mac_process.c revision 184407
1/*- 2 * Copyright (c) 1999-2002, 2008 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 * Copyright (c) 2006 SPARTA, Inc. 7 * Copyright (c) 2008 Apple Inc. 8 * All rights reserved. 9 * 10 * This software was developed by Robert Watson and Ilmar Habibulin for the 11 * TrustedBSD Project. 12 * 13 * This software was developed for the FreeBSD Project in part by Network 14 * Associates Laboratories, the Security Research Division of Network 15 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 16 * as part of the DARPA CHATS research program. 17 * 18 * This software was enhanced by SPARTA ISSO under SPAWAR contract 19 * N66001-04-C-6019 ("SEFOS"). 20 * 21 * Redistribution and use in source and binary forms, with or without 22 * modification, are permitted provided that the following conditions 23 * are met: 24 * 1. Redistributions of source code must retain the above copyright 25 * notice, this list of conditions and the following disclaimer. 26 * 2. Redistributions in binary form must reproduce the above copyright 27 * notice, this list of conditions and the following disclaimer in the 28 * documentation and/or other materials provided with the distribution. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 33 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 40 * SUCH DAMAGE. 41 */ 42 43#include <sys/cdefs.h> 44__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 184407 2008-10-28 11:33:06Z rwatson $"); 45 46#include "opt_mac.h" 47 48#include <sys/param.h> 49#include <sys/condvar.h> 50#include <sys/imgact.h> 51#include <sys/kernel.h> 52#include <sys/lock.h> 53#include <sys/malloc.h> 54#include <sys/mutex.h> 55#include <sys/mac.h> 56#include <sys/proc.h> 57#include <sys/sbuf.h> 58#include <sys/systm.h> 59#include <sys/vnode.h> 60#include <sys/mount.h> 61#include <sys/file.h> 62#include <sys/namei.h> 63#include <sys/sysctl.h> 64 65#include <vm/vm.h> 66#include <vm/pmap.h> 67#include <vm/vm_map.h> 68#include <vm/vm_object.h> 69 70#include <security/mac/mac_framework.h> 71#include <security/mac/mac_internal.h> 72#include <security/mac/mac_policy.h> 73 74static int mac_mmap_revocation = 1; 75SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 76 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 77 "relabel"); 78 79static int mac_mmap_revocation_via_cow = 0; 80SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW, 81 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via " 82 "copy-on-write semantics, or by removing all write access"); 83 84static void mac_cred_mmapped_drop_perms_recurse(struct thread *td, 85 struct ucred *cred, struct vm_map *map); 86 87struct label * 88mac_cred_label_alloc(void) 89{ 90 struct label *label; 91 92 label = mac_labelzone_alloc(M_WAITOK); 93 MAC_PERFORM(cred_init_label, label); 94 return (label); 95} 96 97void 98mac_cred_init(struct ucred *cred) 99{ 100 101 if (mac_labeled & MPC_OBJECT_CRED) 102 cred->cr_label = mac_cred_label_alloc(); 103 else 104 cred->cr_label = NULL; 105} 106 107static struct label * 108mac_proc_label_alloc(void) 109{ 110 struct label *label; 111 112 label = mac_labelzone_alloc(M_WAITOK); 113 MAC_PERFORM(proc_init_label, label); 114 return (label); 115} 116 117void 118mac_proc_init(struct proc *p) 119{ 120 121 if (mac_labeled & MPC_OBJECT_PROC) 122 p->p_label = mac_proc_label_alloc(); 123 else 124 p->p_label = NULL; 125} 126 127void 128mac_cred_label_free(struct label *label) 129{ 130 131 MAC_PERFORM(cred_destroy_label, label); 132 mac_labelzone_free(label); 133} 134 135void 136mac_cred_destroy(struct ucred *cred) 137{ 138 139 if (cred->cr_label != NULL) { 140 mac_cred_label_free(cred->cr_label); 141 cred->cr_label = NULL; 142 } 143} 144 145static void 146mac_proc_label_free(struct label *label) 147{ 148 149 MAC_PERFORM(proc_destroy_label, label); 150 mac_labelzone_free(label); 151} 152 153void 154mac_proc_destroy(struct proc *p) 155{ 156 157 if (p->p_label != NULL) { 158 mac_proc_label_free(p->p_label); 159 p->p_label = NULL; 160 } 161} 162 163/* 164 * When a thread becomes an NFS server daemon, its credential may need to be 165 * updated to reflect this so that policies can recognize when file system 166 * operations originate from the network. 167 * 168 * At some point, it would be desirable if the credential used for each NFS 169 * RPC could be set based on the RPC context (i.e., source system, etc) to 170 * provide more fine-grained access control. 171 */ 172void 173mac_cred_associate_nfsd(struct ucred *cred) 174{ 175 176 MAC_PERFORM(cred_associate_nfsd, cred); 177} 178 179/* 180 * Initialize MAC label for the first kernel process, from which other kernel 181 * processes and threads are spawned. 182 */ 183void 184mac_cred_create_swapper(struct ucred *cred) 185{ 186 187 MAC_PERFORM(cred_create_swapper, cred); 188} 189 190/* 191 * Initialize MAC label for the first userland process, from which other 192 * userland processes and threads are spawned. 193 */ 194void 195mac_cred_create_init(struct ucred *cred) 196{ 197 198 MAC_PERFORM(cred_create_init, cred); 199} 200 201int 202mac_cred_externalize_label(struct label *label, char *elements, 203 char *outbuf, size_t outbuflen) 204{ 205 int error; 206 207 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen); 208 209 return (error); 210} 211 212int 213mac_cred_internalize_label(struct label *label, char *string) 214{ 215 int error; 216 217 MAC_INTERNALIZE(cred, label, string); 218 219 return (error); 220} 221 222void 223mac_thread_userret(struct thread *td) 224{ 225 226 MAC_PERFORM(thread_userret, td); 227} 228 229/* 230 * When a new process is created, its label must be initialized. Generally, 231 * this involves inheritence from the parent process, modulo possible deltas. 232 * This function allows that processing to take place. 233 */ 234void 235mac_cred_copy(struct ucred *src, struct ucred *dest) 236{ 237 238 MAC_PERFORM(cred_copy_label, src->cr_label, dest->cr_label); 239} 240 241int 242mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 243{ 244 struct label *label; 245 struct mac mac; 246 char *buffer; 247 int error; 248 249 if (mac_p == NULL) 250 return (0); 251 252 if (!(mac_labeled & MPC_OBJECT_CRED)) 253 return (EINVAL); 254 255 error = copyin(mac_p, &mac, sizeof(mac)); 256 if (error) 257 return (error); 258 259 error = mac_check_structmac_consistent(&mac); 260 if (error) 261 return (error); 262 263 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 264 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 265 if (error) { 266 free(buffer, M_MACTEMP); 267 return (error); 268 } 269 270 label = mac_cred_label_alloc(); 271 error = mac_cred_internalize_label(label, buffer); 272 free(buffer, M_MACTEMP); 273 if (error) { 274 mac_cred_label_free(label); 275 return (error); 276 } 277 imgp->execlabel = label; 278 return (0); 279} 280 281void 282mac_execve_exit(struct image_params *imgp) 283{ 284 if (imgp->execlabel != NULL) { 285 mac_cred_label_free(imgp->execlabel); 286 imgp->execlabel = NULL; 287 } 288} 289 290void 291mac_execve_interpreter_enter(struct vnode *interpvp, 292 struct label **interpvplabel) 293{ 294 295 if (mac_labeled & MPC_OBJECT_VNODE) { 296 *interpvplabel = mac_vnode_label_alloc(); 297 mac_vnode_copy_label(interpvp->v_label, *interpvplabel); 298 } else 299 *interpvplabel = NULL; 300} 301 302void 303mac_execve_interpreter_exit(struct label *interpvplabel) 304{ 305 306 if (interpvplabel != NULL) 307 mac_vnode_label_free(interpvplabel); 308} 309 310/* 311 * When relabeling a process, call out to the policies for the maximum 312 * permission allowed for each object type we know about in its memory space, 313 * and revoke access (in the least surprising ways we know) when necessary. 314 * The process lock is not held here. 315 */ 316void 317mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred) 318{ 319 320 /* XXX freeze all other threads */ 321 mac_cred_mmapped_drop_perms_recurse(td, cred, 322 &td->td_proc->p_vmspace->vm_map); 323 /* XXX allow other threads to continue */ 324} 325 326static __inline const char * 327prot2str(vm_prot_t prot) 328{ 329 330 switch (prot & VM_PROT_ALL) { 331 case VM_PROT_READ: 332 return ("r--"); 333 case VM_PROT_READ | VM_PROT_WRITE: 334 return ("rw-"); 335 case VM_PROT_READ | VM_PROT_EXECUTE: 336 return ("r-x"); 337 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 338 return ("rwx"); 339 case VM_PROT_WRITE: 340 return ("-w-"); 341 case VM_PROT_EXECUTE: 342 return ("--x"); 343 case VM_PROT_WRITE | VM_PROT_EXECUTE: 344 return ("-wx"); 345 default: 346 return ("---"); 347 } 348} 349 350static void 351mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred, 352 struct vm_map *map) 353{ 354 struct vm_map_entry *vme; 355 int vfslocked, result; 356 vm_prot_t revokeperms; 357 vm_object_t backing_object, object; 358 vm_ooffset_t offset; 359 struct vnode *vp; 360 struct mount *mp; 361 362 if (!mac_mmap_revocation) 363 return; 364 365 vm_map_lock_read(map); 366 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 367 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 368 mac_cred_mmapped_drop_perms_recurse(td, cred, 369 vme->object.sub_map); 370 continue; 371 } 372 /* 373 * Skip over entries that obviously are not shared. 374 */ 375 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 376 !vme->max_protection) 377 continue; 378 /* 379 * Drill down to the deepest backing object. 380 */ 381 offset = vme->offset; 382 object = vme->object.vm_object; 383 if (object == NULL) 384 continue; 385 VM_OBJECT_LOCK(object); 386 while ((backing_object = object->backing_object) != NULL) { 387 VM_OBJECT_LOCK(backing_object); 388 offset += object->backing_object_offset; 389 VM_OBJECT_UNLOCK(object); 390 object = backing_object; 391 } 392 VM_OBJECT_UNLOCK(object); 393 /* 394 * At the moment, vm_maps and objects aren't considered by 395 * the MAC system, so only things with backing by a normal 396 * object (read: vnodes) are checked. 397 */ 398 if (object->type != OBJT_VNODE) 399 continue; 400 vp = (struct vnode *)object->handle; 401 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 402 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 403 result = vme->max_protection; 404 mac_vnode_check_mmap_downgrade(cred, vp, &result); 405 VOP_UNLOCK(vp, 0); 406 /* 407 * Find out what maximum protection we may be allowing now 408 * but a policy needs to get removed. 409 */ 410 revokeperms = vme->max_protection & ~result; 411 if (!revokeperms) { 412 VFS_UNLOCK_GIANT(vfslocked); 413 continue; 414 } 415 printf("pid %ld: revoking %s perms from %#lx:%ld " 416 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 417 prot2str(revokeperms), (u_long)vme->start, 418 (long)(vme->end - vme->start), 419 prot2str(vme->max_protection), prot2str(vme->protection)); 420 vm_map_lock_upgrade(map); 421 /* 422 * This is the really simple case: if a map has more 423 * max_protection than is allowed, but it's not being 424 * actually used (that is, the current protection is still 425 * allowed), we can just wipe it out and do nothing more. 426 */ 427 if ((vme->protection & revokeperms) == 0) { 428 vme->max_protection -= revokeperms; 429 } else { 430 if (revokeperms & VM_PROT_WRITE) { 431 /* 432 * In the more complicated case, flush out all 433 * pending changes to the object then turn it 434 * copy-on-write. 435 */ 436 vm_object_reference(object); 437 (void) vn_start_write(vp, &mp, V_WAIT); 438 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 439 VM_OBJECT_LOCK(object); 440 vm_object_page_clean(object, 441 OFF_TO_IDX(offset), 442 OFF_TO_IDX(offset + vme->end - vme->start + 443 PAGE_MASK), 444 OBJPC_SYNC); 445 VM_OBJECT_UNLOCK(object); 446 VOP_UNLOCK(vp, 0); 447 vn_finished_write(mp); 448 vm_object_deallocate(object); 449 /* 450 * Why bother if there's no read permissions 451 * anymore? For the rest, we need to leave 452 * the write permissions on for COW, or 453 * remove them entirely if configured to. 454 */ 455 if (!mac_mmap_revocation_via_cow) { 456 vme->max_protection &= ~VM_PROT_WRITE; 457 vme->protection &= ~VM_PROT_WRITE; 458 } if ((revokeperms & VM_PROT_READ) == 0) 459 vme->eflags |= MAP_ENTRY_COW | 460 MAP_ENTRY_NEEDS_COPY; 461 } 462 if (revokeperms & VM_PROT_EXECUTE) { 463 vme->max_protection &= ~VM_PROT_EXECUTE; 464 vme->protection &= ~VM_PROT_EXECUTE; 465 } 466 if (revokeperms & VM_PROT_READ) { 467 vme->max_protection = 0; 468 vme->protection = 0; 469 } 470 pmap_protect(map->pmap, vme->start, vme->end, 471 vme->protection & ~revokeperms); 472 vm_map_simplify_entry(map, vme); 473 } 474 vm_map_lock_downgrade(map); 475 VFS_UNLOCK_GIANT(vfslocked); 476 } 477 vm_map_unlock_read(map); 478} 479 480/* 481 * When the subject's label changes, it may require revocation of privilege 482 * to mapped objects. This can't be done on-the-fly later with a unified 483 * buffer cache. 484 */ 485void 486mac_cred_relabel(struct ucred *cred, struct label *newlabel) 487{ 488 489 MAC_PERFORM(cred_relabel, cred, newlabel); 490} 491 492int 493mac_cred_check_relabel(struct ucred *cred, struct label *newlabel) 494{ 495 int error; 496 497 MAC_CHECK(cred_check_relabel, cred, newlabel); 498 499 return (error); 500} 501 502int 503mac_cred_check_visible(struct ucred *cr1, struct ucred *cr2) 504{ 505 int error; 506 507 MAC_CHECK(cred_check_visible, cr1, cr2); 508 509 return (error); 510} 511 512int 513mac_proc_check_debug(struct ucred *cred, struct proc *p) 514{ 515 int error; 516 517 PROC_LOCK_ASSERT(p, MA_OWNED); 518 519 MAC_CHECK(proc_check_debug, cred, p); 520 521 return (error); 522} 523 524int 525mac_proc_check_sched(struct ucred *cred, struct proc *p) 526{ 527 int error; 528 529 PROC_LOCK_ASSERT(p, MA_OWNED); 530 531 MAC_CHECK(proc_check_sched, cred, p); 532 533 return (error); 534} 535 536int 537mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum) 538{ 539 int error; 540 541 PROC_LOCK_ASSERT(p, MA_OWNED); 542 543 MAC_CHECK(proc_check_signal, cred, p, signum); 544 545 return (error); 546} 547 548int 549mac_proc_check_setuid(struct proc *p, struct ucred *cred, uid_t uid) 550{ 551 int error; 552 553 PROC_LOCK_ASSERT(p, MA_OWNED); 554 555 MAC_CHECK(proc_check_setuid, cred, uid); 556 return (error); 557} 558 559int 560mac_proc_check_seteuid(struct proc *p, struct ucred *cred, uid_t euid) 561{ 562 int error; 563 564 PROC_LOCK_ASSERT(p, MA_OWNED); 565 566 MAC_CHECK(proc_check_seteuid, cred, euid); 567 return (error); 568} 569 570int 571mac_proc_check_setgid(struct proc *p, struct ucred *cred, gid_t gid) 572{ 573 int error; 574 575 PROC_LOCK_ASSERT(p, MA_OWNED); 576 577 MAC_CHECK(proc_check_setgid, cred, gid); 578 579 return (error); 580} 581 582int 583mac_proc_check_setegid(struct proc *p, struct ucred *cred, gid_t egid) 584{ 585 int error; 586 587 PROC_LOCK_ASSERT(p, MA_OWNED); 588 589 MAC_CHECK(proc_check_setegid, cred, egid); 590 591 return (error); 592} 593 594int 595mac_proc_check_setgroups(struct proc *p, struct ucred *cred, int ngroups, 596 gid_t *gidset) 597{ 598 int error; 599 600 PROC_LOCK_ASSERT(p, MA_OWNED); 601 602 MAC_CHECK(proc_check_setgroups, cred, ngroups, gidset); 603 return (error); 604} 605 606int 607mac_proc_check_setreuid(struct proc *p, struct ucred *cred, uid_t ruid, 608 uid_t euid) 609{ 610 int error; 611 612 PROC_LOCK_ASSERT(p, MA_OWNED); 613 614 MAC_CHECK(proc_check_setreuid, cred, ruid, euid); 615 616 return (error); 617} 618 619int 620mac_proc_check_setregid(struct proc *proc, struct ucred *cred, gid_t rgid, 621 gid_t egid) 622{ 623 int error; 624 625 PROC_LOCK_ASSERT(proc, MA_OWNED); 626 627 MAC_CHECK(proc_check_setregid, cred, rgid, egid); 628 629 return (error); 630} 631 632int 633mac_proc_check_setresuid(struct proc *p, struct ucred *cred, uid_t ruid, 634 uid_t euid, uid_t suid) 635{ 636 int error; 637 638 PROC_LOCK_ASSERT(p, MA_OWNED); 639 640 MAC_CHECK(proc_check_setresuid, cred, ruid, euid, suid); 641 return (error); 642} 643 644int 645mac_proc_check_setresgid(struct proc *p, struct ucred *cred, gid_t rgid, 646 gid_t egid, gid_t sgid) 647{ 648 int error; 649 650 PROC_LOCK_ASSERT(p, MA_OWNED); 651 652 MAC_CHECK(proc_check_setresgid, cred, rgid, egid, sgid); 653 654 return (error); 655} 656 657int 658mac_proc_check_wait(struct ucred *cred, struct proc *p) 659{ 660 int error; 661 662 PROC_LOCK_ASSERT(p, MA_OWNED); 663 664 MAC_CHECK(proc_check_wait, cred, p); 665 666 return (error); 667} 668