1 /*- 2 * ---------------------------------------------------------------------------- 3 * "THE BEER-WARE LICENSE" (Revision 42): 4 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you 5 * can do whatever you want with this stuff. If we meet some day, and you think 6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp 7 * ---------------------------------------------------------------------------- 8 */ 9 10 #include <sys/cdefs.h> 11 __FBSDID("$FreeBSD$"); 12 13 #include "opt_mac.h" 14 15 #include <sys/param.h> 16 #include <sys/types.h> 17 #include <sys/kernel.h> 18 #include <sys/systm.h> 19 #include <sys/errno.h> 20 #include <sys/sysproto.h> 21 #include <sys/mac.h> 22 #include <sys/malloc.h> 23 #include <sys/proc.h> 24 #include <sys/taskqueue.h> 25 #include <sys/jail.h> 26 #include <sys/lock.h> 27 #include <sys/mutex.h> 28 #include <sys/namei.h> 29 #include <sys/mount.h> 30 #include <sys/queue.h> 31 #include <sys/socket.h> 32 #include <sys/syscallsubr.h> 33 #include <sys/sysctl.h> 34 #include <sys/vnode.h> 35 #include <net/if.h> 36 #include <netinet/in.h> 37 38 MALLOC_DEFINE(M_PRISON, "prison", "Prison structures"); 39 40 SYSCTL_NODE(_security, OID_AUTO, jail, CTLFLAG_RW, 0, 41 "Jail rules"); 42 43 int jail_set_hostname_allowed = 1; 44 SYSCTL_INT(_security_jail, OID_AUTO, set_hostname_allowed, CTLFLAG_RW, 45 &jail_set_hostname_allowed, 0, 46 "Processes in jail can set their hostnames"); 47 48 int jail_socket_unixiproute_only = 1; 49 SYSCTL_INT(_security_jail, OID_AUTO, socket_unixiproute_only, CTLFLAG_RW, 50 &jail_socket_unixiproute_only, 0, 51 "Processes in jail are limited to creating UNIX/IPv4/route sockets only"); 52 53 int jail_sysvipc_allowed = 0; 54 SYSCTL_INT(_security_jail, OID_AUTO, sysvipc_allowed, CTLFLAG_RW, 55 &jail_sysvipc_allowed, 0, 56 "Processes in jail can use System V IPC primitives"); 57 58 static int jail_enforce_statfs = 2; 59 SYSCTL_INT(_security_jail, OID_AUTO, enforce_statfs, CTLFLAG_RW, 60 &jail_enforce_statfs, 0, 61 "Processes in jail cannot see all mounted file systems"); 62 63 int jail_allow_raw_sockets = 0; 64 SYSCTL_INT(_security_jail, OID_AUTO, allow_raw_sockets, CTLFLAG_RW, 65 &jail_allow_raw_sockets, 0, 66 "Prison root can create raw sockets"); 67 68 int jail_chflags_allowed = 0; 69 SYSCTL_INT(_security_jail, OID_AUTO, chflags_allowed, CTLFLAG_RW, 70 &jail_chflags_allowed, 0, 71 "Processes in jail can alter system file flags"); 72 73 /* allprison, lastprid, and prisoncount are protected by allprison_mtx. */ 74 struct prisonlist allprison; 75 struct mtx allprison_mtx; 76 int lastprid = 0; 77 int prisoncount = 0; 78 79 static void init_prison(void *); 80 static void prison_complete(void *context, int pending); 81 static struct prison *prison_find(int); 82 static int sysctl_jail_list(SYSCTL_HANDLER_ARGS); 83 84 static void 85 init_prison(void *data __unused) 86 { 87 88 mtx_init(&allprison_mtx, "allprison", NULL, MTX_DEF); 89 LIST_INIT(&allprison); 90 } 91 92 SYSINIT(prison, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_prison, NULL); 93 94 /* 95 * MPSAFE 96 * 97 * struct jail_args { 98 * struct jail *jail; 99 * }; 100 */ 101 int 102 jail(struct thread *td, struct jail_args *uap) 103 { 104 struct nameidata nd; 105 struct prison *pr, *tpr; 106 struct jail j; 107 struct jail_attach_args jaa; 108 int vfslocked, error, tryprid; 109 110 error = copyin(uap->jail, &j, sizeof(j)); 111 if (error) 112 return (error); 113 if (j.version != 0) 114 return (EINVAL); 115 116 MALLOC(pr, struct prison *, sizeof(*pr), M_PRISON, M_WAITOK | M_ZERO); 117 mtx_init(&pr->pr_mtx, "jail mutex", NULL, MTX_DEF); 118 pr->pr_ref = 1; 119 error = copyinstr(j.path, &pr->pr_path, sizeof(pr->pr_path), 0); 120 if (error) 121 goto e_killmtx; 122 NDINIT(&nd, LOOKUP, MPSAFE | FOLLOW | LOCKLEAF, UIO_SYSSPACE, 123 pr->pr_path, td); 124 error = namei(&nd); 125 if (error) 126 goto e_killmtx; 127 vfslocked = NDHASGIANT(&nd); 128 pr->pr_root = nd.ni_vp; 129 VOP_UNLOCK(nd.ni_vp, 0, td); 130 NDFREE(&nd, NDF_ONLY_PNBUF); 131 VFS_UNLOCK_GIANT(vfslocked); 132 error = copyinstr(j.hostname, &pr->pr_host, sizeof(pr->pr_host), 0); 133 if (error) 134 goto e_dropvnref; 135 pr->pr_ip = j.ip_number; 136 pr->pr_linux = NULL; 137 pr->pr_securelevel = securelevel; 138 139 /* Determine next pr_id and add prison to allprison list. */ 140 mtx_lock(&allprison_mtx); 141 tryprid = lastprid + 1; 142 if (tryprid == JAIL_MAX) 143 tryprid = 1; 144 next: 145 LIST_FOREACH(tpr, &allprison, pr_list) { 146 if (tpr->pr_id == tryprid) { 147 tryprid++; 148 if (tryprid == JAIL_MAX) { 149 mtx_unlock(&allprison_mtx); 150 error = EAGAIN; 151 goto e_dropvnref; 152 } 153 goto next; 154 } 155 } 156 pr->pr_id = jaa.jid = lastprid = tryprid; 157 LIST_INSERT_HEAD(&allprison, pr, pr_list); 158 prisoncount++; 159 mtx_unlock(&allprison_mtx); 160 161 error = jail_attach(td, &jaa); 162 if (error) 163 goto e_dropprref; 164 mtx_lock(&pr->pr_mtx); 165 pr->pr_ref--; 166 mtx_unlock(&pr->pr_mtx); 167 td->td_retval[0] = jaa.jid; 168 return (0); 169 e_dropprref: 170 mtx_lock(&allprison_mtx); 171 LIST_REMOVE(pr, pr_list); 172 prisoncount--; 173 mtx_unlock(&allprison_mtx); 174 e_dropvnref: 175 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 176 vrele(pr->pr_root); 177 VFS_UNLOCK_GIANT(vfslocked); 178 e_killmtx: 179 mtx_destroy(&pr->pr_mtx); 180 FREE(pr, M_PRISON); 181 return (error); 182 } 183 184 /* 185 * MPSAFE 186 * 187 * struct jail_attach_args { 188 * int jid; 189 * }; 190 */ 191 int 192 jail_attach(struct thread *td, struct jail_attach_args *uap) 193 { 194 struct proc *p; 195 struct ucred *newcred, *oldcred; 196 struct prison *pr; 197 int vfslocked, error; 198 199 /* 200 * XXX: Note that there is a slight race here if two threads 201 * in the same privileged process attempt to attach to two 202 * different jails at the same time. It is important for 203 * user processes not to do this, or they might end up with 204 * a process root from one prison, but attached to the jail 205 * of another. 206 */ 207 error = suser(td); 208 if (error) 209 return (error); 210 211 p = td->td_proc; 212 mtx_lock(&allprison_mtx); 213 pr = prison_find(uap->jid); 214 if (pr == NULL) { 215 mtx_unlock(&allprison_mtx); 216 return (EINVAL); 217 } 218 pr->pr_ref++; 219 mtx_unlock(&pr->pr_mtx); 220 mtx_unlock(&allprison_mtx); 221 222 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 223 vn_lock(pr->pr_root, LK_EXCLUSIVE | LK_RETRY, td); 224 if ((error = change_dir(pr->pr_root, td)) != 0) 225 goto e_unlock; 226 #ifdef MAC 227 if ((error = mac_check_vnode_chroot(td->td_ucred, pr->pr_root))) 228 goto e_unlock; 229 #endif 230 VOP_UNLOCK(pr->pr_root, 0, td); 231 change_root(pr->pr_root, td); 232 VFS_UNLOCK_GIANT(vfslocked); 233 234 newcred = crget(); 235 PROC_LOCK(p); 236 oldcred = p->p_ucred; 237 setsugid(p); 238 crcopy(newcred, oldcred); 239 newcred->cr_prison = pr; 240 p->p_ucred = newcred; 241 PROC_UNLOCK(p); 242 crfree(oldcred); 243 return (0); 244 e_unlock: 245 VOP_UNLOCK(pr->pr_root, 0, td); 246 VFS_UNLOCK_GIANT(vfslocked); 247 mtx_lock(&pr->pr_mtx); 248 pr->pr_ref--; 249 mtx_unlock(&pr->pr_mtx); 250 return (error); 251 } 252 253 /* 254 * Returns a locked prison instance, or NULL on failure. 255 */ 256 static struct prison * 257 prison_find(int prid) 258 { 259 struct prison *pr; 260 261 mtx_assert(&allprison_mtx, MA_OWNED); 262 LIST_FOREACH(pr, &allprison, pr_list) { 263 if (pr->pr_id == prid) { 264 mtx_lock(&pr->pr_mtx); 265 return (pr); 266 } 267 } 268 return (NULL); 269 } 270 271 void 272 prison_free(struct prison *pr) 273 { 274 275 mtx_lock(&allprison_mtx); 276 mtx_lock(&pr->pr_mtx); 277 pr->pr_ref--; 278 if (pr->pr_ref == 0) { 279 LIST_REMOVE(pr, pr_list); 280 mtx_unlock(&pr->pr_mtx); 281 prisoncount--; 282 mtx_unlock(&allprison_mtx); 283 284 TASK_INIT(&pr->pr_task, 0, prison_complete, pr); 285 taskqueue_enqueue(taskqueue_thread, &pr->pr_task); 286 return; 287 } 288 mtx_unlock(&pr->pr_mtx); 289 mtx_unlock(&allprison_mtx); 290 } 291 292 static void 293 prison_complete(void *context, int pending) 294 { 295 struct prison *pr; 296 int vfslocked; 297 298 pr = (struct prison *)context; 299 300 vfslocked = VFS_LOCK_GIANT(pr->pr_root->v_mount); 301 vrele(pr->pr_root); 302 VFS_UNLOCK_GIANT(vfslocked); 303 304 mtx_destroy(&pr->pr_mtx); 305 if (pr->pr_linux != NULL) 306 FREE(pr->pr_linux, M_PRISON); 307 FREE(pr, M_PRISON); 308 } 309 310 void 311 prison_hold(struct prison *pr) 312 { 313 314 mtx_lock(&pr->pr_mtx); 315 pr->pr_ref++; 316 mtx_unlock(&pr->pr_mtx); 317 } 318 319 u_int32_t 320 prison_getip(struct ucred *cred) 321 { 322 323 return (cred->cr_prison->pr_ip); 324 } 325 326 int 327 prison_ip(struct ucred *cred, int flag, u_int32_t *ip) 328 { 329 u_int32_t tmp; 330 331 if (!jailed(cred)) 332 return (0); 333 if (flag) 334 tmp = *ip; 335 else 336 tmp = ntohl(*ip); 337 if (tmp == INADDR_ANY) { 338 if (flag) 339 *ip = cred->cr_prison->pr_ip; 340 else 341 *ip = htonl(cred->cr_prison->pr_ip); 342 return (0); 343 } 344 if (tmp == INADDR_LOOPBACK) { 345 if (flag) 346 *ip = cred->cr_prison->pr_ip; 347 else 348 *ip = htonl(cred->cr_prison->pr_ip); 349 return (0); 350 } 351 if (cred->cr_prison->pr_ip != tmp) 352 return (1); 353 return (0); 354 } 355 356 void 357 prison_remote_ip(struct ucred *cred, int flag, u_int32_t *ip) 358 { 359 u_int32_t tmp; 360 361 if (!jailed(cred)) 362 return; 363 if (flag) 364 tmp = *ip; 365 else 366 tmp = ntohl(*ip); 367 if (tmp == INADDR_LOOPBACK) { 368 if (flag) 369 *ip = cred->cr_prison->pr_ip; 370 else 371 *ip = htonl(cred->cr_prison->pr_ip); 372 return; 373 } 374 return; 375 } 376 377 int 378 prison_if(struct ucred *cred, struct sockaddr *sa) 379 { 380 struct sockaddr_in *sai; 381 int ok; 382 383 sai = (struct sockaddr_in *)sa; 384 if ((sai->sin_family != AF_INET) && jail_socket_unixiproute_only) 385 ok = 1; 386 else if (sai->sin_family != AF_INET) 387 ok = 0; 388 else if (cred->cr_prison->pr_ip != ntohl(sai->sin_addr.s_addr)) 389 ok = 1; 390 else 391 ok = 0; 392 return (ok); 393 } 394 395 /* 396 * Return 0 if jails permit p1 to frob p2, otherwise ESRCH. 397 */ 398 int 399 prison_check(struct ucred *cred1, struct ucred *cred2) 400 { 401 402 if (jailed(cred1)) { 403 if (!jailed(cred2)) 404 return (ESRCH); 405 if (cred2->cr_prison != cred1->cr_prison) 406 return (ESRCH); 407 } 408 409 return (0); 410 } 411 412 /* 413 * Return 1 if the passed credential is in a jail, otherwise 0. 414 */ 415 int 416 jailed(struct ucred *cred) 417 { 418 419 return (cred->cr_prison != NULL); 420 } 421 422 /* 423 * Return the correct hostname for the passed credential. 424 */ 425 void 426 getcredhostname(struct ucred *cred, char *buf, size_t size) 427 { 428 429 if (jailed(cred)) { 430 mtx_lock(&cred->cr_prison->pr_mtx); 431 strlcpy(buf, cred->cr_prison->pr_host, size); 432 mtx_unlock(&cred->cr_prison->pr_mtx); 433 } else 434 strlcpy(buf, hostname, size); 435 } 436 437 /* 438 * Determine whether the subject represented by cred can "see" 439 * status of a mount point. 440 * Returns: 0 for permitted, ENOENT otherwise. 441 * XXX: This function should be called cr_canseemount() and should be 442 * placed in kern_prot.c. 443 */ 444 int 445 prison_canseemount(struct ucred *cred, struct mount *mp) 446 { 447 struct prison *pr; 448 struct statfs *sp; 449 size_t len; 450 451 if (!jailed(cred) || jail_enforce_statfs == 0) 452 return (0); 453 pr = cred->cr_prison; 454 if (pr->pr_root->v_mount == mp) 455 return (0); 456 if (jail_enforce_statfs == 2) 457 return (ENOENT); 458 /* 459 * If jail's chroot directory is set to "/" we should be able to see 460 * all mount-points from inside a jail. 461 * This is ugly check, but this is the only situation when jail's 462 * directory ends with '/'. 463 */ 464 if (strcmp(pr->pr_path, "/") == 0) 465 return (0); 466 len = strlen(pr->pr_path); 467 sp = &mp->mnt_stat; 468 if (strncmp(pr->pr_path, sp->f_mntonname, len) != 0) 469 return (ENOENT); 470 /* 471 * Be sure that we don't have situation where jail's root directory 472 * is "/some/path" and mount point is "/some/pathpath". 473 */ 474 if (sp->f_mntonname[len] != '\0' && sp->f_mntonname[len] != '/') 475 return (ENOENT); 476 return (0); 477 } 478 479 void 480 prison_enforce_statfs(struct ucred *cred, struct mount *mp, struct statfs *sp) 481 { 482 char jpath[MAXPATHLEN]; 483 struct prison *pr; 484 size_t len; 485 486 if (!jailed(cred) || jail_enforce_statfs == 0) 487 return; 488 pr = cred->cr_prison; 489 if (prison_canseemount(cred, mp) != 0) { 490 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 491 strlcpy(sp->f_mntonname, "[restricted]", 492 sizeof(sp->f_mntonname)); 493 return; 494 } 495 if (pr->pr_root->v_mount == mp) { 496 /* 497 * Clear current buffer data, so we are sure nothing from 498 * the valid path left there. 499 */ 500 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 501 *sp->f_mntonname = '/'; 502 return; 503 } 504 /* 505 * If jail's chroot directory is set to "/" we should be able to see 506 * all mount-points from inside a jail. 507 */ 508 if (strcmp(pr->pr_path, "/") == 0) 509 return; 510 len = strlen(pr->pr_path); 511 strlcpy(jpath, sp->f_mntonname + len, sizeof(jpath)); 512 /* 513 * Clear current buffer data, so we are sure nothing from 514 * the valid path left there. 515 */ 516 bzero(sp->f_mntonname, sizeof(sp->f_mntonname)); 517 if (*jpath == '\0') { 518 /* Should never happen. */ 519 *sp->f_mntonname = '/'; 520 } else { 521 strlcpy(sp->f_mntonname, jpath, sizeof(sp->f_mntonname)); 522 } 523 } 524 525 static int 526 sysctl_jail_list(SYSCTL_HANDLER_ARGS) 527 { 528 struct xprison *xp, *sxp; 529 struct prison *pr; 530 int count, error; 531 532 if (jailed(req->td->td_ucred)) 533 return (0); 534 retry: 535 mtx_lock(&allprison_mtx); 536 count = prisoncount; 537 mtx_unlock(&allprison_mtx); 538 539 if (count == 0) 540 return (0); 541 542 sxp = xp = malloc(sizeof(*xp) * count, M_TEMP, M_WAITOK | M_ZERO); 543 mtx_lock(&allprison_mtx); 544 if (count != prisoncount) { 545 mtx_unlock(&allprison_mtx); 546 free(sxp, M_TEMP); 547 goto retry; 548 } 549 550 LIST_FOREACH(pr, &allprison, pr_list) { 551 mtx_lock(&pr->pr_mtx); 552 xp->pr_version = XPRISON_VERSION; 553 xp->pr_id = pr->pr_id; 554 strlcpy(xp->pr_path, pr->pr_path, sizeof(xp->pr_path)); 555 strlcpy(xp->pr_host, pr->pr_host, sizeof(xp->pr_host)); 556 xp->pr_ip = pr->pr_ip; 557 mtx_unlock(&pr->pr_mtx); 558 xp++; 559 } 560 mtx_unlock(&allprison_mtx); 561 562 error = SYSCTL_OUT(req, sxp, sizeof(*sxp) * count); 563 free(sxp, M_TEMP); 564 if (error) 565 return (error); 566 return (0); 567 } 568 569 SYSCTL_OID(_security_jail, OID_AUTO, list, CTLTYPE_STRUCT | CTLFLAG_RD, 570 NULL, 0, sysctl_jail_list, "S", "List of active jails"); 571 572 static int 573 sysctl_jail_jailed(SYSCTL_HANDLER_ARGS) 574 { 575 int error, injail; 576 577 injail = jailed(req->td->td_ucred); 578 error = SYSCTL_OUT(req, &injail, sizeof(injail)); 579 580 return (error); 581 } 582 SYSCTL_PROC(_security_jail, OID_AUTO, jailed, CTLTYPE_INT | CTLFLAG_RD, 583 NULL, 0, sysctl_jail_jailed, "I", "Process in jail?"); 584