1/*- 2 * Copyright (c) 1999, 2000, 2001, 2002 Robert N. M. Watson 3 * Copyright (c) 2001 Ilmar S. Habibulin 4 * Copyright (c) 2001, 2002, 2003 Networks Associates Technology, Inc. 5 * All rights reserved. 6 * 7 * This software was developed by Robert Watson and Ilmar Habibulin for the 8 * TrustedBSD Project. 9 * 10 * This software was developed for the FreeBSD Project in part by Network 11 * Associates Laboratories, the Security Research Division of Network 12 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 13 * as part of the DARPA CHATS research program. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#include <sys/cdefs.h>
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38__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 122524 2003-11-12 03:14:31Z rwatson $");
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38__FBSDID("$FreeBSD: head/sys/security/mac/mac_process.c 123173 2003-12-06 21:48:03Z rwatson $"); |
39 40#include "opt_mac.h" 41 42#include <sys/param.h> 43#include <sys/condvar.h> 44#include <sys/imgact.h> 45#include <sys/kernel.h> 46#include <sys/lock.h> 47#include <sys/malloc.h> 48#include <sys/mutex.h> 49#include <sys/mac.h> 50#include <sys/proc.h> 51#include <sys/sbuf.h> 52#include <sys/systm.h> 53#include <sys/vnode.h> 54#include <sys/mount.h> 55#include <sys/file.h> 56#include <sys/namei.h> 57#include <sys/sysctl.h> 58 59#include <vm/vm.h> 60#include <vm/pmap.h> 61#include <vm/vm_map.h> 62#include <vm/vm_object.h> 63 64#include <sys/mac_policy.h> 65 66#include <security/mac/mac_internal.h> 67 68int mac_enforce_process = 1; 69SYSCTL_INT(_security_mac, OID_AUTO, enforce_process, CTLFLAG_RW, 70 &mac_enforce_process, 0, "Enforce MAC policy on inter-process operations"); 71TUNABLE_INT("security.mac.enforce_process", &mac_enforce_process); 72 73int mac_enforce_vm = 1; 74SYSCTL_INT(_security_mac, OID_AUTO, enforce_vm, CTLFLAG_RW, 75 &mac_enforce_vm, 0, "Enforce MAC policy on vm operations"); 76TUNABLE_INT("security.mac.enforce_vm", &mac_enforce_vm); 77 78static int mac_mmap_revocation = 1; 79SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 80 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 81 "relabel"); 82 83static int mac_mmap_revocation_via_cow = 0; 84SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW, 85 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via " 86 "copy-on-write semantics, or by removing all write access"); 87 88#ifdef MAC_DEBUG 89static unsigned int nmaccreds, nmacprocs; 90SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, creds, CTLFLAG_RD, 91 &nmaccreds, 0, "number of ucreds in use"); 92SYSCTL_UINT(_security_mac_debug_counters, OID_AUTO, procs, CTLFLAG_RD, 93 &nmacprocs, 0, "number of procs in use"); 94#endif 95 96static void mac_cred_mmapped_drop_perms_recurse(struct thread *td, 97 struct ucred *cred, struct vm_map *map); 98 99struct label * 100mac_cred_label_alloc(void) 101{ 102 struct label *label; 103 104 label = mac_labelzone_alloc(M_WAITOK); 105 MAC_PERFORM(init_cred_label, label); 106 MAC_DEBUG_COUNTER_INC(&nmaccreds); 107 return (label); 108} 109 110void 111mac_init_cred(struct ucred *cred) 112{ 113 114 cred->cr_label = mac_cred_label_alloc(); 115} 116 117static struct label * 118mac_proc_label_alloc(void) 119{ 120 struct label *label; 121 122 label = mac_labelzone_alloc(M_WAITOK); 123 MAC_PERFORM(init_proc_label, label); 124 MAC_DEBUG_COUNTER_INC(&nmacprocs); 125 return (label); 126} 127 128void 129mac_init_proc(struct proc *p) 130{ 131 132 p->p_label = mac_proc_label_alloc(); 133} 134 135void 136mac_cred_label_free(struct label *label) 137{ 138 139 MAC_PERFORM(destroy_cred_label, label); 140 mac_labelzone_free(label); 141 MAC_DEBUG_COUNTER_DEC(&nmaccreds); 142} 143 144void 145mac_destroy_cred(struct ucred *cred) 146{ 147 148 mac_cred_label_free(cred->cr_label); 149 cred->cr_label = NULL; 150} 151 152static void 153mac_proc_label_free(struct label *label) 154{ 155 156 MAC_PERFORM(destroy_proc_label, label); 157 mac_labelzone_free(label); 158 MAC_DEBUG_COUNTER_DEC(&nmacprocs); 159} 160 161void 162mac_destroy_proc(struct proc *p) 163{ 164 165 mac_proc_label_free(p->p_label); 166 p->p_label = NULL; 167} 168 169int 170mac_externalize_cred_label(struct label *label, char *elements, 171 char *outbuf, size_t outbuflen) 172{ 173 int error; 174 175 MAC_EXTERNALIZE(cred, label, elements, outbuf, outbuflen); 176 177 return (error); 178} 179 180int 181mac_internalize_cred_label(struct label *label, char *string) 182{ 183 int error; 184 185 MAC_INTERNALIZE(cred, label, string); 186 187 return (error); 188} 189 190/* 191 * Initialize MAC label for the first kernel process, from which other 192 * kernel processes and threads are spawned. 193 */ 194void 195mac_create_proc0(struct ucred *cred) 196{ 197 198 MAC_PERFORM(create_proc0, cred); 199} 200 201/* 202 * Initialize MAC label for the first userland process, from which other 203 * userland processes and threads are spawned. 204 */ 205void 206mac_create_proc1(struct ucred *cred) 207{ 208 209 MAC_PERFORM(create_proc1, cred); 210} 211 212void 213mac_thread_userret(struct thread *td) 214{ 215 216 MAC_PERFORM(thread_userret, td); 217} 218 219/* 220 * When a new process is created, its label must be initialized. Generally, 221 * this involves inheritence from the parent process, modulo possible 222 * deltas. This function allows that processing to take place. 223 */ 224void
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225mac_create_cred(struct ucred *parent_cred, struct ucred *child_cred)
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225mac_copy_cred(struct ucred *src, struct ucred *dest) |
226{ 227
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228 MAC_PERFORM(create_cred, parent_cred, child_cred);
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228 MAC_PERFORM(copy_cred_label, src->cr_label, dest->cr_label); |
229} 230 231int 232mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 233{ 234 struct label *label; 235 struct mac mac; 236 char *buffer; 237 int error; 238 239 if (mac_p == NULL) 240 return (0); 241 242 error = copyin(mac_p, &mac, sizeof(mac)); 243 if (error) 244 return (error); 245 246 error = mac_check_structmac_consistent(&mac); 247 if (error) 248 return (error); 249 250 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 251 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 252 if (error) { 253 free(buffer, M_MACTEMP); 254 return (error); 255 } 256 257 label = mac_cred_label_alloc(); 258 error = mac_internalize_cred_label(label, buffer); 259 free(buffer, M_MACTEMP); 260 if (error) { 261 mac_cred_label_free(label); 262 return (error); 263 } 264 imgp->execlabel = label; 265 return (0); 266} 267 268void 269mac_execve_exit(struct image_params *imgp) 270{ 271 if (imgp->execlabel != NULL) { 272 mac_cred_label_free(imgp->execlabel); 273 imgp->execlabel = NULL; 274 } 275} 276 277/* 278 * When relabeling a process, call out to the policies for the maximum 279 * permission allowed for each object type we know about in its 280 * memory space, and revoke access (in the least surprising ways we 281 * know) when necessary. The process lock is not held here. 282 */ 283void 284mac_cred_mmapped_drop_perms(struct thread *td, struct ucred *cred) 285{ 286 287 /* XXX freeze all other threads */ 288 mac_cred_mmapped_drop_perms_recurse(td, cred, 289 &td->td_proc->p_vmspace->vm_map); 290 /* XXX allow other threads to continue */ 291} 292 293static __inline const char * 294prot2str(vm_prot_t prot) 295{ 296 297 switch (prot & VM_PROT_ALL) { 298 case VM_PROT_READ: 299 return ("r--"); 300 case VM_PROT_READ | VM_PROT_WRITE: 301 return ("rw-"); 302 case VM_PROT_READ | VM_PROT_EXECUTE: 303 return ("r-x"); 304 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 305 return ("rwx"); 306 case VM_PROT_WRITE: 307 return ("-w-"); 308 case VM_PROT_EXECUTE: 309 return ("--x"); 310 case VM_PROT_WRITE | VM_PROT_EXECUTE: 311 return ("-wx"); 312 default: 313 return ("---"); 314 } 315} 316 317static void 318mac_cred_mmapped_drop_perms_recurse(struct thread *td, struct ucred *cred, 319 struct vm_map *map) 320{ 321 struct vm_map_entry *vme; 322 int result; 323 vm_prot_t revokeperms; 324 vm_object_t object; 325 vm_ooffset_t offset; 326 struct vnode *vp; 327 328 if (!mac_mmap_revocation) 329 return; 330 331 vm_map_lock_read(map); 332 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 333 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 334 mac_cred_mmapped_drop_perms_recurse(td, cred, 335 vme->object.sub_map); 336 continue; 337 } 338 /* 339 * Skip over entries that obviously are not shared. 340 */ 341 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 342 !vme->max_protection) 343 continue; 344 /* 345 * Drill down to the deepest backing object. 346 */ 347 offset = vme->offset; 348 object = vme->object.vm_object; 349 if (object == NULL) 350 continue; 351 while (object->backing_object != NULL) { 352 object = object->backing_object; 353 offset += object->backing_object_offset; 354 } 355 /* 356 * At the moment, vm_maps and objects aren't considered 357 * by the MAC system, so only things with backing by a 358 * normal object (read: vnodes) are checked. 359 */ 360 if (object->type != OBJT_VNODE) 361 continue; 362 vp = (struct vnode *)object->handle; 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 continue; 374 printf("pid %ld: revoking %s perms from %#lx:%ld " 375 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 376 prot2str(revokeperms), (u_long)vme->start, 377 (long)(vme->end - vme->start), 378 prot2str(vme->max_protection), prot2str(vme->protection)); 379 vm_map_lock_upgrade(map); 380 /* 381 * This is the really simple case: if a map has more 382 * max_protection than is allowed, but it's not being 383 * actually used (that is, the current protection is 384 * still allowed), we can just wipe it out and do 385 * nothing more. 386 */ 387 if ((vme->protection & revokeperms) == 0) { 388 vme->max_protection -= revokeperms; 389 } else { 390 if (revokeperms & VM_PROT_WRITE) { 391 /* 392 * In the more complicated case, flush out all 393 * pending changes to the object then turn it 394 * copy-on-write. 395 */ 396 vm_object_reference(object); 397 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 398 VM_OBJECT_LOCK(object); 399 vm_object_page_clean(object, 400 OFF_TO_IDX(offset), 401 OFF_TO_IDX(offset + vme->end - vme->start + 402 PAGE_MASK), 403 OBJPC_SYNC); 404 VM_OBJECT_UNLOCK(object); 405 VOP_UNLOCK(vp, 0, td); 406 vm_object_deallocate(object); 407 /* 408 * Why bother if there's no read permissions 409 * anymore? For the rest, we need to leave 410 * the write permissions on for COW, or 411 * remove them entirely if configured to. 412 */ 413 if (!mac_mmap_revocation_via_cow) { 414 vme->max_protection &= ~VM_PROT_WRITE; 415 vme->protection &= ~VM_PROT_WRITE; 416 } if ((revokeperms & VM_PROT_READ) == 0) 417 vme->eflags |= MAP_ENTRY_COW | 418 MAP_ENTRY_NEEDS_COPY; 419 } 420 if (revokeperms & VM_PROT_EXECUTE) { 421 vme->max_protection &= ~VM_PROT_EXECUTE; 422 vme->protection &= ~VM_PROT_EXECUTE; 423 } 424 if (revokeperms & VM_PROT_READ) { 425 vme->max_protection = 0; 426 vme->protection = 0; 427 } 428 pmap_protect(map->pmap, vme->start, vme->end, 429 vme->protection & ~revokeperms); 430 vm_map_simplify_entry(map, vme); 431 } 432 vm_map_lock_downgrade(map); 433 } 434 vm_map_unlock_read(map); 435} 436 437/* 438 * When the subject's label changes, it may require revocation of privilege 439 * to mapped objects. This can't be done on-the-fly later with a unified 440 * buffer cache. 441 */ 442void 443mac_relabel_cred(struct ucred *cred, struct label *newlabel) 444{ 445 446 MAC_PERFORM(relabel_cred, cred, newlabel); 447} 448 449int 450mac_check_cred_relabel(struct ucred *cred, struct label *newlabel) 451{ 452 int error; 453 454 MAC_CHECK(check_cred_relabel, cred, newlabel); 455 456 return (error); 457} 458 459int 460mac_check_cred_visible(struct ucred *u1, struct ucred *u2) 461{ 462 int error; 463 464 if (!mac_enforce_process) 465 return (0); 466 467 MAC_CHECK(check_cred_visible, u1, u2); 468 469 return (error); 470} 471 472int 473mac_check_proc_debug(struct ucred *cred, struct proc *proc) 474{ 475 int error; 476 477 PROC_LOCK_ASSERT(proc, MA_OWNED); 478 479 if (!mac_enforce_process) 480 return (0); 481 482 MAC_CHECK(check_proc_debug, cred, proc); 483 484 return (error); 485} 486 487int 488mac_check_proc_sched(struct ucred *cred, struct proc *proc) 489{ 490 int error; 491 492 PROC_LOCK_ASSERT(proc, MA_OWNED); 493 494 if (!mac_enforce_process) 495 return (0); 496 497 MAC_CHECK(check_proc_sched, cred, proc); 498 499 return (error); 500} 501 502int 503mac_check_proc_signal(struct ucred *cred, struct proc *proc, int signum) 504{ 505 int error; 506 507 PROC_LOCK_ASSERT(proc, MA_OWNED); 508 509 if (!mac_enforce_process) 510 return (0); 511 512 MAC_CHECK(check_proc_signal, cred, proc, signum); 513 514 return (error); 515}
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