mac_cred.c revision 162467
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: head/sys/security/mac/mac_process.c 162467 2006-09-20 13:33:41Z rwatson $"); 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 69int mac_enforce_process = 1; 70SYSCTL_INT(_security_mac, OID_AUTO, enforce_process, CTLFLAG_RW, 71 &mac_enforce_process, 0, "Enforce MAC policy on inter-process operations"); 72TUNABLE_INT("security.mac.enforce_process", &mac_enforce_process); 73 74int mac_enforce_vm = 1; 75SYSCTL_INT(_security_mac, OID_AUTO, enforce_vm, CTLFLAG_RW, 76 &mac_enforce_vm, 0, "Enforce MAC policy on vm operations"); 77TUNABLE_INT("security.mac.enforce_vm", &mac_enforce_vm); 78 79static int mac_mmap_revocation = 1; 80SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 81 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 82 "relabel"); 83 84static int mac_mmap_revocation_via_cow = 0; 85SYSCTL_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 89static int mac_enforce_suid = 1; 90SYSCTL_INT(_security_mac, OID_AUTO, enforce_suid, CTLFLAG_RW, 91 &mac_enforce_suid, 0, "Enforce MAC policy on suid/sgid operations"); 92TUNABLE_INT("security.mac.enforce_suid", &mac_enforce_suid); 93 94static void mac_cred_mmapped_drop_perms_recurse(struct thread *td, 95 struct ucred *cred, struct vm_map *map); 96 97struct label * 98mac_cred_label_alloc(void) 99{ 100 struct label *label; 101 102 label = mac_labelzone_alloc(M_WAITOK); 103 MAC_PERFORM(init_cred_label, label); 104 return (label); 105} 106 107void 108mac_init_cred(struct ucred *cred) 109{ 110 111 cred->cr_label = mac_cred_label_alloc(); 112} 113 114static struct label * 115mac_proc_label_alloc(void) 116{ 117 struct label *label; 118 119 label = mac_labelzone_alloc(M_WAITOK); 120 MAC_PERFORM(init_proc_label, label); 121 return (label); 122} 123 124void 125mac_init_proc(struct proc *p) 126{ 127 128 p->p_label = mac_proc_label_alloc(); 129} 130 131void 132mac_cred_label_free(struct label *label) 133{ 134 135 MAC_PERFORM(destroy_cred_label, label); 136 mac_labelzone_free(label); 137} 138 139void 140mac_destroy_cred(struct ucred *cred) 141{ 142 143 mac_cred_label_free(cred->cr_label); 144 cred->cr_label = NULL; 145} 146 147static void 148mac_proc_label_free(struct label *label) 149{ 150 151 MAC_PERFORM(destroy_proc_label, label); 152 mac_labelzone_free(label); 153} 154 155void 156mac_destroy_proc(struct proc *p) 157{ 158 159 mac_proc_label_free(p->p_label); 160 p->p_label = NULL; 161} 162 163int 164mac_externalize_cred_label(struct label *label, char *elements, 165 char *outbuf, size_t outbuflen) 166{ 167 int error; 168 169 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen); 170 171 return (error); 172} 173 174int 175mac_internalize_cred_label(struct label *label, char *string) 176{ 177 int error; 178 179 MAC_INTERNALIZE(cred, label, string); 180 181 return (error); 182} 183 184/* 185 * Initialize MAC label for the first kernel process, from which other 186 * kernel processes and threads are spawned. 187 */ 188void 189mac_create_proc0(struct ucred *cred) 190{ 191 192 MAC_PERFORM(create_proc0, cred); 193} 194 195/* 196 * Initialize MAC label for the first userland process, from which other 197 * userland processes and threads are spawned. 198 */ 199void 200mac_create_proc1(struct ucred *cred) 201{ 202 203 MAC_PERFORM(create_proc1, cred); 204} 205 206void 207mac_thread_userret(struct thread *td) 208{ 209 210 MAC_PERFORM(thread_userret, td); 211} 212 213/* 214 * When a new process is created, its label must be initialized. Generally, 215 * this involves inheritence from the parent process, modulo possible 216 * deltas. This function allows that processing to take place. 217 */ 218void 219mac_copy_cred(struct ucred *src, struct ucred *dest) 220{ 221 222 MAC_PERFORM(copy_cred_label, src->cr_label, dest->cr_label); 223} 224 225int 226mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 227{ 228 struct label *label; 229 struct mac mac; 230 char *buffer; 231 int error; 232 233 if (mac_p == NULL) 234 return (0); 235 236 error = copyin(mac_p, &mac, sizeof(mac)); 237 if (error) 238 return (error); 239 240 error = mac_check_structmac_consistent(&mac); 241 if (error) 242 return (error); 243 244 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 245 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 246 if (error) { 247 free(buffer, M_MACTEMP); 248 return (error); 249 } 250 251 label = mac_cred_label_alloc(); 252 error = mac_internalize_cred_label(label, buffer); 253 free(buffer, M_MACTEMP); 254 if (error) { 255 mac_cred_label_free(label); 256 return (error); 257 } 258 imgp->execlabel = label; 259 return (0); 260} 261 262void 263mac_execve_exit(struct image_params *imgp) 264{ 265 if (imgp->execlabel != NULL) { 266 mac_cred_label_free(imgp->execlabel); 267 imgp->execlabel = NULL; 268 } 269} 270 271/* 272 * When relabeling a process, call out to the policies for the maximum 273 * permission allowed for each object type we know about in its 274 * memory space, and revoke access (in the least surprising ways we 275 * know) when necessary. The process lock is not held here. 276 */ 277void 278mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred) 279{ 280 281 /* XXX freeze all other threads */ 282 mac_cred_mmapped_drop_perms_recurse(td, cred, 283 &td->td_proc->p_vmspace->vm_map); 284 /* XXX allow other threads to continue */ 285} 286 287static __inline const char * 288prot2str(vm_prot_t prot) 289{ 290 291 switch (prot & VM_PROT_ALL) { 292 case VM_PROT_READ: 293 return ("r--"); 294 case VM_PROT_READ | VM_PROT_WRITE: 295 return ("rw-"); 296 case VM_PROT_READ | VM_PROT_EXECUTE: 297 return ("r-x"); 298 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 299 return ("rwx"); 300 case VM_PROT_WRITE: 301 return ("-w-"); 302 case VM_PROT_EXECUTE: 303 return ("--x"); 304 case VM_PROT_WRITE | VM_PROT_EXECUTE: 305 return ("-wx"); 306 default: 307 return ("---"); 308 } 309} 310 311static void 312mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred, 313 struct vm_map *map) 314{ 315 struct vm_map_entry *vme; 316 int vfslocked, result; 317 vm_prot_t revokeperms; 318 vm_object_t backing_object, object; 319 vm_ooffset_t offset; 320 struct vnode *vp; 321 struct mount *mp; 322 323 if (!mac_mmap_revocation) 324 return; 325 326 vm_map_lock_read(map); 327 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 328 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 329 mac_cred_mmapped_drop_perms_recurse(td, cred, 330 vme->object.sub_map); 331 continue; 332 } 333 /* 334 * Skip over entries that obviously are not shared. 335 */ 336 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 337 !vme->max_protection) 338 continue; 339 /* 340 * Drill down to the deepest backing object. 341 */ 342 offset = vme->offset; 343 object = vme->object.vm_object; 344 if (object == NULL) 345 continue; 346 VM_OBJECT_LOCK(object); 347 while ((backing_object = object->backing_object) != NULL) { 348 VM_OBJECT_LOCK(backing_object); 349 offset += object->backing_object_offset; 350 VM_OBJECT_UNLOCK(object); 351 object = backing_object; 352 } 353 VM_OBJECT_UNLOCK(object); 354 /* 355 * At the moment, vm_maps and objects aren't considered 356 * by the MAC system, so only things with backing by a 357 * normal object (read: vnodes) are checked. 358 */ 359 if (object->type != OBJT_VNODE) 360 continue; 361 vp = (struct vnode *)object->handle; 362 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 363 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 364 result = vme->max_protection; 365 mac_check_vnode_mmap_downgrade(cred, vp, &result); 366 VOP_UNLOCK(vp, 0, td); 367 /* 368 * Find out what maximum protection we may be allowing 369 * now but a policy needs to get removed. 370 */ 371 revokeperms = vme->max_protection & ~result; 372 if (!revokeperms) { 373 VFS_UNLOCK_GIANT(vfslocked); 374 continue; 375 } 376 printf("pid %ld: revoking %s perms from %#lx:%ld " 377 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 378 prot2str(revokeperms), (u_long)vme->start, 379 (long)(vme->end - vme->start), 380 prot2str(vme->max_protection), prot2str(vme->protection)); 381 vm_map_lock_upgrade(map); 382 /* 383 * This is the really simple case: if a map has more 384 * max_protection than is allowed, but it's not being 385 * actually used (that is, the current protection is 386 * still allowed), we can just wipe it out and do 387 * nothing more. 388 */ 389 if ((vme->protection & revokeperms) == 0) { 390 vme->max_protection -= revokeperms; 391 } else { 392 if (revokeperms & VM_PROT_WRITE) { 393 /* 394 * In the more complicated case, flush out all 395 * pending changes to the object then turn it 396 * copy-on-write. 397 */ 398 vm_object_reference(object); 399 (void) vn_start_write(vp, &mp, V_WAIT); 400 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 401 VM_OBJECT_LOCK(object); 402 vm_object_page_clean(object, 403 OFF_TO_IDX(offset), 404 OFF_TO_IDX(offset + vme->end - vme->start + 405 PAGE_MASK), 406 OBJPC_SYNC); 407 VM_OBJECT_UNLOCK(object); 408 VOP_UNLOCK(vp, 0, td); 409 vn_finished_write(mp); 410 vm_object_deallocate(object); 411 /* 412 * Why bother if there's no read permissions 413 * anymore? For the rest, we need to leave 414 * the write permissions on for COW, or 415 * remove them entirely if configured to. 416 */ 417 if (!mac_mmap_revocation_via_cow) { 418 vme->max_protection &= ~VM_PROT_WRITE; 419 vme->protection &= ~VM_PROT_WRITE; 420 } if ((revokeperms & VM_PROT_READ) == 0) 421 vme->eflags |= MAP_ENTRY_COW | 422 MAP_ENTRY_NEEDS_COPY; 423 } 424 if (revokeperms & VM_PROT_EXECUTE) { 425 vme->max_protection &= ~VM_PROT_EXECUTE; 426 vme->protection &= ~VM_PROT_EXECUTE; 427 } 428 if (revokeperms & VM_PROT_READ) { 429 vme->max_protection = 0; 430 vme->protection = 0; 431 } 432 pmap_protect(map->pmap, vme->start, vme->end, 433 vme->protection & ~revokeperms); 434 vm_map_simplify_entry(map, vme); 435 } 436 vm_map_lock_downgrade(map); 437 VFS_UNLOCK_GIANT(vfslocked); 438 } 439 vm_map_unlock_read(map); 440} 441 442/* 443 * When the subject's label changes, it may require revocation of privilege 444 * to mapped objects. This can't be done on-the-fly later with a unified 445 * buffer cache. 446 */ 447void 448mac_relabel_cred(struct ucred *cred, struct label *newlabel) 449{ 450 451 MAC_PERFORM(relabel_cred, cred, newlabel); 452} 453 454int 455mac_check_cred_relabel(struct ucred *cred, struct label *newlabel) 456{ 457 int error; 458 459 MAC_CHECK(check_cred_relabel, cred, newlabel); 460 461 return (error); 462} 463 464int 465mac_check_cred_visible(struct ucred *u1, struct ucred *u2) 466{ 467 int error; 468 469 if (!mac_enforce_process) 470 return (0); 471 472 MAC_CHECK(check_cred_visible, u1, u2); 473 474 return (error); 475} 476 477int 478mac_check_proc_debug(struct ucred *cred, struct proc *proc) 479{ 480 int error; 481 482 PROC_LOCK_ASSERT(proc, MA_OWNED); 483 484 if (!mac_enforce_process) 485 return (0); 486 487 MAC_CHECK(check_proc_debug, cred, proc); 488 489 return (error); 490} 491 492int 493mac_check_proc_sched(struct ucred *cred, struct proc *proc) 494{ 495 int error; 496 497 PROC_LOCK_ASSERT(proc, MA_OWNED); 498 499 if (!mac_enforce_process) 500 return (0); 501 502 MAC_CHECK(check_proc_sched, cred, proc); 503 504 return (error); 505} 506 507int 508mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum) 509{ 510 int error; 511 512 PROC_LOCK_ASSERT(proc, MA_OWNED); 513 514 if (!mac_enforce_process) 515 return (0); 516 517 MAC_CHECK(check_proc_signal, cred, proc, signum); 518 519 return (error); 520} 521 522int 523mac_check_proc_setuid(struct proc *proc, struct ucred *cred, uid_t uid) 524{ 525 int error; 526 527 PROC_LOCK_ASSERT(proc, MA_OWNED); 528 529 if (!mac_enforce_suid) 530 return (0); 531 532 MAC_CHECK(check_proc_setuid, cred, uid); 533 return (error); 534} 535 536int 537mac_check_proc_seteuid(struct proc *proc, struct ucred *cred, uid_t euid) 538{ 539 int error; 540 541 PROC_LOCK_ASSERT(proc, MA_OWNED); 542 543 if (!mac_enforce_suid) 544 return (0); 545 546 MAC_CHECK(check_proc_seteuid, cred, euid); 547 return (error); 548} 549 550int 551mac_check_proc_setgid(struct proc *proc, struct ucred *cred, gid_t gid) 552{ 553 int error; 554 555 PROC_LOCK_ASSERT(proc, MA_OWNED); 556 557 if (!mac_enforce_suid) 558 return (0); 559 560 MAC_CHECK(check_proc_setgid, cred, gid); 561 return (error); 562} 563 564int 565mac_check_proc_setegid(struct proc *proc, struct ucred *cred, gid_t egid) 566{ 567 int error; 568 569 PROC_LOCK_ASSERT(proc, MA_OWNED); 570 571 if (!mac_enforce_suid) 572 return (0); 573 574 MAC_CHECK(check_proc_setegid, cred, egid); 575 return (error); 576} 577 578int 579mac_check_proc_setgroups(struct proc *proc, struct ucred *cred, 580 int ngroups, gid_t *gidset) 581{ 582 int error; 583 584 PROC_LOCK_ASSERT(proc, MA_OWNED); 585 586 if (!mac_enforce_suid) 587 return (0); 588 589 MAC_CHECK(check_proc_setgroups, cred, ngroups, gidset); 590 return (error); 591} 592 593int 594mac_check_proc_setreuid(struct proc *proc, struct ucred *cred, uid_t ruid, 595 uid_t euid) 596{ 597 int error; 598 599 PROC_LOCK_ASSERT(proc, MA_OWNED); 600 601 if (!mac_enforce_suid) 602 return (0); 603 604 MAC_CHECK(check_proc_setreuid, cred, ruid, euid); 605 return (error); 606} 607 608int 609mac_check_proc_setregid(struct proc *proc, struct ucred *cred, gid_t rgid, 610 gid_t egid) 611{ 612 int error; 613 614 PROC_LOCK_ASSERT(proc, MA_OWNED); 615 616 if (!mac_enforce_suid) 617 return (0); 618 619 MAC_CHECK(check_proc_setregid, cred, rgid, egid); 620 return (error); 621} 622 623int 624mac_check_proc_setresuid(struct proc *proc, struct ucred *cred, uid_t ruid, 625 uid_t euid, uid_t suid) 626{ 627 int error; 628 629 PROC_LOCK_ASSERT(proc, MA_OWNED); 630 631 if (!mac_enforce_suid) 632 return (0); 633 634 MAC_CHECK(check_proc_setresuid, cred, ruid, euid, suid); 635 return (error); 636} 637 638int 639mac_check_proc_setresgid(struct proc *proc, struct ucred *cred, gid_t rgid, 640 gid_t egid, gid_t sgid) 641{ 642 int error; 643 644 PROC_LOCK_ASSERT(proc, MA_OWNED); 645 646 if (!mac_enforce_suid) 647 return (0); 648 649 MAC_CHECK(check_proc_setresgid, cred, rgid, egid, sgid); 650 return (error); 651} 652 653int 654mac_check_proc_wait(struct ucred *cred, struct proc *proc) 655{ 656 int error; 657 658 PROC_LOCK_ASSERT(proc, MA_OWNED); 659 660 if (!mac_enforce_process) 661 return (0); 662 663 MAC_CHECK(check_proc_wait, cred, proc); 664 665 return (error); 666} 667