1 /*- 2 * Copyright (c) 1999-2002, 2008-2009 Robert N. M. Watson 3 * Copyright (c) 2001 Ilmar S. Habibulin 4 * Copyright (c) 2001-2003 Networks Associates Technology, Inc. 5 * Copyright (c) 2006 SPARTA, Inc. 6 * Copyright (c) 2008 Apple Inc. 7 * All rights reserved. 8 * 9 * This software was developed by Robert Watson and Ilmar Habibulin for the 10 * TrustedBSD Project. 11 * 12 * This software was developed for the FreeBSD Project in part by Network 13 * Associates Laboratories, the Security Research Division of Network 14 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 15 * as part of the DARPA CHATS research program. 16 * 17 * This software was enhanced by SPARTA ISSO under SPAWAR contract 18 * N66001-04-C-6019 ("SEFOS"). 19 * 20 * This software was developed at the University of Cambridge Computer 21 * Laboratory with support from a grant from Google, Inc. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the above copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include "opt_mac.h" 49 50 #include <sys/param.h> 51 #include <sys/condvar.h> 52 #include <sys/imgact.h> 53 #include <sys/kernel.h> 54 #include <sys/lock.h> 55 #include <sys/malloc.h> 56 #include <sys/mac.h> 57 #include <sys/proc.h> 58 #include <sys/rwlock.h> 59 #include <sys/sbuf.h> 60 #include <sys/sdt.h> 61 #include <sys/systm.h> 62 #include <sys/vnode.h> 63 #include <sys/mount.h> 64 #include <sys/file.h> 65 #include <sys/namei.h> 66 #include <sys/sysctl.h> 67 68 #include <vm/vm.h> 69 #include <vm/pmap.h> 70 #include <vm/vm_map.h> 71 #include <vm/vm_object.h> 72 73 #include <security/mac/mac_framework.h> 74 #include <security/mac/mac_internal.h> 75 #include <security/mac/mac_policy.h> 76 77 static int mac_mmap_revocation = 1; 78 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 79 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 80 "relabel"); 81 82 static int mac_mmap_revocation_via_cow = 0; 83 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW, 84 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via " 85 "copy-on-write semantics, or by removing all write access"); 86 87 static void mac_proc_vm_revoke_recurse(struct thread *td, 88 struct ucred *cred, struct vm_map *map); 89 90 static struct label * 91 mac_proc_label_alloc(void) 92 { 93 struct label *label; 94 95 label = mac_labelzone_alloc(M_WAITOK); 96 MAC_POLICY_PERFORM(proc_init_label, label); 97 return (label); 98 } 99 100 void 101 mac_proc_init(struct proc *p) 102 { 103 104 if (mac_labeled & MPC_OBJECT_PROC) 105 p->p_label = mac_proc_label_alloc(); 106 else 107 p->p_label = NULL; 108 } 109 110 static void 111 mac_proc_label_free(struct label *label) 112 { 113 114 MAC_POLICY_PERFORM_NOSLEEP(proc_destroy_label, label); 115 mac_labelzone_free(label); 116 } 117 118 void 119 mac_proc_destroy(struct proc *p) 120 { 121 122 if (p->p_label != NULL) { 123 mac_proc_label_free(p->p_label); 124 p->p_label = NULL; 125 } 126 } 127 128 void 129 mac_thread_userret(struct thread *td) 130 { 131 132 MAC_POLICY_PERFORM(thread_userret, td); 133 } 134 135 int 136 mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 137 { 138 struct label *label; 139 struct mac mac; 140 char *buffer; 141 int error; 142 143 if (mac_p == NULL) 144 return (0); 145 146 if (!(mac_labeled & MPC_OBJECT_CRED)) 147 return (EINVAL); 148 149 error = copyin(mac_p, &mac, sizeof(mac)); 150 if (error) 151 return (error); 152 153 error = mac_check_structmac_consistent(&mac); 154 if (error) 155 return (error); 156 157 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 158 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 159 if (error) { 160 free(buffer, M_MACTEMP); 161 return (error); 162 } 163 164 label = mac_cred_label_alloc(); 165 error = mac_cred_internalize_label(label, buffer); 166 free(buffer, M_MACTEMP); 167 if (error) { 168 mac_cred_label_free(label); 169 return (error); 170 } 171 imgp->execlabel = label; 172 return (0); 173 } 174 175 void 176 mac_execve_exit(struct image_params *imgp) 177 { 178 if (imgp->execlabel != NULL) { 179 mac_cred_label_free(imgp->execlabel); 180 imgp->execlabel = NULL; 181 } 182 } 183 184 void 185 mac_execve_interpreter_enter(struct vnode *interpvp, 186 struct label **interpvplabel) 187 { 188 189 if (mac_labeled & MPC_OBJECT_VNODE) { 190 *interpvplabel = mac_vnode_label_alloc(); 191 mac_vnode_copy_label(interpvp->v_label, *interpvplabel); 192 } else 193 *interpvplabel = NULL; 194 } 195 196 void 197 mac_execve_interpreter_exit(struct label *interpvplabel) 198 { 199 200 if (interpvplabel != NULL) 201 mac_vnode_label_free(interpvplabel); 202 } 203 204 /* 205 * When relabeling a process, call out to the policies for the maximum 206 * permission allowed for each object type we know about in its memory space, 207 * and revoke access (in the least surprising ways we know) when necessary. 208 * The process lock is not held here. 209 */ 210 void 211 mac_proc_vm_revoke(struct thread *td) 212 { 213 struct ucred *cred; 214 215 PROC_LOCK(td->td_proc); 216 cred = crhold(td->td_proc->p_ucred); 217 PROC_UNLOCK(td->td_proc); 218 219 /* XXX freeze all other threads */ 220 mac_proc_vm_revoke_recurse(td, cred, 221 &td->td_proc->p_vmspace->vm_map); 222 /* XXX allow other threads to continue */ 223 224 crfree(cred); 225 } 226 227 static __inline const char * 228 prot2str(vm_prot_t prot) 229 { 230 231 switch (prot & VM_PROT_ALL) { 232 case VM_PROT_READ: 233 return ("r--"); 234 case VM_PROT_READ | VM_PROT_WRITE: 235 return ("rw-"); 236 case VM_PROT_READ | VM_PROT_EXECUTE: 237 return ("r-x"); 238 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 239 return ("rwx"); 240 case VM_PROT_WRITE: 241 return ("-w-"); 242 case VM_PROT_EXECUTE: 243 return ("--x"); 244 case VM_PROT_WRITE | VM_PROT_EXECUTE: 245 return ("-wx"); 246 default: 247 return ("---"); 248 } 249 } 250 251 static void 252 mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred, 253 struct vm_map *map) 254 { 255 vm_map_entry_t prev, vme; 256 int result; 257 vm_prot_t revokeperms; 258 vm_object_t backing_object, object; 259 vm_ooffset_t offset; 260 struct vnode *vp; 261 struct mount *mp; 262 263 if (!mac_mmap_revocation) 264 return; 265 266 prev = &map->header; 267 vm_map_lock(map); 268 for (vme = vm_map_entry_first(map); vme != &map->header; 269 prev = vme, vme = vm_map_entry_succ(prev)) { 270 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 271 mac_proc_vm_revoke_recurse(td, cred, 272 vme->object.sub_map); 273 continue; 274 } 275 /* 276 * Skip over entries that obviously are not shared. 277 */ 278 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 279 !vme->max_protection) 280 continue; 281 /* 282 * Drill down to the deepest backing object. 283 */ 284 offset = vme->offset; 285 object = vme->object.vm_object; 286 if (object == NULL) 287 continue; 288 VM_OBJECT_RLOCK(object); 289 while ((backing_object = object->backing_object) != NULL) { 290 VM_OBJECT_RLOCK(backing_object); 291 offset += object->backing_object_offset; 292 VM_OBJECT_RUNLOCK(object); 293 object = backing_object; 294 } 295 VM_OBJECT_RUNLOCK(object); 296 /* 297 * At the moment, vm_maps and objects aren't considered by 298 * the MAC system, so only things with backing by a normal 299 * object (read: vnodes) are checked. 300 */ 301 if (object->type != OBJT_VNODE) 302 continue; 303 vp = (struct vnode *)object->handle; 304 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 305 result = vme->max_protection; 306 mac_vnode_check_mmap_downgrade(cred, vp, &result); 307 VOP_UNLOCK(vp); 308 /* 309 * Find out what maximum protection we may be allowing now 310 * but a policy needs to get removed. 311 */ 312 revokeperms = vme->max_protection & ~result; 313 if (!revokeperms) 314 continue; 315 printf("pid %ld: revoking %s perms from %#lx:%ld " 316 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 317 prot2str(revokeperms), (u_long)vme->start, 318 (long)(vme->end - vme->start), 319 prot2str(vme->max_protection), prot2str(vme->protection)); 320 /* 321 * This is the really simple case: if a map has more 322 * max_protection than is allowed, but it's not being 323 * actually used (that is, the current protection is still 324 * allowed), we can just wipe it out and do nothing more. 325 */ 326 if ((vme->protection & revokeperms) == 0) { 327 vme->max_protection -= revokeperms; 328 } else { 329 if (revokeperms & VM_PROT_WRITE) { 330 /* 331 * In the more complicated case, flush out all 332 * pending changes to the object then turn it 333 * copy-on-write. 334 */ 335 vm_object_reference(object); 336 (void) vn_start_write(vp, &mp, V_WAIT); 337 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 338 VM_OBJECT_WLOCK(object); 339 vm_object_page_clean(object, offset, offset + 340 vme->end - vme->start, OBJPC_SYNC); 341 VM_OBJECT_WUNLOCK(object); 342 VOP_UNLOCK(vp); 343 vn_finished_write(mp); 344 vm_object_deallocate(object); 345 /* 346 * Why bother if there's no read permissions 347 * anymore? For the rest, we need to leave 348 * the write permissions on for COW, or 349 * remove them entirely if configured to. 350 */ 351 if (!mac_mmap_revocation_via_cow) { 352 vme->max_protection &= ~VM_PROT_WRITE; 353 vme->protection &= ~VM_PROT_WRITE; 354 } if ((revokeperms & VM_PROT_READ) == 0) 355 vme->eflags |= MAP_ENTRY_COW | 356 MAP_ENTRY_NEEDS_COPY; 357 } 358 if (revokeperms & VM_PROT_EXECUTE) { 359 vme->max_protection &= ~VM_PROT_EXECUTE; 360 vme->protection &= ~VM_PROT_EXECUTE; 361 } 362 if (revokeperms & VM_PROT_READ) { 363 vme->max_protection = 0; 364 vme->protection = 0; 365 } 366 pmap_protect(map->pmap, vme->start, vme->end, 367 vme->protection & ~revokeperms); 368 vm_map_try_merge_entries(map, prev, vme); 369 } 370 } 371 vm_map_unlock(map); 372 } 373 374 MAC_CHECK_PROBE_DEFINE2(proc_check_debug, "struct ucred *", "struct proc *"); 375 376 int 377 mac_proc_check_debug(struct ucred *cred, struct proc *p) 378 { 379 int error; 380 381 PROC_LOCK_ASSERT(p, MA_OWNED); 382 383 MAC_POLICY_CHECK_NOSLEEP(proc_check_debug, cred, p); 384 MAC_CHECK_PROBE2(proc_check_debug, error, cred, p); 385 386 return (error); 387 } 388 389 MAC_CHECK_PROBE_DEFINE2(proc_check_sched, "struct ucred *", "struct proc *"); 390 391 int 392 mac_proc_check_sched(struct ucred *cred, struct proc *p) 393 { 394 int error; 395 396 PROC_LOCK_ASSERT(p, MA_OWNED); 397 398 MAC_POLICY_CHECK_NOSLEEP(proc_check_sched, cred, p); 399 MAC_CHECK_PROBE2(proc_check_sched, error, cred, p); 400 401 return (error); 402 } 403 404 MAC_CHECK_PROBE_DEFINE3(proc_check_signal, "struct ucred *", "struct proc *", 405 "int"); 406 407 int 408 mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum) 409 { 410 int error; 411 412 PROC_LOCK_ASSERT(p, MA_OWNED); 413 414 MAC_POLICY_CHECK_NOSLEEP(proc_check_signal, cred, p, signum); 415 MAC_CHECK_PROBE3(proc_check_signal, error, cred, p, signum); 416 417 return (error); 418 } 419 420 MAC_CHECK_PROBE_DEFINE2(proc_check_wait, "struct ucred *", "struct proc *"); 421 422 int 423 mac_proc_check_wait(struct ucred *cred, struct proc *p) 424 { 425 int error; 426 427 PROC_LOCK_ASSERT(p, MA_OWNED); 428 429 MAC_POLICY_CHECK_NOSLEEP(proc_check_wait, cred, p); 430 MAC_CHECK_PROBE2(proc_check_wait, error, cred, p); 431 432 return (error); 433 } 434