1 /*- 2 * Copyright (c) 1999-2002 Robert N. M. Watson 3 * Copyright (c) 2001 Ilmar S. Habibulin 4 * Copyright (c) 2001-2003 Networks Associates Technology, Inc. 5 * Copyright (c) 2005 Samy Al Bahra 6 * All rights reserved. 7 * 8 * This software was developed by Robert Watson and Ilmar Habibulin for the 9 * TrustedBSD Project. 10 * 11 * This software was developed for the FreeBSD Project in part by Network 12 * Associates Laboratories, the Security Research Division of Network 13 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 14 * as part of the DARPA CHATS research program. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 */ 37 38 #include <sys/cdefs.h> 39 __FBSDID("$FreeBSD$"); 40 41 #include "opt_mac.h" 42 43 #include <sys/param.h> 44 #include <sys/condvar.h> 45 #include <sys/imgact.h> 46 #include <sys/kernel.h> 47 #include <sys/lock.h> 48 #include <sys/malloc.h> 49 #include <sys/mutex.h> 50 #include <sys/mac.h> 51 #include <sys/proc.h> 52 #include <sys/sbuf.h> 53 #include <sys/systm.h> 54 #include <sys/vnode.h> 55 #include <sys/mount.h> 56 #include <sys/file.h> 57 #include <sys/namei.h> 58 #include <sys/sysctl.h> 59 60 #include <vm/vm.h> 61 #include <vm/pmap.h> 62 #include <vm/vm_map.h> 63 #include <vm/vm_object.h> 64 65 #include <sys/mac_policy.h> 66 67 #include <security/mac/mac_internal.h> 68 69 int mac_enforce_process = 1; 70 SYSCTL_INT(_security_mac, OID_AUTO, enforce_process, CTLFLAG_RW, 71 &mac_enforce_process, 0, "Enforce MAC policy on inter-process operations"); 72 TUNABLE_INT("security.mac.enforce_process", &mac_enforce_process); 73 74 int mac_enforce_vm = 1; 75 SYSCTL_INT(_security_mac, OID_AUTO, enforce_vm, CTLFLAG_RW, 76 &mac_enforce_vm, 0, "Enforce MAC policy on vm operations"); 77 TUNABLE_INT("security.mac.enforce_vm", &mac_enforce_vm); 78 79 static int mac_mmap_revocation = 1; 80 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 81 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 82 "relabel"); 83 84 static int mac_mmap_revocation_via_cow = 0; 85 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW, 86 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via " 87 "copy-on-write semantics, or by removing all write access"); 88 89 static int mac_enforce_suid = 1; 90 SYSCTL_INT(_security_mac, OID_AUTO, enforce_suid, CTLFLAG_RW, 91 &mac_enforce_suid, 0, "Enforce MAC policy on suid/sgid operations"); 92 TUNABLE_INT("security.mac.enforce_suid", &mac_enforce_suid); 93 94 #ifdef MAC_DEBUG 95 static unsigned int nmaccreds, nmacprocs; 96 SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, creds, CTLFLAG_RD, 97 &nmaccreds, 0, "number of ucreds in use"); 98 SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, procs, CTLFLAG_RD, 99 &nmacprocs, 0, "number of procs in use"); 100 #endif 101 102 static void mac_cred_mmapped_drop_perms_recurse(struct thread *td, 103 struct ucred *cred, struct vm_map *map); 104 105 struct label * 106 mac_cred_label_alloc(void) 107 { 108 struct label *label; 109 110 label = mac_labelzone_alloc(M_WAITOK); 111 MAC_PERFORM(init_cred_label, label); 112 MAC_DEBUG_COUNTER_INC(&nmaccreds); 113 return (label); 114 } 115 116 void 117 mac_init_cred(struct ucred *cred) 118 { 119 120 cred->cr_label = mac_cred_label_alloc(); 121 } 122 123 static struct label * 124 mac_proc_label_alloc(void) 125 { 126 struct label *label; 127 128 label = mac_labelzone_alloc(M_WAITOK); 129 MAC_PERFORM(init_proc_label, label); 130 MAC_DEBUG_COUNTER_INC(&nmacprocs); 131 return (label); 132 } 133 134 void 135 mac_init_proc(struct proc *p) 136 { 137 138 p->p_label = mac_proc_label_alloc(); 139 } 140 141 void 142 mac_cred_label_free(struct label *label) 143 { 144 145 MAC_PERFORM(destroy_cred_label, label); 146 mac_labelzone_free(label); 147 MAC_DEBUG_COUNTER_DEC(&nmaccreds); 148 } 149 150 void 151 mac_destroy_cred(struct ucred *cred) 152 { 153 154 mac_cred_label_free(cred->cr_label); 155 cred->cr_label = NULL; 156 } 157 158 static void 159 mac_proc_label_free(struct label *label) 160 { 161 162 MAC_PERFORM(destroy_proc_label, label); 163 mac_labelzone_free(label); 164 MAC_DEBUG_COUNTER_DEC(&nmacprocs); 165 } 166 167 void 168 mac_destroy_proc(struct proc *p) 169 { 170 171 mac_proc_label_free(p->p_label); 172 p->p_label = NULL; 173 } 174 175 int 176 mac_externalize_cred_label(struct label *label, char *elements, 177 char *outbuf, size_t outbuflen) 178 { 179 int error; 180 181 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen); 182 183 return (error); 184 } 185 186 int 187 mac_internalize_cred_label(struct label *label, char *string) 188 { 189 int error; 190 191 MAC_INTERNALIZE(cred, label, string); 192 193 return (error); 194 } 195 196 /* 197 * Initialize MAC label for the first kernel process, from which other 198 * kernel processes and threads are spawned. 199 */ 200 void 201 mac_create_proc0(struct ucred *cred) 202 { 203 204 MAC_PERFORM(create_proc0, cred); 205 } 206 207 /* 208 * Initialize MAC label for the first userland process, from which other 209 * userland processes and threads are spawned. 210 */ 211 void 212 mac_create_proc1(struct ucred *cred) 213 { 214 215 MAC_PERFORM(create_proc1, cred); 216 } 217 218 void 219 mac_thread_userret(struct thread *td) 220 { 221 222 MAC_PERFORM(thread_userret, td); 223 } 224 225 /* 226 * When a new process is created, its label must be initialized. Generally, 227 * this involves inheritence from the parent process, modulo possible 228 * deltas. This function allows that processing to take place. 229 */ 230 void 231 mac_copy_cred(struct ucred *src, struct ucred *dest) 232 { 233 234 MAC_PERFORM(copy_cred_label, src->cr_label, dest->cr_label); 235 } 236 237 int 238 mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 239 { 240 struct label *label; 241 struct mac mac; 242 char *buffer; 243 int error; 244 245 if (mac_p == NULL) 246 return (0); 247 248 error = copyin(mac_p, &mac, sizeof(mac)); 249 if (error) 250 return (error); 251 252 error = mac_check_structmac_consistent(&mac); 253 if (error) 254 return (error); 255 256 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 257 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 258 if (error) { 259 free(buffer, M_MACTEMP); 260 return (error); 261 } 262 263 label = mac_cred_label_alloc(); 264 error = mac_internalize_cred_label(label, buffer); 265 free(buffer, M_MACTEMP); 266 if (error) { 267 mac_cred_label_free(label); 268 return (error); 269 } 270 imgp->execlabel = label; 271 return (0); 272 } 273 274 void 275 mac_execve_exit(struct image_params *imgp) 276 { 277 if (imgp->execlabel != NULL) { 278 mac_cred_label_free(imgp->execlabel); 279 imgp->execlabel = NULL; 280 } 281 } 282 283 /* 284 * When relabeling a process, call out to the policies for the maximum 285 * permission allowed for each object type we know about in its 286 * memory space, and revoke access (in the least surprising ways we 287 * know) when necessary. The process lock is not held here. 288 */ 289 void 290 mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred) 291 { 292 293 /* XXX freeze all other threads */ 294 mac_cred_mmapped_drop_perms_recurse(td, cred, 295 &td->td_proc->p_vmspace->vm_map); 296 /* XXX allow other threads to continue */ 297 } 298 299 static __inline const char * 300 prot2str(vm_prot_t prot) 301 { 302 303 switch (prot & VM_PROT_ALL) { 304 case VM_PROT_READ: 305 return ("r--"); 306 case VM_PROT_READ | VM_PROT_WRITE: 307 return ("rw-"); 308 case VM_PROT_READ | VM_PROT_EXECUTE: 309 return ("r-x"); 310 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 311 return ("rwx"); 312 case VM_PROT_WRITE: 313 return ("-w-"); 314 case VM_PROT_EXECUTE: 315 return ("--x"); 316 case VM_PROT_WRITE | VM_PROT_EXECUTE: 317 return ("-wx"); 318 default: 319 return ("---"); 320 } 321 } 322 323 static void 324 mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred, 325 struct vm_map *map) 326 { 327 struct vm_map_entry *vme; 328 int result; 329 vm_prot_t revokeperms; 330 vm_object_t object; 331 vm_ooffset_t offset; 332 struct vnode *vp; 333 334 if (!mac_mmap_revocation) 335 return; 336 337 vm_map_lock_read(map); 338 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 339 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 340 mac_cred_mmapped_drop_perms_recurse(td, cred, 341 vme->object.sub_map); 342 continue; 343 } 344 /* 345 * Skip over entries that obviously are not shared. 346 */ 347 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 348 !vme->max_protection) 349 continue; 350 /* 351 * Drill down to the deepest backing object. 352 */ 353 offset = vme->offset; 354 object = vme->object.vm_object; 355 if (object == NULL) 356 continue; 357 while (object->backing_object != NULL) { 358 object = object->backing_object; 359 offset += object->backing_object_offset; 360 } 361 /* 362 * At the moment, vm_maps and objects aren't considered 363 * by the MAC system, so only things with backing by a 364 * normal object (read: vnodes) are checked. 365 */ 366 if (object->type != OBJT_VNODE) 367 continue; 368 vp = (struct vnode *)object->handle; 369 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 370 result = vme->max_protection; 371 mac_check_vnode_mmap_downgrade(cred, vp, &result); 372 VOP_UNLOCK(vp, 0, td); 373 /* 374 * Find out what maximum protection we may be allowing 375 * now but a policy needs to get removed. 376 */ 377 revokeperms = vme->max_protection & ~result; 378 if (!revokeperms) 379 continue; 380 printf("pid %ld: revoking %s perms from %#lx:%ld " 381 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 382 prot2str(revokeperms), (u_long)vme->start, 383 (long)(vme->end - vme->start), 384 prot2str(vme->max_protection), prot2str(vme->protection)); 385 vm_map_lock_upgrade(map); 386 /* 387 * This is the really simple case: if a map has more 388 * max_protection than is allowed, but it's not being 389 * actually used (that is, the current protection is 390 * still allowed), we can just wipe it out and do 391 * nothing more. 392 */ 393 if ((vme->protection & revokeperms) == 0) { 394 vme->max_protection -= revokeperms; 395 } else { 396 if (revokeperms & VM_PROT_WRITE) { 397 /* 398 * In the more complicated case, flush out all 399 * pending changes to the object then turn it 400 * copy-on-write. 401 */ 402 vm_object_reference(object); 403 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 404 VM_OBJECT_LOCK(object); 405 vm_object_page_clean(object, 406 OFF_TO_IDX(offset), 407 OFF_TO_IDX(offset + vme->end - vme->start + 408 PAGE_MASK), 409 OBJPC_SYNC); 410 VM_OBJECT_UNLOCK(object); 411 VOP_UNLOCK(vp, 0, td); 412 vm_object_deallocate(object); 413 /* 414 * Why bother if there's no read permissions 415 * anymore? For the rest, we need to leave 416 * the write permissions on for COW, or 417 * remove them entirely if configured to. 418 */ 419 if (!mac_mmap_revocation_via_cow) { 420 vme->max_protection &= ~VM_PROT_WRITE; 421 vme->protection &= ~VM_PROT_WRITE; 422 } if ((revokeperms & VM_PROT_READ) == 0) 423 vme->eflags |= MAP_ENTRY_COW | 424 MAP_ENTRY_NEEDS_COPY; 425 } 426 if (revokeperms & VM_PROT_EXECUTE) { 427 vme->max_protection &= ~VM_PROT_EXECUTE; 428 vme->protection &= ~VM_PROT_EXECUTE; 429 } 430 if (revokeperms & VM_PROT_READ) { 431 vme->max_protection = 0; 432 vme->protection = 0; 433 } 434 pmap_protect(map->pmap, vme->start, vme->end, 435 vme->protection & ~revokeperms); 436 vm_map_simplify_entry(map, vme); 437 } 438 vm_map_lock_downgrade(map); 439 } 440 vm_map_unlock_read(map); 441 } 442 443 /* 444 * When the subject's label changes, it may require revocation of privilege 445 * to mapped objects. This can't be done on-the-fly later with a unified 446 * buffer cache. 447 */ 448 void 449 mac_relabel_cred(struct ucred *cred, struct label *newlabel) 450 { 451 452 MAC_PERFORM(relabel_cred, cred, newlabel); 453 } 454 455 int 456 mac_check_cred_relabel(struct ucred *cred, struct label *newlabel) 457 { 458 int error; 459 460 MAC_CHECK(check_cred_relabel, cred, newlabel); 461 462 return (error); 463 } 464 465 int 466 mac_check_cred_visible(struct ucred *u1, struct ucred *u2) 467 { 468 int error; 469 470 if (!mac_enforce_process) 471 return (0); 472 473 MAC_CHECK(check_cred_visible, u1, u2); 474 475 return (error); 476 } 477 478 int 479 mac_check_proc_debug(struct ucred *cred, struct proc *proc) 480 { 481 int error; 482 483 PROC_LOCK_ASSERT(proc, MA_OWNED); 484 485 if (!mac_enforce_process) 486 return (0); 487 488 MAC_CHECK(check_proc_debug, cred, proc); 489 490 return (error); 491 } 492 493 int 494 mac_check_proc_sched(struct ucred *cred, struct proc *proc) 495 { 496 int error; 497 498 PROC_LOCK_ASSERT(proc, MA_OWNED); 499 500 if (!mac_enforce_process) 501 return (0); 502 503 MAC_CHECK(check_proc_sched, cred, proc); 504 505 return (error); 506 } 507 508 int 509 mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum) 510 { 511 int error; 512 513 PROC_LOCK_ASSERT(proc, MA_OWNED); 514 515 if (!mac_enforce_process) 516 return (0); 517 518 MAC_CHECK(check_proc_signal, cred, proc, signum); 519 520 return (error); 521 } 522 523 int 524 mac_check_proc_setuid(struct proc *proc, struct ucred *cred, uid_t uid) 525 { 526 int error; 527 528 PROC_LOCK_ASSERT(proc, MA_OWNED); 529 530 if (!mac_enforce_suid) 531 return (0); 532 533 MAC_CHECK(check_proc_setuid, cred, uid); 534 return (error); 535 } 536 537 int 538 mac_check_proc_seteuid(struct proc *proc, struct ucred *cred, uid_t euid) 539 { 540 int error; 541 542 PROC_LOCK_ASSERT(proc, MA_OWNED); 543 544 if (!mac_enforce_suid) 545 return (0); 546 547 MAC_CHECK(check_proc_seteuid, cred, euid); 548 return (error); 549 } 550 551 int 552 mac_check_proc_setgid(struct proc *proc, struct ucred *cred, gid_t gid) 553 { 554 int error; 555 556 PROC_LOCK_ASSERT(proc, MA_OWNED); 557 558 if (!mac_enforce_suid) 559 return (0); 560 561 MAC_CHECK(check_proc_setgid, cred, gid); 562 return (error); 563 } 564 565 int 566 mac_check_proc_setegid(struct proc *proc, struct ucred *cred, gid_t egid) 567 { 568 int error; 569 570 PROC_LOCK_ASSERT(proc, MA_OWNED); 571 572 if (!mac_enforce_suid) 573 return (0); 574 575 MAC_CHECK(check_proc_setegid, cred, egid); 576 return (error); 577 } 578 579 int 580 mac_check_proc_setgroups(struct proc *proc, struct ucred *cred, 581 int ngroups, gid_t *gidset) 582 { 583 int error; 584 585 PROC_LOCK_ASSERT(proc, MA_OWNED); 586 587 if (!mac_enforce_suid) 588 return (0); 589 590 MAC_CHECK(check_proc_setgroups, cred, ngroups, gidset); 591 return (error); 592 } 593 594 int 595 mac_check_proc_setreuid(struct proc *proc, struct ucred *cred, uid_t ruid, 596 uid_t euid) 597 { 598 int error; 599 600 PROC_LOCK_ASSERT(proc, MA_OWNED); 601 602 if (!mac_enforce_suid) 603 return (0); 604 605 MAC_CHECK(check_proc_setreuid, cred, ruid, euid); 606 return (error); 607 } 608 609 int 610 mac_check_proc_setregid(struct proc *proc, struct ucred *cred, gid_t rgid, 611 gid_t egid) 612 { 613 int error; 614 615 PROC_LOCK_ASSERT(proc, MA_OWNED); 616 617 if (!mac_enforce_suid) 618 return (0); 619 620 MAC_CHECK(check_proc_setregid, cred, rgid, egid); 621 return (error); 622 } 623 624 int 625 mac_check_proc_setresuid(struct proc *proc, struct ucred *cred, uid_t ruid, 626 uid_t euid, uid_t suid) 627 { 628 int error; 629 630 PROC_LOCK_ASSERT(proc, MA_OWNED); 631 632 if (!mac_enforce_suid) 633 return (0); 634 635 MAC_CHECK(check_proc_setresuid, cred, ruid, euid, suid); 636 return (error); 637 } 638 639 int 640 mac_check_proc_setresgid(struct proc *proc, struct ucred *cred, gid_t rgid, 641 gid_t egid, gid_t sgid) 642 { 643 int error; 644 645 PROC_LOCK_ASSERT(proc, MA_OWNED); 646 647 if (!mac_enforce_suid) 648 return (0); 649 650 MAC_CHECK(check_proc_setresgid, cred, rgid, egid, sgid); 651 return (error); 652 } 653 654 int 655 mac_check_proc_wait(struct ucred *cred, struct proc *proc) 656 { 657 int error; 658 659 PROC_LOCK_ASSERT(proc, MA_OWNED); 660 661 if (!mac_enforce_process) 662 return (0); 663 664 MAC_CHECK(check_proc_wait, cred, proc); 665 666 return (error); 667 } 668