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>
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44__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 184407 2008-10-28 11:33:06Z rwatson $");
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44__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 184412 2008-10-28 12:49:07Z 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
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84static void mac_cred_mmapped_drop_perms_recurse(struct thread *td,
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84static void mac_proc_vm_revoke_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
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317mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred)
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317mac_proc_vm_revoke(struct thread *td) |
318{
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319 struct ucred *cred; |
320
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321 PROC_LOCK(td->td_proc); 322 cred = crhold(td->td_proc->p_ucred); 323 PROC_UNLOCK(td->td_proc); 324 |
325 /* XXX freeze all other threads */
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321 mac_cred_mmapped_drop_perms_recurse(td, cred,
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326 mac_proc_vm_revoke_recurse(td, cred, |
327 &td->td_proc->p_vmspace->vm_map); 328 /* XXX allow other threads to continue */
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329 330 crfree(cred); |
331} 332 333static __inline const char * 334prot2str(vm_prot_t prot) 335{ 336 337 switch (prot & VM_PROT_ALL) { 338 case VM_PROT_READ: 339 return ("r--"); 340 case VM_PROT_READ | VM_PROT_WRITE: 341 return ("rw-"); 342 case VM_PROT_READ | VM_PROT_EXECUTE: 343 return ("r-x"); 344 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 345 return ("rwx"); 346 case VM_PROT_WRITE: 347 return ("-w-"); 348 case VM_PROT_EXECUTE: 349 return ("--x"); 350 case VM_PROT_WRITE | VM_PROT_EXECUTE: 351 return ("-wx"); 352 default: 353 return ("---"); 354 } 355} 356 357static void
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351mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred,
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358mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred, |
359 struct vm_map *map) 360{ 361 struct vm_map_entry *vme; 362 int vfslocked, result; 363 vm_prot_t revokeperms; 364 vm_object_t backing_object, object; 365 vm_ooffset_t offset; 366 struct vnode *vp; 367 struct mount *mp; 368 369 if (!mac_mmap_revocation) 370 return; 371 372 vm_map_lock_read(map); 373 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 374 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
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368 mac_cred_mmapped_drop_perms_recurse(td, cred,
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375 mac_proc_vm_revoke_recurse(td, cred, |
376 vme->object.sub_map); 377 continue; 378 } 379 /* 380 * Skip over entries that obviously are not shared. 381 */ 382 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 383 !vme->max_protection) 384 continue; 385 /* 386 * Drill down to the deepest backing object. 387 */ 388 offset = vme->offset; 389 object = vme->object.vm_object; 390 if (object == NULL) 391 continue; 392 VM_OBJECT_LOCK(object); 393 while ((backing_object = object->backing_object) != NULL) { 394 VM_OBJECT_LOCK(backing_object); 395 offset += object->backing_object_offset; 396 VM_OBJECT_UNLOCK(object); 397 object = backing_object; 398 } 399 VM_OBJECT_UNLOCK(object); 400 /* 401 * At the moment, vm_maps and objects aren't considered by 402 * the MAC system, so only things with backing by a normal 403 * object (read: vnodes) are checked. 404 */ 405 if (object->type != OBJT_VNODE) 406 continue; 407 vp = (struct vnode *)object->handle; 408 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 409 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 410 result = vme->max_protection; 411 mac_vnode_check_mmap_downgrade(cred, vp, &result); 412 VOP_UNLOCK(vp, 0); 413 /* 414 * Find out what maximum protection we may be allowing now 415 * but a policy needs to get removed. 416 */ 417 revokeperms = vme->max_protection & ~result; 418 if (!revokeperms) { 419 VFS_UNLOCK_GIANT(vfslocked); 420 continue; 421 } 422 printf("pid %ld: revoking %s perms from %#lx:%ld " 423 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 424 prot2str(revokeperms), (u_long)vme->start, 425 (long)(vme->end - vme->start), 426 prot2str(vme->max_protection), prot2str(vme->protection)); 427 vm_map_lock_upgrade(map); 428 /* 429 * This is the really simple case: if a map has more 430 * max_protection than is allowed, but it's not being 431 * actually used (that is, the current protection is still 432 * allowed), we can just wipe it out and do nothing more. 433 */ 434 if ((vme->protection & revokeperms) == 0) { 435 vme->max_protection -= revokeperms; 436 } else { 437 if (revokeperms & VM_PROT_WRITE) { 438 /* 439 * In the more complicated case, flush out all 440 * pending changes to the object then turn it 441 * copy-on-write. 442 */ 443 vm_object_reference(object); 444 (void) vn_start_write(vp, &mp, V_WAIT); 445 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 446 VM_OBJECT_LOCK(object); 447 vm_object_page_clean(object, 448 OFF_TO_IDX(offset), 449 OFF_TO_IDX(offset + vme->end - vme->start + 450 PAGE_MASK), 451 OBJPC_SYNC); 452 VM_OBJECT_UNLOCK(object); 453 VOP_UNLOCK(vp, 0); 454 vn_finished_write(mp); 455 vm_object_deallocate(object); 456 /* 457 * Why bother if there's no read permissions 458 * anymore? For the rest, we need to leave 459 * the write permissions on for COW, or 460 * remove them entirely if configured to. 461 */ 462 if (!mac_mmap_revocation_via_cow) { 463 vme->max_protection &= ~VM_PROT_WRITE; 464 vme->protection &= ~VM_PROT_WRITE; 465 } if ((revokeperms & VM_PROT_READ) == 0) 466 vme->eflags |= MAP_ENTRY_COW | 467 MAP_ENTRY_NEEDS_COPY; 468 } 469 if (revokeperms & VM_PROT_EXECUTE) { 470 vme->max_protection &= ~VM_PROT_EXECUTE; 471 vme->protection &= ~VM_PROT_EXECUTE; 472 } 473 if (revokeperms & VM_PROT_READ) { 474 vme->max_protection = 0; 475 vme->protection = 0; 476 } 477 pmap_protect(map->pmap, vme->start, vme->end, 478 vme->protection & ~revokeperms); 479 vm_map_simplify_entry(map, vme); 480 } 481 vm_map_lock_downgrade(map); 482 VFS_UNLOCK_GIANT(vfslocked); 483 } 484 vm_map_unlock_read(map); 485} 486 487/* 488 * When the subject's label changes, it may require revocation of privilege 489 * to mapped objects. This can't be done on-the-fly later with a unified 490 * buffer cache. 491 */ 492void 493mac_cred_relabel(struct ucred *cred, struct label *newlabel) 494{ 495 496 MAC_PERFORM(cred_relabel, cred, newlabel); 497} 498 499int 500mac_cred_check_relabel(struct ucred *cred, struct label *newlabel) 501{ 502 int error; 503 504 MAC_CHECK(cred_check_relabel, cred, newlabel); 505 506 return (error); 507} 508 509int 510mac_cred_check_visible(struct ucred *cr1, struct ucred *cr2) 511{ 512 int error; 513 514 MAC_CHECK(cred_check_visible, cr1, cr2); 515 516 return (error); 517} 518 519int 520mac_proc_check_debug(struct ucred *cred, struct proc *p) 521{ 522 int error; 523 524 PROC_LOCK_ASSERT(p, MA_OWNED); 525 526 MAC_CHECK(proc_check_debug, cred, p); 527 528 return (error); 529} 530 531int 532mac_proc_check_sched(struct ucred *cred, struct proc *p) 533{ 534 int error; 535 536 PROC_LOCK_ASSERT(p, MA_OWNED); 537 538 MAC_CHECK(proc_check_sched, cred, p); 539 540 return (error); 541} 542 543int 544mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum) 545{ 546 int error; 547 548 PROC_LOCK_ASSERT(p, MA_OWNED); 549 550 MAC_CHECK(proc_check_signal, cred, p, signum); 551 552 return (error); 553} 554 555int 556mac_proc_check_setuid(struct proc *p, struct ucred *cred, uid_t uid) 557{ 558 int error; 559 560 PROC_LOCK_ASSERT(p, MA_OWNED); 561 562 MAC_CHECK(proc_check_setuid, cred, uid); 563 return (error); 564} 565 566int 567mac_proc_check_seteuid(struct proc *p, struct ucred *cred, uid_t euid) 568{ 569 int error; 570 571 PROC_LOCK_ASSERT(p, MA_OWNED); 572 573 MAC_CHECK(proc_check_seteuid, cred, euid); 574 return (error); 575} 576 577int 578mac_proc_check_setgid(struct proc *p, struct ucred *cred, gid_t gid) 579{ 580 int error; 581 582 PROC_LOCK_ASSERT(p, MA_OWNED); 583 584 MAC_CHECK(proc_check_setgid, cred, gid); 585 586 return (error); 587} 588 589int 590mac_proc_check_setegid(struct proc *p, struct ucred *cred, gid_t egid) 591{ 592 int error; 593 594 PROC_LOCK_ASSERT(p, MA_OWNED); 595 596 MAC_CHECK(proc_check_setegid, cred, egid); 597 598 return (error); 599} 600 601int 602mac_proc_check_setgroups(struct proc *p, struct ucred *cred, int ngroups, 603 gid_t *gidset) 604{ 605 int error; 606 607 PROC_LOCK_ASSERT(p, MA_OWNED); 608 609 MAC_CHECK(proc_check_setgroups, cred, ngroups, gidset); 610 return (error); 611} 612 613int 614mac_proc_check_setreuid(struct proc *p, struct ucred *cred, uid_t ruid, 615 uid_t euid) 616{ 617 int error; 618 619 PROC_LOCK_ASSERT(p, MA_OWNED); 620 621 MAC_CHECK(proc_check_setreuid, cred, ruid, euid); 622 623 return (error); 624} 625 626int 627mac_proc_check_setregid(struct proc *proc, struct ucred *cred, gid_t rgid, 628 gid_t egid) 629{ 630 int error; 631 632 PROC_LOCK_ASSERT(proc, MA_OWNED); 633 634 MAC_CHECK(proc_check_setregid, cred, rgid, egid); 635 636 return (error); 637} 638 639int 640mac_proc_check_setresuid(struct proc *p, struct ucred *cred, uid_t ruid, 641 uid_t euid, uid_t suid) 642{ 643 int error; 644 645 PROC_LOCK_ASSERT(p, MA_OWNED); 646 647 MAC_CHECK(proc_check_setresuid, cred, ruid, euid, suid); 648 return (error); 649} 650 651int 652mac_proc_check_setresgid(struct proc *p, struct ucred *cred, gid_t rgid, 653 gid_t egid, gid_t sgid) 654{ 655 int error; 656 657 PROC_LOCK_ASSERT(p, MA_OWNED); 658 659 MAC_CHECK(proc_check_setresgid, cred, rgid, egid, sgid); 660 661 return (error); 662} 663 664int 665mac_proc_check_wait(struct ucred *cred, struct proc *p) 666{ 667 int error; 668 669 PROC_LOCK_ASSERT(p, MA_OWNED); 670 671 MAC_CHECK(proc_check_wait, cred, p); 672 673 return (error); 674}
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