEAR(set, priv);
490 + __PRIV_DELSET(set, priv);
491 491 }
492 492
493 493 boolean_t
494 494 priv_ismember(const priv_set_t *set, int priv)
495 495 {
496 496 ASSERT(priv >= 0 && priv < MAX_PRIVILEGE);
497 - return (__PRIV_ISASSERT(set, priv) ? B_TRUE : B_FALSE);
497 + return (__PRIV_ISMEMBER(set, priv) ? B_TRUE : B_FALSE);
498 498 }
499 499
500 500 #define PRIV_TEST_BODY(test) \
501 501 int i; \
502 502 \
503 503 for (i = 0; i < PRIV_SETSIZE; i++) \
504 504 if (!(test)) \
505 505 return (B_FALSE); \
506 506 \
507 507 return (B_TRUE)
508 508
509 509 boolean_t
510 510 priv_isequalset(const priv_set_t *a, const priv_set_t *b)
511 511 {
512 512 return ((boolean_t)(bcmp(a, b, sizeof (*a)) == 0));
513 513 }
514 514
515 515 boolean_t
516 516 priv_isemptyset(const priv_set_t *set)
517 517 {
518 518 PRIV_TEST_BODY(set->pbits[i] == 0);
519 519 }
520 520
521 521 boolean_t
522 522 priv_isfullset(const priv_set_t *set)
523 523 {
524 524 PRIV_TEST_BODY(set->pbits[i] == ~(priv_chunk_t)0);
525 525 }
526 526
527 527 /*
528 528 * Return true if a is a subset of b
529 529 */
530 530 boolean_t
531 531 priv_issubset(const priv_set_t *a, const priv_set_t *b)
532 532 {
533 533 PRIV_TEST_BODY((a->pbits[i] | b->pbits[i]) == b->pbits[i]);
534 534 }
535 535
536 536 #define PRIV_CHANGE_BODY(a, op, b) \
537 537 int i; \
538 538 \
539 539 for (i = 0; i < PRIV_SETSIZE; i++) \
540 540 a->pbits[i] op b->pbits[i]
541 541
542 542 /* B = A ^ B */
543 543 void
544 544 priv_intersect(const priv_set_t *a, priv_set_t *b)
545 545 {
546 546 /* CSTYLED */
547 547 PRIV_CHANGE_BODY(b, &=, a);
548 548 }
549 549
550 550 /* B = A v B */
551 551 void
552 552 priv_union(const priv_set_t *a, priv_set_t *b)
553 553 {
554 554 /* CSTYLED */
555 555 PRIV_CHANGE_BODY(b, |=, a);
556 556 }
557 557
558 558 /* A = ! A */
559 559 void
560 560 priv_inverse(priv_set_t *a)
561 561 {
562 562 PRIV_CHANGE_BODY(a, = ~, a);
563 563 }
564 564
565 565 /*
566 566 * Can the source cred act on the target credential?
567 567 *
568 568 * We will you allow to gain uids this way but not privileges.
569 569 */
570 570 int
571 571 priv_proc_cred_perm(const cred_t *scr, proc_t *tp, cred_t **pcr, int mode)
572 572 {
573 573 const priv_set_t *eset;
574 574 int idsmatch;
575 575 cred_t *tcr;
576 576 int res = 0;
577 577
578 578 /* prevent the cred from going away */
579 579 mutex_enter(&tp->p_crlock);
580 580 crhold(tcr = tp->p_cred);
581 581 mutex_exit(&tp->p_crlock);
582 582
583 583 if (scr == tcr && !(tp->p_flag & SNOCD))
584 584 goto out;
585 585
586 586 idsmatch = (scr->cr_uid == tcr->cr_uid &&
587 587 scr->cr_uid == tcr->cr_ruid &&
588 588 scr->cr_uid == tcr->cr_suid &&
589 589 scr->cr_gid == tcr->cr_gid &&
590 590 scr->cr_gid == tcr->cr_rgid &&
591 591 scr->cr_gid == tcr->cr_sgid &&
592 592 !(tp->p_flag & SNOCD));
593 593
594 594 /*
595 595 * Source credential must have the proc_zone privilege if referencing
596 596 * a process in another zone.
597 597 */
598 598 if (scr->cr_zone != tcr->cr_zone && secpolicy_proc_zone(scr) != 0) {
599 599 res = EACCES;
600 600 goto out;
601 601 }
602 602
603 603 if (!(mode & VWRITE)) {
604 604 if (!idsmatch && secpolicy_proc_owner(scr, tcr, 0) != 0)
605 605 res = EACCES;
606 606 goto out;
607 607 }
608 608
609 609 /*
610 610 * For writing, the effective set of scr must dominate all sets of tcr,
611 611 * We test Pt <= Es (Et <= Pt so no need to test) and It <= Es
612 612 * The Limit set of scr must be a superset of the limitset of
613 613 * tcr.
614 614 */
615 615 eset = &CR_OEPRIV(scr);
616 616
617 617 if (!priv_issubset(&CR_IPRIV(tcr), eset) ||
618 618 !priv_issubset(&CR_OPPRIV(tcr), eset) ||
619 619 !priv_issubset(&CR_LPRIV(tcr), &CR_LPRIV(scr)) ||
620 620 !idsmatch && secpolicy_proc_owner(scr, tcr, mode) != 0)
621 621 res = EACCES;
622 622
623 623 out:
624 624 if (res == 0 && pcr != NULL)
625 625 *pcr = tcr;
626 626 else
627 627 crfree(tcr);
628 628 return (res);
629 629 }
630 630
631 631 /*
632 632 * Set the privilege aware bit, adding L to E/P if necessary.
633 633 * Each time we set it, we also clear PRIV_AWARE_RESET.
634 634 */
635 635 void
636 636 priv_set_PA(cred_t *cr)
637 637 {
638 638 ASSERT(cr->cr_ref <= 2);
639 639
640 640 if ((CR_FLAGS(cr) & (PRIV_AWARE|PRIV_AWARE_RESET)) == PRIV_AWARE)
641 641 return;
642 642
643 643 CR_FLAGS(cr) |= PRIV_AWARE;
644 644 CR_FLAGS(cr) &= ~PRIV_AWARE_RESET;
645 645
646 646 if (cr->cr_uid == 0)
647 647 priv_union(&CR_LPRIV(cr), &CR_EPRIV(cr));
648 648
649 649 if (cr->cr_uid == 0 || cr->cr_suid == 0 || cr->cr_ruid == 0)
650 650 priv_union(&CR_LPRIV(cr), &CR_PPRIV(cr));
651 651 }
652 652
653 653 boolean_t
654 654 priv_can_clear_PA(const cred_t *cr)
655 655 {
656 656 /*
657 657 * We can clear PA in the following cases:
658 658 *
659 659 * None of the uids are 0.
660 660 * Any uid == 0 and P == L and (Euid != 0 or E == L)
661 661 */
662 662 return ((cr->cr_suid != 0 && cr->cr_ruid != 0 && cr->cr_uid != 0) ||
663 663 priv_isequalset(&CR_PPRIV(cr), &CR_LPRIV(cr)) &&
664 664 (cr->cr_uid != 0 || priv_isequalset(&CR_EPRIV(cr), &CR_LPRIV(cr))));
665 665 }
666 666
667 667 /*
668 668 * Clear privilege aware bit if it is an idempotent operation and by
669 669 * clearing it the process cannot get to uid 0 and all privileges.
670 670 *
671 671 * This function should be called with caution as it may cause "E" to be
672 672 * lost once a processes assumes euid 0 again.
673 673 */
674 674 void
675 675 priv_adjust_PA(cred_t *cr)
676 676 {
677 677 ASSERT(cr->cr_ref <= 2);
678 678
679 679 if (!(CR_FLAGS(cr) & PRIV_AWARE) ||
680 680 !priv_can_clear_PA(cr)) {
681 681 CR_FLAGS(cr) &= ~PRIV_AWARE_RESET;
682 682 return;
683 683 }
684 684
685 685 if (CR_FLAGS(cr) & PRIV_AWARE_INHERIT)
686 686 return;
687 687
688 688 /*
689 689 * We now need to adjust P/E in those cases when uids
690 690 * are zero; the rules are P' = I & L, E' = I & L;
691 691 * but since P = L and E = L, we can use P &= I, E &= I,
692 692 * depending on which uids are 0.
693 693 */
694 694 if (cr->cr_suid == 0 || cr->cr_ruid == 0 || cr->cr_uid == 0) {
695 695 if (cr->cr_uid == 0)
696 696 priv_intersect(&CR_IPRIV(cr), &CR_EPRIV(cr));
697 697 priv_intersect(&CR_IPRIV(cr), &CR_PPRIV(cr));
698 698 }
699 699
700 700 CR_FLAGS(cr) &= ~(PRIV_AWARE|PRIV_AWARE_RESET);
701 701 }
702 702
703 703 /*
704 704 * Reset privilege aware bit if so requested by setting the PRIV_AWARE_RESET
705 705 * flag.
706 706 */
707 707 void
708 708 priv_reset_PA(cred_t *cr, boolean_t finalize)
709 709 {
710 710 ASSERT(cr->cr_ref <= 2);
711 711
712 712 if ((CR_FLAGS(cr) & (PRIV_AWARE|PRIV_AWARE_RESET)) !=
713 713 (PRIV_AWARE|PRIV_AWARE_RESET)) {
714 714 CR_FLAGS(cr) &= ~PRIV_AWARE_RESET;
715 715 return;
716 716 }
717 717
718 718 /*
719 719 * When PRIV_AWARE_RESET is enabled, any change of uids causes
720 720 * a change to the P and E sets. Bracketing with
721 721 * seteuid(0) ... seteuid(uid)/setreuid(-1, 0) .. setreuid(-1, uid)
722 722 * will cause the privilege sets "do the right thing.".
723 723 * When the change of the uid is "final", e.g., by using setuid(uid),
724 724 * or setreuid(uid, uid) or when the last set*uid() call causes all
725 725 * uids to be the same, we set P and E to I & L, like when you exec.
726 726 * We make an exception when all the uids are 0; this is required
727 727 * when we login as root as in that particular case we cannot
728 728 * make a distinction between seteuid(0) and seteuid(uid).
729 729 * We rely on seteuid/setreuid/setuid to tell us with the
730 730 * "finalize" argument that we no longer expect new uid changes,
731 731 * cf. setreuid(uid, uid) and setuid(uid).
732 732 */
733 733 if (cr->cr_suid == cr->cr_ruid && cr->cr_suid == cr->cr_uid) {
734 734 if (finalize || cr->cr_uid != 0) {
735 735 CR_EPRIV(cr) = CR_IPRIV(cr);
736 736 priv_intersect(&CR_LPRIV(cr), &CR_EPRIV(cr));
737 737 CR_PPRIV(cr) = CR_EPRIV(cr);
738 738 CR_FLAGS(cr) &= ~(PRIV_AWARE|PRIV_AWARE_RESET);
739 739 } else {
740 740 CR_EPRIV(cr) = CR_PPRIV(cr);
741 741 }
742 742 } else if (cr->cr_uid != 0 && (cr->cr_ruid == 0 || cr->cr_suid == 0)) {
743 743 CR_EPRIV(cr) = CR_IPRIV(cr);
744 744 priv_intersect(&CR_LPRIV(cr), &CR_EPRIV(cr));
745 745 }
746 746 }
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