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_kdtrace.h" 49 #include "opt_mac.h" 50 51 #include <sys/param.h> 52 #include <sys/condvar.h> 53 #include <sys/imgact.h> 54 #include <sys/kernel.h> 55 #include <sys/lock.h> 56 #include <sys/malloc.h> 57 #include <sys/mutex.h> 58 #include <sys/mac.h> 59 #include <sys/proc.h> 60 #include <sys/sbuf.h> 61 #include <sys/sdt.h> 62 #include <sys/systm.h> 63 #include <sys/vnode.h> 64 #include <sys/mount.h> 65 #include <sys/file.h> 66 #include <sys/namei.h> 67 #include <sys/sysctl.h> 68 69 #include <vm/vm.h> 70 #include <vm/pmap.h> 71 #include <vm/vm_map.h> 72 #include <vm/vm_object.h> 73 74 #include <security/mac/mac_framework.h> 75 #include <security/mac/mac_internal.h> 76 #include <security/mac/mac_policy.h> 77 78 static int mac_mmap_revocation = 1; 79 SYSCTL_INT(_security_mac, OID_AUTO, mmap_revocation, CTLFLAG_RW, 80 &mac_mmap_revocation, 0, "Revoke mmap access to files on subject " 81 "relabel"); 82 83 static int mac_mmap_revocation_via_cow = 0; 84 SYSCTL_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 static void mac_proc_vm_revoke_recurse(struct thread *td, 89 struct ucred *cred, struct vm_map *map); 90 91 static struct label * 92 mac_proc_label_alloc(void) 93 { 94 struct label *label; 95 96 label = mac_labelzone_alloc(M_WAITOK); 97 MAC_POLICY_PERFORM(proc_init_label, label); 98 return (label); 99 } 100 101 void 102 mac_proc_init(struct proc *p) 103 { 104 105 if (mac_labeled & MPC_OBJECT_PROC) 106 p->p_label = mac_proc_label_alloc(); 107 else 108 p->p_label = NULL; 109 } 110 111 static void 112 mac_proc_label_free(struct label *label) 113 { 114 115 MAC_POLICY_PERFORM_NOSLEEP(proc_destroy_label, label); 116 mac_labelzone_free(label); 117 } 118 119 void 120 mac_proc_destroy(struct proc *p) 121 { 122 123 if (p->p_label != NULL) { 124 mac_proc_label_free(p->p_label); 125 p->p_label = NULL; 126 } 127 } 128 129 void 130 mac_thread_userret(struct thread *td) 131 { 132 133 MAC_POLICY_PERFORM(thread_userret, td); 134 } 135 136 int 137 mac_execve_enter(struct image_params *imgp, struct mac *mac_p) 138 { 139 struct label *label; 140 struct mac mac; 141 char *buffer; 142 int error; 143 144 if (mac_p == NULL) 145 return (0); 146 147 if (!(mac_labeled & MPC_OBJECT_CRED)) 148 return (EINVAL); 149 150 error = copyin(mac_p, &mac, sizeof(mac)); 151 if (error) 152 return (error); 153 154 error = mac_check_structmac_consistent(&mac); 155 if (error) 156 return (error); 157 158 buffer = malloc(mac.m_buflen, M_MACTEMP, M_WAITOK); 159 error = copyinstr(mac.m_string, buffer, mac.m_buflen, NULL); 160 if (error) { 161 free(buffer, M_MACTEMP); 162 return (error); 163 } 164 165 label = mac_cred_label_alloc(); 166 error = mac_cred_internalize_label(label, buffer); 167 free(buffer, M_MACTEMP); 168 if (error) { 169 mac_cred_label_free(label); 170 return (error); 171 } 172 imgp->execlabel = label; 173 return (0); 174 } 175 176 void 177 mac_execve_exit(struct image_params *imgp) 178 { 179 if (imgp->execlabel != NULL) { 180 mac_cred_label_free(imgp->execlabel); 181 imgp->execlabel = NULL; 182 } 183 } 184 185 void 186 mac_execve_interpreter_enter(struct vnode *interpvp, 187 struct label **interpvplabel) 188 { 189 190 if (mac_labeled & MPC_OBJECT_VNODE) { 191 *interpvplabel = mac_vnode_label_alloc(); 192 mac_vnode_copy_label(interpvp->v_label, *interpvplabel); 193 } else 194 *interpvplabel = NULL; 195 } 196 197 void 198 mac_execve_interpreter_exit(struct label *interpvplabel) 199 { 200 201 if (interpvplabel != NULL) 202 mac_vnode_label_free(interpvplabel); 203 } 204 205 /* 206 * When relabeling a process, call out to the policies for the maximum 207 * permission allowed for each object type we know about in its memory space, 208 * and revoke access (in the least surprising ways we know) when necessary. 209 * The process lock is not held here. 210 */ 211 void 212 mac_proc_vm_revoke(struct thread *td) 213 { 214 struct ucred *cred; 215 216 PROC_LOCK(td->td_proc); 217 cred = crhold(td->td_proc->p_ucred); 218 PROC_UNLOCK(td->td_proc); 219 220 /* XXX freeze all other threads */ 221 mac_proc_vm_revoke_recurse(td, cred, 222 &td->td_proc->p_vmspace->vm_map); 223 /* XXX allow other threads to continue */ 224 225 crfree(cred); 226 } 227 228 static __inline const char * 229 prot2str(vm_prot_t prot) 230 { 231 232 switch (prot & VM_PROT_ALL) { 233 case VM_PROT_READ: 234 return ("r--"); 235 case VM_PROT_READ | VM_PROT_WRITE: 236 return ("rw-"); 237 case VM_PROT_READ | VM_PROT_EXECUTE: 238 return ("r-x"); 239 case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE: 240 return ("rwx"); 241 case VM_PROT_WRITE: 242 return ("-w-"); 243 case VM_PROT_EXECUTE: 244 return ("--x"); 245 case VM_PROT_WRITE | VM_PROT_EXECUTE: 246 return ("-wx"); 247 default: 248 return ("---"); 249 } 250 } 251 252 static void 253 mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred, 254 struct vm_map *map) 255 { 256 vm_map_entry_t vme; 257 int vfslocked, result; 258 vm_prot_t revokeperms; 259 vm_object_t backing_object, object; 260 vm_ooffset_t offset; 261 struct vnode *vp; 262 struct mount *mp; 263 264 if (!mac_mmap_revocation) 265 return; 266 267 vm_map_lock(map); 268 for (vme = map->header.next; vme != &map->header; vme = vme->next) { 269 if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) { 270 mac_proc_vm_revoke_recurse(td, cred, 271 vme->object.sub_map); 272 continue; 273 } 274 /* 275 * Skip over entries that obviously are not shared. 276 */ 277 if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) || 278 !vme->max_protection) 279 continue; 280 /* 281 * Drill down to the deepest backing object. 282 */ 283 offset = vme->offset; 284 object = vme->object.vm_object; 285 if (object == NULL) 286 continue; 287 VM_OBJECT_LOCK(object); 288 while ((backing_object = object->backing_object) != NULL) { 289 VM_OBJECT_LOCK(backing_object); 290 offset += object->backing_object_offset; 291 VM_OBJECT_UNLOCK(object); 292 object = backing_object; 293 } 294 VM_OBJECT_UNLOCK(object); 295 /* 296 * At the moment, vm_maps and objects aren't considered by 297 * the MAC system, so only things with backing by a normal 298 * object (read: vnodes) are checked. 299 */ 300 if (object->type != OBJT_VNODE) 301 continue; 302 vp = (struct vnode *)object->handle; 303 vfslocked = VFS_LOCK_GIANT(vp->v_mount); 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, 0); 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 VFS_UNLOCK_GIANT(vfslocked); 315 continue; 316 } 317 printf("pid %ld: revoking %s perms from %#lx:%ld " 318 "(max %s/cur %s)\n", (long)td->td_proc->p_pid, 319 prot2str(revokeperms), (u_long)vme->start, 320 (long)(vme->end - vme->start), 321 prot2str(vme->max_protection), prot2str(vme->protection)); 322 /* 323 * This is the really simple case: if a map has more 324 * max_protection than is allowed, but it's not being 325 * actually used (that is, the current protection is still 326 * allowed), we can just wipe it out and do nothing more. 327 */ 328 if ((vme->protection & revokeperms) == 0) { 329 vme->max_protection -= revokeperms; 330 } else { 331 if (revokeperms & VM_PROT_WRITE) { 332 /* 333 * In the more complicated case, flush out all 334 * pending changes to the object then turn it 335 * copy-on-write. 336 */ 337 vm_object_reference(object); 338 (void) vn_start_write(vp, &mp, V_WAIT); 339 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 340 VM_OBJECT_LOCK(object); 341 vm_object_page_clean(object, 342 OFF_TO_IDX(offset), 343 OFF_TO_IDX(offset + vme->end - vme->start + 344 PAGE_MASK), 345 OBJPC_SYNC); 346 VM_OBJECT_UNLOCK(object); 347 VOP_UNLOCK(vp, 0); 348 vn_finished_write(mp); 349 vm_object_deallocate(object); 350 /* 351 * Why bother if there's no read permissions 352 * anymore? For the rest, we need to leave 353 * the write permissions on for COW, or 354 * remove them entirely if configured to. 355 */ 356 if (!mac_mmap_revocation_via_cow) { 357 vme->max_protection &= ~VM_PROT_WRITE; 358 vme->protection &= ~VM_PROT_WRITE; 359 } if ((revokeperms & VM_PROT_READ) == 0) 360 vme->eflags |= MAP_ENTRY_COW | 361 MAP_ENTRY_NEEDS_COPY; 362 } 363 if (revokeperms & VM_PROT_EXECUTE) { 364 vme->max_protection &= ~VM_PROT_EXECUTE; 365 vme->protection &= ~VM_PROT_EXECUTE; 366 } 367 if (revokeperms & VM_PROT_READ) { 368 vme->max_protection = 0; 369 vme->protection = 0; 370 } 371 pmap_protect(map->pmap, vme->start, vme->end, 372 vme->protection & ~revokeperms); 373 vm_map_simplify_entry(map, vme); 374 } 375 VFS_UNLOCK_GIANT(vfslocked); 376 } 377 vm_map_unlock(map); 378 } 379 380 MAC_CHECK_PROBE_DEFINE2(proc_check_debug, "struct ucred *", "struct proc *"); 381 382 int 383 mac_proc_check_debug(struct ucred *cred, struct proc *p) 384 { 385 int error; 386 387 PROC_LOCK_ASSERT(p, MA_OWNED); 388 389 MAC_POLICY_CHECK_NOSLEEP(proc_check_debug, cred, p); 390 MAC_CHECK_PROBE2(proc_check_debug, error, cred, p); 391 392 return (error); 393 } 394 395 MAC_CHECK_PROBE_DEFINE2(proc_check_sched, "struct ucred *", "struct proc *"); 396 397 int 398 mac_proc_check_sched(struct ucred *cred, struct proc *p) 399 { 400 int error; 401 402 PROC_LOCK_ASSERT(p, MA_OWNED); 403 404 MAC_POLICY_CHECK_NOSLEEP(proc_check_sched, cred, p); 405 MAC_CHECK_PROBE2(proc_check_sched, error, cred, p); 406 407 return (error); 408 } 409 410 MAC_CHECK_PROBE_DEFINE3(proc_check_signal, "struct ucred *", "struct proc *", 411 "int"); 412 413 int 414 mac_proc_check_signal(struct ucred *cred, struct proc *p, int signum) 415 { 416 int error; 417 418 PROC_LOCK_ASSERT(p, MA_OWNED); 419 420 MAC_POLICY_CHECK_NOSLEEP(proc_check_signal, cred, p, signum); 421 MAC_CHECK_PROBE3(proc_check_signal, error, cred, p, signum); 422 423 return (error); 424 } 425 426 MAC_CHECK_PROBE_DEFINE2(proc_check_wait, "struct ucred *", "struct proc *"); 427 428 int 429 mac_proc_check_wait(struct ucred *cred, struct proc *p) 430 { 431 int error; 432 433 PROC_LOCK_ASSERT(p, MA_OWNED); 434 435 MAC_POLICY_CHECK_NOSLEEP(proc_check_wait, cred, p); 436 MAC_CHECK_PROBE2(proc_check_wait, error, cred, p); 437 438 return (error); 439 } 440