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 #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/mac.h> 55 #include <sys/proc.h> 56 #include <sys/rwlock.h> 57 #include <sys/sbuf.h> 58 #include <sys/sdt.h> 59 #include <sys/systm.h> 60 #include <sys/vnode.h> 61 #include <sys/mount.h> 62 #include <sys/file.h> 63 #include <sys/namei.h> 64 #include <sys/sysctl.h> 65 66 #include <vm/vm.h> 67 #include <vm/pmap.h> 68 #include <vm/vm_map.h> 69 #include <vm/vm_object.h> 70 71 #include <security/mac/mac_framework.h> 72 #include <security/mac/mac_internal.h> 73 #include <security/mac/mac_policy.h> 74 75 static int mac_mmap_revocation = 1; 76 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 77 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 78 "relabel"); 79 80 static int mac_mmap_revocation_via_cow = 0; 81 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation_via_cow, CTLFLAG_RW, 82 &mac_mmap_revocation_via_cow, 0, "Revoke mmap access to files via " 83 "copy-on-write semantics, or by removing all write access"); 84 85 static void mac_proc_vm_revoke_recurse(struct thread *td, 86 struct ucred *cred, struct vm_map *map); 87 88 static struct label * 89 mac_proc_label_alloc(void) 90 { 91 struct label *label; 92 93 label = mac_labelzone_alloc(M_WAITOK); 94 MAC_POLICY_PERFORM(proc_init_label, label); 95 return (label); 96 } 97 98 void 99 mac_proc_init(struct proc *p) 100 { 101 102 if (mac_labeled & MPC_OBJECT_PROC) 103 p->p_label = mac_proc_label_alloc(); 104 else 105 p->p_label = NULL; 106 } 107 108 static void 109 mac_proc_label_free(struct label *label) 110 { 111 112 MAC_POLICY_PERFORM_NOSLEEP(proc_destroy_label, label); 113 mac_labelzone_free(label); 114 } 115 116 void 117 mac_proc_destroy(struct proc *p) 118 { 119 120 if (p->p_label != NULL) { 121 mac_proc_label_free(p->p_label); 122 p->p_label = NULL; 123 } 124 } 125 126 void 127 mac_thread_userret(struct thread *td) 128 { 129 130 MAC_POLICY_PERFORM(thread_userret, td); 131 } 132 133 int 134 mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 135 { 136 struct label *label; 137 struct mac mac; 138 char *buffer; 139 int error; 140 141 if (mac_p == NULL) 142 return (0); 143 144 if (!(mac_labeled & MPC_OBJECT_CRED)) 145 return (EINVAL); 146 147 error = copyin(mac_p, &mac, sizeof(mac)); 148 if (error) 149 return (error); 150 151 error = mac_check_structmac_consistent(&mac); 152 if (error) 153 return (error); 154 155 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 156 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 157 if (error) { 158 free(buffer, M_MACTEMP); 159 return (error); 160 } 161 162 label = mac_cred_label_alloc(); 163 error = mac_cred_internalize_label(label, buffer); 164 free(buffer, M_MACTEMP); 165 if (error) { 166 mac_cred_label_free(label); 167 return (error); 168 } 169 imgp->execlabel = label; 170 return (0); 171 } 172 173 void 174 mac_execve_exit(struct image_params *imgp) 175 { 176 if (imgp->execlabel != NULL) { 177 mac_cred_label_free(imgp->execlabel); 178 imgp->execlabel = NULL; 179 } 180 } 181 182 void 183 mac_execve_interpreter_enter(struct vnode *interpvp, 184 struct label **interpvplabel) 185 { 186 187 if (mac_labeled & MPC_OBJECT_VNODE) { 188 *interpvplabel = mac_vnode_label_alloc(); 189 mac_vnode_copy_label(interpvp->v_label, *interpvplabel); 190 } else 191 *interpvplabel = NULL; 192 } 193 194 void 195 mac_execve_interpreter_exit(struct label *interpvplabel) 196 { 197 198 if (interpvplabel != NULL) 199 mac_vnode_label_free(interpvplabel); 200 } 201 202 /* 203 * When relabeling a process, call out to the policies for the maximum 204 * permission allowed for each object type we know about in its memory space, 205 * and revoke access (in the least surprising ways we know) when necessary. 206 * The process lock is not held here. 207 */ 208 void 209 mac_proc_vm_revoke(struct thread *td) 210 { 211 struct ucred *cred; 212 213 PROC_LOCK(td->td_proc); 214 cred = crhold(td->td_proc->p_ucred); 215 PROC_UNLOCK(td->td_proc); 216 217 /* XXX freeze all other threads */ 218 mac_proc_vm_revoke_recurse(td, cred, 219 &td->td_proc->p_vmspace->vm_map); 220 /* XXX allow other threads to continue */ 221 222 crfree(cred); 223 } 224 225 static __inline const char * 226 prot2str(vm_prot_t prot) 227 { 228 229 switch (prot & VM_PROT_ALL) { 230 case VM_PROT_READ: 231 return ("r--"); 232 case VM_PROT_READ | VM_PROT_WRITE: 233 return ("rw-"); 234 case VM_PROT_READ | VM_PROT_EXECUTE: 235 return ("r-x"); 236 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 237 return ("rwx"); 238 case VM_PROT_WRITE: 239 return ("-w-"); 240 case VM_PROT_EXECUTE: 241 return ("--x"); 242 case VM_PROT_WRITE | VM_PROT_EXECUTE: 243 return ("-wx"); 244 default: 245 return ("---"); 246 } 247 } 248 249 static void 250 mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred, 251 struct vm_map *map) 252 { 253 vm_map_entry_t prev, vme; 254 int result; 255 vm_prot_t revokeperms; 256 vm_object_t backing_object, object; 257 vm_ooffset_t offset; 258 struct vnode *vp; 259 struct mount *mp; 260 261 if (!mac_mmap_revocation) 262 return; 263 264 prev = &map->header; 265 vm_map_lock(map); 266 for (vme = vm_map_entry_first(map); vme != &map->header; 267 prev = vme, vme = vm_map_entry_succ(prev)) { 268 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 269 mac_proc_vm_revoke_recurse(td, cred, 270 vme->object.sub_map); 271 continue; 272 } 273 /* 274 * Skip over entries that obviously are not shared. 275 */ 276 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 277 !vme->max_protection) 278 continue; 279 /* 280 * Drill down to the deepest backing object. 281 */ 282 offset = vme->offset; 283 object = vme->object.vm_object; 284 if (object == NULL) 285 continue; 286 VM_OBJECT_RLOCK(object); 287 while ((backing_object = object->backing_object) != NULL) { 288 VM_OBJECT_RLOCK(backing_object); 289 offset += object->backing_object_offset; 290 VM_OBJECT_RUNLOCK(object); 291 object = backing_object; 292 } 293 VM_OBJECT_RUNLOCK(object); 294 /* 295 * At the moment, vm_maps and objects aren't considered by 296 * the MAC system, so only things with backing by a normal 297 * object (read: vnodes) are checked. 298 */ 299 if (object->type != OBJT_VNODE) 300 continue; 301 vp = (struct vnode *)object->handle; 302 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 303 result = vme->max_protection; 304 mac_vnode_check_mmap_downgrade(cred, vp, &result); 305 VOP_UNLOCK(vp); 306 /* 307 * Find out what maximum protection we may be allowing now 308 * but a policy needs to get removed. 309 */ 310 revokeperms = vme->max_protection & ~result; 311 if (!revokeperms) 312 continue; 313 printf("pid %ld: revoking %s perms from %#lx:%ld " 314 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 315 prot2str(revokeperms), (u_long)vme->start, 316 (long)(vme->end - vme->start), 317 prot2str(vme->max_protection), prot2str(vme->protection)); 318 /* 319 * This is the really simple case: if a map has more 320 * max_protection than is allowed, but it's not being 321 * actually used (that is, the current protection is still 322 * allowed), we can just wipe it out and do nothing more. 323 */ 324 if ((vme->protection & revokeperms) == 0) { 325 vme->max_protection -= revokeperms; 326 } else { 327 if (revokeperms & VM_PROT_WRITE) { 328 /* 329 * In the more complicated case, flush out all 330 * pending changes to the object then turn it 331 * copy-on-write. 332 */ 333 vm_object_reference(object); 334 (void) vn_start_write(vp, &mp, V_WAIT); 335 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 336 VM_OBJECT_WLOCK(object); 337 vm_object_page_clean(object, offset, offset + 338 vme->end - vme->start, OBJPC_SYNC); 339 VM_OBJECT_WUNLOCK(object); 340 VOP_UNLOCK(vp); 341 vn_finished_write(mp); 342 vm_object_deallocate(object); 343 /* 344 * Why bother if there's no read permissions 345 * anymore? For the rest, we need to leave 346 * the write permissions on for COW, or 347 * remove them entirely if configured to. 348 */ 349 if (!mac_mmap_revocation_via_cow) { 350 vme->max_protection &= ~VM_PROT_WRITE; 351 vme->protection &= ~VM_PROT_WRITE; 352 } if ((revokeperms & VM_PROT_READ) == 0) 353 vme->eflags |= MAP_ENTRY_COW | 354 MAP_ENTRY_NEEDS_COPY; 355 } 356 if (revokeperms & VM_PROT_EXECUTE) { 357 vme->max_protection &= ~VM_PROT_EXECUTE; 358 vme->protection &= ~VM_PROT_EXECUTE; 359 } 360 if (revokeperms & VM_PROT_READ) { 361 vme->max_protection = 0; 362 vme->protection = 0; 363 } 364 pmap_protect(map->pmap, vme->start, vme->end, 365 vme->protection & ~revokeperms); 366 vm_map_try_merge_entries(map, prev, vme); 367 } 368 } 369 vm_map_unlock(map); 370 } 371 372 MAC_CHECK_PROBE_DEFINE2(proc_check_debug, "struct ucred *", "struct proc *"); 373 374 int 375 mac_proc_check_debug(struct ucred *cred, struct proc *p) 376 { 377 int error; 378 379 PROC_LOCK_ASSERT(p, MA_OWNED); 380 381 MAC_POLICY_CHECK_NOSLEEP(proc_check_debug, cred, p); 382 MAC_CHECK_PROBE2(proc_check_debug, error, cred, p); 383 384 return (error); 385 } 386 387 MAC_CHECK_PROBE_DEFINE2(proc_check_sched, "struct ucred *", "struct proc *"); 388 389 int 390 mac_proc_check_sched(struct ucred *cred, struct proc *p) 391 { 392 int error; 393 394 PROC_LOCK_ASSERT(p, MA_OWNED); 395 396 MAC_POLICY_CHECK_NOSLEEP(proc_check_sched, cred, p); 397 MAC_CHECK_PROBE2(proc_check_sched, error, cred, p); 398 399 return (error); 400 } 401 402 MAC_CHECK_PROBE_DEFINE3(proc_check_signal, "struct ucred *", "struct proc *", 403 "int"); 404 405 int 406 mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum) 407 { 408 int error; 409 410 PROC_LOCK_ASSERT(p, MA_OWNED); 411 412 MAC_POLICY_CHECK_NOSLEEP(proc_check_signal, cred, p, signum); 413 MAC_CHECK_PROBE3(proc_check_signal, error, cred, p, signum); 414 415 return (error); 416 } 417 418 MAC_CHECK_PROBE_DEFINE2(proc_check_wait, "struct ucred *", "struct proc *"); 419 420 int 421 mac_proc_check_wait(struct ucred *cred, struct proc *p) 422 { 423 int error; 424 425 PROC_LOCK_ASSERT(p, MA_OWNED); 426 427 MAC_POLICY_CHECK_NOSLEEP(proc_check_wait, cred, p); 428 MAC_CHECK_PROBE2(proc_check_wait, error, cred, p); 429 430 return (error); 431 } 432